Easy-opening can end

Abstract

An easy-opening can end comprises: an end panel; a score which is formed on the upper surface or the lower surface of the end panel; the score having a cross section of a curved surface; and a tab having a finger grasping portion. The tab is attached to the can end panel and is rotatable around tab-fastening device. The tab-fastening device is positioned offset.

What is claimed is:  
     
         1 . An easy-opening can end comprising: 
 an end panel having an upper surface and a lower surface;    a score which is formed on the upper surface or the lower surface of the end panel; and    said score having a cross section of a curved surface having a radius of 0.01 to 1 mm, the end panel having a thickness of 0.025 to 0.08 mm at the thinnest portion thereof.    
     
     
         2 . An easy-opening can end comprising: 
 an end panel having an upper surface and a lower surface;    scores which are formed on the upper surface and the lower surface of the end panel; and    said score having a cross section of a curved surface having a radius of 0.025 to 1 mm, the end panel having a thickness of 0.025 to 0.08 mm at the thinnest portion thereof.    
     
     
         3 . A method for making an easy-opening can end, comprising the step of: 
 providing an upper die and a lower die, either the upper die or the lower die having a curved surface with a radius ranging from 0.1 to 1 mm at the tip portion thereof, the other die having a flat surface at the tip portion thereof; and    press-forming an end panel by using the upper die and the lower die to form a score on the upper surface or the lower surface of the end panel so that the end panel has a thickness of 0.025 to 0.08 mm at the thinnest portion thereof.    
     
     
         4 . A method for making an easy-opening can end, comprising the step of: 
 providing an upper die and a lower die, the upper die and the lower die having a curved surface with a radius ranging from over 0.025 to 1 mm at the tip portion thereof; and    press-forming an end panel by using the upper die and the lower die to form scores on the upper surface and the lower surface of the end panel so that the end panel has a thickness of 0.025 to 0.08 mm at the thinnest portion thereof.    
     
     
         5 . An easy-opening can end comprising: 
 an end panel having an upper surface and a lower surface;    a score which is formed on the upper surface or the lower surface of the end panel;    said score having a cross section of a curved surface having a radius of 0.01 to 1 mm, the end panel having a thickness of 0.025 to 0.12 mm at the thinnest portion thereof;    a tab having a finger grasping portion, said tab being attached to the can end panel and being rotatable around tab-fastening means;    said tab-fastening means being positioned offset by a distance “a” expressed in the following equation from the center of the can end to the opposite side of an openable section:   ( D−d )/2 <a<d /2 −l     said finger grasping portion having a distance “L” from the tab-fastening means, the distance “L” being defined by the following equation:     d−l>L>d /2 −a     the tab having a first center line before rotation thereof and a second center line at an opening position, the first center line and the second line having an angle “θ” therebetween which is within a range defined by the equation:   −1<cos θ<1/(2 ×a×L )×{( d /2) 2 −( L   2   +a   2 )}   a slope protrusion for lifting the tab to above a height of a seam portion when the tab is rotated to a position for allowing the can open,    where,    a: distance between the center of the tab-fastening means and the center of can end,    L: distance between the center of the tab-fastening means and the finger grasping portion on the tab,    l: distance between the center of the tab-fastening means and a tab working section,    θ: angle between the center line of tab before rotation and the center line at opening position,    d: inner diameter of the can end,    D: outer diameter of the can end.    
     
     
         6 . An easy-opening can end comprising: 
 an end panel having an upper surface and a lower surface;    scores which are formed on the upper surface and the lower surface of the end panel;    said score having a cross section of a curved surface having a radius of over 0.025 to 1 mm, the end panel having a thickness of 0.025 to 0.12 mm at the thinnest portion thereof;    a tab having a finger grasping portion, said tab being attached to the can end panel and being rotatable around tab-fastening means;    said tab-fastening means being positioned offset by a distance “a” expressed in the following equation from the center of the can end to the opposite side of an openable section:   ( D−d )/2 <a<d /2 −l     said finger grasping portion having a distance “L” from the tab-fastening means, the distance “L” being defined by the following equation:     d−l>L>d /2 −a     the tab having a first center line before rotation thereof and a second center line at an opening position, the first center line and the second line having an angle “θ” therebetween which is within a range defined by the equation:   −1<cos θ<1/(2 ×a×L )×{( d /2) 2 −( L   2   +a   2 )}   a slope protrusion for lifting the tab to above a height of a seam portion when the tab is rotated to a position for allowing the can open,    where,    a: distance between the center of the tab-fastening means and the center of can end,    L: distance between the center of the tab-fastening means and the finger grasping portion on the tab,    l: distance between the center of the tab-fastening means and a tab working section,    θ: angle between the center line of tab before rotation and the center line at opening position,    d: inner diameter of the can end,    D: outer diameter of the can end.    
     
     
         7 . An easy-opening can end comprising: 
 an end panel comprising a steel sheet and resin film layers on an upper surface and a lower surface of the steel sheet;    a score which is formed on at least one surface of the upper surface and the lower surface of the end panel, the can being opened by fracturing the score; and    said score having a cross section of a curved surface having a radius of 0.1 to 1 mm, the end panel having a thickness of 0.025 to 0.08 mm at the thinnest portion thereof.    
     
     
         8 . A method for making an easy-opening can end, comprising the step of: 
 providing an end panel comprising a steel sheet and resin film layers on an upper surface and a lower surface of the steel sheet;    providing an upper die and a lower die, at least one of the upper die and the lower die having a curved surface with a radius ranging from 0.1 to 1 mm at the tip portion thereof; and    press-forming the end panel by using the upper die and the lower die to form a score on at least one surface of the upper surface and the lower surface of the end panel so that the end panel has a thickness of 0.025 to 0.08 mm at the thinnest portion thereof.    
     
     
         9 . A method of  claim 8 , wherein the press-forming of the end panel is carried out by applying a lubricant to the end panel.  
     
     
         10 . An easy-opening can end comprising: 
 an end panel comprising a steel sheet and resin film layers on an upper surface and a lower surface of the steel sheet;    a score which is formed on at least one surface of the upper surface and the lower surface of the end panel;    said score having a cross section of a curved surface having a radius of 0.1 to 1 mm, the end panel having a thickness of 0.025 to 0.12 mm at the thinnest portion thereof;    a tab having a finger grasping portion, said tab being attached to the can end panel and being rotatable around tab-fastening means;    said tab-fastening means being positioned offset by a distance “a” expressed in the following equation from the center of the can end to the opposite side of an openable section:   ( D−d )/2 <a<d /2 −l     said finger grasping portion having a distance “L” from the tab-fastening means, the distance “L” being defined by the following equation:     d−l>L>d /2 −a     the tab having a first center line before rotation thereof and a second center line at an opening position, the first center line and the second line having an angle “θ” therebetween which is within a range defined by the equation:   −1<cos θ<1/(2 ×a×L )×{( d /2) 2 −( L   2   +a   2 )}   a slope protrusion for lifting the tab to above a height of a seam portion when the tab is rotated to a position for allowing the can open,    where,    a: distance between the center of the tab-fastening means and the center of can end,    L: distance between the center of the tab-fastening means and the finger grasping portion on the tab,    l: distance between the center of the tab-fastening means and a tab working section,    θ: angle between the center line of tab before rotation and the center line at opening position,    d: inner diameter of the can end,    D: outer diameter of the can end.    
     
     
         11 . An easy-opening can end comprising: 
 a end panel comprising a steel sheet having a tensile strength (TS) of 30 to 45 kgf/mm 2  and a work-hardening coefficient (n-value) of 0.15 to 0.2; and    a score which is formed on at least one surface of an upper surface and a lower surface of the end panel.    
     
     
         12 . A method for making an easy-opening can end comprising the steps of: 
 providing a end panel comprising a metal sheet having a thickness of t 0  (mm), a work-hardening coefficient of n in a 40 to 90% range of uniform elongation region and a tensile strength of TS (kgf/mm 2 );    providing an upper die and a lower die, either the upper die or the lower die having a curved surface with a radius ranging from over 0.025 to 1 mm at the tip portion thereof, the other die having a flat surface at the tip portion thereof; and    press-forming the end panel by using the upper die and the lower die to form score on the upper surface or the lower surface of the end panel, the press-formed can end panel having a thickness t (mm) at the thinnest portion thereof, the thickness t (mm) satisfying the following equations.   2.5≦P≦5.0 P=t×TS ×{exp( n )/( n   n )}×[2/{square root}3×| ln (1+( t−t   0 ) /t   0 }|] n     
     
     
         13 . A method for making an easy-opening can end comprising the steps of: 
 providing a end panel comprising a metal sheet having a thickness of t 0  (mm), a work-hardening coefficient of n in a 40 to 90% range of uniform elongation region and a tensile strength of TS (kgf/mm 2 );    providing an upper die and a lower die, the upper die and the lower die having a curved surface with a radius ranging from over 0.025 to 1 mm at the tip portion thereof; and    press-forming the end panel by using the upper die and the lower die to form score on the upper surface or the lower surface of the end panel, the press-formed can end panel having a thickness t (mm) at the thinnest portion thereof, the thickness t (mm) satisfying the following equations.   2.5≦P≦5.0 P=t×TS ×{exp( n )/( n   n )}×[2/{square root}3×| ln (1+( t−t   0 ) /t   0 }|] n     
     
     
         14 . A method for making an easy-opening can end comprising the steps of: 
 providing a end panel comprising a steel sheet having a thickness of t 0  (mm), a work-hardening coefficient of n in a 40 to 90% range of uniform elongation region and a tensile strength of TS (kgf/mm 2 ) and resin film layers on both sides of the steel sheet;    providing an upper die and a lower die, either the upper die or the lower die having a curved surface with a radius ranging from over 0.1 to 1 mm at the tip portion thereof, the other die having a flat surface at the tip portion thereof; and    press-forming the end panel by using the upper die and the lower die to form score on the upper surface or the lower surface of the end panel, the press-formed can end panel having a thickness t (mm) at the thinnest portion thereof, the thickness t (mm) satisfying the following equations.   2.5≦P≦5.0 P=t×TS ×{exp( n )/( n   n )}×[2/{square root}3×| ln (1+( t−t   0 ) /t   0 }|] n     
     
     
         15 . A method for making an easy-opening can end comprising the steps of: 
 providing a end panel comprising a steel sheet having a thickness of t 0  (mm), a work-hardening coefficient of n in a 40 to 90% range of uniform elongation region and a tensile strength of TS (kgf/mm 2 ) and resin film layers on both sides of the steel sheet;    providing an upper die and a lower die, the upper die and the lower die having a curved surface with a radius ranging from over 0.1 to 1 mm at the tip portion thereof; and    press-forming the end panel by using the upper die and the lower die to form scores on the upper surface and the lower surface of the end panel, the press-formed can end panel having a thickness t (mm) at the thinnest portion thereof, the thickness t (mm) satisfying the following equations.   2.5≦P≦5.0 P=t×TS ×{exp( n )/( n   n )}×[2/{square root}3×| ln (1+( t−t   0 ) /t   0 }|] n     
     
     
         16 . A method for making an easy-opening can end comprising the steps of: 
 providing a end panel comprising a metal sheet having a thickness of t 0  (mm), a work-hardening coefficient of n in a 40 to 90% range of uniform elongation region and a tensile strength of TS (kgf/mm 2 );    providing an upper die and a lower die, either the upper die or the lower die having a curved surface with a radius ranging from over 0.025 to 1 mm at the tip portion thereof, the other die having a flat surface at the tip portion thereof;    press-forming the end panel by using the upper die and the lower die to form score on the upper surface or the lower surface of the end panel, the press-formed can end panel having a thickness t (mm) at the thinnest portion thereof, the thickness t (mm) satisfying the following equations;   5<P≦7.0 P=t×TS ×{exp( n )/( n   n )}×[2/{square root}3×| ln (1+( t−t   0 ) /t   0 }|] n     attaching a tab having a finger grasping portion to the can end panel rotatably around tab-fastening means;    said tab-fastening means being positioned offset by a distance “a” expressed in the following equation from the center of the can end to the opposite side of an openable section:   ( D−d )/2 <a<d /2 −l     said finger grasping portion having a distance “L” from the tab-fastening means, the distance “L” being defined by the following equation:     d−l>L>d /2 −a     the tab having a first center line before rotation thereof and a second center line at an opening position, the first center line and the second line having an angle “θ” therebetween which is within a range defined by the equation;   −1<cos θ<1/(2 ×a×L )×{( d /2) 2 −( L   2   +a   2 )}   arranging a slope protrusion for lifting the tab to above a height of a seam portion when the tab is rotated to a position for allowing the can open;    where,    a: distance between the center of the tab-fastening means and the center of can end,    L: distance between the center of the tab-fastening means and the finger grasping portion on the tab,    l: distance between the center of the tab-fastening means and a tab working section,    θ: angle between the center line of tab before rotation and the center line at opening position,    d: inner diameter of the can end,    D: outer diameter of the can end.    
     
     
         17 . A method for making an easy-opening can end comprising the steps of: 
 providing a end panel comprising a metal sheet having a thickness of t 0  (mm), a work-hardening coefficient of n in a 40 to 90% range of uniform elongation region and a tensile strength of TS (kgf/mm 2 );    providing an upper die and a lower die, the upper die and the lower die having a curved surface with a radius ranging from over 0.025 to 1 mm at the tip portion thereof;    press-forming the end panel by using the upper die and the lower die to form score on the upper surface or the lower surface of the end panel, the press-formed can end panel having a thickness t (mm) at the thinnest portion thereof, the thickness t (mm) satisfying the following equations;   5<P≦7.0 P=t×TS ×{exp( n )/( n   n )}×[2/{square root}3×| ln (1+( t−t   0 ) /t   0 }|] n     attaching a tab having a finger grasping portion to the can end panel rotatably around tab-fastening means;    said tab-fastening means being positioned offset by a distance “a” expressed in the following equation from the center of the can end to the opposite side of an openable section:   ( D−d )/2 <a<d /2 −l     said finger grasping portion having a distance “L” from the tab-fastening means, the distance “L” being defined by the following equation:     d−l>L>d /2 −a     the tab having a first center line before rotation thereof and a second center line at an opening position, the first center line and the second line having an angle “θ” therebetween which is within a range defined by the equation;   −1<cos θ<1/(2 ×a×L )×{( d /2) 2 −( L   2   +a   2 )}   arranging a slope protrusion for lifting the tab to above a height of a seam portion when the tab is rotated to a position for allowing the can open;    where,    a: distance between the center of the tab-fastening means and the center of can end,    L: distance between the center of the tab-fastening means and the finger grasping portion on the tab,    l: distance between the center of the tab-fastening means and a tab working section,    θ: angle between the center line of tab before rotation and the center line at opening position,    d: inner diameter of the can end,    D: outer diameter of the can end.    
     
     
         18 . A method for making an easy-opening can end comprising the steps of: 
 providing a end panel comprising a metal sheet having a thickness of t 0  (mm), a work-hardening coefficient of n in a 40 to 90% range of uniform elongation region and a tensile strength of TS (kgf/mm 2 ) and resin film layers on both sides of the steel sheet;    providing an upper die and a lower die, either the upper die or the lower die having a curved surface with a radius ranging from 0.1 to 1 mm at the tip portion thereof, the other die having a flat surface at the tip portion thereof;    press-forming the end panel by using the upper die and the lower die to form score on the upper surface or the lower surface of the end panel, the press-formed can end panel having a thickness t (mm) at the thinnest portion thereof, the thickness t (mm) satisfying the following equations;   5<P≦7.0 P=t×TS ×{exp( n )/( n   n )}×[2/{square root}3×| ln (1+( t−t   0 ) /t   0 }|] n     attaching a tab having a finger grasping portion to the can end panel rotatably around tab-fastening means;    said tab-fastening means being positioned offset by a distance “a” expressed in the following equation from the center of the can end to the opposite side of an openable section:   ( D−d )/2 <a<d /2 −l     said finger grasping portion having a distance “L” from the tab-fastening means, the distance “L” being defined by the following equation:   d−l>L>d/2 −a     the tab having a first center line before rotation thereof and a second center line at an opening position, the first center line and the second line having an angle “θ” therebetween which is within a range defined by the equation;   −1<cos θ<1/(2 ×a×L )×{( d /2) 2 −( L   2   +a   2 )}   arranging a slope protrusion for lifting the tab to above a height of a seam portion when the tab is rotated to a position for allowing the can open;    where,    a: distance between the center of the tab-fastening means and the center of can end,    L: distance between the center of the tab-fastening means and the finger grasping portion on the tab,    l: distance between the center of the tab-fastening means and a tab working section,    θ: angle between the center line of tab before rotation and the center line at opening position,    d: inner diameter of the can end,    D: outer diameter of the can end.    
     
     
         19 . A method for making an easy-opening can end comprising the steps of: 
 providing a end panel comprising a metal sheet having a thickness of t 0  (mm), a work-hardening coefficient of n in a 40 to 90% range of uniform elongation region and a tensile strength of TS (kgf/mm 2 ) and resin film layers on both sides of the steel sheet;    providing an upper die and a lower die, the upper die and the lower die having a curved surface with a radius ranging from over 0.1 to 1 mm at the tip portion thereof;    press-forming the end panel by using the upper die and the lower die to form scores on the upper surface and the lower surface of the end panel, the press-formed can end panel having a thickness t (mm) at the thinnest portion thereof, the thickness t (mm) satisfying the following equations;   5<P≦7.0 P=t×TS ×{exp( n )/( n   n )}×[2/{square root}3×| ln (1+( t−t   0 ) /t   0 }|] n     attaching a tab having a finger grasping portion to the can end panel rotatably around tab-fastening means;    said tab-fastening means being positioned offset by a distance “a” expressed in the following equation from the center of the can end to the opposite side of an openable section:   ( D−d )/2 <a<d /2 −l     said finger grasping portion having a distance “L” from the tab-fastening means, the distance “L” being defined by the following equation:     d−l >L>d /2 −a     the tab having a first center line before rotation thereof and a second center line at an opening position, the first center line and the second line having an angle “θ” therebetween which is within a range defined by the equation;   −1<cos θ<1/(2 ×a×L )×{( d /2) 2 −( L   2   +a   2 )}   arranging a slope protrusion for lifting the tab to above a height of a seam portion when the tab is rotated to a position for allowing the can open;    where,    a: distance between the center of the tab-fastening means and the center of can end,    L: distance between the center of the tab-fastening means and the finger grasping portion on the tab,    l: distance between the center of the tab-fastening means and a tab working section,    θ: angle between the center line of tab before rotation and the center line at opening position,    d: inner diameter of the can end,    D: outer diameter of the can end.