JPS6245887Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a foam molding apparatus, and more particularly to a foam molding apparatus for producing a foam molded article having a density gradient and reinforced through holes.

In recent years, foamed molded products such as polystyrene foam, polyurethane foam, polyethylene foam, and polyvinyl chloride foam have been widely used in insulation materials, cushion materials, packaging materials, flotation materials, building materials, mats, and the like. However, for example, insulation of water tanks and water tanks for flush toilets, dew-proofing materials, etc. must be installed at appropriate locations (e.g., through screw holes).
Connection work with drainage pipes, etc. is essential. The installation and connections require a certain level of strength and perfect sealing, so they are usually installed and connected through packing.

However, in the case of conventional foam molded products, the peripheral edge of the through hole into which the drain pipe is inserted and connected also has a constant thickness, so when the drain pipe flange, foam molded product, tank, and nut are tightened together, the drain pipe flange Since most of the pressed area is tightened, a step is created between it and the surrounding foam molded body, resulting in so-called intergranular cracking (the separation of thermally fused particle interfaces), which prevents water from leaking. Cause.

In addition, when polyethylene foam is a flexible material with low creep resistance, such as polyvinyl chloride foam, it is possible to press (tighten) it until it becomes a thin sheet, so it takes time to tighten the nuts, which reduces work efficiency. Excessive tightening may cause breakage or damage to the molded body, impairing sealing performance.
If excessive tightening is to be avoided, there will be significant individual differences in the degree of tightening among workers, which will eventually lead to troublesome problems such as poor sealing performance.

In view of the above problems, the present invention has a density gradient,
The present invention proposes an apparatus for manufacturing a foamed molded body having partially reinforced through holes.

That is, the present invention provides an apparatus for obtaining a foam molded product by filling thermoplastic foamable resin particles into a mold consisting of a core mold and a cavity mold and heating and expanding the mold, in which a recess is formed in the inner wall of one of the molds, A square-shaped piston is provided on the opposing part of the opposing mold, and has a convex part that fits into the concave part and is movable forward and backward within the concave part, and has a tapered part extending obliquely outward from the lower end of the convex part. The foam molding device is characterized by being movable forward and backward.

The present invention will be explained based on drawings showing embodiments of the present invention. Fig. 1 is a schematic sectional view showing a molding device for a foam molded container having a circular through hole in the bottom, and Fig. 2 is an enlarged sectional view of the main part. It is a diagram. 1 is a core mold, 2 is a cavity mold, 3 is a steam pore, 5, 6
are the steam chambers of the core mold and cavity mold, respectively, and although not shown, steam and cooling water piping are arranged as in a normal device. The cavity mold 2 is equipped with a filler 7 for filling expandable resin particles and a pin 8 for extruding a molded body. Further, a cylindrical recess 2a is formed at the bottom of the cavity mold 2 at approximately the center thereof. On the other hand, the core mold 1 has a columnar protrusion 9a that fits into the recess 2a and is movable back and forth within the recess, and has a tapered part 9b extending obliquely outward from the lower end of the columnar protrusion. A piston 9 is provided so as to be movable forward and backward via a pneumatic cylinder 10. In this way, a mold cavity 4 is formed by the core mold 1, the cavity mold 2, and the square-shaped piston.

The mold cavity 4 is filled with foamable resin particles from a filling device 7. In this case, as shown in FIG. 2, the piston 9 is moved back an appropriate distance to expand the filling volume of the foamable resin particles and fill the enlarged portion, and after heating and expansion, the piston 9 is moved back to line A before cooling. Advance and compression mold.

FIG. 3 is a partial cross-sectional view of the foamed molded product 12 obtained. 13 is a through hole. The density gradient and strength of the foamed product depend on the compression ratio, the expansion ratio of the pre-expanded particles, etc., but it is generally preferred to be about 50 to about 80%, and if it is within this range, the above-mentioned intergranular cracks and work Good sealing properties can be obtained without any problems such as properties.

FIG. 4 shows another embodiment of the square-shaped piston, and shows an example in which steam pores 3 are bored in the tapered portion 9b of the piston. With such a structure, the fear of poor fusion between particles due to insufficient heating is completely eliminated.

FIG. 5 is an enlarged sectional view of a main part showing another embodiment, and shows an example in which the cylindrical recess is a through hole 2b.

The above embodiments all show examples in which the cavity mold is provided with a concave part, but by making some modifications, the same result can be obtained even if the core mold is provided with a concave part and the cavity mold is provided with a convex part. can get. Further, although the description has been made regarding a circular through hole, which is the most common through hole, it goes without saying that the present invention is also applicable to polygonal, elliptical, etc. shapes. Depending on the desired shape of the through hole,
Concave portions, convex portions, etc. having a polygonal or elliptical shape may be used. Further, the 〓-shaped piston may be solid or hollow.

As described above, the present invention provides an apparatus for manufacturing foamed molded products with a simple structure and through holes suitable for installing the foamed molded products and connecting them to drainage pipes, etc., and is extremely practical.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view showing an example of the implementation of the present invention, Fig. 2 is an enlarged sectional view of the main part, Fig. 3 is a partial sectional view of the foam molded product, and Fig. 4 is another embodiment of the square-shaped piston. FIG. 5 is an enlarged sectional view of the main part showing another embodiment of the invention. 1...Core mold, 2...Cavity mold, 2
a, 2b... Cylindrical recess, 3... Steam pore, 4...
Mold cavity, 5... Core mold steam chamber, 6... Cavity mold steam chamber, 7... Filler for foamable resin particles, 8
...Pin for extruding a molded object, 9...〓Shaped piston,
9a... Columnar convex portion, 9b... Tapered portion, 10...
...Pneumatic cylinder, 11...Pin button, 12
...Foamed molded body, 13...Through hole.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. In an apparatus for obtaining a foamed product by filling thermoplastic foamable resin particles into a mold consisting of a core mold and a cavity mold and heating and expanding the mold, a recess is formed in the inner wall of one of the molds. and has a convex part that fits into the concave part and is movable back and forth within the concave part on the opposing part of the opposing mold, and has a tapered part extending obliquely outward from the lower end of the convex part. A foam molding device characterized by a shaped piston that is movable forward and backward. 2. The device according to claim 1 of the utility model registration, in which a small hole is provided in the tapered portion of the shaped piston.