ES2198269T3 - MACHINE FOR PACKAGING VERTIBLE FOOD PRODUCTS. - Google Patents

Abstract

A machine (1) for packaging pourable food products in packages formed from a continuous tube (2) of packaging material (4) having crease lines (13) for assisting folding of the packaging material, and wherein a control device (60) for controlling feed of the tube (2) has an optical sensor (62) for detecting the position of prelaminated holes (5) formed on the material (4) and in register with the crease lines (13), and a control unit (63) for controlling actuators (7, 56, 25) for correcting the longitudinal and angular position of the tube (2) in response to respective longitudinal and transverse position errors (E1, E2) of the holes (5) detected by the optical sensor (62). <IMAGE>

Description

Machine for packaging food products poubles

The present invention relates to a machine to pack pourable food products.

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

The packaging material has a structure of multiple layers comprising a layer of paper material coated on both sides with layers of plastic material heat-welded, for example, polyethylene, and, in the case of packaging aseptic for long-term storage products, such as UHT milk, also comprise a layer of protective material defined, for example, by an aluminum foil, which overlaps on a layer of heat-welded plastic material and which in turn cover with another layer of heat-welded plastic material that eventually define the inner face of the container that is in contact with the food product.

To produce aseptic containers, the band of packaging material is unwound from a reel and introduced to through an aseptic chamber in which it is sterilized, for example, applying a sterilizing agent such as hydrogen peroxide, which subsequently evaporates by heat and / or subjecting packaging material at a wavelength and intensity radiation adequate. The sterilized band is then folded into a cylinder and is welded longitudinally to form, in a known manner, a continuous, vertical and longitudinally welded tube. In others words, the tube of packaging material forms an extension of the aseptic chamber, continuously filled with the product pourable food and then introduced into a unit of formation and welding (transverse) to form the containers individual and in which a pair of jaws grab and weld the tube transversely in pillow-shaped containers.

Pillow-shaped containers are separated then cutting the welding part between the containers, and then they enter a final folding station where they are folded mechanically to give them the shape of the finished containers.

The training procedure involves folding of the packaging material along fold lines formed with in advance as part of the manufacturing process of the material.

The material manufacturing procedure typically comprises lamination steps to produce the various layers from which the material will be formed; a number of print stages to print graphics or drawings that reproduce periodically throughout the material with a step equal to the length of the material used to produce each container; and the folding stage mentioned above, which carried out on the finished material or only on a subset of layers of material comprising at least the layer of paper. Holes are also known that are practiced in the layer of paper before coating it with a continuous layer of material of protection to form the so-called holes `` prelaminates '' closed by the protective material, which ensures a tight and aseptic welding while at the same Time can be drilled easily. The holes in the layer of paper can be conveniently formed using the same tool than for the fold lines, in which case, the material of protection is laminated later.

Packaging materials with holes prelaminates are used for aseptic materials with straws or opening devices, for example, of the type comprising a articulated cap or screw cap.

The various operations of the procedure of Packaging material manufacturing is carried out using, as a match mark, an optical match code printed on the material during the first stage of Print.

The same code is normally used on the machine trainer to control the feeding of the material through The various work stations. More specifically, as is known, a device called `` drawing correction '' acts on the containers that are being formed to `` throw away '' with a tensile force of varying intensity of the material in the feed direction and ensure that mechanical operations  training are done in coincidence with the drawing in the containers (see, for example, EP 25235).

However, manufacturing tolerances of material may lead to code position errors optical match with respect to the fold lines, so that a frequent manual adjustment of the device is required drawing correction (based on optical match code) to prevent members that form from interacting incorrectly with the material with respect to the lines of fold.

In known packaging machines, the position Angular packing tube may vary, in use, with with respect to the desired angular position, due to the fact that side edges of the band are not perfectly straight, and of the effect produced by the pairs of jaws colliding successively with the tube

How this can have negative effects on the quality of longitudinal and transverse welds, and on the precision with which the containers are formed, machines are provided known with devices to manually adjust the position angle of the tube (see for example EP 903902). Without However, these devices require relatively much time, and they can imply stopping the machine with the consequent loss in manufacturing. Systems have also been proposed to adjust automatically the angular position of the material tube of package, but require the use of an exclusive sensor to determine the position of the longitudinal weld.

An object of the present invention is to provide a machine for packaging pourable food products, designed in order to solve the aforementioned problems which are typically related to known machines.

In accordance with the present invention, provides a machine for packaging food products poubles in containers formed from a continuous band of packaging material, whose machine comprises a folding unit longitudinal to fold longitudinally to said band in order of forming a continuous tube; a forming unit that has at least two pairs of jaws that interact cyclically with said tube to weld the tube along transverse bands equidistant; and a control device to control the feeding of said tube, and which in turn comprises means for correct the longitudinal position of said tube, and means for correct the angular position of said tube; whose material of packaging comprises a drawing, and a series of fold lines for help to fold the packaging material in said unit of training; characterized in that said control device intended to control the feeding of said tube comprises detection means to detect the position of elements optically detectable formed in said material and in coincidence with said fold lines; and means to control to said means intended to correct the longitudinal position of said tube and said means intended to control the position angle of said tube, in response to respective errors of longitudinal and transverse position of said detectable elements optically that they are detected by said means of detection.

The control of the position of the material tube package based on a position reference matching the fold lines prevents any tolerances of manufacturing, which may result in the fold lines not perfectly match the drawing, disturb the quality of the Welding and training procedure.

Successive operations on the packaging that use the edges of the container as a reference, such as when apply opening devices on the holes, they are carried to also perform correctly, by controlling the training of the package based on a matching position reference With the fold lines.

Therefore, the present invention provides the improvement of the quality of the finished product and the reduction of manual adjustment of the machine.

In a preferred embodiment of the present invention, the position of the prelaminated holes is used practiced in the material as an element to detect the tube position of packaging material; the position of the holes with a horizontal reference position; and they are used any longitudinal and transversal errors to correct the feeding of the material and the angular position of the tube, respectively.

The use of pre-laminated holes as position detecting elements allows both the longitudinal position as the angular position using a single sensor

An embodiment is described below. Preferred of the present invention, without limitation and title example with reference to the attached drawings, in which:

Figure 1 shows a front view of a packaging machine that has an adjustment device packaging material according to the present invention.

Figure 2 shows a perspective view of a station for supplying and folding the packaging material;

Figure 3 shows a schematic side view of a machine forming station of Figure 1;

Figure 4 shows a diagram of the device of feeding adjustment of the packaging material according to the invention; Y

Figure 5 shows a part of the material of package.

With reference to Figures 1 to 3, the number 1 indicates in its entirety a machine to produce containers of a pourable food product, such as pasteurized milk or milk UHT, fruit juice, wine, etc.

In particular, machine 1 serves to produce aseptic sealed containers of a pourable food product a from a tube 2 of heat-welded material 4 to be packaged, which to in turn it is formed by folding and longitudinally welding a band 3 of packaging material.

Material 4 (Figure 5) comprises conveniently a layer 4a of paper material, and a layer 4b of protective material defined, for example, by a sheet of aluminum. Layers 4a and 4b are fixed together by a layer intermediate of thermoplastic material (not shown), for example, polyethylene, and are coated on opposite sides with layers Additional polypropylene (not shown). The 4th layer of material of paper comprises a succession of holes 5 made before form the lamination layer 4b; and a series of fold lines 13 (Figure 4) to help fold the material when the containers, and that reproduce periodically with a P step equal to the distance between the holes and the length of the band part 3 required to produce each container. Holes 5 and lines 13 are conveniently formed in the same apparatus, thereby They perfectly match each other.

In all of layer 4b they have been practiced holes 5 to ensure a tight and aseptic welding of the container until it opens; and subsequently installed on the holes 5 types of extraction devices or other types of opening devices (not shown).

Material 4 also comprises a drawing 14 defined by a succession of graphics that are reproduced periodically with a step P and each of which comprises a code 15 optical match. Drawing 14 also includes conveniently a white area 15a that surrounds each hole 5 (Figure 5).

Band 3 of packaging material 4 is unwind a reel (not shown) and enter, by known guiding roller devices (not shown), to through a sterilization unit (not shown) to a chamber upper aseptic 6 of machine 1, which communicates with the unit of  sterilization and through which band 3 is introduced at along a longitudinal path P1. Band 3 deviates then down using a roller 7 - which is part of a roller system, one of which is propelled - and it feeds down along a vertical path P2 that is extends inside a vertical chamber or tower 8.

Inside tower 8, band 3 folds longitudinally in a cylinder to form tube 2, which has a longitudinal axis A parallel to the path P2 and is welded longitudinally by a welding device 10 and by means of a known heat welding strip that is not described in detail. Tube 2 is continuously filled with the food product by means of a known filling device 11 (not described with detail) and is introduced to a known training unit 12 described below only as to the relevant parts to the present invention.

More specifically, machine 1 comprises a folding unit 9 for longitudinally folding the band 3 with the in order to form tube 2, and that is defined by a number of known sets 16, 17 and 18 of folding located along the P2 path inside tower 8, which interact with the band 3 to gradually fold it into a cylinder and overlap with the opposite side parts of the band 3 (Figures 1 and 2) to form the tube of packaging material.

Sets 16, 17 and 18 comprise numbers respective rollers 21, 22 and 23 of substantially folding cylindrical having respective axes perpendicular to the A axis, and that define polygons surrounding the A axis such that the respective lateral surfaces define successive ducts bound for band 3 of packaging material being folding. As it is introduced through the ducts, the band goes from having an open C shape defined by the folding rollers 21 of the folding assembly 16, to have a substantially circular shape defined by rollers 23 of folding of the folding assembly 18.

The axes of the rollers 21 and 23 of the assemblies 16 and 18 folding are fixed, while the rollers 22 of folded assembly 17 are attached to a support plate 24 in C shape connected to the structure of machine 1 in order to be adjustable angularly around the A axis to adjust the angular position of the tube 2 that is being formed with respect to the axis TO.

The rotation of the plate 24 is controlled by a drive mechanism 25 through a mechanism 26 of transmission, for example screw screw nut.

The speed at which band 3 is introduced through the folding sets 16, 17 and 18 is determined by the movement of the sets 35 and 35 ', and is produced by a electric motor that drives the folding roller 7.

Once welded longitudinally, tube 2 is enter the forming unit 12.

Unit 12 comprises a structure 33 of support defining two vertical guides 44 arranged symmetrically with respect to a longitudinal vertical median plane á of the unit a through the A axis, and whose respective axes are located in a vertical transversal midplane ta of unit 12. By therefore, axis A defines the intersection of the planes α and \ tau.

Unit 12 comprises, in a known manner, two forming sets 35 and 35 'vertically movable length of respective guides 44 and interacting alternately with the tube 2 of packaging material to grip and heat the tube cross sections.

Since sets 35 and 35 'are symmetrical with with respect to the plane á, only one (set 35) has been shown with detail in Figure 3, and described later. In the drawings Attached, the corresponding parts of sets 35 and 35 'are have indicated using the same reference numbers.

With reference to figures 1 and 3, the set 35 substantially comprises a slide 36 movable to along a respective guide 44; and two jaws 37 articulated in the lower part of the slide 36, around horizontal axes respective 38 parallel to the plane \ tau and symmetric with respect to said plane \ tau, so that they open and close substantially `` like a book. ''

More specifically, each jaw 37 comprises a main control body 39, which has substantially the shape of a properly ribbed quadrangular plate (Figures 1 and 3), extends along a working plane? of the jaw 37 which contains the respective axis 38, is articulated very close to its lower side to the slide 36, and comprises a respective arm 40 control protruding from one face of the body 39 facing each other out of the plane?

The jaws 37 also comprise respective support arms 41, which are attached to the upper ends of the respective bodies 39 of the respective jaws 37, and protrude to and beyond the plane á, in a parallel direction to the respective axes 38 and substantially along the respective work plans [beta], so that they remain located on opposite sides of tube 2.

The protruding parts of the arms 41 have 42 and 43 rod-shaped welding elements (Figure 3) that interact with tube 2, and that can be defined, for example, by an inductance coil to generate current in the layer of Aluminum packaging material and melt the thermoplastic layer as a consequence of the Joule effect, and for a support of coupling against the one that grabs tube 2 under pressure required

The alternative movement of slides 36 and the opening / closing movement of the jaws 37 are controlled by in a known way (not described) by pairs of stems vertical (not shown) which in turn are controlled by rotating cams or servomotors.

The jaws 37 are movable between a closed position in which the respective elements 42 and 43 of Weld grab tube 2, and a fully open position.

In the transverse welding stage, tube 2 it is welded along equidistant cross bands 45 (Figure 4).

On the respective elements 42 and 43 of welding, the arms 41 of the jaws 37 support tabs respective 46 of container volume control having a C-shaped cross section open at the front, and that cooperate with each other, after the transverse welding operation made by elements 42 and 43, to define a cavity of default shape and volume that encloses and forms tube 2 in a rectangular section shape.

The training stage mentioned above (Figure 4) produces 47 `` pillow-shaped '' containers each of which comprises a main part 48 in the same way and volume than the finished container; and transitional parts 49 that connect the main part 48 to respective adjacent bands 45 welding, and laterally defined by faces 50 substantially triangular

One of the jaws 37 comprises, in a manner known, two folding tabs 54 to control, together with the folding roller 7, the longitudinal feeding of the tube 2 a through the forming unit 12.

The folding tabs 54 (Figures 3 and 4) are located on both sides of tube 2, they are symmetrical with respect to the A axis and adjacent to tube 2, revolve around respective axes perpendicular to the β plane, and are rotated in directions contrary by a known device 51 for correcting drawing - active in the training stage - to thereby act on the lateral faces 50 of the transition parts 49 of the pillow-shaped packaging and exert a variable effort of traction on the tube 2.

The device 51 comprises, for example, a cam 52 of variable geometry or variable position, shown from a simply schematic mode in Figure 4, which interacts with a cam follower 53 arranged in the jaw 37 and connected to the tabs 54 by a transmission mechanism 55 also shown of Simply schematic form. Examples of said device control are illustrated in Italian patent application no. MI97A-002473 and in the European patent application No. 99830715.1 presented by the present applicant.

The path of the tabs 54, and therefore the tensile stress exerted on tube 2, is adjustable, and described in detail below, by means of a drive mechanism 56 acting, for example, on the cam position 52.

The drive mechanism 25 that controls the pipe bending assembly 17, the electric motor 27 that drives the folding roller 7, and the driving mechanisms 56 of the drawing correction devices 51 of the respective sets 35 and 35 'are part of a device 60 intended for Check the feeding of tube 2 of packaging material. In addition, the device 60 also comprises a first optical sensor conventional 61 to read optical match code 15 printed on material 4; a second optical sensor 62 to detect the position of the holes 5; and a control unit 63 connected at the input to sensors 61 and 62, and at the output to the drive mechanisms 25 and 56 and motor 27.

The second optical sensor 62 is defined conveniently by a camcorder, for example a CCD type, that `` reads '' a part of material 4 in holes 5. To avoid the acquisition and treatment of an excessive amount of data, the first sensor 51 is used to generate a signal I_ {1} of enablement, which changes state in response to the detection of a code 15 and supplied to control unit 63 to enable Reading to the second optical sensor. Thus, to sensor 62 it is only enabled to read in each hole 5 or in one of each number N of holes 5, indicating the position of holes 5 and with respect, for example, to an array of pixels conveniently coded

The control unit 63 compares the position of the detected hole 5 with a memorized reference position (Figure 5) and calculate an error E1 of longitudinal position of the tube 2, and an error E2 of transverse position of hole 5, obviously correlated with the torsion angle of tube 2.

The control unit 63 generates a signal O_ {1} to control the electric motor 27; O2 signals (identical) to control the drive mechanisms 56; and a signal O 3 to control the drive mechanism 25. The signals O_ {1} and O_ {2} are correlated in a way conventional with the value E1, and the signal O3 with the value E_ {2}.

In actual operation, the speed at which supplies material 4 to folding assemblies 16, 17 and 18 and to the training unit 12 is determined by the motor 27 controlled by control unit 63. Since it is known and it may deduct in part from the above description, it is not described in detail the operation of sets 16, 17 and 18 and of the training unit 12.

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no basándose en que el código óptico 15 esté en coincidencia con el dibujo 15 y que forma parte del mismo.If the longitudinal position of the tube 2 is correct, that is, if the absolute value of E_ {1} is less than a predetermined threshold value, the control unit maintains a constant speed of the motor 27. On the contrary, in the presence of a error E_ {1}, the material feed rate 4 is corrected by the control unit 63 by properly modulating the signal O_ {1}. If the resulting correction is not sufficient, in addition to the motor 27, the control unit 63 also acts on the drawing correction device 51 by properly adjusting, by means of the signal O 2, the intensity of the tensile stress exerted by the folding tabs 54. In accordance with the present invention, the controls described above, known per se, are carried out based on errors in the position of the holes 5 - which, as indicated, coincide with lines 13 of

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not based on the fact that the optical code 15 coincides with drawing 15 and is part of it.

In a preferred embodiment of the present invention, the signal I1 of the first sensor 61 is used only to generate a `` reading window '' in which the second sensor 62 actually reads the position of material 4 based on the position of a hole 5 at a given time, and supplies the control unit 63 a signal I_ {1} indicating the matrix of detailed pixels. The white area 15a that surrounds each hole 5 Simplify reading.

Another important feature of the present invention is that the signal I1 is also used to calculate the hole transverse position error, and thereby correct the twisting of the tube 2 by means of the folding assembly 17. Plus specifically, in response to a position error E_ {2} transverse, control unit 63 sends mechanism 25 of actuation, by means of signal O2, which rotates the set 17 folding in one direction or another depending on the sign of the error This control is also performed based on the position of holes 5 and not in optical code 15.

Obviously, changes can be made to the machine 1 described herein without departing, no However, the scope of the invention. In particular, the second sensor 62 can be replaced by any type of sensor, for example defined by a linear succession of photosensitive elements that are extend transversely to the tube feed direction 2, to reconstruct the position of the holes 5 by means of the exploration of the hole area as the material gets is feeding forward, facing the solution of picking up a instant image Moreover, different references can be used position, as long as they coincide with lines 13 of creased.

Claims (7)

1. A machine (1) for packaging pourable food products in containers formed from a continuous band (3) of packaging material (4), whose machine (1) comprises a longitudinal folding unit (9) for longitudinally folding said band (3) in order to form a continuous tube (2); a forming unit (12) having at least two pairs of jaws (37) that interact cyclically with said tube (2) to weld the tube along equidistant transverse bands (45); and a control device (60) for controlling the feeding of said tube (2), and which in turn comprises means (7.27; 51) for correcting the longitudinal position of said tube (2), and means (17, 25) to correct the angular position of said tube (2); whose packaging material (4) comprises a drawing (14), and a series of fold lines (13) to help fold the packaging material into said forming unit (12); characterized in that said control device (60) intended to control the feeding of said tube comprises detection means (62) for detecting the position of optically detectable elements (5) formed in said material (4) and in coincidence with said lines (13 ) fold; and means (63) for controlling said means (7.27; 51) intended to correct the longitudinal position of said tube and said means (17.25) intended to correct the angular position of said tube (2) in response to respective errors (E1, E2) of longitudinal and transverse position of said optically detectable elements (5) that are detected by said detection means (62). 2. A machine as claimed in claim 1, characterized in that said optically detectable elements are pre-laminated holes (5) made in said material (4). 3. A machine as claimed in claims 1 or 2, characterized in that said means intended to correct the longitudinal position of said tube comprise a propelled roller (7) located upstream of said longitudinal folding unit (9). 4. A machine as claimed in one of the preceding claims, characterized in that said means (51) intended to correct the longitudinal position of said tube comprise two folding tabs (54) arranged in a jaw (37) of each pair of jaws (37) and that interact with said material (4) and subject said material (4) to a tensile force of varying intensity. A machine as claimed in any one of the preceding claims, characterized in that said means intended to correct the angular position of said tube (2) comprise at least one folding assembly (17) that is part of said unit (9) of longitudinal folding and which rotates around an axis (A) of longitudinal feeding of said tube (2); and a drive mechanism (25) controlled by said control device (60) for adjusting the position of said folding assembly (17) around said axis (A). A machine as claimed in any one of the preceding claims, characterized in that it comprises a sensor (61) for detecting an optical matching code (15) formed in said material (4) and coinciding with said drawing (14); whose sensor (61) is connected to said control device (60) and generates a signal (I_ {1}) to enable reading to said detecting means (62). 7. A machine as claimed in any one of the preceding claims, characterized in that said detecting means comprise a video camera (62).