Metal deforming – With cleaning – descaling – or lubrication of work or product – Lubricating
Patent
1994-06-10
1995-10-24
Larson, Lowell A.
Metal deforming
With cleaning, descaling, or lubrication of work or product
Lubricating
72349, B21D 2228
Patent
active
054600243
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for drawing and ironing metallic or metalloplastic cans.
During the forming of metallic or metalloplastic cans, by drawing and redrawing or drawing and ironing, two kinds of difficulties are encountered.
The first one is that Al alloys containing Mg (5000 series according to the Aluminum Association designations) have a tendency to to gall to the forming tools particularly to drawning and ironing rings (or dies). It is practically impossible to form cans with bare metal; the solution consists either to make specific surface treatments (see FR-A-2 627 189) or to coat with a plastic matter on the external or internal surface.
The first solution is relatively complex and expensive; the second one presents another difficulty which is the roll-back defect, which is more important when the height (H) over diameter (D) ratio is high and/or the thickness of the lateral wall (e) is low.
The defect is produced when the drawn receptable is extracted on the mandrel rod by the extractor. It takes the form of concertina folds in the body of the receptable, or rolling back of its free edge, or in the most serious cases of longitudinal tears in the body of the receptable and rolling of the intermediate strips into "petal" shapes. It results from a hooping effect or adhesion on the body of the receptacle to the mandrel rod during the drawing operation.
The fault is still more pronounced in cases where the drawn cans are coated internally with an organic material such as plastics; this has a spring back effect which accentuates the hooping effect.
Attempts have been made to remedy this defect in various ways, but the results obtained are still inadequate and/or uncertain: means. However, this solution has the following limitations:
It does not allow one to obtain high rates of thickness reduction and hence limitation of the drawing ratio r (e.g. to a maximum value r=(E-e)/E.times.100=20 with e .ltoreq.0.15 mm for aluminium cans) and of the H/D value obtained.
As far as the die is concerned, improved lubrication gives a drawn external surface which is rough and dull in appearance rather than smooth and shiny, whereas the latter surface condition is most frequently required; steel one (modulus of elasticity 500 GPa instead of 200 GPa) ; during the drawing operation, and by removing the pressure before extracting the drawn can.
However this solution is mechanically complex, difficult to implement and expensive; through the mandrel rod; however the pressure is limited by the stability of the base and often proves to be inadequate for correct extraction.
SUMMARY OF THE INVENTION
Being aware of these difficulties, Applicants have sought to avoid the disadvantages described above.
A can drawing machine is essentially made up of a plurality of coaxial dies of decreasing diameters and a generally cylindrical axial mandrel rod. The mandrel rod successively pushes the blank though the dies, in which its side wall is made thinner and drawn (made longer); in present-day industrial machines the dies are generally three in number.
The apparatus according to the invention thus comprises a chamber which is located upstream of at least one of the drawing dies, in semi-impervious manner, and provided with a port for lubricant intake and a discharge port.
The essential feature of the invention is that in each chamber on the upstream side of the corresponding die (or ring), there is a antechamber formed by a long and narrow cylindro-conic annular space, near the external surface of the drawn can. This antechamber is externally limited by the die itself or by an inserted sleeve. It comprises an eventually annular cylindrical part, extending on the ring side, by a conical transition part. If lo is its total length and jo its thickness, one should preferably have:
The unexpected result is that, in the case of drawing and ironing a metalloplastic can with this apparatus placed on the last drawing die, the drawn can can easily by extracted from the mandrel rod. The equipment may b
REFERENCES:
patent: 3798943 (1974-03-01), Benteler et al.
patent: 4223544 (1980-09-01), Main
patent: 4881394 (1989-11-01), Jansen
Meneghin Rene
Trepied Louis
American National Can Company
Larson Lowell A.
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