MXPA98004800A - Packaging unit to produce sealed containers containing food products that can be poured, from a container material pipe - Google Patents

Abstract

The present invention relates to a packaging unit for continuously producing aseptic sealed packages, containing a pourable food product, from a tube made of heat seal packaging material in laminated form, fed along a path of vertical supply, and filled with the food product, the unit is characterized in that it comprises: a first chain conveyor having a number of jaws and defining a first endless way along which the jaws are fed; chain having a number of counter-jaws and defining a second endless track along which the counter-jaws are fed, the first track and the second track each comprising respective work portions adjacent to the tube supply path packing material, and extend substantially symmetrically on opposite sides of the supply path, whereby the jaws cooperate n with respective counter-jaws for clamping the tube in respective cross sections and equally spaced when the tube is advanced along the supply path, first cam guide means along the respective working portions for guiding the jaws; second cam guide means for guiding the counter-jaws; the jaws and counter jaws comprise cam follower means cooperating with the first and second respective cam guide means; the jaws and counter jaws comprise, respectively, heating means for heat sealing the packing material, and pushing means for exerting clamping pressure along a clamping pressure direction for clamping the packing material against the heating means; the counter-jaws comprise each a main body, each main body comprises the cam follower means, the thrust means comprise at least two ap assemblies. pressure in the main body and define a link of the second chain conveyor, the thrust means comprise a pressing element that connects and pressure application assembly and can be moved with respect to the main body in the direction of pressure of clamping, and elastic means interposed between the main body and the pressure element, and which define the clamping pressure

Description

PACKAGING UNIT TO PRODUCE ENV SE-S .qTp.T. TWO THAT CONTAIN ALIMRMTTpTQg PRODUCTS THAT CAN BE VI-IRTE! -, A STARTING FROM U? PACKAGING MATERIAL PIPE DESCRIPTION OF THE INVENTION The present invention relates to a packaging unit for continuously producing aseptic sealed packages, containing pourable food products, from a tube of packaging material. More specifically, the packaging unit according to the present invention provides a way to produce aseptic sealed packages substantially in the form of a parallelepiped. Many food products that can be poured, such as fruit juices, pasteurized milk or UHT (treated at ultra high temperature), wine, tomato sauce, etc. , they are sold in containers made of sterilized packaging material. A typical example of such a container is the parallelepiped-shaped packaging container for liquid or for pourable food products known under the name of Tetra Brik Aseptic (registered trademark), which is formed by folding and sealing a material of packaging rolled into strips. The packaging material REF: 27473 rolled comprises layers of fibrous material eg paper, covered on both sides with thermoplastic material, for example, polyethylene; and the side of the packaged material and finally contacting the food product in the package also comprises a layer of barrier material, for example, an aluminum sheet, which in turn is covered with a layer of thermoplastic material. As is known, packages of the above type are produced in fully automatic packaging machines, in which a continuous tube is formed from the packaging material supplied in the form of a strip. The strip of packaging material is sterilized by the packaging machine, for example, by applying a chemical sterilizing agent such as a hydrogen peroxide solution; followed by sterilization, the sterilizing agent, for example heat-vaporized, is removed from the surfaces of the packaged material; and the packaged material strip sterilized in this way is maintained in a closed sterile environment, and is folded and longitally sealed to form a tube. The tube is filled with the sterilized or sterile processed food product, and sealed in equally spaced cross sections in which packets are then cut into a pillow form, which are then mechanically folded into parallelepiped-shaped packages . Packaging machines of the above type are known, in which sections of the tube are sealed by two jaw units which are moved by respective arms so as to alternately grip the tube in successive sections for sealing. A jaw of each jaw unit comprises an injection heating element for locally melting the thermoplastic material when the jaw unit is clamped on the tube, and in this way the thermoplastic shell is sealed to seal a cross section of the tube. Each jaw unit performs a relatively complex cycle of operations, in which the respective jaws are brought into contact with the tube in an upper station of the packaging machine; and the unit, which firmly holds the tube, is lowered, together with the tube, along the feeding axis of the tube to seal the cross section and then opened in the lower station of the packaging machine. The same cycle, diverted by a time interval corresponding to the output speed of the machine, is also performed by the second unit, so that each container is formed by a portion of the tube that extends between a first seal manufactured by one jaw unit, and a second seal manufactured successively by another jaw unit. Although widely used and with confidence, known machines of the type described above are limited in terms of performance speed, considering the cyclic reciprocating movement of the large masses involved (arms, jaws and respective actuators), the inertia of which limits the speed of performance to a few hundred cycles / hour, above and below which, they are dynamic problems such as damaged operation of the machine. To increase the speed of performance of such machines, continuous packing units have been proposed, which comprise two chain conveyors defining respective endless trajectories and which are respectively placed with numerous jaws and against jaws. The two trajectories comprise respective branches that are substantially opposite and parallel to each other and between which the tube of packaging material is fed.; and the jaws on a conveyor cooperate, along the branches of their respective paths, against the corresponding counter-jaws on the other conveyor for holding the tube in numerous successive cross sections and thus sealing the packages. Continuous chain conveyor systems eliminate, to a certain extent, the dynamic problems and thus increase the maximum performance speeds imposed by the reciprocating systems. Machines of this kind are illustrated, for example, in US-Re 33 467. Although they have been experienced for some time, to the knowledge of the applicant, such machines have failed, even, to find a satisfactory practical application. One of the problems presented by the machines of the above type is the difficulty of controlling with precision and reliability the contact pressure exerted on the packaging material by the jaws and counter-jaws to form the seal, and which is generated by contact between the cams of control fixed to the structure of the machine and respective cam follower members traveling along the respective cams associated with the respective jaws and counter-jaws. Since the contact pressure depends to a large extent on the manufacturing and assembly tolerances, on the wear of the cams and on the respective cam follower members and on the operating temperature, considerable difficulty is encountered in adjusting the machine and maintaining conditions. optimal operation.

The control of the sealing pressure is essential to obtain a reliable production process that ensures that the container is not damaged and thus preserve the aseptic characteristics of the contents.

An object of the present invention is to provide a packaging unit for continuously producing aseptically sealed packages containing pourable food products, and which provides for elimination of the aforementioned drawbacks, typically associated with known machines. According to the present invention, there is provided a packaging unit for continuously producing aseptic sealed packages, containing a pourable food product, from a tube made of a heat sealing packaged material, in the form of a sheet, fed along a vertical supply path; and filled with food product; the unit comprises: a first chain conveyor having numerous jaws and defining a first endless path along which the jaws are fed; a second chain conveyor having numerous counter-jaws and defining a second endless path along which the counter-jaws are fed; the first and second trajectory comprise respective working portions adjacent to the supply path of the packing material tube, and extending substantially symmetrically on opposite sides of the supply path, so that the jaws of the first conveyor cooperate with the counter-jaws for holding the tube in respective spaced apart cross sections; the unit also comprises, along at least the respective working portions, a first cam guide means for guiding the jaws, and a second cam guide means for guiding the counter jaws; the jaws and counter jaws comprise cam tracking means cooperating with the respective first and second cam guide means; and the jaws and counter jaws also comprise, respectively, heating means for heat sealing the packaging material, and biasing means for exerting clamping pressure to hold the packaging material against the heating means; characterized in that the counter-jaws each comprise a main body which in turn comprises a cam follower means and which defines a joint in the second chain conveyor; and biasing means comprising a pressure element positioned towards and movable with respect to the main body in the direction of the clamping pressure, and elastic means interposed between the main body and the pressure element and defining the pressure of subjection.

A preferred non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a perspective view, with parts removed for clarity, of the packaging unit according to the drawings; teachings of the present invention; Figure 2 shows a partial schematic side view of the unit of Figure 1; Figure 3 shows a perspective view of a jaw and the corresponding counter-jaw of the unit of Figure 1; Figures 4 shows a front view of the counter-jaw of Figure 3; Figure 5 shows a section along the line V-V in Figure 4; Figure 6 shows a larger scale detail of Figure 5; Figure 7 shows a middle cross section, with parts removed for clarity, of the jaw and counter jaw in Figure 3, in the clamped position. With reference to Figures 1 and 2, the number 1 indicates the packaging unit that is produced continuously, from a tube 14 of packaging material, aseptically sealed packages 2 containing a pourable food product, such as milk pasteurized or UHT, fruit juice, wine, etc. The tube 14 is formed in a known manner upstream from the unit 1 by longitudinally bending and sealing a strip of heat sealing material, and is filled upstream with the sterilized or sterile processed food product for packaging. The unit 1 comprises a frame 3 (figure 1) defined by two side walls 4, 5 and by two parallel transverse walls 6, 7 rigidly placed between the side walls 4, 5 and defining, with the side walls 4, 5, a opening 8 and two chain conveyors 10, 11 placed on the frame 3 and comprising respectively the jaws 12 (in figure 1 only 1 is shown) and counter-jaws 13 (in figure 1 only 1 is shown) cooperating with each other to interacting with the tube 14 of packaging material fed along a vertical path A through the opening 8.

The conveyors 10 and 11 define trajectories Endless respective P and Q along which the jaws 12 and counter-jaws 13 are fed and which extend respectively around the walls 6 and 7 of the frame 3. The conveyor 10 comprises an articulated chain 15 which extends as far as possible. along the path P; and two drive wheels 16 engaging with, and on both sides of the chain 15 at the lower end of the trajectory P. The jaws 12 are integral part and define alternating joints of the chain 15, and are connected to each other in a manner articulated by pairs of articulations 17. More specifically, each jaw 12 (Figure 3) comprises an elongated main body 20 extending in a direction perpendicular to a path A and parallel to the wall 6, and having projections 21 and 22 of respective ends, each of which has a first and second projecting bolt 23, 24, spaced apart from each other and having respective axes 25, 26, parallel to the main dimension of the body 20. The pivot joints 17 the bolts 23, 24 of the jaws 12 in this manner connect the bolts 23 of a jaw 12 with the bolts 24 of the adjacent jaw.

- ?? - Similarly, the conveyor 11 comprises an articulated chain 27 that extends along the path Q; and two drive wheels 28 which mesh with the chain 27 at the lower end of the path Q. The chain 27 is defined by numerous counter-jaws 13 connected in an articulated manner to each other and described only in detail in so far as they differ from the jaws 12, and using the same numbering system for any of the similar parts or corresponding to those described in relation to the jaws 12. Briefly, each counter jaw 13 comprises a main body 20 having pairs of end bolts 23, 24 of which the links 17 rotate to connect adjacent pairs of counter-jaws 13. Each jaw 12 comprises an induction heating element 29 positioned in the main body 20 in a direction transverse to the path A of the tube 14, and which in turn comprises a pair of parallel, straight, active surfaces 30 and is electrically supplied by a pair of contact bushings 34 which cooperate in a manner Sliding, in use, with the supply rod (not shown) placed in the frame 3 and extending in the region of the trajectory P inside the opening 8.

In opposition to the heating element 29, each counter-jaw 13 comprises a pressure bar 35 (FIGS. 4 and 5), which cooperates with the heating element 29 of the corresponding jaw 12 to hold a cross section of the tube 14 (Figure 2). In a front surface 46 correspondingly facing the jaw 12 in use, the bar 35 comprises two bands 36 of relatively flexible elastomeric material, which cooperate with the packaging material in opposition to the active surfaces 30 of the heating element 29. The jaws 12 and counter-jaws 13 each comprise a respective control device 37 - not part of the present invention, and therefore not described in detail - to control the volume of the container 2 as it is produced. The movement of the jaws 12 and counter-jaws 13 is controlled by respective pairs of cams 50, 51 placed on the walls 6, 7 of the frame 3 and cooperating with respective pairs of rollers 52, 53 on the jaws 12 and counter-jaws 13. More specifically, and as shown in the figure 3, the jaws 12 and counter-jaws 13 each comprise a first pair of rollers 52, 53 freely positioned within the end portion 21 of the main body 20, and a second pair of rollers 52, 53 freely positioned within the body. the end projection 22 of the main body 20; and the projections 21, 22 each comprise a pair of seats 54, 55 parallel, side by side, formed on the rear side (i.e., the facing side away from the heating element 29 or pressure bar 35) and extending in a direction perpendicular to the axes 25, 26 of the pins 23 , 24 and substantially parallel to the plane defined by the axes 25, 26. The roller 53 in each pair is housed within a respective outer seat 54 (i.e., closest to the end of the body 20) and placed in a respective pin 23; and the roller 52 in each pair is housed within a respective inner seat 55 and is placed in a respective pin 24. The wall 6 (figure 1) is placed with two pairs of cams 50, 51 with which the respective pairs of rollers 52, 53 of the jaws 12 cooperate in a rolling manner; and similarly, the wall 7 is placed with two pairs of cams 50, 51 with which the respective pairs of rollers 52, 53 of the counter-jaws 13 cooperate. The cams 50, 51 comprise substantially U-shaped portions 50a, respectively, which they extend around the abutting edge of the respective walls 6, 7 to define, for the respective chains 15, 27 of the respective conveyors 10, 11 driving wheels 16 and 28 opposed to the transmission; and the respective portions 50b, 51b extend vertically along the respective walls 6, 7 within the opening 8. The portions 50a, 51a define path portions Pl, Ql along which the jaws 12 and counter-jaws 13 they approach and make contact with the tube 14 of packaging material; and the portions 50b, 51b define portions P2, Q2 of parallel, facing trajectory, along which the jaws 12 and counter-jaws 13 are kept in contact under pressure to form the seals defining the containers 2. The cams 50, 51 they release the respective chains 15, 27 in respective portions P3, Q3 of trajectories P and Q downstream of the respective drive wheels 16, 28. Along the portions P3, Q3, the chains 15, 27 cooperate with the respective pairs of tensioners 56 so as to tension the chains so as to ensure that the rollers 52, 53 of the jaws 12 and counter-jaws 13 remain in contact in relation to the respective cams 50, 51. Each tensioner 56 comprises a mobile shoe 57 articulated about a horizontal axis to a support fixed to the wall 6 or 7; and a spring 59 interposed between the shoe 57 and the wall 6 6 1. On the facing face away from the wall 6 or 7, the shoe 57 comprises two laterally rolling tracks 60, 61 which, by virtue of the spring 59, cooperate respectively with the rollers 52 and 53 of the jaws 12 or counter-jaws 13. according to the present invention, the pressure bar 35 of each counter-jaw is to be placed on the main body 20 so as to allow a limited amount of movement in a direction perpendicular to the plane defined by the axes 25, 26 of the bolts 23, 24; direction which, indicated by X in FIGS. 5 and 7, defines, in use, the direction in which the pressure is applied by each jaw / counter-jaw pair in the tube 14. Two bolts 65 with respective axes parallel to the X direction, in particular screwed, projected towards the rear of the bar 35, at the opposite ends of the front surface 46 of the bar, and which are coupled loosely with respective positioning holes 66 formed in the body 20. principal . The bar 35 is placed in the main body 20 by means of interposition of two connection assemblies 67 to generate, in use, a reaction pressure in the direction X to keep the bar 35 against the respective jaw 12. The mounts 67 are located at opposite ends of the bar 35, along the front surface 46, and in FIG. 6 a larger scale section of one of the mounts 67 is shown, which is referenced in the following . Each assembly 67 substantially comprises a guide shaft 70 having an axis parallel to the X direction and which is positioned with wide radial width through a substantially cylindrical through cavity 71 in the main body 20, and comprising a flange 72 of end positioned with the rear part of the body 20 and by a number of screws 73 around the cavity 71. The cavity 71 houses a highly rigid helical spring 75 made of wire of quadrangular section and compressed between the rim 72 and the element 76 in the form of cup which can be slid axially loosely within the cavity 71 and which is connected axially and radially with the bar 35. More specifically, the element 76 comprises an annular base wall 77 axially cooperating with the spring 75, and a cylindrical wall 78 housed loosely within the cavity 71; and a wall 77 comprising a tapered inner blade edge 79 cooperating in a sliding manner with the shaft 70. The cavity 71 comprises a circumferential groove 80 that houses an annular seal 81, which cooperates in a sliding manner with the cylindrical wall 78 item 76; and the cavity 71 and the element 76 are suitably filled with lubricating grease. Within the cylindrical seat 83 of the pressure bar 35 a smaller diameter end portion 82 of the shaft 70 is accommodated via the interposition of a bushing 84 of elastomeric material. The bushing 84 is packed between a flange 85 of the tree 70 and a stop washer 86 coaxial with the shaft 70 and which is positioned at the end of the end portion 82 of the shaft. The peripheral edge of the washer 86 cooperates axially with an annular seat flange 87 of the bar 35 to hold the flange 87 axially against the bushing 84 and maintain the bar 35 against the element 76 in opposition to the spring 75. More specifically, the The base wall 77 of the element 76 defines a positioning collar 90 which engages the seat 83 of the pressure bar 35. Unit 1 works as follows. The conveyors 10, 11 are rotated in known manner in opposite directions, as indicated by the arrows in Figure 2 so that, from the end of the portions Pl, Ql of the respective paths P, Q and along the respective portions P2, Q2, the respective jaws 12 and counter-jaws 13 cooperate with the tube 14 of the packaging material according to a movement defined by the profiles of the cams 50, 51.

After a first stage in which the tube 14 is brought into contact and gradually compressed, and the packaging material is folded locally to form a flat seal strip 88 extending transversely to the tube 14, the jaws 12 and counter-jaws 13 they respectively reach straight positions 50b, 51b of cams 50, 51 (FIG. 2) where the maximum clamping pressure is applied to the tube 14 and a heating element 29 of each clamp 12 is provided to form the heat seal. The distance between the portions 50b and between the portions 51b of respective substantially homologous cams 50 of the jaws 12 and counter-jaws 13 is constant over most of the portions, and is thus selected to compress slightly and deform the springs 75 of the counter-jaws 13. Such compression is made possible by the axial elastic stiffness of the bushings 84 of elastomeric material which is considerably less than that of the springs 75 so that, when the rod 35 cooperates with the heating element 29 of the corresponding clamp 12 for clamping the packaging material, the pressure to which the rod 35 is subjected in the clamping direction X axially compresses the bushings 84, and is transmitted almost completely to the springs 75 via the elements 76 in - respective cup shape.

As the springs 75 deform only to a very small extent, the clamping pressure exerted on the packaging material is determined substantially by the preload of the springs 75. The advantages of the unit 1 according to the present invention will be apparent from of the following description.

In particular, the assemblies 67 that elastically connect the pressure bars 35 to the respective counter-jaws 13 provide, in a linear manner, accurate and reliable control of the clamping pressure exerted on the packaging material. Further, by virtue of the inner blade edges 79 and the relatively flexible elastic bushings 84 that allow the cup-shaped elements 76 to oscillate on the shafts 70, the assemblies 67 allow the rod 35 to adapt its position to some extent, although limited, so that, even in the case of minor placement errors of the bar 35, due to the machining and assembly tolerances, the bar 35 exerts uniform pressure throughout the entire sealing portion. Finally, the elastic bushings 84 provide the elimination of sliding connections between each bar 35 and the respective shafts 70 and thus avoid, in combination with the seal 81, the infiltration of the interior cavity 71 of the external agents, particularly liquids, the which can oxidize in spring and result in the formation of accumulations, thereby damaging the efficient operation of the elastic connection assemblies 67. Clearly, changes can be made to unit 1 as described and illustrated herein, however, without departing from the scope of the claims. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates. Having described the invention as above, property is claimed as contained in the following:

Claims (8)

I ^ IVINDIC? CIONS

1. A packaging unit for continuously producing sealed and aseptic packages, containing a pourable food product, from a tube made of a heat-sealed packaging material in the form of a sheet fed along a vertical delivery path, and filled with the food product; the unit comprises: a first chain conveyor having several jaws and defining a first endless path along which the jaws are fed; a second chain conveyor having several counter-jaws and defining a second endless path along which the counter-jaws are fed; the first and second trajectories comprise respective working portions adjacent to the supply path of the tube of packaging material and extend substantially symmetrically on opposite sides of the supply path so that the jaws cooperate with the respective counter-jaws to hold the tube to evenly spaced cross sections, respectively; the unit also comprises, along at least the respective working portions, first cam guide means for guiding the jaws, and second cam guide means for guiding the counter jaws; the jaws and counter jambs comprise cam followers which cooperate with the first and second respective cam guide means; the jaws and counter-jaws also comprise, respectively, heating means for heat sealing the packaging material, and biasing means for exerting clamping pressure to hold the packaging material against the heating means; characterized in that the counter-jaws each comprise a main body which in turn comprises the cam follower means and which define an articulation of the second chain conveyor; the pushing means comprises a pressure element positioned and movable with respect to the main body in the direction of the clamping pressure, and elastic means interposed between the main body and the pressing element and defining the clamping pressure. The unit according to claim 1, characterized in that the pressure element is in the form of an elongated bar extending in a direction perpendicular to the supply path of the tube of packaging material; the pushing means comprises a pair of elastic connecting assemblies having respective elastic means and connecting the pressing element to the main body near the respective opposite ends of the pressing element. The unit according to claim 1 or 2, characterized in that the elastic connection assemblies each comprise a substantially closed seat that houses an elastic means; and the sealing means to prevent the infiltration of external agents into the seat. The unit according to claim 2 or 3, characterized in that the elastic connection assemblies each comprise a guiding element for guiding the pressure element and which is placed to maintain the body and extends in the direction of the clamping pressure; and positioning means for positioning the pressure element with respect to the guide element and allowing a small amount of misalignment. The unit according to claim 4, characterized in that the positioning means comprises a flexible element connected to the pressure element and the guide element in the direction of the clamping pressure, and which is deformable to allow the element of pressure is moved relative to the guide element without mutually sliding contact surfaces. The unit according to claim 4 or 5, characterized in that the guide element is a shaft having an axis parallel to the direction of the clamping pressure, which extends through the seat housing and the elastic means and which is rigidly fixed to the main body; the elastic means comprises a spring coaxial with the shaft; and the positioning means comprises a cup-shaped element connected to the pressure element and having a base wall axially cooperating with the spring and a side wall sliding within the spring seat housing. The unit according to claim 6, characterized in that the base wall of the cup-shaped element comprises an inner tapered blade edge sliding on the shaft. The unit according to claim 6 or 7, characterized in that the means is sealed comprises an annular seal housed in the housing and cooperating in a sliding manner with the side wall of the cup-shaped element.