CN1524049A - Can shells and double-crimped can ends - Google Patents

Abstract

A drawn aluminum can shell has a peripheral crown which is double-seamed with an end portion of an aluminum can body to provide a can end having a generally flat center panel connected by a curved panel wall to an inner wall of an annular U-shaped countersink. The countersink has a generally cylindrical outer wall and an inner width less than the radius of the panel wall. The outer wall of the countersink connects with a frusto-conical chuckwall at a junction below the center panel, and the chuckwall extends to an inner wall of the crown at an angle of at least 16 DEG with the center axis. In one embodiment, the chuckwall has an intermediate generally vertical riser portion with small radii, the inner bottom width of the countersink is less than 0.040 inch.

Description

Can shells and double-crimped can ends

technical field

The present invention relates to the shape and construction of sheet metal/aluminum can shells and can ends having a peripheral edge or ridge which is double beaded to the upper edge portion of a sheet metal or aluminum can body.

Background technique

Such can ends are formed from drawn sheet metal can shells, such as those made by the tooling disclosed in US Patent No. 5,857,374 to the applicant. Typically, shaped tank shells comprise a circular central plate which extends to a wall which extends to or also forms stiffening ribs or the inner wall of a countersink having a U-shaped cross-sectional configuration. The counterbore is connected by a frusto-conical collet wall to a peripheral crimped annular ridge. For beverage containers, the shell center panel is usually provided with an E-Z opening, and after the can is filled with beverage, the peripheral crimping ridge of the shell is double seamed to the upper end portion of the can.

When the can body is filled with a carbonated beverage or a pasteurized beverage, the can end must have sufficient crimp strength to withstand the pressurized beverage, eg, a crimp strength of at least 90 psi. Such resistance to "crumple" and "rock" pressures is described in detail in US Patent No. 4,448,322, which is incorporated herein by reference in its entirety. It is also desirable to minimize the weight of sheet metal or aluminum within the can end without reducing bending strength. This may be achieved by reducing the thickness or gauge of the flat sheet metal that is drawn to form the shell, and/or by reducing the diameter of the circular blanks that are cut from the sheet metal to form the shell.

There have been many sheet metal tank shells and tank ends constructed and proposed for increasing the bending strength of the tank end and/or reducing the weight of the sheet metal within the tank end without reducing the bending strength. For example, U.S. Patent No. 3,843,014, No. 4,031,837, No. 4,093,102, the aforementioned Nos. 6,089,072 and No. 6,102,243 disclose various shapes and configurations of tank shells and ends, and various sizes and configurations suggested or used to increase the bending strength of the end and/or reduce the metal inside the end. Furthermore, Published PCT Application No. WO98/34743 discloses a variation of the tank shell and tank ends disclosed in the above-mentioned Patent No. 6,065,634. In addition to increasing the can end bend strength/weight ratio, it is also desirable to form the can shell so that the tools available in the art for adding E-Z openers to the can shell and for double seaming the can shell to the can body require minimal improvement. While some of the tank shells and can ends disclosed in the aforementioned patents provide some desirable structural features, none of the patents provide all of them.

Contents of the invention

The present invention relates to an improved sheet metal can shell and can end, and a method of forming a can end, which provide the above-mentioned desirable features and advantages, including a substantial reduction in the diameter of the blank from which the shell is formed, and the resulting can Significant increase in the strength-to-weight ratio of the end. Can shells and can ends formed in accordance with the present invention not only increase the bending strength of the can ends, but also outperform existing tools in the art for adding E-Z openings to shells and for double seaming the shell to the body changes or changes are minimized.

According to one embodiment of the invention, the shell and end are formed such that the overall height between the ridge and the counterbore is less than 0.240 inches, preferably less than 0.230 inches, and the counterbore has a generally cylindrical outer wall and inner wall. The generally frusto-conical collet wall extends from the counterbore outer wall to the raised inner wall and has an upper wall portion extending at an angle of at least 16°, preferably between 25° and between 30°. The countersink may have a generally flat bottom wall connected to the countersink outer wall by a small radius substantially smaller than the width of the radius of the bottom wall, the inner width of the countersink at its bottom being smaller than the radius of the plate wall.

According to a variant of the invention, the tank shell and the tank end have some of the above-mentioned structures and incorporate the lower part of the collet wall and the outer wall of the counterbore substantially below the level of the center plate. The countersink lower wall portion extends at an angle of less than 16° relative to the central axis and is connected to the countersink upper wall portion by a substantially vertical short rise forming a jump and a sharpened radius. The radius of curvature of the countersink is substantially smaller than the radius of curvature of the curved panel wall, and the interior width at the bottom of the countersink is also smaller than the radius of the panel wall, preferably less than 0.030 inches.

Other features and advantages of the invention will be apparent from the following description, drawings and appended claims.

Description of drawings

Figure 1 is a vertical cross-sectional view of a sheet metal tank shell formed in accordance with the present invention;

Figure 2 is a partially enlarged cross-sectional view of the tank shell in Figure 1, showing the structure of an embodiment;

Figure 3 is a smaller partial cross-sectional view of the shell of Figure 2 showing the shell being formed into a can end using double seaming chucks and a first stage roller press;

Fig. 4 is a partial cross-sectional view similar to Fig. 3, showing a double seamed can end utilizing collets and a second stage roller;

Figure 5 is an enlarged fragmentary cross-sectional view of the double seamed can end shown in Figure 4, with a portion of the improved double seamed chuck;

Figure 6 is a cross-sectional view similar to Figure 1 showing a double seamed can end formed in accordance with the present invention;

Figure 7 is an enlarged fragmentary sectional view similar to Figure 2, showing a modified tank shell according to the present invention; and

Figure 8 is an enlarged fragmentary sectional view similar to Figure 5, showing the double seaming of the can shell of Figure 7 to a can body.

Detailed ways

Figure 1 shows a unitary tank shell 10 formed from a generally circular blank of sheet metal or aluminum, preferably about 0.0085 inches thick, and about 2.705 inches in diameter. The tank shell 10 has a central axis 11 and includes a slightly raised central plate 12 having an annular portion 14 extending to a curved plate wall 16 . Central wall portion 14 and wall 16 may be formed from a series of mixed curved walls having radii of 1.489 inches for R1, 0.321 inches for R2, 0.031 inches for R3, and 0.055 inches for R4, respectively. The bottom inside diameter D1 of the curved wall 16 is about 1.855 inches.

A curved panel wall 16 of radius R4 extends from the inner wall 17 of a stiffener or countersink 18 having a U-shaped cross-sectional configuration and comprising a flat annular bottom wall 22 and a generally cylindrical outer wall 24, The inner diameter D2 of the outer wall is, for example, about 1.957 inches. The flat bottom wall 22 of the countersink 18 is connected to the inner panel wall 16 and the outer countersink wall 24 by radiused walls 26, each radiused wall having an inner diameter R5 of approximately 0.010 inches. The radial width W of the flat bottom wall 22 is preferably about 0.022 inches, so that the inner bottom width W1 of the counterbore 18 is about 0.042 inches.

The outer wall 24 of the counterbore 18 is connected to a generally frusto-conical collet wall 32 by a curved wall 34 having a radius R6 of about 0.054 inches. The clamping wall 32 extends such that the angle A1 relative to the central axis 11 or a vertical reference line 36 parallel to the central axis 11 of the tank shell is at least 16°. Preferably the angle A1 is between 25° and 30° and close to 29°. The upper end of the collet wall 32 is connected to the bottom of the curved inner wall 38 of the circular protrusion 42 having a curled outer wall 44 . The radius R7 of the inner wall 38 of the ridge 42 is preferably about 0.070 inches, the inner diameter D3 at the bottom of the curved inner wall 38 is preferably about 2.039 inches, and the outer diameter D4 of the curled outer wall 44 is preferably about 2.340 inches. The height C of the curled outer wall 44 is in the range of 0.075 inches to 0.095 inches, and is preferably about 0.079 inches. Depth D from the bottom of crimped outer wall 44 or the junction 46 of collet wall 32 and raised inner wall 38 to the inner surface of countersunk bottom wall 22 is in the range of 0.108 inches to 0.148 inches, preferably about 0.126 inches. The depth G of the junction 47 or the center point of the radius R6 from the junction 46 or the bottom of the curled outer wall 44 of the protuberance 42 is about 0.079 inches.

FIG. 3 shows that the ridge 42 of the can shell 10 is doubly crimped to the peripheral end 48 above the sheet metal or aluminum sheet can body 50 . The double seaming operation is carried out between rotating double seaming circular chucks 55 which engage the tank shell 10 and have an outer surface 58 which is relative to the central axis of the chucks 55 and the direction of the tank shell 10. The common central axis 11 is slightly inclined at an angle between 0° and 10°. Preferably, the surface 58 has a slight taper of about 4°, and in response to the radially inward movement of the first stage double seaming roller 60, the inner wall 38 of the ridge 42 engages the surface 58 while the can body 50 and all its contents The contents and shell 10 rotate together with the chuck 55 . The collet 55 also has a frustoconical surface 62 which matches and engages the frustoconical collet wall 32 of the tank shell 10, and the downwardly projecting annular flange portion 64 of the collet 55 extends into the counterbore. 18, and has a bottom surface 66 (FIG. 5) and a cylindrical outer surface 68 that engage the bottom wall 22 and outer wall 24 of the counterbore 18, respectively.

Figures 4 and 5 illustrate the completion of the double hemming operation to form the double hemming ridge 70 between the rotary chuck 55 and the second stage double hemming roller 72, which is also moved radially inward , while the collet 55, shell 10, and body 50 are rotated to transform the shell 10 into a can end 75, which is effectively connected and sealed to the upper end 48 of the can body 50. The double seamed edge or ridge 70 has an inner wall 74 formed by the inner wall 38 of the shell ridge 42 and also has an outer wall 76 formed by the shell ridge 42 which includes a curled outer wall 44 . The height H2 of the double bead ridge 70 ranges between 0.090 inches and 0.110 inches, and is preferably about 0.100 inches. Can end 75 is located at an overall height H1 between the top of ridge 70 and the bottom of counterbore 18 in a range between 0.170 inches and 0.240 inches, and preferably about 0.235 inches. Since the can end 75 has the same cross-sectional structure as the can shell 10 except for the double bead 70, the same common reference numerals are used for common structures in FIGS. 4-6.

As shown in FIG. 6 , the central portion of the center plate 12 defines a plane 80 that generally intersects the junction 46 of the collet wall 32 with the inner wall 74 of the double bead ridge 70 . For purposes of clarity and simplicity, the E-Z opening is omitted in Figure 6, as the E-Z opening does not form part of the present invention.

Figures 7 and 8 illustrate another embodiment or variation of the invention comprising a can shell (Figure 7) and a double crimped can end (Figure 8). Accordingly, structural parts corresponding to those described above with reference to Figures 1-6 have the same reference numerals except for the addition of a prime. Referring thus to Figure 7, the tank shell 10' has a central axis identical to the central axis 11 and comprises a circular central panel 12' connected to a peripheral curved panel wall 16' connected to a U-shaped cross-sectional structure. The sloped inner wall 17' of the counterbore 18'. The counterbore has a generally cylindrical outer wall 24' which extends at an angle of less than 10° and is connected to the collet wall which has a frusto-conical upper wall portion 32' and a slightly curved lower wall portion 34 '. Wall sections 32' and 34' are connected by a short jump or generally vertical rise 35' having relatively sharp inner and outer radii, eg, on the order of 0.02 inches. The upper chuck wall portion 32' is connected by a curved wall 37' to an inner curved wall 38' having a ridge 42' of a curled outer wall 44'.

The inner wall 38' of the protrusion 42' is connected to the upper chuck wall portion 32' at a junction 46', and the outer wall 24' of the counterbore 18' is connected to the lower chuck wall portion 34' at a junction 47'. The vertical height G1 from the bottom of the counterbore 18' to the jump or raised portion 35' is about 0.086 inches. Radius R10 is about 0.051 inches, and lower wall portion 34' extends at angle A3 of about 15°. The radius R9 of the counterbore 18' is approximately 0.009 inches to 0.011 inches. Other approximate dimensions and angles of the tank shell 10' shown in Figure 7 are as follows:

C1 0.082 inches W1 0.024 inches

C2 0.153 inches W2 0.063 inches H5 0.078 inches

D6 1.910 inches W3 0.034 inches H6 0.149 inches

D7 2.036 inches A2 29°

D8 2.337 inches A3 15°

D9 1.731 inches A4 16° A6 13°

It has been found that the particular cross-sectional configuration of the tank shell 10' provides performance results superior to those provided by the tank shell 10. Accordingly, the structural details of the tank shell 10' include the upper wall portion 32' of the chuck wall, the angle A2 of which relative to the central axis is at least 16° and preferably in the range of 25° to 30°. The chuck wall lower wall portion 34' forms an angle A3 of approximately 15°. The inner wall 38' of the protuberance 42' forms an angle A4 preferably in the range between 5° and 30°, and preferably about 16°. The inner wall 17' of the countersink 18' forms an angle A6 of greater than 10° and approximately 13°. The bottom width W1 of the counterbore between the inner wall 17' and the outer wall 24' is less than 0.040 inches, and preferably about 0.024 inches. The radius R8 of the curved inner panel wall 16' is substantially greater than the width W1 of the counterbore 18' and is approximately 0.049 inches.

The bulge 42' of the tank shell 10' has a height C1 and a height C2, C1 being in the range between 0.075 inches and 0.095 inches, and preferably about 0.082 inches, and C2 being in the range between 0.120 inches and 0.170 inches within, and preferably about 0.153 inches. The overall diameter D8 of the shell 10' is about 2.337 inches and the diameter D7 to the joint 46' is about 2.036 inches. The inner bottom diameter D6 of the countersink outer wall 24' is about 1.910 inches, and the difference W2 between D7 and D6 is greater than the countersink width W1, or about 0.063 inches. Diameter D9 at the center of radius R8 is approximately 1.731 inches. It should be understood that if a tank shell of a different diameter is desired, the diameters D6-D9 may vary proportionally. The height H5 of the center plate 12' from the bottom of the counterbore 18' is in the range of 0.070 inches to 0.110 inches, and is preferably about 0.078 inches. The height H6 of the shell 10' between the top of the center panel 12' and the top of the hump 42' is in the range of 0.125 inches to 0.185 inches, and is preferably about 0.149 inches.

Referring to Fig. 8, the can shell 10' and the upper end 48' of the formed can body 50' are double seamed to form the can end 75' using substantially the same tooling as described above with reference to Figs. 3-5. That is, a seamer chuck (not shown) similar to chuck 55 includes a lower portion like portion 64 that extends into counterbore 18' and has a surface 58, 62 that is compatible with seamer chuck 55. , and corresponding surfaces 68 for engaging the counterbore outer wall 24' and the collet wall portion 32' and forming the inner wall 74' of the double bead 70'. As also shown in FIG. 8, the inner wall 74' of the double seam 70' extends at a slight angle A5 of about 4°, and the overall height H3 of the can end 75' is less than 0.24 inches, and preferably about 0.235 inches. The height H4 of the double seam ridge 70' is on the order of 0.100 inches, and the height H7 from the top of the ridge 70' to the top of the center panel 12' is greater than the center panel height H5, preferably about 0.148 inches.

By forming the can shell and can end with the above configuration and dimensions, it was found that the can end was able to withstand an internal can pressure in excess of 110 psi before crimping. The construction of the can end and the shallower profile (so that the overall height is less than 0.24 inches) also enables a significant reduction in the diameter of the round blank used to form the can shell by more than 0.040 inches. This reduction results in a significant reduction in the width of the aluminum sheet or plate used to make the can shells and thus in the weight and cost of the aluminum forming the can ends, which is especially important in view of the large number of can ends produced each year. The tank shell 10 or 10' also minimizes the modification of existing tools in the art for forming the double seam bead 70 or 70'. That is, the only modification required of the tool for forming the double seam ridge is to replace the conventional or standard double seam cartridge with a new type of collet having a frusto-conical mating surface 62 and a generally shaped groove on the bottom 64. The cylindrical surface 68, base 64 extends into the counterbore and engages the counterbore outer wall. Conventional double seaming chucks typically have a slightly sloped surface 58 that extends at an angle of about 4° relative to the central axis of the double seaming chuck.

While the shapes of shells and ends described herein and methods of forming shells and ends constitute preferred embodiments of the invention, it should be understood that the invention is not limited to these precisely shaped shells and ends and may be made without departing from changes within the scope and spirit of the invention as defined in the appended claims.

Claims (17)

1. A sheet metal tank shell having a vertical central axis and a crimped peripheral ridge adapted to be double crimped to the end of a formed sheet metal tank body, said tank shell comprising a Circular central plate to the inner wall of a counterbore having a U-shaped cross-section and an outer wall, a frusto-conical collet wall having a wall portion at an angle greater than 16° with respect to said central axis ° and is connected to the outer wall of the counterbore at a first junction, the protuberance has an inner wall connected to the collet wall at a second junction, the radius of curvature of the counterbore is substantially smaller than the radius of curvature of the curved panel walls, the first joint is spaced below the horizontal plane of the center panel, and the vertical distance between the first joint and the second joint is greater than the countersink The width of the bottom of the countersink between the inner and outer walls of the hole, and the radius of curvature of the curved plate is greater than the width of the countersink. 2. The tank shell of claim 1 wherein the difference in diameter between said inner wall of said bulge and said outer wall of said countersink is substantially greater than said radius of curvature of said countersink. 3. The tank shell of claim 1, wherein said wall portion of said frusto-conical collet wall extends at an angle of between 25° and 30° relative to said central axis. 4. The tank shell of claim 1, wherein said tank shell has an overall height between said ridge and said counterbore of between 0.195 inches and 0.265 inches. 5. The tank shell of claim 1 wherein said counterbore has a generally flat bottom wall and curved inner and outer filleted walls dividing said bottom wall into connected to the inner and outer walls of the counterbore, and each filleted wall has a radius of curvature that is less than the radial width of the bottom wall. 6. The shell of claim 1 in combination with a double seaming chuck having an axis of rotation which is the same as said central axis of said shell, said seaming The collet includes an annular portion extending into said counterbore and having an outer surface engaging said outer wall of said counterbore, said crimping collet having a frusto-conical surface engaging said collet wall , and said crimping chuck has a surface that engages said inner wall of said protrusion. 7. A sheet metal tank shell having a vertical central axis and a crimped peripheral ridge adapted to be double crimped to the end of a formed sheet metal tank body, said tank shell comprising a a circular center plate to the inner wall of a counterbore having an outer wall and U-shaped cross-sectional configuration, a generally frusto-conical collet wall extending from said outer wall of said counterbore and having an angled upper wall portion extending at an angle of at least 16° relative to said central axis, said chuck wall having an angled lower wall portion joined at a junction substantially below the level of said center plate to said outer wall of said countersink, said protrusion having an inner wall connected to said upper wall portion of said collet wall, said countersink having a radius of curvature substantially smaller than the radius of curvature of said curved panel wall, and The width of the bottom of the countersink between the inner and outer walls of the countersink is less than the radius of curvature of the panel wall and less than 0.040 inches. 8. The tank shell of claim 7, wherein the difference in diameter between the inner wall of the bulge and the outer wall of the countersink is greater than the width of the countersink. 9. The tank shell of claim 7, wherein said upper wall portion of said collet wall extends at an angle of at least 25° relative to said central axis. 10. The tank shell of claim 7, wherein a generally vertical short riser wall portion connects said upper and lower wall portions of said collet wall together. 11. A tank shell as claimed in claim 7, wherein said sloping lower wall portion of said collet wall extends at an angle which is less than the angle of said upper wall portion relative to said central axis. angle. 12. The tank shell of claim 7, wherein said angle of said inner wall of said counterbore is inclined such that the angle is between the angle of said inclined lower wall portion of said collet wall and between the angles of the sloped upper wall portion of the collet wall. 13. The tank shell of claim 7, wherein said collet wall is connected to said raised inner wall at a first joint and to said inner wall of said counterbore at a second joint. The outer walls are connected, and the axial distance between the first joint and the second joint is substantially greater than the width of the counterbore. 14. A sheet metal can shell having a vertical central axis and a crimped peripheral ridge adapted to be double crimped to the end of a formed sheet metal can body, said can shell comprising a circular central plate , the circular central plate is connected by a curved plate wall to the inner wall of a counterbore having a U-shaped cross-section, the generally frusto-conical collet wall comprising an angle greater than 16° with respect to said central axis an extended upper wall portion and having a sloped lower wall portion connected to the outer wall of the counterbore at a first junction, the protrusion having an inner wall connected to the outer wall of the collet wall at a second junction said upper wall portion, said countersunk hole having a radius of curvature substantially smaller than that of said curved panel wall, said first junction located below the level of said center panel and spaced apart from said center panel to said countersink The axial distance of the bottom of the hole is less than the axial distance from the center plate to the top of the ridge. 15. The tank shell of claim 14, wherein the difference in diameter between the inner wall of the bulge and the outer wall of the countersink is greater than the width of the countersink. 16. A tank shell as claimed in claim 14, wherein said upper wall portion of said collet wall extends at an angle of at least 25[deg.] relative to said central axis. 17. A tank shell as claimed in claim 14 wherein the radius of curvature of said curved panel wall is substantially greater than said width of said counterbore.

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