US3204595A - Clinched seam formation - Google Patents

Description

Sept. 1965 w. c. BROOKSON 3,204,595

CLINCHED SEAM FORMATION Original Filed Aug. 2, 1960 f i A {d .4 A a"! 44 1 y a? 7 j J, 7- f IN V EN TOR.

W Z, 5. W/AZMM (WA/FA 5 5200/60 ATTORNEY United States Patent Ofl ice 3,204,595 CLINCHED SEAM FORMATION William Charles Brookson, Hamilton, Untario, Canada, assignor to American Can Company, New York, N.Y., a corporation of New Jersey Original application Aug. 2, 1960, Ser. No. 46,913, now Patent No. 3,053,409, dated Sept. 11, 1962. Divided and this application Oct. 4, 1961', Ser. No. 146,685 3 Claims. (Cl. 113--121) This application is a division of application Serial No. 46,913, filed August 2, 1960, now US. Patent No. 3,053,- 409, granted September 11, 1962.

The present invention relates to the clinching of can ends onto can bodies to facilitate the vacuumizing of double seamed cans prior to the final double seaming operation, and has particular reference to the formation of a clinched seam wherein conventional can body and end flanges are rolled together to interlock them in such manner as to positively prevent the lining compound which is carried on the end flange from seating on the body flange to hermetically seal off the interior of the can.

In the canning of comminuted products such as powdered milk, ground coflee and the like, it is necessary to remove as much as possible of the air which is entrapped within the can and the product contained therein prior to the final double seaming operation in order to prevent subsequent deterioration of the product by oxidation. Removal of this air is usually effected by placing the filled but unsealed can in a closed chamber and subjecting the chamber to a high vacuum in order to evacuate the interior of the can.

In such vacuumizing operation, vacuums as high as 29.8 inches of mercury may be employed. Since automatic equipment is usually employed, the time during which the evacuating process can be effected is necessarily limited and the vacuum is created in the vacuum chamber in a relatively short time. As a result, there is a definite tendency for the air within the canto be drawn from the can with great velocity, and the resultant outrush of air from the can, unless controlled, frequently carries with it a portion of the comminuted product.

Obviously, removal of the product from the can interior in such manner is very undesirable. In order to prevent it, the usual practice is to apply the can cover to the can body prior to the time the can is inserted into the vacuumizing chamber, and to provide for passageways in either the body or the cover through which the air may be withdrawn, these passageways being carefully dimensioned to limit and control the rate of withdrawal of the an.

A generally used method of providing such passageway is to secure the can cover to the can body in a preliminary seaming operation wherein the can body and end flanges are rolled together to form an incomplete, nonhermetic seam which is referred to as a clinched seam, this seaming operation being known as clinching operation. No particular difficulty is encountered in the formation of such seams when a low vacuum is being drawn, inasmuch as it is possible to use clinched seams which are quite loose and which provide relatively large passageways for the flow of air, since a low vacuum does not pull the air from the can interior violently enough to carry the product with it. Such loosely clinched seams can be easily formed without danger of creating a hermetic seam through which the air cannot pass. However, when very high vacuums are being utilized, the clinched seam must be relatively tight in order to prevent the air from being pulled from the can too rapidly, and there is the ever present possibility that in tight seams the end lining compound will seat on the body flange and create a seal which is completely hermetic, or so close to being hermetic as to effectively prevent the desired withdrawal of the air from the container interior.

A relatively tight clinched seam is also advantageous for use with packing processes wherein the vacuum within the can is replaced by an inert gas such as carbon dioxide or nitrogen, while the can is still in the closed chamber, for in such processes it is a common practice to introduce the can into the outside atmosphere prior to the final seaming operation, and a tight clinched seam is necessary to prevent the inert gas from spilling out of the can and being replaced, in part at least, by the outside air during the transfer of the can from the vacuumizing and gassing chamber to the closing machine. The tighter the clinched seam, the less chance there is: of such loss of inert gas.

The present invention provides a solution to this problem by providing a method and apparatus for forming a clinched seam which positively insures against seating of the end lining compound on the body flange to form a hermetic seal, and yet produces a seam which is tight enough to control the flow of air from the can when high vacuums are being used. This is effected by tightly rolling spaced portions of the seam together in such manner that the end lining compound carried by the cover in such spaced portions is pressed into engagement against the can body flange, thus locking the cover and can body together and holding them against upward relative axial movement so that the seam does not open up to an undesirable extent when the can is subjected to external vacuum. However, the seam, between these tightly rolled portions, is formed with loosely rolled portions wherein the cover flange is lifted upwardly away from the body flange in order to positively eliminate the possibility of having the end lining com-pound in these portions seat upon the body flange. While in these loosely rolled areas there is metal-to-metal contact between the contiguous portions of the can cover and can body, such contact is discontinuous because of the inherent irregularities in the metal of these parts and is not effective in preventing the passage of the air through these portions of the seam.

The clinched seam is formed by a specially profiled, generally circular clinching roll which is provided with an endless clinching groove which is radially non-concentric with the clinching roll axis in order to create the alternate loose and tight seam portions, and which, axially of the roll is of wavy or sinuous configuration so that it is provided with a series of high spots which actually lift the cover flange upwardly away from the body flange in the loose seam portions. As a result of the fact that the cover flange is lifted away from the body in the loosely formed seam portions, there is substantially no chance of having the end lining compound in such areas seat on the body flange and passage of air through the seam is always insured.

An object of the invention therefore is the provision of a method of forming a clinched seam wherein the seam is formed with alternately loosely and tightly rolled portions in such manner that the seating of the end lining compound in the loosely rolled portion is effectively prevented.

Still another object is the provision of a specially constructed seaming roll for effecting the formation of such a seam.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings:

FIGURE 1 is a side elevation of a can having its cover secured in place in a clinched seam made according to the principles of the instant invention, the view also showing Patented Sept. 7, 1965 in operative position relative to said can certain operating parts of a clinching machine, including a specially projected clinching roll which is designed to form the said clinched sea-n1;

FIG. 2 is a plan view of the clinched can and the clinching machine parts shown in FIG. 1;

FIG. 3 is a fragmentary vertical section on an enlarged scale taken through an upper peripheral portion of the can of FIGS. 1 and 2, but showing the can end in assem'bled position on the can body preparatory to the clinching operation;

FIG. 4 is a vertical section, on the same scale as FIG. 3, taken substantially along the line 44 in FIG. 2, this view being taken through the loosely formed portion of the clinched seam, the view also including, in dot and dash linw, a vertical section taken through the corresponding portion of the clinching roll which effects the formation of such loosely formed seam portion; and

FIG. 5 is a vertical section taken substantially along the line 5-5 in FIG. 2, this view being taken through a tightly rolled portion of the clinched seam and also showing in dot and dash lines a vertical section taken through the corresponding portion of the clinching roll which forms the tightly rolled seam portion.

As a preferred .and exemplary embodiment of the instant invention the drawings illustrate a can of the conventional double seamed variety which comprises a tubular can body 12 preferably formed with a conventional side seam 14 and having its lower end closed by a recessed bottom end member 16 which is secured thereto in a conventional double seam 18. The can 10, after being filled with a suitable comminuted or powdery product such as powdered milk (not shown), has applied to its upper end a conventional cover member 20 of the type which is adapted to be sealed to the body 12 in a conventional double seam.

In order to permit the formation of such a double seam, the can body 12 is provided at its upper end with an outwardly extending annular flange 22 which normally projects from the can body 12 in a generally horizontal plane, as best seen in FIG. 3. The cover member 20 is provided with a depressed center panel 24 which at its outer edge merges into an upwardly extending annular wall 26 which in the trade is referred to as a countersink wall. This countersink wall 26 in turn merges into an annular, outwardly extending cover flange 28 which at its outer edge is bent into a downwardly and inwardly extending curl 30. The underside of the cover flange 23 carries an end lining compound 32 which normally comprises a thin film of a rubbery material, which when compressed between the cover flange 28 and body flange 22 in the finished double seam (not shown), provides a hermetic seal.

When the cover member 20 is initially placed in position in the upper end of the can body 12, as best seen in FIG. 3, the end lining compound 32 comes into loose contact with the upper surface of the body flange 22. With these parts thus positioned, the filled can is fed into a clinching machine wherein the formation of the clinched sear-n of the instant invention is effected. In such machine, the cover member 20 and can body 12 are clamped together under pressure between a seaming chunk 40, which is so shaped that it fits into the cover member 20 and engages against the panel 24 and against the inner surface of the countersink wall 26, and a lifter pad 42 which fits into the recessed bottom end member 16.

After being thus clamped together, a clinching roll 44, made according to the principles of the instant invention, is moved radially of the can and brought into contact with the outer surface of the cover flange 28 and curl 26 in order to reshape the cover flange 28 and body flange 22 to form a clinched seam S, which tightly secures the cover member 20 in position on the can body 12, but which is not hermetically sealed and thus permits the passage of air from the interior of the can when the clinched can is subsequently introduced int-o a vacuumizing chamber (not shown).

The clinching roll 44 is carried by a shaft 46 and is mounted for axial rotation, being either positively driven by the shaft 46 or idly affixed thereto. Suitable means are provided to effect a relative circumferential movement of the rotating clinching roll 44 around the upper periphery of the can It) and cover 20 to thereby effect formation of the clinched seam S. This may be done either by moving the clinching roll 44 bodily around the can 10 and cover 20, or by rotating the can 14D and cover 20 on their own axes and maintaining a seaming roll shaft 46 in a fixed position relative thereto.

As best seen in FIG. 1, the clinching roll 44 is formed with an upper annular shoulder 48, which extends inwardly over the cover flange 28, and a body portion 50 which is disposed immediately below said shoulder. An endless annular clinching groove 52 of special configuration is cut into an outer periphery of the body portion 50. This clinching groove 52 throughout its length is uniform in vertical cross-sectional contour as best seen in FIGS. 4 and 5, but is generally sinuous or wavy as viewed in side elevation (see FIG. 1) and is formed with a plurality of evenly spaced high portions 54 which are offset upwardly relative to the intervening low portions 56. The distance of offset is comparatively small, and may be in the nature of .025", although this figure may be varied somewhat on either side and still produce the desired results.

In addition to its serpentine configuration, the groove 52 is irregular in that it is not concentric with the axis of the seaming roll 44, but is preferably formed of a plurality (here shown as three) of eccentric groove segments 58 each of which extends around the clinching roll 44, thus forming what in effect is a three lobed groove. The eccentricity of the segments 58 is, however, comparatively minor so that they merge smoothly into each other at their ends at points which are designated by the letter B, the groove 52 at such points being at its maximum distance from the axis of the clinching roll 44 (as best seen in FIG. 2). The total eccentricity of the segments 58 is not critical, but as example, there may be radial variations of approximately .055" in the groove 52 of a roll wherein the diameter of the body portion 50 is approximately 1.977. As best seen in FIG. 1, the body portion 50 is not actually circular but has a circumferential contour which is substantially parallel to the contour of the clinching groove 52, being formed of three eccentric segments which merge smoothly into each other.

The clinching groove 52 is formed so that there is a definite relationship between its eccentricity and its sinuosity, the low spots 56 of the groove 52 coinciding with the points E of greatest radial length, and the high spots 54 lying midway between the points E and coinciding with those portions of the groove 52 having the shortest radial length.

When the clinching roll 44 is moved inwardly against the flange 28 of the cover member 20, the clinching groove 52 reshapes this flange 28 to roll it downwardly and inwardly beneath the can body flange 22, and this movement of the cover flange 28 in turn bends the body flange 22 downwardly and inwardly, the result being that these flanges are rolled together and interlocked to form the clinched seam S of the instant invention.

Because of the unusal configuration of the seaming groove 52, this clinched seam is not formed of uniform tightness, but rather comprises a series of loosely clinched portions, which will be hereinafter referred to by the letter L, and a series of tightly clinched portions which will hereinafter be referred to by the letter T, the portions L and T merging into each other smoothly and evenly, as best seen in FIG. 1.

At the tightly clinched portions T, the can body and end flanges 22, 28 are tightly rolled together in such manner that the end lining compound 32 seats upon the body flange 22 as clearly seen in FIG. 5, thus effecting a substantially hermetic seal at these portions.

The tight seam portions T are formed by the portions E of the clinching groove 52, because at such points the clinching groove 52 has its greatest radial length, and thus extends farthest towards the axis of the can body 12 and cover 20. Also, the portions E coincide with the low spots 56 of the groove 52 and the combination of these two factors eifects the maximum reshaping of the can parts and in effect gives the tight seam portions T a contour which closely approximates that of a full first operation seam.

Laterally of the tight seam portions T, however, the cover flange 28 is gradually lifted upwardly away from the body flange 22 by the high spots 54 of the clinching groove 52, and in addition, is rolled less tightly in a lateral direction as the portions 54 of the clinching groove 52 become operative. As a result, the lining compound 32 in such seam portions is positively lifted out of contact with the body flange 22, and is prevented from seating thereon. As seen in FIG. 4 the body flange 22 may be reshaped slightly, even in the loose seam portions L, but is nevertheless maintained out of contact with the lining compound 28.

Thus, when the clinched can is placed in the vacuumizing chamber and subjected to external vacuum, the air within the can passes easily and readily through the loose seam portions L and the desired vacuum within the can is quickly obtained, despite the fact that metal-tometal contact between the can body and cover may be present in such loosely roller portions.

It will be clear that the invention is not limited to a clinching roll wherein the lobes which form the tight seam portions T are formed by eccentric segments in the manner shown, but that the lobes may be formed in any manner, as long as the groove contains portions of difierent radial lengths. It will also be clear that the invention is not limited to a three lobed clinching groove, but that a groove having one or more lobes will effect alternate loose and tight seam portions, the frequency and spacing between such portions however, being determined by the number of lobes used. In every construction, however, the low portions of the clinching groove will concide with the groove lobes, so that these portions of the groove will produce tight seam portions.

After the air has thus been removed from the can, it is necessary to dissipate the vacuum Within the can in order to prevent its replacement by the external air if the clinched can is to be introduced into the outside atmosphere prior to the final seaming operation. In such event, the vacuum in the chamber is replaced by an inert gas such as nitrogen or carbon dioxide which is held at substantially atmospheric pressure. Because of the high vacuum Within the can, such inert gas passes through the loose seam portions L and enters the can until it establishes a substantially atmospheric pressure therewithin. Thereafter, the clinched gassed can may be introduced into the external atmosphere, and then fed into a closing machine wherein the final double seam is formed in the conventional manner. Because of the fact that the gas pressure within is substantially in balance with the atmospheric pressure, and because the passageways in the loosely seam portions L are restricted by the metal-tometal contact in such areas, there is substantially no tendency for the gas in the can to be replaced by the external air during the time the can is being transferred from the chamber to the closing machine, and thus the oxygen content of the finally seamed can is held to a minimum.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing discription, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts and in the steps of the method described and their order of accomplishment without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. The method of forming a clinched seam, which comprises the steps of clamping a flanged can end having sealing material thereon and a flanged can body together, rolling the flanges of said can end and said can body toether to produce alternating loosely rolled seam portions, and tightly rolled seam portions wherein said can end flange and said sealing material thereon are maintained in engagement with said can body flange, and simultaneously lifting said can end flange in said loosely rolled seam portions to move said sealing material thereon out of engagement with said can body flange.

2. The method of forming a clinched seam which comprises the steps of clamping a flanged can end having sealing material thereon and a flanged can body together, rolling said flanges together to interlock them, and simultaneously imparting an axially sinuous configuration to said flanges to produce tightly interlocked flange portions wherein said can end flange and said sealing material thereon are maintained in engagement with said can body flange, and loosely interlocked flange portions wherein the portion of said can end flange having said sealing material thereon is axially spaced from said can body flange to prevent a hermetic seal between said flanges in said loosely interlocked flanged portions.

3. The method of claim 2 wherein said loosely interlocked flange portions are so formed that said can end flange is disposed in engagement with the end portion of said can body flange in said loosely interlocked portions.

References Cited by the Examiner UNITED STATES PATENTS 1,160,055 11/15 Dorland 113 23 1,367,953 2/21 Englund 113 23 1,476,213 12/23 OBrien 113- 1,689,641 10/23 Pickles 113-120 1,766,173 6/30 Hills 113- 120 2,455,737 12/48 COyle .113 120 2,643,627 6/53 Wobbe "113-120 CHARLES W. LANHAM, Primary Examiner. WHITMORE A. WILTZ, Examiner.

Claims (1)

1. THE METHOD OF FORMING A CLINCHED SEAM, WHICH COMPRISES THE STEPS OF CLAMPING A FLANGES CAN END HAVING SEALING MATERIAL THEREON AND A FLANGED CAN BODY TOGETHER, ROLLING THE FLANGES OF SAID CAN END AND SAID CAN BODY TOGETHER TO PRODUCE ALTERNATING LOOSELY ROLLED SEAM PORTIONS, AND TIGHTLY ROLLED SEAM PORTIONS WHEREIN SAID CAN END FLANGE AND SAID SEALING MATERIAL THEREON ARE MAINTAINED IN ENGAGEMENT WITH SAID CAN BODY FLANGE, AND SIMULTANEOUSLY LIFTING SAID CAN END FLANGE IN SAID LOOSELY ROLLED SEAM PORTIONS TO MOVE SAID SEALING MATERIAL THEREON OUT OF ENGAGEMENT WITH SAID CAN BODY FLANGE.

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