Patent Publication Number: US-9850089-B2

Title: Apparatus and method for controlling the unwinding of a web

Description:
TECHNICAL FIELD 
     The present disclosure relates to an apparatus and method for controlling web alignment as a web is unwound from a roll. 
     BACKGROUND OF THE DISCLOSURE 
     During the manufacture of several goods, raw materials may be required that are provided in the form of webs  2  wound onto cores  3  in roll form. For example, a manufacturing process to produce absorbent articles, such as diapers, training pants, feminine hygiene absorbent articles, incontinence absorbent articles, etc., may include materials wound on rolls such as, for example, layers of the absorbent article, elastics and components of the absorbent core. 
     In general, webs  2  unwound from rolls may have web  2  alignment issues during the manufacturing process. Some causes of web  2  alignment issues can include the properties of the web  2  material or the manner in which the web  2  material is wound onto the core. For example, as some web  2  materials are unwound from the roll, the web  2  material properties may allow a tendency for the web  2  material to either neck or curl, and/or fold upon itself in the cross direction of the web  2 . In other situations, the web  2  material may be wound on a roll in such a manner where transverse movement of the web  2  is inherent as the web  2  is unwound from the roll. For example, web  2  material unwound from a level-wound roll  1   b  must traverse the roll length  5  which introduces a large amount of web  2  weave during the manufacturing process. Additionally, some webs  2  may have the tendency to fold upon themselves in the cross direction of the web  2  when the web  2  encounters a change of direction in the web  2  path, such as a 90 degree turn. In some instances, the web  2  may encounter a twist that has been incorporated into the web  2  path as a means to turn the web  2  or to reduce web  2  weave. In prior systems, the web  2  may have been twisted with the use of a long dead bar and an idler, or non-rotating dead bar. Twists incorporated into the web  2  path for some web  2  materials can cause web  2  instability that may contribute to the web  2  folding over on itself. Web  2  foldover can also cause machine stops in order to correct the web  2  path. It can be understood by one skilled in the art that web  2  alignment or instability issues that arise early in the unwinding of the web  2  affect the web  2  alignment throughout the remainder of the process. The detection of web  2  alignment issues towards the end of the manufacturing process also allows for continuation of the web  2  alignment issues throughout the manufacturing process. 
     Web  2  alignment or instability issues can impact the quality of the finished product, aesthetically or functionally. Components of the finished product originating from webs  2  that experience web  2  alignment issues may not be placed in the desired location of the finished product. Web  2  alignment and instability issues can also cause waste and delay in the manufacturing process when the machine speed is reduced in order to control the web  2  material for desired splicing of one roll to another roll or for desired placement of the web  2  material in the finished product, for example, a cut and placed component of the absorbent core, such as a liquid distribution layer as is known to one skilled in the art. As such, a need remains to detect the web  2  alignment issues of webs  2  as they are unwound from a roll early in the manufacturing process. A further need remains to correct the web  2  alignment issues of webs  2  as quickly as possible in the manufacturing process. An additional need remains to eliminate the need to twist the web  2  in the manufacturing process. 
     SUMMARY OF THE DISCLOSURE 
     In an embodiment, an apparatus for controlling the unwinding of a web wound on a core forming a roll includes a turnbar. The roll includes a roll length. The turnbar may be configured to receive the web that is unwound from the core such that a portion of the web unwound from the core and disposed between the core and the turnbar provides an incoming web and a portion of the web after engaging the turnbar provides an outgoing web. The incoming web includes an incoming web axis and the outgoing web includes an outgoing web axis. The turnbar includes a target location to receive the incoming web. An actuator is coupled to the turnbar and the actuator includes an axis of movement substantially parallel to the outgoing web axis. A sensor is configured to measure a transverse placement of the web relative to the target location and the sensor being in electrical communication with the actuator through a controller. The sensor is configured to transmit an input signal to the controller when the transverse placement of the web differs from the target location. The controller is configured to provide an output signal to the actuator based on the input signal. The actuator is configured to receive the output signal from the controller and to move the turnbar along the axis of movement in response to the output signal such that the web maintains substantial alignment with the target location. 
     In another embodiment, an apparatus for controlling the unwinding of a web wound on a core forming a roll includes a turnbar, an actuator, a sensor, and a controller. The roll includes a roll length. The turnbar may be configured to receive the web unwound from the core such that a portion of the web unwound from the core and disposed between the core and the turnbar provides an incoming web and a portion of the web after contacting the turnbar provides an outgoing web. The incoming web includes an incoming web axis and the outgoing web includes an outgoing web axis. The turnbar includes an incoming web target location and an outgoing web target location. The sensor is configured to measure a transverse placement of the incoming web relative to the incoming web target location. The sensor is capable of transmitting an input signal to the controller when the transverse placement of the incoming web differs from the target location. The controller is configured to provide an output signal to the actuator based on the input signal. The actuator is coupled to the turnbar and is configured to receive the output signal from the controller. The actuator is configured to move the turnbar in response to the output signal such that the web maintains substantial alignment with the target location. 
     In a further embodiment, the present application includes a method for controlling the unwinding of a web wound on a core. The method includes providing a turnbar to receive the web unwound from the core, the turnbar having a target location. The turnbar is coupled to an actuator. The actuator includes an axis of movement that is substantially parallel to an axis of a portion of the web after the web contacts the turnbar. A sensor is provided to measure a transverse placement of the web relative to the target location. The sensor transmits a signal to the actuator based on measurements provided by the sensor when the transverse placement of the web differs from the target location. The actuator moves the turnbar along the axis of movement based on the signal received by the actuator such that the web is substantially aligned with the target location. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  representatively illustrates a perspective view of a regular roll of web material. 
         FIG. 1B  representatively illustrates a perspective view of a roll of level-wound web material. 
         FIG. 1C  representatively illustrates a perspective view of a roll of center-feed wound web material. 
         FIG. 2  representatively illustrates another perspective view of a roll of level-wound web material. 
         FIG. 3  representatively illustrates a perspective view of an exemplary apparatus of the present disclosure and process of utilizing the apparatus. 
         FIG. 4  representatively illustrates a top plan view of a web being received by the turnbar at an incoming web target location and thus leaving the turnbar at the outgoing web target location. 
         FIG. 5  representatively illustrates a top plan view of an incoming web target location and an outgoing web target location on a turnbar of the present disclosure. 
         FIG. 6  representatively illustrates a perspective view of a preferred embodiment of the apparatus of the present disclosure, the turnbar being removed for clarity. 
         FIG. 7  representatively illustrates another perspective view of the preferred embodiment of the apparatus of the present disclosure. 
         FIG. 8  representatively illustrates a top plan view of a web being received by the turnbar that is not in alignment with the incoming web target location and thus does not leave the turnbar at the outgoing web target location. 
     
    
    
     Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the disclosure. 
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The present disclosure relates to an apparatus  1  and method for controlling the unwinding of a web  2  from a roll. The web  2  material may initially be wound onto a core  3  in a variety of different ways to form a roll wherein the roll includes a roll length  5  and a roll diameter  6 . The roll length  5  as used herein refers to the length of the web  2  material along the length of the core  3  on which the web  2  material wound. It is possible that the length of the core  3  may be the same length as the roll length  5 . In some instances, the length of the core  3  may be longer than the roll length  5 ; that is, a portion of the core  3  may extend beyond where the web  2  material is wound onto the core  3 . The various roll winding configurations may change based on the end-use and/or shipping concerns. A regular roll  1   a  is illustrated in  FIG. 1A . The regular roll  1   a  is formed by winding the web  2  material around a core  3  by turning the web  2  material over on itself several times. The web  2  is removed from the outside of the roll  1   a . The web width  7  of a regular roll  1   a  is generally the same as the roll length  5 . A level-wound roll  1   b  is illustrated in  FIG. 1B . The level-wound roll  1   b  is formed by winding the web  2  material around a core  3  by traversing the web  2  material along the roll length  5  several times. The web  2  is removed from the outside of the roll  1   b . The web width  7  is smaller than the roll length  5 , and in most circumstances, substantially smaller than the roll length  5 . As shown in FIG.  1   c , a center-feed wound roll  1   c  is formed similarly to a level-wound roll  1   b  except that the core  3  is removed and the web  2  is removed, or fed, from a roll center  4 . The web width  7  is smaller than the roll length  5  in a center-feed roll  1   c  similar to a level-wound roll  1   b  as well. 
     Webs  2  unwound from level-wound rolls  1   b  must traverse the entire roll length  5  such that the web  2  comes off of the roll  1   b  at different points along the roll length  5 . The traversing motion along the roll length  5  of the level-wound roll  1   b  effectively creates a large amount of web  2  weave during the manufacturing process. For example, when the web  2  is being unwound from the ends of the level-wound roll  1   b , the web  2  is entering the manufacturing process at a more extreme angle α than when the web  2  is being unwound from the middle of the level-wound roll  1   b . The web  2  leaving the level-wound roll  1   b  at more extreme angles α can also lead the web  2  to flip or fold over on itself in the cross direction. Web  2  alignment issues may be exacerbated by other factors when the web  2  is unwound including high machine speeds and properties of the web  2  that may be non-symmetrical. For example, some webs  2  may have properties that vary between sides or surfaces of the web  2 . 
     Web  2  materials that have a tendency to either neck or curl, and/or fold upon itself in the cross direction of the web  2  while being unwound from the roll may also contribute to web  2  alignment and instability issues, such as, for example, materials that include some amount of stretch or lack of recovery. Several materials used in manufacturing processes, such as, for example, those used to produce absorbent articles, may include materials that can contribute to web  2  alignment issues. Other examples of materials that can contribute to web  2  alignment issues are multi-layered, or composite, materials. Such materials may exhibit properties on a surface that differ from an opposite surface. For example, a material that can be used as a liquid acquisition/distribution layer in an absorbent article can be a two-layered, nonwoven fibrous composite, wherein the two layers are bonded through hydroentanglement and one surface is smooth and the opposite surface includes projections. Other examples include, but are not limited to, a single-layered fibrous nonwoven material wherein one surface is coated and the opposite surface is uncoated, a single-layered fibrous nonwoven material wherein one surface is coated and the opposite surface is coated with a different coating than the other surface, or a single-layered film nonwoven material wherein one surface is coated and the opposite surface is uncoated. Web  2  materials exemplary of those contributing to web  2  alignment issues may include, but are not limited to, plastic films and/or nonwoven webs that may be used as components in absorbent articles such as, for example, outer cover materials, urine or fecal matter acquisition or distribution materials, waist elastics, and leg elastics. Woven materials may also have a tendency to neck or curl, and/or fold upon itself in the cross direction of the web  2  while being unwound from the roll. Absorbent article refers herein to an article that may be placed against or in proximity to the body (i.e., contiguous with the body) of the wearer to absorb and contain various liquid and solid waste discharged from the body. Non-limiting examples of absorbent articles include personal care absorbent articles such as diapers, diaper pants, training pants, swimwear, absorbent underpants, adult incontinence products including garments and insert pads, bed pads, feminine hygiene pads or liners, digital tampons, sweat absorbing pads, shoe pads, helmet liners, wipes, tissues, towels, napkins, and the like, as well as medical absorbent articles such as medical absorbent garments, bandages, masks, wound dressings, surgical bandages and sponges, underpads, and the like. 
     The present disclosure provides an apparatus  1  and a method to control web  2  alignment issues that may arise when unwinding a web  2  from a roll. With reference to  FIGS. 3-5 , in an embodiment, the web  2  is unwound from a level-wound roll  1   b  as illustrated in  FIG. 3  however, the apparatus  1  and method described herein can be utilized with other forms of rolls, such as those previously discussed. The apparatus  1  includes a turnbar  10 , a sensor  30  and an actuator  20  (not shown in  FIG. 3  for the purpose of clarity). The turnbar  10  receives an incoming web  12  that is the portion of the web  2  that is unwound from the core  3  and disposed between the core  3  and the turnbar  10 . An outgoing web  14  is the portion of the web  2  after engagement with the turnbar  10 . The incoming web  12  includes an incoming web axis  16  that can be substantially parallel to the longitudinal direction  40  and the outgoing web  14  includes an outgoing web axis  18  that can be substantially parallel to the lateral direction  42  as illustrated in  FIG. 4 . Turnbars  10  are used in the web  2  path to change the direction of the web  2  during the manufacturing process. Turnbars  10  can be placed at an angle α relative to the incoming web axis  16  that is parallel to the longitudinal direction  40 . Often times, the turnbar  10  is placed at a 45 degree angle α in order to turn the incoming web  12  such that the outgoing web axis  18  is approximately 90 degrees from, or substantially perpendicular to, the incoming web axis  16 . The exemplary embodiment and configuration of the turnbar  10  shown and discussed herein forms a 90 degree turn of the web  2  wherein the incoming web axis  16  is substantially perpendicular to the outgoing web axis  18 . However, the apparatus  1  and method can apply to turnbars  10  configured to provide other angles α between the incoming web axis  16  and the outgoing web axis  18 . It can be appreciated that the turnbar  10  may be placed at any angle α to provide a desirable turn in the web  2  path for the given manufacturing process, for example from 1 degree to 89 degrees, and more specifically from about 10 degrees to about 80 degrees. The turnbar  10  has a target location that includes an incoming web target location  51  and an outgoing web target location  52  as illustrated in  FIG. 4  and  FIG. 5 . The turnbar  10  receives the incoming web  12  at the target location  51  as illustrated in  FIG. 4 . The incoming web target location  51  of the turnbar  10  will in turn include an outgoing web target location  52  also illustrated in  FIG. 5 . The outgoing web target location  52  is the location on the turnbar  10  where the outgoing web  14  should engage the turnbar  10  if the incoming web  12  engages the turnbar  10  at the incoming web target location  51 . While the incoming web target location  51  and the outgoing web target location  52  are shown in  FIG. 4  and  FIG. 5  as zones that correspond to the web width  7 , the target location could be configured to be a point or a width that is less than, equal to, or several times greater than the web width  7 . The target location may be as small or as large as desired as long as it serves as a reference location with respect to the web  2 . The turnbar  10  may be made from materials that have low friction and to reduce drag of the web  2 , such as polished steel or a coating and/or the turnbar  10  may include air assistance, but is not limited to such configurations. 
     The apparatus  1  further includes an actuator  20 , as illustrated in  FIGS. 6 and 7 . The actuator  20  includes a drive mechanism  21  that is positioned internally of the actuator  20 . The drive mechanism  21  can provide movement to a component, such as for example, a carriage  26  that may be coupled to the actuator  20 . The drive mechanism  21  may include a motor and some means to communicate this movement to the carriage  26 . For example, a cut-away portion of a belt drive mechanism  21  is illustrated in  FIGS. 6 and 7  wherein a belt  23  is shown over a belt roller  27  (all components of the belt drive mechanism  21  are not shown for the purpose of clarity), where the belt  23  can be coupled to the carriage  26  via a carriage connector  28 , such that linear movement of the belt  23  can provide linear movement to the carriage  26 . 
     The carriage  26  may be moveably coupled to the actuator  20  as illustrated in  FIGS. 6 and 7 . The actuator may include a carriage guide  25  upon which the carriage  26  can move along, such as, for example through a sliding movement. A mounting plate  24  may also be coupled to the carriage  26 . A turnbar mount  22  may be coupled to the mounting plate  24  wherein the turnbar  10  can be coupled to the turnbar mount  22 . 
     The sensor  30  of apparatus  1  is in electrical communication with the actuator  20  and can be configured to measure transverse movement of, 1) the incoming web  12  relative to the incoming web target location  51 , or 2) the outgoing web  14  relative to the outgoing web target location  52 . For example, an incoming web target location difference  60  can be detected when there is a difference between where the incoming web  12  engages the turnbar  10  relative to the incoming web target location  51 . With respect to the sensor  30  detecting the incoming web target location difference  60 , the incoming web  12  includes an incoming web left edge  12   a  and an incoming web right edge  12   b  and the incoming web target location  51  includes an incoming web target location left edge  51   a  and an incoming web target location right edge  51   b . The sensor  30  can, for example, detect the incoming web target location difference  60  when the incoming web left edge  12   a  is not in alignment with the incoming web target location left edge  51   a , or when the incoming web right edge  12   b  is not in alignment with the incoming web target location right edge  51   b . In such a circumstance, the sensor  30  can be referred to as an edge sensor. The transverse movement of the incoming web  12  may be to the incoming target left side  51   a  or to the incoming target right side  51   b  as shown in  FIG. 8 . The transverse movement of the incoming web  12  is substantially parallel to the lateral direction  42  as illustrated in  FIGS. 4, 5 and 8 . 
     Alternatively, the sensor  30  can detect an outgoing web target location difference  62  wherein the outgoing web  14  includes an outgoing web bottom edge  14   a  and an outgoing web top edge  14   b  and the outgoing web target location  52  includes an outgoing web target location target bottom edge  52   a  and an outgoing web target location top edge  52   b . The outgoing web target location difference  62  can be detected when there is a difference between where the outgoing web  14  engages the turnbar  10  relative to the outgoing web target location  52  such that the transverse movement of the outgoing web  14  may above the outgoing web target location top side  52   b  or below the outgoing web target location bottom side  52   a  as also shown in  FIG. 8 . The transverse movement of the outgoing web  14  is substantially parallel to the longitudinal direction  40  as illustrated in  FIGS. 4, 5 and 8 . 
     Another type of sensor  30  may detect an incoming web centerline  12   c  relative to some reference, such as for example an incoming web target location centerline  51   c  wherein the incoming web centerline  12   c  and the incoming web target location centerline  51   c  are collinear with the incoming web axis  16 . The sensor  30  can detect the incoming web target location difference  60  when the incoming web centerline  12   c  is not in alignment with the incoming web target location centerline  51   c . Alternatively, the sensor  30  may detect an outgoing web centerline  14   c  relative to some reference, such as for example an outgoing web target location centerline  52   c  wherein the outgoing web centerline  14   c  and the outgoing web target location centerline  52   c  are collinear with the outgoing web axis  18 . The sensor  30  can detect the outgoing web target location difference  62  when the outgoing web centerline  14   c  is not in alignment with the outgoing web target location centerline  52   c . The transverse movement of the incoming web  12  in the lateral direction  42  directly affects the transverse movement of the outgoing web  14  in the longitudinal direction  40 , wherein the incoming web axis  16  is substantially parallel to the longitudinal direction  40  and the outgoing web axis  18  is substantially parallel to the lateral direction  42  as illustrated in  FIG. 4 ,  FIG. 5  and  FIG. 8 . 
     In one embodiment, the actuator  20  of apparatus  1  is an electronic device that can provide linear movement in an axis of movement  29  such that the axis of movement  29  is substantially parallel to the outgoing web axis  18  as illustrated in  FIG. 7 . The actuator  20  is configured to receive the signal from the sensor  30  wherein the turnbar  10  is moved to keep the incoming web  12  substantially in alignment with the incoming web target location  51 , and/or the outgoing web  14  substantially in alignment with the outgoing web target location  52 . The actuator  20  of apparatus  1  may include a rotary motion type actuator  20  that can be also be used for linear applications by transforming the rotary motion to linear motion with the use of, for example, screw, cam, rack, chain or belt mechanisms. Alternatively, some actuators  20  provide direct linear movement, such as, for example, piezoelectric, linear motor, or moving coil actuators. An exemplary actuator  20  of apparatus  1  includes a belt driven actuator available from Tolomatic, Hamel, Minn., USA, model B3W15/M3W15. It should be understood that the actuator  20  could provide any type of movement, such as for example, rotary; although, linear movement is discussed as one way of having the actuator  20  respond to the sensor  30  signal. Additionally, the actuator  20  can move in more than one linear direction. For example, it is contemplated that the actuator  20  can provide motion in a direction parallel to the outgoing web axis  18  and/or the incoming web axis  16 . 
     Exemplary actuators  20  that may be used when unwinding level-wound rolls  1   b  should be able to provide suitable stroke lengths that are related to the roll length  5 . In embodiments configured for use with level-wound rolls  1   b,  1) the actuator  20  should be able to at least traverse the entire roll lengths as the incoming web  12  engages the turnbar  10  and 2) the actuator  20  may also provide stroke lengths greater than the roll length  5  to allow for detection of the incoming web target location difference  60  or the outgoing web target location difference  62  that may occur at each end of the roll length  5  for the level-wound roll  1   b . For example, the stroke length of actuators  20  used in the manufacturing process of absorbent articles may include lengths of from about 120 mm to about 1500 mm and more specifically from about 600 mm to about 900 mm. While stroke lengths in a typical application for manufacturing absorbent articles have been discussed, it should be understood that stroke lengths outside of this range may exist for other applications. Exemplary actuators  20  will also be able to move at speeds that accommodate the speed of the incoming web  12  relative to the roll diameter  6 ; that is, the speed of the actuator  20  will be less when the level-wound roll  1   b  is at full roll diameter  6  and the actuator  20  speed increases as the incoming web  12  is unwound from the roll  1   b  and approaches the core  3 . 
     The sensor  30  and the actuator  20  can be in electrical communication with one another by being in electrical communication with software that is housed in a controller  70 . The controller  70  can be a programmable logic controller (PLC) and/or may be housed in a computer or central processing unit (CPU). The actuator  20  is configured to move the turnbar  10  based on output signals received from the controller  70 . The signal sent from the controller  70  to the actuator  20  is defined by feedback control that is based on input information received by the controller  70  from the sensor  30  via input signals from the sensor  30 . The feedback control may calculate an error value, or the difference between a measured variable and a desired setpoint, such as, for example, the incoming web target location difference  60  or the outgoing web target location difference  62 . The sensor  30  sends the error value to the controller  70  wherein the controller  70  attempts to minimize the error value by sending an appropriate output signal to the actuator  20  to actuate movement of the actuator  20 , and in turn, the turnbar  10 . Some examples of feedback control include, but are not limited to, proportional, proportional-integral (PI), or proportional-integral-derivative (PID). 
     In an embodiment, as illustrated in  FIG. 7 , the sensor  30  may detect the incoming web target location difference  60 . The sensor  30  transmits a signal to the controller  70  and if necessary, the controller  70  provides a signal to the actuator  20  to change the position of the turnbar  10 . The actuator  20  can cause the turnbar  10  to move by enacting the drive mechanism  21  to slide the carriage  26  along the carriage guide  25  in the direction of the axis of movement  29 . The movement of the carriage  26  in turn moves the mounting plate  24  upon which the turnbar  10  is attached via the turnbar mount  22 . 
     In an embodiment, the sensor  30  can be located along the path of the web  2  at a location 1) prior to the turnbar  10  to sense the incoming web  12  such as at the incoming web sensor location  32 , or 2) after the turnbar  10  to sense the outgoing web  14  such as at the outgoing web sensor location  34  as illustrated in  FIG. 3 . In another embodiment, the sensor  30  can be coupled to the actuator  20  to sense the outgoing web  14 . In yet another embodiment, that is preferred, the sensor  30  is coupled to the actuator  20  to sense the incoming web  12  as illustrated in  FIG. 6  and  FIG. 7 . The apparatus  1  configuration of this embodiment provides a series of benefits including, 1) early detection of the incoming web target location difference  60 , 2) quicker correction of web  2  alignment or instability issues based on the incoming web target location difference  60  before web  2  alignment issues are translated further downstream, 3) reduced likelihood of the web  2  material folding on itself or twisting, 4) reduced machine downtime, 5) reduced number of processing steps, such as for example, eliminating the need for steps to twist the web  2 , 6) reduced machine stops, 7) increased product quality, and 8) reduced waste. 
     In an embodiment, a method for controlling the unwinding of a web  2  wound on a core  3  includes providing a turnbar  10  to receive an incoming web  12  at an incoming web target location  51 . The turnbar  10  can be coupled to an actuator  20  wherein the actuator  20  includes an axis of movement  29  that is substantially parallel to the outgoing web axis  18  as shown in  FIGS. 6 and 7 . A sensor  30  is provided to measure the incoming web location difference  60  or the outgoing web location difference  62 . The sensor  30  transmits a signal to the actuator  20  through the use of a controller  70  when the incoming web location difference  60  or the outgoing web location difference  62  differs from the incoming web target location  51  or the outgoing web target location  52 , respectively. The actuator  20  moves the turnbar  10  along the axis of movement  29  based on the signal received from the controller  70  based on the sensor  30  such that the incoming web  12  is substantially aligned with the incoming web target location  51 . The sensor  30  can be coupled to the actuator  20  as shown in  FIGS. 6 and 7 . A benefit of such a configuration allows the sensor  30  to move transversely with the turnbar  10 , and thus, the incoming web  12 . In such a configuration, the sensor  30  may not need to be as wide as in a configuration where the sensor  30  is not coupled to the actuator  20 . For example, in a configuration where the sensor  30  is not coupled to the actuator  20 , as shown in  FIG. 3 , the sensor  30  may have to be very wide, such as for example, greater than the roll length  5 , in order to detect the incoming web target location difference  60  or the outgoing web target location difference  62  which may cause greater transverse movement of the turnbar  10  for correction of the web  2  alignment. 
     When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Many modifications and variations of the present disclosure can be made without departing from the spirit and scope thereof. Therefore, the exemplary embodiments described above should not be used to limit the scope of the invention