JP2004502607A - Machines for packing liquid foods - Google Patents

Abstract

A machine (1) for packaging a flowable food product in a package formed from a continuous tube (2) of packaging material (4) comprising a fold line (13) to assist in folding the packaging material. ) Wherein a control device (60) for controlling the supply of the tube (2) detects the position of the pre-laminated hole (5) and optically aligns it with the fold line (13). The longitudinal direction and the angle of the tube (2) according to the sensor (62) and the respective longitudinal and lateral position errors (E ₁ , E ₂ ) of the hole (5) detected by the optical sensor (62). A machine having a control unit (63) for controlling an actuator (7, 56, 25) for correcting the position.

Description

[0001]
(Technical field)
The present invention relates to a machine for packaging flowable foods.
[0002]
(Background technology)
Machines for packaging flowable foods such as fruit juices, wines, tomato sauces, pasteurized milk or long-term (UHT) milk consist of a series of packaging materials defined by longitudinally sealed webs. It is known that a package is formed from a tube that has been removed.
[0003]
The packaging material has a multilayer structure with layers of paper material covered on both sides with a layer of heat-sealed plastic material, for example polyethylene, and in the case of a sterile package for long-term storage products such as UHT milk, For example, it also comprises a layer of barrier material defined by an aluminum film. This layer is overlaid with a layer of heat seal plastic material and covered with another layer of heat seal plastic material that ultimately defines the interior surface of the package in contact with the food.
[0004]
To create a sterile package, a web of packaging material is fed from a reel and fed through a sterile chamber that is sterilized by, for example, adding a sterilant, such as hydrogen peroxide. The disinfectant is then evaporated by heating and / or by exposing the packaging material to radiation of the appropriate wavelength and intensity. The sterilized web is then folded into a cylinder and longitudinally sealed in a known manner to form a continuous vertical longitudinally sealed tube. The tube of packaging material, in other words, forms an extension of the sterile chamber, is continuously filled with the flowable food, and then fed to a forming and (laterally) sealing unit to separate the individual packages. Once formed, several pairs of jaws laterally grip and seal the tube into a pillow pack.
[0005]
The pillow packs are then separated by cutting the seal between the packs and fed to a final fold position where they are mechanically folded into the shape of the finished package.
[0006]
The forming process includes folding the package material along preformed fold lines as part of the material manufacturing process.
[0007]
The material manufacturing process typically involves a laminating step to create the various layers in which the material is formed, and periodic along the material at a pitch equal to the length of the material used to create each package. Includes a number of printing steps to print the repetitive graphic or design, and the above-described creasing steps performed on the finished material, or at least only on a subset of the material layer comprising a layer of paper. The holes are also covered with a continuous layer of barrier material to form a so-called "pre-laminated" hole, closed by an easily perforable barrier material, while at the same time ensuring a hermetic and sterile seal. Before it is formed in a layer of paper. The holes in the layer of paper are conveniently formed using the same tools as for the fold line, in which case the barrier material is later laminated.
[0008]
Package materials with pre-laminated holes are used for sterile packages with straws or opening devices of the type with, for example, hinged lids or screw caps.
[0009]
Various operations in the packaging material manufacturing process are performed using the optical alignment code printed on the material during the first printing step as an alignment mark.
[0010]
The same cord is typically used on a forming machine to control the supply of material through various work stations. More specifically, as is known, a so-called "design modification" device works on a forming package to variably "pull" material in the feed direction and align the design on the package. Ensure that the mechanical forming operation is performed.
[0011]
However, material manufacturing tolerances result in positional errors of the optical alignment code with respect to the fold line, so that frequent manual adjustments of the design modification device (based on the optical alignment code) require forming members. Is required to prevent incorrectly affecting the material with respect to the fold line.
[0012]
In known packaging machines, due to the fact that the lateral edges of the web are not perfectly straight and the action created by several pairs of jaws that in turn bite the tube, the angular position of the tube of packaging material is in use. It may vary for the desired angular position.
[0013]
This has a negative effect on the quality of the longitudinal and lateral sealing, and on the accuracy with which the package is formed, so known machines use devices for manually adjusting the angular position of the tube. Prepare. However, such devices are time consuming and can include machine downtime with consequent loss of production. Systems for automatically adjusting the angular position of the tube of packaging material have also been proposed, but require the use of dedicated sensors to determine the position of the longitudinal seal.
[0014]
(Disclosure of the Invention)
It is an object of the present invention to provide a machine for packaging pourable food products, designed to solve the above-mentioned problems usually associated with known machines.
[0015]
According to the present invention, a longitudinal folding unit for folding a web longitudinally to form a continuous tube, and periodically interacting with said tube to seal the tube along equally spaced transverse bands A forming unit having at least two pairs of jaws, means for controlling the supply of the tube and for correcting the longitudinal position of the tube, and means for correcting the angular position of the tube. A control device, wherein the packaging material flows into a package formed from a continuous web of packaging material comprising a design and a series of fold lines to assist in folding the packaging material on the forming unit. A machine for packaging foods of any nature, wherein the control device for controlling the supply of the tube comprises: Formed in, and aligned with the fold line, detecting means for detecting the position of the optically detectable element, and detected by the detecting means, the longitudinal direction of the optically detectable element and And means for controlling the means for correcting the longitudinal position of the tube and the means for correcting the angular position of the tube in response to an error in each of the lateral positions. Is provided.
[0016]
Controlling the position of the tube of packaging material based on the alignment criteria that aligns with the fold line can result in the fold line not being fully aligned with the design due to incomplete sealing quality and the forming process. Some prevent any manufacturing tolerances.
[0017]
Consecutive movements on the package, using the package edge as a reference, also control the formation of the package based on a positional reference that aligns with the fold line, such as when attaching an opening device that covers a hole Is done exactly by doing
[0018]
Thus, the present invention provides for improving the quality of the finished package and reducing manual adjustment of the machine.
[0019]
In a preferred embodiment of the present invention, the location of the pre-laminated holes in the material is used as an element for sensing the location of the tube of packaging material. The position of the hole is compared to a stored reference position and any longitudinal and lateral errors are used to correct the material feed and tube position, respectively.
[0020]
The use of pre-laminated holes as position sensing elements allows both longitudinal and lateral position of the tube to be controlled with a single sensor.
[0021]
Preferred and non-limiting embodiments of the present invention will now be described by way of example with reference to the accompanying drawings.
[0022]
(Best mode for carrying out the invention)
With reference to FIGS. 1 to 3, numeral 1 generally indicates a packaging machine for making packages of pasteurized or flowable food products such as UHT milk, fruit juice, wine, and the like.
[0023]
In particular, the machine 1 can produce a sterile hermetically sealed package of flowable food products formed by longitudinally folding and sealing a web of packaging material 3 from a tube 2 of heat sealing packaging material 4. it can.
[0024]
Material 4 (FIG. 5) advantageously comprises a layer 4a of paper material and a layer 4b of barrier material defined, for example, by a sheet of aluminum. Layers 4a and 4b are secured to one another by an intermediate layer (not shown) of a thermoplastic material, for example polyethylene, and the opposite side is also covered by another layer of polyethylene (not shown). Layer 4a of paper material comprises a series of holes 5 formed before laminating layer 4b and a series of fold lines 13 (FIG. 4) to assist in folding the material when forming the package. . The fold lines are periodically repeated at a pitch P equal to the distance between the hole and the length of the portion of the web 3 required to make each package. The holes 5 and the lines 13 are advantageously formed on the same fixed part so that they are perfectly aligned with one another.
[0025]
The layer 4b is generally at the hole 5 to ensure an airtight and sterile seal of the package until the package is opened. A pull-off or other type of opening device (not shown) is later fitted over the hole 5.
[0026]
The material 4 also comprises a design 14 defined by a series of graphics that repeat periodically at the pitch P, each with an optical alignment code 15. The design 14 also advantageously comprises a white area 15a surrounding each hole 5 (FIG. 5).
[0027]
A web 3 of packaging material 4 is unwound from a reel (not shown) and is passed by a known guide roller device through a known sterilization unit (not shown) to the top sterile chamber of the machine 1. 6. The sterile chamber 6 is in communication with a sterilization unit, through which the web 3 is fed along a horizontal path P1. Thereafter, the web 3 is turned downward by rollers 7, one of which forms part of the powered roller group system, and is fed downward along a vertical path P2 extending inside the vertical chamber or tower. Is done.
[0028]
Inside the tower 8, the web 3 is folded longitudinally into a cylindrical shape to form the tube 2. The tube 2 has a longitudinal axis A parallel to the path P2 and is longitudinally sealed by a sealing device 10 and using a known heat sealing strip, not described in detail here. The tube 2 is continuously filled with foodstuffs using a known filling device 11 (not described in detail here) and supplied to a known forming unit 12 described below only for parts relevant to the invention. .
[0029]
More specifically, the machine 1 comprises a folding unit 9 for longitudinally folding the web 3 to form the tube 2, the folding unit 9 being arranged along a path P 2 inside the tower 8. Defined by several known folding assemblies 16, 17, 18, interacting with the web 3, gradually folding the web 3 into a cylinder and overlapping opposing transverse portions of the web 3 (FIGS. 1 and 2) Form a tube of packaging material.
[0030]
Each of the assemblies 16, 17, 18 has a respective axis perpendicular to the axis A and defines a polygon surrounding the axis A, so that each lateral surface is a continuous web of web 3 of package material to be folded. It comprises a number of substantially cylindrical folding rollers 21, 22, 23 defining a forced path. As the web is fed through the passageway, from the open C-shape defined by folding rollers 21 of folding assembly 16 to the substantially circular shape defined by folding rollers 23 of folding assembly 18. pass.
[0031]
The axes of the rollers 21, 23 of the folding assemblies 16, 18 are fixed, while the folding rollers 22 of the assembly 17 are fitted on a C-shaped support plate 24 connected to the structure of the machine 1, Thereby, an angular adjustment around the axis A can be made to adjust the angular position of the tube 2 being formed with respect to the axis A.
[0032]
The rotation of the plate 24 is controlled by an actuator 25 via a transmission mechanism 26 such as a screw / nut screw.
[0033]
The speed at which the web 3 is fed through the folding assemblies 16, 17, 18 is determined by the movement of the assemblies 35, 35 'and is affected by the electric motor 27 driving the folding rollers 7.
[0034]
Once sealed longitudinally, the tube 2 is fed to the forming unit 12.
[0035]
The unit 12 comprises a support structure 33 defining two vertical guides 44 symmetrically arranged with respect to the unit's longitudinal mid-plane α passing through the axis A, the respective axis of which is transverse to the unit 12. In the vertical intermediate plane τ. Thus, axis A defines the intersection of planes α and τ.
[0036]
The unit 12 is vertically movable along respective guides 44 in a known manner and interacts alternately with the tube 2 of package material to grip and heat seal the tube cross section. One forming assembly 35, 35 '.
[0037]
Since the assemblies 35, 35 'are symmetric with respect to the plane α, only one (assembly 35) is shown in detail in FIG. 3 and will be described below. In the accompanying drawings, corresponding parts of the assemblies 35, 35 'are indicated using the same reference numerals.
[0038]
Referring to FIGS. 1 and 3, the assembly 35 includes a slide 36 movable along a respective guide 44 and a respective slide 36 that is parallel to plane τ and symmetric about plane τ so that it can be opened and closed substantially in a “book” fashion. It comprises essentially two jaws 37 hinged at the bottom to the slide 36 about a horizontal axis 38.
[0039]
More specifically, each jaw 37 is substantially in the form of a suitably ribbed quadrilateral (FIGS. 1 and 3) and extends along the work plane β of the jaw 37 including the respective axis 38; It comprises a main control body 39 hinged to the slide 36 near its bottom and comprising individual controls 40 protruding from the face of the opposing body 39 remote from the plane β.
[0040]
The jaws 37 are also fitted to the uppermost end of the respective body 39 of the respective jaws 37 and towards and beyond the plane α so that they can be arranged on the opposite side of the tube 2. It has individual support arms 41 projecting in a direction parallel to the axis 38 and substantially along the respective work plane β.
[0041]
The protruding part of the arm 41 interacts with the tube 2, for example by generating an electric current in the aluminum layer of the package material, by an inductor which melts the thermoplastic layer as a result of the Joule effect, and at the required pressure by the tube. 2 are fitted in respective bar-shaped sealing elements 42, 43 (FIG. 3) defined by mating pads for gripping.
[0042]
The reversing movement of the slide 36 and the opening / closing movement of the jaws 37 are controlled in a known manner (not described) by several pairs of vertical rods (not shown) controlled by a rotary cam or a servomotor. ing.
[0043]
The jaws 37 can move between a closed position in which the respective sealing elements 42, 43 grip the tube 2 and a fully open position.
[0044]
In the lateral sealing step, tube 2 is heat sealed along equally spaced lateral bands 45 (FIG. 4).
[0045]
On each sealing element 42, 43, the arm 41 of the jaw 37 supports a respective package volume control tab 46 having a C-shaped cross section with an open front, the tab being moved by the element 42, 43. After the transverse sealing operation is performed, the tubes 2 are closed and formed into a rectangular cross-sectional shape, cooperating with each other to define a cavity of a predetermined shape and volume.
[0046]
The above forming steps (FIG. 4) each connect a main portion 48 of the same shape and volume as the finished package and connect the main portion 48 to each adjacent sealing band 45 and traverse by a substantially triangular surface 50. A "pillow" pack 47 comprising a transition portion 49 determined in the direction is created.
[0047]
One of the jaws 37 comprises, in a known manner, together with the folding roller 7, two folding tabs 54 for controlling the longitudinal feeding of the tube 2 through the forming unit 12.
[0048]
The folding tabs 54 (FIGS. 3 and 4) are arranged on both sides of the tube 2 and are symmetrical with respect to the axis A and adjacent to the tube 2 and rotate about their respective axes perpendicular to the plane β, forming steps. Are rotated in the opposite direction by a known design modification device 51, acting on the lateral surface 50 of the transition section 49 of the pillow pack so as to exert a variable tension on the tube 2.
[0049]
The device 51 comprises, for example, a cam 52 of variable geometry or position, shown only schematically in FIG. The cam 52 is carried by a jaw 37 and interacts with a cam follower 53 connected to a tab 54 by a transmission mechanism 55 shown only schematically. Examples of such control devices are given in Italian patent application No. MI97A-002473 and European patent application No. 9983075.1, filed by the applicant.
[0050]
The travel of the tab 54, and thus the amount of tension exerted on the tube 2, can be adjusted, for example, using an actuator 56 acting on the position of the cam 52, as will be described in more detail below.
[0051]
An actuator 25 for controlling the tube folding assembly 17, an electric motor 27 for driving the folding rollers 7, and an actuator 56 for the design modification device 51 of the assemblies 35, 35 ', respectively, for controlling the supply of the tube 2 of packaging material. Of the device 60 of FIG. The device 60 also includes a conventional first optical sensor 61 for reading the optical alignment code 15 printed on the material 4 and a second optical sensor 62 for detecting the position of the hole 5. And a control unit 63 connected to inputs to sensors 61 and 62 and outputs to actuators 25 and 56 and to motor 27.
[0052]
The second optical sensor 62 is advantageously defined by a "camera" for reading a part of the material 4 at the hole 5, for example a CCD type video camera. To avoid requiring and processing an excessive amount of data, the first sensor 61 is used to change state in response to the detection of the code 15 and to make the second optical sensor readable. the enable signal I ₁ to be supplied to the control unit 63 generates such. That is, the sensor 62 is readable only at each hole 5 or only at every N holes 5, and the control unit 63 indicates the position of the holes 5 and, for example, a signal I relating to a conventional coded pixel matrix. Supply ₂ .
[0053]
The control unit 63 compares the detected position of the hole 5 with the stored reference position (FIG. 5), and corrects the longitudinal position error E of the tube 2 apparently corrected for the torsion angle of the tube 2. _1, and calculates the position error E ₂ lateral holes 5.
[0054]
The control unit 63 generates a signal O ₁ for controlling the electric motor 27, a signal 02 (identical) for the actuator 56, and a signal O ₃ for the actuator 25. Signals O ₁ and O ₂ are corrected using value E ₁ in a conventional manner, and signal O ₃ is corrected using value E ₂ .
[0055]
In actual use, the speed at which the material 4 is supplied to the folding assemblies 16, 17, 18 and to the forming unit 12 is determined by a motor 27 controlled by a control unit 63. The operation of the assemblies 16, 17, 18 and the forming unit 12 will not be described in detail herein, as is known and inferred in part from the above description.
[0056]
When the longitudinal position of the tube 2 is correct, i.e., when the absolute value of E ₁ is below a predetermined threshold value, the control unit maintains a constant speed of the motor 27. Conversely, if the error E ₁ is present, the feed rate of the material 4, the control unit 63 is corrected by appropriately correcting the signals O _1. If as a result of the correction is not sufficient, in addition to the motor 27, the control unit 63 may also be used to signal O _2, it acts on the design modifying device 51 by suitably modifying the amount of tension on the bent tabs 54 I do. According to the invention, the above-mentioned control, which is known per se, is based on the position error of the hole 5, which is aligned with the fold line 13 as described above, and the optical code 15 and the aligned It is not based on the formation of the design 14.
[0057]
In a preferred embodiment of the present invention, the signal I1 of the _first sensor 61 only generates a "lead window" and the second sensor 62 determines the position of the hole 5 at a given moment. actually read the position of the material 4, the control unit 63 supplies the signal I ₂ indicating the matrix of the detected pixels. The white area 15a surrounding each hole 5 simplifies reading.
[0058]
Another important feature of the present invention, the signal I ₂ is also used to calculate the lateral position error of the hole is to modify the torsion of the tube 2 with it by folding assembly 17. More specifically, in response to the lateral position error E _2, the control unit 63, by using a signal O _3, the actuator 25, in a direction or in the opposite direction is a bending assembly 17 in accordance with the sign of the error Command to rotate. This control is also performed based on the position of the hole 5 facing the optical cord 15.
[0059]
Obviously, modifications can be made to the machine 1 described herein without departing from the scope of the invention. In particular, the second sensor 62 is replaced by any other type of sensor, for example a linear continuous photosensitive element extending transversely to the feeding direction of the tube 2, as opposed to extracting the instantaneous image, The position of the hole 5 can be reconstructed by scanning the area of the hole as the material is fed forward. Also, different positional references can be used in alignment with the fold line 13.
[Brief description of the drawings]
FIG.
1 is a front view of a packaging machine featuring a packaging material supply adjustment device according to the present invention.
FIG. 2
FIG. 3 is a perspective view of a station for supplying and folding package material.
FIG. 3
FIG. 2 is a schematic side view of a forming station on the machine of FIG. 1.
FIG. 4
1 is a diagram of a packaging material supply and regulation device according to the present invention.
FIG. 5
FIG. 3 is a view showing a part of a package material.

Claims (7)

A longitudinal folding unit (9) for longitudinally folding the web (3) to form a continuous tube (2), and periodically interacting with said tube (2) to provide equally spaced lateral directions A forming unit (12) having at least two pairs of jaws (37) for sealing the tube along a band (45); and controlling the supply of the tube (2) and the longitudinal position of the tube (2). And a control device (60) comprising means (7, 27, 51) for correcting the angular position of the tube (2) and means (17, 25) for correcting the angular position of the tube (2). 4) a continuous web (3) of packaging material (4) comprising a design (14) and a series of fold lines (13) to assist in folding the packaging material on said forming unit (12) From A machine (1) for packaging a flowable food product in a package, wherein the control device (60) for controlling the supply of the tube is formed on the material (4); Detecting means (62) for detecting the position of the optically detectable element (5) aligned with the folding line (13); and the optically detected element detected by the detecting means (62). depending on the longitudinal and lateral position respective error detectable elements (5) _(E 1, _{E 2),} and said means (7,27,51) for correcting the longitudinal position of said tube, Means for modifying the angular position of said tube (2) and means (63) for controlling said means (17, 25). The machine according to claim 1, wherein the optically detectable element is a pre-laminated hole (5) in the material (4). The means for correcting the longitudinal position of the tube comprises a powered roller (7) arranged upstream from the longitudinal folding unit (9). The machine according to. The means (51) for modifying the longitudinal position of the tube is carried by one jaw (37) of each pair of jaws (37) and interacts with the material (4), 4. The machine according to claim 1, comprising two folding tabs (54) giving (4) a variable amount of tension. Said means for correcting the angular position of said tube (2) form part of said longitudinal folding unit (9) and rotate at least with respect to the longitudinal supply axis (A) of said tube (2). Comprising one folding assembly (17) and an actuator (25) controlled by the control device (60) for adjusting the position of the folding assembly (17) around the axis (A). The machine according to any one of claims 1 to 4, characterized in that: A sensor (61) formed on the material (4) for sensing an optical alignment code (15) and aligning with the design (14), the sensor (61) comprising the control device Machine according to one of the preceding claims, characterized in that it is connected to (60) and generates a signal (I ₁ ) for enabling the detection means (62) to be read. . A machine according to any one of the preceding claims, wherein the sensing means comprises a video camera (62).