ES2927273T3 - Packaging line for products in bags - Google Patents

Abstract

A packaging line (1) for bagged products is described, comprising: a feeding unit (11), configured to receive a web from a reel (12A) and to move it along a feeding path (P); a control unit (10), connected to the power unit (11) to move the band intermittently; a folding station (13), configured to fold the web around a folding line (131); a sealing station (14), configured to seal the first and second flaps of the folded band along the sealing lines (14A); a cutting station (15), configured to cut the packaging band and define a plurality of packaging bags; a filling station (16), configured to fill the plurality of packaging bags with a product; a sealing station, configured to seal the plurality of packaging bags. The feeding unit (11) includes a first motorized roller (11A), to move the band through the folding (13) and sealing (14) stations, by means of a first succession of advance movements (S1) with a first feeding step, and a second motor-driven roller (11B), to move the band through a second succession of advance movements (S2), with a second feeding step. The line includes an adjustment unit (18), located between the first (11A) and the second (11B) motorized roller. The adjustment unit includes a tensioning element (181), operatively in contact with the band and movable between a first operative position (P1) and a second operative position (P2), and an actuator (182), connected to the tensioning element (181). ) to vary a position of the tensioning element (181), to vary the length of the feeding path (P). (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Packaging line for products in bags

technical field

The present invention refers to a line for packaging products in bags. The technical sector to which this invention belongs is that of packaging lines for products, for example, food, which can be liquid, solid or in grain form.

prior art

In the technical sector of packaging products in bags, there are packaging lines of the state of the art which, from a strip of plastic or paper material, produce bags in which to package the products. More specifically, the web passes through a plurality of processing stations along the packaging line. Following a band feed path, the line includes a folding station, where the band is folded, a sealing station, where at least two (folded) band flaps are sealed together (for example, by heat sealing) to define an unsealed bag, a cutting station, where the unsealed bags are separated from each other, a filling station (usually a rotating carousel), where the bags are filled with product, and a sealing station , where the bag is sealed.

In these packaging lines, the web feed is a reciprocating forward motion generated by a plurality of powered rollers, each of which may be associated with (ie, designed to feed) a respective processing station. Each powered roller is characterized by a feed stage which is dependent on the productivity of the respective machine with which the powered roller is associated.

The patent document EP 3265386 B1 describes a solution to adjust the tension of a band due to its stretching between two processing stations of the same productivity. This solution comprises having an additional band stretching unit between the two stretching units that feed the band to said processing stations.

The productivity of the processing stations can be heterogeneous and, consequently, the feeding stage of the motorized rollers can be different.

On lines where this condition occurs, the difference between the feed stages of the motorized rollers could cause a loss of web tension on the line or, on the other hand, excessive web tension.

In the industry, solutions intended to regulate this problem are known. These are described in the documents EP0999134A2, BO93A000453 and BO94A000073.

The patent document EP0999134A2 describes a solution in which a mobile element (connected to the band) responds to a variation in the tension of the band by varying the position of a piston. The position of the piston is measured by a control unit which, depending on the position, determines a tension of the band. Based on the web tension, the control unit adjusts the unwinding speed of a reel to feed the web. However, this solution does not take into account the imbalances between the processing stations that are known before the start of the machine. For this reason, the system adjusts the tension only after it has detected an increase in tension, thus increasing the risk that the belt may deteriorate.

The patent document BO93A000453 illustrates a station that includes a plurality of rollers on which the band is wound. However, it does not describe in any way how this solution can overcome the imbalance generated by heterogeneous stages along the line.

The patent document BO94A000073 illustrates an adjustment unit in which the band tension is kept constant by adjusting the pressure of a negative pressure chamber, where the band is sucked. The negative pressure in the chamber is proportional to the belt tension. This is a self-regulating solution, so the system responds to variations in the length of the unwound web by adapting autonomously. However, the adjustment is not precise and not very reliable, since any failure of the negative pressure pump could negatively affect the operation. In addition, the solution of the document BO94A000073, which must guarantee a pressure inside the vacuum chamber (delimited by the band), has serious problems related to the hydraulic seals, which further reduces the degree of reliability.

Description of the invention

The object of this invention is to provide a line for packaging products in bags and a method for packaging bagged products that overcomes the aforementioned drawbacks of the prior art.

This object is fully achieved by the line for packaging products in bags and by the method for packaging products in bags according to the invention which are characterized in the appended claims. According to one aspect of this invention, the method provides a line for packaging products in bags. The line comprises a power unit. The feed unit is configured to receive a web from a reel. The feed unit is configured to move the web along a feed path. In some embodiments, the web may have split upstream and therefore the moving unit is configured to move parts of the web.

The line comprises a control unit. The control unit is connected to the power unit to move the band. In one embodiment, the control unit is connected to the power unit to move the band intermittently, through a sequence of advance movements with a predetermined spacing. According to the invention, the line includes a folding station. The folding station is configured to fold the web around a fold line. In one embodiment, the fold line is oriented along the feed path, to overlap first and second web flaps. In some embodiments, the line is also fed with two separate, overlapping bands to form the first and second flaps of the band.

According to the invention, the line includes a sealing station. The sealing station is configured to seal the first and second flaps (of the folded band). According to the invention, the sealing station is configured to seal the first and second flaps (of the folded web) along sealing lines oriented transversely to the fold line. In one embodiment, the sealing station is configured to seal the first and second flaps (of the folded web) along sealing lines oriented parallel to the fold line.

According to the invention, the line includes a cutting station. A cutting station is configured to cut the packaging web, to define a plurality of packaging bags.

According to the invention, the line includes a filling station. The filling station is configured to fill the plurality of packaging bags with a product.

According to the invention, the line includes a sealing station. The sealing station is configured to seal the plurality of packaging bags.

According to the invention, the feeding unit includes a first motorized roller. The first motorized roller is controlled by the control unit. The first powered roller is configured to move the web through the folding and/or sealing stations. The first motorized roller is configured to move the band through the folding and/or sealing stations, through a first succession of forward movements, with a first feeding stage.

According to the invention, the feeding unit comprises a second motorized roller. The second motorized roller is controlled by the control unit. The second motorized roller is controlled by the control unit to move the band through a second succession of advance movements different from the first succession of advance movements, with a second feeding stage. The second feed roll is configured to move the web through the cutting station. In one embodiment, the second powered roller is positioned upstream of the cutting station. The second motorized roller is located downstream of the first motorized roller. In one embodiment, the first feed stage and the second feed stage are different.

According to the invention, the line includes an adjustment unit. The adjustment unit is located between the first and the second motorized roller. The adjustment unit is configured to adjust the belt tension. The adjustment unit is configured to vary the length of the feed path.

According to the invention, the adjustment unit includes a tensioning element. The tensioning element is in operative contact with the band. The tensioning element is movable between a first operating position, where the feed path has a first length, and a second operating position, where the feed path has a second length. In one embodiment, the first length is different from the second length. Feed path length means the length of the strip unwound from the reel to the point where it is cut at the cutting station.

According to the invention, the adjustment unit includes an actuator. The actuator is connected to the tensioning element to vary a position of the tensioning element, to vary the length of the feed path.

In this way, by actively using the actuator, there is a more precise control of the belt tension that will always be maintained at an optimum tension value.

The actuator is connected to the control unit. The actuator is connected to the tensioning element by means of a transmission unit. The transmission unit is configured to transmit (and, if necessary, transform) the movement of the actuator into a movement of the tensioning element along an adjustment direction.

The control unit is configured to receive work data. The work data represents the operating parameters of the line. More specifically, they can include information related to the work cycle of the packaging bags and/or the working times of each station and/or the starting times of the first and second motorized rollers and/or the number of bags to be removed. to produce. According to the invention, the work data represents the first and the second sequence. According to the invention, the control unit is configured to generate control signals. The control signals are a function of the work data. The control unit is configured to control the actuator by means of the control signals, thus depending on the working data.

This characteristic makes it possible to know, before the line is activated, the speed profile (and therefore the position at each instant) that the tensioning element must follow (have). For this reason, the control is not a feedback control that has, by its very nature, a certain delay in adaptation that can sometimes be critical.

In one embodiment, the actuator is configured to move the tensioning element according to a predetermined velocity profile. In one embodiment, the velocity profile is a constant profile over time. In one embodiment, the velocity profile is a linear profile that increases or decreases with time. In one embodiment, the velocity profile is a profile that increases to a maximum point and then decreases to zero so as to avoid excessive inertial loads on the tensioning element.

In one embodiment, the actuator is an electric actuator.

The use of an electric actuator considerably simplifies the command and control of the movement of the tensioning element.

In other embodiments, the actuator may be a pneumatic actuator and/or a hydraulic actuator and/or an internal combustion engine.

In one embodiment, the adjustment unit comprises a complementary tensioning unit. The complementary tensioning element is in operative contact with the band. The complementary tensioning element can be moved to vary the tension of the band. The complementary tensioning element can be moved to vary the length of the feed path as a function of its position. In one embodiment, the complementary tensioning element is configured to vary its position automatically with the variation of the tension of the band.

The presence of a complementary tensioning element is very advantageous for the reliability of the system. Indeed, it constitutes an important support for the tensioning element if it is damaged or incorrectly controlled.

In one embodiment, the complementary tensioning element is connected to a damping member. The damping member, in one embodiment, includes an elastic element. The elastic element is configured to apply an opposing force, in opposition to the direction of a movement of the complementary tensioning element. In one embodiment, the elastic element is a spring. In other embodiments, it can be a pneumatic cylinder.

The elastic element comprises a first end connected to a frame of the adjustment unit and a second end connected to the complementary tensioning element so as to damp its movement with respect to the frame of the adjustment unit.

In one embodiment, the adjustment unit comprises a guide. In one embodiment, the tensioning element includes a slider. The slider can also be part of the adjustment unit and be rigidly connected to the tensioning element.

In one embodiment, the tensioning element includes an idler roller.

The tensioner slider is configured to translate in the guide of the adjustment unit to move the tensioner, along the direction of adjustment, from the first to the second operating position.

In one embodiment, the tensioning element is oriented parallel to the direction of the load force. In one embodiment, the tensioning element is oriented parallel to a plane perpendicular to the direction of the load force.

In one embodiment, the line comprises a voltage sensor. The tension sensor is configured to measure belt tension. The tension sensor is configured to generate tension signals, which represent the tension of the web. In one embodiment, the voltage sensor is configured to send the voltage signals to the control unit. The control unit is configured to receive voltage signals. The control unit is configured to generate at least a part of the control signals as a function of the voltage signals. The control unit is configured to cause the actuator to move the tensioning element.

The tension sensor can be an additional secondary system for use if the tension element is not correctly controlled by the control unit based on previously established working data. In one embodiment, the first powered roller is located downstream of the sealing station along the feed path.

In one embodiment, the adjustment unit (the line) comprises a plurality of fixed rollers. The plurality of stationary rollers are in operative contact with the band. The plurality of fixed rollers operate together with the tensioning element to define the path of the packaging web within the adjustment unit.

According to an embodiment not within the scope of the invention, the adjustment unit includes a tensioning element, in operative contact with a band and movable between a first operating position and a second operating position to vary the length of a band. feed path followed by the web on the packaging line.

The adjusting unit includes an actuator, connected to the tensioning element for varying a position of the tensioning element, to vary the length of the feed path. The actuator of the adjustment unit can be an electric motor or a pneumatic motor.

The adjustment unit comprises a control unit, configured to generate control signals, based on the work data, which represent operating parameters of (a first succession of advance movements of the band and a second succession of advance movements of the band, made by) a first motorized roller and a second motorized roller of the packaging line. The adjustment unit is configured to be positioned between the first and the second motorized roller of the packaging line in which the adjustment unit is integrated. In one embodiment, the control unit is connected to the actuator to control it, through the control signals, to change the position of the tensioning element.

According to another aspect of this invention, a method for packaging products in bags is provided.

The method comprises the steps according to claim 10.

In one embodiment, during the step of moving in a controlled manner, the actuator moves the tensioning element according to a predetermined velocity profile. In one embodiment, the actuator moves the tensioning element with a constant speed. In one embodiment of the method, it comprises a step of moving a complementary tensioning element, connected with the band, to vary, as a function of a complementary tension position, along the feed path.

In one embodiment, the step of moving the complementary tensioning element comprises a damping step. In this damping step, a damping member applies an opposing force on the complementary tensioning element. The counterforce is opposite to the direction of a movement of the complementary tensioning unit due to a variation of the tension of the web. In this way, the belt never reaches excessive tension values that could negatively affect the condition.

In one embodiment, the step of moving the tensioning element comprises a step of translating a slider, connected to a tensioning element, in a guide of the adjustment unit.

In one embodiment, the method comprises a feedback control step. In this feedback control stage, a tension sensor measures a belt tension value and generates corresponding tension signals, which represent the belt tension value. In this stage of feedback control, the voltage sensor sends the voltage signals to the control unit. The control unit generates the corresponding control signals, based on the voltage signals. The control unit sends the control signals to the actuator to control it during the movement of the tensioning element.

These and other features of the invention will become more apparent from the following description of a preferred embodiment thereof, illustrated purely by way of example in the accompanying drawings.

Brief description of the drawings

Figure 1 schematically illustrates a plan view of a line for packaging products in bags;

Figure 1A is a plan view of a part of the line of Figure 1;

Figure 2 is a perspective view of a part of the line of Figure 1;

Figures 3A and 3B schematically illustrate a unit for adjusting the line of Figure 1 in a first and a second operational configuration, respectively;

Figures 4A and 4B schematically illustrate two embodiments of a first succession of feed movements, performed by a first motorized roller and a second succession of feed movements, performed by a second motorized roller, respectively.

Preferred forms of embodiment of the invention

With reference to the accompanying drawings, number 1 indicates a line for packaging products in bags. The products can be liquid, solid, gaseous or in grains.

Line 1 comprises a control unit 10. Control unit 10 is configured to control the operating parameters (working parameters) of line 1. Line 1 comprises a user interface 10'. The user interface 10' is configured to allow a user to enter configuration data, which represents the operating parameters of line 1.

More specifically, the configuration data includes duty data 101. In one embodiment, the duty data 101 is data identifying the duty cycle of the line. For this reason, in some embodiments, the job data 101 represents the productivity of each machine on the line (units processed per unit of time).

Line 1 comprises a feed unit 11. Feed unit 11 is configured to receive a packaging web and to move it in line 1 along a feed path P. The feed path P changes its direction during feeding. trajectory.

According to the invention, the feed unit 11 is configured to move the band intermittently. In short, the feed unit is connected to the control unit to move the web in a succession of forward and pause movements. Each feeding and each pause defines a feeding time and a pause time, respectively.

In one embodiment, the feed path is included in a plane perpendicular to the direction of the load force. In one embodiment, the feed unit includes a plurality of feed rolls 110. The web is wound around the plurality of feed rolls 110 to move along line 1. More specifically, the plurality of feed rolls 110 it is configured to carry the belt while maintaining it at a predetermined tension value.

In one embodiment, a part of the plurality of feed rollers 110 is motorized, that is, its movement is determined by a driving force transmitted by an actuator. In one embodiment, a part of the plurality of feed rollers 110 is idle, that is, its movement is determined by the frictional force of the strip driven by the plurality of powered rollers.

In one embodiment, each motorized roller defines a respective stationary time and feed time. For this reason, within the feeding unit, the feeding line can comprise different pause and feeding times. These differences are substantially due to the processing times of each machine (units worked per unit of time).

The control unit 10 is connected to the power unit 11 to control it based on the work data 101.

In one embodiment, line 1 comprises a feed station 12. Feed station 12, in one embodiment, includes a reel 12A. In one embodiment, the feeding station 12 may comprise an already machined web reserve.

Feed station 12 is configured to feed the web to feed unit 11 to allow relative movement along the feed path P.

According to the invention, the line comprises a folding station 13. The term "station" means a plurality of elements that contribute to the performance of a specific function. The folding station 13 is configured to fold the band. According to the invention, the folding station 13 is configured to fold the web around the fold lines 131, oriented along the feed path P. The folding station 13 is configured to fold the web around the lines of folding 131, superimposing a first and a second flap of the band. The folded band is thus formed by two flaps connected at the fold line (the part of the band, in a preferred embodiment, is configured to become the bottom part of the packaged bag). In one embodiment, the folding station 13 is located downstream of the station of feeding 12.

According to the invention, line 1 comprises a sealing station 14. The sealing station 14 is configured to seal the first and second flaps of the web along sealing lines 141. The sealing station 14, in a embodiment, comprises a transverse sealing station 14A, configured to seal the first and second web flaps along transverse sealing lines 141A, perpendicular to the feed path P. The sealing station 14, in one embodiment , comprises a longitudinal sealing station 14B, configured to seal the first and second flaps of the web along longitudinal sealing lines 141B, parallel to the feed path P. In one embodiment, where the first and second flaps second can come from two bands separated from each other, the longitudinal sealing lines 141B define the bottom of the packaged bag. In one embodiment, transverse seal lines 141A define the sides of the packaged bag.

In one embodiment, the sealing station 14 is configured to seal at a first working speed. The sealing station 14 is configured for the processing, during a stationary time, of a first length of the web.

According to the invention, line 1 comprises a cutting station 15. The cutting station is configured to cut the web, separating it into a plurality of portions defining a plurality of packaging bags. The cutting station includes a 15' cutting tool. Cutting tool 15' is configured to cut the web along cut lines 151. In one embodiment, cut lines 151 are transverse, perpendicular to the feed path.

In one embodiment, the cutting station 15 is configured to seal at a second working speed. For example, cutting station 15 is configured to process, during a stationary time, a second length of web.

The control unit is configured to receive the work data 101, which represents the first and second work speeds.

According to the invention, line 1 comprises a filling station 16. The filling station 16 is configured to allow the filling of the plurality of packaging bags with the product. In one embodiment, the filling station 16 includes a filling carousel 161. The filling carousel may include a plurality of suction surfaces 162. The plurality of suction surfaces 162 are configured to retain the bags during filling by means of a negative pressure generated by air suction.

In one embodiment, line 1 comprises a conveyor 17.

Conveyor 17 is configured to pick up packaging bags from cutting station 15 and place them in fill station 16. Conveyor 17, in one embodiment, includes a suction surface 171, where each packaging bag is retained during its transport to the filling station 16.

According to the invention, line 1 comprises a sealing station. The sealing station is configured to seal (close) the packaging bags to make them hermetic (preventing the escape and entry of products). According to the invention, the feeding unit 11 comprises a first motorized roller 11A. The first motorized roller 11A is controlled by the control unit 10. The first motorized roller 11A is configured to move the web through the folding and sealing stations. The first motorized roller 11A is configured to move the band through the folding and sealing stations, through a first succession of forward movements S1, with a first feeding stage. Briefly, the first feeding stage is a feeding stage corresponding to a feeding of the strip of the first length.

In one embodiment, the first motorized roller 11A is located downstream of the sealing station. In one embodiment, the first motorized roller 11A is located upstream of the sealing station.

The first motorized roller 11A rotates at a first rotational speed. The first motorized roller 11A rotates during a first feeding time T1.

The first succession of advance movements S1 is spaced apart by a corresponding first succession of pauses.

According to the invention, the feeding unit 11 comprises a second motorized roller 11B. The second motorized roller 11B is controlled by the control unit 10. The second motorized roller 11B is configured to move the web through the cutting station. The second motorized roller 11B is configured to move the web through the cutting station by means of a second succession of feed movements S2, with a second feeding stage. In short, the second feed stage is a feed stage that corresponds to a feeding of the band of the second length.

The second motorized roller 11B rotates at a second rotation speed. The second motorized roller 11B rotates for a second advance time T2.

The second succession of advance movements S2 is spaced by a corresponding second succession of pauses.

In one embodiment, the second powered roller 11B is positioned upstream of the cutting station 15. In other embodiments, the second powered roller 11B is positioned downstream of the cutting station 15. The second powered roller 11B is positioned downstream of the first motorized roller 11A.

It should be noted that the first feeding stage and the second feeding stage are different.

In one embodiment, the first and second advance stages are different because the first advance times T1 and second advance times T2 are different for values of the first and second rotational speeds that are equal to each other. In one embodiment, the first and second feed stages are different because the first and second rotational speeds are different for values of the first T1 and second T2 feed times that are equal to each other.

According to the invention, the line 1 includes an adjustment unit 18. The adjustment unit 18 is configured to adjust the tension of the band. The adjustment unit 18 is placed, along the feed path P, between the first motorized roller 11A and the second motorized roller 11B. The adjustment unit 18 comprises a frame 180. According to the invention, the adjustment unit 18 includes a tensioning element 181. The tensioning element 18 is in operative contact with the band to maintain it at a predetermined tension value. The tensioning element 18 can move. The tensioning element 18 is movable between a first operating position P1 and a second operating position P2 to vary the feed path length P. More specifically, a first feed path length L1 P corresponds to the first position of operation. A second feed path length L2 P corresponds to a second feed path length P, different from the first feed path length. Since the choice of the first and the second position is completely arbitrary, in one embodiment, the first length L1 is greater than the second length L2. More specifically, in one embodiment, the difference between the first length L1 and the second length L2 is equal to the difference between the first advance stage and the second advance stage. Indeed, the path of the tensioning element 18 makes it possible to balance the line 1, being able to keep the tension of the band constant with the predetermined value.

According to the invention, the adjustment unit 18 comprises an actuator 182. The actuator 182 is connected to the tensioning element 181 to vary a relative position. This makes it possible to vary the length of the feed path and keep the web tension constant. In one embodiment, the control unit 10 is configured to determine control signals 102 as a function of the work data 101. The work data 101 represents the first S1 and second S2 feed motion succession and consequently the succession of first and second pauses. In one embodiment, the control unit 10 is configured to send the control signals 102 to the actuator 182 to vary the position of the tensioning element 181. For this reason, the tensioning element 181 is a controlled element that, knowing the duty cycle of the belt, it can anticipate the tension variations induced by unbalances on line 1 and can therefore guarantee optimum belt tension. In one embodiment, the control signals 102 represent a velocity profile, which represents the position of the tensioning element 181 over time. In summary, the control signals are configured to change the operating parameters of the actuator 182 (electrical power, chemical power, hydraulic power, pneumatic power, etc.) such that the required velocity profile for the tensioning element 181 is obtained. allows global control of the movement of the tensioning element 181, which can vary the speed and direction of movement. In one embodiment, actuator 182 includes an electric motor and/or an internal combustion engine and/or a pneumatic motor and/or a hydraulic motor.

In one embodiment, adjustment unit 18 includes a transfer unit 183. Transfer unit 183 is designed to transfer movement from actuator 182 to tensioning element 181.

In one embodiment, the adjustment unit includes a slider 183', limited to the tensioning element 181. In one embodiment, the adjustment unit includes a guide 183", where the slider 183' can slide to define an adjustment direction R of the tensioning element 181.

In one embodiment, the adjustment unit 18 includes a lead screw 182', integral with and rotatable with a drive shaft of the actuator 182. The terms integral and rotating mean that the lead screw 182' rotates at a rotational speed that depends on the speed of rotation of the drive shaft to specifications and any speed reducers.

The lead screw 182' engages with the slider 183' to transform a rotation of the lead screw 182' into a translation of the slider 183' along the direction of adjustment R. The translation of the slider 183' produces a variation in the position of the tensioning element 181 and a consequent variation in the length of the feed path P.

In this embodiment, the slider 183' can be moved along the lead screw 182' from a first position, corresponding to the first operating position P1 of the tensioning element 181, to a second position, corresponding to the second operating position. P2 of the tensioning element 181.

In one embodiment, the take-up element 181 is a (idle) take-up roller on which the web is wound. In one embodiment, the tensioner roller has a maximum direction of extension parallel to the direction of the load force. In a preferred embodiment, the direction of adjustment R belongs to a plane perpendicular to the direction of the force of the load. In one embodiment, the direction of adjustment R is parallel to the direction of the force of the load.

In one embodiment, adjustment unit 18 includes a plurality of stationary rollers 184. The plurality of stationary rollers 184 are in operative contact with the web. The plurality of stationary rollers 184 operate in conjunction with the tensioning element 181 to define the path of the band within the adjustment unit 18.

In one embodiment, the adjustment unit 18 comprises a complementary tensioning element 185. The complementary tensioning element can be a tension roller, on which the band is wound. The complementary tensioning element 185 is in operative contact with the band. Supplementary tension element 185 is movable to vary, as a function of relative position, the length of the feed path P. More specifically, supplementary tension element 185, in response to any variation in web tension due to faults or errors in the tensioning element 181, it is configured to vary its position, in such a way that the length of the feeding path P varies and, therefore, the tension of the band.

In one embodiment, the complementary tensioning element 185 is coupled to the frame 180 of the adjustment unit 18 by a prismatic pair. In summary, in this embodiment, the complementary tensioning element 185 comprises a carriage 185' slidable within a track 185".

In one embodiment, the adjustment unit 18 includes a damping member 186, configured to damp any sudden jolts of tension that the band may experience in particular situations. The damping member 186 is connected to the complementary tensioning element 185 to damp its movement. The damping member 186 comprises an elastic element 186' which may be a spring, instead of a pneumatic piston. The elastic element 186' is configured to apply an opposing force, opposite to the direction of a movement of the complementary tension element 195. This makes it possible to reduce the amount of movement of the complementary tension element 185 that would otherwise overload the band. .

In one embodiment, line 1 comprises a tension sensor 19. Tension sensor 19 is configured to measure web tension. The tension sensor is configured to generate tension signals 103, based on the tension value of the web.

In one embodiment, the voltage sensor is configured to send voltage signals 103 to control unit 10.

In one embodiment, control unit 10 is configured to generate control signals 102 as a function of voltage signals 103.

The control unit is then configured to send the control signals 102 to the actuator, based on which the latter is configured to vary the position of the tensioning element 181.

This embodiment makes it possible to obtain a feedback signal that allows it, if there are errors or failures in normal operation, to continue working without irreparably damaging the band.

According to an embodiment that is not within the scope of the invention, a method for packaging products in bags is provided. The method comprises a feeding step. In the feeding stage, a reel 12A feeds a web (consisting of plastic material or paper material) to a feeding unit 11.

In the feeding stage it is also possible that the web is already fed separately, ie in the form of the already separated portions.

According to an embodiment that is not within the scope of the invention, the method comprises a stage of configuring line 1. The stage of configuring line 1 comprises a stage of receiving, in a control unit 10, work data 101 , which represent the operating parameters of line 1.

The method comprises a step of feeding the strip along a feeding path, preferably belonging to a plane perpendicular to the direction of the force of the load.

In the feeding stage, a plurality of conveyors, for example a plurality of roller conveyors 110, move the web along a plurality of stations of the packaging line 1.

In one embodiment, the web is fed to a folding station 13. At this folding station 13, the method comprises a step of folding the web along the fold lines 131. The fold lines 131 are preferably oriented in parallel to the feed path P.

In the folding step, the band is folded to define a first and a second flap.

The band is then fed to a sealing station 14. At this sealing station 14, the method comprises a step of sealing the first and second flaps of the band. More specifically, in one embodiment, the sealing step comprises a transverse sealing step, wherein the first and second flaps are sealed along transverse sealing lines 14A, perpendicular to the feed path P. In one embodiment, embodiment, the sealing step comprises a longitudinal sealing step, wherein the first and second flaps are sealed along the longitudinal sealing lines 14B, parallel to the feed path P.

The sealing station 14 is characterized by a first productivity P1.

In one embodiment, the method comprises a step of cutting the band. In this cutting step, the web is cut along transverse cut lines 151, to define a plurality of packaging bags. The cutting station is characterized by a second productivity P2.

In one embodiment, the advance stage comprises a first succession of advance movements S1, carried out by a first motorized roller 11A. In one embodiment, the first powered roller 11A is located upstream of the sealing station 14. In one embodiment, the first powered roller 11A is located downstream of the sealing station 14.

In any case, the first motorized roller 11A feeds the web to the sealing station 14 by feeding it through a first feeding stage, which is correlated with the first productivity P1 of the sealing station (i.e., the number of seals per unit of weather). In this first succession of feed movements P1, the first motorized roller 11A unwinds the band in a first feed length. In this first succession of advance movements P1, the first motorized roller 11A rotates at a first speed of rotation for a first advance time T1.

In one embodiment, the advance stage comprises a second succession of advance movements S2, carried out by a second motorized roller 11B. In one embodiment, the second powered roller 11B is located downstream or upstream of the sealing station 14. In one embodiment, the second powered roller 11B is located downstream of the cutting station 15. In one embodiment, the second powered roller 11B motorized 11B is located upstream of the cutting station 15.

In any case, the second motorized roller 11B feeds the strip to the cutting station 15 by feeding it through a second feeding stage, which is correlated with the second productivity P2 of the cutting station (that is, the number of cuts per unit of weather). In this second succession of feed movements S2, the second motorized roller 11B unwinds the strip in a second feed length. In this second succession of feed movements S2, the second motorized roller 11B rotates at a second rotational speed for a second feed time T2.

For this reason, the feeding unit performs a first forward movement section and a second forward movement section, different from each other. The difference in length could cause a loss of tension and therefore a reduction in the quality of the bags.

In order to solve this problem, in one embodiment, the method comprises a step for adjusting the tension of the band. In this adjustment step, an adjustment unit 18 varies the length of the feed path P to adjust the web tension. In this adjusting step, a tensioning member 181 is moved along an adjusting direction R to vary the feed path length P and maintain the web tension at an optimum value. The adjustment stage includes a stage of controlled movement of the tensioning element 181. In this stage of controlled movement, the control unit 10 sends control signals 102 to an actuator 182 of the adjustment unit 18 to cause it to move the tensioning element. 181. The control unit generates the control signals 102 based on the work data 101.

In one embodiment, actuator 182 moves tensioner 181 with a predetermined velocity profile.

In one embodiment, the variation of the feed path P per unit time due to the movement of the tensioning element 181 must be equal to the difference between the first speed of rotation of the first motorized roller 11A and the second speed of rotation of the second motorized roller. 11B per unit of time. For this reason, in one embodiment, the velocity profile depends on the first advance stage and the second advance stage.

The drawings illustrate the succession of advance movements first S1 and second S2. In the following, an embodiment of a cycle of the method is described with reference to the drawings.

The first motorized roller 11A feeds the band of the first feeding stage, rotating at the first speed of rotation for a time equal to the first advance time T1.

The second motorized roller 11B feeds the band of the second feeding stage, rotating at the second rotational speed for a time equal to the second advance time T2.

The first feeding time T1 is greater than the second feeding time T2, since the sealing station is capable of simultaneously processing a greater number of units than the cutting station. For example, but not necessarily, the sealing station can process four units for each feed while the cutting station can process two or a single unit for each feed.

After the second feeding time T2, the second motorized roller 11B stops while the first motorized roller 11A is still in rotation. The cutting station 15 performs the cutting step in a cutting time Tt. When the cutting station 15 performs the cutting step, the second motorized roller continues to unwind the web, increasing the amount of web interposed between the first motorized roller 11A and the second motorized roller 11B. To keep the band under tension, the adjustment unit 18 moves the tensioning element 181 by means of the actuator 182, in such a way that the length of the feed path P increases. When the first motorized roller has rotated for a time equal to the first feeding time T1, the latter stops and the sealing stage begins. At this time, that is, when the first motorized roller 11A stops, the feed path P has a first length L1. In one embodiment, the first length L1 is the maximum length of the feed path P.

The sealing station 14 performs the sealing step in a sealing time Ts.

During the sealing stage, the second motorized roller 11B will continue the second succession of forward movements S2 thus recovering the band and reducing the length of the unwound band interposed between the first motorized roller 11A and the second 11B.

In order to keep the band under tension, the adjustment unit 18 moves the tensioning element 181 by means of the actuator 182 in such a way that the length of the feed path P is reduced.

In one embodiment, at the end of the sealing stage, the first motorized roller 11A remains stationary for a stationary time Tf, to allow the cutting station 14 to cut a number of units equal to the number of sealed units. When the cutting station 15 has cut the units that the sealing station 14 has sealed, the length of the band interposed between the first motorized roller 11A and 11B is minimal and the feeding path P has a second length L2. In one embodiment, the second length L2 is the minimum length of the feed path P.

In one embodiment, the step of moving the tensioning element 181 includes a translation step. In the translation step, a slider 183', connected to the tensioning element 181, translates in a guide 183" along the adjustment direction R.

Translation, in one embodiment, is generated by a lead screw 182', engaging and rotating with a drive shaft of the actuator (which in this embodiment is rotatable).

The lead screw 182' is coupled with the slider 183' of the tensioning element 181 to transform the rotary movement of the drive shaft into a translational movement of the tensioning element 181.

In one embodiment, the method comprises a step of moving a complementary tensioning element 185. In one embodiment, the step of moving the complementary tensioning element 185 includes a damping step. In this damping step, a damping member 186 damps the movement of the complementary tensioning unit 185 due to a variation of the web tension. More specifically, an elastic element 186' of the damping member 186 applies an opposing force, in the opposite direction to the direction of movement of the complementary tensioning element 185.

In one embodiment, the elastic element is a spring 186'. In this embodiment, a carriage 185' of the complementary tensioning element 185 slides inside a rail 185" made on a frame 180 of the adjustment unit 18. The sliding of the carriage 185' on the rail 185" opposes the action of the spring 186'.

In one embodiment, the method comprises a feedback control step. In this feedback control step, a tension sensor 19 measures a tension value of the web and generates corresponding tension signals 103, which represent the tension value of the web. The tension sensor 19 may be located upstream or downstream of the first and/or second motorized roller 11A, 11. In this feedback control step, the tension sensor 19 sends the tension signals 103 to the control unit. The control unit 10 generates the corresponding control signals 102, based on the tension signals 103. The control unit 10 sends the control signals 102 to the actuator 182 to control it during the movement of the tensioning element 181.

continuation

Claims (12)

1. A packaging line (1) of products in bags, comprising: - a feeding unit (11), configured to receive a band from a reel (12A) and to move it along a feeding path (P); - a control unit (10), connected to the power supply unit (11) to move the band intermittently, through a succession of advance movements with a predetermined spacing; - a folding station (13), configured to fold the band around a folding line (131) oriented along the feed path (P), to superimpose a first and a second flap of the band; - a sealing station (14), configured to seal the first and second flaps of the folded band, along sealing lines (141A) oriented transversely to the fold line (131); - a cutting station (15), configured to cut the packaging band and define a plurality of packaging bags; - a filling station (16), configured to fill the plurality of packaging bags with a product; - a sealing station, configured to seal the plurality of packaging bags; wherein the power unit (11) includes - a first motorized roller (11A), controlled by the control unit (10) to move the band through the folding (13) and sealing (14) stations, by means of a first succession of forward movements (S1) , with a first stage of feeding; - a second motorized roller (11B), controlled by the control unit (10) to move the strip through a second succession of advance movements (S2) different from that of the first succession of advance movements (S1), with a second feeding stage, the second motorized roller (11B) being positioned downstream of the first motorized roller (11A), to move the band through the cutting station (15); - an adjustment unit (18), placed between the first (11A) and the second (11B) motorized roller and configured to adjust the tension of the band, characterized in that the adjustment unit (18) includes: - a tensioning element (181), which can move between a first operating position (P1) in operative contact with the band, where the feed path (P) has a first length (L1) and a second operating position ( P2) in operative contact with the strip, wherein the feed path (P) has a second length (L2) different from the first length (L1); an actuator (182), connected to the tensioning element (181) for varying a position of the tensioning element (181) between said first and second operating positions (P1, P2), for varying the length of the feed path (P), and wherein the control unit (10) is configured to receive work data (101), which represent the first (S1) and the second (S2) succession of advance movements, and to generate control signals (102), to control the actuator (182) according to the working data (101). The line (1) according to claim 1, wherein the actuator (182) is configured to move the tensioning element (181) according to a predetermined speed profile. The line (1) according to claim 2, wherein the actuator (182) of the adjustment unit (18) includes an electric motor. 4. The line (1) according to any one of the preceding claims, wherein the adjustment unit (18) comprises a complementary tensioning element (185), in operative contact with the band and that can move to vary, depending on a relative position, the length of the feed path (P). The line (1) according to claim 4, wherein the complementary tensioning element (185) is connected to a damping member (186). The line (1) according to any one of the preceding claims, wherein the adjustment unit (18) comprises a guide (183") and the tensioning element (181) includes an idler roller and a slider (183'), configured to translate in the guide (183") of the adjustment unit (18) and pull the tensioning element (181) from the first (P1) to the second (P2) operating position. The line (1) according to any one of the preceding claims, wherein the tensioning element (181) is oriented parallel to the direction of the loading force. The line (1) according to any one of the previous claims, comprising a tension sensor (19), configured to measure the tension of the web, and wherein the control unit is configured to receive tension signals (103 ), which represent the tension of the band, of the tension sensor (19), to generate signals of control (102), based on the tension signals (103), and to cause the actuator (182), through the control signals (102), to move the tensioning element (181). The line (1) according to any one of the preceding claims, wherein the first motorized roller (11A) is located downstream of the sealing station (14) along the feed path (P), and/or or where the second motorized roller (11B) is located upstream of the cutting station (15). 10. A method for packaging products in bags comprising the following steps: - receiving the band from a reel (12A) and intermittently feeding the band along a feed path (P) using a succession of advance movements with a predetermined spacing; - folding the band around a folding line (131) oriented along the feed path (P), to superimpose a first and a second flap of the band; - sealing the first and second flaps of the band along sealing lines (141A) oriented transversely to the fold line (131); - cutting the packaging band to define a plurality of packaging bags; - filling the plurality of packaging bags with the product; - sealing the plurality of bags; wherein the feeding stage includes: - a first succession of advance movements (S1), with a first feeding stage, using a first motorized roller (11A) arranged to move the band through the folding and sealing stations; - a second succession of advance movements (S2) different from the first succession of advance movements (S1), with a second feeding stage, using a second motorized roller (11B) arranged to move the band through the station court; - adjusting the tension of the band by means of an adjustment unit (18) placed, on the packaging line, in an intermediate position between the first (11A) and the second (11B) motorized roller along the trajectory of feeding (P), characterized by comprising the following stages: - moving in a controlled manner a tensioning element (181), connected to the band, between a first operating position (P1) and a second operating position (P2), by means of an actuator (182) controlled by a control unit (10), to vary the length of the feed path (P), where, in the stage of moving in a controlled manner, the control unit (10) receives the work data (101), which represent the sequences of first (S1) and second (S2) feed movements, it generates control signals (102) based on the working data (101), and sends the control signals (102) to the actuator (182), to make it move the tensioning element (181) to vary the length of the feed path (P). The method according to claim 10, comprising a step of moving a complementary tensioning element (185), connected with the band, to vary, as a function of a position of the complementary tensioning element (185), the length of the trajectory of feeding (P). The method of claim 11, wherein the step of moving the complementary tensioning element (185) includes an absorption by damping step, wherein a damping member (186) applies an opposing force, opposite to the direction of a movement of the complementary tensioning element (185).