METHOD AND DEVICE FOR MEASURING THE INTERNAL SHAPE OF ELECTRIC WELDED STEEL PIPE, AND MANUFACTURING METHOD AND MANUFACTURING FACILITY FOR ELECTRIC WELDED STEEL PIPE

Abstract

To provide a method and a device for measuring an inner surface shape of an electro-resistance-welded steel pipe that can measure an inner surface shape of an electro-resistance-welded steel pipe easily and with sufficient accuracy during a forming process before welding, as well as a method and a facility for manufacturing an electro-resistance-welded steel pipe using the same.SOLUTION: A method for measuring an inner surface shape of an electro-resistance-welded steel pipe is used to measure an inner surface shape of an electro-resistance-welded steel pipe when a steel plate is formed and ends are welded to manufacture the electro-resistance-welded steel pipe. The method comprises the steps of: inserting a distance measuring unit including a non-contact distance meter into the electro-resistance-welded steel pipe from an unwelded part of the electro-resistance-welded steel pipe being manufactured; measuring, by the distance measuring unit, a distance of the inner surface of the electro-resistance-welded steel pipe in a circumferential direction; and calculating, on the basis of the measurement, a circumferential shape of the inner surface as the inner surface shape of the electro-resistance-welded steel pipe.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method and device for measuring the inner shape of an electric resistance welded steel pipe, and a method and equipment for manufacturing an electric resistance welded steel pipe. [Background technology]

[0002] In the steelmaking process, electric resistance welded steel pipe manufacturing line, the raw material, hot-rolled steel strip, is continuously bent in the width direction using multiple roll stands, and Joule heat is generated by passing a large high-frequency current through both ends of the steel strip, melting the ends. Almost simultaneously with the melting, the steel strip is passed through a diameter-reducing roll to perform butt welding of the steel strip, thereby continuously manufacturing steel pipes.

[0003] The forming of electric resistance welded steel pipes is mainly carried out by a breakdown stand, which roughly forms a flat blank into a semicircular shape, and a fin pass stand, which performs finish forming up to a C shape, but during this process, the base steel plate is subjected to additional deformations such as bending and unbending deformations in the longitudinal direction each time it passes through the rolls, and stretching and shrinking deformations in the longitudinal and width directions due to the fact that each part of the blank follows a different spatial trajectory as it is formed. For this reason, the blank is not deformed uniformly in the width direction, and the amount of these deformations is determined by the dimensions, shape, and spatial arrangement of the rolls, i.e., the form of constraint applied to the blank during forming.

[0004] The additional deformation as described above causes various welding defects and shape defects by hindering the conformity of the blank sheet to the rolls during widthwise bending deformation to form the desired product cross section and by suppressing or promoting elastic recovery after bending deformation.

[0005] In order to reduce the effects of such additional deformation, it is effective to optimize the transition of the blank shape formed by forming rolls called roll flowers and to deform the blank smoothly.One method for doing so is the cage roll forming method, in which a large number of small diameter rolls called cage rolls are placed in the process from breakdown forming to fin pass forming to restrict the three-dimensional deformed curved surface of the blank to a desirable shape, aiming to guide the blank flow along a smooth trajectory to the fin pass stand.

[0006] By adopting this cage roll forming method and optimizing the dimensions, shape, and spatial arrangement of the rolls, an ideal roll flower can be designed, and the designed ideal roll flower can be compared with the roll flower during the production of electric resistance welded steel pipe. By adjusting the rolls so that the roll flower during production has an ideal shape, it is possible to achieve ideal forming while reducing the effects of additional deformation.

[0007] Thus, to compare the roll flower produced during the manufacture of electric resistance welded steel pipes with the ideal roll flower, information on the circumferential shape of the electric resistance welded steel pipe is required. As a means of obtaining information on the circumferential shape of the electric resistance welded steel pipes, workers have traditionally used diameter tapes or calipers to manually measure the pipe circumference, the outer diameter in the vertical and horizontal directions, and the seam opening length, but there are limitations on the frequency of measurement and the time required for industrial production. For this reason, various methods have been proposed for automatically measuring the outer diameter, etc. of steel pipes.

[0008] For example, Patent Document 1 proposes a method for measuring the outer diameter of a large-diameter pipe from its outer surface using a measuring instrument consisting of a projector attached to the outer surface of the large-diameter pipe and a receiver arranged opposite the projector. Specifically, the technology of Patent Document 1 involves attaching a first outer diameter measuring instrument located on an extension of the tangent of the outer circumference of the pipe and a second outer diameter measuring instrument located on an extension of a tangent parallel to the tangent on which the first outer diameter measuring instrument is located to a base material through which a pipe arranged so that its axial direction is horizontal is inserted, and measuring the outer diameter over the entire circumference of the pipe by rotating the base material to which the first and second outer diameter measuring instruments are attached by at least 90° in the circumferential direction of the large-diameter pipe.

[0009] Patent document 2 also proposes a technology in which a first outer and inner laser rangefinder for measuring outer diameter and wall thickness is arranged on a first line, a second outer laser rangefinder for alignment is arranged on a second line perpendicular to the first line, and these are arranged concentrically, and supported by a frame, and the frame is used by a frame rotation means, a frame movement means, and a forward / backward movement means to enable concentric rotation of all the laser rangefinders and movement in the direction of the second line and in the direction perpendicular to the concentric circle.

[0010] Furthermore, Patent Document 3 proposes a method for performing an automated tube forming press using an apparatus in which at least one light source and receiver for measuring the inner contour of a slit tube or primary tube product is coupled to at least one inner deformation processing tool.

[0011] Furthermore, Patent Document 4 proposes a technology for checking the shape of a metal plate in the middle of forming, using a welded pipe manufacturing apparatus that has a bending means for bending a metal plate, a light emitting means for irradiating the inner surface of the curved metal plate with directional light, an imaging means for imaging the light reflected by the metal plate after being irradiated by the light emitting means, and an adjustment support means for supporting adjustment of the bending means in accordance with the shape of the reflected light. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2010-71778 A [Patent Document 2] JP 2011-7587 A [Patent Document 3] Special Publication No. 2014-508042 [Patent Document 4] JP 2018-83207 A Summary of the Invention [Problem to be solved by the invention]

[0013] In order to measure the outer diameter over the entire circumference using the method proposed in Patent Document 1, it is necessary to rotate the base material to which the outer diameter measuring device is attached by at least 90 degrees, and it is necessary to install a large base material into which the pipe to be measured can be inserted and which has a rotation drive mechanism. Therefore, there is a problem that the locations where a large device like that in Patent Document 1 can be used are limited in the forming process before welding of the seam part, where forming stands are arranged continuously.

[0014] In addition, the method proposed in Patent Document 2 requires a frame with a rotating function and a laser distance meter to be placed opposite one end of the pipe in the axial direction of the pipe to be measured, so its use is limited to pipes after they have been cut, and there is a problem that it is not possible to measure during the forming process prior to welding of the seam portion where forming stands are arranged continuously.

[0015] In addition, in the device proposed in Patent Document 3, at least one of the mechanisms for measuring the inner contour of the object to be measured, that is, the slit pipe or primary pipe product, is coupled to at least one inner deformation processing tool, so that the location where the inner contour can be measured is limited to the location where the inner deformation processing tool is installed. Also, since at least one of the mechanisms for measuring the inner contour of the slit pipe or primary pipe product and the object to be measured are in contact with each other via at least one inner deformation processing tool, they are susceptible to disturbances such as vibrations, and it is considered that the measurement accuracy will decrease.

[0016] Furthermore, Patent Document 4 is limited to a method for checking the shape of a metal plate during forming, and does not propose a specific method for quantifying the captured shape or for assisting in adjusting the bending means.

[0017] Therefore, the present invention provides an inner surface shape measurement method and device for electric-resistance welded steel pipe, which can measure the inner surface shape of electric-resistance welded steel pipe during the forming process before welding easily and with sufficient accuracy, as well as a manufacturing method and manufacturing equipment for electric-resistance welded steel pipe using the same. [Means for solving the problem]

[0018] In order to solve the above problems, the present invention provides the following means [1] to

[14] .

[0019] [1] A method for measuring the inner shape of an electric-resistance welded steel pipe, which is produced by forming a steel plate and welding an end of the electric-resistance welded steel pipe, comprising the steps of: A method for measuring the inner surface shape of an electric-welded steel pipe, comprising inserting a distance measuring unit having a non-contact distance meter into the electric-welded steel pipe from an unwelded portion of the electric-welded steel pipe during manufacture, measuring the distance of the inner surface of the electric-welded steel pipe in the circumferential direction using the distance measuring unit, and calculating the circumferential shape of the inner surface as the inner surface shape of the electric-welded steel pipe based on the result.

[0020] [2] The method for measuring the inner shape of an electric-resistance welded steel pipe described in [1], wherein the distance meter is a laser distance meter.

[0021] [3] The method for measuring the inner surface shape of an electric-welded steel pipe described in [1] or [2], wherein the distance measuring unit measures the distance on the inner surface of the electric-welded welded steel pipe in the circumferential direction by measuring the distance while rotating the distance meter.

[0022] [4] A method for measuring the inner surface shape of an electric-welded steel pipe described in [3], in which the circumferential shape of the inner surface of the electric-welded welded steel pipe is calculated by continuously measuring the distance measured by the distance meter and the rotation angle of the distance meter due to the rotation of the distance meter.

[0023] [5] A method for measuring the inner surface shape of an electric-welded steel pipe described in [1] or [2], wherein the distance measuring unit includes a plurality of distance meters arranged in the circumferential direction of the inner surface of the electric-welded steel pipe.

[0024] [6] An apparatus for measuring the inner shape of an electric-resistance welded steel pipe, which is used to manufacture an electric-resistance welded steel pipe by forming a steel plate and welding an end of the pipe, comprising: a distance measuring unit having a non-contact distance meter that is inserted into the electric resistance welded steel pipe from an unwelded portion of the electric resistance welded steel pipe during production; An electric-resistance welded steel pipe inner surface shape measuring device, which uses the distance measuring unit to measure the distance of the inner surface of the electric-resistance welded steel pipe in the circumferential direction, and based on that, measures the circumferential shape of the inner surface as the inner surface shape of the electric-resistance welded steel pipe.

[0025] [7] The inner surface shape measuring device for electric resistance welded steel pipes described in [6], wherein the distance meter is a laser distance meter.

[0026] [8] The distance measuring unit has the distance meter and a rotation mechanism for rotating the distance meter in a circumferential direction of the electric welded steel pipe, and measures the distance on the inner surface of the electric welded steel pipe in the circumferential direction by measuring the distance while rotating the distance meter. This is the inner surface shape measuring device for electric welded steel pipe described in [6] or [7].

[0027] [9] An inner surface shape measuring device for electric welded steel pipes as described in [8], further comprising a calculation unit that calculates the circumferential shape of the inner surface of the electric welded steel pipe by continuously measuring the distance measured by the distance meter and the rotation angle of the distance meter by rotating the distance meter.

[0028]

[10] The distance measuring unit is an apparatus for measuring the inner surface shape of an electric-welded steel pipe described in [6] or [7], in which a plurality of distance meters are arranged in the circumferential direction of the inner surface of the electric-welded steel pipe.

[0029]

[11] A method for producing an electric-resistance welded steel pipe, comprising the steps of: A process of continuously bending a steel sheet in the width direction using a pipe-making system having multiple roll stands; a step of welding both ends of the steel plate formed by the bending; a step of inserting a distance measuring unit having a non-contact distance meter into the electric-resistance welded steel pipe from an unwelded portion of the electric-resistance welded steel pipe during manufacture, and measuring a distance of an inner surface of the electric-resistance welded steel pipe in a circumferential direction by the distance measuring unit; A step of calculating a circumferential shape of an inner surface as an inner surface shape of the electric resistance welded steel pipe based on the calculated shape; controlling an actuator of the pipe-making system so that the inner circumferential shape of the electric resistance welded steel pipe becomes a desired shape; The method for producing an electric resistance welded steel pipe comprising the steps of:

[0030]

[12] The calculating step includes setting a plurality of feature points at arbitrarily selected positions of an ideal profile, which is a pre-stored ideal circumferential inner surface shape profile of the electric resistance welded steel pipe, and calculating a control value by comparing the feature points with corresponding feature points of an actual measured profile, which is an actual measured circumferential inner surface shape profile of the electric resistance welded steel pipe; The method for manufacturing an electric-resistance welded steel pipe described in

[11] , wherein the controlling step controls an actuator of the pipe-making system based on the control value.

[0031]

[13] An electric-resistance welded steel pipe manufacturing facility for producing electric-resistance welded steel pipes, A pipe-making system having multiple roll stands that continuously bend the steel plate material in the width direction; An actuator that drives the pipe-making system; a welding means for welding both ends of the steel plate formed by the bending; a distance measuring unit having a non-contact distance meter that is inserted from an unwelded portion of the electric-resistance welded steel pipe during manufacture into the electric-resistance welded steel pipe and measures the distance in a circumferential direction from an inner surface of the electric-resistance welded steel pipe; a calculation device that calculates a circumferential shape of an inner surface as an inner surface shape of the electric resistance welded steel pipe based on the distance of the inner surface measured in the circumferential direction by the distance measuring unit; a control device that controls an actuator of the pipe-making system so that the inner circumferential shape of the electric resistance welded steel pipe becomes a desired shape; The electric resistance welded steel pipe manufacturing facility has the following features:

[0032]

[14] The calculation device prestores an ideal profile, which is an ideal circumferential inner surface shape profile of the electric resistance welded steel pipe, sets a plurality of feature points at arbitrarily selected positions of the ideal profile, and calculates a control value by comparing the feature points with corresponding feature points of an actual measured profile, which is an actual circumferential inner surface shape profile of the electric resistance welded steel pipe, The control device controls the actuator of the pipe making system based on the control value. Effect of the Invention

[0033] According to the present invention, the inner surface shape of an electric resistance welded steel pipe in the forming process prior to welding can be measured easily and with sufficient accuracy. [Brief description of the drawings]

[0034] [Figure 1] 1 is a side view showing an example of an inner surface shape measuring device for measuring the circumferential shape of the inner surface of an electric resistance welded steel pipe. [Diagram 2] 1 is a front view showing an example of an inner surface shape measuring device for measuring the circumferential shape of the inner surface of an electric resistance welded steel pipe. [Diagram 3] 1 is a cross-sectional view showing a state in which the inner surface shape of an electric resistance welded steel pipe in the circumferential direction is measured by an inner surface shape measuring device. [Figure 4] 1 is a diagram showing an example of a pipe inner surface shape profile in the circumferential direction obtained by continuously measuring the rotation angle θ of a range finder and the distance L to the pipe inner surface in the circumferential direction. FIG. [Diagram 5] 1 is a diagram for explaining the overlapping of an ideal profile M and an actually measured profile N. FIG. [Figure 6] 1 is a diagram for explaining a method of comparing feature points of an ideal profile M and an actual measurement profile N. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In one embodiment, in a production line for electric resistance welded steel plates, a distance measuring unit is inserted into an electric resistance welded steel pipe from an unwelded portion (open seam portion) of the electric resistance welded steel pipe being manufactured, and the distance of the inner surface of the electric resistance welded steel pipe is measured in the circumferential direction by the distance measuring unit. In the following description, the term "electric resistance welded steel pipe" also includes an electric resistance welded steel pipe in an unwelded state after pipe manufacturing.

[0036] Specifically, electric resistance welded steel pipes are basically continuously manufactured by continuously bending a hot-rolled steel strip (material) in the width direction using a multi-stage roll stand, passing a large high-frequency current through both ends of the steel strip to generate Joule heat and melt the ends, and almost simultaneously with the melting, passing the steel strip through a diameter-reducing roll to butt-weld (weld) the steel strip.

[0037] At this time, it is necessary to measure the inner shape of the electric-welded steel pipe in order to control the roll flower of the electric-welded steel pipe actually being manufactured to the desired shape, preferably to control it so that it approaches the ideal roll flower in the design.

[0038] To achieve this, in this embodiment, as described above, a distance measuring unit is inserted into the electric-resistance welded steel pipe from the unwelded portion (open seam portion), and the distance measuring unit measures the distance of the inner surface of the electric-resistance welded steel pipe in the circumferential direction to grasp the circumferential shape of the inner surface as the inner surface shape of the electric-resistance welded steel pipe.

[0039] Fig. 1 is a side view showing an example of an inner surface shape measuring device for measuring the circumferential shape of the inner surface of an electric resistance welded steel pipe, and Fig. 2 is a front view thereof. As shown in these figures, the inner surface shape measuring device 100 has a distance measurement unit 1, a position adjustment mechanism 2, and an inner surface shape calculation device 3.

[0040] The distance measuring unit 1 is inserted into the inner surface of the electric-resistance welded steel pipe 10 to measure the distance on the inner surface in the circumferential direction, and is inserted from the unwelded portion 10a of the electric-resistance welded steel pipe 10 into the inside of the electric-resistance welded steel pipe 10. Note that Fig. 1 and Fig. 2 show the state in which the distance measuring unit 1 is inserted into the inside of the electric-resistance welded steel pipe 10.

[0041] The distance measurement unit 1 has a distance meter 11, a rotation mechanism 12 that rotates the distance meter 11, and a rotation detector 17. The distance meter 11 measures the distance to the object to be measured without contacting it, and is typically a laser distance meter. The rotation mechanism 12 is composed of a rotating head 13, a gear motor 14, a reducer 15, a first shaft 16a, and a second shaft 16b. The distance meter 11 is attached to the rotating head 13. The first shaft 16a connects the reducer 15 and the gear motor 14 via a coupling, and the second shaft 16b connects the rotating head 13 and the reducer 15 via a coupling. The first shaft 16a and the second shaft 16b extend in the longitudinal direction of the electric resistance welded steel pipe 10, and the rotation of the gear motor 14 is transmitted to the rotating head 13 by the first shaft 16a, the reducer 15, and the second shaft 16b. Therefore, the rotation mechanism 12 is configured to rotate the distance meter 11 attached to the rotating head 13 360° in the circumferential direction of the electric resistance welded steel pipe 10. The rotation detector 17 detects the rotation of the rotation mechanism 12 and is composed of a photoelectric rotation detection sensor 18 and a reflective mark 19.

[0042] The position adjustment mechanism 2 holds the distance measurement unit 1 and adjusts its position. The position adjustment mechanism 2 has a support member 21 that supports the distance measurement unit 1, and adjusts the position of the distance measurement unit 1 via the support member 21. The position adjustment mechanism 2 holds the distance measurement unit 1 within the electric resistance welded steel pipe 10 and adjusts the position of the distance measurement unit 1 within the electric resistance welded steel pipe 10. The position adjustment mechanism 2 also makes it possible to move the distance measurement unit 1 in and out of the electric resistance welded steel pipe 10 via the unwelded portion 10a. The position adjustment mechanism 2 may be automated by combining an actuator such as a cylinder or a motor with a simple automatic control system. It is preferable to attach the position adjustment mechanism 2 to the forming stand housing near the measurement location.

[0043] The inner surface shape calculation device 3 calculates the circumferential shape of the inner surface as the inner surface shape of the inner surface of the electric resistance welded steel pipe 10 (hereinafter sometimes simply referred to as the "pipe inner surface") based on the inner surface distance measured in the circumferential direction of the electric resistance welded steel pipe by the distance measurement unit 1. Specifically, the measurement values ​​of the distance meter 11 and the photoelectric rotation detection sensor 18 in the rotation detector 17 are input, and the pipe inner surface shape profile in the circumferential direction is calculated based on these.

[0044] The inner surface shape calculation device 3 receives input of the outer diameter specifications of the electric resistance welded steel pipe 10 to be measured from a higher-level control device such as a process computer. In addition, an ideal pipe inner surface shape profile M in the circumferential direction for each outer diameter specification may be stored in advance. In this case, a plurality of characteristic points may be set at arbitrarily selected positions of the ideal pipe inner surface shape profile M, and the control value may be calculated by comparing the characteristic points with the corresponding characteristic points of the actually measured pipe inner surface shape profile.

[0045] The control values ​​derived from the calculation results of the inner surface shape calculation device 3 are input to the pipe manufacturing system control device 4, which controls various actuators such as cylinders and motors of the pipe manufacturing system located upstream of the distance meter 11 of the manufacturing equipment so that the circumferential pipe inner surface shape of the electric welded steel pipe 10 becomes the desired shape.

[0046] Next, a method for measuring the inner surface shape of the electric resistance welded steel pipe 10 using the above-described inner surface shape measuring device 100 will be described.

[0047] FIG. 3 is a cross-sectional view showing a state in which the inner surface shape of an electric resistance welded steel pipe 10 in the circumferential direction is being measured by the inner surface shape measuring device 100. As shown in FIG.

[0048] 3, the distance measurement unit 1 of the inner surface shape measuring device 100 is inserted from above the electric resistance welded steel pipe 10 into the inside of the electric resistance welded steel pipe 10 after pipe making, via the unwelded portion (open seam portion) 10a, by the position adjustment mechanism 2. When the position adjustment mechanism 2 is to be automatically adjusted, the motor, cylinder, etc. provided in the position adjustment mechanism 2 are driven in accordance with the outer diameter specifications inputted to the inner surface shape calculation device 3 to raise and lower the device in the vertical direction.

[0049] After the distance measurement unit 1 has been completely set in the electric-resistance welded steel pipe 10, a command to start measurement is given from a higher-level control device, causing the rotation mechanism 12 to rotate the distance meter 11, and causing the photoelectric rotation detection sensor 18 to start measuring the number of rotations and the distance to the electric-resistance welded steel pipe 10 by the distance meter 11. The rotation mechanism 12 causes the distance meter 11 to rotate 360° in the circumferential direction of the electric-resistance welded steel pipe 10, and when the distance meter 11 returns to its initial position, the rotation by the rotation mechanism 12, the distance measurement by the distance meter 11, and the rotation number measurement by the photoelectric rotation detection sensor 18 are terminated.

[0050] When the range finder 11 is a laser range finder, the semiconductor laser of the laser range finder irradiates the measured part on the inner surface of the tube with laser light, the reflected light is collected by a light receiving lens, and the distance L to the measured part is measured from the amount of change in the image position on the light receiving element when the image is formed on the light receiving element. When the range finder 11 is rotated in the circumferential direction by the rotation mechanism 12, the range finder 11 continuously measures the distance L in the circumferential direction.

[0051] Furthermore, when the range finder 11 is rotated in the circumferential direction by the rotation mechanism 12, the rotation detector 17 measures the number of rotations of the first shaft 16a connecting the reducer 15 and the gear motor 14. The number of rotations is converted into the rotation angle of the second shaft 16b connecting the rotary head 13 and the reducer 15, i.e., the rotation angle θ of the range finder 11 attached to the rotary head 13, based on the reduction ratio of the reducer 15 previously set in the inner surface shape calculation device 3 and the elapsed time t from the start of measurement, and this rotation angle θ is continuously measured.

[0052] In this way, by rotating the range finder 11 in the circumferential direction by the rotation mechanism 12, the distance L to the inner surface of the pipe and the rotation angle θ of the range finder 11 can be continuously measured. In FIG. 3, the rotation angle of the range finder 11 is θ 1 , θ 2 When the distance to the inner surface of the pipe measured by the distance meter 11 is L, 1 , L 2 This shows that.

[0053] The inner surface shape calculation device 3 calculates a circumferential pipe inner surface shape profile based on the continuously measured distance L to the pipe inner surface and the rotation angle θ of the range finder 11. Fig. 4 is a diagram showing an example of a circumferential pipe inner surface shape profile obtained by continuously measuring the rotation angle θ of the range finder and the distance L to the pipe inner surface in the circumferential direction. In Fig. 4, the circumferential pipe inner surface shape profile is displayed on a coordinate system with the rotation angle θ on the horizontal axis and the distance L on the vertical axis.

[0054] In order to improve the measurement accuracy, it is effective to increase the measurement time t and increase the measurement values ​​of the rotation angle θ and the distance L to the inner surface of the pipe as much as possible, and to do this, it is desirable to increase the reduction ratio of the reducer 15.

[0055] In the inner surface shape calculation device 3, when an ideal pipe inner surface shape profile M in the circumferential direction for each outer diameter specification is stored in advance, a plurality of feature points are set at arbitrarily selected positions of the ideal pipe inner surface shape profile M, and the feature points are compared with the corresponding feature points of the actually measured pipe inner surface shape profile to calculate a control value.

[0056] Fig. 5 is a diagram for explaining the superposition of a profile M of an ideal pipe inner surface shape in the circumferential direction (ideal profile M) and a profile N of a pipe inner surface shape (actually measured profile N) obtained by actually measuring the inner surface of an electric resistance welded steel pipe 10 in the circumferential direction. In Fig. 5, the ideal profile M and the actually measured profile N are actually superimposed, but it is also possible to superimpose profiles on a coordinate system in which the horizontal axis represents the rotation angle θ and the vertical axis represents the distance L to the pipe inner surface, as shown in Fig. 4.

[0057] FIG. 5 shows the case of a mill in which the bottom pass line of the forming stand is predetermined for each size, and the ideal profile M and the measured profile N are superimposed so that the points on the bottom surfaces of the profiles coincide. The center point O' of the measured profile N is located on the normal line between point B' on the bottom surface of the profile and the measured profile, at a point O'B' away from the point on the bottom surface. The distance O'B' between center point O' of the measured profile N and point B' on the bottom surface is calculated by the radius of rotation r of the distance meter 11 and the measurement value of the distance meter 11 at the bottom surface point, i.e., the distance L between the distance meter 11 and the bottom surface of the pipe, as shown in the following equation (1). B’ It can be found by the sum of: Distance O'B'=r+L B’ (1) In the case of mills where the height of the bottom roll is predetermined for each size, it is assumed that the ideal and actual distances from the point on the bottom surface of the profile to the center point are equal, and the center point O of the ideal profile M is located on the normal line to point B on the bottom surface of the profile and the ideal profile, at a distance O'B' from the point on the bottom surface, and the subsequent overlay and calculations are performed.

[0058] Next, the feature points of the ideal profile M, whose center point has been determined by the above procedure, are compared with those of the measured profile N. Fig. 6 is a diagram for explaining the method of comparing the feature points at this time. In order to calculate the roll adjustment amount, the inner surface shape calculation device 3 has a feature point at which the ideal profile M and the measured profile N are compared, for example, feature point B of the breakdown No. 1 stand top roll. 1T (See Figure 6) Breakdown No. 1 stand bottom roll feature point B 1B A plurality of such characteristic points are set in advance, and an arithmetic expression for calculating the amount of roll adjustment is set in advance for each characteristic point.

[0059] For example, as shown in Fig. 6, the distance from the center point O of the ideal profile M to point B, which is set as a characteristic point of the roll on the breakdown stand No. 1, is 1T Distance to L B1T From the center point O of the measured profile N, the characteristic point B of the roll on the breakdown stand No. 1 1T Distance to LB1T ', the roll adjustment amount is calculated using the following equation (2). Roll adjustment amount = α × (L B1T '-L B1T )+β (2) The coefficients α and β must be set in advance. For example, the difference L between the two profiles for some outer diameter specifications is B1T '-L B1T One method is to experimentally determine the relationship between the roll adjustment amount and the outer diameter specification to be measured, and then extrapolate the results to the entire outer diameter specification.

[0060] The calculated values ​​calculated by the inner surface shape calculation device 3 are input to the pipe-making system control device 4. Based on such control values, the pipe-making system control device 4 controls actuators such as cylinders, motors, etc. of various pipe-making systems located upstream of the distance meter 11 of the manufacturing equipment. For example, the roll adjustment amount obtained by the above formula (2) is input to the pipe-making system control device 4 as a control value, and the pipe-making system control device 4 controls actuators such as cylinders, motors, etc. of various pipe-making systems located upstream of the distance meter 11 based on such control values.

[0061] As described above, in this embodiment, the distance measurement unit 1 constituting the distance measurement device 100 is inserted into the electric resistance welded steel pipe 10 from the unwelded portion (open seam portion) 10a of the electric resistance welded steel pipe 10 being manufactured, and the distance of the inner surface of the electric resistance welded steel pipe 10 in the circumferential direction is measured by the distance meter 11 of the distance measurement unit 1. Therefore, the pipe inner surface shape profile in the circumferential direction during the forming process before seam welding can be measured easily and with sufficient accuracy without cutting the pipe. In addition, there is no limit to the measurement frequency, and measurements can be made with sufficient frequency.

[0062] Then, using the information on the circumferential pipe inner surface shape profile measured with sufficient accuracy in this way, electric resistance welded steel pipe can be manufactured with high accuracy by controlling actuators such as cylinders and motors of various pipe manufacturing systems located upstream of the distance meter 11 using the pipe manufacturing system control device 4. In particular, by storing an ideal profile M for each outer diameter specification in advance in the inner surface shape calculation device 3, setting multiple characteristic points at arbitrarily selected positions of the ideal profile M, and comparing the characteristic points with the pipe inner surface shape profile to calculate control values, ideal forming can be performed and electric resistance welded steel pipe can be manufactured with higher accuracy.

[0063] Although the embodiments of the present invention have been described above, these are merely examples and should not be considered as limiting. The above embodiments may be omitted, substituted, or modified in various ways without departing from the spirit of the present invention.

[0064] For example, in the above embodiment, an example was shown in which the distance measuring unit includes a distance meter and a rotation mechanism for rotating the distance meter, and the distance meter is rotated in the circumferential direction of the electric resistance welded steel pipe to measure the inner surface shape in the circumferential direction. However, in the present invention, the distance measuring unit is not limited to this as long as it can measure the distance of the inner surface of the electric resistance welded steel pipe in the circumferential direction, and may be, for example, a unit in which multiple distance meters are arranged in the circumferential direction of the inner surface of the electric resistance welded steel pipe. In this case, the number and arrangement of the distance meters may be appropriately set so that the distance of the inner surface of the electric resistance welded steel pipe in the circumferential direction can be measured with the desired accuracy. [Explanation of symbols]

[0065] 1 Distance measurement section 2 Position adjustment mechanism 3. Inner surface shape calculation device 4. Pipe manufacturing control device 10 Electric resistance welded steel pipe 10a Unwelded section (open seam section) 11 Distance meter 12 Rotation mechanism 13 Rotating Head 14 Gear motor 15 Reducer 16a, 16b Shaft 17 Rotation detector 100 Inner surface shape measuring device

Claims

1. A method for measuring an inner surface shape of an electric-resistance welded steel pipe, which is produced by forming a steel plate and welding an end of the electric-resistance welded steel pipe, and measures the inner surface shape of the electric-resistance welded steel pipe before welding, comprising the steps of: a step of inserting a distance measuring unit having a non-contact distance meter into the electric resistance welded steel pipe from an unwelded portion of the electric resistance welded steel pipe at a predetermined stage before welding; a step of measuring the distance of the inner surface of the electric resistance welded steel pipe in a circumferential direction while rotating the distance meter of the distance measuring unit inserted into the electric resistance welded steel pipe; A step of calculating a circumferential shape of an inner surface as an inner surface shape of the electric resistance welded steel pipe at a predetermined stage before the welding based on the measured circumferential distance; The method for measuring the inner shape of an electric resistance welded steel pipe comprises:

2. The method for measuring the inner surface shape of an electric resistance welded steel pipe according to claim 1, wherein the distance meter is a laser distance meter.

3. A method for measuring the inner surface shape of an electric-welded steel pipe as described in claim 1 or claim 2, wherein the measuring step continuously measures the distance measured by the rangefinder and the rotation angle of the rangefinder due to rotation of the rangefinder, and the calculating step calculates the circumferential shape of the inner surface of the electric-welded welded steel pipe based on the distance and the rotation angle.

4. An apparatus for measuring an inner surface shape of an electric-resistance welded steel pipe, which measures the inner surface shape of the electric-resistance welded steel pipe before welding, in manufacturing an electric-resistance welded steel pipe by forming a steel plate and welding an end portion of the electric-resistance welded steel pipe, a distance measuring unit having a non-contact distance meter and a rotation mechanism for rotating the distance meter in a circumferential direction of the electric-resistance welded steel pipe, and rotating the distance meter within the electric-resistance welded steel pipe to measure a distance of an inner surface of the electric-resistance welded steel pipe in a circumferential direction; a position adjustment mechanism for adjusting the position of the distance measurement unit; A calculation device that calculates a circumferential shape of an inner surface as an inner surface shape of the electric resistance welded steel pipe at a predetermined stage before welding based on the circumferential distance measured by the distance measurement unit; a control unit that controls the position adjustment mechanism to insert the distance measurement unit into the electric-resistance welded steel pipe from an unwelded portion of the electric-resistance welded steel pipe at a predetermined stage before welding, causes the distance measurement unit to measure the distance of the inner surface of the electric-resistance welded steel pipe in the circumferential direction, and causes the calculation device to calculate a circumferential shape of the inner surface as the inner surface shape of the electric-resistance welded steel pipe at the predetermined stage before welding based on the circumferential distance measured by the distance measurement unit; An apparatus for measuring the inner shape of an electric resistance welded steel pipe.

5. The apparatus for measuring the inner surface shape of an electric resistance welded steel pipe according to claim 4, wherein the distance meter is a laser distance meter.

6. The inner surface shape measuring device for electric welded steel pipes as described in claim 4 or claim 5, wherein the distance measuring unit further has a rotation detector that measures the number of rotations of the distance meter, and continuously measures the distance measured by the distance meter and the rotation angle of the distance meter obtained from the number of rotations detected by the rotation detector, and the calculation device calculates the circumferential shape of the inner surface of the electric welded steel pipe based on the distance and the rotation angle.

7. A method for producing an electric-resistance welded steel pipe, comprising: A process of continuously bending a steel sheet in the width direction using a pipe-making system having multiple roll stands; a step of welding both ends of the steel plate formed by the bending; a step of inserting a distance measuring unit having a non-contact distance meter into the electric resistance welded steel pipe from an unwelded portion of the electric resistance welded steel pipe at a predetermined stage before welding; a step of measuring the distance of the inner surface of the electric resistance welded steel pipe in a circumferential direction while rotating the distance meter of the distance measuring unit inserted into the electric resistance welded steel pipe; A step of calculating a circumferential shape of an inner surface as an inner surface shape of the electric resistance welded steel pipe at a predetermined stage before the welding based on the measured circumferential distance; a step of controlling an actuator of the pipe-making system based on the calculated circumferential shape of the inner surface so that the circumferential shape of the inner surface becomes a desired shape; The method for producing an electric resistance welded steel pipe comprising the steps of:

8. The calculating step includes setting a plurality of feature points at arbitrarily selected positions of an ideal profile, which is a pre-stored ideal circumferential inner surface shape profile of the electric resistance welded steel pipe, and calculating a control value by comparing the feature points with corresponding feature points of an actual measured profile, which is an actual measured circumferential inner surface shape profile of the electric resistance welded steel pipe; The method for producing electric resistance welded steel pipe according to claim 7 , wherein the controlling step controls an actuator of the pipe-making system based on the control value.

9. An electric-resistance welded steel pipe manufacturing facility for manufacturing electric-resistance welded steel pipes, A pipe-making system having multiple roll stands that continuously bend the steel plate material in the width direction; An actuator that drives the pipe-making system; a welding means for welding both ends of the steel plate formed by the bending; an electric resistance welded steel pipe inner surface shape measuring device for measuring the inner surface shape of the electric resistance welded steel pipe before welding; A pipe-making system control device for controlling an actuator of the pipe-making system; having The inner surface shape measuring device is a distance measuring unit having a non-contact distance meter and a rotation mechanism for rotating the distance meter in a circumferential direction of the electric-resistance welded steel pipe, and rotating the distance meter within the electric-resistance welded steel pipe to measure a distance of an inner surface of the electric-resistance welded steel pipe in a circumferential direction; a position adjustment mechanism for adjusting the position of the distance measurement unit; A calculation device that calculates a circumferential shape of an inner surface as an inner surface shape of the electric resistance welded steel pipe at a predetermined stage before the welding based on the circumferential distance measured by the distance measuring unit; a control unit that controls the position adjustment mechanism to insert the distance measurement unit into the electric-resistance welded steel pipe from an unwelded portion of the electric-resistance welded steel pipe at a predetermined stage before welding, causes the distance measurement unit to measure the distance of the inner surface of the electric-resistance welded steel pipe in the circumferential direction, and causes the calculation device to calculate a circumferential shape of the inner surface as the inner surface shape of the electric-resistance welded steel pipe at the predetermined stage before welding based on the circumferential distance measured by the distance measurement unit; having The pipe-making system control device is an electric-resistance welded steel pipe manufacturing equipment that controls actuators of the pipe-making system based on the calculated circumferential shape of the inner surface so that the circumferential shape of the inner surface becomes a desired shape.

10. The calculation device prestores an ideal profile, which is an ideal pipe inner surface shape profile of the electric resistance welded steel pipe in the circumferential direction, sets a plurality of feature points at arbitrarily selected positions of the ideal profile, and calculates a control value by comparing the feature points with corresponding feature points of an actual measured profile, which is an actual measured pipe inner surface shape profile of the electric resistance welded steel pipe in the circumferential direction; The electric resistance welded steel pipe manufacturing facility according to claim 9, wherein the pipe-making system control device controls the actuators of the pipe-making system based on the control value.

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