Device and method for creating a vacuum in bags

Abstract: A device and method are described for creating a vacuum in bags (20), particularly those for holding food products, in which the device comprises an outer tube (10) that is inserted into the bag (20) from above and an inner tube (11) that can slide axially inside the tube (10) to move from a retracted position in which it is completely housed inside the tube (10) to an extended position in which it protrudes downwards from the tube. The inner tube (11) takes up a position protruding from the tube (10) during creation of the vacuum in the bag (20) and a retracted position inside the tube (10) to allow sealing of the bag (20) by means of a pair of sealing bars (32).

Description: The present invention relates to a device and a method for creating a vacuum in bags, particularly in packs with one or more layers of sheet material, for holding granular or pulverulent products or the like. As is known, various methods exist for creating vacuum in a pack. One method entails having the head of the vacuum-creating machine work in a bell inside which the pack is placed. When all the air is sucked from the bell, the residual air in the pack is obviously drawn off too, after which the pack is sealed. Another method, which is that to which the present invention refers, entails inserting a suction tube, known as a "snorkel", into the bag, open at the top; the air contained in the bag is drawn through the tube, to create the vacuum. When the vacuum has been created in the bag, the tube (snorkel) remains trapped inside it and can be removed only after the opposite walls of the bag have been soldered beneath the bottom end of said tube. This method, though widely used, presents great drawbacks. Since the products contained in the packs in which the vacuum must be created are generally food products, it is clearly desirable to produce the highest vacuum possible to allow better preservation of the product. The further the tube is inserted inside the bag, that is the nearer its end is to the product, the higher the vacuum that can be reached. However, the suction tube cannot be inserted far into the bag, to leave sufficient space to seal it. The degree of vacuum that can be produced can also be improved by using a large-sized tube. However, in this case when soldering is carried out to seal the bag, creases can form that jeopardise the vacuum seal. GB-A-728 239 discloses a device specifically designed to work in the horizontal position, having a head assembly that includes a nozzle with a slidably mounted suction tongue therein clamping jaws and spreader bars that are fixed on a frame for movement together with the frame. The nozzle is not itself insertable into a bag . US-A-3 700 387 discloses a sealing apparatus including a vacuum manifold having a bell on which a bag opening is placed by an operator and clamp bars clamp the bag to the bell. Once the bag is placed on the bell, the movable suction tube of the manifold causes the bag to collapse on the bell, after which a clip is applied to the bag. US-A-4 736 572 discloses a device for creating a vacuum in bags comprising a movable first suction tube, means for inserting the bottom end of the tube into a bag, a pair of shaped clamping bars to close the bag tightly around the suction tube and means for sealing the bag disposed below the bottom end of the tube and the shaped bars, as described in the preamble of claim 1. The aim of the invention is to eliminate the drawbacks of this vacuum creating and sealing method, providing a device and relative method that allow a high vacuum to be reached in the packs, ensuring perfect seals, without any creases forming. This aim is achieved, according to the invention, with the characteristics listed in the attached independent claims. Preferred embodiments of the invention appear from the dependent claims. The suction tube substantially contains inside it a second tube axially mobile with respect to said suction tube, so as to protrude from it and penetrate further into the pack during the suction stage, returning into the outer tube at the end of the suction stage to allow sealing of the pack. The inner tube thus performs the dual function of holding the opposite walls of the pack apart during the suction stage, preventing them from obstructing the mouth of the suction tube, and at the same time improving the vacuum that can be reached by also sucking through the inner tube. Further characteristics of the invention will be made clearer by the detailed description that follows, referring to a purely exemplary and therefore non-limiting embodiment, illustrated in the attached drawings in which: Figure 1 is a schematic side elevation view, with some parts in sectional view, of the head of the device for creating a vacuum in bags according to the invention; Figures 2 to 7 are even more schematic views similar to that in Figure 1, showing the successive stages of a cycle for creating a vacuum inside a bag; Figure 8 is a view of a suction tube, taken at 90° with respect to the preceding figures; Figure 9 is an axonometric view of the tube in Figure 8. With reference to these figures, 1 indicates the device according to the invention as a whole, comprising a fixed structure 2, inside which a slide 3 driven by a cylinder 4 slides vertically, guided on a column 5. The cylinder 4 is integral with the structure 2 and acts, by means of its stem 6, on a projecting side part 7 of the slide 3. The upper end of a suction tube 10 (seen better in Figures 8 and 9), whose structure will be better described below, is fixed on the bottom of the slide (3), a second tube 11 being disposed inside said tube 10 and axially mobile with respect to it. The inner tube 11 is operated independently by the stem 9 of a second cylinder 8 integral with the slide 3. In this way, actuation of the cylinder 4 produces simultaneous movement of the tubes 10, 11, whilst actuation of the cylinder 8 produces a relative movement of the inner tube 11 with respect to the outer tube 10, for the purposes that will be stated below. As can be seen from Figures 8 and 9, both tubes 10, 11 have a highly flattened shape, so as to allow opposite side walls 21 of a bag or a pack 20 in which vacuum must be created to be kept at a minimal distance (Figures 2-7). The tube 10 has a bottom opening 12, whilst the inner tube 11 has a plurality of side openings 13 on its narrow sides. Should the bag 20 contain non-pulverulent products, openings can also be provided on a bottom wall 14 of the inner tube 11, which in the example shown, however, is closed. Returning to Figure 1, it will be noted that the device according to the invention comprises, on both sides of the suction tube 10, 11 and beneath it, when it is in the raised position, a pair of suction cups 30, such as to separate the upper edges 21' of the opposite side walls 21 of the bag 20 that is positioned under the device for vacuum creation and sealing. The suction cups 30 can obviously be replaced by similar means, such as a pair of pincers for example. Two shaped bars 31 are situated under the suction cups 30 and close on the opposite walls 21 of the bag 20, creating a tight closure around the tube 10, when the latter is inserted in the bag. Beneath the shaped bars 31, two sealing bars 32 are provided to seal the bag after creation of the vacuum. Having briefly described the basic elements of the device according to the invention, operation thereof will now be described, with particular reference to figures 2 to 7. The pack 20 for vacuum sealing is fed and positioned, in a per se known fashion, under the device 2, resting on a flat base 40 and possibly disposed between a pair of side walls 41 that help maintain it in an upright position. In this position, shown in Figure 2, the inner tube 11 is retracted inside the tube 10 and both tubes 10, 11 are in the raised position, above a top margin of the bag 20, whose upper edges 21' of the opposite side walls 21 are held together, for example by means of soldered points or bonding spots, an expedient generally used to facilitate transfer of the bag from the filling station to the sealing station. As can be seen again in Figure 2, the pairs of suction caps 30, shaped bars 31 and sealing or soldering bars 32 are in the open position. As can be seen in Figure 3, the suction cups 30 close on the upper edges 21' of the opposite side walls 21 of the bag 20 and subsequently reopen (Figure 4) to bring said edges apart, producing an upper opening 50 for insertion of the tube 10. At this point first the cylinder 4 is operated to cause simultaneous lowering of the tubes 10, 11, and then the cylinder 8 is operated to produce a further lowering of the inner tube 11 alone and thus cause it to come out of the tube 10, as shown in Figure 5, where the shaped bars 31 are already tightly closed on the tube 10. Once the stage of creating a vacuum in the bag 20 has been completed, the opposite walls 21 are drawn together as shown in Figure 6. At this point the inner tube 11 is retracted inside the tube 10 by again operating the cylinder 8 in the opposite direction, thus allowing closing of the sealing bars 32 that carry out sealing of the bag 20. The suction cups 30 and the shaped bars 31 are then opened, after which the tubes 10 and 11 are removed from the bag with a simultaneous movement, by operating the cylinder 4 (Figure 7). The sealing bars 32 are then opened and the pack is ready to be placed on the market, once the sealed edges have been folded, in a per se known manner. The tubes 10 and 11 are advantageously made of metal, but they can also be made of plastic or other suitable materials. From what is described, the advantages of the invention are obvious in that, thanks to provision of the inner tube 11 it allows the opposite side walls 21 of the bag 20 to be held apart during the final stage of creation of a vacuum inside the bag, and at the same time it allows a higher vacuum to be produced thanks to the suction applied through said inner tube 11, which is positioned much closer to the product than the outer tube 10.

Claims: A device for creating a vacuum in bags (20), comprising: a movable first suction tube (10) having a bottom end insertable from above into a bag (20) having an open top, means for inserting the bottom end of the first suction tube into a bag, a pair of shaped clamping bars (31) to close the bag tightly around said first suction tube (10) during suction of air contained in the bag, means (32) for sealing the bag disposed at a lower level with respect to the inserted position of the bottom end of said tube (10) and said pair of shaped bars (31), characterized in that a second tube (11) is disposed axially inside said first tube (10), and moveable between a retracted position housed completely inside the first tube and an extended position protruding downward from the said first tube, the first tube (10) and the second tube (11) having a highly flattened shape with wider front and back walls and narrower side walls, the shaped clamping bars (31) being disposed parallel to the wider walls of the first suction tube, the second tube (11) having a plural of openings (13) in the narrower side walls, such openings (13) extending across all the width of said side walls and partially into said front and back walls. A device according to claim 1, wherein said second tube (11) has a perforated bottom wall (14). A device according to claim 1 or 2, wherein said means for sealing the bag includes a pair of heat sealing bars (32), the heat sealing bars disposed parallel to the wider front and back walls of the first tube (10). A device according to anyone of the claims 1 to 3, further comprising means (30) for holding apart upper edges (21') of the bag (20), presoldered or not, for inserting the first tube (10). A method for creating a vacuum in a bag, comprising the steps of: placing a bag (20) having an open top under a first flattened suction tube (10), extending said first suction tube into the bag through the open top, clamping the top of the bag around the first suction tube, extending a second flattened tube (11) axially from an end of the first tube (10) further into the bag, said second tube (11) having wider front and back walls and narrower side walls with a plurality of openings (13) which extend across all the width of said narrower side walls and partially into said front and back walls. activating suction means to remove air from the bag through the first and second tubes to create a vacuum in the bag, retracting the second tube (11) into the first tube (10) after a vacuum has been created in the bag, sealing said bag at a location beneath a maximum entry position of said first tube (10) and below the clamped portion of the bag, and, after sealing the bag, releasing the clamped portion of the bag.

Inventors: CARCANO MAURIZIO, CARCANO, MAURIZIO
Applicants: GOGLIO SPA LUIGI MILANO, GOGLIO LUIGI MILANO S.P.A.
Application year: 1996
Main classification: B65B31
IPC codes: B65B31