JPS63174703A - Production of pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention rolls raw pipes such as seamless pipes with a circular cross section.

The present invention relates to a method for manufacturing a pipe having a circular cross section and an outer diameter smaller than the base pipe by performing wall thinning processing by punching or drawing.

[Prior art]

As a method for reducing the diameter of a metal tube with a circular cross section, a mandrel bar or a plug is inserted into the metal tube, and the groove shape of two or more groove rolls is formed, specifically as shown in FIG. For example, a hole pattern 22 formed on four circumferential surfaces by arranging four groove rolls 21.21, 21.21 around the pass line.
Let it bite and roll here.

There is a method of reducing the thickness of the metal pipe by punching or drawing.

[Problem that the invention seeks to solve]

In this method, the raw pipe portion that has been rolled down by the rolls is stretched in a direction perpendicular to the rolling direction. Therefore,
When the raw pipe is subjected to high pressure, the amount of stretching becomes large, and the amount of stretching increases between the adjacent rolls, that is, at the shoulder shoulders 23, 2323.2.
3, and it may become impossible to process after that.

This protrusion does not occur when four grooved rolls are used, but generally occurs similarly when two or more grooved rolls are used.

In addition, as shown in FIG. 6, a reaction force (indicated by an arrow) from the raw pipe in a direction perpendicular to each position of the groove forming groove 21a formed on the circumferential surface of the roll 21 that contributes to the pressure reduction of the raw pipe is applied. occurs, and grooves 2 are formed in the roll 21 due to the reaction force in the longitudinal direction of the roll axis.
Tension in the axial direction (indicated by an open arrow) acts except directly below the bottom of 1a.

Therefore, when processing is performed using grooved rolls, it may not be possible to apply high pressure to the raw pipe due to the strength of the rolls. For this reason, the use of large diameter rolls is required, and since the degree of processing per pass is low, it is necessary to prepare a large number of holes depending on the finished outer diameter of the product pipe, and the hole forming grooves are three-dimensional. Because of the rough shape, it takes a long time to cut the grooves, and it is necessary to have a large number of spare rolls for the time being, which is uneconomical.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a pipe manufacturing method that can apply high pressure to the raw pipe, does not become unworkable even when the high pressure is applied, and is economical. purpose.

[Means for solving problems]

In the present invention, a blank pipe with a circular cross section is subjected to high pressure using a cylindrical flat roll to reduce the thickness of the raw pipe, and at the stage of making a product pipe, the irregular cross section is returned to a pipe with a circular cross section.

That is, in the tube manufacturing method according to the present invention, a cylindrical roll is formed around the pass line by 3111i! A raw pipe with a circular cross section with a mandrel or plug inserted inside is inserted between the rolls of the rolling down device arranged above, and the material is reduced by rolling, punching or drawing, and after that, the mandrel or plug is inserted. The method is characterized in that a tube having a circular cross section is manufactured by rolling using grooved rolls in the state of the pipe, or by punching or drawing using a ring die.

[Effect]

In the present invention, a blank tube with a circular cross section into which a mandrel or a plug is inserted is partially rolled down in the circumferential direction by cylindrical rolls, thereby making the cross section irregular and thinning. Then, rolling using grooved rolls or punching or drawing using a ring die is performed to produce a product tube with a circular cross section.

〔Example〕

The present invention will be specifically explained below based on the drawings.

Fig. 1 is a side view showing the implementation state when the present invention is applied to rolling processing, Fig. 2 is a front view taken along the IF-IF line in Fig. 1, and 1 is a metal with a circular cross section to be rolled. Shows the raw pipe made by The raw tube 1 is a long mandrel 2 with a circular cross section.
Inserted therein, the sheet is transferred in the axial direction indicated by the white arrow (this is referred to as the main direction), and is bitten by the reverse type rolling device 10, where it is repeatedly rolled.

On the upper and downstream sides of the lowering device 10 in the main direction, there are provided a first.
A second tube rotation and transfer bed (not shown) is provided;
This first. The second tube rotation/transfer bed rotates the raw tube 1 by 45° around its axis during repeated rolling by the rolling down device 10, and then transfers it to the rolling down device 10.

The rolling down device 10 has four cylindrical rolls 11.11.11.11 with flat circumferential surfaces arranged at 90° pitch around the pass line.
It is individually arranged and rolls 11.11. ... can be rotated in the main direction or the opposite direction by a motor and driving force transmission means (not shown). Roll @12.12.・・・
・.

12 is supported by a support device (not shown) so that the distance between the rolls and the axis of the raw pipe 1 during rolling down (hereinafter referred to as the distance between the rolls) can be adjusted, and the distance between the rolls can be adjusted in the main direction or in the opposite direction. Each time rotation in the direction is completed, it is changed according to the degree of work in the next rolling.

A rolling mill (not shown) having a circular groove formed by a conventional groove roll is provided on the downstream side of the rolling device 10 in the main direction, and the size of the groove is determined according to the size of the product pipe. ing.

The pipe manufacturing method according to the present invention is carried out in the following manner using the equipment configured as described above.

A mandrel 2 is inserted into the inside of the raw pipe 1 and transferred to the rolling down device 10 from the upstream side in the main direction. The raw pipe 1 caught in the rolling down device IO is rolled according to the distance between the rolls. At this time, a reaction force from the raw pipe 1 acts on the roll 11, but since the roll circumferential surface is flat, a component of the reaction force in the roll axis length direction is not substantially generated, and tension in the axis length direction is applied to the roll. The rolled raw pipe 1 has a substantially rectangular irregular cross-section that has been rolled down at four points in the circumferential direction over its entire length, and is then exited from the rolling down device 10 and placed on the second pipe rotation/transfer bed 5. placed.

When this rolling is completed, the operator, for example, sets the distance between the rolls to a smaller appropriate value, rotates the base tube 1 thereon by 45 degrees around the axis on the second tube rotation/transfer bed, and then The roll is transferred in a secondary direction opposite to the main direction, and the roll is rotated in the opposite direction to the previous direction.

As a result, the previously unrolled portion of the raw tube 1 is rolled by the rolling down device 10. Also at this time, no tension is applied to the roll 11 in the axial direction. The rolled blank tube 1 is placed on the first tube rotation/transfer bed in a state of irregular cross section over its entire length.

Each time the rolling is completed, the operator sets the distance between the rolls to a smaller appropriate value and then rotates the rolls on the first and second tube rotation/transfer beds to transfer the rolls in the main direction or the sub direction. As a result, the raw pipe 1 is repeatedly rolled by the rolling device 10.

Thereafter, when the opposite side dimension of the raw pipe 1 is reduced to a dimension slightly larger than the product dimension, the operator finishes rolling using the rolling down device 10.

For each rolling mentioned above, the rolling reduction rate, that is, the distance between the rolls, is determined so that the length of the roll width W is longer than the circumferential length lc of one rolled part of the raw pipe 1, as shown in FIG. . This is because by applying a pressure of W≧2c to the raw pipe 1, the part of the raw pipe that passes through the roll shoulder is mainly stretched in the circumferential direction due to the elongation of the lower part of the raw pipe in the longitudinal direction of the pipe axis, and This is because the occurrence can be prevented.

After that, the raw pipe 1 is placed in a rolling mill (not shown) on the downstream side in the main direction of the rolling device 10 with the mandrel 2 inserted inside, or once the mandrel 2 is pulled out and a new mandrel with a slightly smaller diameter is inserted. The raw tube 1 having an irregular cross section is then rolled in the groove of the rolling mill to form a product tube having a circular cross section.

In the method of the present invention, since a reduction is applied to the raw pipe 1 by the flat rolls 11, no tension is generated in the axial direction, and high reduction rolling is possible. Since the distance can be changed, the number of rolls required can be significantly reduced, and since the rolls are flat, there is no need to keep many spare rolls, and in addition, roll cutting is easy.

In the above embodiment, four rolls are arranged around the pass line, but the present invention is not limited to this, and can also be carried out using a rolling down device with three or five or more rolls arranged around the pass line. As described above, the reason why the number of rolls is set to three or more in the present invention is as follows.

That is, as shown in FIG. 3, when the raw tube 1 with the mandrel 2 inserted therein is rolled by two flat rolls 11, 11, the raw tube 1 bulges in the tube radial direction perpendicular to the rolling direction. In other words, flaring may occur and streak-like flaws may occur on the inner surface of the raw pipe 1. Therefore, the tube circumferential surface is
By restraining at a tension of 1 lb or more, it is possible to prevent the occurrence of flaws.

However, during each rolling by the rolling device 10, the angle θ at which the raw tube is rotated around the axis is determined according to the number n of rolls used as shown in the following equation.

θ=180' 10Although a mandrel is used in the above embodiment, the present invention is not limited to this, and the pipe can be similarly manufactured by inserting a plug inside the raw pipe portion that is rolled down by rolls.

Further, in the above embodiment, a reverse type rolling down device is used, but the present invention is not limited to this. Rolling is performed during transfer in the main direction using a rolling device in which the rolls are rotated in one direction, and then the secondary rolling device is used. It can also be carried out by repeating the rolling by rolling back in the direction without being rolled down, or it can be carried out by using a plurality of similar rolling devices installed in tandem.

Furthermore, in the above embodiment, a product tube with a circular cross section is produced from an irregular cross section using a conventional rolling mill using grooved rolls, but the present invention is not limited to this. It is also possible to punch out or pull out a tube with an irregular cross section using the same method.

Further, in the above explanation, the raw pipe is rolled using a rolling device having a roll drive mechanism, but the present invention does not rely on this, and instead involves punching or pulling out the raw pipe using a rolling device not equipped with a roll drive mechanism. You can do the same thing if you go.

〔effect〕

FIG. 4 shows the first case in which the present invention is carried out using four flat rolls (only one roll is shown by a two-dot chain line in the figure) 11 using a garden lead pipe as a raw pipe. The cross-sectional shape of the raw tube after the second stand (Tal, (shown in bl) and the cross-sectional shape of the tube finally manufactured using a ring die or roller die ((cl, (shown in dl) ), and the broken line in the figure shows the raw pipe before thinning.The manufacturing conditions are: outer diameter: 164.5 mm.

Wall thickness: 3.3 m thick inside lead pipe with outside diameter: 93 fi
Insert a φ mandrel and roll it @W is 10゜n
The degree of processing is 26%, 50%, and 45% using the following rolls.
, and the minimum wall thickness is 21m, 9.5 tm, 8.5
It was manufactured in 3 passes so that x was obtained.

As can be understood from this figure, the present invention has a flat roll 11.
By using this method, we were able to apply high pressure to the raw tube, which enabled us to reduce the thickness with a high degree of processing.

As described in detail above, the present invention uses a rolling device having three or more cylindrical rolls arranged around a pass line, and inserts a mandrel or a plug into a blank pipe having a circular cross section to perform rolling, punching, or drawing. After that, the mant
Product pipes with a circular cross section are manufactured by rolling using grooved rolls with a lulu or plug inserted, or by punching or drawing using a ring die, so high pressure processing without overhanging is possible. In the case of a tandem type rolling down device, the number of stands and rolls can be reduced, while in the case of a method that changes the distance between rolls, the number of rolls can be significantly reduced, and flat rolls can be used. Therefore, the period required for cutting is short, and therefore the number of spare rolls to be kept can be extremely reduced, and the cost of cutting the rolls is also kept low, making it possible to manufacture tubes economically.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the implementation state of the present invention, and FIG.
A front sectional view taken along the line ■-■ in the figure, FIG. 3 is an explanatory diagram of the reason for limiting the number of rolls used in the present invention, FIG. 4 is a detailed explanatory diagram of the present invention, and FIG. 5 is an explanation of the contents of the prior art 6 are explanatory diagrams of problems in the prior art. 1...Main pipe 2...Mandrel 10...Reducing device 11...Roll patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono 5 Diagram no! 2/? Figure G Figure 1 Figure 2 Old

Claims (1)

[Claims] 1. A blank tube with a circular cross section with a mandrel or plug inserted inside is inserted between the rolls of a rolling device having three or more cylindrical rolls arranged around a pass line, and rolled and pressed. Thickness is reduced by punching or drawing, and then rolling with a grooved roll with a mandrel or plug inserted, or punching or drawing using a ring die, to produce a material with a circular cross section. A pipe manufacturing method characterized by forming a pipe. 2. The tube manufacturing method according to claim 1, wherein the rolling down device is equipped with a mechanism for adjusting the rolling down position. 3. The pipe manufacturing method according to claim 1, wherein the rolling down devices are installed in tandem.