JPS60171408A - Thickness measuring apparatus for tube thread part - Google Patents

Abstract

PURPOSE:To automatically perform a measurement in parallel with machining by measuring the thickness of a threaded tube based on measured values with a displacement meter when the displacement of a cutting tool in the specified axial direction of the tube is detected with a traverse value measuring device after the end of the tube is detected with the projection type optical displacement meter. CONSTITUTION:The length Lb of screwing a thread section on a joint (not illustrated) is set for a traverse value measuring device 32 so that the optical axis of a projector 30A of a projector type optical displacement meter 30 coincides with the edge of a finishing blade X of a chaser 26 while the rotation period of a tube 18 is set for a memory circuit of an arithmetic section (not illustrated). A thread cutting of the tube 18 is done moving a frame 22 following a taper guide 20 and a displacement meter 30 is made ready for measurement as the finishing blade X puts on the tube 18. In addition, when the device 32 reaches the length Lb, a coincidence signal is sent to the memory and arithmetic circuits to output a measured value l stored to the arithmetic circuit and based on the taper angle of a guide 20, a correction processing is executed to convert the measured value to the value lc in the length Lb to determine the thickness T by the thickness T=l2-lc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a pipe thread thickness measuring device for measuring the wall thickness of a threaded part formed at the end of a pipe.

As shown in the partial cross-sectional view of FIG. 1, a steel pipe used as a conventional oil country tubular goods has a thread on the outer circumferential surface of its end 10 to be threadedly connected to a joint 12 for connection with another steel pipe. Part 1
4 is formed. The strength of this threaded part is extremely important for oil country tubular goods, which are used in conjunction with hundreds of pipes, and for this reason, thread elements such as taper, lead, hide, etc. are measured to ensure that they meet standards and to ensure that there are no flaws on the thread surface. It is required that there be no

In addition, for pipes without upsets, the thickness of the threaded portion is important. That is, as can be seen from FIG. 1, the threaded portion cut into the tube without upset has a thinner wall thickness. The part of the threaded part 14 having a length La that is threaded with the joint 12 and has a length Lb is reinforced by the joint 12, whereas the part of the threaded part 14 having a length La that is not threaded with the joint 12 is reinforced by the joint 12. The portion is weaker than other portions, and the stress of the connection portion is concentrated at that portion. Therefore, the insufficient thickness of the threaded portion 14 causes a buckling accident to occur at the portion of length Lc.

Therefore, API (8merican Petroleum)
In the standard, the length La from the tube end to the thread reduction point A and the length Lb from the tube end to the limit point B at which the fitting is screwed are determined. During thread cutting, it is necessary for the strength of the threaded part that the thicknesses Ta and Tb of the threaded part at points A and B are respectively at the minimum standard values.

However, in the conventional wall thickness inspection of a threaded part of a pipe end, a tuning fork-shaped gauge 16 is inserted from the end of the pipe IO so as to sandwich the pipe wall part, as shown in FIG. If the insertion amount l into the threaded portion 14, which is formed by tapering it so that In other words, the wall thickness itself was not measured, and moreover, it was a manual inspection, and some kind of improvement was desired.

In view of such circumstances, the applicant here
Patent application published in 1984 as Publication No. 171613
No. 54402, we proposed a method and device for measuring wall thickness of pipe threads.

The method for measuring the wall thickness of a pipe thread according to Japanese Patent Application Laid-Open No. 58-171613 is to measure the distance from the base 1μ position on the outside of the pipe to the outer peripheral surface of the pipe thread, and separately from the reference position on the inside of the pipe. By measuring the distance to the inner peripheral surface of the pipe and subtracting the sum of the two measured distances from the distance between both reference positions,
Measuring the wall thickness of the pipe thread.

As is clear from the following -1-, in the method disclosed in the above publication, the thickness of the threaded portion must be measured independently of the cutting process of the thread. Furthermore, the measurement operation itself is complicated because two measurements have to be taken, one on the inside and one on the outside of the tube.

Furthermore, two distance or length measuring means are required, and the device configuration is complicated.

The device disclosed in Publication No. 1 uses an optical laser beam to measure the outer circumferential surface of a pipe thread, and when measuring the thread thickness, it is necessary to calculate the bottom and peak of the thread from profile data. .

Purpose of the Invention Therefore, the purpose of the present invention is to automatically measure the thickness of a thread at a predetermined distance from the pipe end, without the need for calculations based on profile data, and which can be measured almost in parallel with the thread cutting process. Moreover, it is an object of the present invention to provide a pipe thread wall thickness measuring device having a simple configuration and capable of quantitatively measuring the thickness.

According to the present invention, the thread cutting surfaces of a thread cutting tool for pipe thread cutting are fixed at a predetermined distance from the thread cutting tool so as to face each other, and the thread cutting surfaces of the pipe are and a traversing amount measuring device that measures the amount of displacement of the thread cutting tool in the tube axis direction. After the projecting type optical displacement side detects the pipe end, when the traverse amount measuring device detects a predetermined displacement of the well-intentioned thread cutting tool in the pipe axial direction, the thickness of the pipe thread portion is measured based on the measurement value by the displacement meter. Provided is a pipe thread wall thickness measuring device that measures thickness.

As described above, by providing a branch light type optical displacement cutter facing the thread cutting surface of the thread cutting tool, it is possible to detect the pipe end as the thread cutting tool moves in the pipe axis direction, and also to detect the thread cutting surface of the thread cutting tool. The wall thickness of the threaded part can be measured in parallel with the cutting process. Therefore, during pipe thread cutting, after the light projecting optical displacement side detects the pipe end, when it is determined by the traverse amount measuring device that the thread cutting tool has moved a predetermined amount in the pipe axis direction, the light projecting type If the wall thickness is measured based on the output of the optical displacement meter, the screw wall thickness at a point a predetermined distance from the tube end can be easily measured. Furthermore, since the thickness of the threaded portion can be measured using only the value measured by the displacement meter, the thickness of the threaded portion can be measured automatically and quantitatively without the need for calculations based on profile data.

Embodiments Hereinafter, embodiments of a pipe thread wall thickness measuring device according to the present invention will be described with reference to the accompanying drawings.

FIG. 3 is a schematic configuration diagram of a pipe thread thickness measuring device of the present invention. Thread cutting equipment is roughly divided into a thread cutting tool fixed translation-pipe rotating type and a thread cutting tool rotation parallel translation-tube fixed type. Built into cutting equipment.

In order to pressurize the end of the rotating tube 18 by thread cutting, the frame 2 moves in the tube axis direction following the taper guide 20? A tool stand 24 is fixed to the mount 24, and a screw cutting tool such as a chaser 26 is attached to the mounting stand 24. As shown in FIG. 5, the illustrated chaser 26 has a finishing blade X, a medium cutting blade Y1, and a rough cutting blade Z arranged side by side, so that it is possible to perform rough cutting to finishing at one time.

The pedestal 22 to which the chaser mount 24 is attached is made in a U-shape so that its tip 2B can enter inside the tube end. The tip 28 of the pedestal 22
A floodlight type optical displacement meter 30 is installed in (=I).

This floodlight type optical displacement meter 30 includes a floodlight 30Δ that emits a light beam toward the inner surface 18A of the tube 18 at right angles to the axis of the tube 18, and a light beam from the floodlight 3oΔ. The camera 30Ba is configured to view the light spot formed by the camera 30Ba from a direction inclined with respect to the light beam of the projector 30A.

FIG. 4 is a diagram illustrating the principle of position measurement using a floodlight type optical displacement meter. Now, the tube inner surface 18Δ is the reference position P with respect to the projector 30A. Camera 30B
The beam spot S at that time is on the center point O of the field of view. When the tube inner surface 18A approaches the projector 30A and moves to position P1, the camera 30B sees the beam spot s at that time, for example, to the right of the center point O of the field of view. Conversely, when the tube inner surface 18A moves away from the projector 30A to position P2, the camera 30B moves to the center point 0 of the field of view.
The beam spot S2 at that time is seen further to the left. Therefore, in the field of view of the camera 30B, by setting the coordinates so that the coordinate center is located on the center point O, and by measuring the distance from the coordinate center of the beam spot, the direction of the optical axis of the light beam, that is, the diameter of the tube. The inner surface of the tube 18Δ in the direction and the reference position P.

The distance D1 between the two can be set.

Therefore, the displacement meter 30 and the reference position P. The distance from the displacement meter to the inner surface 18Δ of the tube to be measured can be determined by subtracting or adding the above distance D□ to the distance between the displacement meter and the inner surface 18Δ of the tube to be measured.

In addition, in this floodlight type optical displacement meter, the floodlight 30
Unless the inner surface of the tube is in front of A, the camera 30B cannot detect the light spot and cannot measure the position of the inner surface of the tube. Therefore, at the moment in FIG. 3 when the floodlight type optical displacement meter 30 moves in the tube axis direction from the outside to the inside of the tube, the displacement meter changes from a non-measurable state to a measurable state. This moment is the moment when the tube end is positioned directly in front of the projector at 3°A. Therefore, the tube end can be detected depending on whether the measurement is possible or not.

In the illustrated pipe thread wall thickness measuring device, a traverse amount measuring device 32 is further attached to the pedestal 22. The traversing amount measuring device 32 detects the movement of the pedestal 22, that is, the chaser 26 and the displacement meter 30 in the tube axis direction.

Since the chaser 26 and the displacement gauge 30 are mounted on the stand 22, as shown in FIG.
6 is a predetermined constant distance 11, and the distance f12 between the cutting edge of the blade It is. Therefore, the floodlight 30A of the displacement meter 30
If the optical axis of the light beam is aligned with the finishing blade
Thickness T at the root of the screw cut by the finishing blade X,
(-112-β3) can be calculated.

On the other hand, the distance between the cutting edge T of the rough cutting blade Z of Chaser 26 and the displacement word! ! 4 is also a fixed distance that can be known in advance. Therefore, if the optical axis of the light beam of the projector 30Δ of the displacement meter 30 is aligned with the blade base 'F of the rough cutting blade Z of the chaser 26, the measured value of the distance 15 from the displacement plate 30 to the tube inner surface 18Δ 30 in total, the wall thickness Ta (-
, fl! 1-L).

FIG. 6 is a block diagram showing the circuit of the calculation section of the pipe thread wall thickness measuring device. The output of the camera 30B is transmitted to the controller 34
The output of the traverse amount measuring device 32 is connected to a traverse amount counter 36. The controller 34 controls the camera 30
When B changes from an unmeasurable state to a measurable state, the traverse amount counter 36 is reset to zero, and the measured value is output to the storage circuit 38.

The traverse amount counter 36 is set with the distance from the pipe end at which the wall thickness is to be measured, and after being reset to zero, receives the output of the traverse amount measuring device 32 and counts up.
When the count value matches I-7, a match signal is output to the storage circuit 38 and the arithmetic circuit 40.

The memory circuit 38 receives the rotation period 1'' of the tube 18 and stores the open side constant value for one rotation period T. In other words, the storage circuit 38 holds the measured values for one rotation period Tp, and when a new measurement value is manually input, the measured values one rotation period old are sequentially erased.

When the traverse amount counter 36 outputs a coincidence signal, the storage circuit 38 stores the accumulated measured value for one period in the calculation circuit 40.
Output to. The measured values other than the latest measured value among the measured values manually input to the calculation circuit 40 do not indicate the wall thickness in terms of distance, and the measured value one rotation period before the preparation is less than the distance measured by screw 1.
This is the thickness in front of the pitch. Therefore, the arithmetic circuit 40
A correction process is performed to convert each manually inputted measurement value β into a distance value 1C based on the taper angle of the taper guide 20. Each correction value measurement value lc obtained in this way
The calculation T-(,i! or il',)-L is calculated for each time, and the average value, maximum value, and minimum value are calculated as necessary. Then, the results are displayed on the recorder 42 and the display 44.
and alarm 46 when the wall thickness is less than the standard value.
Activate.

Next, the measurement of the wall thickness of the pipe threaded portion at point B in FIG. 1 using the pipe threaded portion wall thickness measuring device as described above will be explained. In this case, the displacement meter 30 is set so that the optical axis of the light beam of the light projector 30A of the displacement meter 30 coincides with the cutting edge of the finishing blade X of the chaser 26. On the other hand, the distance Lb is set in the traverse amount counter 36, and the rotation period T of the tube 18 is set in the storage circuit 38.

In FIG. 3, when the pedestal 22 is moved following the taper guide 20 and the end of the pipe 18 is thread-cut, the rough-cutting blade 2 of the chaser 26 first cuts the pipe, and then the intermediate-cutting blade Y rough-cuts the pipe. Cut the screw grooves. Medium cutting blade Y
The light beam from the projector 30A passes through the tube 18 without hitting the tube 18 until the point where the light beam hits the tube end. Therefore, the displacement side 30 is in a non-measurable state.

After that, when the first blade X hits the tube 18, the projector 30
The light beam from A hits the inner surface 18A of the tube 18, and the camera 30B detects the light spot formed on the inner surface 18A of the tube, and becomes ready for measurement. As a result, the control circuit 34 resets the traverse amount counter 36 and outputs the measured value to the storage circuit 38.

Thereafter, as the thread cutting process progresses, the traverse amount 2 counter 36 counts up. When the count value matches the above, a match signal is output to the storage circuit 38 and the arithmetic circuit 40.

The memory circuit 3 receives the coincidence signal from the traverse amount count 36
8 is an arithmetic circuit 4 which calculates the accumulated measured values for one rotation period.
Output to 0. The arithmetic circuit 40 calculates the value at the distance Lb by applying each input measurement value l to the taper guide 20 based on the taper angle. . Execute correction processing to convert to . Each corrected measurement value β thus obtained. The calculation of T-β2-1c is performed for each time, and the average value, maximum value, and minimum value are determined as necessary. The results are then recorded on the recorder 42 and displayed on the display 44. Further, when the wall thickness T is less than the reference value 15, the alarm 46 is activated.

FIG. 7 is a schematic diagram of the head section including the displacement meter and its operating mechanism. A projector 30A and a camera 30B are fixed to a helad base 50 having a U-shaped cross section. Floodlight 3
0Δ is fixed to the head base 50 such that the optical axis of the light beam it outputs is located in the diametrical direction of the tube 18. On the other hand, the camera 30B may be placed at an angle with respect to the light beam in a plane including the optical axis of the light beam of the projector 30Δ and the central axis of the tube 18, or may be of a type including a near sensor 52, or may be of a type other than that of the camera 30B. It may be of a format.

The respective members attached to the head base 50 described above constitute the head portion of the pipe thread wall thickness measuring device.

A boss member 58 is fixed to the straightening plate 50Δ of the head base 50, and a large diameter shaft 60 extends from the boss member 58 through a bearing 62 and is supported by the bearing 62.

Plates 64A and 64B are fixed to the bearing 62 and boss member 58, respectively, and a bellows 66 is attached between these plates 64Δ and 64B.

The bearing 62 has an extension 62A.
2A is fixed to a pedestal 22 for mounting a chaser.

A small diameter shaft 70 is coupled to the tip of the large diameter shaft 60 protruding from the other end of the bearing 62 via a coupling fitting 68 . Further, a support plate 72A is fixed to the other end of the bearing 62. One end of a plurality of spacer bodies 74 is fixed to 2A, and another support plate 72B is fixed to the other end of the spacer body 74.

Further, an air piston cylinder 76 is fixed to the support plate 72B in parallel with the small diameter shaft 70. A piston rod 76Δ of the air piston cylinder 76 is coupled to the other end of the small diameter shaft 70 via a coupling fitting 78.

When the air piston cylinder 76 is operated to push the piston rod 76B to the left in FIG. 7, the small diameter rod 70 and the large diameter rod 60 move to the left in FIG. It can be retracted in the tube axis direction. Conversely, when the piston rod 76B is pulled to the right in FIG. 7 by the air piston cylinder 76, the small diameter rod 70 and the large diameter rod 6° move to the right in FIG. can be advanced in the direction of the tube axis. Therefore, air piston cylinder 7
By appropriately operating 6, the position of the measuring device head, especially the projector 30A, is adjusted in the tube axis direction with respect to the chaser 26, and the optical axis of the light beam is aligned with the cutting edge of the finishing blade X.
It can be matched to the cutting edge T of the rough cutting blade Z.

All of the embodiments described above are for male thread cutting, but can also be applied to female thread cutting by reversing the positional relationship between the thread cutting tool and the displacement fitting.

Effects of the Invention As is clear from the above description, if the pipe thread thickness measuring device according to the present invention is used, the thickness of the threaded part at a predetermined distance from the pipe end can be measured in parallel with the thread cutting process. Thickness can be easily measured. Furthermore, since the thickness of the threaded portion can be measured using only the measured value by the displacement meter, the thickness of the threaded portion can be measured automatically and quantitatively without the need for calculations based on profile data.

[Brief explanation of drawings]

Fig. 1 is a schematic illustration of a threaded part of a pipe end, Fig. 2 is a diagram illustrating a conventional method for measuring the thickness of a threaded part, and Fig. 3 is a schematic diagram of a thickness measuring device of a threaded part of a pipe according to the present invention. Diagram,
FIG. 4 is a diagram illustrating the principle of position measurement using a floodlight type optical displacement meter used in the pipe thread wall thickness measuring device according to the present invention, and FIG. A diagram illustrating the principle of wall thickness measurement by the device, FIG. 6 is a block diagram showing the configuration of the calculation section of the pipe thread wall thickness measuring device according to the present invention, and FIG. FIG. 2 is a schematic diagram of a head section including a floodlight type optical displacement meter of the measuring device and its operating mechanism. (Main reference numbers) lO...Pipe end, 12...Joint, 14...Threaded part, 16
... Tuning fork-shaped cage, 18 ... Tube, 20 ... Taper guide, 22 ... Frame, 26 ... Chaser, 30 ... Floodlight type optical displacement meter 32 ... Traverse amount measuring device Patent applicant Sumitomo Metal Industries, Ltd. Company Representative Patent Attorney Masahiko Arai

Claims (1)

[Claims] Fixed at a predetermined distance with respect to the thread cutting tool so as to face the thread cutting surface of the thread cutting tool for pipe thread cutting, and measuring the position of the pipe surface on the opposite side to the thread cutting surface of the pipe. It is equipped with a light-emitting optical displacement meter and a traverse amount measuring device that measures the amount of displacement of the thread cutting tool in the tube axis direction, and the light-emitting optical displacement meter measures the amount of displacement of the tube end during pipe thread cutting. A pipe characterized in that, when a predetermined displacement of the thread cutting tool in the pipe axial direction is detected by the traverse amount measuring device after detection, the wall thickness of the pipe thread portion is measured based on the measurement value by the displacement meter. Thread thickness measuring device.