This invention relates to hydraulic systems which are employed in automatic machining equipment. The present invention is more particularly directed to a hydraulic system for a machining device which has a rotary spindle that has an openable and closable collet or chuck, a tailstock slide that contacts and supports a workpiece in the collet or chuck, a tool selection turret, and a spindle brake, all of which are hydraulically actuated and all of whose conditions can be hydraulically monitored. Preferably, the machining device can be a computerized numerically controlled (CNC) machine tooler, of which there are several well known designs.
CNC machinery equipment enjoys the advantages of fast machine cycle times, high precision, consistent dimensional accuracy, flexibility of operation, and ease in programming to machine any specific workpiece automatically into a finished, machined product.
Generally, the machining equipment has an enclosure or cabinet, which holds the machining tools and also confines any metal dust or by-product, and also maintains an even temperature to preclude loss of accuracy due to thermal expansion.
Within the cabinet there is a spindle which holds a collet, chuck, or jaw into which a workpiece or part is secured for a machining operation. The collet is automatically opened and shut. A spindle brake is automatically applied when required to halt rotation of the spindle. A tailstock slide moves hydraulically between a home position remote from the associated workpiece, and a forward position with the tailstock against and supporting the workpiece. A turret clamp prevents the turret from rotating out of position when a tooling operation is carried out, but is moved to an unclamp position when it is necessary to rotate the turret to bring another tool into position.
The machine tool industry has long sought a simple, but reliable hydraulic system that performs the necessary functions, and also provides positive signals to indicate collet open and closed condition, spindle brake actuation, tailstock position and system pressure. Control and signal of the tailstock is especially important so that the tailstock can be brought with gentle but firm pressure against the workpiece to permit handling of light, fragile parts as well as heavy, lengthy, or bulky workpieces. However, until this invention, no completely suitable hydraulic system has been provided for automated machining equipment.