WO2015152131A1

WO2015152131A1 - Injection molding die and method for manufacturing resin molding

Info

Publication number: WO2015152131A1
Application number: PCT/JP2015/059866
Authority: WO
Inventors: 俊次藤村; 山本　功
Original assignee: 日本写真印刷株式会社
Priority date: 2014-04-04
Filing date: 2015-03-30
Publication date: 2015-10-08
Also published as: JP5965092B2; TWI636862B; KR20160141701A; KR102280117B1; CN105636755A; TW201600302A; CN105636755B; JPWO2015152131A1

Abstract

[Problem] In the decorative layer of a resin molding that is simultaneously molded and decorated using a decorative sheet, to improve inhibition of ink running, which occurs due to melted resin injected during molding. [Solution] A gate undercut block (62) is configured so that: during injection of molten resin when a peripheral plate (54) is in contact with the first parting surface and the compression block (60) is retracted with respect to the peripheral plate (54), the gate undercut block is fitted in the cavity (60b) and adheres tightly to the compression block (60); during compression, the gate undercut block fitted in the cavity (60b) compresses the molten resin together with the compression block (60) by means of the second forming surface (52); and during molding removal, the gate undercut block separates from the cavity (60b) and detaches from the gate resin.

Description

Injection mold and method for producing resin molded product

The present invention relates to an injection mold used for manufacturing a resin molded product that is molded simultaneously with a decorative sheet, and a method for manufacturing a resin molded product that is molded simultaneously with a decorative sheet.

Resin molded products may require high strength while reducing wall thickness. If a resin with poor flowability at the time of melting is used for injection molding in order to obtain high strength, various problems such as high stress are generated when the molten resin is injected into the cavity of the mold. It is known to occur. For example, as described in Patent Document 1 (Patent No. 5155992), in particular, when decorating simultaneously with molding using a decorative sheet, there is a problem that ink of the decorative layer flows.

Japanese Patent No. 5155992

In the above-mentioned Patent Document 1, in order to prevent a large pressure from being applied to both sides of the fan gate and an increase in the flow rate of the molten resin, before the second bent portion which is the longitudinal end of the opening of the gate with respect to the cavity. The ink flow is suppressed by providing a first bent portion that widens the width of the resin flow path downstream in the molten resin flow direction. However, even when the injection mold described in Patent Document 1 is used, the effect of suppressing ink flow may not be sufficient when the thickness of the product is reduced. In particular, when reinforcing fibers such as glass fibers are dispersed in the molten resin and the molten resin is difficult to flow, the effect of suppressing ink flow tends to be insufficient.

An object of the present invention is to provide an injection mold and resin in which the effect of suppressing ink flow caused by a molten resin injected at the time of molding is improved in a decorative layer of a resin molded product that is simultaneously decorated using a decorative sheet It is providing the manufacturing method of a molded article.

Hereinafter, a plurality of modes will be described as means for solving the problems. These aspects can be arbitrarily combined as necessary.
An injection mold according to an aspect of the present invention is in contact with a first mold in which a first molding surface on which a decorative sheet is arranged is formed on a first parting surface, and the first parting surface. And a second mold in which a second molding surface opposite to the first molding surface is formed on the second parting surface, wherein the second mold is a part of the second molding surface. A gate part for directly injecting resin from the direction intersecting the second molding surface, a compression block in which a recess arranged in connection with the gate part is formed, the first molding surface and the first molding surface 2 includes an outer peripheral plate arranged around the compression block for compressing the molten resin injected into the cavity surrounded by the molding surface, and a part of the second molding surface, and is detachably arranged in the recess. The first resin flow path is formed in which the gate portion is narrowed in a flat shape while being mounted in the recess. A gate portion undercut block that constitutes one surface of the first resin flow path, and the gate portion undercut block has an outer periphery at the time of injection of molten resin in which the outer peripheral plate is in contact with the first parting surface. In a state where the compression block is pulled down with respect to the plate, it is attached to the recess and is in close contact with the compression block, and during compression, the molten resin is compressed by the second molding surface together with the compression block in a state of being attached to the recess. At the time of taking out, it is configured to be detached from the concave portion and detached from the gate resin.

In the injection mold configured as described above, when the molten resin is injected, the first molding surface of the first mold, the outer peripheral plate in contact with the first parting surface, and the second molding surface of the compression block. The enclosed space has a first molding surface and a second molding compared to a cavity formed by combining the first parting surface of the first mold and the second parting surface of the second mold in order to mold the molded product. The distance from the surface is wide. At this time, the gate undercut block is mounted in the concave portion of the compression block, and the first resin flow path is narrowed to a flat shape. Therefore, when the molten resin is injected from the first resin flow path to the first molding surface on which the decorative sheet is arranged, the stress that the decorative layer of the decorative sheet receives from the molten resin can be reduced. The ink flow in the decorative layer of the molded product is suppressed. In addition, since the gate portion undercut block is in close contact with the recess from the time of injection to the time of compression, problems such as resin flowing between the compression block and the gate portion undercut block can be prevented. Further, the shape of the gate resin is undercut by the gate portion undercut block in order to narrow the gate portion, and the backflow of the resin during compression is prevented.

The mold for injection molding according to the above-mentioned aspect maintains the state where the gate portion undercut block is attached to the recess and is in close contact with the compression block at the time of injection of the molten resin, and the gate portion undercut block is placed in the recess during compression. With the compression block attached, the gate undercut block is moved relative to the first mold to compress the molten resin, and the gate undercut block is moved in the protruding direction of the molded product when the molded product is taken out. The gate part undercut block moving mechanism which removes from gate resin by this may be further provided.
In the injection mold configured in this way, the gate undercut block can be reliably operated by the gate undercut block moving mechanism, and there is a problem that the gate undercut block does not adhere to the compression block. It is possible to prevent the occurrence of a malfunction due to the occurrence of a failure or the failure of the gate portion undercut block to be smoothly removed from the gate resin.

In the second mold, the gap between the opening portions of the first resin flow channel narrowed by the gate portion undercut block in a state where the gate portion undercut block is mounted in the concave portion, and the first molding surface in the vicinity of the gate portion It may be not less than 0.25 times and not more than 0.7 times the interval at the time of compression of the second molding surface.
In the injection molding die configured as described above, the interval between the openings of the first resin flow path is 0.25 times or more and 0.7 times or less the compression interval between the first molding surface and the second molding surface. Therefore, while sufficiently preventing the ink flow, the volume of the first resin flow path is reduced with respect to the product thickness in the vicinity of the gate portion to the extent that the resin sink generated in the molded product after molding is inconspicuous. be able to.

The compression block has a gate portion disposed substantially at the center of the second molding surface, the gate portion having a second resin flow path that leads to a difference in height relative to the first resin flow path, and a hollow shape with respect to the second molding surface. If the length of the diagonal line of the cavity is ML inches when viewed from a vertical direction, the overlap amount between the first resin flow path and the second resin flow path is ML × 0.2 mm or more ML × 0 The width of the first resin flow path may be set to ML × 4.5 mm or more and ML × 17 mm or less.
In the injection mold configured as described above, the stress applied to the decorative sheet by the molten resin is relieved, and the molten resin can smoothly flow from the second resin flow path to the first resin flow path, so that the resin into the cavity Filling becomes easy.

The manufacturing method of the resin molded product according to an aspect of the present invention includes the first step in which the decorative sheet is disposed on the first molding surface of the first mold, and the second mold on the first parting surface of the first mold. The first die and the second die are clamped so that the outer peripheral plate is brought into contact with and the compression block including a part of the second molding surface of the second die is pulled down with respect to the outer peripheral plate. After the second step and the second step, the first resin flow in the gate portion, which is attached to the recess connected to the gate portion of the compression block so that the gate portion undercut block is in close contact with the compression block and narrowed to a flat shape. A third step of injecting resin directly from the direction intersecting the second molding surface through the first resin flow path with the gate portion undercut block formed on one side of the path, and the gate portion undercut in the recess With the block attached, the compression block A fourth step of compressing the molten resin by the second molding surface included in the compression block and the gate part undercut block by moving the gate part undercut block relative to the first mold together with the pack; And a fifth step of removing the gate portion undercut block from the gate resin by moving it in the protruding direction of the molded product.
In the method of manufacturing a resin molded product configured as described above, in the third step, the first molding surface of the first mold, the outer peripheral plate in contact with the first parting surface, and the second molding surface of the compression block are used. The enclosed space has a first molding surface and a second molding compared to a cavity formed by combining the first parting surface of the first mold and the second parting surface of the second mold in order to mold the molded product. The distance from the surface is wide. At this time, the gate undercut block is mounted in the concave portion of the compression block, and the first resin flow path is narrowed to a flat shape. Therefore, when the molten resin is injected from the first resin flow path to the first molding surface on which the decorative sheet is arranged, the stress that the decorative layer of the decorative sheet receives from the molten resin can be reduced. The ink flow in the decorative layer of the molded product is suppressed. In addition, since the gate portion undercut block is in close contact with the recess from the third step to the fourth step, problems such as resin flowing between the compression block and the gate portion undercut block can be prevented. Further, the shape of the gate resin is undercut by the gate portion undercut block in order to narrow the gate portion, and the back flow of the resin in the fourth step is prevented.

In the third step, the molten resin in which the reinforcing fibers are dispersed is injected through the flat first resin flow path. In the fourth step, the second molding surface included in the compression block and the gate undercut block. Thus, the first molding surface and the second molding surface may be compressed until the distance between the first molding surface and the second molding surface is equal to or larger than the target product thickness around the gate portion and equal to or smaller than 1.2 mm.
In the method of manufacturing a resin molded product configured in this way, molten resin containing reinforcing fibers is injected while maintaining the high strength of the molded product with the reinforcing fibers even if the product thickness is as thin as 1.2 mm or less. When doing, the ink flow of the decoration layer of a decoration sheet can be suppressed.

In the third step, molten resin in which glass fibers are dispersed as reinforcing fibers is injected through the flat first resin flow path, and in the fourth step, the first molding surface and the second molding surface are surrounded. When the cavity has a substantially rectangular shape when viewed from a direction perpendicular to the second molding surface, the first molding surface and the second molding surface are assumed to have a diagonal length of 4 inches or more and 6 inches or less. May be compressed until it is within the range of the product target thickness around the gate portion and 0.5 mm or more and 0.7 mm or less.
In the method of manufacturing a resin molded product configured as described above, deformation at the time of molding can be reduced even if the molded product has a thin product thickness of about 0.5 mm to 0.7 mm.

According to the injection mold of the present invention or the method for producing a resin molded product, the ink produced by the molten resin injected at the time of molding in the decorative layer of the resin molded product that is simultaneously decorated using the decorative sheet The effect of suppressing the flow can be improved.

Sectional drawing for demonstrating the clamping state of the injection mold which concerns on 1st Embodiment. Sectional drawing for demonstrating the mold open state of the metal mold | die for injection molding of FIG. Sectional drawing for demonstrating the protrusion state of the molded article of the injection die of FIG. Sectional drawing for demonstrating the state by which the decorating sheet is followed along the 1st molding surface of the injection die of FIG. Sectional drawing for demonstrating the state by which the preliminary mold clamping of the injection mold of FIG. 1 was complete | finished, and the compression amount was set. The perspective view for demonstrating an example of a structure of a molded article. (A) The elements on larger scale which looked around the gate part from the front, (b) The elements on larger scale which looked at the circumference of the gate part from the side. (A) The perspective view of a gate part undercut block, (b) The front view of a gate part undercut block. (A) The top view of a gate part undercut block, (b) The side view of a gate part undercut block. (A) Schematic sectional view for explaining the mold opening state of the injection mold according to the second embodiment, (b) Schematic for explaining the state where the gate undercut block is returned to the compression block. Sectional view. (A) Typical sectional drawing for demonstrating the mold closing state of the injection mold of FIG. 10, (b) Typical sectional drawing for demonstrating the injection state of molten resin. (A) Typical sectional drawing for demonstrating the cooling state of the molten resin after compression with the injection mold of FIG. 10, (b) Typical sectional drawing for demonstrating a mold open state. (A) Typical sectional drawing for demonstrating the state by which the molded article was protruded with the injection mold of FIG. 10, (b) Typical sectional drawing which shows the state after the molded article was taken out.

<First Embodiment>
(1) Outline of Configuration of Injection Mold FIG. 1 to FIG. 5 show a cross section of an injection mold according to the first embodiment of the present invention. The injection mold 10 includes a first mold 20 on the movable side and a second mold 50 on the fixed side. There is a parting line 11 that divides the injection mold 10 between the first mold 20 and the second mold 50. A first parting surface 21 is formed on the first mold 20 along the parting line 11, and a second parting surface 51 is formed on the second mold 50. A first molding surface 22 is formed on the first parting surface 21 of the first mold 20, and a second molding surface 52 is formed on the second parting surface 51 of the second mold 50.
The first insert 23 on which the first molding surface 22 is formed is fixed to the first template 24. The first mold plate 24 is fixed to the first mounting plate 25 on the surface opposite to the surface on which the first insert 23 is fixed. The first mounting plate 25 is mounted on an injection molding machine (not shown) on the surface opposite to the surface on which the first template 24 is mounted.

A first air cylinder 26 is attached to the first attachment plate 25. One end of a clamp pin 27 installed through the first template 24 is attached to the first air cylinder 26. The other end of the clamp pin 27 is fastened with a bolt 28 a to a clamp 28 disposed on the surface of the first template 24 to which the first insert 23 is attached. A decorative sheet 80 is sandwiched between the clamp 28 and the first insert 23. FIG. 4 shows a state where the decorative sheet 80 is sucked and the decorative sheet 80 extends along the first molding surface 22. A number of suction ports (not shown) are formed in the first nest 23. The broken-line arrows shown in FIG. 4 indicate the suction direction when air is sucked from the suction port.
A first guide bush 29 is provided on the first mold plate 24 of the first mold 20. The first guide bush 29 of the first mold 20 guides the guide pin 59 of the second mold 50. By guiding the guide pin 59 by the first guide bush 29, the mold clamping and mold opening of the first mold 20 and the second mold 50 are performed with high accuracy.

The second insert 53 on which the second molding surface 52 is formed is disposed on the outer peripheral plate 54. A second guide bush 55 is provided on the outer peripheral plate 54. The outer peripheral plate 54 is guided along the guide pins 59 by the second guide bush 55. With the guide pin 59 inserted into the first guide bush 29, the outer peripheral plate 54 is guided along the guide pin 59 by the second guide bush 55, so that the positioning of the second insert 53 relative to the first insert 23 is accurate. Often done.
The guide pin 59 is fixed to the second template 56. A hydraulic cylinder 57 for moving the outer peripheral plate 54 is attached to the second template 56. The movable portion 57 a of the hydraulic cylinder 57 is provided through the second template 56 and is connected to the outer peripheral plate 54. Accordingly, the outer peripheral plate 54 moves together with the movable portion 57a. The second template 56 is provided with a movable space 56 a for accommodating the movable plate 58. The movable plate 58 can move so as to move forward and backward in the movable space 56a toward the first mold 20.

A compression block 60 is fixed to the second template 56. Of the surfaces of the compression block 60, the surface opposite to the second template 56 is a part of the second molding surface 52. Further, the compression block 60 is configured to be movable relative to the outer peripheral plate 54 around the compression block 60. That is, when the outer peripheral plate 54 is pushed in the direction of the first mold 20 by the hydraulic cylinder 57 and moves along the guide pin 59, the compression block 60 is pulled down with respect to the outer peripheral plate 54. The compression block 60 is formed with a gate portion 60a for injecting molten resin at the time of injection molding. The gate portion 60a is a direct fan gate.
A movable pin 58 a extending through the compression block 60 extends from the movable plate 58. One end of the movable pin 58a is fixed to the movable plate 58, and the gate undercut block 62 is connected to the other end. The gate undercut block 62 is detachably disposed in the recess 60b of the compression block 60. As can be seen from a comparison between FIG. 2 and FIG. 3, the gate undercut block 62 is moved relative to the compression block 60 by the movable pin 58 a. The gate undercut block 62 is moved to a position where it is detached from the compression block 60. In the gate portion undercut block 62, a surface facing the first molding surface 22 is a part of the second molding surface 52. The surface F1 of the gate portion undercut block 62 shown in FIG. 2 constitutes one surface of the gate portion 60a of the compression block 60.

A sprue bush 63 for injecting molten resin into the gate portion 60 a of the compression block 60 is inserted into the compression block 60. The sprue bush 63 is fixed to the third template 64. A second air cylinder 65 is attached to the third template 64. Extending from the second air cylinder 65 is a movable portion 65 a installed through the third template 64. The movable portion 65 a is connected to the movable plate 58. When the movable portion 65a of the second air cylinder 65 expands and contracts, the movable plate 58 moves, and the gate undercut block 62 moves together with the movable plate 58.
A fixing pin 67 is fixed to the third template 64. On the other hand, a fixing bush 66 is attached to the second template 56. Then, the third mold plate 64 is fixed to the second template 56 by fitting the fixing pins 67 to the fixing bush 66. In addition, the third mold plate 64 is fixed to the second mounting plate 68 on the surface opposite to the surface in contact with the second mold plate 56. A manifold 69 connected to the sprue bushing 63 is disposed in a space 64 a surrounded by the third template 64 and the second mounting plate 68. The manifold 69 is connected to a nozzle touch portion 68 a attached to the second attachment plate 68.

(2) Outline of Operation of Injection Mold Die When the mold is clamped as shown in FIG. 1, the first molding surface 22 of the first mold 20 and the second molding surface 52 of the second mold 50 Together, the cavity 12 of the injection mold 10 is formed. A molten resin is injected into the cavity 12 to form a molded product 90. The injection mold 10 shown in FIG. 1 is in a state where compression has been completed.
FIG. 2 shows a state where the mold opening is completed. The first mold 20 and the second mold 50 are separated from each other, and the guide pin 59 is removed from the first guide bush 29. At this time, the decorative sheet 80 is in a state of being fastened to the first mold 20 by the clamp 28. On the other hand, in the second mold 50, the outer peripheral plate 54 is pressed against the second mold plate 56 by the hydraulic cylinder 57. That is, the first mold 20 and the second mold 50 are separated while the outer peripheral plate 54 is pulled by hydraulic pressure. At this time, the second air cylinder 65 also contracts the movable portion 65 a and maintains the state where the gate portion undercut block 62 is mounted in the concave portion 60 b of the compression block 60.

FIG. 3 shows a state in which the molded product 90 is protruded. In order to project the molded product 90, the movable portion 65 a of the second air cylinder 65 extends and the gate portion undercut block 62 is detached from the concave portion 60 b of the compression block 60. At this time, a decorative layer 91 is formed on the surface of the molded product 90 formed by the first molding surface 22 by transferring the decorative sheet 80. In FIG. 3, the part shown with the broken line of the decorating sheet 80 is a part from which the decorating layer was lose | eliminated by transcription | transfer. The clamp 28 sandwiching the decorative sheet 80 is opened, and the decorative sheet 80 is movable. Next, the decorative sheet 80 is moved by a sheet feeding device (not shown), and a portion with the decorative layer is fed onto the first molding surface 22. At this time, the outer peripheral plate 54 is in a state of being hydraulically pulled by the movable portion 57 a of the hydraulic cylinder 57, and the outer peripheral plate 54 is pressed against the second template 56. In the state shown in FIG. 3, the molded product 90 is taken out.
Prior to the state shown in FIG. 4, the first air cylinder 26 pulls the clamp pin 27, and the clamp 28 sandwiches the decorative sheet 80. Next, suction is performed from the suction port of the first insert 23, and the decorative sheet 80 is placed along the first molding surface 22. Simultaneously with the suction of the decorative sheet 80, the first mold 20 is moved toward the second mold 50, and the injection mold 10 is clamped. When the mold closing is started, the hydraulic pressure of the hydraulic cylinder 57 is lowered to make the movable portion 57a free. Accordingly, the outer peripheral plate 54 is advanced by an elastic body (not shown) embedded between the second mold 50 and the outer peripheral plate 54. For example, a spring can be used as the embedded elastic body. In addition, at the stage where the removal of the molded product 90 is completed before the mold closing is started, the movable portion 65a of the second air cylinder 65 is contracted and the gate portion undercut block 62 is mounted in the concave portion 60b of the compression block 60.

The decorative sheet has a base sheet and a decorative layer formed on the base sheet. For the decorative layer, a peeling layer that forms the outer surface of the molded product and protects the design layer, etc., a design layer that expresses the design and alignment marks, and an adhesive that improves the adhesion between the molded product and the decorative layer There are anchor layers that protect layers and design layers and improve interlayer adhesion. Furthermore, when improving the peelability of the decorating layer from the base sheet, a release layer is formed between the base sheet and the decorating layer.

The base sheet is made of a material such as a resin sheet such as PET, polypropylene (PP) or PMMA, a metal foil, glassine paper, coated paper, a cellulosic sheet such as cellophane.

For the release layer, a copolymer such as PMMA resin, polyester resin, vinyl chloride-vinyl acetate copolymer resin is used. In order to increase the hardness of the release layer and improve the scratch resistance of the molded product, an ultraviolet curable resin, an electron beam curable resin, or the like is used. The release layer is printed on the substrate sheet by a gravure printing method, a screen printing method, an offset printing method, or the like.

The design layer is formed of a colored ink containing a resin and a coloring material such as a pigment or a dye. Resins used as binders include polyvinyl resins, polyamide (PA) resins, polyester resins, PMMA resins, polyurethane resins, polyvinyl acetal resins, polyester urethane resins, cellulose ester resins, alkyd resins, etc. is there. The pattern layer is printed on the release layer by a gravure printing method, a screen printing method, an offset printing method, or the like. The symbol layer is set entirely or partially depending on the symbol to be expressed. When it is desired to express metallic luster as a pattern, the pattern layer may be constituted by a metal thin film layer formed by a vacuum deposition method, a sputtering method, an ion plating method, a plating method or the like. You may form both a design layer and a metal thin film layer.

A melamine-based resin or the like is used for the release layer, and a heat-sensitive or pressure-sensitive resin suitable for the resin material of the molded product, for example, a PMMA resin if the molded product resin is a PMMA resin. Resin is used, and a thermosetting urethane resin or the like is used for the anchor layer. The release layer, the adhesive layer, and the anchor layer are printed by a gravure printing method, a screen printing method, or the like.

In the injection mold 10, the interval between the first molding surface and the second molding surface is larger when the molten resin is injected than when the molten resin is injected, and the first resin flow path is narrowed to a flat shape. Therefore, the stress received by the decorative sheet placed on the first molding surface from the molten resin can be reduced. Therefore, it is possible to suppress the appearance failure of the design near the gate mark, which is caused by the flow of the design layer by the molten resin. In particular, when a metal thin film layer is formed on the decorative sheet, the metal thin film layer is likely to break due to the stress applied to the metal thin film layer, resulting in poor appearance. It is effective for suppressing appearance defects on the design near the mark.

The state shown in FIG. 5 is a state in which the pre-clamping is finished and the compression amount is set. The injection molding machine is driven to perform preliminary mold clamping, and the first mold 20 is touched to the outer peripheral plate 54 that has been advanced first. Thereafter, the compression amount is set by clamping the first mold 20. That is, the first mold 20 stops before the compression amount set value as compared with the completely clamped state. At this time, the compression amount setting value CV, which is the size of the gap between the outer peripheral plate 54 and the second mold plate 56, is set to a value larger than 0 mm and smaller than 0.5 mm, for example.
In the state shown in FIG. 5, the molten resin is injected from the injection molding machine that is in contact with the nozzle touch portion 68 a, passes through the manifold 69 and the sprue bush 63, passes through the gate portion 60 a, and the molten resin is hollow 12. Flows in. While the molten resin is being filled into the cavity 12 or from the time when the filling is completed, the hydraulic pressure of the hydraulic cylinder 57 is lowered to weaken the force with which the movable portion 57a pushes the outer peripheral plate 54, and the outer peripheral plate 54 is pushed by the first mold 20. Clamp compression starts. At this time, the second air cylinder 65 pulls the movable portion 65 a to bring the gate undercut block 62 mounted in the recess 60 b into close contact with the compression block 60. Therefore, even if stress is applied to the gate undercut block 62 from the molten resin, the molten resin does not enter between the gate undercut block 62 and the compression block 60.

(3) Shape of Gate FIG. 6 is a perspective view of a molded product that is injection-molded through the steps of FIGS. 1 to 5. The gate resin 92 extending in the longitudinal direction of the molded product 90 remains in the approximate center of the molded product 90 having a substantially rectangular shape in plan view. FIG. 6 shows that the gate part 60a is a direct fan gate. By disposing the gate portion 60a substantially at the center of the second molding surface 52, the flow length of the molten resin from the gate portion 60a to the end of the cavity 12 is shortened, and the resin of the molten resin is facilitated. Warpage is also alleviated. The gate width W1, which is the width of the opening of the first resin flow path FL1 connected to the cavity 12, is set to a diagonal length ML × 4.5 mm to ML × 17 mm, and the diagonal length ML is set to 10 In the case of an inch or less, it is preferably set to ML × 6 mm or more and ML × 10 mm or less. If the gate width W1 is too long or too short, it becomes difficult to set the flow pattern and the injection pressure.

FIG. 7A is a partially enlarged view of the periphery of the gate portion 60a as viewed from the front, and FIG. 7B is a partially enlarged view of the periphery of the gate portion 60a as viewed from the side. The gate part 60 a is provided downstream of the sprue part 63 a formed in the sprue bush 63. A rib-shaped third resin flow path FL3 that is relatively thick and extends in the width direction is formed in the sprue portion 63a. At both ends in the width direction of the third resin flow path FL3, width direction reservoir portions 63a1 are provided so that cold slag does not enter the molded product 90.
The gate part 60a mainly includes a flat first resin flow path FL1 that continues from an opening that opens toward the cavity 12, and a space between the first resin flow path FL1 and the third resin flow path FL3 of the sprue part 63a. The flat second resin flow path FL2 is formed.
The interval d1 of the first resin flow path FL1 is 0.25 × Th ≦ d1 ≦ 0.7 × with respect to the interval Th during compression of the first molding surface 22 and the second molding surface 52 in the vicinity of the gate portion 60a. It is preferable to set to be Th. If the distance d1 between the first resin flow paths FL1 is narrower than the distance Th when the first molding surface 22 and the second molding surface 52 are compressed, a large injection pressure is required, making it difficult to prevent ink flow. On the contrary, when the width is increased, the volume of the gate portion 60a is increased, and the resin sink generated in the molded product is easily noticeable.

In order to keep the peak of the flow rate of the molten resin inside the gate portion 60a, the first resin flow path FL1 and the second resin flow path FL2 are partially overlapped to form a step and the flow direction is changed. I am letting. The first resin flow path FL1 and the second resin flow path FL2 have substantially the same distances d1 and d2, and are set in the range of 1 ≦ (d2 / d1) ≦ 3, for example.
The overlap amount OL between the first resin flow path FL1 and the second resin flow path FL2 is in a range of ML × 0.2 mm ≦ OL ≦ ML × 0.3 mm when the diagonal line of the molded product 90 is ML inches. Is preferably set. Further, the interval d3 between the overlapping portions is slightly smaller than the same value (d1 + d2) obtained by adding the interval d1 between the openings of the first resin channel FL1 and the interval d2 between the second resin channels FL2 ( It is preferable to set in the range of d1 + d2) × 0.9. When the overlap amount OL is small or the interval d3 is too large, the filling property of the molten resin into the cavity 12 is deteriorated. On the contrary, if the overlap amount OL is large or the interval d3 is too small, it becomes difficult to fit the peak of the flow rate of the molten resin in the gate portion 60a.
It is preferable that the taper angle θ at both ends of the first resin flow path FL1 and the second resin flow path FL2 is 20 ° ≦ θ ≦ 40 °. If the taper angle θ is small, the molten resin injection efficiency is lowered. If the taper angle θ is large, the molten resin does not spread, so that it is difficult to reduce the flow rate of the molten resin, and it is difficult to obtain an ink flow suppressing effect.

The length L1 of the first resin flow path FL1 is preferably set in a range of ML × 0.7 mm ≦ L1 ≦ ML × 1.2 mm using a diagonal length ML inch. If the length L1 of the first resin flow path FL1 is too long or too short, the effect of preventing ink flow is reduced. When the length L1 of the first resin flow path FL1 is thus set, both ends of the gate width W2 of the second resin flow path FL2 connected to the overlap portion with respect to the gate width W1 of the first resin flow path FL1. Are preferably shortened by about the same amount and set in a range of 1.6 ≦ L1 / (W1−W2) ≦ 2.4. If (W1-W2) is too small, it becomes difficult to fit the peak of the flow velocity of the molten resin inside the gate portion 60a, and if (W1-W2) is too large, the filling property of the molten resin into the cavity 12 is deteriorated. Note that the gate width W2 is set to be approximately the same as the width of the third resin flow path FL3, for example.
A reservoir 60a1 is provided in the second resin flow path FL2 on the side that is undercut by the step between the second resin flow path FL2 and the first resin flow path FL1. The pool portion 60a1 suppresses cold slag from entering the molded product 90. Of the surfaces of the gate portion 60 a, the surface on which the pool portion 60 a 1 is provided is constituted by the gate portion undercut block 62.

(4) Positional relationship between the gate portion and the gate portion undercut block The positional relationship between the gate portion 60a and the gate portion undercut block 62 is shown in FIGS. FIG. 8A is a perspective view of the gate portion undercut block 62, and FIG. 8B is a front view of the gate portion undercut block 62. As shown in FIG. 8B, the width W0 of the gate undercut block 62 is wider than the gate width W1 of the first resin flow path FL1, for example, several mm to several tens on both sides of the gate width W1. The width W0 of the gate undercut block 62 is set by adding about mm. The surface F2 of the gate portion undercut block 62 is formed at a position farther from the gate portion 60a than the third resin flow path FL3. FIG. 9A is a plan view of the gate portion undercut block 62, and FIG. 9B is a side view of the gate portion undercut block 62. 9A and 9B, the relative position of the gate undercut block 62 after the movement is indicated by a two-dot chain line. A solid line in FIGS. 9A and 9B indicates a position when the gate undercut block 62 is attached to the recess 60b of the compression block 60. FIG. 9 (a) and 9 (b), the position indicated by the two-dot chain line is the movement distance of the gate undercut block 62 in the direction perpendicular to the movement direction of the first mold 20 and the second mold 50. The movement of the first mold 20 and the second mold 50 in the moving direction is ignored. It can be seen that the gate portion undercut block 62 is completely separated from the gate portion 60a in a state where the gate portion undercut block 62 is detached from the concave portion 60b of the compression block 60. Thus, the gate part undercut block 62 is completely separated from the gate part 60a after being detached, so that the molded product 90 can be taken out without being deformed even though the gate part 60a has an undercut.

Second Embodiment
Although the said 1st Embodiment demonstrated the case where the molded article 90 was decorated simultaneously with shaping | molding by transferring the decorating layer 91 from the decorating sheet 80, the decorating sheet 85 was combined with the decorating layer. The above-described manufacturing method can also be used when decorating at the same time as molding by attaching the molded product 90 to be a part of the molded product 90. Therefore, the difference in configuration between the injection mold 10 according to the first embodiment and the injection mold 10A according to the second embodiment is transferred by the decorative sheet 80 or the decorative sheet 85 is transferred to the molded product 90. Therefore, the other parts are denoted by the same reference numerals and detailed description thereof is omitted.

(5) Outline of Manufacturing Process of Molded Product FIGS. 10 to 13 are schematic cross-sectional views for explaining the manufacturing process of the resin molded product. FIG. 10A shows the mold open state. In the state of FIG. 10A, the first mold 20 and the outer peripheral plate 54 are in a separated state, and the gate undercut block 62 detached from the recessed portion 60 b of the compression block 60 is also in a separated state from the compression block 60. . The decorative sheet 85 is disposed on the first mold 20 side. FIG. 10B shows a state where the gate undercut block 62 has returned to the compression block 60. At this time, the first mold 20 and the outer peripheral plate 54 are still in a separated state. The gate undercut block 62 is pulled by the movable pin 58a and attached to the recess 60b of the compression block 60, whereby the gate portion 60a of the compression block 60 is formed. FIG. 11A shows the mold closed state. In the state of FIG. 11A, the outer peripheral plate 54 is in close contact with the first mold 20. At this time, the space between the cavity 12 formed by the outer peripheral plate 54 of the first mold 20 and the second mold 50 and the compression block 60 is in a wide state before compression. FIG. 11B shows a state where the molten resin 105 is being injected. The molten resin 105 is injected into the cavity 12 through the gate portion 60a. Since the cavity 12 at this time is before compression, the space is wide. Therefore, the flow rate of the molten resin 105 in the cavity 12 is the same as that before compression in compression molding as compared with the case where the cavity has only an interval substantially equal to the thickness of the molded product, which is not compression molding. In the cavity 12 in a state where the interval is widened, it becomes slow and it becomes difficult to cause a problem such as ink flowing.
In particular, when glass fibers are dispersed as reinforcing fibers in the molten resin 105 at this time, an ink flow is likely to be generated by the molten resin 105. Therefore, the resin molded product according to the second embodiment is manufactured. By applying the method, the effect of suppressing ink flow is remarkably observed. In addition to the glass fibers, the reinforcing fibers include carbon fibers, metal fibers, natural fibers, or composites thereof. In addition, as a resin material that can be used in the method of manufacturing a resin molded product according to the second embodiment, acrylic resin, polyphenylene oxide / polystyrene resin, polyamide resin, polycarbonate resin, styrene copolymer resin, Examples include polystyrene-based blend resins and polypropylene resins.

FIG. 12A shows a state in which the molten resin is cooled after being compressed. The compression block 60 moves relative to the first mold 20 and the outer peripheral plate 54 toward the first mold 20, so that the molten resin 105 (see FIG. )) Is compressed. As a result, even if the molded product 90 is thin, the surface decoration can be beautifully finished without flowing ink. FIG. 12B shows the state of mold opening. The first mold 20 is separated from the outer peripheral plate 54, the compression block 60, and the molded product 90. At this time, the decorative sheet 85 is adhered to the surface of the molded product 90 and remains as the decorative layer 95. At this time, the compression block 60 is maintained in a stopped state relative to the outer peripheral plate 54.
FIG. 13A shows a state where the molded product 90 is protruded. As the compression block 60 moves relative to the outer peripheral plate 54, the gate undercut block 62 is detached from the compression block 60 and the molded product 90 is released from the second mold 50. At the time of taking out the molded product, the gate undercut block 62 is obliquely pushed out by the movable pin 58a, detached from the concave portion 60b of the compression block 60, and moved in a direction along the second molding surface of the compression block 60. The gate resin 92 is detached.
FIG. 13B shows a state after the molded product 90 is taken out. By disposing the decorative sheet 85 in the state of FIG. 13B, the mold opening state shown in FIG.

(6) Features In the method of manufacturing a resin molded product described above, the first step described using FIG. 4 or FIG. 10 (a), the second step described using FIG. 5 or FIG. 11 (a), The third step described with reference to FIG. 5 or FIG. 11 (b), the fourth step described with reference to FIG. 1 or FIG. 12 (a), and the use of FIG. 2, FIG. 3 or FIG. 13 (a). And the fifth step described. In the first step, the

decorative sheets

80 and 85 are disposed on the first molding surface 22 of the first mold 20. In the second step, the outer peripheral plate 54 of the second mold 50 is brought into contact with the first parting surface 21 of the first mold 20, and a part of the second molding surface 52 of the second mold 50 is made against the outer peripheral plate 54. The first mold 20 and the second mold 50 are clamped so that the compressed block 60 that is included is pulled down. In the third step, the first resin flow of the gate portion 60a that is attached to the concave portion 60b that is connected to the gate portion 60a of the compression block 60 so that the gate portion undercut block 62 is in close contact with the compression block 60 and is narrowed into a flat shape. In a state where the gate portion undercut block 62 constitutes one surface of the path FL1, the resin is directly injected from the direction intersecting the second molding surface 52 through the first resin flow path FL1. In the fourth step, the gate undercut block 62 is moved relative to the first mold 20 together with the compression block 60 with the gate undercut block 62 mounted in the recess 60b, and the compression block 60 and the gate are moved. The molten resin 105 is compressed by the second molding surface 52 included in the partial undercut block 62. In the fifth step, the gate undercut block 62 is moved in the protruding direction of the molded product 90 and removed from the gate resin 92 by moving in the direction along the second molding surface 52.

In the

injection molds

10 and 10A described above, the first molding surface 22 and the first parting surface 21 of the first mold 20 are abutted when the molten resin 105 is injected, for example, as shown in FIG. A space (cavity 12) surrounded by the outer peripheral plate 54 and the second molding surface 52 of the compression block 60 is formed in order to mold the molded product 90 as shown in FIG. 1 or FIG. The space between the first molding surface 22 and the second molding surface 52 is smaller than the cavity 12 during compression formed by combining the first parting surface 21 of the first mold 20 and the second parting surface 51 of the second mold 50. It is getting wider. At this time, the gate undercut block 62 is mounted in the recess 60b of the compression block 60, and the first resin flow path FL1 is narrowed to a flat shape. Therefore, when the molten resin 105 is injected from the first resin flow path FL1 to the first molding surface 22 on which the

decorative sheets

80 and 85 are arranged, the

decorative sheets

80 and 85 are decorated from the molten resin 105. The stress which a layer receives can be made small and the ink flow of the decoration layer of the molded article 90 is suppressed. Further, since the gate portion undercut block 62 is in close contact with the recess 60b from the time of injection to the time of compression, problems such as molten resin flowing between the compression block 60 and the gate portion undercut block 62 can be prevented. . Further, in order to narrow the gate portion 60a, the shape of the gate resin 92 is undercut by the gate portion undercut block 62 to prevent back flow of the resin during compression, while the gate portion undercut block 62 has the second portion. Since it moves in the direction along the molding surface 52 and disengages from the gate resin 92, it is possible to prevent problems such as the deformation of the molded product 90 by the gate undercut block 62 being caught by the gate resin 92 when the molded product is taken out. It is.

In the

injection molds

10 and 10A, the movable portion 58, the movable pin 58a, the second air cylinder 65, and the movable portion 65a (an example of a gate portion undercut block moving mechanism) securely secure the gate portion undercut block 62. It can be operated. It is possible to prevent problems caused by the gate part undercut block 62 not being in close contact with the compression block 60 and problems caused by the gate part undercut block 62 not being smoothly removed from the gate resin 92. it can.

Further, in the

injection molds

10 and 10A, the distance d1 between the openings of the first resin flow path FL1 is 0.25 times or more the distance Th when the first molding surface 22 and the second molding surface 52 are compressed. Since the ratio is 7 times or less, the product in the vicinity of the gate portion 60a is made to the extent that the volume of the first resin flow path FL1 is inconspicuous in the molded product 90 after molding while sufficiently preventing ink flow. The thickness can be reduced with respect to the wall thickness.

The compression block 60 has a gate portion 60a disposed substantially at the center of the second molding surface 52, the gate portion 60a having a second resin flow path FL2 that is connected to the first resin flow path FL1, and the shape of the cavity 12 Is a substantially rectangular shape when viewed from a direction perpendicular to the second molding surface 52, the length of the diagonal line of the cavity 12 is ML inches, and the first resin flow path FL1 and the second resin flow path FL2 overlap. The amount OL is set to ML × 0.2 or more and ML × 0.3 or less, and the width of the first resin flow path FL1 is set as follows. That is, the width of the first resin flow path FL1 is set to ML × 6 mm or more and ML × 10 mm or less when ML is 10 inches or less, and is set to ML × 4.5 mm or more and ML × 17 mm or less when ML is 10 inches or less. . With such a configuration, in the

injection molds

10 and 10A, the stress applied to the

decorative sheets

80 and 85 by the molten resin 105 is relieved, and the molten resin is transferred from the second resin flow path FL2 to the first resin flow path FL1. The resin can be filled into the cavity 12 easily.

In the third step described above, the molten resin 105 in which the reinforcing fibers are dispersed is injected through the flat first resin flow path FL1, and in the fourth step, the compression block 60 and the gate portion undercut block 62 are injected. The included second molding surface 52 is compressed until the distance Th between the first molding surface 22 and the second molding surface 52 is not less than the target product thickness around the gate portion 60a and not more than 1.2 mm. As a result, even when the product thickness is 1.2 mm or less, the

decorative sheets

80 and 85 are added when the molten resin 105 containing the reinforcing fibers is injected while maintaining the high strength of the molded product 90 with the reinforcing fibers. The ink flow of the decoration layer can be suppressed.

In the third step described above, the molten resin 105 in which the glass fibers are dispersed as reinforcing fibers is injected through the flat first resin flow path. In the fourth step, the first molding surface 22 and the second molding surface are injected. When the shape of the cavity 12 surrounded by 52 is substantially rectangular when viewed from the direction perpendicular to the second molding surface 52, the diagonal length ML of the cavity 12 is 4 inches or more and 6 inches or less. The distance Th between the first molding surface 22 and the second molding surface 52 is compressed until it is within the range of the product target wall thickness around the gate portion 60a and within the range of 0.5 mm to 0.7 mm. Even when the molded product 90 has a thin product thickness of about 0.7 mm, deformation during molding can be reduced.

(7) Modification (7-1)
As mentioned above, although 1st Embodiment and 2nd Embodiment of this invention were described, in each said embodiment, although the 1st molding surface 22 exists in the cavity side and the 2nd molding surface 52 exists in the core side, conversely The first molding surface 22 may be on the core side, and the second molding surface 52 may be on the cavity side.
(7-2)
In each of the above embodiments, the case of a single-piece injection mold for molding one molded product 90 with one

injection mold

10, 10A has been described, but the

injection mold

10, 10A is The present invention can also be applied to a multi-cavity injection mold, and for example, a plurality of resin flow paths can be provided in the manifold 69 to change the configuration of the

injection molds

10 and 10A to a multi-cavity.
(7-3)
In each of the above embodiments, in the fifth step, the gate undercut block 62 is moved in the protruding direction of the molded product 90 and is moved away from the gate resin 92 by moving in the direction along the second molding surface 52. The case where the

injection molds

10 and 10A are configured has been described. However, when moved in the protruding direction of the molded product, the gate undercut block does not move in the direction along the second molding surface, for example, the robot moves the molded product in the direction along the second molding surface. It may be configured to move. That is, it is only necessary to be configured to move in the direction along the second molding surface relative to the molded product from which the gate portion undercut block is projected.

10, 10A Injection mold 12 Cavity 20 First mold 22 First molding surface 50 Second mold 52 Second molding surface 54 Peripheral plate 58 Movable plate 58a Movable pin 60 Compression block 62 Gate part undercut block 65 Air cylinder 65a Movable part FL1 1st resin flow path FL2 2nd resin flow path

Claims

A first mold surface on which the decorative sheet is arranged is formed on the first parting surface, and a second parting surface that is in contact with the first parting surface on the first molding surface An injection mold having a second mold on which an opposing second molding surface is formed,
The second type is
Compression in which a part of the second molding surface, a gate portion for directly injecting resin from a direction intersecting the second molding surface, and a concave portion connected to the gate portion are formed. Block,
An outer peripheral plate disposed around the compression block for compression of the molten resin injected into a cavity surrounded by the first molding surface and the second molding surface;
The first resin flow path includes a part of the second molding surface, is detachably disposed in the concave portion, and forms the first resin flow path in which the gate portion is narrowed in a flat shape in a state of being attached to the concave portion. A gate portion undercut block constituting one surface of the first resin flow path;
Have
The gate undercut block is
In the state where the compression block is pulled down with respect to the outer peripheral plate at the time of injection of the molten resin in which the outer peripheral plate comes into contact with the first parting surface, the compression block is attached to the concave portion and is in close contact with the compression block. The injection molding is configured to compress the molten resin by the second molding surface together with the compression block while being attached to the recess, and to be detached from the recess and removed from the gate resin when the molded product is taken out. Mold.
The state in which the gate undercut block is attached to the recess and is in close contact with the compression block is maintained at the time of injection of molten resin, and together with the compression block, the gate undercut block is attached to the recess during compression. The gate portion undercut block is moved relative to the first mold to compress the molten resin, and the gate portion undercut block is moved in the protruding direction of the molded product when the molded product is taken out. Further comprising a gate part undercut block moving mechanism to be removed from,
The injection mold according to claim 1.
In the second mold, the gap between the openings of the first resin flow path narrowed by the gate undercut block in a state where the gate undercut block is mounted in the recess is in the vicinity of the gate portion. The interval between the first molding surface and the second molding surface during compression is not less than 0.25 times and not more than 0.7 times.
The injection mold according to claim 1 or 2.
In the compression block, the gate portion is disposed at substantially the center of the second molding surface, the gate portion has a second resin flow path that is connected to the first resin flow path, and the shape of the cavity is When the length of the diagonal line of the cavity is ML inches when viewed from a direction perpendicular to the second molding surface, the overlap between the first resin flow path and the second resin flow path The amount is set to ML × 0.2 mm or more and ML × 0.3 mm or less, and the width of the first resin channel is set to ML × 4.5 mm or more and ML × 17 mm or less.
The injection mold according to claim 3.
A first step in which the decorative sheet is disposed on the first molding surface of the first mold;
The outer peripheral plate of the second mold is brought into contact with the first parting surface of the first mold, and the compression block including a part of the second molding surface of the second mold is pulled down with respect to the outer peripheral plate. A second step in which the first mold and the second mold are clamped,
After the second step, the gate portion undercut block is mounted in a recess connected to the gate portion of the compression block so as to be in close contact with the compression block, and the first resin flow path of the gate portion narrowed in a flat shape A third step of injecting the resin directly from the direction intersecting the second molding surface through the first resin flow path in a state in which the gate portion undercut block is configured on one surface;
The compression block and the gate portion undercut block are moved relative to the first mold together with the compression block while the gate portion undercut block is mounted in the recess. A fourth step of compressing the molten resin with the second molding surface included in
A fifth step of removing the gate part undercut block from the gate resin by moving in the protruding direction of the molded product;
A method for producing a resin molded product.
In the third step, the molten resin in which the reinforcing fibers are dispersed is injected through the flat first resin flow path,
In the fourth step, due to the second molding surface included in the compression block and the gate portion undercut block, the distance between the first molding surface and the second molding surface is a product target meat around the gate portion. Compress until the thickness is greater than or equal to 1.2 mm,
The manufacturing method of the resin molded product of Claim 5.
In the third step, the molten resin in which glass fibers are dispersed as reinforcing fibers is injected through the flat first resin flow path,
In the fourth step, the cavity surrounded by the first molding surface and the second molding surface is substantially rectangular when viewed from a direction perpendicular to the second molding surface. When the length of the diagonal line is 4 inches or more and 6 inches or less, the distance between the first molding surface and the second molding surface is not less than the target product thickness around the gate portion and not less than 0.5 mm and not more than 0.7 mm. Compress until it is within range,
The manufacturing method of the resin molded product of Claim 6.
The resin molding according to any one of claims 5 to 7, wherein the decorative sheet includes a base sheet and a decorative layer formed on the base sheet, and the decorative layer includes a metal thin film layer. Product manufacturing method.