Patent GB-808035-A (GB)
Title: Automatic screw machine and method of making countersunk or counterbored articles in an automatic screw machine
Inventor: SCHRADER CLARENCE OLIVER
IPC: B23B31/20
Filed: 1956-12-18
Abstract: 808,035. Combined lathes and drilling-machines; chucks. PAPER MATE MANUFACTURING CO. Dec. 18, 1956, No. 38549/56. Class 83 (3). Articles 12 having their opposite ends countersunk or counterbored are machined from bar stock 3 in an automatic lathe by cotmter-boring the end of the stock 3, parting-off the machined end, maintaining the separated work 12 in axial alignment with the stock 3 but spaced therefrom, and then simultaneously counterboring the newly-formed end of the stock and the unbored end of the separated work. The lathe comprises a headstock 1 in which the stock 3 is carried in a hollow spindle, an auxiliary spindle 8 to receive the parted-off work 12 and a tool-frame (not shown), supporting a drillholder 5 with oppositely-directed drills, or a pair of drill-holders 5, 6, the frame also supporting holders for parting-off and turning-tools (not shown). Radial movements of the tool-holders and axial movements of the headstock and auxiliary spindle are effected by a cam-shaft. The outer surface of the stock is turned to the desired form before the tool-holder or holders 5, 6, with oppositelydirected drills 15<SP>1</SP>, 16<SP>1</SP>, 17<SP>1</SP>, 18<SP>1</SP>, are brought to the operative position shown in Fig. 4. The headstock and spindle 8 are fed towards the drills during the drilling of bore 15 and again, after the holders 5, 6 have been re-positioned, during the drilling of bore 16 with drill 16<SP>1</SP>. After radial-withdrawal of this drill, the headstock is again advanced, to carry the stock 3 to the path of the parting-off tool (not shown), where it is received by the collet of spindle 8, and the workpiece 12 is withdrawn by the spindle 8 after the parting-off operation. The stock is then advanced through the headstock, which is again fed forward for a fresh cycle of operations on the new end of the stock. In this cycle, the unbored end of the work held by the spindle 8 is drilled, simultaneously with the drilling of the holes 15, 16 in the stock, by feeding the spindle 8 towards the drills 17<SP>1</SP>, 181 when the headstock is fed towards the drills 151, 161. The collet of spindle 8 is opened and the spindle, withdrawn, leaving the finished work 12 on the drill 17<SP>1</SP>, Fig. 6, which withdraws the work radially. When the spindle 8 is again advanced to receive the next workpiece, spring fingers 11 on the housing of the spindle engage the finished work on the drill 17<SP>1</SP> and remove it as the spindle is retracted, a stop (not shown), releasing the work from the fingers and permitting it to fall into a shoot. Knurling- operations may also be performed, and the auxiliary spindle is preferably rotated at a higher speed than the headstock spindle. Collet-chucks.-The collet is operated by a diaphragm, piston 54, Fig. 8, secured at its outer periphery to the hub 37 of a driving pulley for the spindle and at its inner periphery to the shank 45 of the collet, the diaphragm being clamped by a nut 53 against a backing 48 which engages screw-threads on the shank and is guided by pins 49. The collet is opened, while rotating, by a spring 58, and closed by pressurefluid admitted through a connection 43 on the spindle-housing and fed to the diaphragm-along one or more surface-channels or passages 46 in the shank 45.