JPH09117943A - Injection compression molding method and mold therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fully apply the pressure due to mold clamping even to sub- compression regions and consequently realize the easy controlling of the sinking at a molding part by a method wherein molds are actuated to close under the state that some part of a molten resin is being pushed out of a cavity so as to heighten the pressure in the sub-compression regions. SOLUTION: After the interior of the cavity 1 of a mold 2 under a slightly- opened state is filled with a molten resin, a movable mold is advanced so as to bring the mold 2 into its mold-clamped state. At this time, by pushing some part of the molten resin within the cavity 1 or excess molten resin hindering mold clamping outside the cavity 1, the mold clamping by the advancement of a male mold 2b is made possible. By backflowing the excess molten resin through a gate 5, the excess molten resin can be pushed outside the cavity 1. Further, the assumption that the male mold 2b is the movable mold may well be changed to the assumption that the female mold 2a is the movable mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection compression molding method for performing molding by applying a compression force due to a mold clamping force in addition to an injection pressure in order to obtain a molded product having a sink-free mold reproducibility. Regarding the mold used for it. More specifically, for example, it relates to an injection compression molding method suitable for molding a box, a container or the like having a bottom portion and a side wall portion which is raised from the bottom portion with an inclination, and a mold used therefor.

[0002]

2. Description of the Related Art Conventionally, as an injection compression molding method, a method which is performed by the following procedure is known (Japanese Patent Publication No. 4-70).
No. 134).

(1) The mold is opened slightly, and a molten resin slightly larger than the amount of molten resin required for molding is injected into a cavity having a volume slightly larger than a predetermined cavity volume. In this state, the cavity is not yet filled with the molten resin.

(2) The injection of the resin is stopped, and the mold is clamped while maintaining the injection primary pressure to a predetermined cavity volume,
The molten resin is spread throughout this cavity, and a compression force due to mold clamping is applied to the molten resin in the cavity.

(3) If the above state is continuously maintained, the molten resin invades the parting surface of the mold to cause burrs. Therefore, the injection primary pressure is lowered and the excess molten resin in the cavity is injected to the injection nozzle side. Return to.

(4) The injection primary pressure is returned to the original state again, and a part of the molten resin that has flowed back is returned to the cavity and cooled in this state.

In the conventional injection compression molding method described above, when the mold is clamped to a predetermined cavity volume, the cavity is overfilled with mold clamping pressure, thereby improving the close contact between the resin and the cavity surface. After this mold clamping, the molten resin in the cavity is made to flow back to the injection nozzle side,
This prevents unnecessary burrs from occurring.

[0008]

By the way, for example, in injection compression molding of a molded article such as a box or a container having a bottom portion and a side wall portion which is raised from the bottom portion with a slope, usually, The cavity is formed so that the bottom portion is positioned substantially at right angles to the opening / closing direction of the mold. That is, the bottom molding region of the cavity is substantially perpendicular to the opening / closing direction of the mold, and the side wall molding region of the cavity extends from the bottom molding region with a gradient with respect to the opening / closing direction of the mold. The gradient of the side wall forming region may be a draft only or a gradient added in terms of design or function.

When the above-mentioned box or container is molded by the conventional injection compression molding method, the pressure in the side wall molding region does not increase so much even after the mold is clamped, and there is a problem that sink marks are likely to occur in this region. In other words, since the side wall forming region has the above-mentioned slope, but extends substantially in the opening / closing direction of the mold,
Unlike the bottom molding area, which is located almost at right angles to the opening and closing direction of the mold, pressure due to mold clamping is less likely to be applied. Therefore, although the mold is clamped in the overfilled state, the pressure due to this mold mainly acts only on the bottom molding region, and it hardly acts on the side wall molding region, which causes the sink mark. .

In the present specification, a cavity region, which is located substantially at right angles to the opening / closing direction of the mold, such as the bottom molding region, is a main compression region, and a mold region is opened / closed, such as the sidewall molding region. The cavity region extending from the bottom molding region (main compression region) with a gradient with respect to the direction is called a secondary compression region.

The present invention has been made in view of the conventional problems as described above, and in injection compression molding using a mold in which the cavity has the main compression region and the sub compression region, pressure due to mold clamping is applied. It is an object of the present invention to sufficiently act also on the secondary compression region so that sink marks at the molding site in the region can be easily suppressed.

[0012]

To this end, according to the first aspect of the invention, as shown in FIGS.
Is a main compression region 1a substantially perpendicular to the opening and closing direction of the mold 2,
Main compression region 1a with a gradient in the opening / closing direction of the mold 2
In the injection compression molding by the mold 2 having the secondary compression region 1b extending from the cavity 1 of the mold 2 in the open state.
After the inside is filled with the molten resin, a part of the molten resin in the cavity 1 is pushed out of the cavity 1 and the mold 2 is closed to perform an injection compression molding method for increasing the pressure in the secondary compression region 1b. Is.

The inventions of claims 9 and 10 relate to a mold used in the above-mentioned injection compression molding method.
7, the die 2 for injection compression molding is provided with the slide core 3 defining the tip of the secondary compression region 1b on the female die 2a side. As shown in FIGS. 8 and 9, the mold 2 for injection compression molding has a releasable stopper means 4 for locking the opening of the mold 2 beyond a predetermined open state. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An injection compression molding method according to the present invention will be described with reference to FIGS.

First, the mold 2 used will be described. As shown in FIG. 1, the mold 2 includes a female mold 2a and a male mold 2.
b and the cavity 1 has a mold 2
The main compression area 1a is substantially perpendicular to the opening / closing direction of the mold, and the sub compression area 1b extends from the main compression area 1a with a gradient in the opening / closing direction of the mold 2. The gate 5 is provided substantially in the center of the main compression region, and a runner 7 is formed in series with the gate 5. The gate 5 and the runner 7 may be a direct gate or a cold runner, but as shown in the drawing, it is preferable to use a valve gate and a hot runner that can be opened and closed by the gate opening / closing means 6. The reason will be described later.

The gate opening / closing means 6 includes a cylinder portion 6a formed in the female die 2a, a piston 6b slidably mounted in the cylinder portion 6a in the front-back direction, and a piston 6a.
and a rod 6c extending from b toward the gate 5. Pressurized fluid passages 6d and 6e are connected to the front and rear ends of the cylinder portion 6a. In the state shown in FIG. 1, the pressurized fluid pressure (air pressure or hydraulic pressure) is applied from the pressurized fluid passage 6d connected to the rear end side of the cylinder portion 6a.
When the piston 6b is added, the piston 6b advances to the left in the figure, and the tip portion of the rod 6c fits into the gate 5 to close it.
Further, in this state, when a pressurized fluid pressure is applied from the pressurized fluid passage 6e connected to the tip side of the cylinder portion 6a, the piston 6b moves to the rear end side of the cylinder portion 6a as shown in FIG. The rod 6c is pushed to the gate 5
Away from it and open it up.

Next, the injection compression molding method of the present invention using the mold 2 will be described.

First, as shown in FIG. 1, the cavity 1 of the mold 2 in an open state is filled with molten resin. As the resin, a thermoplastic resin used for general injection molding or extrusion molding can be widely used. Further, a thermosetting resin can be used if necessary. Furthermore, fillers such as fillers and reinforcing fibers and various additives can be added to these resins as required.

In order to obtain the state shown in FIG. 1, the mold 2 is opened more than the open state (referred to as "half-open state"), and a sufficient amount of molten resin is injected to fill the cavity 1 in the half-open state. After that, the mold 2 may be closed to the open state so that the cavity 1 in the open state is filled with the molten resin.

However, in the above-described manner, the flow of the molten resin in the cavity 1 due to the injection and the flow of the molten resin in the cavity 1 due to the compression when closing the mold 2 to the open state are intermittent. The so-called hesitation mark is likely to occur due to this interruption. In order to prevent the generation of this hesitation mark, the mold 2 is held in a predetermined open state, and the cavity 1 in this state is kept open.
It is preferable that the molten resin be injected and filled therein. Also, when injecting the molten resin in the half open state,
The closing operation of the mold 2 and the injection of the molten resin are performed in parallel, and when the mold 2 is closed until the mold 2 is opened, the cavity 1 is filled with the molten resin and the injection is completed. It is preferable.

After the cavity 1 of the mold 2 in the open state is filled with the molten resin as described above, the movable mold (the male mold 2b in the illustrated example) is moved forward, and as shown in FIG. , The mold 2 is clamped. At this time, in the present invention,
A part of the molten resin in the cavity 1, that is, an excessive amount of molten resin that hinders the mold clamping is pushed out of the cavity 1 to enable the mold clamping by the forward movement of the male mold 2b. In the illustrated example, excess molten resin is forced to flow out of the cavity 1 by flowing back through the gate 5. Although the male mold 2b is movable in the illustrated example, the female mold 2a may be movable.

The excess molten resin can be caused to flow back through the gate 5 by closing the die 2 and decreasing the holding pressure on the injection side. This backflow can be easily generated by sucking back the screw (not shown) of the injection nozzle. In the illustrated example, the gate 5 is a valve gate and the runner 7 is a hot runner as described above.
These may be direct gates and cold runners, but when performing backflow through the gate 5, it is necessary to prevent the gate 5 from being clogged with cooled resin and making it difficult to backflow. A combination is preferable.

Extrusion of the surplus molten resin from the cavity 1 is carried out by a sub-cavity (not shown) communicating with the cavity 1 in the mold 2 in addition to the reverse flow from the gate 5.
It is also possible to perform such a process by closing the mold 2 and pushing the excess resin into this sub-cavity so that the mold clamping is completed immediately after the sub-cavity is filled with the molten resin. Further, the communication between the cavity 1 and the sub-cavity can be opened and closed, and this communication is closed at the time of injection in the dimensionally open state, opened after completion of injection in the dimensionally open state, and closed again just before the completion of mold clamping. You can also do it. However, the backflow from the gate 5 by controlling the injection pressure is preferable because the labor for processing the mold 2 is not required and the control is easy.

In the open state shown in FIG. 1, since the cavity 1 is filled with the molten resin, even if the mold 2 is closed while the injection pressure is maintained, the male mold 2b is almost closed. Can't move forward. That is, since the molten resin filling the inside of the cavity 1 hardly changes in volume due to compression, it is mainly used in the main compression region 1
Only when pressure is applied to a, the male die 2b hardly moves forward, and particularly the secondary compression region 1b, which is long in the compression direction, receives almost no pressure. As shown in FIG. 3, when the inclination of the secondary compression region 1b with respect to the opening / closing direction of the mold 2 is θ and the cavity 1 is filled with the molten resin and the mold 2 is closed by the force of P, the secondary compression is performed. The pressure acting on the region 1b is P · sin θ, and it is clear that the pressure is extremely small. In addition, in FIG. 3, the position indicated by the alternate long and short dash line is the position of the male mold 2b in the open state.

As in the present invention, at the time of closing operation of the mold 2 from the open state shown in FIG. 1 to the mold clamping state shown in FIG. 2, a part of the molten resin in the cavity 1 is moved to the outside of the cavity 1. When the male mold 2b is pushed out, the excess molten resin that interferes with the mold clamping is discharged, so that the male mold 2b can be advanced by the compression stroke S _{1 of the} mold 2 for mold clamping. When the male mold 2b advances by the compression stroke S ₁ and is clamped, the secondary compression region 1b is compressed by S ₁ · sin θ and the thickness thereof changes. Letting S ₁ · sin θ be the effective compression stroke S ₂ of the _secondary compression region 1 b, the _secondary compression region 1 b undergoes compression accompanied by a thickness change corresponding to the effective compression stroke S ₂ and the pressure between the _secondary compression region 1 b and the main compression region 1 a. Will be balanced and internal pressure will be increased.

In the present invention, basically, by increasing the effective compression stroke S ₂ , the thickness change of the secondary compression region 1b, that is, the secondary compression, occurs between the open state of the mold 2 and the clamped state. The amount of compression in the region 1b is increased to increase the pressure in the sub-compression region 1b. Therefore,
The effective compression stroke S ₂ is preferably 0.02 mm or more, and particularly preferably 0.05 mm or more. If the effective compression stroke S ₂ is too small, it becomes difficult to increase the pressure in the _secondary compression region 1b. The upper limit of the effective compression stroke S ₂ is theoretically not particularly limited, but even if it is excessively increased, the molding cycle is extended and the actual profit is poor.
To the extent.

The cavity 1 in the vicinity of the outlet from which a part of the molten resin is extruded during the closing operation of the mold 2 from the open state to the closed state, for example, the vicinity of the gate 5 in the illustrated example.
Although the internal pressure of the cavity 1 drops to some extent, the pressure drop range in the cavity 1 stays within a very limited range near the outflow port because the resin has viscosity and the interval between the cavities 1 is narrow. To restore the pressure in this pressure drop region, the extrusion of the excess molten resin from the cavity 1 is terminated immediately before the completion of the mold clamping, and the remaining mold 2 until the completion of the mold clamping is completed.
It can be performed by compression by the closing operation of. However, in order to maintain the entire pressure in the sub compression region 1b as high as possible, the outlet, for example, the gate 5 in the case of reverse flow through the gate 5 and the communication portion with the cavity 1 in the case of providing the sub cavity. Is preferably provided in the main compression region 1a and is separated from the sub compression region 1b as much as possible.
In particular, when a part of the molten resin is made to flow back through the gate 5, the secondary injection is performed after completion of the mold clamping, and a part or all of the molten resin that has flowed back is pressed into the cavity 1 again.
This is preferable because it is possible to surely recover the pressure in the pressure drop region.

When a part of the molten resin is made to flow back through the gate 5, the gate 5 is a direct gate and the runner 7 is a cold runner, and when a part of the molten resin is extruded into the sub-cavity. After the secondary injection, by cooling the resin in the cavity 1 while maintaining the pressure, a good molded product can be obtained. Further, when a part of the molten resin is made to flow back through the gate 5, and the gate 5 is a valve gate and the runner 7 is a hot runner, after the secondary injection, as shown in FIG. A good molded product can be obtained by cooling the resin in the cavity 1 in the closed state.

The molded product molded according to the present invention is a mold 2
Is formed by a cavity 1 having a main compression region 1a that is substantially perpendicular to the opening and closing direction of and a sub compression region 1b extending from the main compression region 1a with a gradient with respect to the opening and closing direction of the mold 2. For example, a box or a container. An example is a box or container as shown in FIG. The gradient of the secondary compression region 1b may be provided as a so-called draft gradient or may be provided according to the design of the molded product. In addition, for example, in the case of a box or container as shown in FIG. 5, this gradient appears on the side wall portion 8, but as shown in FIG. 6A, the entire side wall portion has a gradient θ. In either case, as shown in FIG. 6 (b), only the inner surface side of the side wall portion has the slope θ. That is, the gradient θ of the secondary compression region 1b is determined by the female die 2a and the male die 2b in the secondary compression region 1b.
When both cavity surfaces are formed almost equally,
It does not matter if it is formed only on the cavity surface of the male mold 2b in the secondary compression region 1b.

The present invention, as described with reference to FIG.
Is effective when the force applied to the secondary compression region 1b becomes P · sin θ and only a small pressure is applied when the valve is closed by the force of P. From this viewpoint, the gradient θ is 0.3. It is preferable that the angle is about 45 °. If the gradient θ is less than 0.3 °, a sufficient effective compression stroke S ₂ cannot be obtained unless the compression stroke S ₁ is extremely large, and the molding efficiency tends to decrease. Also, the gradient θ
Is more than 45 °, it is possible to prevent sinking of the molded portion in the secondary compression region 1b by adjusting the injection pressure and the like without particularly taking the procedure of the present invention.

By the way, the mold 2 used in the injection compression molding method of the present invention has a spigot structure for the compression stroke S ₁ . As can be seen by looking at the change from the state shown in FIG. 1 to the state shown in FIG. 2, the tip of the secondary compression region 1b during the closing operation of the mold 2 from the open state of the mold 2 to the clamped state. The part (the left end side in the figure) is pushed in the mold clamping direction. At this time, since the resin in contact with the cavity surface is already being cooled, there is a possibility that a defect may occur in the pushed-in portion. In order to prevent this, as shown in FIG. 7, it is preferable to use a mold 2 having a slide core 3 on the side of the female mold 2a that defines the tip surface of the secondary compression region 1b. The slide core 3 is divided into two or more parts in accordance with the shape of the cavity 1 (the shape of the molded product) so that the cavity 1 can be opened by sliding in a direction perpendicular to the opening / closing direction of the mold 2. It is what For example, when the molded product has a plane circular shape as shown in FIG. 5, it is usually divided into two parts, and when it is a square shaped product, it is usually divided into four parts.

When the slide core 3 as described above is provided,
Even if the male mold 2b is advanced from the open state shown in the figure and the mold is clamped, the tip of the secondary compression region 1b is not pushed in the mold clamping direction, and a defect occurs at the tip of the secondary compression region 1b. There is no.

The injection compression molding method of the present invention can be carried out as long as the injection molding apparatus is capable of holding and holding the mold 2 in the open state and injecting the mold 2 from that state. However, an injection molding apparatus capable of holding the mold 2 in the open state against the injection pressure is usually an expensive apparatus equipped with a computer controller. Therefore, in order to carry out the injection compression molding method of the present invention with a simple device, it is preferable to use the mold 2 having the stopper means 4 as shown in FIGS. 8 to 10.

The stopper means 4 is composed of a stopper shaft 9 and a stopper block 10. The stopper shaft 9 has a male type 2 on the rear end side (the left end side in the figure).
It is fixed to b, and the front end side (right end side in the drawing) is slidably inserted into a slide hole 11 formed in the opposing female mold 2a. As shown in FIG. 10, the stopper shaft 9 has a small diameter portion 12 in an intermediate portion located inside the female mold 2a. In addition, the stopper block 10
The stopper shaft 9 has a U-shaped notch 13 that fits in the small diameter portion 12 of the stopper shaft 9. The U-shaped notch portion 13 is fitted in the female mold 2a and is cut into the small diameter portion 12 of the stopper shaft 9 located in the female mold 2a. The notches 13 are fitted together.

When the mold 2 is in the slightly open state or the half open state, as shown in FIG. 8, the side surface of the stopper block 10 abuts on the step portion between the small diameter portion 12 and the tip portion of the stopper shaft 9, The opening of the mold 2 is locked. Therefore, when the mold 2 is closed and the molten resin is injected without applying a mold clamping force, the cavity 1 is filled with the molten resin, and the mold 2 is in the open state or the semi-open state shown in FIG. 8 due to the injection pressure. Open until the stopper means 4 in this state
Will be locked by. On the other hand, when the mold 2 is closed in the slightly open state or the half open state, the stopper shaft 9 slides in the slide hole 11 to allow the male mold 2b to move forward, and the mold clamping state as shown in FIG. can get. Therefore, it becomes possible to easily carry out the injection compression molding method of the present invention without performing control by an expensive computer controller. The mold 2 is opened by sliding the stopper block 10 to the outside of the female mold 2a and releasing the fitting between the small diameter portion 12 of the stopper shaft 9 and the cutout portion 13 of the stopper block 10. , Can be done easily.

In the above description, the molten resin is injected in the closed state of the mold 2 without applying the mold clamping force. However, after the mold 2 is opened or semi-opened as shown in FIG. Needless to say, the molten resin may be injected. However, in the mold 2 described with reference to FIGS. 8 to 10, it is difficult to set the inflated state or the half-opened state as shown in FIG. 8 before the injection of the molten resin. Therefore, as shown in FIG. 11, if the spring 14 is interposed between the female die 2a and the male die 2b, this inflated state or half-opened state can be reliably obtained. In the case of the mold 2 shown in FIG. 11, the mold is clamped while compressing the spring 14, as shown in FIG.

[0037]

【Example】

Example 1 A container-shaped molded product having a wall thickness of 2 mm as shown in FIG. 5 (the angle between the main compression region and the sub compression region being 10 °, and having a rib of 5 mm in height and 2 mm in thickness on the inner surface of the side wall) was used. , AB
S resin ("Styrac ABS 191" manufactured by Asahi Kasei Corporation)
F "was used to mold with a mold as shown in FIG. The mold had a hot runner and a valve gate (gate diameter 3 mm) that was forcibly opened and closed by air drive. As the injection molding machine, "IP1050" manufactured by Komatsu Ltd. having a function of freely setting the press speed and the press pressure at an arbitrary screw position and mold opening position was used.

For the molding, after injecting in a slightly opened state with the compression stroke set to 0.5 mm, the mold is clamped and sucked back by 5 mm to flow back the surplus resin, and the secondary injection after the mold clamping is not performed. It was molded into. Table 1 shows the main molding conditions and molding results in which the press pressure, the press speed, and the injection pressure were all constant in Example 1 and Examples 2 and 3 and Comparative Examples 1 and 2 described below. Show.

Example 2 Using the same resin and apparatus as in Example 1, 5 m from the mold clamped state
m The mold is opened from the half open state to the same open state as in Example 1 while the mold is closed and injection is performed. When compressing from the open state to the mold closed state, excess resin is used without sucking back. Was made to flow backward, and the second injection after the mold clamping was not performed, and a molded product similar to that of Example 1 was molded.

Table 1 shows the main molding conditions and molding results.

Example 3 Molding was performed in the same manner as in Example 2 except that secondary injection was performed after mold clamping and a holding pressure was applied at a pressure of 200 kg / cm ² .

Table 1 shows the main molding conditions and molding results.

Comparative Example 1 Using the same resin and apparatus as in Example 1, a molded product similar to that in Example 1 was molded by ordinary injection molding in which the resin was injected in a mold clamped state.

Table 1 shows the main molding conditions and molding results.

Comparative Example 2 Using the same resin and apparatus as in Example 1, 3 m from the mold clamped state.
m The same mold as in Example 1 was molded by injecting while the mold was clamped from the opened open state so that the cavity was filled with resin during mold clamping.

Table 1 shows the main molding conditions and molding results.

Example 4 The mold used in Examples 1 to 3 was modified into a mold as shown in FIG. 11, and a normal injection molding machine having no special function as used in Example 1 was used. A molded product similar to that of Example 1 was molded using the same resin as that of Example 1. Molding is performed by closing the mold, releasing the mold clamping force, and making the mold half open by the repulsive force of the spring, and initiating injection in this state,
It was performed by starting the closing of the mold when a predetermined amount of resin was injected (when the screw position advanced to the predetermined position) and performing suck back just before reaching the mold clamping state. As a result, it was possible to obtain a good molded product that was substantially the same as in Example 2.

[0048]

[Table 1]

[0049]

The present invention is as described above, and the cavity 1 has the main compression region 1a and the sub compression region 1b.
In the injection compression molding by the mold 2 having the above, the pressure due to the mold clamping can be sufficiently applied to the sub compression region 1b, and the sink mark at the molding site in the region can be easily suppressed, and the molding with excellent quality can be achieved. You can get the goods.

On the other hand, according to the present invention, it is possible to reduce the filling pressure of the molten resin into the cavity 1 by injecting the resin in the slightly open state or the half open state, and further, in the cavity 1 during the mold clamping operation. By making the molten resin of (1) flow backward to the injection cylinder side, it is possible to reduce the thickness of the molded product.
In other words, even a thin-walled molded product or a large molded product can be reliably molded without using an extremely high injection pressure. Therefore, according to the present invention, it is possible to mold a larger and thinner molded product with the mold clamping force of the conventional injection molding machine, and such a benefit can be obtained. It is also useful in forming flat-plate shaped articles.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a cavity according to the present invention is filled with a molten resin in a partially opened state of a mold.

FIG. 2 is a cross-sectional view showing a state in which the state of FIG. 1 has shifted to a mold clamping state.

FIG. 3 is an explanatory diagram of an operation in the present invention.

FIG. 4 is a cross-sectional view showing a state in which a valve gate is closed and a cooling step is started from the state of FIG. 2;

FIG. 5 is a perspective view showing an example of a molded product according to the present invention.

FIG. 6 is an explanatory diagram of a gradient included in a secondary compression region.

FIG. 7 is a sectional view showing an example of another mold used in the injection compression molding method of the present invention.

FIG. 8 is a cross-sectional view of another mold used in the injection compression molding method of the present invention in a partially opened state or a half opened state.

9 is a cross-sectional view of the mold shown in FIG. 8 in a clamped state.

10 is an explanatory view of stopper means of the mold shown in FIG.

FIG. 11 is a cross-sectional view of another mold used in the injection compression molding method of the present invention in a partially opened state or a half opened state.

FIG. 12 is a cross-sectional view of a mold clamped state of the mold shown in FIG.

[Explanation of symbols]

 1 Cavity 1a Main compression area 1b Secondary compression area 2 Mold 2a Male type 2b Female type 3 Slide core 4 Stopper means 5 Gate 6 Gate opening / closing means 6a Cylinder part 6b Piston 6c Rod 6d Pressurized fluid passage 6e Pressurized fluid passage 7 Runner 8 Side Wall 9 Stopper Shaft 10 Stopper Block 11 Slide Hole 12 Small Diameter 13 Notch 14 Spring

Claims (10)

[Claims] 1. A mold having a cavity having a main compression region substantially perpendicular to the opening and closing direction of the mold and a secondary compression region extending from the main compression region with a gradient with respect to the opening and closing direction of the mold. In injection compression molding, after filling the cavity of the mold in the open state with the molten resin, the mold is closed while pushing a part of the molten resin out of the cavity, and the pressure in the secondary compression region A method for injection compression molding, characterized by increasing 2. The injection compression molding according to claim 1, wherein the cavity of the die in the open state is filled with the molten resin by injecting the molten resin while closing the die to the open state. Method. 3. The molten resin is injected into the cavity of the mold that is held in the open state or locked in the open state beyond the open state so that the molten resin is injected into the cavity of the mold that is in the open state. The injection compression molding method according to claim 1, wherein the condition is satisfied. 4. The injection compression molding method according to any one of claims 1 to 3, wherein a part of the molten resin in the cavity is caused to flow back from the gate when the mold is closed from the slightly opened state. 5. The injection compression molding method according to claim 4, wherein a part of the molten resin in the cavity is backflowed from the gate by sucking back the screw of the injection cylinder. 6. The injection compression molding method according to claim 4, wherein after the mold is clamped, a secondary injection is carried out, and a part or all of the molten resin flowing back from the gate is pressed into the cavity again. 7. The effective compression stroke for the secondary compression region is 0.02 mm when the mold is changed from the open condition to the mold clamping condition.
It is above, The injection compression molding method in any one of Claims 1-6 characterized by the above-mentioned. 8. The gradient of the secondary compression region is 0.3 ° to 45 °.
The injection compression molding method according to any one of claims 1 to 7, wherein 9. An injection compression molding in which a cavity has a main compression region substantially perpendicular to a mold opening / closing direction and a sub compression region extending from the main compression region with a gradient with respect to the mold opening / closing direction. A mold for injection compression molding, characterized in that a slide core that defines a tip end surface of a secondary compression region is provided on the female mold side. 10. An injection compression molding in which a cavity has a main compression region substantially perpendicular to a mold opening / closing direction and a sub compression region extending from the main compression region with a gradient with respect to the mold opening / closing direction. A mold for injection compression molding, which comprises a releasable stopper means for locking the opening of the mold beyond a predetermined open state.