Metal deforming – Process – Deforming sheet metal
Reexamination Certificate
2001-03-13
2002-08-13
Tolan, Ed (Department: 3725)
Metal deforming
Process
Deforming sheet metal
C206S531000
Reexamination Certificate
active
06430984
ABSTRACT:
The present invention 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 such, for example base parts for blister packs, also known as push-through packs, or other packaging containers e.g. by deep drawing, stretch-drawing or thermoforming. The shaped packaging may be manufactured from thermoplastics or from composites or laminates such as e.g. aluminium foils laminated with plastic films or layers of thermoplastics laminated by means of extrusion.
If the shaped-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 from 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 tool 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.
The object of the present invention is to provide a process which enables shaped packaging, or shaped parts free of folds, to be made from 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 from 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 independent of each other, be divided into two or more strokes of the stamping tool using the same or different tools.
In the present invention the various stamping tools are advantageously employed one after the other and, via pre-forming, each stamping tool is lowered—in a series of steps down maximum depth—into the die opening by the same amount or further than the preceding tool. The metal-plastic laminate springs back, therefore at least the last forming step must exceed the full, i.e. 100% desired depth of deformation.
Usefully, the stamping tools with low-friction forming surface employed in the first step are cylindrical, blunted cone, blunted pyramid or barrel shaped. The stamping tools employed for the second step have the shape of a cone, pyramid, blunted cone, blunted pyramid, segment of a sphere or cap. The stamping tools for the first step feature in particular vertical or steep side walls, and the edges or periphery at the bottom of the tool has a small radius. The stamping tool for the second step with a low-friction forming surface, may be vertical or exhibit sloping side walls, and the transition to the bottom of the stamp may be round or roundish in shape. In the present process the stamping tool or tools, in particular the first tools for the first shaping step, may exhibit between the base of the stamping tool and its side wall an edge radius R of e.g. 0.3 mm to 1.5 mm, preferably 0.5 mm to 1.2 mm. It has also been found useful to vary the geometry of the shape-forming surface of the successive tools. A favourable version in this respect is to gradually increase the value of the edge radius R between the stamping tool base and its side wall on proceeding from the first to the second stamping tool i.e. to round the edges more. Instead of an edge radius R one may introduce in several steps a transition involving conical or blunted cone shaped tools.
It has been found particularly advantageous for a first forming step to employ a first stamping tool having an edge radius R between the tool base and tool side wall of 0.1 mm to 5.0 mm, preferably 0.5 mm to 5.0 mm and a second forming tool for the second forming step having a multi-step conical or blunted cone transition from stamping tool side wall to stamping tool base.
The process according to the invention may be performed e.g. using a die and retaining tool and two or more stamping tool
Oster Heinz
Zeiter Patrik
Alcan Technology & Management Ltd.
Bachman & LaPointe P.C.
Tolan Ed
LandOfFree
Process for manufacturing shaped packaging does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for manufacturing shaped packaging, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for manufacturing shaped packaging will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2912525