A method of manufacturing a brake disk made of gray cast iron is disclosed. The method includes casting a disk body using gray cast iron containing 3.1 wt % to 3.7 wt % of C; machining a surface of the cast disk body; nitriding the disk body by exposing the machined surface to a temperature in the range of 540 C. to 580 C. for 50 min to 70 min, and coating the nitrided disk body.

In a tripod type constant velocity universal joint 1 of a double roller type, R/PCD?0.0850 and t/PCD?0.145, where PCD is a pitch circle diameter of a roller guide surface 6 of an outer joint member 2. R is a radius of curvature at an intermediate portion between a body portion 31 and a leg shaft 32 of a tripod member 3, and t is a minimum distance from a large-diameter portion 34a of a spline 34 of the tripod member 3 to an intermediate portion 33.

The invention provides a coating film having excellent adhesion, even without a chemical conversion film treatment being carried out as an undercoat treatment, and a metal automotive part having the coating film. A powder is deposited by powder-coating onto the surface of a metal automotive part that has been quenched after forging, and tempering of the metal automotive part and bake-hardening of the deposited powder are carried out simultaneously, thereby forming a skin film on the surface of the metal automotive part. The surface of the metal automotive part before the powder is powder-coated thereon is a work-hardened basis material surface that has been not subjected to a chemical conversion filming treatment.

A method of manufacturing a brake disk made of gray cast iron is disclosed. The method includes casting a disk body using gray cast iron containing 3.1 wt % to 3.7 wt % of C; machining a surface of the cast disk body; nitriding the disk body by exposing the machined surface to a temperature in the range of 540 C. to 580 C. for 50 min to 70 min, and coating the nitrided disk body.

A universal joint configured to transfer rotational movement from a first shaft to a second shaft at an angle and method of manufacturing the same.

A method of manufacturing a brake disk made of gray cast iron is disclosed. The method includes casting a disk body using gray cast iron containing 3.1 wt % to 3.7 wt % of C; machining a surface of the cast disk body; nitriding the disk body by exposing the machined surface to a temperature in the range of 540 C. to 580 C. for 50 min to 70 min, and coating the nitrided disk body.

A brake disc of the present invention is a brake disc that stops the rotation of an axle when a brake pad is pressed on a surface of the brake disc, including a disc main body that is attached to a rotary body integrally rotating with the axle; and a plurality of build-up layers laminated on a surface of the disc main body, in which the build-up layers are laminated on the surface of the disc main body by means of laser metal deposition welding.

A tripod type constant velocity universal joint includes an outer joint member having track grooves formed at trisected positions thereon in a circumferential direction to extend in an axial direction of the tripod type constant velocity universal joint, a tripod member having a trunnion barrel spline-fitted to a shaft and trunnion journals radially projecting from trisected positions on the trunnion barrel in the circumferential direction, and rollers fitted to the trunnion journals, respectively, that are received in the track grooves, respectively. Each of the rollers is guided by roller guide surfaces formed on both side walls of each of the track grooves. The tripod member has quench-hardened layers formed by carburizing, quenching, and tempering, and a depth of a quench-hardened layer of a radially outer surface of the trunnion journal is larger than a depth of a quench-hardened layer of a root portion of the trunnion journal.

A tripod type constant velocity universal joint includes an outer joint member that includes track grooves, a tripod member that includes three leg shafts protruding in a radial direction, a roller that is inserted into the track groove, and an inner ring that is fitted onto the leg shaft, and rotatably supports the roller. A hardened layer is formed on a surface of each leg shaft by carburizing, hardening, and tempering. The tripod member is formed a steel material having a carbon content of 0.23% to 0.44%. An effective hardened layer depth of the hardened layer by using, as a Ts torque, 0.3 times a minimum static torsional torque at which a shaft coupled to the tripod member causes torsional fracture and 600HV as limit hardness is equal to or greater than a maximum shear stress depth Z when the Ts torque is applied.

A method for manufacturing at least one synchronizing ring includes providing a rough-turned blank made from a hardenable material that is in a not-hardened state and laser-cutting the rough-turned blank to form the at least one synchronizing ring, the laser cutting being performed with an energy chosen to be sufficient to selectively harden at least a portion of the material in a region along which the laser cutting occurs.