Abstract: A system for preventing the collision of two cutting tools in a computer-controlled cutting unit in which the two cutting tools may at times be moved toward each other. This system determines the actual position of each cutting tool during the cutting process. The distance between the two cutting tools is determined and is compared with a previously specified tolerated separation by means of a comparator in the computer. As soon as the tolerated separation has been reached, the system shuts off the cutting unit. In addition, an electrical safety circuit prevents the cutting unit from starting up again automatically after an automatic shutdown.

Abstract: In a sheet cutting machine in which a guidance system moves a blade across a work surface, the blade height is adjusted in accordance with stored data of irregularities of the guidance system and work surface relative to each other. The machine is also operable in a mapping mode in which the blade is replaced by a sensor which is scanned over the work surface, and the sensor output data is stored in the memory.