JPH1142684A - Injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding method, in which a time required for solidifying by cooling down and hole marks made on the surface of the product part of a molded article by ejecting pins are eliminated and, at the same time, both the strain at the release from a mold and the residual stress can be reduced. SOLUTION: At the start or after the finish of a process for releasing some part of the product part 30a of a molded article 30 and its peripheral part 30b from a movable mold 20, under the state that the peripheral part 30b closely contacts with the tips of ejecting pins 27 and 28 and the surface of the product part 30a contacts only with the major surface of an insert 22 corresponding to the surface of the product part, by further sliding only the ejecting pins 27 and 28 closely contacting with the peripheral part 30b to the ejecting direction of the molded article 30, the product surface of the molded article 30 is separated from the major surface of the insert 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method for injecting a heat-melted resin into a molding die for molding.

[0002]

2. Description of the Related Art Conventionally, when a resin product is manufactured, a resin as a material is heated and melted, and then injected into a molding die corresponding to the shape of the product to be cooled and solidified. Injection molding methods for molding by the method are widely used.

A conventional injection molding apparatus for producing a resin product by such an injection molding method will be briefly described below. FIG. 3 is a schematic sectional view showing the configuration of a conventional injection molding apparatus. In FIG. 3, reference numeral 10 denotes a fixed mold which is a fixed mold of a pair of molds constituting the mold,
12 is an insert prepared according to the product shape and incorporated into the fixed mold 10 side, 14 is a sprue into which a resin melted by heating and injected is poured, and 20 is a pair of molds constituting a mold. A movable mold having a movable part, 2
2 is an insert prepared corresponding to the product shape and incorporated in the movable mold 20 side, 24 is a resin flow path comprising a runner and a gate provided in the movable mold 20 side, 25
Indicates that the resin flow path 24 is formed and the insert 2
2 is incorporated, and 27 and 28 are movable molds 2.
A protruding pin which is a movable portion of the movable mold 0 and protrudes from the movable mold 20 to release the molded product 30 from the movable mold 20;
Reference numeral 30 denotes a molded product formed by cooling and solidifying the resin injected into the mold space 40 through the resin flow path 24, and reference numeral 40 denotes a mold space into which the heat-melted resin is injected.

In the conventional injection molding method using the injection molding apparatus having the above-described structure, as shown in FIG. 3 (a), a resin melted by heating and a fixed mold 10 and a movable mold 20 are paired. Into the fixed mold 1 through the sprue 14 and the resin flow path 24.
Inserts 12 and 22 on 0 side and movable mold 20 side
After the resin is cooled, solidified and molded, the movable mold 20 is moved in the direction of the arrow Y1, and the molded product 30 remaining on the movable mold 20 is removed.
As shown in FIG. 3 (b), the sliding operation of the protruding pins 27 and 28 in the direction of the arrow Y2 causes the movable mold 20 to move the arrow Y2.
Remove in three directions.

In such an injection molding method, usually, a molded product 30 formed by cooling and solidifying is molded into a movable molding die 2.
If the protruding pins 27 and 28 for taking out from the position 0 are incorporated into the insert 22 created corresponding to the shape of the product part 30a of the molded product 30, or if they cannot be incorporated into the insert 22, as shown in FIG. Then, it is optimally arranged in the template 25 created according to the shape of the peripheral portion 30b of the molded product 30.

The arrow Y2 of the protruding pins 27, 28
When the molded product 30 is released from the movable mold 20 by the sliding operation in the direction, if the molded product 30 to be taken out is sufficiently cooled and solidified, the molded product 30 can be taken out without causing deformation and distortion.

[0007]

However, in the conventional injection molding method as described above, in actual molding, from the viewpoint of productivity, molding is performed with a long cooling time until the molten resin is completely cooled and solidified. Rarely, when the resin temperature is cooled to a temperature close to the thermal deformation temperature, a protrusion pin incorporated in the insert 22 corresponding to the product portion 30a of the molded product 30 is slid, and the molded product 30 is molded. As a result, when the molded product 30 is protruded, distortion occurs in the molded product 30, a residual stress is generated over time, and an adverse effect is exerted on the molded product. Had the problem of giving.

Particularly, when an optical component such as a lens is manufactured by injection molding, extremely high shape accuracy is required, and reduction of distortion and residual stress is strongly desired. Further, in the transparent optical component, the shape trace of the protruding pin cannot be left on the product surface, so that the protruding pin has to be arranged around the product part, and the same adverse effect on the product as above is likely to occur. There was also a problem that.

The present invention solves the above-mentioned conventional problems, shortens the time required for cooling and solidifying, eliminates a hole mark due to a protruding pin protruding from the surface of a product part of a molded product, and provides a molding die. Provided is an injection molding method capable of reducing distortion and residual stress at the time of release from a mold, and improving productivity and shape accuracy of a molded product.

[0010]

In order to solve the above-mentioned problems, an injection molding method according to the present invention comprises a step of releasing a part of a product part and a peripheral part of a molded product from a molding die after starting or completing the step. In the state where the peripheral portion protrudes and is in close contact with the tip of the pin, and the surface of the product portion is in close contact with only the corresponding main surface of the insert, only the protruding pin that is in close contact with the peripheral portion is slid in the projecting direction of the molded product. By moving, the product surface of the molded product and the main surface of the insert are finally released.

As described above, the time required for cooling and solidifying can be shortened, and the trace of holes caused by the projecting pins on the surface of the product part of the molded product can be eliminated, and the distortion and residual stress when releasing from the molding die can be reduced. Thus, the productivity and the shape accuracy of the molded product can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the injection molding method according to the first aspect of the present invention, a resin that has been heated and melted is injected into a molding die created in accordance with the shape of a product, cooled and solidified, and molded. An injection molding method for removing the molded product from the molding die to obtain the product, wherein the step of removing the cooled and solidified molded product from the molding die includes removing a part of a product portion and a peripheral portion of the molded product. A first step of releasing from the molding die, and after the start or completion of the first step, using a protruding pin provided to a peripheral portion of the molded article, all the product parts in the molded article are removed. And a second step of releasing from the molding die.

According to a second aspect of the present invention, there is provided an injection molding method wherein the step of releasing a part of the product part according to the first aspect is performed without using a protruding pin in an insert corresponding to the product part. I do.

According to a third aspect of the present invention, in the injection molding method, the step of releasing a part of the product part or the step of releasing the entirety of the product part according to the first or second aspect is performed on the product part. The method is executed in a state where the corresponding insert is fixed to the formwork.

According to a fourth aspect of the present invention, there is provided an injection molding method in which a molding die corresponding to the shape of a transparent optical component is used as the molding die according to the first, second, or third aspect.

According to a fifth aspect of the present invention, there is provided an injection molding method in which a resin for a transparent optical component is molded as the resin according to any one of the first to fourth aspects. According to these methods, after the step of releasing the part of the product part of the molded product and the peripheral part from the mold is started or completed, the peripheral part protrudes and comes into close contact with the tip of the pin, and the surface of the product part corresponds thereto. By sliding only the protruding pin that is in close contact with the peripheral part in the protruding direction of the molded product while in contact with only the main surface of the insert, finally, the product surface of the molded product and the main surface of the insert And mold release.

Hereinafter, an injection molding method according to an embodiment of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a sectional view showing a configuration of an injection molding apparatus for realizing the injection molding method of the present embodiment. Here, an injection molding apparatus for molding an optical lens which is a transparent optical component will be described as an example of a product to be molded. FIG. 2 is an explanatory diagram of a molding operation by the injection molding apparatus shown in FIG. Note that the same reference numerals are given to components having the same functions as those of the conventional injection molding device shown in FIG. 3, and detailed description thereof will be omitted.

This injection molding apparatus, as shown in FIG.
As a pair of molds constituting a mold for injection molding, a fixed mold 10 and a movable mold 20 are arranged vertically. The upper fixed mold 10 is a fixed mold, and the lower movable mold 20 is a movable mold that moves up and down. As the movable mold 20 moves up and down, the mold is opened and closed.

In a pair of upper and lower fixed molds 10 and movable molds 20, product inserts 12 and inserts 22, each of which is made to correspond to the shape of the product obtained from the molded product 30, are embedded. It is arranged.

The movable mold 20 is provided with a resin flow path 24 composed of a runner and a gate. The resin melted and pressurized from the outside flows from the sprue 14 through the runner and gate of the resin flow path 24 into the mold. The space 40 is filled.

Next, each step of the injection molding using the above-described injection molding apparatus will be sequentially described below. (1) Mold Closing Step As shown in FIG. 1, the movable mold 20 is lifted so as to be in contact with the fixed mold 10 to close the mold. That is, FIG. 1 shows a state where the movable mold 20 is at the mold closing position. In this state, the insert 22 and the template 25 having the resin flow path 24 are arranged on the same plane. Thereby, an in-mold space 40 is formed between the insert 12 and the insert 22. (2) Resin Injection Step By applying pressure to the heated and melted resin sent from an external injection cylinder (not shown), the sprue 1
4 and injected into the mold space 40 through the runners and gates of the resin flow path 24 to be filled. (3) Cooling Step The resin filled in the mold space 40 is filled with the upper and lower fixed molds 1.
The molded article 30 is cooled and solidified by heat radiation to the movable mold 20 and the movable mold 20.

The above steps (1) to (3) are the same as the ordinary injection molding steps. (4) Molded Product Removal Step (Part 1) After the cooling step, which is the step (3), only the movable mold 20 is moved to the mold opening position. FIG. 2 shows a state in which the movable mold 20 is at the mold opening position. In this state, the template 25 having the resin flow path 24 is fixed at the position shown in FIG. After the movable mold 20 has been moved to the mold opening position in this way, as shown in FIG.
The slider 26 is slid by the operation of the driving device 26 in the direction of the arrow Y4 which is the opposite direction to the above.

By this action, the peripheral portion 30b corresponding to the resin flow path (runner, gate) 24 of the molded product 30 is
The protruding pins 27 and 28 are released from the template 25 except for the tip portions. At the same time, a part of the product part 30 a of the molded product 30 is also released from the template 25. However, at this time, since the mold body K1 supporting the insert 22 has not moved, the main surface of the product part 30a and the main surface of the insert 22 are not separated. Here, a part of the product part 30a refers to a part that is not the main surface of the product part 30a. The main surface is a surface that requires a precise curvature, flatness, surface shape such as unevenness, or processing accuracy. That is, generally, the non-principal portion refers to the side surface of the product or a rising surface in the vicinity thereof. (5) Molded Product Removal Step (Part 2) As shown in FIG. 2A, after the start of the step (4), after the peripheral portion 30b of the molded article 30 starts releasing from the mold plate 25, or After the completion of (4), the release of the peripheral portion 30b of the molded product 30 from the mold plate 25 is completed.
As shown in (b), the protruding pins 27 and 28 provided in the basic injection molding apparatus are moved in the product removal direction 50.
In the direction of arrow Y5, which is the same direction as
Is released from the insert 22.

In this state, the peripheral portion 30b of the molded product 30
Are kept in close contact with the protruding pins 27 and 28, but can be sufficiently taken out by an ordinary take-out device.
The post-treatment is performed in the same manner as in the usual injection molding process.

After the molded article 30 is taken out, the mold is closed again by the fixed mold 10 and the movable mold 20 to prepare for the next injection molding. By the above, Product Department 3
0a is in close contact with the corresponding main surfaces of the inserts 12 and 22, so that distortion and residual stress due to deformation of the main surface at the time of release and part of the product portion 30a are released. Will not remain.

As a result, the optical lens which is the molded product 30 obtained by the above-described injection molding method has a small distortion when the molded product 30 is taken out, and the precision of the molded product 30 even when repeatedly injection-molded. And it was confirmed that the optical lens had excellent characteristics. (Another Embodiment) Next, FIG. 4 shows an injection molding apparatus partially different in structure from the injection molding apparatus in the above embodiment, and an injection molding method according to another embodiment will be described.

As shown in FIG. 4, the injection molding apparatus used in this injection molding method includes a release plate 2 in a mold plate 25.
9 is provided. A resin flow path (runner, gate) 24 is provided on a release plate 29. The release plate 29 is disposed on the same plane as the insert 22 when the mold is closed. Template 25
The same operation as described above is performed.

In this injection molding apparatus, as shown in FIG. 4, since the mold plate 25 is also fixed to the movable mold 20, it is necessary to adjust the height of the movable mold 20 when the mold is closed. Absent. (Further Embodiment) In the injection molding apparatus in each of the above embodiments, the mold plate 25 or the release plate 2
As means for sliding the actuator 9, means for indirectly using a cam or the like instead of directly acting via the drive unit 26 can be employed. The drive unit 26 may also be a hydraulic cylinder, a pneumatic cylinder, an electromagnetic solenoid, or the like. Etc. are available.

In the injection molding method of each of the above-described embodiments, a part of the product part 30a of the molded product 30 and the runner part which is the peripheral part 30b are connected to the mold plate 2 on the movable molding die 20 side.
The step of releasing from step 5 (step (4)) is performed in the mold space 40.
It is preferable that the heat treatment is performed in a state where the resin in the inside is cooled and at least the surface portion of the molded article 30 is cooled to a temperature equal to or lower than the thermal deformation temperature of the resin constituting the molded article 30. Good.

In the above steps, since the insert 22 corresponding to the product portion 30a of the molded product 30 is fixed to the mold body K1 supporting the insert 22, the molded product 3
The precision of the mold can be assured without moving the main surface of the product section 30a every time 0 is taken out. In particular, in the case of the molded product 30 that requires precision, the slight inclination of the insert 22 corresponding to the product portion 30a poses a serious problem, but such a concern is eliminated.

[0031]

As described above, according to the present invention, after the step of releasing a part of the product part of the molded article and the peripheral part from the molding die is started or completed, the peripheral part projects and comes into close contact with the tip of the pin. In the state where the surface of the product part is in close contact with only the corresponding main surface of the insert, and furthermore, only the protruding pins that are in close contact with the peripheral part are slid in the protruding direction of the molded product, so that the molding is finally completed. The product side of the article and the main side of the insert can be released.

Therefore, the time required for cooling and solidifying can be shortened, the trace of a hole caused by the projecting pin on the surface of the product part of the molded product can be eliminated, and the distortion and residual stress when releasing from the molding die can be reduced. Thus, the productivity and shape accuracy of the molded product can be improved.

As a result, an injection molded article useful as an optical part or the like can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of an injection molding apparatus for realizing an injection molding method according to an embodiment of the present invention.

FIG. 2 is a sectional view for explaining the operation of the injection molding apparatus of the embodiment.

FIG. 3 is a sectional view of an injection molding apparatus for explaining a conventional injection molding method.

FIG. 4 is a cross-sectional view of an injection molding apparatus for realizing an injection molding method according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fixed molding die 12,22 Insert 20 Movable molding die 26 Drive device 29 Release plate

Claims (5)

[Claims] 1. An injection molding method comprising: injecting a resin melted by heating into a mold prepared in accordance with the shape of a product, cooling and solidifying the molded product; and taking out the molded product from the mold to form the product. The method, wherein the step of removing the cooled and solidified molded product from the molding die includes: a first step of releasing a part and a peripheral portion of a product part in the molded product from the molding die; And / or after the start or completion of the step, a second step of releasing all of the product portion of the molded product from the molding die by using a protruding pin provided to a peripheral portion of the molded product. Method. 2. The injection molding method according to claim 1, wherein the step of releasing a part of the product part is performed without using a projecting pin in an insert corresponding to the product part. 3. The step of releasing a part of the product part or the step of releasing the whole product part in a state where an insert corresponding to the product part is fixed to a mold body. The injection molding method according to claim 1 or 2. 4. The injection molding method according to claim 1, wherein the molding is performed using a molding die corresponding to the shape of the transparent optical component. 5. The injection molding method according to claim 1, wherein the resin is molded using a resin for a transparent optical component.