JP4059239B2 - Method and apparatus for identifying the horizontal joint of a steel pipe during hot operation - Google Patents

Description

  The present invention relates to a method for manufacturing an electric-welded steel pipe or a forged steel pipe and an apparatus therefor, and to a method for manufacturing a steel pipe capable of identifying a transverse joint at a lower cost and an apparatus therefor.

  An electric resistance welded steel pipe or a forged steel pipe is manufactured from a steel strip as a raw material through processes such as heating, pipe making using a forming roll, and adjustment of inner and outer diameters using a drawing mill. Usually, the steel strip is coiled, and the coil has a predetermined length. Although it is possible to perform so-called batch processing that performs processing such as heating and molding for each coil, the productivity is poor, so the coil ends that are the raw materials are welded one after another as an endless steel strip. Each process of the said heating, the pipe manufacturing process by a forming roll, adjustment of the inner and outer diameter by a drawing mill, etc. is performed.

  The steel pipe completed through such a process includes a portion where the coil and the coil are joined by welding, that is, a joint. However, such seams tend to have variations in mechanical strength compared to other parts, and electrochemically unstable, resulting in extremely poor quality. Because there is a possibility, it is necessary to exclude somewhere in the production line.

  As a method for detecting such a seam in a production line, generally, after a steel pipe is cooled, a straightening operation is performed, and an eddy current flaw test is continuously performed for selection. However, it is not desirable for quality control that the seam that is clearly defective flows until just before the inspection process, and it is also disadvantageous in terms of productivity.

As means for rejecting such a joint in the previous step, Patent Document 1 discloses a hot eddy current flaw detector.
Japanese Utility Model Publication No. 2-135857

  However, the hot eddy current flaw detection device disclosed in Patent Document 1 has a problem that the device itself is very expensive and, when actually introduced, requires a lot of equipment cost. In addition, since this apparatus requires a setup change operation for each size of the object to be inspected, there is a problem that it is difficult to apply in the field of steel pipes in which various sizes are manufactured.

  Therefore, the present invention provides a more preferable quality control method by identifying and rejecting a defective seam portion at a faster stage (for example, before passing through a straightening machine) by a cheaper and simpler method, It is an object of the present invention to provide a method and apparatus for manufacturing a steel pipe with improved productivity.

As a result of repeated studies to solve the above-described problems, the present inventor, for example,
(1) After uncoiling the steel strip, the steel strip ends are joined together by flash butt welding or the like, and paint is applied to this joined portion (hereinafter referred to as “seam”).
(2) Before the heating furnace, the part to which this paint is applied is identified from the unpainted part using a laser sensor or the like, and the joint position is detected.
(3) Tracking processing is performed from the position where the seam is detected to the spray marking device arranged on the drawing side of the drawing mill. The tracking processing includes a distance L1 from the position A where the seam is detected by the laser sensor or the like to the drawing mill entry side B, a distance L2 from the drawing mill entry side B to the exit side C, and the drawing mill exit side C. Spray marking after the seam is detected in A above based on the distance L3 to the spray marking device D, the material speed V1 on the entrance B of the drawing mill, and the material speed V2 on the exit C of the drawing mill It pays attention to the time s to reach the device D.
(4) Based on the above tracking process, spray marking is performed at the timing when the joint portion passes through the spray marking device on the drawing mill exit side.
(5) Reject the spray marking part (joint part, that is, welded joint part) in the cooling bed process.
It has been found that the above problems can be solved.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

  The invention according to claim 1 is a method for producing a steel plate by successively welding and joining longitudinal ends of a plurality of steel strips, heating and forming the steel plate, and continuously producing a steel pipe, The marking step of marking the welded joint location of the mark, the marking location is detected in front of the heating furnace (5, 6) (A), and tracking from that position to the drawing mill (8) exit side (C, D), A marking part specifying step for specifying a part that has been marked on the exit side of the drawing mill by the tracking, a step for re-marking the specified marking part, and a re-marked part on the cooling bed or its exit side And a step of rejecting the steel pipe.

  According to a second aspect of the present invention, in the method of manufacturing a steel pipe according to the first aspect, the marking part specifying step for specifying the marked part is performed by a drawing machine that detects the welded joint from the detection position before the heating furnace. It is a step of performing site identification by calculating the time to reach the position for specifying the marking site on the side and after.

  The invention according to claim 3 is a steel pipe manufacturing apparatus comprising a steel strip welding joint machine (2), a welding point marking device (2a), a heating furnace (5, 6), and a drawing mill (8) in this order. The mark detection device (4) for detecting the mark of the steel strip attached by the welding point marking device in front of the heating furnace (5, 6) (A), the material up to the drawing mill entrance side (B) A first speed detecting device (13) for detecting the traveling speed and a second speed detecting device (14) for detecting the material traveling speed after the drawing mill (C) are provided. On the basis of the detection results of the speed detection device and the second speed detection device, a tracking device (12) is provided for identifying the location when the welding location passes through the drawing mill exit side. Remark the identified welds An apparatus for manufacturing a steel pipe, characterized in that it comprises two marking device (9) (100).

  According to the present invention, a defective horizontal joint portion is identified at a faster stage (before passing through a straightening machine) by a cheaper and simpler method, and the seam is rejected, thereby improving the quality control and refining process. The workability of the straightening machine or later can be improved. Such an operation and gain of the present invention will be made clear from the best mode for carrying out the invention described below.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method and apparatus for identifying a steel pipe joint according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a conceptual diagram schematically showing a steel pipe manufacturing apparatus according to the present invention. In the steel pipe manufacturing apparatus 100 shown in the drawing, first, a steel strip is paid out from a coil mounted on the uncoiler 1. When all the steel strips of the coil are paid out, the next coil is mounted on the uncoiler 1, and the rear end of the coil and the front end of the next coil are welded and joined by the transverse joint welding device 2. In this embodiment, flash butt welding is employed.

  During this welding, the feeding of the steel strip from the uncoiler 1 is stopped, but during that time, the amount of material passing is adjusted appropriately by the looper 3 and the continuous operation of the steel pipe manufacturing apparatus 100 is maintained.

  The steel strip that has passed through the looper 3 is heated to a predetermined temperature in the preheating furnace 5 and then in the heating furnace 6, and is continuously (plate-shaped)-(C) by a roll forming machine 7 composed of a plurality of pairs of rolls. (Shape)-transformed into (open tubular). And this open tube is locally heated by the induction heating coil not shown to both edge part to melting | fusing point. The open pipe whose both edge portions are locally heated to the melting point is melt-welded by a squeeze roll (not shown). The molten beads on the inner and outer surfaces are cut and removed with a fixed cutting tool or a rotating tool. After the bead is removed, the rolling is performed by the drawing apparatus 6 and adjusted to a predetermined inner and outer diameter. Then, it cut | disconnects to predetermined length with the rotary hot saw 10, and cools in the cooling floor 11.

  In the steel pipe manufacturing facility 100 described above, the welding joint part of the two coils joined by the transverse joint welder 2 is subjected to paint for identifying the part by the welding part marking device 2a. After the paint application, the joint moves according to the line speed of the manufacturing apparatus 100, and the amount of light reflected by the paint application part and the non-application part differs depending on the laser detector 4 installed before entering the preheating furnace 5. The seam portion is detected by using this fact.

  On the other hand, a first speed detection device 13 that detects the travel speed V1 of the material (steel strip) before the entrance of the heating furnace 6 detects the travel speed V2 of the formed tube material on the exit side of the drawing mill 8. A second speed detection device 14 is provided.

The speed information detected by the first speed detection device 13 and the second speed detection device 14 is sent to a terminal (hereinafter referred to as “tracking device 12”). The tracking device 12 (1) detects the detected speed information,
(2) A distance L1 from the laser detection device 4 (a position marked with “A” in the drawing) to the drawing mill 10 entry side (a position marked with “B” in the drawing),
(3) Distance L2 from the entrance side B of the drawing mill 10 to the exit side (the position marked with “C” in the figure), and
(4) A distance L3 from the drawing side C of the drawing mill 10 to the marking device 9,
Based on the above, the following time (s) required for the welded joint from point A to point D in FIG. 1 is calculated.
s = K1 (L1 / V1) + K2 {2L2 / (V1 + V2)} + K3 (L3 / V2)
Where V1: material speed, V2: pipe speed,
L1: Distance from the laser detection device 4 (the preheating furnace 5 entering side) to the drawing mill 8 entry side L2: Distance from the drawing mill 8 entry side to the exit side L3: From the drawing mill 8 exit side to the marking device 9 Distances K1, K2, and K3: correction coefficients.

  In the above description, the speeds V1 and V2 are calculated from the number of rotations using a measuring roll, but K1 and K3 are provided as correction coefficients in order to correct the degree of wear of the roll diameter. The drawing mill 8 is narrowed down by a large number of stands, but even if the simulated value of each stand is used, it is necessary to consider slip between the stands. It was.

  After the seam is detected by the laser detection device 4 and the time s calculated by the tracking device 12 has elapsed, a white paint that can be identified with heat from the spray marking device 9 installed on the exit side of the drawing mill 8 is obtained. Apply.

  The spray marking device 9 clearly applies to the pipe that has been drawn and drawn at high speed, so that it can be clearly identified even in the subsequent cooling bed process, so that it can be applied twice more in two locations in the circumferential direction of the pipe. Four spray nozzles 15a to 15d are arranged (see FIG. 2). Spray time is arbitrarily set by an external timer.

  The spray marking device 9 can be moved up and down, moved forward and backward from the line by a hydraulic or pneumatic cylinder 18, and the number of spray nozzles to be used can be selected according to the size of the steel pipe and the material speed. I have to. Spray marking is performed on the seam, and after elapse of a preset time (for example, after 5 seconds), the joint is raised and retracted from the pipe conveyance line. In addition, at the timing when the laser detection device 4 detects the next seam, it moves forward and down again and performs marking.

Furthermore, the present invention will be described more specifically with reference to examples.
For example, when a 15A steel pipe is manufactured, the coil to be used is uncoiled and the end faces of the strip steel are flash-butt welded. After flash butt welding, white paint is applied to this part by lacquer spray or the like. Thereafter, the joint portion passes through the looper and passes through the laser sensor on the heating furnace entrance side. The laser sensor is installed from a steel strip, for example, with a height of 300 mm and an angle of 30 °, and emits light having a wavelength of 650 nm. The transmitted light is reflected from the steel strip and received by the laser detector. At this time, the ratio of the attendance level of the belt steel normal part and the light reception level of the white paint application part is confirmed in advance (for example, 1: 2), and a threshold is set (for example, 1.5 times that of the non-application part). . When the transverse part passes through the laser detection device, the amount of light received exceeds the threshold value and recognized as a transverse part. In addition, when the outer peripheral surface of the steel strip has rust, the amount of light received changes. However, by detecting the joint, an off-delay timer is provided to prevent erroneous detection of this part.

  The detected information is sent to a tracking device that is a terminal for tracking. The tracking device has a distance L1 from the laser detection device to the entrance side of the drawing mill, a distance L2 from the entrance side of the drawing mill to the exit side, and The distance L3 (for example, 8 m) from the drawing side of the drawing mill to the spray marking device, the speed V1 (for example, 60 mpm) to the drawing side of the drawing machine, and the speed V2 (for example, 350 mpm) on the drawing side of the drawing mill After the laser detection, the time (s) until spray spraying is calculated.

  When the seam is detected, the spray marking device on the exit side of the drawing mill advances to the pipe conveyance line, and the spray height set in advance (position where the distance between the pipe surface and the tip of the spray nozzle becomes 35 mm, for example: fine adjustment handle in advance Until it is adjusted with the cylinder). After descending, the seam is detected by the laser, and spraying is performed on the pipe surface at the timing when the time required to reach the marking device has elapsed. The selection of the nozzle is 15A. For example, when the pipe speed is 350 mpm, there are four nozzles and the spraying time is 0.5 seconds. When the spraying is completed, the marking device is lifted, retreated, and waits until the next seam is detected.

  In the steel pipe manufacturing apparatus according to the present example, a water-soluble paint having excellent heat resistance (for example, SEP-60N manufactured by Tainet Corporation) was used as the paint.

  The seam with the spray marking could be clearly identified in the cooling bed process, allowing it to be taken offline and rejected before passing through the straightener.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, the present invention can be modified as appropriate without departing from the scope or spirit of the invention that can be read from the claims and the entire specification, and a method and apparatus for manufacturing a steel pipe with such changes are also within the technical scope of the present invention. It must be understood as included.

It is a conceptual diagram which shows the manufacturing apparatus of a steel pipe. It is a figure which shows the nozzle arrangement | sequence of a spray marking apparatus.

Explanation of symbols

1 Uncoiler 2 Transverse welder (welding machine)
2a Welding point marking device 3 Looper 4 Laser detector (mark detector)
5 Preheating furnace (heating furnace)
6 Heating furnace 7 Roll forming machine 8 Drawing mill 9 Spray marking device (marking device, second marking device)
DESCRIPTION OF SYMBOLS 10 Rotary hot saw 11 Cooling bed 12 Tracking apparatus 13 1st speed detection apparatus 14 2nd speed detection apparatus 15, 15a-d Spray nozzle 16 Conveyance roller 17 Pipe 18 Hydraulic (pneumatic) cylinder 100 Steel pipe manufacturing apparatus

Claims (3)

A method of producing a steel plate by sequentially welding and joining longitudinal end portions of a plurality of steel strips, heating and forming the steel plate, and continuously producing a steel pipe,
A marking step for marking the welded joint of the original plate;
The marking part is detected in front of the heating furnace, the tracking is performed from the position to the drawing mill exit side, and the marking part specifying step for identifying the marked part on the drawing mill exit side by the tracking,
Re-marking the identified marking site;
Rejecting the re-marked site on the cooling bed or its exit side;
A method of manufacturing a steel pipe, comprising: The marking part specifying step for specifying the marked part calculates the time until the welded joint part reaches the position for specifying the marking part after the drawing side of the drawing mill from the detection position before the heating furnace. And the manufacturing method of the steel pipe of Claim 1 which is a process of performing site | part identification. A steel pipe manufacturing apparatus equipped with a steel band welding machine, a welding point marking device, a heating furnace, and a drawing mill in this order,
A mark detection device that detects the mark of the steel strip attached by the welding location marking device before the heating furnace, a first speed detection device that detects a traveling speed of the material up to the entrance to the drawing mill, and the drawing A second speed detection device that detects the material traveling speed after the rolling mill exit side is provided, and based on the detection results of these mark detection device, first speed detection device, and second speed detection device, the welding location is A tracking device that identifies the part when passing through the drawing side of the drawing mill,
Furthermore, the manufacturing apparatus of the steel pipe characterized by including the 2nd marking apparatus which attaches a mark again to the said welding location specified with the said tracking apparatus.

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