Patent Publication Number: US-6708615-B2

Title: Powder apparatus for printing press

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a powder apparatus for a printing press which blows powder to the printing surface of a sheet, so that undried ink will not cause setoff between sheets stacked on a pile plate in the delivery unit of the printing press. 
     A powder apparatus of this type for a printing press is disclosed in Japanese Utility Model Registration No. 2578195 (reference 1). The apparatus disclosed in reference 1 has a spray for blowing powder to the printing surface of a sheet which is conveyed as it is held by the grippers of delivery chains, shielding members provided upstream and downstream of the spray in the sheet convey direction to prevent the powder from scattering, and brushes provided to the shielding members and each brought into slidable contact with the grippers of the delivery chains. In this arrangement, the powder blown from the spray toward the printing surface of the sheet is shielded by the shielding members and brushes, so it is prevented from scattering around. 
     In the conventional powder apparatus described above, as each brush is fixed to the corresponding shielding member, when the grippers pass through the brush, the brush is not retreated from the grippers. In this case, if the brush is positioned to come into contact with the grippers entirely, it may interfere with the grippers from traveling, and when it comes into slidable contact with the grippers, the bristles may be pulled out and scatter. For this reason, the brush can be brought into slidable contact with only part of the grippers, and accordingly can be brought close to the sheet held by the distal ends of the grippers only limitedly. A comparatively large gap is thus formed between the distal end of the brush and a paper guide that supports the sheet under conveyance. The powder may desirably scatter around through this gap. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a powder apparatus for a printing press which prevents powder scattering. 
     In order to achieve the above object, according to the present invention, there is provided a powder apparatus for a printing press, comprising sheet conveying means having sheet holding means for holding and moving in a sheet convey direction a sheet having a printing surface, powder spraying means for spraying powder toward the printing surface of the sheet which is being conveyed by the sheet conveying means, and a circular columnar rotary member provided downstream of the powder spraying means in the sheet convey direction and supported rotatably, the rotary member having at least one notch that opposes the sheet holding means, during rotation, which moves along with sheet convey operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a delivery unit for a sheet-fed rotary printing press according to the first embodiment of the present invention; 
     FIG. 2 is a side view of the main part of the delivery unit shown in FIG. 1; 
     FIG. 3 is an enlarged side view for explaining powder spraying operation in the delivery unit shown in FIG. 1; 
     FIG. 4 is a side view of the main part showing a modification of the first embodiment of the present invention; 
     FIG. 5 is a layout view of cylinders to show the second embodiment of the present invention; and 
     FIG. 6 is a layout view of cylinders to show the third embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A delivery unit for a printing press according to the first embodiment of the present invention will be described with reference to FIGS. 1 to  3 . As shown in FIG. 1, a delivery unit  1  for the sheet-fed rotary printing press has a pair of delivery frames  2  each having a substantially inverted-L shape, when seen from the side surface. The delivery frames are connected to each other with a stay (not shown) or the like to oppose each other. A pair of sprockets  3  are rotatably, pivotally mounted on the rear ends of horizontal portions  2   a  of the pair of delivery frames  2 . 
     As shown in FIG. 2, a pair of sprockets  5  are axially mounted on the two end shafts of a delivery cylinder which is in contact with a printing cylinder  4  of a final printing unit. A pair of delivery chains  6  serving as a sheet conveying means extend between the sprockets  3  and  5 . The delivery chains  6  are guided as they are clamped by upper and lower chain guides  7  and  8 , and travel in the direction of arrow A upon rotation of the sprockets  3  driven by the drive side. 
     As shown in FIG. 3, a plurality of gripper bars  10  each having a gripper shaft  11  and gripper pad shaft  12  are supported between the pair of delivery chains  6  at a constant pitch. A plurality of sets of gripper units  15  each consisting of a gripper  13  and gripper pad  14  are provided to each gripper bar  10  to be parallel to each other in the axial direction. A sheet  16 , the leading edge of which has been subjected to gripping change from grippers provided to the printing cylinder  4  of the final printing unit to the gripper units  15  of the delivery chains  6 , is conveyed in the direction of arrow A as the gripper units  15  travel. 
     As shown in FIG. 1, paper guides  17 ,  18 , and  19  divided into three in the convey direction of the sheet  16  are sequentially supported under the convey path of the sheet  16  along the convey path, and support and guide the sheet  16  which is being conveyed. Obliquely above that upright portion of the convey path of the sheet  16  which extends obliquely upward from the start ends of the delivery chains  6 , a spray tube  20  serving as a powder spraying means connected to an air source (not shown) is supported between the pair of delivery frames  2 . 
     The spray tube  20  has a plurality of spray nozzles  21  arranged parallel to each other. Powder sprayed from the spray nozzles  21  is blown to the sheet  16  which is being conveyed. A shielding cover  22  for covering the spray nozzles  21  extends between the pair of delivery frames  2  and is supported by the delivery frames  2 . As shown in FIG. 3, the shielding cover  22  is formed of a spray cover portion  22   a  having a substantially crank-shaped section and one end close to the outer surface of a rotary member  30  (to be described later), and a rotary member cover portion  22   b  extending upward from one end of the spray cover portion  22   a  to cover the outer surface of the rotary member  30 . A brush  23  is fixed to the other end of the spray cover portion  22   a  of the shielding cover  22 . The distal end of the brush  23  is located to be in slidable contact with the traveling gripper units  15  upstream of the spray nozzles  21  in the sheet convey direction (direction of arrow A). More specifically, the shielding cover  22  covers the spray nozzles  21 , thus covering a range from the upstream in the sheet convey direction to the rotary member  30 . 
     In this embodiment, the cover portion  22   b  of the shielding cover  22  covers as far as the outer surface of the rotary member  30 . Alternatively, only the cover portion  22   a  may be provided. It suffices if the powder  33  does not scatter from the gap between the shielding cover  22  and rotary member  30  downstream of the spray nozzles  21  in the sheet convey direction. 
     As shown in FIG. 1, a pile board  25  hung by elevating chains  24  from the horizontal portions  2   a  of the delivery frames  2 , and a pile plate  26  placed on the pile board  25  are provided below the terminal ends of the delivery chains  6  in the sheet convey direction. The sheet  16  gripped by the gripper units  15  of the delivery chains  6  and conveyed by the travel of the delivery chains  6  is released by the gripper units  15  at the convey terminal end, and is dropped onto the pile plate  26  and stacked there. The delivery unit and powder apparatus described above are not different at all from those of the sheet-fed rotary printing press that are conventionally known. 
     The rotary member  30  as the characteristic feature of the present invention will be described. The rotary member  30  forms a substantially circular column, and is provided downstream of the spray tube  20  in the sheet convey direction, as shown in FIG.  3 . Alternatively, the rotary member  30  may form a circular column with no hollow portion, or a circular column with a hollow portion, that is, a cylinder. A notch  31  which has a trapezoidal section and in which the corresponding gripper bar  10  and gripper units  15  can be fitted is formed in part of the outer surface of the rotary member  30  to extend entirely in the axial direction. The outer surface of the rotary member  30  excluding the notch  31  forms a guide surface  32  for guiding the sheet  16 . The rotary member  30  is axially mounted on a rotary shaft  29  rotatably supported between the pair of delivery frames  2 , and the rotary shaft  29  rotates as it is driven by the drive side. The rotary shaft  29  rotates such that the rotating direction and peripheral speed of the rotary member  30  become equal to the convey direction A and convey speed, respectively, of the sheet  16  which is conveyed as it is gripped by the gripper units  15 . 
     The length of circumference of the rotary member  30  is set to be equal to the pitch of the gripper units  15  of the delivery chains  6 . The rotation of the rotary member  30  is synchronized with the travel of the delivery chains  6  so that the gripper bars  10  and gripper units  15  driven to travel by the delivery chains  6  oppose the notch  31 . Therefore, after one row of gripper units  15  of the delivery chains  6  opposes the notch  31  of the rotary member  30 , when the rotary member  30  rotates by one turn, the next row of gripper units  15  opposes the notch  31  of the rotary member  30 . 
     The rotary member  30  axially mounted on the rotary shaft  29  extends between the pair of delivery frames  2 , and is positioned such that its guide surface  32  which forms the outer surface of the rotary member  30  comes close to the paper guide  18 . More specifically, when the guide surface  32  of the rotary member  30  excluding the notch  31  opposes the sheet convey path, the gap formed between the guide surface  32  and paper guide  18  is set very small so that the sheet  16  can barely pass through it. In other words, this gap is set to be slightly larger than the thickness of the sheet  16 . 
     The powder spraying operation of the powder apparatus with the above arrangement will be described. 
     After printing operation, the sheet  16  which has been subjected to gripping change from the grippers of the printing cylinder  4  of the final printing unit to the gripper units  15  of the delivery chains  6  is conveyed in the direction of the arrow A with its printing surface facing up, while it is supported by the paper guides  17  and  18 . When one gripper bar  10  and corresponding gripper units  15  of the delivery chains  6  oppose the notch  31  of the rotary member  30 , the leading edge of the sheet  16  opposes the spray nozzles  21 , and powder  33  sprayed from the spray nozzles  21  is blown to the printing surface of the sheet  16 . 
     Subsequently, the rotary member  30  rotates, so its guide surface  32  opposes the paper guide  18 , and the gap formed between the paper guide  18  and guide surface  32  becomes very small. Hence, the paper guide  18  and guide surface  32  prevent the powder  33  from scattering downstream in the sheet convey direction, and the proportion (amount) of powder  33  fixed on the sheet  16  increases. 
     In addition, as the gap between the paper guide  18  and guide surface  32  is very small, when the sheet  16  passes through it, air flows  34  occur, as shown in FIG.  3 . The air flows  34  drift toward the obverse side of the sheet  16 . Thus, the powder  33  is reliably fixed on the sheet  16  by the air flows  34 . 
     Furthermore, one end of the shielding cover  22  which covers the spray nozzles  21  comes close to the outer surface of the rotary member  30 , and upstream of the spray nozzles  21  in the sheet convey direction, the distal end of the brush  23  comes into slidable contact with the traveling gripper units  15 . Therefore, the powder  33  sprayed by the spray nozzles  21  is prevented from scattering toward the upstream side in the sheet convey direction by the shielding cover  22  and brush  23 . 
     When the guide surface  32  of the rotary member  30  opposes the sheet convey path, the gap between the guide surface  32  and paper guide  18  is very small so that the conveyed sheet  16  can barely pass through it. Therefore, the sheet  16  will not be clamped by the guide surface  32  and paper guide  18  to wave, but is guided smoothly. As the rotating direction and peripheral speed of the rotary member  30  are equal to the convey direction A and convey speed, respectively, of the sheet  16  which is gripped by the gripper units  15 , the guide surface  32  will not damage the printing surface of the sheet  16 . 
     In the first embodiment, the rotary member  30  has one notch  31 . Alternatively, the rotary member  30  may have a plurality of notches. In this case, the pitch of the plurality of notches is set to be equal to that of the gripper units  15 . 
     FIG. 4 shows a modification of the first embodiment. In this modification, a gap W formed by the opposing inner chain guides  7  and  8  is narrow, and the outer surface of a rotary member  30  opposes the return path of delivery chains  6 . In this case, the positions, numbers of teeth, diameters, and the like of the sprockets  3  are set such that when a row of gripper units  15  which grip the sheet  16  and travel opposes the notch  31  of the rotary member  30 , another row of gripper units  15  on the return path of the delivery chains  6  is located in the middle of rows of gripper units  15  which grip the sheet  16  and travel. Thus, the row of gripper units  15  which travel along the return path of the delivery chains  6  also opposes the notch  31  of the rotary member  30 . 
     FIG. 5 shows the second embodiment of the present invention. In the second embodiment, the sheet conveying means is a transfer cylinder  40 . Spray nozzles  21  spray powder  33  to the printing surface of a sheet  16  which is conveyed as it is gripped by grippers  42  of the transfer cylinder  40 . More specifically, the transfer cylinder  40  is in contact with the outer surface of a delivery cylinder having end shafts on which sprockets  5  are axially mounted, and an impression cylinder  43  is in contact with the outer surface of the transfer cylinder  40 . A pair of notches  41  are formed in the outer surface of the transfer cylinder  40  at positions that have an angular interval of 180° in the circumferential direction. The grippers  42  are provided in the respective notches  41 . 
     A pair of notches  44  are formed in the outer surface of the impression cylinder  43  at positions that have an angular interval of 180° in the circumferential direction, and grippers  45  are provided in the respective notches  44 . A blanket cylinder  46  is in contact with the outer surface of the impression cylinder  43 , and a plate cylinder  47  is in contact with the outer surface of the blanket cylinder  46 . 
     A rotary member  48 , provided parallel to the transfer cylinder  40  such that their outer surfaces are at a small gap from each other, is rotatably supported downstream in the sheet convey direction (direction of an arrow B) from the spray nozzles  21  to the transfer cylinder  40 . The rotary member  48  has the same diameter as that of the transfer cylinder  40 , and rotates, when driven by the drive side, in the same direction as the sheet convey direction (direction of arrow B) of the transfer cylinder  40 , i.e., clockwise in FIG.  5 . The rotating speed of the rotary member  48  is also set equal to that of the transfer cylinder  40 . 
     A pair of notches  49  are formed in the outer surface of the transfer cylinder  40  at positions that have an angular interval of 180° in the circumferential direction. When the rotary member  48  and transfer cylinder  40  rotate, the notches  49  oppose the grippers  42  of the transfer cylinder  40 . More specifically, the distance between the notches  49  on the outer surface of the rotary member  48  is set equal to that of the grippers  42  on the outer surface of the transfer cylinder  40 . 
     One end of a shielding cover  22  which covers the spray nozzles  21  is in contact with the outer surface of the rotary member  48 . The distal end of a brush  23  fixed to the other end of the shielding cover  22  comes close to the outer surface of the transfer cylinder  40  in the upstream side of the transfer cylinder  40  in the sheet convey direction (direction of the arrow B). 
     With this arrangement, the surface of the sheet  16  is printed when the sheet  16  passes through the contact point between the blanket cylinder  46  and impression cylinder  43 . After printing, the sheet  16  is subjected to gripping change from the grippers  45  of the impression cylinder  43  to the grippers  42  of the transfer cylinder  40 , and is conveyed in the direction of arrow B by rotation of the transfer cylinder  40 . While the sheet  16  is being conveyed by the transfer cylinder  40 , the powder  33  is sprayed from the spray nozzles  21  to the printing surface of the sheet  16 . 
     At this time, in the downstream side of the spray nozzles  21  in the sheet convey direction, the transfer cylinder  40  and rotary member  48  which oppose each other through a small gap can prevent the sprayed powder from scattering. Also, the shielding cover  22  for covering the spray nozzles  21 , and the brush  23  can prevent the powder  33  from scattering outside. Thus, the proportion (amount) of powder  33  sprayed by the spray nozzles  21  and fixed on the sheet  16  increases. 
     In the second embodiment, the projecting amount of the grippers  42  of the transfer cylinder  40  as the sheet conveying means from the outer surface of the transfer cylinder  40  is small, which is smaller than the projecting amount of the gripper bars  10  from the delivery chains  6  in the first embodiment. Hence, the rotary member  48  can be brought close to the transfer cylinder  40  without forming in the rotary member  48  any notches  49  which oppose the grippers  42 . When no notches  49  are formed in the rotary member  48  in this manner, they need not oppose the grippers  42  of the transfer cylinder  40 . Thus, the diameter of the rotary member  48  need not be equal to that of the transfer cylinder  40 , and a small-diameter cylinder can be used as the rotary member  48 . 
     In this case, a rotary member can be provided in a space upstream of the spray nozzles  21  in the sheet convey direction in place of the shielding cover  22  and brush  23 . When two rotary members are provided upstream and downstream of the spray nozzles  21  in the sheet convey direction, scattering of the powder  33  can be prevented more reliably. In the first and second embodiments, the powder  33  is sprayed to the surface of the sheet  16 . Thus, the first and second embodiments can be applied to both double-sided printing and single-sided printing. 
     FIG. 6 shows the third embodiment of the present invention. In the third embodiment, double-sided printing is performed, and powder  33  is sprayed to the reverse side of the sheet. Between a transfer cylinder  40  as a rotary member and an impression cylinder  54 , another transfer cylinder  50  serving as a sheet conveying means is provided. In this arrangement, while a sheet  16  is conveyed by the transfer cylinder  50 , spray nozzles  21  spray the powder  33 . 
     More specifically, the powder  33  sprayed from the spray nozzles  21  is blown to the reverse side of the sheet  16  which has been subjected to gripping change from grippers  56  formed in notches  55  of the impression cylinder  54  to grippers  52  formed in notches  51  of the transfer cylinder  50 . Subsequently, the sheet  16  is subjected to gripping change from the grippers  52  of the transfer cylinder  50  to grippers  42  of the transfer cylinder  40 , then to gripper units  15  of delivery chains  6 , and is conveyed by the delivery chains  6  such that its reverse side faces down. 
     This arrangement can prevent the powder  33  sprayed by the spray nozzles  21  from scattering downstream of the contact position of the transfer cylinder  50  and transfer cylinder  40  in the sheet convey direction (direction of arrow C). As a shielding cover  22  which covers the spray nozzles  21  and a brush  23  can prevent the powder  33  from scattering outside, the proportion (amount) of powder  33  sprayed from the spray nozzles  21  and fixed on the sheet  16  increases. 
     According to this embodiment, the transfer cylinder  40 , which is in contact with the transfer cylinder  50  and has the grippers  42  for receiving the sheet  16  from the grippers  52  of the transfer cylinder  50 , is utilized as the rotary member. Thus, scattering of the powder  33  can be prevented with the existing arrangement. As a result, not only the structure is simplified, but also the number of components can be reduced. In this embodiment, the powder  33  is sprayed to the reverse side of the sheet  16 . Hence, the third embodiment can be applied to double-sided printing, and single-sided printing in which the sheet is conveyed with its printing surface facing down. 
     In the second and third embodiments, the rotary member  40  or  48  has two notches  41  or  49 , and two grippers  42  or  52  are provided as the sheet holding means. However, the present invention can also be applied to a case wherein the number of sets of the notches and that of the grippers are one. Although the convey target is a sheet, the present invention is not limited to this, but can also be applied a case wherein a plastic sheet or film is to be conveyed. 
     As has been described above, according to the present invention, the outer surface of a rotary member excluding a portion provided with a notch is brought close to a sheet which is being conveyed, and a minimum gap is formed between the outer surface of the rotary member and the paper guide. Therefore, the rotary member and paper guide can prevent scattering of the powder.