JPS6018938B2 - Detection coil for hot flaw detection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling structure that can effectively cool a high-temperature detector in an eddy current flaw detector.

Hot flaw detection, which is carried out during the hot rolling process, has recently become commonplace for inspecting surface flaws in wire strips, bamboo wood, etc. manufactured by hot rolling.

In the case of deep scratches, the temperature of the material to be inspected is extremely high, especially steel materials, which are at temperatures above the Curie point. Therefore, a cooling structure is required to block the influence of heat from the material to be inspected and to prevent burnout of the detection coil. considered essential. However, conventional cooling structures have various disadvantages, and a sufficient cooling structure has not yet been achieved. For example, with a structure in which a coil is wound around a ceramic bobbin and a water jacket is placed around the bobbin to radiate heat through the circulation of coolant, the inner surface of the bobbin facing the material to be inspected is insufficiently cooled, and there is a risk that the bottom of the coil will overheat and burn out. There is a risk that the bobbin will collide with the material to be inspected and be damaged. As another example, a coil bobbin can be loosely attached to a coil bobbin with a small gap on the outside of the heat-resistant sleeve through which the material to be inspected penetrates. In a structure that blocks heat, it is necessary to reduce the thickness of the heat-resistant sleeve and increase the filling rate of the coil.If the sleeve is made of ceramic or glass, the impact strength will be weakened, and if it is made of metal, a decrease in sensitivity due to eddy current loss can be avoided. do not have. The object of the present invention is to provide a cooling structure that solves these problems.

The present invention will be explained in detail below with reference to Examples. FIG. 1 is a sectional view of an embodiment of the present invention.

Reference numeral 5 denotes a thin cylinder made of non-magnetic rust-free steel or heat-resistant steel, which has an inner diameter that allows the material to be inspected to pass through, has high electrical resistivity, and has good wear resistance at high temperatures.

Reference numeral 6 denotes a cylindrical bobbin made of a non-metallic material with good heat resistance and some degree of elasticity, and a flaw detection coil 7 is wound around a plurality of annular grooves carved on the outside.

The bobbin 6 is watertightly fixed to the frame 1 by flanges 2 and 3 and a guide 4 through which the birch material passes, and the frame 1, together with the flanges 2 and 3, constitutes a water jacket surrounding the bobbin 6 and the coil 7. There is. Slj deep 5
is attached to the bobbin 6 and constitutes a part of the peripheral wall of the inspection target material passageway that is continuous with the through hole 9 in the guide 4. The coolant enters through the injection hole 12 in the frame and exits through the discharge port 13, so the cooling liquid flows through the frame, flanges 2, 3, guide 4,
The inside of the water jacket 10 constituted by the bobbin 6 is filled with cooling liquid, and the outside of the coil 7 and the bobbin 6 is sufficiently cooled. Next, cooling the coil 7 and the inside of the bobbin 6, which are exposed to higher temperatures, becomes a problem.For this reason, a gap 11 is formed between the bobbin 6 and the sleeve 5, so that the cooling liquid sent into the water jacket 10 can be cooled. is made to flow through this gap as well.

That is, the bobbin 6 is held at both ends by the flange portion of a flanged short tube 15 which is iron-bonded to the guide 4 via a ring 14, and is fixed coaxially to the center line of the guide 4, and the sleeve 5 is fixed coaxially to the center line of the guide 4. Both ends are iron-bonded to the cylindrical portion of the short tube 15, the outer diameter of the sleeve 5 is smaller than the inner diameter of the bobbin 6, and a gap 11 is formed between the bobbin 6 and the sleeve 5. This gap may be provided with a spacer as appropriate. A through hole 16 is bored in the flange portion of the flanged short tube 15, and the gap 11 is filled with a water jacket 10.
I am communicating with. Furthermore, the sleeve 5 is provided with a split groove 18, which is a feature of the present invention. That is, the grooves 18 make it possible to easily contract the sleeve 5 in the circumferential direction and absorb the difference in thermal expansion, and also prevent the short-circuiting effect of the eddy current on the sleeve itself, making it possible to cause deep damage with a high sensitivity to the eddy current. can. water jacket 10
A part of the coolant injected into the gap 1 from both ends of the bobbin 6
1 and flows out into the inspection hole 9 through the split groove 18. Since water pressure is applied to the injection of water from the injection row 2, a pressure difference is created between the inside and outside of the metal sleeve 5, and the cooling liquid flowing through the gap 11 maintains a constant speed. Even if the inner surface of the sleeve 5 is heated due to the cooling effect of water flowing through the gap 11, the temperature can be maintained at a low temperature similar to that of the inner surface of the coil bobbin. As described above, the present invention fully satisfies both the requirements of cooling effect and high sensitivity, and by adopting the present invention, it can withstand continuous use for a long period of time and enables highly sensitive hot eddy current deep damage. Become.

Also, as shown in Fig. 2, there is a partition 2 inside the water jacket 10.
1 may be provided, and the cooling water may enter from 12 and flow toward the bag and exit from 13, so that the water flows within the gap 11 from one end to the other end.

In this case as well, grooves are drilled.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a side sectional view of another embodiment. In the figure, 1...Frame, 2, 3...Flange, 4...Guide, 5...Sleeve, 6...Bobbin, 7...
Coil, 8...○Ring, 9...Inspection hole, 10...Housing, 11...Gap, 12...
...Inlet, 13...Outlet, 14...0 ring,
15...Short tube with flange, 18...Split groove. Figure 2

Claims (1)

[Claims] 1. A thin-walled sleeve is fixedly installed inside a coil bobbin that has a water jacket on the outside so that cooling fluid flows between the thin-walled sleeve and the coil bobbin, and an axial groove is bored in this thin-walled sleeve. Features a detection coil for hot flaw detection.