JPH0338697Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial field of application) This invention is a test coil support device for eddy current testing of test items with flat surfaces such as steel plates. This invention relates to a support device for a test coil for detecting flaws.

(Prior Art) An apparatus is known that performs eddy current flaw detection by supplying fluid to a fluid float section containing a probe-type test coil to levitate the test coil above the surface of a test piece. As an example of such a device, there is a flaw detection device disclosed in Japanese Patent Application Laid-Open No. 103459/1983, which simply has a fluid supply hole in the center of a fluid float, and has a structure in which the fluid float is rotated and , it is impossible to detect flaws facing the back side of the steel plate. When detecting flaws with an eddy current flaw detector, it is important to maintain a constant distance between the test coil and the test piece, ie, the steel plate, in order to perform stable detection, and the same applies to the back side of the steel plate.

(Problems to be solved by the invention) The present invention maintains a fluid float at a fixed distance when detecting flaws on the back side of a steel plate, and floats effectively so that it can follow the shape of the steel plate up and down.
Further, it is an object of the present invention to provide a device that allows initial settings to be easily performed.

(Means for solving the problem) The present invention was made to advantageously solve the above problem, and its gist is to introduce a fluid between the back surface of the test piece and the top surface of the probe-type test coil. In a device that performs eddy current flaw detection by suctioning and floating a test coil on the back surface of a test piece, a cylindrical case that is supported by the main body of the flaw detection head and opens upward, and a fluid supply that extends from the bottom of the case to near the top. A tube, a cylindrical fluid float whose outer circumferential surface is connected to the upper part of the case and whose inner circumferential surface is fitted to the fluid supply pipe, and which has a built-in test coil, and a spring for initial setting is provided in the case between the lower surface of the case and the lower surface of the fluid float. The present invention relates to a support device for an eddy current flaw detection test coil, which is characterized by the following arrangement.

(Function) A spring placed between the bottom surface of the cylindrical case in which the fluid float containing the test coil is connected and the bottom surface of the fluid float pushes up the fluid float and brings it close to the back surface of the test item. In this state, the fluid float When fluid is supplied to the upper center of the fluid float through the fluid supply pipe, the supplied fluid is ejected from the upper center of the fluid float to the back surface of the test piece. As a result, the fluid float receives suction force and buoyancy, and floats on the back surface of the test piece at regular intervals, and moves up and down in response to waves or undulations on the back surface of the test piece.

(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 drawing, the head body 2 is supported by a frame 3 directly below a steel plate S. The head body 2 is equipped with a cylindrical shaft 4 that rotates around a vertical axis.
A signal wiring conduit and a conduit (none of which are shown) are installed inside the cylinder shaft 4.
Further, a reduction gear 6 is connected to the cylinder shaft 4 via a fluid supply rotary joint 5, and a fluid supply source (not shown) is connected via the fluid supply rotary joint 5 and a fixed pipe 8. The rotational drive AC motor 7 rotationally drives the cylindrical shaft 4 via the decelerator 6.

Further, the flaw detection head 1 includes a signal wiring section 9 and a non-contact rotating transformer section or slip ring 1.
1, which transmit and receive signals to and from the cylinder shaft 4. The signal wiring 10 is connected to an input/output section (not shown) of the flaw detector.

An arm 12 extending horizontally is provided at the upper end of the cylinder shaft 4.
is attached, and a case 15 is fixed to each end of the arm 12. As shown in FIG. 2, a supply hole 13 is provided in the arm 12 and communicates with the conduit.

FIG. 3 shows details of case 15. As shown in this drawing, the case 15 has a cylindrical shape, with a closed bottom and an open top. A fluid supply pipe 19 extends concentrically with the case 15 from the bottom of the case 15 to near the top end. Fluid supply pipe 19
is in communication with the supply hole 13. A plurality of guide holes 171 extending vertically are provided in the peripheral wall 16 of the case 15, and a plurality of small holes 18 opening inward are provided near the upper end of the peripheral wall 16.
The lower end of the guide hole 17 communicates with the supply hole 13, and the upper end communicates with the small hole 18.

The casing 21 has a double cylindrical shape, with the outer peripheral surface facing the upper part of the case 15 and the central through hole 22.
The fluid supply pipes 19 are loosely connected to each other.

The initial setting spring 14 is disposed within the case 15 between the bottom surface of the case 15 and the lower surface of the fluid float 20 loosely engaged with the case 15, and serves to constantly push the fluid float 20 upward. That is, the spring 14 may be strong enough to support the weight of the fluid float 20, and in this embodiment, its diameter is approximately 50 mm. In addition, since the fluid float 20 has a structure that allows it to move up and down by 23 mm, that is, ±11.5 mm, the initial setting spring 14 moves the upper surface of the fluid float 20 from the upper end of the case 15.
It should be long enough to push it up so that it protrudes 11.5mm.

The gap between the loose parts is set to about 1 mm. In this embodiment, the outer diameter of the fluid supply pipe 19 is 10 mm. The diameter of the through hole 22 is 12 mm. Therefore, the casing 21 is movable up and down, left and right, and can be tilted within the range of this gap. In the through hole 22 of the casing 21, a portion above the upper end of the fluid supply pipe 19 forms a fluid reservoir 23. Probe-type test coils 24 and 25 are built into the annular portion between the outer and inner walls of the casing 21. below,
The casing 21 and the test coils 24, 25 are referred to as a fluid float 20.

The flaw detection head 1 is mounted so that the upper end surfaces of the case 15 and the test coils 24 and 25 are aligned when the fluid float 20 is at its highest position. Therefore, the length of the fluid supply pipe 19 is such that its upper end is located slightly below the upper end surface of the housing 15 (approximately 3 mm).

The test coils 24 and 25 are connected to the signal wiring, and their upper end surfaces face the back surface of the steel plate S. Here, the test coils are flaw detection coil 24 and AGC.
The AGC detection probe 25 is a generic term for the detection coil 25, and the AGC detection probe 25 is a distance correction detector that compensates the detection signal when the distance between the steel plate S and the flaw detection coil 24 changes within a short period of time.

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. The cylinder shaft 4 is rotated by the rotational drive AC motor 7.
When the arm 12 is rotated, the arm 12 rotates. The test coils 24 and 25 at both ends of the arm 12 scan the surface of the steel plate S in the width direction while drawing an arc.

Fluid reservoir 23 in through hole 22 of fluid float 20
When fluid is supplied through the fluid supply pipe 19, the supplied fluid is temporarily stored in the fluid reservoir 23 and is ejected onto the back surface of the steel plate S. As a result, the fluid float 20 receives buoyancy and floats to a certain height.
It moves up and down according to the waves or undulations of the steel plate S.

The fluid ejected from the small hole 18 of the case 15 forms a high-pressure fluid layer around the float 20. As a result, the casing 21 is held substantially concentrically with the case 15, and the casing 21 is held substantially concentrically with the case 15 or the fluid supply pipe 19.
never come into contact with.

This invention is not limited to the above embodiment; for example, the fluid float may not be rotated but may be reciprocated in the width direction of the test article. Moreover, a circumferential groove may be used instead of the plurality of small holes in the housing.

(Effect of the invention) As explained in detail above, according to the device of the present invention,
The cylindrical fluid float containing the test coil is loosely connected to the fluid supply pipe and the case, so it can be moved up and down, left and right, and tilted. Furthermore, an initial setting spring is arranged inside the case to constantly push up the fluid float to a certain height.This spring is necessary for the initial setting of the fluid float and the steel plate, but after setting, the fluid float is not necessary because it is attracted to the steel plate by the suction force. The effect of the spring is therefore to push the fluid float upwards until it approaches the steel plate. If there is no spring installed,
The fluid float is at its lowest point due to its own weight. Therefore, it is necessary to raise the entire device until the fluid float approaches the steel plate, and after the fluid float has been sucked into the steel plate, it must be moved downward until it can move up and down following the shape of the steel plate. This has the disadvantage that it takes time to set up, and the setting operation is also complicated.

The present invention brings about an excellent industrial effect in that the position of the fluid float can be set with high precision in a short time by arranging the initial setting spring.

[Brief explanation of drawings]

The drawings show an embodiment of the invention, with FIG. 1 being a side view of an example of a flaw detection head, FIG. 2 being a detailed view of the lower part of the flaw detection head, and FIG. 3 being a detailed view of a fluid float. 1...Flaw detection head, 4...Cylinder shaft, 5...Fluid supply rotary joint, 7...AC for rotational drive
Motor, 8... Fluid supply piping, 9... Signal wiring section, 11... Non-contact rotating transformer section, 14... Spring for initial setting, 15... Case, 16...
Peripheral wall, 17... Guide hole, 18... Small hole, 19... Fluid supply pipe, 20... Fluid float, 21... Casing, 22... Through hole, 23... Fluid reservoir,
24...Flaw detection coil, 25...AGC detection coil,
S...2 boards.

Claims (1)

[Scope of utility model registration request] In a device that performs eddy current flaw detection by supplying fluid between the back surface of a test piece and the top surface of a probe-type test coil, the test coil is suctioned and floated to the back surface of the test piece.
a cylindrical case that is supported by the main body of the flaw detection head and opens upward; a fluid supply pipe that extends from the bottom of the case to near the top; an outer peripheral surface is engaged with the upper part of the case, and an inner peripheral surface is engaged with the fluid supply pipe; 1. A support device for an eddy current flaw detection test coil, comprising: a cylindrical fluid float containing a test coil; and an initial setting spring disposed within the case between a lower surface of the case and a lower surface of the fluid float.