Shell press and method for forming a shell

Abstract

An apparatus and method for forming a shell with a central panel and a chuck wall is provided. The apparatus and method employ the use of a biasing member to selectively bias and control movement of the inner pressure sleeve and a die core having an outer diameter equal to or greater than the outer diameter of the punch core. The apparatus and method can also be employed in a single action press or a double action press.

Description

FIELD OF THE INVENTION [0001] The invention generally relates to an apparatus and method for forming container end panels, commonly called shells, from a sheet of blanked material. More particularly, the invention relates to a press and method for forming the shell with the press having a biasing member that selectively biases and controls movement of the inner pressure sleeve and a die core having an outer diameter equal to or greater than the outer diameter of the punch core. BACKGROUND OF THE INVENTION [0002] The forming of can ends or shells for can bodies, namely aluminum or steel cans, is well-known in the art. Shells typically have a central panel connected to an inner panel wall which is connected to a countersink. The countersink is usually connected to a chuck wall of the shell which is connected to a peripheral curl that is structured to be seamed onto a can body. [0003] A representative patent disclosing shell forming is Bulso U.S. Pat. No. 4,716,755. As is typically see...

AI Technical Summary

Benefits of technology

The invention provides an apparatus and method for forming a shell that avoids excessive heat generation and strain hardening of the chuck wall. The apparatus includes a central panel and a chuck wall with an inner pressure sleeve, an outer pressure sleeve, a punch shell, a die core, a die core ring, a pressure pad, and a blank cutedge. The method involves moving material between a first die set and a second die set, blanking the material to form a blank, and selectively controlling movement of the inner pressure sleeve to avoid excessive strain hardening of the chuck wall. The technical effects include improved control and precision in forming the shell and avoidance of excessive strain hardening of the chuck wall.

Problems solved by technology

These approaches are not without certain limitations though.

The inner pressure sleeve mounted around a punch core, supported on a column of gas or supported on a piston can lead to the inner pressure sleeve heating up excessively in the shell forming process due to the loads that are applied to the inner pressure sleeve from formation of the chuck wall area of the shell being formed.

Excess heat generation in the inner pressure sleeve is not desirable in shell forming since the inner pressure sleeve can undergo thermal expansion and cause the press to form shells that do not meet the tolerances required by a can maker.

Also, the inner pressure sleeve mounted around a punch core, supported on a column of gas or supported on a piston can cause excessive strain hardening to occur in the chuck wall area of the shell being formed.

Excess strain hardening of the chuck wall is not desirable in shell forming since the final converted can end could crack or deform once the can end is seamed onto a can body containing product that is under pressure.

This approach is not without certain limitations though.

Hubball's approach does not provide the portion adjacent to the surface of the die core with the control, precision and stability one would obtain by having the portion adjacent to the surface of the die core in contact with the die core ring located around the die core.

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