Patent Publication Number: US-6336543-B1

Title: Method for forming a replaceable roll covering and apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part application of U.S. Ser. No. 09/065,846, filed Apr. 22, 1998 U.S. Pat. No. 6,068,100. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates generally to rolls of the type used in roller conveyors and, more particularly, to a roll assembly having a replaceable roll covering. 
     2. Discussion 
     As is known, roller conveyors are used in material handling systems for moving objects from one location to another. Conventional roller conveyors include a series of rolls that are rotatably supported from a rigid frame structure. Typically, the rolls have an elongated cylindrical body segment which is mounted between a pair of frame rails. The cylindrical body segment of the roll can be journalled on a support shaft extending between the frame rails or, in the alternative, can have integral end shafts that are supported in anti-friction bearings mounted in the frame rails. Regardless of the roll type, it is also known to provide a layer of a cover material (i.e., rubber, urethane, etc.) on the outer surface of the cylindrical body segment. The cover layer functions to minimize potential damage to the objects caused by contact with the rolls while concurrently assisting in the frictional movement of the objects on the rolls. Irrespective of the type of material used for the cover layer, its outermost contact surface will ultimately wear and thus necessitate replacement of the roll from the conveyor. Once the roll is removed from the conveyor it is either discarded or refurbished by stripping the old cover layer and subsequently bonding a new cover layer on the roll. As is obvious, this refurbishing process is both labor intensive and expensive. 
     In an effort to minimize the costs associated with replacing and/or repairing worn-out rolls, it has previously been proposed to install a replaceable cover strip on the body segment of the roll. Typically, hook and loop materials, such as Velcro®, and other analogous latch-type fastener products, have been used to releasably secure the cover strip to the body segment of the roll. In such arrangements, a mounting strip is permanently secured to the outer surface of the roll&#39;s body segment and is adapted to receive the replaceable cover strip to which the cover layer is bonded. However, these releasable latch-type mounting arrangements have proven to have limited functional utility. In particular, since the contact interface defined between the interdigitated latching projections on the mounting strip and the cover strip is irregular and of low density, the weight of the objects supported on the rolls may tend to cause undesirable radial and/or circumferential deformation of the cover strip. Thus, a need exists to develop an improved roll covering, and a method for installing and replacing the roll covering on a conveyor roll, which overcomes the shortcomings of the prior art. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a roll assembly comprised of a roll, a carrier strip adapted to be secured to the roll, and a replaceable cover strip adapted to be adhesively bonded to the carrier strip. When it is desired to remove the cover strip from the roll assembly, the cover strip is stripped from the carrier strip such that the adhesive causes a portion of the carrier strip to be pulled away with the cover strip. As such, the newly exposed surface of the carrier strip is then prepared to have a replacement cover strip adhesively bonded thereto. 
     A related object of the present invention is to provide a replaceable cover strip for the roll assembly which includes a substrate layer having an inner surface adapted to be adhesively bonded to the carrier strip, and an outer surface to which a cover layer is bonded. 
     As a further object, the cover strip for the roll assembly of the present invention includes an adhesive layer having an inner surface bonded to the inner surface of the substrate layer and an outer surface capable of being activated for bonding to the carrier strip. 
     It is a further object to provide a carrier strip for the roll assembly of the present invention which includes a base layer having an inner surface adapted to be adhesively bonded to the outer surface of the roll, and an outer surface to which the base layer of the cover strip is adhesively bonded. 
     As a related object, the base layer of the carrier strip is made from a friable and/or peelable material that will release (i.e., slough-off or shed) a thin skin portion of the friable material in response to delaminating the adhesive bond between the adhesive layer of the cover strip and the base layer of the carrier strip. 
     As a further object, the adhesive bond between the roll and the carrier strip has greater strength than the adhesive bond between the cover strip and the carrier strip to permit removal of the cover strip from the roll when replacement is required. 
     Accordingly, the roll assembly of the present invention provides a replaceable roll covering for rolls used in roller conveyors and is further directed to methods of installing and removing the replaceable roll covering. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a portion of an exemplary roller conveyor equipped with the roll assembly of a first preferred embodiment of the present invention. 
     FIG. 2 is an enlarged sectional view taken generally along line  2 — 2  of FIG.  1 . 
     FIG. 3 is an enlarged partial view of FIG.  2 . 
     FIG. 4 is a sectional view of the carrier strip. 
     FIG. 5 is a sectional view of the cover strip. 
     FIG. 6 is a simplified view of an arrangement for manufacturing a roll assembly of a second preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In general, the present invention is directed to a replaceable roll covering for a roll that can be used in virtually any type of material handling system or analogous application. Specifically, a roll covering is disclosed which includes a carrier strip secured to a roll and a replaceable cover strip adhesively bonded to the carrier strip. Removal of the cover strip functions to remove a surface portion of the carrier strip, thereby exposing a new surface which is then ready for receipt of a replacement cover strip. While the following is described in conjunction with a roller conveyor, the roll assembly of the present invention can be used in any other roller applications. 
     Referring to FIGS. 1-5 of the drawings, a roller conveyor constructed in accordance with the teachings of a first preferred embodiment of the present invention is generally identified at reference numeral  10 . A portion of the roller conveyor  10  is shown in FIG. 1 to include a roll assembly  12  supported for rotation from a frame structure  14 . Roll assembly  12  includes a roll  16  and a roll covering  18 . Roll  16  includes an elongated cylindrical body segment  20  on which roll covering  18  is installed and a pair of axle shafts  22  extending coaxially from opposite ends of body segment  20 . Axle shafts  22  are rotatably supported in an otherwise conventional manner, such as by bearing blocks  24 , from between a pair of laterally-spaced frame rails  26  of frame structure  14 . Roll covering  18  provides a wear surface between body segment  20  of roll  16  and objects engaging roll covering  18  that are transported in response to rolling motion of roll  16 . 
     Referring now primarily to FIG. 2 through 5, roll covering  18  will now be described in greater detail. In general, roll covering  18  includes a carrier strip  28  secured to body segment  20  of roll  16 , and a cover strip  30  secured to carrier strip  28 . Cover strip  30  is replaceable in that, when the existing cover strip is worn and requires replacement, it may be stripped from carrier strip  28 . Such removal of a worn-out cover strip causes a surface portion of the carrier strip to be released with the cover strip to expose a new surface to which a replacement cover strip is secured. Thus, a plurality of replacement cover strips can be sequentially installed and removed from the carrier strip prior to necessitating replacement of the carrier strip thereby providing a quick and cost effective system for refurbishing roll assemblies. 
     According to a preferred construction for roll covering  18 , cover strip  30  is, as shown in FIG. 4, a laminated assembly comprised of a substrate layer  32  that is anchored to a cover layer  34 . Cover layer  34  is made of a resilient material such as, for example, natural or synthetic rubber. Other materials for use with cover layer  34  include rubber, urethane, polyester, vinyl, synthetic rubber, synthetic fibers, fiberglass, polymeric material or light gauge metal. Substrate layer  32  is made of dacron or cotton. Preferably, cover layer  34  is adhesively bonded to substrate layer  32  using any conventional adhesive capable of providing the requisite bond strength to avoid delamination during use of roll assembly  12 . To accommodate the step of securing cover strip  30  to carrier strip  28 , an adhesive layer  36  is shown therebetween. If applied as a liquid, adhesive layer  36  can be applied directly to substrate layer  32  or carrier strip  28  prior to anchoring of cover strip  30  to carrier strip  28 . In the alternative, adhesive layer  36  can be an adhesive film or double-sided tape, such as a transferable film acrylic, mounted to substrate layer  32  and which can be activated when cover strip  30  is to be secured to carrier strip  28 . 
     Carrier strip  28  is provided to perform the function of maintaining a strong adhesive bond with body segment  20  of roll  16  while establishing a permanent and intimate bond with adhesive layer  36  of cover strip  30 . As shown in FIG. 5, carrier strip  28  includes a base layer  38  and an adhesive layer  40 . Base layer  38  is made of a friable material such as, for example, rolled paper, short fiber webbings, non-textured webbing of cotton, wool or synthetic, thin short fiber cloth of cotton, wool or synthetic fiber, or the like. Adhesive layer  40  is adapted to permanently bond carrier strip  28  to body segment  20  of roll  16  in such a manner to inhibit delamination of carrier strip  28  from roll  16  during use and during the process of stripping cover strip  30  from carrier strip  28 . 
     As noted, adhesive layer  36  on cover strip  30  functions to bond cover strip  30  to the outermost surface of base layer  38  of carrier strip  28 . Adhesive layer  36  establishes a strong mechanical interface such that the cross-sectional contact between substrate layer  32  of cover strip  30  and friable base layer  38  of carrier strip  28  approaches 100% thereby resulting in minimal mobility at the interface. When replacement of cover strip  30  is desired, the adhesive bond between cover strip  30  and carrier strip  28  is broken such as by peeling or stripping of cover strip  30 . Thereafter, the worn-out cover strip  30  is discarded. However, the adhesive joint between the outermost surface of base layer  38  and adhesive layer  36  causes a thin film or skin of friable material from base layer  38  to be released (i.e., peeled, delaminated, sloughed-off, shed, etc.) and pulled away with cover strip  30 . As such, a new surface of friable material of base layer  38  is exposed to which adhesive layer  36  of a replacement cover strip  30  will be adhesively bonded. Thus, base layer  38  acts as foundation for multiple replacements of cover strips  30  until enough friable material has been shed or sloughed-off to require removal of roll assembly  12  from conveyor  10  for reconditioning roll assembly  12 . During such reconditioning, the old base layer is removed from body segment  20  of roll  16 , and a new carrier strip  28  is adhesively secured to roll  16 , as previously described. Both cover strips  30  and carrier strips  28  can be fabricated as sheets for coaxial mounting on roll  16  or, in the alternative, can be fabricated in rolls of material that are wound in a spiral manner to cover the work areas of roll  16 . As an alternative, cover strip  30  may be laminated to the carrier strip  28  during the manufacturing process to define a one-piece roll covering  18  used to expedite the first installation of roll covering  18  on roll  16 . 
     From the foregoing description, it should be appreciated that the replaceable covering system provides improved cross-sectional contact at the interface between the replaceable outer strip (i.e., cover strip  30 ) and the underlying mounting strip (i.e., carrier strip  28 ). As a result, the replaceable covering is able to resist heavy weights and high pressure during functional operation without deforming or destruction of the bond interface. Additionally, cover strip  30  may be removed and replaced quickly and inexpensively when worn down without the necessity for replacing carrier strip  28 . Finally, the carrier strip  28  serves as a base for multiple replacements of cover strip  30  before the necessity for replacing the carrier strip  28  arises. 
     Turning now to FIG. 6, a simplified view of an arrangement for manufacturing a roll assembly in accordance with the teachings of a second preferred embodiment of the present invention is generally identified at reference numeral  100 . In view of the similarities between the first and second preferred embodiments, like reference numerals will be used to identify like elements. The roll assembly includes a roll  16  and a carrier strip  28  permanently bonded to the roll  16 . The carrier strip  28  includes a friable base layer and an adhesive layer permanently securing the friable base layer to the roll  16 . The friable base layer and adhesive layer are identical to that disclosed above. 
     The roll assembly  16  further includes a cover strip  30  removably secured to the carrier strip  28 . The cover strip includes at least a cover layer  34 . The cover strip  30  may also include a substrate layer as discussed above. 
     The cover strip  30  is secured to the friable layer of the carrier strip  28  through an adhesive layer  36 . In the embodiment illustrated, the adhesive layer  36  is a double sided adhesive tape. A first side is secured to the friable layer of the carrier strip  28  and a second side is secured to the cover strip  30 . 
     As shown in FIG. 6, the carrier strip  28  is completely bonded to the roll  16 . The cover strip  30  is provided from a core roll of cover strip  102 . The double sided adhesive is provided from a core roll  104  which carries the double sided adhesive  36  on a discardable backing  107 . 
     A drive roller  106  rotates in a clockwise direction (indicated by arrow A). The drive roller  106  frictionally engages the roll assembly  12  to thereby rotate the roll assembly  12  in an opposite, counterclockwise direction (indicated by arrow B). The drive roller  106  is interconnected with a driven roller  108  through a belt  110 . As the drive roller rotates clockwise, the belt  110  and driven roller  108  similarly rotate clockwise. 
     The double sided pressure sensitive adhesive tape  36  along with the discardable backing  107  is pressed against the cover strip  30  by a pair of press rollers  112 . In this manner, a first side of the double sided adhesive  36  is secured to the cover strip  30 . the cover strip  30  continues clockwise around a lower one of the press rollers  112  along with the double sided adhesive  36 . Upon passing through the pressure rollers  112 , the discardable backing  107  which carries the double sided adhesive  36  is separated from the double sided adhesive  36  and is spooled on the driven roller  108 . In this manner, the second side of the double sided adhesive  36  is exposed and is secured to the friable layer of the carrier strip  28 . 
     In the embodiment illustrated, the arrangement  100  is illustrated to include a spring biased mechanism  114  for pressing the press rollers  112  together. The spring biased mechanism  114  includes a biasing spring  116 . It will be understood by those skilled in the art that the mechanism  114  is conventional in construction insofar as the present invention is concerned. 
     Those skilled in the art can now appreciate the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification and following claims.