GB926203A - Mechanical lock-up means for overriding drives - Google Patents

Abstract

926,203. Metal strip feeds. F. J. LITTELL MACHINE CO. Feb. 27, 1961 [March 2, 1960], No. 7064/61. Class 83 (4). [Also in Group XXIV] A strip feeding mechanism comprises feed rolls, a feed roll drive shaft, intermittently operating driving means for the feed roll drive shaft including an over-running clutch having an annular outer housing comprising the driving member and a hub keyed to the feed roll drive shaft and comprising the driven member of the clutch, lock-up means for releasably locking the hub to the housing including at least one locking member carried by the hub, resilient means for actuating the locking member to render the lock-up means operative, and a reciprocable member adapted to apply a hammer blow against the resilient means for instantaneously releasing the locking member. The mechanism includes a frame 10 supporting a main shaft 15 carrying a face plate 16 to which is fixed a guide block 17. The block rides in a slot 18 in an arm 20 which is pivoted to the frame at 21 and which has a groove 24. A block 26 slides in the groove 24 and carries a stud shaft 28 on which runs the lower end of a rack 30. The stroke of the rack can be altered by adjusting the position of the block 26 by a screw 25. Also mounted on the frame are two feed rollers, only the lower one 32 of which is shown, and which is fixed to a drive shaft 33 supported in bearings 34,35 and 36. Fixed to the shaft is a gear 40 which meshes with a similar gear fixed to the upper feed roll. The rack 30 meshes with a pinion 42 having trunnions 47 and 48 which form journals for a housing 43 which maintains the rack and pinion in mesh. The pinion 42 is free to rotate on the feed roll drive shaft 33 and runs on a bearing sleeve 49. The trunnion 48 is integral with the housing 50 of the over-running clutch 51. The hub 52 of the clutch is keyed to the drive shaft 33 and is provided with off-centre gripping faces 54 and 55 (Fig. 6) which receive hard steel inserts 56 that are biased by springs 62 and pins 61 to the locking position. The hub 52 also has three equally spaced lock-up elements each consisting of a roller 70 and a piston 65 which can be moved outwardly by a cam rod 71 which slides axially within the feed roll drive shaft 33 and is biased to move the rollers to the locked position by a spring 74. Instantaneous release of the rollers 70 is effected by a hammer 78 which slides within the drive shaft 33 and is connected by a pin 80, which passes through slots 81 in the shaft, to a collar 83 mounted on the shaft. The collar has a groove 84 which is engaged by the upper bifurcated leg of a crank arm 85, the other arm of which is pivotally connected to a rod 92, acted on by a spring 94 and having its lower end resting on a cam 98. The cam has a helical contour which provides an abrupt drop-off edge and is adjustably mounted on a shaft 100 which rotates in timed relation with the main drive shaft 15. In Fig. 2 the hammer 78 is shown in retracted position, rotation of the cam 98 in a clockwise direction will presently allow the rod 92 to be driven down by the spring 94 and the crank arm 85 will move the collar 83 and hence the hammer 78 to the left so that the spring 74 is overcome. A timing diagram (Fig. 7, not shown) indicates that the feed cycle occupies 240 degrees of each revolution of the main shaft 15, and that a quick return is imparted to the rack 30. The cam rod 71 locks the clutch approximately 35 degrees after the start of the feed cycle, until a few degrees before the end of the decelerating portion of the feed cycle.