A Stepper Motor System for Profile Following and Cutting

The function of an automatic profile cutter is to cut from the work material a replica, possibly scaled, of a given shape. The profile may be available as an ink outline drawing or a template. There are two functions involved in the process: one is the following of the outline of the shape. The other is the positioning and control of the cutting tool. A digital system employing stepper motors as position transducers has been developed to perform the required functions. The use of rate multipliers followed by simple smoothing greatly simplifies the implementation of the system. Digital system has a stable characteristic with respect to the outline to be followed as well as to extraneous disturbances. Reproducibility of the cut profile has been enhanced and the tedious task of ``tuning up,´´ necessary for reliable operation of the analog counterpart, has been entirely removed. An external digital storage device such as a cassette tape unit can easily be incorporated into the system. This permits the following of an outline drawing at an optimum speed and the subsequent regeneration of the information at any speed to drive the cutter.