Method for measuring tube outer peripheral length and instrument therefor

Abstract

To enable operation with a measuring instrument left on a line which automatically measures the outer peripheral length of an element tube in the process of manufacturing a tube.SOLUTION: A measure bobbin 4 is rotatably attached on a swivel ring 3 retained so as to swivel along the outer periphery of an element tube / tube T. The hold / swivel drive mechanism of the swivel ring 3 has winding function for winding a measure 5 around the outer peripheral surface of the element tube / tube T by accompanying the rotation of the swivel ring 3 with a starting point of the measure 5 in the measure bobbin 4 fixed outside of the outer periphery of the swivel ring 3. When the state that the measure 5 is wound by a turn or more around the element tube / tube T is to be measured in an observation field of view from outside, the swivel ring 3 or the measure bobbin 4 moves in the axial direction of the element tube / tube T by the width dimension of the measure 5, so that the wound measure 5 avoids the situation of lapping in the observation field of view.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and device for measuring the outer periphery of a blank pipe during forming, in order to control the periphery to determine whether the roll position adjustment and forming amount are appropriate when changing product dimensions in a cold roll forming machine capable of producing steel pipes with several-fold diameter ratios, for example. [Background technology]

[0002] Electric resistance welded steel pipes are manufactured on a mill line using a large number of forming roll stands, where steel strips unwound from coils are bent, welded, and drawn to produce steel pipes of the required diameter. In more detail, the strip steel plate is edge-bent and bent into a semicircular shape in the breakdown BD process, then formed into an approximately round tube in the cluster CL process, and finally formed into a blank tube with the desired outer circumference in the fin pass roll FP process.

[0003] Next, the pipe is butt-welded using a squeeze roll SQ to form a round pipe, and then it is finished into an electric resistance welded steel pipe with the required diameter, roundness, and straightness using a sizing roll SZ and a Turks head roll TH, and is then cut to the required pipe length to complete the pipe.

[0004] When performing initial threading due to a change in steel pipe diameter, etc., the position of the forming rolls in each process is adjusted while the strip steel plate passes through the BD, CL, and FP processes in order. If the plate thickness is changed while keeping the same diameter, there is no need to perform initial threading again, but since the plate width will change, the roll position in each stand will need to be adjusted.

[0005] Whether the roll position adjustment has been performed properly is confirmed by measuring the outer periphery of the mother pipe, a process known as circumference control. That is, at the entry and exit sides of the stand after the FP process, the outer periphery of the mother pipe or welded pipe is measured with a steel tape measure (hereinafter referred to as "measure") to confirm whether the specified amount of reduction has been achieved, and this information is fed back to the roll position adjustment.

[0006] Currently, the outer circumference is measured manually by wrapping a measuring tape around the outer circumference of the unprocessed pipe or welded pipe while the production line is stopped. Taking the initial threading in the FP process as an example, the initial roll position is adjusted according to the forming schedule for the desired diameter, and then the material is passed through once and the outer periphery is measured. After that, the roll position is adjusted again, the material is advanced again, and the circumference is measured a second time to confirm the effectiveness of the previous roll position adjustment. If there is an excess or deficiency, the circumference measurement is repeated a third time. When such manual measurement work is performed multiple times, there are concerns about safety, measurement time which affects the availability rate, and reproducibility of measurement accuracy.

[0007] On the other hand, to reduce the labor required for measurement, a device has been proposed in which a welded spiral steel pipe is inserted into the belt that forms the loop, tension is applied to the belt wire using a spring or cylinder, and the length of the wound belt wire that is unwound is measured (Patent Documents 1, 2, and 3).

[0008] In addition, a device has been proposed in which a self-propelled tape measure wrapping device like a can opener is wound around the outer periphery of the end of a welded steel pipe, and the length of the tape measure that is unwound is measured as the outer periphery length (Patent Document 4).

[0009] The devices in Patent Documents 1, 2, and 3 measure the outer circumference of spiral steel pipes that have been welded and are proceeding to the next process, and are not suitable for online circumference management during pipe production before welding, such as in the FP process.Furthermore, Patent Document 4 is a measuring device for pipes such as steel pipes that have been cut to the required length after pipe production, and cannot be placed on the line of an operating pipe mill. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JPA 1981010203 [Patent Document 2] JPA 1983083207 [Patent Document 3] JPB 1982020561 [Patent Document 4] Jippan Hei 6-56702 Summary of the Invention [Problem to be solved by the invention]

[0011] The steel strip used to form the pipe material varies greatly in its characteristics due to differences in the steelmaking, rolling, and width cutting processes, and the width of the strip material in particular is not uniform, and may even meander slightly in the longitudinal direction. When manufacturing welded steel pipe of a certain diameter, a coil of strip steel plate with a specified plate width is used, but because the characteristics of the material vary, such as uneven plate width and thickness, after it has been bent and formed in the BD and CL processes, in order to weld it into a steel pipe of the required diameter in the SQ process, it is necessary to adjust the cross-sectional shape and outer periphery length by drawing to an amount that suits the characteristics of the material in the FP process just before SQ.

[0012] Furthermore, in pipe mills that can manufacture steel pipes with a diameter ratio of 2 to 3 times without changing rolls, product dimensions are often changed, and setup is changed each time. Once position adjustment is completed at the roll stand where bending is performed, the degree of drawing to be performed at the two- to three-stage fin pass FP roll stand must be determined by measuring the outer periphery of the blank pipe before and after the roll stand, so it is extremely important to adjust the roll position and manage the periphery to ensure that forming is appropriate.

[0013] For example, whether the bending radius in the three-stage fin pass FP roll stand region is formed according to the design schedule has a significant impact on the welding quality in the next process, so the sum of the outer periphery of the mother pipe before it enters the first stage FP roll and the distance between the opposing edges of the mother pipe (the length of the open portion of the mother pipe) is measured as the outer periphery of the open mother pipe (open pipe), and the true outer periphery of the mother pipe is determined and evaluated. Similarly, the outer periphery of the open pipe after it has passed the first and second stages FP rolls is measured, and this type of periphery control is carried out. In addition, in the SZ and TH processes, circumference management, which measures the outer circumference of the tube, is used to manage the distribution of the amount of drawing at each roll stand, contributing to improved dimensional accuracy of the product.

[0014] In such a pipe mill line, for example, in order to reduce the labor required for or automate the initial threading process each time a product dimension is changed, it is necessary to perform circumference management that enables the outer circumference of the blank pipe to be measured online.

[0015] An object of the present invention is to provide a method and apparatus for automatically measuring the outer periphery of a mother tube during forming. [Means for solving the problem]

[0016] The inventors have studied various measurement methods and device configurations with the aim of creating a circumference measurement device that can be easily installed even in spaces where the stand pitch is narrow or where there is existing equipment around the stands, and that is configured so that the measurement device can be operated while remaining on the line.

[0017] As a result, the inventors discovered that by supporting a measure bobbin with a wound measuring tape on a swivel ring that contains the mother tube and rotatably holds the outer circumference of the tube, and as the ring rotates, the measure bobbin rotates while revolving around the outer circumference of the mother tube, winding the measuring tape around the outer circumference of the mother tube, and then moving the swivel ring itself or the bobbin itself linearly in the axial direction of the mother tube by the required distance, for example, the width of the measuring tape, so that the measuring tape is wrapped around the tube more than once, so that the measuring tape is close to each other on the outer circumference of the mother tube but does not overlap, the outer circumference can be measured by observing the measuring tape scale from above, for example, visually, or in the field of view of a periscope or digital camera, and the invention was completed.

[0018] Furthermore, in this method, by ensuring that the tape measures are close to each other on the outer surface of the raw pipe when wrapping the tape around the raw pipe more than once, and that they do not overlap, the outer periphery length is not measured precisely, but it was discovered that this method allows measurements to be made in the shortest time possible and with good reproducibility each time, and the invention was completed based on this knowledge.

[0019] That is, the present invention is The method and device for measuring the outer periphery of a mother pipe during pipe manufacturing and / or a pipe after welding (mother pipe / pipe) measures the state of a tape measure wrapped around the mother pipe / pipe one or more times from an observation field from the outside. a swivel ring that encloses the mother tube / tube and holds its outer periphery rotatably, and a holding / swivel drive mechanism for the swivel ring; A measuring bobbin with a measuring tape wound around it is rotatably mounted on the swivel ring, and the starting point of the measuring tape is fixed outside the outer periphery of the swivel ring. The holding / swivel drive mechanism is provided with a measuring tape winding function that enables the measuring tape to be wound / unwound around the outer periphery of the mother tube / tube as the swivel ring rotates. a tube axial direction moving means for moving the swivel ring or the measure bobbin in the tube axial direction of the mother tube / tube by at least the tape width dimension of the measure when the measure is wound around the mother tube / tube one or more times; This is a method and device for measuring circumference that is characterized by the fact that the wrapped tape does not overlap within the observation field.

[0020] Furthermore, in the above configuration, the present invention The outer periphery length measuring method and device are characterized in that the axial movement stage of the slewing ring itself is a linear motion mechanical mechanism with a threaded structure between the outer periphery of the slewing ring and the holding mechanism of the slewing ring.

[0021] Furthermore, in the above configuration, the present invention The method and device for measuring outer periphery length are characterized in that the means for moving the major bobbin itself in the tube axial direction uses a linear motion mechanical mechanism as a shaft support mechanism for the major bobbin.

[0022] Furthermore, in the above configuration, the present invention The method and device for measuring outer periphery length are characterized in that the means for moving the major bobbin itself in the tube axial direction uses a linear motion mechanical mechanism for placing the major bobbin on the swivel ring.

[0023] Furthermore, in the above configuration, the present invention The method and apparatus for measuring circumference are characterized in that the observation field is obtained by a digital camera. [Effects of the Invention]

[0024] The circumference measuring method and device of the present invention allows measurements to be taken while the pipe mill line is stopped, and after the measurement is completed, the device can be left in place and pipe production operations can resume. In addition to measuring the outer periphery of welded steel pipes offline, it is also possible to measure the outer periphery of raw pipes before welding, raw pipes after welding online, and round and square pipes before, during and after forming in the forming process. Furthermore, the measurement can be performed automatically without the need for human intervention. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a simplified explanatory diagram of a measuring device for illustrating an overview of a perimeter measurement method. [Figure 2] FIG. 1 is a front view illustrating a circumference measuring device according to a first embodiment. [Figure 3] FIG. 1 is an explanatory top view of a circumference measuring device according to a first embodiment. [Figure 4] FIG. 1 is an explanatory side view of a circumference measuring device according to a first embodiment. [Figure 5] 5A and 5B are explanatory views of a cross section taken along the line AA of the circumference measuring device of the first embodiment, in which FIG. 5A shows the initial state and FIG. 5B shows the state after one and a half revolutions. [Figure 6] FIG. 10 is a front view illustrating a circumference measuring device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] The configuration of the measuring device and the measuring method will be explained based on the simplified front view of the measuring device in Figure 1. Here, an example will be explained in which it is placed on the upstream side of the fin pass roll stand. The blank tube being formed as the object to be measured has its opposing edges open, and moves from the front to the back of the figure.

[0027] The main frame of the equipment is, for example, a single face plate 1, with a hole 2 in the center through which the blank tube T can pass. Around the periphery of this hole 2, there is a holding mechanism that supports a ring plate 3, which also has an inner diameter that allows the blank tube T to pass through, so that the ring plate 3 can rotate around the hole 2. The hole 2 is configured to prevent interference, taking into account the size of the product formed by the pipe mill, and is designed to allow the blank tube to pass through at the center of the tube axis or the center of the tube bottom, depending on the roll forming method, for example.

[0028] A bobbin 4 is rotatably mounted on the top surface of the ring plate 3, and has a tape-like measuring tape 5 wound around it. The starting end of the measuring tape 5 can be anywhere outside the outer periphery of the ring plate 3 in the figure, but here it is fixed to the center of the right side of the face plate 1. The measuring tape 5 is made of, for example, a thin steel tape, but its thickness is exaggerated in the figure to illustrate how it is wound.

[0029] Here, if the state in which the bobbin 4 faces the vicinity of the measuring fixing point 6 is taken as the neutral position before measurement, there will be no obstacles when the blank tube T passes through the hole 2 in the face plate 1.

[0030] From the neutral position, the ring plate 3 is rotated counterclockwise as shown in the figure, and the bobbin 4 rotates about one and a half revolutions around the bare tube T, resulting in the state shown in the figure.If a camera S is placed above the bare tube T, whose opposing edge portion is open, the scale markings on the tape measure can be read within the field of view of the camera S.

[0031] However, simply rotating the ring plate 3 causes the measuring tapes to overlap, making it unclear which of the measuring tape scales at both edge positions of the raw tube T and the scale indicating the outer circumferential length is located. Therefore, when the bobbin 4 turns around the blank tube T one or more times, it is necessary to prevent the measuring tapes from overlapping each other.

[0032] In other words, a means is provided for moving the bobbin 4 itself or the ring plate 3 itself in the axial direction of the tube so that when the bobbin 4 rotates one or more times around the base tube T, it moves in the axial direction of the tube by at least the width of the measuring tape, and by bringing the wrapped measuring tape close together so that they do not overlap within the observation field, the outer circumferential length of the open pipe can be measured, for example, by reading the measuring tape scales at two opposing edge positions of the base tube T.

[0033] When wrapping the tape of the measuring tape around the outer surface of the blank pipe more than once, to prevent the tape from coming close to each other and overlapping, if the tape unwinding speed of the measuring tape, the rotation speed of the ring plate (the revolution speed of the bobbin), and the axial feed speed of the rotating ring / measuring bobbin itself are kept constant and synchronized, measurements can be taken at the shortest length and with good reproducibility every time. Furthermore, measurements can be made with consistent accuracy even if the above speeds are not constant. Furthermore, in order to measure the outer circumferential length of the raw tube T itself, the opposing edge apexes 8 of the illustrated raw tube T can be confirmed, the edge opening state can be observed, and the opposing distance between the edge apexes 8 can be measured.

[0034] When winding and measuring at the maximum and minimum diameters within a diameter ratio of several times the pipe mill's planned diameter, differences in winding speed may occur, and if movement in the pipe axial direction by the width of the measuring tape is insufficient, the movement amount can be increased by more than one to two times.

[0035] To make imaging and viewing easier when measuring the circumference or checking the edge apex 8, the type of lighting source, illuminance, and light distribution direction can be adjusted, and the measuring tape 5 itself can be colored or provided with an identification means such as reflecting specific light.

[0036] To enable the bobbin 4 to wind and unwind a tape measure around the outer circumferential surface of the blank tube T as the ring plate 3 rotates, a tape measure winding means having a mechanism for applying and maintaining the necessary tension is required. For example, a winding mechanism using an elastic body such as a spiral spring as shown in the embodiment can be used.

[0037] Various methods can be used to move the swivel ring itself in the axial direction of the tube. In the illustrated example, the ring plate 3 is supported by a holding mechanism that allows it to rotate using support wheels 7 placed around the outer periphery of the hole 2 in the face plate 1, and a spiral track is provided on the outer periphery of the ring plate 3 so that the support wheels 7 can run on the track. As the ring plate 3 is rotated by the rotation drive means, the plate 3 itself can be moved in the axial direction of the tube.

[0038] Furthermore, the support shaft of the support ring 7 itself is a screw shaft, and when the ring plate is driven to turn, the entire holding mechanism can be moved in the axial direction of the tube by the linear motion of the screw shaft.

[0039] The means for moving the major bobbin itself in the axial direction of the tube can use a linear motion mechanical mechanism for the major bobbin's support mechanism, and a linear motion mechanical mechanism such as a screw or copying mechanism that converts rotation into linear motion can be adopted for the support part of the bobbin 4.

[0040] Furthermore, a linear motion mechanical mechanism can be used for the mechanism for placing the major bobbin on the swivel ring. For example, the plate itself on which the major bobbin is placed can be moved in the axial direction of the tube by a linear motion actuator, and the plate can be raised and lowered by a wedge-shaped slider that moves horizontally between the plate and the swivel ring by an actuator.

[0041] The amount of movement in the tube axis direction depends on various factors, such as the size of the diameter of the pipe to be made, whether it revolves around the mother tube T or revolves and rotates around it, and the configuration of the driving mechanical mechanism, so that the measuring tapes do not overlap when the ring plate 3 and bobbin 4 rotate around the mother tube T more than once.By taking these factors into consideration, it is possible to determine the above-mentioned orbit length, etc.

[0042] To rotate the ring plate 3, as shown in the embodiment, the spiral track on the outer periphery of the ring and the support wheel 7 are used, and a round belt, rubber belt, etc. is hung on the spiral track and driven by a motor to rotate it.

[0043] The support wheel itself can also be driven by a mechanism that rotates it with a motor, for example, by friction with tires, gear meshing, direct drive of the rotating shaft, etc. Furthermore, a gear ring can be provided on the back surface or outer peripheral surface of the ring plate, and multiple gear motors can be arranged on the face plate 1 to drive it with gears.

[0044] The measurement of the measuring tape scale and the like can be performed using various observation fields, such as visual inspection from above the bare tube T or visual inspection from below using a periscope or endoscope. Measurements can also be performed using an observation field using a digital camera, and can be performed using anything from simple configurations such as a pan-focus lens camera or webcam to AI cameras using known image sensors and autofocusing means in the lens, allowing measurements to be performed remotely on a display device with an enlarged field of view.

[0045] Furthermore, it is equipped with an illumination light that can automatically adjust the direction of illumination and brightness, and the AI ​​camera's image sensor and program can track the observation target within the observation field even when the observation conditions change, and convert the readings of, for example, the letters, codes, calibrations on a measuring tape, etc. into image data and identify them, thereby automating measurements. [Example]

[0046] Example 1 A measuring device for implementing the perimeter measuring method shown in FIG. 1 will be described with reference to FIGS. 2 to 5. FIG.

[0047] The frame of the device is a single main plate 10 with a passage hole 11 in the center for the raw tube to be formed. Four guide rollers 12 are journaled around the passage hole 11 at approximately 90-degree intervals, and the upper left part of the main plate 10 protrudes outward to accommodate a geared motor 13.

[0048] The four guide rollers 12 are configured so that the outer peripheries of the rollers fit into spiral grooves 20b provided on the outer periphery of a ring plate 20 having an inner diameter similar to that of the passage holes, thereby supporting the rotation of the ring plate 20.

[0049] The ring plate 20 is rotated by a so-called belt drive, in which a belt rope 14 driven by a geared motor 13 is fitted into a belt groove 20a provided on the outer circumferential surface of the ring plate 20. This belt drive adjusts the position of a roller 16 of a tension adjustment unit 15 arranged on the plate adjacent to the geared motor 13, thereby maintaining an appropriate tension in the belt 14.

[0050] A bobbin 22 around which a steel tape measure 21 is wound is rotatably supported on the front surface of the ring plate 20 via a winding mechanism 23 that winds the measure using a spiral spring.

[0051] The tip of the tape measure 21 is led out to a pair of tape guide rollers 24, 24 arranged adjacent to the bobbin 22 and fixed to a tape measure fixing point 17 provided in the right center of the main plate 10. A felt pad 25 for cleaning the tape measure 21 is arranged between the pair of tape guide rollers 24, 24.

[0052] A sensor dog 26 for detecting the rotation position is placed at a required position on the top surface of the ring plate 20, and a proximity sensor 18 provided near the guide roller 12 on the lower right side of the main plate 10 detects the sensor dog 26 to determine the number of rotations of the bobbin 22.

[0053] If the state of the front view in Figure 2 is the initial state of the ring plate 20, which is in the neutral position, its cross-sectional view along the line AA is Figure 5A, and after rotating one and a half revolutions, it becomes the state shown in Figure 5B, where the ring plate 20 moves downstream by the tape width of the measuring tape 21, to the left side in Figure 5, and the measuring tape wrapped around the base pipe is observed from the observation field, in this case, when viewed from above, the measuring tapes do not overlap each other.

[0054] A measuring device having the above configuration is placed in line, for example, on the upstream or downstream side of a fin pass roll stand, connected to an arm hanging down from above without being connected to the stand, and the outer circumferential length of a blank tube can be measured by, for example, mounting a camera on the arm.

[0055] Example 2 The device shown in FIG. 6 has the same configuration as that of the first embodiment, except that the shape of the main plate 30 and the positions of the geared motor 13 and tension roller unit 15 are different.

[0056] In Example 1, the geared motor 13 is placed at the upper left side of the figure, but if the roll stand on which the measuring device is placed has a different configuration or function, there may be components that interfere with the corresponding position. In Example 2 of Figure 6, the main plate 30 is irregularly shaped and extends upward to avoid the equipment on the roll stand side.

[0057] Since the geared motor 13 is spaced upward from the ring plate 20, a pair of rollers 16, 16 are appropriately arranged to guide the belt rope 14 to the tension adjusting section 15. An image sensor is placed on the main plate 30 between the geared motor 13 and the ring plate 20, and the outer circumferential length of the blank tube can be measured. [Industrial Applicability]

[0058] The method and apparatus of the present invention enable remote or automatic measurement of the outer circumferential length of the blank pipe being formed during the initial adjustment process when changing product dimensions in a cold roll forming machine capable of producing steel pipes with several times the diameter ratio. This makes it easy to adjust the position of the rolls in each forming roll stand and to manage the circumferential length to ensure that the amount of forming is appropriate, and also allows for automation of operations. [Explanation of symbols]

[0059] 1 face plate 2 hole 3,20 Ring Plate 4,22 Bobbin 5,21 Major 6,17 Major fixed point 7 Support wheel 8 Edge top 10,30 Main plate 11 Passing hole 12 Guide roller 13 Geared motor 14 Belt 15 Tension adjustment section 16 Tension roller 17 Tape Measure Holder 18 Proximity sensor 20a belt groove 20b spiral groove 23 Winding mechanism 24 Tape guide roller 25 felt pads 26 Sensor Dog S Camera T plain tube

Claims

1. The method and device for measuring the outer periphery of a mother pipe during pipe manufacturing and / or a pipe after welding (mother pipe / pipe) measures the state of a tape measure wrapped around the mother pipe / pipe one or more times from an observation field from the outside. The swivel ring contains the blank tube / tube and holds its outer periphery rotatably, and the holding / swivel drive mechanism is provided. a measuring bobbin with a measuring tape wound around it is rotatably mounted on the swivel ring, the start point of the measuring tape is fixed outside the outer periphery of the swivel ring, and the holding / swivel drive mechanism has a measuring tape winding function that enables the measuring tape to be wound / unwound around the outer periphery of the mother pipe / pipe as the swivel ring rotates; a tube axial direction moving means for moving the swivel ring or the measure bobbin in the tube axial direction of the mother tube / tube by at least the tape width dimension of the measure when the measure is wound around the mother tube / tube one or more times; A method for measuring circumference characterized in that the wrapped tape does not overlap within the observation field.

2. In claim 1, The outer periphery length measuring method is characterized in that the moving stage of the slewing ring itself in the pipe axial direction is a linear motion mechanical mechanism with a screw structure between the outer periphery of the slewing ring and the holding mechanism of the slewing ring.

3. In claim 1, The method for measuring outer circumference is characterized in that the means for moving the major bobbin itself in the tube axial direction uses a linear motion mechanical mechanism as the axial support mechanism of the major bobbin.

4. In claim 1, The method for measuring outer circumference is characterized in that the means for moving the major bobbin itself in the tube axial direction uses a linear motion mechanical mechanism for placing the major bobbin on the swivel ring.

5. In claim 1, A method for measuring circumference, characterized in that the observation field is taken using a digital camera.

6. This is a perimeter length measuring device that measures the perimeter of a mother pipe during pipe manufacturing and / or a pipe after welding (mother pipe / pipe) by wrapping a measuring tape around the mother pipe / pipe one or more times from an observation field from the outside. The swivel ring contains the blank tube / tube and holds its outer periphery rotatably, and the holding / swivel drive mechanism is provided. a measuring bobbin with a measuring tape wound around it is rotatably mounted on the swivel ring, the start point of the measuring tape is fixed outside the outer periphery of the swivel ring, and the holding / swivel drive mechanism has a measuring tape winding function that enables the measuring tape to be wound / unwound around the outer periphery of the mother pipe / pipe as the swivel ring rotates; a tube axial direction moving means for moving the swivel ring or the measure bobbin in the tube axial direction of the mother tube / tube by at least the tape width dimension of the measure when the measure is wound around the mother tube / tube one or more times; A circumference measuring device characterized by the fact that the wrapped tape does not overlap within the observation field.

7. In claim 6, The outer periphery length measuring device is characterized in that the moving stage of the swivel ring itself in the pipe axial direction is a linear motion mechanical mechanism with a screw structure between the outer periphery of the swivel ring and the holding mechanism of the swivel ring.

8. In claim 6, The outer circumference measuring device is characterized in that the means for moving the major bobbin itself in the tube axial direction uses a linear motion mechanical mechanism as the axial support mechanism of the major bobbin.

9. In claim 6, The outer circumference measuring device is characterized in that the means for moving the major bobbin itself in the tube axial direction uses a linear motion mechanical mechanism for placing the major bobbin on the swivel ring.

10. In claim 6, A circumference measurement device characterized in that the observation field is taken by a digital camera.

Images