| 摘要 |
The invention relates to a method for producing hot-rolled seamless pipes having at least one thickened wall portion that can be arranged at arbitrary positions across the length of the pipe, wherein by means of a multi-stand rod rolling mill having at least three roll stands and at least two rollers per stand, the rollers roll a hollow block pipe on a rolling rod as an internal tool to a required nominal wall thickness, and at pre-determined positions across the length of the pipe produce a required thickened wall portion on the outside of the pipe as compared to the nominal thickened wall portion by driving the rollers in the roll stands. In order to provide a method for producing hot-rolled seamless pipes by means of a rod rolling mill, with which at least one thickened wall portion at the pipe end or at a defined position on the pipe, of optimal roundness without the need for a subsequent compression process, can be produced, according to the invention the thickened wall is produced and roll-finished at the predetermined positions with only the two roll stands that are successive as viewed in the direction of rolling, wherein deviations of the finished contour of the thickened portion from an ideal circular cross section resulting from driving the rollers through the roller contours become minimal. The roll stands located in front thereof as viewed from the direction of rolling are likewise driven on for a required wall thickness gradation of the roll stands, and all subsequent roll stands are at least driven on such that a contact of the rollers of said roll stands with the previously produced thickened portion, and thus a subsequent reduction of the produced thickened wall portion is avoided. Fig. 2: |
