| 摘要 |
A method for making a hollow crank includes a three-direction forging step to forge a piece to have a recess in a first end of the prototype; a step of forming a hollow first end of the prototype by forcing the first end through a cone-shaped passage in a mold; a step of forming the first end of the prototype to have an angle relative to the second end of the prototype; a step of setting the first end of the prototype in a cold-forging mold to set the shape of the prototype.
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