US3525455A

US3525455A - Sheet metal container

Info

Publication number: US3525455A
Application number: US387609A
Authority: US
Inventors: William T Saunders
Original assignee: National Steel Corp
Current assignee: National Steel Corp
Priority date: 1964-08-05
Filing date: 1964-08-05
Publication date: 1970-08-25
Anticipated expiration: 1987-08-25

Description

Aug. 25, 1970 w. *r. SAUNDERS SHEET METAL CONTAINER 2 Sheets-Sheet l Filed Aug.

FIGS,

v INVENTOR. WILLIAM T. SAUNDERS ATTORNEYS United States Patent 6;

3,525,455 Patented Aug. 25, 1970 Bee Int. Cl. B65d 7/42 US. Cl. 22067 12 Claims This invention relates to improvements on sheet metal containers particularly of the type in which an end cover is double seamed to the body portion to close and seal the container.

"Conventional sheet metal containers, such as of the type in which food and beverage products are marketed, include a body portion, which may be of cylindrical form, and end covers which are double seamed to the ends of the body member to close and seal the container. The central portion of the end cover is located inwardly with respect to the end of the container and is surrounded by a vertical wall, referred to as the countersink wall, which lies in close-fitting contact with the inside end surface of the body member. The end cover includes an outer portion extending from the countersink wall which is folded over and with an extension of the end wall of the body portion in a double seam which projects radially beyond the body portion and the double sea-m with the countersink wall forming a relatively wide rim at the end of the container. Containers of the foregoing type include inherent structural weakness and, in order to prevent bulging of the end covers and failure of the container by outward buckling of the end cover, in the presence of anticipated internal pressures, the end covers formed of heavy gage material of high tensile strength greatly in excess of the ultimate strength of the material required merely to contain anticipated internal pressures and the end covers are formed to include a circumferential reinforcing bead close to the countersink wall.

It is an object of the present invention to provide a novel sheet metal container of the double seam type which overcomes the foregoing disadvantages.

Another object is to provide a sheet metal container of the double seam type in which the end covers are formed of relatively light plate material and of lower tensile strength as compared to end covers of double seamed sheet metal containers constructed according to the prior art.

Still another object of the present invention is to provide a novel sheet metal container of the double seam type which is capable of containing high internal pressures without bulging of the end covers or failure by outward buckling of the end covers yet permits the container to be opened by piercing or cutting the end cover upon the application of a relatively small force as compared with the force required to open prior double seamed sheet metal containers.

A still further object is to provide a novel sheet metal container of the double seamed type having the foregoing characteristics in which end covers are formed of relatively light plate material of lower tensile strength as compared to the end covers of prior double seamed sheet metal containers and which provides a properly sized rim at the end of the container to permit opening of the container by use of conventional piercing or cutting devices.

Other objects and features of the present invention will appear more fully from the following detailed description considered in connection with the accompanying drawings which disclose several embodiments of the invention. It is to be expressly understood however that the drawings are designed for purposes of illustration only and not as a definition of the limits of the invention, reference for the latter purpose being had to the appended claims.

In the drawings, in which similar reference characters correspond to similar elements throughout the various views:

FIG. 1 is a three-dimensional view of an end of a double seamed sheet metal container according to the prior art illustrating typical failure by outward buckling due to excessive internal pressure;

FIG. 2 is an enlarged view in section taken along the line 2-2 of FIG. 1;

FIG. 3 is a top view in plan of a sheet metal container constructed in accordance with the principles of the present invention;

FIG. 4 is a view in section taken along the line 4--4 of FIG. 3;

FIG. 5 is an enlarged view of one side of the structure shown in FIG. 4;

FIG. 6 is a view in section showing another embodiment of the present invention;

FIGS. 7, 8, 9 and 10 are views in section illustrating successive steps in the forming of an end cover in accord ance with the present invention; and

FIG. 11 illustrates a cover member constructed in accordance with the present invention in position with a body member prior to the double seaming operation.

In FIGS. 1 and 2 of the drawings, there is shown a double seamed sheet metal container constructed in accordance with the prior art including a body member 10, of cylindrical shape, and an end cover 11, the normal shape and position of the end cover 11 being shown in broken lines. The end cover 11 includes a central portion 12 surrounded by a vertical or countersink wall 13 which lies in contact with the inside surface of the body member adjacent its end. The end cover also includes a circumferential reinforcing bead 14 adjacent the countersink wall and an outer portion 15 extending from the countersink wall which is rolled with the end of the body member to form a double seam 16 which projects radially from the body member. The double seam 16 and the countersink wall 13 form a rim 17 at the end of the container.

When pressure exists within the container, there will be a tendency for pressurized gas to enter the interface between the countersink wall 13 and the body member and, if the internal pressure exceeds the restraining force presented by the countersink wall 13 and the outer periphery of the central portion 12, the countersink wall will be forced away from the body member at one region of its periphery and the countersink wall will be deformed and pushed upwardly together with the adjacent outer peripheral part of the central portion, as viewed in the drawing, to the position shown in FIG. 2 resulting in failure of the container due to outward buckling of the end cover. As mentioned above, according to prior practice, end covers are formed of relatively heavy plate of high tensile strength and the reinforcing bead 14 is provided all for the purpose of preventing failures of the foregoing character in the presence of anticipated internal pressures. Containers of the prior construction for marketing other carbonated beverages require end covers to be formed of heavy plate of the same order used for beer containers although a pasteurization process is not involved and although internal pressures due to extremely adverse storage conditions would probably not approach a buckling pressure of about p.s.i.g. However, normal storage conditions for carbonated beverages develop internal pressures up to 70 p.s.i.g. at which pressure the end covers bulge outwardly and it has been determined that, in order to prevent outward bulging at the end covers in the presence of internal pressures of about 70 p.s.i.g., it is necessary that containers of the prior construction possess a buckling pressure of the order of 95 p.s.i.g. The

necessity to form end covers of heavy plate is not only expensive but the containers are difficult to open. In order to overcome this tendency, and also to prevent outward bulging of the end covers when subject to anticipated internal pressures, it has been the practice in the past to form the end covers of heavy plate of high tensile strength and to provide the reinforcing bead 14 adjacent the countersink wall.

Prior to the present invention, double seamed sheet metal containers for beer included end covers formed of heavy plate of from 90 to 107 pounds per base box providing a thickness of from 0.010 to 0.011 inch and possessing a tensile strength up to 100,000 pounds per square inch in order to contain the high internal pressures up to about 83 p.s.i.g. developed during the pasteurization process. In particular, a container of the prior construction having end covers formed of 90 pounds per base box double reduced renitrogenized plate having a tensile strength of 100,000 pounds per square inch possesses a buckling pressure of about 95 p.s.i.g. which is sufficiently above the cyclic internal pressures developed during the pasteurization process to safely permit the use of such container for marketing of beer. Also, the use of heavy plate of high tensile steel presents forming problems and decreases the life of the double seaming equipment.

As mentioned above, it is an object of the present invention to provide a double seamed sheet metal container of novel construction which permits the end covers to be formed of light plate of low tensile strength. The embodiment of the invention shown in FIGS. 3, 4 and 5 of the drawings comprises a sheet metal container including a body member of cylindrical shape and a circular end cover 26 joined to an end of the body member by a double searn 27 projecting radially beyond the body member; it is understood the other end of the container may be provided with an end cover of similar construction. The end cover 26 includes a central raised portion 28 merging into a depressed outer annular portion 29 which is joined to a vertical countersink wall portion 30, the countersink wall portion projecting longitudinally of the container beyond the central raised portion 28 to provide a recess for receiving a chuck during the double seaming operation in accordance with conventional practice. The end cover 26 further includes an outer portion 31 extending from the countersink wall portion and terminating in a cover hook 32 of the double seam 27 in double seamed relation with a body hook 33 formed at the end of the body member. In accordance with the present invention, the material of the end cover 26 is of uniform thickness and improved resistance against outward bulging of the end cover and failure of the container by outward buckling of the end cover is obtained by forming the countersink wall portion 30 to include an odd number of folds of the end cover material greater than one, preferably three folds. As shown in FIG. 5, the countersink wall includes an inside fold 35 extending from the annular portion 29 and overlying the inner surface 36 of the body member, and intermediate fold 37 extending from the outer end of the inner fold at shoulder 38 and overlying the inner fold 35, and an outer fold 39 extending from the inner end of the intermediate fold at shoulder 40 and overlying the intermediate fold and merging into the outer portion 31. The

folds

35, 37 and 39 are closely pressed together and form a countersink wall of a thickness a number of times greater than the thickness of the material forming the end cover equal to the number of folds and, as described below, the multifold countersink wall is formed in the end cover prior to joining and sealing the end cover to the body member and the double seaming operation is performed in a conventional manner.

The feature of merging the inner fold 35 from. the annular portion 29 of the end cover and of successively forming the remaining folds inwardly of the container presents but one interface between the body member and the countersink wall and inward lateral movement of the countersink wall due to the action of pressurized gas tending to enter the interface is resisted by a thickness of metal equal to three times the thickness of the material from which the end cover is formed. In addition, the improved rigidity of the countersink wall resulting from at least three folds resists deformation of the central portion of the end cover from its normal position and prevents outward bulging of the end cover When subject to anticipated internal pressures notwithstanding the end cover being formed of light plate. Furthermore, the high rigidity of the multi-fold countersink wall makes it possible to form the end cover with the central portion under tension to further increase the resistance to outward bulging of the end cover.

As discussed above, the end cover of conventional double seamed sheet metal containers, although formed of heavy plate of high tensile strength, is provided with the reinforcing head 14, as shown in FIGS. 1 and 2, to aid in resisting outward buckling of the end cover in the presence of anticipated internal pressures. When practicing the present invention, such a reinforcing bead is unnecessary and, as shown in FIGS. 4 and 5, the end cover includes a central raised portion or plateau 28 and a depressed annular portion 29* merging with the inner fold of the countersink wall. This feature is of particular importance with end covers formed of light plate of 65 to pounds per base box which becomes practicable by the present invention since, with such light plate, there would be a tendency of localized buckling in a reinforcing bead of the type shown in FIGS. 1 and 2.

The embodiment of the invention shown in FIG. 6 of the drawings. includes a modified form of multi-fold countersink wall which increases further resistance to outward buckling due to internal pressure. As shown, the innermost end of the countersink wall tapers inwardly toward the central longitudinal axis of the container and terminates in a conical portion 45. In this construction, the intermediate fold 37 overlies at least the curved portion 46 of the end cover between the annular portion 29 and the inner fold 35, and the outer fold 39 is similarly curved at its innermost end and overlies the intermediate fold. It will be appreciated that with this structure there is provided additional metal resisting inward lateral movement of the inner fold 3 5.

End covers including a multi-fold countersink wall may be formed by relatively simple die operations as shown in FIGS. 7, 8, 9, 10, and 11 which are views in cross section of one side of the end cover during various phases of its formation. FIG. 7 shows what may be referred to as the starting blank 50 which may be formed by a simple pressing operation. The blank 50 includes the central raised portion 28 and a double seaming portion 51 joined by a slightly outwardly inclined portion 52 and an inverted generally U-shaped portion 53. The first die forming step is illustrated in FIG. 8 wherein the portion 52 is being collapsed outwardly beneath the portion 53 and the latter portion is being collapsed downwardly to initiate formation of folds .35, 37 and 39. In FIG. 9, the folds are shown squeezed together and FIG. 10 illustrates positioning of the squeezed folds to provide a countersink wall in proper relationship with the other portions of the end cover as illustrated in FIG; 11. During the phase of FIG. 10, the central portion 28 may be placed under tension, if desired. FIG. 11 also illustrates the body member 25 terminating in a double seaming flange 55 and positioned relative to the end cover prior to the double seaming operation.

As discussed above, conventional sheet metal containers for use in packing beer include end covers formed of heavy plate of from to 107 pounds per base box which are of thickness of 0.010 to 0.011 inch. On the other hand, by practicing the present invention, end covers for beer containers may be formed of relatively light plate such as of from 70 to 75 pounds per base box, which are of a thickness of 0.0076 to 0.0082 inch providing a total countersink wall thickness of 0.0228 to 0.0246 inch which is more than twice the thickness of the countersink wall of prior double seamed sheet metal containers having end covers formed of heavy plate of from 90 to 107 pounds per base box. As a further example of the advantages obtained by the present invention, a double seamed container of prior construction including end covers of conventional continuously annealed steel of 65 pound per base box plate was tested and found to fail by outward buckling under an internal pressure of 30 to 35 p.s.i.g., while a container formed of the same material and constructed according to the present invention possesses a buckling pressure of greater than 70 p.s.i.g. Containers 'of the latter type are suitable for and have been used to market carbonated beverages without bulging of the end covers although light plate is used to form the ends covers and the buckling pressure is less than what would be required with the prior construction to present end cover bulging. Double seamed sheet metal containers constructed in accordance with the present invention with end covers constructed of conventional continuously annealed steel having a tensile strength of about 60,000 pounds per square inch have been tested and found to possess a buckling pressure of about 92 p.s.i.g. when formed of 70 pound per base box plate and a buckling pressure of about 110 p.s.i.g. when formed of 75 pound per base box plate, both with the requirements for beer containers. To illustrate the improvement obtained by the present invention, containers constructed according to prior practices employing the same steel were tested and found to have a buckling pressure of 42 p.s.i.g. for 70 pound per base box plate and 49.5 p.s.i.g. for 75 pound per base box plate.

While the present invention has particular application to double seamed sheet metal containers used to market beer or carbonated beverages or other goods involving the existence of substantial internal pressures, the novel feature of a multi-fold countersink wall structure obtains additional advantages (Whether the container be pres- SUIlZBd or not. The formation of end covers of light plate from 75 pounds per base box and below greatly decreases to an insignificant force the pressure required to open the container by pierce or wheel type openers. The opening force surprisingly decreases at a rate substantially greater than the decrease in plate thickness and the ability to employ light plate for end covers renders opening of the container a simple, painless task requiring insignificant effort. For example, end covers of prior type containers for beer and other carbonated beverages are required to be formed from heavy plate of 90 pounds per base box or greater, and the force required for plate of the latter weight is about 11 pounds. On the other hand, the opening force required for end covers formed from light plate of 75 pounds per base box requires about 5 pounds, while about 4 pounds is required to open end covers of 70 pounds per base box plate and about 4 pounds for end covers of 65 pounds per base box plate. By way of contrast, the force required to open soft aluminum can ends by punching is over 9 pounds and the force required to operate a tab-type opener is over 7.5 pounds.

In addition to the foregoing, the principles of the present invention make it possible to employ in sheet metal containers light plate including light-weight tinplate in weights as low as 45 pounds per base box. By way of example, containers for citrus juices could be advantageously constructed of light plate; however, light plate containers constructed according to the prior art are not acceptable since the end rim possesses insufficient width to permit opening of the container by conventional piercing or wheel type openers. This disadvantage is overcome by the present invention as the three-fold countersink wall provides an endrim. of suflicient width to enable the container to readily open by employing conventional opening devices.

The present invention has particular application to sheet metal containers formed of tinplate which may or may not be lacquered but is also applicable to containers formed of blackplate coated with organic material or metal.

Although several embodiments of the invention have been disclosed and described herein, it is to be expressly understood that various changes and substitutions may be made therein without departing from the spirit of the invention as well understood by those skilled in the art. Reference therefor will be had to the appended claims for a definition of the limitations of the invention.

What is claimed is: 1. A sheet metal container comprising a body member and an end cover joined to an end of the body member for closing and sealing the container,

the end cover including a central portion disposed inwardly from the end of the container at its close end,

the body member having an inside surface extending abount an axis of the container with the inside surface including a portion between the plane of the central portion of the end cover and the plane of the closed end of the container parallel to said axis,

the end cover having its central portion surrounded by a wall portion and an outer portion secured to the end of the body member by a double seam which projects radially from the outside surface of the body member, the wall portion of the end cover being received within the body member in contact with the parallel portion of the inside surface of the body member,

the end cover being formed of sheet metal material of uniform thickness,

the wall portion of the end cover comprising at least three overlapping folds of said sheet metal material 'with adjacent surfaces of the folds in mutual contact, and

the overlapping folds of the wall portion extending throughout a major part of the parallel portion of the inside surface of the body member with one of the folds in overlying contact therewith.

2. A sheet metal container as defined in claim 1 in which the fold in overlapping contact with the parallel portion of the inner surface of the body member merges with the central portion of the end cover, and

in which the fold most removed from the parallel portion of the inner surface of the body member merges into the outer portion of the end cover.

3. A sheet metal container as defined in claim 1 in which the overlapping folds comprise a first fold, a second fold and a third fold,

the first fold overlies the parallel portion of the inside surface of the body member and one edge of the tfirst fold merges with the central portion of the end cover and the second edge of the first fold terminates in spaced relation with the central portion of the end cover.

the second fold overlies the first fold and one edge of the second fold merges with the second edge of the first fold and the second edge of the second fold terminates adjacent the one edge of the first fold, and

the third fold overlies the second fold and one edge of the third fold merges with the second edge of the second fold and the second edge of the third fold merges with the outer portion of the end cover.

4. A sheet metal container as defined in claim 3 in which the marginal portions of the first fold, the

second fold and the third fold adjacent the central portion of the end cover are curved downwardly toward the central portion of the end cover and inwardly toward the axis.

'5. A sheet metal container as defined in claim 3 in which the end cover includes a depressed portion formed in the outer marginal region thereof, and

in which the first fold merges with the depressed portion of the end cover.

6. A sheet metal container as defined in claim 5 in which the marginal portions of the second fold and the third fold adjacent the central portion of the end cover are curved downwardly toward the central portion of the end cover and inwardly toward the axis in overlying relation with the depressed portion.

7. A container having a tubular body having an end closure, said end closure comprising a substantially fiat panel, a countersink wall extending upwardly therefrom and a flange portion extending outwardly from said wall and joined in an end seam to said body, said countersink wall consisting of an outer layer integral with and ex tending upwardly from said panel, an intermediate layer integral with and extending downwardly from the top of said outer layer, said intermediate layer extending downwardly substantially to abutment with said panel, and an inner layer extending upwardly from the bottom of said intermediate layer to said flange.

8. An end closure for a tubular container body comprising a flat central panel, a countersink wall extending upwardly therefrom and a flange extending generally radially outwardly from said countersink wall wherein said countersink wall comprises an outer layer extending upwardly from said panel, an intermediate layer integral with and extending downwardly from the top of said outer layer substantially to said panel and an inner layer integral with and extending upwardly from the bottom of said intermediate layer, said layers lying one against the other.

9. The end closure defined in claim 8 wherein said in- 8 termediate layer extends downwardly and abutts against said panel.

10. The end closure defined in claim 9 wherein said flange extends generally perpendicularly to said countersink wall.

11. The end closure defined in claim 10 wherein said countersink wall is substantially perpendicular to said panel.

12. A container having a tubular body having an end closure, said end closure comprising a substantially flat panel, a countersink Wall extending upwardly therefrom and a flange portion extending outwardly from said wall and joined in an end seam to said body, said countersink wall consisting of an outer layer integral with and extending upwardly from said panel, an intermediate layer integral with and extending downwardly from the top of said outer layer, said intermediate layer extending downwardly to abutment with said panel, and an inner layer extending upwardly from the bottom of Said intermediate layer to said flange.

References Cited UNITED STATES PATENTS 851,815 4/1907 Libbman 220-66 2,426,550 8/1947 Coyle 22067 2,894,844 7/1959 Shakman 220-66 3,186,583 6/1965 Zundel 220-66 FOREIGN PATENTS 11,925 5/1903 Germany.

78,777 10/1918 Switzerland.

JOSEPH R. LECLAIR, Primary Examiner a J. R. GARRETT, Assistant Examiner U.S. Cl. X.R.

PO-IObO (5/69) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3|525o455 D d August 25, 1.970

William T. Saunders It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 31, after "covers" insert --are.

Column 5, line 21, change "present" to --prevent--.

Column 6, line 62, change the period to a comma oihiiib N KEALED rm 1 0 (SEAL) Attest:

Edward M. Flewhwal I WILLIAM E. suaunm, JR. Amsting Commissioner of Patents

Claims

1. A SHEET METAL CONTAINER COMPRISING A BODY MEMBER AND AN END COVER JOINED TO AN END OF THE BODY MEMBER FOR CLOSING AND SEALING THE CONTAINER, THE END COVER INCLUDING A CENTRAL PORTION DISPOSED INWARDLY FROM THE END OF THE CONTAINER AT ITS CLOSED END, THE BODY MEMBER HAVING AN INSIDE SURFACE EXTENDING ABOUNT AN AXIS OF THE CONTAINER WITH THE INSIDE SURFACE INCLUDING A PORTION BETWEEN THE PLANE OF THE CENTRAL PORTION OF THE END COVER AND THE PLANE OF THE CLOSE END OF THE CONTAINER PARALLEL TO SAID AXIS, THE END COVER HAVING ITS CENTRAL PORTION SURROUNDED BY A WALL PORTION AND AN OUTER PORTION SECURED TO THE END OF THE BODY MEMBER BY A DOUBLE SEAM WHICH PROJECTS RADIALLY FROM THE OUTSIDE SURFACE OF THE BODY MEMBER, THE WALL PORTION OF THE END COVER BEING RECEIVED WITHIN THE BODY MEMBER IN CONTACT WITH THE PARALLEL PORTION OF THE INSIDE SURFACE OF THE BODY MEMBER, THE END COVER BEING FORMED OF SHEET METAL MATERIAL OF UNIFORM THICKNESS, THE WALL PORTION OF THE END COVER COMPRISING AT LEAST THREE OVERLAPPING FOLDS OF SAID SHEET METAL MATERIAL WITH ADJACENT SURFACES OF THE FOLDS IN MUTUAL CONTACT, AND THE OVERLAPPING FOLDS OF THE WALL PORTION EXTENDING THROUGHOUT A MAJOR PART OF THE PARALLEL PORTION OF THE INSIDE SURFACE OF THE BODY MEMBER WITH ONE OF THE FOLDS IN OVERLYING CONTACT THEREWITH.