| 摘要 |
To provide a method and an apparatus capable of manufacturing a pillow ball for automobile by a multistage forming machine, a method and an apparatus for manufacturing a pillow ball for automobile without buckling by multistage pressure forming, and a pillow ball of which metal has excellent mechanical properties such as tensile strength and fatigue strength. The method for manufacturing a pillow ball comprises a pre-process of obtaining a cylindrical work(40) by cutting a raw material for pillow ball manufacture at a cutting knife block of a multistage forming machine; a first process of obtaining a groove formed preformed work(42) by transferring the cylindrical work to a processed work placement part of die of first stage so that the cylindrical work is supported by a die side supporting rod in a placement space and moving a punch such that the punch presses both cross sections of the cylindrical work; a second process of obtaining a pipe type work(44) formed in such a shape that a central portion of the work is closed by transferring the preformed work to a processed work placement part of die of second stage so that the preformed work is placed in a placement space and simultaneously pressing chamfered grooves(64,66) on both surfaces of the preformed work in both directions by die pin and punch pin; a third process of obtaining a pipe type work(46) by transferring the pipe type work(44) to a processed work placement part of die of third stage so that the pipe type work is placed in a placement space and perforating a closed central portion of the pipe type work by punch and die pin; a fourth process of obtaining a basic spherical surface formed pipe type work(48) by transferring the pipe type work(46) to a processed work placement part of die of fourth stage so that the pipe type work is placed in a placement space and pressing both ends of the pipe type work by punch and die, thereby basically forming a spherical surface of a body part; and a fifth process of obtaining a pillow ball finished product(50) by transferring the basic spherical surface formed pipe type work to a processed work placement part of die of fifth stage so that the basic spherical surface formed pipe type work is placed in a placement space and pressing both ends of the basic spherical surface formed pipe type work by punch pin and die pin, thereby forming the basic spherical surface of the body part into a completed spherical surface.
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