Pneumatic fail-safe sensor system for N/C machine tool

In an N/C machine tool, adapted to cut a part in accordance with a program that includes a probe adapted to follow a master pattern as the part is being cut, the improvement comprising a pneumatic sensor system, said pneumatic sensor system including:

• a pneumatic valve mechanism including a movable element and a valve seat, said movable element adapted to open and close an aperture formed in said valve seat;
• a probe connected to said movable element and normally spaced from said master pattern, said probe adapted to contact said master pattern whenever said N/C machine deviates from the cutting path established by said program, said probe being displaced when it comes in contact with said master pattern, said master pattern probe contact causing said movable element of said valve mechanism to be displaced and open said aperture formed in said valve seat;
• a pneumatic pressure source for applying pneumatic pressure to said aperture in said valve seat;
• pneumatic pressure sensing means for sensing drops in the pneumatic pressure applied to said aperture in said valve seat, said pneumatic pressure drops occurring when said movable element of said pneumatic valve mechanism is displaced by said probe coming in contact with said master pattern;
• and,
• electronic control means connected to said pneumatic pressure sensing means for detecting when said pneumatic pressure sensing means detects a drop in the pneumatic pressure applied to said aperture in said valve seat and generating control signals suitable for terminating the operation of said N/C machine tool in a rapid manner when a said pneumatic pressure drop is detected.