Rocker arm
A rocker arm comprises an arm body, a shaft and a roller. The arm body formed substantially in a U-shape in section by effecting drawing on a metal plate, includes a connection wall connecting a pair of side walls, an aperture formed through the connection wall, and through-holes at positions where the pair of side walls are aligned with each other. A peripheral edge of the aperture is so formed as to be finished by inserting a first finishing die into the aperture from between the pair of side walls. The shaft is fitted in the pair of through-holes and extended between the pair of side walls. The roller is rotatably supported on the shaft.
1. Process for manufacturing a rocker arm body which includes a pair of side walls, a connection wall connecting said pair of side walls, comprising the steps of:
press-forming a rocker arm body blank of a U-shape in section which includes a pair of side walls and a connection wall connecting said pair of side walls by drawing a metal plate blank;
forming through-holes in positions where said pair of side walls are aligned with each other;
punching said connection wall of said rocker arm body blank to form an aperture; and
inserting, while supporting said rocker arm body blank in an outer die, a first finishing die into said aperture from between said pair of side walls so that an inner peripheral edge of said aperture may be bent up by being plastically deformed or sheared, thereby finishing a peripheral edge of said aperture.
2. Process for manufacturing a rocker arm body according to claim 1 , further comprising a step of:
pressing and finishing a second finishing die against external end surfaces of said pair of side walls configuring a rocker arm portion surrounding said aperture to form and finish said external end surfaces.
3. Process for manufacturing a rocker arm body according to claim 1 , wherein the peripheral edge of the aperture is flush with internal surfaces of the pair of side walls.
4. Process for manufacturing a rocker arm which includes an arm body which is formed of metal plate and includes a pair of side walls, a connection wall connecting said pair of side walls, an aperture formed through said connection wall, and through-holes in positions where said pair of side walls are aligned with each other, a shaft fitted in said pair of through-holes and extended between said pair of side walls, and a roller rotatably supported on said shaft, said roller being exposed partially through said aperture to be in contact with a cam robe, said process comprising the steps of:
press-forming a rocker arm body blank of a U-shape in section which includes a pair of side walls and a connection wall connecting said pair of side walls by drawing a metal plate blank;
forming through-holes through said side walls in positions where said pair of side walls are aligned with each other;
punching said connection wall of said rocker arm body blank to form the aperture; and
inserting, while supporting said rocker arm body blank in an outer die, a first finishing die into said aperture from between said pair of side walls so that an inner peripheral edge of said aperture may be bent up by being plastically deformed or sheared, thereby finishing a peripheral edge of said aperture.
5. Process for manufacturing a rocker arm according to claim 4 , further comprising a step of:
pressing a second finishing die against external end surfaces of said pair of side walls configuring a rocker arm portion surrounding said aperture to form and finish said external end surfaces.
6. Process for manufacturing a rocker arm body according to claim 4 , wherein the peripheral edge of the aperture is flush with internal surfaces of the pair of side walls.