| 摘要 |
A manufacturing method of a sub frame cup is provided to improve productivity and reduce manufacturing costs by reducing waste of a plate workpiece and reducing the number of manufacturing processes, extend the service life of the sub frame cup by enhancing formability and durability of a completed product, and reduce the production of defective products substantially. A manufacturing method of a sub frame cup comprises: an upper cup processing step of determining a central line of the plate workpiece along the length direction of a plate workpiece, and processing the upper cup from the plate workpiece such that an upper cup(52) with a circular cross-sectional shape is positioned at a position that is eccentric to the central line; a first artifact manufacturing step of manufacturing a first artifact(55) with the upper cup and a flat face part(54) by determining a horizontal extension line in which a center(C1) of the upper cup is horizontally extended to a direction at which the central line is positioned, determining, as a central point(P1), a point which is vertically extended from the horizontal extension line and encountered with the central line, and cutting the plate workpiece along a predetermined radius(r1) about the central point such that the upper cup is included within the radius; a second artifact manufacturing step of manufacturing a second artifact(58) with the upper cup, a lower cup(56), and a lower inclined face(57) by determining, on the flat face part, a processing line(L4) having a radius(r2) from the center of the upper cup, the radius being larger than an outer peripheral surface(52a) of the upper cup and smaller than an outer peripheral surface(54a) of the flat face part, and bending the flat face part that is not included within the radius(r2) relative to the processing line in the vertical downward direction opposite to the projecting direction of the upper cup; and a finished product manufacturing step of manufacturing a sub frame cup by processing a through hole in a top face of the upper cup in the second artifact with the upper cup, the lower cup, and the lower inclined face.
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