Metal can for a food product

Abstract

The invention relates to a metal can ( 40 ) for preserving a food product sterilised by heat treatment after closing the can, made up of an integral body forming the bottom ( 41 ) and the side wall ( 43 ) of the can, and a lid ( 42 ) mounted on said body in order to seal the latter, the minimum thickness of the side wall ( 43 ) being between 20% and 60% of the thickness of the centre of the bottom ( 41 ). According to the invention, the height of the can ( 40 ) is between 1.5 and 3.5 times the width thereof, and the bottom ( 41 ) and/or the lid ( 42 ) of the can has a central wall ( 411, 421 ) with an outwardly convex shape, connected to the side wall ( 43 ) by a peripheral groove ( 410 ) opening up towards the outside.

1 . A method for obtaining an integral body of a metal can for preserving a food product sterilized by heat treatment after closing of the can, the integral body having a bottom and a side wall, the method comprising:
 ironing the side wall of the integral body using Drawn and Wall Ironing technology (DWI) which is implemented so that
 a minimum thickness of the side wall is between 20% and 60% of a thickness of the center of the bottom, and 
 a height of the body is between 1.5 times and 3.5 times the width thereof, and 
   providing the bottom with a central wall that has an outwardly convex shape connected to the side wall by a peripheral groove opening up outwards.   
     
     
         2 . The method according to  claim 1 , wherein the peripheral groove has a first wall connected to the convex central wall, a second wall connected to a peripheral area of connection to the side wall of the can, and a bottom forming a rounded shape, and
 wherein the first wall forms an angle between 2° and 45° with the axis of the can,   the connection between the first wall and the central wall forms a rounded shape with a radius greater than 0.5 mm,   a depth of the groove is between 1 mm and 7 mm, and   the rounded shape of the bottom of the groove has a radius smaller than 5 mm.   
     
     
         3 . The method according to  claim 1 , further comprising forming beads on the side wall to increase a resistance thereof to external pressure. 
     
     
         4 . A method for preserving a food product sterilized by heat treatment, comprising:
 obtaining an integral body of a metal can comprising a bottom and a side wall, including ironing the side wall with Drawn and Wall Ironing technology (DWI) which is implemented so that
 a minimum thickness of the side wall is between 20% and 60% of a thickness of the center of the bottom, and 
 a height of the body is between 1.5 times and 3.5 times the width thereof; 
   adding the food product to be sterilized in the integral body;   closing the integral body with a lid; and   sterilizing the can by heat treatment after the closing thereof,   wherein one of the bottom and the lid has a central wall with an outwardly convex shape connected to the side wall by a peripheral groove opening up outwards.   
     
     
         5 . The method according to  claim 4 , wherein the peripheral groove of the integral body has a first wall connected to the convex central wall, a second wall connected to a peripheral area of connection to the side wall, and a bottom forming a rounded shape, and
 wherein   the first wall forms an angle between 2° and 45° with the axis of the can,   the connection between the first wall and the central wall forms a rounded shape with a radius greater than 0.5 mm,   a depth of the groove is between 1 mm and 7 mm, and   the rounded shape of the bottom of the groove has a radius smaller than 5 mm.   
     
     
         6 . The method according to  claim 4 , wherein the sterilization by heat treatment includes heating the content of the can to a temperature of about 110° C. to 150° C. 
     
     
         7 . The method according to  claim 4 , wherein an internal pressure of the can is higher than atmospheric pressure. 
     
     
         8 . The method according to  claim 7 , further comprising adding a substance to a content of the can before the closing thereof, and vaporizing the substance to produce an overpressure inside the can. 
     
     
         9 . The method according to  claim 8 , wherein the substance is liquid nitrogen. 
     
     
         10 . The method according to  claim 4 , wherein, in the lid, the peripheral groove has a first wall connected to the convex central wall, a second wall connected to a peripheral area of connection to the side wall of the can, and a bottom forming a rounded shape, and
 wherein   the first wall forms an angle between 2° and 45° with the axis of the can,   the connection between the first wall and the central wall forms a rounded shape with a radius greater than 0.5 mm,   a depth of the groove is between 1 mm and 7 mm, and   the rounded shape of the bottom of the groove has a radius smaller than 5 mm.   
     
     
         11 . The method according to  claim 4 , wherein the lid comprises a disk of steel-based material, and wherein a capacity of the can is one of 212 ml, 425 ml, and 850 ml and the lid has a diameter 52 mm, 65 mm and 83 mm, respectively. 
     
     
         12 . The method according to  claim 4 , wherein the lid comprises an aluminum disk, and wherein a capacity of the can is one of 212 ml, 425 ml, and 850 ml and the lid has a diameter of one of 52 mm, 63.7 mm and 81.5 mm, respectively. 
     
     
         13 . The method to  claim 4 , further comprising forming beads on the side wall so as to increase resistance to external pressure.