Patent GB-588610-A (GB)
Title: Automatic control means for change speed mechanisms for machine tools
IPC: B23Q5/14
Filed: 1944-07-05
Abstract: 588,610. Change-speed gearing. POTTER & JOHNSTON MACHINE CO. July 5, 1944, No. 12874. Convention date, June 22, 1943. [Class 80 (ii)] [Also in Group XXII] In an automatic lathe comprising a spindle, a traversing tool slide or turret and change-speed mechanism for driving the spindle and slide, the change-speed mechanism is actuated by pneumatic means controlled by electrically operated valves, the switches of the electric circuits of said valves being opened and closed by a control means actuated by the operation of the machine: The spindle 15 is mounted in the headstock 11 and is driven from a motor 18 through change-speed gearing which includes overrunning gears 23, 27, clutches 19a, 25a, external pick-off gears 28, 29 and a gear 32 keyed to the spindle. Motor 18 drives a shaft 16 which has keyed thereto gears 19 and 20 meshing respectively with a gear 21 and an overrunning gear 23 on a shaft 22 which also carries a pinion 24. Gears 21 and 24 mesh respectively with gear 25 and an overrunning gear 27 on the shaft 26 on which is mounted the pick-off gear 28. Four speeds are obtainable, one by disengaging both clutches 19a, 25a, two others by engaging one or other of the clutches and a fourth by engaging both clutches. A gear 35 keyed to the spindle drives a shaft 40 in a transmission feed-box 39 through a shaft 33 and chain 36. The turret (not shown here) mounted on ways 13 is traversed by a cam (not shown here) driven from a shaft 41 which is geared to a high-speed motor 42, by which the turret is traversed during idle periods and which is also geared through an overrunning gear 45 with a gear 46 of the feed-box. This arrangement permits of three different speeds of the turret traverse during cutting periods according to the position of a clutch 67. With the clutch in neutral position a fine feed is obtained, the drive being from pinion 51, gear 53, shaft 55, gears 54 and 56, pick-off gears F and F<1>, pinion 59, overrunning gear 60, shaft 47 and gear 46. When the clutch is engaged with the gear 63 a medium feed is obtained and the drive from gear 56 is by way of shaft 57, pick-off gears M and M' shaft 61, gears 62 and 63 and clutch 67 to shaft 47. A coarse feed is obtained when the clutch engages gear 66, the drive from pinion 54 being by way of gear 52, shaft 40a, pick-off gears C and C<1>, shaft 64, gears 65 and 66, clutch 67 and shaft 47. The clutches 19a, 25a, and 67 and also the switch for the high-speed motor 42 are all controlled by a dog drum geared to the shaft 41. The sliding parts of the clutches 19a, 25a, are operated by yokes 19b, 25b, from nested rocker shafts 72, 73 which are rocked by levers 79, 80 connected by links 81, 82 to the rods of pistons 68, 70 operating in cylinders 69, 71. Compressed air may be admitted to either side of either piston under the control of four solenoid operated valves 88a, 91a, the opening of. the valves being controlled by switches actuated by the dog drum. Air pressure in the supply pipe 93 is regulated by a regulator (not shown) which in the event of the pressure falling below a certain limit operates switches to stop motors 18 and 42. The movable element 67 of the clutch in the feed-box transmission is moved into engagement with the clutch members 67a or 67b through a lever connection with the rod 96a of a piston 96 operating in a cylinder 98 to either side of which compressed air may be admitted by pipes 100, 101, through valves 100a, 101a operated by switches actuated by the dog drum. An arm 107 extending laterally from the piston rod 96a operates through abutments 109 and 110 on a rod 108 to position a distributing valve 104 controlling the admission of pressure air from a pipe 102 to a cylinder 99 so that upon the opening of the valve 102a, under the control of the dog drum, air will be admitted to the cylinder 99 so as to move the piston 97 which in turn moves the clutch element 67 into neutral position. Specification 288,340, [Class 83 (iii)], is referred to.