Abstract:
A print cylinder having a first header, a second header and a hollow cylinder body is internally piped. The first header includes an air inlet and an air outlet. The air outlet is sealingly connected to a central conduit which is sealingly attached to a disk, the disk being sealed about its perimeter to the cylinder body. The second header includes an air inlet and at least one air outlet, the air outlet being connected to a perimeter groove defined about the outer surface of the second header. Apertures are defined within the print cylinder immediately above the perimeter groove whereby an air flow continuum is created from the air inlet of the first header, through the central conduit, through the second header inlet and outlet, through the perimeter groove and through the cylinder apertures. Secondary apertures are defined within the cylinder body, each connected in an air flow continuum to the central conduit by means of secondary conduits.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates generally to the field of printing and to rollers and cylinders used in printing presses. More specifically, it relates to an internally piped print cylinder that facilitates both the placement of a print sleeve onto the cylinder and the removal of the sleeve from the cylinder. It also relates to a method for making the internally piped print cylinder that accomplishes this result.  
       BACKGROUND OF THE INVENTION  
       [0002]     The use of flexible printing plates is well known in the art of printing. The printing plate is typically mounted onto a cylindrically hollow and slightly more rigid print sleeve which, in turn, overlays a cylindrical print cylinder. The print cylinder, usually made of a metal material, then rotates about its longitudinal axis at relatively high speeds. Printing plates mounted to a print cylinder in this fashion are particularly useful for printing images and text on surfaces and materials that are soft, flexible and easily deformable. Such flexible surfaces and materials include packaging materials of paper, plastic films or metal foils, or materials with an irregular surface.  
         [0003]     The use of the interposed sleeve provides a surface to which the printing plate can adhere, the print sleeve being relatively rigid in comparison to the generally flexible and pliable printing plate that is secured to it. Moreover, the interposed sleeve allows for the removal of the sleeve, and thus the printing plate, from the print cylinder in order that different print jobs can be run using the same cylinder, the cylinder being a very expansive piece of equipment. In the art, the print sleeve has an inner diameter that is slightly less than that of the outer diameter of the print cylinder. Once in place over the print cylinder, it is intended that the print sleeve frictionally adhere to the print cylinder and not be moved relative to it as the print cylinder rapidly rotates during the printing process. Due to this tight fit, methods and devices have been used to facilitate the mounting of the sleeve onto the cylinder and then the removal of the sleeve from the cylinder.  
         [0004]     In the experience of these inventors, at least one such attempt has been made to air pressurize the inside of the print cylinder and then provide a number of small air apertures about the outer perimeter of the cylinder surface. In this fashion, pressurization of the cylinder interior works to provide air flow through the apertures and, in turn, provide the print sleeve with a layer of pressurized air to ride over. This air pressure expands the inner diameter of the sleeve ever so slightly, but enough to allow the sleeve to be placed over the cylinder in a relatively easy fashion. One disadvantage to this type of cylinder pressurization, however, is that it requires a greater volume of pressurized air to accomplish the intended purpose. That is, sufficient air flow through the apertures is only accomplished when the complete interior of the cylinder in adequately pressurized. Not only may such cylinders not qualify as certifiably safe pressure vessels, but there is additional time that is required to pressurize the entire cylinder. This takes time away from production. Additionally, the pressurized air supply typically includes air contaminants, including moisture, which, in larger volume vessels, may accumulate in the vessel and work to corrode and destroy the vessel from within.  
       SUMMARY OF THE INVENTION  
       [0005]     It is therefore an object of the present invention to provide a new and useful print cylinder that is internally piped so as to facilitate the application of a print sleeve to the cylinder and to facilitate the removal of the print sleeve from the cylinder. It is another object of the present invention to provide a method for making the internally piped print cylinder such that a much smaller volume of space is required to be pressurized in order to accomplish the intended result. It is a further object to provide such an internally piped print cylinder that is fabricated in accordance with the method of the present invention as original equipment or as a retrofit to an existing cylinder with the same effect. It is still another object of the device and method of the present invention to fabricate and assemble such a device which will accomplish all of the foregoing without great expense, which will allow printers to readily and easily use the device, and which utilizes a minimum number of elements to assemble and a minimum number of steps to operate.  
         [0006]     The apparatus and method of the present invention has obtained these objects. It provides for a method of fabricating or retrofitting a print cylinder that is internally piped. The print cylinder of the present invention includes a drive side header and a tending side header. Extending between the headers is the hollow cylinder body. The drive side header includes an air inlet and an air outlet. The air outlet is sealingly connected to one end of a central cylinder conduit. The other end of the central conduit is sealingly attached to a disk, the disk being sealed about its perimeter to the inner surface of the cylinder. The tending side header includes an air inlet and at least one air outlet, the air outlet being connected to a perimeter groove that is defined about the outer surface of the tending side header, the outer surface of the tending side header being located within the inner surface of the print cylinder. A plurality of air flow apertures are defined within the print cylinder immediately above the perimeter groove whereby an air flow continuum is created from the air inlet of the drive header, through the central conduit, through the tending header inlet, through the tending header outlet, through the perimeter groove and through the cylinder apertures. Additionally, a plurality of secondary apertures are defined within the surface of the cylinder and are connected in an air flow continuum to the central conduit by means of secondary conduits that are sealingly connected to the central conduit and to the inner surface of the print cylinder. In this fashion, the method of the present invention can be used with new print cylinders or incorporated into existing print cylinders, all with the same effect.  
         [0007]     The foregoing and other features of the method and apparatus of the present invention will be apparent from the detailed description that follows. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1  is a front elevational and cross-sectioned view of a print cylinder constructed in accordance with the present invention.  
         [0009]      FIG. 2  is a front and right side perspective view of the internally piped print cylinder constructed in accordance with the present invention and illustrating a print sleeve being slid over the outer surface of the cylinder.  
         [0010]      FIG. 3  is a front and right side perspective view of the print cylinder and sleeve illustrated in  FIG. 2  and showing the sleeve in its fully attached position.  
         [0011]      FIG. 4  is an enlarged and cross sectioned view of the internal piping of the print cylinder shown in  FIG. 1 .  
         [0012]      FIG. 5  is an exploded left side and front perspective view of the component parts used in the print cylinder of the present invention.  
         [0013]      FIG. 6  is a greatly enlarged right side elevational and cross sectioned view of a lateral pipe used in the print cylinder of the present invention taken along line  6 - 6  in  FIG. 4 .  
         [0014]      FIG. 7  is a right side elevational and cross sectioned view of the tending side header of the print cylinder of the present invention taken along line  7 - 7  in  FIG. 4 . 
     
    
     DETAILED DESCRIPTION  
       [0015]     The following detailed description is intended to describe the preferred embodiment that is depicted in the figures. It is to be understood that changes could be made to that which is specifically described and shown that would still fall within the scope of the present invention. Referring now to the drawings in detail, wherein like numbered elements refer to like elements throughout,  FIG. 1  illustrates the basic components of the internally piped print cylinder, generally identified  10 , constructed in accordance with the present invention.  
         [0016]     As shown in  FIG. 1 , and in greater detail in  FIG. 4 , the print cylinder  10  includes a drive side header  20 , a tending side header  40  and a cylindrical portion  60  extending between the headers  20 ,  40 . As shown, the print cylinder  10  also includes an internal central pipe  80 .  
         [0017]     The drive side header  20  is generally located at the drive side of the printing press (not shown). The drive side header  20  includes a proximal end  22  and a distal end  24 . The proximal end  22  of the drive side header  20  includes an air inlet bore  26 , the air inlet bore  26  being disposed generally perpendicular to the axis of the drive side header  20 . The drive side header  20  also includes a first internal bore  28 , the first internal bore  28  being disposed along the axis of the drive side header  20  and intersecting the air inlet  26 . The first internal bore  28  extends from the proximal end  22  of the drive side header  20  to the distal end  24  of it. A second internal bore  32  is also provided at the distal end  24  of the drive side header  20  and is axially aligned with the drive side header  20 , but is of a diameter that is substantially greater than that of the first internal bore  28 . The driver side header  20  also includes an outer surface  34 .  
         [0018]     The print cylinder  10  also includes a tending side header  40 . The tending side header  40  is located at the tending, or operator, side of the printing press (not shown). The tending side header  40  includes a proximal end  42  and a distal end  44 . Disposed axially within the proximal end  42  of the tending side header  40  is a first internal bore  46 . The first internal bore  46  does not extend through to the distal end  44  of the tending side header  40 . Disposed perpendicularly to the axis of the tending side header  40  is a second internal bore  48 . The tending side header  40  also includes an outer surface  54 . As Shown in  FIG. 4 , the second internal bore  48  of the tending side header  40  extends from one side of the outer surface  54  of the tending side header  40  to the opposite side of that same circumferential surface  54 . It is to be understood, however, that the second bore  48  need only extend to the surface  54  of the tending side header  40  at one point. Defined completely circumferentially within the outer surface  54  of the tending side header  40  is a peripheral groove  52 . The shape of this groove  52  is not a limitation of the present invention. The function and purpose of this peripheral groove  52  will become apparent further in this detailed description.  
         [0019]     Extending between the drive side header  20  and the tending side header  40  of the print cylinder  10  is a central cylinder portion  60 . Situated toward the drive side header  20  is the proximal end  62  of the cylinder  60 . Situated at the tending side header  40  is the distal end  64  of the cylinder  60 . The cylinder  60  includes an internal cavity  66  that runs substantially the length of the cylinder  60 . The cylinder  60  also includes an outer cylinder surface  68 .  
         [0020]     The print cylinder  10  of the present invention further includes an internal piping arrangement. Specifically, a centrally disposed internal pipe  80  is included and extends between the drive side header  20  and the tending side header  40 . The internal pipe  80  does not, however, extend completely to the tending side header  40 . The central tube  80  includes a proximal end  82  and a distal end  84 . The central tube  80  also includes an internal bore  86  that extends between the proximal end  82  and the distal end  84 . The proximal end  82  of the central pipe  80  is functionally adapted to be received by the second internal bore  32  of the drive side header  20 . Situated at the distal end  84  of the pipe  80  is a sealing plate  90 . The sealing plate includes a central bore  92  and an outer perimeter  94 . See  FIG. 5 . The distal end  84  of the central pipe  80  is functionally adapted to be received within the central bore  92  of the sealing plate  90 .  
         [0021]     Extending outwardly from the central pipe  80 , and located at various positions along the length of the print cylinder  10 , are a plurality of auxiliary pipes  70 . See also  FIG. 6 . Each auxiliary pipe  70  is disposed generally 180° from the next auxiliary pipe  70 . See  FIG. 1 . Referring again to  FIG. 6 , it will be seen that each pipe  70  includes a proximal end  72 , a distal end  74  and a central bore  76 . The proximal end  72  of each auxiliary pipe  70  is functionally adapted to be secured within an aperture  85  defined within the central pipe  80 . The distal end  74  of each auxiliary pipe  70  is functionally adapted to be secured within an aperture  61  defined within the outer surface  68  of the central cylinder  60 . See  FIG. 5 . In this fashion, an air pressure and air flow continuum is created between the drive side header inlet  26 , the first internal bore  28  of the drive side header, the central pipe bore  86 , the auxiliary pipe bore  76  and the outer surface  68  of the central cylinder  60 . See  FIG. 4 .  
         [0022]     In application, a basic print cylinder is provided which has a drive side header  20 , a central cylinder  60  and a tending side header  40  as previously described. These basic elements would be original manufacture items that are being modified at the time of manufacture or retrofitted at a later time after the cylinder  10  has been used in production for a period of time.  
         [0023]     With the drive side header  20  separated from the central cylinder  60 , the inlet bore  26  and the first and second internal bores  28 ,  32 , respectively, are drilled into the drive side header  20 . The proximal end  82  of the central pipe  80  is then threadably secured or welded  81  into the second internal bore  32  of the drive side header  20 . The drive side header  20  and the central cylinder  60  are then reattached, preferably by weldment  21 . The sealing plate  90  is then positioned such that the central bore  92  of the plate  90  engages the distal end  84  of the central pipe  80 . The outer periphery  94  of the plate  90  is placed internally of the distal end  64  of the cylinder  60 . The sealing plate  90  is then welded  91 ,  93  to the cylinder  60  about its periphery  94  and to the central pipe  80  about the central bore  92 , respectively.  
         [0024]     The tending side header  40  is also modified to include the internal bores  46 ,  48  and periphery groove  52  as previously described and is then welded  41  back into the distal end  64  of the central cylinder  60 . In this fashion, a relatively small central cylinder void  69  is created between the sealing plate  90  and the proximal end  42  of the tending side header  40 . With these elements in place, the outer surface  68  of the central cylinder  60  is then strategically and carefully drilled to intersect axially with the central pipe  80 . The central pipe apertures  85  are then threaded and the auxiliary pipes  70  are inserted and the proximal pipe end  72  is secured. At the outer surface  68  of the central cylinder  60 , the distal pipe end  74  is welded into place and a small hole  65  is drilled through the weldment. Similar small holes  67  are drilled about the periphery of the central cylinder  60  at its distal end  64 , such holes  67  being aligned with the periphery groove  52  of the tending side header  40  which lies directly below them. As shown in  FIG. 7 , these small holes  67  are aligned at 45° relative to one another.  
         [0025]     When pressurized air is applied to the air inlet  26  of the drive side header  20 , the air flow continues through the first and second internal bores  28 ,  32 , respectively, of the drive side header, and into the bore  86  of the central pipe  80 . Pressurized air then continues through each of the auxiliary pipes  70  and through the hole  65  at the surface  68  of the central cylinder. Pressurized air fills the void  69  between the sealing plate  90  and the proximal end  42  of the tending side header  40  and enters the first bore  46  thereof. The pressurized air flows through the secondary bore  48  to the periphery groove  52  of the tending side header  40  and escapes through the holes  67  defined above the groove  52 . In this fashion, a sleeve  100  may be placed over the cylinder  10  as pressurized air creates a layer of air over which the sleeve  100  may pass. See  FIGS. 2 and 3 . It is to be understood that the expansion of the sleeve  100  as shown in  FIG. 2  is greatly exaggerated. A greater number of holes  67  at the tending side header  40  end of the cylinder  10  is desirable to assist with initial placement of the sleeve  100  onto the cylinder  10 .  
         [0026]     Accordingly, it will be seen from the foregoing that there has been provided a new and useful print cylinder that is internally piped so as to facilitate the application of a print sleeve to the cylinder and to facilitate the removal of the print sleeve from the cylinder; that provides an apparatus and a method for making the internally piped print cylinder such that a much smaller volume of space is required to be pressurized in order to accomplish the intended result; that is fabricated in accordance with the method of the present invention as original equipment or as a retrofit to an existing cylinder with the same effect; and which accomplishes all of the foregoing without great expense, which will allow printers to readily and easily use the device, and which utilizes a minimum number of elements to assemble and a minimum number of steps to operate.  
         [0027]     The principles of this invention having been described in accordance with the foregoing,