JPS5926455B2 - Method for manufacturing a resin pipe having an annular hollow part in the pipe wall - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a resin tube having an annular hollow portion in the tube wall.

In a resin pipe made of a thermoplastic resin such as vinyl chloride resin, a hollow part is provided in the pipe wall to create a double pipe structure as described in Japanese Utility Model Publication No. 38-11145, for example, in order to reduce weight, improve heat insulation, or improve strength. Sometimes.

The resin pipe described in the above publication has a connecting wall that connects the inner and outer walls along the pipe axis, so it is relatively easy to manufacture by extrusion molding. Since it is continuous in the pipe axis direction and communicates with both pipe end faces, the conventional general connection method is to expand the diameter of one end and use it as a pipe socket, and insert the non-diameter end of another pipe into this. The method of connecting the pipes by means of a pipe is disadvantageous because fluid leaks inside or outside from the hollow part of the pipe wall.

j In view of the above points, the present invention has been made for the purpose of partitioning the hollow part of the tube wall by providing connecting walls in the circumferential direction at appropriate intervals instead of providing connecting walls in the tube axis direction. The gist is that a resin tube with a heavy pipe structure is continuously extruded from a mold attached to an extruder; guidance,
A pipe pipe characterized in that the inner and outer walls of the resin pipe are thickened and fused together by intermittently slowing down or stopping the take-up speed of the resin pipe in the annular space.
The present invention resides in a method of manufacturing a resin pipe having an annular hollow portion in the wall. Next, the present invention will be described with reference to embodiments of the drawings.

FIG. 1 schematically shows the method of this invention, in which molten resin is continuously supplied from an extruder 1 and is discharged through a mold 2 into a double tube shape having inner and outer walls. The resin tube 5 is guided to regulate the inner and outer diameters, and is then further cooled and solidified in the cooling tank 4 to obtain the resin tube 5.

Reference numeral 6 denotes a take-off device for the resin pipe 5, the take-off speed of which can be varied or temporarily stopped, and is operated to intermittently slow down or stop during extrusion molding of the resin pipe 5.

7 is a device for cutting the resin pipe 5;

An annular auxiliary mold 225 is provided concentrically in the annular resin passage 21 of the mold 2, and the molten resin is divided into two into an inner wall and an outer wall by the auxiliary mold 22, and is discharged from the mold 2 in a double tube shape. is being done.

23 is a through hole that penetrates the auxiliary mold 22 from the outer surface of the mold 2 and communicates with the space 33 for regulating the diameter of the diameter regulating mold 3. Air can be exhausted from this through hole 23 or Pressurized fluid may be delivered. The diameter regulating mold 3 consists of an outer diameter regulating mold 31 and an inner diameter regulating mold 32, and an annular space 33 for diameter regulating is formed between them. The outer diameter regulating type 31 and the inner diameter regulating type 32 each have a cooling jacket 311.
, 321 are provided to cool the resin pipe 5, and exhaust pipes 312, 322 are provided that open to the inner circumferential surface of the outer diameter regulating mold 31 and the outer circumferential surface of the inner diameter regulating mold 32. The circumferential surfaces of the control walls 31 and 32 are in close contact with the circumferential surfaces of the regulating walls 31 and 32. The resin pipe 5 is normally cooled and regulated in the annular space 33 of the diameter regulating mold 3 in a double pipe state discharged from the mold 2.

However, if the take-off speed is intermittently lowered or stopped than the normal take-off speed, the molten resin supplied from the extruder 1 remains substantially constant, and the amount of resin discharged from the mold 2 does not change. Since the take-up speed of the resin pipe 5 is temporarily reduced or stopped, the annular space 33 of the diameter regulating type 3
In this process, the inner and outer walls of the resin tube 5 become thicker, come into contact with each other, and are fused together. At this time, the pressure may be reduced by evacuating through the through hole 23 of the mold 2. When the take-off device 6 returns to its original normal take-up speed, the inner and outer walls of the resin tube 5 are separated to form a double pipe structure. By intermittently slowing down or stopping the take-up speed of the resin pipe 5, the resin pipe 5, in which the pipe wall has a solid portion, is continuously connected in the circumferential direction by connecting the inner and outer walls at corresponding intervals. extrusion molded. As described above, the present invention involves intermittently slowing down or stopping the take-up speed of a resin pipe extruded into a double-tubular shape by extrusion molding, thereby thickening the inner and outer walls of the resin pipe at the inner and outer diameter regulating mold parts, and thereby allowing the inner and outer walls of the resin pipe to overlap each other. Since the resin tube is fused, it is easy to obtain a resin tube in which the space in the tube wall is partitioned by the fused portion at appropriate intervals in the tube axis direction, and the inner and outer walls are connected and supported at this portion. The pipe does not leak water through the space in the pipe wall, and is suitable for use as a buried pipe such as a drain pipe.

[Brief explanation of the drawing]

FIG. 1 is an embodiment of the method of the present invention, and FIG. 2 is an enlarged longitudinal sectional view of the main part of FIG. 1. DESCRIPTION OF SYMBOLS 1... Extruder, 2... Mold, 31... Outer diameter regulation type, 32... Inner diameter regulation type, 6... Taking-off device.

Claims (1)

[Claims] 1. A resin tube with a double tube structure is continuously extruded from a mold attached to an extruder and introduced into an annular space between an outer diameter regulating mold and an inner diameter regulating mold provided at the outlet of the mold, and A resin having an annular hollow part in the pipe wall, characterized in that the inner and outer walls of the resin pipe are thickened and fused together by intermittently slowing down or stopping the take-up speed of the resin pipe in the annular space. Method of manufacturing tubes.