JPS5913701B2 - Sensor block for scanning the outer surface of inspected materials with a circular cross-sectional shape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a sensor for scanning the outer surface of a material to be inspected having a circular cross-sectional shape, such as a round billet, a round bar, a circular tube, or a carbon electrode rod, for the purpose of flaw detection, etc. Regarding blocks.

Conventionally, when detecting surface flaws on a round billet made of steel, for example, the sensor is moved in the length direction of the round billet that is rotated around its axis to scan the round billet surface in a spiral pattern. For example, magnetic flaw detection probes and eddy current flaw detection coils are attached to sensor blocks that touch the outer surface of the round billet and move in the length direction, and are controlled by this sensor block to respond to bends in the round billet. There are 35 people.

As this type of mechanism, for example, Japanese Patent Publication No. 19799/1979 discloses that in order to maintain a constant gap size between the sensor and the outer surface of the material to be inspected at the end portion of the material to be inspected, a space is provided before and after the sensor. When the leading roll of the short rolls installed comes off the end of the material to be inspected, the receiving member supported by the fixing member supports the leading end of the sensor block from below, and the trailing roll is separated from the trailing roll. Sensors are known in which the sensor is held in place by a receiving member. However, as is often experienced with round billets and steel pipes, in the case of abnormally rolled materials, especially those with curved ends, if there is a curve b in the portion closer to the end than the trailing roll, it will be affected by the rotation. The bent part rotates eccentrically and approaches and moves away from the sensor as it rotates, causing periodic changes in the gap between the bottom surface of the sensor and the surface of the material to be inspected, which adversely affects the measurement results. However, depending on the degree of bending, the sensor may be destroyed by the edge of the material to be inspected. In addition to the bends at the ends mentioned above, ordinary round billets and steel pipes always have uneven bends and waviness that occur during the manufacturing process, so the rotation conditions of the inspected material may vary from one piece to another. Therefore, it is an extremely difficult task to adjust the position of the receiving member so as to obtain a predetermined inspection accuracy with respect to the pattern of change in gap size, circumferential speed, etc. Further, when the material to be inspected is, for example, a rolled round billet material, if a fin-like oval protrudes near the end of the material, the sensor may be destroyed by this oval.
There is also a known device, as disclosed in Japanese Patent Application Laid-Open No. 49-111689, in which a spiral spring type balancer is used to make the sensor block stand in the axial direction of the material to be inspected. Since a strong function cannot be ensured at the end, a large non-inspection area is created near the end, and if the curvature of the material to be inspected becomes too large, it becomes impossible to follow the test material in the direction perpendicular to the axial direction.

This invention was made in view of the above-mentioned situation, and is particularly effective in following the bending of the inspected material, keeping the gap between the lower surface of the sensor and the surface of the inspected material constant, and preventing abnormalities on the surface of the inspected material. We provide a sensor block that prevents the sensor from being destroyed due to its shape or edges, minimizes the non-inspected portion at the edges, and simplifies adjustment work when changing the size even when the outer diameter of the material to be inspected changes. The purpose is to

An embodiment in which the present invention is applied to a round billet eddy current type surface flaw detection device will be described in detail with reference to the drawings as follows. FIG. 1 is a perspective view showing the overall structure of a round billet surface flaw detection apparatus according to an embodiment of the present invention, and FIG. 2 is a front view of only the flaw detection line.

In FIGS. 1 and 2, reference numeral 4 denotes a rear table of Shotplast as preliminary equipment, which is connected to the flaw detection equipment via a rope transfer 5 and a chain transfer 6. The flaw detection equipment includes an end face matching table equipment 7 and a turning roller table equipment 8 that are installed in parallel, and a flaw detection rear table 9 that connects to downstream equipment, such as a grinder equipment, is also installed in parallel.

In order to transfer the round billets traversely transferred by the chain transfer 6 one by one to the end face matching table equipment 7, from there to the turning roller table equipment 8, and then to the rear table 9, the flaw detection equipment is equipped with these devices. A scratch tractor 10 that moves orthogonally to the table equipment is provided. The end face alignment table equipment 7 is provided with a fluid pressure cylinder piston device 11 for pushing one end face of a billet carried in and aligning the end face at a predetermined position. A support girder 12 as a fixed frame is installed above the turning roller table equipment 8, and this girder 1
Two carts 13a and 13b are movably suspended on the top of the vehicle. The trolleys 13a and 13b respectively suspend sensor blocks 14a and 14b according to the present invention so as to be movable up and down directly above the turning roller table equipment 8 via a fluid pressure cylinder piston device 3 as a pressurizing device. As an extension of the turning roller table installation 8, a calibrating turning roller arrangement 15 is provided in the area of the girder 12, in which the characteristics of the sensor are calibrated. In the illustrated embodiment, two carts 13a, 13b are mounted on the support girder.
is suspended, and the sensor blocks 14a and 14b of each truck inspect half of one round billet for flaws, including a small amount of overlap, thereby halving the time required for flaw detection over the entire length.

The left end of the round billet 1 in the figure is aligned at a predetermined position using the end face alignment table equipment 7, and the length is measured at the same time. Then, it is transferred in parallel to a turning roller table facility by a scratch tractor 10 and rotated at a predetermined constant circumferential speed. The support girder 12 is provided with position detectors (not shown) at multiple locations corresponding to the predetermined position and in the middle, and one of the carts 13a is located at the predetermined position on the left end detected by the position detector. , and the other trolley 13b is stopped at a position to the left of the central position detected by a position detector at one of a plurality of intermediate positions selected based on the length measurement result by a predetermined overlap. , it enters a standby state for flaw detection to start. The sensor block, which is suspended by the carts 13a and 13b so as to be able to rise and fall, is pressed into contact with the surface of the round billet in the above-mentioned standby state, and as the round billet rotates, the end portion is inspected for more than one revolution to reduce the number of undetected portions at the end. Then, by moving the cart to the right, the entire outer surface of the round billet is scanned in a spiral manner. As shown in FIGS. 3 and 4, the basic structure of the sensor block consists of an elevator shaft 16 connected to a piston rod of a hydraulic cylinder piston device 3 attached to a truck, and a lift shaft 16 for guiding the truck up and down. guide shaft 1
A support base 18 is provided which is suspended from the trolley by means 7, and the base 18 is capable of sliding in a horizontal direction perpendicular to the direction of travel of the trolley by means of a slider 19 consisting of a slide bearing in order to follow the bending of the round billet. slide board 2
0 is attached to the slide board 20, a stiff board 22 is suspended from the slide board 20 by a coil spring 21 as a first elastic member, and another spring 2 as a second elastic member is suspended from the board 22.
The sensor holder 25 is suspended by a bamboo spring 3 (bamboo spring) via a hinge portion 24.

That is, the sensor holder 25 is rotatable at the hinge portion 24 in a vertical plane along the direction of carriage movement with respect to the base 18. Moreover, the pressing force from the lifting and lowering pressing shaft 16 is reduced by the springs 21 and 2.
3 and can be pressed against the round billet 1. Axis 2
6 is a guide shaft fixed to the hinge part 24 at the lower end;
It is slidably inserted into the substrates 20 and 22.

At the front and rear of the base plate 22, there are guide wheels 27, 27 and 27', 27' spaced apart from each other on both sides in the direction of movement.
A pair of broken wheel devices 2, 2'/) - installed,
As shown in FIG. 4, each pair of guide wheels is pressed against both sides by the pressing force of the cylinder piston device 3, with the top of the outer circumferential surface of the round billet in between.

Four guide wheels 27, 27, 27', 27' (: The sensor holder 25 located inside the enclosed area is provided with rolling wheels 28, 28 at its front and rear, and The cylinder piston device 3 is arranged so that the gap size between the eddy current flaw detection coils 29a, 29b to 29h and 30, the lower surface of the distance detection coil 31, and the surface of the round billet is kept constant at, for example, 5 cm.
It is pressed against the surface of the round billet by the pressing force of .

Each coil is fixed to the sensor holder 25 by a holder 32 made of non-magnetic material, and another proximity switch 33, 34 is attached to the front of the sensor holder 25 at a predetermined interval, and It is designed to detect the position of the part. In the configuration of the sensor block described above, for example, when the curved round billet 1 is rotated, it can be considered that its center 0 revolves along a broken line trajectory as shown in FIG. The pressing force applied by the fluid pressure cylinder piston device 3 is F
Let w be the suspension load of the shaft 16 of the short wheel device, sensor holder, support base, slide board, short board, etc., and furthermore, a reaction force is applied to the cylinder piston device 3 by pressing the guide ring against the round billet. When the force opposite to the applied F is Fc, F-W-Fc...
...(1).

When the magnitude of this force F, the contact angle α between the guide ring 27 and the round billet 1, and the lateral movement resistance Fs of the slider 19 satisfy the following equation (2), the left and right resistance to bending by the guide ring 27 is will be fulfilled. FcOtα〉Fs・・・・・・
(2) However, formula (2) ignores the rotational frictional resistance between the guide ring and the round billet. Further, it is possible to follow the acceleration V up to the vertical movement. (
(where g is the gravitational acceleration), that is, the downward force F as shown in Fig. 5 causes a reaction force N in the direction of the angle α on the guide wheel that contacts the round billet at an angle α, and a friction force μN in the direction perpendicular to it.
are generated, and an inward force FcOtα that balances these forces is generated. Therefore, when FcOtα>Fs, F=Nsinα−
If μNcOsα is ~ μ<<l, then F=Nsinα, and the substrate 22 can move left and right with an acceleration determined by FcOtα−Fs. The diameter and interval dimensions of the guide ring 27 and the cylinder piston device 3 are adjusted to meet the above conditions.
The stroke of the slider 19, the stroke of the slider 19, etc. are determined by taking into account the outer diameter of the material to be inspected, the size of the bend, the rotational speed, the weight of the sensor block, various frictions, etc. The same device performs testing on materials to be inspected within a certain outer diameter size range.

In this case, in order to prolong the life of the guide ring and bearings that come into contact with the material to be inspected and obtain stable operation over a long period of time, the cylinder-piston device 3 reduces the contact pressure between the guide ring and the material to be inspected so that the movement of the guide ring and the bearings used is extended. Negative pressure may be generated to reduce the pressure to the limit obtained. For example, if the sensor block is supported in a hanging manner and its entire weight is applied to the point of contact between the guide wheel and the round billet, and the weight becomes even larger due to its fleeting motion, the above-mentioned cylinder-piston device will generate Pressure is an upward force that pulls up the sensor block. This power F
The extent to which c' should be determined is determined by the piston friction force FPL of the cylinder piston device 3, the maximum bending amplitude A1 of the inspected material, the rotation speed n (Rpm) of the inspected material, and the range in which the following equation (4) is satisfied. If inside, contact between the inspected material and the guide ring is maintained.

The cross-sectional external shape of the material to be inspected is not necessarily a perfect circle, and there are various abnormal shapes as described below, so there is a limit to the size of Fc', but pressure control using equation (4) above Therefore, wear on equipment such as guide wheels and pairings caused by contact pressure is significantly reduced.

The round billet 1 usually has a concave oval 35a or a convex oval 35b as shown in FIG. At the same time, the rolling wheels 28, 28z follow the oval and maintain a constant gap just below the coil, so the coil will not be damaged by the oval protrusion and the gap between the coil and the billet outer surface will always remain constant. is maintained, and no change in detection characteristics occurs. Further, at one end of the holder 25 on the round billet end side, a protector 36 is provided that protrudes downward from the lower surface of the coil and is positioned above the lower end of the rolling wheel, so that the rolling wheel 28 is secured at the round billet end. This prevents the coil from being damaged by the edges of the round billet when it falls. First and second proximity switches 33 and 34 are provided to detect the round billet end before the coil, and when the first proximity switch 33 detects the billet end, it changes the cart moving speed. When the second proximity switch 34 detects the billet end after further deceleration, a predetermined time limit is given so that the bogie stops with the rolling wheels 28 resting on the billet end as much as possible. A sequence is created.

On the other hand, in order to maintain a constant gap between the lower surface of the coil and the surface of the round billet even if the leading guide ring comes off from the end of the round billet, and to perform surface flaw detection while bending, the As shown, other guide wheels 27//, 2715, similar to guide wheels 27, 27', may be mounted on the separate base plate 22, located on both sides of the sensor holder, or at least on one side thereof. In this case, the leading side guide wheel 27
, 27 is removed from the end of the round billet, the guide wheel も7/
T27//G27', 27' protect against bending, and a predetermined surface flaw detection is performed until the rolling wheel 28 on the leading side exceeds the end of the round billet. The inspection portion is an extremely small portion corresponding to the distance between the rolling wheel 28 and the first coil 29a. The basic configuration of the flaw detection circuit is as shown in Figure 8, with eddy current flaw detection coil 2
An alternating current signal from a reference frequency signal generator 37 is applied to 9 via an amplifier 38 to generate an eddy current in the round billet, and a change in the eddy current due to a flaw is detected as a change in coil impedance. A flaw detection output signal is obtained from 39, and 40 shown in FIG. 8 is a phase shifter that provides a synchronizing signal for phase detection.

In this case, the input voltage of the reference signal to the amplifier 38 is Ein
When the coil impedances are Zl and Z2, the output signal EOut is as follows.

However, according to the above formula, G is the gain of the amplifier 38. By appropriately selecting the values of the coil impedances Z1 and Z2 in the reference state, the feedback ratio of the amplifier circuit can be changed, and the amplifier 38
By changing the degree of amplification and the flaw detection phase, the range in which an output with good linearity with respect to the flaw depth can be obtained changes. Therefore, for example, the flaw detection coils 29a to 29h are set as coils for small to medium flaws that can obtain linearity at a flaw depth of 5 wm or less, and the flaw detection coil 30 is set as a coil for large flaws that can obtain linearity at a flaw depth of 5 m or more. If set as , the extent of the flaw can be identified. Since the shape of the coil also changes the above-mentioned characteristics, it is possible to make only the coil for large defects large.The distance detection coil 31 is connected to a distance detection circuit that performs linear detection instead of phase detection in the circuit shown in FIG. The output is used as a control signal in an automatic gain control amplification circuit (AGC circuit) downstream of the detector output shown in FIG.

In the embodiment shown in FIG. 3, for example, if the width of each of the coils 29a to 29h is 18 m and the total width is 144 Tan, the flaw detection pitch is set to 135 Tfm, that is, the flaw detection lap rate is set to (144-135)/1442. 0.06 (6%)
Then, when the circumferential speed Vr of rotation of the round billet by the turning roller is kept constant at 500 TWL/Sec, the cart moving speed v is determined by the outer diameter d (m) of the round billet as shown in the following equation.

A control device is provided in the cart drive system to automatically control the moving speed of the cart by setting the outer diameter of the billet carried in based on this calculation formula.

As shown in FIG. 4, each of the sensor blocks 14a and 14b has a nozzle 41 for spraying marking paint supported by, for example, a holder 25 and directed onto the surface of a round billet a predetermined distance behind the coil. The above-mentioned predetermined dimensions are determined according to the circumferential speed of billet rotation by the turning roller, and the position detected by the coil is located directly below the nozzle after a delay time of the signal system and the actuation system. For example, when the coils 29a to 29h for small and medium defects detect a defect, white paint is sprayed from a nozzle installed at a position corresponding to the coil, and the coil 30 for large defects is sprayed with white paint. When it detects a flaw, red paint is sprayed from another nozzle installed at a position corresponding to the coil. Conduit 42 connected to nozzle 41 in FIG. 4 is a paint conduit, and conduit 43 is a compressed air conduit. A paint tank and a pump are connected to the paint conduit 42 via a solenoid valve (not shown), and a compressed air source is connected to the air conduit 43, which also functions to constantly blow out air and remove dust, etc. from the surface of the round billet. . The electromagnetic valve is actuated by the flaw signal detected by the coil, and paint is supplied to the nozzle. When the detected flaw arrives just below the nozzle, the paint is sprayed from the nozzle. As described above, according to the sensor block of the present invention, the sensor performs a gentle operation by following the bending of the object to be inspected, which has a circular cross-sectional outer shape, and even if there are irregularly shaped protrusions or recesses, the sensor The gap size between the lower surface and the surface of the object to be inspected can be kept constant, and the sensor can be prevented from being destroyed at the edges of the object to be inspected, and the non-inspected portions at the edges can be reduced. By adjusting the pressing force of the sensor block, objects to be inspected with various external shapes can be handled, and there is no need to readjust the guide ring interval, so extra work when changing the sipe can be omitted.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a surface flaw detection apparatus according to an embodiment of the present invention, FIG. 2 is a front view of the same, FIG. 3 is a front view of a sensor block, and FIG. 4 is an arrow indicated by the - line in FIG. View, 5th
The figure is a functional explanatory diagram of the broken wheel device, Figure 6 is an end view showing the oval of the round billet, Figure 7 is a plan layout diagram showing another example of the guide wheel arrangement, and Figure 8 is a flaw detection circuit diagram. be. 1: Inspected object (round billet), 2: Breaking wheel device, 3: Fluid pressure cylinder piston device, 7: End face matching table equipment, 8: Turning roll table equipment, 10: Extractor, 11: Fluid pressure cylinder piston Device, 12: Support girder, 13a, 13b: Cart, 14a, 14b: Sensor block, 16: Lifting press shaft, 18: Support base, 1
9: slider, 20: slide board, 22: short board,
21, 23: Spring, 24: Hinge portion, 25: Sensor holder, 27, 27: Guide wheel, 28, 28: Rolling wheel, 29a
, 29b to 29h, 30: flaw detection coil, 31: distance detection coil, 33, 34: proximity switch, 41: nozzle.

Claims (1)

[Claims] 1. In a sensor block that scans the outer surface of a material to be inspected by sitting astride the material to be inspected, which is rotated around an axis in the longitudinal direction and has a circular cross-sectional outline, a support base supported by a fixed pedestal and a A slide base is attached to the support base so as to be slidable in a direction perpendicular to the length direction of the test material, and a slide base is slidably attached to the support base in a direction perpendicular to the length direction of the test material, and the slide base is in contact with the outer surface of the test material at intervals in the direction of sliding and rolls by the rotation. A dead ring device consisting of two guide wheels, and a pair of said hard wheel devices supported with an interval in the length direction of the material to be inspected, and a first one in the direction of pressing the broken wheel device against the material to be inspected. a short base plate coupled to the sliding base plate through an elastic member; and a shaft oriented in the pressing direction through the second elastic member and in the sliding direction within the space between the pair of short wheel devices. A sensor holder is rotatably connected to the thin substrate, and the distance between the lower surface of the sensor attached to the center of the sensor holder and the surface of the material to be inspected is maintained at a predetermined value. A rolling wheel is attached to each longitudinal end of the sensor holder within the interval between the wheel devices and rolls in contact with the surface of the object to be inspected as it rotates, and presses the support base. a pressurizing device for pressing the guide wheel and rolling wheel against the surface of the material to be inspected via the sliding substrate, the fragile substrate, and the first and second elastic members; Another guide wheel that rolls in contact with the surface of the material to be inspected is supported by a small substrate on at least one side of the section, and the fixed frame is directly above the turning roller equipment that rotates the material to be inspected. The support girder is constructed in such a way that the support base is suspended from a truck movably suspended on the girder, and the pressurizing device is constituted by a fluid pressure cylinder piston device supported by the truck, A sensor lower surface protection fitting having a bottom surface protruding below the lower surface of the sensor and located above the lower end of the rolling wheel is provided between the sensor and the rolling wheel at least on one end. Sensor block for scanning the outer surface of the inspected material.