Title:
DEGAUSING SYSTEM FOR STEEL PIPE
Document Type and Number:
Japanese Patent JPH1111850
Kind Code:
A
Abstract:
PROBLEM TO BE SOLVED: To prevent the generation of the magnetic blow, and to improve the workability in welding, by demagnetizing the residual magnetism of a steel pipe by generating the attenuated DC electric current on a lifting magnet in a condition that the polarities of a lifting magnet are alternately reversed. SOLUTION: A degausing system comprises a power source for generating a DC current of two polarities on a lifting magnet, a transformer for attenuating the DC current while alternately reversing the polarities, and an operation unit for controlling the DC current, and the demagnetization is performed by this device in such manner that a steel pipe is attracted by an excitation current, and then a part where the steel pipe and the lifting magnet are kept into contact with each other, is demagnetized when the part where the steel pipe and the lifting magnet are kept into contact with each other, is separated. The demagnetization of the residual magnetism of a steel pipe is performed by generating the attenuated demagnetization current 14 on the lifting magnet while alternately reversing the polarities. Whereby the workability in welding can be improved in a case when the steel pipe is cut on the part where the steel pipe is brought into contact with the lifting magnet, to be welded and joined again.
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Inventors:
WADA HIDEYUKI
Application Number:
JP9169498A
Publication Date:
January 19, 1999
Filing Date:
April 03, 1998
Export Citation:
Assignee:
NIPPON KOKAN KK
International Classes:
B66C1/08; H01F13/00; (IPC1-7): B66C1/08; H01F13/00