Patent GB-546355-A (GB)
Title: Improvements in or relating to power knock-off devices for grinding machines or other machine tools
IPC: B23Q5/34
Filed: 1941-03-08
Abstract: 546,355. Feed mechanism for grinding machines &c. BROWN & SHARPE MANUFACTURING CO. March 8, 1941, No. 3173. Convention date, March 14, 1940. [Class 60] An automatic stop for the feed of a grinding-machine or other machine tool having compound slides includes yielding means to disengage a clutch and so disconnect the slides from power operation, such means being normally restrained by a detent which is withdrawn by a knock-off element controlled by dogs on one of the slides. In the application to a surface grinding- machine a saddle 12 is cross fed along a base 10 and carries a longitudinally reciprocating work table 16. The table is driven from a driving shaft 26 which drives oppositely rotating loose bevel gears 30-32 which are selectively clutched to a shaft 34 by a clutch member 36. The shaft 34 is connected through bevel gearing 38, shaft 42, and spur gearing 46 to a table feed shaft 48 carrying a splined pinion 50 connected through a gear 55 to a rack 56 on the table. The table may be manually operated from a hand wheel 57 on an axially movable shaft carrying a wheel 59 engageable with a gear 60 on the feed shaft. Cross-feed of the saddle is effected from a shaft 62 having a screwed portion engaging a nut on the saddle. Rotation of the shaft 48 acts through a friction arm 84 to rock a double pawl member mounted on a sleeve which carries one end of a rack bar 70 thus engaging the pawl with a ratchet wheel 80 and imparting movement to the rack. On reversal of the shaft 48 a return movement is imparted to the rack. The rack operates a pinion 92 on the cross feed shaft, the pinion being connected through a sleeve to a double pawl 98 which may be set to impart movement in either direction to a ratchet wheel 100 on the cross feed shaft 62. The pawl may also be set in a neutral position to disconnect the cross feed. The main clutch is shifted by the actuation of a rock shaft 108 either by a hand lever 111 or by dogs 113, on the table. The shaft 108 operates a rod 118 mounted on arms connected to a rock shaft 124 carrying the clutch-shifting levers 126. A lever arm 138 secured to the shaft 124 is associated with a load-and-fire device comprising a spring pressed cam member 142, Fig. 6, which ensures a quick throw-over of the clutch 36. In order to shift this clutch to a neutral position a rock shaft 134 carries a cross bar 164 fitted with pins coacting with opposite sides of a rod 168 extending from the lever arm 132. A hand knob 160 is connected to a torsion spring which normally urges the shaft 154 to the position shown in Fig. 2 to hold the clutch in neutral. To start the table power feed the knob 160 is rotated through 90 degrees and the shaft 154 locked in this position by a plunger 180 thus leaving the clutch 36 free to move in either direction. The clutch may be disengaged by releasing the plunger 180 which allows rod 154 to return to the Fig. 2 position. For this purpose a sleeve 188 may be rotated by a handle 200 to cause ball camming devices 196 to withdraw the plunger 180 and permit the shaft 154 to return the clutch to neutral position. Similar neutralizing of the clutch may te effected by dogs on the saddle coacting with an extension of the sleeve 188 thus stopping the table after a predetermined cross feed.