Patent GB-677527-A (GB)
Title: An automatic stop motion arrangement, more particularly for the feed mechanism of machine tools
IPC: F16H1/02
Filed: 1949-05-31
Abstract: 677,527. Lathe details. UNITED MACHINE TOOLS FACTORIES, NATIONAL CORPORATION, and NOUZAK, V. May 31, 1949 [June 1, 1948], No. 14618/49. Class 83 (iii). [Also in Group XXIV] In machine-tools the drive from a gear 2, Fig. 1, to a similar coaxial gear 3 is transmitted by a double-width gear 4 mounted on a swing- ing arm 7, Fig. 2, so as to be pressed into mesh with both gears 2, 3 by a spring 8 acting togglefashion to thrust the arm 7 against a stop 12. Upon overload, the gear 4 is forced by tooth reaction out of mesh with the gears 2, 3 to break the driving connection, and the spring 8 passes over-centre to hold the arm 7 against a stop 13. The drive is re-set manually, as by a hand-lever (not shown), fast with the pivot shaft 6 of the arm 7. The teeth of the gears 2 ... 4 are formed with intersecting involute flanks to facilitate meshing. As applied to reversing-gearing for bi-directional drive of both the longitudinal and transverse slide feeds of a universal lathe, a driving-shaft 75, Figs. 10 and 11, powered as by worm gearing (not shown), has mounted thereon two pairs of gears 81, 811 and 82, 821, the gears 81, 82 being fast with the shaft and the gears 81<SP>1</SP>, 82<SP>1</SP> rotatable thereon. Similar pairs of gears 83, 83<SP>1</SP> and 84, 84<SP>1</SP> are carried by shafts 78, 80 powered from the shaft 75 by gear pairs 76, 77 and 76, 79. Double-width gears 85, 86 mounted on swinging arms 99, 100 arranged mutually at right angles coact with the gears 82, 82<SP>1</SP> and 83, 83<SP>1</SP> and the gears 81, 81<SP>1</SP> and 84, 84<SP>1</SP> respectively and are each controlled by a spring-loaded roller 33, Fig. 6, engaging either a central cut-out as shown, or bevelled flanks 34, 35, on the respective swinging arm. When the roller 33 engages the cut-out the double-width gear is held free of both the respective coacting pairs, and when the roller engages the flank 34 or 35 the arm is held against a stop 29 or 28 and the gears are meshed for drive in one or other direction from the shaft 75 to, as the case may be, a gear 87 meshing both the gears 821, 831 or a gear 94 meshing both the gears 81<SP>1</SP>, 841. The gear 87 powers the longitudinal slide feed through gears 89, 90 and a pinion and rack 92, 93, and the gear 94 powers the transverse slide feed through a gear 95 and a screw-and-nut mechanism 96, 97. Control of both swinging arms 99, 100 is effected by a ball-mounted hand lever 101 moving in a four-armed slot 103 and engaging crossed slots on the arms 99, 100, the arrangement being such that the slide movements follow those of the lever 101 in direction. Stops, such as 106, adjustably fixed on the machine bed, limit the longitudinal slide feed and cause overload disconnection of the drive in either direction; stops, such as 107, mounted on the longitudinal slide member, acting similarly as regards the transverse feed. As applied to the control of a semi-automatic lathe, the transverse slide feed screw 53, Fig. 7, and the longitudinal slide feed driving rack pinions 45 are alternately powered from the driving shaft 36 through a double-width gear 58 alternately meshable with gear pairs 50, 51 and 38, 39, the gears 38, 50 being respectively fast with the shaft 36 and a shaft 49 driven therefrom by a gear pair 37, 47, and the gears 39, 51 being loose on these shafts and connected to the rack 45 and screw 53 by gears 40, 42, 43 and gear 52 respectively. The gear 58 is mounted on a swinging arm 55 similar to that of Fig. 6 but without a central neutral cut-out, so that on throw-out of one drive, at an overload determined by the adjustable tension of the spring loading, the other drive is engaged. A hand lever 67 is provided for initial drive engagement of either feed. Stops, such as 70, 72 are provided at appropriate points in the paths of travel of the slide housing and the transverse slide respectively, enabling the automatic machining of a stepped work-piece to be effected by alternate overload switching-in of the feeds, a final stop operating an electric switch causing rapid return of the slide to the starting point ready for a fresh operation.