Bolt-Screwing Machine

a machine tool for cutting threads on bolts, studs, and tubing. It is equipped with a tapping head for the tools, which are threading dies. The workpiece, which is clamped in a vise on the saddle, is moved along the machine’s bed into contact with the threading dies; thereafter the movement is controlled by the threading dies which pull the workpiece one pitch of the thread per revolution. When the machining is finished, the threading dies open automatically so the threaded workpiece can be removed without stopping the machine. A bolt-screwing machine surpasses in productivity both turning lathes and thread-milling machines but is inferior to thread-rolling machines which, because of this and other advantages, are supplanting the bolt-screwing machines.