Continuously operating severing machine

In a continuously operating severing machine having a cutting tool arranged to advance continuously to effect cutting of a workpiece, a machine stand presenting a workpiece table for supporting the workpiece and clamping jaws for holding the workpiece in position, a machine head containing the cutting tool and movable relative to the workpiece table for advancing the tool in a feed direction through the workpiece during cutting, and a feed device connected between the machine stand the machine head for controlling the relative movement of the machine head in the feed direction and the cutting pressure between the cutting tool and workpiece in dependence upon the workpiece material and cross section, and for returning the machine head back to its starting position at high speed after a cutting operation, the improvement wherein said feed device comprises:

• a ball roller spindle rotatably supported by said machine stand and provided with a helical thread on its outer surface, said spindle extending in the feed direction, and having a length greater than the maximum feed displacement of the portion of said machine head in the region of said spindle;
• two axial bearings carried by said machine head in the vicinity of said spindle and spaced apart in the direction of the length of said spindle;
• a freewheel coupling positioned between said axial bearings and composed of an inner race in threaded engagement with said spindle and having a thread pitch outside of the range of self-locking with said spindle thread;
• an outer race carried by, and rotatable freely relative to, said inner race, and coupling means coupling said races together in a manner to permit said outer race to rotate freely relative to said inner race in the direction of rotation of said inner race relative to said spindle during movement of said machine head in the feed direction;
• drive means connected for rotating said outer race in said direction of rotation at a rate which is a function of the advance of the tool;
• a braked drive motor connected for rotating said spindle in said direction of rotation;
• and
• means for adjusting the weight loading imposed by said machine head on said freewheel coupling.