JPH0671707A - Compression correcting method for injection compression molding method - Google Patents

Abstract

PURPOSE:To enhance a molding accuracy of a molded form in a method for molding by an injection compression mold having a stationary mold, a movable mold and a slidable mold. CONSTITUTION:A cavity 15 is formed of a lower core 4 of a lower mold 1 of a stationary mold, an upper core 6 of an upper mold 2 of a movable mold, and a slidable mold 14 moving horizontally in cooperation with vertical movements of the mold 2 by a cam 18. Before melted resin is injected and filled in the cavity 15, when the cavity 15 is increased by retracting the core 6, the mold 14, the melted resin is injected to be filled, the core 6, the mold 14 are advanced to pressurize, compress the resin, temperature control fluid is fed to the mold 14 thereby to thermally deform the mold 14 to correct the pressurization, compression of the resin, thereby obtaining an accurately molded form.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of performing compression correction in an injection compression molding method, and can be used when molding a precision molded product such as an optical component.

[0002]

BACKGROUND ART A fixed die, a movable die that is arranged to face the fixed die and is movable back and forth with respect to the fixed die, and is slidable in a direction (for example, a right angle direction) that makes an angle with the moving direction of the movable die. When performing injection compression molding using a mold having a slide mold that moves forward and backward in conjunction with the movement of a movable mold, before filling the molten resin into the cavity formed by these molds, The movable mold and slide mold are retracted to expand the cavity, the molten resin is injected and filled into the cavity, and then the movable mold and slide mold are moved forward. The pressurization and compression are performed while following them. Conventionally, the mechanism for moving the slide die forward and backward in conjunction with the movement of the movable die is constituted by a cam provided on the movable die, and when the movable die moves forward, the slide die also moves due to the pressing action of the inclined surface of the cam. It is designed to move forward.

[0003]

When the molded product is an optical component such as a polygon mirror for scanning a laser beam, the required molding accuracy is extremely high, and pressing by the slide type forward movement is performed. The surface accuracy of the surface to be compressed must be highly accurate with an error of 1 μm or less.
When the slide die is moved forward when the movable die is moved forward by the interlocking mechanism composed of the cam, the error that this interlocking mechanism has is larger than the molding accuracy of the molded article, so that the molded article is required. It is not possible to mold with sufficiently high precision. In addition, the surface of the molded product that is pressed by the slide mold is deformed so that the central portion bulges due to the pressure applied by the movable mold, and this deformation cannot be solved by the interlocking mechanism by the cam.

It is conceivable that the slide type advancing / retreating may be performed not by a cam interlocking mechanism but by a control device such as a cylinder. However, this requires a large number of parts and therefore the structure is complicated. Therefore, the problem of cost increase occurs. Further, the advance of the slide mold cannot be accurately controlled to the extent that the above-mentioned high precision molding can be achieved, and the molded product is prevented from bulging at the center of the surface of the molded product that is pressed by the slide mold. Can not be molded.

An object of the present invention is to provide an injection compression molding method in which a mechanical interlocking mechanism such as a cam having a simple structure can be used and the molding accuracy of a molded product can be made sufficiently high to a required degree. There is provided a compression correction method in.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a fixed die, a movable die which is disposed so as to face the fixed die and is movable back and forth with respect to the fixed die, and a movable die which forms an angle with a moving direction of the movable die. A cavity is formed by a movable movable die and a slide die that moves back and forth in conjunction with the movement of the movable die, and the movable die and the slide die are retracted before the molten resin is injected and filled into the cavity. In the injection compression molding method of filling the molten resin into the cavity expanded by, moving the movable mold and the slide mold to pressurize and compress the molten resin,
When the movable die and the slide die are moved forward, a temperature control fluid is circulated through the slide die, so that the temperature control fluid causes the slide die to thermally deform into a shape capable of obtaining a highly accurate molded product. It is characterized in that the pressurization and compression of the molten resin by the slide mold necessary for molding a high precision molded product are corrected.

[0007]

Operation Before the continuous production of the molded product by the continuous injection molding cycle, the molded product is trial molded by the trial production work. By this trial molding, the error of the molded product is examined, and the temperature, the flow rate, the circulation time and the like of the temperature control fluid to be circulated in the slide die when advancing the slide die are determined based on the result. As a result, the amount of thermal deformation of the slide mold necessary for molding the high-precision molded product is obtained, and the molded product obtained by the continuous injection molding cycle is sufficiently accurately molded to the required degree.

[0008]

An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 to 3 are sectional views showing a mold for carrying out the method according to the present embodiment in the order of operation thereof. This mold is for injection compression molding of an optical component such as a polygon mirror, and has a lower mold 1 and an upper mold 2. As shown in FIG. 3, the lower mold 1 is an immovable fixed mold, and the upper mold 2
Is a movable type that moves up and down.

The lower mold 1 comprises a mold body 3 and a lower mold core 4 fixed to the mold body 3. The upper mold 2 is the mold body 5
And an upper mold core 6 which is vertically movable in the mold body 5.
And a support member 7 provided on the upper part of the mold body 5,
The mold body 5 is a bolt 8 slidably inserted in the support member 7.
Is attached to the support member 7 so as to be vertically movable, and
The mold body 5 is constantly urged downward by a spring 9,
A gap S for the compression margin is formed between the mold body 5 and the support member 7. The mounting plate 7A provided on the upper surface of the support member 7 is attached to a mold clamping device (not shown), and the upper mold 2 is moved up and down by the mold clamping device to open and close the mold. .

A cutter member 10 is hung and fixed on the support member 7, and the cutter member 10 is vertically movably inserted into the upper die core 6. A pressure receiving member 11 is arranged on the support member 7 above the cutter member so as to be vertically movable, and the pressure receiving member 11 has two eject pins 12 extending downward.
The upper ends of 13 are joined. The eject pin 12 is inserted into the support member 7 and the lower end thereof is coupled to the upper die core 6, and the eject pin 13 is inserted into the cutter member 10 and reaches the inside of the upper die core 6. The pressure receiving member 11 is constantly urged upward by a spring (not shown), so that the eject pins 12, 13 and the upper die core 6 are always urged upward.

Inside the die main body 5 of the upper die 2, between the lower die core 4 and the upper die core 6 when the die is clamped, and on the lateral outer sides of these cores 4, 6, A slide die 14 is arranged, and four slide dies 14 are provided in each of the front, rear, left and right sides in total. A space surrounded by the lower mold core 4, the upper mold core 6 and the slide mold 14 is a molten resin filling cavity 15. Each slide mold 14 is slidable in the horizontal direction, which is a direction that makes an angle with the vertical direction, which is the moving direction of the upper mold 2, and the mold body 5 is provided at the rear end of each slide mold 14. The bolt 16 that is slidably inserted in the
The slide die 14 is constantly urged in the backward direction by the spring 17 acting on.

A cam 18 is hung and fixed on the lower surface of the support member 7. The cam 18 is provided for each slide mold 14, and the lower end portion thereof forms an inclined surface 18A. The slide mold 14 is provided with a sloped surface corresponding to the sloped surface 18A, and the cam 18 presses the slide mold 14 toward the cavity 15 to move forward. The cam 18 constitutes an interlocking mechanism for advancing and retracting the slide die 14 in conjunction with the upper die 2.

A temperature control circuit 19 is provided inside each of the slide molds 14. The temperature control circuit 19 is a passage for passing a temperature control fluid such as air, water or steam, and the temperature control circuit 19 is provided. A temperature control fluid supply source is connected to.

Next, the operation will be described. The upper mold 2 is lowered by the mold clamping device to be combined with the lower mold 1, and the mold is clamped until the gap S disappears as shown in FIG. Next, before the nozzle of an injection molding machine (not shown) is brought into contact with the lower die core 4 which is also a spool bush to inject and fill the cavity 15 with the molten resin, the upper die 2 is slightly raised by the die clamping device. As shown in FIG. 2, the mold body 5 of the upper mold 2
While making the spring 9 contact the mold body 3 of the lower mold 1 with the spring 9,
A gap S is provided between the support member 7 and the support member 7. When the support member 7 is raised by S in this way, the upper die core 6 is raised via the pressure receiving member 11 and the eject pin 12, and the cam 18
The slide die 14 is retracted by the urging force of the spring 17 due to the rise of the. Therefore, the cavity 15 expands. After the cavity 15 is expanded in this way, molten resin is injected into the cavity 15 from the nozzle of the injection molding machine. The molten resin injected and filled into the cavity 15 gradually cools while contracting. Therefore, the supporting member 7 is lowered by the mold clamping device, which causes the upper core 6 through the pressure receiving member 11 and the eject pin 12. And the slide mold 14 is advanced by the cam 18 to pressurize and compress the molten resin in the cavity 15.

At this time, a temperature control circuit provided on the slide mold 14.
A temperature control fluid is circulated through the temperature control fluid 19, the slide mold 14 is thermally deformed by the temperature control fluid, and the slide mold 14 causes a cavity 15
While pressurizing and compressing the molten resin inside, the pressurization and compression of the molten resin are corrected by the amount of thermal deformation of the slide mold 14, and the slide mold 14 in the molded product obtained in the cavity 15 is corrected.
The surface pressed by is set to have high surface accuracy.

To explain this in detail, before the continuous production of molded products by the continuous injection molding cycle, trial production is performed, the molded products produced by this trial production are precisely inspected, and the front surface of the slide mold 14 is tested. Check the flatness of the surface to be molded with. The molding error of this surface is, for example, slide type
This is based on the processing error of 14 itself, the processing error of the cam 18 that constitutes the interlocking mechanism for moving the slide mold 14 in conjunction with the movement of the support member 7 of the upper mold 2, and the like. When a precision inspection of the molded product obtained by trial production is performed, it is found out how to deform the slide mold 14 in order to produce a molded product with sufficiently high accuracy to the required degree, From this, the temperature, the flow rate, the flow time, etc. of the temperature control fluid to be passed through the temperature control circuit 19 of the slide mold 14 are determined.

The flow condition of the temperature control fluid determined in this way is carried out during continuous production of the molded product by the continuous injection molding cycle, and the temperature control fluid causes the slide mold 14 to have a shape capable of obtaining a highly accurate molded product. Heat deformation is performed, and by the amount of this heat deformation, when the molten resin is contracted and cooled, pressure and compression by the slide mold 14 are corrected to produce a high precision molded product. For example, when the central portion of the surface of the molded product that is pressed by the front surface of the slide mold 14 swells outward by the pressing action from above and below by the lower mold core 4 and the upper mold 2 core 6, heating fluid is supplied to the temperature control circuit 19. This bulge is suppressed by circulating and bulging the central portion of the front surface of the slide mold 14,
The surface accuracy of molded products is high. Slide type like this
The pressurization and compression of the molten resin performed by the thermal deformation of 14 can be corrected with an accuracy of 1 μm or less.

Although only one temperature control circuit 19 is shown in each slide mold 14 in the drawing, the number of this temperature control circuit may be plural, and the arrangement position thereof is arbitrarily determined and each temperature control circuit 19 is set. By properly setting the type, temperature, flow rate, etc. of the temperature control fluid to be circulated in the control circuit, the slide mold 14 can be deformed by heat more precisely, which enables highly accurate molding of the molded product. Can be achieved.

After the molten resin in the cavity 15 is cooled and solidified into a molded product, as shown in FIG.
Then, the pressure receiving member 11 is lowered by the operating member 20 of the ejecting device, and the ejected pins 12, 13 and the upper die core 6 are lowered to push out the molded product 21 from the cavity 15.

Although the opening and closing direction of the mold is vertical in the above-described embodiment, the present invention can be applied even when the opening and closing direction is horizontal, and the number of slide molds 14 in the above-described embodiment is also applicable. However, the number of slide type is not limited to this, and the sliding direction of the slide type is not limited to the direction perpendicular to the moving direction of the movable type, and the slide type with respect to the moving direction of the movable type is not limited. The sliding direction may be an arbitrary angle.

Further, in the above embodiment, the lower mold 1 and the upper mold 2 are provided with the lower mold core 4 and the upper mold core 6, but the present invention can be applied to the case where these cores are not provided. .

[0022]

According to the present invention, the molding accuracy of a molded product can be made sufficiently high to the extent required by thermal deformation of the slide die, and the interlocking mechanism moves the slide die in conjunction with the movement of the movable die. Can be configured by a mechanical mechanism such as a cam having a simple structure, and the cost of the mold can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a mold clamped state of a mold used for carrying out a method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the mold when the cavity is enlarged.

FIG. 3 is a cross-sectional view showing a mold when the mold is opened to take out a molded product.

[Explanation of symbols]

 1 Lower mold which is a fixed mold 2 Upper mold which is a movable mold 3 Lower mold body 4 Lower mold core 5 Upper mold body 6 Upper mold core 7 Support member 12, 13 Eject pin 14 Slide mold 15 Cavity 21 Molded product

Claims (1)

[Claims] 1. A fixed die and a fixed die, which are arranged to face each other,
A cavity is formed by a movable die that can move forward and backward with respect to a fixed die and a slide die that can slide in a direction that forms an angle with the moving direction of the movable die and that moves forward and backward in conjunction with the forward and backward movement of the movable die. Before the injection molding of the molten resin into the cavity, the movable mold and the slide mold are retracted to expand the cavity. After the injection of the molten resin into the cavity, the movable mold and the slide mold are advanced. In the injection compression molding method of pressurizing and compressing the molten resin, a temperature control fluid is circulated through the slide mold when the movable mold and the slide mold are advanced, and the slide mold is highly accurately moved by the temperature control fluid. Thermally deform the molded product into a shape,
A compression correction method in an injection compression molding method, wherein the amount of thermal deformation corrects the pressurization and compression of the molten resin by the slide mold necessary for molding the high-precision molded product.