| 摘要 |
PURPOSE:To provide a titled rolling mill which decreases the rolling force on a mandrel by making the angle of inclination, diameter and offset angle of circular conical rolls respectively small, and containing the ultimate range of the rolling force acting from said rolls within a hollow blank material. CONSTITUTION:The angle (r) of inclination of the shaft of a circular conical roll 1 is set at <=30 deg. so that the rolling force P from said rolls acts on a hollow blank material A but acts hardly on a mandrel 2. The diameter D(2Xrw) at the forward end in he rolling region of the roll 1 is made small so as to be kept at <=2 times the outside diameter d(2Xrm) on the outlet side of the material A, usually D/d=1.0-2.0. The degree of the deviation in the central axial line of the roll 1 with respect to the central axial line of the material A, that is, offset alpha, to be provided in order to feed the material A forward in parallel with drawing is set small so as to be maintained at alpha<=4 deg.. As a result, the life of the expensive mandrel is extended considerably, the times for exchanging the mandredl are decreased; hence, the productivity in producing a seamless pipe by diametral reduction is improved. |
