Patent GB-638206-A (GB)
Title: Improvements in or relating to a milling machine
IPC: B23F5/22
Filed: 1947-07-29
Abstract: 638,206. Gear &c. cutting. BARBERCOLMAN CO. July 29, 1947, No. 20409. Convention date, Feb. 3, 1940. [Class 83 (iii)] [Also in Group XXXVII] A hobbing or like machine comprises a frame having horizontally-spaced columns 21,22, Fig. 1, top and base members 20, 23 rigidly connecting the columns and defining therewith a central opening, a work-supporting spindle 25 mounted on the frame for vertical move - ment in the opening, a tool-supporting spindle 53 mounted on the frame for horizontal movement in the opening and into and out of operative relationship to the line of movement of the spindle 25, and means for driving and translating the spindle. The work spindle 25 is mounted on a slide 26 which also carries a vertically-adjustable tailstock 133 and is fed along the column 21 by a feed-screw 144 driven from a motor 150. In addition, a motor 322 in the column 21 is arranged to drive the feed-screw 144 through a gear-train 318 ... 321 in order to effect rapid traverse of the work slide. The tool spindle 53 is carried by a hollow slide 31 which is movable to and from the work spindle 25 along horizontal guides 30 carried by the column 22. Both the spindles are rotated through gearing from the motor 150. Tool support and operation.-The tool spindle 53, Fig. 4, is journalled in a member 47 which is adjustable by a screw-threaded shaft 49 along a guide-way in a plate 35 forming the end wall of the hollow slide 31; this plate 35 is rotatable on the slide by a worm 39, Fig. 2, engaging a gear segment 37. The slide 31 is fed along the guides 30 by hydraulic means in which fluid is fed to the opposite ends of a cylindrical bore 57, Fig. 16, formed in the slide and engaged by a piston 58 on a rod 59 projecting from the column 22. The slide is clamped in its extended position by two shoes 80, Fig. 6, which are seated in the upper face of a gib plate 72 secured along the lower edge of each guide 30 and raised to engage a tapered gib 74 by plungers 77, Fig. 16. The plungers are operated hydraulically from pistons 91, 92 which work in cylinders 69, 70 and are connected by lever arms 84 with the upper ends of the plungers. The limits of movement of the slide 31 are determined by mechanism in the form of a nut 103, Fig. 16 (and Fig. 7, not shown), on the slide engaging a screwed rod 104 which is movable with the slide and is splined for engagement with a tubular shaft 105 on the column 22. The outward travel of the slide is limited by the engagement of the rod 104 with a stop-pin 116, and the retracted movement by the contact of a collar 118 on the rod with the end of the tubular shaft 105. The positions at which the stops are effective are adjustable by rotation of the rod 104 through worm gearing. The spindle 53 is driven from the motor 150 through a transmission line including a belt drive 151 and pulley 152, Fig. 12, which is mounted on a shaft 159 and adapted to be coupled thereto by a hydraulically-actuated clutch 161, Fig. 16. The shaft 159 drives a parallel shaft 187 through pick-off gears 185, 186, and either of two bevel gears 188, 189 on the shaft 187 may be set to engage a gear 190 for driving a vertical shaft 203 journalled in the column 22. The upper end of the shaft 203 extends into the slide 31 and drives a horizontal shaft 211, Figs. 4 and 12, through gearing 205, 210, the slide being movable axially of the shaft 211 without affecting the gearing. The shaft 211 projects through the plate 35 in order to drive, through gearing 213, 214, a shaft 215 which carries an elongated pinion 216 engaging a gear 217 on the tool spindle 53. Work support and operation.-The slide 26 has an elongated nut 145, Fig. 1, for engaging the feed-screw 144, and a hollow casing 131 for supporting the work spindle 25 and enclosing the driving mechanism therefor. The spindle is supported on the upper and lower walls of the casing by combined radial and end thrust bearings (Fig. 9, not shown). The work spindle 25 is driven from the transmission system of the tool spindle through a worm 260 and wormwheel 140, Fig. 12, the shaft 249 of the worm being connected through change-speed gearing 234 ... 243 to a bevel gear 230 splined for vertical movement with the slide on a vertical shaft 226 on the front of the casing 131 ; the shaft 226 is driven by gearing 220, 221, 225 from the shaft 203. In order to feed the slide 26 for the cutting action, the feed-screw 144 is coupled by a hydraulically-actuated clutch 146 to a vertical shaft 287 which is driven through worm-gearing 283, 284 from a shaft 268 connected through a transmission line including change-speed gearing 269 ... 272 with the worm-wheel 140. The movable member of the clutch 146 is connected by an arm 301, Figs. 12 and 16, to pistons 311, 312, movable in aligned cylinders 306, 309. The rapid-traverse motor 322, which operates the feed-screw through the gearing 318 ... 321, is operable in either direction (as determined by the setting of a direction switch 334, Fig. 1) under the control of a pair of relay switches R1, R2, Fig. 17, which are linked together to ensure that only one switch is operated at one time. The motor is provided with a brake 503, Fig. 16, which is held applied by springs 504 and is maintained out of engagement when the machine is in operation by the onergization of a solenoid 505. The relay switch R4 controlling the solenoid 505 is disposed in circuit with a time-delay relay R3, and it is arranged that the solenoid brake is applied only after de-energization of the motor and then only momentarily. Coolant system.-A motor 323, Figs. I and 17, mounted in the column 21, drives a pump 324 for circulating coolant through a conduit 325 ending in a flexible portion 326, the nozzle of which is adjustably secured to the slide 31. Control system.-The operation of the various hydraulic and electric components are controlled from a control-box 329, Fig. 1, arranged on the column 21. The hydraulic system includes, as shown in Fig. 16, a cycle control valve A, clutch control valve B, feed control valve C and control valve D, the position of the latter being determined by a pilot valve E which has its position reversed each time the slide 31 reaches an extreme position by a lever 120 connected with the collar 118 on the rod 104. Fluid for the valves is supplied by a pump 158 driven from the pulley 152. The valves are controlled by a set of cam-shafts which are arranged in the box 329 and also control the electric circuit shown in Fig.. 17 for operating the various electric motors. Operation.-Operation of a push-button 330, Fig. 17, energizes the motor 150 and, through the relay switch R4 and time-delay R3, the brake solenoid 505 so as to release the brake 503. As shown, the machine is set for upward feed and rapid downward traverse, and movement of the cycle lever shaft 375, Fig. 16, by a handle 337, depresses the cycle valve A and clutch valve B through arms 376, 379, the valve A being locked in this position by a latch lever 415 ; as a result, fluid passes to the slide cylinder 57 so as to advance the slide 31, and the clutch 161 is engaged by fluid passing to its operating cylinder 173 so as to drive both spindles. A cam 381, Fig. 17, on the shaft 375 also closes a switch 396, opens a switch 384 in the circuit of the rapid traverse motor 322, and closes a switch 387 in order to energize the coolant motor 323. When the slide 31 reaches its advanced position as determined by the stoppin 116, Fig. 16, the pilot valve E is reversed by the lever 120 so as to reverse the position of the control valve D, whereby pressure fluid is admitted to the cylinders 70, 306, 309 in order to effect, respectively, the clamping of the shoes 80 and the engagement of the feed clutch 146 of the work-slide 26. Simultaneously with the reversal of the pilot valve E, the lever 120 closes a switch 127, Fig. 16, to set up a circuit by which the rapid traverse of the slide 26 may be obtained by manually closing one of the switches 508, 509, Fig. 17, as described below. At the end of the feed of the slide 26, a dog 347, Fig. 16, adjustably mounted thereon, engages a roller 345 on an arm on a cam-shaft 342 so that a cam drum 364 is rocked to cause a lever 423 to release the latch 415 and permit return of the cycle valve A and shaft 375 to their original positions; the pressure fluid connections are then such as to unclamp and retract the slide 31 and disengage the feed clutch 146; also, the valve B returns to its original position so as to disengage the main clutch 161, the switch 387 of the coolant motor is opened, and the switch 384 is closed to set up the rapid traverse circuit for returning the work-slide when the circuit is finally closed at the end of the retracting movement of the slide 31. As the slide 31 reaches its retracted position, the pilot valve E returns the control valve D to its initial position, thereby releasing pressure entirely from the clamping and feed-clutch cylinders. The switch 127 is also reversed to -close a circuit including a safety switch 373, switches 384, 396, and the direction switch 334 which is set to include the energizing winding W2 of the relay switch R2 corresponding to rapid downward movement of the work-slide. The rapid traverse of the work-slide continues until a dog 346, Fig. 16, thereon engages a roller on an arm on the cam-shaft 342 so as to rock the cam drum 364 and cause the latch 398, Fig. 17, to release and open the switch 396 in order to break the circuit of the motor 322; at the same time, the solenoid 505 is de-energized to permit application of the brake for a short period determined by the time-delay relay R3. Means are provided for effecting rapid traverse of the workslide in either direction independently of the cyclic control, for example to produce rapid jogging of the slide while the machine is being set up, by manually closing either of the two switches 508, 509 (according to the desired direction of traverse) which are inc