Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon

Definitions

• the present invention relates to a process for manufacturing aluminum alloy products suitable for drawing and which applies more particularly to the strips obtained by casting between rolls.
• This band is particularly interesting for the production by deep drawing and stretching, in particular for boxes - ment packaging of beverages. For this, it is brought to a thickness close to 300 ⁇ m by cold or hot rolling, in several passes which can be separated by intermediate annealing operations, then circular discs are cut from the sheet thus obtained and they are cut. submits to the combined action of a punch and a die, which causes by stamping the formation of a bucket whose walls surround the piston. This bucket then undergoes a dimensional transformation in a so-called stretching operation during which its walls are thinned.
• This shaping requires the application of significant forces to the surface of the metal and this quite often results in the appearance of a phenomenon known as "galling", that is to say binding between the stamped material and the tools.
• This galling translates for aluminum alloys by fouling of the tools, gradually leading to the appearance of scratches which can, in certain cases, reduce the mechanical resistance of the boxes, even sometimes causing breakage during the operation of stretching and, in any case, harm their aesthetic quality.
• the raw casting strip had to be heated in air at a temperature between 520 and 550 ° C for a few hours to find anti-galling properties.
• the Applicant has succeeded in solving the problems of galling and irregularity in coloring and gloss by operating from 'a classic 3004 and under the usual conditions of heat treatment.
• the invention therefore consists of a process for manufacturing sheets of aluminum alloy suitable for drawing, in which the alloy is cast between cylinders so as to form a strip which is heat treated, rolled to a thickness similar to of 300 ⁇ m in a series of passes which can be separated by annealing operations, so as to lead to a sheet from which discs are cut which are subjected to drawing and drawing, characterized in that the surface of the strip is mechanically cleaned and then modified by heating in air.
• the new means implemented firstly include mechanical cleaning of the strip and, preferably, continuously. It can be carried out using any known device which essentially eliminates the particles deposited on the surface of the strip and the thick oxide layer formed during casting, while limiting the thickness of metal removed to a minimum.
• This cleaning can be carried out on parade, preferably by brushing using a brush with metallic or composite bristles (for example nylon plus tungsten carbide) driven by a rotational movement. Brushing can be done in the direction of travel of the strip, by means of a fixed cylindrical brush, the length of which is slightly greater than the width of the strip and the axis of which is perpendicular to this direction.
• the cleaning can also be carried out on the strip having already undergone a rolling pass when its thickness is close to 2.7 mm.
• Cleaning can be carried out on one or both sides depending on the destination of the product. In the case of bolting products, only the cleaning of the face which will form the outside of the box is necessary.
• an "anti galling" layer is reformed on the surface of the strip by a heat treatment at high temperature in the air. This operation is carried out by heating the coil formed by the cleaned strip and wound at the outlet of the casting machine, in air, at a temperature between 520 and 550 ° C for 4 to 8 hours. A strip, heated to a lower temperature or for a shorter period, is just as sensitive to galling during stretching as a raw cleaning strip.
• the heating is carried out at a temperature above 560 ° C., the results are excellent from the galling point of view, but there is then formed on the strip a brown layer which results, at the level of the drawn and drawn products, by surface irregularities such as a more or less shiny and more or less brownish appearance, the unsightly effect of which results in the disposal of the box thus obtained.
• the modification of the surface of the strip by heat treatment can also be carried out continuously on passing, at the outlet of the casting machine after brushing. Under these conditions, the heating time being necessarily short and of the order of 1 to 10 minutes, unless there are very long passage ovens, the treatment temperature must be higher and between 600 and 620 ° C. to make a suitable modification of the surface.
• This treatment is preferably carried out in an electric oven, but it is also possible to use a flame oven or an oven with controlled atmosphere.
• the treatment is optimized as a function of the type of oven, its more or less humid atmosphere and the composition of the alloy treated, in particular as regards its magnesium and manganese content.
• alloy 3004 This process therefore does not only apply to alloy 3004 and the results of this invention have been verified and confirmed with alloys richer than the latter in magnesium, which contained, for example, 0.8% Mn and 2% Mg, or less rich in magnesium, for example, with an Mn content of 1.5% and Mg content of 0.5%.
• this treatment in an oxidizing atmosphere can, for certain alloys, contribute to the homogenization effect sought to improve the mechanical characteristics.
• the strip covered with the deposit caused by the heating is then subjected to the rolling operations to bring it to the state of sheets with a thickness close to 300 ⁇ m.

Landscapes

• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Organic Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Thermal Sciences (AREA)
• Metal Rolling (AREA)
• Shaping Metal By Deep-Drawing, Or The Like (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Continuous Casting (AREA)
• Heat Treatment Of Nonferrous Metals Or Alloys (AREA)
• Powder Metallurgy (AREA)

Applications Claiming Priority (2)

Publications (2)

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Citations (9)

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• 1982
  • 1982-04-30 FR FR8207924A patent/FR2526047A1/fr active Granted
• 1983
  • 1983-02-25 US US06/469,757 patent/US4441933A/en not_active Expired - Lifetime
  • 1983-03-11 PH PH28634A patent/PH18237A/en unknown
  • 1983-04-25 JP JP58072762A patent/JPS58199854A/ja active Granted
  • 1983-04-25 AR AR292805A patent/AR231151A1/es active
  • 1983-04-25 CA CA000426641A patent/CA1203068A/fr not_active Expired
  • 1983-04-25 GR GR71195A patent/GR71597B/el unknown
  • 1983-04-26 GB GB08311283A patent/GB2119294B/en not_active Expired
  • 1983-04-26 IN IN500/CAL/83A patent/IN159293B/en unknown
  • 1983-04-27 SU SU833586955A patent/SU1306484A3/ru active
  • 1983-04-27 TR TR21513A patent/TR21513A/xx unknown
  • 1983-04-28 MA MA20004A patent/MA19784A1/fr unknown
  • 1983-04-28 AU AU14033/83A patent/AU550513B2/en not_active Ceased
  • 1983-04-29 NO NO831516A patent/NO831516L/no unknown
  • 1983-04-29 ES ES521949A patent/ES8402620A1/es not_active Expired
  • 1983-04-29 BR BR8302222A patent/BR8302222A/pt unknown
  • 1983-04-29 DE DE8383420075T patent/DE3360967D1/de not_active Expired
  • 1983-04-29 EP EP83420075A patent/EP0094328B1/de not_active Expired
• 1986
  • 1986-12-30 MY MY318/86A patent/MY8600318A/xx unknown

Patent Citations (10)

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