JPS62450B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a metal tube that can automatically and accurately detect inner surface flaws of metal tubes in both hot and cold conditions, regardless of temperature changes. This relates to a tube inner surface flaw detection device.

For example, the inspection of the inner surface of a seamless steel pipe immediately after rolling has conventionally been carried out by placing combustible material into the pipe, illuminating the inner surface of the pipe with a flame generated by the combustible material, and visually inspecting the inner surface of the pipe. After cooling, internal flaws were detected using automatic inspection equipment using the magnetic flux leakage method.

However, in the above-mentioned visual inspection by workers, it is difficult to see deep into the tube if the tube is small in diameter, and the rolling cycle time is usually short, ranging from several tens of seconds to several tens of seconds, so 100% inspection is extremely difficult. Since it requires a lot of labor, it is practically impossible and has to rely on sampling inspection.As a result, the timing of detecting lap defects due to poor rolling conditions such as roll gaps and defective tools is delayed, and countermeasures are taken. It was not possible to promptly take measures such as adjusting the roll gap or changing tools, which was an impediment to improving yield. In addition, since the automatic inspection device is used after the tube has cooled, it is not possible to promptly take measures based on flaw detection, and the conventional device has a dead zone near the end of the tube. Inspection for flaws near the edges was insufficient, and if a flaw was overlooked during visual inspection, the product would be defective.

From the above-mentioned viewpoint, the present invention automatically removes defects on the inner surface of metal tubes in any hot or cold state, regardless of temperature changes, and regardless of the location, such as at the end or middle of the tube. The present invention provides a metal tube inner surface flaw detection device capable of accurately detecting flaws on the inside surface of a metal tube. A rotatable inner cylindrical body having one end protruding from the end of the outer cylindrical body and the other end protruding into the box body within the cylindrical body, the tube being inserted concentrically with the metal tube; A probe that is movable in the axial direction, a laser oscillation tube, a laser light detector, and an infrared ray detector provided inside the box, and a laser oscillation tube attached to the tip inside the probe head that emits light from the inner tube. a scanning mirror for receiving a beam traveling straight through the body and irradiating it onto the inner wall of the metal tube and receiving the reflected light; and a scanning mirror for receiving infrared radiation from the metal tube; The device is characterized by comprising a half mirror provided within the box body for sending reflected light of a laser beam to the laser light detector and sending infrared radiation to the infrared detector.

Next, the present invention will be explained with reference to examples and drawings.

FIG. 1 is an explanatory diagram showing the arrangement of the flaw detection apparatus and the flaw detection cycle of the present invention. In the drawing, a running line 2 that sends the pipe to be inspected 1 to a flaw detection device is provided with an alignment device 3 at its terminal end, and a cooling table 4 is provided in a direction perpendicular to the running line 2. The pipe to be inspected 1 that has been sent has its end aligned in a fixed position by the alignment device 3, and then is pushed out onto the cooling table 4 by a popping device (not shown), and then the pipe 1 is pushed out onto the cooling table 4. By means of a transfer mechanism (not shown),
Move sequentially.

At one end of the cooling table 4, rails 5, 5' are laid parallel to the moving direction of the tube 1 to be inspected, and a flaw detection device 6 is installed on the rails 5, 5' to detect the movement of the tube 1 to be inspected. They are arranged so that they can move in synchronization.

FIG. 2 shows the configuration of the flaw detection device 6 in an explanatory diagram. Reference numeral 7 denotes a box body that houses the flaw detection device 6. At approximately the center of the side surface 7a of the box body 7 facing the tube to be inspected 1, there is an outer cylindrical body 8 whose interior is cooled by circulation of cooling water or the like. An inner cylindrical body 9 is fixed and has one end protruding from the end of the outer cylindrical body 8 and the other end penetrating the side surface 7a of the box body 7 and protruding into the box body 7. The outer cylinder 8 is rotatably supported by sliding members on the inner surface of both ends, and the probe 10
It consists of Reference numeral 11 denotes a chain for transmitting the rotating force of the inner cylinder, which is suspended around the outer peripheral surface of the protrusion 9a in the box body 7 of the inner cylinder 9, and one end of the chain 11 is connected to the rotation of a motor 12 equipped with a transmission mechanism. body 13
, and the other end is the rotating body 1 of the rotational position detector 15.
Each of them is tied to 4. Therefore probe 1
0, the chain 1 is driven by the motor 12.
1, and its rotational position can be detected by signal processing etc. by a rotational position detector 15.

Reference numeral 16 denotes a laser oscillation tube installed in the box body 7, which oscillates a narrow beam 17a of about 2 mmφ. 18 is a beam 1 in the path of the beam 17a.
A first mirror 19 is located at a position to reflect the beam 7a in the right angle direction, and a second mirror 19 is located at a position to reflect the beam 17a reflected by the first mirror 18 into the probe 10. . 20
receives the beam 17a that is reflected by the second mirror 19 and travels straight through the inner cylinder body 9, and irradiates the beam 17a onto the inner wall 1a of the tube to be inspected 1, and receives the reflected light. A scanning mirror that also receives infrared radiation from the probe head 10a, which is mounted inside the probe head 10a
A beam passage hole 33 is provided at a position where the beam 17a passes by the scanning mirror 20.

21 is a laser photodetector, generally a photomultiplier is used, and depending on the intensity of the laser, a sensor such as a Si cell or the like may also be used. A beam 17a oscillated by the laser oscillation tube 16 and irradiated onto the inner wall 1a of the tube to be inspected 1 through the beam passage hole 33 by the first mirror 18, the second mirror 19, and the scanning mirror 20 is transmitted to the inner wall 1a. The reflected light 17b is reflected by the scanning mirror 20.
The light is received by the

The reflected light 17b received by the scanning mirror 20 is
The reflected light 1 passes through the inner cylindrical body 9 and enters the box body 7.
The laser beam passes through a lens 22 provided in the path of the laser beam 7b, is reflected in a right angle direction by a half mirror 23, is narrowed down by an aperture 24, and then is received by a filter 25 at a wavelength matching the laser beam by a laser beam detector 21. .

26 and 27 are infrared detectors, the first infrared detector 26 is for defect detection, and the second infrared detector 27 is for temperature compensation of the detection result by the first infrared detector 26. It is for measurement. Note that the infrared detectors 26 and 27 are
All have built-in highly sensitive elements such as PbSe, PbS, InAs, etc.

Further, infrared radiation 28 emitted from the inner wall 1a of the tube 1 to be inspected is received by the scanning mirror 20 provided in the probe head 10a, passes through the inner cylinder 9 as described above, and passes through the lens 22 and the half mirror 2.
3 and reflected in the right angle direction by the second half mirror 29, and the first infrared detector 26
The light is received by the

Reference numeral 30 denotes a chopper provided in the path of the infrared rays 28' passing straight through the second half mirror 29;
1 is a photo interrupter, and the above-mentioned chipper 30
is rotated by a chopper motor 32, and the infrared ray 28' traveling straight through the half mirror 29 is chopped. The picked infrared light 2
8' enters the second infrared detector 27, the inner surface temperature of the tube 1 to be inspected is measured, and the signal detected by the first infrared detector 26 is temperature-compensated by the meter.

34 is on the side surface 7a of the box body 7 facing the tube to be inspected 1;
This is a tube body holding arm for the tube to be inspected 1 which is pivotally attached by a pin 37 across the probe 10, and has a roller 35 attached to its tip. Reference numeral 36 denotes a cylinder for driving the tubular body holding arm 34, one end of which is pivotally connected to an intermediate position of the tubular body holding arm 34, and the other end to the side surface 7a of the box body by pins 38, 38', respectively.

The flaw detection device 6 configured as described above runs on rails 5, 5' laid parallel to the direction of movement of the tube to be inspected 1 on the cooling table 4 in synchronization with the movement of the tube to be inspected 1. The said trolley 3 on the trolley 39
A rail 40 provided in a direction perpendicular to the running direction of 9.
It is mounted on a moving table 41 via a vertical centering device 42 that can be raised and lowered. In addition,
The trolley 39 may be driven by obtaining driving force from the moving tube 1 to be inspected, or a separate driving device may be provided. 43 is the wheel of the trolley 39, 44 is the moving platform 41
The wheels 45 are sensors provided at predetermined positions on the rail 40 for detecting the entry position into the pipe.

Next, regarding an example in which flaw detection was performed at the end of the tube to be inspected 1 using the device of the present invention, its operation will be described below.
This will be explained with reference to FIGS. 1 and 2. That is, the tube to be inspected 1 having a temperature of 400 to 800 DEG C. after rolling, which has traveled along the running line 2, is ejected onto the cooling table 4 with its tube ends aligned in a fixed position by the alignment device 3. At this time, the flaw detection device 6 is in a standby position as shown by a in FIG. As the tube 1 to be inspected moves on the cooling table 4, the flaw detection device 6 mounted on the trolley 39 begins to move on the rails 5, 5' in synchronization with the movement of the tube 1 to be inspected. At the same time, the moving table 41 starts moving the rail 40 on the cart 39 in the axial direction of the tube 1 to be inspected. And the second
As shown in the figure, when the holding arm 34 reaches the tube to be inspected 1, the cylinder 36 is actuated, and by adjusting the vertical movement by the centering device 42, the tube to be inspected 1 is moved to the holding arm 34 of the flaw detection device 6. The probe head 10a is held in such a manner that its center and the center of the inner cylindrical body 9 coincide with each other, and the probe head 10a is inserted into the tube from the end of the tube 1 to be inspected, as shown by b in FIG.

As described above, when the probe head 10a is inserted into the tube to be inspected 1, the inner cylindrical body 9 begins to rotate by the chain 11 due to the drive of the motor 12, and the inner cylindrical body 9 begins to rotate. The inner peripheral surface of the tube is scanned by the scanning mirror 20. In this way, the flaw detection device 6 moves in synchronization with the movement of the tube 1 to be inspected, as shown in FIG. It stops when the flaw detection is completed. Then, it begins to retreat as shown in the figure e, and escapes from the tube to be inspected 1, and when the retreat is completed as shown in the figure f, it returns to the initial standby position and becomes ready for the flaw detection of the next tube. .

Next, a mechanism for detecting flaws on the inner surface of a metal tube using this flaw detection device 6 will be explained. As mentioned above, the apparatus of the present invention has a built-in laser detector 21 and infrared detectors 26 and 27, and
When the temperature is low, flaw detection is performed using a laser beam oscillated by the laser oscillation tube 16. That is, when the inner wall 1a of the tube 1 to be inspected is irradiated with a laser beam, a change in the geometric shape of the tube inner surface flaw is detected as the reflectance of the laser beam. Also, the tube to be inspected 1
When the temperature is high, infrared rays emitted from the inner wall 1a of the tube 1 to be inspected are received, and defects on the inner surface of the tube are detected as a state of attenuation of the infrared radiation intensity, that is, a change in the inner surface temperature.

FIG. 3 shows the above flaw detection process in the form of a block diagram. In the drawing, A is a laser light detection system, and the laser reflected light 17b received by the scanning mirror 20 is converted into an electric signal and amplified by the amplifier 46a, and the change in the reflection angle due to the change in the diameter of the tube 1 to be inspected is detected. After performing reflectance compensation 49 using a circuit that obtains an average reflected light intensity 48 using an amplifier 46b and a low-pass filter 47, and improving the S/N ratio using a high-pass filter 50, the influence of the tube inner surface roughness is considered. ,
An AD converter 51 performs AD conversion, and the signal is stored in a signal storage circuit 52.

B in the figure shows an infrared detection circuit, in which infrared radiation light 28 for detecting defects in a narrow area of several mm ² for the first infrared detector 26 received by the scanning mirror 20 is converted into an electrical signal by an amplifier 46c. Width is increased. On the other hand, the infrared radiation light 28' for the second infrared detector 27
After chopping by the chopper 30, it is amplified by the amplifier 46d to become the tube inner surface temperature signal 53, and the infrared radiation light 28 for defect detection is amplified by the amplification device 46d.
Temperature compensation 54 is performed. In this way, the infrared radiation light 28 for defect detection has achieved stable detection ability.
The signal from S/
After improving the N ratio, the AD converter 51 performs AD conversion, and the signal is stored in the signal storage circuit 52.

Further, C in the figure is a rotational position detection circuit, and the rotational position of the probe 10 detected by the rotational position detector 15 is stored in the signal storage circuit 52.

As described above, the laser beam or infrared radiation beam stored in the signal storage circuit 52 is sent to the pattern recognition circuit 55, along with a signal indicating its detection position.
Since the level determination circuit 56 displays the detection results of defects in various shapes, the display control device 57 reconstructs the results into a screen with a shape that can be recognized by humans, and then displays it on the display device 58. .

Next, a display method using the display device 58 will be explained. A CRT is used as the display device 58, and in both the laser light reflection type and infrared type, the results of the flaw detection are displayed on the CRT in the form of an expanded view of the inner surface of the tube. In the case of an infrared type, the display method is the value obtained by dividing the temperature difference by the average temperature inside the tube, and in the case of a laser beam reflection type, it is classified into several levels, for example 8 levels, depending on the amount and size of the reflected light. , depending on the level of light and darkness.
Displayed on CRT. That is, for example, in the case of an infrared type, areas with a large temperature difference are displayed brightly, and areas with a small temperature difference are displayed darkly. Therefore, when there is a flaw on the inner surface of the tube, it is displayed brightly because the temperature difference between the flaws is large, so that the flaw can be easily identified. In this case, a clearer defect pattern can be obtained by highlighting only a specific level, such as the level of temperature difference occurring in a defect.

FIG. 4 shows a specific example of a CRT address. As shown in the figure, the horizontal direction of the CRT is the circumferential direction of the tube, and the vertical direction is the tube axis direction, and the circumference of the tube is divided into, for example, 512 pieces, and when the brightness and darkness of each is displayed, the scanning mirror 20 is attached. Since one rotation of the probe head 10a corresponds to a scanning line in the horizontal direction, for example, by moving the probe head 10a by 3 mm per rotation in the axial direction of the tube, the tube end portion from tube end a to 1536 mm can be scanned. can display defect patterns. Figure 5 shows an example of the inspection results. Figure A shows the occurrence of a mechanical lap flaw 59 on the inner wall of the tube end, and Figure B shows the mechanical lap flaw 59 detected by the device of the present invention. A CRT display example is shown.

In the above-mentioned embodiment, an example of flaw detection at the end of the tube has been described, but it goes without saying that the entire length of the tube can be detected by the same method.

As explained above, according to the flaw detection device of the present invention, defects on the inner surface of a tube, especially defects near the tube end, which was considered a dead zone in conventional automatic inspection devices, can be detected.
It is possible to automatically and accurately detect both hot and cold conditions, and therefore, defects on the inner surface of the pipe can be detected with high accuracy even when there is a large temperature change immediately after rolling. Since it becomes possible to quickly take measures based on the above, the occurrence of defective products is reduced, yields can be improved, and other excellent industrial effects are brought about.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the arrangement and flaw detection cycle of the flaw detection device of this invention, Fig. 2 is an explanatory diagram showing the configuration of the flaw detection device of this invention, Fig. 3 is a block diagram showing the flaw detection process by this inventive device, and Fig. 4 5 is a diagram showing a method of displaying flaw detection results, and FIG. 5 is a diagram showing a similar display example. In the drawings, 1...Pipe to be inspected, 2...Travel line, 3...Alignment device, 4...Cooling stand, 5, 5'...Rail, 6...Flaw detection device, 7...Box, 8... ...Outer cylinder body, 9...Inner cylinder body, 10...Probe, 10a...
...Probe head, 11...Chain, 12...
Motor, 13, 14... Rotating body, 15... Rotation position detector, 16... Laser oscillation tube, 17... Beam, 18... First mirror, 19... Second mirror, 20... Scanning Mirror, 21... Laser detector, 22... Lens, 23... Half mirror, 2
4...Aperture, 25...Filter, 26...1st
Infrared detector, 27...Second infrared detector, 28
...Infrared rays, 29...Second half mirror, 30...
...Chiyotsupa, 31...Photo interrupter, 3
2... Chopper motor, 33... Beam passage hole, 34... Holding arm, 35... Roller, 36...
Cylinder, 37, 38... pin, 39... trolley,
40... Rail, 41... Moving platform, 42... Centering device, 43, 44... Wheels, 45... Sensor, 46... Amplifier, 47... Low pass filter, 48... Average reflected light intensity, 49... Reflectance compensation, 50... High pass filter, 51... AD converter, 52... Signal storage circuit, 53... Tube inner surface temperature signal, 54... Temperature compensation, 55... Pattern recognition circuit, 56... ... Level determination circuit, 57 ... Display control device, 58 ... Display device, 59 ... Mechanical lap defect.

Claims (1)

[Scope of Claims] 1. A box housing a flaw detection device, and an outer cylindrical body fixed to the side of the box facing the metal tube to be inspected, with one end extending from the end of the outer cylindrical body. protruding,
a probe that is inserted concentrically into the metal tube and is movable in the axial direction of the tube, the probe comprising a rotatable inner cylindrical body whose other end projects into the box; A laser oscillation tube, a laser light detector, and an infrared detector are attached to the tip inside the probe head to receive a beam that is emitted from the laser oscillation tube and travel straight inside the inner cylinder, and to irradiate it onto the inner wall of the metal tube. a scanning mirror for receiving the reflected light and receiving infrared radiation from the metal tube; and a scanning mirror for transmitting the reflected light of the laser beam received by the scanning mirror to the laser light detector and for transmitting the infrared radiation. a half mirror installed in the box body to send the laser beam to the infrared detector, and when the metal tube is at a low temperature, the reflected light of the laser beam irradiated onto the inner surface of the metal tube by the probe head. flaws are detected based on changes in the inner surface shape of the metal tube obtained from A flaw detection device for an inner surface of a metal tube, characterized in that a flaw is detected based on a change in the inner surface temperature of the metal tube.