US2963835A - Sealing containers - Google Patents

Description

Dec. 13, 1960 P. E. CLIF T SEALING CONTAINERS Filed Aug. 26, 1957 nite States Patent SEALING CONTAINERS Paul Emory Cliff, Rugby, England, assignor to Thomas Hunter Limited, Rugby, England Filed Aug. 26, 1957, Ser. No. 680,267

Claims priority, application Great Britain Aug. 31, 1956 Claims. (Cl. 53-42) This invention relates to the closing or sealing of caps on to screw threaded containers, especially glass jars.

It is already well known to seal jars such as jam jars, formed with a continuous bead around the mouth, by the indentation in situ at spaced position, under the bead, of the reinforced edge of a cap skirt, so pulling the cap (with is gasket) tightly on to the jar mouth.

A considerable amount of effort has been directed towards adapting this method of closure to screw-threaded containers with a View to orientating the thread form and indentation means of the closing head relative to one another, especially for containers having a short multistart thread. Heretofore, it had never been doubted that such orientation was necessary.

This invention consists in a method of closing a container formed with a continuous thread form about its mouth, with a skirted cap, which comprises indenting the cap skirt at a plurality of circumferentially spaced substantially coplanar positions whilst the cap is seated on the container mouth, the skirt forming a snug fit about the thread form and the latter extending at least as far as the skirt edge.

Preferably, the cap used has a reinforced edge to the skirt, and it is this edge which is indented.

In one convenient arrangement, the thread form merges into a ring (termed a transfer ring) formed around the container, and the reinforced skirt edge substantially reaches this ring when the cap is passed on to the container mouth. Such thread forms are commonly offered on containers for use with rolled-on screw closures.

It is surprising that an effective grip should be obtainable by indentations, all at the same level, engaging a helical thread. However, not only can such an effective grip be obtained, but the method affords distinct advantages apart from the avoidance of having to orientate the container or sealing head, In particular, the cap is or tends to be self-ejecting on being unscrewed, thus aifording means for breaking the vacuum in the case of vacuum closures. This is because the thread form extends at least as far as the reinforced edge so that on unscrewing, some at least of the indentations will ride up the thread form, further, it is found possible to press the cap home after it has been unscrewed, and to tighten with a short twist, so avoiding protracted screwing home, and crossed threads.

Another advantage is that the number of indentations and correspondingly the grip can Within limits be carried at will, so minimising thread bind, a fault normally encountered on traditional metal screw caps whether preformed or rolled on. At the same time many pre-existing closure installations can be used without modification.

It will be desirable to have the indentation members of the sealing head resiliently mounted, as in the head known under the name Omnia so as to avoid excessive pressure at the point where a member is located, in use, opposite the crest of the thread.

The method so far described enables a good vacuum to dentations with a minimum of four in each set.

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be obtained when sealing cold products with the aid of steam injection, and when sealing hot products, but may not always be adequate if extended to the sealing of products which are to be pasteurised. The pasteurisation process is not normally applicable to screw-capped jars, where it is required that the air contained above cold-sealed products should be vented on heating the container to pasteurisation temperature without prejudicing the automatic reseating of the cap to create a vacuum.

We have found that the re-seating of caps sealed on as described above is promoted if the cap skirt is indented in situ about the thread form to provide two axially spaced coplanar sets of indentations, preferably having an axial separation of a fraction, suitably the order of one half of a thread pitch. The indentations may be staggered, suitably symmetrically. Preferably also, one of the sets of indentations is in a reinforced edge of the cap skirt.

Tests have shown that caps may be applied, as just described, to jars containing cold products without steam injection, and vacuum drawn reliably after pasteurising. Of course, this method may equally be applied to hotsealed products and those vacuumised by steam injection, thereby not only securing an enhanced safety margin but also giving an increased versatility to the sealing apparatus.

The number of indentations in the or each coplanar set will not normally be less than four, although the optimum number will be influenced by many factors, such as the strength of the metal, the diameter of the container mouth, the shape, angle and number of starts of the thread, and the desired grip, as well as whether one or two sets of indentations are used, and whether the contents will be under vacuum. With single start threads of diameter exceeding about 35 mm. at least six indentations in a single set or four in each of two sets Will be desir able; with double start threads of this diameter at least five indentations in a single set will generally be desirable, or at least four in each of two sets. With wide mouth containers, where the thread is at least about 70 mm. in diameter, it is preferred to use two sets of in- In practice, more than these mimima will generally be employed, for example 6-12 indentations in each set.

The invention also consists in a sealing head comprising an annulus of circumferentially spaced indentationeifecting members having co-cylindrical working tips in two axially spaced sets each set occupying a plane at rightangles to the head axis and being constituted by the tips of alternate indentation-effecting members. The head may be essentially the same as that used under the name Omnia (registered trademark) of which the indentationefiecting members are cantilever-mounted fingers extending more or less axially from a crown member with a set of co-operating outer fingers for pushing the firstmentioned fingers inwards by cam action on relative axial motion between the two, the working tips being on the radially inner face of the inner fingers, disposed at the angles of an annular zig-zag. Such a head in accordance with this invention may be exactly like a customary Omnia head except for the displacement of alternate tips or claws to a higher position so as to indent the wall of a cap skirt instead of the reinforced edge.

The invention further consists in a container having an externally, continuous-threaded mouth closed by a cap having a skirt indented at a plurality of coplanar, circumferentially spaced positions so as to grip the thread form. Preferably the indentations are around the skirt edge, which is reinforced. In addition a coplanar, axially displaced set of indentations may be provided, preferably the same in number and staggered symmetrically relative to the first set, and preferably having an axial displacement of about one half thread pitch.

The invention will be described further with reference to the following drawings, of which:

Figure 1 is a side, partly sectional view of a sealing head, and

Figure 2 is a side view of a sealed jar.

The sealing head of Figure l is precisely as shown in Figure l of United States Patent No. 2,670,118 of S. D. Young, and referenced generally 1, except that the working tips or claws 2 alternate with like tips 3 at a higher level. Tips 2 are at a proper depth below pressure plate 4 to engage the reinforced edge 5 of a cap 6 placed on a screw-threaded jar 7 (Figure 2); tips 3 engage the skirt about /2 thread pitch above the edge as at 8. The thread, not seen, merges at the bottom end with transfer ring 9.

I claim:

1. A method of closing a container formed with a continuous thread form about its mouth, with a skirted cap, which comprises indenting the cap skirt at a plurality of circumferentially spaced substantially coplanar positions whilst the cap is seated on the container mouth, the skirt forming a snug fit about the thread form and the latter extending at least as far as the skirt edge- 2. A method according to claim 1, in which the cap used has a reinforced edge to the skirt, and it is this edge which is indented.

3. A method according to claim 2, in which the thread form merges into a transfer ring formed around the container, and. the reinforced skirt edge substantially reaches this ring when the cap is passed on to the container mouth.

4. A method according to claim 1, in which the cap skirt is indented in situ about the thread form to provide two axially spaced coplanar sets of indentations having an axial separation less than a thread pitch.

5. A method according to claim 4, in which the indentations of the two sets are symmetrically staggered relative to one another.

6. A method according to claim 5, in which the axial separation is about one half of the thread pitch.

7. A sealing head comprising an annulus of circumferentially spaced indentation-effecting members having co-cylindrical working tips in two axially spaced sets each set occupying a plane at right-angles to the head axis 4 and being constituted by the tips of alternate indentationefifecting members.

8. A sealing head according to claim 7, in which the working tips lie at the angles of an annular zig-zag on the inner face of the end portion of respective axiallyextending cantilever-mountedv fingers comprised by the head.

9. A method of closing a container formed with a continuous thread form about its mouth, with a skirted cap, the skirtforming. a snug fit about. the thread form and the latter extending at least as far as the skirt edge, the skirt edge being reinforced, which comprises indenting the reinforced skirt edge at from 6 to 12 circumferentially spaced substantially coplanar positions whilst the cap is seated on the container mouth.

10. A method of closing a container formed with a continuous thread form about its mouth, with a skirted cap, the skirt forming a snug fit about the thread form and the latter extending at least as. far as the skirt edge, the skirt edge being reinforced, which comprises indenting the reinforced edge at from 6 to 12 circumferentially spaced substantially coplanar positions whilst the cap is seated on the container mouth, and also indenting the cap skirt at from 6 to 12 circumferentially spaced sub stantially coplanar positions which are symmetrically staggered relative to the first mentioned positions and are spaced axially therefrom by about one half of the thread pitch.

References Cited in the file of this patent UNITED STATES PATENTS 774,425 Hicks Nov. 8, 1904 1,473,540 Bernardo Nov. 6, 1923 1,579,942 Jensvold Apr. 6, 1926 1,979,458 Eisen -c Nov. 6, 1934 1,998,628 Kramer Apr. 23, 1935 2,139,572 Bootld Dec. 6, 1938 2,171,015 Webb Aug. 29, 1939 2,409,788 Osborne Oct. 22, 1945 2,670,118 Young 5. Feb. 23, 1954 2,765,600 Young Oct. 9, 1956 FOREIGN PATENTS 826,557 Germany Ian. 3, 1952

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