GB2247000A

GB2247000A - Packaging machine

Info

Publication number: GB2247000A
Application number: GB9110186A
Authority: GB
Inventors: Renzo Francioni
Original assignee: Cavanna SpA
Current assignee: Cavanna SpA
Priority date: 1990-08-17
Filing date: 1991-05-10
Publication date: 1992-02-19
Anticipated expiration: 2011-05-10
Also published as: CH682652A5; NL9101391A; FR2665876A1; ES2043501A2; IT9067648A1; ES2043501B1; DE4123923A1; ES2043501R; IT9067648A0; GB2247000B; GB9110186D0; IT1240711B

Abstract

In an automatic packaging machine 1, particularly for food products such as confectionery in which the articles p to be packaged are inserted in a tubular wrapper s which is then transversely sealed by a first unit 6 and further sealed and cut by a second unit 7 spaced from the first unit in the direction of wrapper advance, is characterised in that the second unit is adjustably mounted to permit variation of the spacing between the two units. The spacing is adjusted to a distance d non-equal to the package length to be formed, or whole multiples of that length, so that the wrapper is not stressed by simultaneous engagement by the two units (Fig. 3). <IMAGE>

Description

2 1) G, PACKAGING MACHINE The present invention relates to packaging

machines and is particularly concerned with packaging machines which can form wrappers of the type currently known as "flow-packs","form-fill-seal", or simply 1IFFS11 packages.

More specifically, the present invention relates to a packaging machine including two units arranged in cascade for closing the wrapper, the upstream unit having the function of closing the tubular wrapper by. forming closure regions (seals)- which separate successive articles to be packaged and the downstream unit having the function of further reinforcing the seal and also of cutting the wrapper so as to separate the successive packages thus formed.

Such packagunig machines are widely known in the art as can be seen, for ele, from United States patents Nos.2,280,405, 3,007,295 and 3,241,288, from European patent application No. 0055211, and from italian patent No. 1,208,'.11 and the corresponding United States patent No. 4,862,673, the last two patents being in the name of the present Applicant.

Up to now, packaging machines of the type specified above have been used primarily for forming flow-pack wrappers for generally flattened articles, that is, articles whose heights (this term meaning their dimensions in the direction in which the tubular wrappers are pressed shut) are much less than their lengths (this latter term meaning their dimensions in the direction of advance of the articles in the packaging machine, that is, the direction in which the 1 2 sheet or film for forming the tubular wrapper is usually supplied).

Under these conditions, provided that the two closure units are suitably synchronised (whichcan easily be achieved by known means), the distance between the regions in which the two closure units act in cascade may be largely irrelevant as regards the quality of the final product.

The Applicant has now found that this is not true if flow-pack wrappers are to be formed for fairly "tall" articles, that is, articles whose heights correspond to a considerable fraction (l/3-1/4) of their lengths: this is the case, for example, with wrappers which contain biscuits or crackers stacked vertically in the package.

When one is operating on such articles, the closure of the wrapper with the consequent formation of flattened closure regions which, after the cutting and consequent separation of the individual packages, are intended to form the so-called end flaps of the wrappers involves the application of a considerable longitudinal tensile stress to the tubular wrapper.

As a result, under some operating conditions (that is, for finished wrappers of certain lengths), the two closure units arranged in cascade may operate on the wrapper simultaneously, which results in th@ application of considerable longitudinal stress to the wrapper. This may give rise to considerab " le problems in operation, particularly as regards the tisk that the seal which is formed by the upstream unit (usually by the - localised melting of the plastics material 3 constituting the wrapper or of a film of fusible material applied to a metallic wrapper) may reopen as a result of the separation of the parts of the tubular wrapper which are brought into contact with each other in the first closure unit. Even if the parts of the seal do not reopen, the overall quality of the closure of the wrapper may be adversely affected.

In theory, this problem could be resolved simply by controlling the operation of the closure units so that they never act simultaneously on the wrapper which is being closed.

In practice, it has been found that this principle cannot be applied in a generalised manner since the relative phases of the movement of the two closure units cannot be selected freely but, in general, depend on a set of physical parameters of the installation and, in particular, on the dimensions of the articles and the final dimensions of the packages produced.

There is thus a need to provide means which can solve the aforesaid problems in a generalised manner but which is completely free of the physical constraints of the systems described above.

According to the present invention, this object is achieved by a packaging machine having the characteristics recited specifically in the claims which follow.

In summary, in the packaging machine of the invention, the distance between the regions in which the two closure units act in cascade, that is, the distance between the two closure units in the direction of

4 advance of the articles, can be varied selectively and permanently.

It should be stated that the term "permanently" as used in the present description and in the claims which follow relates specifically to the fact that, in the machine according to the invention, the distance between the two closure units arranged in cascade can be varied selectively (for example, by its adjustment according to criteria which will be explained further below - for the overall lengths of the wrappers to be formed) whilst its adjustment position is kept constant as long as no further adjustment opdration takes place to allow for articles of different shapes.

This distinguishes the solution of the present invention precisely from the solution of the prior Italian patent No. 1,208,411 and the corresponding United States patent No. 4,862,673, in which the distance between the two closure units arranged in cascade is varied cyclically to a limited extent - at a frequency corresponding to the frequency at which the individual articles advance so as to enable the closure unit situated downstream to "follow" the wrapper during the reinforcement of the closure and the cutting of the wrapper in order to separate the individual packages.

The invention will now be described, purely by way of non-limiting example, with reference to the appended drawings, in which:

Figure 1 is an ideal, longitudinal, vertical section of part of a packaging machine according to the invention, and 1 Figures 2 and 3 show the operating criteria of the machine of Figure 1 in greater detail.

Figure 1 corresponds, essentially, to Figure 3 of the drawings appended to Italian patent No. 1,208,411 and the corresponding United States patent No. 4,862,673.

The general description of the operating principles of the packaging machine of these prior patents will not therefore be repeated herein, except insofar as it is necessary for an understanding of the invention.

In summary, it will be remembered that the packaging machine, generally indicated 1, is intended to form packages of the type currently known as "flow-packs", each containing a respective article or group of articles (so-called "multi-pack" packages).

The packages are formed from a continuous flow of products P advancing from right to left as seen in Figure 1.

According to widely known criteria, a continuous tubular wrapper is formed (by known means not shown specifically) from a sheet of plastics material, or metallic material covered by a film of plastics material, which unwinds from a supply station, not shown in the drawings, and the articles P are fed into the wrapper at regular intervals (with reference to single packs for simplicity).

The continuous tube with the articles P spaced regularly therein is advanced towards a closure station 5 whose function is essentially to flatten the tubular wrapper in the spaces between two consecutive articles 6 P to form sealed regions in those spaces in order sealingly to separate the individual articles P. The wrapper is then subjected to a further sealing and cutting operation resulting in the separation of the packages.

In the embodiment illustrated in Figures 1, the closure station 5 has two assemblies or units 6 and 7 which have rotary jaws and are arranged upstream and downstream respectively in the direction (from right to left) in which the products P advance through the machine 1.

The downstream unit 7 includes two identical rotary jaws, an upper jaw 8 and a lower jaw 9. Each j aw comprises essentially a shaft 8a, 9a which is rotated by drive means (not shown) and on which one or more active members 8b, 9b (two in the embodiment illustrated) carrying associated heaters, not shown, are mounted.

In this specific embodiment, each of the jaws 8 and 9 has a pair of active members 8b, 9b which are mounted in diametrally opposite positions and whose free ends, which are generally rounded and may have grooves for gripping the wrapper, carry cutting members (cutters) 10 which are intended to cooperate with each other to reinforce the seal formed previously by the upstream unit 6 (according to criteria described further below) and to cut the sealed region between successive articles so as to separate the individual packages.

The shafts Sa, 9a are interconnected in known manner by a gear mechanism which rotates them in opposite senses. The active members 8b, 9b thus perform orbital 7 movements in opposite senses so that one of the active members 8b of the upper jaw 8 is lowered from time to time to cooperate with a rising active member 9b of the lower jaw 9 so as to cut the wrapper and separate the two packages. For this purpose, the active members 8b and 9b have cutters 10. When these come into contact with each other, they cut the wrapper which is softened by the heaters in the jaws.

The function of the upstream unit 6, however, is to form beforehand the sealed region which is cut by the downstream unit 7. To form the sealed region, the region of the tubular wrapper between two successive articles p is squashed and the wrapper is simultaneously heated so that the two sides or portions of the wrapper which are pressed together are heatsealed.

For this purpose, the unit 6 includes an upper jaw 11 and a lower jaw 12 each constituted by a rotary shaft 1 la, 12a on which respective active members llb, 12b with rounded free ends, possibly with grooves for gripping the wrapper, are mounted.

The upper jaw 11 of the unit 6 is substantially the same as the jaws 8 and 9 of the unit 7 but with the difference that the jaw 11 (like the jaw 12) does not have the cutters 10 which are present on the jaws of the unit 7.

The active members llb, 12b of the jaws 11 and 12 also have heaters (not shown) for bringing the portions of the active members llb, 12b which are intended to act on the wrapper to a temperature such that the two portions of the wrapper which are gripped between the 8 two jaws 11 and 12 during the sealing operation are melted locally and are consequently sealed.

The lower jaw 12 differs from the other jaws 8, 9, 11 in that, as well as having slightly --.larger active members 12b, it also has a different number of active members, the number selected being three, arranged at 0 angular spacings of 120 moreover, the jaws 11 and 12 of the unit 6 are mounted on the frame of the machine 1 with the interposition of an oscillating or swinging support structure 13 which is moved by a crank-and-slotted-link mechanism 14.

According to the criteria described in detail in Italian patent No. 1,208, 411 and in the corresponding United States patent No. 4,862,673 (to which reference should be made for a more complete description), the function of the mechanism 14, which is connected to the support structure 13 by a transmission rod 30, is to cause the structure 13 to oscillate, and hence the jaw 11 to oscillate relative to the jaw 12, at different speeds in the two senses: in particular, the forward swing (that is, the movement in the sense which brings the upper jaw 11 towards the cutting unit 7) is faster than the swing in the opposite sense.

This oscillation enables the upper jaw 11 to "follow" the region of the tubular wrapper between two successive products P so that - under all conditions it can remain in contact therewith long enough for the wrapper to be heat-sealed and closed correctly.

More particularly, in the solution of the prior Italian and Dnited States patents 1,208,411 and 4,862,673, the 9 structure 13 oscillates about a substantially fixed position identified, in practice, by the axis of rotation X 12 of the shaft 12a of the lower jaw 12.

The jaws 8 and 9 of the downstream unit 7 are also mounted in positions which are practically fixed relative to the frame of the machine 1, except that, at most, the relative positions of the jaws can be adjusted precisely and limited relative pivoting of the jaws can take place during their movement in order to prevent jamming.

The main characteristic of the machine according to the present invention, however, is that the closure unit 7 situated downstream (that is, the jaws 8 and 9 and their support frame, generally indicated 100) is mounted on the structure of the machine 1 so that it can move horizontally.

In a currently preferred embodiment, for example, the frame 100 is mounted on a set of prismatic guides 102 extending longitudinally of the machine (in the direction of advance of the products P) beneath the lower jaw 9.

There may be two guides 102 on opposite sides of the path of the products P or there may be a larger number of guides.

The frame 100 is restrained on the guides 102 by clamping means, such as screws 104 or the like, which can be slackened selectively to enable the frame 100 to slide longitudinally on the guides 102 in order to vary the distance d between the two units 6 and 7 arranged in cascade.

once the desired adjustment position has been reached, the screws 104 can be tightened again so as to keep the frame 100 securely in a fixed position on the frame of the machine as is necessary for the packaging machine to operate correctly.

Of course, it is possible to provide for the longitudinal adjustment of the upstream closure unit 6 or of both the units 6 and 7 rather than just the downstream station 7 (as in the embodiment illustrated). Naturally, if the longitudinal position of an upstream unit 6 which can oscillate, as in the embodiment illustrated, is made sel'ectively variable, its structure may become too complicated so this choice is usually avoided.

The fact that the distance d between the two units 6 and 7 can be varied enables that distance to be adjusted precisely in relation to the dimensions of the articles P to be packaged.

In particular, as already stated in the introduction to the present description, the Applicant has found that with fairly "tall" products P, the most critical condition arises when the distance d between the two units 6 and 7 in cascade coincides with the overall lengthi of the finished package, that is to say (see Figure 2) the distance between the outer end edges of the two f laps of the wrapper, or a whole multiple of that length 1. In these conditions, the two units 6, 7 act on the wrapper almost simultaneously, subjecting it to great stress.

The fact that the position of the downstream station 7 can be adjusted (or, more generally, the fact that the 11 distance d between the two units 6, 7 can be adjusted) means that the machine can be adjusted to allow for changes in the dimensions of articles P to be packaged so that, in any circumstances, it can be arranged to operate in a condition such as that shown by way of example in Figure 3, in which the distance d is not generally a whole multiple of the length 1.

Naturally, if - as in the embodiment illustrated - one unit can oscillate, the aforementioned considerations relating to the distance d refer to the (constant) mean value of that distance since the oscillations (which at any rate are of limited amplitude) "do not themselves have any particular bearing on the embodiment of the invention.

In particular, the condition shown by way of example in Figure 3 may be expressed in mathematical terms as d 0 K1, where K = 1, 2 n.

The ability of the downstream station 7 to move longitudinally is preferably combined with a similar adjbstability---ofthe associated convYor members such as, for example, the output conveyor 106 onto which the packages produced by the packaging machine are transferred. This applies in particular both to the end return roller 108 of the conveyor at the outlet of the unit 7 and to the maintenance of an even tension in the upper pass of the conveyor 106 on which the packaged articles P advance. This is ensured by the formation of a loop in the belt of the conveyor 106 preferably in its lower pass - betwe ' en two return rollers 110, 111, at least one of which (for example, the roller 110 in the embodiment illustrated) is 12 movable longitudinally relative to the frame of the machine substantially in synchronism with the end roller 108.

Any one of the rollers 108 to 111 may be used to drive the conveyor 106 (all according to known principles).

The foregoing remarks relating to adjustability also apply to the unit which is located between the two units 6 and 7 for regulating the movement of the products P.

With regard to the general purposes and function of the regulating unit, reference should once more be made to the description of Italian patent No. 1,208,411 and the corresponding United States patent No. 4,362,673 referred to several times above.

In the embodiment illustrated, the unit 26 is constituted essentially by two units 112, 114 positioned above and below the path along which the products P advance, respectively. Each of the units is constituted, in turn, by a motor-driven belt conveyor with an active pass aligned with the respective facing surface of the wrapper for the products.

In particular, the conveyor 114 has an upper active pass which is intended to form a plane of sliding for the products P, whilst the conveyor 112 has a lower active pass which is intended to constitute a restraining barrier to prevent excessive lifting of the chain of packaged articles P between the units 6 and 7.

In general, the vertical distance between the active passes, which are moved at substantially the same speed 13 of advance as the articles P, is selected so as to be slightly greater than the maximum vertical dimension expected and tolerated for the articles P being packaged.

All this ensures that the advancing articles are guided correctly between the two units 6 and 7, avoiding the risk of their being squeezed or squashed.

Preferably, the lengths of the active passes of the conveyors 114 and 112 should also be variable to allow for changes in the distance d between the units 6 and This can be achieved in at least two different ways.

According to a first solution, an arrangement substantially similar to that used for the belt conveyor 106 is also used for the conveyors 112 and 114, that is, the position of mounting of one of the return rollers between which the active pass of the conveyor extends is made variable: this arrangement may sometimes be too complex both from a structural point of view and because of the limited space available between the two units 6 and 7.

According to another solution, which is currently considered preferable by the Applicant, the conveyors 112 and 114 may be mounted on the frame I with the interposition of respective support members 116 and 118 which are fitted removably to the frame.

The conveyors 112 and 114 can thus be removed from the frame 1 selectively and replaced by substantially similar conveyors having active passes of different lengths.

14 In any case, the correct tensioning of the part of the belt constituting the conveying member of the conveyor can be regulated by an auxiliary tensiorzAng roller such as the roller 119 shown with reference to the upper conveyor 112.

The fact that the distance d between the two units 6 and 7 is selectively adjustable in dependence on changes in the dimensions of the articles P to be packaged may, at least in some cases, involve the need to alter the rotation of the jaws 8, 9, 11 and 12.

As is known, this rotation takes place not at a uniform speed but rather with a general oscillation of its angular velocity so that the jaws rotate slightly faster during their travel along the angular portion of their path in which the respective active members are in contact with the wrapper.

This oscillation of their speed of rotation is imparted to the jaws by gear mechanisms of known type.

The law according to which the speed oscillates can be varied in a particularly effective manner, in dependence on changes in the distance d, and possibly with a temporary change in the phase of the rotation of the jaws when it is detected that there is an absence of one or more articles to be packaged, by means of a gear mechanism which forms the subject of a patent application of even date by the present Applicant.

An absence of one or more articles due to a malfunction or failure of any station upstream is detected upstream of the unit 6 according to widely know principles, for example, by means of an optical sensor.

Naturally, the principle of the invention remaining the same, the details of construction and forms of embodiment may be varied widely with respect to those described and illustrated, without thereby departing from the scope of the present invention.

1

Claims

16 CLAIMS

1. A packaging machine (1) in which articles (P) to be packaged are inserted in a tubular wrapper (S) which is then closed by two closure units (6, 7) arranged in cascade in the general direction of advance of the articles (P), characterised in that it includes means (102) for selectively and permanently varying the distance (d) between the two units (6, 7) arranged in cascade.

2. A machine according to Claim 1, characterised in that the closure units (6, 7) are of the type with contrarotating jaws (8, 9; 11, 12).

3. A machine according to Claim 1 or Claim 2, characterised in that the first closure unit (6) is mounted on the machine (1) in a substantially fixed position whereby the distance (d) is varied by the movement of the other closure unit (7).

4. A machine according to any one of the preceding Claims 1 to 3, characterised in that at least one closure unit (6) has associated oscillating support means which impart a general oscillating movement to the closure unit in operation, the selectively and permanently variable distance (d) being with reference to the mid-point of the oscillation.

5. A machine according to any one of Claims 3 and 4, characterised in that the first closure unit (7) and the other closure unit (6) are arranged upstream and downstream respectively in the direction of advance of the articles to be packaged.

1 A 17 6. A machine according to any one of the preceding claims, characterised in that the distance (d) is varied by the adjustment of the position of at least one (7) of the closure units which carries associated conveyor means (106, 112, 114) which can also be adjusted selectively (110, 112) to allow for the adjustment of the at least one closure unit (7).

7. A machine according to Claim 6, characterised in that the associated conveyor means include a belt conveyor (106) with at least one return roller (108, 116) whose position is selectively adjustable relative to the frame (1) of the machine 'to allow for the adjustment movement of the at least one closure unit (7).

8. A machine according to Claim 6 or Claim 7, characterised in that the conveyor means comprise at least one conveyor (112, 114) mounted on the machine (1). in a selectively removable manner to enable the at least one conveyor (112, 114) to be replaced by a similar conveyor with different dimensions.

9. A packaging machine substantially as hereinbefore described tjith reference to the accompanying drawings.

-1,16 - AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS.

6. A machine according to any one of the preceding claims, characterised in that the distance (d) is varied by the adjustment of the position of at least one (7) of the closure units which carries associated conveyor means (106, 112, 114) which can also be adjusted selectively (110, 112) to allow for the adjustment of the at least one closure unit (7).

7. A machine according to Claim 6, characterised in that the associated conveyor means include a belt conveyor (106) with at least one return roller (108, 116) whose position is selectively adjustable relative to the frame (1) 'of the machine 'tq allow for the adjustment movement of the at least one closure unit (7).

8. A machine according to Claim 6 or Claim 7, characterised in that the conveyor means comprise at. least one conveyor (112, 114) mounted on the machine (1). in a selectively removable manner to enable the at least one conveyor (112, 114) to be replaced by a similar conveyor with different dimensions.

9. A method of operating a packaging machine (1), in which method articles (P) are inserted in a tubular wrapper (S) which is then closed by forming two end flaps having end edges which define the overall length (1) of each finished package, said tubular wrapper (S) being closed by two closure units (6,7) arranged in cascade at a distance (d) from each other in a general direction of advance of the articles (P), wherein the method includes the step of selecting said distance (d) so as not to be equal to said overall length (1) or a multiple thereof.

10. A method according to claim 9, wherein at least one closure unit (S) has associated oscillating support means which impart general oscillating movement to the at least one closure unit (S) in operating, and wherein said distance (d) is selected with reference to the mid-point of the oscillation.

4 1 lot -

11. A packaging machine substantially as hereinbefore described with reference to the accompanying drawings.

12. A method of operating a packaging machine, substantially as hereinbefore described with reference to the accompanying drawings.

Published 1992 at The Patent office Concept House. Cardiff Road. Ne-port. Gwent NP9 1 RH Further copies rna be obtaired jr,,]: Sales Branch. Unit 6. Nine Mile PD,nl. Clk'infelinfach. Cross Keys. xe%-port. ultiplex techniques lid St Mar% Cray Ken, - NPI 7HZ. Printed by M