JPH0661827B2 - Method for manufacturing plastic hollow body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a blow molding of a hollow plastic body, such as an air-conditioning duct or panel, which is required to have a shielding property against heat, sound, vibration, electromagnetic waves and the like. The present invention relates to a manufacturing method.

[Prior Art] Conventionally, an air-conditioning duct having a foamed plastic shielding layer on the outer surface is disclosed in Japanese Utility Model Laid-Open No. 53-121657.
As described in Japanese Patent Laid-Open Publication No. Heisei No. 1994-163, those used for various purposes are known.

[Problems to be Solved by the Invention] Generally, in various air-conditioning ducts, it is desirable that the outer surface layer be rigid in order to maintain sufficient strength, and also to be integrally formed in the mounting portion.

However, as described above, in the conventional air-conditioning duct, since the foaming shielding layer is provided on the outer surface, the rigid portion such as the mounting portion cannot be integrally formed.

The present invention solves the above-mentioned drawbacks of the prior art by blow molding a plastic hollow body having a rigid outer surface layer and having a shielding layer adhered to the inner surface and having a high shielding property against heat, sound, vibration, electromagnetic waves and the like. The present invention provides a method for manufacturing, which has a large strength as a whole and allows a rigid portion such as a mounting portion to be integrally formed on the outer surface.

[Means for Solving the Problems] The present invention proposes the following manufacturing method in order to achieve the above object.

That is, it is a method of producing a plastic hollow body having a shielding layer on the inner surface by blow molding,
A method for producing a plastic hollow body, characterized in that a shielding material is inserted into a parison forming an outer surface layer of the hollow body at the time of blow molding to form a shielding layer which is closely adhered and integrated with the inner surface of the hollow body.

[Operation] According to the method for manufacturing a plastic hollow body of the present invention, since the shielding material is inserted into the parison forming the outer surface layer of the hollow body during blow molding, the shielding material adheres to the inner surface of the parison. Then, a shielding layer is formed that is integrated with the inner surface of the hollow body.

[Examples] A method for producing a plastic hollow body according to the present invention will be described with reference to Examples shown in the drawings.

FIG. 1 illustrates an air conditioning duct 1, which is a plastic hollow body molded by the manufacturing method according to the present invention. The air-conditioning duct 1 is manufactured by blow molding plastic, the outer surface layer 2 has rigidity, and the shielding layer 3 of foamed plastic is closely adhered and integrated on the inner surface. Reference numeral 4 is a mounting portion, and this mounting portion 4 is formed integrally with the outer surface layer 2.

2 to 5 show the steps of blow molding the air conditioning duct 1 in order.

That is, 5 and 5 are a pair of split molds, each having a cavity 6 forming the duct 1 and a mounting portion cavity 7 forming the mounting portion 4 inside.

When the blow molding of the air conditioning duct 1 is performed, the parison 9 forming the outer surface layer 2 extruded from the die 8 is placed between the pair of split molds 5 and 5, and the parison is set by the four expansion rods 10.
Expand 9 and insert foam 11 of foamed plastic, which is a shielding material, into Paris 9 in a heat-softened state. Then, by closing the pair of split molds 5, 5 and blowing a pressurized fluid into the parison 9 to perform blow molding, as shown in FIG. 1, the foam 11 is expanded and the shielding layer 3 is formed on the inner surface. The air-conditioning duct 1 in which the components are closely integrated is obtained. In the pinch-off part P of the molded air conditioning duct 1, the foamed structure of the shielding layer 3 is compressed and welded together.

FIG. 6 and FIG. 7 show, as another embodiment, foam on a part of the inner surface of the air conditioning duct 1, that is, a pair of wide surfaces.
The blow-molding mode of 11 intimately integrated is shown. In this embodiment, a pair of expanding jigs 12 are used to expand the parison 9 arranged in the pair of split molds 5, 5. The pair of expanding jigs 12 correspond to the pair of narrow surfaces of the air conditioning duct 1.

The air-conditioning duct 1 configured as described above uses a thermoplastic such as polyethylene or polypropylene, and the foam 11 is a plastic having a foaming ratio of 1.2 to 80 times. Incidentally, instead of the foam 11, natural fiber, semi-synthetic fiber,
It may be a shielding material such as a woven fabric, a knitted fabric or a non-woven fabric made of synthetic fibers and these Brent fibers.

[Effects of the Invention] The present invention is a method for producing a plastic hollow body having a shielding layer on the inner surface by blow molding, wherein a shielding material is inserted into the parison forming the outer surface layer of the hollow body during blow molding. Since this is a method of forming a tightly integrated shield layer on the inner surface of the hollow body, the outer surface layer is rigid, and the inner surface has a shield layer with high heat, sound, vibration, and electromagnetic wave shielding properties. The plastic hollow body can be manufactured by blow molding, and by this method, the strength as a whole is large and the rigid portion such as the mounting portion can be integrally molded on the outer surface.

[Brief description of drawings]

FIG. 1 is a perspective view showing a part of an air conditioning duct manufactured by the method according to the present invention, and FIGS. 2, 3, 4, and 5 show an embodiment of the method according to the present invention. FIG. 2 shows a blow molding process, FIG. 2 is a vertical sectional front view, FIG. 3 is a sectional view taken along the line AA in FIG. 2, FIG. 4 is a transverse sectional view showing a state in which the parison is expanded, and FIG. Same as the above, a cross-sectional view showing the mold closed state, FIGS. 6 and 7 are cross-sectional views showing the blow molding process of another embodiment, and FIG. 6 is a cross-sectional view showing the state before the mold is closed, FIG. 7 is a cross-sectional view showing a state in which the mold is closed. 1 …… Air conditioning duct, 2 …… Outer surface layer, 3 …… Shield layer, 4
…… Mounting part, 5,5 …… A pair of split molds, 6 …… Cavity, 7 …… Mounting part cavity, 8 …… Die, 9 …… Parisson, 10 …… Expanding rod, 11 …… Foam , 12 …… Expansion jig

Claims (1)

[Claims] 1. A method for producing a plastic hollow body having a shielding layer on its inner surface by blow molding, wherein a shielding material is inserted into a parison forming an outer surface layer of the hollow body during blow molding. A method for producing a plastic hollow body, comprising forming a shielding layer which is intimately adhered and integrated with an inner surface.