Patent GB-301457-A (GB)
Title: Improvements in turning lathes and like machine tools
IPC: B23Q5/14
Filed: 1928-11-10
Abstract: 301,457. Potter, W. W., (Assignees of Curtis, M. S.). Nov. 30, 1927, [Convention date]. Lathes.-In a machine tool such as an automatic lathe for chuck or centre turning, the work-spindle is driven from a constant speed driving-shaft through change speed gearing, and hydraulically operated tool-feed mechanism is driven from the spindle so that the tool-feed speeds are changed in synchronism with the spindle speeds. An independent constant-speed pump is provided for supplying fluid for idle fast motions. In the application to a vertical single-spindle automatic turret lathe, the spindle 11 carried in upper and lower roller bearings 12 is driven by change speed gearing from a power shaft 20 which carries a main driving pulley 29 and is driven through a clutch 30. The shaft 20 carries a fast gear 22 and loose gear 19 engaging respectively with an overrunning gear 21 and a fixed gear 18, these gears being carried on a shaft 17 connected to the spindle by hand change gears 16 and worm-gearing 14. The arrangement is such that when a clutch 23 is engaged the gear 21 overruns its shaft. The clutch 23. is operated by a, rod 26 connected to the piston of a hydraulic cylinder. The main clutch 30 is operated from a handlever 33 and when this clutch is disengaged a friction clutch 32 may be engaged with the housing 31 to brake the spindle. A column 39 carries a five-sided turret 40 having four tool stations and one idle station for loading. The turret may be held down against a seating 41 by means of a hydraulic cylinder 42. A series of locking bolts 48 are provided on the turret and these co-act with a slot in a block 49, to determine the successive turret positions. For indexing, the turret is raised by the cylinder 42, and indexing is then effected by means of a mutilated wheel 54 engaging a mutilated internal gear 55 and driven from a motor 51 through worm gearing 52. The turret tool slides 56 are normally held in their raised position by a jaw member 58 engaging in a groove in a fixed circular housing 60, this groove being gapped at a position in line with the spindle so that when any tool slide reaches its operative position, the member 58 is engaged by a block on a piston rod 64 to effect the tool feed. The machine base carries two vertical columns 65, 66 secured to a top plate 61 and provided respectively with cross slides 69, 70 which are operated by hydraulic cylinders 73, 74 for facing operations. The rapid movements of the various slides are effected from a constantspeed pump 82 driven by gearing, Fig. 8, from a pulley 75 attached to the main pulley 29. This pump delivers fluid to a control valve 86 controlling the cylinder 42, control valve 87 on tool feed cylinder 88 and control valves 89, 92, operating cross slide cylinders 73, 74 respectively. The worm shaft 15 driving the work-spindle is connected through a coupling 99 to pumps 100, 101, which are of the variable-delivery piston displacement type, delivery being controlled by levers 102 103. The pump 100 furnishes high-pressure fluid to the control valve 87 and the stroke of the pump may be automatically varied by a dog on the slide 56 which acts through lever mechanism on the pump control lever 102. The pump 101 supplies pressure fluid to feed the cross slide controlling valves, and its stroke may be varied by either cross slide by means of cams 115, 116 fastened to these slides and acting through lever mechanism on the pump control lever 103. The control valve 87 of the cylinder 88 consists of a body having bushings accommodating sliding valves 131, 132 which are operated by pilot valves 133, 134. The pilot valves are normally held in one position by springs but may be moved against the spring pressure by means of solenoids 155, 158 actuated by automatic electrical control devices. Low pressure fluid enters through ports 137, 138 and in the position shown in Fig, 14 the main valves are moved to the left and the high pressure entering through port 149, and the low pressure through port 137, both flow to the exhaust 148, the cylinder-head port 150 and cylinder reverse port 151 being both closed. As the turret 40 moves downwardly, a switch 152 Fig. 18, is depressed by a dog on the turret thus energizing solenoid 155 and shifting valve 133 to the position shown in Fig. 15. This moves the main valve 131 so that both high and low pressure fluid flow to the cylinder-ahead port to give the quick idle approach movement to the vertical tool slide. When the work is reached a dog 163 on the slide 56 actuates a pin 164 to cause the shift of the valve 134. This moves the corresponding main valve so that high pressure fluid enters the cylinder-ahead port and the low pressure enters the cylinder reverse port, giving slow cutting feed. On completion of the operation dog 163 depresses switch 167 causing the solenoid circuit 155 to be broken and shifting valve 133. This causes the return of the main valve 131 and the high pressure fluid then passes to exhaust while the low pressure fluid flows to cylinder reverse port and causes rapid withdrawal of the slide. This valve may also be operated by hand switches 170-172 in a switch box 218. A hand switch 174 is also provided for breaking both solemoid circuits to bring the control valve to stop position. The control valves 89, 92 of the cross slides are controlled in a similar way except that the fast ahead switches 175, 176 are operated by the turret slide while feed ahead switches 177, 178, and fast reverse switches 179, 180 and stop switches 181, 182 are operated by dogs 183, 184 on the cross slides 69, 70, respectively. Manual control switches in boxes 219, 220 are provided for these circuits. The valve 96 controlling the speedchanging clutch 24 is operated by a push-and-pull solenoid 185. cor trolled through switches 186, 187 operated by dog 163 on the tool side. Valve 86 controlling the cylinder 42 for raising and lowering the turret is normally held by a spring 190 so that fluid flows above the piston in this cylinder to hold the turret down on its seating. On starting operation a hand switch 191 is closed to operate valve 86 to cause the raising of the turret. At the top of the stroke a dog 196 closes a switch 197 and piston rod 64 closes a switch 198. Current then flows to the motor 50 which causes the indexing of the turret. After one revolution of the pinion 54 a pin 201 operates a switch to break the motor circuit and stop the indexing movement. At the same time a pin 202 breaks the circuit of solenoid 195 so that the valve 86 is returned to cause the downward movement of the turret. In operation switch 191 is first manually operated to start the turret upwards and the indexing and tool feeding operations then proceed automatically until the turret has indexed a complete revolution when a dog 203 on one face of the turret throws a switch 192 to break the turret control circuit until the manual switch 191 is operated. In some cases the low pressure pump 82 may be omitted and the necessary flow conditions for controlling the feed are then obtained by actuation of the pump levers 102, 103 and by disconnecting the pumps from the spindle and driving them at constant speed from the pulley 29 the maximum flow for the idle movements may be obtained. In this form Fig. 19, a pulley 76 drives a pulley 210 which is loose on a shaft 208 forming an extension of the shaft 15' driving the work spindle and connected thereto by a ratchet coupling 209. The pumps 218, 219 are driven from the shaft 208 through gearing 214-216. For the fast movements the shaft 208 is driven from the pulley 210 by means of a clutch 213. For the feed movements, the clutch 213 is disengaged and the ratchet 209 then picks up the drive from the shaft 15' to drive the pumps synchronously from the spindle. At the same time the pump control levers 220, 221 are shifted to give the proper pump discharge for the feed movement. On completion of the feed the levers 220, 221 are shifted to full discharge position and the drive is transferred to the pulley 210 for the quick return movements.