Abstract:
Apparatus and method for aligning webs, such as photographic film or paper, where the trailing edge of an expiring web is spliced to the lead edge of a fresh web. A supporting means having the fresh web thereon in a fixed position is caused to move by sensor means transmitting a signal corresponding to precise positioning of the expiring relative to the fixed position of the fresh web. According to the invention, a programmable controller is used to analyze the signals received from the sensors and directs the movements of the supporting means where the webs are ultimately moved into abutting or overlapping contact and then spliced.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a divisional of Ser. No. 08/575,943, filed Dec. 20, 1995, now U.S. Pat. No. 5,849,123, issued Dec. 15, 1998, by Brian S. Rice, titled, “APPARATUS AND METHOD FOR ALIGNING WEBS”. 
    
    
     TECHNICAL FIELD 
     The invention relates generally to an apparatus and method for aligning flexible material, such as webs. More particularly, the invention concerns an apparatus and method for aligning while conveying a trailing end of a first expiring web with a leading end of a second, fresh web so that a spliced web is substantially free of edge weave and the like when conveyed. 
     BACKGROUND OF THE INVENTION 
     Apparatus for splicing flexible material, such as web, are well known in the art. In a typical apparatus and method for splicing the ends of webs, the web ends are cut while generally in an overlapping or abutting relations. One end of one of the webs is separated while being conveyed so that the two cut ends to be joined can be maneuvered into abutting or overlapping relations with one another. Splice tape is then applied to the abutting or overlapping ends to form the spliced web. 
     A problem with existing web splicing operations is that in most continuous web processing machines, the conveyance of webs prior to splicing oftentimes results in misalignment between the web ends. Poor geometric alignment, i.e,. skew  10  and offset (illustrated in FIG.  1 ), of the spliced webs  102 ,  104  will invariably produce coating edge registration problems. Illustrated in FIGS. 2 and 3, respectively, are the effects of a misaligned spliced webs  102 ,  104  and an aligned spliced web on coating registration. One of the most common results of weave is coating registration problems, as shown in FIG.  2 . Experience has shown that weave, occurring generally along lateral edge portions of the joined webs, is caused by the lateral motion of a moving web perpendicular to its direction of motion and in the plane defined by the width of the web. Thus, it is generally established that lateral edge weave is induced by splice misalignment (offset and skew). While prior art developments have not addressed the problem of web alignment, there are exists some developments that teach web splicing generally, and in particular, disclose various means of cutting the new and expired webs and then joining of the two webs with, for instance. tape, glue, heat seal for both butt and lap splices. As examples, U.S. Pat. Nos. 4,892,611 and 4,878,986 each discloses limiting operator intervention in the cutting and joining phase of the splice operation. Neither of these references evinces concern or appreciation for geometric alignment of the new and expired web as a means for resolving the weaving of one web relative to the other prior to splicing. 
     Therefore, a need persists for an apparatus and method for aligning adjoining ends of webs in (high speed) conveying operations so as to eliminate the possibility of misaligned web segments prior to splicing. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the invention to provide an apparatus for aligning webs prior to splicing so as to virtually eliminate splice induced weave. 
     It is another object of the invention to provide a spliced web wherein the lateral alignment can be specified in terms of offset, lateral displacement of the expired and new web edges and skew, and the local angle between the two web edges (edge parallel to the machine direction of travel). 
     It is yet another object of the invention, to provide an apparatus capable of geometrically aligning the trailing edge of an expiring web and the leading edge of a new web in continuously operating web converting machines prior to the splice operation. 
     It is an advantageous effect of the present invention that the apparatus and method minimize splice induced weave and eliminates waste associated therewith. 
     It is a feature of the invention that lateral edges of an expiring web and fresh web are aligned by position metrics detected by sensors which communicates with a controller that processes the signals and transmits a signal to a movable support means bearing the fresh web. The movements of the support means registrably aligns the fresh web with the expiring web. 
     To accomplish these and other objects and advantages of the invention, there is provided, in one aspect of the invention, an apparatus for moving a first, fresh web into registered alignment with a second, expiring web. According to this embodiment, means is provided for movably supporting the fresh web in a prearranged fixed position. A first sensor means in proximity to the supporting means and arranged to detect the fresh web is employed to detect both the rotational and lateral metrics of the fresh web in its fixed position. Similarly, a second sensor means in proximity to the supporting means is used to detect the plurality of positions of the expiring web as it is being positioned in proximity with the supporting means. Each of the sensor means produces signals that are received and processed by a controller means having a microprocessor which compares the positions of the expiring and fresh webs and transmits a third signal corresponding to precisely sensed positions of the expiring web relative to the fixed position of the fresh web. Thus, the third signal provides the supporting means with movements that registrably aligns the fresh web with the expiring web. 
     In another aspect of the invention, a method for moving a first, fresh web into registered alignment with a second, expiring web, comprises the step of movably supporting the fresh web in a fixed position. The movably supporting means is capable of movements in response to a signal corresponding to the sensed positions of the expiring web relative to the fixed position of the fresh web. Sensors are used for generating signals corresponding to the positions of the fresh web and the expiring web, as described above. A controller means receives and processes these signals. Thereafter, the controller means transmits a third new signal that provides the supporting means with movements that registrably aligns the fresh web with the expiring web. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiments of the invention, as illustrated in the accompanying drawings: 
     FIG. 1 is a top plane view of misaligned web ends prior to splicing; 
     FIG. 2 is top plane view of a misaligned spliced web; 
     FIG. 3 is a top plane view of an aligned spliced web; 
     FIG. 4 is a side elevational view of the web splicing apparatus of the invention; 
     FIG. 5 is a side elevational view of the web splicing apparatus of the invention illustrating slack in the fresh web; 
     FIG. 6 is a top plane view of the fresh and expiring webs in the proximity of the vacuum table; 
     FIG. 7 is a side elevational view of the apparatus showing the control means of the invention; 
     FIG. 8 is an alternative embodiment of the apparatus of the invention; 
     FIG. 9 is a side elevational view of the apparatus prior to a splice sequence; and, 
     FIGS. 10-13 are side elevational views of the apparatus during a splice sequence. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings, and particularly to FIGS. 4,  5  and  6 , the apparatus  100  of the invention is illustrated. Broadly defined, the apparatus, or web splicing machine,  100 , for positioning a first, fresh web  102  into registered alignment with a second, expiring web  104 . According to this embodiment, means  106  is provided for movably supporting the fresh web  102  in a prearranged fixed position, as described in details below. 
     According to FIGS. 4 &amp; 5, supporting means, preferably a partially ported vacuum table,  106 , is employed for holding the fresh web  102  in its fixed position prior to splicing to an expiring web  104 . Movements of the supporting means, or vacuum table,  106 , while supporting the fresh web  102  correspond to precisely sensed positions of the expiring web  104  relative to the fixed position of the fresh web  102 , as further described herein. 
     FIGS. 4,  5 , &amp;  6 , moreover depict a pair of first sensor means  108  positioned in proximity to the supporting means, or vacuum table,  106 , and arranged to detect the fixed position of the fresh web  102 . Preferably a first sensor means  108  is arranged on either end portion of the vacuum table  106  so as to precisely sense a lateral edge  107  of the fresh web  102  in its fixed position. Thus, the rotational and translational metrics of this fixed position are detected or sensed by both first sensor means  108 . Referring to FIG. 5, the stationary fresh web  102  is illustrated under zero tension on the machine  100  traveling along a path over idler roller  110 , first sensor means  108  and then attached to vacuum table  106  where it will be spliced to the expiring web  104 . Placement of the fresh web  102  in a prearranged fixed position on the movable vacuum table  106  is accomplished manually or by a machine process step. Positioning of the expiring web  104  in proximity of the vacuum table  106  where it is to be spliced to the fresh web  102  is achieved by conveying it from expiring web roll  144 . 
     Referring again to FIGS. 4,  5 , &amp;  6  , similarly, a pair of second sensor means  114  positioned in proximity to the supporting means  106  is used to detect the rotational and translational metrics corresponding to the plurality of positions of the expiring web  104  as it is positioning in proximity to the support means  106 . Preferably, second sensor means  114  are arranged on opposite end portions of the vacuum table  106  for precisely sensing the lateral edge  116  of the expiring web  104 . Each of the first and second sensor means  108 ,  114  produces signals that are received and processed by a programmable controller means  118  having a microprocessor which compares the positions of the expiring web  104  to the fixed position of the fresh webs  102 , and then transmits a third signal corresponding to precisely sensed positions of the expiring web  104  relative to the fixed position of the fresh web  102 . More importantly, this third signal provides the supporting means  106  with movements that registerably aligns the fresh web  102  to the expiring web  104 . In this embodiment of the invention, it is the corresponding lateral edges  116 ,  107  of the expiring web  104  and fresh web  102 , respectively, that are aligned as a result of the movements of the support means  106  bearing the fresh web  102 . 
     It is important to the invention that fresh web  102  is under zero tension (producing what is commonly referred to as slack web) during the alignment process, as illustrated in FIG.  5 . Slack web is important because it provides the necessary degrees of freedom (including translational and rotational) of the vacuum table  106  as it tracks precisely the positioning of the expiring web  104 . Moreover, slack web prevents excessive forces from developing in the fresh web  102  due to bending stiffness of a tensioned web. Further, without slack web, the possibility of creasing the fresh web  102  and/or causing the fresh web  102  to move relative to the vacuum table  106  would exist. Such a development would clearly exacerbate the web aligning process as defined by the present invention. 
     According to FIG. 6, a top plan view vacuum table  106  of machine  100  showing second sensor means  114  for detecting the lateral edge  116  of the expiring web  104 , first sensor means  108  for detecting the fixed position of the fresh web  102  on the vacuum table  106 , and the fresh and expiring webs  102 ,  104  in proximity to the vacuum table  106 . Vacuum table  106  provides a platform for splicing. To facilitate alignment, an edge indicator reference (T—T)  124  is provided on the vacuum table  106  (e.g. a mechanical feature). Prior to the fresh web  102  being affixed to the vacuum table  106 , the vacuum table  106  is in its initial starting position with respect to translation axis  122  and rotation axis  123  axis. Thus, edge indicator reference (T—T)  124  is coincident with machine edge reference (R—R)  126 . The edge indicator reference (T—T)  124  is provided to aid the operator in placing the fresh web  102  as close as possible to machine edge reference (R—R)  126  prior to the vacuum being applied to the vacuum table  106  for holding the fresh web  102 . Further according to FIG. 6, rotation and translation of the vacuum table  106  provides movements for maneuvering the lateral edge  107  of fresh web  102  into alignment with the lateral edge  116  of the expiring web  104 , as sensed by their respective sensor means  108 . Alignment of the fresh web  102  with the expiring web  106  takes place just after the expiring web  106  reaches zero speed. Alternatively, one of ordinary skill in the art will appreciate that the alignment can occur just prior to the expiring web  106  reaching zero speed. 
     While the invention has thus far been generally described with reference to web edge alignment, extension of the inventive concept to centerline web alignment is within the contemplation of the invention. 
     Referring next to FIGS. 7 &amp; 8, the arrangement of first and second sensor means  108 ,  114  are used to provide datum useful in determining how much the vacuum table  106  must move along its translation axis  122  and rotation axis  123  in order to bring the fresh web  102  into alignment with the expiring web  104 . In FIG. 7, a pair of second sensor means  114  arranged for sensing the lateral edge  116  of expiring web  104 , measures expiring web  104  position error (E 1 ). An opposed second sensor means  114  measures position error E 2  of expiring web  104 . Similarly, a pair of first sensor means  108 , as indicated above, detects the lateral edge  107  of fresh web  102 . One of the two first sensors means  108  provides position error E 3  while the opposed first sensor means  108  provides position error E 4 . Further, both webs have an offset error as shown in FIG.  6 . Expiring web  104  has an offset error defined by (O l ) and the fresh web  102  has an offset error defined by (O 2 ). Each of these offset errors are calculated along an axis  130  passing through the cutting means, or knife,  132  [( 36 )]. Moreover, each of the webs are also subject to skew as described above. The skew error for expiring web  104  is defined by (A 1 ); and, the skew error for the fresh web  102  is defined by A 2 . Furthermore, I have found that machine  100  is more efficient if the first sensor means  108  is spaced distances (L 3  and L 4 ) from axis  130  of the cutting means  132 ; and the second sensor  114  is spaced a distances (L 1  and L 2 ) from axis  130  of the cutting means  132 . According to my convention, displacements above axis R—R  126  are considered positive, and those below are negative (see FIG.  6 ). Thus (E 1 ), (E 2 ) and (O 1 ) are positive and (E 3 ), (E 4) and (O   2 ) are negative. Furthermore, angles sloping downward from left to right are considered positive. Thus, (A 2 ) is positive and (A 1 ) is negative. 
     One skilled in the art, of course, will appreciate that first sensor means  108 , as described herein, while preferred, are not necessary to detect the position of the fresh web  102  if the desired alignment accuracies can be accomplished with mechanical datums on the vacuum table  106  (e.g. a mechanical feature on the vacuum table  106  referred to as machine edge reference T—T  124 . 
     Measuring the lateral edge  107  of fresh web  102  in offset and skew with respect to axis T—T  124  with first sensors means  108  and translating and rotating vacuum table  106  to bring the fresh web  102  into alignment with machine axis R—R  126  is also a possible method of alignment. Here the position of the expiring web  104  is ignored, thus there is a loss in splice alignment quality. 
     As indicated above, a programmable controller means  118  is used to analyze signals corresponding to positions of the expiring and fixed fresh webs  104 ,  102  (best seen in FIG.  7 ). The following equations can be programmed into a microprocessor for determining the movements of the support means or vacuum table  106 , as described in details above:          O   1     =         E   1          (     1   -     L1     L2   +   L1         )       +     E2L1     L2   +   L1                   O   2     =         E   3          (     1   -     L3     L4   +   L3         )       +     E4L3     L4   +   L3                   A   1     =       TAN     -   1            (       E1   -   E2       L1   +   L2       )                 A   2     =       TAN     -   1            (       E3   -   E4       L3   +   L4       )               TRANS   =       O   1     -     O   2               ROT   =       A   1     -     A   2                              
     Thus, as shown more clearly in FIGS. 7, the controller means  118  calculates TRANS and ROT (as shown above) and sends the appropriate signals to first and second actuators  134 ,  136 . Actuators  134 ,  136  govern the movements of the supporting means  106  to bring the fresh web  102  into alignment with the expiring web  104 . Note the second order terms coupling vacuum table translation to vacuum table rotation are ignored in the alignment calculation. 
     Referring again to FIG. 6, if the lateral edge  116  of the expiring web  104  is coincident with the machine edge reference R—R  126 , errors E 1  and E 2  will be zero for the second sensor means  114 . On the other hand, if the lateral edge  107  of fresh web  102  is coincident with the machine edge reference (T—T)  124 , errors E 3  and E 4  will be zero for first sensor means  108 . 
     Accordingly, the preferred embodiment of our invention presents a continuously operating web converting machine which makes stationary web splices, as illustrated, for instance in FIGS. 4 &amp; 5. Although not required, we prefer employing two mandrels for accommodating each of the stock rolls of fresh and expiring webs, a turret for selectively feeding a stockroll to the machine, a zero speed splicer, sensors to locate the fresh and expiring web and a method of web storage (accumulator), each being described in more details below. 
     Alternatively, machine  100  may include means for cutting  132 , e.g. a knife or blade, fresh and expiring webs  102 ,  104  so that just-cut ends of the webs can form either abutting web ends or overlapping web ends. In this embodiment, a just-cut end of the expiring web  104  is positioned into proximity with the just-cut end leading end of the fresh web  102  to form abutting or overlapping aligned web ends. 
     Referring again to FIGS. 4 &amp; 5, although not required, an unwind turret  142  supports expiring web roll  144  from which is conveyed the expiring web  104 ; and fresh web roll  146  from which is conveyed fresh web  102 . The expiring web  104  is conveyed over idler rollers  112  and through the pair of second sensor means  114 . Splice material, preferably a tape,  150  is attached to tape dispenser head  152  for transferring to the abutting or overlapping web ends. 
     OPERATIONS 
     FIG. 8 illustrates the machine  100  in operation prior to the splice sequence. The expiring roll  144  starts its deceleration and the accumulator starts to close allowing the rest of the machine  100  to remain at line speed. Expiring web  104  at this point reaches zero speed. The pair of second sensors means  114  and measure translational and angular positions of the expiring web  104  and then sends this information to the controller means  118 . Further the pair of first sensor means  108  measure translational and rotational positions of the fresh web  102  and send this information to the controller means  118 . The controller means  118  calculates TRANS and ROT as shown in FIG.  7 . Controller means  118  then transmits the appropriate signal to first actuator  134  to translate a distance TRANS calculated as shown above. First actuator  134  translates first frame  148  on first and second slides  156 ,  158  Second frame  160  supporting the vacuum table  106  moves with first frame  148  and the vacuum table  106  moves with second frame  160 . Thus, the vacuum table  106  translates as a result of the movements of first frame  148 . Controller means  118  also transmits a signal to second actuator  136  so as to cause second frame  160  to rotate about central axis (S—S)  123  passing through a centerline of first and second frames  148 ,  160 . Second frame  160  rotates by an angle ROT, calculated as shown above. Moreover, second actuator  136  causes second frame  160  to rotate about pivot  164  or central axis  123 ; and, the vacuum table  106  moves with second frame  160 . Thus, the vacuum table  106  rotates as a result of the rotation of second frame  160 . These movements brings the fresh web  102  into alignment with the expiring web  104 . 
     Further, according to FIG. 8, a third frame  166  arranged below the first and second frames  148 ,  160  is depicted in a splice ready position. Third actuator  168  is used to lift third frame  166  on a plurality of similar guide rails  170  preferably four, into splice ready position. The expiring web  104 , at this point, is being conveyed into proximity with the vacuum table  106 . 
     In FIG. 9, the start of the splicing operation is illustrated. Clamps  172 ,  174  secure the fresh web  102  and the expiring web  104  to the vacuum table  106 . A cutting means, or knife  132 , [( 36 )] supported by the supporting means  106  transverses across the web widths cutting both the expiring and fresh webs  102 ,  104 . 
     FIG. 10 depicts the steps needed to splice the fresh web  102  and expiring web  104  together. Clamp  174  retracts allowing the expiring web roll  144  to rewind pulling the unwanted portion of the expiring web  104  out of the way. Next tape head  152  applies the tape  150  to the just cut-ends of the expiring web  104  and the fresh web  102 , thus producing the spliced web. 
     FIG. 11 illustrates the tape head  152  and clamp  172  retracting. Vacuum supplied to vacuum table  106  is turned off and the fresh web roll  146  rewinds removing the slack in the fresh web  102 . 
     In FIG. 12, the start of web conveyance after the splice operation is illustrated. The fresh web roll  146  accelerates up to a speed greater than line speed allowing the accumulator (not shown) to fill with fresh web  102 . 
     FIG. 13 shows the machine  100  sequence needed to get ready for the next splice operation. Unwind turret  142  rotates  180  degrees. Third actuator  168  retracts third frame  166  on guide rails  170  into the splice preparation position. The operators remove the piece of fresh web scrap  176  adds tape  150  to tape head  152  and replaces expiring web roll  144 , with a fresh roll, allowing the splice cycle to be repeated again. 
     A skilled artisan will appreciate that the fresh and expiring web materials  102 ,  104  may be paper, plastic films and the like. This invention is important in continuous operating converting machine where the lateral position of the running web is important for registration of something being applied to (e.g. photographic emulsion) the running web. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Parts List: 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Slew 
                  10 
               
               
                   
                 Offset 
                  12 
               
               
                   
                 Machine 
                 100 
               
               
                   
                 Fresh web 
                 102 
               
               
                   
                 Expiring web 
                 104 
               
               
                   
                 Vacuum table 
                 106 
               
               
                   
                 Fresh web lateral edge 
                 107 
               
               
                   
                 First sensor means 
                 108 
               
               
                   
                 Fresh web idle roller 
                 110 
               
               
                   
                 Expiring web idle roller 
                 112 
               
               
                   
                 Second sensor means 
                 114 
               
               
                   
                 Expiring web lateral edge 
                 116 
               
               
                   
                 Controller means 
                 118 
               
               
                   
                 Translation axis 
                 122 
               
               
                   
                 Rotation axis 
                 123 
               
               
                   
                 Machine edge indicator 
                 124 
               
               
                   
                 Machine edge reference 
                 126 
               
               
                   
                 Cutting means axis 
                 130 
               
               
                   
                 Cutting means 
                 132 
               
               
                   
                 First actuator 
                 134 
               
               
                   
                 Second actuator 
                 136 
               
               
                   
                 Unwind turret 
                 142 
               
               
                   
                 Expiring web roll 
                 144 
               
               
                   
                 Fresh web roll 
                 146 
               
               
                   
                 First frame 
                 148 
               
               
                   
                 Splicing tape 
                 150 
               
               
                   
                 Tape dispenser head 
                 152 
               
               
                   
                 First &amp; Second Slides 
                 156, 158 
               
               
                   
                 Second frame 
                 160 
               
               
                   
                 Pivot 
                 164 
               
               
                   
                 Third frame 
                 166 
               
               
                   
                 Third actuator 
                 168 
               
               
                   
                 Guide rails 
                 170 
               
               
                   
                 Clamps 
                 172, 174 
               
               
                   
                 Fresh web scrap 
                 176 
               
               
                   
                   
               
             
          
         
       
     
     The invention has therefore been described with reference to certain embodiments thereof, but it will be understood that variations and modifications can be effected within the scope of the invention.