Patent GB-624218-A (GB)
Title: Improvements relating to nut-tapping machines
IPC: B23G1/18
Filed: 1947-06-16
Abstract: 624,218. Tapping. NICHOLS (TOOLS), Ltd., R., NICHOLS, R. and BROWN, W. June 16, 1947, No. 15765. [Class 83 (iii)] [Also in Group XXX] Work-piece feeding means for a nut-tapping machine comprises an inclined shoot 40, a horizontal guide 42 to the tapping position, a feed member 44 adapted by successively engaging and propelling different workpieces occupying an intermediate position in the shoot to impart feeding movements to the preceding work-pieces, and means for imparting compound reciprocatory movements to the feed member. A pair of rotary and axially-movable tap spindles are mounted in bearings 13, Fig. 4, vertically adjustable by a screw 16, and each carries a curved shank tap 8, on the stem of which the nuts accumulate until thrown by centrifugal force into a casing 9 having a shoot 10. The spindles feed downward under gravity and are raised by a pneumatic cylinder 19, abutments 23 on the casings 9 overlapping each other so that, when the left-hand spindle is obstructed, downward feed of the other spindle is prevented. The nuts are contained in two hoppers 26, each communicating with an inclined shoot 40. To facilitate delivery of the nuts to the shoots, agitating bars 30, 31, Fig. 7, of angle-section, are oppositely reciprocated by a pneumatic cylinder 38 which actuates a transverse bar 34 connected directly to the bars 31 and indirectly to the bars 30 by centrally-pivoted slotted levers 36. A flat plate 29, Figs. 5 and 7, is also secured to each bar 30. Near the end of each chute, one of the nuts is propelled forward by a feed-pin 44 adjustably secured on the piston-rod 45 of a cylinder 48; the pin is raised to engage a nut and lowered again for the return stroke by a spring 55 and by a stepped collar 53 on a shaft 50 reciprocated by a cylinder 52. A metal strip 58 secured to a plate 59 adjustably secured on a fixed plate 62 holds the nuts within the chute. An adjustable stop 43 and a guide 42 are fitted at the tapping position, a vertical extension 42a of the guide preventing rotation of the nuts during tapping. Pneumatic system.-A compressed-air operating system, Fig. 8, comprises impulse valves 69, 70, 71 which are operated by the moving parts of the machine to supply high-pressure air from a pipe 79 to operate automatic valves 66, 67, 68 controlling the supply to the cylinders of lowpressure air from a reducing valve 64 and starting valve 65. The impulse valve 69 controls the automatic valve 66 for supplying air to the spindle actuating cylinder 19 and is operated by an abutment 104, Fig. 1, attached to one of the spindles and engaging collars 106 on a rod 105 connected to the valve; if the feed of either spindle is obstructed the valve 69 is not operated and the machine stops. The im. pulse valve 70 is similarly actuated by the other spindle and controls the automatic valve 67 supplying air to the agitator cylinder 38 and feed-cylinders 48; either cylinder 48 may be isolated by means of valves 72, 73. The impulse valve 71 is operated by an abutment 111, Fig. 7, on the bar 34 of the agitator mechanism and controls the valve 68 and the cylinder 52 for engaging and withdrawing the feed pin. According to the Provisional Specification, the tap spindles are operated by separate pistons, and valves controlling the supply of compressed air to the cylinders are operated by cams on a rotary shaft. A holder for circular work-pieces is also described, comprising a pair of fixed jaws at each tapping station and a pair of sliding jaws between them, the latter having rollers bearing on a pneumatically-reciprocated wedge.