Abstract: Tublar workpieces are formed with perforations of desired size and/or shape by repeatedly piercing selected portions of the workpieces by needles, pins or analogous piercing tools. The tools can be stationary while the workpieces roll therealong, or the workpieces can rotate while coming into repeated engagement with one or more sets of orbiting tools. The frequency and the number of penetrations of tools into selected portions of the workpieces are selected with a view to heat the tools as a result of frictional engagement with the material of the workpieces, i.e., as a result of repeated penetration into and extraction from selected portions of a rotating or rotating and rolling and/or axially moving workpiece. This enhances the making of predictable perforations in tubular workpieces, especially workpieces which consist of a synthetic thermoplastic material, such as bobbins for the storage of textile yarns.

Abstract: The invention relates to methods and apparatus for making rings from tube stock (10) by a part-off rolling tool (12,15) which is advanced radially into the tube stock to form successive rings, e.g. annular blanks for subsequent roll forming into bearing rings. The tube stock is indexed forward after separation of each ring. Errors in the length of tube stock indexed forward each time are contained by forming a locating groove (47) on the tube stock by means of a groove-rolling tool (40) set at an appropriate axial distance from the part-off rolling tool (12) and moved radially with it. In the next cycle the groove (47) automatically centers the part-off tool as the latter begins its advance into the tube stock, so as to give the correct axial length of the finished ring. The part-off tool is stopped before fully penetrating the tube wall, which is then machined. Final separation takes place during this machining or in a subsequent finishing pass by the part-off tool.