JPH10315292A - Method and device for plastic molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding device for molding easily and with high accuracy a thick wall molded product such as a plastic lens. SOLUTION: A molding device is provided with a mold consisting of a fixed mold 11 and a movable mold 12, temperature control plates 13 and 14 and temperature control blocks 19 and 20 for heating or cooling the mold, press mechanisms 22 and 23 for pressing the temperature blocks to the mold and a computation control section 27. In the solidifying process of molten resin in a cavity 30, the pressure of respective sections of molten resin is sensed by a mold internal pressure sensor 26a, and based on the pressure sensed value, the operations of the temperature plates, temperature control blocks and press mechanisms are controlled by commands from the computation control section 27. The uniformization of pressure of respective sections of in-mold resin in the solidifying process, namely the uniformization of solidifying speed of molten resin, can be achieved by the above mold temperature control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for molding a plastic, and more particularly, to a molding method for producing a high-precision plastic optical element having a mirror surface such as a lens or a mirror, and a method for producing the same. It relates to a molding device suitable for carrying out.

[0002]

2. Description of the Related Art As a method of manufacturing a plastic molded product, an injection molding method of injecting a molten resin into a mold cavity maintained at a constant temperature and cooling and solidifying the molten resin is generally used. However, like lenses, mirrors, etc.
In the case of molding (1) a thick molded product, (2) a molded product having uneven thickness, or (3) a long molded product, in (1) and (2), a thick portion and a thin portion of the molded product are used. Further, in the case of (3), there is a problem that a difference in cooling rate of the molten resin is generated between the central portion and the end portion, and molding distortion is easily generated, so that it is difficult to obtain a product with good accuracy.

[0003] Conventionally, when molding this type of molded article, the resin is injected after the temperature of the mold is raised to a temperature equal to or higher than the glass transition point of the raw material resin, and the resin is injected. And remove the molded product. As a heating / cooling technique for the mold in this case, as disclosed in JP-A-1-200925 [Title of Invention: Molding method of plastic lens (Canon)], a cooling pipe for flowing cooling water into the mold is used. It is known to perform heating / cooling in combination with a heater.

[0004] In addition to the above, patent publications disclosing the manufacturing technology of plastic optical elements include, for example, the following. JP-B-7-51305 [Title of Invention: Mold for Molding (Matsushita Electric Industrial)], JP-A-6-328538 [Title of Invention: Heat Cycle System for Injection Molding (Olympus Optical Industries), JP-B-7 No. 59375 [Title of the Invention: Mold for molding plastic lenses (Nissei Plastic Industries).

[0005]

However, in the molding apparatus proposed in JP-A-1-200925, since the heater is directly embedded in the mold, only the area around the heater is rapidly heated. There is a problem that the mold has an inappropriate temperature distribution, and the quality of the molded product (such as sink marks) is likely to occur.

Further, in the molding die described in Japanese Patent Application Laid-Open No. 7-51305, the heat medium passage in the die is arranged at a short distance from the die surface where the surface area of the die is large. In addition, by arranging the heat medium passage from the upstream side to the downstream side of the heat medium passage so as to decrease the distance from the mold surface, the surface temperature of the molded article is made uniform. But,
There is a problem that it is extremely difficult to set the optimal arrangement of the heat medium passage for this mold.

The present invention has been made in view of the above problems of the prior art, and has as its object to provide a molding method and a molding method capable of easily controlling the temperature of a mold into which a molten resin has been injected to an optimum value. It is an object of the present invention to provide a molding apparatus, and more specifically, when molding a molded product in which molding pressure unevenness of a resin in a mold is likely to occur, such as a thick-walled, uneven-walled or long-sized molded product, By controlling the temperature of each part of the molten resin in the mold and equalizing the pressure of each part of the molten resin in a short time, it is possible to prevent the occurrence of molding distortion and obtain a highly accurate molded product. An object of the present invention is to provide a method and a molding apparatus suitable for carrying out the method.

[0008]

According to a first aspect of the present invention, there is provided a plastic molding method for obtaining a molded product by injecting and filling a molten resin into at least one pair of dies which are integrally joined to form a cavity. In, a mold clamping direction in which the molds are joined to each other, and a mold temperature distribution control means provided in a direction orthogonal to the mold clamping direction,
It is characterized in that selective mold temperature distribution control is performed.

According to a second aspect of the present invention, there is provided a plastic molding apparatus for obtaining a molded product by injecting and filling a molten resin into at least one pair of dies which are integrally joined to form a cavity. A mold temperature distribution control means is provided in a mold clamping direction to be joined to each other and in a direction orthogonal to the mold clamping direction, and by selectively operating these mold temperature distribution control means, selective mold temperature control is performed. Is made possible.

In the molding method of the first aspect and the molding apparatus of the second aspect, the plurality of mold temperature distribution control means are individually operated to perform the mold temperature control minutely and selectively.
Plastic products such as lenses and mirrors with high precision (shape, dimensions, surface form, etc.) can be easily and stably formed.

According to a third aspect of the present invention, in the plastic molding apparatus according to the second aspect, the mold temperature distribution control means provided in a mold clamping direction for joining the molds to each other is made of a material having high thermal conductivity. The mold temperature distribution control means formed of a temperature control plate and provided in a direction orthogonal to the mold clamping direction is formed of a temperature control block made of a material having high thermal conductivity.

According to a fourth aspect of the present invention, in the plastic molding apparatus according to the third aspect, each of the temperature control rate and the temperature control block as the mold temperature distribution control means includes a heating system and a cooling system. Features.

According to a fifth aspect of the present invention, in the plastic molding apparatus according to the fourth aspect, the heating system provided in the temperature control plate and the temperature control block comprises a heating resistor heater. And a multi-segment heater capable of freely controlling the amount of heat generated in the portion.

According to a sixth aspect of the present invention, in the plastic molding apparatus according to the fourth or fifth aspect, the cooling system provided in the temperature control plate and the temperature control block has at least one of a heat pipe and a cooling circuit. I do.

According to a seventh aspect of the present invention, there is provided a plastic molding apparatus according to the third, fourth, fifth or sixth aspect, wherein the temperature control block comprises a plurality of blocks.

In the plastic molding apparatus according to the present invention, the temperature control block can finely control the adhesion force to the mold by means of a hydraulic pressure, a pneumatic pressure, an electric motor or the like in the third, fourth, fifth, sixth or seventh aspect. It is characterized by being.

According to a ninth aspect of the present invention, in the plastic molding apparatus according to any one of the second to eighth aspects, the cavity forming portion of the mold comprises a plurality of mold members, and each mold member has at least one mold member. It is characterized by having one pressure detecting means.

According to a tenth aspect of the present invention, there is provided a plastic molding apparatus according to the ninth aspect, wherein the mold temperature distribution control means calculates and controls a set temperature in accordance with a detection result of the pressure detection means. It is characterized by having.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is a cross-sectional view showing a main configuration of a plastic molding apparatus (injection molding machine). This molding apparatus includes a pair of molds composed of a fixed mold 11 and a movable mold 12, temperature control plates 13 and 14 for heating or cooling the molds, and a heater for heating or cooling the molds. Temperature control block 19,
20 and pressing mechanisms 22 and 23 for these temperature control blocks.
And a calculation control unit 27 for controlling the operation of the temperature control plate, the temperature control block, and the pressing mechanism. The calculation control unit 27 is a mechanism for calculating and controlling the set temperature of each part of the mold based on a pressure detection value by the in-mold pressure sensor 26a described later, and includes a calculation unit 27a and an output control unit 27b. I have. Hereinafter, each component of the molding apparatus will be described in detail.

The outside of the fixed mold 11 (the right side in FIG. 1) and the outside of the movable mold 12 (the left side in FIG. 1) are temperature control means for controlling mold temperature distribution for controlling the mold temperature. Plates 13 and 14 are attached. These temperature control plates 13 and 14 are supported by right and left die plates 17 and 18 via heat insulating plates 15 and 16 provided on the outside of the temperature control plates 13 and 14, respectively. I have.

The molten resin injection port of the heating cylinder 41 constituting the injection molding machine of this molding apparatus has a temperature control plate 13,
It penetrates through the respective central portions of the heat insulating plate 15 and the die plate 17 and faces the sprue 30a of the fixed mold 11, and the mold clamping mechanism 21 fixes the movable mold 12 in the mold clamping direction (thick rightward in FIG. 1). (Indicated by an arrow)).

On both sides (upper and lower sides in FIG. 1) in a direction orthogonal to the mold clamping direction, temperature control blocks 19, which are mold temperature distribution control means for similarly controlling mold temperature, are provided.
20 are provided. These are connected to pressing mechanisms 22 and 23 capable of performing fine adjustment pressurization at a predetermined pressure by hydraulic pressure, pneumatic pressure, electric motor, or the like, and these pressing mechanisms are connected to an output control unit 27 b of an arithmetic control unit 27. .

The temperature control plates 13, 14 and the temperature control blocks 19, which are the aforementioned mold temperature distribution control means provided on both sides of the mold in the mold clamping direction and on both sides in a direction perpendicular to the mold clamping direction. Reference numeral 20 is made of a material having a high thermal conductivity (for example, an aluminum alloy, a copper alloy, or a composite of a metal and a ceramic having a high thermal conductivity). In FIG. 1, 3
Numeral 0 denotes a cavity, numeral 28 denotes a cavity forming portion of the fixed die 11, and numeral 29 denotes a cavity forming portion of the movable die 12.

Here, the structure of the temperature control plate 14 will be described in more detail with reference to FIG. FIG. 2A is a cross-sectional view taken along line AA of FIG. 1 and shows the structure of the temperature control plate 14. The vertical direction in FIG. 2A matches the vertical direction in FIG. FIG. 2B is an enlarged view of a portion B in FIG. Note that the structure of the temperature control block 19 (20) is basically the same as that of the temperature control plate 14, and a description thereof will be omitted.

In FIG. 2A, a heating system 24 and a cooling system 25 are provided at upper and lower stages and alternately in each of the right half and the left half of the temperature control plate 14. The output is communicated to the output control unit 27b of the control unit 27. However, the cooling systems 25 are provided adjacent to each other at the central portion in the vertical direction of the temperature control plate 14, that is, at the portion facing the injection port of the heating cylinder 41. Further, a thermocouple 31 is inserted between the heating system 24 and the cooling system 25, and these thermocouples 31 are connected to an indication recording thermometer 32.

As described above, the temperature control plate 14 has both the heating system 24 and the cooling system 25 therein, and the heating means of the heating system 24 is a multi-division heating resistor heater. These heaters are capable of freely controlling the amount of heat generated in each portion, and thereby can finely control the temperature distribution of the mold. The cooling means of the cooling system 25 includes at least one of a heat pipe and a cooling circuit, whereby the temperature of the mold can be adjusted with high accuracy by a simple structure.

Although not shown, the temperature control blocks 19 and 2
0 also has a heating system and a cooling system, and a thermocouple inside similarly to the temperature control plates 13 and 14. The heating system and the cooling system are connected to an output control unit 27b of an arithmetic control unit 27, and the thermocouple is connected to an instruction recording thermometer. The structure of the heating system, the cooling system, the heating system 24,
It is the same as the cooling system 25. Temperature control block 1
9 and 20 are composed of a plurality of blocks, and the pressure mechanisms 22 and 23 capable of performing fine adjustment pressurization control can control the adhesion force to the mold with high precision, so that the mold can be more finely and selectively selected. Temperature control of each part can be performed.

As described above, the heating system 24 and the cooling system 25 provided on the temperature control plates 13 and 14 and the heating system, the cooling system and the pressing mechanisms 22 and 23 provided on the temperature control blocks 19 and 20 are appropriately selected. By operating the mold, the respective parts of the mold can be quickly and more selectively adjusted to a desired temperature over a wide temperature range.

In the fixed mold 11 and the movable mold 12, each of the cavity forming portions 28 and 29 is composed of a plurality of mold members, and these mold members detect the pressure of the molten resin. In-mold pressure sensor 26a as a means
At least one. This internal pressure sensor 26
“a” is communicated to the calculation unit 27a of the calculation control unit 27 via the internal pressure detection unit 26b.

As described above, the molding apparatus of this embodiment
A plurality of in-mold pressure sensors 26a are provided in the fixed mold 11 and the movable mold 12 constituting the mold, respectively, and the temperature control plates 13 and 14 and the temperature control block 1 are respectively provided on the left and right and up and down of the mold.
9 and 20; and pressing mechanisms 22 and 23 for pressing these temperature control blocks against the mold; and an arithmetic control unit 27 for controlling the operation of the temperature control plate, the temperature control block, and the pressing mechanism. I have.

In the molding apparatus, in the step of solidifying the molten resin in the mold injected from the heating cylinder 41, the pressure of each portion of the molten resin in the cavity 30 is detected by the in-mold pressure sensor 26a, and the pressure is detected. The value is transmitted to the calculation unit 27a of the calculation control unit 27 via the internal pressure detection unit 26b, and the data from the calculation unit 27a is output to the output control unit 27.
b and the temperature control plates 13 and 14 and the temperature control blocks 19 and 2 in response to a command from the output control unit 27b.
In addition to controlling the operation of 0 (heating or cooling of each part of the mold), the pressing mechanisms 22 and 23 control the pressing force (adhesion force) of the temperature control blocks 19 and 20 against the mold. FIG.
Medium, upward and downward thick arrows indicate temperature control block 1.
The direction of these movements when increasing the pressing force of 9, 20 is shown.

In this case, in the resin portion where the detected pressure value is relatively high, the resin is heated by the temperature control plate and / or the temperature control block. Conversely, in the resin portion where the detected pressure value is relatively low, the resin is heated. The cooling is performed by the temperature control plate and / or the temperature control block. That is, in the resin portion where the detected pressure value is relatively high, the cooling rate of the injected molten resin is higher than in the other portions, indicating that the solidification of the resin is progressing excessively. On the other hand, in the part where the pressure detection value is low, the cooling of the molten resin is too slow compared to other parts, so by cooling this to promote the solidification, the resin in the mold is cooled. This is to achieve a uniform solidification rate. In this way, by controlling the temperature of each part of the mold to the optimum value based on the measured pressure of the resin in each part of the mold, the solidification rate of the molten resin in the mold becomes uniform, so that high-precision molding is performed. Goods can be easily obtained.

For example, in the case of molding a molded article having an irregular thickness such as a lens, when the mold is cooled by a cooling device having a simple structure as conventionally known, the solidification rate of the molten resin in each part of the molded article is reduced. Therefore, it was difficult to obtain a high-precision molded product. On the other hand, in the above embodiment, the solidification is delayed by heating the thin portion (the molten resin), and the solidification is promoted by cooling the thick portion. Temperature control for equalizing the solidification rate can be performed precisely and finely by determining based on the pressure detection value of each part of the molded article.

For this reason, a thick molded product, uneven molded product, or a long molded product, such as a lens and a mirror, in which the molding pressure of each part of the molded product tends to be uneven when the molten resin is solidified. Also in this case, since the pressure of each part of the molded product can be made uniform in a short time, a highly accurate molded product can be molded easily and stably. Further, in this embodiment, since the mold temperature distribution control means is provided outside the mold, there is an advantage that versatility is extremely high.

During the molding step, the thermocouples 13 and 14 and the temperature control blocks 19 and 20 are used by the thermocouple.
Are detected and transmitted to the instruction recording thermometer.
Therefore, if it is confirmed that the temperature change during the molding process recorded in the indication recording thermometer is suitable for molding a highly accurate molded product, the control program is executed based on the temperature change data. Thus, the heating / cooling operation of the mold by the temperature control plate and the temperature control block can be program-controlled.

Embodiment 2 FIG. 3 is a sectional view of an essential part showing an example of a molding method performed by using the plastic molding apparatus of the present invention. In this molding method, a plurality of plastic preforms P, which have been processed into a substantially final shape in advance, are inserted into a mold composed of an upper mold 11a and a lower mold 12a in which a plurality of cavities 30 are formed. The base material P is heated and melted to a temperature equal to or higher than the glass transition point, thereby generating a resin internal pressure, and then gradually cooled, thereby transferring the mirror-like inner surface of the mold to the surface of the base material P, thereby increasing the thickness. Thus, a molded article such as a lens having a non-uniform surface and a mirror surface is obtained. In FIG. 3, thick upward arrows indicate the mold clamping direction, and thick left and right arrows indicate the directions of pressing by the pressing mechanisms 22 and 23, respectively.

According to the molding apparatus of the first embodiment and the molding method of the second embodiment, precise and fine selective temperature control is performed for each part of the mold, so that high precision plastics such as lenses and mirrors can be obtained. Molded articles can be easily and stably manufactured.

[0038]

As is apparent from the above description, according to the present invention, the following effects can be obtained. (1) The molding method according to claim 1, wherein the mold temperature distribution control means provided in the mold clamping direction and the mold temperature distribution control means provided in a direction perpendicular to the mold clamping direction selectively mold. In order to control the mold temperature distribution,
Even in the case of a thick-walled, uneven-walled or long-shaped molded product in which irregularities in molding pressure are likely to occur, the pressure of the molten resin injected into the mold can be made uniform in a short time. As a result, occurrence of molding distortion is prevented, and a highly accurate molded product can be obtained.

(2) The molding apparatus according to claim 2, wherein the mold temperature distribution control means provided in the mold clamping direction and the mold temperature distribution control means provided in a direction perpendicular to the mold clamping direction are respectively provided. Claims 1 and 2 allow independent mold temperature control by independent operation.
The same excellent effects as the effects obtained by the molding method are obtained.

(3) The molding apparatus according to claim 3, wherein the mold temperature distribution control means comprises a temperature control plate and a temperature control block made of a material having high thermal conductivity.
The mold temperature can be quickly adjusted to the desired temperature.

(4) The molding apparatus according to claim 4 Since the temperature control plate and the temperature control block have both heating and cooling systems, the temperature of each part of the mold can be more selectively controlled over a wide temperature range. be able to.

(5) The molding apparatus according to claim 5, wherein the heating system provided in the temperature control plate and the temperature control block comprises a heating resistor heating heater, and the heating resistor heating heater can freely generate heat in each part. , The temperature of each part of the mold can be more finely controlled.

(6) A molding apparatus according to claim 6, wherein the cooling system provided in the temperature control plate and the temperature control block has at least one of a heat pipe and a cooling circuit, so that the temperature of each part of the mold can be reduced with a simple structure. It can be adjusted with high precision.

(7) The molding apparatus of claim 7 Since the temperature control block is composed of a plurality of blocks, it is possible to finely control the temperature of each part of the mold.

(8) The molding apparatus according to claim 8, wherein the temperature control block can finely control the adhesion to the mold by means of hydraulic pressure, pneumatic pressure, an electric motor or the like. It can be carried out.

(9) The molding apparatus according to claim 9, wherein the cavity forming portion of the mold is constituted by a plurality of mold members, and each mold member has at least one pressure detecting means. In the event that some of the components fail, it is possible to cope with them by exchanging only these components, resulting in excellent maintainability.

(10) The molding apparatus according to the tenth aspect, wherein the mold temperature distribution control means is provided with a calculation control unit for calculating and controlling the set temperature in accordance with the detection result of the pressure detection means. The temperature of each part of the mold can be adjusted to an optimum value.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of a plastic molding apparatus according to the present invention.

FIGS. 2A and 2B show the structure of a temperature control plate constituting the molding apparatus of FIG. 1; FIG. 2A is a cross-sectional view thereof (a cross-sectional view taken along line AA of FIG. 1); FIG.

FIG. 3 is a sectional view of a main part showing an embodiment of a plastic molding method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Fixed type 11a Upper mold 12 Movable mold 12a Lower mold 13,14 Temperature control plate 15,16 Heat insulation plate 17,18 Die plate 19,20 Temperature control block 21 Mold clamping mechanism 22,23 Pressing mechanism 24 Heating system 25 Cooling system 26a Mold internal pressure sensor 26b Internal pressure detection unit 27 Operation control unit 27a Operation unit 27b Output control unit 28, 29 Cavity forming unit 30 Cavity 30a Sprue 31 Thermocouple 32 Indicating recording thermometer 41 Heating cylinder

Claims (10)

[Claims] 1. A plastic molding method for obtaining a molded product by injecting and filling a molten resin into at least one pair of dies that are integrally joined to form a cavity, wherein a mold clamping direction in which the dies are joined to each other; A plastic molding method characterized by selectively controlling a mold temperature distribution by means of mold temperature distribution control means provided in a direction orthogonal to a mold clamping direction. 2. A plastic molding apparatus for obtaining a molded product by injecting and filling a molten resin into at least one pair of dies which are integrally joined to form a cavity, wherein a mold clamping direction in which the dies are joined to each other; Mold temperature distribution control means are provided in the direction orthogonal to the mold clamping direction, and by selectively operating these mold temperature distribution control means, selective mold temperature control can be performed. Characteristic plastic molding equipment. 3. The mold temperature distribution control means provided in a mold clamping direction for joining the molds to each other comprises a temperature control plate made of a material having high thermal conductivity, and is provided in a direction orthogonal to the mold clamping direction. The provided mold temperature distribution control means,
3. The plastic molding apparatus according to claim 2, comprising a temperature control block made of a material having high thermal conductivity. 4. A temperature control plate and a temperature control block, each of which is a mold temperature distribution control means, include a heating system and a cooling system.
A plastic molding apparatus as described. 5. A heating system provided on the temperature control plate and the temperature control block comprises a heating resistor heater, and the heating resistor heater comprises a multi-split heater capable of freely controlling the amount of heat generated in each portion. 5. The plastic molding apparatus according to claim 4, wherein: 6. The plastic molding apparatus according to claim 4, wherein the cooling system provided in the temperature control plate and the temperature control block has at least one of a heat pipe and a cooling circuit. 7. The plastic molding apparatus according to claim 3, wherein the temperature control block is composed of a plurality of blocks. 8. The plastic according to claim 3, wherein the temperature control block is capable of finely controlling the adhesion to a mold by means of a hydraulic pressure, a pneumatic pressure, an electric motor, or the like. Molding equipment. 9. The method according to claim 2, wherein the cavity forming portion of the mold comprises a plurality of mold members, and each mold member has at least one pressure detecting means. A plastic molding apparatus according to any one of the preceding claims. 10. The apparatus according to claim 9, wherein said mold temperature distribution control means includes a calculation control unit for calculating and controlling a set temperature in accordance with a detection result of said pressure detection means. Plastic molding equipment.