| 摘要 |
PURPOSE:To roll a seamless pipe to uniform dimensional accuracy and shape and to prolong the life of a mandrel in the stage of forming the seamless pipe from a hollow bland pipe by rolling by regulating and controlling the speed of a mandrel in accordance with the rolling part of the hollow blank pipe. CONSTITUTION:A mandrel 10 is inserted into the hole of a hollow blank pipe 12 set to mandrel mills, and the moving speed in the rolling direction A of a mandrel 10 is controlled by a mandrel moving device 11. The speed of the mandrel 10 is accelerated or decelerated by the device 11 in accordance with the rolling part of the pipe 12 in such a way that it rises to high speed when the leading and trailing end parts of the pipe 12 are rolled by grooved roll paris 14, 14 of a rolling stand 13 and lowers to a low speed when the intermediate part is rolled with the roll pairs 14, 14. During this time, the pipe 12 is rolled and is made to thin wall between the roll paris 14, 14 of the respective rolling stands 13 and the mandrel 10, whereby the seamless pipe is produced. |
