METHOD FOR FORMING BOSS PART OF ROTARY BODY

Japanese Patent JP2769775

B2

PURPOSE: To obtain enough thickness and provide projecting boss parts on both sides by forming a cap like part on a raw material, pressing of the outer circumference of this cap like parts into an annular shape in a direction opposite to the projecting direction of the cap like parts to form a fold back shape, then punching the top part of the cap like parts to form the inner circumferential surface thereof as the inner surface of the boss part.
CONSTITUTION: By using a first cap like part forming die, the central part of a raw material 1 of thin steel sheet blanked and formed in a circular disk is protruded and formed into a cap like shape. By using an upper and lower recessed part forming dies, the outer circumference of the cap like part is formed into an annular recessed part 5 in a direction opposite to its projecting direction by supporting its inner side of the cap like part with a second cap like part forming die of small diameter. Next, the annular recessed part 5 is folded back and a fold back part 9 is roughly formed. At this time, upper and lower pressing dies 10a, 10b press the circumference of the raw material, and fold back part roughly forming dies 11a, 11b form the central part roughly. Further, after this bent back part 9 is finished by closely sticking the fold back surfaces, the top part of the cap like part is punched, the inner diameter of the fold back part 9 is finished.

Shigeaki Yamanaka

JP29521293A

June 25, 1998

November 25, 1993

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Kubota Iron Works Co., Ltd.

B21D28/28; B21J5/08; B21K1/40; (IPC1-7): B21K1/40; B21D28/28; B21J5/08

JP49243A
JP4258337A
JP2160138A
JP3204123A
JP3180219A
JP5718967B2

Masaaki Yonehara (2 others)

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