GB837732A - Method and apparatus for forming projections of a predetermined width on the external surface of a workpiece - Google Patents

Abstract

837,732. Rolling. MICHIGAN TOOL CO. Sept. 20, 1957 [March 13, 1957], No. 29731/57. Class 83 (4). In a method of forming projections of a predetermined width, e.g. helical gear teeth, splines, oil grooves, &c. on the external surface of a workpiece, a rack-type tool having a narrow band of teeth of a shape conjugate to the projections is rolled along a helical band on the surface without relative axial movement between the tool and the workpiece, so that successive convolutions of the helical band overlap on the workpiece to extend the projections to the said predetermined width. A tube is rotatably supported at one end by a rotatable mandrel and at the other end by a spindle or a tail stock. Hardened steel racks or platens 29, 31 mounted on carriages 27, 28 and reciprocated on tracks 25, 26 by cylinders 32, 33, each have a diagonal band or zone 37, Fig. 3, of conjugate-forming teeth 44, 48, Fig. 4, the teeth rolling along a helical band on the surface of the tube when the racks reciprocate tangentially to the tube to progressively form splines of a predetermined width by cold-rolling. The teeth 48 at the leading end of zones 37 either have a downwardly-inclined pitch line or have the tops ground off so that the racks engage the tube smoothly. Gripping teeth 51 in zones 36 of the racks have a similar form to teeth 44, 48 but are ground down to the pitch line so that they partially form the splines prior to the action of the teeth 44, 48 and also rotate the tube. Conjugate teeth 52 in the zones 38 of the racks have their tops slightly ground off and burnish the fully-formed splines or projections. The distance apart of platens or racks 29, 31 is adjustable by gibs 34, 35 to suit various sizes of work. Each rack may have more than one band of fully conjugate teeth inclined in the same or opposite directions. Specification 797,860 is referred to.