JPS5978718A - Production of small diameter pipe - Google Patents

Abstract

PURPOSE:To produce a seamless steel pipe which has no weld zone, is small in diameter and is thickly walled in a simple stage without requiring any specific installation by heating a pipe of a metal, clamping the pipe at both ends, and elongating axially the same thereby reducing the diameter of the pipe. CONSTITUTION:Both ends of a steel pipe are clamped by current conducting chucks and current is conducted thereto to heat the pipe up to a prescribed temp. The current conducting chucks are removed and in turn the pipe is clamped with pulling chucks and is pulled by the same, whereby the pipe which is made small in diameter except both ends is obtd. Since the above-mentioned pipe is produced simply by the means for heating and pulling without requiring any specific rolling means, an initial cost is low and high productivity is obtained, because the time required for the production is short.

Description

[Detailed Description of the Invention] The present invention uses a pipe made of other metal as a material,
The present invention relates to a method for manufacturing small diameter tubes. The method of the present invention is particularly useful for producing thin-diameter, thick-walled tubes.

In recent years, there has been an increasingly strong demand for weight reduction and reduction in manufacturing loss for automobiles and other machinery, and in response to these demands, tubular bodies have been increasingly adopted as structural members. Taking steel pipes as an example, they are broadly classified into welded steel pipes and seamless steel pipes depending on their manufacturing method, and each has its advantages and disadvantages. In other words, welded steel pipes have high productivity and low cost, but because defects occur in the welded parts, they are not used as important safety parts. J.It is difficult to build something within the government office due to the narrow path. On the other hand, seamless t! 4 tubes are highly reliable, so
Although it can be used for parts subject to high stress, small-diameter products are manufactured by reducing the diameter from hot extruded steel pipes.

The purpose of the present invention is to solve these problems and to manufacture seamless steel pipes without welded parts with a small diameter and thick wall through a simple process without requiring special rolling equipment. The purpose is to provide a method.

The method for manufacturing a small-diameter tube of the present invention consists of heating a metal tube other than both ends to a temperature at which plastic working is easy, grasping both ends, and stretching the metal tube in the axial direction to reduce the diameter.

The means of heating is arbitrary, and the simplest option is to use a gas flame or an electric furnace, but in order to significantly enjoy the high productivity that is one of the effects of the present invention, it is desirable to heat rapidly. . From this point of view, it is preferable to directly energize the material using dicol heat or to heat it by high-frequency induction.

In particular, direct energization is the simplest method, and if a tension chuck that grips both ends and pulls the material also serves as the energization chuck, tensioning can be started immediately after the material is heated to a predetermined temperature by energization. It's convenient.

The temperature to be reached during heating is appropriately selected depending on the material of the material and the intended number of seconds for diameter reduction.

If the temperature is too low, the deformation resistance during plastic working is large and a large force is required for tension.
and circumferential uniformity.

As can be easily understood, the degree of reduction in the pipe diameter is determined by the length of the draw, and this can be selected from a fairly wide range depending on the easily available material and the desired pipe diameter. .

When using the method of the present invention, no special rolling equipment is required as described in 1 above, and heating and stretching means are sufficient, so the equipment cost is small and the process can be completed in a short time. , extremely productive.

The biggest advantage is that even if the diameter of the tube is reduced during stretching, the wall thickness of the tube does not decrease much, and this is a major advantage in the M construction of small-diameter, thick-walled tubes, which were difficult to manufacture using conventional techniques. This is why the invention is particularly useful.

1-L-Takumi A steel pipe for STR-' G 38 pressure piping according to JIS G 3454 standard as shown in FIG. 1 was prepared.

The dimensions of each part are as follows.

Outer diameter DI = 34.0111m Inner diameter d+ = 26.0mm Initial length L+ = 5000-mm Hold both ends of this conduit with an energizing chuck and directly energize it J: 760
℃ in 20 seconds.

Grip length I=-1001111 Remove the energizing chuck and use a tension chuck instead. Relative speed between the chuck and the chuck: 600 mm/
By applying a tension of s(!a), a tube with a small diameter except for both ends was obtained as shown in FIG.

Outer diameter Dz = 25.8++v Inner diameter dz = 19.4 mm Length after tension l-2 = 8000 mm The outer diameter reduction rate is 24.1%, and the wall thickness reduction rate relative to this is 6.
It remained at 0%.

[Brief explanation of drawings]

FIG. 1 is a partially omitted, half-sectional view of a metal tube that is a raw material for manufacturing small diameter tubes. Figure 2 (This is a similar view to Figure 1, showing a small diameter pipe made by WA manufacturing by applying the method of the present invention to the material shown in Figure 1.) Agent Co., Ltd. Patent attorney Su Kawao

Claims (2)

[Claims] (1) A method for manufacturing a small-diameter tube, which comprises heating a metal tube to a temperature at which it is easy to plastically shape parts other than both ends, grasping both ends, and stretching the tube in the axial direction to reduce the diameter. (2) The manufacturing method according to claim 1, wherein the heating is performed by direct energization or electric current to the metal tube or by frequency induction.