JPH02175131A - Formation of cylindrical body - Google Patents

Abstract

PURPOSE:To provide both end opening sections of accurate inner diameter dimension, eliminate cutting of one side opening section of a molded product and prevent the generation of mold split line trace such as in a blow molded product by bonding a cylindrical body to a core bar, molding, and then melting the metal core bar. CONSTITUTION:A core bar 2 having an outer peripheral section of a bellows type shape corresponding with a bellows shape inner diameter section of a product by being formed with a low melting metal is installed around a core bar supporting shaft 1, and a cylindrical body 3 formed with heat-shrinkable resin is heated and bonded in a manner of coating the outer peripheral-section of the core bar 2. After that, the core bar 2 and the cylindrical body 3 are cooled simultaneously to solidify and mold the cylindrical body 3 in conformity with the outer peripheral shape of the core bar 2. Then, the core bar 2 and the cylindrical body 3 are disposed in an induction heating coil and heated, and the core bar 2 is melted at the low temperature leaving the resin cylindrical body 3 only.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a molding method, particularly a method for molding a cylindrical resin product.

(Prior Art) As a conventional molding technology, there is a blow molding method. The outline of this molding method will be explained with reference to FIG. 7. The molding machine 1OO consists of a pair of molds 101 and 102, and has a cavity 103 inside. 104 is a temperature adjustment hole, and 105 is an extruder goose. A thermoplastic resin such as vinyl chloride, polyethylene, polypropylene, or polycarbonate is heated and melted and extruded into a pipe or two sheets using a vertical extruder. When the pipe or sheet is long enough, it is molded into a mold 101. , mold 1
Close 02, cut out the bottom part, and close the resin vibrator. Next, air is blown into the center of the die 105, the resin is brought into close contact with the molds 101 and 102, and the resin is allowed to stand until it cools down to be molded, and then the molds 101 and 102 are opened to take out the molded product. This is a very efficient molding method for hollow products such as plastic bottles.

As described above, a method is generally known in which a resin molded product is obtained by cutting at a predetermined position on the side opposite to the air injection side during blow molding after blow molding.

(Problems to be Solved by the Invention) However, in the conventional method of forming a cylindrical body, due to the nature of the forming method, it is difficult to stably obtain the inner diameter dimension of both end openings of the molded product, and Since the blowing side must be cut, there is a problem in that molding material is lost.

Furthermore, when using a plurality of molds 101 and 102,
When the molds are clamped, a mold parting line appears at opposing positions on the outer periphery of the molds 101 and 102, which poses a problem in terms of product finish.

The present invention has been made in view of the problems of the prior art described above, and its purpose is to facilitate the manufacture of resin products and provide a method for molding cylindrical resin products with high precision. It's about doing.

(Means for Solving the Problems) The present invention having the above-mentioned object covers the outer periphery of a metal core with a heat-deformable resin cylindrical body, and heats the heat-deformable resin cylindrical body. The outer periphery of the core metal is brought into close contact with the outer periphery of the core metal, cooled and molded together with the core metal, and the metallic core metal is melted to obtain a resin molded product.

(Function) According to the present invention, a thermally deformable resin cylindrical body is placed over the outer periphery of a metal core having a low melting point, and the thermally deformable resin cylindrical body is brought into close contact with the core metal. The molded product was cooled to form a cylindrical body, and then the metal was melted to obtain a resin molded product, so the inner diameter of both end openings of the molded product could be stably obtained, and the opening on one side could be cut. This eliminates the loss of molding material.

(Example) The present invention will be described below based on the illustrated embodiment. In this embodiment, a bellows-shaped product will be described as an example of the resin cylindrical body. Referring to FIG. 1, a rod-shaped core support shaft 1
A core metal 2 is attached around the . The core metal 2 has a bellows-shaped outer circumference corresponding to the inner diameter of the bellows-shaped product. Further, the core bar 2 is made of a metal with a low melting point.

Next, a cylindrical body 3 made of a heat-deformable resin, particularly a heat-shrinkable resin that contracts when heated, as shown in FIG. 2, is prepared and placed over the outer periphery of the core metal 2.

In Fig. 3, a cylindrical body 3 made of heat-deformable resin.
heat up. This heating brings the cylindrical body 3 into close contact with the outer circumference of the core bar 2 so as to cover it.

At this time, since the outer periphery of the core metal 2 has a bellows shape as shown in the figure, the cylindrical body 3 is also formed in a bellows shape in close contact with the outer periphery of the core metal 2.

Thereafter, when the core metal 2 and the cylindrical body 3 are simultaneously cooled, the resin cylindrical body 3 is solidified and molded in accordance with the outer peripheral shape of the core metal 2.

Next, the core metal 2 and the cylindrical body 3 are placed together in an induction heating coil and heated. As described above, this core metal 2 is made of a metal with a low melting point, so it melts at a low temperature, leaving only the resin cylindrical body 3.

In this method, since the resin cylindrical body 3 is molded in close contact with the core metal 2, the inner diameter dimension of the openings at both ends of the molded product can be stably obtained, and there is no need to cut the opening on one side. , there is no loss of molding material, and good products can be obtained without leaving mold parting lines that are seen in blow molded products.

Next, FIG. 5 shows a second embodiment of the method for forming a cylindrical body of the present invention.

Components in this embodiment that have the same functions and functions as those in the first embodiment will be described with the same reference numerals.

Referring to FIG. 5, two core metals 2 are attached around a rod-shaped core metal support shaft 1. The two core metals 2 have a bellows-shaped outer circumference corresponding to the inner diameter of the bellows-shaped product. Further, the core bar 2 is made of a metal with a low melting point.

Next, two cylindrical bodies 3 made of a heat-deformable resin, in particular a heat-shrinkable resin that contracts when heated, are prepared.
They are arranged so as to cover the outer peripheries of the two core metals 2, respectively.

Next, the cylindrical body 3 made of heat-deformable resin is heated. By this heating, the outer circumferences of the two core metals 2 are brought into close contact so as to cover them.

At this time, since the respective outer peripheries of the two core metals 2 have a bellows shape as shown in the figure, the two cylindrical bodies 3 are also formed in a bellows shape in close contact with the outer peripheries of the core metal 2.

Thereafter, when each of the core metals 2 and the cylindrical body 3 are simultaneously cooled, the resin-made cylindrical body 3 is solidified and molded around the outer periphery of the core metal 2.

Next, the two core metals 2 and the two cylindrical bodies 3 are placed together in an induction heating coil and heated. As described above, this core metal 2 is made of a metal with a low melting point, so it melts at a low temperature, leaving only the resin cylindrical body 3.

In this embodiment, a case has been described in which two core metals 2 are used, but if three or more core metals 2 are used in series, a large number of resin molded products can be obtained.

Further, in this embodiment, the resin-made cylindrical body 3 is explained as an example in which it is divided into each core metal 2, but it is also possible to use a continuous one piece by piece.

Next, FIG. 6 shows a third embodiment of the present invention.

In this embodiment, a bottomed cylindrical component will be explained as an example of a resin product. Referring to FIG. 6, a core metal 2 is attached around a rod-shaped core metal support shaft l. The core metal 2 has a cylindrical shape in which the outer circumference corresponds to the inner diameter of the bottomed cylindrical part of the product. Further, the core bar 2 is made of a metal with a low melting point.

Next, a bottomed cylindrical body 3 made of a heat-deformable resin, in particular a heat-shrinkable resin that contracts when heated, is prepared, and the core metal 2 is
Place it over the outer periphery of the

Next, the bottomed cylindrical body 3 made of heat-deformable resin is heated. By this heating, the outer periphery of the core metal 2 is brought into close contact so as to cover it.

At this time, since the outer periphery of the core metal 2 has a bottomed cylindrical shape as shown in the figure, the bottomed cylindrical body 3 is also formed into a bottomed cylindrical shape in close contact with the outer periphery of the core metal 2.

Thereafter, when the core metal 2 and the bottomed cylindrical body 3 are simultaneously cooled, the bottomed cylindrical body 3 made of resin is solidified and molded.

Next, the core metal 2 and the cylindrical body 3 are placed together in an induction heating coil and heated. As described above, this core bar 2 is made of a metal with a low melting point, so it melts at a low temperature, leaving only the bottomed cylindrical body 3 made of resin.

In this way, by molding the molding material 2 and the cylindrical body 3 into various shapes in advance, a wide range of product shapes can be accommodated.

(Effects of the Invention) According to the present invention, it has the above-described structural effect, and in particular, since the resin cylindrical body is molded in close contact with the core metal, and then the metal core metal is melted, the resin It is possible to obtain both end openings having accurate inner diameter dimensions of the molded product. In addition, there is no need to cut the opening on one side of the resin molded product, which eliminates the loss of molding material, and eliminates the mold dividing line marks seen in conventional blow molded products, resulting in a good product. You can get the product.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view illustrating a first embodiment of the method for forming a cylindrical body of the present invention, FIG. 2 is a longitudinal sectional view illustrating the method of forming a cylindrical body of the present invention, and FIG. FIG. 4 is a vertical cross-sectional view of the resin molded product of the present invention, and FIG. 5 is a vertical cross-sectional view showing a second embodiment of the method for molding a cylindrical body of the present invention. , FIG. 6 is a longitudinal sectional view showing a third embodiment of the method for forming a cylindrical body of the present invention, and FIG. 7 is a longitudinal sectional view showing the forming method of the prior art. Explanation of symbols 1... Core metal support shaft 2... Core metal 3... Cylindrical body number! Drawing procedure amendment (Jichi Patent Application No. 329969, filed in 1988, method for forming a cylindrical body Representative Tsuru Masaden

Claims (2)

[Claims] (1) A heat-deformable resin cylindrical body is placed over the outer periphery of the metal core, and the heat-deformable resin cylindrical body is heated so as to tightly cover the outer periphery of the core. A method for molding a cylindrical body, characterized by cooling and molding with gold and melting a metal core to obtain a resin molded product. (2) The method for forming a cylindrical body according to claim 1, wherein the metallic core is made of a low melting point metal.