GB1485391A - Gear forming - Google Patents

Abstract

1485391 Rolling gears SOUTHWESTERN INDUSTRIES Inc 21 Aug 1974 [31 Aug 1973] 36687/74 Heading B3M Teeth are cold rolled into the smooth surface of a workpiece gear blank by a rotatable profiled forming roll, the final forming pressure between gear and roll being increased progressively over several rotations of the blank. In one form of apparatus, a profiled roll 29, Fig. 1, is supported in the bifurcated ends 33 of a holder 31. The holder is connected by a spring beam 39 to a main support 28 which can be held in the cross slide of a lathe. When the holder is moved towards a workpiece gear blank rotated in the lathe, the initial contact causes the beam 39 to bend until stops 35 and 36 contact. This provides an initially soft contact between roll and blank, with the full rolling pressure only occurring after the stops have moved into contact. The blank 12, Fig. 3, is held between supports 14 and 15 mounted in the headstock and tailstock of the lathe, the support 14 having a driving pin 25 which co-operates with an aperture in the blank. Supporting rolls may act on shoulders 43 of the supports 14 and 15. In an alternative form of apparatus, Fig. 4, the blank is introduced axially into the space between two cantilevered rolls 48 and 50. The rolls are intergeared to be driven at the same speed by a common motor. The roll 48 is fixed, whereas the roll 50 is supported in a housing 49 pivoted at 51 and movable by a hand screw 110. As the screw is initially rotated, a spring 120 within the screw acts on a pin 116 fixed to the housing to produce a rolling force related to the spring stiffness. The full rolling force is exerted when the end of the screw contacts an abutment 118. An adjustable assembly 56 biases the rolls apart and limits the extent of movement of roll 50 towards roll 48. Backlash in the drive to the rolls is prevented by the use of friction washers (Fig. 6, not shown), and the rolls are secured to their supporting shafts by a friction connection. A holder (Fig. 8, in plan) for presenting a blank between the rolls 48 and 50 includes a longitudinally movable slide 81 having a blank supporting assembly 92. The assembly fits within a slot in the slide and is shaped according to the particular blank being rolled. A weak plate spring 97 holds a blank in place but places no constraints on the blank during rolling. The blank may be a pin of 0À05 inch diameter. The work rolls or roll are of significantly greater diameter (say 2 inches) than the blank, and may be adapted to produce spur, helical, bevel, tapered or internal gears.