Dana Corporation

Torque-Traction Technologies, Inc.

Spicer Technology Inc.

James Steven Fisher

Roland Clark Smith

Wei-Jiung Tsung

Trevor O'Bryan McKinney

John Edward Masseth

A method for manufacturing a bevel gear member, comprises the steps of providing a bevel gear blank having a gearhead, forming gear teeth on the gearhead of the bevel gear blank by simultaneously cutting gear tooth top land, gear tooth side profile and a bottom land to form an unfinished bevel gear member using a face hobbing process, and machining at least one selected surface of the unfinished bevel gear member using the top lands of said gear teeth as a datum for centering the unfinished bevel gear member, thus forming a finished product. The method is applicable for manufacturing the bevel gear member both with shaft axially extending from the gearhead and without the shaft. The bevel gear members manufactured with this method exhibit reduced runout and require simpler, less expensive tooling.

Method for manufacturing bevel gears

This invention is directed to a method of using a two spindle Hurth-Module multi-spindle (or similar) cutting machine to accomplish face hobbing of hypoid and spiral bevel gear sets. A first cutter mounted on a first spindle would rough cut the gears and a second cutter mounted on a second spindle would finish the gears with both cutters using a face hobbing process. According to this process, multiple cutters are used for a single gear, but on a single machine, thereby reducing cutter wear, increasing cutter life, and raising production output of the multi-spindle machine by utilizing both spindles. In one embodiment, a fine pitch cutter is used to create the initial rough-cut of the gear, and a second coarse pitch cutter is used to create the finish cut of the gear.

Face hobbing of hypoid gears using a two-spindle machine

Bevel gears having a carbon content of at least about 0.4% by weight, preferably 0.5% by weight are manufactured by a process which includes forging a steel blank having a carbon content of at least 0.4% by weight until a bevel gear precursor having essentially the tooth configuration and dimensions of the desired product gear is obtained, and hardening the teeth of the gear precursor by induction heating without machining of the teeth. The initial forging is precise enough so that no further machining of the teeth is required. This requires forging to a tolerance specified in AGMA class 6. The gear is then induction hardened, first by preheating at a lower frequency, say 10 KHz, then induction heating at a higher frequency, say 50 KHz, in order to obtain a desired hardness profile. The desired hardness profile includes the surface hardness of at least 50, preferably 60, on the Rockwell C scale and a core hardness not over Rockwell C 45, preferably from Rockwell 25 to Rockwell 40. This invention provides a low-cost manufacturing process which is especially suited for differential gears, such as pinion mate gears and side gears, and other non-automotive gears that do not have to carry a high torque load. This process eliminates costly steps of manufacturing and carburizing heat treatment.

Induction hardened forged gear and process for preparing same

Induction hardening of heat treated gear teeth which includes the steps of rough and finish cutting the gear teeth, or alternatively cutting the gear teeth to their final configuration utilizing a one cut method, carburizing the gear and in particular, the gear teeth, slow cooling, or alternatively drawing back the gear so the gear teeth are not hard, and induction hardening the gear teeth heating only the surface of the gear teeth. This results in improved strength for the gear teeth as a result of increased residual compressive stresses therein. Induction heating of only the surface of the gear teeth results in an relatively low case depth in the root of the gear teeth. Since the residual compressive stresses increase as the case depth decreases, the fatigue life of such a gear will be improved as compared to gears produced using known prior art methods which utilize the case depth from the carburizing process which results in a relatively deeper case and, therefore, lower residual compressive stresses in the gear teeth and a less than desirable fatigue life.

Induction hardening of heat treated gear teeth

An improved spline rack for use on a spline rack cutter is disclosed wherein the spline rack includes a plurality of teeth each having a top land surface that curves toward the inner tooth edge region, and the inner tooth edge region of each tooth includes a chamfer connecting the inner tooth edge region with the curved portion of the top land surface. In this manner, the exit radius of curvature of the inner top land surface may be maximized, while the chamfer prevents interference between the inner tooth edge region and the workpiece. A method of forming an improved spline rack is also disclosed.

Spline rack

A method and apparatus for machining a workpiece from a hardened unmachined part includes the use of non-rotating centers in a turning machine, on which the workpiece is mounted. The shape of the dead centers permits less force to be used in support of the workpiece for reducing friction between the rotating workpiece and non-rotating centers, while exerting a maximum amount of radial holding force to reduce runout in the machining operation. Lubrication can be supplied through the dead centers to further reduce friction and/or an anti-friction coating may be applied to the contacting surface of the centers for this purpose. Machining of the hardened part may be controlled by CNC equipment.

Method and apparatus for machining hardened parts apparatus for

A method for machining a part with gear teeth onto an unmachined part to form drive pinion gears is disclosed. A center bore is formed at one end of the part and receives a tool center to mount the part for machining. The center bore includes a plurality of lobes which are in point contact with the lathe center, allowing adjustment between the unmachined part and the lathe center. Drive apertures are formed radially outwardly of this center bore to receive drive pins from the machine tool. Most preferably the drive apertures are slots which provide clearance, facilitating the alignment of the drive pins in the drive apertures.

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Huntertown, IN, United States of America

James Steven Fisher