ES2226032T3 - TRAINING UNIT AND HERMETIC CLOSURE TO PACK VERTIBLE FOOD PRODUCTS. - Google Patents

Abstract

A forming and sealing unit (1) for producing aseptic sealed packages from a tube (2) of packaging material filled with a pourable food product, the unit having a fixed structure (3); a pair of forming assemblies (5, 5') interacting alternately and cyclically with the tube (2) of packaging material, and in turn having respective slides (6) movable vertically and in reciprocating manner with respect to the fixed structure (3), and respective pairs of jaws (7) having sealing means and movable between an open position and a closed position in which the sealing means cooperate with the tube (2) of packaging material; a first pair of control rods (15) for controlling the movement of the slides (6); and a second pair of control rods (16) for controlling the opening and closing movement of the jaws (7); the control rods (15, 16) being activated independently by respective servomotors (20, 21, 20', 21') controlled by a programmable control unit (60). <IMAGE>

Description

Training and sealing unit for pack pourable food products.

The present invention relates to a unit of formation and sealing for a packaging machine for pack pourable food products.

Machines for packaging products are known pourable food, such as fruit juice, wine, sauce long-lasting or pasteurized tomato, milk (UHT), etc. in the which containers are formed from a continuous tube of packaging material defined by a sealing band longitudinally.

The packaging material has a structure of multiple layers comprising a layer of paper material coated on both sides with layers of heat-sealable material, by example polyethylene. For aseptic product packaging preserved such as UHT milk, the packaging material comprises a layer of barrier material defined, for example by a sheet of aluminum, which is superimposed on a layer of material heat sealable plastic and is in turn coated with another layer of heat-sealable plastic material that defines the inner face of the container that comes into contact with the food product.

Aseptic containers are produced by unrolling the band of material to pack a roll and through a aseptic chamber, in which it is sterilized, for example, by applying a sterilizing agent such as hydrogen peroxide, which is subsequently evaporated by heating, and / or subjecting the material for radiation wavelength and intensity packaging appropriate. The sterilized band is then folded into a cylinder and closes hermetically longitudinally to form a known way, a tightly sealed tube longitudinal vertical continuous. That is, the material tube for packaging forms an extension of the aseptic chamber, and is filled continuously with the pourable food product and fed to a formation and sealing unit (transverse) for form the individual containers, and that grabs the tube between the pair of jaws to seal the tube transversely in pillow-shaped containers.

Pillow-shaped containers are separated cutting the seal portion between the containers, and transfer then to a final folding station where they are mechanically folded in its final form.

EP-BO 091 712 illustrates and describes a unit for forming and sealing of the type described above, in which the alternative movement of the jaws is controlled by a cam system. That is, the system comprises an electric motor which couples the drive shaft, for each pair of jaws, with two cams with appropriately differentiated profiles. By means of respective oscillating arms, the cams control the axial alternative movement of the respective vertical rods, one of which is connected to a slide that supports the jaws to which the jaws are articulated; while the other rod extends through the slide, without being functionally connected to it, and controls, by means of articulated arms, the opening and closing movement of the
jaws

Two training skirts that look at each other they are articulated to the respective jaws in each pair, and are mobile between an open position, within which they are pushed by a elastic medium, and a closed position in which they are coupled to define a space that defines the shape and volume of the container that is It will form. Training skirts are closed by fixed cams to the machine frame and that interact with the respective rollers carried by the skirts. The configuration is described specific to the training skirts, for example, in the EP-B-O 460540.

At the same time, the compressed tube portion between the jaws closes tightly transversely by heating means, for example induction or ultrasonic, transported by the jaws; and, once the hermetic closure, a cutting machine is activated to cut the tube of packaging material along the center of the portion hermetically sealed and thus separate a container in the form of pillow from the bottom end of the tube. Since the lower end is tightly closed transversely, the jaws, when they reach the central position of neutral bottom, can be opened to avoid interfering with a portion tube top. At the same time, another pair of jaws, actuated in the same way, it moves down from the central position of top dead center, and cutting operations are repeated and hermetic closure, formation / grip mentioned above.

Although extremely satisfactory and reliable, even to the point of requiring very little maintenance yet After many years of service, type machines described above have various disadvantages, particularly in terms of adaptability to produce changes and the limited degree in which you can correct the position of the designs, according to explain below.

Machines of the aforementioned type of in fact the production of packaging in various ways and sizes, although only at the expense of substantially the reconstruction of some machine parts and replacement of others many, resulting in considerable costs and inactivity time.

The document EP-A-O 140 280 describes a device for producing containers that contain a product pourable food, in which displacement is controlled vertical of the slides, via a swing arm, by a motor impeller to regulate the amount of displacement. This solution provides a certain amount of device regulation to produce containers of different heights, although from the same section transverse, so that any change in the configuration of the Packaging also implies substantial alterations to the machine.

To minimize downtime of the machine, therefore, there is a demand in this particular field for a training and sealing unit that provides no only the height of regulation quickly of the package, but also the packaging regulation configuration as required, to change, for example of a container of a width and depth determined to one of width and / or greater or lesser depth, or from from a square corner container to a beveled corner container in the shortest possible time.

Another technical disadvantage of training units and hermetic closure lies in the system called "correction of design".

Since the band of packaging material usually includes a series of images or printed designs equally spaced over the portions that eventually define the outer surfaces of the containers, the band must thereby supply the formation and sealing unit because the formation of the container, hermetic closing and operations of cut are "recorded" accurately with respect to succession of designs. In actual use, however, even though the designs are equally spaced, the position of each design with respect to the jaws in the formation and sealing unit can vary due to the variable deformation of the packaging material by the mechanical pressure exerted by the jaws, or due to the pulsation pressure of the pourable food product within the tube of the material for packaging, so that a device is required to correct the position of the designs.

In modern packaging machines, such device comprises an optical detector to detect the position of a bar code on the package; and a control unit for Compare the detected position with a theoretical position.

Each pair of jaws is provided with a pair of extraction elements to pull the material tube for packaging, and which are mobile with respect to the jaws for form skirts at the bottom and top corners of the container in pillow shape When detecting an error in the design position, the control unit regulates the speed of the motor that supplies the packaging material band, and, if this correction is not sufficient, the extraction elements are also controlled to slightly increase or decrease the traction exerted on the packed material The previous operation is repeated until the design position matches the theoretical position, in which case, any of the containers produced in the meantime must be Rejected. Sometimes, even this method fails to ensure the correct positioning of designs, such as when replace the roll of the packaging material with one in which it is Different the distance between design points. In which case, it you must stop the machine and manually reset the distance between Design points of the new roller.

A further object of the present invention, by Therefore, it is to provide a training and sealing unit which allows quick effective correction to minimize the number of rejections and eliminate the downtime involved in manually reset the machine.

The document EP-A-0764580 describes a machine to produce bags from a tube of packaging material, which includes a unique welding device for welding the cross seams of the bags defined by a pair of welding jaws. The welding device is movable to along a first direction parallel to the direction of tube feeding by means of a first servomotor, and both jaws are movable along a second direction perpendicular to the feeding direction of the tube, to open and close the welding device, by means of a second servomotor; the two servomotors are controlled by a unit of control.

Therefore, this document does not indicate the problems related to the control of packaging machines high speed food product provided with two units of airtight seal, each including a pair of locking jaws airtight.

According to the present invention, the objects previously mentioned are achieved by a training unit and hermetic seal according to claim 1.

A non-limiting, preferred embodiment of the The present invention will be described by way of example with reference to the accompanying drawings, in which:

Figures 1 and 2 describe a front view and side respectively of a training and closing unit Airtight for a machine for packaging food products vertibles, as set forth in the present invention;

Figure 3 shows a partial side view in a larger scale of the unit of figures 1 and 2 in a condition different operation;

Figure 4 shows a perspective view of a drive unit assembly;

Figure 5 shows an exploded view in perspective of a transmission unit of the assembly of the figure 4;

Figures 6 and 7 show a side view and front respectively of a detail of the transmission unit of Figure 5

The number 1 in figures 1 and 2 indicates in its set a training and sealing unit for a machine (not shown) for packaging pourable food products, such as pasteurized or UHT milk, fruit juice, wine, etc.

Unit 1, in particular, intended for produce tightly sealed aseptic containers, which contain a pourable food product, from a tube 2 of material for packaging formed by folding and sealing tightly longitudinal a strip of heat sealable sheet material, and refilled with the food product upstream of the unit one.

The tube 2 is fed to the unit 1 in a way known along a vertical path defined by an axis TO.

Unit 1 comprises a support structure 3 which defines a pair of symmetrically located vertical guides 4 with respect to the longitudinal vertical mean α plane of the unit through the A axis.

Unit 1 comprises, in a known manner, a pair of sets 5, 5 'vertically movable forming along the respective guides 4, and which interact alternately with tube 2 of packaging material to grip and heat seal the cross sections of the tube.

Since the sets 5, 5 'are known and are symmetrical with respect to the plane α, only one (set 5) is will describe here, and only as for the parts relevant to the present invention, which use the same reference numbers for the corresponding parts of both sets 5, 5 '.

The assembly 5 substantially comprises a slide (6) that moves along the respective guide 4; Y a pair of jaws 7 substantially in the form of plates appropriately ribbed quadrangular, and which are articulated to the slide at the bottom around axes 8a, 8b respective horizontal perpendicular to the plane α, and have the respective control posters 9 protruding from the faces respective opposites.

The jaws 7 are integrally coupled with the respective support arms 10, which are fixed to the upper ends of the respective jaws 7 and protrude towards and beyond the plane α to be positioned in either side of tube 2 (figure 2).

The protruding portions of the arms 10 are couple with the elements (not shown) of hermetic seal in respective bar shape to interact with tube 2. Whose elements can be defined, for example by an inductor to generate current in the aluminum layer of the packaging material and the thermoplastic fusion layer by virtue of the Joule effect; and by a contrast pad that allows grip pressure necessary to be applied to the tube.

The movement of the jaws 7 is controlled by known way for a pair of vertical rods 15, 16.

Rod 15 is rigidly connected to the slide 6 and therefore controls the vertical movement of the set 5; while the rod 16 extends therethrough, without be connected to the slide 6, and is connected to the end 17 lower of the jaws 9 of control of the jaws 7 by means of the respective connecting rods 18, so that the movement down the rod 16 with respect to the rod 15 open the jaw 7 (figure 3).

The jaws 7 are mobile between one position closed (shown in figure 3 in relation to the assembly 5 ') and a fully open position (shown in figure 3 in relation to set 5). According to this movement it overlaps on the alternative vertical movement of the slide 6, the rods 15 move alternately, while rods 16 perform a periodic axial movement defined by a combination of the alternative movement of the rods 15 and a periodic movement additional to open and close the jaws 7. Skirts 19 of known respective training are also articulated to the arms 10.

According to the present invention, the rods 15, 16 of each of the training sets 5, 5 'are controlled independently by respective servomotors 20, 21, 20 ', 21' (figure 4).

The four servomotors 20, 21, 20 ', 21' are they lodge in juxtaposed pairs in the upper part of the structure 3. More specifically, engines 20, 21 of assembly 5 are mounted on one side of structure 3, and have respective drive shafts (not shown) face and coaxial to each other, with the axes respective parallel to the plane α; and the 20 'servomotors. twenty-one' of the set 5 'are mounted in the same way on the other side of structure 3 and symmetrically with servo motors 20, 21 with with respect to the α plane.

Each servomotor 20, 21, 20 ', 21' is conveniently coupled to a support frame 22, which is connected to a respective card 24, protruding laterally to starting from structure 3, by means of a vertical joint 23 respective. This provides smooth access to servomotors 20, 21, 20 ', 21' for maintenance purposes, allowing each one to be substantially "extracted" without be completely disassembled, from structure 3 by turning it towards outside around the respective joint 23.

Each motor pair is provided with a unit 25, 25 'of respective transmission. Since both units are identical and located symmetrically with respect to the plane α, only unit 25, shown in detail in the Figure 5, the same considerations obviously also apply, unchanged, to unit 25 '.

The transmission unit 25 comprises a frame 27 support in turn comprising an annular base flange 28 coupled to support the structure 3 of the unit 1, on the engines 20, 21, and a gantry structure 29 extending towards above from tab 28.

The frame 27 houses and supports two transmissions of tape 33a. 33b interposed respectively between motor 20 and the respective rod 15, and between the motor 21 and the rod 16 respective. Since transmissions 33a, 33b are substantially identical, only transmission 33a will be described, the transmission elements 33b being indicated to use the same reference numbers as for the corresponding elements of transmission 33a.

The transmission 33a comprises a belt 34 toothed, which meshes with a drive pulley 35 coupled to the motor shaft of the motor 20 and with a drive pulley 36 coupled freely to a support fork 37 connected to an element 38 upper transverse of the gantry structure 29 by means of a tensioning device shown in figures 6 and 7 and described in detail below. The shafts of pulleys 35 and 36 they rest in a vertical plane parallel to the plane α, so that the tape 34 comprises a pair of parallel branches vertical

One of said branches of the tape is rigidly engages with a shoe or skate or block 42 of skate defined by a sliding element 43 into the belt and coinciding with the teeth, and by a fastener 44 towards off the tape and rigidly connected to element 43 to insert the tape.

Element 43 collaborates slidingly with a vertical guide section 55 integrally carried by a support frame 56 that is rigidly fixed inside the frame 27.

Element 44 comprises a portion 45 of clamp to which the upper end of the rod is connected fifteen.

With reference to figures 6 and 7, the tensioning device 39 comprises a tubular body 46, which is coupled to the upper transverse element 38 of the structure 29 of frame gantry 27, through an opening 47 in the element transversal (figure 5).

The device 39 also comprises an axis 48 vertically coupled through and sliding axially with respect to the tubular body 46; and a holding portion 49 is formed in the lower end of shaft 48 and rigidly connects to the fork 37.

A coil spring 50, coaxial with axis 48, it is compressed axially between the tubular body 46 and the ring 51 of stop rigidly coupled to and near the upper end of the shaft 48, to push the shaft 48 and therefore the fork 37 elastically upwards.

The device 39 for tensioning also comprises a pair of located cylindrical bushings 52 diametrically opposed to each other with respect to body 46, with their respective axes that extend radially with respect to the body axis 46 and resting along a straight line C common.

The bushings 52 are fixed in a manner rotating to the respective pins (not shown), and house the respective springs (not shown) to produce torque to the bushings in opposite directions (for example in the sense clockwise, with reference to the sleeve 52 shown in Figure 6). Advantageously, the bushings 52 are mounted on non-return needle bearings for rotating movement unidirectional

Each bushing 52 carries an integral cam 54 that extends circumferentially along a fraction of the side surface of bushing 52; and each cam 54 has a profile of elevation that increases in the opposite direction at the time of torsion acting on the bushing.

The stop ring 51 comprises a pair of arms 57 diametrically opposed, protruding each one towards a respective bushing 52; and, at the free end, each arm 57 defines a threaded bushing 58 in which a screw is screwed 59 of regulation or respective adjustment that collaborates at the end with the respective cam 54.

The servomotors 20, 21, 20 ', 21' are connected to a control unit 60, which can be programmed to vary the operation that governs engine parameters, and therefore to vary the operating cycles of unit 1.

Unit 1 works as follows.

The vertical movement of the rods 15, 16 which control sets 5, 5 'of formation are controlled by servomotors 20, 21, 20 ', 21'. The axis 33 motor rotation of each servomotor is transmitted, via drive pulley 35 respectively, to the toothed belt 34, which produces a movement vertical shoe or block 42 of skate and therefore rod 15, 16 respectively.

The servomotors 20, 21, 20 ', 21' are controlled to govern the movement of the rods 15, 16 of the assemblies 5, 5 'training as required to perform the operating cycle of unit 1.

Very briefly, jaws 7 of each set 5, 5 'close during the downward movement of the assembly, to grab tube 2 with a vertical downward component of movement equal to the translation speed of tube 2. The jaws 7 remain closed during movement towards below, and the sealing elements grab the tube with enough pressure to seal it. Near the central position in lower dead center, jaws 7 open to release the tube 2, also open during upward movement, and they reach the fully open position (figure 3) before reaching the central position in top dead center. The jaws then they begin closing, and close completely after reaching the central position in top dead center for the reasons explained above.

The operation of sets 5 and 5 'is obviously displaced in the middle of a cycle: set 5 is move up with jaws 7 open according to the set 5'moves down with the jaws closed, so that the arms of the set 5 'pass between the arms of the set 5 without interfere with them.

The tensioning devices 39 ensure the correct tension defined by spring load 50 -of the tapes 34, even in the case of stretching of the tapes In which case, shaft 48 is pushed up by the spring 50 to form a gap between screws 59 and cams 54; whose clearance, however, is automatically absorbed by the rotating bushings 52 and thus come into contact with a portion of highest elevation of the cams 54 with the screws. The devices 39 therefore allow the upward movement of the respective transmission pulleys 36 to compensate for the stretching of the ribbons 34, although they avoid any movement in the opposite direction.

The control of sets 5, 5 'by servomotors 20, 21, 20 ', 21' allows the cycle parameters operating (displacement, speed) can be adjusted as requires according to the volume and configuration of the containers that will occur, without any mechanical alterations important to the machine. In addition, since the sets 5. 5 'of training are independently controlled, the position of the Packaging designs can be corrected quickly and easily, thereby reducing the number of rejections.

More specifically, in the presence of a signal input indicating a design error position with respect to to the theoretical position, the travel speed of one of the sets 5, 5 'can be varied with respect to each other within a cycle, without any change in the relative starting position and end of cycle And once the required corrections are achieved, the control unit can thus control the speed for restore the relative position of the formation sets 5, 5 ' before the end of the cycle

The additional advantages of unit 1 according to the present invention are higher compactness and lower cost as compare with mechanically controlled cam units conventional.

Clearly, changes can be made to the unit as described and illustrated in this document without, no However, departing from the scope of the claims to be accompany.

Claims (12)

1. A formation and sealing unit (1) for producing aseptic airtight containers, containing a pourable food product, from a tube (2) of packaging material filled with said food product and fed along a path (A) vertical, said unit (1) comprising a fixed structure (3); a pair of forming assemblies (5, 5 ') that interact alternately and cyclically with said tube (2) of packaging material, and in turn comprising respective slides (6) movable vertically and alternately with respect to said fixed structure (3), and respective pairs of jaws (7) having sealing and moving means between an open position and a closed position in which said sealing means collaborates with said tube (2) of packaging material; a first pair of control elements (15) to control the movement of said slides (6); a second pair of control elements (16) for controlling the opening and closing movement of said jaws (7); and activation means for activating said first and second control elements (15, 16); characterized in that said activation means comprise a first servo motor (20) and a second servo motor (20 ') to activate the respective control elements (15) of said first pair of control elements (15), and a third servo motor (21) and a fourth servomotor (21 ') for activating the respective control elements (16) of said second pair of control elements (16), said forming and sealing unit also includes a control unit (60) for independently controlling said first, second, third and fourth servomotors (20, 21, 20 ', 21'). 2. A unit according to claim 1, characterized in that said control unit (60) is programmable to vary the movement of said control elements (15, 16). A unit according to claim 1 or 2, characterized in that said first control elements comprise a pair of first vertical rods (15) connected to said respective slides (6); and said second control elements comprise a pair of second vertical rods (16) connected to said respective pairs of jaws (7); said unit (1) comprising means (33a, 33b) of belt transmission interposed between each servomotor (20, 21, 20 ', 21') and said respective rod (15, 16). A unit according to claim 3, characterized in that said means (33a, 33b) of belt transmission comprise a toothed belt (34) activated by the servo motor (20, 21, 20 ', 21') and having at least one movable portion along a vertical plane; and a shoe (42) rigidly connected to said portion of said tape (34) and having connection means (45) for connecting to said respective rod (15, 16). A unit according to claim 4, characterized in that said transmission means (33a, 33b) comprise means (36, 37, 46, 48, 50, 51) for tensioning each of said tapes (34). A unit according to claim 5, characterized in that said tension means comprise a transmission pulley (36) that collaborates with said belt (34); support means (37, 48, 51) for supporting said transmission pulley (36); fastening means (46) for fastening said support means (37, 48, 51) to said fixed structure (3) of said unit (1); and an elastic means (50) interposed between said means (37, 48, 51) for supporting said transmission pulley (36) and said fastening means (46), to exert on said means (37, 48, 51) of support a force to give tension to said belt (34). A unit according to claim 6, characterized in that said means for tensioning comprise means (54, 59) for retaining a direction interposed between said means (37, 48, 51) for supporting said transmission pulley (36) and said securing means (46), and which allow the movement of said support means (37, 48, 51) for supporting said transmission pulley (36) with respect to said securing means (46) in the determined elongation direction of said tape (34), and prevent relative movement in the opposite direction. A unit according to claim 7, characterized in that said one-way retention means comprise the cam means (54) carried by said holding means (46); and the pressure means (59) carried by said support means (37, 48, 51) for supporting said pulley (36); said cam means (54) having a variable elevation profile, and being elastically pushed to recover any clearance formed between said cam means (54) and said pressure means (59). A unit according to claim 8, characterized in that said support means of said pulley (36) comprise a support fork (37); a shaft (48) rigidly connected to said fork (37); and a stop member (51) rigidly coupled to said shaft (48); said fastening means comprising a tubular body (46) coupled to said fixed structure (3) and housing said shaft (48) in a sliding manner; and said elastic means comprising a spring (50) compressed between said tubular body (46) and said stop element (51). A unit according to claim 9, characterized in that said cam means comprise at least one cam (54) that rotates around an axis (C) that extends radially with respect to said tubular body (46); and because said pressure means comprise a pressure screw (59) that collaborates with said cam (54) and carried by an arm (57) that forms part of said stop element (51); said cam (54) being loaded by said elastic means (50) for contacting the increasing elevation portions of said profile with said screw (59) in the case of a gap formed between said cam (54) and said screw (59). A unit according to one of the preceding claims, characterized in that said servomotors (20, 21, 20 ', 21') are coupled to the respective support elements (22) to be at least partially removable from said structure (3) of said unit (1). A unit according to claim 11, characterized in that said support elements (22) are articulated to said structure (3) of said unit (1).