JPS5862505A - Measuring device for screw element - Google Patents

Abstract

PURPOSE:To improve resolution and to enable to perform a high-precise measurement of a screw element, by using an optical system which limits a visual field of a two-dimentional photographing device. CONSTITUTION:A steel pipe 10, which has a screwed outer periphery, is located in a horizontal manner, light is radiated from one side by an illuminating lamp 27, and a two-dimentional photographing device 11, such as a television camera, is situated at the other side. Through location of mirrors 21-24 between the television camera 11 and the steel pipe 10, the photographing visual field of the television camera 11 is limited to upper and lower outer edge parts 10a and 10b (a part including screw thread) of the steel pipe 10. A picture photographed by the camera 11 produces a picture signal by means of a television camera controller 12, it is displaced by a monitor 13, and simultaneously, it is inputted to a picture processor 14. Position data of a bright and dark boundary part for showing a screw shape can be obtained in the processor 14. A computing device 15 prints and records computing results of the screw element by means of a printer 16, and meanwhile, in case computing results of each element is out of an allowable tolerance, an alarming device 17 is actuated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the measurement of screw elements, and particularly proposes an optical measuring device that can improve measurement accuracy.

A thread is formed on the outer circumferential surface of the end of a steel pipe used as an oil country tubular pipe for threading connection with a joint for connection to another steel pipe. This threaded part needs to be inspected to ensure that its lead, hide, taper, and other threaded elements meet API standards. Generally, the method of measuring dimensions using a gauge is widely used to measure screw elements, but this method often relies on manual labor, has difficulty keeping up with production capacity, and has the problem of having to rely on sampling inspections. In addition, there is a time lag between the thread cutting work and the inspection work, which delays the discovery of defective products, resulting in problems such as a large amount of oil country tubular goods being repaired during this work or becoming defective. As a means of solving this problem, multiple contactors that are movable in the radial direction are brought into contact with the peaks and valleys of the screw, and their positions are detected by a position detection means such as a differential transformer connected to the contactors. A device that measures screw elements based on the detection results has been developed and is on the market, but there are only a few measurement and inspection items, and the device is large, making it difficult to install it on existing lines with limited floor space. Moreover, there is a problem that it is extremely expensive.

The present invention has been made in view of certain circumstances, and
It is an object of the present invention to provide a screw element measuring device that can perform measurements with higher precision than by using a two-dimensional imaging device such as a television camera, an optical system that limits the field of view, and the like.

The present invention will be specifically described below based on drawings showing embodiments thereof.

FIG. 1 shows the overall configuration of the apparatus of the present invention.

A steel pipe 10#i for oil country tubular goods having a threaded outer peripheral surface is held in a horizontal position by a chuck or the like (not shown).

On one side of this steel pipe 10, a television camera 11 is directly facing with its optical axis aligned with a horizontal plane passing through the pipe axis, and the horizontal and vertical fields of view are aligned with the actual horizontal plane so that the imaging field of view is vertically elongated. , vertical and inverted.

Mirrors 21, 22' and 23, 24, which are interposed between the television camera 11 and the steel pipe 1.0, are used to limit the imaging field of the television cuff 1 to the outer edge of the screw.
is the same height as the upper edge of the steel pipe lO and the lower edge of the -22H steel pipe 10, and the steel pipe lO is tilted at 45 degrees with respect to both the horizontal and vertical.
It is facing the direction of O.

@23 is directly below −21, and mirror 2 is directly above mirror 22.
4 are placed opposite each other so that their respective mirror surfaces are parallel to the mirror surfaces of mirrors 21 and 22, and the images reflected on these mirrors 23 and 24 are captured by a television camera IIK. By arranging the mirrors 21 to 24 in this manner, the field of view of the television camera 11 is as shown in FIG.
It will be limited.

Reference numeral 27 denotes an illumination lamp, which is designed to illuminate the steel pipe IO from the side opposite to the television camera 11.

As a result, the television camera 11 can capture the upper and lower outer edge portions 10a of the steel pipe 10, as schematically shown on the monitor 13.

10b is perceived as a locally projected image in which the steel pipe is dark and the background is bright.

Note that the television camera 11111jK may be provided with an illumination light to simultaneously image the steel pipe brightly and the background darkly.

FIG. 3 shows the interlocking adjustment mechanism of #'i mirrors 21 and 22 from the steel pipe 10 side.

-21 to 24 are appropriate mirror frames 210.220.230.2
A guide tube 211, 221 is attached to one side of the lens frame 210, 220 with its axis vertical, and a threaded tube 212 with a thread on the inner surface is attached to the other side.
, 222 are housed with their axes vertical.

The guide tubes 211 and 221 are slidably fitted into a guide column 251 which is a vertical column on one side of the Fi support member 25, and a feed screw 252 provided parallel to and opposite to the guide column 251. Threaded tubes 212 at the top and bottom respectively
and 222 are screwed together. The upper and lower threads of the feed screw 252 are reversely threaded, and the middle part has no thread, and a support tube 232, 242 formed on one side of the lens frame 230° 240 is provided in this part. It is a game chart. The other end of the lens frame 230 and 240 is fixed to the guide column 251. A pulse motor 26 is attached to the lower end of the feed screw 252.
are connected to each other, and the feed screw 252 is rotated a predetermined number of times by driving the l step. This allows the upper -21
And the bottom lol! 22 and move away from each other by the same size.

Therefore, by driving the pulse motor 26, the television camera 1
The imaging field of view 1 is moved in parallel, so that the field of view can be easily adjusted according to the diameter of the steel pipe.

A television camera controller 12 outputs an image signal corresponding to an image taken by the television camera 11-. This image signal is input to the image processing device 14, where data specifying the position of the bright/dark boundary region for each horizontal scanning line is obtained, and this data is read into the arithmetic device 15.

Needless to say, the position specifying data of the bright and dark boundary region is a data group representing the shape of the projected image of the screw.

The calculation device 15 calculates the thread element based on this data group, but since the steel pipe 10 is stationary, data input for one screen is sufficient. The arithmetic unit 15 prints and records the thread element calculation results using the printer 16, and activates the alarm 17 if the calculation results for each element are outside the allowable tolerances.

Next, an outline of the calculation method for each element will be explained. The arithmetic device 15 temporarily stores the data read from the image processing device 14 in the memory, but the contents are in a trap as shown in FIG. In other words, the data Li on the outer edge of the screw projection image on the left side of the screen (the part where the image signal changes from the white level to the black level) and the outer edge of the screw projection image on the right side (the part where the image signal changes from the black level to the white level) with one K on the horizontal scanning line number laminate. data Ri (the part that changes to the level). The calculation is performed in the next step by reading out these data. These data L
As shown in FIG. 5, on the monitor 13, l*R1 is data corresponding to the dimensions from the left side of the screen (to be more precise, horizontal) to each changing portion of the synchronization signal (placement force, etc.).

(1) For the i grain horizontal scanning line, one @tlt
Di-difference from the first data L i -1 I Li
Li-1l is calculated sequentially, and the predetermined level,
Example 1E11' Compare the actual size with the value equivalent to 1 opes.

(2) Assuming that the smaller part is the flat part of the LLIms or troughs of the screw, find the horizontal scanning line number located at +6 in that part.
If the wood grain data satisfies that condition, then the force 1 ra− (= j−
4-(k-j+t')/2 or c=(k+j+1)
/2. This C is IIJ 8rs as shown in Figure 5.
(or trough), and C obtained for the Butha 0 loop which became IL:Li-1 giant 10 Ha after Mfl due to j+1~ is conversely the center of the trough (or LIJ sub). In other words, the horizontal scanning numbers for specifying the centers of peaks and valleys are alternately determined.

The odd-numbered C calculated in this way is C,
, C, , C, . . . C0 . Store as shown. As can be understood from the above, 1 For example, the calculated value of an odd number is at the center of the valley, and the calculated value of an even number is at the center of the mountain.0 (3) Next, the 1 value at co and ce tco t Lce
is calculated and written to memory in correspondence with each C0, Ce.
nothing. If C0, C, is an integer value, the Li value of the corresponding horizontal scanning line is used as is; otherwise, it is calculated by proportional calculation based on the Li values of the horizontal scanning lines before and after it.

With the above, the pipe diameter direction position 1d of the center of the thread ridges and valleys can be identified.

(进 Next, lead calculation processing begins. This is calculated as the difference between successive Cs. In other words, the ``valley'' is C, -C.

C, -C.

C02C0-8 et ◆* -C6 Pressing like this, the mountain lead again C, -C.

C, C.

Ce Ce-x C@+z　C4 Find each as follows.

(5) Next, the Hyde calculation process begins.

Tani Hyde is C0. Li value in C and K.

. Find the individual /Site using the LceO difference.

That is, LC2-LcI LC3tex LC4-LC3 tco tce Find it by applying pressure.

(6) Next, enter taper calculation processing. This is determined individually as the difference between successive LCOe or Lce.

That is, the taper of the valley is LCa-Lct LCs LCO LCOLe・-Snow Lc. Tomi-LC (1 So, the taper of Mt. Lea Leg tcs tea’ LCO-LCe-1 L(@＋＊　Lcs It is highly sought after as K.

The above-mentioned processing is similarly carried out for the data cap on the right side. Then, for the numerical values calculated for each screw thread as described above, including both the left and right sides, an algebraic average value is determined, and this is used as the lead, hide, and taper. Buri・
It goes without saying that the printer 16 may also print out the individual calculation results, the average value for each right and left side, etc.

In the apparatus of the present invention, the thread element is calculated based on the thread shapes at two positions symmetrical with respect to the tube axis. This is important in improving taper measurement accuracy when the horizontal scanning line of the captured image and the steel pipe axis are not exactly perpendicular. That is, the optical systems of the television camera 11 and the mirrors 21 to 24 are stabilized tt, and the steel pipe IO is also positioned by the chuck, but the axis of the pipe is adjusted to an accuracy of ±20 tones according to the thread element management standard of the API standard. Measure the taper of
It is difficult to position it strictly horizontally (or perpendicularly to the horizontal scanning line direction of the television camera 11) so as to achieve 1iT performance. However, as in the present invention, two
When data processing is performed based on the projected image of the position, the taper errors included in each individual screw due to the inclination of the axis from the horizontal are averaged for the left and right ones K. It will be canceled out.

:1 (7) Next, the bevel calculation process will be explained. The bevel is the angle β of the tapered portion of the threaded end with respect to the axis, as shown in FIG. This process converts Ll to a predetermined number of data Ll+k from the tube end side (upper side of the monitor). .

...Lll (however, the value of vm-/ is set so that ll is a value within the range of the taper part, the so-called bevel part) is read out sequentially, and based on these data, the least square method is used. Calculate the inclination a of the taper part in the orthogonal coordinate system on the imaging plane (or monitor image plane), and β = tmll
Calculate the bevel as l.

Such processing is also performed for the data Ri on the right side,
Find the average of the bevel obtained for the data on the left. In this case as well, the error due to the inclination of the tube axis from the horizontal is canceled out by taking the average of β determined based on both data.

As described above, the screw element measuring device according to the present invention is arranged between a two-dimensional imaging device, the two-dimensional imaging device and the screw, and
an optical system that limits the imaging field of view to a region that includes the outer edge portions at two different positions in the circumferential direction of the screw; and an arithmetic device that calculates screw elements based on image signals from a two-dimensional imaging device. Since it is equipped with
It can be installed even in narrow spaces, and can be attached to existing oil country tubing inspection lines without any problems. By limiting the area to be imaged for image processing to the area where the projected shape of the screw appears, the middle part of the tube is not needlessly imaged, and the resolution can be improved accordingly, making it possible to perform highly accurate measurements. Become.

Moreover, the resolution can be maintained at a substantially constant value regardless of the size of the pipe diameter. Furthermore, as mentioned above, even if there is a slight deviation in the relationship between the tube axis and the imaging device, that is, even if the tube axis takes a strictly horizontal position, this will cause measurement errors in taper and bevel. There is no. Furthermore, since the apparatus of the present invention can quickly and automatically perform measurements without requiring any manual labor, the inspection speed can be made to follow the production efficiency of steel pipes, making it possible to perform complete failure inspections.

The device f of the present invention can be provided at a significantly lower cost than the conventional self-help measuring device described above.

Furthermore, when the mirror 21 and the mirror 22 are constructed so that they can approach and separate from each other as in the above-mentioned embodiment, the uj4 of the present invention has many advantages, such as being able to quickly cope with the measurement of tubes with different diameters. It has a great effect.

It goes without saying that the present invention can be applied to external threads.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, in which Figure 1 is an overall configuration diagram of the apparatus of the present invention, Figure 2 is an explanatory diagram of the imaging field of view,
FIG. 3 is an elevational view of the interlocking adjustment mechanism of mirror #i, FIG. 4.6 is a conceptual diagram of memory contents, and FIG. 5 is an explanatory diagram of data LI and R1. DESCRIPTION OF SYMBOLS 11... Television camera 12... Television camera controller 13... Monitor 14... Image processing device 15... Arithmetic device 21-24... Mirror frame permission
Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney
Noboru Kono/(/7 Sai 2 Zuho 3 (2) 'Ik 4 Answer 5 l: Hibiki No. 6

Claims (1)

[Claims] 1. A two-dimensional imaging device, and an optical device disposed between the two-dimensional imaging device and the screw, which limits the imaging field of view to an area that exclusively includes the outer edge portions at two different positions in the circumferential direction of the screw. system and
1. A screw element measuring device comprising: an arithmetic device that calculates a screw element based on an image signal from a two-dimensional imaging device.