Process and device for threading elongated metal workpieces, especially tubes, into a drawing apparatus

A process for threading tubes into a drawing device for cross-sectional reduction in at least one drawing step by means of at least two successive drawing units which grasp a workpiece along its outer circumference with revolving driving chains which, after a drawing point formed at a start of the tube is threaded in, draw the workpiece continuously through a drawing ring arranged in front of each drawing unit, said process comprising the steps of:

• (a) opening the driving chains of a first drawing unit by moving the driving chains of the first drawing unit apart transversely relative to a drawing axis;
• (b) introducing a gripper disposed downstream of the drawing unit, in a direction opposite to a drawing direction, into an intermediate space between the driving chains so as to detect a tube point projecting out from the drawing ring;
• (c) grasping the drawing point projecting out from the drawing ring and drawing the start of the tube through the driving chains using the gripper;
• (d) closing the driving chains by moving the driving chains together transversely relative to the drawing axis so as to grasp the start of the tube at its outer circumference;
• (e) disengaging the gripper from the drawing point and swiveling the gripper into a position adjacent to the drawing axis while the driving chains are running;
• (f) advancing the tube to a following drawing unit;
• (g) moving apart transversely to the drawing axis the driving chains of the following drawing unit;
• and
• (h) repeating steps (b) through (e) for each following drawing unit.