JP2001150517A - Method of manufacturing for thermoplastic resin pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing for a thermoplastic resin pipe capable of enhancing the cooling efficiency of the parison extruded from an extrusion mold and capable of increasing extrusion quantity. SOLUTION: In a method of manufacturing for a thermoplastic resin pipe by kneading and melting a thermoplastic resin from an extruder to extrude the same from an extrusion mold 1 to form a parison P and molding the parison P while advancing the same through a water tank 2 having a sizing tube 3 provided to its inlet, a mold having a hole 12, which communicates with the interior of the parison P from the outside, provided thereto and having the cooling tube 4 inserted in the hole 12 is used as the extrusion mold 1 to allow air K to flow through the cooling tube 4 to cool the inner surface of the parison P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a thermoplastic resin tube extruded from an extrusion die and having excellent cooling efficiency.

[0002]

2. Description of the Related Art The extrusion molding process of a thermoplastic resin tube can be divided into an extrusion process, a cooling shaping process, a take-up process, a printing process, and a cutting process. It was common to only spray or spray the parison from outside. However, in the case of a thick-walled resin pipe or a foamed resin pipe or the like, since heat insulation is large, cooling or spraying only by water spraying or spraying from the outside becomes insufficient. The solution can be solved by increasing the length of the cooling bath, but this solution is limited because it must be manufactured in a limited factory space. In addition, there is a problem that since the cooling tends to be insufficient, the extrusion amount cannot be increased, and the production efficiency decreases.

[0003] For example, Japanese Patent Application Laid-Open No. 8-66963 discloses that a cooling mandrel is mounted on the tip of a mold and gradually cooled while maintaining a constant diameter with the cooling mandrel, so that the heat expansion property is improved. There has been proposed a method of manufacturing a tube having a slab.

However, this method has a special purpose of using the manufactured pipe for lining a steel pipe, the equipment cost of the cooling mandrel and the internal medium temperature controller is high, and the parison with the cooling mandrel is required. It is difficult to increase the extrusion speed due to the large contact area of the tube, and it is difficult to adopt this method as a general pipe manufacturing method.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems and has a high cooling efficiency for a parison extruded from an extrusion die, and can increase the throughput of a thermoplastic resin tube. The purpose of the present invention is to provide a manufacturing method.

[0006]

The invention according to claim 1 of the present application (Invention 1) is a method in which a thermoplastic resin is kneaded with an extruder.
A method for manufacturing a thermoplastic resin tube in which a parison melted and extruded from an extrusion mold is formed into a tubular shape while being advanced in a water tank provided with a sizing tube at an inlet, and the parison is externally used as the extrusion mold. A method of manufacturing a thermoplastic resin tube that cools the inner surface of a parison by allowing a gas to flow through the cooling tube by using a cooling tube inserted through the hole, provided with a hole communicating with the inside. is there.

The invention described in claim 2 of the present application (the present invention 2)
A blind disk projecting inward from the parison and having an outer peripheral surface abutting against the inner surface of the parison is provided at a substantially center of the outlet side surface of the extrusion die via a supporting member, and the cooling tube is provided with a blind disk. A method for manufacturing a thermoplastic resin tube according to the first aspect of the present invention, wherein an end portion of the thermoplastic resin tube is penetrated through the blind disk and led out inside a parison.

In the present invention, the thermoplastic resin includes:
For example, hard polyvinyl chloride, polyethylene, polypropylene and the like can be mentioned. In the present invention, the material for the cooling tube is not particularly limited as long as it can withstand the temperature of the extrusion mold. For example, in addition to metal tubes such as steel tubes and stainless steel tubes, nylon tubes and tetrafluoroethylene tubes and the like Can also be used.

In the present invention, the flow rate and direction of the cooling gas are appropriately changed depending on the size of the extrusion die, the material and the diameter of the cooling tube to be used, the diameter of the thermoplastic resin pipe to be manufactured, and the like. As a tendency, in the production of small-diameter thermoplastic resin pipes, it is preferable to flow gas through a cooling tube so as to be sucked into the extrusion die side, and in the production of large-diameter thermoplastic resin pipes, It is preferable to allow the gas to flow through the cooling tube so as to flow out from the mold side.

In the production of a small-diameter thermoplastic resin tube, flowing gas through a cooling tube so as to be sucked toward the extrusion die is opposite to the direction in which the parison flows and the direction in which the gas flows. Although the cooling efficiency of the inner surface of the parison is high, in the production of a large-diameter thermoplastic resin tube, even when sucked from the extrusion die side, the flow rate is small and the cooling efficiency becomes small. It is better to let the gas flow through the cooling tube so that it flows out. The larger the gas flow rate is, the higher the cooling efficiency is. However, if the gas flow rate is too large, the parison is deformed and adversely affects the shaping. Therefore, the gas flow rate is appropriately changed in consideration of this point.

In the second aspect of the present invention, the blind disk is preferably made of metal since it comes into contact with the inner surface of the extruded thermoplastic resin tube. Good.

[0012]

The method of manufacturing a thermoplastic resin tube according to the first aspect of the present invention uses the extrusion die provided with a hole communicating with the inside of the parison from the outside and a cooling tube inserted through the hole. Since the inner surface of the parison is cooled by flowing gas through the cooling tube, the parison extruded from the extrusion die can be cooled from the inside and outside, so that the cooling efficiency is high and the throughput can be increased.

The method for producing a thermoplastic resin tube according to the second aspect of the present invention comprises:
At a substantially center of an outlet side surface of the extrusion die, a blind disk projecting inward of the parison and having an outer peripheral surface abutting against an inner surface of the parison is provided via a support member, and an end of the cooling tube is provided. Penetrates through the blind disk and is led out inside the parison, so that the air inside the parison is blocked by the blind disk and does not directly contact the extrusion mold,
Does not adversely affect parison extrusion.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram illustrating an example of a method for manufacturing a thermoplastic resin tube of the present invention. First, a manufacturing apparatus used in the present invention will be described. In FIG. 1, 1 is an extrusion die attached to an extruder (not shown), 2 is a water tank, and 3 is a sizing tube.

In the water tank 2, cooling water supplied from a tank provided with a cooling means (not shown) is jetted from a plurality of nozzles 21, 21... The waste water is returned to the tank via a drain pipe (not shown), and cooling water whose temperature is controlled is circulated within a certain temperature range. A sizing tube 3 is provided at the entrance of the water tank 2. The inner diameter of the sizing tube 3 is set so as to substantially regulate the outer diameter of the thermoplastic resin tube to be manufactured.

The extrusion die 1 is provided with a resin flow path 11 having a ring-shaped outlet side through which a molten resin supplied from an extruder flows. A hole 12 is provided which communicates with the exit end face surrounded by the road 11. The cooling tube 4 is inserted into the hole 12, one end of which projects from the upper surface of the central portion through the hole 12, and the other end projects from the outlet end surface. Therefore, the opening at the other end of the cooling tube 4 is open inside the parison P extruded from the extrusion die 1. An air compressor (not shown) is connected to one end of the cooling tube 4 protruding above the center of the extrusion die 1, and the cooling tube 4 is moved so that air K flows out of the extrusion die 1. After that, it is sent to the inside of the parison P.

Next, an example of a method for manufacturing a thermoplastic resin pipe of the present invention using the above-described manufacturing apparatus will be described with reference to FIG. A parison P extruded from an annular resin flow path 11 of the extrusion die 1 is kneaded and melted by an extruder (not shown), and the parison P is moved along a traveling direction in a water tank 2 provided with a sizing tube 3 at an inlet. The cooling water is injected from a plurality of nozzles 21, 21... Arranged in a row, and the cooling water is advanced while being cooled to form a large-diameter thermoplastic resin pipe.

At this time, the air K is sent to the cooling tube 4 so as to flow out from the extrusion die 1 side. The gas K is sent from the other end of the cooling tube 4 into the parison 5 extruded from the extrusion die 1. The inner surface of the parison P is cooled by the flow of the air K.

FIG. 2 is an explanatory view for explaining another example of the method for producing a thermoplastic resin tube of the present invention. First, a manufacturing apparatus used in the present invention will be described. This manufacturing equipment
At the substantially center of the exit side surface of the extrusion die 1, a blind disk 6 projecting inside the parison 5 and having an outer peripheral surface abutting against the inner surface of the parison 5 is provided via a support member 7. The other end passes through the blind disk 6 and is led out inside the parison 5.

In this manufacturing apparatus, a gas suction device (not shown) is connected to one end of the cooling tube 4 protruding above the center of the extrusion die 1, and the air K is supplied to the extrusion die 1.
The air is sucked through the cooling tube 4 to the side, and the flow of the air K cools the inner surface of the parison P extruded from the extrusion die 1. Otherwise, it is the same as the manufacturing apparatus described with reference to FIG.

Next, another example of the method of manufacturing a thermoplastic resin pipe of the present invention using the above-described manufacturing apparatus will be described with reference to FIG. A parison P extruded from an annular resin flow path 11 of the extrusion die 1 is kneaded and melted by an extruder (not shown), and the parison P is moved along a traveling direction in a water tank 2 provided with a sizing tube 3 at an inlet. The cooling water is injected from a plurality of nozzles 21, 21... Arranged in a row and cooled and formed to form a small-diameter thermoplastic resin tube. In the method of manufacturing a thermoplastic resin tube of this example, the parison P extruded from the annular resin flow path 11 of the extrusion die 1 is outside the blind disk 6 provided from the extrusion die 1 via the support member 6. It proceeds as sliding on the periphery.

The air K is caused to flow through the cooling tube 4 so as to be sucked into the extrusion die 1. Gas K is blind disk 5
Is sucked from the inside of the parison P after passing through the portion. The inner surface of the parison P is cooled by the flow of the air K. At this time, the air to be sucked is blocked by the blind disk 5 and does not directly contact the extrusion die 1, so that there is no adverse effect on the extrusion of the parison.

FIG. 3 is an explanatory view for explaining another example of the method for producing a thermoplastic resin tube of the present invention. First, a manufacturing apparatus used in the present invention will be described. This manufacturing equipment
At a substantially center of the outlet side surface of the extrusion die 1, a blind disk 5 projecting inside the parison P and having an outer peripheral surface abutting against the inner surface of the parison P is provided via a support member 6. The end penetrates the blind disk 6 and is led out inside the parison P. Further, a perforated disk 7 is provided on a side opposite to the extrusion die 1 of the blind disk 6 via a perforated support cylinder 8.

An air compressor (not shown) is connected to one end of the cooling tube 4 protruding above the center of the extrusion die 1, and is used for cooling so that air K flows out of the extrusion die 1. It is sent to the tube 4 and sent inside the parison P extruded from the extrusion die 1.

Next, an example of a method for manufacturing a thermoplastic resin pipe of the present invention using the above-described manufacturing apparatus will be described with reference to FIG. A parison P extruded from an annular resin flow path 11 of the extrusion die 1 is kneaded and melted by an extruder (not shown), and the parison P is moved along a traveling direction in a water tank 2 provided with a sizing tube 3 at an inlet. The cooling water is injected from a plurality of nozzles 21, 21... Arranged in a row, and the cooling water is advanced while being cooled to form a large-diameter thermoplastic resin pipe.

At this time, the air K is sent to the cooling tube 4 so as to flow out from the extrusion die 1 side. The gas K is sent from the other end of the cooling tube 4 to the inside of the parison 5 extruded from the extrusion die 1 and strikes the perforated disk 7 to form a turbulent flow. The turbulent air K cools the inner surface of the parison 5 with high cooling efficiency. The air K flows downstream through the holes of the perforated disk 7. Further, since the air K is not blocked by the blind disk 5 and does not directly contact the extrusion die 1, there is no adverse effect on the extrusion of the parison P.

[0027]

The method for producing a thermoplastic resin tube of the present invention comprises:
With the configuration as described above, the parison extruded from the extrusion die has a high cooling efficiency, and the extrusion amount can be increased.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a method for manufacturing a thermoplastic resin tube of the present invention.

FIGS. 2A and 2B are explanatory views illustrating another example of the method for producing a thermoplastic resin tube of the present invention, wherein FIG. 2A is a cross-sectional view thereof, and FIG. 2B is a cross-sectional view taken along line AA of FIG. It is.

FIG. 3 is an explanatory view for explaining still another example of the method for producing a thermoplastic resin tube of the present invention, wherein FIG.
(B) is a cross-sectional view along the line BB in (a).

[Explanation of symbols]

 P Parison K Gas 1 Extrusion mold 2 Cooling water tank 3 Sizing tube 4 Cooling tube 5 Blind disk 6 Support member 7 Perforated disk 8 Perforated support cylinder 11 Resin flow path 12 holes

Claims (2)

[Claims] 1. Production of a thermoplastic resin tube in which a parison kneaded and melted by an extruder and extruded from an extrusion die is formed into a tubular shape while being advanced in a water tank provided with a sizing tube at an inlet. A method in which a hole communicating with the inside of the parison from the outside is provided as the extrusion die, and a gas is circulated through the cooling tube by using a hole through which a cooling tube is inserted. A method for producing a thermoplastic resin tube, comprising cooling the inner surface of a parison. 2. A blind disk, which protrudes inward of the parison and whose outer peripheral surface is in contact with the inner surface of the parison, is provided substantially at the center of the outlet side surface of the extrusion die via a support member, and the cooling is provided. The method for producing a thermoplastic resin tube according to claim 1, wherein an end portion of the tube for use penetrates the blind disk and is led out inside the parison.