Patent GB-423837-A (GB)
Title: Improvements in or relating to machines for fashioning articles successively from bar stock
IPC: B23B13/00
Filed: 1934-06-05
Abstract: 423,837. Feeding stock-bars in lathes. BROWN & SHARPE MANUFACTURING CO., Providence, Rhode Island, U.S.A.- (Assignees of Rich, C. A.) June 5, 1934, No. 16768. Convention date, June 6, 1933. [Class 83 (iii)] An automatic screw or similar machine operating on bar stock has replenishing means for automatically feeding a fresh stock bar when the bar being worked is used up, the replenishing mechanism being timed to begin the advancing movement of the new bar during the continued operation on the old bar and to complete the advancing movement to bring the leading end of the new bar into operation position immediately after completion of the last operation on the old bar. In a machine similar to that described in Specification 300,619, [Class 83 (iii)], the work stop 28 is swung into and out of operative position by a pinion engaged by a vertical rack bar 40 operated by cam on the main shaft 36. The magazine comprises frames 54 enclosing a stack of bars over a member 50. The reserve bars are normally supported on a plate 56 carried by a series of yokes 64 which are rocked by a cam 80 on a cam shaft 82 to remove the plate 56 and permit a fresh bar to drop into the guide 52. When this occurs, fingers 62 are moved forward to support the remainder of the stock bars. The new bar is moved along the guideway by a feed plunger 67 secured to a feed slide 70 operated by a spiral cam 78 on the cam shaft 82. When a fresh bar is to be fed the latter is driven from a continuously driven clutch member 118 coacting with a sliding clutch part on the cam shaft, the clutch being normally held in disengaged position by a latch pin on a lever 125 pivoted at 127. A transverse drop lever 130 supports one end of a longitudinal lever 134 and when the end of the old bar passes from under the drop lever, the lever 134 releases a pawl 140 connected to the chuck operating mechanism so that at each feed movement, the pawl feeds a rack bar 138 which is set according to the number of pieces the remaining length of bar will produce. When the last piece has been produced a dog 152 rocks a lever 154 to move a thrust bar 160 under a cam lever 44 to hold the stock stop 28 inoperative. A second dog 162 carried by the rack 138 at the same time rocks a lever 164 to disengage the main clutch and stop the machine. The mechanism for selecting and feeding a fresh bar is timed to be started before completion of the operation on the old bar so that the new bar has been moved up to within a short distance of the old bar by the time the last operation is completed and the machine stopped thus reducing the inactive period. For this purpose the rack bar 138 carries an adjustable dog 170 provided with a cam projection 169 which at a predetermined point before the exhaustion of the old bar engages a spring finger 171, Fig. 8 to depress the latch lever 125 thus withdrawing the latch pin and engaging the clutch 118 to operate the cam mechanism for selecting and feeding the new bar. The latch lever is held up in the clutch engaging position by means of latches 182, 186. As the shaft 60 is rocked for the feeding of the new bar a cam surface 173 on the bar 57 resets the drop lever 130. Means are provided to move the lever 134 out of alignment with the tail of the pawl 140 so that the intermittent advance of the rack bar is not interrupted when the drop lever is reset. At the end of the feed and return movement of the feed slide 70 produced by the cam 78 a cam 196 on a bracket 84 secured to the feed slide rocks a lever 190 to release the latch 182 whereupon the latch pin 124 engages a cam groove in the clutch sleeve to disengage the clutch and stop the cam shaft 82. The precise adjustment of the dog 170 is determined by a comparison of the times for manufacturing an article and for feeding in the new bar so that the last article may be completed before the new bar engages the waste end. If the time for turning out one article is greater than the time required to place and feed a new bar, means are provided for interrupting the feed of a new bar until the last operation on the old bar has been completed. For this purpose a second lever 204 adjustably mounted on the rock shaft 192 carries a pivoted arm in the path of the cam 196 so that the latch 182 may be released to disengage the clutch member 118, and stop the feed cam at a predetermined point before the leading end of the new bar engages the old bar. When the last article is complete the feed movement of the slide 70 must be completed to eject the waste end. For this purpose a second cam surface 208, Fig. 13, on the dog 170 is arranged at this time to operate the latch lever 125 to permit re-engagement of the clutch 118. As the feed slide 70 reaches the limit of its advancing movement an adjustable dog 214 thereon actuates a lever 216, which acts through a push bar 220 to withdraw the bar 160 from a cam lever 44 and permit the return of the stop lever 28. At the same time the starting lever 164 is rocked to engage the machine clutch 38. As the feed slide 70 reaches its advanced position the pawl 140 is disengaged from the feed rack and is locked in retracted position. The rack bar 138 of the timing mechanism is returned by a spring plunger 236 which during the return of the feed slide, engages a lug 238 on the rack.