Abstract: A ram (5U) is descended by a self-weight pressure of a rod-side cylinder chamber (19) of a hydraulic cylinder (13R) which vertically moves the ram (5U) is detected by oil pressure detection means (21), and a determination section (65) detects a position at which a punch (P) attached to the ram (5U) contacts with an upper surface of a workpiece (W), from a change of this detected pressure. If the upper surface of the workpiece (W) is detected, a plate thickness calculation section (67) calculates a plate thickness of the workpiece (W) based on an upper surface position of a die (D) known in advance and stored in a memory (63).

Abstract: A vertical position of a ram (5U) is directly detected by a ram position detecting means (11), and a first speed arithmetic operating portion (65) determines a first ram moving speed on the basis of a change of the detected position. At the same time, a second speed arithmetic operating portion (67) determines a second ram moving speed on the basis of a rotational number of a servo motor (39) which is determined by a servo motor rotational number detecting means (40). A comparing portion (69) compares the first ram speed with the second ram speed, and in the case that a difference is equal to or more than a predetermined amount, a judging portion (71) judges that an abnormality exists so as to immediately stop the servo motor (39) and stop a working.

Abstract: An operation management system for managing the operation of a managed software product. When a management target function is executed, reference is made to a battery value and, if the value is zero or greater, the function is allowed to be executed. The battery value is decremented as the function is executed. A charge value is supplied on a charge disk, such as a floppy disk, to allow the user to increase the battery value and to extend the usage period of the managed software product. The charge value may be supplied over a communication line.