Abstract:
A roll for a printing press has at least two circular partial areas ( 25, 33 ) made of an ink-friendly material and at least one circular partial area ( 23, 34 ) made of an ink-repellent material, which is arranged between the at least two circular partial areas ( 25, 33 ) made of ink-friendly material. A process is provided for manufacturing such a roll, wherein at least two annular structures ( 25, 33 ) made of an ink-friendly material and, located between these annular structures, at least one annular structure ( 23, 34 ) made of an ink-repellent material are formed on a blank roll body ( 20, 30 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims the benefit of priority under 35 U.S.C. § 119 of German patent application DE 103 16 240.2 filed Apr. 9, 2003 the entire contents of which are incorporated herein by reference.  
         FIELD OF THE INVENTION  
         [0002]    The present invention pertains to a roll, especially a roll that can be used in a printing press, for example, in the inking or damping system, and to a process for manufacturing such a roll.  
         BACKGROUND OF THE INVENTION  
         [0003]    [0003]FIG. 4 shows a roll diagram of a printing couple, through which a web B to be printed on runs. In the arrangement shown in FIG. 4, the web B is first guided over an inking roll  1 ′, with which a first rubber blanket cylinder  2 ′ and a second rubber blanket cylinder  2 ″ are in contact, and is led farther for postdamping over another inking roll  1 , with which a first rubber blanket cylinder  2  and a second rubber blanket cylinder  2 ″ are likewise in contact. The roll diagram is described based on the example of a printing couple design used for postdamping. A damping agent applicator roll  11  is in contact with the plate cylinder  3 , which is in contact with the rubber blanket cylinder. The damping agent applicator roll  11  is in contact with a distributing roller  12 , the so-called damping agent distributor. The damping agent transfer roll  13  is in contact with this distributing roller, and the damping agent transfer roll receives the damping agent sprayed on it via a contactless damping system. The damping agent transfer roll  13 , the distributing roller  12  and the damping agent applicator roll  11  transfer the damping agent to the plate cylinder  3 , as a result of which the desired predamping and postdamping are achieved.  
           [0004]    The inking rolls  4  that are in contact with the plate cylinder  3  transfer ink from the first distributing roller  5   a  that is in contact with them, the first, so-called distributor. The rubber blanket cylinder  6   a , which is further in contact with a second ink distributor  5   b , is in contact with the ink distributor  5   a , and two other rubber blanket cylinders  6   b  and  6   c  are in contact with the said second ink distributor  5   b . The rubber blanket cylinder  6   c  is in contact with the ink film roll  7 , with which the ink doctor roll  8  and the dipping roll  10  are in contact in the known manner. The ink distributor  5   a  is inked in the known manner via the rubber blanket cylinders  6   a ,  6   c , the additional ink distributor  5   b , the ink film roll  7 , via the ink doctor roll  8 , on which the ink is metered by means of doctor knives, which are arranged in the doctor knife bar  9 , and via the dipping roll  10 , which dips into the ink in the ink tray.  
           [0005]    An exemplary inking and damping system is shown in the Applicant&#39;s DE 40 12 283 A1 (and corresponding U.S. Pat. No. 5,090,314). DE 40 12 283 A1 and U.S. Pat. No. 5,090,314 are hereby incorporated by reference in their entirety and in particular, the teaching of these documents concerning the design of an inking and damping system is incorporated by reference.  
           [0006]    It is known from DE 40 122 83 A1 that distributing rollers have a surface made of copper in order for these rollers to have an ink-friendly surface.  
           [0007]    If two different inks are printed on two webs located next to each other, it may happen that the damping agent distributors  12  moving to and fro mix the different inks used in two webs running next to each other, which leads to unsatisfactory printing results.  
         SUMMARY OF THE INVENTION  
         [0008]    One object of the present invention is to provide a roll, especially for a printing press, which reduces or prevents the mixing of inks in the case of webs running next to each other.  
           [0009]    According to the invention, a roll for a printing press is provided with at least two partial areas running around the central axis of the roll, which are made of an ink-friendly material. At least one circular partial area made of an ink-repellent material is arranged between the at least two circular partial areas made of ink-friendly material.  
           [0010]    The roll according to the present invention is preferably used for postdamping, in which there is a risk that ink flows back into the damping system.  
           [0011]    The roll according to the present invention has at least two partial areas or surfaces, which extend around the central axis of the roll and consist of an ink-friendly material, wherein at least one circular partial area or a circular surface, which consists of an ink-repellent material, is arranged between the two circular partial areas or surfaces made of an ink-friendly material. The terms “circular partial area” or “circular surface” are defined in the sense of the present invention as an area of a surface of a roll that extends fully or partially around the circumference of the roll. A circular surface may have, for example, an annular design or have one or more ring segments, the surface being advantageously designed corresponding to the surface of the roll and being preferably arranged around the central axis of the roll and especially advantageously having approximately the same curvature as the curvature of the adjacent roll surface. Thus, according to one embodiment, a first circular surface or an annular element made of an ink-friendly material, an annular element adjoining same and made of an ink-repellent material, and, adjoining the latter, a second annular element made of an ink-friendly material are arranged according to the present invention in the axial direction of a roll, as a result of which the two annular elements made of ink-friendly material are separated by the annular element made of an ink-repellent material.  
           [0012]    A material that is “ink-friendly” in the sense of the present invention shall have, for example, such physical and/or chemical properties that a roll coated with such a material can assume the function of an inking roll, i.e., it can absorb ink. An ink-friendly material preferably possesses hydrophobic properties. Correspondingly, a material that is “ink-repellent” in the sense of the present invention shall be a material that possesses such physical and/or chemical properties that the roll can assume the function of a damping roll, i.e., it can absorb water, in an area coated with an ink-repellent material. The ink-repellent material shall preferably possess hydrophilic properties or be hydrophilic.  
           [0013]    A ceramic, copper, polyamide or Rilsan (R) is preferably used as the ink-friendly or hydrophobic material.  
           [0014]    Various ink-friendly and ink-repellent materials are known in the state of the art. Reference is made as an example to the teachings of EP 0 203 342 A2 and DE 196 53 911 A1 (corresponding to U.S. Pat. No. 5,957,052). The disclosure of each of EP 0 203 342 A2; DE 196 53 911 A1; and U.S. Pat. No. 5,957,052 are hereby incorporated by reference in their entirety, particularly concerning the materials for coating roll surfaces is incorporated in this application.  
           [0015]    A plurality of areas or circular surfaces made of ink-friendly material are advantageously arranged one after another in the axial direction in a roll according to the present invention, and at least one area or a circular surface each, made of an ink-repellent or hydrophilic material, is arranged between those said areas or surfaces. For example, four ink-friendly partial areas, which are separated from one another by three partial areas made of hydrophilic or ink-repellent material, may be provided one after another in the axial direction in a roll according to one exemplary embodiment.  
           [0016]    The thickness of the ink-friendly material is preferably in a range of 0.1 mm to 0.5 mm and especially preferably 0.3 mm. The thickness of the ink-repellent or hydrophilic material is advantageously in the range of 0.01 mm to 0.10 mm, more preferably in the range of 0.02 mm to 0.05 mm and advantageously 0.035 mm.  
           [0017]    The width of a circular surface or a partial area made of ink-friendly material is preferably approximately the width of a printing area and is advantageously in the range of 25 cm to 35 cm. The width of the partial area made of hydrophilic material is preferably somewhat greater than the stroke of a distribution roll and is advantageously in the range of 18 mm to 26 mm and advantageously equals 22 mm.  
           [0018]    According to another aspect, the present invention pertains to an inking and/or damping system for offset printing presses with at least one roll as described above.  
           [0019]    According to another aspect, the present invention pertains to a process for manufacturing a roll as described above, wherein at least two annular or ring segment-shaped structures made of an ink-friendly material and, between them, at least one annular structure made of an ink-repellent material in the surface area or directly on the surface of the roll are formed, i.e., for example, exposed, arranged or coated on a blank roll body.  
           [0020]    The roll according to the present invention is advantageously manufactured by premachining a blank roll body or tube by turning in order to obtain a surface with a designed surface quality. According to one embodiment, one or more partial areas made of an ink-friendly and ink-repellent material may already be provided in the blank roll body. It is also possible to apply an ink-friendly or ink-repellent material to the blank roll body in the desired areas. The application of an ink-friendly or ink-repellent material may be carried out, for example, by chrome-plating, facing or by a coating method, for example, plasma coating. An area at the transition between ink-friendly and ink-repellent materials or an edge area may be advantageously sealed in order to prevent, e.g., moisture from penetrating into the roll. After the application and/or exposure and/or finishing of the materials made of ink-friendly and/or ink-repellent material, finishing of the roll thus manufactured may be performed by turning or polishing in order to obtain a roll that can be used, for example, in an inking or damping system of a printing press.  
           [0021]    The present invention will be described below on the basis of preferred exemplary embodiments. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which the preferred embodiments of the invention are illustrated.  
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a schematic sectional view of a partial area of a roll according to the present invention;  
         [0023]    [0023]FIG. 2 is a first exemplary embodiment of a process according to the present invention for manufacturing a roll;  
         [0024]    [0024]FIG. 3 is a second exemplary embodiment of a process according to the present invention for manufacturing a roll; and  
         [0025]    [0025]FIG. 4 is a roll diagram for the explanation of the use of a roll according to the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    [0026]FIG. 1 shows in a sectional view a partial area of a roll according to the present invention, the design of the roll being shown from the central axis toward the surface. The roll shown as an example is divided into four sections having the width Y, assigned to the zones A through D, which have approximately equal width each and approximately correspond to a printing area. An ink-friendly or hydrophobic material  25 ,  33 , for example, ceramic, copper, polyamide or Rilsan (R), is applied with a layer thickness of approx. 0.3 mm to the surface in the zones A through D. Ink-repellent or hydrophilic material  23 ,  24 , chromium in the exemplary embodiment, is applied with a layer thickness of approx. 0.02 mm to 0.05 mm and a width of approx. 20 mm to 24 mm on the surface between the areas with ink-friendly material. The surface of the roll according to the present invention is consequently designed to be such that an ink-friendly material, which is associated with the printing area, and a hydrophilic material, which is located between two adjacent ink-friendly materials, are arranged alternatingly over the surface, which corresponds more or less to a paper width B for the printing.  
         [0027]    A damping agent distribution roll provided with such a surface, which is moved to and fro in the axial direction with a stroke of, e.g., 20 mm during use in printing, ensures, on the one hand, that the transfer of an ink is possible due to the ink-friendly material associated with the printing area, and, on the other hand, it prevents inks that run next to one another in adjacent zones from being able to be mixed together due to the ink-repellent or hydrophilic material located between the areas made of ink-friendly material. The surface area made of hydrophilic material ensures the sufficient supply and drainage of water during the operation and can thus remove an ink flowing beyond the edge of a zone or a printing area and thus prevent this ink from running into an adjacent zone or an adjacent printing area.  
         [0028]    [0028]FIG. 2 shows a first embodiment of a process according to the present invention for manufacturing a roll according to the present invention. In the initial state designated by  1 , there is a blank roll body or tube  20 , which is premachined by turning such that four circular depressions  21  are produced. A circular projection  22  each is located between two depressions  21  each.  
         [0029]    Each circular projection  22  is chrome-plated in step  2  and a layer of chromium  23  is thus applied.  
         [0030]    Next, a weld seam  24  is applied at the transitions designated by  24  between the chromium  23  applied and the blank roll body  20  in order to produce a waterproof sealing at the edge of the chromium layer  23 . The weld seam  24  may be preferably applied in order to guarantee better adhesion of the ink-friendly or hydrophobic coating  25  to be applied in step  4 .  
         [0031]    For example, a polyamide may be applied as an ink-friendly layer  25 . It is possible to carry out plasma coating in order to prepare the ink-friendly coating  25 . Hard chrome plating may be performed as well. Rilsan is advantageously applied as an ink-friendly material  25  to the roll  20 . The ink-friendly layer may be applied either as a single layer or in a plurality of layers—three layers in the exemplary embodiment—to the roll  20 .  
         [0032]    As is shown in step  5 , the roll  20  manufactured in the processing steps  1  through  4  may be finally polished or turned in order to obtain an essentially flat surface with circular ink-friendly partial areas  25 , which are interrupted or separated from each other by circular ink-repellent or hydrophilic partial areas  23 .  
         [0033]    [0033]FIG. 3 shows process steps for carrying out a second process according to the present invention for manufacturing the roll according to the present invention.  
         [0034]    In step  1 , a blank roll body  30  is machined by turning on the surface indicated by the arrow in order to make the surface of the blank roll body  30  more planar for the subsequent manufacturing processes. A depression  31  running around the central axis of the blank roll body  30  is subsequently prepared in step  2  by cropping or another material-removing process. As is shown in step  3 , a material  32  is subsequently introduced into the depression  31  prepared in step  2  by facing with a stainless material. As is shown in step  4 , the surface of the blank roll body prepared in steps  1  through  3  is brought to a desired shape by preturning, and the outer surface of the material  32  applied in-step  3  is made planar, and the width of this material  32  is reduced to the desired width.  
         [0035]    An ink-friendly material  33 , for example, Rilsan (R), is applied in the next step  5  to the surface areas of the blank roll body  30 , which adjoin the projecting area of the material  32 . As is described in connection with FIG. 2, one or more layers of the ink-friendly material  33  may be applied. The outer surface of the material  32  embedded between the ink-friendly material  33  is hard chrome-plated in step  6  in order to apply an ink-repellent chromium layer, and the blank roll body  30  processed in steps  1  through  6  is polished in step  7  in order to obtain an essentially planar outer surface.  
         [0036]    Even though exemplary embodiments for manufacturing rolls or roll surfaces with four and two partial areas made of an ink-friendly material are shown in FIGS. 2 and 3, these processes can be used to prepare any desired number of coatings with ink-friendly and ink-repellent surfaces on rollers.  
         [0037]    While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.