JPH10166085A - Method for extruding tube with groove on inner surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for extruding a tube with grooves on inner surface which is suitable for continuously extruding and which produces directly the tube having twisted grooves on the inner surface and without causing swells on the outer surface. SOLUTION: In this method for extruding a material from a port hole 6 between a mandrel 1 and a die 14, and forming an extruding tube 21, a flat surface tube 13 is formed between the mandrel 1 and the die 14, 15 smooth tube 13 is, the diameter of the top end side of the die 15 is reduced and the flat surface tube 13 is pressed onto a plug with grooves 16 installed freely rotatably on the top end of the mandrel 1 to form the twisted grooves on the inside face while the plug 16 is rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extruding an inner grooved tube, particularly a tube having an inner surface with a twist groove by extrusion.

[0002]

2. Description of the Related Art Recently, internally grooved tubes have been adopted as heat transfer tubes used in heat exchangers and the like in order to increase the heat transfer efficiency.

FIG. 2 shows a diagram in which a combination die is installed in an extruder to extrude an internally grooved tube having a twist groove.

[0004] The mandrel 1 of the extruder 10 is fixed, and a groove is formed on the outer periphery of the tip 1a.
After installing the billet 2 in the container 3,
Extrusion is performed with the stem 5. The material that is billet 2 is
After being divided at the port hole 6, it is press-bonded again in the chamber 7 and extruded as a tube 9 from the gap between the mandrel 1 and the die bearing portion 8. At this time, mandrel 1
The inner surface of the tube is pushed into the groove 1a at the end of the tube. When the extrusion is continued in this state, the portion pushed into the mandrel groove 1a becomes a resistance.

In particular, when the torsion angle α of the mandrel groove 1a is large, the tensile stress on the mandrel 1 increases, and the mandrel is broken. If the mandrel does not break, the groove on the inner surface of the pipe will be cut.

In order to avoid this phenomenon, an extruded material tensioning device 11 is provided in front of the extruder 10 so that the tensioning device 11 can be towed in accordance with the extrusion speed of the extruded material, and the extruded material can be drawn. The chuck 12 for gripping the tip can be rotated in accordance with the extrusion speed of the extruded material and the twist angle α of the inner surface groove. Since the torsion to the extruded material is applied to a portion that has not yet been cooled and hardened from the die, the extruded material does not break.

[0007]

However, the outer surface of the extruded tube manufactured by this extruder has undulation due to torsion. In order to remove the undulation on the outer surface, an empty space is required to reduce the outer diameter of the extruded tube. A pulling step is required, and it cannot be used for a continuous extrusion method in which an extruded material is wound.

Further, there is a method of avoiding torsion pulling out of the extruded tube by making a work so that only the mandrel tip groove portion (plug) of the combination die can be rotated. However, the strength of the plug holding mechanism is insufficient, and Cannot be realized because the deformation force of the plug makes the rotation of the plug difficult.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and to provide a method of extruding an inner grooved tube suitable for continuous extrusion and capable of directly producing a tube having a twist groove on the inner surface and no undulation on the outer surface. Is to do.

[0010]

In order to achieve the above object, the present invention is directed to an extrusion molding method for extruding a material from a port hole from between a mandrel and a die to form an extruded tube. A smooth tube is formed between the tubes, and the smooth tube is reduced in diameter with a diameter reducing die provided on the tip side of the die and pressed against a grooved plug rotatably provided at the tip of the mandrel while rotating the plug. This is an extrusion molding method for an inner grooved tube for forming a twist groove on the inner surface.

According to a second aspect of the present invention, there is provided an extrusion molding method for extruding a material from a porthole from between a mandrel and a die to form an extruded tube. A tube with a vertical groove on the inner surface is formed between the dies, and the tube is reduced in diameter with a contraction die provided on the tip side of the die and pressed against a grooved plug rotatably provided at the tip of the mandrel. This is a method of extruding an internally grooved tube in which a thread groove is formed on the inner surface while rotating the plug to form a cross groove.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

In FIG. 1, at the tip of a die holder 20, a dice 15 for a reduced tube having a reduced diameter portion 15a is accommodated, and a dice 14 for a smooth tube forming a chamber 7 of the extruded material is accommodated behind the dice 15 for a tube. , A tool 19 having a mandrel 1 at the center and a plurality of port holes 6 is accommodated therein.

At the end of the mandrel 1, a plug holding shaft 17 is provided so as to protrude from the contraction die 15, and a grooved plug 16 is rotatably provided on the shaft 17, and a threaded portion 17a of the shaft 17 is provided. Nuts 18 are screwed into the nut.

A groove 16a having a lead angle α is formed in the grooved plug 16.

Behind the die holder 20, a billet 2
Is provided, and the billet 2 is directly extruded by the push plate 4 and the stem 5.

Next, the extrusion molding method of the present invention will be described.

The billet 2 inserted into the container 3 is extruded by the stem 5 via the push plate 4. The material extruded by the stem 5 is divided through the port hole 6 and then pressure-welded again in the chamber 7, and first passes between the mandrel 1 and the die 14 for a smooth tube, and the smooth tube without a vertical groove on the inner surface. Before cooling and hardening, the smoothing tube 13 is reduced in diameter by the tube reducing die 15 and is pushed into the groove 16a of the grooved plug 16 to bite into the tube 21 having the twist groove 21a on the inner surface. Formed continuously.

At this time, the lead angle α of the plug 16
The plug 16 is rotated by receiving a component force, which is a rotational force, from the smooth tube 13.
Since no material deformation force acts on the inside, the pipe 21 having the torsion groove 21a on the inner surface can be continuously formed without breaking the plug holding shaft 17 and the nut 18.

In the above-described embodiment, a primary groove 1a composed of a plurality of vertical grooves is formed on the outer periphery of the tip side of the mandrel 1, a vertical groove is previously formed on the inner surface of the smooth tube 13, and a twist groove is formed by the plug 16. It may be. By doing so, it is possible to form a cross groove by the vertical groove and the twist groove on the inner surface of the tube.

In the above embodiment, the billet 2 is connected to the stem 5
However, by applying the tool 19, the dicing die 15 and the grooved plug 16 to the die portion of the rotary wheel type continuous extruder, a pipe having a twist groove on the inner surface is continuously obtained. It becomes possible. In this case, the rotary wheel type continuous extruder supplies a metal material (rough drawing line) to a passage formed by an outer circumferential groove and a shoe block provided on the rotary wheel, and sends the metal material sent to the inside of the passage to the inside of the passage. Refers to an extruder that continuously extrudes from the dies arranged in a single wheel, with a plurality of passages provided on one rotating wheel, and an assembly of them, and two rotating wheels arranged vertically and arranged in the middle, And a die part is arranged.

[0022]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) Since an extruded material having an internally twisted groove can be manufactured in one step, the step for twisting can be omitted.

(2) A tube having a complicated shape such as an inner surface secondary groove tube can be manufactured.

(3) The semi-rigid and hard materials of the hot extruded material can be directly manufactured, and the manufacturing process can be omitted.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention.

FIG. 2 is an explanatory view illustrating a conventional extrusion molding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mandrel 6 Port hole 13 Smooth tube 14, 15 Die 16 Slotted plug 21 Extruded tube 21a Twisted groove

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Makoto Oba 3550 Kida Yomachi, Tsuchiura City, Ibaraki Prefecture Within Hitachi Cable, Ltd.System Materials Research Laboratories (72) Inventor Noboru Hagiwara 3550 Kida Yomachi, Tsuchiura City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Company System Materials Laboratory

Claims (2)

[Claims] 1. An extrusion molding method for extruding a material from a port hole from between a mandrel and a die to form an extruded tube, wherein a smooth tube is formed between the mandrel and the die, and the smooth tube is connected to a tip side of the die. The inner grooved tube is extruded by reducing the diameter with a diameter reducing die provided on the inner surface and pressing a plug rotatably provided on the tip of the mandrel to form a twist groove on the inner surface while rotating the plug. Molding method. 2. An extrusion molding method for extruding a material from a port hole from between a mandrel and a die to form an extruded tube, wherein a plurality of vertical grooves are provided on an outer periphery of the mandrel, and an inner surface is provided between the mandrel and the die. A tube with a vertical groove is formed, and the tube is reduced in diameter with a contraction die provided on the tip side of the die, and pressed against a grooved plug rotatably provided at the end of the mandrel while rotating the plug. An extruding method of an inner grooved pipe, wherein a thread groove is formed on an inner surface.