JPS59131432A - Molding method of pipe having different diameters - Google Patents

Abstract

PURPOSE:To make it possible to easily mold a titled pipe, by extruding a polymer compound from an extrusion gap while changing the opening direction of the extrusion gap by moving the die position of a pipe extruder to the axial direction of a mandrel. CONSTITUTION:When a hydraulic cylinder is provided so as to move a die to the axial direction thereof and the die is retracted from the leading end surface of a mandrel to extrude a polymer compound from the formed extrusion gap, the polymer compound is extruded to said direction because the extrusion gap is opened toward an obliquely outward direction to mold a large diameter part P1. Subsequently, if the die 6 is advanced to the position where flushed with the leading end surface of the mandrel 5 and the polymer compound is succeedingly extruded, a small diameter part P2 is continuously molded, and if the die 6 is further retracted to extrude the polymer compound, a large diameter part P3 is continuously molded. Thus extruded and molded pipe is cut to a proper length and vulcanized to obtain a desired pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides the following features: This invention relates to a method for forming pipes of different diameters from a polymer blend containing navy blue dispersed therein.

Conventionally, to mold pipes with different diameters, the molding material is heated and melted in the injection cylinder of an injection molding machine, and then the fluidized molding material is injected into a mold cavity that is tightly closed in advance by an injection plunger. So-called injection molding is carried out in which the material is injected, completely filled, and then cooled and solidified or hardened to form a molded product.

However, in this method, the structure of the inner mold becomes complicated, which is not only cumbersome and expensive, but also the inner mold is made by reducing the diameter of the split cone 7 during die cutting. This mold structure could not be used for pipes with a small f ¥.

In addition, to form tubes with different diameters, heat-melted thermoretroactive plastic material is made into a cylindrical tube by extrusion or injection molding, and then air is blown into the tube in a blow molding mold to form hollow containers. A method of molding is known.

However, even with this method, it is difficult to reliably obtain a desired R-diameter tube, and the number of steps is complicated, making it difficult to simply and continuously form desired different-diameter tubes.

The present invention was made to solve the above-mentioned problems, and includes a method of extruding a polymer compound containing dispersed short fibers using a pipe extruder, orienting the short fibers, and forming an internally reinforced pipe. A pipe with different diameters, characterized in that the position of a die of a pipe extruder is moved in the axial direction of a mandrel to change the opening direction of an extrusion gap, and a polymer compound is extruded from the extrusion gap to form a pipe with different diameters. Regarding the molding method,
As described above, by extruding the polymer compound while changing the opening direction of the extrusion gap, it is possible to easily mold a desired different diameter tube.

Hereinafter, the present invention will be explained with reference to the drawings. Fig. 1 shows extrusion molding of a straight pipe in the normal state of the pipe extruder,
2 to 5 show extrusion molding of different diameter tubes with the die moved in the axial direction, and the embodiments of each extrusion molding are as follows.

First, referring to Fig. 1, 1 is a screw, 2 is a cylinder, 3 is a head, 4 is a breaker, 5 is a mandrel, 6 is a die, 7 is a die holder, and 8 is a hydraulic cylinder rod connected to the die 6. , the die 6 is moved in the diametrical direction via the rod 8 by the operation of a hydraulic cylinder (not shown),
The extrusion gap between the mandrel 5 and the die 6 is changed.

This pipe extruder is used to extrude straight pipes and pipes of different diameters. When extruding straight pipes, the tip surfaces of the mandrel 5 and the die 6 are aligned flush as shown in Figure 1, and their central axes are aligned. The extrusion gaps between the two are set to be equal. At this time, the extrusion gap has a thickness in the entire circumferential direction from the upper gap a to the lower gap. When the polymer compound M is extruded in this state, a straight pipe P having a diameter and wall thickness corresponding to the extrusion fill gap is formed.

When extruding pipes of different diameters, a hydraulic cylinder (not shown) is provided to move the die 6 shown in Fig. 1 in the axial direction (left and right in Fig. 1), and the die 6 is moved as shown in Fig. 2. It is moved backward from the tip end surface of the mandrel 5 or advanced from the tip end surface of the mandrel 5 as shown in FIG.

When the polymer compound is extruded from the extrusion gap with the die 6 retracted from the mandrel 5 as shown in FIG.
Since the gap is diagonally outward, the I remer compound is extruded in that direction, forming the large diameter portion P1 as shown in FIG.

Then, the die 6 is advanced to a position flush with the mandrel 5 as shown in FIG. 1, and the polymer blend is continuously extruded.
The small diameter portion P2 shown in the figure is continuously molded, and the die 6 is again inserted into the second die.
If the polymer compound is extruded by retreating to the state shown in the figure, the large diameter portion P3 in FIG. 3 will be continuously molded.

When the polymer compound is extruded with the die 6 extending beyond the mandrel 5 as shown in FIG. is formed, and then the die 6 is retracted flush with the mandrel 5 as shown in FIG. 1 to extrude the polymer blend.
After the large diameter portion P5 shown in the figure is molded, the die 6 is advanced again to the state shown in FIG. 4 to extrude the polymer compound, thereby continuously molding the small diameter portion P6 shown in FIG.

The tube of different diameters extruded as described above is cut into appropriate lengths and vulcanized to obtain the desired tubes of different diameters. The aforementioned polymer compound has short fibers dispersed in it, and has a structure in which the gap between the die and the mandrel gradually widens from the inlet to the discharge section.If the gap narrows by not moving the die, the flow in that area will decrease. Because it is relatively slow, when this is molded, the proportion of short fibers oriented in the circumferential direction is higher in the small extrusion gap than in the large gap, so it is actually 25% smaller than the standard thickness. It has been experimentally shown that the bursting strength of the thinner part is equivalent to that of the standard thickness part. Therefore, this different diameter tube has greater strength and better appearance than different diameter tubes made by conventional manufacturing methods.

When forming pipes with different diameters as described above, the extruded product extruded from the extrusion gap between the mandrel and die to have different diameters maintains its different diameter shape until vulcanization due to its own raw strength. Since the shape is fixed by vulcanization, it is possible to reliably obtain the desired different diameter tube.

As described above, the present invention allows pipes of different diameters to be easily formed by moving the relative positions of the mandrel and die of the pipe extruder, changing the extrusion gap, and extruding the polymer compound from the extrusion gap. This is an economically advantageous invention that saves labor and time compared to conventional methods, and is of great practical benefit.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIG. 1 is a longitudinal cross-sectional view showing a vibrator extruder in a normal state, and FIGS. FIG. 1 is a longitudinal cross-sectional view of the pipe in an extruded state as shown in FIGS. 2 and 4 (G, which does not show flat molding), and a perspective view of a pipe of different diameters that has been flat molded. 1 is the screw, 2 is the cylinder, 3 is the head, 4 is the breaker, 5 is the mandrel, 6 is the die, 7 is the die presser, and 8 is the hydraulic cylinder rond. Formula) % Formula % 1. Indication of the case Patent Application No. 152854 of 1982 2. Name of the invention Method for forming different diameter pipes 3. Person making the amendment Relationship with the case Patent applicant Meiji Rubber & Chemicals Co., Ltd. 4, Agent 9-16-chome, Kajicho-chome, Chiyoguchi 1-ku, Tokyo 5, date of the amendment order, I91, January 31, 1980, 6, full text of the specification subject to the amendment 7, contents of the amendment

Claims (1)

[Claims] 1. In a method of extruding a polymer compound containing dispersed short fibers using a pipe extruder and orienting the short fibers to form an internally reinforced tube, the position of the die of the vibrator extruder is moved in the axial direction of the mandrel. 1. A method for forming pipes with different diameters, the method comprising: changing the opening direction of an extrusion gap, and extruding a polymer compound from the extrusion gap to form a pipe with different diameters.