Metal deforming – By use of tool acting during relative rotation between tool... – During rotation of work
Patent
1984-08-29
1986-08-19
Larson, Lowell A.
Metal deforming
By use of tool acting during relative rotation between tool...
During rotation of work
72110, B21D 1906
Patent
active
046062076
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national application corresponding to international application PCT/GB No. 83/00355, filed Dec. 29, 1983.
This invention relates to methods of, and apparatus for, forming a neck about an open end of a hollow body having its other end closed and comprising a thin cylindrical sidewall, an end portion of which has a terminal edge defining the open end; the invention further relates to such a hollow body when provided with a neck about its open end by a said method.
The hollow body in question is typically a can body made of a metal which will normally be steel (usually though not necessarily, having a coating of metallic tin) or aluminium. Such a can body is particularly likely to be of the unitary kind formed by drawing, with subsequent redrawing or wall ironing or both, and this Description is written with particular reference to unitary can bodies.
It is however to be clearly understood that the invention is applicable to any hollow body as defined above, and not exclusively to can bodies. Furthermore, the hollow body may not be of metal, but may for example be of a plastics material of a kind to which the method may successfully be applied.
The word "thin", as used herein in relation to the sidewall of the hollow body, is not to be taken as implying any particular thickness or range of thicknesses. In respect of the method of the present invention, however, it implies that the sidewall of the hollow body is too thin to be readily worked, so as to form a neck to its final size in a single operation without the danger of uncontrolled wrinkling or other undesired distortion, by methods currently in use for forming terminal necks on metal can bodies. Such methods involve also the forming, either at the same time as the formation of the neck or subsequently, of a terminal flange which is used to form part of the peripheral end seam by which a can end is later secured over the open end of the can body. The methods referred to are die necking, and methods of simultaneously forming the neck and terminal flange by rolling or spinning.
The present Applicants' United Kingdom Patent No. 1534716 describes a typical method and apparatus for forming a terminal neck with radical flange on a can body, whereby the latter is held in axial compression whilst a chuck is engaged axially with its open end. External neck rolling tools are advanced radially into engagement with the sidewall of the can body whilst a control or limit ring is engaged axially with the terminal end of the can body, to apply the necessary axial compressive force. The limit ring is moved axially so as to remain in engagement with the terminal end, whilst the can body is itself moved axially during the neck-forming operation. The can is not supported internally in any way, so that the neck is formed in free space, its shape being determined by appropriately controlling the relative movements of the can body, the limit ring and the external neck rolling tools. This process wil be referred to herein as "spin necking and flanging".
Present methods of forming necks and associated terminal flanges on metal can bodies, where the reduction in diameter, as between the main part of the sidewall and the neck, is greater than a certain amount, involve several stages of working. For example, a single die necking operation will allow only a relatively small reduction in diameter (typically no greater than 4.3% of the material if the can body is tinplate), if localised buckling of the open end or collapse of the main part of the sidewall are to be avoided. Thus if a greater overall reduction in diameter is called for when die necking is used, this must be effected in two or more separate operations. On the other hand, whilst the use of the spin necking and flanging process can reduce the number of separate operations required for a given reduction in diameter, it does not permit the formation of a flange having an external diameter smaller than the original diameter of the adjacent portion of the sidewall.
REFERENCES:
patent: 3754424 (1973-08-01), Costanzo
patent: 3765351 (1973-10-01), Kubacki et al.
patent: 3812696 (1974-05-01), Kneusel et al.
patent: 4058998 (1977-11-01), Franek et al.
patent: 4064726 (1977-12-01), Hinze
patent: 4512172 (1985-04-01), Abbott et al.
Larson Lowell A.
Metal Box Public Limited Company
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