Method and apparatus for producing untrimmed container bodies

Abstract

Exemplary embodiments of the invention relate to an apparatus and method for producing untrimmed container bodies from pre-cut metal blanks. The method involves cupping a metal blank by positioning the blank against an immovable draw punch comprising an annular body having an inner surface adapted to form a redraw die and an outer surface, and drawing a periphery of the blank over the outer surface of the draw punch with an encircling draw die to form a cup having an open end, a closed end and an interior. The cup is then inverted and redrawn by forcing a redraw punch into the closed end of the cup to draw the closed end through the redraw die until the cup is inverted to form an inverted cup with a closed end supported on the punch. The inverted cup while supported on the redraw punch is passed through one or more ironing rings to lengthen the inverted cup to form an untrimmed container body having a closed end. The closed end of the untrimmed container body is shaped by engaging the closed end of the untrimmed container body with one or more end shaping tools while supported on the redraw punch. The apparatus comprises tools, actuators and a solid support structure adapted to carry out the method. The metal blank may be pre-cut and supplied to the apparatus for shaping, or it may be cut from a metal sheet supplied to the equipment just as the shaping operations commence.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation-in-part of prior co-pending U.S. patent application Ser. No. 11 / 975,926 filed on Oct. 22, 2007 by applicants named herein. The entire contents of the aforesaid application are specifically incorporated herein by this reference.BACKGROUND OF THE INVENTION[0002]I. Field of the Invention[0003]This invention relates to the production of container bodies made of metal. More particularly, the invention relates to apparatus and methods for forming untrimmed beverage container (can) bodies, particularly such bodies made of aluminum and aluminum alloys. Untrimmed bodies of this kind are subsequently trimmed and provided with a container end closure to create a completed container.[0004]II. Background Art[0005]Beverage container bodies are generally produced in two forming steps carried out in different machines. The first step involves cutting a flat circular blank from a sheet of metal and creating a shallow cup...

AI Technical Summary

Benefits of technology

The patent describes an apparatus for making untrimmed container bodies from pre-cut metal blanks. The apparatus includes shaping tools and a support structure for the tools. The support structure is designed to resist flexing and play during the forming operations, which means that the apparatus is less likely to encounter flexing and play under the forces required for the forming operations. The apparatus also includes a holding device for the untrimmed container body, and a device for removing the container body from the apparatus. The use of pre-cut metal blanks instead of flat metal sheets reduces the distance between the leading end of the redraw punch and the operational end of the annular body of the combined draw punch and redraw die, which means that the supporting structure and the redraw punch can be made shorter, resulting in more regular container bodies. The apparatus also includes an annular draw holder and an annular redraw holder for gripping the blank and holding it in place during the shaping process.

Problems solved by technology

This produces a significant amount of metal waste in the form of a flat web with punched-out circular holes.

The metal waste is normally returned to the metal supplier for recycling, but this is an inefficient procedure because it involves transporting a certain percentage of metal first to the fabricator and then from the fabricator back to the metal supplier.

In circumstances where the metal fabricator and can body producer are located in different countries, some governments apply taxes or duties on both metal sheet imports and scrap metal exports, thus further reducing the economic benefit of supplying the metal in the form of continuous sheet.

In addition, the indicated two-step container-forming procedure is not fully efficient because an intermediate product (a shaped cup) is created in one kind of apparatus and is then transferred to a second kind of apparatus (a redraw and ironing machine) for the second stage of the process.

This can result in significant wastage of both time, factory floor space and invested capital.

Moreover, the redraw and ironing operations often cannot produce container bodies of consistent thickness and unwrinkled appearance because there is often an unwanted degree of play between the punch, die and ironing elements that creates non-uniformity in production.

Consequently, a degree of flexing of the punch may take place that results in play at the operational end.

Attempts have been made in the past to overcome some or all of these disadvantages, but problems still persist.

Additionally, the apparatus is arranged such that the various moving components may encounter a high degree of play, therefore resulting in a lack of uniformity in the can bodies thus produced, or even a degree of metal wrinkling or seaming during the drawing and ironing procedures.

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