Patent ID: 11859675
Assignee: MAZDA MOTOR CORPORATION
Field: Mechanical elements (Mechanical engineering)
Classification: CPC F | IPC F

Claim 4:
5. A method of forming a friction engagement device of an automatic transmission provided with a cylindrical drum part supporting an annular friction plate, the friction plate being provided in an outer circumferential side surface with a tooth part projecting radially outward, and the drum part including a cylindrical body including a spline part having serrations extending in an axial direction of the drum part and depressed radially outward so as to fit onto the tooth part of the friction plate, in an inner circumferential side surface; a vertical wall part provided at an end side of the cylindrical body, and extending radially inward; and a corner part provided between the cylindrical body and the vertical wall part, wherein a drum recess is formed inside the corner part, the drum recess being connected to the serration of the spline part, and being depressed toward an end side of the drum part in the axial direction, the method comprising:
die-casting the drum part, outside the corner part, to form a press-out part that projects outside, at a position corresponding to the drum recess; and
cutting the press-out part of the corner part of the drum part that is die-cast, to cut the drum part so that a cut part connected to the drum recess is formed in a circumferential direction of the drum part,
wherein the drum recess is opened to the outside by the cut part after the cutting to form an oil gallery.