JPS5830131B2 - Thermoplastic resin pipe manufacturing method and manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method and apparatus for manufacturing a thermoplastic resin tube that is lightweight, strong, and has excellent flexibility.

Conventionally, thermoplastic resin conduits used for applications such as cable protection piping have generally had a bellows structure with an axially symmetrical or spiral waveform on a uniform-walled tube, as shown in Figure 1. .

This structure has the advantage of being strong against lateral pressure without impairing its flexibility, but there is a limit to the ability to achieve both flexibility and crush resistance, and if flexibility is emphasized, the resin pipe may be damaged by unexpected external forces. There was a drawback that it could lead to accidents such as water intrusion into the pipes.

In order to overcome the drawbacks of the conventional structure, a thermoplastic resin tube as shown in FIG. 2 or 3 has been proposed as a new structure for resin tubes.

This new structure of thermoplastic resin pipe has the following features.

That is, the structure shown in FIG. 2 sacrifices flexibility slightly compared to the conventional structure, but the crush resistance can be greatly increased without increasing the friction when the internal cable is drawn in.

Furthermore, the structure shown in FIG. 3 does not impair flexibility or friction when pulling in the cable, and can increase crush resistance compared to the conventional structure.

The structure shown in FIGS. 2 and 3 has the advantage that the resin tube stretches less in response to an axial force than the conventional structure.

The present invention relates to a method and apparatus for manufacturing thermoplastic resin pipes having a new structure, and is based on a novel idea.

FIG. 4 is a schematic diagram for explaining an embodiment of the method for manufacturing a thermoplastic resin pipe of the present invention.

A fixed die 1 and a rotating die 5 arranged concentrically inside the fixed die 1
A thermoplastic resin pipe 3 and a spiral string 6 are simultaneously extruded from each tube and guided to a sizing device.

The sizing device consists of a cylindrical sizing die 4 with exhaust holes 7 on the inner wall and an exhaust device connected to the exhaust holes, and includes a thermoplastic resin pipe and a spiral string led into the sizing die. are welded and integrated by the heat of extrusion, and the outer diameter of the pipe is molded to match the inner diameter of the sizing die.

Thereafter, the resin tube is cooled and solidified in a cooling device, and as shown in FIG. By inhaling the water through the gap with the inner wall and draining it through the exhaust pores 7, cooling efficiency is increased.
Enables high-speed extrusion molding of uniform resin pipes.

Furthermore, as shown in FIG.
, a heating device 14 and a cooling device 1 are installed behind the cooling device 12.
In step 5, the extruded, sized, cooled, and molded thermoplastic resin tube into the structure shown in Figure 2 is heated and softened again.
By subsequent cooling, a structure as shown in FIG. 3 can be obtained by utilizing the fact that the amount of contraction due to internal stress differs depending on the heat capacity difference between the thick and thin parts of the pipe.

Further, an embodiment of the manufacturing apparatus of the present invention is shown in FIG.

The details of the extrusion device 10 are as shown in FIG. 4. A rotary die 5 is provided concentrically inside a fixed die 1 and a nipple 2. A thermoplastic resin pipe is passed from the fixed die, and a thermoplastic resin pipe is disposed from the rotating die. The strings are extruded simultaneously in a spiral shape.

A sizing device 11 is provided next to the extrusion device, the details of which are shown in FIG. 4, in which exhaust holes 1 are provided in the inner wall of the sizing die 4, and the exhaust holes are connected to the exhaust device. .

A first cooling device 12 is provided after the sizing device, but it can be a hot water or cold water tank and placed at a distance from the sizing device; Cooling efficiency can also be improved by absorbing water from the water tank through the gap between the outer surface of the resin tube and the inner wall of the sizing die and draining it through the exhaust holes provided in the inner wall of the sizing die.

After the first cooling device, a feeding device 13, a heating device 14 for reheating, a second cooling device 15, and a winding device 16 are sequentially provided to form protrusions on the inner wall as detailed in the explanation of the manufacturing method. The most suitable apparatus for manufacturing thermoplastic resin pipes is provided.

It should be noted that the thermoplastic resin tube shown in FIG. 2 or 3 has the advantage that it can be manufactured using the same apparatus.

[Brief explanation of the drawing]

Figure 1 is a structural diagram of a conventional thermoplastic resin pipe, Figures 2 and 3
The figure is a structural diagram of the newly proposed thermoplastic resin pipe, and Figure 4 is a schematic diagram of the extrusion device, sizing device, and cooling device of the present invention, where 1 is a fixed gouer, 2 is a nipple, and 3 is a thermoplastic resin pipe. , 4 is a sizing die, 5 is a rotating die, 6 is a spiral string 7 is an exhaust hole, 8 is a water tank, and 9 is a cooling water. FIG. 5 shows an embodiment of the manufacturing device of the present invention, and 10 is an extrusion device;
11 is a sizing device, 12 is a first cooling device, 13 is a feeding device, 14 is a heating device, 15 is a second cooling device, and 16 is a winding device.

Claims (1)

[Claims] 1. A pipe made of thermoplastic resin and a spiral string are simultaneously extruded from a fixed die and a rotating die arranged concentrically inside the fixed die, and guided to a sizing device and a cooling water tank to cool the pipe. The spiral string is integrally welded to the inner wall, and the resin tube is cooled and solidified. Thereafter, the resin pipe with the pipe and the spiral string integrated is heated and softened in a heating device, and then cooled and solidified again in a cooling device to obtain the resin pipe. A method for producing a thermoplastic resin pipe, which comprises reducing the diameter of the unwelded part of the pipe using a shrinkage force. 2. An extrusion device equipped with a fixed gou for extruding a pipe made of thermoplastic resin, a rotary die inside thereof for extruding a string made of thermoplastic resin in a spiral shape, and the extruded pipe and the spiral shape. A sizing device that integrally welds and molds strings, a first cooling device that cools the molded thermoplastic resin tube, a feeding device that runs the resin tube, and a heating softener that heats and softens the resin tube after being cooled and solidified. A heating device, a second cooling device for re-cooling and solidifying, and a winding device for winding the completed resin pipe are sequentially provided, and the sizing device and the cooling water tank as the first cooling device are connected,
1. A thermoplastic resin pipe manufacturing device characterized in that the water in the cooling water tank is configured to flow along the inner wall of a sizing die.