| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing apparatus line for a mandrel bar that dispenses with a rolling schedule where a low alloy steel is wedged into rolling of a steel species containing many alloy elements, invites no complication in the rolling schedule or no deterioration in profitability and can elongate the tool life of the mandrel bar by inviting no large investment with no need of plating treatment.SOLUTION: A manufacturing apparatus line for a mandrel bar 1, which heats a bar blank 10 that is a semi-product of mandrel bar shape up to a tempering temperature and succeedingly cools the same down to 100°C or less to form a mandrel bar 1, has a tempering furnace 20, which heats the bar blank 10 up to a tempering temperature and an acceleration cooling device 22 that sets the cooling rate from the tempering temperature of the bar blank extracted out of the tempering furnace to 100°C at 10.0 - 35°C/min, disposed in this order.SELECTED DRAWING: Figure 1 |
