JP2005103597A - Apparatus for detecting inside bead grinding trace of steel tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a apparatus for detecting a inside bead grinding trace of a steel tube capable of highly accurately detecting the position of the inside bead grinding trace when secondary working of the steel tube with the inside bead grinding trace is performed, and correctly determining the position of the inside bead grinding trace in a secondary working apparatus. <P>SOLUTION: The apparatus for detecting a inside bead grinding trace of a steel tube is provided with: a steel tube rotating means to rotate around the axis the steel tube with an inside bead grinding trace longitudinally continuously extending substantially straight; bar-shaped members to be inserted inside the steel tube and an advancing/retracting means therefor: rotary contacts which are mounted on the distal ends of the bar-shaped members separate from each other and brought into contact with a lowest part of the inner surface of the steel tube; a vibration sensor which is disposed between the adjacent rotary contacts and detects the vibration generated in the rotary contacts crossing the inside bead grinding trace by the rotation of the steel tube; and a signal detection means to describe the signals generated by the vibration sensor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an inner surface bead cutting trace detection device for a steel pipe, and particularly detects an inner surface bead cutting trace formed on a seam portion of an ERW steel pipe with high accuracy, and the inner surface bead cutting trace is detected at a desired position by a secondary processing device. Related to the technology to match.

  For example, an electric resistance welded steel pipe is generally formed into a cylindrical shape by a group of forming rolls while rewinding and continuously running a coiled steel strip that is a material, and then both end portions in the width direction of the steel strip that are butted together It is manufactured by welding. For the production, a steel slab obtained by continuously casting molten steel as a raw material is heated to a predetermined temperature (usually 1200 to 1300 ° C.) in a heating furnace, and then coiled to a constant width by hot rolling A steel strip is used. Then, as shown in FIG. 4, the steel strip 8 is fed at a constant speed with the steel strip surface horizontal to a group of forming rolls 9 in which rolls having various shapes are arranged in multiple stages. The tubular body processed by the forming roll 9 and formed into a cylindrical shape (referred to as an open tube because the abutted width direction end portions are unjoined) continues to the abutted width direction both end portions of the induction coil 10. And is pressed with a squeeze roll (not shown), and is crimped and welded to form a steel pipe 11. Since the protrusions formed on the inner and outer surfaces of the joint portion (hereinafter referred to as the seam portion 1) extending substantially linearly continuously in the longitudinal direction of the raw steel pipe 11 are formed, the beads are bead cutting means. 12 is cut off or smoothed by a special rolling mill for rolling the outer surface or the inner surface. Here, a mark obtained by cutting or smoothing such a bead is referred to as an inner surface or outer surface bead cutting mark. Further, the steel tube 11 is reheated in a heating furnace 13, adjusted in dimensions with a multi-stage drawing mill such as a hot stretch reducer or sizer 14, and inspected to have a desired size and characteristics, and then a primary product. It becomes an ERW steel pipe. Further, if the welding method is replaced by welding or pressure welding or forging, a pressure welding steel pipe or a forging steel pipe is obtained.

  Next, the ERW steel pipe as the primary product is cut to a required length by the cutter 15 according to the application, and transported to the next process, for example, subjected to secondary processing such as diameter reduction and bending. However, at that time, the inner surface bead cutting trace needs to be arranged at a fixed position (in the same posture) in the processing apparatus. This is to avoid the occurrence of defects in the secondary product after processing so that the lowest load is applied to the inner surface bead cutting trace during bending.

  By the way, in order to arrange the inner surface bead cutting trace at a fixed position by a secondary processing apparatus, conventionally, (1) the human inner surface bead cutting trace is visually observed or (2) on the outer surface side of the steel pipe. A magnetic sensor, a laser type sensor, or the like is disposed to detect the position of the inner surface bead cutting trace and perform alignment (see Patent Document 1).

However, although the above-mentioned method of observing with eyes can surely align the inner surface bead cutting traces, it requires a dedicated worker, which not only increases labor costs but also reduces productivity. Not right. In addition, the method of detecting the inner surface bead cutting trace by providing a laser sensor or the like on the outer surface side of the steel pipe has a small difference in magnetic properties between the inner surface bead cutting trace and other parts (also referred to as a base material). The detection accuracy of the inner surface bead cutting trace is low, and incorrect positioning may be performed.
Japanese Patent Laid-Open No. 7-60459

  In view of such circumstances, the present invention detects the position of the inner surface bead cutting trace with high accuracy when performing secondary processing on a steel pipe having the inner surface bead cutting trace, It is an object of the present invention to provide an inner surface bead cutting mark detection device for a steel pipe whose position can be accurately determined.

  The inventor has intensively studied to achieve the above object, and the results have been embodied in the present invention.

  That is, the present invention relates to a steel pipe rotating means for rotating a steel pipe having an inner surface bead cutting trace continuously extending in the longitudinal direction around the axis, a rod-shaped member inserted into the steel pipe inner face, and its advance / retreat means. Rotating across the inner surface bead cutting trace by rotation of the steel pipe, which is attached to the tip of the rod-like member at a distance from each other and disposed between the rotating contact contacting the lowest point of the inner surface and the adjacent rotating contact A steel pipe inner surface bead cutting trace detection device comprising a vibration sensor for detecting vibration generated in a contact and signal detection means for indicating a signal generated by the vibration sensor.

  In this case, an E-type eddy current sensor may be used instead of the vibration sensor. Further, the signal detection means receives a signal issued by the vibration sensor, issues a rotation stop command to the rotation means of the steel pipe, and at the time of stopping the steel pipe, detects the position where the detected inner surface bead cutting trace stops. It is preferable to have a function for calculating the angle. Furthermore, it is preferable that the steel pipe is any one of an electric resistance welded steel pipe, a pressure welded steel pipe, and a forged steel pipe.

  ADVANTAGE OF THE INVENTION According to this invention, the position of this inner surface bead cutting trace of the steel pipe which has an inner surface bead cutting trace can be detected now accurately based on the level | step difference or shape change which arises in a steel pipe inner surface. As a result, when the steel pipe is subjected to secondary processing and secondary processing such as bending is performed, the inner surface bead cutting trace can be set at a designated position where the load applied to the secondary processing device is reduced, Defects that occur in the secondary product after processing can be reduced.

  Hereinafter, the best mode for carrying out the present invention will be described based on the circumstances leading to the invention.

  First, the inventor has determined that it is difficult to detect an inner surface bead cutting trace of an electric resistance welded steel pipe, a pressure welded steel pipe, a forged steel pipe, or the like from the outer surface side of the steel pipe or the like based on the shape and magnetic characteristics. He sought an alternative to such means. As a result, the inner surface bead cutting trace generated on the inner surface of the electric resistance welded steel pipe, etc., can be removed by cutting the bead generated at the time of joining with a bite or smoothing by using a special roller, We paid attention to the shape change. In other words, it was thought that the inner surface bead cutting trace could be detected with higher accuracy than before if these steps or shape changes were detected.

  Specifically, as shown in FIG. 1A, an electric resistance welded steel pipe or the like having an inner surface bead cutting trace 1 extending substantially linearly continuously in the longitudinal direction (hereinafter sometimes simply referred to as a steel pipe 2). A steel pipe rotating means (not shown) for rotating around the shaft is provided, and a rod-like member 3 can be inserted into the inner surface of the steel pipe 2 as an advancing / retreating means 4 using, for example, an air cylinder. In addition, as a rotating means of the steel pipe 2, a general turn roller can be used. Further, the rotation speed need not be high.

  A rotating contact 5 is attached to the tip of the rod-like member 3 so as to be in contact with the substantially lowest portion of the inner surface of the steel pipe, being separated from each other by a predetermined distance (for example, about 40 mm). As a result, the steel pipe 2 is rotated around the axis (in the direction of the arrow), and when the inner surface bead cutting trace 1 passes through the lowest point, the rotating contact 5 and the inner surface of the steel pipe near the inner surface bead cutting trace 1 Touch. These rotary contacts 5 generate vibration when crossing the step (not shown) remaining on the inner surface bead cutting trace 1. The reason why the contact is made rotatable is that, if not so, when the steel pipe 2 is rotated, the rod-like member 3 comes into contact with the inner surface of the steel pipe, and a new defect such as “scratch” may occur. Therefore, the frictional resistance is reduced as a countermeasure. The rotary contact 5 is not particularly limited in the present invention, but a ball used in a ball bearing as shown in FIG.

  In the present invention, the vibration generated as described above is detected by providing the vibration sensor 6 between the adjacent rotary contacts 5. That is, the position of the inner surface bead cutting trace 1 of the steel pipe 2 is detected at the lowest position. A commercially available sensor is sufficient as the vibration sensor 6. This detected vibration is converted into an electric signal by a signal detection means (not shown) such as an oscilloscope, and is displayed on the chart as shown in FIG. 2, for example. FIG. 2 shows the results obtained in the two confirmation tests. The peak when the rotating contact contacts the inner surface of the steel pipe (symbol: A) and the peak when the first pass through the step (symbol: B). ) And a peak (symbol: C) appearing at the second step difference. In the present invention, an E-type eddy current sensor 7 for detecting the magnitude of the magnetic flux density as shown in FIG. In this case, instead of detecting the vibration as in the case of the rotary contact 5, a change in the shape of the inner surface bead cutting trace 1 (specifically, surface irregularities or the like) is detected. Since it was confirmed that the result actually tried was the same as that of the vibration sensor 6, it was decided to add to the present invention.

  Next, only the inner surface bead cutting trace detection device for a steel pipe according to the present invention described above can detect the inner surface bead cutting trace 1 of the steel pipe 2 at the lowest position, but in a practical state, the rotation of the steel pipe 2 is stopped. It is necessary to know where the internal bead cutting trace 1 is located. Therefore, the inventor continued to intensively study this.

  First, the stop switch of the rotating means of the steel pipe was turned off in conjunction with the second step passing, and the stop position of the inner surface bead cutting trace was actually investigated. By the way, when 25 experiments were performed with a steel pipe having an outer diameter of 42.7 mmφ, a wall thickness of 2.3 mm, and a length of 500 mm, as shown in FIG. Concentrated at the position of °. The reproducibility was within a range of ± 1.5 mm at the outer peripheral distance and was very stable.

  Therefore, if the actual stop position of the inner surface bead cutting trace 1 after turning off the stop switch of the rotating means of the steel pipe is grasped in advance, the inner surface bead cutting trace detection device for a steel pipe according to the present invention, The position of the inner surface bead cutting trace of the steel pipe can be detected with higher accuracy than before. However, the above-described detection of the actual inner surface bead cutting trace requires manpower for operating the stop switch and the like. Therefore, the inventor has received a signal issued by the vibration sensor to the signal detection means to issue a rotation stop command to the rotation means of the steel pipe, and at the time of stopping the steel pipe, the inventor has detected the inner surface bead cutting. A function for calculating the position where the trace stops by the rotation angle θ of the steel pipe is provided. In order to exert this function, a computer or the like may be used.

  The rotation is stopped after a certain time has elapsed since the switch of the steel pipe rotating means is stopped (the position of the inner surface bead cutting trace is at the lowest position). The rotation speed varies depending on the size (inner diameter, thickness, etc.) of the steel pipe. Therefore, even in such automation, it is necessary to investigate in advance the stop position of the inner surface bead cutting trace in a test operation and store the rotational speed of the steel pipe until the actual stop in the computer.

  In this way, the electric resistance welded steel pipe or the like in which the position of the inner surface bead cutting trace is detected by the apparatus according to the present invention is sent to the next process and subjected to secondary processing. For the transportation, it is preferable to use a robot that holds the steel pipe in a state where the stop position of the inner surface bead cutting trace is fixed and moves the steel pipe to the inner surface bead cutting trace designated position of the secondary processing apparatus as it is.

  A steel pipe inner surface bead cutting trace detection device according to the present invention was provided in the vicinity of the cutting machine of the ERW steel pipe production line shown in FIG. And the position of the inner surface bead cutting trace of the electric-resistance-welded steel pipe made of the steel type STKM having the outer diameter of 42.7 mmφ, the wall thickness of 2.3 mm, and the length of 600 mm manufactured by the production line, and the rotational speed of the steel pipe is 15 rpm. As automatically detected. In addition, in order to compare the effect with this invention, the investigation with the detection apparatus using the magnetic sensor detected from the conventional steel pipe outer surface was also performed similarly (conventional example).

  As a result, the position of the inner surface bead cutting trace was reconfirmed with the naked eye, and the coincidence ratio between them ((the inner surface bead cutting trace position by the apparatus according to the present invention—the inner surface bead cutting trace position by visual observation) / the number of investigations × 100). From Table 1, it is clear that according to the present invention, the detection accuracy is remarkably improved as compared with the conventional apparatus.

It is a figure explaining the inner surface bead cutting trace detection apparatus of the steel pipe concerning the present invention, (a) shows the whole transverse section, (b) shows the front of a rotating contact, and (c) shows an E type eddy current sensor. It is a perspective view. It is a chart which shows the output of a signal detection means. It is a figure which shows the stop position of an inner surface bead cutting trace by rotation angle (theta) of a steel pipe. It is a flowchart which shows the production line of an electric resistance steel pipe.

Explanation of symbols

1 Internal bead cutting trace 2 Steel pipe 3 Bar-shaped member 4 Advancement / retraction means (air cylinder, etc.)
DESCRIPTION OF SYMBOLS 5 Rotating contact 6 Vibration sensor 7 E type eddy current sensor 8 Steel strip 9 Forming roll group 10 Induction coil 11 Raw steel pipe 12 Bead cutting means 13 Reheating furnace 14 Sizer 15 Cutter

Claims (4)

Rotating means for rotating a steel pipe having an inner surface bead cutting trace continuously extending in the longitudinal direction around the axis, a rod-shaped member inserted into the inner surface of the steel pipe, its advancing and retracting means, and a tip of the rod-shaped member A rotating contact that is mounted on the inner surface of the inner surface of the inner surface of the inner surface of the inner surface of the inner surface of the inner surface of the inner surface of the inner surface of the rotating contact. A steel pipe inner surface bead cutting trace detection device, comprising: a vibration sensor for detecting vibration; and a signal detection means for indicating a signal generated by the vibration sensor. 2. An inner surface bead cutting trace detection device for a steel pipe according to claim 1, further comprising an E-type eddy current sensor instead of the vibration sensor according to claim 1. The signal detection means receives a signal issued by the vibration sensor, issues a rotation stop command to the rotation means of the steel pipe, and at the time of stopping the steel pipe, the position where the detected inner surface bead cutting trace stops is determined by the rotation angle of the steel pipe. The apparatus for detecting an inner surface bead cutting trace of a steel pipe according to claim 1 or 2, further comprising a function to calculate. The inner pipe bead cutting trace detection device for a steel pipe according to any one of claims 1 to 3, wherein the steel pipe is any one of an electric-welded steel pipe, a pressure-welded steel pipe, and a forged steel pipe.

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