Abstract:
A cleaner assembly for cleaning a roller comprising a tape unwinder and winder for holding and dispensing adhesive tape which may be a continuous strip or may comprises discrete sheets of adhesive tape wound on top of each other. The winder and unwinder are connected to a drive by a timing belt. Thus a length of tape may be wound back and forth on a roller surface by alternating the rotation of the drive. The tape is passed around a backing roller to press the tape against a roller to be cleaned. In a second embodiment, the tape roll comprises a plurality of sheets of tape wound on top of each other. To remove a spent outer sheet, the outer sheet carrying the transferred particles is transferred to a continuous tape roll, exposing a fresh sheet on the sheeted tape roll which is then ready for renewed cleaning service.

Description:
[0001]     The present application draws priority from a pending U.S. Provisional Patent Application, Ser. No. 60/687,675, filed Jun.  6 ,  2005 . 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to method and apparatus for cleaning particles from a substrate; more particularly, to method and apparatus for cleaning particles from the surface of a process roller; and most particularly, to method and apparatus for cleaning particles from a roller surface by contact with an adhesive-covered tape which may be rewound for repeated use.  
       BACKGROUND OF THE INVENTION  
       [0003]     Methods and apparatus for cleaning particles from sheets and rollers by impingement of an adhesive-covered tape are well known. See, for example, U.S. Pat. Nos. 4,009,047 and 6,196,128.  
         [0004]     Adhesive-covered tape (referred to herein for simplicity as “adhesive tape) as used in the prior art can be an expensive medium for removing particles from a substrate, as the adhesive capabilities of the tape typically are far from exhausted in prior art applications. In addition, cleaning of relatively wide rollers by tape requires either an equivalently wide adhesive tape, which is very costly, or the progression of a narrower tape element along the surface to be cleaned.  
         [0005]     Further, the operation of prior art systems for using and renewing adhesive tape cleaners is highly labor-intensive, requiring that an operator be present to remove the length of spent tape and establish a fresh tape adhesive surface on the surface to be cleaned. See, for example, U.S. Pat. No. 6,196,128 B1.  
         [0006]     What is needed in the art is a method and apparatus for increasing the utility of adhesive tape for cleaning by reusing a tape element in a controlled, predictable, and automated way.  
         [0007]     What is further needed is an automated system for removing from a work zone a length of spent tape and establishing a fresh length of tape in the work zone.  
         [0008]     It is a principal object of the present invention to improve the use of adhesive tape as a substrate cleaning medium.  
       SUMMARY OF THE INVENTION  
       [0009]     Briefly described, a cleaner assembly for cleaning a roller comprises a tape unwinder for holding and dispensing adhesive tape. The adhesive tape may be a continuous strip or may comprises discrete sheets of adhesive tape wound on top of each other. In a first embodiment of a cleaner assembly in accordance with the invention, the tape roll is held in place by a spring-loaded gudgeon and by a drive having a one-way clutch that free-wheels in the tape forward direction but engages in the reverse direction. A tape winder is similarly equipped except that it winds in the forward direction and free-wheels in the reverse direction. The two drives are connected by a timing belt that also includes a motorized drive pulley. Thus a length of tape may be wound back and forth between the unwinder and the winder by alternating the rotation of the drive. Preferably, the tape is wound with its adhesive side out and may be passed around a backing roller (although not necessarily) for pressing the tape against a substrate to be cleaned. Pressure of the backing roller may be varied. A tach sensor at the backing roller tracks the length of tape passed in either direction. The cleaning head may be mounted on a rail for axial movement such that a substrate, such as a roller longer than the width of the tape, may be cleaned by moving the head in discrete stages along the roller.  
         [0010]     In a second embodiment, the tape roll comprises a plurality of discrete lengths of tape, herein referred to as “sheets”, wound on top of each other. Such a tape roll is referred to herein as a “sheeted tape roll”. The outer sheet has an end exposed, and the tape roll is rotated against the substrate to be cleaned in a direction such that the exposed end is trailing. To remove the outer sheet after it is spent, the tape roll is impinged against a continuous tape roll such that the outer sheet adhering the transferred particulates is transferred to the continuous tape roll, exposing a fresh sheet on the sheeted tape roll which is then ready for renewed cleaning service. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0012]      FIG. 1  is a schematic elevational view of a prior art system for using adhesive tape to clean a contact cleaning roller, as disclosed in U.S. Pat. No. 6,196,128 B1;  
         [0013]      FIG. 2  is a schematic cross-sectional view of a prior art sheeted tape roll as disclosed in U.S. Patent Application Publication No. US 2006/0057322 A1;  
         [0014]      FIG. 3  is a schematic cross-sectional view of a prior art system for employing the sheeted tape roll shown in  FIG. 2  for cleaning a contact cleaning roller as disclosed in U.S. Patent Application Publication No. US 2006/0057322 A1;  
         [0015]      FIG. 4  is an elevational end view of a first embodiment of a tape cleaning system in accordance with the invention;  
         [0016]      FIG. 4   a  is a detailed end view of the first embodiment shown in  FIG. 4 , showing typical operation of the system in accordance with the invention;  
         [0017]      FIG. 5  is an elevational side view of the tape cleaning system shown in  FIG. 4 ;  
         [0018]      FIG. 6  is an elevational end view showing an alternative backing roller for a tape cleaning system in accordance with the invention;  
         [0019]      FIG. 7  is an elevational side view of a second embodiment of a tape cleaning system in accordance with the invention;  
         [0020]      FIG. 8  is an end view of a third embodiment of a substrate cleaning system in accordance with the invention, showing the system in a first operating position;  
         [0021]      FIG. 9  is a view of the third embodiment shown in  FIG. 8 , showing the system in a second operating position;  
         [0022]      FIG. 10  is a schematic drawing of a control and alarm module for the system shown in  FIG. 4 ;  
         [0023]      FIG. 11  is an elevational end view of a fourth embodiment of a substrate cleaning system in accordance with the invention;  
         [0024]      FIG. 12  is an elevational end view of a fifth embodiment of a substrate cleaning system in accordance with the invention; and  
         [0025]      FIGS. 13 through 15  show three stages in renewal of a sheeted tape roll in accordance with the invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]     In broadest terms, the present invention is directed to apparatus and methods for bringing an adhesive tape surface into contact a plurality of times with a substrate to be cleaned. The prior art, as exemplified in U.S. Pat. Nos. 4,009,047 and 6,196,128, and U.S. Patent Application Publication No. U.S. 2006/0057322 A1, does not suggest or disclose to use an adhesive tape surface for more than one pass in contact with a substrate to be cleaned, such as a process roller or CCR. Such repeated usage in accordance with the present invention can greatly reduce the cost of operating roller cleaning systems wherein a CCR is cleaned by being brought into contact repeatedly with a length or circumference of adhesive tape.  
         [0027]     Referring to  FIG. 1 , a prior art system  10  is shown for cleaning the surface of a process roller  12 , such as a contact cleaning roller (CCR). System  10  is substantially as disclosed in U.S. Pat. No. 6,196,128 B1, the relevant disclosure of which is incorporated herein by reference. CCR  12  is in nipped contact with a web substrate  14  wrapped around a backing roller  16  and moving in a direction  18  such that CCR  12  rotates clockwise  20  as shown. By engaging in rolling contact with web substrate  14 , CCR  12  removes particulate contamination from the surface of web substrate  14  and transfers such contamination onto the surface of CCR  12  in known fashion. CCR  12  is also known in the art as a “particle transfer” roller, the surface of which typically is formed of a triboelectric material such as polyurethane or silicone rubber which attracts particles with a greater force than the surface of web substrate  14 .  
         [0028]     CCR  12 , or any other type of process roller, must be cleaned of accumulated particulate debris from time to time, to maintain a healthy process. In the case of a CCR, the particle removing effectiveness of the roller tends to diminish as the roller surface accumulates particles. Prior art system  10  renews the surface of CCR  12  by removing accumulated particles therefrom.  
         [0029]     System  12  comprises a secondary CCR  22  may be similar to the surface of primary CCR  12 , in that it may be formed of a resilient polymer having a high surface energy such as polyurethane, silicone rubber, butyl rubber, neoprene, or the like, or it may be formed of a tacky polymer such as a tape adhesive; for example, CCR  22  may comprise a multiple-convolution roll of adhesive tape wound on a core with the adhesive side facing outwards. A suitable tape, for example, is “Scotch Brand Tape No. 850” available from 3M Corporation, St. Paul, Minn., or its equivalent. Whatever material is selected for the surface of secondary CCR  22 , it is important that the surface tack be substantially greater than the surface tack of primary CCR  12  to assure transfer of particles to CCR  22 . Prior art system  10  further comprises mounting means  24  for supporting CCR  22 . Mounting means  24  is slidably disposed on a vertical guide  26  for variable vertical actuation thereof by a controllable linear solenoid actuator  28 . System  10  is mounted via a bearing element  30  on a track  32  for traversing secondary CCR  22  across the surface of primary CCR  12  in an axial direction thereof, either continuously or intermittently at a sequence of axial positions. Secondary CCR  22  is not powered for rotation but rather is rotated along the surface of primary CCR  12  by frictional contact therewith.  
         [0030]     As noted above, an operational disadvantage of prior art system  10  is that operator involvement is frequent, either to wash secondary CCR  22  as it gets dirty, when the surface is a triboelectric polymer; or to remove an outer convolution of adhesive tape, when CCR is an roll of adhesive tape, when the adhesive surface becomes loaded with particles removed from primary CCR  12 .  
         [0031]     The remainder of this discussion, and the present invention, are directed to roller cleaning systems wherein the primary CCR is cleaned by being brought into contact repeatedly with a length or circumference of adhesive tape.  
         [0032]     Referring now to  FIGS. 2 and 3 , a prior art sheeted roll of adhesive tape  122  is substantially as disclosed in U.S. Patent Application Publication No. US 2006/0057322 A1. Sheeted tape roll  122  comprises a conventional roll core  140  with individual adhesive sheets  142 ,  144 ,  146  removably attachable around the circumference of the roll core  140  superimposed onto one another. The roll core  140  has an attachment means which may be an adhesive coating to allow the first individual adhesive sheet  142  to be removably attachable around the circumference of the roll core  110 . The individual adhesive sheets  142 ,  144 ,  146  have an adhesive surface  148   a - c  facing outwardly, and have a non-adhesive surface facing inwardly. Alternatively the individual sheets can be rolled such that the adhesive surfaces are facing inwardly and the non-adhesive surfaces are facing outwardly.  
         [0033]     The sheeted roll  122  is formed by attaching a first end  150  of the first sheet  142  onto the roll core  140  and wrapping the first sheet  142  around the circumference of the roll core  140 . The other end  152  of the first sheet  142  will overrun first end  150  by virtue of first sheet  142  being greater in length than the circumference of the roll core  140 . The end  152  is removably attached onto end  150  by the adhesive surface  148   a  of the first sheet  142 .  
         [0034]     A second sheet  144  is then wrapped around the outer circumference of the first sheet  142  with end  154  of the second sheet  144  being abutted to end  152  of the first sheet  142 . The term abutted is to be understood to include being adjacent to, as there may be a gap between successive sheets. The adhesive surface  148   a  of the first sheet  142  will securely hold in place the second sheet  144 .  
         [0035]     A third sheet  146  is then wrapped around the outer circumference of the second sheet  144  with end  158  of the third sheet  116  being abutted to end  156  of the second sheet  114 . The adhesive surface  148   b  of the second sheet  144  will securely hold in place the third sheet  146 . Similarly, further individual adhesive sheets (not shown) are abutted to end  160  of the third sheet  146  and so on until the roll core  140  is “full”.  
         [0036]     It will be realized that because the sheets  142 ,  144 ,  146  are all of the same length, the overrun or circumferential offset of the respective ends  152 ,  156 ,  160 , and so on, will decrease as the roll core  140  becomes “full”. The length of each sheet can however be adjusted as desired or required. The offset of the abutment of the ends of the sheets disperses the load on the roll core  140  making the roll core  140  more stable when rotating.  
         [0037]     Referring to  FIG. 3 , in use, the roll core  140  is positioned such that the outermost sheet of sheeted roll  122  is positioned in contact at a point  164  with the cleaning surface  166  of CCR  12 . As both the roll core  140  and the cleaning roll  12  rotate, impurities located on the cleaning surface  166  will be transferred to the adhesive surface of the outer sheet of sheeted tape roll  122 . When the adhesive surface of the outer sheet becomes contaminated, replacement is achieved simply by peeling the contaminated sheet away by virtue of lip  162 , thus leaving behind a clean sheet to be applied to the cleaning surface  166  of the cleaning roll  12 , until that sheet too needs replacement, and so on.  
         [0038]     Referring now to  FIGS. 4, 4   a , and  5 , a first embodiment  210  of a substrate cleaner in accordance with the invention comprises a turret  270  including first and second winding spindles  272   a , 272   b  having first and second timing pulleys  274   a , 274   b  and first and second one-way clutches  275   a , 275   b  and first and second magnetic particle clutch brakes  276   a , 276   b , respectively, for tension control between the spindles. A reversible tape wind drive motor  278  is provided with an output pulley  280 . A timing belt  282  connects output pulley  280  and timing pulleys  274   a , 274   b . A tailstock stand  284  includes first and second spring-loaded spindle gudgeons  286   a , 286   b  for removably mounting two tape-supporting cores (not shown) to first and second winding spindles  272   a , 272   b , respectively. A backing roller  288  is disposed for idle rotation between turret  270  and stand  284 . A continuous adhesive tape web  242  wound onto one of the cores, preferably at spindle  272   a , is led (adhesive side facing outwards) around backing roller  288  and attached to an empty core mounted at the other spindle. Tape web  242  may be advanced from spindle  272   a , around backing roller  288 , and onto spindle  272   b  by energizing motor  278  in a first direction. Because motor  278  is reversible, the tape web may also be driven in the reverse direction from spindle  272   b  onto spindle  272   a , in accordance with the present invention.  
         [0039]     A currently-preferred method for cleaning a roller such as a CCR  12  comprises the minimum steps of:  
         [0040]     a) engaging the tape web with the CCR surface by advancing the backing roller (CCR is in idler mode);  
         [0041]     b) passing a predetermined first length (preferably 48 inches, as measured by tach sensor  285  and length counter  287 ) of tape over the CCR surface between the unwinder spindle and the winder spindle to clean the CCR surface a first time; and  
         [0042]     c) rewinding the length of tape onto the unwinder spindle to clean the CCR surface a second time.  
         [0043]     Thus the first length of tape is used twice as a roller cleaner. The spent first length of tape may then be advanced permanently onto the winder spindle and stored for later discard, exposing a new, second length of fresh tape, or the first length may be used yet again if its adhesive properties are not significantly diminished. The tape length may be further re-used until it fails to adequately remove particles from the surface to be cleaned.  
         [0044]     In cleaning a CCR having an axial length longer than the width of the tape to be employed, the roller may be cleaned in successive stages by moving the tape to successive cleaning positions along the roller, in accordance with the following process steps:  
         [0045]     a) retracting the CCR from a substrate it has been cleaning (CCR is in idler mode);  
         [0046]     b) advancing the cleaning system to a first cleaning zone on the CCR;  
         [0047]     c) engaging the tape with the CCR surface by advancing the backing roller;  
         [0048]     d) passing a predetermined first length (preferably 48 inches) of tape over the CCR between the unwinder spindle and winder spindle to clean the first cleaning zone a first time;  
         [0049]     e) rewinding the first length of tape onto the unwinder spindle to clean the first zone a second time;  
         [0050]     f) retracting the backing roller and tape from the CCR surface;  
         [0051]     g) re-advancing the tape to place the first predetermined length of tape permanently on the winder spindle;  
         [0052]     h) moving the cleaning system to the next cleaning zone on the CCR (which preferably overlaps slightly the first cleaning zone);  
         [0053]     and i) repeating steps c) through h) until the entire CCR has been cleaned.  
         [0054]     Referring to  FIG. 6 , backing roller  288  may be provided with a relatively compliant (soft) surface layer  288   a , which can be a benefit in assisting system  210   a  in cleaning rollers (typically not CCRs) having surfaces of varying depth or diameter wherein the adhesive tape may be conformably adapted to the roller surface.  
         [0055]     Referring to  FIG. 7 , in a second embodiment  310  of a substrate cleaner in accordance with the invention, the particle brakes, timing pulleys, timing belt, and one-way clutches shown for first embodiment  210  are replaced by first and second torque motors  378   a , 378   b  for driving spindles  372   a , 372   b , respectively. Tension regulation of the tape is readily accomplished by coordination of the two torque motors.  
         [0056]     Referring to  FIGS. 8 and 9 , in a third embodiment  410  of a substrate cleaner in accordance with the invention, the cleaner assembly  411  includes a lift mechanism  490  for adjusting the vertical position of the assembly so that tape  442  passing around backing roller  488  may engage either of two primary CCRs  12   a , 12   b  being used alternately for continuous cleaning of a moving substrate web  14 . The out-of-service CCR is cleaned while the other CCR is in service, allowing for continuous substrate cleaning without the need to stop the substrate to rejuvenate a single CCR. Lift mechanism  490  includes a car  491  that rides on a vertical rail  492 , and a hydraulic piston  493  attached to mechanism  411 , which entire assembly may be translated axially of the CCRs on a horizontal rail  494 .  
         [0057]     Referring to  FIG. 10 , a control and alarm module  500  for the system  210  shown in  FIG. 4  comprises a signal processor  502  for comparing a motor amp signal  504  to a predetermined set point signal  506  and energizing an alarm  508  when the motor amp signal equals the set point signal. In operation, a roll of adhesive tape may be wound from the A spindle to the B spindle and then reversed, B to A, until the entire roll of adhesive tape is spent, in accordance with the previously described steps. Monitoring the motor current during the winding process provides feedback as to the cleanliness of the adhesive tape in contact with the CCR. As the tape progressively accumulates particles, the tack of the tape decreases, leading to a progressive reduction in motor amps necessary to unwind the tape and drive the tape over the surface of the CCR. A motor amp signal indicative of a spent roll of tape is predetermined and is programmed into the processor as the set point. The tape may then be advanced to store the spent portion permanently on the winder and to present a fresh length of tape for repeated rewinding use. Thus, system  210  when coupled to control and alarm module  500  can run without operator supervision or intervention for the full length of a roll of adhesive tape.  
         [0058]     Referring to  FIG. 11 , in a fourth embodiment  610  of a substrate cleaner in accordance with the invention, a tape backing roller such as roller  288  in first embodiment  210  is omitted from the cleaner assembly  611 , creating a free span  607  of tape  242  between first and second spindles  672   a , 672   b . Free span  607  provides conformance with the surface to be cleaned of roller  612  and thereby allows cleaning of irregularly shaped or contoured rollers, such as convex, concave, or bowed rollers.  
         [0059]     Free span  607  also allows for cleaning of very low durometer rollers, and even foam rubber rollers, that might be damaged by line pressure from a hard backing roller such as roller  288 .  
         [0060]     Referring to  FIG. 12 , in a fifth embodiment  710  of a substrate cleaner in accordance with the invention, a cleaner assembly  711  similar to assembly  611  is mounted on a rail car  730  for pivoting about a horizontal axis  713 . Assembly  611  is positioned vertically such that the tape roll associated with first spindle  772   a  functions like a backing roller for tape  742  being pressed against a roller  712  to be cleaned. The pressure exerted by the tape against the roller may be controlled via a controllable actuator  715 , preferably pneumatic, disposed between the assembly  711  and a flange  717  on rail car  730 . In this configuration, the particle clutch brakes  275   a , 275   b  required in embodiment  210  may be eliminated.  
         [0061]     Referring now to  FIG. 13 , in a sixth embodiment  800  of a substrate cleaner in accordance with the invention, a first cleaner assembly  810 , similar to assembly prior art assembly  10  ( FIG. 1 ), is provided with a first sheeted tape roll  840   a , similar to prior art sheeted tape roll  140  ( FIG. 2 ) in replacement of secondary CCR  22  for cleaning primary CCR  12 . Like secondary CCR  22 , sheeted tape roll  840  defining a secondary CCR may be raised into contact with primary CCR  12  and allowed to be driven by such contact through multiple revolutions of roll  840   a , and multiple contacts of outer tape sheet  846   a  with CCR  12 , as may be desired, thus fully utilizing the adhesive capability of outer sheet  846   a . Further, secondary CCR  840   a  may be retracted, moved along rail  832  to a new axial position adjacent primary CCR  12 , and re-engaged therewith for additional revolutions of roll  840   a.    
         [0062]     Referring now to  FIGS. 14 and 15 , renewal of sheeted tape roll  840   a  is carried out in a fashion similar to the renewal of a secondary CCR as shown variously in embodiments  210  ( FIGS. 4 and 10 ) and  410  ( FIGS. 8 and 9 ). Accumulated particles on sheeted tape roll  840   a  are transferred to a continuous adhesive tape roll  840   b  mounted on a cleaner assembly  811  in similar fashion to those previously discussed in accordance with the invention, except that the entire spent tape sheet carrying the particles is also transferred.  
         [0063]     Note that roll  846   a  is mounted for rotation in cleaning use in a counterclockwise direction, as shown in  FIG. 13 , such that winding lip  862  (analogous to prior art lip  162  in  FIG. 2 ) is trailing. Cleaner assembly  811  is advanced to bring tape surface  842  into contact with lip  862 . The lip is engaged therewith, and rotation of spindles  872   a , 872   b  causes the spent outer tape sheet  846   a  to be unwound from sheeted tape roll  840   a  and wound onto adhesive tape surface  842  whereon it is stored on spindle  872   a  for eventual discard when all of roll  840   b  is consumed. Cleaner assembly  811  is retracted, and the next fresh sheet  844   a  on cleaner assembly  810  is now fully exposed and ready for use in further cleaning of CCR  12 . Sheet  844   a  and all additional sheets on sheeted tape roll  840   a  may be similarly stripped and stored on continuous tape roll  840   b  as needed.  
         [0064]     While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.