Method for forming closed-bottom cylindrical container

Abstract

When an outer punch (23) is lowered while the container bottom section (21a) of a closed-bottom cylindrical container (21) is gripped between an inner punch (22) and a die (25), a container opening end (21d) enters the inside of the step-shaped groove section (23c) of the outer punch (23), and the container opening end (21d) is restrained in the direction perpendicular to a center axis (20) by the step-shaped groove section (23c) and a die sidewall section (25b). When the outer punch (23) is further lowered, a punch shoulder section (23f) comes into contact with a container shoulder section (21c), and then the second press surface section (23e) of the step-shaped groove section (23c) comes into contact with the container opening end (21d) to cause the material of the thickened wall portion of the container bottom section (21a) flow into a space at a die corner section (25d), thereby increasing the wall thickness of the container shoulder section (21c) and forming the container shoulder section (21c) into a right-angled shape.

Description

technical field [0001] The present invention relates to a forming method of thickening the container shoulder of a cylindrical container with a bottom and forming it into a right-angle shape, and forming the side wall of the container into a linear shape. Background technique [0002] For example, in the case of components that rotate and transmit torque such as brake drums and hubs used in automatic transmissions of automobiles, it is required to form the shoulder connecting the bottom surface and the side wall perpendicular to the bottom surface at a right angle. shape and have a sufficient wall thickness to withstand only the transmitted torque. In addition, the side wall portion is also required to have a sufficient thickness. [0003] figure 1 It is a figure which shows the state of the mold and the bottomed cylindrical container 11 before forming in the conventional forming method. In the conventional forming method, first, the container bottom 11a of the bottomed c...

AI Technical Summary

Problems solved by technology

In this case, if figure 2 As shown, there is the following problem: on the inner side of the container shoulder 11c, there is a wrinkle-shaped defect (referred to as a fold-in defect in this application) 11d formed by folding and overlapping the surface.

However, in this forming method, it is necessary to move the pressing punch and the fixed punch in the first to third steps, and three steps are required in a normal double-action press machine.

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