JPH0525864Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a foaming method used in injection molding for molding rubber molded products and resin molded products, especially reaction injection molding (RIM) in which gas is generated during molding. This invention relates to molds for molded products.

[Prior art] Conventionally, especially in RIM urethane molding, when molding a foam molded product that has a rib-like protrusion in a part, the tip of the recess for rib molding of the molded product is The generated gas and the air in the cavity are compressed, creating an air pocket, which prevents the material from turning around at the tip of the rib, leading to chipping, which can result in defective products. Therefore, it is necessary to discharge air, etc. accumulated at the tip of the molding recess to the outside of the mold.

Therefore, for example, as shown in FIG.
An air vent 16 is provided that communicates the tip of the rib molding recess 14 that is integrated with the molded product-shaped cavity 13 formed by the upper mold 12 and the notch 15 provided on the upper surface of the upper mold 12. The air accumulated in the rib forming recess 14 is extracted to the notch 15 together with the molding material.

In addition, if the molded product cannot be taken out if the molding material is released outside the mold, as shown in FIG. An extension recess 17 is provided at the tip of the rib forming recess 14, and the rib forming recess 1
Air accumulated in the molding material 4 is extracted into the extended recess 17 together with the molding material.

[The problem that the idea aims to solve]

However, in the mold shown in FIG. 3 above, when the air vent 16 is located on the opposite side from the operator, when removing the excess molding material discharged into the notch 15,
There were problems in that workers were slow to work and lost work time. In addition, the mold shown in FIG. 4 requires cutting of the extension protrusion formed by the extension recess 17, and the air in the extension recess 17 may cause molding defects due to chips in the ribs of the molded product. There was a problem that this could occur.

An object of the present invention is to provide a mold for foam molded products that has excellent workability and does not require post-processing after molding.

[Means to solve the problem]

In order to achieve the above object, the mold for a foam molded product of the present invention is a mold for a foam molded product for molding a foam molded product having a protrusion in a part thereof, and includes a pair of molds. When combined together, a cavity is formed for molding a foam molded product, and one of the molds is provided with an extending recess for forming a protrusion of the molded product extending from the cavity,
The mold dividing surface of the other mold is provided with a material reservoir recess for discharging gas etc. during molding from the extending recess along with the molding material and storing surplus material of the molding material, and the material reservoir recess is provided in the extending recess. A means is adopted in which the tip of the recess and the extending portion are communicated with each other through a tapered communication hole that has a small diameter and widens toward the material reservoir recess.

[Effect]

By adopting the above means, when molding a foam molded product by injecting a foam molding material into the cavity, the extension for forming the protrusion of the molded product that extends from the cavity provided in one mold is possible. The molding material is also injected into the recess, and the gas generated in the molding material and the air inside the cavity are pushed into the extending recess, but the gas, etc. is provided on the mold splitting surface of the other mold. Since the molding material is extruded into the material reservoir recess through the communication hole, the tip of the protrusion of the molded product will not be chipped due to gas or the like. Furthermore, the communication hole is formed in a tapered shape with a small diameter on the extending recess side and an enlarged diameter toward the material reservoir recess side, so the molding material flowing through the communication hole flows smoothly and gas etc. also flows into the material reservoir recess. Discharges smoothly. Also,
When the pair of molds are opened after molding, since the communicating hole has a smaller diameter on the extending concave side, the molded solidified material in the communicating hole is easily cut and separated from the tip of the protrusion of the molded product. Therefore, a foamed molded product having a protruding portion that is not chipped by gas or the like can be easily taken out from the mold.

〔Example〕

An embodiment embodying the present invention will be described below with reference to FIGS. 1 and 2.

As shown in Fig. 1, a cavity 3 in the shape of a product with curved ends is formed on the parting surface (PL surface) of a lower mold 1 and an upper mold 2 as a pair of molds for foam molded products.
is formed. The upper mold 2 is provided with an extending recess 4 that extends from the cavity 3 and is enlarged on the side of the cavity 3, and the extended recess 4 is designed to form a rib that is a protrusion of the foam molded product. It's summery.

A material reservoir recess 5 having a substantially rectangular cross section is provided on the PL surface of the lower mold 1, and the excess molding material discharged through the communication hole 6 containing gas etc. is accommodated therein. . In addition, the upper mold 2 includes:
Between the tip of the extending recess 4 and the material reservoir recess 5 of the lower mold 1, there is a material reservoir recess 5 with a smaller diameter on the extending recess 4 side.
A tapered communication hole 6 with an enlarged diameter on the side is provided through the hole. Through this communication hole 6, gas and the like that tend to accumulate at the tip of the extending recess 4 are smoothly extracted together with the molding material toward the material reservoir recess 5 side of the lower mold 1.

The end E of the communicating hole 6, which is the connecting part between the communicating hole 6 and the extending recess 4, has a diameter so that it can be cut automatically when opening the mold, and to eliminate the need for post-finishing of the cut part after cutting. It is desirable to have a small diameter of about 1 mm. In addition, the central axis of the communication hole 6 is aligned with the extending recess 4 in order to facilitate automatic cutting when opening the mold.
The angle between the center axis and the center axis is set to be between 40 degrees and 50 degrees. Further, surplus molding material containing gas etc. is easily extracted from the extending recess 4 into the material reservoir recess 5, and the molded solidified material in the communication hole 6 is extracted together with the molded product in the material reservoir recess 5 after molding. Therefore, the communicating hole 6 is formed in a tapered shape, and the connecting portion between the communicating hole 6 and the material reservoir recess 5 is set to be somewhat large. Note that the above taper angle is 10 to 15 degrees.

An undercut portion 7 that slightly protrudes toward the material storage recess 5 is formed at the upper part of the material storage recess 5, and the undercut portion 7 channels the surplus molding material discharged into the material storage recess 5 into the communication manner. Together with the solidified material in the hole 6, the lower mold 1 is removed when the mold is opened.
At the same time, the molded solidified material in the communication hole 6 can be automatically cut at the end E of the communication hole 6 on the extending recess 4 side.

The functions and effects of the mold for foam molded products configured as described above will be explained.

As shown in FIG. 1, when the lower mold 1 and the upper mold 2 are in a clamped state, a foam molding material such as liquid polyisocyanate, polyol, chain extender, foaming agent, etc. is injected into the cavity 3. Note that a filler such as glass fiber can also be blended as a molding material. Then, this polyisocyanate,
The polyol, chain extender, etc. proceed through the cavity 3 to the end while reacting, and the extension recess 4 is also filled. At this time, the gas generated by the above reaction and the air inside the cavity 3 are forced into the tip of the extending recess 4 and tend to accumulate therein.

However, these gases and the like are discharged together with the molding material from the tip end (upper part in FIG. 1) of the extended recess 4 into the communicating hole 6. The gases and the like then pass through the tapered communicating hole 6 and are further discharged into the material reservoir recess 5 of the lower mold 1. As a result, gases and the like do not remain at the tip end of the extended recess 4 that is used to form the protrusion of the foam-molded product, and it is possible to mold a protrusion without any chipping.

After the molding is completed in this manner, the lower mold 1 and the upper mold 2 are opened. At this time, as shown in FIG. 2, the molded product in the material reservoir recess 5 is retained on the lower mold 1 side together with the molded solidified material in the communication hole 6 by the undercut portion 7 provided in the recess 5. Therefore, the molded solidified product in the communicating hole 6 is automatically cut off from the molded product in the extending recess 4 at the end E of the communicating hole 6. Next, by separating the molded product on the lower surface of the upper mold 2 from the upper mold 2, a foamed molded product having a protrusion, for example, a pad for an automobile steering wheel is obtained.

As described above, according to the mold for foam molded products of this embodiment, even if the communication hole 6 and the material reservoir recess 5 are located on the opposite side of the operator, the communication hole 6 and the material reservoir recess 5 can be The molded solidified product and the molded product in the extending recess 4 can be easily cut, and excess molding material for degassing can be taken out from the mold dividing surface, reducing the difficulty of the operator's work and reducing the work involved in taking out the material. There is little loss of working time, there is no need to perform post-processing of the cut portion, and there is no occurrence of molding defects due to chipping of the molded product in the extending recess 4.

As described above, in the mold for foam molded products of the present invention, reactive gas is generated, and because the injection pressure is low, the gas tends to accumulate in the narrow portion of the extending recess 4 for forming the ribs of the molded product. Moreover, it has a design that prevents the molded product from chipping due to the gas.
Suitable as a mold for RIM molding.

The present invention is not limited to the above-mentioned embodiments, and can be modified as desired without departing from the spirit of the invention. For example, it can be configured as follows.

That is, in the above embodiment, the undercut portion 7 is provided in the material reservoir recess 5 of the lower die 1, but this undercut portion 7 can be omitted. In this case, when the lower mold 1 is opened from the upper mold 2, the material reservoir recess 5
The molded solidified material in the communication hole 6 moves toward the upper mold 2 side together with the molded product in the extending recess 4. Subsequently, by pulling the molded solidified product in the material storage recess 5 by hand, it can be cut from the molded product at the end E of the communication hole 6 and easily taken out.

[Effect of idea]

The metal fitting for foam molded products of the present invention can be used to mold a foam molded product that has a protrusion in a part thereof, without causing molding defects such as chips due to gas accumulation at the tip of the protrusion. Can be molded. Further, the work of removing the surplus molding material discharged together with the gas etc. can be easily carried out, and the workability is good.

[Brief explanation of the drawing]

1 and 2 are views showing an embodiment of the present invention, in which FIG. 1 is a cross-sectional view of the mold showing the mold closing state, FIG. 2 is a cross-sectional view of the mold showing the mold opening state, FIGS. 3 and 4 are diagrams showing conventional molds,
Figure 3 is a sectional view showing a mold with an air vent;
FIG. 4 is a sectional view showing a mold having an extended recess. 1...Lower mold, 2...Upper mold, 3...Cavity,
4...Extending recess, 5...Material reservoir recess, 6...Communication hole.

Claims (1)

[Claims for Utility Model Registration] A mold for a foam molded product for molding a foam molded product having a protrusion in a part thereof, which is formed by molding a pair of molds 1 and 2 together. In addition to forming a cavity 3 for molding the product, one of the molds 2 is provided with an extending recess 4 for forming a protrusion of the molded product extending from the cavity 3, and the splitting surface of the other mold 1 is is provided with a material reservoir recess 5 for discharging gas during molding together with the molding material from the extending recess 4 and storing surplus material of the molding material, and the material reservoir recess 5 is located at the tip of the extending recess 4. A mold for a foam molded product, characterized in that the part and the extending recess 4 are connected to each other by a tapered communication hole 6 which has a small diameter and widens toward the material reservoir recess 5 side.