NL9101391A - PACKAGING DEVICE, IN PARTICULAR FOR FORMING SO-CALLED "FLOW-PACK" PACKAGING AND METHOD OF OPERATION THEREOF. - Google Patents

Description

Extract

An automatic packaging device (1), especially for food products such as sweets, in which the objects to be packaged (p) are placed in a tubular wrapper (s) which is then closed by two sealing members (6, 7) which are arranged in cascade in the general locomotive arrangement of the objects (p) includes means (102) for optionally permanently varying the distance (d) between the two members (6, 7) arranged in cascade.

(figure 1)

Packaging device. in particular for forming so-called "flow-pack * 1 packs" and for their operation.

The present invention relates to packaging devices and in particular to packaging devices which can form wrappers of the kind commonly referred to as "flow packs", "form fill seal", or simply "FFS" packages.

More particularly, the present invention relates to a packaging device comprising two cascaded sealing members intended for closing the wrapper, the upstream member having the function of closing the tubular wrapper by forming of sealing areas (welds) separating the successive articles to be packaged, while the downstream member has the function of further strengthening the weld and also of cutting the wrapper to separate the successive packages thus formed.

Such packaging devices are well known in the art, as is apparent, for example, from U.S. Pat. Nos. 2,280,405, 3,007,295 and 3 * 241,288, from European Patent Application 0,055 * 211, and from Italian Patent No. 1,208,411 and the corresponding U.S. Patent No. 4,862 .673. the last two patents of which are in the name of the applicant.

Until now, such packaging devices have mainly been used to form flow-pack wrappers for mainly flat objects, which are objects whose height (indicating the size in the direction in which the tubular wrappers are pressed shut) is considerably less than their length (the latter term being the dimension in the direction of travel of the articles in the packaging device, which is the direction in which the sheet or foil for forming the tubular wrapper is usually fed).

Under these circumstances, assuming that the two sealing members are properly synchronized (which can be easily achieved by known means), the distance between the areas in which the two cascaded sealing members operate is largely irrelevant in terms of the quality of the final product.

Applicant has found that this is not the case when flow-pack wrappers are to be formed for rather "long" objects, which are objects whose height is not an insignificant part (1 / 3-1 / 4) of their length, and this is the case, for example, for wrappers which contain vertically stacked biscuits or crackers in the packaging.

As a result, under some operating conditions (that is in the case of finished windings of a certain length), the two cascaded sealing members can act simultaneously on the wrapper, resulting in considerable longitudinal stress in the wrapper. This can pose significant problems during operation, particularly regarding the risk of the weld formed at the upstream member (usually by locally melting the plastic material from which the wrapper is formed or from a film of fusible material added to a metal wrapper) may reopen as a result of separating the portions of a tubular wrapper brought into contact in the first sealing member. Even if the parts of the weld do not open again, the overall quality of the wrap closure may be adversely affected.

In theory, this problem could be solved in a simple manner by controlling the action of the closing members so that they never work simultaneously on the wrapper being closed.

In practice, it has been found that this principle cannot be applied in general because the relative phase of the movement of the two closing members cannot be freely chosen, but generally depends on a number of physical parameters of the installation and, in particular, on the dimensions of the objects and the final dimensions of the manufactured packaging.

There is thus a desire to provide means which can solve the above-mentioned problems in a general manner, but are completely free from the physical limitations of the systems described above.

In accordance with the present invention, this object is achieved by a packaging device having the features set out in the appended claims.

In summary, in the packaging device according to the invention, the distance between the areas in which the two closing members operate in cascade arrangement, that is the distance between the two closing members in the direction of movement of the objects, can be varied optionally and permanently.

It is noted that the term "permanent" as used in the present description and in the appended claims particularly refers to the fact that, in the device according to the invention, the distance between the two cascaded shut-off members can be optionally varied (for example, by adjusting - according to the requirements to be explained later - the total length of the wrappers to be formed) while keeping the adjusted position constant as long as no other adjustment is made for treating objects of different shapes.

This accurately distinguishes the solution of the present invention from the solution of the well-known Italian Patent No. 1,208,411 and the corresponding U.S. Patent No. 4,867,673. according to which patents the distance between the two cascaded sealing members is - to a limited extent - periodically varied with a frequency corresponding to the frequency with which the individual objects travel, so that the downstream sealing member has the chance to follow the wrapper "while realizing the sealing and cutting the wrapper to separate the individual packages.

The invention will now be described, purely by way of non-limiting example, with reference to the annexed drawings, in which: figure 1 is a vertical cross-section in longitudinal direction, part of a packaging device according to the invention and, figures 2 and 3 show the operating requirements of the accurately depict the arrangement of Figure 1.

Figure 1 substantially corresponds to Figure 3 of the drawings appended to Italian Patent No. 1,208,441 and the corresponding U.S. Patent No. 4,862,673

Therefore, the general description of the operating principle of the packaging device of these known patents will not be repeated here, except to the extent necessary for the understanding of the invention.

It should be briefly reiterated that the packaging device, generally designated by the reference numeral 1, is intended to form packages of the type currently known as "flow packs", each of which is an article or group of articles (so-called "multiple packaging ").

The packages are formed from a continuous flow of products P.

which moves from right to left in Figure 1. According to well known standards, a continuous tubular wrapper is formed (by known means, not shown in more detail) from a sheet of plastic material, or metallic material covered with a film of plastic material, which is unwound from a feed station not shown in the drawings, while the objects P are introduced into the wrapper at uniform intervals (in this case, single-piece packages are shown for clarity).

The continuous hose with the objects P therein regularly spaced is advanced to a sealing station 5 which has the primary function of flattening the tubular wrapper in the space between two consecutive objects P to form sealed areas in that space around the individual seal objects P in a sealing manner. The wrapper is then subjected to a subsequent sealing and cutting operation which leads to the separation of the packages.

In the exemplary embodiment shown in Figure 1, the station 5 has two assemblies or members 6 and 7 which have rotating jaws and are arranged upstream and downstream respectively in the direction (from right to left) in which the objects P travel through the device 1.

The downstream member 7 comprises two identical rotating jaws, an upper jaw 8 and a lower jaw 9. Each jaw substantially comprises a shaft 8a, Sa rotated by drive means (not shown) and on which one or more active members, 8b 9b (two in the exemplary embodiment shown) are mounted, which members carry associated heaters, not shown.

In this particular embodiment, each jaw 8 and 9 has a pair of active members 8b, 9b which are diametrically opposed and whose free ends, which are substantially rounded and may have grooves for gripping the wrapper, carry cutters (knives) intended to cooperate with each other to reinforce the weld initially formed by the upstream member 6 (in a manner as will be described hereinafter) and to cut the weld region between successive objects to separate individual packages.

The shafts 8a, 9a are connected in a known manner to a gear mechanism, whereby they rotate in opposite directions. The operative members 8b, 9b thus perform circular movements in opposite directions so that one of the active members 8b of the upper jaw 8 is lowered from time to time to cooperate with an upwardly moving active member 9b of the lower jaw 9 so that the wrapper is cut and the two packages are separated. The active members 8b and 9b have knives 10 for this purpose. When they come into contact with each other, they cut the wrapper softened by the heaters in the jaws.

However, the function of the upstream member 6 is to preform the weld region cut by the downstream member 7. To form the welding area, the area of the tubular wrapper between two successive articles B is flattened while the wrapper is simultaneously heated so that the two sides or parts of the wrapper that are pressed together are welded together.

The member 6 includes for this purpose an upper jaw 11 and a lower 12, each of which is formed by a rotating shaft 11a, 12a on which respective active members 11b, 12b with rounded free ends are mounted, and which are optionally provided with gripping grooves of the wrapper.

The upper jaw 11 of the member 6 is essentially the same as the jaws 8 and 9 of the member 7, except that the jaw 11 (like the jaw 12) is not provided with the blades 10 present on the jaws of the organ 7 *

The active members 11b, 12b of the jaws 11 and 12 also have heaters (not shown) to heat the parts of the active members 11b, 12b intended to act on the wrapper so that the two parts of the the wrap caught between the two jaws 11 and 12 during sealing, local melting and subsequent welding.

The lower jaw 12 differs from the other jaws 8, 9. 11 in that, in addition to having slightly larger active members 12b, it also has a different number of active members, with three active members selected at an angle of 120 °.

In addition, the jaws 11 and 12 of the member 6 are mounted on the frame of the device 1 interposing an reciprocating or swinging support structure 13 moved by a crankshaft-with-groove coupling mechanism 14.

As described in detail in Italian Patent No. 1,208,421 and the corresponding U.S. Patent No. 4,862,673 (which provides a more complete description), the function of the mechanism 14, which is connected to the support structure 13 via a transmission rod 30, is causing reciprocation of the structure 13, and thus reciprocation of the jaw 11 with respect to the jaw 12 at different bi-directional speeds, the forward swing (i.e. movement in the direction through which the upper jaw 11 is moved towards the cutter 7) is faster than the swing in the opposite direction.

This reciprocation allows the upper jaw 11 to follow the region of the tubular wrapper between two successive objects "P *" so that it can maintain contact with it for a sufficient length of time under all conditions so that the wrapper is sealed and on the is properly sealed.

More specifically, in the solution of known Italian and U.S. Pat. Nos. 1,208,441 and 4,862,673, the structure 13 moves back and forth around a substantially fixed position actually defined by the axis of rotation X12 of the axis 12a of the lower mouth 12.

The jaws 8 and 9 of the downstream member 7 are also arranged in positions which are substantially fixed relative to the frame of the device 1, except that only the relative positions of the jaws can be accurately adjusted and, to a limited extent, relatively pivoted from the pelvis can take place during their movement to avoid jamming.

However, the main feature of the device of the present invention is that the sealing member 7 located downstream (i.e., the jaws 8 and 9 and their support frame, which is generally designated 100) is mounted on the structure of the device 1 in such a manner that it can move horizontally.

For example, in a presently preferred embodiment, the frame 100 is mounted on a set of prismatic guides 102 running in the longitudinal direction of the device (in the direction of advancement of the objects P and under the lower jaw).

There may be two guides 102 at opposite sides of the path of the articles P, or there may be a greater number of guides.

The frame 100 is held on the guides 102 by clamping means, such as screws 104 or the like, which can be selectively loosened to allow the frame 100 to slide longitudinally over the guides 102 so that the distance d between the two cascaded members 6 and 7 can be varied.

Once the desired adjustment position has been reached, the screws 104 can be re-tightened so that the frame 100 is held securely in a fixed position on the frame of the device, which is necessary for the packaging device to operate properly.

Of course, it may also be provided that the upstream sealing member 6, or both members 6 and 7, may be longitudinally adjustable, instead of the downstream only member 7 (as shown in the embodiment). Of course, if the longitudinal position of an upstream member 6 that can reciprocate, as in the illustrated embodiment, can be varied optionally, its construction will be too complicated, so that this selection is usually avoided.

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

In particular, as already indicated in the introduction to the description, the applicant has discovered that with rather long objects P, the most critical situation arises when the distance d between the two cascaded members 6 and 7 corresponds to the total length L of the finished package, which means (see Figure 2) the distance between the outer end edges of the two flaps of the wrapper, or a multiple of whole digits of that length L. Under these conditions, the two members 6, 7 are almost simultaneously acting on the wrapper, subjecting it to high loads.

The fact that the position of the downstream member 7 can be adjusted (or, more generally, the fact that the distance d between the two members 6, 7 can be adjusted) means that the device can be adjusted so that changes in the size of the articles to be packaged P may be allowed, so that, under all circumstances, work can be ensured under conditions as shown by way of example in Figure 3, the distance d not being approximately a multiple of integers of the length is L.

If - as in the illustrated embodiment - a unit can move back and forth, the above considerations regarding the distance naturally refer to the (constant) mean value of that distance because the reciprocating movements (which under all circumstances have a limited amplitude) do not themselves have any particular influence on the embodiment according to the invention.

In particular, the circumstance shown by way of example in Figure 3 can be summarized in matematic quantities as

The possibility that the downstream member 7 can move in the longitudinal direction is preferably combined with a corresponding adjustability of the associated conveying members such as, for example, the discharge conveyor 106 on which the packages produced by the packaging device are conveyed. In particular, this relates both to the conveyor end return roller 108 at the dispensing end of the member 7 and to maintaining an even pull in the upper portion 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 part - between two return rollers 110, 111, at least one of which (e.g. the roll 19 in the illustrated embodiment) is movable longitudinally relative to the frame of the device, substantially synchronous with the end roller 108.

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

The foregoing remarks regarding adjustability also concern the unit located between the two members 6 and 7 for controlling the movement of the objects P.

With regard to the general purpose and function of the control unit, reference is again made to the description of Italian Patent No. 1,208,411 and the corresponding U.S. Patent No. 4,362,673 referred to several times above.

In the embodiment shown, the unit 26 is essentially formed by two units 112, 114 which are positioned above and below the path along which the objects P travel. Each of the units, in turn, is formed by a motor-driven belt conveyor with a conveyor aligned with the respective face of the wrapper facing the products.

In particular, the conveyor 114 has an upper transport part which is intended to form a sliding surface for the objects P, while the conveyor 112 has a lower transport part which is intended to form a boundary to prevent the chain of packaged objects P between the members 6 and 7 is lifted too much.

In general, the vertical distance between the active parts, which move at substantially the same speed as the speed of movement of the objects P, is chosen such that it is slightly greater than the maximum expected permissible and vertical dimensions of the objects to be packaged P.

All this ensures that the moving objects are properly guided between the two members 6 and 7, avoiding the risk of being compressed or flattened.

The length of the active parts of the conveyors 114 and 112 should preferably also be adjustable, so that variations in the distance d between the members 6 and 7 are possible.

This can be accomplished 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, adjusting the mounting position of one of the return rollers between which the active part of the carrier is running. However, this arrangement can sometimes be too complex, both in terms of the construction to be realized and due to the limited space available between the two members 6 and 7

According to another solution, which is presently preferred by the applicant, the conveyors 112 and 114 can be mounted on the frame 1 with the interposition of respective support members 116 and 118 detachably attached to the frame.

The conveyors 112 and 114 can thus optionally be removed from the frame 1 and replaced by substantially corresponding conveyors with active parts of different lengths. In any event, the proper pulling force of the portion of the belt that forms the conveying member of the conveyor may be controlled by a pull-applying auxiliary roller such as the roller 119 shown in conjunction with the upper conveyor 112.

The fact that the distance d between the two members 6 and 7 can be optionally adjusted depending on variations in the dimensions of the articles to be packaged may, at least in some cases, cause the need for the rotation of the jaws 8, 9. 11 and 12.

As is known, this rotation does not take place at a uniform speed, but mainly at a change in its peripheral speed so that the jaws rotate slightly faster during their movement along the corner portion of their path in which the respective active members are in contact with the wrapper .

This change in their rotational speed is transmitted to the jaws by a known gear-wheel mechanism.

The manner in which the speed changes can be varied in a particularly effective manner depending on changes in the distance b, and possibly with a temporary change in the phase of the rotation of the pelvis when it is determined that one or more articles to be packed are absent , using a gear mechanism that is the subject of applicant's patent application having a corresponding priority date.

The absence of one or more objects due to an erroneous operation or failure of any station located upstream may be determined upstream of the member 6 according to well-known principles, for example by means of an optical observer.

Of course, while maintaining the principle of the invention, the construction details and embodiments can be varied from the described and shown embodiment without departing from the essence of the present invention.

Claims (8)

Packaging device into which articles to be packaged are placed in a tubular wrapper which is then sealed by two sealing members cascaded in the general locomotive device of the articles, characterized in that the packaging device (1) comprises means (102) for selectively and permanently varying the distance (d) between the two cascaded members (6, 7) Device according to claim 1, characterized in that the sealing members (6, 7) are of the type with counter-rotating jaws (8, 9; 11, 12). Device according to claim 1 or 2, characterized in that the first sealing member (6) is arranged in a substantially fixed position on the device (1), the distance (d) being varied by the movement of the other sealing member ( 7). Device according to any one of the preceding claims 1 to 3, characterized in that at least one sealing member (6) has associated reciprocating supporting means which moves the operating sealing member in a substantially reciprocating movement, the selective and permanently variable distance (d) is referenced to the center of the reciprocating motion. Device according to one of claims 3 or 4, characterized in that the first sealing member (7) and the other sealing member (6) are arranged upstream and downstream respectively in the direction of travel of the objects to be packaged. Device according to any one of the preceding claims, characterized in that. that the distance (d) is varied by adjusting the position of at least one (7) of the closing members (6, 7) carrying associated conveyor means (106, 112, 114) which can also be adjusted optionally (110, 112) so that at least one sealing member (7) can be adjusted. Device as claimed in claim 6, characterized in that the associated conveyor means are provided with a belt conveyor (106) with at least one return roller (108, 116), the position of which can be selectively adjusted relative to the frame (1) of the device so that the adjustment movement of at least one sealing member (7) is possible. Device according to claim 6 or 7 *, characterized in that the conveyor means comprise at least one conveyor (112, 14) mounted on the device (1) in a selectable removable manner such that at least one conveyor (112, 114) can be replaced by a corresponding conveyor with other dimensions.