Patent GB-340373-A (GB)
Title: Improvements in automatic lathes and like machine tools
IPC: B23B5/24
Filed: 1929-11-13
Abstract: 340,373. Lathes. SENECA FALLS MACHINE CO., Fall Street, Seneca Falls, New York, U.S.A. Nov. 13, 1929, No. 34674. Convention date, Jan. 28. [Class 83 (iii).] Lathe drivers.-In a machine tool such as an automatic lathe for turning pistons, the work is fed automatically between a driving device and a slidable tail centre, fluid operated means being provided to advance the tail centre and the driving device to operative positions in predetermined timed relation. The machine base 40 is provided with a fixed headstock 41 and a tailstock 42 slidable on ways 43. A front tool carriage 44 movable on ways 45 is actuated through a link 46 by a cam 49, on a main cam shaft 50, Fig. 3. A cross slide 51 mounted on the carriage 44 is actuated by a cam plate 53 secured to the bed 40. A back tool slide 60 is mounted on a support 61 which is longitudinally adjustable on the ways 43 which support the tail stock 42. The slide 60 is actuated by a cam 43. The general arrangement of the driving mechanism is shown diagramatically in Fig. 3. The main driving belt B is connected by a pneumatic clutch 76 to a shaft 77 which through a gear train 78 .. 85 drives the work-spindle 72. A wheel 95 on the work-spindle drives through a belt 96 and spur gearing, a low-speed coupling 103, and a wheel 86 on the shaft 77 drives a high-speed coupling 87, these couplings being selectively arranged to drive a shaft 88 by means of a splined clutch 107 actuated by a cam 110. The shaft 88 drives through worm gearing 89, and gear 92, a wheel 93 on the cam shaft which is thus driven at high speed for idle movements and low speed for working movements. The shaft 88 also drives through a belt 113 and other gearing, Fig. 3, the cam 63 operating the rear tool slide, this cam being driven at the same speed as the cam 49. The work pieces W pass down a runway 130 and are held up by a dog 131 connected to a lever 138 which is engaged by the carriage 44 at the end of the working stroke to lower the dog 131 and allow a piston to descend into engagement with a lug 132. From this point the work piece is transferred to the lathe centres by a gripper 140 and at the same time a similar gripper 141 transfers a finished workpiece to a delivery runway 142. Each gripper comprises curved arms pivoted on a stud 145 in aholder 146 which is fitted with a piston 152 which may be pressed down by air delivered through a pipe 153 to engage projections 155 with lugs on the gripper arms to close the grippers on to the work. When the air pressure is released a spring 160 raises the piston 152 and depresses an inner piston 158 thereby engaging projections on this piston with lugs 162 on the gripper arms which are thus opened. Both grippers are mounted on a rock plate 147 pivoted at 148 to a pivoted lever 149 and carrying a stud 165 engaging in a fixed cam slot 180 and actuated by a slotted arm 167 on a spindle which is oscillated by a pneumatic cylinder 174. When the piston in the cylinder 174 is at one end of its travel the grippers are moved to the position shown in Fig. 4 to pick up a fresh blank and remove a finished work piece. At the other end of the travel the grippers, Fig. 6, are positioned to place the fresh blank between the centres and place the finished work piece on the runway 142. The tail centre 70 is mounted on a slide 200 actuated through a lever 201, Fig. 18, by a pneumatic cylinder 207. The centre is advanced towards the work by admission of air through a pipe 209. The open end of the work is supported on the conical end 73 of the work support 71. The inner surface of the piston head is engaged by a positioning device 212 which is moved forward by a rod 222 actuated by a pneumatic cylinder 225. During the forward movement on this rod a shoulder 220 engages a driver 215 which is then carried forward until projections 214 on the driver engage with the gudgeon pin bosses of the piston. During the chucking of the work, the advance of the tail centre first overcomes the pressure of springs 221a but when the member 212 advances the higher pressure which is admitted to the cylinder 225 causes the centre 70 to be pressed back until the fixed outer position of the member 212 is reached. Air is admitted through a valve 123 to a pipe 122 leading to the clutch 76 which is thus disengaged to stop the machine if failure in the air supply occurs. A full pressure branch pipe 124 and a reduced pressure branch 125 lead to a valve casing 230 containing piston valves controlling the various cylinders. These valves are actuated by a number of cams 240 .. 243 mounted on the cam shaft 50 and acting through rocker arms 235, Fig. 23. The full pressure air supply is connected through a valve to pipes 226, 227 feeding the cylinder 225 which operates the work positioning and driving members. The remaining cylinders are supplied from the reduced pressure line 125. The piston valve 234 controlling the supply to the gripper cylinders 174 is actuated by a cam 240, Fig. 31, which first shifts the valve to admit air to move the piston 173 to the position shown in Fig. 4. The valve is then reversed to move the parts to the delivery position, Fig. 6. A high spot 285 on the cam then again reverses the valve for a short period until the piston reaches the mid position, whereupon the valve is shifted to a central position in which air is admitted to both sides of the piston to hold the same against further movement.