JP2793129B2 - Injection molding method and injection molding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an injection molding method and an injection molding apparatus, and more particularly to an injection molding method and an injection molding apparatus suitable for injection molding of an optical element such as a plastic lens.

[0002]

2. Description of the Related Art In recent years, various injection moldings utilizing the advantages of molding (molding), for example, injection molding of plastic lenses such as aspherical lenses (optical elements) have been performed due to high precision of plastic molding processing. In these lenses, it is important that the surface accuracy and optical distortion satisfy the required accuracy sufficiently, and in particular, optical distortion is a cause of disturbance of the transmitted light path. Reduction is required.

On the other hand, in molding a lens or the like having a large thickness and a large thickness deviation ratio, in order to prevent the above-mentioned optical distortion from occurring and to enhance the shape transfer accuracy, the resin is filled immediately before the resin is completely filled into the cavity. It is necessary to continue applying a suitable pressure until the filling resin solidifies from the time. Therefore, for example, a molding method for sealing a gate as described in JP-A-64-36421 has been proposed.

In this method, in order to eliminate non-uniformity in resin pressure and resin temperature caused by resin orientation and pressure distribution, the temperature of the mold is raised to a temperature higher than the glass transition point of the resin by heating the mold. Perform injection filling, seal the gate to stop the flow of the resin, then relax the resin by keeping the mold at a temperature above the glass transition point, uniform the pressure and temperature of the resin in the cavity, Next, the resin pressure is slowly decreased until the temperature becomes equal to or lower than the heat deformation temperature, and the resin pressure becomes 0 (kgf / c
Once m ²⁾ and is adapted to take out a molded product.

However, in such a molding method for sealing the gate, there is a problem that the molding cycle is lengthened due to slow cooling, and the productivity is reduced. In order to solve such a problem, for example, a molding system for sealing a gate as disclosed in Japanese Patent Application Laid-Open No. 4-310717 has been proposed. This includes a plurality of cavity units each including a pair of molds each having a cavity formed therein and a self-holding mechanism for self-holding a force in a mold clamping direction by connecting the pair of molds, and a cavity unit. Provided in the gate portion, a gate sealing means capable of sealing the gate portion, a conveying means for conveying the cavity unit in the order of a predetermined heating station, a filling / relaxation station, a slow cooling station, and a molded product removal station, It has.

In this apparatus, a cavity unit heated to a temperature higher than the glass transition point of the resin is filled with a molten resin by an injection molding machine. At this time, when the gate of the cavity unit is sealed by gate sealing means, Self-holding resin temperature and resin pressure by cavity unit alone,
That is, the resin temperature and the resin pressure are made uniform.
Next, after this state is continued for a certain period of time, the cavity unit is transported from the filling / relaxation station to the slow cooling station and gradually cooled.

While the cavity unit is gradually cooled, another cavity unit is injected and filled with a molten resin. For this reason, productivity can be improved, and since the resin temperature and the resin pressure can be appropriately maintained, the occurrence of optical distortion and the like can be prevented, and the molding accuracy can be improved.

[0008]

However, the molding system in which the gate is sealed as described above is advantageous in terms of optical distortion and the like as compared with other molding methods. Since the mold temperature is only maintained for a certain period of time, when molding a lens or the like with a large wall thickness and uneven thickness ratio,
Optical distortion and the like could not be sufficiently prevented.

That is, of the optical strains remaining in the molded article, those in the skin layer (layer formed along the cavity surface) are mainly caused by freezing of shear stress due to flow,
Since optical strain in the core layer (resin in the skin layer) is mainly due to thermal stress due to thermal shrinkage, freezing of these shearing stress and thermal stress can be achieved only by maintaining the mold temperature during injection for a certain period of time. It cannot be sufficiently removed, and therefore, there has been a problem that the occurrence of optical distortion or the like cannot be sufficiently prevented.

The inventions according to claims 1 to 11 have been made in view of such a conventional problem, and an injection molding method and an injection molding method having high precision transferability by preventing the occurrence of optical distortion. An object is to provide a molding device. Claim
It is an object of the invention described in 12 to 20 to provide an injection molding method and an injection molding apparatus which have high precision transferability while preventing occurrence of optical distortion and have high productivity.

Further, according to the invention of claims 21 to 30, the temperature of the cavity unit can be raised quickly and uniformly at the time of filling and relaxing of the molten resin, and the occurrence of optical distortion is further prevented. It is an object of the present invention to provide an injection molding method and an injection molding apparatus having transferability with higher precision.

[0012]

In order to achieve the above object, according to the first aspect of the present invention, each unit has a pair of molds each having a cavity formed therein, and the pair of molds are connected to each other in a mold clamping direction. A heating step of sequentially heating the cavity unit having a self-holding mechanism that self-holds the force of the resin, and after heating, injecting and filling the molten resin through the gate portion into the cavity unit, and sealing the gate of the cavity unit after the filling. After the filling / relaxation step of relaxing the molten resin, the injection molding of the molten resin into the cavity unit, and the final heating step of heating the cavity unit when the relaxation of the molten resin is started, and after the heating of the cavity unit is completed, A slow cooling step of gradually cooling the cavity unit, and a solidification process in the cavity unit after the slow cooling of the cavity unit. A demold step of taking out the goods from the cavity unit and is characterized in that it consists of.

In order to achieve the above object, the invention according to claim 2 is the invention according to claim 1, wherein in the final heating step, the relaxation of the molten resin filled in the cavity unit in the filling / relaxation step is completed. It is characterized in that the temperature is raised by heating. To achieve the above object, Claim 3
The invention described in claim 1 is the invention according to claim 1 or 2,
In the heating step, the cavity unit is heated so that the mold temperature at the time of injection is equal to or higher than the glass transition point of the resin.

In order to achieve the above object, the invention according to claim 4 is the invention according to claim 1, wherein the heating step comprises:
The cavity unit is heated so that the mold temperature at the time of injection is equal to or lower than the glass transition point of the resin. In the final heating step, the mold when the relaxation of the molten resin filled in the cavity in the filling / relaxation step is completed. It is characterized in that heating and heating are performed until the temperature becomes equal to or higher than the glass transition point of the resin.

In order to achieve the above object, according to a fifth aspect of the present invention, each unit has a pair of molds each having a cavity formed therein, and the pair of molds are connected to each other to self-hold a force in a mold clamping direction. A plurality of cavity units comprising a self-holding mechanism, a conveying means for conveying the cavity units in the order of a predetermined heating station, a filling / relaxation station, a slow cooling station, and a molded product taking-out station; Heating means for heating to a predetermined temperature, injection filling means provided at the filling / relaxation station, for injecting and filling the molten resin through the gate portion into the cavity unit heated by the heating means, and provided at the gate portion of each cavity unit A gate sealing means capable of sealing the gate portion,
A final heating means provided in the injection filling means for heating the cavity unit to a predetermined temperature or higher; a cooling means provided in the slow cooling station for gradually cooling the cavity unit; and a cooling means provided in the molded product take-out station. And a molded product taking-out means for taking out the molded product solidified from the above from the cavity unit.

According to a sixth aspect of the present invention, in order to achieve the above object, the injection filling means comprises an injection molding machine, and the final heating means is provided on a die plate of the injection molding machine. It is characterized by the following. In order to achieve the above object, the invention according to claim 7 is characterized in that, in the invention according to claim 6, a plurality of the final heating means are provided on the die plate.

In order to achieve the above object, an eighth aspect of the present invention is characterized in that, in the sixth or seventh aspect, the final heating means is made of oil flowing through a die plate. . To achieve the above object, Claim 9
The invention described in claim 6 is the invention according to claim 6 or 7,
The final heating means comprises a resistance heater.

In order to achieve the above object, the invention according to claim 10 is the invention according to claim 6 or 7, characterized in that the final heating means comprises a high-frequency induction heating mechanism. In order to achieve the above object, the invention according to claim 11 is characterized in that, in the invention according to any one of claims 5 to 10, a heating stage is provided in the conveying means in front of the filling / relaxation station. .

In order to achieve the above object, according to the present invention, each unit has a pair of molds each having a cavity formed therein, and the pair of molds are connected to each other to self-hold a force in a mold clamping direction. A plurality of cavity units each comprising a self-holding mechanism, a conveying means for conveying the cavity units in the order of a filling / relaxation station, a slow cooling station, and a molded product taking-out station; Filling means for injecting and filling a molten resin through the cavity unit, a gate sealing means provided at a gate portion of each cavity unit, capable of sealing the gate portion, and a cavity unit after the gate is sealed by the gate sealing means. Heating means for heating the cavity unit to a predetermined temperature; And cooling means for, provided demold station, it is characterized in that it comprises a demold means for retrieving a molded article solidified in the cavity unit from the cavity unit.

In order to achieve the above object, the invention according to claim 13 is the invention according to claim 12, wherein the injection filling means comprises an injection molding machine, and the heating means is provided on a die plate of the injection molding machine. It is characterized by the following.
To achieve the above object, the invention described in claim 14 is applied to claim 13
In the above invention, a plurality of the heating means are provided on the die plate.

In order to achieve the above object, the invention according to claim 15 is characterized in that, in the invention according to claim 12, the heating means is also provided on a transport means between a filling / relaxation station and a slow cooling station. It is assumed that. In order to achieve the above object, the invention according to claim 16 is the invention according to claim 13, wherein the heating means is made of oil flowing through a die plate.

In order to achieve the above object, the invention according to claim 17 is characterized in that, in the invention according to claim 13, the heating means comprises a resistance heater. In order to achieve the above object, an invention according to claim 18 is characterized in that, in the invention according to claim 13, the heating means comprises a high-frequency induction heating mechanism. To achieve the above object, the invention according to claim 19 is an injection molding method using the injection molding apparatus according to claim 12, wherein the mold temperature at the time of injection at the filling / relaxation station is defined as a molded product taking-out temperature. After the temperature is set to the same value, after the injection and filling of the molten resin, the mold is heated to a temperature equal to or higher than the glass transition point of the resin by a heating means.

In order to achieve the above object, an invention according to claim 20 is an injection molding method using the injection molding apparatus according to claim 15, wherein the temperature of the mold at the time of injection at the filling / relaxation station is adjusted to the molded product. After setting the temperature equal to the unloading temperature, and after injection filling of the molten resin, heating means provided in the injection molding machine and filling
The mold temperature is heated to a temperature equal to or higher than the glass transition point of the resin by a heating means provided on a transfer means between the relaxation station and the slow cooling station.

In order to achieve the above object, according to the present invention, each unit has a pair of molds each having a cavity formed therein, and the pair of molds are connected to each other to self-hold a force in a mold clamping direction. A heating step of sequentially heating the cavity unit having a self-holding mechanism, and after the heating, the molten resin is injected and filled into the cavity unit through its gate portion, and after filling, the gate of the cavity unit is sealed to ease the molten resin. After the relaxation step, the cavity unit is injected and filled with the molten resin, and the final heating step of heating the cavity unit when the relaxation of the molten resin is started, and after the heating of the cavity unit is completed,
A slow cooling step of gradually cooling the cavity unit; and a removing step of removing a molded product solidified in the cavity unit after the slow cooling of the cavity unit from the cavity unit. In the final heating step, two directions of a mold clamping direction are provided. And heating the cavity unit from two directions orthogonal to the mold clamping direction.

In order to achieve the above object, the invention according to claim 22 is the invention according to claim 21, wherein the heating step comprises:
The method is characterized in that the temperature of the mold is heated to a predetermined low temperature, and in the final heating step, the mold temperature is heated to a temperature equal to or higher than the glass transition point of the resin higher than the predetermined temperature. In order to achieve the above object, the invention according to claim 23 is a self-holding mechanism for self-holding a force in a mold clamping direction by connecting a pair of dies each of which forms a cavity therein, and connecting the pair of dies. A plurality of cavity units, and a conveying means for conveying the cavity units in the order of a predetermined heating station, a filling / relaxation station, a slow cooling station, and a molded article taking-out station; A heating means for heating; an injection filling means provided at the filling / relaxation station, for injecting and filling the molten resin through the gate portion into the cavity unit heated by the heating means; and a gate portion provided at the gate portion of each cavity unit. Provided in the gate sealing means capable of sealing the Final heating means for heating the heating unit above the glass transition point, cooling means for gradually cooling the cavity unit provided in the slow cooling station, and a molded product provided in the molded product removal station for solidifying the molded product in the cavity unit. And a molded product take-out means for taking out the molded product from the final heating means,
It is characterized in that it has a plurality of heating members that contact the cavity unit and heat the cavity unit in two directions of the mold clamping direction of the cavity unit and two directions orthogonal to the mold clamping direction.

In order to achieve the above object, the invention according to claim 24 is the invention according to claim 23, wherein the injection filling means comprises an injection molding machine, and wherein the injection filling means is provided in the mold clamping direction of the cavity unit. The heating member is provided in a horizontal mold clamping mechanism provided in a direction orthogonal to a mold clamping direction of the die plate and the cavity unit.

In order to achieve the above object, the invention according to claim 25 is characterized in that, in the invention according to claim 24, a plurality of the heating members are provided on the die plate and the horizontal clamping mechanism, respectively. To achieve the above objectives,
The invention according to claim 26 is characterized in that, in the invention according to claim 24 or 25, the heating member comprises a die plate and a resistance heater embedded in a horizontal clamping mechanism.

In order to achieve the above object, the invention according to claim 27 is characterized in that, in the invention according to claim 24 or 25, the heating member comprises a high frequency induction heating mechanism embedded in a die plate and a horizontal clamping mechanism. It is assumed that.
In order to achieve the above object, the invention described in claim 28 is based on claim 24.
26. The invention according to claim 25, wherein the heating member is made of oil flowing in the die plate and the horizontal clamping mechanism.

In order to achieve the above object, the invention according to claim 29 is the invention according to any one of claims 23 to 29, wherein the die plate is provided with a hot air mechanism, and the hot air mechanism is provided with a cavity unit. The cavity unit is provided in a die plate region other than the surface in contact with the cavity unit, and heats the cavity unit from directions other than two directions orthogonal to the mold clamping direction and the mold clamping direction of the cavity unit.

[0030] In order to achieve the above object, the invention according to claim 30 is characterized in that, in the invention according to claim 29, the hot air mechanism is capable of changing the temperature of the hot air.

[0031]

According to the first aspect of the invention, the molten resin is injected and filled into the cavity unit heated to a predetermined temperature, and when the relaxation of the molten resin is started, the heating of the cavity unit is started. For this reason, the fluidity of the molten resin is maintained,
Shear stress and heat shrinkage generated during injection filling are alleviated. As a result, it is possible to obtain a molded article having extremely low optical distortion and high transferability with high accuracy.

According to the second aspect of the present invention, in the final heating step, heating is performed until the relaxation of the molten resin filled in the cavity in the filling / relaxation step is completed. Therefore, the fluidity of the molten resin is reliably maintained, and the shear stress and heat shrinkage generated during injection filling are reliably reduced. Therefore, a molded article having high-precision transferability with less optical distortion can be obtained.

According to the third aspect of the present invention, in the heating step,
The cavity unit is heated so that the mold temperature at the time of injection is equal to or higher than the glass transition point of the resin. Therefore, the fluidity of the molten resin is reliably maintained, and the shear stress and heat shrinkage generated during injection filling are reliably reduced. Therefore,
A molded article having a high-precision transferability with less optical distortion can be obtained.

According to the fourth aspect of the present invention, in the heating step,
The cavity unit is heated so that the mold temperature during injection is equal to or lower than the glass transition point of the resin.
In the filling / relaxation step, heating and heating are performed until the mold temperature at the time when the relaxation of the molten resin filled in the cavity is completed is equal to or higher than the glass transition point of the resin. Therefore, since the mold temperature at the time of injection becomes low, it is possible to obtain a molded product having high precision transferability with less optical distortion while preventing burrs from occurring in the molded product.

According to the fifth aspect of the invention, the cavity unit heated to a predetermined temperature is filled with the molten resin by the filling means, and the gate is sealed by the gate sealing means. Then, when the relaxation of the molten resin is started in this state, the heating of the cavity unit is started by the final heating means. As a result, the fluidity of the molten resin is maintained, and the shear stress and heat shrinkage generated during injection filling are reduced. As a result, it is possible to obtain a molded article having extremely low optical distortion and high transferability with high accuracy.

In the invention according to claim 6, the injection filling means comprises an injection molding machine, and the die plate of the injection molding machine is provided with a final heating means. Therefore, the temperature can be quickly raised, and the plurality of cavity units can be simplified at a low cost without a temperature adjusting member. According to the seventh aspect of the present invention, since a plurality of final heating means are provided on the die plate, the heating time of the cavity unit is shortened, and a molded article having very small optical distortion and high precision transferability can be obtained in a short time. . As a result, the molding cycle is shortened, and the productivity of the molded product is improved.

According to the eighth aspect of the present invention, since the final heating means is made of oil flowing through the die plate, rust is prevented from being generated on the die plate and the die plate can be used for a long period of time. Can be. According to the ninth aspect of the present invention, since the final heating means is constituted by the resistance heater, the heating time of the cavity unit is shortened, and a molded article having very small optical distortion and high precision transferability can be obtained in a short time. . As a result, the molding cycle is shortened, and the productivity of the molded product is improved.

According to the tenth aspect of the present invention, since the final heating means is constituted by a high-frequency induction heating mechanism, the heating time of the cavity unit is shortened, and the molding is performed in a short time with very little optical distortion and high precision transferability. Goods are obtained. As a result, the molding cycle is shortened, and the productivity of the molded product is improved. According to the invention as set forth in claim 11, since the heating stage is provided in the transfer means before the filling / relaxation station, the subsequent cavity unloaded from the heating station while the preceding cavity unit is heated in the filling / relaxation station. The unit waits in a heated state immediately before the filling / relaxation station. As a result, the temperature of the subsequent cavity unit does not decrease, there is no need to reheat the cavity unit at the filling / relaxation station, the time for raising the temperature of the cavity unit is shortened, and the molding cycle of the molded article is shortened. .

In the twelfth aspect of the invention, when the filling of the molten resin into the cavity unit is started by the filling means, the heating of the cavity unit is started. When the gate is sealed by the gate sealing means, relaxation of the molten resin is started. At this time, since the cavity unit is heated by the heating means, the fluidity of the molten resin is maintained, and the shearing stress and thermal shrinkage generated during injection filling are reduced. For this reason, a molded article having extremely accurate optical transferability and high precision transferability can be obtained.

Further, since the cavity unit is heated after the filling of the molten resin is started, the filling / relaxation station also serves as the heating station, so that an independent heating station is not required. As a result, the preheating step is not required, the molding cycle of the molded article is significantly shortened, and the productivity of the molded article is greatly improved. In the invention according to claim 13, the injection filling means comprises an injection molding machine, and the heating means is provided on the die plate of the injection molding machine,
The temperature can be raised quickly, and the plurality of cavity units can be simplified at a low cost without a temperature adjusting member.

According to the fourteenth aspect of the present invention, since a plurality of heating means are provided on the die plate, the heating time of the cavity unit is reduced, and a molded article having high precision transferability with little optical distortion in a short time is obtained. can get. As a result,
The molding cycle is shortened, and the productivity of the molded product is improved.
In the invention according to claim 15, the heating means is also provided on the transport means between the filling / relaxation station and the slow cooling station. Therefore, when the heating by the injection filling means is not sufficient, by heating on the transport means, the heating of the cavity unit is surely performed, and the fluidity of the molten resin is reliably maintained, which is generated at the time of injection filling. Shear stress and thermal shrinkage are reliably reduced. For this reason, in the invention according to claim 16, a molded product having highly accurate transferability with very little optical distortion is obtained, since the heating means is composed of oil flowing through the die plate, rust is generated on the die plate. And the die plate can be used for a long period of time.

According to the seventeenth aspect of the present invention, since the heating means is constituted by a resistance heater, the heating time of the cavity unit is shortened, and a molded article having high precision transferability with very little optical distortion in a short time is obtained. can get. As a result, the molding cycle is shortened, and the productivity of the molded product is improved. In the invention according to claim 18, since the heating means is constituted by the high-frequency induction heating mechanism, the heating time of the cavity unit is shortened, and a molded article having high precision transferability with very little optical distortion in a short time can be obtained. . As a result, the molding cycle is shortened, and the productivity of the molded product is improved.

In the invention according to claim 19, after the mold temperature at the time of injection at the filling / relaxation station is set to be equal to the temperature at which the molded product is taken out, after the injection and filling of the molten resin, the mold temperature is reduced by the heating means. Heated to above the glass transition point of the resin. Therefore, the flowability of the molten resin is maintained while preventing the generation of burrs, and the shear stress and heat shrinkage generated during injection filling are alleviated. For this reason, a molded article having extremely accurate optical transferability and high precision transferability can be obtained.

In the invention according to claim 20, after the mold temperature at the time of injection at the filling / relaxation station is set to be equal to the temperature at which the molded product is taken out, the injection molding machine is provided after the injection filling of the molten resin. The mold temperature is heated to a temperature equal to or higher than the glass transition point of the resin by the heating means and the heating means provided on the transport means between the filling / relaxation station and the annealing station. Therefore, the flowability of the molten resin is maintained while preventing the generation of burrs, and the shear stress and heat shrinkage generated during injection filling are alleviated. For this reason, a molded article having extremely accurate optical transferability and high precision transferability can be obtained.

In addition, when the heating at the filling / relaxation station does not raise the temperature sufficiently, heating is performed on the transporting means, so that the cavity unit is reliably heated and the fluidity of the molten resin is reliably maintained. As a result, the shear stress and the heat shrinkage generated at the time of injection filling are reliably reduced. For this reason, in the invention according to the twenty-first aspect, a molded product having a highly accurate transfer property with very little optical distortion is obtained, the molten resin is injected and filled into the cavity unit heated to a predetermined temperature, and relaxation of the molten resin starts. When heated, the cavity unit is heated. At the time of this heating, the cavity unit is heated from two directions (for example, up and down directions) of the cavity unit clamping direction and two directions orthogonal to the mold clamping direction.

Therefore, the cavity unit is quickly heated, the temperature distribution of the cavity unit is made uniform, and the fluidity of the molten resin is maintained. As a result, the shear stress and the heat shrinkage generated during the injection filling are further alleviated, and a molded product having much higher precision transferability with very little optical distortion is obtained. In the invention according to claim 22, in the heating step, the temperature of the mold is heated to a predetermined low temperature, and in the final heating step, the mold temperature is heated to a glass transition point of a resin higher than the predetermined temperature or higher. You. Therefore, burrs do not occur on the molded product,
It is possible to obtain a molded article having transferability with higher accuracy than optical distortion.

According to the twenty-third aspect, the molten resin is injected and filled into the cavity unit heated to a predetermined temperature by the injection and filling means, and the gate is sealed by the gate sealing means. When the relaxation of the molten resin is started in this state, two directions of the mold clamping direction of the cavity unit are performed.
The cavity unit is heated by a heating member that abuts the cavity unit in two directions (eg, up and down directions) and a direction orthogonal to the mold clamping direction.

Therefore, the cavity unit is quickly heated, the temperature distribution of the cavity is made uniform, and the fluidity of the molten resin is maintained. As a result,
Shear stress and thermal shrinkage generated during injection filling are further alleviated, and a molded product having extremely high optical transferability and even higher precision transferability can be obtained. In the invention according to claim 24,
The injection filling means comprises an injection molding machine, and a heating member is provided on a die plate of the injection molding machine provided in the mold clamping direction of the cavity unit and a horizontal mold clamping mechanism provided in a direction orthogonal to the mold clamping direction of the cavity unit. . Therefore, it is not necessary to provide a temperature adjusting member for each of the plurality of cavity units, and the manufacturing cost of the cavity unit is reduced.

In the invention according to claim 25, a plurality of heating members are provided for the die plate and the horizontal clamping mechanism, respectively. Therefore, the heating time of the cavity unit is greatly reduced, and the molding cycle of the molded product is shortened. As a result, the productivity of the molded product is improved. In the invention according to claim 26, the heating member is constituted by the die plate and the resistance heater buried in the horizontal clamping mechanism. Therefore,
The heating time of the cavity unit is greatly reduced, and the molding cycle of the molded product is shortened. As a result, the productivity of the molded product is improved.

In the invention according to claim 27, the heating member comprises a die plate and a high-frequency induction heating mechanism embedded in the horizontal clamping mechanism. Therefore, the heating time of the cavity unit is greatly reduced, and the molding cycle of the molded product is shortened. As a result, the productivity of the molded product is improved.
In the invention according to claim 28, the heating member is made of oil flowing in the die plate and the horizontal clamping mechanism. Therefore, rust is prevented from being generated on the die plate and the horizontal clamping mechanism, and the die plate and the horizontal clamping mechanism can be used for a long time.

In the invention according to claim 29, the hot air mechanism is provided on the die plate, and the hot air mechanism is provided in the die plate area other than the surface in contact with the cavity unit. The cavity unit is heated from directions other than two directions orthogonal to the tightening direction. Therefore, the cavity unit is also heated from the surface of the cavity unit where the heating member is not provided, so that the cavity unit can be heated in a shorter time and the temperature distribution of the cavity unit is further uniformed while melting. The fluidity of the resin can be maintained. As a result, it is possible to further alleviate the shear stress and the heat shrinkage generated at the time of injection filling, and to obtain a molded product having very high optical transferability and extremely high transferability.

In the invention according to claim 30, since the warm air mechanism can change the temperature of the warm air, the heating temperature of the cavity unit can be easily adjusted, and the heating time of the cavity unit can be adjusted. It can be done easily.

[0053]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 11 are views showing an embodiment of an injection molding method and an injection molding apparatus for achieving the injection molding method according to the first to eleventh aspects of the present invention. An example in which the present invention is applied to molding is shown.

First, the configuration will be described. Figure 1
In FIG. 3, reference numeral 10 denotes a plurality of cavity units,
Each of the cavity units 10 includes a pair of upper and lower molds 11 and 12 that form a cavity 10a having a predetermined shape therein. The upper and lower molds 11 and 12 are composed of lens mirror pieces 11a and 12a, gate pieces 11b and 12b and input pieces 11c and 12c, and two template portions 11d, 11e and 12d and 12e for attaching the same.
And a strip-shaped cavity
10a is formed.

Further, the lens mirror pieces 11 of the upper and lower dies 11, 12
A groove-shaped concave portion (not shown) is formed in the peripheral portion of the transfer surface of a, 12a, and a plurality of ribs are formed at the ridge of the cavity 10a. The plurality of cavity units 10 are transported by a transporting means 90 such as a chain, heated at a predetermined heating station 20, and then sent to a filling / relaxation station 30, where the melt / melt into the cavity 10a is performed. The gate is sealed by injecting and filling the resin, and the temperature and pressure are reduced.Then, the resin is conveyed to the slow cooling station 40 where it is gradually cooled to a temperature equal to or lower than the thermal deformation temperature.
The mold is opened for taking out the molded product.

The heating station 20 is a place for quickly heating the cavity unit 10 with uniform heat, and includes a plurality of mold heating devices 21A, 21B and 21C as heating means. As shown in FIGS. 4 and 5, the mold heating device 21A
To 21C are copper materials having good thermal conductivity (heat conductivity 3
32 kcal / mh ° C.) and a pair of L-shaped heater blocks 22, 23,
Multiple sets of rod heaters 24 and thermocouples 25 embedded in 23
A clamping means 26 of a general clamp type, which is fixed upright on a substrate 27 together with a lower heater block 22, and a plurality of bolts 28A, 28B to form an upper heater block 23.
And a heater block retainer 29 connected to the heater block holder 29.

By rotating the tension lever portion 262 of the fastening means 26, the heater block 2
Cavity unit 1 inserted in the space between 2 and 23
Zero is clamped or its clamped state is released.
Further, a heater controller (not shown) cooperates with the thermocouple 25 to manage the calorific value of the bar-shaped heater 24. In both figures, reference numeral 261 denotes a stand portion of the fastening means 26; 263, a pressing plate interposed between the tension lever portion 262 and the heater block presser 29;
1, 292, 293 and 271 are heat insulating plates, and 231 and 232 are relative rotation stoppers between the heater blocks 22 and 23 attached to the heater block 23.

The tightening means 26 is for heating the cavity unit 10 and shortening the time required for raising the temperature. That is, the heating / heating time varies significantly depending on the degree of adhesion between the heater blocks 22 and 23, and the heating time of the cavity unit 10 can be shortened by heating while generating a strong fastening force by the fastening means 26.

Further, in the heating method in this embodiment, for example, the mold heating device 21A as the first heating stage is set slightly higher than the target temperature (the temperature at the time of injection), and then the second and third heating stages are performed. A step heating system in which the cavity unit 1 is heated uniformly in stages by the mold heating devices 21B and 21C as stages is adopted. Further, the shape of the heater blocks 22 and 23 does not necessarily have to be L-shaped, and heating from four directions (four-sided heating) may be performed. The material of the heater blocks 22 and 23 may be replaced with the above-described copper material. For example, an aluminum material having good heat conductivity can be used. Further, the tightening method of the tightening means 26 can obtain a sufficient tightening force by any power such as hydraulic pressure or air pressure.

In this embodiment, a heating stage 80 is provided on the conveying means 90 on the front side of the filling / relaxation station 30, and the heating stage 80 is also provided with the above-described mold heating apparatus.
A heating device 80A is provided for keeping the cavity unit 10 at a target temperature. In the filling / relaxation station 30, a resin is injected and filled into the cavity 10a of the cavity unit 10 at a high pressure and is moved by a ball-shaped moving valve body 13 (gate sealing means) as shown in FIGS. 6 (a) and 6 (b). The gate of the cavity unit 10 is sealed, so that uneven distribution of the temperature and pressure of the resin after filling is reduced. The injection / filling operation is performed by a known injection molding machine 60 (injection filling means) at a high pressure of, for example, 1000 kgf / cm ² or more. As shown in FIG. 7, a plurality of resistance heaters 63, 64 are provided on die plates 61, 62 of the injection molding machine 60.
(Final heating means) is embedded, and die positioning jigs 65 and 66 for positioning the cavity unit 10 at predetermined positions are attached to the die plate 62.

The filling / relaxation station of the present embodiment
7, the pressing mechanism 71 including the hydraulic cylinder 71a and the contact member 71b tightens the cavity unit 10 also in a direction orthogonal to the mold clamping direction, as shown in FIG. This prevents the cavity unit 10 from being deformed so as to open in the orthogonal direction during injection filling. When such deformation occurs, a gap is generated between the lens mirror pieces 11a, 12a constituting the cavity unit 10 and the mold plates 11e, 11d, 12d, 12e in the mold main body, and burrs are generated. In this case, the lens mirror pieces 11a, 12
This is because a is deformed.

On the other hand, the cavity unit 10 is provided with a self-holding mechanism 15 so that a predetermined mold clamping force can be held by the self-holding mechanism 15. Specifically, as shown in FIGS. 2 and 3, the self-holding mechanism 15 includes a plurality (four) of self-holding bolts 16 that connect the upper and lower dies 11 and 12 of the cavity unit 10 by tightening them in the mold-clamping direction. The self-holding bolt 16 is provided near the cavity 10a and penetrates the mold 11 and is screwed to the mold 12. By adopting the self-holding mechanism 15, the gate portion 10b of the cavity unit 10 is moved to the movable valve body 13 after filling / relaxation by the injection molding machine 60.
After closing the gate for a certain period of time, the injection molding machine 60
To allow the cavity unit 10 to be gradually cooled alone and to maintain a predetermined pressure-holding state independent of the injection molding machine 60. In FIGS. 2 and 3,
14a and 14b are positioning pins for relative positioning of the upper and lower dies 11 and 12.

The slow cooling station 40 is provided with a cavity unit taken out of the injection molding machine 60 by opening the machine.
An air-based slow cooling device 41 is provided which gradually cools 10 at a cooling rate of 5 ° C./min or less to a temperature equal to or lower than a heat deformation temperature (solidification temperature). This air-based slow cooling device 41 is shown in FIG. As described above, it is composed of a forced exhaust duct 43 installed on the mold transfer section. The mold transfer section 42 constitutes a part of the transfer means 90, and advances at a fixed speed by a set count number or stops for a set stop time. Further, it is set so that the time of one molding cycle = the moving time of the mold conveying unit 42 + the stopping time. The forced exhaust duct 43 is provided for the purpose of generating air flow inside the cover and cooling the mold more quickly, and the air flow of the entire duct is based on the airflow scale of the intake duct 43 of the exhaust duct 43. Etc. can be adjusted. Further, in order to change the slow cooling rate (cooling rate) of the cavity unit 10, shielding plates 44 are provided at four positions of the apparatus, and the air flow can be adjusted by changing the directions thereof. .

The molded product take-out station 50 uses a well-known nut runner (automatic tightening tool) 51 as shown in FIG. After loosening the plurality of self-holding bolts 16 of the holding mechanism 15, the upper and lower dies 11, 12 are opened by the die opening / closing device 52 shown in FIG. The mold opening / closing device 52 includes a lifting plate 54 attached to a plurality of guide posts 53 (only one is shown) so as to be able to move up and down, and a fixed plate fixed below the lifting plate 54.
55, an auto-clamp type (for example, an automatic type using a pneumatic cylinder) mold clamp 56 which is attached to the elevating plate 54 and engages with a groove 10d formed in the periphery of the cavity unit 10, and a fixing plate 55. Mold clamp 57 mounted
And a lifting drive source (not shown). Also,
Since the cavity unit 10 does not have an eject mechanism, the molded product is taken out by a so-called gripping type take-out device (not shown). The cavity unit 10 from which the molded product has been taken out is tightened with the self-holding bolt 16 by the nut runner 51, and the mold is closed and clamped again.

Next, the operation will be described. First, in this embodiment, the movable valve body 13 is put in advance between the upper and lower molds 11 and 12 of the cavity unit 10, for example, in a gate portion forming groove of the lower mold 12, and the mold opening / closing device of the molded product removal station 50 The self-holding bolt 16 is tightened by 52, and the cavity unit 10 is closed and clamped.

The cavity unit 10 has a glass transition point T1 at the heating station 20 as shown by the solid line in FIG.
After being soaked and heated to the following temperature Tb, it is transferred to the filling / relaxation station 30. At this time, if the preceding cavity unit 10 is performing work at the filling / relaxation station 30, the succeeding cavity unit 10 is made to stand by at the heating stage 80, and is kept at the target temperature.

After being conveyed to the filling / relaxation station 30, it is set (clamped) in the injection molding machine 60 and receives a clamping force from the injection molding machine 60. Also, with this mold clamping, the cavity unit 10 is also clamped by the pressing mechanism 71 in a direction orthogonal to the mold clamping direction.
The cavity in the cavity unit 10 is injected and filled with the molten resin. And upon completion of this injection, cavity 10
When the gate is sealed by the movable valve body 13 which has received the injection resin pressure on the a side, the cavity unit 10 is heated to a temperature equal to or higher than the glass transition point T1 by the resistance heaters 63 and 64,
The uneven distribution of pressure and temperature of the resin in the cavity unit 10 is reduced. When the uneven distribution of the pressure and temperature of the resin is reduced, the operation of the resistance heaters 63 and 64 is stopped.

Next, the mold of the cavity unit 10 by the injection molding machine 60 is released, and the cavity unit 10 is released by opening the injection molding machine 60 and releasing the clamp of the pressing mechanism 71.
When the 10 is taken out of the injection molding machine 60, the cavity unit 10 is sent to the slow cooling station 40 where it is gradually cooled. At this time, the cavity unit that is gradually cooled
Since the bolt 10 is fastened by the self-holding bolt 16, it can hold a predetermined mold clamping force by itself, and a desired holding pressure state can be obtained without relying on the holding pressure of the injection molding machine 60. Therefore, the upper and lower molds 11 of the cavity unit 10,
The transfer surface shape (the surface forming the cavity 10a) formed on the transfer surface 12 is transferred with high accuracy, and unnecessary burrs do not occur.

The resin in the cavity unit 10 is solidified by the slow cooling of the cavity unit 10 (cooled to the heat deformation temperature T2),
When the cavity unit 10 is transported to the molded product removal station 50, the self-holding bolt 16 is loosened by the nut runner 51, and the mold of the cavity unit 10 is opened. And the solidified molded product is the cavity unit
It is taken out from 10 by the above-mentioned take-out type take-out device. Hereinafter, continuous molding is performed with the above series of steps (see the solid line b in FIG. 10) as one cycle.

As described above, in this embodiment, the cavity unit heated to the temperature Tb below the glass transition point T1 is used.
The molten resin is filled in the injection molding machine 60 and the gate is sealed by the moving valve body 13. When the relaxation of the molten resin is started in this state, the resistance heaters 63, 64
Since the heating of the cavity unit 10 is started by this, the fluidity of the molten resin can be maintained, and the shearing stress and thermal shrinkage generated during injection filling can be reduced. For this reason, it is possible to obtain a molded article having extremely high optical transferability and high precision transferability.

Further, the cavity unit 10 is heated by the mold heating devices 21A to 21C so that the mold temperature at the time of injection becomes equal to or lower than the glass transition point T1. Since the heating and heating are performed until the relaxation of the molten resin filled in the mold is completed, it is possible to reliably maintain the fluidity of the molten resin described above while preventing burrs from occurring in the molded product, and to perform injection filling. The shearing stress and thermal shrinkage generated at the time can be surely alleviated, and a molded article having a high precision transferability with less optical distortion can be obtained.

Further, since the resistance heaters 63 and 64 are provided on the die plates 61 and 62 of the injection molding machine, it is possible to quickly raise the temperature.
Can be simplified at a low cost without a temperature control member. Further, resistance heaters 63 and 64 are used as heating means.
In addition, since a plurality of resistance heaters 63 and 64 are provided on the die plates 61 and 62, the heating time of the cavity unit 10 can be reduced, and the optical distortion can be reduced in a short time with high precision. A molded article having transferability can be obtained. As a result, the molding cycle can be shortened and the productivity of the molded article can be improved.

Further, since the heating stage 80 is provided in the transfer means 90 in front of the filling / relaxation station 30, the carrier unit 10 is unloaded from the heating station 20 while the preceding cavity unit 10 is heated in the filling / relaxation station 30. Filling and relaxation station for the subsequent cavity unit 10
It can be made to stand by in the heated state just before 30. For this reason, the temperature of the subsequent cavity unit 10 can be prevented from lowering, and it is not necessary to reheat the cavity unit 10 at the filling / relaxation station. To shorten
The molding cycle of the molded article can be shortened.

In this embodiment, the cavity unit 1 is set so that the mold temperature at the time of injection becomes equal to or lower than the glass transition point T1.
0 is heated and heated until the mold temperature at the time when the relaxation of the molten resin filled in the cavity 10a in the filling / relaxation step is completed is equal to or higher than the resin glass transition point T1, but is not limited thereto. Alternatively, the cavity unit 10 may be heated so that the mold temperature at the time of injection becomes equal to or higher than the glass transition point T1, and then the cavity unit 10 may be heated to Ta (see the two-dot chain line (c) in FIG. 10). In addition, FIG. 10 shows a state at the time of filling / relaxation of the conventional molding method as indicated by a dotted line (a) for comparison. The conventional one keeps the temperature of the cavity unit constant when the molten resin is relaxed, apparent from the dotted line.

FIG. 11 shows a state of occurrence of optical distortion of a molded article by the molding method shown in FIG. In FIG. 11, a conventional example indicated by a broken line (a), a solid line (b) and a two-dot chain line are shown.
It shows a comparison with the embodiment shown in FIG. This figure 11
It is clear from FIG. 11 that heating the cavity unit 10 with the resistance heaters 63 and 64 makes it possible to obtain a molded product having very high optical transferability with very little optical distortion (see FIG. 11 for photoelastic interference). The less stripes indicate better optical distortion).

In particular, compared with the case where the mold temperature at the time of injection is heated below the glass transition point by the mold heating devices 21A to 21C and then the cavity unit 10 is heated by the resistance heaters 63 and 64, It was found that the optical distortion was reduced when the mold unit was heated to a temperature equal to or higher than the glass transition point and then the cavity heater 10 was heated by the resistance heaters 63 and 64.

In this embodiment, the resistance heaters 63 and 64 are used as the final heating means. However, the present invention is not limited to this. Oil is circulated through the die plates 61 and 62, and the oil is used for the die plates 61 and 64. The cavity unit 10 may be heated via 62. By doing so, the die plate 61,
The generation of rust on 62 can be prevented so that die plates 61 and 62 can be used for a long time.

Further, it may be constituted by a high frequency induction heating mechanism. In this way, the heating time of the cavity unit 10 can be greatly reduced, and a molded product having high precision transferability with very little optical distortion can be obtained in a short time, and the molding cycle can be shortened. In addition, the productivity of molded articles can be greatly improved. The temperature of the cavity unit 10 at the time of filling / relaxation, the heating temperature at the time of relaxation / cooling rate, and the like are set appropriately according to the shape of the molded product, the material of the resin, and the size of the cavity unit. Needless to say, the effects of the example can be sufficiently obtained.

FIGS. 12 and 13 are views showing an embodiment of an injection molding method and an injection molding apparatus for achieving the injection molding method according to the present invention. In this embodiment,
Since the heating station 20 is abolished, and the point that the heating means is provided on the transport means 90 between the filling / relaxation station 30 and the regular station 40 is different from the above embodiment only, the other configuration is the same The same components are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 12, a mold heating device 100 as a heating means is provided on a transport means 90 between the filling / relaxation station 30 and the gradual station 40, and the heating device 100 is a mold of the above embodiment. It has the same configuration as the heating devices 21A to 23A. Further, a quenching stage 40A is provided on the side of the molded product take-out station 50 of the annealing station 40,
The quenching stage 40A is provided with a forced exhaust duct 43 having the same configuration as in the above embodiment. Therefore, rapid cooling can be performed by making the air flow in the forced exhaust duct 43 larger than that of the other forced exhaust ducts 43 in the slow cooling station 40.

Next, the operation will be described. In the present embodiment, the cavity unit 10 with the mold closed and the mold clamped is set to the same temperature as the temperature at which the molded product is taken out by tightening the self-holding bolt 16, and in this state, the cavity unit 10 is conveyed to the filling / relaxation station 30. Then, it is set (clamped) on the injection molding machine 60 and receives a clamping force from the injection molding machine 60. At the same time as the mold clamping, the cavity unit 10 is also clamped by the pressing mechanism 71 in a direction orthogonal to the mold clamping direction. In this state, the cavity in the cavity unit 10 is injected and filled with the molten resin.

When the injection is completed, the cavity 10
When the sealing of the gate is started by the movable valve body 13 which has received the injection resin pressure on the side a, the cavity units 10 are heated by the resistance heaters 63 and 64 to a temperature above the glass transition point T1 as shown by the solid line in FIG. Until the pressure and temperature of the resin in the cavity unit 10 are alleviated. When the uneven distribution of the pressure and temperature of the resin is reduced, the resistance heater 63,
Stop operation of 64.

At this time, since the cavity unit 10 is clamped in the direction orthogonal to the mold clamping direction by the pressing mechanism 71, if the heating is not sufficient, the mold clamping of the cavity unit 10 by the injection molding machine 60 is performed. When the cavity unit 10 is taken out of the injection molding machine 60 by releasing the injection molding machine 60 and releasing the clamp of the pressing mechanism 71, the mold is transported to the annealing station 40. The cavity unit 10 is heated again by the heating device 100.

Next, the cavity unit 10 is conveyed to the slow cooling station 40 and slowly cooled independently. Then, when the temperature is sufficiently cooled to a temperature equal to or lower than the glass transition point T1 in the slow cooling station 40, the cavity unit 10 is rapidly cooled to a temperature equal to or lower than the heat deformation temperature T2 of the resin by the rapid cooling station 40A. Next, the cavity unit 10 is transported to the molded product removal station 50, the self-holding bolt 16 is loosened by the nut runner 51, the mold of the cavity unit 10 is opened, and the solidified molded product is grasped from the cavity unit 10 by the above-described gripping method. Remove with a removal device. Hereinafter, continuous molding is performed with the above series of steps as one cycle.

As described above, in this embodiment, when the injection molding machine 60 starts filling the cavity unit 10 with the molten resin, the heating of the cavity unit 10 is started, and the gate is sealed by the gate sealing means. When the relaxation of the molten resin is started in this state, the cavity units 10 are heated by the resistance heaters 63 and 64, so that the fluidity of the molten resin is maintained, and the shear stress and thermal shrinkage generated during injection filling are reduced. Is done. For this reason, it is possible to obtain a molded article having extremely high optical transferability and high precision transferability.

Further, since the cavity unit 10 is heated after the filling of the molten resin is started, the filling / relaxation station 30 can be used as a heating station, and an independent heating station is not required. it can. As a result, a pre-heating step can be eliminated,
The molding cycle of the molded article can be greatly shortened, and the productivity of the molded article can be greatly improved.

Also, after setting the mold temperature at the time of injection at the filling / relaxation station 30 to be equal to the molded product take-out temperature,
After injection and filling of the molten resin, the mold is heated until the mold temperature reaches the glass transition point of the resin by the mold heating device 100, so high-accuracy transfer with minimal optical distortion is prevented while preventing burrs. A molded article having properties can be obtained. Furthermore, after setting the mold temperature at the time of injection at the filling / relaxation station 30 to be equal to the molded product take-out temperature, after injection filling of the molten resin, the resistance heater 63 provided at the injection molding machine 60,
The mold heating device 100 provided on the conveying means 90 between the filling and relaxation station 64 also heats the mold to a temperature equal to or higher than the glass transition point of the resin. When the temperature is not sufficient, the heating on the transporting means 90 allows the cavity unit 10 to be reliably heated. For this reason, it is possible to reliably maintain the fluidity of the molten resin and to obtain a molded product having extremely low optical distortion and high-precision transferability.

The die plates 61, 62 of the injection molding machine 60
Since a plurality of resistance heaters 63 and 64 are provided, the same effects as in the above embodiment can be obtained. Also, in the present embodiment, the heating means may be constituted by oil flowing through the die plates 63 and 64, or may be constituted by a high-frequency induction heating mechanism. Can be obtained.

In each of the above embodiments, a ball is used as the moving valve body constituting the gate sealing means. However, if a necessary gate sealing function can be exhibited, various valve bodies can be applied. Instead, for example, a polygonal valve body may be used. Figure
14 to 16 are views showing an embodiment of an injection molding method according to the invention of claims 21 to 30 and an injection molding apparatus for achieving the injection molding method. In the present embodiment, the configuration of the cavity unit, the heating unit, the cooling unit, and the molded product taking-out unit is the same as that of the above-described claims 1 to 11 except that only some of the configurations of the final heating unit and the injection filling unit are different from those of the above embodiments. Since the configuration is the same as that of the embodiment of the invention described, the same configuration will be denoted by the same reference numeral, and the description thereof will be omitted. The description will be made with reference to the drawings of the above embodiments as necessary.

First, the configuration will be described. 1 to 6, FIG. 8,
9, 14, and 15, the filling / relaxation station 30
Is provided with an injection molding machine 60 (injection filling means), and the cavity unit 10 is provided with a die plate of the injection molding machine 60.
Pressing by the molds 61 and 62 in the mold clamping direction, in this embodiment, the vertical direction. The die plate 61 is provided with a shaft member 61a, and the shaft member 61a is slidably inserted into the die plate 62. For this reason, when the cavity unit 10 is mounted on the die plate 62, the die plate 61 abuts on the upper surface of the cavity unit 10 and is clamped together with the die plate 62 by the shaft member 61a being guided by the die plate 62. It is supposed to.

A plurality of resistance heaters (heating members) 63 and 64 are embedded in the die plates 61 and 62, respectively. The cavity unit 10 is vertically moved by the resistance heaters 63 and 64, that is, in the mold clamping direction. To be heated. An opening 10c is formed in the cavity unit 10, and this opening 10c is
The injection molding machine 60 injects and fills the cavity 10a with the molten resin through the opening 60.

The die plate 62 of the injection / filling station 30 is provided with a pressing mechanism 106 (horizontal clamping mechanism) including hydraulic cylinders 98 and 99, contact members 102 and 103, and plates 104 and 105. Plates 104 and 105 are abutting members 10
It is attached to the tip of 2, 103, and plates 104, 105
When the contact members 102 and 103 are pressed by the hydraulic cylinders 98 and 99, the contact members 102 and 103 move from the position shown by the solid line to the position shown by the imaginary line to move on both sides of the cavity unit 10, that is, with the mold clamping direction of the cavity unit 10. The cavity unit 10 is laterally tightened from two orthogonal directions.

Therefore, it is possible to prevent the cavity unit 10 having relatively low rigidity from being deformed so as to open in the orthogonal direction during injection filling. When such deformation occurs, the lens mirror piece constituting the cavity unit 10
11a, 12a and mold plate parts 11e, 11d, 12d, 12
A gap is formed between the lens mirrors e and b, and burrs are generated. In severe cases, the lens mirror pieces 11a and 12a are deformed. On the other hand, in the present embodiment, it is possible to prevent such a problem from occurring.

Further, resistance heaters (heating members) 107 and 108 are embedded in the plates 104 and 105, and the cavity unit 10 is moved in the horizontal direction (2
Direction). Also, hot air mechanisms 109 and 110 are provided on the die plates 61 and 62,
The hot air mechanisms 109 and 110 are provided in a die plate area other than a surface that comes into contact with the cavity unit 10 when hot air is supplied from hot air supply means provided in the die plates 61 and 62, that is, FIGS. The hot air is supplied to the front and rear portions of the cavity unit 10 shown in FIG. The temperature of the hot air supplied from the hot air mechanisms 109 and 110 can be changed by a temperature adjusting means (not shown).

Next, the operation will be described. First, in this embodiment, the movable valve body 13 is put in advance between the upper and lower molds 11 and 12 of the cavity unit 10, for example, in a gate portion forming groove of the lower mold 12, and the mold opening / closing device of the molded product removal station 50 The self-holding bolt 16 is tightened by 52, and the cavity unit 10 is closed and clamped.

The cavity unit 10 is heated at the heating station 20 as shown by the solid line in FIG.
After being soaked and heated to the following target temperature Tb, it is transferred to the filling / relaxation station 30. At this time,
When the preceding cavity unit 10 is working at the relaxation station 30, the succeeding cavity unit 10 is caused to stand by on the heating stage 80, and is kept at the target temperature.

After being conveyed to the filling / relaxation station 30, it is set (clamped) in the injection molding machine 60, and receives a mold clamping force by the die plates 61 and 62 of the injection molding machine 60. At the same time, the plate 1 of the pressing mechanism 106 is
04 and 105, the cavity unit 10 is also clamped in a direction orthogonal to the mold clamping direction. In this state, the nozzle of the injection molding machine 60 contacts the opening 10c of the cavity unit 10, and the injection molding machine 60 The molten resin is injected and filled into the cavity 10a in the inside 10. When the gate is sealed by the movable valve body 13 which has received the injection resin pressure on the side of the cavity 10a at the time of completion of the injection, the cavity unit is controlled by the resistance heaters 63, 64, 107, 108 and the hot air mechanisms 109, 110. 10 is heated from six directions to a temperature equal to or higher than the glass transition point Ta, so that the uneven distribution of the pressure and temperature of the resin in the cavity unit 10 is reduced. When the uneven distribution of the pressure and temperature of the resin is reduced, the resistance heaters 63, 64, 10
The operations of 7, 108 and the hot air mechanisms 109, 110 are stopped. At the time of heating, the temperatures of the hot air mechanisms 109 and 110 may be appropriately adjusted.

Next, when the cavity unit 10 is taken out of the injection molding machine 60 by opening the injection molding machine 60 and releasing the clamp of the pressing mechanism 71, the cavity unit 10 is sent to the slow cooling station 40 and singly. It is cooled slowly. At this time, the cavity unit 10 that is gradually cooled
Since it is tightened by the self-holding bolt 16, a predetermined mold clamping force can be held by itself, and a desired pressure holding state can be obtained without relying on the pressure holding of the injection molding machine 60. Therefore, the transfer surface shapes (the surfaces forming the cavities 10a) formed on the upper and lower dies 11, 12 of the cavity unit 10 are transferred with high accuracy, and unnecessary burrs do not occur.

The resin in the cavity unit 10 is solidified by the slow cooling of the cavity unit 10 (cooled to the heat deformation temperature Tc),
When the cavity unit 10 is transported to the molded product removal station 50, the self-holding bolt 16 is loosened by the nut runner 51, and the mold of the cavity unit 10 is opened. And the solidified molded product is the cavity unit
It is taken out from 10 by the above-mentioned take-out type take-out device. Hereinafter, continuous molding is performed with the above series of steps (see the solid line in FIG. 15) as one cycle. Note that the broken line in FIG. 15 is shown in the conventional example.

As described above, in this embodiment, the cavity unit heated to the temperature Tb below the glass transition point Ta is used.
10 is filled with the molten resin by the injection molding machine 60, and the gate is sealed by the moving valve body 13. When the relaxation of the molten resin is started in this state, the resistance heaters 63, 6
Since heating of the cavity unit 10 is started by 4, 107 and 108, the cavity unit 10 can be quickly heated, and the fluidity of the molten resin is maintained while the temperature distribution of the cavity unit 10 is made uniform. be able to. As a result, it is possible to further alleviate the shear stress and the heat shrinkage generated at the time of injection filling, and to obtain a molded product having very high optical transferability and extremely high transferability.

In addition, since the cavity unit 10 is also heated by the warm air mechanisms 109 and 110, the heater 6
The cavity unit 10 can be heated even from the surface of the cavity unit 10 where no 3, 64, 107, and 108 are provided, and the cavity unit 10 can be heated in a shorter time. The fluidity of the molten resin can be maintained while making the temperature distribution even more uniform. As a result, shear stress and heat shrinkage generated during injection filling can be further reduced,
It is possible to obtain a molded article having transferability with higher precision than in optical distortion.

Further, since the warm air mechanisms 109 and 110 can change the temperature of the warm air, the heating temperature of the cavity unit 10 can be easily adjusted, and the heating time of the cavity unit 10 can be easily adjusted. Can be performed. Further, the cavity unit 10 is heated by the heating devices 21A to 21C so that the mold temperature at the time of injection becomes equal to or lower than the glass transition point Ta.
4, 107, 108 and the hot air mechanisms 109, 110 heat the cavity unit 10 to a temperature equal to or higher than the glass transition point Ta of the resin. The molded product can be reliably held, and the shear stress and thermal shrinkage generated during injection filling can be surely alleviated to obtain a molded product having high precision transferability with less optical distortion.

The die plates 61, 62 of the injection molding machine 60
And resistance heaters 63, 64 and plates 104, 105
Since the 107 and 108 are provided, the temperature can be quickly raised, and the plurality of cavity units 10 can be made simple at low cost without a temperature control member. Further, since the resistance heaters 63, 64, 107, and 108 are used as the heating members, and a plurality of the resistance heaters 63, 64, 107, and 108 are provided on the die plates 61 and 62 and the plates 104 and 105, The heating time of the cavity unit 10 can be shortened, and a molded article having very small optical distortion and high transferability can be obtained in a short time. As a result, the molding cycle can be shortened and the productivity of the molded article can be improved.

In this embodiment, the resistance heaters 63, 64, 107 and 108 are used as heating members. However, the invention is not limited to this, and oil is circulated through the die plates 61 and 62 and the plates 107 and 108. The cavity unit 10 may be heated by the oil via the die plates 61 and 62 and the plates 107 and 108. By doing so, the die plates 61, 62
In addition, die plates 61 and 62 and plates 107 and 108 can be used for a long period of time while preventing rust from being generated on plates 107 and 108.

The heating member may be constituted by a high-frequency induction heating mechanism. In this way, the heating time of the cavity unit 10 can be greatly reduced, and a molded product having high precision transferability with very little optical distortion can be obtained in a short time, and the molding cycle can be shortened. In addition, the productivity of molded articles can be greatly improved. The temperature of the cavity unit 10 at the time of filling / relaxation, the heating temperature at the time of relaxation / cooling rate, and the like are set appropriately according to the shape of the molded product, the material of the resin, and the size of the cavity unit. Needless to say, the effects of the example can be sufficiently obtained.

[0106]

According to the first to third aspects of the present invention, the flowability of the molten resin can be maintained, and the shearing stress and thermal shrinkage generated during injection filling can be reduced. For this reason, it is possible to obtain a molded article having extremely high optical transferability and high precision transferability.

According to the fourth aspect of the present invention, since the mold temperature at the time of injection is set to a low temperature, it is possible to prevent the occurrence of burrs on the molded product and to achieve high-accuracy transfer with less optical distortion. A molded article having the same can be obtained. According to the fifth aspect of the invention, the fluidity of the molten resin can be maintained, and the shearing stress and heat shrinkage generated during injection filling can be reduced. For this reason, it is possible to obtain a molded article having extremely high optical transferability and high precision transferability.

According to the sixth and thirteenth aspects of the present invention, the temperature can be quickly raised, and the plurality of cavity units can be simplified at a low cost without a temperature adjusting member. According to the seventh and fourteenth aspects, it is possible to shorten the heating time of the cavity unit, and to obtain a molded article having high precision transferability with very little optical distortion in a short time. As a result, the molding cycle is shortened,
The productivity of molded articles can be improved.

According to the eighth and sixteenth aspects of the present invention, rust is prevented from being generated on the die plate, and the die plate can be used for a long period of time. Claims 9, 10, 17, 18
ADVANTAGE OF THE INVENTION According to the described invention, the heating time of a cavity unit can be shortened, and the molded article which has very few optical distortions and has highly accurate transfer property can be obtained in a short time. As a result, the molding cycle can be shortened and the productivity of the molded article can be improved.

According to the eleventh aspect, while the preceding cavity unit is being heated at the filling / relaxation station, the subsequent cavity unit carried out of the heating station is heated just before the filling / relaxation station. You can wait in the state. Therefore, the temperature of the subsequent cavity unit can be prevented from lowering, and it is not necessary to reheat the cavity unit at the filling / relaxation station. As a result, the temperature rise time of the cavity unit can be shortened, and the molding cycle of the molded article can be shortened.

According to the twelfth aspect of the present invention, the flowability of the molten resin can be maintained, and the shearing stress and heat shrinkage generated during injection filling can be reduced. For this reason,
It is possible to obtain a molded product having very low optical distortion and high transferability with high precision. Further, since the cavity unit is heated after the filling of the molten resin is started, the filling / relaxation station can be used as a heating station, and an independent heating station can be eliminated. As a result, the pre-heating step is not required, the molding cycle of the molded article can be greatly shortened, and the productivity of the molded article can be greatly improved.

According to the fifteenth aspect of the present invention, when the heating by the injection filling means is not sufficient, the heating on the transfer means can surely heat the cavity unit, and the molten resin can be reliably heated. , The shear stress and the heat shrinkage generated during injection filling can be reliably reduced. For this reason, it is possible to obtain a molded article having extremely high optical transferability and high precision transferability.

According to the nineteenth aspect of the present invention, since the temperature of the mold is set at the time of injection, it is possible to prevent occurrence of burrs on a molded product and to obtain a highly accurate transfer with less optical distortion. Goods can be obtained. According to the invention as set forth in claim 20, since the mold temperature is set at the time of injection, it is possible to obtain a molded product having high precision transferability with less optical distortion while preventing burrs from occurring in the molded product. be able to.

In addition, when the heating at the filling / relaxation station does not raise the temperature sufficiently, the heating on the transporting means ensures the heating of the cavity unit and ensures the fluidity of the molten resin. Can be held. As a result, it is possible to surely alleviate the shear stress and the thermal shrinkage generated during the injection filling, and to obtain a molded article having extremely accurate optical transferability with very little optical distortion.

According to the twenty-first aspect, the cavity unit can be rapidly heated, and the fluidity of the molten resin can be maintained while the temperature distribution of the cavity unit is made uniform. As a result, it is possible to further alleviate the shear stress and the heat shrinkage generated at the time of injection filling, and to obtain a molded product having very high optical transferability and extremely high transferability.

According to the twenty-second aspect of the present invention, it is possible to prevent the occurrence of burrs in the molded product, and to obtain a molded product having extremely low optical distortion and having higher transferability with higher precision. According to the twenty-third aspect of the present invention, it is possible to obtain an injection molding apparatus capable of quickly heating the cavity unit, uniformizing the temperature distribution of the cavity, and maintaining the fluidity of the molten resin. As a result, it is possible to further alleviate the shear stress and the heat shrinkage generated at the time of injection filling, and to obtain a molded product having very high optical transferability and extremely high transferability.

According to the twenty-fourth aspect, it is not necessary to provide a temperature adjusting member for each of the plurality of cavity units, and the manufacturing cost of the cavity unit can be reduced. According to the inventions described in claims 25 to 27, the heating time of the cavity unit can be greatly reduced, and the molding cycle of the molded product can be shortened. As a result, the productivity of the molded article can be improved.

According to the twenty-eighth aspect of the present invention, rust can be prevented from being generated on the die plate and the horizontal clamping mechanism, and the die plate and the horizontal clamping mechanism can be used for a long time. According to the invention according to claim 29, the cavity unit can be heated even from the surface of the cavity unit where the heating member is not provided, and the cavity unit can be heated in a shorter time, and the cavity unit can be heated. And the fluidity of the molten resin can be maintained while making the temperature distribution of the resin more uniform. As a result, it is possible to further alleviate the shear stress and the heat shrinkage generated at the time of injection filling, and to obtain a molded product having very high optical transferability and extremely high transferability.

According to the thirtieth aspect, the heating temperature of the cavity unit can be easily adjusted.
It is possible to easily adjust the heating time of the cavity unit.

[Brief description of the drawings]

FIG. 1 is a plan view showing a system configuration of an embodiment of an injection molding method and an injection molding apparatus for achieving the method according to the first to eleventh aspects of the present invention.

FIGS. 2A and 2B are diagrams showing a configuration of a cavity unit according to an embodiment, wherein FIG. 2A is a front sectional view and FIG. 2B is a side sectional view.

FIG. 3 is a perspective view of an upper mold of the cavity unit.

FIG. 4 is a partial cross-sectional view of a mold heating device according to one embodiment.

FIG. 5 is a side view of the mold heating device.

FIG. 6 is a diagram showing a configuration of a gate sealing unit according to one embodiment;
(A) shows the time of injection filling when the moving valve body moves to the cavity side, and (b) shows the time of sealing the gate where the moving valve body moves to the nozzle side.

FIG. 7 is a configuration diagram of a vertical injection molding machine of one embodiment.

FIG. 8 is a schematic configuration diagram of a pneumatic slow cooling device of one embodiment.

FIG. 9 is a configuration diagram of a mold opening / closing device for removing a molded product according to one embodiment.

FIG. 10 is a diagram illustrating a temperature change of a cavity unit during a molding operation according to one embodiment.

FIG. 11 is a diagram illustrating a state of occurrence of optical distortion according to one embodiment;
(a) is an optical distortion generated by the conventional gate seal molding, and (b) is an injection and injection at a temperature lower than the glass transition point of one embodiment.
FIG. 4C is a diagram showing optical distortion when filled and (c) shows optical distortion when injected and filled at a temperature equal to or higher than the glass transition point of one example.

FIG. 12 is a plan view showing an injection molding method according to the invention of claims 12 to 20 and a system configuration of an embodiment of an injection molding apparatus for achieving the method.

FIG. 13 is a diagram illustrating a temperature change of a cavity unit during a molding operation according to one embodiment.

FIG. 14 is a diagram showing an embodiment of an injection molding method and an injection molding apparatus for achieving the method according to any one of claims 21 to 30, wherein a die plate of the injection molding machine is provided; FIG. 3 is a front configuration diagram of a horizontal closing mechanism.

FIG. 15 is a perspective configuration diagram of a die plate and a horizontal closing mechanism of the injection molding machine.

FIG. 16 is a diagram showing a temperature change of the cavity unit during the molding operation of one embodiment.

[Description of Signs] 10 Cavity unit 10a Cavity 10b Gate section 11, 12 Upper and lower mold 13 Moving valve body (gate sealing means) 15 Self-holding mechanism 20 Heating station 21, 100 type heating device (heating means) 30 Filling / mitigation Station 40 Slow cooling station 41 Pneumatic slow cooling device (cooling means) 50 Mold removal station 60 Injection molding machine (injection filling means) 61, 62 Die plate 63, 64, Resistance heater (final heating means, heating means, Heating member) 80 Heating stage 90 Conveying means 106 Pressing mechanism (horizontal clamping mechanism) 107, 108 Resistance heater (heating member) 109, 110 Hot air mechanism

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Jun Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-2-158314 (JP, A) JP-A-Hei 5-329901 (JP, A) JP-A-5-305633 (JP, A) JP-A-6-320568 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/03 -45/13 B29C 45/17 B29C 45/64-45/82

Claims (30)

(57) [Claims] Heating for sequentially heating a pair of molds each having a cavity therein and a cavity unit having a self-holding mechanism for self-holding a force in a mold clamping direction by connecting the pair of molds. Injecting and filling the molten resin into the cavity unit through its gate after heating and filling the cavity unit, and then filling and sealing the gate of the cavity unit to relieve the molten resin after filling.
A relaxation step, a final heating step of injecting and filling the cavity resin with the molten resin and heating the cavity unit when the relaxation of the molten resin is started, and a gradual cooling of the cavity unit after the heating of the cavity unit is completed. An injection molding method, comprising: a cooling step; and a molded article removing step of removing a molded article solidified in the cavity unit after the cavity unit is gradually cooled from the cavity unit. 2. The injection molding method according to claim 1, wherein in the final heating step, heating and heating are performed until the relaxation of the molten resin filled in the cavity unit in the filling / relaxation step is completed. 3. The injection molding method according to claim 1, wherein in the heating step, the cavity unit is heated such that a mold temperature at the time of injection is equal to or higher than a glass transition point of the resin. 4. In the heating step, the cavity unit is heated so that the mold temperature at the time of injection is equal to or lower than the glass transition point of the resin. In the final heating step, the molten resin filled in the cavity in the filling / relaxation step is heated. 2. The injection molding method according to claim 1, wherein the heating is performed until the temperature of the mold at the time when the relaxation of the resin is completed is equal to or higher than the glass transition point of the resin. 5. A plurality of cavity units each comprising a pair of molds each having a cavity formed therein and a self-holding mechanism for connecting the pair of molds and self-holding a force in a mold clamping direction. A conveying means for conveying the cavity unit in the order of a predetermined heating station, a filling / relaxation station, a slow cooling station, and a molded article removing station; a heating means provided in the heating station for heating the cavity unit to a predetermined temperature; Injection filling means provided at the station and injecting and filling the molten resin into the cavity unit heated by the heating means through its gate portion; and gate sealing means provided at the gate portion of each cavity unit and capable of sealing the gate portion And provided in the injection filling means, and set the cavity unit to the glass transition point. A final heating means for heating the upper part, a cooling means provided at the slow cooling station for gradually cooling the cavity unit, and a molded article removal provided at the molded article removal station for removing the solidified product from the cavity unit from the cavity unit Means for injection molding. 6. The injection filling means comprises an injection molding machine,
The injection molding apparatus according to claim 5, wherein the final heating means is provided on a die plate of the injection molding machine. 7. The injection molding apparatus according to claim 6, wherein a plurality of said final heating means are provided on the die plate. 8. The injection molding apparatus according to claim 6, wherein said final heating means is made of oil flowing in a die plate. 9. The injection molding apparatus according to claim 6, wherein said final heating means comprises a resistance heater. 10. The injection molding apparatus according to claim 6, wherein the final heating means comprises a high-frequency induction heating mechanism. 11. A heating stage is provided in a conveying means in front of the filling / relaxation station.
10. The injection molding apparatus according to any one of 10. 12. A plurality of cavity units each including a pair of molds each having a cavity formed therein and a self-holding mechanism for connecting the pair of molds and self-holding a force in a mold clamping direction. Conveying means for conveying the cavity unit in the order of a filling / relaxation station, a slow cooling station, and a molded product take-out station; and an injection filling means provided at the filling / relaxation station, for injecting and filling the molten resin through the gate unit of the cavity unit, A gate sealing means provided at a gate portion of each cavity unit to seal the gate portion; heating means for heating the cavity unit to a predetermined temperature after the gate is sealed by the gate sealing means; A cooling means provided at the station for gradually cooling the cavity unit; Provided emissions, injection molding apparatus comprising: the demold means for retrieving a molded article solidified in the cavity unit from the cavity unit. 13. The injection filling means comprises an injection molding machine,
13. The injection molding apparatus according to claim 12, wherein the heating means is provided on a die plate of the injection molding machine. 14. The injection molding apparatus according to claim 13, wherein a plurality of said heating means are provided on a die plate. 15. The injection molding apparatus according to claim 12, wherein said heating means is also provided on a transport means between a filling / relaxation station and a slow cooling station. 16. The injection molding apparatus according to claim 13, wherein said heating means is made of oil flowing through a die plate. 17. The injection molding apparatus according to claim 13, wherein said heating means comprises a resistance heater. 18. The injection molding apparatus according to claim 13, wherein said heating means comprises a high-frequency induction heating mechanism. 19. An injection molding method using the injection molding apparatus according to claim 12, wherein the mold temperature at the time of injection at the filling / relaxation station is set to be equal to the molded product take-out temperature, and then the molten resin is injected. An injection molding method, wherein after the injection filling, the mold is heated to a temperature equal to or higher than the glass transition point of the resin by a heating means. 20. An injection molding method using the injection molding apparatus according to claim 15, wherein the mold temperature at the time of injection at the filling / relaxation station is set to be equal to the molded product take-out temperature, and then the molten resin is injected. After injection filling, the mold temperature is heated to a temperature equal to or higher than the glass transition point of the resin by the heating means provided on the injection molding machine and the heating means provided on the transfer means between the filling / relaxation station and the annealing station. An injection molding method characterized by the above-mentioned. 21. Heating for sequentially heating a pair of molds each having a cavity formed therein and a cavity unit having a self-holding mechanism for connecting the pair of molds and self-holding a force in a mold clamping direction. Injecting and filling the molten resin into the cavity unit through its gate after heating and filling the cavity unit, and then filling and sealing the gate of the cavity unit to relieve the molten resin after filling.
A relaxation step, a final heating step of injecting and filling the cavity resin with the molten resin and heating the cavity unit when the relaxation of the molten resin is started, and a gradual cooling of the cavity unit after the heating of the cavity unit is completed. A cooling step, and a molded article taking-out step of taking out the molded article solidified in the cavity unit after the cavity unit is gradually cooled, wherein the final heating step is orthogonal to the two mold clamping directions and the mold clamping direction. An injection molding method characterized by heating a cavity unit from two directions. In the heating step, the temperature of the mold is heated to a predetermined low temperature, and in the final heating step, the mold temperature is heated to a glass transition point of a resin higher than the predetermined temperature. 22. The injection molding method according to claim 21, wherein: 23. A plurality of cavity units each comprising a pair of molds each of which forms a cavity therein, and a self-holding mechanism for connecting the pair of molds and self-holding a force in a mold clamping direction. A conveying means for conveying the cavity unit in the order of a predetermined heating station, a filling / relaxation station, a slow cooling station, and a molded article removing station; a heating means provided in the heating station for heating the cavity unit to a predetermined temperature; Injection filling means provided at the station and injecting and filling the molten resin into the cavity unit heated by the heating means through its gate portion; and gate sealing means provided at the gate portion of each cavity unit and capable of sealing the gate portion Provided in the injection filling means, and the cavity unit is set at or below the glass transition point. A final heating means for heating the upper part, a cooling means provided at the slow cooling station for gradually cooling the cavity unit, and a molded article removal provided at the molded article removal station for removing the solidified product from the cavity unit from the cavity unit Means, and wherein the final heating means has a plurality of heating members that contact the cavity unit in two directions of a mold clamping direction of the cavity unit and two directions orthogonal to the mold clamping direction to heat the cavity unit. An injection molding apparatus characterized by the above-mentioned. 24. The injection filling means comprises an injection molding machine,
24. The heating member is provided on a die plate of an injection molding machine provided in a mold clamping direction of the cavity unit and a horizontal mold clamping mechanism provided in a direction orthogonal to the mold clamping direction of the cavity unit. The injection molding apparatus according to the above. 25. The injection molding apparatus according to claim 24, wherein a plurality of the heating members are provided on the die plate and the horizontal clamping mechanism, respectively. 26. The injection molding apparatus according to claim 24, wherein the heating member comprises a die plate and a resistance heater embedded in a horizontal clamping mechanism. 27. The injection molding apparatus according to claim 24, wherein the heating member comprises a high frequency induction heating mechanism embedded in a die plate and a horizontal clamping mechanism. 28. The injection molding apparatus according to claim 24, wherein the heating member is made of oil flowing in the die plate and the horizontal clamping mechanism. 29. A hot air mechanism is provided on the die plate, and the hot air mechanism is provided in a die plate area other than a surface abutting on the cavity unit, and is orthogonal to a mold clamping direction and a mold clamping direction of the cavity unit. 29. The injection molding apparatus according to claim 23, wherein the cavity unit is heated from a direction other than the two directions. 30. The injection molding apparatus according to claim 29, wherein the hot air mechanism is capable of changing the temperature of the hot air.