JPH07236920A - Method and device for straightening tubular body - Google Patents

Abstract

PURPOSE:To efficiently obtain a product which is satisfactory in out-of-roundness and straightness over the entire tube length by deforming the tubular body to be straightened, in which a freely rotatable and movable mandrel bar have been inserted, by means of plural inclined rotating rolls arranged on a concentric circular. CONSTITUTION:When deformation is imparted in the circumferential direction of the tubular body 1 by plural inclined rotating rolls 2 arranged on a concentric circular, a tubular body 1 to be straightened is sent to the axial direction while being rotated, by a component of force from the rolls 2, in proportion to the inclined angle to the tubular body axis against the rolls 2. At that time, a freely rotatable and movable mandrel bar 3, which is inserted into the tubular body 1 to be straightened, restrains the tubular body 1 from the inside surface; consequently, the bend of the tube in the longitudinal direction is straightened; and the dimensional accuracy is improved and the out-of-roundness and the straightness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to correction of bending of a tubular body.

[0002]

2. Description of the Related Art As a conventional technique for straightening a steel pipe to obtain a pipe having excellent roundness and straightness, the pipe is continuously installed like a long ERW pipe production line. When it is put in, it is a bending system that turns the pipe at right angles to the pipe axis or moves up and down, left and right, and repeatedly bends the pipe, or a discontinuous single pipe (short pipe) such as a seamless steel pipe 1 In the line for producing a, there is an inclined roll type in which the tubular body is rotated by the inclined roll 2 and repeatedly deformed in the circumferential direction and the longitudinal direction as shown in FIG. In addition, there is a case where a portion such as a pipe end where the correction effect is insufficient is corrected by a press. Furthermore, JP-A-5-423
In the straightening method described in Japanese Patent Publication No. 08-08, as shown in FIG. 5, a tube body 1 hot-rolled by a mandrel mill rolling machine 16 in which rolling rolls 14 are continuously arranged is provided with an inclined roll 2 around a tube axis. It has been proposed to improve the dimensional accuracy by a planetary reeler method in which a planetary reel 8 for turning is pressed and stretched with the mandrel bar 3.

[0003]

Among the straightening methods of the tubular body, in the bending method in which the tubular body is repeatedly bent by a roll in a direction perpendicular to the tubular axis without rotating the tubular body, the roundness of the tubular body is ensured. There is a problem in doing it. In addition, in the inclined roll type straightening method of bending while giving rotation to the pipe,
There is a problem in ensuring the straightness of the pipe end. This is Figure 4
This is because the bending deformation is not applied to the pipe end portion corresponding to the distance between the stands (ls), as shown in FIG. Further, the press straightening method has a problem that the workability is low and the roundness is easily deteriorated. Furthermore, JP-A-5-42
In the method described in Japanese Patent No. 308, the application is limited to the mandrel mill rolling line, the purpose is to reduce the wall thickness, a means for suppressing the rotation of the pipe is required, and the thermal stress after the mandrel mill rolling. However, there is a problem that it is not possible to deal with the deformation due to the above. The present invention has been made to solve the above problems, and an object thereof is to efficiently obtain a product having good roundness and straightness over the entire length of the pipe.

[0004]

In the straightening method for a tubular body according to the present invention, a plurality of rotating inclined rolls in which a tubular body to be straightened in which a rotatable and movable mandrel bar is inserted are arranged concentrically. It is what is transformed. Further, in the tubular body straightening device according to the present invention, the drive-rotating roll, which is inclined about the tubular axis and arranged concentrically with the tubular axis, and the rear end of the mandrel bar are rotatable. In addition, the mandrel bar holding mechanism that supports the mandrel bar movably in the tube axis direction is provided.

[0005]

In the tubular body straightening method of the present invention, the tubular body to be straightened is a plurality of rotating inclined rolls arranged on concentric circles, and when the tubular body is deformed in the circumferential direction, the roll tube is rolled. In proportion to the angle of inclination with respect to the shaft, the component force from the roll causes the component to be fed in the axial direction while being rotated. At this time, since the rotatable and movable mandrel bar inserted in the pipe to be corrected restrains the pipe from the inner surface side, the bending of the pipe in the longitudinal direction is also corrected, and the dimensional accuracy is roundness and straightness. Improve together. Further, in the tubular body straightening device of the present invention, a roll which is driven and rotated around the tubular axis and inclined with respect to the tubular axis and arranged concentrically with respect to the tubular body is arranged in the rotational and axial directions. Deformation with component force is given. The mandrel bar inserted into the tubular body is supported at its rear end by a mandrel bar holding mechanism that is rotatable and movable in the axial direction of the tube. It can move in response to the amount of force that is sent out in the axial direction.

[0006]

The present invention will be described in detail below with reference to an example of one embodiment for demonstrating the straightening method and apparatus of the present invention. FIG. 1 is an explanatory diagram showing the configuration of an example of one embodiment of an apparatus to which the present invention is applied. In the figure, reference numeral 1 denotes a pipe to be straightened, which is a pipe body such as a seamless steel pipe manufactured by a plug mill system or a mandrel mill system. Reference numeral 2 is a roll, which is inclinedly arranged so as to surround the pass line P in the same vertical plane on a concentric circle with the pass line P in which the pipe 1 to be corrected moves in the longitudinal direction, and a plurality of straightening machines 4 are configured. It is driven to rotate by a motor (not shown) from the outside. A mandrel bar 3 is provided on the upstream side of the straightening machine 4 so as to be movable concentrically with the pass line P and to be rotatable.
Reference numeral 5 denotes a sliding block, which rotatably supports the rear end of the mandrel bar 3. A bed 6 supports the sliding block 4 movably along the pass line P on the upper surface parallel to the lower side of the pass line P. The sliding block 5 and the bed 6 form a mandrel bar holding mechanism. Reference numeral 7 denotes a stopper, which is a plate-like member and is provided at the entrance of the straightening machine 4 so as to be able to project and retract in the vertical direction. 8 is a table, which is provided along the pass line P,
It moves up and down together with the stopper 7. 2 and 3 show the relationship between the rotation direction and the force of the roll 2 and the tube 1 to be straightened. The rotation force Fa and the longitudinal feed to the surface of the pipe 1 to be straightened from the roll 2 installed at an inclination angle θ. The force Fb is applied, and the tube 1 to be corrected advances in a spiral shape while rotating. At the same time, a compressive force of P acts on the straightened tube 1 from the roll 2 in the diameter direction of the straightened tube 1. This compressive force causes a straightening action on the straightened tube 1, but the inner surface side of the straightened tube 1 is regulated by a mandrel bar 3 inserted inside,
High dimensional accuracy is obtained. The plurality of rolls 2 that are driven and rotated may be an odd number or an even number, and may be arranged concentrically with the pass line P in either a symmetrical or asymmetrical state.

In the straightening device constructed as described above, the tube 1 to be straightened is placed along the pass line P on the entrance side of the straightening machine 4 on the table 8 in a state where the desired height is raised. , The stopper 7 is also raised. Next, the mandrel bar 3 is inserted into the inner surface of the tube 1 to be straightened in a state where the distal end on the entry side of the straightening machine 4 hits the stopper 7 and does not move. Then, the stopper 7 is lowered. The tube 1 to be straightened and the mandrel bar 3 in the above state are advanced together and drawn into the straightening machine 4 composed of a group of rolls 2 which are rotationally driven. After that, the table 8 descends. As shown in FIG. 2, the roll 2 is installed with an inclination angle of θ with respect to the tube axis and is rotationally driven by a motor from the outside. The tube 1 to be straightened together with a mandrel bar 3 which is rotatably supported by a sliding block 5 which slides on a bed 6,
The force transmitted from the roll 2 causes a deformation for correction while advancing in a spiral shape. In this correction method, the wall thickness is not reduced, but if the outer diameter is slightly reduced (1% or less), the correction effect is further improved. Next, the results of comparing the effect of the method of the present invention with the conventional method are concretely shown in Tables 1 and 2. Table 1 shows the straightening conditions and the straightening results when the thin-walled pipe is straightened. The conventional method is the case of a general inclined roll type straightening machine as shown in FIG. 4, and the method of the present invention is the case of straightening using a mandrel bar with four rolls shown in FIGS. For the bending amount of the raw pipe, the same condition was selected for comparison. In addition, the position to compare the bends of the pipe is 1m at the tip of the pipe where correction bend is likely to remain.
We compared about the part. As is clear from Table 1, the bending correction effect according to the present invention is clear. Further, it is clear that a further correction effect can be obtained under the condition of slightly reducing the outer diameter of the tube. Table 2 shows straightening conditions and straightening results when a relatively thick tube is straightened. In the case of a thick-walled tube, the correction effect is likely to appear on the whole, but the correction effect of the present invention is clear.

[0008]

[Table 1]

[0009]

[Table 2]

[0010]

As described above, according to the present invention, by arranging a plurality of rolls in the same vertical plane and performing straightening using a mandrel bar, roundness and straightness can be obtained over the entire length of the pipe to be straightened. Corrective work with high accuracy can be efficiently performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an aspect example of an apparatus to which the present invention is applied.

FIG. 2 is a side view showing a relationship between a rotation direction and a force of a roll and a tube to be corrected.

FIG. 3 is a front view showing a relationship between a rotation direction and a force of a roll and a tube to be corrected.

FIG. 4 is an explanatory view showing a roll arrangement of a conventional inclined roll type straightener.

FIG. 5 is an explanatory diagram showing a configuration of a conventional planetary type hot finish rolling mill.

[Explanation of symbols]

 1 Tube to be straightened 2 Roll 3 Mandrel bar 4 Straightening machine 5 Sliding block 6 Bed P Pass line

Claims (2)

[Claims] 1. A straightening method of a tubular body, comprising: deforming a straightened tubular body having a rotatable and movable mandrel bar inserted therein with a plurality of rotating inclined rolls arranged on a concentric circle. 2. A roll which is driven and rotated around a pipe axis and is arranged concentrically with respect to the pipe axis, and a rear end of a mandrel bar is rotatable and movable in the pipe axis direction. A straightening device for a tubular body, comprising a supporting mechanism for supporting a mandrel bar.