JP2000158038A - Diameter reduction of metal pipes - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To increase the degree of drawing Re when drawing a metal pipe by a drawing machine and reducing the diameter, thereby reducing the number of times of drawing from the mother pipe to the product size. And a method for reducing the diameter of a metal pipe. A plurality of drawing dies are arranged at intervals in a die holder of a tube drawing machine, and a gap between the drawing dies before and before and after a first-stage drawing die is filled with a lubricant, respectively. 1 pass metal pipe with a drawing die. Preferably, two drawing dies are arranged in the die holder of the tube drawing machine, and the gap between the first-stage drawing die and the gap between the first-stage drawing die and the second-stage drawing die is filled with a lubricant. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing the diameter of a metal pipe by drawing it.

[0002]

2. Description of the Related Art In order to manufacture a metal pipe, a method is generally employed in which a large-diameter mother pipe obtained by extrusion or welded pipe forming is formed into a predetermined size by a diameter reducing process such as a die drawing tube.

[0003] The above-described tube extension is implemented by a pull block type single-head tube extension machine shown in FIG. This is because the metal pipe 2 coiled in the basket 6 is drawn out by a drawing die by drawing the metal pipe 2 and passing it through the die holder 1, and then wound in a coil shape while being pressed against the rotating drum 5 by a pressing roll 7. ,
And it is the method of coiling in the basket 5.

FIG. 4 specifically shows the inside of the die holder 1. A drawing die 3 is mounted in the die holder 1, and a portion before the drawing die 3 is filled with a lubricating oil 4.

[0005] In the above method, the amount of elongation in one pass of the die, that is, the degree of outer diameter working Re in one pass, must be set so that the pulling force of the pipe is equal to or less than the breaking load on the die passing side of the pipe. This Re is the specification of the pipe (material, outer diameter /
Although it is empirically specified separately for the inner diameter ratio, etc., Re
(%) = (Pipe outside diameter before processing) − (Pipe outside diameter after processing) / (Pipe outside diameter before processing).

[0006] As a typical example, copper and stainless steel drawn pipes are shown with Re = 20 to 30%.

[0007]

The problem with the prior art described above; the method of reducing the diameter of a metal pipe shown in FIGS. 3 and 4 is that the number of drawing passes is large because one die is drawn. For example, when a 10 mm metal pipe is pulled out to 1 mm using the single-head pipe expander shown in FIG. 3, the pipe must be repeated seven times in total with a metal pipe whose Re = 30% is the limit.

Therefore, the problems to be solved by the present invention (objects)
It is possible to increase the degree of drawing Re in the case where the metal pipe is pulled out by a pipe drawing machine to reduce the diameter, thereby reducing the number of times of drawing from the mother pipe to the product size. It is to provide a diameter reduction processing method.

[0009]

According to the method for reducing the diameter of a metal pipe provided by the present invention, a plurality of drawing dies are arranged at intervals in a die-drawing machine die holder, and before the first-stage drawing die. And a method in which a gap between the front and rear drawing dies is filled with a lubricant, and the plurality of drawing dies are used to form a one-pass drawing of a metal pipe.

In a preferred embodiment, two drawing dies are arranged in a die-drawing machine die holder, and a gap between the first-stage drawing die and a gap between the first-stage drawing die and the second-stage drawing die is formed. Each provides a method of filling with a lubricant.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a method for reducing the diameter of a metal pipe according to the present invention in the form of a die holder and a die and the state of drawing by the die.

In this embodiment, the first-stage drawing die 3-a and the second-stage drawing die 3-b are set in the tube-drawing machine die holder 1 with an interval therebetween.
A lubricating oil 4 as a lubricant is filled in a portion before the first-stage drawing die 3-a and a front-rear gap between the first-stage drawing die 3-a and the second-stage drawing die 3-b. The metal pipe is supplied, and the first-stage drawing die 3-a and the second-stage drawing die 3-b are used to draw lubricating oil into both the dies and the pipe, thereby performing one-time drawing by two continuous drawing operations. How to

By applying the two continuous drawing operations as in this embodiment, it is possible to increase the degree of drawing Re in comparison with the conventional method (FIGS. 3 and 4).

In order to verify the effect of the above-described method, a one-pass drawing experiment was performed using a draw bench. At this time, the test pipe was made of a material: Fe-42% Ni alloy (full annealed material), dimensions: φ9.6 mm × t0.7 mm × L5 m, and the drawing conditions were as follows: drawing speed: 10 m / min (lubricating oil) The kinematic viscosity was 2500 mm ² / s), and a conical die (die full angle 14 °) was used as a drawing die. The conventional method (FIGS. 3 and 4) was used as a comparative example under the same conditions as above.
The combination of the drawing dies in the examples is
The first stage had an intermediate size between the test pipe (before drawing) and its finished outer diameter (after drawing), and the second stage had the finished outer diameter. Table 1 shows the results of the tube drawing experiments of these examples and comparative examples.

[0015]

[Table 1]

As is evident from Table 1, it was found that the elongation degree Re of the example was 10% larger than the elongation degree Re of the comparative example. As a result, the number of elongation passes up to a 10 mm outer diameter mother tube can be reduced by two from seven to five.

According to the above-described embodiment, the present invention can be implemented by a simple improvement of only the existing die-drawing machine die holder, and can be provided as a unique practical method.

In order to simplify the structure of the die holder, the gap between the first-stage drawing die 3-a and the second-stage drawing die 3-b shown in FIG. 1 is made zero.
In other words, when the pipes were made to adhere to each other and the tube drawing experiments were performed in parallel, in the case of a pipe diameter of 5.5 mm that could be drawn in the above-mentioned experiment, the test pipe was the second stage. When only lubricating oil flowed into the drawing die, seizure occurred, and when the pipe was stretched 1 m, the pipe was cut off. From these results, it was verified that it is a necessary condition to provide a gap between the front and back of the first-stage drawing die and the second-stage die so that sufficient lubricating oil flows into the second-stage drawing die. Was done.

The above-described embodiment has been illustrated as an optimal one to the extent that it is tired, and modifications and applications other than those are possible. For example, the present invention can be applied not only to a single-head drawing machine but also to a continuous drawing machine.

Further, in the manufacturing process of the optical fiber unit for an optical fiber composite overhead ground wire as shown in FIG. 2A, pipe forming by aluminum tape (roll forming / TIG welding) and die drawing are performed. In addition, the present invention can be applied to a process of inserting an optical fiber at the same time. In addition, FIG.
In (1), there is a simultaneous and continuous pipe drawing part (five-step pipe drawing). Here, the first pipe is plug-pulled and the second to fifth steps are idle. FIG. 2B shows the state of TIG welding in the above step, and FIG. 2C shows the optical fiber unit after drawing. In these FIGS. 2A to 2C,
8 is an aluminum tape feeder, 9 is a slitter, 10 is an optical fiber feeder, 11 is a forming unit, and 12 is T
IG welding machine, 13 is an endless track (caterpillar), 14 is a dancer, 15 is a washing machine, 16 is a winding machine, 17 is an optical fiber unit, 18 is an optical fiber, 19 is an aluminum tape, and 20 is an aluminum pipe weld. Show.

[0021]

According to the present invention as described above, the degree of drawing Re can be increased when a metal pipe is drawn out by a pipe drawing machine and reduced in diameter, whereby the product dimension from the mother pipe can be increased. The object (object) of providing a method for reducing the diameter of a metal pipe, which can reduce the number of times of drawing, can be achieved, and can greatly contribute to a reduction in manufacturing cost.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a method for reducing the diameter of a metal pipe according to the present invention in the form of a die holder and a die and a drawing state of the metal pipe by the die holder, and FIG.
(B) is a longitudinal sectional view.

FIG. 2A is an explanatory view showing a manufacturing process of an optical fiber unit for an optical fiber composite overhead ground wire, FIG. 2B is an explanatory cross-sectional view showing a TIG welding situation of an aluminum pipe in the manufacturing process, and FIG. FIG. 3 is an explanatory cross-sectional view of the optical fiber unit after drawing.

FIG. 3 is an explanatory diagram showing a conventional example using a single-headed pipe expander (pull block).

4A and 4B show the inside of a die block in the single-head pipe expander shown in FIG. 3, wherein FIG. 4A is a plan view (top view) and FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dice holder 2 Metal pipe 3-a First stage drawing die 3-b Second stage drawing die 4 Lubricating oil

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hiroaki Numata 4-10-1, Kawajiri-cho, Hitachi-shi, Ibaraki F-term in the Toyoura Plant of Hitachi Cable, Ltd.

Claims (2)

[Claims] In a method for reducing the diameter of a metal pipe by drawing a die, a plurality of drawing dies are arranged at intervals in a drawing machine die holder, and before and after a first-stage drawing die. A method for reducing the diameter of a metal pipe, wherein a gap between the drawing dies is filled with a lubricant, and the plurality of drawing dies are used to form a one-pass drawing of the metal pipe. 2. A drawing machine, wherein two drawing dies are arranged in a die holder, and a lubricant is provided before the first-stage drawing die and a gap between the first-stage drawing die and the second-stage drawing die. The method according to claim 1, wherein