Hollow shaft and method of producing the same

A method of producing a hollow shaft having first and second profilings provided for torque transmission at respective ends thereof, wherein a shaft section between the ends has a smaller diameter than at least one of the profilings, and the hollow shaft is assembled from first and second components joined via a torque-transmitting slip joint, said method comprising forming a hollow shaft section having at one end thereof a torque-transmitting profiling with a larger diameter than the shaft diameter and at the other end thereof an external torque-transmitting profile of said slip joint from a workpiece by:

• a) cutting a material blank from bar stock,
• b) subjecting the cut blank to a first cupping wherein a cup-like hollow region with a solid extension is formed by cold extrusion and wherein the cup region corresponds at least approximately to the inside diameter and the outside diameter of a torque-transmitting profile section,
• c) subjecting the blank to a second cupping, wherein the hollow region is lengthened from the extension by cold extrusion,
• d) perforating the bottom of the cup resulting from c),
• e) cold extruding the tube to commence formation of the hollow shaft body,
• f) reducing the diameter and wall thickness in a first reduction step and lengthening the hollow shaft section and forming a neck portion that is thicker than the outside hollow shaft diameter adjoining a region intended for forming the profiling using cold extrusion,
• g) starting from said neck portion, reducing the diameter and lengthening the hollow shaft section in a second reduction step using cold extrusion,
• h) final pressing the profile region in the form of external teeth by inserting a mandrel into the internal contour in the profile region with the same diameter, wherein an annular die surrounding the mandrel penetrates the end face of the end region and thereby displaces material into counterteeth of a die placed around a region intended to form the teeth, thereby forming an axial projection by cold extrusion,
• i) optionally and simultaneously with step h), forming the external profile of said slip joint in the section of the hollow shaft opposite the profile region by cold extrusion, and
• j) removing the projection by turning.

A method of producing a hollow shaft having first and second profilings provided for torque transmission at respective ends thereof, wherein a shaft section between the ends has a smaller diameter than at least one of the profilings, and the hollow shaft is assembled from first and second components joined via a torque-transmitting slip joint, said method comprising forming a sleeve having a torque-transmitting external profiling at one end thereof and an internal profile of a slip joint at the other end thereof from a workpiece by:

• a) cutting a material blank from bar stock to length,
• b) subjecting the cut blank to a cupping step and simultaneously forming the internal profile of the slip joint by cold extrusion,
• c) perforating the bottom of the cupped blank,
• d) turning the outside diameter of the workpiece,
• e) producing the external profiling by cold extrusion, by inserting a mandrel with a profile corresponding to the internal profile of the slip joint into said the cupped workpiece, and forcing an annular die surrounding the mandrel past the end face opposite the perforated bottom to displace material of the workpiece into counterteeth of a die placed around the region intended to form the profiling, whereby an axial projection is formed, and
• f) turning the sleeve height to finished dimensions and simultaneously removing the axial projection.

A method of producing a hollow shaft having first and second profilings provided for torque transmission at respective ends thereof, wherein a shaft section between the ends has a smaller diameter than at least one of the profilings, and the hollow shaft is assembled from first and second components joined via a torque-transmitting slip joint, said method comprising:

• a) turning a portion within the profile formed integrally with the shaft profile,
• b) forming a recess in the outer end region of the profile,
• c) forming a chamfer at the beginning of the internal contour in the region of the profile, and
• d) forming an undercut in the end region of the cylindrical internal contour in the region of the profile.