JPH1034732A - Extrusion molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extrude a homogeneous and excellent quality tube body without being affected by molding condition fluctuations in a mold and flow characteristics of a molten resin as in the conventional case. An extrusion method is provided. SOLUTION: Extrusion mold 1 is provided at the tip of a screw.
In the method for extruding a tubular body using an extruding apparatus equipped with, a temperature above and below the core 11 for shaping the tubular body on the tip side of the mold 1 is independently detected, Based on the detected temperature, the heating of the temperature above and below the core 11 and the temperature control thereof are independently performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for extruding a tubular body using a twin-screw extruder or the like.

[0002]

2. Description of the Related Art Conventionally, a mold used for extruding a tubular body made of a thermosetting resin by attaching a mold to a tip of a twin-screw extruder is provided with a core provided therein. A heater has been built into the core to preheat the core before the start of extrusion molding. As these extrusion moldings, those described in JP-A-6-91732 are known.

[0003]

However, in the extrusion of a tubular body using such a twin-screw extruder, particularly when the twin-screw is rotated in the opposite direction, the extruder may not be suitable due to its characteristics. The flow of the molten resin in the mold is easier to flow in the lower part than in the upper part, which causes uneven thickness,
There is a disadvantage that it is difficult to control the wall thickness uniformly.

Further, the fluidity is affected by the temperature of the molten resin,
Due to the change in the flow of the molten resin, a problem such as breaking of the standard of the product occurs. Furthermore, in the case of a tubular body made of a thermosetting resin that is extruded at a high temperature, heat is easily accumulated in the core portion, so-called B-UP is induced, and the quality of the product is lowered due to this. Problems remain. In recent years, customer demands for quality have become stronger,
Higher quality products are increasingly required.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to solve these problems and to reduce the molding conditions in a conventional mold. An object of the present invention is to provide an extrusion method capable of extruding a tube of uniform and excellent quality without being affected by fluctuation and flow characteristics of a molten resin.

[0006]

According to the extrusion molding method of the present invention, there is provided a method for extruding a tubular body using an extrusion molding apparatus comprising a die for extrusion molding attached to a tip of a screw. The upper and lower temperatures of the core forming the tubular body on the distal end side are independently detected, and based on the detected temperatures, heating of the upper and lower temperatures of the core and its temperature control are performed. It is characterized in that it is performed independently for each.

More specifically, independent heating oil is placed above and below the inside of the core of the parallel part on the tip side of the extrusion die for the tube attached to the tip of the screw. Along with forming a circulation path, one thermocouple is attached to each of the upper and lower cores of the parallel portion, and the flow rate of the oil is controlled based on the temperature detected by the thermocouple. It is intended to separately control the upper and lower temperatures of the core of the section.

[0008]

According to the extrusion molding method of the present invention, there is provided a method for extruding a tube using an extrusion molding apparatus in which an extruding die is attached to a tip of a screw. The upper and lower temperatures of the core to be shaped are independently detected, and based on the detected temperatures, the heating of the upper and lower temperatures of the core and the temperature control are independently performed. By doing so, the uneven flow generated above and below the flow of the molten resin in the mold is suppressed and uniform, and a thermosetting resin tube having uniform and excellent quality is extruded. Became possible.

Conventionally, the thickness of the molded pipe is adjusted by adjusting the width of the flow path of the molten resin by adjusting bolts provided on the mold. The surface smoothness has been adjusted by adjusting extrusion conditions, that is, adjusting the extrusion amount, controlling the temperature of the molten resin, and the like.

In the extrusion molding method of the present invention, the tip of the mold is parallelized without changing the extrusion conditions (adjustment of the extrusion amount by changing the temperature of the molten resin and the number of rotations of the screw). By simply controlling the core temperature of the section, it is possible to obtain a tube with uniform and excellent quality, to reduce management man-hours, and to improve product efficiency and mechanical efficiency. became.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of an extrusion molding device in the extrusion molding method of the present invention. The extrusion molding apparatus shown in FIG. 1 includes a mold 1 mounted at the tip of a twin-screw extruder (not shown), a heat exchanger 2, a heater 3, and a temperature controller connected to the mold 1 and used. 4.

An upper portion 11a of the core 11 on the distal end side for shaping a tube of the mold 1 constituted by the land 12 and the core 11.
And lower part 11b, thermocouples 5, 5 for detecting temperature
a is buried in each.

The upper and lower portions 11a and 11b of the core 11 are independently provided with piping 6 and 7 for heating oil, respectively. Supply pipe 6 through a passage provided through
a, 7a and return pipes 6b, 7b are connected to each other.

The supply pipes 6a and 7a are branched and connected to the heater 3 and the heat exchanger 2. The oil whose temperature is controlled by the temperature control device is heated to the upper part 11a and the lower part 11b of the core 11. Supplied, upper 11a and lower 1
1b can be independently heated.

The surface temperatures of the upper portion 11a and the lower portion 11b of the core 11 are constantly detected by thermocouples 5 and 5a, and the detected values are sent to a temperature control device 4, which controls the heaters 3 and The heating temperature of the oil is controlled using the heat exchanger 2, and the upper part 11a and the lower part 1 of the mold 1 are controlled.
1b, and the temperature of the molten resin flowing through the upper part 11a and the lower part b of the core 11 is adjusted.

Therefore, when the flow characteristics of the molten resin are different between the upper part 11a and the lower part 11b of the mold 1, for example, especially when the twin screw is rotated in the opposite direction, the characteristics of the extruder may cause a problem in the mold. The flow of the molten resin in the above becomes easier to flow in the lower part than in the upper part. However, by lowering the temperature of the lower part 11b of the core 11 from that of the upper part 11a, the temperature of the molten resin flowing below is lowered, and It is possible to balance properties and perform uniform extrusion.

Therefore, in the extrusion molding method of the present invention,
Automatically controls the core temperature at the upper and lower parts of the parallel part at the tip of the mold without changing the extrusion conditions as in the past (adjusting the extrusion amount by changing the temperature of the molten resin and the number of screw revolutions). By doing so, it is possible to obtain a tube having uniform and excellent quality.

[0018]

According to the extrusion molding method of the present invention, there is provided a method for extruding a tubular body using an extrusion molding apparatus in which an extrusion molding die is attached to a tip of a screw. The temperature above and below the core forming the tube is detected independently of each other, and based on the detected temperature, the heating of the temperature above and below the core and its temperature control are independently performed. Extrusion of a thermosetting resin tube with uniform and excellent quality is suppressed by suppressing the drift generated above and below the flow of the molten resin in the mold. It became possible to do.

Conventionally, the thickness deviation of the formed tube is adjusted by adjusting the width of the flow path of the molten resin by adjusting bolts provided on the mold. The surface smoothness has been adjusted by adjusting the extrusion conditions, that is, adjusting the extrusion amount and controlling the temperature of the molten resin. However, in the extrusion molding method of the present invention, such a change in the extrusion conditions (the molten resin Adjusting the extrusion rate by changing the temperature and the screw rotation speed), and automatically controlling the core temperature of the parallel part at the tip of the mold without obtaining a homogeneous and excellent quality tube. It has become possible to reduce management man-hours and improve product efficiency and mechanical efficiency. Therefore, it is suitably used as a method for extrusion molding.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an example of an extrusion molding apparatus in an extrusion molding method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die 11 Core 12 Land 11a Upper part 11b Lower part 2 Heat exchanger 3 Heater 4 Temperature control device 5 Thermocouple 6, 7 Piping 6a, 7a Supply pipe 6b, 7b Return pipe

Claims (1)

[Claims] 1. A method for extruding a tube using an extruder in which a die for extrusion molding is attached to a tip of a screw, the method comprising: Extrusion molding characterized by independently detecting the temperature of the core and the temperature of the lower part, and heating and controlling the temperature of the core above and below the core independently based on the detected temperature. Method.