Electricity: measuring and testing – Magnetic – With temperature control of material or element of test circuit
Patent
1990-11-07
1992-04-21
Strecker, Gerard R.
Electricity: measuring and testing
Magnetic
With temperature control of material or element of test circuit
324226, 324238, G01N 2790, G01R 3312
Patent
active
051072149
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a through-type eddy current hot state flaw detector for detecting flaws in ferromagnetic metals such as wires, steel bars, steel pipes, etc., and in non-magnetic metal materials in the step of hot rolling. More specifically, the invention relates to a hot flaw detector which requires no sleeve for shielding the heat.
BACKGROUND ART
Electromagnetic induction (eddy-current) flaw detecting method has heretofore been widely used for non-destructive inspection of metal wires and bars that are hot rolled to meet initial prerequisites such as high-speed and non-contact operation. A variety of heat shielding and cooling constructions have been devised for the sensor unit used for the flaw detection since it always confronts the materials of high temperatures that are to be inspected.
In order to protect the sensor unit from high temperatures radiated from the materials to be inspected, heat-resistant coils for eddy-current flaw detection employing a heat-shielding thin-wall sleeve have long been put into practical use as disclosed in Japanese Utility Model Application Publication No. 45-26143, U.S. Pat. No. 3,694,735, Japanese Application Public Disclosure No. 58-83254, and U.S. Pat. No. 4,461,995. In the heat-resistant coils for eddy current flaw detection, the thin-wall sleeve for shielding is made up of a thin-wall pipe composed of an austenite-type stainless steel or titanium resulting, however, in the development of eddy-current loss since it is an electrically conductive material. That is, the magnetic lines of force of the flaw detecting exciting coils or of the detecting coils surrounding the outer circumference of the thin-wall pipe are attenuated by the thin-wall pipe as they reciprocally travel through the hot material to be tested running inside the thin-wall pipe. Attempts were made to replace the thin-wall pipe by a non-metallic pipe such as a ceramic cylinder of alumina or the like without, however, any success of putting it into practice in regard to mechanical resistance and thermal shock resistance.
In order to solve such problems, it was devised to form a single or a plurality of elongated grooves in the heat-shielding sleeve which is made up of a thin metal pipe as disclosed in Japanese Utility Model Application Publication No. 54-26072 and Japanese Patent Application Publication No. 60-18938. With the structure disclosed in Japanese Utility Model Application Publication No. 54-26072, however, the cooling water flows out through the elongated grooves. With the structure disclosed in Japanese Patent Application Publication No. 60-18938, on the other hand, the leakage of water can be prevented by sealing the elongated grooves with a filler material or a junction material. However, since the heat-shielding sleeve and the filler material or the junction material have different coefficients of thermal expansion, the filler material or the junction material is split off causing, after all, the water to leak. There have further been proposed hot eddy-current flaw detecting coils in which the cooling water is positively injected from the heat-shielding member of the hot flaw detecting coil to locally cool the outer surface of the pipe to be inspected after the flaw detecting coil is cooled as disclosed in U.S. Pat. Nos. 4,024,470 and 4,123,708. With the eddy-current flaw detection being carried out while permitting the water to be leaked as done in Japanese Utility Model Application Publication No. 54-26072 and Japanese Patent Application Publication No. 60-18938 and in U.S. Pat. Nos. 4,024,470 and 4,123,708, however, there arises a problem in that the outer surface of the material to be tested is locally cooled.
Therefore, there have been proposed the structures for effecting the cooling without using heat-shielding electrically conductive sleeve which deteriorates the sensitivity of the flaw sensor and without permitting the cooling water to come in contact with the outer surface of the material to be inspected, as disclosed in Japanese Patent Appl
REFERENCES:
patent: 3694735 (1972-09-01), Mester
patent: 4123708 (1978-10-01), Vild et al.
patent: 4461995 (1984-07-01), Harris
patent: 4789828 (1988-12-01), Tornblom
patent: 4810988 (1989-03-01), Schenk, Jr. et al.
Fujiwara Masaki
Miyazawa Kazuyoshi
Nitta Shigeyuki
Taguchi Katsumi
Yoshida Mitsuo
Eddio Corporation
Nippon Steel Corporation
Strecker Gerard R.
LandOfFree
Hot flaw detector with annular injection port for injecting cool does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hot flaw detector with annular injection port for injecting cool, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hot flaw detector with annular injection port for injecting cool will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1589877