Metal deforming – By use of closed-die and coacting work-forcer – Forcing work into or within closed die; e.g. – forging
Reexamination Certificate
2000-03-08
2001-05-29
Larson, Lowell A. (Department: 3725)
Metal deforming
By use of closed-die and coacting work-forcer
Forcing work into or within closed die; e.g., forging
C248S363000
Reexamination Certificate
active
06237388
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The invention relates to container body forming presses for stamping metal can bodies from a strip of sheet metal in a succession of work stations in the press. More particularly, the invention relates to a transfer apparatus mounted in a fixed position on the base of the press between work stations for receiving and maintaining container bodies in a fixed position between work stations as the press is performing an operation on the adjacent can bodies at the work stations.
2. Background Information
It is well known in the container forming art to form two piece containers, that is, containers in which the walls and bottom of the container are a one piece member and the top end closure is a separate piece by stamping a plurality of blanks in a single or double action press from a strip of sheet metal and then subsequently drawing and redrawing the desired can body configuration into the blank in a series of work stations in the press.
These presses use multiple stage dies, that is, a single downward stroke of the press may simultaneously blank a plurality of disks from the sheet metal while at another station will draw the previously cut blank into a first stage can body while at still another work station in of the press the drawn can body will be redrawn into a final configuration or provide for a stepped shoulder or profile bottom thereto, with another station then trimming the annular outer flange of the can body to form the final container configuration. In these multiple station presses, a blank or dead space is generally provided between the work stations so that as the can body advances through the press it will rest in a dead space during each successive stroke while the press is performing a forming operation on the adjacent can bodies. Various mechanisms have been devised for sequentially moving the can bodies through the various stages of forming, that is, between the blank station to the redraw station to the shoulder and profile forming station, and then to the trimming station.
The prior art apparatus provided at the dead spaces between work stations usually will maintain the partially formed can body in position by applying a vacuum to the bottom of the body as it rests upon a transfer pad mounted in the dead space. This vacuum retention has proved satisfactory for prior art container bodies, especially those having a round bottom since the orientation of the body at the dead space always results in a similar shape bottom for gripping by the vacuum. However, more recently, various configured containers are being formed from the sheet metal other than a round container, one such example being a generally rectangular or elongated oval shaped container used for the storage of canned meat products such as sold under the trademark SPAM® and TREET®. The secure retention of these elongated can bodies on the transfer pads becomes more difficult due to the formation of a raised rib generally along only part of the can bottom which raises the majority of the can bottom wall off of the surface of the transfer pad making it extremely difficult for the suction of the vacuum to adequately hold the can against the pad surface due to the constant incoming of air through openings formed by the non continuous peripheral ribs or projections on the container bottom. The proper retention of the container bodies on the transfer pads becomes increasingly important and more difficult to satisfactorily achieve with the non circular shaped container bodies due to the ever increasing speed of the press and resulting transfer of the container bodies between the various work stations.
Therefore, the need exists for an improved transfer pad located at the transfer or dead areas of a multiple station press for securely gripping and positioning non circular container bodies thereon.
SUMMARY OF THE INVENTION
Objectives of the invention include providing an improved apparatus and method for properly positioning and retaining non circular container bodies in the dead spaces of a multiple station press between adjacent work stations without materially modifying the operation of the press or the previously used transfer pad configuration and mounting arrangement.
Another objective of the invention includes providing such a method and apparatus in which a transfer pad includes a generally flat planar elongated surface located between a pair of guide rails which rails have converging tapers to facilitate the entrance of the container bodies into the transfer pad, and in which a plurality of air holes extend along each of the guide rails closely adjacent thereto for aligning with the raised edges or ribs formed on the contoured bottom of the container body for firmly holding the container body to the transfer pad by a vacuum impressed thereon.
A still further objective of the invention is to provide such a method and apparatus which enables the improved transfer pad to be mounted by convenient mounting bolts at the same location and area as existing draw pad thereby requiring very little modifications to the existing press.
Another objective of the invention is to provide such an apparatus which achieves the stated objectives in a relatively simple, inexpensive, yet efficient manner.
These objectives and advantages are obtained by the improved apparatus of the present invention, the general nature of which may be stated as including an apparatus for assisting in transferring a container body between stations in a press which forms said body from sheet metal, said apparatus including a pad having an upper surface; means for mounting said pad in a fixed position on a base of said press; a pair of substantially parallel guide rails extending outwardly from the upper surface forming a guide surface therebetween; a vacuum manifold formed within the pad adapted to be connected to a vacuum source; a plurality of air holes formed in the pad and extending between the manifold and guide surface and located closely adjacent the rails for applying a vacuum against a bottom edge of the container body to maintain said body in position on the pad as said body is being transferred between stations in the press.
REFERENCES:
patent: 3902347 (1975-09-01), Ridgway et al.
patent: 5483876 (1996-01-01), Davis et al.
patent: 5626048 (1997-05-01), McClung
patent: 5823041 (1998-10-01), McClung
McClung James A.
Rubalcava Manuel P.
Can Industry Products, Inc.
Larson Lowell A.
Sand & Sebolt
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