| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of using a mandrel bar to realize longer life and improved unit consumption. SOLUTION: This is a method of using a mandrel bar with chrome plating film formed on its surface, which is used for mandrel mill rolling in the Mannesmann process. The use is stopped before the depth of heat crack caused during the use becomes maximum 8 mm or before the residual plating thickness becomes minimum 5μm. The plating film is removed, and then the base metal surface is finish-polished or surface-treated, and replated for reuse. If this method is used, it is not always necessary to maintain a specific surface roughness when the chrome-plated bar is used. Also it is not necessary to form various multi-layer films or greatly increase the manufacturing and maintenance costs to make the sleeve structure. It is possible to reduce separation of the plating due to the progress of heat crack and occurrence of seizure due to the wear of the chrome plating film, thus realizing longer life of the mandrel bar and improved unit consumption.
|
