Swiss Aluminium Ltd.

Zdenek Maly

Erich Hofling

Karl Mack

Prior to coating with lacquer or adhesive, or laminating with plastic, strips or foils of aluminum or aluminum alloys are pretreated in an electrolyte by electrochemical oxidation using alternating current. These strips or foils are passed through an aqueous electrolyte which is heated to 25.degree.-95.degree. C. and has a pH adjusted to 4.2-12.5. The electrolyte is silicate-free and contains 0.01-10 weight percent of an organic compound which forms a complex with aluminum. A current of 10-500 coulomb/dm.sup.2 is supplied to the workface of the strips or foils.

Process for pretreating strips and foils of aluminum or aluminum alloys

The invention relates to a method and apparatus for the determination of the thickness of transparent, clear or colored, layers of lacquer on bright rolled, metallic foil or thin strip, in particular of aluminium or aluminium alloys, wherein the optical transmission factor (D) of the layer is determined. The attenuation of irradiated light reflected from the metallic surface disposed in an arched configuration is measured in the infrared to visible range after transmission through the layers of lacquer.

Method and apparatus for the determination of the thickness of

The invention relates to a process for coating bare, sheared edges of the pouring or drinking outlets stamped out in metal lids for beverage cans. In the process, modified lacquers are deposited electrophoretically on the bare, non-insulated sheared regions of the lid.

Process for coating sheared edges of metal can lids

Pretreatment of aluminum strip or foil for lacquering, adhesive coating or laminating processes involves heavy metal compounds which are considered undesirable for many packaging purposes, in particular for foodstuff packaging. These disadvantages are avoided if the strip or foil is pretreated in an electrolyte by subjecting it to a three phase alternating current of which one phase is rectified and the side of the strip or foil to be treated is made to pass in sequence three electrodes of which at least one is connected to the rectified phase while the others are connected to the other phase of the alternating current. Such a pretreatment has the advantage over an alternating current treatment that the oxide layers offer high strength of adhesion and the treatment can be performed faster.

Process for continuous pretreatment by electrochemical oxidation of

To fill up the ring-shaped gaps between the tubes and fins of a tube and fin type heat exchanger with a corrosion protective hardenable filler, a unit made up of two closing pieces with filler material between them is pushed by means of the tube to be inserted in the stacked fins through the space formed by the collars of the openings in the fins which are stacked together for assembly into a heat exchanger. On passing this unit through the stacked fins the ring-shaped gaps are filled up with the filler material. The remaining thin film on the collars is also forced into the ring-shaped gaps when the tubes are subsequently expanded. A device for carrying out the process comprises a sleeve with a mandrel which slides inside the sleeve and forms a seal with the sleeve and a piston which likewise slides in the sleeve and forms a seal therewith and which lies ahead of the mandrel forming a space which can be varied in size and which accommodates the filler material. This device is positioned at and in line with a cylindrical space formed by the collars of the stack of fin material and the unit comprising the piston and mandrel with filler material between them is pushed out of the sleeve and through the cylindrical space formed by the stacked batch of fins.

Process for filling with a hardenable filler gaps where corrosive attack

To fill up the ring-shaped gaps between the tubes and fins of a tube and fin type heat exchanger with a corrosion protective hardenable filler, a unit made up of two closing pieces with filler material between them is pushed by means of the tube to be inserted in the stacked fins through the space formed by the collars of the openings in the fins which are stacked together for assembly into a heat exchanger. On passing this unit through the stacked fins the ring-shaped gaps are filled up with the filler material. The remaining thin film on the collars is also forced into the ring-shaped gaps when the tubes are subsequently expanded. A device for carrying out the process comprises a sleeve with a mandrel which slides inside the sleeve and forms a seal with the sleeve and a piston which likewise slides in the sleeve and forms a seal therewith and which lies ahead of the mandrel forming a space which can be varied in size and which accommodates the filler material. This device is positioned at and in line with a cylindrical space formed by the collars of the stack of fin material, and the unit comprising the piston and mandrel with filler material between them is pushed out of the sleeve and through the cylindrical space formed by the stacked batch of fins.

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Kreuzlingen, Switzerland

Zdenek Maly