JP2021112902A - Molded article manufacturing method and molding mold-unit - Google Patents

Abstract

To improve a quality of a molded article to be molded by using a resin-made molding mold having a simple configuration.SOLUTION: A molding mold-unit 100 comprises: a resin-made molding mold 110 having a wall portion 13 having a transfer surface 131 that defines a part of a cavity 10; and a reinforcing member 12 that can be attached to and detached from the molding mold 110 so as to come into contact with a wall surface 132 on the wall portion 13 opposite to the transfer surface 131. A molded article is formed by filling the cavity 10 with molten resin, and the molding mold 110 is opened, and then the reinforcing member 12 is taken out. After that, the wall portion 13 is destroyed to take out the molded article.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a molded product and a molding unit.

When a molded product such as a gear or a camera barrel is manufactured by injection molding of a resin material, a mold is generally used. The mold is generally manufactured by cutting with a machining center, turning with a lathe, grinding with a grinding machine, electric discharge machining with a copper electrode / wire electric discharge machine, or the like. Although the components of the mold are highly accurate, it takes a long time to complete the mold because it is processed through a plurality of steps and because there are a large number of components of the mold. For this reason, in the case of making a prototype of a molded product by injection molding, a mold is manufactured each time, which causes a problem that the time required for the trial production becomes long and the cost increases.

Therefore, it has been proposed to inject a molded product using a resin mold instead of a mold. Patent Document 1 discloses a method of producing a resin mold integrated with a metal reinforcing structure by a stereolithography method using a photocurable resin.

Japanese Unexamined Patent Publication No. 8-192467

However, although the method described in Patent Document 1 can secure the strength of the resin mold by the metal reinforcing structure, it does not correspond to the molded product having a special shape such as an undercut shape. Therefore, it is conceivable to provide a slide structure or a placing piece structure in the resin mold as well as the mold. However, in this method, it is necessary to process the resin mold with high accuracy so that burrs do not occur in the mating portion of the pieces, and the production time becomes long as in the case of the mold.

An object of the present invention is to improve the quality of a molded product molded by using a resin molding mold with a molding mold having a simple structure.

The method for producing a molded product of the present invention includes a step of fitting a reinforcing member into a resin molding mold, an injection step of injecting resin into the cavity of the molding mold, and after the injection step, the reinforcement from the molding mold. It is characterized by including a step of taking out a member and a step of breaking the molding die and taking out a molded product.

The molded product unit of the present invention is in contact with a resin molding mold having a wall portion having a transfer surface that defines a part of the cavity and a wall surface of the wall portion opposite to the transfer surface. It is characterized in that the molding die is provided with a removable reinforcing member.

According to the present invention, the quality of a molded product molded using a resin molding die can be improved by a molding die having a simple structure.

(A) is a schematic cross-sectional view of a part of the injection molding machine according to the first embodiment and a molding mold unit assembled to the injection molding machine. (B) is a perspective view of a molded article according to the first embodiment. (A), (b) and (c) are explanatory views of the manufacturing method of the molded article which concerns on 1st Embodiment. (A) and (b) are explanatory views of the manufacturing method of the molded article which concerns on 1st Embodiment. (A) and (b) are explanatory views of the manufacturing method of the molded article which concerns on 1st Embodiment. It is sectional drawing which shows typically the core resin mold of the molding mold which concerns on 2nd Embodiment. It is a perspective view of the molded article which concerns on 3rd Embodiment. (A) and (b) are explanatory views of the manufacturing method of the molded article which concerns on 3rd Embodiment. (A) and (b) are explanatory views of the manufacturing method of the molded article which concerns on 3rd Embodiment. It is a perspective view of the molded article which concerns on 4th Embodiment. (A) and (b) are explanatory views of the manufacturing method of the molded article which concerns on 4th Embodiment. (A) and (b) are explanatory views of the manufacturing method of the molded article which concerns on 4th Embodiment.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1A is a schematic cross-sectional view of a part of the injection molding machine according to the first embodiment and the molding unit 100 assembled to the injection molding machine. FIG. 1B is a perspective view of a helical gear 9 which is an example of a molded product.

As shown in FIG. 1A, a molding unit 100 for injection molding the helical gear 9 is mounted on the die set 3 of the injection molding machine. The mold unit 100 includes a mold 110 and a reinforcing member 12. The helical gear 9, which is an example of the resin molded product shown in FIG. 1 (b), is manufactured by injection molding with an injection molding machine using the molding unit 100 shown in FIG. 1 (a).

The molding die 110 shown in FIG. 1A includes a cavity resin mold 1 which is a cavity mold and a core resin mold 2 which is a core mold. The cavity resin mold 1 and the core resin mold 2 can be mounted on the die set 3. It is preferable that the dimensions of the portion of the die set 3 to which the molding die 110 is mounted are standardized according to the size of the molded product. If the specifications such as the dimensions of the die set 3 are determined, only the cavity resin mold 1 and the core resin mold 2 are manufactured according to the standards, and the cavity resin mold 1 and the core resin mold 2 are attached to the die set 3 of the injection molding machine. Injection molding can be performed simply by performing injection molding. As a result, it becomes possible to make a prototype and manufacture by injection molding in a short period of time using the resin molding die 110.

The cavity resin mold 1 and the core resin mold 2 are molded to define a cavity 10 for transferring the shape of the helical gear 9 in FIG. 1 (b). In the present embodiment, the gate method is a disc gate, and the center pin 4 forming the disc gate is arranged on the side of the core resin mold 2. The resin of the molding material is injected into the cavity 10 via the resin inflow port 5 arranged on the side of the cavity resin mold 1, the sprue runner 6, and the gate 7 defined in the gate bush 8.

Note that FIG. 1A omits illustration of other parts of the injection molding machine, for example, a pressure system for injecting molten resin connected to the resin inflow port 5, a drive system of the die set 3, and the like. .. Known configurations can be used for the members of these injection molding machines. The teeth 91 of the helical gear 9 shown in FIG. 1B are undercut portions, and cannot be easily released from the molding die 110 simply by opening the molding die 110.

The mold 110 has a wall portion 13 having a transfer surface 131 that defines a portion of the cavity 10. In this embodiment, the core resin mold 2 has a wall portion 13. The wall portion 13 is formed in a ring shape. In the core resin mold 2, a ring-shaped groove 11 is formed on the side opposite to the side of the cavity 10 with respect to the wall portion 13. In the present embodiment, the groove 11 is formed in the core resin mold 2. The reinforcing member 12 is formed in a ring shape and can be fitted into the groove 11. That is, the reinforcing member 12 is removable from the molding die 110. The wall surface 132 of the wall portion 13 opposite to the transfer surface 131 is in contact with the reinforcing member 12 fitted in the groove 11. The reinforcing member 12 is fitted into the groove 11 prior to injection molding, and when it comes into contact with the wall surface 132 of the wall portion 13, the wall portion 13 is deformed or damaged by the pressure of the resin injected during injection molding. This can be prevented and the rigidity of the wall portion 13 can be ensured. The transfer surface 131 is a surface for transferring the teeth 91 of the helical gear 9, that is, the undercut portion. The wall portion 13 has a thin wall portion so that it can be easily broken after injection molding.

2 (a), 2 (b), 2 (c), 3 (a), 3 (b), 4 (a), and 4 (b) relate to the first embodiment. It is explanatory drawing of the manufacturing method of the helical gear 9 which is an example of a molded product.

As shown in FIG. 2A, the cavity resin mold 1 and the core resin mold 2 are mounted on the die set 3 and molded. As a result, the cavity 10 is defined inside the molding die 110. Further, in this step, the reinforcing member 12 is fitted into the molding die 110. That is, the reinforcing member 12 is fitted into the groove 11 of the core resin mold 2, and the cavity resin mold 1 and the core resin mold 2 are molded.

Next, as shown in FIG. 2 (b), the molten resin M is introduced into the cavity 10 via the resin inflow port 5 (FIG. 1 (a)), the sprue runner 6 (FIG. 1 (a)), and the gate 7. Inject (injection process). As a result, the cavity 10 is filled with the molten resin M. After that, by holding the pressure inside the cavity 10 and cooling and solidifying the molten resin M, a helical gear 9 is formed inside the cavity 10 as shown in FIG. 2C.

For the resin material of the helical gear 9, for example, POM (polyacetal) is preferably used. In addition to this, PA (polyamide), PBT (polybutylene terephthalate), PC (polycarbonate), PPS (polyphenylene sulfide), TPE (thermoplastic elastomer) and the like may be used. As the resin material used for molding the gear 9, a material other than the above may be used.

When the material of the molding die 110 is, for example, an epoxy-acrylate type, the wall portion 13 which is a thin wall portion has a thickness of about 0.6 mm, specifically, 0.6 mm ± 0.1 mm. preferable. The material of the reinforcing member 12 is preferably a metal having high rigidity such as an aluminum alloy, a copper alloy, or steel, but a resin may be used as long as the wall portion 13 can be prevented from being damaged or deformed by the pressure during molding.

Next, the molding die 110 is opened. By opening the molding die 110, the runner resin connected to the helical gear 9 is removed from the helical gear 9. FIG. 3 (a) schematically shows a cross section of the core resin mold 2 in a state where the molding die 110 is opened, and FIG. 3 (b) shows a core resin mold in a state where the molding die 110 is opened. A plan view of 2 is schematically shown. When the helical gear 9 is released from the core resin mold 2 after the injection step, the reinforcing member 12 is first taken out from the core resin mold 2 as shown in FIG. 4A.

Here, as shown in FIG. 1B, the helical gear 9 has an undercut portion that becomes a twisted tooth 91 as it advances in the axial direction, so that it is a molding die that does not use a technique called rotation punching. Then, it is difficult to release the helical gear 9.

Therefore, in the step shown in FIG. 4B, the helical gear 9 is released from the core resin mold 2 by breaking the core resin mold 2 by utilizing the characteristic that the material is resin. That is, the molding die 110 is destroyed and the helical gear 9 is taken out. In the present embodiment, the wall portion 13 which is a portion corresponding to the undercut portion of the helical gear 9 and is a thin-walled portion is destroyed. Thereby, even when the helical gear 9 has an undercut portion, the injection-molded helical gear 9 can be easily released from the core resin mold 2.

In order to destroy the wall portion 13, a method of applying a radial external force from the center of the core resin mold 2 toward the outside along the radius thereof may be adopted by using a tool or a jig (not shown). If the wall portion 13 is a thin-walled portion, it is easily destroyed.

Here, a method for manufacturing the molding die 110 will be described. In the present embodiment, the molding die 110 is manufactured by the technique of three-dimensional modeling (3D printing). There are three main 3D printing methods, and a molding die 110 is produced by any of these methods. The first method is to lay a thin layer of resin or metal powder material, irradiate the part to be formed with laser light, and continuously repeat melting and solidification to obtain a three-dimensional model. This method is called the SLS method or the like. The second method is a three-dimensional method in which the surface of a liquid tank filled with a photocurable liquid resin material or the lowermost part to be formed is irradiated with ultraviolet rays to continuously perform photopolymerization. It is a stereolithography method for obtaining a modeled object and is called the STL method. The third method is an inkjet additive manufacturing method in which a photocurable liquid resin material is discharged from a nozzle to a portion where a modeled object is to be formed and laminated to obtain a three-dimensional modeled object. In either method, it is not necessary to provide a slide structure or a placing piece structure even when the molded product has an undercut shape. Further, since the material of the molding die 110 is resin, the reinforcing member 12 can prevent the molding die 110 from being damaged or deformed by the pressure applied during molding. Then, the helical gear 9 can be easily taken out by breaking the molding die 110 after molding.

When the cavity resin mold 1 and the core resin mold 2 are molded by a stereolithography method, an epoxy-based or acrylate-based resin can be used as the resin material. For example, as the acrylate-based oligomer, urethane acrylate-based, epoxy acrylate-based, polyester acrylate-based, acrylic acrylate-based, and the like can be considered.

As described above, according to the first embodiment, since the resin molding die 110 is destroyed, it is not necessary to provide the molding die 110 with a slide structure or a placing piece structure, and the molding die 110 is used for molding. The quality of the helical gear 9 can be improved by the molding die 110 having a simple structure.

[Second Embodiment]
FIG. 5 is a cross-sectional view schematically showing the core resin mold 2A of the molding mold according to the second embodiment. The core resin mold 2A has a wall portion 13A. The wall portion 13A has a transfer surface 131A that defines a part of the cavity 10. The wall portion 13A is formed in a ring shape. In the core resin mold 2A, a ring-shaped groove 11 is formed on the side opposite to the side of the cavity 10 with respect to the wall portion 13A. The reinforcing member 12 is formed in a ring shape and can be fitted into the groove 11. The wall surface 132A on the wall surface 13A opposite to the transfer surface 131A is in contact with the reinforcing member 12 fitted in the groove 11. The reinforcing member 12 is fitted into the groove 11 prior to injection molding, and when it comes into contact with the wall surface 132A of the wall portion 13A, the wall portion 13A is deformed or damaged by the pressure of the injected resin during injection molding. It is possible to secure the rigidity of the wall portion 13A. The transfer surface 131A is a surface on which the tooth surface of the helical gear 9, that is, the undercut portion is transferred. The wall portion 13A has a thin wall portion so that it can be easily broken after injection molding.

A notch 14 is formed on the wall surface 132A of the wall portion 13A. The notch 14 is formed so as to extend in the circumferential direction. The notch 14 is formed at a position substantially the lowermost end of the wall portion 13A. The notch 14 is formed in a groove shape having a substantially V-shaped cross section, for example. By providing the notch 14 in the core resin mold 2A, after taking out the reinforcing member 12, for example, by applying an external force to the notch 14 via a tool, a jig, or the like, the wall portion 13A of the core resin mold 2A can be formed. It can be easily destroyed. The notch may be provided as a destruction starting point at a position where the destruction is desired. Further, the shape, position and number of notches can be set according to the shape of the molded product, the shape of the molding mold, the material and the like.

[Third Embodiment]
FIG. 6 is a perspective view showing a molded product according to the third embodiment. The molded product shown in FIG. 6 is the housing 9B of the camera lens barrel. The housing 9B of the camera lens barrel is made of resin. The housing 9B of the camera lens barrel has an outer peripheral surface 91B and an inner peripheral surface 92B in which a cam groove, a key groove, and the like are formed to drive the lens unit. The outer peripheral surface 91B and the inner peripheral surface 92B serve as an undercut portion in injection molding.

7 (a), 7 (b), 8 (a), and 8 (b) are explanatory views showing a method of manufacturing the housing 9B according to the third embodiment. The method for manufacturing the molded product according to the third embodiment is the same as that of the first embodiment, but the molded product to be molded is different from the first embodiment, so that the molded unit is different from the first embodiment. Is used. In the third embodiment, FIGS. 7 (a), 7 (b), 8 (a) and 8 (b) are shown in FIGS. 3 (a), 3 (b), 4 (a) and FIG. Corresponds to 4 (b). In the molding unit of the third embodiment, the cavity resin mold has the same configuration as the cavity resin mold 1 of the first embodiment, and thus the illustration is omitted.

FIG. 7A schematically shows a part of the molding unit and a cross section of the molded product. FIG. 7A schematically shows a cross section of the core resin mold 2B, the reinforcing members 24B and 27B, and the housing 9B in a state where the molding die is opened. FIG. 7B schematically shows a plan view of the core resin mold 2B, the reinforcing members 24B and 27B, and the housing 9B in a state where the mold is opened.

In the third embodiment, the core resin mold 2B has two wall portions 25B and 28B. The wall portions 25B and 28B are formed in a ring shape. The wall portion 28B is arranged inside the wall portion 25B. A part of the cavity 21B for forming the housing 9B is defined by a transfer surface 251B which is an inner peripheral surface of the wall portion 25B and a transfer surface 281B which is an outer peripheral surface of the wall portion 28B.

In the core resin mold 2B, a ring-shaped outer groove 23B is formed on the outside of the wall portion 25B, and a columnar inner groove 26B is formed on the inside of the wall portion 28B. The reinforcing member 24B can be attached to and detached from the outer groove 23B, and the reinforcing member 27B can be attached to and detached from the inner groove 26B. The reinforcing members 24B and 27B are formed in a ring shape.

The outer peripheral surface of the wall portion 25B, the wall surface 252B opposite to the transfer surface 251B, is in contact with the reinforcing member 24B fitted in the outer groove 23B. The reinforcing member 24B is fitted into the outer groove 23B prior to injection molding, and when it comes into contact with the wall surface 252B of the wall portion 25B, the wall portion 25B is deformed or damaged by the pressure of the resin injected during injection molding. It is possible to secure the rigidity of the wall portion 25B. The transfer surface 251B is an outer peripheral surface 91B of the housing 9B, that is, a surface for transferring the undercut portion. The wall portion 25B has a thin wall portion so that it can be easily broken after injection molding.

The inner peripheral surface of the wall portion 28B, the wall surface 282B opposite to the transfer surface 281B, is in contact with the reinforcing member 27B fitted in the inner groove 26B. The reinforcing member 27B is fitted into the inner groove 26B prior to injection molding, and when it comes into contact with the wall surface 282B of the wall portion 28B, the wall portion 28B is deformed or damaged by the pressure of the resin injected during injection molding. It is possible to secure the rigidity of the wall portion 28B. The transfer surface 281B is an inner peripheral surface 92B of the housing 9B, that is, a surface for transferring the undercut portion. The wall portion 28B is a thin portion so that it can be easily broken after injection molding.

The mold release of the housing 9B is carried out by destroying the core resin mold 2B as in the first embodiment. As shown in FIG. 8A, first, the reinforcing member 24B and the reinforcing member 27B are taken out from the core resin mold 2B. After that, as shown in FIG. 8B, the wall portion 25B and the wall portion 28B, which are the portions corresponding to the undercut portion, are destroyed and removed, and the housing 9B of the camera lens barrel is released from the core resin mold 2B. .. As a result, the housing 9B can be easily taken out from the core resin mold 2B. As in the second embodiment, notches may be formed in the wall portions 25B and 28B as the starting points of fracture.

As described above, according to the third embodiment, since the core resin mold 2B of the resin molding mold is destroyed, it is not necessary to provide a slide structure or a placing piece structure in the molding mold, and the molding is performed using the molding mold. The quality of the housing 9B can be improved by a molding mold having a simple structure.

[Fourth Embodiment]
FIG. 9 is a perspective view showing a molded product according to the fourth embodiment. The molded product shown in FIG. 9 is a frame body 9C having a rectangular shape in a plan view. The frame body 9C is made of resin. The frame body 9C has a cross-shaped through hole 92C formed in the side wall 91C. This through hole 92C serves as an undercut portion.

10 (a), 10 (b), 11 (a), and 11 (b) are explanatory views showing a method of manufacturing the frame body 9C according to the fourth embodiment. The method for manufacturing the molded product according to the fourth embodiment is the same as that of the first embodiment, but the molded product to be molded is different from the first embodiment, so that the molded unit is different from the first embodiment. Is used. In the fourth embodiment, FIGS. 10 (a), 10 (b), 11 (a) and 11 (b) are shown in FIGS. 3 (a), 3 (b), 4 (a) and FIG. Corresponds to 4 (b). In the molding unit of the fourth embodiment, the cavity resin mold has the same configuration as the cavity resin mold 1 of the first embodiment, and thus the illustration is omitted.

FIG. 10A schematically shows a part of the molding unit and a cross section of the molded product. FIG. 10A schematically shows a cross section of the core resin mold 2C, the reinforcing member 12C, and the frame body 9C in a state where the molding die is opened. FIG. 10B schematically shows a plan view of the core resin mold 2C, the reinforcing member 12C, and the frame body 9C in a state where the molding die is opened.

In the fourth embodiment, the core resin mold 2C has a wall portion 13C. The wall portion 13C is formed in a flat plate shape. A part of the cavity 10C for forming the frame body 9C is defined by the transfer surface 131C of the wall portion 13C.

In the core resin mold 2C, a groove 11C is formed on the side opposite to the side of the cavity 10C with respect to the wall portion 13C. A reinforcing member 12C can be attached to and detached from the groove 11C. The reinforcing member 12C is formed in a flat plate shape.

The wall surface 132C on the wall surface 13C opposite to the transfer surface 131C is in contact with the reinforcing member 12C fitted in the groove 11C. The reinforcing member 12C is fitted into the groove 11C prior to injection molding, and when it comes into contact with the wall surface 132C of the wall portion 13C, the wall portion 13C is deformed or damaged by the pressure of the resin injected during injection molding. It is possible to secure the rigidity of the wall portion 13C. The transfer surface 131C is a surface for transferring the side wall 91C of the frame body 9C, that is, the undercut portion. The wall portion 13C has a thin wall portion so that it can be easily broken after injection molding.

The mold release of the frame body 9C is carried out by destroying the core resin mold 2C as in the first embodiment. As shown in FIG. 11A, first, the reinforcing member 12C is taken out from the core resin mold 2C. After that, as shown in FIG. 11B, the wall portion 13C, which is a portion corresponding to the undercut portion, is destroyed and removed, and the frame body 9C is released from the core resin mold 2C. As a result, the frame body 9C can be easily taken out from the core resin mold 2C. As in the second embodiment, the wall portion 13C may be formed with a notch serving as a fracture starting point.

As described above, according to the fourth embodiment, since the core resin mold 2C of the resin molding mold is destroyed, it is not necessary to provide a slide structure or a placing piece structure in the molding mold, and the molding is performed using the molding mold. The quality of the frame body 9C can be improved by a molding die having a simple structure.

The present invention is not limited to the embodiments described above, and many modifications can be made within the technical idea of the present invention. Moreover, the effects described in the embodiments are merely a list of the most preferable effects arising from the present invention, and the effects according to the present invention are not limited to those described in the embodiments.

The above-mentioned reinforcing member can be appropriately selected according to the shape of the molded product and the molding die, but it is preferable that the reinforcing member has a shape that can be easily machined by a processing machine, a lathe, a milling machine, or the like. The reinforcing member may be manufactured by 3D printing in the same manner as the molding die.

Further, the core resin mold is fitted into the above-mentioned core resin mold, and the core resin mold is destroyed after the reinforcing member is taken out, but the present invention is not limited to this. A reinforcing member may be fitted into the cavity resin mold, and the cavity resin mold may be destroyed after the reinforcing member is taken out.

1 ... Cavity resin mold, 2 ... Core resin mold, 9 ... Helical gear (molded product), 10 ... Cavity, 12 ... Reinforcing member, 13 ... Wall part, 100 ... Molding mold unit, 110 ... Molding mold, 131 ... Transfer surface, 132 ... Wall surface

Claims (13)

The process of fitting the reinforcing member into the resin molding and
The injection process of injecting resin into the cavity of the molding mold and
After the injection step, a step of taking out the reinforcing member from the molding mold and
The process of destroying the molding die and taking out the molded product,
A method for producing a molded product, which comprises. The mold comprises a wall having a transfer surface that defines a portion of the cavity.
In the fitting step, the reinforcing member is fitted into the molding die so as to come into contact with the wall surface of the wall portion on the side opposite to the transfer surface.
The method for producing a molded product according to claim 1. The wall portion is a thin wall portion,
The method for producing a molded product according to claim 2. In the step of taking out the molded product, the wall portion is destroyed and the molded product is taken out.
The method for producing a molded product according to claim 2 or 3, characterized in that. A notch is formed in the wall surface of the wall portion.
The method for producing a molded product according to any one of claims 2 to 4, wherein the molded product is produced. The wall portion is a portion that forms an undercut portion of the molded product.
The method for producing a molded product according to any one of claims 2 to 5, characterized in that. The method for producing a molded product according to any one of claims 1 to 6, wherein the molding mold is manufactured by three-dimensional molding. The method for producing a molded product according to any one of claims 1 to 7, wherein the reinforcing member has a ring shape or a flat plate shape. A resin molding with a wall having a transfer surface that defines part of the cavity,
A reinforcing member that can be attached to and detached from the molding mold so as to come into contact with the wall surface of the wall portion on the side opposite to the transfer surface.
A molding unit characterized by being provided with. The wall portion is a thin wall portion,
The molding unit according to claim 9. A notch is formed in the wall surface of the wall portion.
The molding unit according to claim 9 or 10. The wall portion is a portion that forms an undercut portion of the molded product.
The molding unit according to any one of claims 9 to 11. The molded unit according to any one of claims 9 to 12, wherein the reinforcing member has a ring shape or a flat plate shape.

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