Sheet metal container making – Method – Assembling receptacle with closure
Patent
1997-12-04
1999-09-28
Coan, James F.
Sheet metal container making
Method
Assembling receptacle with closure
413 6, 413 27, B21D 5132
Patent
active
059576472
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to the forming of a double seam between an end wall of a can and a body of a can.
Wall ironed can bodies commonly have a bottom wall and an integral side wall upstanding from the periphery of the bottom wall to terminate in a shoulder, a neck of reduced diameter, and an outwardly directed flange. It is usual for the majority of the side wall to be much thinner than the bottom wall. An annulus of arcuate cross-section connects the neck to the flange, and a typical radius of this arcuate annulus is 0.040". Wall ironed can bodies are usually coated internally after forming by sprayed lacquer. Can ends fitted to these wall ironed can bodies are stamped from precoated sheet metal such as tinplate, electrochrome coated steel (TFS), or aluminium alloy.
The can industry is asked to provide a variety of features on the sidewall of the can, such as texturing or can sidewall shaping, which can result in the can having a reduced axial strength. Due to this reduced axial strength, there can be problems encountered during the seaming of the can end onto the can, which is typically carried out using an axial load of approximately 650N.
Accordingly there is provided a method of making a double seam joining a can body to a can end, the can body having a side wall terminating in an outwardly directed flange, said method comprising the steps of: other, can end to progressively form a double seam by a relative rolling motion, -450.degree., and
Alternatively, there is provided a method of joining a can body to a can end with a double seam, the method comprising the steps of: wall of the can body, other, can end to progressively form a double seam by a relative rolling motion, -45.degree., and the angle between the flange and the horizontal, assuming the can is standing upright. Typical conventional cans have a positive flange angle between 0 and 15.degree. (i.e. they are either horizontal or "point upwards" at an angle of up to 15.degree.). Cans with a negative flange angle (i.e. with a downwardly pointing flange) are known as having a "mushroom flange", and this is seen as being a flange defect produced by poor can making practices. U.S. Pat. No. 3,556,031 discloses a seaming technique which uses a downwardly directed can flange but this is a technique using a cam surface, rather than the double operation seaming roll technique which has become the industry's standard.
SUMMARY OF THE INVENTION
Applicants have discovered that when a can is formed having a flange with a negative flange angle in the range described, acceptable double seams can be formed using a much lower axial load during the seaming operation. This is a feature which is not suggested by U.S. Pat. No. 3556031, and has not previously been recognised with previously formed "mushroom" flanges. According to the present invention the load applied between the can end and the can body during seaming is typically in the range 200N-600N, conveniently 400N or less, and conceivably even 200N or less. This reduced axial load during seaming may allow shaped or patterned cans to be seamed which would otherwise risk collapsing during a conventional seaming process.
Conveniently the flange angle of the can flange is in the range -4.degree. to -42.5.degree., and preferably in the range -10.degree. to -40.degree.. The flange radius (which is a term of art in the can making industry meaning the length of the flange during its curvature outwardly from the neck of the can) is conveniently greater than 0.55 mm (0.0217") and preferably in the range 0.75 mm (0.030") to 1.15 mm (0.045").
The invention also extends to a can body having an outwardly directed flange at the peripheral edge of the side wall thereof, characterised in that the flange has a flange angle within the range 0 to -45.degree., a flange radius within the range 0.75 mm (0.030") to 1.15 mm (0.045"), and a flange fibre length (as hereinafter defined) within the range 3.22 mm (0.127") to 4 mm (0.157"). The flange fibre length is hereindefined as the length to the end
REFERENCES:
patent: 1827545 (1931-10-01), Schroeder
patent: 3556031 (1971-01-01), Frankenberg
patent: 4470738 (1984-09-01), Togo et al.
patent: 4606205 (1986-08-01), Segredo et al.
patent: 4777831 (1988-10-01), Masuda
patent: 5066184 (1991-11-01), Taura et al.
Carnaudmetalbox (Holdings) USA, Inc.
Coan James F.
LandOfFree
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