Metal deforming – By use of closed-die and coacting work-forcer – Cup or shell drawing
Reexamination Certificate
1999-08-23
2001-08-07
Tolan, Ed (Department: 3725)
Metal deforming
By use of closed-die and coacting work-forcer
Cup or shell drawing
C072S350000, C072S379400, C072S404000, C072S472000, C425S398000
Reexamination Certificate
active
06269671
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention in relates to a process for manufacturing cold-formed shaped packaging from a metal plastic-laminate in which the laminate is held between a retaining tool and a die exhibiting at least one opening, and a stamping tool is driven into the die opening causing the laminate to be formed into shaped packaging with one or more recesses, the die and the retaining tool each exhibit a facing edge region, the die features within the edge region a shoulder region that surrounds the die opening or openings and the surface of the shoulder region lies lower than the edge region of the die. The present invention relates also to a device for performing the process of cold forming a metal-plastic laminate into shaped packaging, and relates also to cold formed packaging.
It is known to manufacture shaped packaging, for example base parts for blister packs, also known as push-trough packs, or other packaging containers e.g. by deep drawing, stretch-drawing or thermoforming. The shaped packaging may be manufactured from thermoplastics or form composites or laminates such as e.g. aluminum foils laminated with plastic films or layers of thermoplastics laminated by means of extrusion.
If the shape-packaging, made by shape-forming, is made from laminates containing metal foils, then shaping tools comprising a stamping tool, a die and a retaining tool may be employed for this purpose. During deformation the laminate is clamped securely between the die and the retaining tool, then the stamping tool moved towards the laminate. As it is lowered, the stamping tool penetrates deeper into the openings in the die thereby deforming the laminate. The flat laminate is converted into a shaped part exhibiting one or more recesses which are surrounded by shoulders corresponding to the original flat plane of the laminate. Only that part of the laminate in the region of the die opening can flow or be stretched to form a shaped part. In order that the laminate, especially laminates containing metal foil, can be deformed without creating cracks and pores, adequate lateral distance must be maintained between the stamping tool and the die opening. Cold forming a laminate containing a metal foil by this process enables recesses of only small side wall height to be achieved. This results in poor drawing ratios i.e. shallow recesses of large diameter and, therefore, forms of packaging which are too large in relation to the contents.
One possibility for obtaining more laminate for deformation purposes in order to achieve larger wall heights, may be to reduce the retaining force and to employ deep drawing methods. However, as folds would form in the edge or shoulder regions, this type of technology may not be used e.g. for making blister packs form laminates containing metal foil. The edge region and, if desired, the shoulder region of shaped forms of packaging is normally employed for sealing the lid into place. If there are folds present there, then the edge and the shoulders could not be sealed.
The European patent application EP 0 779 143 A1 describes a process for manufacturing such shaped packaging in which a metal-plastic laminate is held securely between a retaining tool and a die featuring one or more openings while two or more stamping tools drive the laminate into the die openings, thereby forming the laminate into shaped packaging with recesses. The process described there consists of two steps. In the first step use is made of a stamping tool that exhibits a high degree of friction in contact with the surfaces effecting the shaping. This causes the laminate to be pre-formed in one or more sub-steps. In a second step a second stamping tools is employed for further shape forming This stamping tool exhibits a lower degree of friction on the surfaces effecting the shape forming. Using this tool the laminate is shape-formed into its final shape in a series of sub-steps.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a process which enables shaped packaging, or shaped parts free of folds, to be made form metal-containing laminates by means of cold forming whereby the degree of forming and size of wall height are an improvement over the state-of-the-art.
That objective is achieved by way of the invention in that a first stamping tool or first stamping tools with a low-friction forming surface pre-form the metal-plastic laminate in a first step up to 100% of the final depth of the recess and, subsequently in a second step, using the first stamping tool or second stamping tool or tools of low-friction forming surface, the pre-formed metal-plastic laminate is shaped up to at least 100% of the final depth of the recesses.
The low degree of friction may be expressed by the dimensionless numbers according to the method 311A in BS 2782. The friction of the stamping tool with respect to the forming surface of the stamping tool is preferably 0.05 to 2.1 e.g. the first or the second and the second tool or second tools for the first and second shaping steps exhibit, at least on the shape-forming surface, different degrees of friction in the region concerned, or the stamping tools exhibit the same friction values.
The first stamping tool or tools may have different geometries form the second stamping tool or tools.
In a preferred version of the invention the first stamping tool or tools is/are driven in a first step down to 90%, usefully to 70% and advantageously to 50% of the final depth of the recesses, and subsequently in a second step the same first stamping tool or tools or a second stamping tool or tools is/are driven down to 100-115%, advantageously to 103-110% of the final depth of the recesses.
The first step, as with the second step, may be independent of each other or, be divided into two or more strokes of the stamping tool suing the same or different tools.
REFERENCES:
patent: 4354370 (1982-10-01), Ullman, Jr.
patent: 4928512 (1990-05-01), Rooney et al.
patent: 5664454 (1997-09-01), Zeiter et al.
patent: 5879612 (1999-03-01), Zeiter et al.
patent: 6055794 (2000-05-01), Breitler
patent: 6098829 (2000-08-01), McHenry et al.
patent: 6135755 (2000-10-01), Zeiter et al.
Oster Heinz
Zeiter Patrik
Alusuisse Technology & Management Ltd.
Bachman & LaPointe P.C.
Tolan Ed
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