HK1061995B - Can lid closure and method of joining a can lid closure to a can body - Google Patents

Description

Can lid and method of attaching same to can body

Technical Field

The present invention relates generally to metal containers and more particularly to metal cans.

Background

Aluminum cans are used primarily as containers for retail serving of beverages. Aluminum cans are sold in billions annually, and so their design has been improved over the years to reduce cost and improve performance. Improvements have also been made to improve recoverability from ecological considerations.

Cost can be reduced by saving material, reducing scrap, and improving productivity. The performance improvement may be functional, such as improving sealing and pressure bearing capabilities. Thinner metal sheets can be used with such improvements, directly reducing material costs. The performance improvement may also be ergonomic, such as a can end configured to facilitate finger pull of the tab or for a person to comfortably drink with their mouth.

Aluminum cans are typically made from a pre-plated aluminum alloy such as aluminum alloy 5182. Cans, which are typically made of relatively thin metal sheets, must be able to withstand pressures approaching 100psi, which the industry requires to withstand 90 psi. Cans are generally constructed of a can body to which a can lid is attached. Both parts have to meet certain specifications and requirements. For example, the top surface of the can end must be capable of nesting with the bottom surface of the can to hold the cans together on top of one another. The can lid itself is also required to be stacked up and down for convenient transportation before being loaded onto the can body. Efforts have been made to meet these functional requirements with less and less material.

PCT International publication No. WO96/37414 describes a can lid design with reduced metal usage. The can lid includes a peripheral portion or "bead", a frustoconical can seamer wall extending downwardly from the interior of the peripheral bead, an outwardly recessed annular bead or "countersink" extending radially inwardly from the can seamer wall, and a center panel supported by the interior of the countersink. The frustoconical seamer wall is inclined at an angle of 20-60 deg. with respect to an axis perpendicular to the central panel. The seamer wall joins the countersink with the circumferential bead and contacts the seamer forming the seam during seam formation. A double seam is formed between the can end and the can body by a process in which a part frustoconical, part cylindrical can seamer is used to center the circumferential bead on the can body flange. The frustoconical portion of the seamer is designed to abut the frustoconical seamer wall of the can lid. The circumferential bead on the lid overlaps the body flange by a common amount. A double seam is formed between the two parts by first rolling the can lid/body against a seam forming roller and then rolling the can lid/body against a flattening roller. In the flattening operation, the portion of the seamer wall adjacent to the circumferential bead is flattened after being bent against the cylindrical surface of the seamer. The circumferential bead portion of the can lid of international publication No. wo96/37414 joined to the can body by a seam is of known dimensions.

The can lid of international publication No. wo96/37414 is also susceptible to metal deformation during seam formation and cannot withstand high pressures. The can lid disclosed in U.S. Pat. No.6,065,634(Brifcani) is the same as International publication No. WO96/37414.

Another PCT international publication No. wo98/34743 discloses a can lid modified from the international publication No. wo96/37414 can lid in that the seamer wall of the can lid is formed of two parts. The can lid includes a peripheral portion or "bead", a two-part seamer wall extending downwardly from the interior of the peripheral bead, an outwardly recessed annular bead or "countersink" extending radially inwardly from the seamer wall, and a center panel supported by the interior of the countersink. The first portion of the seamer wall is frustoconical, abuts the curl, and is inclined at an angle of 1-39, typically 7-14, to an axis perpendicular to the central panel. The second part of the seamer wall is frustoconical, is contiguous with the reinforcing rib, and is inclined at an angle of 30-60 °, preferably 40-45 °, to the axis perpendicular to the central panel. A double seam is formed between the can end and the can body by a process in which the circumferential bead is centred on the can body flange by a two-part seamer comprising a frusto-conical and cylindrical portion as in No. wo 96/37414. A double seam is formed between the two parts by first rotating the can lid/body against a seam forming tool and then against a flattening roller. A first portion of the seamer wall adjacent the circumferential seam is deformed into contact with the cylindrical surface of the seamer during a seam forming operation.

Disclosure of Invention

According to the present invention, there is provided a can lid for a can body, comprising: a central panel having a central axis perpendicular to the diameter of the outer rim of the can lid; an annular countersink portion extending radially outwardly from said center panel; an arcuate portion extending radially outwardly from said annular countersink, having a radius of no more than 12.7mm and a center point below the can lid surface, wherein a line passing through the ends of said arcuate portion makes an angle of 20-80 ° with said central axis of said center panel; a step portion extending radially outwardly from said arcuate portion, the step portion having a radius of at least 0.254mm and a center above the can lid surface; a first transition portion extending radially outwardly from said step portion, said first transition portion being generally frustoconical and intersecting said central axis at an angle of at least 4 ° but no greater than 12 °; a second transition portion extending radially outwardly from said first transition portion, the second transition portion having a radius of at least 0.508mm and a center located below the surface of the can lid; and a circumferential bead extending radially outwardly from the second transition portion.

According to the present invention, there is also provided a method of forming a double seam joining a can body and a can lid, the can lid comprising: a central panel having a central axis perpendicular to the diameter of the outer rim of the can lid; an annular countersink portion extending radially outwardly from said center panel; an arcuate portion extending radially outwardly from said annular countersink, wherein a line passing through both ends of said arcuate portion makes an angle of 20-80 ° with said central axis of said center panel; a step portion extending radially outwardly from said arcuate portion; a first transition portion extending radially outward from the step portion; a second transition portion extending radially outwardly from the first transition portion to a circumferential bead, the can body having a flange, the method comprising the steps of: supporting the can body on a floor; placing the can lid on the can body such that the second transition portion abuts the can body flange; providing a seamer having a lower portion, a recessed portion and an upper portion, the upper portion of the seamer having a frustoconical portion and a driving surface against a stepped portion of the can lid, the recessed portion of the seamer not deforming said arcuate portion of said can lid during seam formation, the lower portion of the seamer abutting a surface of said annular countersink on a seamer abutment when the seamer is engaged with the can lid; engaging the can cover with the can seamer; rotating the can and can lid assembly using a can seamer; rolling the circumferential bead and can body flange together to form an intermediate circumferential seam; and pressing the intermediate circumferential seam against the upper portion of the seamer to form a double seam.

The present invention contemplates an improved aluminum can end having a reduced amount of aluminum, reduced distortion when forming the seam, and an improved seam between the can end and can body. A preferred embodiment of the disclosed can lid includes a central panel having a central axis perpendicular to a diameter of the outer rim of the can lid, an annular countersink extending radially outward from the central panel, an arcuate portion extending radially outward and upward from the annular countersink, a step portion extending radially outward and upward from the arcuate portion, a first transition portion extending radially outward and upward from the step portion, a second transition portion extending radially outward from the first transition portion, and a circumferential bead extending radially outward from the second transition portion. The preferred embodiment can be used in a seam forming seamer having a frustoconical upper drive portion, a bowl portion and a lower drive portion.

Drawings

The accompanying drawings are included as part of the specification and are included to help explain the present invention. The drawings are only schematic and do not necessarily represent precisely the preferred embodiments of the invention. The drawings illustrate preferred embodiments of the invention, both as to its manufacture and use, and are not to be construed as limiting the invention to the illustrated and described examples. The advantages and features of the present invention will be apparent from the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of a portion of a can lid constructed in accordance with the present invention;

FIG. 2 is a cross-sectional view of a portion of a can lid constructed in accordance with the present invention;

FIG. 3 is a cross-sectional view of a portion of a can lid on a can body prior to forming a double seam;

FIG. 4 is a cross-sectional view of a portion of a can lid on a can body in a first step of forming a double seam;

FIG. 5 is a cross-sectional view of a portion of a can lid on a can body in a final step of forming a double seam;

FIG. 6 is a cross-sectional view of a can lid stacked one on top of the other prior to seam formation in accordance with the present invention;

FIG. 7 is a top-down cross-sectional view of the can of the present invention after filling with a beverage; and

FIG. 8 is a cross-sectional view of a seamer.

Detailed Description

The invention is described below with reference to the drawings showing examples of the manufacture and use of the invention. The drawings are merely schematic representations, not necessarily to scale, of illustrative embodiments of the invention. In these drawings, the same or corresponding parts are denoted by the same reference numerals. The embodiments shown are illustrative. Many details are well known and will not be shown or described. It is not required that all of the details, components, elements, or steps described herein be novel. While the drawings and specification illustrate the many features and advantages of the invention, the description is illustrative only, and changes may be made in detail, especially in matters of structure, shape and size of the parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. The dimensions used in describing can lids are tool dimensions and can lids made in accordance with the present invention may differ slightly from the actual dimensions of the tool. As used herein, the terms "radially outwardly extending," "radially inwardly extending," "radially downwardly extending," and "radially upwardly extending" refer to one portion extending from another portion in the direction indicated. But does not necessarily mean that these parts are connected to each other; there may be other parts between the two parts not shown or described. This patent uses the word "connected" in its ordinary sense. The term "upwardly" as used herein refers to a can end as viewed when the can end is placed on a flat surface with the tab on the surface opposite the flat top surface, such as when looking down at the top surface of a beverage can.

Prior to the description of the present invention, the applicant has noted that the terminology used to describe the various parts of the can lid of the present invention has been different from that used in the prior application due to the further development of the claimed can lid described in the prior international patent application No. pct/US00/42561, of which the present application is a continuation-in-part. These differences relate to further developments in seamer and can lid design, particularly with respect to the point of engagement between the seamer and the can lid during seam formation. These differences, which are described in detail below, indicate that the parts of the invention are described more precisely than in the original application.

In the No. pct/US00/42561 application, see in particular fig. 4 of that application, seamer 44 has a drive surface 46 for abutting, engaging arcuate seamer walls 132 during seam forming, and thus the portion identified as 132 is described using the term seamer wall. Further, No. pct/US00/42561 discloses a step portion 34 extending radially outwardly from the arcuate seamer wall, a transition portion 36 extending radially outwardly from the step portion, and a circumferential bead portion 38 extending radially outwardly from the transition portion.

As will be described in detail below, the can lid of the present invention is primarily intended to make further developments and modifications to what was previously referred to as the "seamer wall" and its surrounding parts and the point of abutment of the seamer during the seaming process. The portion of the can lid referred to as the seamer wall 132 in the No. pct/US00/42561 application generally corresponds to the portion referred to as the arcuate portion 132 in the present invention, although the radius of curvature of the two arcuate portions is different. Because the seamer 144 of the present invention does not abut or engage the arcuate portion 132 as the seamer 44 does in the prior application abut the seamer wall 132, the arcuate portion is not referred to as a "seamer wall". The point of abutment of the seamer of the present invention will be apparent from the detailed description of the drawings that follow.

The applicant notes that the step 34 in the No. pct/US00/42561 application corresponds to the step 134 described herein, the radius of curvature of both portions being the same. The transition 36 of No. pct/US00/42561 application is in the present invention formed of two separate parts generally corresponding to the first transition 136 and the second transition 137. As described below, the first transition 136 is oblique to the central axis, and the second transition 137 has a radius of curvature that is substantially the same as that of the transition 36 of the prior application. Finally, the circumferential bead 38 of the No. pct/US00/42561 application generally corresponds to the circumferential bead 138 of the present invention, with the radius of curvature of the two portions being approximately the same.

The applicant believes that the above clearly illustrates the difference in terms used to describe the various parts of the invention from the related application No. pct/US 00/42561. The details of the development of the present invention in the design of seamers and can ends, and particularly the engagement point between the seamer and the can end during seam formation, are described in detail below with reference to the drawings.

Figure 1 is a cross-sectional view of a portion of a can lid 110 illustrating a presently preferred embodiment of the invention. The can lid 110 is preferably formed from sheet metal of aluminum. An aluminum alloy such as aluminum alloy 5182 is generally used. The sheet metal typically has a thickness of about 0.007 to 0.010 inches, preferably about 0.0075 to 0.0088 inches, and most preferably about 0.0078 to 0.0083 inches. The metal sheet may be coated with a plating layer (not shown) on at least one surface. The coating is typically located on the surface of the metal sheet that serves as the can inner surface. Methods of making can lids having the same structure and geometry as can lid 110 described herein are well known.

The can lid 110 has a center panel 112. The center plate 112 is generally circular, but may be non-circular. The diameter d1 of the center panel 112 may be about 1.4-2.0 inches, preferably about 1.6-1.8 inches, more preferably about 1.65-1.75 inches, and still more preferably 1.69 inches. Although the central panel 112 is shown as being planar, it may be ridged and not limited to the planar shape shown. The center panel 112 has a central axis 114 that is perpendicular to the diameter d2 of the outer edge or circumferential bead 138 of the can lid 110. The diameter d2 is about 2.25-2.50 inches, preferably 2.34 inches. The diameter d1 of the central plate 112 is preferably less than 80% of the outer diameter d 2.

An annular countersink 116 formed by spaced apart inner and outer walls 120, 128 extending radially outwardly from an arcuate bottom 124 surrounds the center panel. The inner and outer walls 120, 128 are generally flat and may be parallel to each other and to the central axis 114, but one or both walls may open at an angle of up to about 15. An annular countersink 116 extends radially downward from the center panel 112 along the top edge of the inner wall 120. The radius of curvature r1 of connecting arcs 118 extending radially inward from inner wall 120 toward center panel 112 is about 0.013 inches to about 0.017 inches, preferably about 0.014 inches to about 0.016 inches, more preferably about 0.01475 inches to about 0.01525 inches, and even more preferably about 0.015 inches. The bottom 124 preferably has a radius of curvature r 2. The radius of curvature r2 is about 0.030-0.060 inches, preferably about 0.035-0.05 inches, and most preferably about 0.038 inches. The center of the radius of curvature r2 is located below the profile of the can lid 110. The annular countersink 116 has a height h1 of about 0.03-0.115 inches, more preferably about 0.05-0.095 inches, and most preferably about 0.06-0.085 inches. The bottom 124 of the annular countersink 116 may also be formed with different inner and outer radii extending radially outward from a straight portion.

The outer wall 128 includes a second seamer abutment 228 that is one of two points of abutment of the seamer with the interior of the can lid 110 during the seaming operation. An arcuate portion 132 extends radially outwardly from outer wall 128 through a connecting arc 130 having a radius of curvature r4 of about 0.03-0.07 inches, preferably about 0.035-0.06 inches, more preferably about 0.0375-0.05 inches, and even more preferably about 0.04 inches. The center of the radius of curvature r4 is located below the plane of the can lid 110. The illustrated arcuate portion 132 has a radius of curvature r5 of about 0.100-0.300 inches, preferably about 0.160-0.220 inches, and most preferably about 0.180-0.200 inches. In the present invention, the radius of curvature r5 is 0.0187 inches. The center of the radius of curvature r5 is located below the plane of the can lid 110. The arc portion 132 is configured as: a line passing through the innermost end of the arcuate portion 132 at the terminal end of the connecting arc 130 and the outermost end of the arcuate portion 132 at the beginning of the step portion 134 makes an acute angle with the central axis 114 of the central plate 112. The acute angle is about 20-80 °, preferably about 35-65 °, and most preferably about 45-55 °. In the present invention, the acute angle is about 50 °.

A step portion 134 extends radially outwardly from the arcuate portion 132. The step 134 is preferably arcuate with a radius of curvature r6 of about 0.02-0.06 inches, preferably about 0.025-0.055 inches, more preferably about 0.03-0.05 inches, and even more preferably about 0.035-0.045 inches. In the present invention, the radius of curvature r6 is 0.040 inch. The center of the radius of curvature r6 is located above the profile of the can lid 110.

A first transition 136 extends radially upward and slightly outward from the step 134. The first transition 136 is at an angle a1 with respect to the central axis 114 of the central panel 112. Angle a1 is about 4-12 °, preferably about 5-7 °, and most preferably about 6 °. As shown in fig. 3, the angle a1 should be slightly larger than the angle a2 of the intersection of the drive face 146 of the seamer 144 and the central axis 114 of the central panel 112. The difference between angle a1 and angle a2 is no greater than about 4 ° and at least about 0.5 °, preferably at least about 1 ° and no greater than about 3 °, and most preferably about 2 °. To facilitate removal of the can from the seamer 144 after the seam is formed, the angle a2 is preferably at least about 2 °, but is preferably no greater than about 8 °. In the present invention, the angle a2 is about 4 °.

The second transition 137 extends radially outward from the first transition 136. The radius of curvature r7 of the second transition 137 is about 0.04-0.09 inches, more preferably about 0.045-0.08 inches, and most preferably about 0.05-0.065 inches. A circumferential bead 138 extends radially outwardly from the second transition 137. The height h2 of the circumferential bead 138 is about 0.04-0.09 inches, preferably about 0.0475-0.0825 inches, more preferably about 0.065-0.0825 inches, and even more preferably about 0.075-0.0825 inches. In the present invention, height h2 is 0.078 inches.

Fig. 2 shows that the overall height h6 of first transition 136 and second transition 137 is about 0.105 inches in the present invention. This height is slightly greater than the height of the double seam being made, which in the present invention is about 0.096-0.100 inches. The height of the double seam of the small seam can is about 0.068-0.080 inches and the height h6 of the first and second transitions 136, 137 is about 0.082 inches. The height of the double seam of the micro-seamed can is about 0.050-0.055 inches and the height h6 of the first transition 136 and the second transition 137 is about 0.060 inches. The higher height h6 provides an area at the bottom of the double seam that creates a high pressure ridge of the resulting seam, thereby sealing the resulting seam against leakage.

Figure 3 illustrates the can lid 110 positioned on the can body 140, and in particular, on the rim 142 of the can body 140. The radius of the flange 142 is slightly less than the second transition radius r 7. Because the flange radius is very close to the second transition radius, the can lid is easily centered on the can body to form the seam. The body neck inside diameter d3 is about 2.051-2.065 inches with a target diameter of about 2.058 inches. The can body 140 is supported by a bottom plate 145 (not shown) which is mounted for rotation about the axis 114 with a seamer 144. The seamer 144 includes an upper drive surface 146 that surface mates with and engages the step 134. As shown in fig. 8, the upper drive surface 146 is formed by a frustoconical upper portion 146a having an angle a2 and an arcuate lower portion 146b having a radius that engages the step 134 having a radius r 6. The seamer 144 further includes a lower drive surface 148 that mates with and engages the second seamer abutment 228 of the annular countersink 116. The depression 232 of the seamer 144 extends between the drive surfaces 146 and 148 without abutting or deforming the arcuate portion 132 of the can lid 110. The gap between the recessed portion 232 and the arcuate portion 132 shown in fig. 3 is not critical and is not shown to scale. In addition, the angle a1 of the first transition 136 to the central axis 114 of the central panel 112 of about 6 ° matches the two drive points of the seamer, the step 134 and the second seamer abutment 228, to align the seamer 144 with the can lid 110. The defined clamping force between the seamer 144 and the bottom panel 145 (not shown) generates a frictional force between the seamer 144 and the step portion 134 and the second seamer abutment 228 sufficient to rotate the can lid 110 and the can body 140. Since the seamer 144 drives the can lid over the two-point step portion 134 and the second seamer abutment 228, the clamp force to prevent the can lid from slipping during seam formation is reduced to about 70-140 pounds. Due to this reduction in the clamping force, the possibility of damage to the can body side wall during seam formation is reduced. The driving surface 146 of the seamer 144 is at an angle a2 of about 4 deg. to the central axis 114 of the center plate 112. Because of this angle, the can be removed from the seamer 144 after the seam is formed.

Figure 4 illustrates an initial stage in the formation of a double seam between the can lid 110 and can body 140. The roller 150 abuts the circumferential bead 138 and the seamer 144 applies a centering force. The can seamer 144 uses the upper drive surface 146 and the lower drive surface 148 to drive the rotation of the can lid 110 and the can body 140, and the resulting rolling, pinching action deforms the second transition portion 137, the circumferential bead portion 138, and the flange 142 into the intermediate circumferential seam 152. The step 134 supports the second transition 137 against the upper drive surface 146 and the circumferential bead 138 guides bead deformation against the roller 150. Note that the first transition 136 rarely moves during seam formation because its angle is nearly the same as the angle of the drive face 146 on the seamer 144. When the roller 150 presses against the circumferential bead 138, the second transition 137 presses against the seamer 144, further enhancing the drive to the can lid 110. The positive support and guidance thus serve together to stably and reliably create the intermediate circumferential seam 152.

Figure 5 illustrates the final stage of forming a double seam between the can lid 110 and can body 140. At this point, the roller 150 presses against the intermediate circumferential seam 152 supported by the seamer 144. The seamer 144 rotates the can lid 110 and can body 140 so that the pressure of the roller 150 flattens the intermediate circumferential seam 152 to the top 148 of the seamer 144, creating a double seam 154. The top 148 of the seamer 144 has a draw angle to facilitate removal of the can lid 110 after the operation.

Figure 6 illustrates how a plurality of can lids 110a and 110b can be stacked together for ease of shipping, packaging and feeding a seam forming machine. The bottom surface of the peripheral curl portion 138a abuts the top of the peripheral curl portion 138b of the adjacent can lid 110 b. The can end 110a is supported and separated from the can end 110b by a height h3, which is h3 sufficient to accommodate the thickness of a tab (not shown). In this manner, the can lid 110 can be more compactly and efficiently transported, facilitating the mechanical handling of the can lid in an automated feed hopper for seam making.

Fig. 7 shows how beverage cans 164a packaged in accordance with the present invention can be stacked on an identical beverage can 164 b. Bead 166a abuts double seam 154 b.

Fig. 8 shows in detail the frustoconical upper portion 146a and the arcuate lower portion 146b of the drive surface 146 on the seamer 144 shown in fig. 3.

The embodiments described above are exemplary. Many details are well known and therefore many of these details are neither shown nor described. It is not required that all of the details, components, elements, or steps described herein be novel. While the drawings and specification illustrate the many features and advantages of the invention, the description is illustrative only, and changes may be made in detail, especially in matters of structure, shape and size of the parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

The above description of specific embodiments and the accompanying drawings do not indicate how this patent is infringed upon, but rather provide at least one explanation of how the invention can be used and made. The scope of the invention and the patent protection scope are defined by the following claims.

Claims (16)

1. A can end for a can body, comprising:

a central panel having a central axis perpendicular to the diameter of the outer rim of the can lid;

an annular countersink portion extending radially outwardly from said center panel;

an arcuate portion extending radially outwardly from said annular countersink, having a radius of no more than 12.7mm and a center point below the can lid surface, wherein a line passing through the ends of said arcuate portion makes an angle of 20-80 ° with said central axis of said center panel;

a step portion extending radially outwardly from said arcuate portion, the step portion having a radius of at least 0.254mm and a center above the can lid surface;

a first transition portion extending radially outwardly from said step portion, said first transition portion being generally frustoconical and intersecting said central axis at an angle of at least 4 ° but no greater than 12 °;

a second transition portion extending radially outwardly from said first transition portion, the second transition portion having a radius of at least 0.508mm and a center located below the surface of the can lid; and

a circumferential bead extending radially outwardly from the second transition portion.

2. The can lid according to claim 1 wherein a line passing through the ends of said arcuate portion is angled from 35 ° to 65 ° relative to said central axis of the central panel.

3. The can lid according to claim 1 wherein a line passing through the ends of said arcuate portion is oriented at an angle of 45-55 ° with respect to said central axis of the central panel.

4. The can lid according to claim 1 wherein said peripheral curl portion has a height of 1.016 to 2.286 mm.

5. The can lid according to claim 1 wherein said central panel is planar.

6. The can lid according to claim 1 wherein said center panel is arcuate.

7. The can lid according to claim 1 wherein said center panel has a diameter of from 35.56 mm to 50.8 mm.

8. The can lid according to claim 1 wherein said annular countersink has a height of from 0.762 to 3.01 mm.

9. The can lid according to claim 1 wherein said arcuate portion has a radius of curvature of from 2.54 mm to 7.62mm, the center of said radius being located below the surface of said can lid.

10. The can lid according to claim 1 wherein said step portion has a radius of curvature of from 0.508 to 1.542mm, the center of said radius being located above the surface of said can lid.

11. The can lid according to claim 1 wherein said first transition portion is inclined at an angle of from 5 ° to 7 ° relative to said central axis.

12. The can lid according to claim 1 wherein said first transition portion is inclined at an angle of 6 ° to said central axis.

13. The can lid according to claim 1 wherein said peripheral curl portion has a radius of curvature of from 0.508 to 1.542mm, the center of said radius being located above the surface of said can lid.

14. A method of forming a double seam joining a can body and a can lid, the can lid comprising: a central panel having a central axis perpendicular to the diameter of the outer rim of the can lid; an annular countersink portion extending radially outwardly from said center panel; an arcuate portion extending radially outwardly from said annular countersink, wherein a line passing through both ends of said arcuate portion makes an angle of 20-80 ° with said central axis of said center panel; a step portion extending radially outwardly from said arcuate portion; a first transition portion extending radially outward from the step portion; a second transition portion extending radially outwardly from the first transition portion to a circumferential bead, the can body having a flange, the method comprising the steps of:

supporting the can body on a floor;

placing the can lid on the can body such that the second transition portion abuts the can body flange;

providing a seamer having a lower portion, a recessed portion and an upper portion, the upper portion of the seamer having a frustoconical portion and a driving surface against a stepped portion of the can lid, the recessed portion of the seamer not deforming said arcuate portion of said can lid during seam formation, the lower portion of the seamer abutting a surface of said annular countersink on a seamer abutment when the seamer is engaged with the can lid;

engaging the can cover with the can seamer;

rotating the can and can lid assembly using a can seamer;

rolling the circumferential bead and can body flange together to form an intermediate circumferential seam; and

the intermediate circumferential seam is pressed against the upper portion of the seamer to form a double seam.

15. The method of claim 14 wherein said frustoconical portion of said upper portion of said seamer is inclined at an angle of-4 ° to said central axis.

16. A method as set forth in claim 14 wherein said frustoconical portion of said upper portion of said seamer is inclined at an angle of greater than 2 ° to said central axis, said angle being no greater than 3 ° less than the angle formed by said first transition portion of said can lid and said central axis of said center panel.