A new positioning system with 4 DOF for the alignment on rotating axes

Summary form only given. Machine tools which possess a precision in the nanometer range are of increasing importance in the field of precision engineering. Workpieces are held on a machine spindle by using a vacuum chuck. The chuck is a precisely finished surface perpendicular to the machine spindle. It requires every workpiece to be precisely centered. Its alignment has until now always been performed manually. This is slow and involves problems. The article presents a new positioning system. It should center the workpiece and correct its tilt. We applied impact drive mechanisms (IDM) to position the work piece. The advantage of IDM is the capability to move objects which are held by relatively large friction forces. The rapid deformation of piezoelectric actuators was used to center the workpiece on its support as well as to correct its tilt. The alignment process was controlled by a PC using a control program written in C++ under MS-Windows, which results in a relatively simple operation of the system.