Method of Forming a Metal Sheet Blank

Abstract

A method of forming a metal sheet blank ( 7 ) by deep-drawing the sheet blank ( 7 ) so as to produce a deep-drawn pre-form ( 7 ) having a base portion ( 8 ) and a skirt portion ( 9 ) extending at substantially right angles therefrom. The height of the skirt portion ( 9 ) varies around the perimeter of the pre-form ( 7 ) so as to provide a skirt ( 9 ) having a curved edge course ( 10 ), and subsequently processing said curved edge ( 10 ) to obtain a curled or bent edge ( 10 ) having a curved course. The invention also relates to a tool ( 1,6 ) and an apparatus for forming a sheet blank and to a lid or container ( 7 ).

1 . A method of forming a metal sheet blank comprising:
 deep-drawing the sheet blank so as to produce a deep-drawn pre-form having a base portion and a skirt portion extending at substantially right angles therefrom, the height of said skirt portion varying around the perimeter of the pre-form so as to provide a skirt having a curved edge course; and   processing said curved edge to obtain a curled or bent edge having a curved course.   
   
   
       2 . The method according to  claim 1 , further comprising punching the blank into circular or non-circular shape from a basic metal sheet. 
   
   
       3 . The method according to  claim 1 , wherein the method is performed by sequentially punching the blank, deep-drawing the blank to a pre-form, and curling or bending the edge of the pre-form. 
   
   
       4 . The method of  claim 1  further comprising:
 providing a first tool part having a curling portion, said curling portion forming a three-dimensional path in the tool to enable formation of said curled edge having a curved edge course;   providing a second tool part opposite in relation to said first tool, said second tool having a die cavity;   providing a punch in an opening in the first tool part, said punch being movable in relation to the first tool part to extend beyond a plane of the first tool part so as to be received in said die cavity of the second tool upon moving the second tool part in relation to said punchy;   placing said sheet blank between the first and second tool part;   deep-drawing said sheet blank by moving the first and second tool in relation to said punch, or vice versa, so that the punch moves into said cavity of the second tool and thereby deep-draws the sheet blank into said pre-form; and   processing said curved edge by moving said pre-form towards the first tool part, or vice versa, for abutment of the curved edge of the pre-form with the curling portion to provide a curled curved edge.   
   
   
       5 . The method according to  claim 4 , further comprising pressing said pre-form towards the punch before processing, said step of pressing being provided by mechanical or hydraulic or pneumatic device. 
   
   
       6 . The method according to  claim 2 , wherein a punch is provided between the first and second tool part on the first or second tool part, and the step of punching comprises moving the first tool part towards the second tool part for cutting out said sheet blank from a sheet of metal. 
   
   
       7 . The method according to  claim 1 , wherein the sheet blank is or non-circular. 
   
   
       8 . A tool comprising a first tool part having a curling portion, said curling portion forming a three-dimensional path in the tool to enable formation of a curled edge on a metal pre-form having a curved edge course. 
   
   
       9 . The tool according to  claim 8 , further comprising a cutting edge adapted to provide a sheet blank having a circular or non-circular shape from a sheet of metal and which blank is adapted to be formed into said pre-form. 
   
   
       10 . The tool according to  claim 8 , further comprising a punch movable in an opening arranged in the first tool part, whereby the punch is movable to extend beyond a plane of the first tool part. 
   
   
       11 . The tool according to  claim 10 , further comprising a second tool part oppositely arranged in relation to said first tool and having a die cavity adapted to receive said punch upon moving said second tool part in relation to said punch so as to allow deep-drawing of a metal sheet blank, provided between the first and second tool, into said metal pre-form. 
   
   
       12 . The tool according to  claim 9 , wherein the cutting edge is provided on the first or second tool so as to cut out said sheet blank upon moving said first and second tool towards each other. 
   
   
       13 . The tool according to  claim 9 , wherein the cutting edge is provided on a third tool arranged adjacent to said first or second tool, so as to cut out said blank upon moving said first or second tool towards said third tool. 
   
   
       14 . The tool according to  claim 10 , further comprising a second punch or piston to press the pre-form towards the first tool part or to keep the pre-form stationary while pressing the first tool part towards the pre-form for abutment of the curved edge of the metal pre-form with the curling portion to provide a curled curved edge. 
   
   
       15 . An apparatus for deep-drawing a metal sheet blank, said apparatus comprising a female tool part for receiving a male tool part when deep-drawing said metal sheet blank to produce a pre-form having a base portion and a skirt portion extending at substantially right angles therefrom, the height of said skirt portion varying around the perimeter of the pre-form so as to provide a skirt having a curved edge course, said apparatus further comprising a curling tool for curling said curved edge. 
   
   
       16 . The apparatus according to  claim 15 , wherein the curling tool comprises a curling portion forming a three-dimensional path in a tool part to enable formation of a curled edge on said metal pre-form having a curved edge course. 
   
   
       17 . The apparatus according to  claim 15 , further comprising a cutting tool for cutting the sheet blank into a circular or non-circular shape prior to deep-drawing. 
   
   
       18 . An apparatus for deep-drawing a metal sheet blank and comprising a tool according to  claim 8 . 
   
   
       19 . An apparatus for deep-drawing a metal sheet blank and adapted to perform the method of  claim 1 . 
   
   
       20 . A metal lid or container having a base portion and a skirt portion extending at substantially right angles therefrom, the height of said skirt portion varying around the perimeter of the lid or container so as to provide a skirt having a curved edge course, said curved edge further being curled. 
   
   
       21 . A metal lid or container having a base portion and a skirt portion extending therefrom and terminating in a curled edge, the height of said skirt portion varies around the perimeter of the lid or container. 
   
   
       22 . The metal lid or container according to  claim 20 , wherein said height is in the range of 0 to 20 cm. 
   
   
       23 . The metal lid or container according to  claim 20 , wherein the lid or container has a circular, non-circular, organic or polygonal shape, or a combination of one or more shapes. 
   
   
       24 . The metal lid or container according to  claim 20 , produced by the method of  claim 1 .