JPH0241582Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a surface flaw detection device for steel plates, and more specifically, it is a type of surface flaw detection device in which an eddy current or ultrasonic flaw detection probe is levitated by a fluid.

(Prior art) Surface flaw inspection of steel sheets in hot strip mills involves inspecting every few ten hot coils immediately after rolling.
A common method is to sample the coil in proportion to the size of a book, unwind part of the coil using unwinding equipment, and visually inspect the coil.

However, because scale is generated on the surface of the hot coil, it is impossible to detect the microscopic defects hidden inside the hot coil. The discovery of defects causes confusion in the process. For this reason, there is a need for a surface flaw detection device that can detect minute flaws in place of human visual inspection.

Eddy current detectors are excellent for detecting flaws on the surface and surface layer of conductors and are used in a wide variety of applications. When detecting flaws using this eddy current detector, the distance between the detection probe and the object to be inspected, ie, the steel plate, is a problem, and it is particularly important to keep this distance constant in order to perform stable detection. As a method for this, a method is used in which the distance is kept constant by arranging a copying roller and arranging a large number of probes between the copying rollers.

The copying roller method is based on the premise of securing a flaw detection area by arranging a large number of detection probes in the width direction, and the diameter of one flaw x number of probes = the flaw detection range in the width direction, so the cost of the detection device is the detection probe. In addition to the problem of being expensive in proportion to the number of rollers, regular maintenance of the rollers is required because the copying rollers are in contact with the surface of the steel plate, and there are also problems of causing scratches. However, JP-A-55-103459 discloses a flaw detection device that takes measures against roller maintenance and scratches, which are one of the drawbacks of the copying roller method. This is a non-contact flaw detection device that maintains a constant spacing between the flaw detection probes, but the number of flaw detection probes arranged is the same as that of the tracing roller method, and the disadvantage of high equipment costs remains unresolved. .

(Purpose of the invention) An object of the invention is to effectively reduce the number of flaw detection probes to be arranged and to provide an inexpensive surface flaw detection device.

(Structure of the Invention) The structure of the surface flaw detection apparatus of the present invention for achieving the above object will be described based on an embodiment shown in the drawings.

That is, a probe rotation drive unit 1, a rotation arm 18 connected to the drive unit 1, a case 7 fixed to the rotation arm 18, and a flaw detection probe 9 opposed to the steel plate surface are built into the case 7. death,
A fluid float section 8 having a fluid passage hole 12' fitted with a fixed pipe 12 that jets high-pressure fluid onto the surface of the steel plate is disposed in the center thereof so as to be movable vertically and horizontally. 8
A small hole 13 that spouts high-pressure fluid toward the outer circumferential position of
This is a steel plate surface flaw detection device configured by providing the following.

To explain in more detail, Fig. 1 is a side view showing the rotary flaw detection mechanism and fluid supply system, and 1 is for the rotary drive.
An AC motor, 2 a speed reducer, and 3 a fluid supply fixed pipe connected to a fluid source (not shown). 4 is a fluid supply rotary joint that supplies fluid from the fixed pipe 3 to the rotating body. 5 is a signal wiring section, and 6 is a non-contact rotating transformer section or slip ring for transmitting and receiving signals from the rotating body. 7,
7' is a fluid float 8 with a built-in flaw detection probe;
8' is housed in a case that can be moved vertically and horizontally, and 17, which is fixed to a rotary arm 18 rotated by a rotary drive AC motor 1 and is placed facing the surface of a steel plate 15, is a case in which the device of the present invention is used to transport hot steel plates. This is a frame for fixing on the line.

FIGS. 2 and 3 are explanatory diagrams showing details of the case 7 attached to the rotating arm 18, the fluid float parts 8 and 8' arranged vertically and horizontally movably inside the case 7, and the fluid floating and fluid support mechanism. It is. The fluid float parts 8 and 8' are cylindrical and have an eddy current flaw detection probe 9 and an AGC detection probe 10 built therein. This is for signal compensation when a change in distance occurs within a short period of time.

11 is a fluid reservoir provided at the bottom of the fluid float section 8. A fixed pipe 12 is connected to the fluid supply pipe 3', and is fitted into a fluid passage hole 12' provided in the center of the fluid float section 8. Reference numeral 13 designates a small hole provided around the case 7, through which high-pressure fluid is ejected toward the outer peripheral position of the fluid float portion 8. A throttle valve 14 adjusts the pressure of high-pressure fluid supplied to a small hole 13 provided around the case 7 via a pipe 16.

The distance between the fixed pipe 12 and the fluid passage hole 12' of the fluid float section 8 is set to 0.5 mm, and the distance between the small hole 13 and the outer periphery of the fluid float section 8 is set to 1 mm.
Therefore, the fluid float section 8 can move up and down, left and right, and tilt within this range.

(Operation of the device) The device of the present invention has the above-described configuration, but when fluid is supplied to the fluid float section 8 shown in FIGS. 2 and 3 through the fixed pipe 12, the supplied fluid is Fluid reservoir 1 via fluid passage 12'
While temporarily stored in 1, it is ejected onto the surface of the steel plate 15,
As a result, the fluid float section 8 receives a levitation force and floats to a certain height. The flying height is related to the size of the fluid reservoir 11, and the larger the diameter and depth, the larger the flying height. Furthermore, fluid reservoir 11
By setting the size optimally, the weight of the fluid float part 8 and the repulsive force with the steel plate 15, and conversely, when the fluid flows out from between the fluid float part 8 and the steel plate 15, negative pressure is created and suction force is reduced. The generated forces are balanced, and it is possible to maintain a constant flying height regardless of the pressure of the supply fluid. Therefore, it is possible to maintain the distance between the eddy current flaw detection probe 9 and the steel plate at an optimum value.

Next, since the device of the present invention uses a fluid to levitate the fluid float section 8 containing the detection probe and rotate it, the centrifugal force caused by the rotation will cause the fluid float section 8 to collide with the case 7 and rotate in a bad posture. However, since vertical movement and horizontal movement are impossible and accurate flaw detection becomes difficult, it is necessary to support the fluid float part 8 within the case 7. When supporting, non-contact support is ideal so that the optimum posture can always be obtained by following changes in the shape of the steel plate. For this reason, the present invention provides a small hole 13 around the case 7,
A non-contact support system is adopted in which high-pressure fluid is ejected from small holes 13 toward the outer circumferential surface of the fluid float section 8 that has floated to a predetermined floating height.

Thus, the fluid float portion 8 is connected to the fluid passage hole 12'.
Since the fixed pipe 12 is fitted with a gap through the pipe, it can be moved up and down and left and right, and since there is a gap between the outer circumference and the small hole 13 of the case 7, the structure allows it to take an inclined position. During rotation, the fluid float part 8 containing the detection probe is fluidly supported against centrifugal force and does not collide with the case 7, so it follows the shape of the steel plate 15 and always maintains an optimal distance and attitude. sell.

(Effect of the invention) The diameter of the detection probe used in this invention is approximately 5 mm, and if it is rotated at a rotational speed of, for example, 500 mm, the required number of detection probes is 1 to 4, depending on the line speed, whereas in the conventional This fixation method requires 100 detection probes (500 mm ÷ 5 mm) when arranged horizontally, and the cost is enormous. Furthermore, since the fluid float part with a built-in detection probe is supported using a non-contact support method of fluid floating and fluid support, the fluid float part follows the shape of the steel plate and can always maintain the optimum distance and posture, eliminating the possibility of micro-defects. can be detected in a short time and with high precision.

In actual use, it is possible to install a plurality of devices of the present invention in parallel in proportion to the width of the steel plate to conduct flaw detection over the entire surface, or it is possible to use only one device that is movable in the width direction. As the fluid, water or air is preferred because it is inexpensive and easy to handle.

Although the above embodiments have described eddy current flaw detection, the present invention can be used for ultrasonic flaw detection by replacing the detection probe with an ultrasonic probe.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with Fig. 1 being a side view showing the rotary flaw detection mechanism and fluid supply system, and Figs. An explanatory diagram showing. 1...AC motor for rotational drive, 2...Reducer,
3...Fluid supply section fixed piping, 4...Fluid supply rotary joint, 5...Signal wiring section, 6...Non-contact rotating transformer section, 7, 7'...Case, 8,
8'...Fluid float part, 9...Eddy current testing probe, 10...AGC detection probe, 11...Fluid reservoir, 12...Fixed piping, 12'...Fluid hole,
13, 13'...small hole, 14...throttle valve, 15...
...Steel plate, 16, 16'...Piping, 17...Frame,
18...Rotating arm.

Claims (1)

[Scope of utility model registration request] A probe rotation drive unit, a rotation arm connected to the drive unit, a case fixed to the rotation arm, and a flaw detection probe opposed to the steel plate surface are built into the case, and the flaw detection probe facing the steel plate surface is installed in the center of the case. A fluid float part provided with a fluid hole that fits into a fixed pipe that spouts high-pressure fluid is arranged so as to be movable vertically and horizontally, and a small A steel sheet surface flaw detection device with holes.