Ink scraper

Abstract: The feature of this invention is as follows. The ink feeder is equipped with an ink scraper comprising scraped ink separators (214) arranged parallel in the axial direction of the scraping doctor support device (218). Each of the scraped ink separators comprises an ink guide plate for guiding the ink scraped from the surface of the doctor roller (7), provided at the bottom, and color mixture preventive walls for preventing mixture of adjacent inks, provided on both sides of the guide plate. Therefore dull color due to mixture of inks of different colors is prevented and the quality of printed matters is improved.

Description: BACKGROUND OF THE INVENTION: Field of the Invention: The present invention relates to an ink scraper which is most suitable for use in an offset rotary press. Description of the Prior Art: Fig. 7 is a partial side view showing the structure of one color part of an offset rotary press in the prior art which makes a printing using a so called keyless ink feeder. As shown in Fig. 7; there is disposed an inkfountain roller 1 which is driven by a motor which is able to make a speed control independent of a main body of the printing machine so as to rotate at a speed which is lowerthan that of the main body of the printing machine so that ink can be transferred, and ink of a constant film thickness is fed onto. an outer circumferential surface of the inkfountain roller 1 from an inkfeed blade 12 portion which is disposed along the axial direction (widthwise direction) of the ink fountain roller 1 or the cross machine direction. Also, there is maintained a gap of a predetermined distance between the ink feed blade 12 and the surface of the ink fountain roller 1 while the printing is being made. In the prior art ink feed blade 12 as used in such for a high consistency fluid, there is no such ink feed blade as sectioned in the widthwise direction of the ink fountain roller 1 and color change in the widthwise direction of the ink fou ntain roller 1 cannot be effected. So, an ink feed blade 12 in which a plurality of ink tanks 2 are provided in the widthwise direction of the ink fountain roller 1 so as to be sectioned each to feed ink uniformly in the widthwise direction onto the inkfountain roller 1 has been disclosed. In Fig. 7, there is disposed an ink transfer roller 3 which is driven to rotate at a same speed as that of the main body of the printing machine, and the ink transfer roller 3 and the ink fountain roller 1 which is fed with ink are urged to each other so that, while a slippage between both rollers is being effected at a nip portion thereof, a slip metering is taken place and the ink is transferred onto the ink transfer roller 3. Then, the ink is fed from the ink transfer roller 3 to a roller group 4 which consists of a plurality of rollers and is further fed onto a printing plate 6 which is attached to an outer circumferential surface of a plate cylinder 45 via a form roller 5 in the roller group 4. In case of an offset printing, the printing plate 6 is also fed with a damping water from a damping device 29 in addition to the ink fed as mentioned above. The ink as so fed onto the printing plate 6 via the ink fountain roller 1, the ink transfer roller 3 and the roller group 4 is fed with a constant film thickness in the cross machine direction and is further transferred from the printing plate 6 to a blanket cylinder 46, so that printing is made on a paper running between the blanket cylinder 46 and another blanket cylinder 46 disposed opposingly thereto. At a portion where no printing is made, that is, at a portion where no ink is fed onto the printing plate 6 from the form roller 5, therefore, although the ink of a constant film thickness is fed, that ink is not consumed and the ink film thickness corresponding to that portion on the outer circumferential surfaces of the roller group 4 etc. becomes thicker. So, a scraping doctor 8 is caused to abut on a doctor roller 7 disposed in the roller group 4 and by use of this scraping doctor 8, the ink at the portion of the roller group 4 where the film thickness becomes thicker is scraped so that the ink is consumed uniformly in the entire widthwise direction of the roller group 4, thus even if ink is fed constantly in the widthwise direction of the roller group 4, it is consumed in a good balance, and even though there occurs a differential ink consummation locally during the printing, a uniform ink film thickness is maintained in the cross machine direction. In such keyless inking in which ink is fed without use of an ink quantity regulating mechanism divided into small sections in the cross machine direction, it has been a large problem how high consistency ink can be used for obtaining a high quality printed matter. In order to dissolve this problem, an apparatus for realizing a high quality printing is disclosed by the Japanese utility model application No. Hei 2(1990)-8147 titled "Ink receiving tank for keyless inking appaxatus". In said apparatus, as illustrated in Fig. 7, a shaft 9 fitted with a spirally formed plate (hereinafter referred to as "a vane wheel 9") is disposed at a bottom portion of the ink tank 2, and by use of this vane wheel 9, ink is fed to an opening portion of an ink suction pipe 44 of an ink pump 10 disposed at the bottom portion of the ink tank 2. It is to be noted that the ink received in the ink tank 2 contains water, which had been fed from the damping device 29 onto the printing plate 6, either transmitted on the surfaces of the roller group 4 etc. or scraped in a form of mixture in the ink and the vane wheel 9 has at a same time a function to agitate the water mixed in the ink in the ink tank 2 for homogenization. In Figs. 8 and 9, a schematic structure of an ink scraping doctor portion in an offset rotary press is shown. In the figures, numeral 3 designates an ink transfer roller, numeral 7 designates a doctor roller, numeral 8 designates a scraping doctor abutting on an outer circumference of the doctor roller 7 and numeral 218 designates a scraping doctor support device for supporting the scraping doctor 8. In said offset rotary press shown in Figs. 7 to 9. ink 2a. injected onto an ink fountain roller 1 which is driven by a speed control motor (not shown) to rotate at a slightly lower speed than that of the main body of the printing machine, is regulated to a predetermined film thickness via a gap at a tip of an ink feed blade 12 portion. Then, the ink 2a is fed, through a nip portion formed between the ink feed blade 12 and an ink fountain roller 1 which is driven to rotate at a same speed as that of the main body of the printing machine, downstream to the ink transfer roller 3 and to an inking roller group 4 for receiving the ink 2a to further feed it to a printing plate 6 via a form roller 5. It is to be noted that a residual ink on a surface of the ink fountain roller 1 is transferred rotationally to be scraped by a scraper 334 fitted right below of an ink feed nozzle 511. The residual ink scraped by the scraper 334 and the ink feed blade 12 falls down to be recovered in an ink tank 2. In the offset press generally, a damping water is fed onto the printing plate 6 from a damping device. The ink 2a, transferred in a uniform quantity in the cross machine direction, is further fed from the printing plate 6 attached around the plate cylinder 45 onto a blanket cylinder 46 so that a printing is made on a paper which is running in contact with the blanket cylinder 46. Thus, at a portion where no printing is made, the ink 2a is neither consumed nor the ink film thickness becomes thinner. As a method for stabilizing such an irregular film thickness of ink 2a, there is disclosed a method wherein the ink 2a is scraped by a scraping doctor 8 abutting on a doctor roller 7 disposed in a midway of an inking roller group so that the ink 2a is recovered throughout in the cross machine direction and even if the ink is fed uniformly in the cross machine direction, the ink is consumed in a good balance. While a color printing in which different colors are arranged in the cross machine direction is made, the inkfeeder 100 is so constructed that the rollerwidthwise direction is sectioned in a plural number (2 to 4, for example) and ink 2a of a different color is fed for each sheet of paper. It is to be noted that the gap between the ink feed blade 12 and the surface of the ink fountain roller 1 is setto a predetermined distance while the printing is being done. On the other hand, as shown in Figs. 8 and 9, as the scraping doctor 8 is formed in one unit extending throughout in the axial direction of the doctor roller 7, it functions well when the ink for each sheet of paper is same in the cross machine direction but if the ink 2a is different for each sheet in the widthwise direction of the roller, the ink of adjacent different colors is mixed with each other and collected in a contaminated state. So, in the ink scraping device shown in Figs. 8 and 9, there are problems to be solved as follows: In the offset press, printing of plural sheets, 4 sheets for example, is sometimes done at one time by use of one set of the blanket cylinders wherein colors of ink are different from each other. In the prior art, as shown in Figs. 8 and 9, as a scraping means of the ink 2a, after used for the printing, remaining on the surfaces of the inking roller group, there has been employed such means as scrapes and recovers the ink 2a by use of a single scraping doctor 8 which extends throughout in the axial direction (widthwise direction) of the inking rollers so as to abut on the doctor roller 7. For this reason, in such a prior art, there is a problem that an adjacent color of ink may mix with other colors on the printing plate side so as to cause a dull color and an aesthetic quality of the printing is damaged furiously. Although there Is disclosed a means for storing the scraped ink in order not to cause such a dull color, as the ink so scraped all through the operation is stored In such means, there has been a need to enlarge the ink tank or to replace the ink frequently or to abandon it. SUMMARY OF THE INVENTION: In view of the problems in the prior art as mentioned above, an object of the present invention is to provide an ink scraper for a printing machine for making a printing of plural colors in a widthwise direction of paper which is able to prevent a dull color due to mixing of different colors so as to enhance a quality of printed matters and to improve efficiency of an ink change work. In orderto attain said object, the present invention has features of construction as defined in claim 1. In the invention, an ink scraper for a printing machine having plural colors of ink fed in an axial direction of an inking roller is constructed such that a scraping ink separator having an ink leading plate at its bottom portion for leading ink scraped from a surface of a doctor roller by a scraping doctor and having a color mixing prevention wall fixed to each side of said ink leading plate so as to rise perpendicularly therefrom for preventing mixing of adjacent ink, is arrayed in an axial direction of a scraping doctor supporting device for supporting said scraping doctor, wherein said scraped ink separator is detachably fittable to said scraping doctor supporting device. According to the invention, the surplus ink sticking on the outer circumferential surface of the doctor roller is scraped by the scraping doctor to flow into each of the scraped ink separators and is separated to each color of ink by the color mixing prevention wall on each side of the scraped ink separator. Also, the scraped ink separator can be made of a thin plate for weight alleviation and the ink leading plate of said separator is made so as to form plural faces, thereby rigidity can be increased as compared to that of a single face. Further, the color mixing prevention wall of said separator is fixed perpendicularly to the ink leading plate, which contributes in increasing rigidity of said separator in addition to the function of ink color mixing prevention as mentioned above. Thus, a sufficient rigidity is obtained with alleviated weight and handling thereof becomes easier. A preferred embodiment is constructed such that said scraped ink separator is disposed so that a flow-out port of scraped ink provided at a lower portion of said scraped ink separator positions above the ink tank. According to this embodiment, the separated ink is recovered in the ink tank disposed below the flow-out port of said each separator. Thus, the ink can be separated and recovered for each of sheets of paper to be printed in different colors, thereby mixing of ink is avoided and loss of ink is reduced. A further preferred embodiment is constructed such that said ink scraper comprises a clamp device for positioning said scraped ink separator on said scraping doctor supporting device. According to this further embodiment, attachment and detachment of the scraped ink separator relative to the scraping doctor supporting device is done easily by a lever operation of the clamp device, thereby color change of ink is done quickly and cleaning work of the sticking ink is done easily. According to the invention, plural colors of ink are transferred and fed in the axial direction of the ink fountain roller, when a printing in plural different colors of ink is applied to plural sheets of paper in the cross machine direction, but even in that case, a surplus ink of each color can be separated to be recovered and mixing of adjacent different colors of ink to cause a contamination of ink can be prevented. Thereby, enhancement of printing quality and maintenance thereof become possible and the scraped ink can be recovered in an ink tank corresponding to each color, loss of ink becomes less and the ink can be reused efficiently. In addition thereto, attachment and detachment of the scraped ink separator are done easily, thus color change of ink for each sheet of paper in the cross machine direction can be done quickly and shortening of set-up time becomes possible. BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 is a schematic outside perspective view of an ink recovery portion in an offset press comprising a scraped ink separator of an embodiment according to the present invention. Fig. 2 is an outside perspective view showing structure of the scraped ink separator of the embodiment. Fig. 3 is a structural view showing a fitting mode of the scraped ink separator. Fig. 4 is an explanatory front view on a method of attachment and detachment of the scraped ink separator. Fig. 5 is a view taken in arrow Z direction of Fig. 4. Fig. 6 is an explanatory view showing structural examples of an ink leading portion of a tip of the scraped ink separator. Fig. 7 is a partial side view showing structure of an offset rotary press in the prior art. Fig. 8 is a front view of a prior art ink scraping doctor portion. Fig. 9 is a sideview of a prior art ink scraping doctor portion. DESCRIPTIONS OF THE PREFERRED EMBODIMENTS: Herebelow, description is made concretely on embodiments of an ink scraper of a printing machine according to the present invention with reference to accompanying figures. Fig. 1 is a schematic outside perspective view of an ink recovery portion in an offset press comprising a scraped ink separator of an embodiment according to the present invention, Fig. 2 is an outside perspective view showing structure of the scraped ink separator, Fig. 3 is a structural view showing a fitting mode of the scraped ink separator, Figs. 4 and 5 are explanatory views on a method of attachment and detachment of the scraped ink separator and Fig. 6 is an explanatory view showing structural examples of an ink leading portion of a tip of the scraped ink separator. In the printing machine according to the present embodiment which is constructed, as shown in Figs. 1 to 3, such that ink 2a from an ink tank 2 (2', 2") of ink feeders disposed arrayedly in the cross machine direction is fed to an ink feed pipe 11 via an ink pump 10 and to an ink fountain roller 1 via an ink feed nozzle 511 and further to a blanket cylinder (not shown) via an ink transfer roller 3 and an inking roller group and a predetermined printing is applied to a paper 210 to which the ink 2a is transferred from the blanket cylinder, an ink scraping doctor 8 portion is so improved that irregularity of film thickness of the ink remaining after consumed for the printing, that is, the ink having an image history sticking on a circumferential surface of a doctor roller 7, is made uniform so as to stabilize a sticking state of the ink which is being fed successively, and the construction is so made that the printing is applied to plural sheets of paper at one time in the cross machine direction and moreover mixing of ink can be prevented in case colors of ink of adjacent sheets are different from each other. Herebelow, description is made in detail. In Figs. 1 to 3, numeral 2 (2', 2") designates an ink tank, numeral 10 (10', 10") designates an ink pump, numeral 11 (11', 11") designates an ink feed pipe, numeral 511 designates an ink feed nozzle, numeral 1 designates an ink fountain roller, numeral 3 designates an ink transfer roller, numeral 4 designates an inking roller group, numeral 100 (100', 100") designates an ink feeder, numeral 45 designates a plate cylinder, numeral 6 designates a printing plate wound around the plate cylinder 45, numeral 12 designates an ink feed blade disposed opposingly to an outer circumferential surface of the ink fountain roller 1, numeral 230 designates a scraper and numeral 231 designates a damping device. The printing machine comprising devices shown in Figs. 1 to 3 is of a type applying a printing to four sheets (or two sheets) at one time, using two different colors of ink 2a, one for two sheets (pages 1 and 2) on the left hand side of Fig. 1 and one for two sheets (pages 3 and 4) on the right hand side of same. In the ink feeder 100, there are provided an ink feeder 100a for feeding ink 2a to the left hand side of Fig. 1 and an ink feeder 100b for feeding ink 2a' to the right hand side of same in a different color from that fed to the left hand side. It is to be noted that if all the adjacent colors of ink are different from each other, four sets of the ink feeder are arrayed in the cross machine direction. In Figs. 1 and 2, numeral 214 designates a scraped ink separator, provided in two sets in the axial direction of rollers or In the cross machine direction, abutting on the doctor roller 7. The scraped ink separator 214 comprises an ink leading plate 215 having a color mixing prevention wall216 fixed to each end thereof. The scraped ink separator 214 is disposed near the scraping doctor 8 so as to cover the scraping doctor 8. A front end of the color mixing prevention wall 216 is cut out in an arcuate form which is concentric with the doctor roller 7 so as to connect to a tip of a scraping doctor supporting device 218 and to stand closely to an outer circumference of the doctor roller 7, as shown in Fig. 5. The scraped ink separator 214 is constructed, as shown in Figs. 1 and 5, such that a flow-out port of the ink flowing on the ink leading plate 215 is positioned above the ink tank (ink tank 2', for example) corresponding to that scraped ink separator 214, thereby the scraped ink 2a can be led smoothly. Also, the scraped ink separator 214 is constructed, as shown in Figs. 4 and 5, to be detachable relative to the scraping doctor supporting device 218 via a bolt 71. That is, in Fig. 1 and in Figs. 4 and 5, the scraped ink separator 214 is provided insertedly between clamp devices 219,219 fixed to the scraping doctor supporting device 218 and is positioned in the rightward and leftward direction and in the upward and downward direction by a fitting plate 220 connected to the ink leading plate 215 being caused to abut on a patch 221 at its both side ends and lower end. The clamp device 219 is constructed such that an eccentric cam 223 is supported by bearing on a bracket 222 fixed to the patch 221, a lever 224 fitted to an outer peripheral surface of the eccentric cam 223 is turned so that the eccentric cam 223 is rotated, thereby a radial directional dimension is changed and fixing and releasing of the scraped ink separator 214 are changed. By use of the clamp device 219 as so constructed, it becomes possible that the fitting plate 220 is pressed to be fixed to the scraping doctor supporting device 218 by the eccentric cam 223 connected to the lever 224 of the clamp device 219. Figs. 6(A) to (C) show shapes of a side end portion of the scraping doctor 8 of the ink leading plate 215 of the scraped ink separator 214. In Figs. 6(A), a thin plate spring 226 as a leading member of the scraped ink is fitted to a tip portion of the ink leading plate 215 by a machine screw 225 between a front end of the ink leading plate 215 and an outer circumferential surface of the doctor roller 7. In this case, as a tip of the plate spring 226 can be approached sufficiently to atip of the scraping doctor 8 by the effect of a spring force of the thin plate spring 226, there is less residual ink on the scraping doctor supporting device 218 when the scraped ink separator 214 is detached for color change of ink and cleaning thereof becomes facilitated. In Fig. 6(B), a front end of the ink leading plate 215 is tapered to form an acute angle and is positioned abuttingly on the tip of the scraping doctor supporting device 218. In this case, structure of the scraped ink separator 214 becomes simplified, there is relatively less residual ink on the scraping doctor supporting device 21 8 at the time of color change and cleaning thereof becomes facilitated. In Fig. 6(C), there is formed a cut out portion on the scraping doctor supporting device 218 so as to correspond to a plate thickness of the ink leading plate 215 and the scraped ink separator 214 is fitted there. In this case, when the ink 2a scraped from the outer circumferential surface of the doctor roller 7 is to be led to the ink leading plate 215, it can be avoided that the scraped ink 2a is prevented from flowing due to deformation of the ink separator 214, as the ink separator 214 is of a thin plate structure having less rigidity in the plate thickness direction. In the printing machine comprising the scraped ink separator as so constructed as above, the scraping doctor 8 is mounted at a predetermined position and the tip of the scraped ink separator 214 fixed to the scraping doctor supporting device 218 is caused to engage with the surface of the scraping doctor supporting device 218. Thereby, a surplus ink 2a, 2a' sticking on the outer circumferential surface of the doctor roller 7 is scraped by the scraping doctor 8 to flow into the scraped ink separator 214 with an ink color boundary portion being separated to each color by the color mixing prevention wall 216 provided on each side of the scraped ink separator 214 and flows down on the ink leading plate 215. The ink 2a, 2a' so scraped from the surface of the doctor roller 7 is, as shown in Fig. 3, recovered in the inktank 2 without being mixed with the adjacent ink. Also, by use of the clamp device 219 as shown in Figs. 4 and 5, the scraped ink separator 214 can be positioned accurately in the upward and downward direction and in the rightward and leftward direction only by the scraped ink separator 214 being caused to abut on the patch 221 and can be fixed securely only by the lever 224 being shifted up and down and detachment thereof also can be done easily. Also, by the functions mentioned above, when color change is to be done frequently due to object to be printed, time needed for color change and for resetting can be shortened and, in addition thereto, as the cleaning work of the scraped ink can be done apart from the main body of the printing machine and productivity can be enhanced greatly. By providing such scraped ink separator 214 and ancillary devices as mentioned above, mixing of adjacent different colors of ink in the cross machine direction can be prevented and the ink so scraped can be recovered efficiently into a corresponding ink tank 2. It is to be noted that the scraped ink separator 214 may be made of various materials, such as a thin steel plate, an aluminum plate, plastics, etc., thereby the devices can be alleviated in weight and workability in the attachment and detachment thereof can be enhanced. INDUSTRIAL APPLICABILITY: The present invention relates to an ink scraper for scraping residual ink sticking on an outer circumference of each inking roller, and said ink feeder and ink scraper are applicable generally to rotary type printing machines including but not limited to an offset rotary press.

Claims: An ink scraper for a printing machine in which plural colors of ink can be fed in an axial direction of an inking roller, characterized in that a scraped ink separator (214) having an ink leading plate (215) at its bottom portion for leading ink scraped from a surface of a doctor roller (7) by a scraping doctor (8) and having a color mixing prevention wall (216) fixed to each side of said ink leading plate (215) so as to rise perpendicularly therefrom for preventing mixing of adjacent ink, is arrayed in an axial direction of a scraping doctor supporting device (218) for supporting said scraping doctor (8), wherein said scraped ink separator (214) is detachably fittable to said scraping doctor supporting device (218). An ink scraper as claimed in claim 1, characterized in that said scraped ink separator (214) is disposed so that a flow-out port of a scraped ink provided at a lower portion of said scraped ink separator (214) positions above an ink tank (2) . An ink scraper as claimed in claim 1 or 2, characterized in that said ink scraper comprises a clamp device (219) for positioning said scraped ink separator (214) on said scraping doctor supporting device (218).

Inventors: HAMAOKA YUKIO, MITA KOJI, MIYAKE MITSUNAO, OYAMA YOSHIHIRO, HAMAOKA, YUKIO, MITA, KOJI, MIYAKE, MITSUNAO, OYAMA, YOSHIHIRO
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI JUKOGYO KABUSHIKI KAISHA
Application year: 1997
Main classification: B41F31
IPC codes: B41F31