JP2005138164A - Straightening method for seamless steel pipes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a straightening method for a seamless steel pipe capable of highly straightening straightness.
In a straightening method for a seamless steel pipe, a two-roll straightening comprising a combination of a multi-roll straightening machine composed of a plurality of opposing rolls and staggered stands and a pair of concave-convex rolls or concave-convex rolls. A straightening method for a seamless steel pipe, characterized by improving straightness to a material end with high accuracy and reducing an end cutting allowance during a cutting process by correcting with a machine.
[Selection] Figure 1

Description

  The present invention relates to a straightening method for manufacturing a seamless steel pipe, and more particularly, to a straightening method for a seamless steel pipe having excellent straightness to the end of a material.

  Generally, a material that has been hot-rolled, cold-rolled, or heat-treated can be straightened to remove the bending of the material, and the degree of straightness required by the secondary processing department or the user, which is a subsequent process, can be obtained. The required bending standard is 1 mm or less per 1 m of material, and straightness is important because various processes such as cutting, cutting, and polishing of the material are performed in the subsequent process. Further, in cutting and removing a defective portion of a material in a cutting process after correction, it is regarded as important to shorten the cutting margin and improve the yield because this leads to a reduction in manufacturing cost and an improvement in productivity.

  However, in order to obtain the straightness required by the post-process, it is necessary to remove the bend remaining at the end of the material in the cutting process. If the straightness of the end is poor by correction, the end is cut by cutting. The bill gets bigger. Therefore, in the conventional method, for example, Japanese Patent Application Laid-Open No. 11-33619 (Patent Document 1) discloses a correction method relating to the production of a thin steel bar wound in a coil shape. In this method, a thin steel bar rolled to a predetermined diameter of 30 mm or less from a billet is wound into a coil shape in a rolling process, and the wound coil is rewound in a separate line different from the rolling process and straightened, and then a predetermined length is obtained. In the method of manufacturing a fine steel bar, a wrinkle is detected after cutting to a length of 1 mm and then straightening.

  However, in the method disclosed in Patent Document 1, the straightening method for straight steel bars and steel pipes, particularly the straightening method while rotating the material with a multi-roll straightening machine and the straightness to the material end with high accuracy. Since the straightening method to be obtained has not been established, the bending cannot be removed to the end portion of the material, and the end cutting margin is large. For this reason, the ratio of the rolled material to the final product becomes low and the yield deteriorates, leading to a rise in manufacturing cost and a decrease in productivity.

  Thus, generally, the multi-roll straightening machine has 1 stand to 4 stands, which are 1 stand 9, 2 stand 10, 3 stand 11, 4 stand 12, which are composed of opposing concave rolls as shown in FIG. It is a structure that improves the straightness of the material by giving a rolling action in the circumferential direction and a bending action in the longitudinal direction of the material. Each of these rolls has an angle (25 to 35 °) with respect to the material traveling direction, and gives a propulsive force to the material 13 by rotating. Moreover, the multi-roll straightening machine is effective for bending the central portion of the material because of its characteristics, but it is difficult to achieve straightness to the end of the material.

  Further, as shown in FIG. 3, the two-roll straightening machine has a pair of opposed concave rolls 14 and convex rolls 15, and provides a rolling action in the circumferential direction of the material and a bending action in the longitudinal direction of the material. It is a structure that improves straightness. Each roll has an angle (10 to 30 °) with respect to the material traveling direction, and gives a propulsive force to the material 13 by rotating each roll. The two-roll straightening machine is effective for both the bending of the central part of the material and the bending of the end of the material because of its characteristics, but the hot-rolled, cold-rolled or heat-treated material was corrected once with only the two-roll straightening machine. In some cases, it may be necessary to reduce the correction speed in order to maintain straightness, or the required straightness may not be obtained.

JP 11-33619 A

  The present invention was devised in order to solve the problems in the case of manufacturing a conventional seamless steel pipe having an outer diameter of φ15 to 95, and has a high degree of straightness up to the material end, and the end cut. The present invention provides a method for manufacturing a product with high accuracy and good yield by reducing the cost to the minimum necessary.

  In order to solve this problem, the present invention provides a method for producing a seamless steel pipe having an outer diameter of 15 to 95, and uses a material having a bend generated in hot rolling, cold rolling, and heat treatment processes as a multi-roll or two-roll straightening. The straightness of the central part of the material is improved with a machine, and then the straightness of the central part of the material and the straightness of the material end are improved with a two-roll straightening machine. Therefore, the manufacturing method can reduce the cutting allowance.

The gist of the invention is that
(1) In a straight steel pipe straightening method, a multi-roll straightening machine composed of a concave roll and a plurality of opposed or staggered multiple stands, and a two-roll straightening machine composed of a pair of concave-convex rolls or concave-convex rolls The straight steel pipe straightening method is characterized in that the straightening degree is improved to the material end portion with high accuracy and the end cutting allowance is reduced during the cutting process.
(2) The seamless steel pipe according to (1) is a straight steel pipe straightening method characterized by straightening a material after hot rolling, a material after cold rolling, and a material after heat treatment. .

  As described above, according to the present invention, in the method of manufacturing a seamless steel pipe having an outer diameter of φ15 to 95 or less, by improving the straightness to the material end portion, the defective portion of the material end portion is reduced, so that the cutting step It is possible to reduce the edge cutting margin at. When the edge cutting allowance is reduced, the yield is improved and the number of materials to be the final product is increased, thereby producing extremely excellent effects of reducing manufacturing costs and improving productivity.

Hereinafter, the present invention will be described in detail.
The material having the bending that has been conveyed to the straightening process through the hot rolling, cold rolling or heat treatment process is inserted into a multi-roll or two-roll straightening machine to improve the straightness of the central portion of the material. The material after straightening with multiple rolls, which is the first straightening, remains bent at the end, and then transported to a 2-roll straightening machine to improve the straightness of the material center and the straightness of the material edge. To obtain a high degree of straightness. After that, it is transported to a cutting machine to cut off and remove defective parts such as bending of the material end and outside diameter, and chamfering to the end shape required by the user with an end processing machine as necessary. .

Hereinafter, the present invention will be described in detail with reference to examples.
FIG. 1 is a diagram showing a process in a straightening machine according to the present invention. As shown in FIG. 1, the material loaded on the charging table 1 is roughly straightened by a multi-roll straightening machine 2 having 4 stands 7 rolls (roll angle 30 °, concave roll) shown in FIG. The extracted material is conveyed to the 2-roll straightening machine 4 by the connection table 3. In the two-roll straightening machine 4, finishing correction is performed with a pair of concave and convex rolls (roll angles of 15 ° each), and then extracted and conveyed to the cutting machine 6 by the connecting table 5, and defective portions at the ends are cut and removed by 40 mm on both sides. Then, if necessary, the end processing machine 7 chamfers the end shape requested by the user and sends it to the final cradle 8. Multi-roll straightener-2 Roll straightener and two kinds of straightening can achieve straightness of 0.5mm / m to the end of the material, reducing cutting allowance of cutting machine from conventional 100mm to 40mm by 60mm I was able to.

It is a figure which shows the process in the correction machine which concerns on this invention. It is the schematic of a multi-roll straightening machine. It is a schematic diagram of a 2 roll straightening machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Loading table 2 Multi-roll straightening machine 3 Connection table 4 2-roll straightening machine 5 Connection table 6 Cutting machine 7 End processing machine 8 Final cradle 9 1 stand 10 2 stand 11 3 stand 12 4 stand 13 Material 14 Concave roll 15 Convex roll


Patent Applicant Sanyo Special Steel Co., Ltd.
Attorney: Attorney Shiina

Claims (2)

In a straightening method for seamless steel pipes, correction is performed by a multi-roll straightening machine composed of a concave roll and a plurality of opposed or staggered stands, and a two-roll straightening machine composed of a pair of concave-convex rolls or uneven rolls. Thus, the straight steel pipe straightening method is characterized in that the straightness is improved to the material end with high accuracy and the end cutting allowance is reduced during the cutting process. The seamless steel pipe according to claim 1, wherein the material after hot rolling, the material after cold rolling, and the material after heat treatment are straightened.

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