Abstract:
An end ring assembly for attachment to a cylindrical rotary printing screen includes an annular support ring adapted to be attached to an interior wall of the cylindrical rotary printing screen, and a drive ring adapted to be releasably attached to the annular support ring in position registration with the support ring to maintain alignment therewith upon rotation of the drive. A method of cleaning and/or storing a cylindrical rotary printing screen includes providing a cylindrical rotary printing screen having two opposed ends, and providing an end ring assembly on each end of the screen. Each end ring assembly has an annular support ring attached to an interior wall of the cylindrical rotary printing screen and a drive ring releasably attached to the annular support ring in position registration with the support ring. The drive rings are removed from the respective support rings, so that printing screen can be cleaned and/or stored with the support rings still attached.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    This invention relates to an end ring for a rotary printing screen, more particularly to a split end ring having a screen-supporting ring and a drive ring separable from the screen-supporting ring, and a method of cleaning and/or storing a cylindrical rotary printing screen. 
       BACKGROUND OF THE INVENTION 
       [0002]    Rotary screen printing entails use of a pattern-perforated or woven screen that is generally constructed of thin metal film layer. The metal film layer of the screen is typically so thin that the screen collapses or at least deforms under its own weight when laid along its longitudinal axis and is vulnerable to damage when handled such that cleaning of the screen is not typically feasible. The screen is typically mounted between end rings that have gears driven by a screen-printing machine. A number of the screens are driven in registration with each other and individually lay down an ink layer onto a substrate that collectively forms the desired image. The end rings typically have screen-facing ends that are glued into the longitudinal ends of the screen and opposing ends having gears, which are typically heavy and expensive to manufacture. A typical screen does exhibit some degree of rigidity once the end rings are mounted into the screen, but the screen is nonetheless subject to collapse during handling if the screen is used to support the heavy end rings. Thus, heavy geared end rings are particularly problematic with longer screens. 
         [0003]    The screen is usually permanently attached to an end ring at each end of the screen. Removal of the screen from the end rings typically destroys the screen. Thus, the end rings can be salvaged for re-use, but the screen cannot be easily cleaned unsupported once it is unattached from the end rings even if the screen survives the removal intact. Even if a careful arrangement is made to store the screen with the heavy geared end rings attached, the expensive geared end rings are then unavailable for use with other printing jobs until they are ultimately recovered from the screen. Thus, if a mounted screen for a particular print job is to be taken from a printing machine and stored while other print jobs are completed, extra ones of the expensive geared end rings are required. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    Therefore it is an object of the present invention to provide a split end ring having a support ring for attachment to a cylindrical rotary printing screen to support the screen and a drive ring releasably attachable to the support ring for rotating the screen when driven by a rotary screen printing machine. According to at least one embodiment of the invention, an end ring assembly for attachment to a cylindrical rotary printing screen includes an annular support ring adapted to be attached to an interior wall of the cylindrical rotary printing screen, and a drive ring adapted to be releasably attached to the annular support ring in position registration with the support ring to maintain alignment with the support ring during machine operation. 
         [0005]    According to another embodiment of the invention, a method of cleaning and/or storing a cylindrical rotary printing screen includes the steps of providing a cylindrical rotary printing screen having two longitudinal ends, and providing an end ring assembly for each end of the screen. Each end ring assembly has an annular support ring attached to an interior wall of the cylindrical rotary printing screen and a drive ring releasably attached to the annular support ring in position registration with the support ring. When not in use, the drive rings can be removed from the support rings, and the printing screen cleaned and/or stored with the attached support rings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The subject matter that is regarded as the invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
           [0007]      FIG. 1  is an exploded perspective view of a split end ring for rotary screen printing according to one embodiment of the present invention; 
           [0008]      FIG. 2  is a perspective view of the of split end ring of  FIG. 1 , shown assembled, and a cylindrical rotary printing screen; 
           [0009]      FIG. 3  is a plan view of the screen-facing sides of the drive ring and support ring of  FIG. 1 ; 
           [0010]      FIG. 4  is a plan view of the screen-opposing sides of the drive ring and support ring of  FIG. 1 ; 
           [0011]      FIG. 5  is an elevation view of the drive ring of  FIG. 1 ; 
           [0012]      FIG. 6  is an elevation view of the support ring of  FIG. 1 ; 
           [0013]      FIG. 7  is a plan view of the screen-opposing side of the split end ring of  FIG. 1 , shown assembled. 
           [0014]      FIG. 8  is an exploded perspective view of a split end ring for rotary screen printing according to another embodiment of the present invention, having a drive ring and a support ring; 
           [0015]      FIG. 9  is a perspective view of the split end ring of  FIG. 8 , shown assembled; and 
           [0016]      FIG. 10  is a plan view of the screen-opposing side of the split end ring of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Referring now to the drawings, where identical reference numerals denote the same elements throughout the various views,  FIG. 1  shows a split end ring  10  according to one embodiment of the present invention. The split end ring  10  includes a support ring  100  and a drive ring  200  that are two separate parts when the split end ring is disassembled as shown in  FIG. 1 . The support ring  100  has an annular body  102  having a cylindrical outer bearing surface  104  to which the interior wall  304  of a rotary printing screen  300  ( FIG. 2 ) is to be attached by an adhesive at the longitudinal end  302  of the rotary printing screen  300 . The support ring  100  has a screen-facing side  106  that faces into the screen  300  and a screen-opposing side  108  that faces outward toward the drive ring  200 . As shown in  FIG. 6 , the support ring  100  has a raised annular shoulder  110  on the screen-opposing side  108  that abuts the drive ring  200  when the split end ring  100  is assembled as shown in  FIG. 2 . The support ring  100  has a cylindrical inner surface  112  that fits around a cylindrical extension  202  ( FIG. 1 ) of the drive ring  200  upon assembly of the split end ring  100  as shown in  FIG. 2 . 
         [0018]    Like the support ring  100 , the drive ring  200  has a screen-facing side  206  that faces toward the screen  300  and the support ring  100 , and a screen-opposing side  208  that faces outward away from the screen  300  and support ring  100 . The screen-facing sides  106  and  206  of the support ring  100  and drive ring  200  are shown in  FIG. 3 . The screen-opposing sides  108  and  208  of the support ring  100  and drive ring  200  are shown in  FIG. 4 . The cylindrical extension  202  of the drive ring  200  extends longitudinally from the screen-facing side  206  as shown for example in  FIGS. 1 ,  3  and  5 . Registration pins  220  extend from the screen-facing side  206  of the drive ring  200  to be received in corresponding registration holes  120  of the support ring  100  to assure a proper alignment arrangement between the drive ring  200  and support ring  100 . The pins  220  are attached to the drive ring  200  by press fitting the pins into holes formed in the drive ring and are flush with the screen opposing side  208  of the drive ring. 
         [0019]    As shown in  FIGS. 3 and 4 , the drive ring  200  has multiple connector holes  222  and the support ring  100  has corresponding threaded connector holes  122  through which the drive ring  200  and support ring  100  are connected together by screws  12  as shown in  FIG. 7  upon assembly of the drive ring  200  and support ring  100 . As shown in  FIG. 4 , countersink spaces  224  are formed around the connector holes  222  in the screen-opposing side  208  of the drive ring  200  to receive the heads of the screws  12  flush with the surface of the screen-opposing side  208  of the drive ring  200 . 
         [0020]    To assemble the split end ring  100 , the shoulder  110  of screen-opposing side  108  of the support ring  100  is abutted against the screen-facing side  206  of the drive ring  200 , with the registration pins  220  of the drive ring  200  extending through the registration holes  120  of the support ring  100 . Then the screws  12  are passed through the connector holes  222  of the drive ring  200 , threaded into the connector holes  122  of the support ring  100 , and tightened by turning the heads of the screws in a clockwise direction. Disassembly of the split end ring  100  is accomplished by these steps taken in reverse order. 
         [0021]    While the Figures illustrated two registration pins  220  and two corresponding registration holes  120 , the descriptions relate to more or less pins and holes as well. Similarly, while three connectors holes  122  and  222  are illustrated in each of the support ring  100  and drive ring  200 , respectively, for accommodating three connecting screws, these descriptions relate to support rings and drive rings connected by more or less screws as well. For example, in at least one embodiment, the support ring and drive ring each have four connecting holes for accommodating four screws that connect the drive ring to the support ring. 
         [0022]    The drive ring  200  has a spur gear  230  by which the entire assembly of the drive ring  200 , support ring  100 , and screen  300  are rotated when installed in a rotary printing machine and used in printing. The screen  300  in use will have an assembled end ring  10  attached to each longitudinal end  302  ( FIG. 2 ). A cylindrical idler extension  234  extends longitudinally opposite the cylindrical extension  202  and outwardly from the screen-opposing side  208  of the drive ring  200  beyond the spur gear  230  to roll upon idler rollers or other supporting elements of the printing machine. A guide flange  236  extends radially outward from the longitudinal end of the idler extension  230  such that the idler extension, the guide flange  236  and the screen-opposing side  208  of the drive ring form a channel within which idler rollers or other supporting elements may support the rotating drive ring  200  when in use. 
         [0023]    When a particular screen is not in use or is to be cleaned, the drive rings  200  at the longitudinal ends of the screen are removed from their respective support rings  100 , which remain attached to the screen to support the screen in a rigid cylindrical shape as the screen is cleaned and/or stored. The drive rings  200  are then available for use with other screens thus reducing the need for inventories of expensive drive rings. The support rings  100  may be recovered once a screen is of no further use or may be discarded with the screen. 
         [0024]    The support ring  100  is constructed of a suitably lightweight, relatively inexpensive material that is sufficiently rigid to support the screen in a cylindrical shape as the screen is cleaned and/or stored, and is yet relatively inexpensive to use in the manufacturing of the support ring. Aluminum and other metals may be selected for their durability against cleaning solvents like acetone where multiple reuse of the support ring is contemplated. Polyvinyl chloride (PVC) or other plastics such as nylon and delron may be selected for their relatively low costs where the support rings may be contemplated as expendable. Relatively large numbers of the support rings  100  can therefore be used without undue expense. The drive ring  200  is preferably constructed of a durable material, such as aluminum or other rigid material. The drive rings  200  may be removed from a screen and reused without also removing the support ring  100  from the screen, thus minimizing the quantity required and substantially reducing the expense of purchasing and inventorying the relatively expensive parts. The drive rings  200  can be removed easily from a screen mounted support ring  100  and attached to another support ring  100 . 
         [0025]    A split end ring  400  according to another embodiment of the invention is shown in  FIGS. 8-10 . The split end ring  400  includes a support ring  500  and a drive ring  600  that are two separate parts when the split end ring is disassembled as shown in  FIG. 8 . The support ring  500  has an annular body  502  having a cylindrical outer bearing surface  504  to which the interior wall of a rotary printing screen is to be attached by an adhesive at the longitudinal end of the rotary printing screen. The support ring  500  has a screen-facing side  506  that faces into the screen and a screen-opposing side  508  the faces outward toward the drive ring  600 . The support ring  500  has a cylindrical inner surface (not shown) that fits around a cylindrical extension  602  of the drive ring  600  upon assembly of the split end ring  400  as shown in  FIG. 9 . 
         [0026]    Like the support ring  500 , the drive ring  600  has a screen-facing side  606  and a screen-opposing side  608  that faces outward away from the screen and support ring  500 . The cylindrical extension  602  of the drive ring  600  extends from the screen-facing side  606  as shown in  FIG. 8 . As also shown in  FIG. 8 , registration pins  620  extends from the screen-facing side  606  of the drive ring  600  to be received in corresponding registration holes of the support ring  500  to assure a proper alignment arrangement between the drive ring  600  and support ring  500 . 
         [0027]    As shown in  FIG. 10 , the drive ring  600  has multiple connector holes  622  and the support ring  500  has corresponding connector holes (not shown) through which the drive ring  600  and support ring  500  are connected together by screws (not shown) upon assembly. Countersink holes  624  are formed around the connector holes  622  in the screen-opposing side  608  of the drive ring  600  to receive the heads of the screws flush with the surface of the screen-opposing side  608  of the drive ring  600 . 
         [0028]    To assemble the split end ring  400 , the screen-opposing side  508  of the support ring  500  is abutted against the screen-facing side  606  of the drive ring  600 , with the registration pins  620  of the drive ring  600  extending through the registration holes of the support ring  500 . Then screws are passed through the connector holes  622  of the drive ring  600 , threaded into the connector holes of the support ring  500 , and tightened by turning the heads of the screws in a clockwise direction. Disassembly of the split end ring  400  is accomplished by these steps taken in reverse order. 
         [0029]    The drive ring  600  has a flange  630  that extends radially outward at the screen-opposing side  608 . An idler channel  632  ( FIG. 9 ) is defined between the flange  630  and the support ring  500 . Within the channel  632 , an outer cylindrical surface  634  of the drive ring  600  rolls upon idler rollers or other supporting elements of the printing machine when the drive ring  600 , support ring  500 , and screen are installed in a rotary printing machine and used in printing. The flange  630  has a drive slot  636  ( FIG. 10 ) by which the drive ring  600 , support ring  500 , and screen are rotated when in use. 
         [0030]    A printing screen in use will have an assembled end ring  400  attached to each longitudinal end. When a particular screen is not in use or is to be cleaned, the drive rings  600  at the longitudinal ends of the screen are removed from their respective support rings  500 , which remain attached to the screen to support the screen in a rigid cylindrical shape as the screen is cleaned and/or stored. The drive rings  600  are then available for use with other screens thus reducing the need for inventories of expensive drive rings. The support rings  500  may be recovered once a screen is of no further use or may be discarded with the screen. 
         [0031]    The support ring  500  and drive ring  600  can be constructed of material as described above with reference to support ring  100  and drive ring  200 . 
         [0032]    The foregoing has described split end rings having releasably attachable support rings and drive rings. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.