JPS6167528A - Tube expansion method of metallic tube - Google Patents

Abstract

PURPOSE:To manufacture a long sized thick tube by a expanding without causing a buckling by moving the narrow width heating zone of the same coaxial shape as the metallic tube to be expanded at the fixed relative interval always to a plug. CONSTITUTION:A expanding by drawing is performed with moving a heating zone 5 in the same direction as of a plug 3 simultaneously with the plug 3 as well as moving the plug 3 by a drawing rod 4 with fixing one end of a metallic tube 1. The part of narrow width only is locally heated at the position where the metallic tube 1 which is about to be expanded with the advance of the plug 3 to the metallic tube 1 and the plug 3 are started to be placed into contact. Other parts are made to remain cold as they are, so that there is no reduction in a rigid body and the length of the limit for buckling generation is elongated and the expanding of a long sized tube is enabled.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method of expanding a metal tube.

(Prior art and problems) There are several methods for expanding metal pipes, but one of them, as shown in Figure 3, is to expand one end of the pipe 1 in advance and fix it to the fixing plate 2, and heat the entire pipe. The method of enlarging the pipe by inserting a plug 3 with an outer diameter smaller than the inner diameter of the pipe into the pipe and pulling the pull rod 4 to the left in the same figure is as shown in the example shown on October 3, 1952.
It is known from ``Preparation of Seamless tIs Pipe'', page 75, published by Seibundo Shinkosha Co., Ltd. However, with this method, the metal tube undergoes tensile deformation in the axial direction, so the wall thickness decreases significantly as the tube expands, making it difficult to manufacture thick-walled tubes.

In other words, in order to manufacture thick-walled pipes, it is necessary to prepare thicker-walled gold main pipes as raw pipes, but it is difficult to manufacture such thick-walled raw pipes, and the pulling force is also low. In order to grow in size, the processing equipment must also become huge.

Furthermore, instead of heating the entire tube and then pulling out the plug, it is also possible to fix the plug, push the tube into it, and apply compressive deformation in the axial direction to expand the tube. It was impossible to manufacture long tubes because it was prone to buckling, and it was impractical.

(Means for Solving the Problem) In view of the above-mentioned circumstances, the inventors of the present invention have made extensive studies, and found that instead of heating the entire pipe as in the past, only the narrow range of the gold paddy pipe to be expanded is heated. This makes it possible to manufacture long thick-walled tubes by expanding them without causing buckling.

(Structure and operation of the present invention) That is, when expanding a metal pipe using a plug having an outer diameter larger than the inner diameter of the pipe, the present invention applies a narrow heating zone that is concentric with the metal pipe to be expanded. This is a method of expanding a metal tube in which one or both of the plug and the heating zone and the metal tube to be expanded are moved relative to each other, with the plug and the heating zone always being positioned at substantially constant relative positions.

The present invention will be explained in detail below.

First, in the present invention, metal tubes are Fe, (Er, N
It refers to a pipe made of pure metals such as iAl5Cu, Ti%Zr, and alloys containing these as main components, and is used for transporting gases, liquids, etc., or for structural parts.

Next, in the present invention, it refers to a narrow heating zone whose heating source is an incense heating or a gas ring burner, and has a 1 mt core shape with the pipe to be expanded. In this case, the width is such that it is possible to expand the tube without bending by heating only the part that is about to expand and the part in front of it. finger (7,
Specifically, the source of addition, the type of metal, the thickness of the pipe, and the expansion! rate,
Although it depends on the plug shape etc., it is desirable that it is about 1 to 5 times the size.

Next, embodiments of the present invention are shown in FIGS. 1 and 2. Among these, in FIG. 1, one end of the metal tube 1 is fixed by an arbitrary means not shown, and the plug 3 is moved to the left in the figure by a pull-out rod 4, and the heating zone 5 is moved in synchronization with the plug 3. Fig. 2 shows a method of moving the plug 3 in the same direction as the plug 3 and spreading it out. Fig. 2 shows the method of moving the plug 3 in the same direction as the plug 3 and fixing the plug 3 by using the support plate 6 and keeping the relative position of the heating zone 5 with the plug 3 constant. This shows a method of expanding the metal tube 1 while compressing and deforming it from the left side of the 2M using an arbitrary pressing means (not shown) after fixing the same as shown in FIGS. 1 and 2. method can also be adopted. Similarly, heating zone 5 is the first
In both FIG. 2 and FIG. 2, the expansion plate is provided on the entry side of the plastic pipe 3 to the metal pipe 1 so as to be substantially concentric with the metal pipe. In this case, the plug 3 and the attaching firefly 5 are always provided in a substantially constant relative position as described above, but the relative position is as shown in FIGS. 1 and 2. Gold ν) When the plug 3 enters the 5 positive 1, by locally heating only the aforementioned narrow part at the position where the plug 3 starts to come into contact with the metal pipe 1 that is about to be expanded. , the other parts are left in a cold state, so there is no decrease in rigidity and the critical length for buckling becomes longer, so the second
As shown in the figure, even when expanding a tube by applying flattening deformation in the axial direction, it is possible to expand a long tube without causing buckling. The embodiments shown in FIGS. 1 and 2 above are only examples, and the present invention does not apply to either or both of the following. In addition to the two methods described in hi'I, an example is given in Figure 1. 1 to the right in the figure, and at the same time move the plug '3 and the adder/firefly 5 to the left in the figure. A method in which the expanded side, that is, the right side, is pulled to the right by any means not shown,
Furthermore, as shown in Fig. 1, the plug 3 and heating zone 5 are fixed in Fig. 2, and an appropriate method can be used depending on the necessity of suction, such as a method in which the plug 3 and the heating zone 5 are fixed and pulled simultaneously by any means from the right and left ends of the metal tube l. The only thing to do is to adopt.

Similarly, in this case, it goes without saying that the magnitude of the pushing force and pulling force can be determined depending on the wall thickness of the expanded pipe material to be manufactured.

Next, the effect of the present invention will be further demonstrated on a monthly basis using an actual tAh example.

Using a charcoal steel tube with a diameter of 50 mm, a wall thickness of 5 mm, and a length of 400 mm as the raw tube, the heating zone and plug were fixed using the method shown in Figure 2, and the steel tube was pushed in to create a tube with an expansion rate of 1.5. The tube was expanded to a circle.

As a heating means, a fossa frequency induction heating having a coil with a width of 10 mm was used, and the pushing speed was 950 mm/see.
The plug was heated to a temperature of 0.degree. C. and formed into a trapezoidal cone measuring 40.degree. As a result, the outer diameter is 75.1 mthl, the length is 292 mm,
A steel pipe with a wall thickness of 4.35 rnn was obtained, and the pressing force was 12.7 tons. On the other hand, the entire tube was heated and expanded using the conventional method shown in FIG. 3 for a similar tube.

A heating furnace was used for heating, and the temperature was raised to 1000°C for 30 minutes.
It was held for 20 minutes. The plug had a trapezoidal shape with an apex angle of 400 at a drawing speed of 1 m/sec. As a result, a steel pipe with an outer diameter of 74.6 mm, a wall thickness of 3.41 mm, and a length of 323 mm was obtained, and the pulling force was 13.2 tons. The conventional method shown in FIG. 3 required more than 50 pieces of raw pipe to fix the ends, which could not be used as a product, resulting in poor yields. Furthermore, the skin condition of the product was better with the method shown in Figure 2.

(Effects of G and Ming) As detailed above, by changing to a method that controls only the part to be expanded instead of heating the entire tube, it is possible to obtain The condition of the skin of the filter lead pipe is improved, and the product yield can be improved by eliminating the need for the 11 constant portion at the end and by making it possible to add pressurized wax B2 in one direction. With this, it becomes easy to obtain thick-walled pipes.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing examples of implementation of the present invention for deaf patients, and FIG. 3 is a schematic diagram showing a conventional method. ■...Metal tube 2...Fixed pipe 3...Plug 4...Pull-out ladder 5...Heating zone
6...Support rod.

Claims (1)

[Claims] When expanding a metal pipe using a plug having an outer diameter larger than the inner diameter of the pipe, a narrow heating zone is provided concentrically with the metal pipe to be expanded so as to always take a substantially constant relative position to the plug, A method for expanding a metal tube, which comprises relatively moving one or both of the plug and the heating zone and the metal tube to be expanded.