Patent Publication Number: US-6338299-B1

Title: Sheet-like material printing and coating system and method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet-like material coating system in a sheet-fed offset printing press. 
     2. Description of the Related Art 
     A polymer-based banknote circulating abroad, called “a plastic banknote”, requires the addition of a treating step after printing, as compared with printing of a banknote based on ordinary paper. That is, coating is performed for the following purposes: 
     (1) Protection for making printed surfaces wear minimally (Sealer). 
     (2) Decreasing gloss, and providing a paper-like texture (Matt). 
     Furthermore, printing intended to prevent forgery, such as printing with ultraviolet luminescent ink (Black Light), is often carried out during this treating step. For these reasons, a machine specifically designed for coating is additionally provided in a process for production of “a plastic banknote”. The coating treatment is performed in the following order: (1) If desired, offset printing aimed for prevention of forgery, (2) application of a sealer, and (3) matting. 
     Generally, a banknote is printed on both sides, and thus requires double-sided coating. Conventional examples of a machine constituted for this purpose are shown in FIGS. 5 and 6. FIG. 5 shows a system composed of two machines arranged for performing printing and coating of a face side and a back side of a sheet separately, in two passes, each machine comprising a feeding unit  100 , a first offset printing unit  101 , a second offset printing unit  102 , a first coating unit  103 , a second coating unit  104 , and a delivery unit  105  provided in this order along flow of the sheet. FIG. 6 shows a system for performing only coating of a face side and a back side of a sheet in one pass by use of an inverting cylinder  108 , the system comprising a feeding unit  100 , a first coating unit  103 , a second coating unit  104 , a first offset printing unit  101 , a second offset printing unit  102 , a third coating unit  106 , a fourth coating unit  107 , and a delivery unit  105  provided in this order along flow of the sheet, the inverting cylinder  108  being interposed between the second coating unit  104  and the first offset printing unit  101 . 
     However, the former system posed the problems of requiring a floor space for installation of the two machines, and necessitating operations for transporting and inverting the sheet between the machines. The latter system occupied a smaller space than the former system, but involved the problem of having a larger entire length per machine, and carrying the risk of causing scratches or rubs during inversion of the sheet. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished in view of the above-described problems. It is an object of the invention to provide a sheet-like material coating system which can perform coating of a face side and a back side of a sheet in one pass with a reduced space and without requiring inversion of the sheet. 
     To attain the above object, the present invention claims a sheet-like material coating system for receiving and transferring a sheet-like material, and coating the sheet-like material, including: 
     an upstream cylinder and a downstream cylinder arranged adjacently in a direction of transport of the sheet-like material; 
     a first coating unit for coating a face side or a back side of the sheet-like material on the upstream cylinder; 
     a first drying device for drying the face side or back side of the sheet-like material on the upstream cylinder after coating by the first coating unit; 
     a second coating unit for coating the back side or face side of the sheet-like material on the downstream cylinder; and 
     a second drying device for drying the back side or face side of the sheet-like material after coating by the second coating unit. 
     According to the foregoing constitution, the coated surface is dried by the first drying device immediately after coating, so that an impression cylinder is prevented from being stained upon intimate contact with the coated surface during coating of the reverse surface. Consequently, double-sided coating is completed in one pass, thereby achieving a saving in space. Moreover, the sheet-like material is not inverted, and thus no scratches or rubs occur. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is a side view of a sheet-fed offset printing press showing a first embodiment of the present invention; 
     FIG. 2 is a side view of a sheet-fed offset printing press showing a second embodiment of the present invention; 
     FIG. 3 is a side view of a sheet-fed offset printing press showing a third embodiment of the present invention; 
     FIG. 4 is a side view of a sheet-fed offset printing press showing a fourth embodiment of the present invention; 
     FIG. 5 is a side view of a sheet-fed offset printing press as a conventional example; and 
     FIG. 6 is a side view of a sheet-fed offset printing press as a different conventional example. 
    
    
     PREFERRED EMBODIMENTS OF THE INVENTION 
     A sheet-like material coating system according to the present invention will now be described in detail by way of the following Embodiments with reference to the accompanying drawings, but it should be understood that the invention is not restricted thereby. 
     First Embodiment 
     FIG. 1 is a side view of a sheet-fed offset printing press showing a first embodiment of the present invention. 
     In FIG. 1, the reference numeral  1  denotes a feeding unit,  2 A,  2 B denote a first and a second face-side coating unit, respectively, for coating a face side of paper (a sheet-like material),  3 A,  3 B denote a first and a second back-side coating unit, respectively, for coating a back side of the paper,  4  denotes a face-side drying unit for drying the face side of the paper,  5  denotes a back-side drying unit for drying the back side of the paper, and  6  denotes a delivery unit. 
     In the illustrated embodiment, four impression cylinders  10  of the coating units  2 A,  2 B,  3 A,  3 B, and two transfer cylinders  11  of the drying units  4 ,  5  are arranged adjacently and nearly linearly in a paper flow direction. Above circumferential surfaces of the odd-numbered cylinders (counted from the upstream side in the paper flow direction) of these cylinders, the first face-side coating unit  2 A, the second face-side coating unit  2 B, and the face-side drying unit  4  are arranged. Below circumferential surfaces of the even-numbered cylinders, the first back-side coating unit  3 A, the second back-side coating unit  3 B, and the back-side drying unit  5  are arranged. Above the circumferential surfaces of the odd-numbered cylinders, a first face-side drying device  7 A and a second face-side drying device  7 B, each of which has one dryer, are disposed downstream of the first face-side coating unit  2 A and the second face-side coating unit  2 B, respectively. Below the circumferential surfaces of the even-numbered cylinders, a first back-side drying device  8 A and a second back-side drying device  8 B, each of which has one dryer, are disposed downstream of the first back-side coating unit  3 A and the second back-side coating unit  3 B, respectively. 
     The feeding unit  1  sucks sheets of paper, which are placed on a sheet piling board (not shown), one by one by a suction device, and feeds the sheet onto a feedboard  12 . The sheet is then fed by a swing arm shaft pregripper  13  to the first face-side coating unit  2 A via a feeding cylinder  14 . 
     The coating units  2 A,  2 B,  3 A,  3 B are ordinary ones each including the aforementioned impression cylinder  10  for receiving paper and holding it, a blanket cylinder  15  adjoining the impression cylinder  10  and having a resin plate (not shown) mounted on a circumferential surface thereof, an anilox roller  16  for supplying varnish to a plate surface of the resin plate on the blanket cylinder  15 , and a chamber coater  17 . 
     It is to be noted that the drying units  4 ,  5  each comprise an aforementioned transfer cylinder  11  and one or more, preferably three, drying devices disposed along a circumferential surface of the respective transfer cylinder as shown, for example, in FIG.  1 . 
     The delivery unit  6  receives the sheet from the back-side drying unit  5  by a delivery chain  19  via a delivery cylinder  18 , transports the thus received sheets, and causes them to fall onto a sheet piling board  20  for piling. 
     Because of the foregoing constitution, a sheet fed from the feeding unit  1  via the feeding cylinder  14  has its face side coated with varnish on the impression cylinder  10  of the first face-side coating unit  2 A, whereby the first coating is performed. Then, the coated sheet is heated and dried by the first face-side drying device  7 A. Then, the sheet has its back side coated with varnish on the impression cylinder  10  of the first back-side coating unit  3 A, whereby the first coating is performed. Then, the coated sheet is heated and dried by the first back-side drying device  8 A. Thereafter, the sheet has its face side coated with varnish on the impression cylinder  10  of the second face-side coating unit  2 B, whereby the second coating is performed. Then, the coated sheet is heated and dried by the second face-side drying device  7 B. Subsequently, the sheet has its back side coated with varnish on the impression cylinder  10  of the second back-side coating unit  3 B, whereby the second coating is performed. Then, the coated sheet is heated and dried by the second back-side drying device  8 B. Thereafter, the sheet has its face side heated and dried on the transfer cylinder  11  of the face-side drying unit  4 , and then has its back side heated and dried on the transfer cylinder  11  of the back-side drying unit  5 . Finally, the sheet is sent to the delivery unit  6  via the delivery cylinder  18 , whereby coating of the face and back sides of the sheet is completed. 
     According to the present embodiment, coating of the face and back sides of a sheet is performed in one pass without using an inverting cylinder (see the inverting cylinder  108  in FIG.  6 ). Thus, a saving in space can be achieved, and no scratches or rubs due to inversion occur. 
     By the way, since the face side and back side of a sheet are alternately coated in one pass, the coated surfaces intimately contact the impression cylinder  10  (and the transfer cylinder  11 ). According to the present embodiment, however, the coated surfaces are heated and dried by the drying devices  7 A,  7 B,  8 A,  8 B immediately after coating. Thus, the circumferential surface of the impression cylinder  10  (and the circumferential surface of the transfer cylinder  11 ) is not stained, and a failure in printing is prevented. 
     Second Embodiment 
     FIG. 2 is a side view of a sheet-fed offset printing press showing a second embodiment of the present invention. This is an embodiment in which two impression cylinders  10  are added forward of the impression cylinder  10  of the first face-side coating unit  2 A in the First Embodiment; above a circumferential surface of the impression cylinder  10  located on the foremost row, a face-side offset printing unit  21  is disposed together with a face-side drying device  22 ; and below a circumferential surface of the impression cylinder  10  located on the second row, a back-side offset printing unit  23  is disposed together with a back-side drying device  24 . The offset printing units  21 ,  23  are ordinary ones each including the aforementioned impression cylinder  10  for receiving paper and holding it, a blanket cylinder  25  adjoining the impression cylinder  10 , and a plate cylinder  26  adjoining the blanket cylinder  25 . The drying devices  22 ,  24  each comprise one dryer. 
     In accordance with this embodiment, offset printing and coating on the face and back sides of paper can be performed in one pass without the use of an inverting cylinder (see the inverting cylinder  108  in FIG.  6 ). Thus, a saving in space and improvement of quality can be realized. Besides, the printed surface and the coated surface are dried immediately after printing and coating. Thus, the circumferential surfaces of the impression cylinder  10  and the transfer cylinder  11  are not stained, and a failure in printing is prevented. 
     Third Embodiment 
     FIG. 3 is a side view of a sheet-fed offset printing press showing a third embodiment of the present invention. This is an embodiment in which first and second face-side offset printing units  27 A and  27 B, and first and second face-side drying devices  28 A and  28 B having the same constitutions as the face-side offset printing unit  21  and the face-side drying device  22 , respectively, in the Second Embodiment are disposed at the positions of the first and second face-side coating units  2 A and  2 B and the first and second face-side drying devices  7 A and  7 B in the First Embodiment; rearward of (downstream of in a paper flow direction) the printing units  27 A,  27 B and the drying devices  28 A,  28 B, the first and second face-side coating units  2 A and  2 B and the first and second face-side drying devices  7 A and  7 B in the First Embodiment are disposed, with impression cylinders  10  being added on both sides of the transfer cylinder  11  having the back-side drying unit  5  in the First Embodiment. Furthermore, the transfer cylinder  11  included in the face-side drying unit  4  in the First Embodiment has been abolished, and instead, three face-side drying devices  7 C have now been disposed inside a delivery chain  19  of a delivery unit  6  that has been extended. 
     In accordance with this Embodiment, not only offset printing and coating on the face side of paper, but also coating on the back side of the paper can be performed in one pass without the use of an inverting cylinder (see the inverting cylinder  108  in FIG.  6 ). Thus, a saving in space and improvement of quality can be realized. 
     Fourth Embodiment 
     FIG. 4 is a side view of a sheet-fed offset printing press showing a fourth embodiment of the present invention. This is an embodiment in which the first and second back-side coating units  3 A and  3 B in the First Embodiment are placed preceding the first and second face-side coating units  2 A and  2 B, and the sheet surface coated by the second face-side coating unit  2 B is heated and dried by the second face-side drying device  7 B disposed in the delivery chain  19  area. The same actions and effects as in the First Embodiment are obtained. 
     This invention being thus described, it will be obvious that the same may be varied in many ways, such that there may be a plurality of the sheet piling boards of the delivery unit. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.