GB591814A - Improvements in or relating to the operation of the tools of gear cutting machines - Google Patents

Abstract

591,814. Gear-cutting. AEPPLI, A. Aug. 22, 1944, No. 16021. Convention date, July 30, 1943. [Class 83 (iii)] In a gear-cutting machine of the kind in which the tool is reciprocated relatively to the work whilst the latter rotates continuously so that the tool enters different tooth spaces at each reciprocation, one or more rotating cams are provided on the tool ram to relieve the tool on the idle strokes and restore the cut on the working strokes, the tool holder being brought into engagement with an abutment on its carrier by the cutting action of the tool. The tool may be a rack-type planing cutter or a grinding disc having a cross-section representing a rack tooth. In a planing machine, the rack cutter 130 is carried by a clapper box 129 pivoted at 131 on a head 128 which is angularly adjustable about a shaft 112 on the ram 115 to give the correct resultant motion between the tool and work depending on the rotation of the work and the helix angle of the teeth thereon. A shaft 135 journalled in the head 128 carries a cam 136 on each end engaging a roller 137 on the box 129 and is rotated one revolution for each reciprocation of the ram so that on the upward stroke the box will be rocked away from the work against the action of a spring 139. On the downward stroke the cams rock the box until a stop surface 100 thereon is just clear of the head 128, this clearance being taken up when the tool engages the work. The shaft 135 is driven by spur gears 133, 134, shaft 132, bevel gears 111, splined shaft 109, spur gears 107, bevel gears 104 and shaft 103 driven from the ram-reciprocating shaft 141 either directly or through gears. The gear 133 is removable from its shaft to allow rotation of the cams independently of the central driving gear 113 in order that the box 129 may be rocked at each end of the stroke irrespective of the angular adjustment of the head 128 on the ram 115. The edge cams 136 may be replaced by a cam disc having a continuous groove engaging a roller on the box 129. The main shaft 141 carries two opposed involute cams 117, 118 for reciprocating the tool at a uniform speed during the cutting stroke, the cams acting on rollers 119 mounted on a slide 116 movable in guides on a member 102 which is angularly adjustable about the shaft 117 on the standard 101 of the machine. A rack 121 on the slide 116 rotates a shaft 124 on the member 102 carrying a pinion 125 engaging a gear 126 attached to another gear which meshes with a rack on the tool ram 115.