This invention relates, in general, to a chuck or rotating vise which may be attached to a spindle of a machine and, more particularly, to a new and useful arrangement for controlling a working machine responsive to the pressure or the position of the piston, or both, in a rotary chuck cylinder.
In known machine tools equipped with tie-rod chucks, the pressure in the chuck cylinder, mounted behind the spindle head or headstock, is monitored to instantly and automatically stop the machine in order to prevent accidents. In such an arrangement, the distributors of the chuck cylinders do not rotate but are stationary and permanently connected through pressure lines, to a pressure fluid supply. This can be simply effected by means of pressure switches provided in the pressure lines which deliver a pulse for stopping the operation of the working machine as soon as a predetermined minimum pressure is reached.
In rotary chuck cylinders, particularly collet chucks, where the pressure is confined inside and the pressure fluid supply lines are interrupted during operation of the machine so that the communication to the cylinder is not permanent, such pressure checking is not possible. Until now, such chucking devices did not permit the machine to automatically be stopped in the event that an insufficient clamping force was caused by a pressure drop in the pressure space of the machine chuck cylinder.