Manufacturing method for resin molded products

Abstract

To increase a degree of freedom in material selection for a resin molded product and to improve a bonding strength between members.SOLUTION: A method for manufacturing a resin molded product 10 includes: a step of molding a first member 11 by filling a first cavity S1 formed between a fixed mold 1 and a movable mold 2 with a first resin material; a step of filling a second cavity S2 formed between the first member 11 and the movable mold 2 with a second resin material 14 by retracting the movable mold 2; and a step of molding a second member 12 by further retracting the movable mold 2 to foam the second resin material 14 in the second cavity S2. The step of molding the first member 11 includes filling the first cavity S1 into which a slide pin 3 is inserted with the first resin material. The step of filling the second cavity S2 with the second resin material 14 includes filling an interior of a through hole 13 with the second resin material 14 after pulling the slide pin 3 from the first member 11, and forming the through hole 13 in the first member 11.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin molded product. [Background technology]

[0002] One type of injection foam molding method is the core-back method. In this method, a mold consisting of a fixed mold and a movable mold is filled with a resin containing a foaming agent, and then the movable mold is retracted from the fixed mold to expand the cavity volume and foam the resin, thereby obtaining a foam. On the other hand, the core-back method is also widely used in two-color molding, in which two different types of resin are molded together, and core-backing is performed after primary molding to form a cavity for secondary molding. Therefore, a technology is known that applies this method and performs core-backing in two stages to integrally mold a secondary molded part made of a foamable resin with a primary molded part made of a different resin (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5714333 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned technology, it is necessary to select a resin material with good adhesive properties (compatibility) to ensure sufficient bonding strength between resin components. However, due to functional constraints and other factors, it is often difficult to select such a material, and the current situation is that the range of application is limited.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for manufacturing a resin molded product that increases the degree of freedom in material selection and improves the bonding strength between members. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the manufacturing method of the resin molded product of the present invention is a manufacturing method of a resin molded product in which a first member made of a first resin material and a second member made of a second resin material containing a foaming agent are integrally molded, the manufacturing method comprising: clamping a fixed mold and a movable mold to form a first cavity between them; and filling the first cavity with the first resin material. only and molding a first member by filling the first cavity with a second resin material; and after molding the first member, retracting the movable mold from the fixed mold to form a second cavity between the first member and the movable mold and filling the second cavity with a second resin material; and further retracting the movable mold to foam the second resin material in the second cavity and mold the second member. Multiple Insert the slide pin and Multiple The method includes filling a first resin material into the first cavity into which the slide pin is inserted, and the step of filling a second resin material includes removing the first resin material from the first member before filling the second resin material. Multiple Pull out the slide pin and insert it into the first component. Multiple After the recess is formed, the second resin material is Multiple This includes filling the interior of the recesses. [Effects of the Invention]

[0007] As described above, according to the present invention, it is possible to increase the degree of freedom in the selection of materials for resin molded products and to improve the bonding strength between members. [Brief explanation of the drawings]

[0008] [Figure 1] 1A to 1C are cross-sectional views illustrating steps of a method for manufacturing a resin molded product according to an embodiment of the present invention. [Figure 2] 1A to 1C are cross-sectional views illustrating steps of a method for manufacturing a resin molded product according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The resin molded product manufactured by the manufacturing method of the present invention is not particularly limited in its use or shape, as long as it is an integrally molded product of a first member made of a first resin material and a second member made of a second resin material containing a foaming agent. The type of resin material is also not particularly limited, and various types of resin materials that can be used in injection molding can be used.

[0010] 1(a) to 2(c) are cross-sectional views showing the steps of a method for producing a resin molded article according to one embodiment of the present invention.

[0011] The resin molded product 10 of this embodiment is an integrally molded product of a first member 11 and a second member 12 (see FIG. 2(c)), and is manufactured using a fixed mold 1, a movable mold 2, and a plurality of slide pins 3. The movable mold 2 is provided so as to be able to advance and retreat relative to the fixed mold 1, and the plurality of slide pins 3 penetrate the movable mold 2 parallel to the advance and retreat direction (movement direction) of the movable mold 2, and are provided so as to be able to slide relative to the movable mold 2.

[0012] The method for producing the resin molded product 10 is roughly divided into a primary molding step shown in FIG. 1 and a secondary molding step shown in FIG.

[0013] In the primary molding step, first, as shown in FIG. 1(a), the movable mold 2 is advanced toward the fixed mold 1, and the fixed mold 1 and the movable mold 2 are clamped together. This forms a first cavity S1 between the fixed mold 1 and the movable mold 2. Simultaneously with or after this, as shown in FIG. 1(b), the slide pin 3 is advanced toward the fixed mold 1 and inserted into the first cavity S1. Then, a molten primary molding resin (first resin material) is injected through a gate (not shown) provided in the fixed mold 1 to fill the first cavity S1 into which the slide pin 3 has been inserted. Thereafter, the primary molding resin is cooled and hardened, thereby forming a primary molded member (first member) 11, as shown in FIG. 1(c).

[0014] Once the primary molding member 11 has been molded in this manner, as shown in FIG. 2(a), the movable mold 2 is retracted from the fixed mold 1 to perform a core-back operation, and at the same time, the slide pins 3 are retracted from the fixed mold 1 to extract the primary molding member 11. As a result, a second cavity S2 is formed between the fixed mold 1 and the movable mold 2, i.e., between the primary molding member 11 and the movable mold 2, and a through-hole 13 communicating with the second cavity S2 is formed in the primary molding member 11. Then, a molten secondary molding resin (second resin material) 14 containing a foaming agent is injected into the second cavity S2 through a gate (not shown) provided in the fixed mold 1, and the secondary molding resin 14 is filled up to the inside of the through-hole 13 in the first member 11, as shown in FIG. 2(b).

[0015] 2(c), a second core-back is performed to further retract the movable mold 2 (and slide pin 3) from the fixed mold 1, expanding the volume of the second cavity S2 and foaming the secondary molding resin 14 in the second cavity S2. The secondary molding resin 14 is then cooled and hardened, whereby the secondary molding member 12 is molded integrally with the primary molding member 11, completing the secondary molding process.

[0016] According to the manufacturing method of this embodiment, the secondary molded member 12 penetrates the through-holes 13 of the primary molded member 11, thereby increasing the bonding area and improving the bonding strength between them through a so-called anchor effect. Therefore, even when functional constraints necessitate the selection of resin materials with poor adhesive properties (compatibility) for the primary molded member 11 and the secondary molded member 12, sufficient bonding strength can be ensured between the primary molded member 11 and the secondary molded member 12. This increases the flexibility in selecting materials for the two members 11 and 12, enabling the selection of various material combinations. Therefore, this manufacturing method of this embodiment is particularly useful when using difficult-to-bond materials such as polypropylene (PP). For example, even when a highly elastic resin material, such as an elastomer used in vibration-damping materials, is selected as the primary molded resin and PP is selected as the secondary molded resin, it is possible to bond (integrally mold) an elastic member with a function such as vibration damping to a foam-molded PP member without performing pretreatment or the bonding process itself.

[0017] In the primary molding step, the slide pins 3 do not have to reach the bottom surface of the first cavity S1. That is, in the secondary molding step, recesses may be formed in the first member 11 instead of the through holes 13, and in this case, a similar anchoring effect can also be obtained. In addition, the number of slide pins 3 is not particularly limited, and an appropriate number of slide pins 3 can be provided depending on various conditions, such as the shapes and dimensions of the primary molded member 11 and the secondary molded member 12, and the compatibility between the resin materials. [Explanation of symbols]

[0018] 1 Fixed type 2 Movable type 3 Slide Pin 10 Resin molded products 11 Primary molding member (first member) 12 Secondary formed member (second member) 13 Through hole 14 Secondary molding resin (second resin material) S1 First cavity S2 Second cavity

Claims

1. A method for manufacturing a resin molded product in which a first member made of a first resin material and a second member made of a second resin material containing a foaming agent are integrally molded, the method comprising: a step of clamping a fixed mold and a movable mold to form a first cavity therebetween, and filling the first cavity with only the first resin material to mold the first member; a step of, after molding the first member, retracting the movable mold from the fixed mold to form a second cavity between the first member and the movable mold, and filling the second cavity with the second resin material; and further retracting the movable mold to foam the second resin material in the second cavity, thereby molding the second member. the step of molding the first member includes inserting a plurality of slide pins into the first cavity before filling the first resin material, and filling the first cavity with the first resin material into which the plurality of slide pins have been inserted; a step of filling the second resin material includes: pulling out the slide pins from the first member before filling the second resin material; forming a plurality of recesses in the first member; and then filling the second resin material into the interiors of the plurality of recesses.

2. 2. The method for manufacturing a resin molded product according to claim 1, wherein the plurality of slide pins are inserted and extracted in a direction parallel to a direction in which the movable mold moves relative to the first cavity.

3. The method for manufacturing a resin molded product according to claim 1 or 2, wherein the plurality of slide pins are slidably provided on the movable die.

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