Metal treatment – Stock – Ferrous
Patent
1997-10-03
2000-05-02
Yee, Deborah
Metal treatment
Stock
Ferrous
148651, C22C 3804, C21D 804
Patent
active
060568321
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing a steel sheet or strip for making a can obtained by drawing and ironing, of the beverage can type.
The present invention also relates to a steel sheet or strip for making a can obtained by drawing and ironing.
2. Description of the Background
This type of can usually comprises a bottom, a thin peripheral wall and a neck for achieving the setting or seaming of a lid, which may be of the easily-opened type, and is produced in particular by drawing and ironing a cup cut from a metal sheet or strip.
For this purpose, the cup is subjected first of all to a drawing operation with a relatively severe reduction on a press which comprises in the conventional manner, on one hand, a fixed punch and a support forming a peripheral blank holder which is slidable around said punch and on which the cup rests, and, on the other hand, a die to be applied against the cup with a force transmitted vertically by an upper slide.
The cup, comprising a bottom and a flange formed by the drawing operation, is then either calibrated by a light drawing operation without the use of a blank holder, or redrawn with a blank holder and is then subjected to an ironing operation which comprises drawing the flange, by means of a draw die with successive reductions, so as to progressively form the thin peripheral wall of the can.
Thereafter, the bottom is formed on the draw die so as to impart thereto a given geometry and the neck of the thin peripheral wall is formed in accordance with two methods, namely a necking method with a die, named die-necking, or a necking method employing a forming roller, named spin necking
The method for necking with a die comprises forcing the neck into a die having a conical inlet profile and a cylindrical outlet profile. A cylindrical element guides the formed wall as it leaves the die.
The force required to permit the deformation of the metal is derived from the thrust applied on the bottom of the can and axially transmitted by its thin peripheral wall.
To reach the desired inside diameter, a plurality of successive reductions are required, each being a distinct forming step. When the reduction in diameter is obtained, flanging is usually effected with flanging rollers.
The spin-necking method employing a forming roller comprises driving the can in rotation while it is maintained between a pusher and a centring ring.
The free end of the thin peripheral wall is engaged on a mandrel and two axially travelling rollers form the neck of the can which progressively leaves the mandrel while always being maintained between the pusher and the centring ring.
The profile of the neck is obtained by the simultaneous displacements of the rollers, the centring ring and the pusher.
Subsequent to these various operations, the can is filled and a lid, for example of the easily-opened type, is set or seamed on the neck of the can.
It is known to use for making this type of can a steel sheet or strip of extra-soft steel type the composition of which in percentage by weight is the following: chromium, the remainder being iron and residual impurities.
The sheet or the strip is produced by a process in which the slab issuing from a continuous casting operation is hot rolled, then cold rolled to obtain a thin sheet or foil which is subjected to a recrystallization annealing operation at a temperature below Ac1.
This process permits obtaining a thin sheet or foil which has a final thickness of about 0.30 mm, and making from this sheet a can whose thin peripheral wall has, after drawing and ironing, a thickness of the order of 0.1 mm.
Now, manufacturers of cans, for reasons of economy and increased productivity, aim at producing cans of reduced weight, i.e. with thinner walls.
In order to enable the can with thinner walls to withstand the pressure of the liquids it contains, particularly when it concerns a gaseous beverage, and in order to ensure that the can itself has a sufficient strength, steels of improved mechanical cha
REFERENCES:
patent: 5587027 (1996-12-01), Tosaka et al.
Patent Abstracts of Japan, vol. 16, No. 128 (C924), Apr. 2, 1992 & JP,A,03 294432 (Nippon Steel), Dec. 25, 1991.
Patent Abstracts of Japan, vol. 14, No. 382 (C-749), Aug. 17, 1990 & JP,A,02 141536 (Nippon Steel), May 30, 1990.
Lespagnol Michel
Renard Jean-Francois
Seurin P.
Sollac
Yee Deborah
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