EP4086211A1

EP4086211A1 - Misalignment detector and misalignment detection method in a film rewinder machine

Info

Publication number: EP4086211A1
Application number: EP21382401.4A
Authority: EP
Inventors: Jordi Prat Gil; Jordi ARGILÉS LLORENS
Original assignee: Comexi Group Industries SA
Current assignee: Comexi Group Industries SA
Priority date: 2021-05-04
Filing date: 2021-05-04
Publication date: 2022-11-09
Anticipated expiration: 2041-05-04
Also published as: CA3157171A1; ES2965263T3; EP4086211B1

Abstract

Film rewinder machine with misalignment detector comprising a rewinder station (10), connected to a conveyance path (3) of a film band (1), including at least one rewinder shaft (11a, 11b) configured to support and rotate at least one core to wind said at least one film band (1) around the core forming a roll (4); wherein the machine further comprises at least one laser telemeter (20) configured to be placed in a measurement position and to project a laser beam directed towards the at least one rewinder shaft in a plane perpendicular to the at least one rewinder shaft, at an offset distance in a transversal direction over at least one predefined edge position, the laser telemeter (20) being configured to detect any edge misalignment in the transversal direction (TD) equal to or bigger than said offset distance.

Description

Technical field

The present invention is directed towards misalignment detector and a misalignment detection method in a film rewinder machine.
A film rewinder machine is a machine which conveys a film band in a conveyance direction through a conveyance path reaching a rewinder station, where said film band in wound around a core to form a roll.
The machine can include several stations in successive segments of the conveyance path to perform different operations on the film band, such as cutting, printing, laminating, among others.
The misalignment detector detects a side edge misalignment of the side edges of the film bands wind in the roll, which produces a problem known as telescoping.

State of the Art

Rewinding machines receiving one or several film bands from a film feeder for rewinding one or several rolls simultaneously are already known.
On those machines, said film feeder transport the film band or film bands in tension through a convey path defined between parallel feeder shafts to a rewinder station where each film band is winded around a core supported on a winding shaft forming a roll. The film material constitutive of the film band is introduced in the film feeder from an unwinding roll supported in an unwinding shaft.
Precisely control the tension of the film material extending between the unwinding roll and the rewind rolls is critical to ensure proper slitting and rewinding without edge misalignments, and the change in diameter of the unwinding roll and of the rewinding roll make such control very difficult. This is especially true in the case of lightweight stretchable web materials such as acetate. Generally, a relatively great amount of pulling force and resulting web tension are required to unwind the web from the unwinding roll. The amount of pulling force required increases as the diameter of the unwinding roll decreases and the resulting leverage is reduced.
If the modification of the pulling forces required to unwind the film material is not correctly coordinated with the change in diameter of the unwinding roll, then over-spinning can occur and the film band weave laterally, or the tension can be uneven during the entire winding operation producing changes in the width of the elastic materials producing uneven rewinded rolls. The resulting product rolls are not uniformly edge aligned, but instead have a telescoping or other undesirable configuration.
Those problems are typically manually detected by an experienced operator of the machine looking at the side surfaces of the rewinded rolls and determining adjustments of the operational parameters of the machine based on its expertise. But this process requires experienced and well trained personnel, is time consuming and produces different results depending on the operator in charge of the machine.
Several devices for detecting edge misalignments in a roll using light are also known, for example through documents KR20120023428A and KR20170022154A . Both documents describe the use of a light beam perpendicular to the side surface of a roll to detect unevenness of said side surface indicative of an edge misalignment of the winded film band.
When there are multiple rolls on the same axis, the solution described in these documents makes it necessary to place the sensor between two rolls.
Documents KR19970047895A and WO2020046010A1 describe an alternative solution to detect edge misalignment in a roll, using an obliquus light and a camera facing the side surface of the roll for detecting the shadows projected by the edge misalignments. This detection system presents similar problems than the previously described system.
The present invention solves the above and other problems.

Brief description of the invention

The present invention is directed, according to a first aspect, towards a misalignment detector in a film rewinder machine.
The proposed machine comprises, in a manner known in the state of the art:

a film feeder configured to provide at least one tensioned film band of a laminar flexible material conveyed in a conveyance direction along a conveyance path maintaining two opposed side edges of said film band in predefined edge positions in a transverse direction perpendicular to the conveyance direction, the band film feeder including an automatic film tensioning device to keep the film band at a constant tension during its conveyance;
a rewinder station, connected to the conveyance path for receiving said at least one tensioned film band, the rewinder station including at least one rewinder shaft with an axis parallel to the transverse direction and configured to support and rotate at least one core to wind said at least one film band around the core forming a roll.

According to that the film feeder provides the rewinder station with a continuum stream of a tensioned film band conveyed in a convey direction following a convey path. Typically, the film feeder comprises a plurality of feeder shafts parallel to each other which support the film band defining said convey path.
The film rewinder machine can be, for example, a slitting machine, a lamination machine, or a printing machine such a digital printing machine, a flexographic printing machine or an offset printing machine.
The laminar flexible material can be for example a plastic film material, which typically has some degree of elasticity, or a paper material.
Said film band is conveyed through the convey path maintaining two opposed side edges of the film band in correspondent predefined edge positions in a transverse direction.
Said transverse direction is a direction perpendicular to the convey direction and coplanar with the film band. Typically, the transverse direction is parallel to the feeder shafts. According to that, each side edge of the film band is maintained, during its conveyance along the conveyance path, in a plane perpendicular to said feeder shafts, maintaining the film band between two of said planes parallel to each other spaced apart a film band width distance.
The rewinder station includes at least one rewinder shaft, typically parallel to the feeder shafts, which supports at least one core connected to one end of the film band.
When said at least one rewinder shaft are several rewinder shafts, all said rewinder shafts are parallel to each other.
Typically, the rewinding shaft includes a retention device configured to retain the core in a predefined position in the transverse direction and also in an angular position, so that the actuated rotation of the rewinding shaft produces the rotation of the at least one core, producing the winding of the film band around the core, generating a roll.
Preferably the actuated rotation of the rewinding shaft is coordinated, through a control device, with an actuated rotation of at least some of the feeder shafts to keep the film band at a predefined tension, considering the variation in diameter of the winded roll.
The proposed invention further comprises the following elements, not known in the state of the art:

at least one laser telemeter configured to be placed in a measurement position and to project a laser beam directed towards the at least one rewinder shaft in a plane perpendicular to the at least one rewinder shaft when in said measurement position, said plane being at an offset distance in the transversal direction, over at least one of said predefined edge positions of said at least one film band wound around the core, the laser telemeter being configured to detect any edge misalignment in the transversal direction equal to or bigger than said offset distance, in regard to the predefined edge position, of the side edges of the film band wound in the roll.

A laser telemeter is a device including a laser emitter and a laser receiver adjacent to each other configured to emit a narrow laser beam through the laser emitter and to detect, through the laser receiver, a reflected light from said laser beam impacting against an object facing the laser emitter. The time of flight of the light between the emission of the laser beam and the detection of the reflected light allows a precise measurement of the existing distance between the laser emitter and the object interrupting the laser beam.
The laser telemeter is configured to emit a laser beam in a plane perpendicular to the at least one rewinder shaft, in a plane perpendicular to the transverse direction, and directed towards the at least one rewinder shaft, it is to say that the laser beam is emitted preferably against the at least one rewinder shaft or adjacent to said at least one rewinder shaft, preferably perpendicular thereto.
The laser telemeter is also configured to be positioned, in the transverse direction, in a measurement position where said plane, through which the laser beam is emitted, is placed at an offset distance, in the transverse direction, in regard to plane containing one side edge of the film band positioned at the predefined edge position. The laser beam, emitted in said measurement position, is parallel to a side surface of one roll formed in the at least one rewinder shaft, the side surface facing said laser beam, and the laser beam is separated from said side surface the offset distance. Any deviation, equal or bigger than the offset distance, of the side edge of the film band winded in the roll in regard to the predefined side edge position will interfere with the laser beam producing a detection of the edge misalignment. Furthermore, the laser telemeter can detect the distance between the laser emitter and the side edge causing said interruption and therefore, it can detect which portion of the roll includes the side edge misalignment.
According to a second aspect, the present invention is directed to a film rewinder operational method of a film rewinder machine. In a manner already known, the method comprises:

convey at least one tensioned film band of a laminar flexible material in a conveyance direction along a conveyance path maintaining two opposed side edges of said film band in predefined edge positions in a transverse direction perpendicular to the conveyance direction;
wind each of said at least one film band around a core forming a roll.

The present invention further proposes, in a manner not known in the state of the art, the following steps:

analyze at least one side edge of the at least one film band using at least one laser telemeter to detect any edge misalignment in the transversal direction equal to or bigger than a given offset distance, in regard to the predefined edge position, of the side edges of the film band wound in the roll; and
associate operational parameters of the machine during the winding of said at least one film band with information provided by the at least one laser telemeter and use said information and associated operational parameters to at least automatically adjust the operational parameters of later winding operations of said machine to reduce or avoid said edge misalignments.

According to that the proposed method, which can be applied to a machine such the machine described above, includes a first step for detecting an edge misalignment using at least one laser telemeter.
Later, the information obtained by said laser telemeter is associated with the operational parameters existing in the machine during the winding of the film band. Using a closed loop analysis of the operational parameters of the machine and of the edge misalignments detected through the laser telemeter the operational parameters can be modified to avoid or reduce the presence of edge misalignments in future winding operations.
The analysis of the at least one side edge can be performed by projecting at least one laser beam towards the at least one rewinder shaft in a plane perpendicular to the at least one rewinder shaft, said plane being at an offset distance, in the transversal direction, over the predefined edge position and by measuring the fly time said laser beam.
Other features of the invention appear from the following detailed description of an embodiment.

Brief description of the Figures

The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be taken in an illustrative and non-limitative manner, in which:

Fig. 1A shows a schematic perspective view of the proposed film rewinder according to a first embodiment in which the film band is split between upper and lower film bands which are wound around an upper rewinder shaft and a lower rewinder shaft forming upper rolls and lower rolls, and wherein upper laser telemeters emit laser beams towards the upper rewinder shaft and lower laser telemeters emit laser beams towards the lower rewinder shaft, the upper laser telemeters and the lower laser telemeters being supported on the same carriages;
Fig. 1B shows an embodiment similar to that shown on Fig. 1A wherein the upper laser telemeters are supported on upper carriages and the lower laser telemeters are supported on lower carriages;
Figs. 2A and 2B shows an embodiment similar to that shown on Figs. 1A and 1B wherein the same laser telemeters emit laser beams towards the upper rewinder shaft, as shown in Fig. 2A, and later the same laser telemeters are adjusted to emit laser beams towards the lower rewinder shaft, as shown in Fig. 2B;
Figs. 3A and 3B shows an embodiment similar to that shown on Figs. 1A and 1B wherein one single laser telemeters is automatically actuated to be moved along said transverse guide in the transverse direction and to be stopped placing the at least one laser telemeter over different measurement positions to measure misalignments of different side edges of the film bands wound in the rolls;
Figs. 4A and 4B shows a schematic cross section of the film rewinder shown in any of the preceding claim wherein Fig. 4A shows upper and lower rolls formed in the upper and lower rewinder shafts placed in the rewinder position, and Fig. 4B shows a later step when said rolls have been moved to the extraction position and new empty cores are placed in the rewinder position, inverting the positions of the first and second upper rewinder shafts and of the first and second lower rewinder shafts.

Detailed description of an embodiment

The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, to be taken in an illustrative and not limitative.
The proposed film rewinder machine with misalignment detector includes a film feeder (not shown) which conveys a film band 1 of a laminar flexible material in a conveyance direction CD along a conveyance path 3 towards a rewinder station 10.
Said film feeder also includes an automatic film tensioning device to keep the film band 1 at a constant tension during its conveyance, avoiding variations in the tension of the film band 1, which could produce an elastic elongation of the film band 1, causing a width reduction. This automatic film tensioning device is well known in the state of the art and many different approaches are possible, typically including a very precise control of the rotation speeds of several cylinders on which the film band 1 is supported along the conveyance path 3.
The film feeder is also configured to maintain the two opposed side edges E of the film band 1 in predefined edge positions in the transverse direction TD. Said transverse direction TD is a direction perpendicular to the conveyance direction CD. This can be achieved, for example, using an optical detector to determine the precise position of the side edge E of the film band 1.
The rewinder station 10 is feed with the film band 1 from the film feeder and rewinds said film band 1 around at least one core supported on a rewinder shaft 11a, 11b perpendicular to the conveyance direction CD.
The machine further comprises at least one laser telemeter 20 configured to project a laser beam towards the rewinder shaft 11a, 11b, in a plane perpendicular to the rewinder shaft 11a, 11b.
Said laser telemeter 20 is placed in a measurement position at an offset distance from the film edge, so that a misalignment of said film edge equal to or bigger than said offset distance will interrupt the laser beam producing its detection.
According to an embodiment the at least one laser telemeter 20 are two laser telemeters 20 configured to project parallel laser beams separated a distance, in the transverse direction TD, equal to the distance between the two opposed edges of the film band 1 in the transverse direction TD plus two times the offset distance to detect any edge misalignment simultaneously on both side surfaces of the same roll 4.
It is also proposed to convey several film bands through said conveyance path 3. In this case each film band 1 will be wound around an independent core supported on the at least one rewinder shaft 11a, 11b defining one roll 4.
The machine can comprise a carriage 21, supporting said at least one laser telemeter 20, slidably attached to a transverse guide and automatically actuated to be moved along said transverse guide in the transverse direction TD and to be stopped placing the at least one laser telemeter 20 over at least one of said measurement positions to measure misalignments of different side edges E of the film bands 1 wound in the rolls. For example, in figures 3A and 3B, different stop positions of the same laser telemeter 20 in the same machine are shown. In that manner, a single laser telemeter 20 can analyze all the side edges of all the rolls winded simultaneously on the same axis.
Furthermore, if the at least one laser telemeter 20, or a mirror affecting the laser beam emitted by the at least one laser telemeter 20, is pivotally mounted around an axis parallel to the at least one rewinder shaft 11a, 11b and is automatically actuated to alternatively direct the laser beam towards the at least one upper rewinder shaft 11a and towards the at least one lower rewinder shaft 11b, one single laser telemeter 20 can analyze all the side edges of all the rolls winded simultaneously on several axis.
If said analysis is performed during the final moments of the winding process before the roll is completed, this analysis can be performed simultaneously with the winding process, not affecting the productivity of the machine.
Said carriage 21 can support one or several laser telemeters 20, for example two laser telemeters 20 emitting parallel laser beams as described above. The carriage 21 is automatically actuated to be moved in the transverse direction TD along the transverse guide, to position the laser telemeters 20 in different measurement positions to detect misalignments on different side surfaces of the same roll 4 or of different rolls.
According to an additional embodiment of the present invention, the at least one rewinder shaft 11a, 11b includes at least one upper rewinder shaft 11a and at least one lower rewinder shaft 11b parallel to each other, wherein the conveyance path 3 splits between an upper conveyance path 3a, which conveys one or several upper film bands 1a, connected to the at least one upper rewinder shaft 11a and a lower conveyance path 3b, which conveys one or several lower film bands 1b, connected to the at least one lower rewinder shaft 11b.
The at least one upper rewinder shaft 11a supports one core for each upper film band 1a, which is winded around said core defining an upper roll. The at least one lower rewinder shaft 11b supports one core for each lower film band 1b, which is winded around said core defining a lower roll. The at least one upper film band 1a and the at least one lower film band 1b are alternated film bands 1 so that the upper film bands 1a forming the upper rolls are separated, in the transverse direction TD, a distance equal to the width of the lower film bands 1b, and the lower film bands 1b are separated, in the transverse direction TD, a distance equal to the width of the upper film bands 1a.
The at least one laser telemeter 20 includes at least one upper laser telemeter 20a, directed towards the at least one upper rewinder shaft 11a and configured to detect any edge misalignment of the side edges E of the upper film bands 1a wound in the upper rolls, and at least one lower laser telemeter 20b, directed towards the at least one lower rewinder shaft 11b to detect any edge misalignment of the side edges E of the lower film bands 1b wound in the lower rolls. According to this, the at least one upper laser telemeter 20a is responsible to detect edge misalignments affecting the at least one upper film band 1a, and the at least one lower laser telemeter 20b is responsible to detect edge misalignments affecting the at least one lower film band 1b.
As described above, the upper laser telemeter 20a can include two upper laser telemeters 20a separated, in the transverse direction TD, a distance and emitting parallel laser beams, and the lower laser telemeter 20b can include two lower laser telemeters 20b separated, in the transverse direction TD, a distance and emitting parallel laser beams.
Alternatively, the at least one laser telemeter 20 or a mirror affecting the laser beam emitted by the at least one laser telemeter 20, is pivotally mounted around an axis parallel to the at least one rewinder shaft 11a, 11b and is automatically actuated to alternatively direct the laser beam towards the at least one upper rewinder shaft 11a and towards the at least one lower rewinder shaft 11b.
Said at least one laser telemeter 20 can also be two laser telemeters 20 emitting parallel laser beams.
According to another embodiment, the carriage 21 supports the at least one upper laser telemeter 20a and the at least one lower laser telemeter 20b. Alternatively, the carriage 21 includes an upper carriage 21a supporting the at least one upper laser telemeter 20a and a lower carriage 21b supporting the at least one lower laser telemeter 20b, said upper carriage 21a and lower carriage 21b being independently actuated allowing an independent detection of side misalignments of the upper film bands 1a and of the lower film bands 1b.
The at least one rewinder shaft 11a, 11 b can be movable between a roll winding position, where at least a part of the film band 1 is bound around the core, and a roll extraction position where a finished roll is detached from the film band 1 conveyed through the conveyance path 3 and is extracted from the rewinding shaft, for example through a free end of said shaft. The at least one laser telemeter 20 can be configured to emit the laser beam preferably towards the at least one rewinder shaft 11a, 11b when placed in the roll winding position, permitting the detection being performed simultaneously with the winding, increasing the productivity, but alternatively said laser beam can be emitted towards the at least one rewinding shaft when placed in the roll extraction position.
The at least one rewinder shaft 11a, 11b can also include a first rewinder shaft 11a, 11b and a second rewinder shaft 11a', 11b', parallel to each other and with interchangeable positions between the roll winding position and the roll extraction position.
When the machine includes at least one upper rewinder shaft 11a, it can be movable between an upper roll winding position, where a part of the upper film band 1a is bound around the core, and an upper roll extraction position where a finished upper roll is detached from the upper film band 1a conveyed through the upper conveyance path 3a and is extracted from the at least one upper rewinding shaft 11a.
For example, the first and second rewinder shafts 11a, 11a', the first and second upper rewinder shafts 11a, 11a', or the first and second lower rewinder shafts 11b, 11b' can be supported on cantilever on a rotating mechanism with a rotation center placed between both rewinder shafts, permitting the exchange of their positions by rotating around said rotation center. Once their positions have been exchanged, the rolls recently positioned in the extraction position are detached from the respective upper or lower film band 3a, 3b, connecting said upper or lower film band 3a, 3b to respective new empty cores supported in the rewinder shaft recently positioned in the winding position, allowing for a seamless winding, and permitting the extraction of the recently formed rolls from the rewinding shaft placed in the extraction position while new rolls are formed.
The at least one laser telemeter 20 can be configured to emit the laser beam towards the at least one upper rewinder shaft 11a when placed in the upper roll winding position or when placed in the upper roll extraction position.
Similarly, the at least one lower rewinder shaft 11b can be movable between a lower roll winding position, where a part of the lower film band 1b is bound around the core, and a lower roll extraction position where a finished lower roll is detached from the lower film band 1b conveyed through the lower conveyance path 3b and is extracted from the at least one lower rewinding shaft, In this case the at least one laser telemeter 20 is configured to emit the laser beam towards the at least one lower rewinder shaft 11b when placed in the lower roll winding position or when placed in the lower roll extraction position.
The at least one upper rewinder shaft 11a can include a first upper rewinder shaft 11a and a second upper rewinder shaft 11a', parallel to each other and with interchangeable positions between the upper roll winding position and the upper roll extraction position and the at least one lower rewinder shaft 11b includes a first lower rewinder shaft 11b and a second lower rewinder shaft 11b', parallel to each other and with interchangeable positions between the lower roll winding position and the lower roll extraction position.
According to an additional embodiment, the at least one laser telemeter 20 is connected to a control device configured to monitor operational parameters of the machine and configured to operate adjustment devices included in the machine to modify said operational parameters in response to measurements obtained from said laser telemeter 20.
The operational parameters can include the material constitutive of the film band, the conveyance velocity, or parameters indicative thereof, the film band 1 tension or parameters indicative thereof, torque of the at least one rewinder shaft 11a, 11b and/or of feeder shafts, film band compression in a nip between two feeder shafts or parameters indicative thereof, among others, and the adjustment devices can include several driving motors of the rewinding shafts and/or the feeder shafts, adjustment motors driving a movement of a feeder shaft against another feeder shaft to regulate the compression force in the nip there between.
Preferably the predefined edge positions of the at least one film band 1 are defined by multiple cutters, integrated in a slitter station, interfering with the conveyance path 3 for cutting a film material, wider than the film band 1 and transported through said conveyance path 3, in one or several film bands 1. This type of machine is known as a slitter machine.
The slitter station can be integrated in the film feeder, and the film material can be introduced in the film feeder from a feeding roll which is unwound to introduce the film in the conveyance path 3.
The present invention is also directed to a film rewinder operational method of a film rewinder machine. First, at least one tensioned film band 1 of a laminar flexible material is conveyed in a conveyance direction CD along a conveyance path 3 maintaining two opposed side edges E of said film band 1 in predefined edge positions in a transverse direction TD perpendicular to the conveyance direction CD. Then, each of said at least one film band 1 is wound around a core forming a roll.
Then, the method further includes analyze at least one side edge E of the at least one film band 1 using at least one laser telemeter 20 to detect any edge misalignment in the transversal direction equal to or bigger than a given offset distance, in regard to the predefined edge position, of the side edges E of the film band 1 wound in the roll.
Then operational parameters of the machine during the winding of said at least one film band 1 are associated with information provided by the at least one laser telemeter 20 and used said information and associated operational parameters to at least automatically adjust the operational parameters of later winding operations of said machine to reduce or avoid said edge misalignments.
According to that the proposed method, which can be applied to a machine such the machine described above, includes a first step for detecting an edge misalignment using at least one laser telemeter 20.
Later, the information obtained by said laser telemeter 20 is associated with the operational parameters existing in the machine during the winding of the film band 1. Using a closed loop analysis of the operational parameters of the machine and of the edge misalignments detected through the laser telemeter 20 the operational parameters can be modified to avoid or reduce the presence of edge misalignments in future winding operations.
The method can further comprise automatically comparing the operational parameters of the machine when edge misalignments are detected and when edge misalignments are not detected to determine the automatic adjustments required to reduce or avoid said edge misalignments.
The at least one laser telemeter 20 will be preferably used to detect edge misalignments on the roll while the winding of the film band 1 in the roll is performed.
Multiple side edges E of the at least one film band 1 can be successively analyzed by the same laser telemeter 20, moving the laser telemeter 20 from one measurement position to another measurement position.
When the at least one winding shaft is movable between the roll winding position and the roll extraction position, the edge misalignments can be measured directing the laser beam towards the at least one winding shaft positioned in the roll winding position. In this case, the at laser beams shall be reoriented towards the at least one winding shaft positioned in the roll extraction position to allow its use as a visual reference.
Said reorientation of the laser beam can be achieved by tilting the laser telemeter 20 or by tilting a mirror affecting the laser beam.
Alternatively, the detection of the edge misalignments and the visual reference can be both performed on the at least one winding shaft while positioned in the roll extraction position.
It will be understood that various parts of one embodiment of the invention can be freely combined with parts described in other embodiments, even being said combination not explicitly described, provided that such combination is within the scope of the claims and that there is no harm in such combination.

Claims

Misalignment detector in a film rewinder machine comprising:
a film feeder configured to provide at least one tensioned film band (1) of a laminar flexible material conveyed in a conveyance direction (CD) along a conveyance path (3) and to maintain two opposed side edges (E) of said film band (1) in predefined edge positions in a transverse direction (TD) perpendicular to the conveyance direction (CD), the film feeder including an automatic film tensioning device to keep the film band (1) at a constant tension during its conveyance;

a rewinder station (10), connected to the conveyance path (3) for receiving said at least one tensioned film band (1), the rewinder station (10) including at least one rewinder shaft (11a, 11b) with an axis parallel to the transverse direction (TD) and configured to support and rotate at least one core to wind said at least one film band (1) around the core forming a roll (4);

characterized in that the misalignment detector comprises:
at least one laser telemeter (20) configured to be placed in a measurement position and to project a laser beam directed towards the at least one rewinder shaft (11a, 11b) in a plane perpendicular to the at least one rewinder shaft when in said measurement position, said plane being at an offset distance in the transversal direction, over at least one of said predefined edge positions of said at least one film band wound around the core, the laser telemeter (20) being configured to detect any edge misalignment in the transversal direction (TD) equal to or bigger than said offset distance, in regard to the predefined edge position, of the side edges (E) of the film band wound in the roll.
The misalignment detector according to claim 1 wherein the at least one laser telemeter is configured to emit the laser beam against the at least one rewinder shaft.
The misalignment detector according to claim 1 or 2 wherein the at least one laser telemeter are two laser telemeters configured to project parallel laser beams separated a distance, in the transverse direction, equal to the distance between the two opposed edges of the film band in the transverse direction plus two times the offset distance to detect any edge misalignment simultaneously on both side edges of the film band.
The misalignment detector according to claim 1, 2 or 3 wherein
the band film feeder conveys several film bands through said conveyance path; wherein each film band is wound around an independent core supported on the at least one rewinder shaft defining one roll; and wherein
the machine further comprises a carriage (21), supporting said at least one laser telemeter, slidably attached to a transverse guide and automatically actuated to be moved along said transverse guide in the transverse direction and to be stopped placing the at least one laser telemeter over at least one of said measurement positions to measure misalignments of different side edges of the film bands wound in the rolls.
The misalignment detector according to any preceding claim wherein
the at least one rewinder shaft (11a, 11b) includes at least one upper rewinder shaft (11a) and at least one lower rewinder shaft (11b) parallel to each other, wherein the conveyance path (3) splits between an upper conveyance path (3a), which conveys at least one upper film band (1a), connected to the at least one upper rewinder shaft (11a) and a lower conveyance path (3b), which conveys at least one lower film band (1b), connected to the at least one lower rewinder shaft (11b); wherein
the at least one upper rewinder shaft (11a) supports a core for winding each upper film band (1a) defining an upper roll and the at least one lower rewinder shaft (11b) supports a core for winding each lower film band (1b) defining a lower roll, the at least one upper film band (1a) and the at least one lower film band (1b) being alternated film bands; and wherein
the at least one laser telemeter (20) includes at least one upper laser telemeter (20a), directed towards the at least one upper rewinder shaft (11a) configured to detect any edge misalignment of the side edges (E) of the upper film bands (1a) wound in the upper rolls, and at least one lower laser telemeter (20b), directed towards the at least one lower rewinder shaft (11b) to detect any edge misalignment of the side edges (E) of the lower film bands (1b) wound in the lower rolls, or
the at least one laser telemeter (20) or a mirror affecting the laser beam emitted by the at least one laser telemeter (20) is pivotally mounted around an axis parallel to the at least one rewinder shaft (11a, 11b) and is automatically actuated to alternatively direct the laser beam towards the at least one upper rewinder shaft (11a) and towards the at least one lower rewinder shaft (11b).
The misalignment detector according to claim 5 when depending on claim 4 wherein
the carriage supports the at least one upper laser telemeter and the at least one lower laser telemeter; or
the carriage (21) includes an upper carriage (21a) supporting the at least one upper laser telemeter (20a) and a lower carriage (21b) supporting the at least one lower laser telemeter (20b), said upper carriage (21a) and lower carriage (21b) being independently actuated.
The misalignment detector according to any preceding claim wherein the at least one rewinder shaft (11a, 11b) is movable between a roll winding position, where a part of the film band is bound around the core, and a roll extraction position where a finished roll is detached from the film band (1) conveyed through the conveyance path (3) and is extracted from the rewinding shaft (11a, 11b), and wherein the at least one laser telemeter (20) is configured to emit the laser beam towards the at least one rewinder shaft (11a, 11b) when placed in the roll winding position or when placed in the roll extraction position; or wherein
the at least one upper rewinder shaft (11a) is movable between an upper roll winding position, where a part of the upper film band is bound around the core, and an upper roll extraction position where a finished upper roll is detached from the upper film band (1a) conveyed through the upper conveyance path (3a) and is extracted from the at least one upper rewinding shaft (11a), and wherein the at least one laser telemeter (20) is configured to emit the laser beam towards the at least one upper rewinder shaft (11a) when placed in the upper roll winding position or when placed in the upper roll extraction position, and the at least one lower rewinder shaft (11b) is movable between a lower roll winding position, where a part of the lower film band (1b) is bound around the core, and a lower roll extraction position where a finished lower roll is detached from the lower film band (1b) conveyed through the lower conveyance path (3b) and is extracted from the at least one lower rewinding shaft (11b), and wherein the at least one laser telemeter (20) is configured to emit the laser beam towards the at least one lower rewinder shaft (11b) when placed in the lower roll winding position or when placed in the lower roll extraction position.
The misalignment detector according to claim 7 wherein
the at least one rewinder shaft includes a first rewinder shaft (11a, 11b) and a second rewinder shaft (11a', 11b'), parallel to each other and with interchangeable positions between the roll winding position and the roll extraction position; or wherein
the at least one upper rewinder shaft (11a) includes a first upper rewinder shaft (11a) and a second upper rewinder shaft (11a'), parallel to each other and with interchangeable positions between the upper roll winding position and the upper roll extraction position and the at least one lower rewinder shaft (11b) includes a first lower rewinder shaft (11b) and a second lower rewinder shaft (11b'), parallel to each other and with interchangeable positions between the lower roll winding position and the lower roll extraction position.
The misalignment detector according to any preceding claim wherein the at least one laser telemeter is connected to a control device configured to monitor operational parameters of the machine and configured to operate adjustment devices included in the machine to modify said operational parameters in response to measurements obtained from said laser telemeter.
The misalignment detector according to any preceding claim wherein the predefined edge positions of the at least one film band are defined by multiple cutters, integrated in a slitter station, interfering with the conveyance path for cutting a film material, wider than the film band and transported through said conveyance path, in one or several film bands.
The misalignment detection method in a film rewinder machine, the method comprising:
convey at least one tensioned film band (1) of a laminar flexible material in a conveyance direction (CD) along a conveyance path (CP) maintaining two opposed side edges (E) of said film band (1) in predefined edge positions in a transverse direction (TD) perpendicular to the conveyance direction (CD);

wind each of said at least one film band (1) around a core forming a roll;

characterized in that the method further comprises:
analyzing at least one side edge (E) of the at least one film band (1) using at least one laser telemeter (20) to detect any edge misalignment in the transversal direction (TD) equal to or bigger than a given offset distance, in regard to the predefined edge position, of the side edges (E) of the film band (1) wound in the roll; and

associate operational parameters of the machine during the winding of said at least one film band (1) with information provided by the at least one laser telemeter (20) and use said information and associated operational parameters to at least automatically adjust the operational parameters of later winding operations of said machine to reduce or avoid said edge misalignments.
The misalignment detection method according to claim 11 wherein the analysis of the at least one side edge (E) is performed by projecting at least one laser beam towards the at least one rewinder shaft (11a, 11b) in a plane perpendicular to the at least one rewinder shaft, said plane being at an offset distance, in the transversal direction (TD), over the predefined edge position and by measuring the fly time said laser beam.
The misalignment detection method according to claim 11 or 12 wherein the method further comprises automatically compare the operational parameters of the machine when edge misalignments are detected and when edge misalignments are not detected to determine the automatic adjustments required to reduce or avoid said edge misalignments.
The misalignment detection method according to claim 11, 12 or 13 wherein the at least one laser telemeter (20) is used to detect edge misalignments in the roll while the winding of the film band (1) in the roll is performed.
The misalignment detection method according to claim 11, 12, 13 or 14 wherein multiple side edges of the at least one film band are successively analyzed by the same laser telemeter (20).