Process for controlling the revolving path motions of the spinning roller of a spinning lathe, and spinning lathe for performing the process

Process for controlling the revolving path motions of the spinning roller of a spinning lathe comprising forming a round-blank sheet-metal workpiece by pressing said workpiece against a rotationally drivable spinning chuck, into a spun part unilaterally hugging a shaping surface of the spinning chuck, wherein the spinning roller is supposed to be freely rotatable, on a bearing block shiftable by means of respectively one coordinate drive unit into two mutually orthogonal (X- and Y-) directions, about an axis fixed at the block, and wherein the activation of the coordinate drive units, fashioned as valve-controlled hydraulic cylinder, takes place according to a track repetition (playing-back) process, in accordance with which, in at least one master spinning process, coordinate data characteristic for the thus-traversed positions of the spinning roller and determined with the aid of position pickups are stored in an electronic NC or CNC control unit and are processed by the latter to output data, the X- and Y-coordinate drive units being actuatable by the serial call-up of these output data along the lines of tracking the course of travel of the spinning roller determined during the master spinning process, and wherein initially the contour of the spinning chuck is scanned, and a set of coordinate data characteristic for the configuration of such contour is introduced into the NC or CNC control unit, a safety curve being determined from these data which marks the limit of a closest possible approach of the spinning roller toward the spinning chuck, said process further including

• (a) operating the coordinate drive units are according to a follow-up control process working with electrically controlled reference position value presetting and mechanical actual value acknowledgement,
• (b) utilizing the spinning roller and the drive units provided for the motion control thereof for said scanning of the outer contour of the spinning chuck, wherein these drive units are operated only with less then the maximally usable control circuit amplification, and
• (c) continuously measuring the follow-up path .DELTA.S (lag error) corresponding to the difference between the set reference position value and the actual position value of the spinning roller at least during the last revolution of the spinning roller through which the spun part received its final shape, and wherein, when this measured follow-up path .DELTA.S exceeds a threshold value .DELTA.S.sub.max, taking at least one of the following measures:
• reducing the path tracking velocity V.sub.B of the spinning roller by decreasing the control data output rate, and
• transitioning to a path routing curve of the spinning roller and thus of its rolling-off point corresponding to an increase of the distance of the spinning roller rolling-off point, measured normally to the outer contour of the spinning chuck, with respect to its previously governing reference value curve, until the threshold value .DELTA.S.sub.max has been exceeded in the downward direction by a defined amount .delta.S.