Patent GB-553285-A (GB)
Title: Improvements in screw and similar machines
IPC: B23B7/04
Filed: 1942-02-12
Abstract: 553,285. Lathes. BROWN & SHARPE MFG. CO. Feb. 12, 1942, No. 1886. Convention date, Feb. 10, 1941. [Class 83 (iii)] In an automatic screw machine for bar stock a tool slide shiftable axially of the work carries a transversely-movable turret-support which is yieldably fed towards the work to an extent limited by stop means to perform a cycle of single point turning operations on the work. The work bar is fed through a headstock 14. The base 10 carries a cross slide 18 and a longitudinally movable tool slide 22. The cam shaft 24 is driven through reduction gearing from the main shaft which carries a pulley 26. A toolturret 34 rotates on an axis parallel to the work axis and is carried on a rocker-supporting member 36 supported on a pivot shaft 42 mounted on arms 46 on the tool slide 22. Collars 48 prevent axial movement of the shaft 42. The longitudinal movement of the tool slide is effected by a cam 55 on the main cam shaft, the cam engaging a follower 54, Fig. 2, on a lever 50 pivoted at 52 and having another arm 58 formed with a gear segment 60 co-acting with a segment 64, Fig. 3, forming part of a bell crank lever which has a slotted arm 74 connected to a block 68 mounted in a groove 70 in the tool-slide. Adjustment of the block along the slot 74 varies the tool slide movement. The cam moves the tool slide positively to the left and return movement is by a spring 76, Fig. 3, engaging a block 82 secured to the tool slide. Rocking movements of the turret-support to move the tools away from the work are effected by the cross slide 18 which carries a guide 84 having a flat guide surface 86 engaged by a follower 88 on a pivot pin 90, the follower being urged downwardly by a spring. A loose plate 96 pivoted on the pin 90 can be swung from the inoperative position shown in Fig. 2 into engagement with the surface 86 to raise the turret rocker for tool setting. The guide surface 86 is sloped, Fig. 2, so that as the cross slide moves rearwardly the follower rides up the surface and lifts the turret away from the work while forward cross slide movement moves the turret towards the work. The guide surface is adjustable angularly and vertically. The cross slide movement is controlled by a cam 117 on the cam shaft, this cam actuating a lever 118 having a segment engaging a rack 126 on the slide 18. The movement towards the work is effected by a spring 128, Fig. 3, and adjustment is provided to set the cross slide relative to its actuating mechanism. In order to support the work close to the tools the slide 22 is fitted with a bracket 156 provided with a split bearing to receive the rotating work. The work stop 158 is adjustably mounted on the tool slide and is positioned by an extreme movement of the tool slide to the left while the turret is in its upward position. The zone of operation of the tool slide being somewhat to the right of the stop position, the stop is withdrawn during operation clear of the tools. The turret, Fig. 4, is mounted on a shaft 140 carried in thrust roller bearings 142, 144, and is fitted with eight tool sockets 146 for single-point turning-tools 150. Locking is effected by a spring-urged longitudinal bolt 151 coacting with notches 149 in the turret. The locking bolt is withdrawn for indexing by a solenoid 160 the armature 162 of which is drawn inwards against a spring 163 when the solenoid is energized. When this occurs a lever 168 on a rock shaft 170 is operated so that the lever arm 172 withdraws the locking bolt which is spring urged into the next notch when the solenoid is de-energized. The bolt may be operated manually by a hand piece 174. The indexing movement is effected by a second solenoid 178 the armature of which, when energized, is drawn inwards to operate a bell crank lever 184 pivoted at 186. Thereupon a pin 188, Fig 4, on the lever engages one of the spiral grooves 192 in the index wheel 190 and rotates the turret through one station. At the end of this movement a conical part 204 of the index wheel lifts the pin 188 to the position shown in Fig. 4 so that the pin is clear of the wheel on its return swing, at the end of which the pin is returned by an abutment 206, Fig. 4. The rocking movement of the turret towards the work is accurately determined for each turret position by stops 214 which are radially adjustable in a stop disc 212 mounted on the turret spindle, these stops coming successively into engagement with a stop surface 216 on the tool slide. The solenoids controlling the indexing mechanism are energized through snap switches 220, 222, operated by dogs on the cam shaft through a lever 254 pivoted at 256, the lever carrying stop screws actuating the respective plungers 246, 252, of the switches. The arrangement is such that the switch controlling the locking bolt is actuated before the switch controlling the indexing movement but both solenoids are deenergized at the same time. The switch-actuating dogs 266 are spaced around a disc 268 on the cam shaft and coact with a follower 270. The complete cycle for making a staff 274, Fig. 7, is described in the Specification.