JPS58205740A - Mold for foaming synthetic resin - Google Patents

Abstract

PURPOSE:To provide the titled mold capable of effectively preventing generation of burrs, wherein a hollow elastic body is placed in a vacant space provided in proximity to a cavity end edge at a parting surface of a metallic mold, and the cavity end edge is sealed. CONSTITUTION:The vacant space 15 is provided in proximity to the cavity end edge 13a at the parting surface 14 of the metallic mold, and the hollow elastic body 19 capable of being expanded and contracted is placed in the space 15. When molding, a pressure is exerted on the interior of the hollow elastic body 19 to expand the body 19 to conform to the shape of the space 15, thereby sealling the cavity end edge 13a. Accordingly, generation of rejective articles due to permanent strain, deformation or the like of a sealing material can be prevented almost perfectly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for foaming synthetic resin such as polyurethane resin.

For example, cast molding (or injection molding) of polyurethane resin
In this case, there is a tendency to use economical molds because the molding is relatively simple.

Further, other materials such as a core material or an outer shell that reinforce the foam layer to be molded are often integrally molded as insert materials. In these cases, the mold itself has a high degree of precision, and the inserts and materials also have slight variations in wall thickness and shape, so during foam molding, the resin material leaks from many sides of the mold, resulting in so-called molded products. Formed as a deposit. For this reason, a complicated process of removing pars must be added after molding.

In order to prevent this occurrence, conventionally, the resin leakage part, mainly the cracked surface of the cavity edge, has been sealed by pasting a packing material or a sealing material made of an elastic material such as rubber or plastic. However, it has the disadvantage that it is not durable because the sealing material itself may weaken or deform due to heat or pressure. When an insert material such as a core material is clamped and molded, these sealing materials cannot cope with slight variations in the thickness or shape of the insert material.

In view of this situation, this invention proposes to seal the resin leakage part using an expandable and contractible hollow elastic body, and specifically has the following configuration. .

That is, in the first invention, a cavity is formed in the vicinity of the cavity edge of the mold dividing surface, a hollow elastic body is housed in the cavity, and pressure is applied to the inside of the hollow elastic body during molding. It is characterized in that it is expanded into a hollow shape and seals the edge of the cavity.

The second invention relates to the case of integrally molding with an insert material (3), in which a void space is formed at the edge of the insert material and the mold clamping part of a mold in which the insert material is clamped and molded. A hollow elastic body is stored in the cavity, and during molding, pressure is applied inside the hollow elastic body to expand it into the shape of the cavity and seal the edge of the insert material and the mold clamping part. It is characterized by what it did. Embodiments will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a polyurethane resin foam mold 10 showing an embodiment of the first invention, and FIG. 9 is a plan view of a lower mold 11 thereof. As shown, cavity 1 of mold lO
Hollow spaces 15 are formed at corresponding positions on the split surfaces 14 of the lower die 11 and the upper die 12 close to the third edge 13a so as to surround the cavity 13. In the embodiment, a continuous void 15 is formed around the entire circumference of the cavity edge 13a as shown in FIG. 2, but a partial void may be formed depending on the shape of the cavity 13a, insert material, product finish, etc. Alternatively, you are free to create separate spaces. In addition, it is preferable to provide a part of the outer edge of the cavity 13 with a part of the periphery of the cavity 15, as shown in (4) in the figure, in order to obtain a higher sealing performance. Further, it is also possible to form the void 15 only in the splitting surface 14 of one of the molds, for example, the lower mold 11. It is desirable that the cross-sectional shape of the cavity 15 be determined by taking into consideration the expanded shape of the hollow elastic body 19, which will be described below.

The hollow elastic body 19 is a rubber tube 19 in the embodiment shown in FIG.
a is used. The hollow elastic body 19 is expanded into the shape of the cavity 15 by feeding compressed air or a liquid such as water or oil into the hollow elastic body 19 and applying pressure during molding, thereby sealing the cavity edge 13a. Therefore, the material must be able to withstand internal pressure and have a certain degree of elongation, but the foaming pressure during molding is less than IKv3 for polyurethane resin, and the material used for this purpose is Since the pressure of a normal near compressor is 6.vj, a hollow elastic body made of rubber or soft plastic that can withstand a pressure of about 10 x g/d and has an elongation of 150 or more is preferably used. Natural or various synthetic rubbers are used as rubber, and typical examples of soft plastics include polyvinyl chloride resin or polyethylene resin.Among them, slush molded products of polyvinyl chloride resin are hollow molded products that conform to a predetermined shape. This is advantageous because the elastic body is easily obtained. In that case, it is preferable to form the hollow space 15 into a similar shape that is about 1.20% smaller than the shape of the space 15. Reference numeral 18 in FIG. 2 denotes an air pulp of a hollow elastic body 19, which is connected to a near compressor (not shown) outside the mold by a conduit 18a.

Next, the function of the mold 10 will be explained. First, a polyurethane resin raw material is injected into the cavity 13 of the lower mold 11 in which the hollow elastic body 19 is housed in the cavity 15. Next, the upper mold 12 is closed and the mold is clamped by a mold clamping device (not shown) K, and then compressed air is fed into the hollow elastic body 19 by a near compressor to pressurize it and expand it into a hollow shape.
Foam molding is performed while maintaining this state. The hollow elastic body 19 expanded in this state tightly seals the edge of the cavity and seals the foamed resin raw material that tends to leak out from the core. After foam molding, the air release mold in the hollow elastic body 19 is opened and the product is taken out.

Next, the second invention will be described according to the drawings from FIG. 3 onwards. The second invention relates to a mold for molding an insert material by sandwiching it between the molds.

In this case, as mentioned above, the thickness of the insert material,
Due to variations in shape such as dimensions, clamping to the mold often becomes insufficient, and resin leaks through the gap between the insert material and the mold bonding part, causing particles to adhere to the product. Fifth
The figure is a cross-sectional view of the case where the skin 31 and the polyurethane foam resin 32 are integrally molded using the core material 30 as an insert material using a conventional mold 40. However, as shown in FIG. The resin raw material that leaked out from the slight gap in the mold bonding part 44 went around to the back side of the core material 30 (2nd side) and deposited burr, which necessitated a finishing process to remove burr as shown in Figure 1 before it could be made into a product. There is.

The object of the second invention is to seal the edge of the core material and the mold bonding part in such a case.

FIG. 3 is a cross-sectional view showing an embodiment of the present invention, showing the state during molding, and FIG. 21 is a lower mold, 22 is an upper mold, 23 is a cavity, 24 is a mold bonding part of the core material 30, 25 is a cavity, 2 is an air valve, 29 is a hollow elastic body, and here represents an air bag 29a. .

As shown in the figure, this invention forms a cavity 25 at the edge 24a of the insert material 30 and the mold adhesive part 24, and the cavity 2
A hollow elastic body 29 is housed in the hollow elastic body 5, and during molding, pressure is applied inside the hollow elastic body 29 to expand it into a hollow shape and seal the edge 24a between the insert material 30 and the mold adhesive part 24. It is characterized by the fact that

In the embodiment, a plurality of cavities 23 are formed into a single skin 23.
The mold 20 is configured to obtain a plurality of products at the same time.Due to the mold structure, a cavity 15 is formed only in the upper mold 22, but as shown by a broken line 25a in FIG. It may be formed by inserting it into a part of 21. Furthermore, if the core material 30 itself is compressed by the air bag 29 when it is inflated as shown in the figure, the shape of the core material thickness, etc., which cannot be expected when the molds are sandwiched together, can be improved. It has the advantage of being able to absorb the above variations.

In addition, when the cavity shape 25 is somewhat complicated, it is preferable to obtain the airbag 291L by a slush molded product of polyvinyl chloride resin as described above. In this case, a similar shape that is slightly smaller than the shape of the space 25 is used, as described above.

Other than that, the material and properties of the hollow elastic body, the function of the mold, etc. are the same as in the first invention, so the description of the relevant parts will be replaced.

As described above, according to the present invention, it is possible to minimize and effectively prevent the occurrence of flakes in this type of synthetic resin foam mold (9). In particular, by using a hollow elastic body, it is possible to almost completely prevent the occurrence of defective products due to the fading or deformation of conventional sealing materials, etc., and the sealing effect is also extremely excellent, making it possible to prevent the occurrence of defects after molding. It has great advantages in terms of omission of the removal process, quality control, etc.

In addition, in the second invention, the hollow elastic body can absorb variations in the shape of the core material such as thickness and dimensions, which is impossible with the sealing material, so integral molding with the insert material is often used. This invention has great effects in foam molding.

[Brief explanation of drawings]

- Fig. 1 is a sectional view of a foaming mold showing an embodiment of the first invention, Fig. 2 is a plan view of the lower die of the mold, and Fig. 3 is an embodiment of the second invention. A cross-sectional view of the mold during molding, Figure 4 is a cross-sectional view of the main parts before molding, Figure 5 is a cross-sectional view of a conventional foam mold, and Figure 6 is a cross-sectional view of the main parts of the molded product immediately after molding. The enlarged sectional view, Figure 1, is also after finishing (10
) is an enlarged cross-sectional view. 10... Foaming mold, 13... Cavity, 1
3a -- Cavity edge, 14... Split surface, 1
5... Blank space, 16... Kikiri υ part, 19...
Hollow elastic body, 20... Foaming mold, 23... Cavity, 24... Mold clamping part, 24a... Clamping part edge, 25... Hollow space, 29... Hollow Elastic body. Patent applicant Inoue MBC Co., Ltd. (11) Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. A cavity is formed close to the edge of the cavity on the mold splitting surface, a hollow elastic body is housed in the cavity, and pressure is applied inside the hollow elastic body during molding. 1. A synthetic resin foam molding mold, characterized in that the synthetic resin foaming mold is expanded into a hollow shape to seal an edge of the cavity. Z. The synthetic resin foaming mold according to claim 1, wherein the void space is formed on the outer periphery of the cut-out portion of the outer edge of the cavity. (5) A hollow space is formed at the edge of the insert material and the bonded part of the mold in a mold for sandwiching and molding the insert material, and a hollow elastic body is housed in the hollow space, and during molding, the hollow elastic body is 1. A synthetic resin foam molding mold, characterized in that pressure is applied to the inside of the body to expand it into a hollow shape and seal the edge of the insert material and the mold bonding part. 4. The synthetic resin foaming mold according to claim 3, wherein the hollow elastic body is formed into a similar shape that is slightly smaller than the shape of the cavity.