Positioning workpieces by clamping devices

A workpiece processing system, comprising:

• a workpiece processing device;
• and
• a workpiece clamping device comprising:
• a carrying structure;
• two clamping elements forming a clamping element pair and being located opposite one another on the carrying structure, wherein each of the clamping elements is provided with a guide slide and wherein each of the guide slides is guided on a guide arm of the carrying structure along a clamping axis and has a control pin protruding from a rear side of the guide slide;
• and
• a servo drive that forms a positioning drive having:
• a drive motor mounted on the carrying structure;
• an adjusting ring that is rotatably mounted on the carrying structure and has two connecting members located diametrically opposite one another on the adjusting ring, each of the connecting members having a connecting member slot extending along the clamping axis and each of the connecting member slots guiding the control pin provided on the guide slide of one of the clamping elements along the clamping axis;
• and
• a numerical control device configured to control the drive motor of the servo drive to rotate the adjusting ring including the connecting member slots and to thereby displace the control pins that are guided in the connecting member slots, the guide slides from which the control pins protrude, and the clamping elements provided with the guide slides, synchronously and in opposite directions along the clamping axis, such that the clamping elements thus are positioned relative to one another along the clamping axis,
• wherein the drive motor of the servo drive is controlled by the numerical control device to:
• first move the clamping elements toward one another into a pre-determined clamping start position in which the clamping elements are positioned on opposite sides of a workpiece arranged therebetween and in which the clamping elements do not apply a force to the workpiece or apply a force to the workpiece that is smaller than a clamping force that is pre-determined based on a stiffness of the workpiece,
• subsequently urge the clamping elements toward one another from the pre-determined clamping start position to an operational state, in which the clamping elements apply the clamping force to the workpiece, and
• when the force applied by the clamping elements on the workpiece reaches the pre-determined clamping force, stop moving the clamping elements.