Method of drawn and ironed processing of resin coated metal sheet and resin coated drawn and ironed can produced thereby

1. A method of drawing and ironing a resin-coated metal sheet, comprising:

preparing the resin-coated metal sheet manufactured by coating at least one surface of a metal sheet with an organic coating resin;

drawing and ironing the resin-coated metal sheet into a can body by employing a punch and a die, wherein the punch has a reduced diameter portion toward its rear end; and

forming the can body having an ironing in the middle portion of its sidewall and substantially no ironing at its open end.

2. A method of drawing and ironing a resin-coated metal sheet as set forth in claim 1 , further comprising:

using a plurality of dies for the ironing,

disposing at least two dies with a land distance of 3 to 40 mm, and

using the former of the two dies to perform 20% or more of the total ironing work by the two dies.

3. A method of ironing a resin-coated metal sheet as set forth in claim 1 , comprising:

using two dies for the ironing, a former die and a latter die;

wherein the two dies are so arranged that the former and latter dies iron the resin-coated metal sheet contiguous to each other.

4. A drawn and ironed can of a resin-coated metal sheet which is made by employing an ironing method as set forth in claim 1 .

5. A method of ironing a resin-coated metal sheet as set forth in claim 2 , wherein the two dies are so arranged that the two dies are contiguous to each other.

6. A drawn and ironed can of a resin-coated metal sheet which is made by employing an ironing method as set forth in claim 5 .

7. A drawn and ironed can of a resin-coated metal sheet which is made by employing an ironing method as set forth in claim 3 .

8. A drawn and ironed can of a resin-coated metal sheet which is made by employing an ironing method as set forth in claim 2 .

9. A method of ironing a resin-coated metal sheet as set forth in claim 1 , further comprising:

providing an ironing ratio at the open end of the can body smaller than the ironing ratio in the middle portion of the sidewall of the can body, and

providing a clearance between the reduced diameter portion of the punch and the inner surfaces of the die, wherein the clearance is wider than what causes damage to the coating resin.

10. A method of ironing a resin-coated metal sheet as set forth in claim 1 , wherein the open end of the can body is formed by the reduced diameter portion at the rear end of the punch.

11. In a method of forming a can body from a resin-coated metal sheet which has been drawn into a cup shape having an open end, comprising ironing the cup shaped resin-coated metal sheet to form the can body having a sidewall, the improvement comprising

placing the cup-shaped resin-coated metal sheet on a punch having a front section having a first diameter and a rear section having a second diameter, the front section being adjacent a free end of the punch and the first diameter being greater than the second diameter, the cup shaped resin-coated metal sheet being complementary in shape to the first section;

passing the punch with the cup shaped resin-coated metal sheet thereon through an ironing die from the free end of the punch along a length of the first section to iron the cup shaped resin-coated sheet and provide the can body having a reduced sidewall thickness and an increased height;

wherein said ironing results in the open end of the can body overlying the rear section of the punch having a reduced diameter so that the open end of the cup shaped resin-coated metal sheet is not ironed and has a greater thickness than the sidewall of the can body.