JPH0424448Y2 - - Google Patents

Description

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

(Prior Art) An apparatus is known that performs eddy current flaw detection by supplying fluid to a fluid float section containing a flaw detection probe to float the flaw detection probe above the surface of a test piece. An example of such a device is a flaw detection device disclosed in Japanese Unexamined Patent Publication No. 103459/1983. With conventional equipment,
A specific plate thickness setting device is not disclosed and it is difficult to respond.

(Problems to be solved by the invention) In eddy current flaw detection, it is important for high precision detection to set and maintain the distance between the surface of the test piece and the flaw detection probe within an appropriate range. The thickness of steel plate obtained by hot strip mill is from the minimum thickness to the maximum thickness.
There is a difference of approximately 24 mm between 1.2 and 25.4 mm, making it difficult to perform high-precision flaw detection over the entire plate thickness by setting a constant height.
Therefore, it is important to set the flaw detection device at an optimal height depending on the plate thickness in order to perform stable detection.

(Means for Solving the Problems) The present invention has been made to advantageously solve the above problems, and its gist is that a lifting mechanism is provided on a slide bed that is provided facing the steel plate surface. A non-contact type flaw detection device in which a flaw detection probe is floated above the surface of the steel plate by fluid is placed in the lifting mechanism, and a data setting unit that provides information on the thickness of the steel plate is installed, and a set amount of plate thickness is determined from the signal from the data setting unit. The present invention relates to a steel sheet surface flaw detection device characterized by comprising a controller that calculates the following: and a drive section that drives an elevating mechanism from the output of the controller.

(Example) Hereinafter, an example of this invention will be described using an eddy current flaw detection test device for steel plates as an example.

FIG. 1 is a side view of the flaw detection head 1 as a whole. As shown in the drawings, the head body 2 is supported by a frame 3 directly above a steel plate S, and is fixed to an elevating section 60 as shown in FIG. The elevating part 60 is fixed to a slide bed 70 for width setting and can move the steel plate S in the width direction.

The head body 1 includes a cylindrical shaft 5 that rotates about a vertical axis, and a signal wiring conduit and a fluid conduit (none of which are shown) are installed within the cylindrical shaft 5. Further, a fluid supply source (not shown) is connected to the cylinder shaft 5 via a fluid supply rotary joint 6 and a fixed pipe 9, respectively.
The rotational drive AC motor 8 rotationally drives the cylindrical shaft 5 via the reduction gear 7 .

Further, the flaw detection head 1 includes a signal wiring section 11 and a non-contact rotating transformer section or slip ring 13, which transmit and receive signals to and from the cylinder shaft 5. The signal wiring section 12 is connected to an input/output section (not shown) of the flaw detector. The cylinder shaft 5
A horizontally extending arm 15 is attached to the lower end of the arm 15, and housings 21 and 21 are fixed to both ends of the arm 15, respectively. As shown in FIG. 2, a supply hole 16 is provided in the arm 15 and communicates with the conduit. Inside the housing 21, fluid floats 30, 30 are introduced which move up and down following the shape of the surface of the steel plate. FIG. 3 is a detailed view of the housing 21. As shown in this drawing, the housing 21 has a cylindrical shape, with a closed top and an open bottom. Housing 21
A fluid supply pipe 27 extends concentrically with the housing 21 from the top to near the bottom end. Fluid supply pipe 27
is in communication with the supply hole 16. housing 2
A plurality of guide holes 23 extending vertically are provided in the peripheral wall 22 of 1.
A plurality of small holes 24 are provided near the lower end of the peripheral wall 22 and open toward the inside. The upper end of the guide hole 23 communicates with the supply hole 16, and the lower end communicates with the small hole 24.

The fluid float 30 has a double cylindrical shape, and the outer peripheral surface thereof is fitted into the lower part of the housing 21, and the fluid supply pipe 27 is fitted into the central through hole 32, respectively.
In the figure, 42 is a flaw detection probe, and 43 is an AGC detection probe for distance correction. That is, if the distance between the steel plate S and the flaw detection probe 42 fluctuates within a short period of time, the detection signal is compensated. fluid float 30
In this example, the vertical stroke of is 23mm, which is initially set to +13mm -10 position. Therefore, it is possible to follow the shape of the steel plate with a stroke of 13 mm in the upward direction and 10 mm in the downward direction.

FIG. 4 shows an example of the elevating mechanism, which is composed of an elevating servo cylinder 50, an elevating guide 61, and an elevating section 60. The elevating section 60 is fixed to a slide bed 70 provided facing the surface of the steel plate, and the rotary flaw detection section 1 is set up and down on the steel plate S by the elevating servo cylinder 50. The elevating guide 61 serves to facilitate the elevating and lowering of the elevating section 60 and to prevent vibrations. Lifting section 60 and slide bed 7 for setting board width
0 is mounted on a trolley 80 and can be moved online and offline.

FIG. 5 shows a detailed internal view of the servo cylinder 50 and its drive circuit. Plate thickness data is input into the controller 57 using a host computer or manual data 58. The position of the cylinder is fixed in advance so that (maximum cylinder stroke) - (plate thickness t) = fluid float + 13 mm - 10 according to the input plate thickness, and the controller 57 calculates each time. When the calculation is completed, a signal is sent to the drive unit 56 and the electromagnetic brake 51 is activated.
is opened, the solenoid valve 55 is turned on, and pressurized air is sent into the cylinder. A ball screw 54 and a ball nut 53 are provided inside the cylinder, and as the cylinder rod moves forward, a rotary encoder 52 is rotated to transmit a position signal. After confirming that the cylinder load is at the specified position, the solenoid valve 55 is turned off and the electromagnetic brake 51 is closed.
If the target position is exceeded, the cylinder rod is moved backward by a reverse signal. Repeat this operation to stop at the target position. The maximum stroke of the servo cylinder was 250 mm in the example. Therefore, the plate thickness setting value is St=250-t.

In this example, we have explained using a servo cylinder, but the cylinder is used to move up and down a certain amount.
It goes without saying that a method in which only the plate thickness is changed using a motor or a speed reducer achieves exactly the same function.

Next, the operation of the apparatus configured as above will be explained. The eddy current flaw detection test is performed on the steel plate S while it is running. Upper computer 58
The controller 57 calculates the plate thickness setting value based on the plate thickness data, and operates the servo cylinder 50 to the target position via the drive unit 56 to complete the plate thickness setting. That is, in the servo cylinder 50, when the solenoid valve 55 is opened and the solenoid valve 55 is turned on, air is sent into the cylinder and the cylinder rod is moved. When it moves, a ball screw 54 inside rotates, and a rotary encoder 52 connected to the ball screw detects the amount of movement and stops at the target position.

After the plate thickness setting is completed, when the cylinder shaft 5 is rotationally driven by the rotational drive AC motor 8, the arm 15 is rotated. The flaw detection probes in the fluid floats at both ends of the arm 15 scan the surface of the steel plate S in the width direction while drawing a circular arc. At the same time, when fluid is supplied to the fluid reservoir 33 of the through hole 32 of the fluid float 30 through the fluid supply pipe 27, the supplied fluid is temporarily stored in the fluid reservoir 33 provided at the bottom of the fluid float 30 and is ejected onto the surface of the steel plate S. . As a result, the fluid float 30 receives buoyancy, floats to a certain height, and moves up and down in accordance with the waves or undulations of the steel plate S. The fluid ejected from the small holes 24 of the housing 21 forms a high pressure fluid layer around the fluid float 30. As a result, the fluid float 30 is held substantially concentrically with the housing 21 and does not come into contact with the housing 21 or the fluid supply pipe 27.

(Effects of the invention) As explained in detail above, with this invention, the optimum height between the fluid float and the steel plate can be easily set in a short time and accurately in response to variations in plate thickness. Therefore, it moves freely following the surface shape of the test item,
It is possible to always maintain the optimum gap and posture with the test piece, allowing for highly accurate surface flaw detection.

[Brief explanation of drawings]

Figure 1 is a side view showing an example of a flaw detection head;
3 is a detailed view of the lower part of the flaw detection head, FIG. 3 is a detailed view of the fluid float, FIG. 4 is a side view of the elevating mechanism, and FIG. 5 is an explanatory view showing details of the inside of the servo cylinder and its drive circuit. 1...Flaw detection head, 5...Cylinder shaft, 6...Fluid supply rotary joint, 8...AC for rotational drive
Motor, 9...Fluid supply piping, 11...Signal wiring section, 13...Non-contact rotating transformer section, 21...Housing, 22...Surrounding wall, 23...Guiding hole, 24...
...Small hole, 27...Fluid supply pipe, 30...Fluid float, 32...Through hole, 33...Fluid reservoir, 4
2... Flaw detection probe, 43... AGC detection probe, 50... Servo cylinder, 51... Electromagnetic brake, 52... Rotary encoder, 53...
Ball nut, 54... Ball screw, 55... Solenoid valve, 56... Drive unit, 57... Controller,
58... Host computer or manual setting section, 60
...Lifting section, 61... Lifting guide, 70... Slide bed for width setting, 80... Cart, S... Steel plate.

Claims (1)

[Scope of utility model registration request] A lifting mechanism is installed on a sliding bed facing the steel plate surface, and a non-contact flaw detection device in which a flaw detection probe is floated above the steel plate surface by fluid is placed on the lifting mechanism, and data setting that provides information on the thickness of the steel plate. A steel sheet surface flaw detection apparatus comprising: a controller for calculating a plate thickness setting amount from a signal from the data setting section; and a drive section for driving an elevating mechanism from the output of the controller.