| 摘要 |
PURPOSE: To prolong the life of a mandrel bar by reusing it with the same size and the same surface hardness, whose surface roughness is deteriorated by using, holding it at a specific temperature after grinding to attach scale on it. CONSTITUTION: By grinding a mandrel bar whose surface roughness is deteriorated, it is recovered to states that a decrease in the outside diameter is about 0.04mm and its surface roughness Rz is about 8μm to maintain within an outside diameter control standard, and grinding and regeneration covering five to six times are usually made possible. Also, by attaching scale to the mandrel bar held in a range from the room temperature to 100 deg.C, spraying seawater on it, lubricant can be well applied without performing seizure and oxidation with deterioration in hardness, and the mandrel bar can be reused with the same size and the same surface hardness as before. Consequently, the life of the mandrel bar can be prolonged and a consumption unit can be remarkably reduced.
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