JPH11320621A - Mold for molding plastic molded article and method for molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and precisely control temp. in the neighborhood of a cavity. SOLUTION: A heat transfer means 14 consisting of thermal conductive members 14a and 14b for transmitting heat generated from a resin 21 in a cavity to the outside of a mold 2 from the neighborhood of the cavity, a heating member 14d provided on the side end part of the cavity of the thermal conductive members and a heat dissipation member 14f provided on the side end part of the outside of the mold of the thermal conductive members and a heat dissipation block 6 for controlling amt. of heat dissipation from the heat transfer means 14 are provided and wide range and fine temp. control is performed based on informations detected by a temp. detecting means 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die and a molding method for a plastic molded product having a complicated shape and an unbalanced thickness distribution, such as a lens and a mirror.

[0002]

2. Description of the Related Art In general, as a method for producing a plastic molded product, a molten resin is injected and filled into a cavity of a molding die maintained at a constant temperature, and then cooled to solidify the resin, thereby molding the molded product. Was. During the cooling, a heat amount corresponding to the resin volume in the cavity is radiated. For this reason, if the cavity shape is complicated and the wall thickness is extremely unbalanced, the cooling and solidification will be partially delayed, and the shrinkage of each part of the molded product will vary, causing deterioration in shape accuracy and optical distortion. Become. Therefore, conventionally, the mold temperature is raised above the glass transition point to increase the resin flow, the molten resin is injected into the cavity, and then the mold is cooled to the heat deformation temperature or lower and the molded product is taken out. Thereby, the transferability is improved, and a device for reducing the temperature difference between the surface of the molded article and the inside thereof is devised. In particular, in the case of molded products requiring high precision, such as lenses, a method of gradually cooling the mold is employed in addition to raising and lowering the mold temperature.

[0003] For example, the same applicant as the present application uses a synthetic resin film attached to the surface of a mold or a thermal emissivity adjusting means composed of a painted surface to adjust the surface of the mold during cooling according to the volume of resin in the cavity. A simple molding method and a metal mold for partially changing the thermal emissivity of the glass have already been proposed. This technology can be applied to molded products with unbalanced thickness distribution.
This is effective for keeping the cooling rate of each part uniform and suppressing the deterioration of shape accuracy and the occurrence of optical distortion. Further, by the same applicant as the present application, a heat transfer means is provided which penetrates the mold from the input piece of the forming mold forming the cavity, and detection information of a temperature sensor or the like is transmitted by a heat dissipation block connected to the heat transfer means. On the basis of this, there has been proposed a molding die configured to adjust the amount of heat radiation from the resin in the cavity. This technology realizes uniform cooling efficiently even when the thickness distribution of the resin in the cavity is unbalanced and the shape is complicated, and even when the distance from the input piece forming the cavity to the mold surface is long. It is effective to shorten the cycle.

[0004]

In the prior art, when a molding die is constituted by using the heat transfer means and the heat radiating block, if the temperature near the cavity is higher than the heat radiating block side, the temperature near the cavity is always increased. Is continued to be dissipated by being transmitted to the heat dissipation block through the heat transfer means. For this reason, when molding the plastic, such as lenses and mirrors that require high precision, when the mold temperature is raised above the glass transition point, or when the mold temperature needs to be kept constant However, there is a problem that the efficiency of temperature rise and heat retention is reduced.

[0005] It is an object of the present invention to improve such problems and to increase the temperature of the mold above the glass transition point during plastic molding or to maintain the mold temperature constant. In some cases, it is an object of the present invention to provide a molding die and a molding method for a plastic molded product capable of efficiently and accurately controlling the temperature in the vicinity of a cavity.

[0006]

In order to achieve the above object, a molding die for a plastic molded product of the present invention is provided with a cavity for integrally joining and injecting and filling a molten resin, and then solidifying by cooling. A molding die for a plastic molded product to be formed, which is provided from the vicinity of the cavity to the outside of the mold through the molding die, and conducts heat generated from the resin filled in the cavity to the outside of the mold to radiate. And a heat transfer means for heating the vicinity of the cavity so as to have a temperature distribution corresponding to the shape of the cavity.

In order to achieve the above object, a method of molding a plastic molded article according to the present invention is directed to a plastic molded article which is integrally joined to form a cavity for injecting and filling a molten resin and then solidifying by cooling. A heat conducting member provided from the vicinity of the cavity to the outside of the mold, penetrating the molding die, and transmitting heat generated from resin in the cavity to the outside of the mold from the vicinity of the cavity; What is claimed is: 1. A molding method for a plastic molded article, comprising: a heating member provided at an end of a conductive member on a cavity side; and a temperature detecting means provided near a cavity and detecting a temperature of a resin in the cavity. Heating the pair of molding dies in which the cavities are formed, injecting and filling a molten resin into the cavities, and heating until the temperature of each part becomes uniform. A cooling step of cooling a molding die injecting and filling the molten resin, transferring a mirror surface formed on the inner peripheral surface of the cavity to the resin, and solidifying the resin; In the step, the vicinity of the cavity is heated by the heating member so as to have a temperature distribution corresponding to the cavity shape based on the detection information of the temperature detecting means.

[0008]

An embodiment of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a cross-sectional view of a molding die of a plastic molded product according to a first embodiment of the present invention. In FIG. 1, a cavity forming member, that is, a fixed input piece 3 and a movable input piece 4 are provided inside a fixed die (molding die) 1 and a movable die (molding die) 2. The peripheral surface has a constant volume, the thickness distribution of the resin 21 in the cavity is unbalanced, the center of the cavity 5 is thin, and both ends have a thick concave cross section, and The cavity 5 is formed such that the distance to the surface of the movable mold 2 is longer than the distance from both ends to the surface of the movable mold 2. A mirror surface is formed on the inner peripheral surface forming the cavity 5. Further, a sprue is formed in the fixed mold 1, and a resin melted from a molding nozzle 22 of an injection molding machine is injected and filled into the cavity 5 through the sprue. Note that detection elements of three temperature sensors are arranged near the cavity on the side of the fixed input piece 3, and a temperature detection unit 18 including these temperature sensors is provided. The resin 21 in the cavity 5 is
It is configured to detect the temperature at the center and both ends of the.

A heat transfer means 14 is provided near the cavity in the movable input piece 4. This heat transfer means 14
Is inserted into the heat radiation block 6 from the vicinity of the cavity through the movable mold 2. Further, as shown in FIG. 2, the heat transfer means 14 has a heat pipe 14 for conducting heat generated from the resin 21 in the cavity from the vicinity of the cavity to the outside of the mold according to the volume of the resin 21 in the cavity.
a, 14b (= heat conducting member) and its heat pipe 14
a, 14b on the cavity side (heat pipes 14a, 14b,
The heating member 14d provided on the A portion of the heat pipe 14b and the radiating fins 14f provided on the outside of the mold of the heat pipes 14a and 14b (the B portion of the heat pipes 14a and 14b in the heat radiating block 6). Heat dissipating member). The heat pipes 14a and 14b are cylindrical and have excellent thermal conductivity and partially change the amount of heat radiated to the heat radiation block 6. Therefore, the heat pipe 14a having a large diameter has a cavity so as to promote heat radiation. The heat pipe 14 having a small diameter is disposed near both ends where the volume of the resin 21 is large.
b is arranged near the center where the volume of the resin 21 in the cavity is small so as to suppress heat radiation. Further, the heating member 14d may be a ring heater shown in FIG.
The silicon rubber heater shown in FIG.
It is constituted by any of the tape heaters shown in (c), and heats the vicinity of the cavity with a current supplied from the current control unit 19 (= heating control means). Note that the current control unit 19
Based on the detection information of the temperature detecting means 18, the heating member 14 is heated such that the center and both ends of the cavity are partially or selectively heated according to the volume of the resin 21 in the cavity.
The current supplied to d is controlled. Since the ring heater shown in FIG. 3A has a castable brass structure that can be machined, it has high thermal conductivity and has a cylindrical heat pipe 14a, 14a, 14b depending on the cavity shape of the plastic molded product.
14b can be attached to a part of the outer periphery. Therefore, the vicinity of the cavity can be effectively heated. The silicon rubber heater shown in FIG. 3B is a planar heater laid out by a plurality of parallel circuits, so that even if some circuits are disconnected, heating can be continued in the remaining circuits. Is configured. Therefore, the frequency of maintenance is low. Further, the tape heater shown in FIG. 3C has an extremely high thermal efficiency because the surface is formed of aluminum foil and the thickness of the entire heater is as thin as about 0.63 mm. In addition, since it is attached with an adhesive, attachment is easy. Further, the heating member 14d composed of the heater is
Depending on the cavity shape of the molded product, each heat pipe 14
Since a plurality of circuits are provided for each of a and b, and are configured to be controlled independently by the current control unit 19, fine and wide-ranging temperature control is possible. The plurality of radiation fins 14f shown in FIG. 2 are made of a material having a high thermal conductivity such as aluminum,
a, 14b promotes dissipation of heat conducted from the vicinity of the cavity.

The radiating block 6 includes a movable mold 2.
, And connected to the heat transfer means 14, and the heat pipes 14 a, 1
4b, the heat pipes 14a, 14
The radiation fin 14f is provided at the end of b as described above. A space 6 a is provided in the heat radiating block 6 so that the cooling medium (air) can be easily circulated, and minute portions are formed on all the surface portions (four surfaces) other than in contact with the movable mold 2 and the temperature control plate 8. A plurality of vent holes 6b. The ventilation holes 6b can be selectively sealed by a sealing material 6c, and combined with the air volume adjustment by the air volume adjusting device 20, the heat pipes 14a,
It is possible to finely adjust the amount of heat radiation from the heat transfer means 14 having the heat radiation fins 14f and the heat radiation fins 14f. In addition, the control unit (not shown) of the air volume adjusting device 20 controls to change the rotation speed of the blowing fan based on the detection information from the temperature detecting unit 18. For example, when cooling the resin 21 filled in the cavity 5, the amount of air blown to the heat radiation block 6 is increased so that heat radiation from the cavity 5 is promoted. Alternatively, the air blowing amount is changed according to the change of the resin material constituting the resin 21 in the cavity.

Further, temperature control plates 7 and 8 are provided on the outer periphery of the fixed mold 1 and the heat radiation block 6, respectively, and inside the temperature control plates 7 and 8, respectively, a heater and a cooling pipe ( (Not shown). The heater is a rod-shaped heater, the cooling pipe is a pipe for flowing water or air or water and air at a predetermined mixing ratio, and the fixed mold 1 is heated and cooled by the heater and the cooling pipe. . In addition, movable mold 2
Is heated and cooled by the heater and the cooling pipe through the heat radiation block 6. Thereby, the temperature can be adjusted from the mold clamping direction.

Die plates 11 and 12 are attached to the temperature control plates 7 and 8 via heat insulating plates 9 and 10, and a mold clamping mechanism 13 is attached to the die plate 12 side. The mold clamping mechanism 13 moves the die plate 12, the heat insulating plate 10, the heat radiation block 6, and the movable mold 2 relative to the die plate 11, the heat insulating plate 9, and the fixed mold 1 in the horizontal direction in the drawing. 5 is opened and closed, and the movable mold 2 is pressed against the fixed mold 1 to generate a predetermined mold clamping force.

Further, a synthetic resin film as a heat emissivity adjusting means 15 is adhered to the surface of the heat radiating block 6, and this film is used to reduce the heat emissivity of the surface of the heat radiating block 6 to the resin 21 in the cavity. It is changed according to the volume. Here, the reason for attaching the film will be described. For example, length and width 60 mm x 60 mm, height 180 mm
FIG. 4 shows the cooling rate when comparing the case where the black film was attached to iron or aluminum with the case where the film was not attached. From FIG. 4, it can be seen that the cooling rate is higher when the black film is attached than when it is not attached.
FIG. 5 shows the thermal emissivity of each color film when the thermal emissivity of the black film is set to 1. From this FIG.
It can be seen that the thermal emissivity differs depending on the color of the film.
In the present embodiment, such a synthetic resin film is formed such that the heat emissivity of the surface of the heat radiation block 6 becomes larger.
It is attached to the surface of the heat radiation block 6. Specifically, a black film is formed with a predetermined thickness on the surface (four surfaces) of the heat radiation block 6.
Affix to. If the resin material is different even if the cavities 5 have the same shape, the color and thickness of the film may be changed and the film may be adhered.

Further, as other thermal emissivity adjusting means,
A paint surface may be formed on the surface of the heat radiation block 6. FIG.
Shows the thermal emissivity of each color when the thermal emissivity of the black paint is set to 1. As can be seen from FIG. 6, since the thermal emissivity differs depending on the color of the paint, the thermal emissivity on the surface of the heat radiation block 6 changes according to the volume of the resin 21 at the center and both ends in the cavity 5. Heat dissipation block 6
Apply paint to the surface of. In the present embodiment, the black paint is applied to the surface (four surfaces) of the heat radiation block 6 with a predetermined thickness to form the paint surface. When the resin material of the resin 21 is changed even in the cavity 5 having the same shape, the color of the paint may be changed and applied.

Further, as other thermal emissivity adjusting means, fine irregularities are formed on the surface of the heat radiation block 6,
By adjusting the surface roughness with this uneven shape, the thermal emissivity of the heat radiation block surface may be changed according to the volume of the resin 21 in the cavity. In the present embodiment, the surface roughness is set so that the heat emissivity of the surface of the heat radiation block 6 becomes larger. Specifically, the entire surface (four surfaces) of the heat radiation block 6 is formed roughly. In addition,
If the resin material of the resin 21 is different even in the cavity 5 having the same shape, the surface roughness may be changed. The reason for this is that a mirror with a smooth surface, such as a mirror surface, has a high reflectance and a low thermal emissivity.

Next, a method for molding a plastic molded product according to this embodiment will be described with reference to FIG. First, after the molds 1 and 2 are clamped by the mold clamping mechanism 13, the temperature of the molds 1 and 2 is increased by the heaters (not shown) of the temperature control plates 7 and 8 to the glass transition point of the resin 21 or more. Then, the resin flow is increased by raising the temperature, and then the melted resin 21 is filled into the cavity 5 from the molding nozzle 22 through a sprue. In the present embodiment, the heating member 14d is provided between the time when the temperature rise is started (A) and the time when the molten resin is injected and filled (B).
This heats the ends of the heat pipes 14a and 14b near the cavity. Thus, the heat in the vicinity of the cavity is prevented from being transmitted through the heat pipes 14a and 14b and continuously radiated in the heat radiation block 6. Also, the heating member 14
d, the current controller 19 controls the temperature detection means 1
8, the resin 21 in the cavity has a larger volume than both ends (thick portion) based on the detection information near the cavity.
The temperature is controlled so that the central portion (thin portion) where the volume of the resin 21 in the cavity is small is positively heated.

Next, after the injection and filling of the molten resin, heating is continued until the temperature of each part becomes uniform based on the detection information of the vicinity of the cavity by the temperature detecting means 18, and after the uniformity of the temperature of each part is confirmed. , Heating member 1 by current control unit 19
The power supply to 4d is stopped. Therefore, (A) to (C)
During this period, heating control is performed. Then, from the start of cooling (C), the molding dies 1 and 2 are passed through cooling pipes (not shown) of the temperature control plates 7 and 8 by flowing water or air or water and air at a predetermined mixing ratio. Cool, resin 2
1 is cooled below the heat distortion temperature. At this time, since the temperature in the vicinity of the cavity is higher than the heat radiation block 6 side, the heat generated by the resin 21 in the cavity is
The heat is transmitted through the heat radiation block 6 through the heat radiation fins 14f through the heat radiation fins 14f. In the present embodiment, the amount of heat radiation from the resin 21 in the cavity is set according to the size of the resin 21 based on the cavity shape, that is, the difference in wall thickness. That is, the heat pipe 14a having a large diameter promotes a thick portion (both ends), and the heat pipe 14b having a small diameter suppresses a thin portion (central portion). On the other hand, in the heat radiation block 6, the amount of air blown is adjusted by controlling the number of rotations of the fan by the air volume adjusting device 20 based on the detection information of the vicinity of the cavity by the temperature detecting means 18, and the amount of heat radiation from the resin 21 is finely adjusted I do. Thus, the resin 21 in the cavity is
Uniform cooling is performed from each part. In addition, the thermal emissivity adjustment means (the synthetic resin film,
With respect to the paint surface, the processed finish surface having an uneven shape, etc.) 15, the optimal heat emissivity is set according to the distance from the cavity 5 to the surface of the molding die 2 and the volume of the resin 21 in the cavity 5. Therefore, efficient cooling is performed not only in the heat dissipation block 6 but also from the surface of the heat dissipation block 6. Therefore, even when the thickness distribution of the cavity 5 is unbalanced and the distance from the cavity 5 to the surface of the molding die 2 is long as in the present embodiment, the cooling rate in each part becomes uniform, and the efficiency is improved. The cooling cycle shortens the molding cycle.

Next, after the mirror surface is transferred to the resin 21 in the cavity and the cooling and solidification of the resin 21 is completed, the molds 1 and 2 are opened by the mold clamping mechanism 13 to remove the molded product from the cavity 5. Take out. In the present embodiment, the cooling control is performed during the period from the start of cooling (C) to the opening of the mold (D). According to the present embodiment, from the vicinity of both end portions (thick portion) of the cavity 5 to the inside of the heat radiation block 6,
A heat pipe 14a having a large diameter is provided, and a heat pipe 14b having a small diameter is provided from the vicinity of the center (thin portion) of the cavity 5 to the inside of the heat radiation block 6, and a heating member 14d is provided at an end of the cavity side. Therefore, in the heating control step, the heating temperature is partially changed so that the amount of heat supplied to the vicinity of the center of the cavity by the heating member 14d is larger than the amount of heat supplied to the vicinity of both ends, and the vicinity of the cavity is changed. Heat is heat pipe 14a, 1
4b, it is possible to suppress heat radiation to the heat radiation block 6 and to control the temperature distribution according to the cavity shape. In the cooling control step, when the temperature near the cavity is higher than the inside of the heat radiating block 6, the heat fins 14f are provided at the ends of the heat pipes 14a and 14b in the heat radiating block. In the heat radiation, the heat radiation from both ends of the cavity is promoted more than the heat radiation from the central portion, and the heat is transmitted through the heat pipes 14a and 14b and continues to be radiated into the heat radiation block 6, so that uniform cooling is performed in each part. In this manner, the heat radiation amount adjustment by the heat radiation block 6 is promoted for a thick portion having a large volume according to the volume of the resin 21 in the cavity based on the detection information of the temperature detecting means 18 provided in the vicinity of the cavity. However, since the control is performed so as to suppress the thin portion having a small volume, uniform cooling of the entire molded article can be efficiently realized. Therefore, it is possible to suppress the deterioration of the shape accuracy and the occurrence of optical distortion, to obtain a high-precision plastic molded product, and to shorten the molding cycle.

Further, according to the present embodiment, the heat radiation block surface portion has a thermal emissivity adjusting means including a synthetic resin film surface, a paint surface, and a finished surface, and is adapted to the volume of the resin in the cavity. Since the thermal emissivity is set, the heat radiation from the resin 21 in the cavity can be easily and efficiently dissipated. In the present embodiment, the heat radiation block 6 is arranged between the movable mold 2 and the temperature control plate 8. However, depending on the arrangement of the cavities 5 in the molding dies 1 and 2, the temperature of the molding mold 1 and the temperature regulation plate are adjusted. It may be configured to be mounted between the plates 7 or on other mold surfaces. By doing so, it is possible to flexibly cope with an unbalanced molded product having a complicated shape and a thickness distribution, and uniform cooling can be realized as a whole.

[Second Embodiment] FIG. 8 is a cross-sectional view of a molding die for a plastic molded product according to a second embodiment of the present invention. In FIG. 8, a fixed mold (molding mold)
1. Inside a movable mold (molding mold) 2, a cavity forming member, that is, a fixed input piece 3 and a movable input piece 4, are provided.
The inner peripheral surface of the cavity forming portion has a constant volume, the cavity 5 has a substantially U-shaped cross section, and the center of the cavity is unevenly distributed toward the fixed input piece 3, and the surface of the movable mold 2 extends from the center. The cavity 5 is formed such that the distance to the surface is longer than the distance to the surface of the fixed mold 1. Both sides of the cavity (upper and lower sides in the figure) are bent symmetrically from both ends of the center, and are arranged from the fixed input piece 3 to the movable input piece 4. A mirror surface is formed on the inner peripheral surface forming the cavity 5. Further, a sprue is formed in the fixed mold 1, and a resin melted from a molding nozzle 22 of an injection molding machine is injected and filled into the cavity 5 through the sprue. In the vicinity of the cavities of the fixed input piece 3 and the movable input piece 4, two detecting elements of temperature sensors 18 (= temperature detecting means) are provided. It is configured to detect the temperature of one side.

A heat transfer means 14 is provided in the vicinity of the cavity in the movable input piece 4. This heat transfer means 14
Is inserted into the heat radiation block 6 through the movable mold 2 from the vicinity of the cavity (the inside of the substantially U-shape).
Further, as shown in FIG. 9, a heat pipe 14c for conducting heat generated from the resin 21 in the cavity from the vicinity of the cavity to the outside of the mold according to the volume of the resin 21 in the cavity, as shown in FIG. (= A heat conducting member), a heating member 14e provided at an end of the heat pipe 14c on the cavity side (A portion of the heat pipe 14c), and a die outside of the heat pipe 14c (inside the heat radiation block 6). And a radiation fin 14g (= radiation member) provided on the B portion of the heat pipe 14c). The heat pipe 14c is a sleeve-type heat pipe having a space in the center, and heats the heat from the vicinity of the cavity (inside of the substantially U-shape) to the heat radiation block 6 so as to be promoted. From the vicinity of the portion to the inside of the heat dissipation block. The heating member 14e is composed of a split type cartridge heater, is buried in the hollow portion of the heat pipe 14c, and heats the vicinity of the cavity with a current supplied from the current control unit 19 (= heating control means). The current control unit 19 controls the heating member 14e based on the detection information of the temperature detection unit 18 so that the center and both sides of the cavity are efficiently heated in accordance with the volume of the resin 21 in the cavity. Since the supply current is controlled, fine and wide-ranging temperature control is possible. Further, since the plurality of radiation fins 14g shown in FIG. 9 are made of a material having a high thermal conductivity such as aluminum,
c promotes the dissipation of the heat conducted from the vicinity of the cavity into the heat dissipation block.

The heat radiation block 6 is provided with a movable mold 2.
, And connected to the heat transfer means 14, and the heat pipes 14 a, 1
4b is inserted, and a radiation fin 14g is provided at the end of the heat pipe 14c as described above. The cooling medium (air) is provided in the heat radiation block 6.
A space 6a is provided so as to easily circulate, and a surface portion (four surfaces) other than in contact with the movable mold 2 and the temperature control plate 8
All have a plurality of minute ventilation holes 6b. The ventilation holes 6b can be selectively sealed by a sealing material 6c, and can be combined with the air volume adjustment by the air volume adjusting device 20 to allow the heat transfer means 14 having the heat pipes 14c and the radiation fins 14g. Can be finely adjusted. In addition, the control unit (not shown) of the air volume adjusting device 20 controls to change the rotation speed of the blowing fan based on the detection information from the temperature detecting unit 18.
For example, when the resin 21 filled in the cavity 5 is cooled, the amount of air blown to the heat radiation block 6 is increased so that heat radiation from the vicinity of the cavity (the inside of the substantially U-shape) is promoted. Alternatively, the resin 2 in the cavity
The amount of air blow is changed according to the change of the resin material constituting 1.

Temperature control plates 7 and 8 are provided on the outer periphery of the fixed mold 1 and the heat radiation block 6, respectively. Inside the temperature control plates 7 and 8, heaters and cooling pipes are provided, respectively. (Not shown). The heater is a rod-shaped heater, the cooling pipe is a pipe for flowing water or air or water and air at a predetermined mixing ratio, and the fixed mold 1 is heated and cooled by the heater and the cooling pipe. . In addition, movable mold 2
Is heated and cooled by the heater and the cooling pipe through the heat radiation block 6. Thereby, the temperature can be adjusted from the mold clamping direction.

Die plates 11 and 12 are attached to the temperature control plates 7 and 8 via heat insulating plates 9 and 10, and a mold clamping mechanism 13 is attached to the die plate 12 side. The mold clamping mechanism 13 moves the die plate 12, the heat insulating plate 10, the heat radiating block 6, and the movable mold 2 with respect to the die plate 11, the heat insulating plate 9, and the fixed mold 1 in the horizontal direction in FIG. Is opened and closed, and the movable mold 2 is pressed against the fixed mold 1 to generate a predetermined mold clamping force.

Further, similarly to the first embodiment, the heat radiation is performed so that the thermal emissivity of the surface of the heat radiation block 6 (four surfaces except the surface in contact with the temperature control plate 8 and the movable mold 2) becomes larger. The thermal emissivity adjusting means 1 is provided on the four surfaces of the block 6.
5 are provided. Specifically, the thermal emissivity adjusting means 1
5 is to apply a synthetic resin film of a predetermined color and thickness, to provide a processed surface having fine irregularities formed on the four surfaces to adjust the surface roughness, or to apply a predetermined color paint. To form a paint surface coated with a predetermined thickness,
Thus, the emissivity of the heat radiation block surface is set according to the volume of the resin 21 in the cavity.

Next, a method of molding a plastic molded article according to the present embodiment will be described. First, after the molds 1 and 2 are clamped by the clamp mechanism 13, the temperature control plates 7 and
8, the temperature of the molding dies 1 and 2 is raised to a temperature equal to or higher than the glass transition point of the resin 21 by a heater (not shown) to increase the resin flow. The filled resin 21 is filled. In the present embodiment, as shown in FIG. 7, the heating member 14e heats the end near the cavity of the heat pipe 14c from the start of heating (A) to the injection and filling of the molten resin (B). . Thus, it is possible to prevent the heat in the vicinity of the cavity from being transmitted through the heat pipe 14 c and being continuously radiated in the heat radiation block 6. Further, upon heating by the heating member 14e, the current control unit 19 uniformly heats the entire inside of the substantially U-shape in accordance with the volume of the resin 21 in the cavity based on the detection information of the vicinity of the cavity by the temperature detecting means 18. Temperature control so that

Then, after the injection and filling of the molten resin, heating is continued until the temperature of each part becomes uniform based on the detection information of the vicinity of the cavity by the temperature detecting means 18, and after the uniformity of the temperature of each part is confirmed. , Heating member 1 by current control unit 19
The power supply to 4e is stopped. Therefore, (A) to (C)
During this period, heating control is performed. Then, from the start of cooling (C), the molding dies 1 and 2 are passed through cooling pipes (not shown) of the temperature control plates 7 and 8 by flowing water or air or water and air at a predetermined mixing ratio. Cool, resin 2
1 is cooled below the heat distortion temperature. At this time, since the temperature in the vicinity of the cavity is higher than that of the heat radiation block 6, the heat generated by the resin 21 in the cavity is reduced by the heat pipe 14c.
Through the heat dissipation block 6 and the heat dissipation fins 14
e continue to emanate. In the present embodiment, the amount of heat radiation from the resin 21 in the cavity is set according to the volume of the resin 21 based on the cavity shape. That is, the heat pipe 14c promotes heat radiation from the vicinity of the central portion where the distance to the movable mold 2 is long. On the other hand, in the heat radiation block 6, the amount of air blown is adjusted by controlling the number of rotations of the fan by the air volume adjusting device 20 based on the detection information of the vicinity of the cavity by the temperature detecting means 18, and the amount of heat radiation from the resin 21 is finely adjusted I do. Thus, uniform cooling is performed from each part of the resin 21 in the cavity. In addition,
Regarding the thermal emissivity adjusting means (the synthetic resin film, the paint surface, the finished surface having irregularities, etc.) 15 on the surface of the heat radiation block 6, the distance from the cavity 5 to the surface of the molding die 2 and the inside of the cavity 5 Since the optimal heat emissivity is set according to the volume of the resin 21, efficient cooling is performed not only in the heat dissipation block 6 but also from the surface of the heat dissipation block 6. Therefore, even when the cavity 5 is substantially U-shaped in cross section and the center of the cavity is unevenly distributed toward the fixed input piece 3 as in the present embodiment, the distance from the center of the cavity to the surface of the movable mold 2 is long. The cooling rate in each part becomes uniform, and the molding cycle is shortened by efficient cooling.

Next, the mirror surface is transferred to the resin 21 in the cavity, and after the resin 21 is cooled and solidified, the molds 1 and 2 are opened by the mold clamping mechanism 13 to remove the molded product from the cavity 5. Take out. In the present embodiment, the cooling control is performed during the period from the start of cooling (C) to the opening of the mold (D). According to the present embodiment, from the vicinity of the center of the cavity 5 (the inside of the substantially U-shape), the heat radiation block 6
In the heating control step, the heating members 14e are heated so that heat is uniformly supplied to the respective parts of the cavity by providing the heat pipes 14c and the heating members 14e at their cavity side ends. By controlling the temperature, heat in the vicinity of the cavity is prevented from being transmitted to the heat radiating block 6 through the heat pipe 14c, and the temperature distribution can be controlled according to the shape of the cavity. Further, a radiation fin 14g is provided at an end of the heat pipe 14c in the heat radiation block. (Inside) is promoted, and the heat is continued to be radiated into the heat radiation block 6 through the heat pipe 14c, so that uniform cooling is performed in each part. As described above, the heat radiation amount is adjusted by the heat radiation block 6 according to the volume of the resin 21 in the cavity based on the detection information of the temperature detecting means 18 provided in the vicinity of the cavity, and the distance from the surface of the movable mold 2 is long. Since the control is performed so as to accelerate the part, uniform cooling can be efficiently realized for the entire molded article. Therefore, it is possible to suppress the deterioration of the shape accuracy and the occurrence of optical distortion, to obtain a high-precision plastic molded product, and to shorten the molding cycle.

Further, according to the present embodiment, the heat radiation block surface portion has a thermal emissivity adjusting means including a synthetic resin film surface, a paint surface, and a processed surface, and is adapted to the volume of the resin in the cavity. Since the thermal emissivity is set, the heat radiation from the resin 21 in the cavity can be easily and efficiently dissipated. In the present embodiment, the heat radiation block 6 is arranged between the movable mold 2 and the temperature control plate 8. However, depending on the arrangement of the cavities 5 in the molding dies 1 and 2, the temperature of the molding mold 1 and the temperature regulation plate are adjusted. It may be configured to be mounted between the plates 7 or on other mold surfaces. By doing so, it is possible to flexibly cope with an unbalanced molded product having a complicated shape and a thickness distribution, and uniform cooling can be realized as a whole.

[0030]

As described above, according to the present invention,
The heat transfer means penetrates the molding die from the vicinity of the cavity to the outside of the mold, conducts heat from the resin in the cavity and radiates it, and heats the vicinity of the cavity so as to have a temperature distribution according to the cavity shape. Therefore, the temperature near the cavity can be efficiently and accurately controlled. More specifically, in the heat conducting member, in the cooling control step, heat generated from the resin is conducted from the vicinity of the cavity to the outside of the mold, and the heating member provided at the cavity side end of the heat conducting member, In the heating control step, it is possible to heat a desired portion to a desired temperature in accordance with the cavity shape, to prevent molding distortion, and to obtain a highly accurate molded product.

Further, according to the present invention, based on the detection information indicating the temperature of the resin in the cavity obtained by the temperature detecting means, the heating control means (= current control unit) controls the heating by the heating member. , The temperature near the cavity can be efficiently and accurately controlled in the heating control step.
Further, according to the present invention, the heat conduction member is formed of a cylindrical heat pipe, and the heating member is formed of any one of a ring heater, a silicon rubber heater, and a tape heater. Excellent in nature. That is, since the ring heater has a brass cast structure that can be machined, it has high thermal conductivity and can flexibly change the shape of the outer peripheral portion according to the cavity shape of the molded product. Therefore, the vicinity of the cavity can be effectively heated. Further, the silicon rubber heater is a planar heater and is wired in a plurality of parallel circuits. Therefore, even if a part of the circuit is broken, heating can be continued in the remaining circuit. Furthermore, the tape heater has good thermal efficiency because its surface is formed of aluminum foil and is thin. Moreover, since the mounting method is an adhesive type, mounting is easy.

Further, according to the present invention, a plurality of the heating members are provided, and each of the heating members is independently controlled by the heating control means. Heating can be controlled with high accuracy. Further, according to the present invention, a sleeve-type heat pipe is used as the heat conducting member, and a heating member including a split-type cartridge heater is provided in a hollow portion thereof. The heating can be controlled efficiently and accurately.

Further, according to the present invention, a heat pipe having a large diameter is disposed for a portion where the volume of the resin in the cavity is large, and a heat pipe having a small diameter is disposed for a portion where the volume of the resin in the cavity is small. Since the pipes are arranged, in the cooling control step, the heat radiation of the thick part is promoted more than that of the thin part, and the heat near the cavity is actively dissipated, and uniform and quick cooling can be realized. . Further, according to the present invention, since a plurality of radiation fins (= radiation member) made of a material having high thermal conductivity are provided at the outer end of the mold of the heat conduction member, the cooling control step includes: The heat in the vicinity of the cavity can be efficiently and accurately dissipated.

According to the present invention, the temperature of the resin in the cavity is detected by the heat radiation adjusting means (heat radiation block) connected to the heat transfer means and arranged so as to be in contact with the surface of the mold. Since the amount of heat radiation from the resin in the cavity is adjusted based on the information, the temperature in the vicinity of the cavity can be efficiently and accurately controlled together with the heat transfer means. Therefore, molding distortion can be prevented and a highly accurate molded product can be obtained.

Further, according to the present invention, in the heating control step, the vicinity of the cavity is heated by the heating member based on the detection information so as to have a temperature distribution corresponding to the shape of the cavity. When it is necessary to raise the temperature above the glass transition point or to keep the mold temperature constant, it is possible to prevent a rise in the temperature or a decrease in the efficiency of heat retention.

Further, according to the present invention, in the heating control step, the heating of the thin part is promoted more than the thick part, and in the cooling control step, the cooling of the thick part is promoted more than the thin part. The temperature in the vicinity of the cavity can be controlled efficiently and precisely, and even for molded products with complicated shapes and unbalanced thickness distribution, high-precision molded products can be obtained by suppressing molding distortion. be able to.

According to the present invention, in the cooling control step, the heat radiation amount adjusting means promotes heat radiation from the thick portion conducted by the heat conducting member based on the detection information, and Since the amount of heat radiation is adjusted so as to suppress heat radiation from the part, the temperature near the cavity can be efficiently and accurately controlled. As described above, according to the present invention, when molding a plastic, the temperature of the mold is raised to a temperature equal to or higher than the glass transition point, or when the mold temperature needs to be kept constant, the temperature near the cavity is reduced. Can be controlled efficiently and accurately.

[Brief description of the drawings]

FIG. 1 is a sectional view of a molding die for a plastic molded product according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a heat transfer means 14 in FIG.

FIG. 3 is a diagram showing a configuration of a heating member 14d in FIG.

FIG. 4 is a diagram showing a change in a cooling rate due to sticking of a black film.

FIG. 5 is a diagram showing the thermal emissivity for each color of a synthetic resin film.

FIG. 6 is a diagram showing thermal emissivity for each color of paint.

FIG. 7 is a diagram showing temperature control in the method for molding a plastic molded product according to the first embodiment of the present invention.

FIG. 8 is a sectional view of a plastic molding die showing a second embodiment of the present invention.

9 is a diagram showing a configuration of the heat transfer means 14 in FIG.

[Explanation of symbols]

 Reference Signs List 1 fixed mold 2 movable mold 3 fixed input piece 4 movable input piece 5 cavity 6 heat dissipation block 14 heat transfer means 14a, 14b, 14c heat pipe 15 heat emissivity adjustment means 14d, 14e heating member 14f, 14g radiation fin 18 temperature Detecting means 19 Current control unit 20 Temperature adjusting device 21 Resin

Claims (12)

[Claims] 1. A molding die for a plastic molded product which is integrally joined to inject and fill a molten resin, and then forms a cavity for solidification by cooling. The molding die penetrates the molding die from near the cavity. Provided outside,
A plastic characterized in that it has heat transfer means for conducting heat generated from the resin filled in the cavity to the outside of the mold and dissipating the heat, and for heating the vicinity of the cavity so as to have a temperature distribution according to the shape of the cavity. Mold for forming molded products. 2. The heat transfer means includes: a heat conducting member that conducts heat generated from the resin from the vicinity of the cavity to the outside of the mold; a heating member provided at a cavity side end of the heat conducting member; The molding die for a plastic molded product according to claim 1, comprising: 3. A temperature detecting means provided in the vicinity of the cavity for detecting a temperature of a resin in the cavity, and a heating control means for controlling heating by the heating member based on detection information of the temperature detecting means. The molding die for a plastic molded product according to claim 2, comprising: 4. The heat conduction member according to claim 3, wherein the heat conduction member comprises a cylindrical heat pipe, and the heating member comprises any one of a ring heater, a silicon rubber heater, and a tape heater. Mold for plastic molded products. 5. The heating member is provided at a plurality of end portions on the cavity side of the heat conducting member, and the heating control means includes:
5. The mold according to claim 4, wherein each of the plurality of heating members is independently controlled. 6. The heat conduction member according to claim 3, wherein the heat conduction member comprises a sleeve type heat pipe, and the heating member comprises a split type cartridge heater provided in a hollow portion of the heat pipe. Mold for plastic molded products. 7. A heat pipe having a large diameter is disposed in a portion where the volume of resin in the cavity is large, and a heat pipe having a small diameter is disposed in a portion where the volume of resin in the cavity is small. 7. A molding die for a plastic molded product according to claim 4, wherein: 8. A heat radiation member having a heat radiation member at an end of the heat conduction member outside the mold, wherein the heat radiation member comprises a plurality of heat radiation fins made of a material having a high thermal conductivity. Item 7. A molding die for a plastic molded product according to any one of Items 2 to 7. 9. A space connected to the heat transfer means and provided in contact with the surface of the mold for circulating a cooling gas, and a plurality of ventilation holes formed in a surface covering the space. And a heat radiation adjusting means for adjusting the amount of heat released from the resin by selectively sealing the gas flow rate and the vent based on the detection information of the temperature detecting means. 9. A molding die for a plastic molded product according to any one of claims 8 to 8. 10. A molding die for a plastic molded product which is integrally joined, injects and fills a molten resin, and then forms a cavity for solidification by cooling. The molding die penetrates the molding die from near the cavity. A heat conductive member provided over the outside and conducting heat generated from the resin in the cavity from the vicinity of the cavity to the outside of the mold; a heating member provided at a cavity side end of the heat conductive member; And a temperature detecting means for detecting the temperature of the resin in the cavity. The method according to claim 1, further comprising: heating the pair of molding dies in which the cavities are formed. A heating control step of injecting and filling the molten resin into the inside and heating until the temperature of each part becomes uniform; A cooling control step of transferring the mirror surface formed on the peripheral surface to the resin to solidify the resin, wherein in the heating control step, the temperature according to the cavity shape is determined based on the detection information of the temperature detecting means. A method for molding a plastic molding die, wherein the vicinity of the cavity is heated by the heating member so as to be distributed. 11. The heat conduction member is arranged corresponding to a thick portion where the volume of the resin in the cavity is large and a thin portion where the volume of the resin in the cavity is small. 11. The molding of a plastic molding die according to claim 10, wherein the heating of the thin part is promoted more than the thin part, and in the cooling control step, the temperature is controlled so as to promote the cooling of the thick part more than the thin part. Method. 12. A heat radiation adjusting means which is connected to the heat transfer means and is provided in contact with a surface of a mold, and adjusts heat dissipation from the resin conducted by the heat conduction means. In the cooling control step, the heat radiation amount adjusting means promotes the heat radiation from the thick part transmitted by the heat conducting member based on the detection information of the temperature detecting means, and suppresses the heat radiation from the thin part. The method for molding a plastic molding die according to claim 11, wherein a heat radiation amount is adjusted so as to perform the heat radiation.