Patent GB-502401-A (GB)
Title: Improvements in or relating to milling and like machine tools
IPC: B23C1/02
Filed: 1937-06-14
Abstract: 502,401. Milling-machines etc.; gearing; clutches. KEARNEY & TRECKER CORPORATION. June 14, 1937, No. 16483. Convention date, June 22, 1936. [Class 83 (iii)] [Also in Group XXIV] A machine tool, such as a milling- machine, has the spindle clutch operated by a fluid-pressure cylindsf the supply to which from one pump is controlled by a pilot valve connected by a single pressure fluid channel to a supply from a second pump. The frame carries a horizontal tool spindle 22 with the usual overarm 23 while the knee 24 sliding vertically on ways 25 carries a saddle 26 and a table 27, the latter moving transversely of the spindle. A motor located in the column drives a power pulley 31 which may be connected by a. friction clutch 36 to a hollow driving shaft 35 connected by bevel gearing 37 to the spindle driving train located within the column. The friction clutch is operated from a rod 38 through a cone 40 and fingers 39. When the clutch is disengaged brake mechanism 43 causes the quick stopping of the spindle. The gear 37 is connected through reversing bevels 46 to the shaft 58 carrying a sliding pair 61. This shaft imparts a two speeds drive to a shaft 60 carrying gears coacting with two sliding pairs on another shaft 65. This shaft also carries another sliding pair coacting with gears on the spindle which is thus selectively driven at sixteen speeds. The gear pairs are shifted by mechanism similar to that. described in Specification 499,189 and an indicating dial 92 is arranged to indicate the spindle speed obtained by the various lever positions. The table-operating power train includes vertical shafts 104, 105 operated as described in the above-mentioned Specification, the former operating the rapid traverse motions and being driven from the pulley 31 and the latter operating the feed traverses and being driven from the shaft 35 only when the spindle-driving train is in operation. All the mechanism for driving the table is carried directly by the saddle which is of hollow construction and encircles the knee 24, Fig. 4, the compartment 121 serving as a reservoir for lubricating oil which also serves as liquid for the hydraulic control system. Ribs 122 stiffen the saddle and assist in oil cooling. The shaft 114, driven from shaft 105, is connected through gearing 126, pick-off gears 132, shaft 133 and pinion 135 to gear 136 associated with overrunning clutch mechanism 137. This is connected through gears 138 and reversing bevel gearing 141 to the table screw 145. To avoid backlash between this screw and the nut 151 the latter consists of upper and lower half nuts 155, 154 which have relative axial movement so that the two half nuts may be caused to bind on opposite sides of the thread. The table has a coolant drain opening 162 draining into pockets in the saddle and thence by pipes 165 to a coolant reservoir. For rapid traverse of the table, the shaft 112 is connected by gears 167 and rapid-traverse clutch 169 to the driving gear 138 on a shaft 192, Fig. 13, the clutch 137 permitting the .overrunning of the feed drive. When the rapid traverse clutch 169 is disengaged, a friction clutch 197, Fig. 13, quickly retards the speed of the shaft 192 to that of the slowspeed gear 136. The reversing bevel gearing of the table drive is actuated by a fork 171, Fig. 5, operated by a gear segment on a hollow shaft 175 rocked by a lever 176 having a central neutral position. Automatic actuation of this clutch is effected by a control rod 177 actuated by gear teeth on a rotatable sleeve actuated by stop dogs 186. These dogs neutralize the clutch and stop the table in predetermined positions, the table being restarted by the handle 176. For automatic reversal.and control of the table speed through the clutch 169 hydraulic mechanism is provided. The clutch rod 177 carries a hydraulic piston 187, Fig. 13, and the rapid traverse clutch 169 may be engaged by fluid passing to chamber 203 and passage 194. A spring 195 disengages the clutch when the fluid pressure is released. The spring 195 also actuates the braking-clutch 197 to cause prompt resumption of the feed speed determined by the gear 136. The supply to line 202 is controlled by a valve 201, the plunger 204 of which is operated by a rock shaft 212 operated by a rod 218, Fig. 5, which may be moved by in-and-out movements of the table control lever 176. For automatic control, the rock shaft 212 carries an arm connected to a tripping post 184 which is moved upwards or downwards by dogs 223, 224 on the table. For manual or automatic operation of the spindle clutch 36, the main clutch rod 38 is operated by a fork 226, Fig. 13, on a rod 228 actuated by a hydraulic piston 230 supplied through pilot valve 234. A spindle control valve 236 is operated manually or automatically, and fluid delivered by a pump 247 flows to port 249 in this valve and thence to port 207 of the rapid-traverse control valve 201. From this valve fluid may flow through a line 238 to the pilot valve. In the position shown in Fig. 13, pressure fluid in line 238 actuates the pilot valve stem against a spring 268 and allows fluid from a pump 232 to pass to the piston 230 and engage the main spindle driving clutch. In the right-hand position of piston 230 this fluid passes through lines 273, 275 to lubricate the entire column mechanism. When the valve 236 is moved to stop position, the pressure is relieved from the pilot valve which is then returned to admit fluid to line 280 and return piston 230 to disengage the spindle clutch. Fluid from line 280 also passes into the line 273 leading to the lubricating system. The trip mechanism for automatic table reversal includes plungers 285, 286 coacting with a dog 287 and connected through lever mechanism, Fig. 4, to the spindle 288 of a valve 254. In Fig. 4, the plungers are in central position but when dog 287 moves plunger 286 downwards, the valve plunger 288 also moves downwards to a position wherein pressure builds up in line 248 past relief valve 299 and maintains low pressure. in line 256 for actuating the rapid traverse clutch and in pilot valve 234 to keep the main clutch engaged. After further movement of plunger 288, fluid is admitted to the reversing cylinder 188 to reverse the table travel. Movement of piston 187 allows fluid to pass through lines 314, 316 to valve 201 whereby plunger 204 is moved up to connect line 256, 202 to actuate the rapid traverse clutch. The plunger 288 is then returned to neutral position and opens both ends of cylinder 188 to exhaust so that the reversing mechanism may be actuated mechanically. The plunger 204 is also left free to be actuated mechanically by the trip mechanism. To prevent marring the work, the spindle is stopped when the automatic table reverse is operated. For this purpose, the port 263 is closed in the rapid traverse position of valve 204, thus cutting off pressure from the pilot valve which is moved by its spring to direct fluid from the pump 232 to the clutch operating cylinder to disengage the clutch. After a predetermined rapid traverse, the tripping post 184 is engaged by a dog to move plunger 204 to feed position, actuating the brake 197 and also admitting fluid to line 238 to cause reengagement of the spindle clutch. At the end of the traverse, another dog moves plunger 285 downwards, raises valve plunger 288 and admits fluid to actuate the reversing piston 187. The parts may also be set so that the spindle is not stopped when the table is reversed at high speed.