US3416476A

US3416476A - Container closure seaming method and apparatus

Info

Publication number: US3416476A
Application number: US615296A
Authority: US
Inventors: Wyss Hans
Original assignee: Afico SA
Current assignee: Afico SA
Priority date: 1966-02-11
Filing date: 1967-02-06
Publication date: 1968-12-17
Anticipated expiration: 1985-12-17
Also published as: DE1602544A1; GB1144746A; SE333128B; ES336681A1; DE6605667U; ES340793A1; NO125481B; FR1510798A; CH451862A

Description

H. WYSS Dec. 17, 1968 CONTAINER CLOSURE SEAMING METHOD AND APPARATUS Filed Feb. 6, 1967 United States Patent Oflice Patented Dec. 17, 1968 3,416,476 CONTAINER CLOSURE SEAMING METHOD AND APPARATUS Hans Wyss, Corsier, Vaud, Switzerland, assignor to Afico S.A., Lausanne, Switzerland, a corporation of Switzerland Filed Feb. 6, 1967, Ser. No. 615,296 Claims priority, application Switzerland, Feb. 11, 1966,

13 Claims. (11. 113-30 ABSTRACT OF THE DISCLOSURE The invention relates to the seaming of and end closure with a curled rim to a can body with an outwardly turned lip by a novel method comprising the steps of pinching the rim around the lip, then turning the pinched rim obliquely and downwardly and finally, pressing the rim against the side wall of the can body. The invention also relates to an apparatus for carrying out this method by means of a mandrel provided with a shoulder, a spring loaded roller, a frusto-conical roller and a flattening cylindrical roller. The invention relates further to a can made by the said seaming method.

This invention relates to container closures, more particularly to the seaming of an end closure with curled rim on a tin can body with an outwardly turned lip.

According to the known seaming process generally utilised the can body has a lip turned outwardly at right angles to the body wall and the end closure a curled rim.

The curled rim facilitates stacking and easy separation of the end closures, since they do not have the tendency to wedge together.

During the first operation of the known process, the curled rim is rolled over the lip of the can body, which may be called a roll seam. This rolling is effected by means of a specially profiled roller.

The second and last operation consists of flattening and pressing the rolled rim against the wall of the can body.

Unfortunately, by this method, the hooks formed by the lip and rim do not overlap completely. Consequently, the resulting seal may prove defective in that the can is not airtight, chiefly, for example, at the intersection of the rim and the longitudinal seam of the can body. At this place the conditions of seaming prove more diflicult due to the double thickness of the tinplate of the can body. In order to ensure satisfactory air tightness, it is necessary to provide relatively large seams which requires a larger tinplate surface.

Furthermore, since the rolling of tinplate during the first operation is made without support, its success will depend chiefly on the correct setting of the machine (profile and pressure of the roller) and on the thickness and rigidity of the tinplate as well as the diameter of the can.

Experience has shown that the roll seam is practically inapplicable to thin tinplate, particularly when the diameter of the can is small. This thin tinplate, generally much harder, has a tendency to form wrinkles thus jeopardizing the air-tightness of the seam. The reduced thickness of the tinplate is however an important economic factor, primarily in the manufacture of small cans.

The process according to the present invention overcomes the drawbacks described above.

The present invention provides a novel method for seaming an end closure with a curled rim to a can body having a side wall terminating in an outwardly turned lip, said end closure comprising a downwardly embossed centre portion and an upwardly turned wall portion flaring outwardly from the periphery of said centre portion and terminating in a downwardly curled rim, said method comprising the steps of pinching said curled rim around said lip, by pressing said rim against a projecting portion of holding'means overlapping said curled rim, said holding means comprising a central portion adapted to engage and support the side wall of the closure during the seaming, then turning the pinched rim obliquely and downwardly and finally, pressing the obliquely downturned pinched rim against the side wall of the can body.

The invention also relates to an apparatus for seaming an end closure to a can body having a side wall terminating in an outwardly turned lip, said end closure comprising a downwardly embossed centre portion and an upwardly turned wall portion flaring outwardly from the periphery of said centre portion and terminating in a downwardly curled rim, said apapratus comprising holding means adapted to position the curled rim of the closure over the lip of the can body, said holding means comprising a central portion adapted to engage and support the side wall of the closure during the seaming and a projecting portion overlapping the curled rim of the closure, pinching means adapted to pinch said curled rim around said lip by pressing said rim against the projecting portion of the holding means, means for turning the pinched rim obliquely and downwardly and means for pressing the obliquely downturned pinched rim against the side wall of the can body.

The invention also provides a can, particularly made out of thin tinplate, obtained by the above seaming method.

FIGURES 1 to 4, which are partial sections through the seam, illustrate the different stages of the operation according to the invention.

FIGURESS to 7 illustrate diagrammatically various embodiments of the apparatus according to the invention.

The seaming of the end closure 2 with a curled rim (FIG. 1) is effected on a can body 1 having a lip turned outwardly at right angles to the body wall.

During the first operation (FIG. 2), the end closure rests on a mandrel 3 having a shoulder and said end closure is supported on two of its faces on said mandrel. The downwardly embossed centre portion is supported namely on the slightly conical side of the mandrel and the flatter part of the rim which covers the lip of the can body is supported by the projecting portion of the mandrel. The periphery of the rim is closed around the outwardly turned lip of the body by pinching it between the projecting portion of the mandrel 3 and a roller 4 of generally cylindrical form. This roller may slide axially on the shaft 5 supported by the seaming head of a machine of known type and is pressed against the projecting portion of the mandrel by a spring 6.

By moving this roller around relative to the can body, the rim of the end closure is compressed in such a way as to eliminate progressively any wrinkling which may form therein, the projecting portion of the mandrel being used as a support during this operation.

The second operation consists of turning the pinched rim downwardly through an angle of about 45, by means of a frusto-conical roller 7 turning round the can body (FIG. 3).

Finally, the third operation consists of pressing and flattening the pinched rim against the side wall of the can body whilst it is supported by the side of the mandrel. This operation is effected by means of an essentially cylindrical roller having a groove with approximately the profile of the seam and turning round the can body (FIG. 4).

The method according to the present invention, compared to the known method, has the following advantages:

(1) The hooks formed by the lip and rim overlap completely, giving a tighter seam. Hence the defects encountered mainly at the intersection of the rim and the longitudinal seam of the can body are practically eliminated.

(2) It is possible to use thin tinplate for the manufacture of small diameter cans (73 mm. or less) since the risk of wrinkling is practically non-existent.

(3) All things being equal, the air-tightness is improved so that it is therefore possible to reduce the depth (h) of the seam.

(4) Since the first operation is carried out against the solid support provided by the projecting portion of the mandrel, any possible deformations may be controlled more precisely and hence the seam will be more compact.

(5) The total time of the operation is reduced, in that the process is accomplished during a cycle comprising a smaller number of revolutions of the seaming head or of the can, as will be shown further on.

This process may be applied when the seaming head rotates with respect to the can body, and also when the can body rotates and the seaming rollers remain stationary.

According to one preferred embodiment of the invention, the apparatus comprises 4 seaming rollers symmetrically disposed with respect to the axis of the mandrel (M) spaced at 90 intervals from each other as illustrated in FIG. 5, the rollers being supported by a rotatable seaming head.

The number of revolutions needed for the seaming head to carry out the process is 4% revolutions, which cycle may be divided as follows:

2 revolutions for the first operation (FIG. 2) with 2 seaming rollers m 1 /6 revolutions for the second operation (FIG. 3) with the seaming roller m 2. /6 revolutions for the third operation (FIG. 4) with the seaming roller m 5 /3 revolutions (relative angular displacement of rollers) If the second operation overlaps the first by /6 and the third overlaps the second by 71 revolution, the total effective angular displacement is reduced to 4% revolutions. It should be noted that the second operation is to be effected very rapidly, since this is one of the elements of success, otherwise the pinched rim might open.

In comparison, the cycle of the known process effected with a current seaming machine having 4 rollers also disposed as shown in FIG. 5, may be divided as follows:

4 revolutions for the first operation with 2 rollers m 2% revolutions for second operation with 2 rollers m and m 6% revolutions (relative angular displacement of the rollers) From this total an overlap of half a revolution should be subtracted between the two operations, since each one is eflected by 2 seaming rollers spaced at 180 from each other, hence the effective angular displacement is 6% revolutions.

According to another embodiment, the apparatus comprises a roller for each operation i.e. 3 rollers m disposed around the mandrel M as shown in FIG. 6. If an overlap of of a revolution between each operation is taken into account, the effective angular displacement of the seaming head is 5 /2 revolutions with 3 /2 turns instead of 2 for the first operation.

According to yet another embodiment where contrary to the preceding examples, the mandrel M and the can body rotate relative to the stationary seaming rollers,

the 3 rollers may be arranged as illustrated by FIG. 7 instead of being arranged at 120 intervals. In comparison to the preceding embodiment, this arrangement allows for a greater overlap between the operations; bringing them to revolution, the total angular displacement of the can is 5 /6 revolutions.

It is understood that the above embodiments have been described and illustrated only by way of example and that minor modifications may be made without departing from the scope of the invention.

I claim:

1. A method for seaming an end closure to a cam body having a side wall terminating in an outwardly turned lip, said end closure comprising a downwardly embossed centre portion and an upwardly turned wall portion flaring outwardly from the periphery of said centre portion and terminating in a downwardly curled rim, said method-comprising the steps of pinching said curled rim around said lip, by pressing said rim against a projecting portion of holding means overlapping said curled rim, said holding means comprising a central portion adapted to engage and support the side wall of the closure during the seaming, then turning the pinched rim obliquely and downwardly and finally, pressing the obliquely downturned pinched rim against the side wall of the can body.

2. A method according to claim 1, in which the can and end closure turn 4% revolutions relatively to seaming rollers symmetrically disposed with respect to the axis of said holding means,

3. A method according to claim 1, in which the can and end closure turn 5 /6 revolutions relatively to three stationary seaming rollers grouped close together.

4. An apparatus for seaming an end closure to a can body having a side wall terminating in an outwardly turned lip, said end closure comprising a downwardly embossed centre portion and an upwardly turned wall portion flaring outwardly from the periphery of said centre portion and terminating in a downwardly curled rim, said apparatus comprising holding means adapted to position the curled rim of the closure over the lip of the can body, said holding means comprising a central portion adapted to engage and support the side wall of the closure during the seaming and a projecting portion overlapping the curled rim of the closure, pinching means adapted to pinch said curled rim around said lip by pressing said rim against the projecting portion of the holding means, means for turning the pinched rim obliquely and downwardly and means for pressing the obliquely downturned pinched rim against the side wall of the can body.

5. An apparatus according to claim 4, in which said holding means is a mandrel provided with a shoulder.

6. An apparatus according to claim 4, in which the height of the shoulder of the mandrel is at least equal to the depth of the seam.

7. An apparatus according to claim. 4, comprising 4 seaming rollers symmetrically disposed about the axis of said holding means, said rollers being supported by a rotatable seaming head.

'8. An apparatus according to claim 7, comprising two spring-loaded pinching rollers, one frusto-oonical roller and one substantially cylindrical flattening roller.

9. An apparatus according to claim 4, comprising rotatable holding means and 4 stationary seaming rollers spaced at intervals around said holding means.

10. An apparatus according to claim 4, comprising 3 seaming rollers spaced at intervals from each other and being supported by a rotatable seaming head.

11. An apparatus according to claim 4, comprising rotatable holding means and 3 stationary seaming rollers at 120 from each other.

12. An apparatus according to claim 4, comprising rotatable holding means and 3 stationary seaming rollers grouped close together.

5 6 13. A can, particularly made out of thin tinplate, ob- 2,455,737 12/1948 Coyle 113-120 tained by the method of claim 1. 2,643,627 6/ 1953 Wobbe 113-120 References Cited CHARLES W. LANHAM, Primary Examiner. UNITED STATES PATENTS 5 RONALD D. GREFE, Assistant Examiner.

2,196,206 4/1940 Foss 113-420 US. Cl. X.R.

2,337,452 12/1943 COmpo 113-30 113-1, 121