Patent GB-804606-A (GB)
Title: Improvements relating to machine tools
Inventor: STEPHAN HALLIS NOAH
IPC: B23B39/02
Filed: 1955-04-21
Abstract: 804,606. Controlling change-speed gearing; clutches. NEW BRITAIN MACHINE CO. April 21, 1955, No. 11579/55. Class 80 (2). [Also in Group XXII] Control mechanism for a machine tool comprises electric switch means for controlling power-actuated means 22, Fig. 4, for moving a member C, Fig. 1, relatively to another member A and relatively movable means 185, 197, Fig. 9, for operating the switch means to position the member in a predetermined number of positions. The spindle 17 of a horizontal boring, drilling and milling machine is rotated and fed axially by a reversible spindle motor, and is traversed rapidly by a reversible motor 23, Fig. 3. The motor 22 provides the feed and rapid traverse movements of the head C and back-rest G through screws 16, 18 and of the saddle E and table F through screws 153, 150. The three motors and their drives are operated by controls on the base A, the head C and a pendant H or by an automatic indexing control. The spindle 17 is rotated from the spindle motor through line-speed gearing J, a vertical shaft 28, a gear 46 or 47 and a gear 44, 45 or a gear 50 for a high-speed drive. The gears 46, 47 are moved by a handl ever 52. The spindle is fed by a screw 53 engaging twin nuts 54 and rotated by gears 56, 57, 60, 62, shaft 63, an overload clutch 83 and change gears M. The direction of rotation of the screw is determined by a clutch 71 operated by solenoids 74, 75 attached to cam members 76, 81. The screw may also be rotated by a hand wheel 85 or crank 86 associated with dials, or by the rapid traverse motor 23 connected through gearing 90, 91, 93 to the shaft 63. The feed screws 16, 18 for the head and back-rest and the feed screws 150, 153 for the table F and slide E are rotated in either direction through solenoidoperated clutches S, S<SP>1</SP>, S<SP>11,</SP> or shaft 100, an over-running clutch O, change-speed gearing N and the motor 22. A fast speed is engaged by a solenoid 106, bell-crank 107, friction clutch P and a clutch 115. When the latter drive is engaged, the inclined sides of the clutch teeth 115 move a clutch part 113 against a spring 117 and disengage teeth 112 on the clutch O to disengage the feed drive. The screws 16, 18 can also be rotated by a hand wheel on a shaft 145. The push buttons on the pendant H, Fig. 5, for controlling the jog and feed movements are illuminated when depressed. The controls are interlocked so that no movement can take place if the spindle is not rotating. The pendant includes a button 180 to cause every movement operating to continue at a rapid rate, a button 181 to start the motor 22, a button 182 to stop all feeds and a button 183 to stop the whole machine. Over-travel switches are also provided, together with interlocks to prevent attempted actuation in two directions at once. The automatic indexing control is put into operation by rendering the spindle feed-up and table jog-back switches 167, 170, 173 and 175 inoperative and by rotating a lever 210, Fig. 10, on a box 185, to the position shown. The latter lever is associated with the automatic control for the spindle head and a similar lever is provided for the table F and a further one for the slide E may be provided. The control for the head only will be described. The lever 210 rotates a block 211 having a groove 226 in which a pin 225 on a control rod 190 can move freely. When the machine is controlled by the pushbuttons the lever 210 is rotated to a position in which the bottom of the groove 226 abuts the pin 225 and renders the control rod 190 inoperative. Otherwise, a control bar 197, secured to a support 199, is formed with grooves 203 at the positions in which it is desired to set the head as it is moved downwardly. The grooves are engaged in turn by a finger 192 formed on the rod 190. When the finger engages a groove, a spring rotates the rod to release a pin 204 from a switch 186, to allow a plunger 207, which passes through a dial indicator 208 to a switch 187, to enter a recess 206 and to release a switch 188 as a plunger 231 enters a recess 232. In operation, with the rod 190 and its finger 192 above the first groove 203 as shown at the top of Fig. 9, the button 168 is depressed to move the head downwardly.. At first, a solenoid 134 is actuated to move the clutch S and rotate the screws 16, 18 at feed rate. Subsequently, the clutch P is operated to feed the head downwardly at a fast rate. Consequently, overshooting occurs when the finger 192 drops into the first groove. The rod 190 rotates and the pin 204 releases the switch 186 causing the clutch S to be moved to neutral. The rotation of the rod further allows the switch 187 to close, causing the clutch P to be released as the solenoid 106 is de-energized and the clutch S to be engaged to move the head upwardly at the feed rate. When the finger 192 is turned by the top edge of the groove 203, the switch 187 is re-opened and the clutch S is returned to neutral to stop the head in its adjusted position which can be checked on the dial indicator 208. When the button 168 is again depressed, after the appropriate boring &c. operation has been completed, the head moves at feed speed until the finger 192 clears the groove 203 when the fast rate becomes operative.