US3885496A

US3885496A - Device for applying ink to the inking roller of an offset printing press

Info

Publication number: US3885496A
Application number: US390520A
Authority: US
Inventors: Peter Breitweg; Karl-Heinz Franz; Peter Mayer; Klaus Wolf
Original assignee: Roland Offsetmaschinenfabrik Faber and Schleicher AG
Current assignee: Roland Offsetmaschinenfabrik Faber and Schleicher AG
Priority date: 1972-08-22
Filing date: 1973-08-22
Publication date: 1975-05-27
Anticipated expiration: 1992-05-27
Also published as: FR2196911A1; GB1440993A; FR2196911B3; DE2241281B2; DE2241281A1

Abstract

An inking device for supplying a film of ink to a printing cylinder in a printing press which includes a housing having a plurality of cup-like discs journaled side by side therein. Structure is provided for continuously feeding ink to the discs and for rotating the discs at high speed so that the ink is slung radially outward by centrifugal force in a finely divided stream through a registering aperture. To control the rate of flow a shutter is movably interposed in the stream. A sump is provided at the bottom of the housing with feeding apparatus including a pump and ink feed line for pumping ink to each of the discs. Alternatively, a feed screw is provided extending from the sump to each of the discs for feeding ink directly to the center of the disc. A scraper apparatus is provided at the periphery of the disc for intercepting the major portion of the ink, thereby to control the amount of ink which is actively discharged in the stream and to maintain the remainder in liquid form. Finally, a heater is used to heat the walls within the device upon which the ink tends to collect so that the viscosity of the ink is reduced for prompt return to the sump.

Description

United States Patent Breitweg et al.

[451 May 27, 1975 1 1 DEVICE FOR APPLYING INK TO THE lNKlNG ROLLER OF AN OFFSET PRINTING PRESS [75] Inventors: Peter Breitweg,

Offenbach-Rumpenheim; Karl-Heinz Franz, Hanau am Main; Peter Mayer, Muhlheim am Main; Klaus Wolf, Neu-lsenburg, all of Germany [73] Assignee: Roland Offsetmaschinenfabrik Faber & Schleicher, Germany [22] Filed: Aug. 22, 1973 [21] Appl. No.: 390,520

[30] Foreign Application Priority Data Aug. 22, 1972 Germany 2241281 [52] US. Cl. 101/363; 101/148; 101/366;

[56] References Cited UNITED STATES PATENTS 1,769,008 7/1930 Winkler 239/223 X 2,086,921 7/1937 Norris 239/218.5 2,624,356 1/1953 Rumbaugh 1 134/194 3,455,507 7/1969 Ryder et a1. 239/224 X 3,543,680 12/1970 Killen et a1. 101/363 X Primary Examiner-Clifford D. Crowder Attorney, Agent, or FirmWolfe, Hubbard, Leydig, Voit & Osann, Ltd.

[57] ABSTRACT An inking device for supplying a film of ink to a print ing cylinder in a printing press which includes a housing having a plurality of cup-like discs journaled side by side therein. Structure is provided for continuously feeding ink to the discs and for rotating the discs at high speed so that the ink is slung radially outward by centrifugal force in a finely dlivided stream through a registering aperture. To control the rate of flow a shutter is movably interposed in the stream. A sump is provided at the bottom of the housing with feeding apparatus including a pump and ink feed line for pumping ink to each of the discs. Alternatively, a feed screw is provided extending from the sump to each of the discs for feeding ink directly to the center of the disc.

A scraper apparatus is provided at the periphery of the disc for intercepting the major portion of the ink, thereby to control the amount of ink which is actively discharged in the stream and to maintain the remainder in liquid form. Finally, a heater is used to heat the walls within the device upon which the ink tends to collect so that the viscosity of the ink is reduced for prompt return to the sump.

5 Claims, 6 Drawing Figures FZJEHEL WW 3,8854% SHEET 3 DEVICE FOR APPLYING INK TO THE INKING ROLLER OF AN OFFSET PRINTING PRESS Perhaps no other portion of a printing press has received more attention over the years than the inking mechanism which converts the ink from the liquid or pastey state to a thin film suitable for application to a plate cylinder. The most commonly used means for accomplishing this is the fountain roller and cooperating fountain blade, with means for transferring at least a portion of the ink on the fountain roller to rollers, arranged in series, which transfer the ink to the plate cylinder. One of the problems in devices of this type is the adjustment of the ink flow to meet the requirements of theprinting plate on a regional or column by column basis. Thus effort has been directed to feeding of ink through nozzles arranged side by side in the column positions with individual control of flow. Such nozzles have been of two types, a first type in which the ink is fed directly to a cooperating cylinder through a narrow slit and a second type in which the ink is sprayed in finely divided form. However, in both it has been difficult to achieve precise control and the nozzles have been susceptible to clogging with lint and other contaminants in the ink.

It is, accordingly, an object of the present invention to provide an ink feed device which is capable of feeding ink in the form of a thin film reliably and at a precisely controlled rate in successive column positions. It is a related object to provide an ink feed device which is capable of consistent operation over long periods of time, which completely avoids the possibility of clogging or other irregularity by reason of contaminants in the ink, and which is capable of successful operation with inks having a wide range of viscosity including ink of thick, pastey consistency.

It is another object of the invention to provide an inking device which discharges ink in finely divided form for direct formation of a film upon a receptive ink, or form, roller and which produces the stream by centrifugal means thereby to avoid the difficulties which have been associated in the past with spray nozzles. Thus it is an object to provide an inking device in which ink is converted to a finely divided form at a high rate but in which only a small portion of the ink'is actually discharged in a finely divided stream, the remainder of the ink being constantly recirculated, in free-flowing liquid form, to a sump. It is an object to provide an inking device which is capable of forming a film having a wide range of thickness but which, unlike prior devices, may be easily adjusted to provide an extremely thin film.

It is an object, further, to provide an inking device having the above advantages but which is easily cleaned, for example, when changing color of ink.

It is yet another object of the invention to provide an inking device which is not only capable of operating consistently over long periods of time without care or maintenance but which is highly compact, simple, and inherently inexpensive, avoiding the complication and expense of the series of ink distribution rollers and drums required for smoothing out the ink film in conventional inking devices.

Other objects and advantages of the invention will become apparent upon reading the attached detailed description and upon reference to the drawings in which:

FIG. 1 is a vertical section taken through an inking device constructed in accordance with the present invention and looking along the line l-l in FIG. 2.

FIG. 2 is a longitudinal section taken along the vertical section line 2-2 in FIG. 1.

FIG. 3 is a view similar to FIG. 1 but showing use of scraper or doctor blades.

FIG. 4 is a fragmentary horizontal section taken along the line 44 in FIG. 3..

FIG. 5 shows a modified form of the device and is a vertical section looking along the line 5-5 in FIG. 6.

FIG. 6 is a fragmentary horizontal section looking along the line 6-6 in FIG. 5.

While the invention has been described in connection with certain preferred embodiments, it will be understood that we do not intend to be limited to the particular embodiments shown but intend, on the contrary, to cover the various alternative and equivalent constructions included within the spirit and scope of the appended claims.

Turning now to the drawings, and particularly FIGS. 1 and 2, there is shown an inking system including an inking device 10 constructed in accordance with the present invention cooperating with an ink roller, or form roller, 11 which is in rolling engagement with the plate on a plate cylinder 12. The plate may, for example, be of the lithographic type, and in such event it will be understood that means (not shown) will be provided for conveying to the plate a thin film of water in addi tion to the ink.

The inking device 10 includes a housing 15 which is spaced parallel with the ink roller 11, extending the length of the latter. The housing has a bottom plate 16 which forms a sump as well as a top plate 17 which serves both as a closure and as a mounting plate. In the side wall of the housing are a row of apertures 18 of limited size through which ink is projected upon the surface of the ink roller 11.

In accordance with the present invention a plurality of cup-like discs, horizontally arranged, are journaled side by side in the housing, with ink being continuously deposited on the discs and with the discs being rotated at high speed so that the deposited ink is slung radially outwardly by centrifugal force through registering apertures 18 to form a thin film of ink upon the receptive surface of the ink roller 11. The discs and their associated parts form separate, identical subassemblies. One such subassembly, 20, will be discussed in detail and it will be understood that similar parts, to which the same reference numerals have been applied, exist in the adjacent subassemblies and perform the same function therein.

Taking the subassembly of FIG. 1, which corresponds to the left-hand subassembly in FIG. 2, as typical, a disc 21 is provided which is of shallow cup shape having a bottom wall 22, a conical side wall 23 and an annular lip 24. The disc is mounted upon an axially extending shaft 25 which is a journaled. in a bearing 26. At the upper end of the shaft is a pulley 27 engaged by a belt 28 which is driven by a motor 29.

For the purpose of feeding ink 30 continuously from the sump 16 to the disc, a feeding means is provided which includes a pump 31 which discharges into a feed line 32, which feed line terminates at 33 at a point elevated slightly above the disc. The pump is preferably of the positive displacement type, for example, a gear pump. The pump is coupled to a drive motor 32. A suitable control 33 is provided for setting the driving speed and thereby directly controlling the output rate. By using a pump of the positive displacement type the amount of ink which is fed per revolution of the pump remains constant in spite of variations in the viscosity of the ink. Even inks of pastey consistency may be successfully fed in the sytem shown.

The disc 21 is rotated at a speed which is sufficient to develop a high centrifugal force so that the ink which is deposited upon the disc is slung from the edge of the disc as a stream of finely divided particles.

It is one of the features of the present invention that the major portion of the ink which is deposited upon the disc is discharged idly within the housing, promptly flowing back to the sump, and only a minor portion is discharged through the aperture 18 for depositing upon the surface of the ink roller 11. In accordance with one of the aspects of the present invention a shutter is adjustably interposed between the disc and the aperture 18 for controlling the rate of feed of ink through the aperture. In the present embodiment the shutter is in the form of a cylindrical shield 40 having an opening 41 which generally registers with the aperture 18 but having provision for bodily movement so as to vary the unobstructed area and hence vary the rate of deposition. In the present instance the shield 40 has an annular flange 42 and is mounted for rotational adjustment, permitting the opening 41 to be moved off-center with respect to the aperture 18 for control of the unobstructed area. When the shutter, or shield, 40 is rotationally adjustable it may be provided with an annular clearance slot 43 to clear the incoming ink feed line 32. Alternatively, the shield may be vertically adjustable to offset the opening 41 from aperture 18, in which case a vertically extending clearance slot is required.

To keep the ink in constant motion and thereby avoid coagulation, a series of stirring devices generally indicated at 45 may be used. These may be of the rotary type powered by any suitable driving means. Makeup may be supplied to the pump by any desired means.

In operation, then, and assuming the

openings

41, 18 are in general alinement, ink from the sump, metered by the pump 31 is fed through line 32 and discharged upon the disc 21. The disc 21 is rotated at high speed, a speed which, using a disc of 2-inch diameter, may be on the order of rpm., a speed which is, in any event, sufficiently high so that the centrifugal force acting upon the ink tends to sling it outwardly from the lip 24 in finely divided form. That portion of the ink which is projected through the opening is deposited upon the surface of ink roller 11 in the form of a thin and uniform film. Where it is desired to reduce the thickness of the film, the shutter, or shield, 40 is rotated about its axis to offset the opening 41 from aperture 18, that is, to reduce the unobstructed area. Most of the ink slung outwardly from the disc strikes the wall of the shield and, by action of gravity, returns promptly to the sump for recirculation.

While it is preferred to use an adjustable shield for controlling the output rate, it will be apparent to one skilled in the art that the output may be controlled with equal facility by changing the speed of the drive motor 32 which drives the pump using, for this purpose, any suitable electrical control assembly 33. In its simplest aspects the control assembly 33 may be a settable rheostat. However, it is preferred to employ a more sophisticated speed control which is capable of maintaining a preset but adjustable speed and having speed calibration to cover a wide range of output.

y In the above described embodiments all of the ink is discharged from the disc by centrifugal force. However, in accordance with one of the features of the present invention some of the ink may be mechanically re moved from the-disc by using a system of scrapers or doctor blades. Such doctor blades, shown in FIGS. 3 and 4, are cantilever-mounted in angled position, with the free, or inner, ends in wiping engagement with the lip of the disc. The blade assembly, indicated generally at 50, may include a plurality of convergently arranged blades 51-55 inclusive. Since such blades span most of the periphery of the disc, the ink which would normally reach the periphery of the disc in this region for centrifugal expulsion is, instead, stripped off for recirculation, and only that portion of the ink which is successful in reaching the lip of the disc within the free angular space 57 is ejected by centrifugal force in the form of a finely divided spray 56. This not only limits the total amount of ink which is ejected but inhibits accumulation at the lip and prevents the ink from being ejected in the form of large droplets. If desired, the doctor blade 51 may be mounted for swinging movement about the axis of the disc as a convenient way of varying the arc of centrifugal ejection and hence the rate of flow of ink through the aperture. Elements of the version shown in FIGS. 3 and 4 which are provided in common with the version shown in FIGS. 1 and 2 carry similar reference numerals with addition of subscript a. Thus, cylindrical shield 40a is provided having an opening 410, with the blades 51-55, as shown in FIG. 4, penetrating the wall of the shield.

In accordance with one of the detailed features of the construction, illustrated in FIG. 3, the cylindrical shield 40a, which surrounds the disc, is artifically heated by means of an encircling heating element H having an outer shell 58 which is, as shown in FIG. 4, also penetrated by the blades. This keeps the shield 40a at such a high temperature as to substantially reduce the viscosity of the ink which strikes the shield so that the impingeing ink flows more promptly to the sump, a typical stream of ink being indicated at 59 in FIG. 3. The shield structure is bodily rotatable on the flange 42a, similarly to the previous embodiment, with the rotation thereby serving to rotate the blades which are mounted in the shield.

In accordance with a still further aspect of the pres ent invention, ink may be conveyed from the sump to the center of each disc by means ofa vertically oriented feed screw, the lower end of which extends into the sump and the upper end of which extends through a clearance opening at the center of the disc, the feed screw being separately driven at a controlled speed in order to vary the feed rate. This is shown in FIGS. 5 and 6 where corresponding parts are indicated by corresponding reference numerals with addition of subscript b. In this version the disc 21b is open at the center and is mounted for driving upon a hollow shaft 25b driven by a pulley 27b about which is trained a driving belt 28b. The shaft 25b is supported in a bearing bracket 60. The bearing bracket is, in turn, supported upon an angle 15b which is employed in lieu of the long housing 15 in FIG. 1. Surrounding the disc is a shield 40b having an opening 41b which is aligned with the lip of the disc 21b and the adjacent surface of the ink roller 11b.

For the purpose of pumping ink to the disc 21b a vertically oriented feed screw 60 is used having a lower end 61 which extends down into the sump and an upper, flaring end 62 which extends through the center of the cup. To confine the ink about the screw a nozzle plate 63 is provided overlying the sump and which has a nozzle 64 which is telescoped over the screw and which defines an annular axially extending pumping space.

For rotating the feed screw at a settable speed, the screw has a shaft 65 which extends upwardly within the hollow shaft b and which terminates in a pulley 66 driven by a belt 67, the belt being powered by a motor 68 having any desired speed setting means 69. The rate of ink feed depends upon the motor speed and the control means 69 is preferably calibrated directly in terms of feed rate.

As an additional means for controlling output, the shield is provided with an adjustable shutter 70 which adjustably covers the opening 41b to determine the unobstructed area of the latter. Either the shutter 70 or the control device 69 for motor 68, or both of them together, may be used to control the rate of discharge of the finely divided stream and hence the thickness of the film formed upon the ink cylinder 11b.

In carrying out the invention the discs and their asso ciated apertures may be used to control the feed rate of ink in successive positions along the length of the ink roller and plate cylinder. However, the discs need not be provided column by column, and each disc may, indeed, because of the dispersal of ink illustrated in FIG. 4, service more than one column position. Thus the latter term is intended to refer to any convenient cycle of length along the ink roller and plate cylinder. The term disc is used to cover any circular inkdispersing element rotated at high speed.

It is found that the angular dispersal of the projected ink is sufficiently great so that the uniformity and continuity of the resulting film is not substantially affected by reasonable degrees of closure, or offset, of the ad justable opening 41 with respect to the aperture 18. However,.if desired, the aperture 18 instead of being a single opening may be formed as a spaced series of openings and the opening 41 in the shield may be similarly divided into openings of registering size and position. In such event the effect of closure will be more evenly distributed along the longitudinal dimension of the aperture 18 and a smaller amount of movement of the shield will suffice to adjust from the fully open to fully closed condition. The fine degree of output control achievable in the present construction is due, in part, to the fact that most of the ink from the disc is idly intercepted and returned to the sump, with only a small fraction being projected upon the roller surface.

It will, in any event, be appreciated by one skilled in the art that the present device is inherently capable of forming a film of ink directly, easily controllable over a wide range of film thickness, including thin films difficult to achieve by ordinary means. Since the film is formed by a stream of finely divided ink particles by centrifugal means there is no clogging tendency. Thus the device once adjusted, and with the discs rotating at a constant rate, can be expected to provide a uniform and consistent rate of discharge. and hence consistent film thickness, over long press runs without care or attention. The term means for variably acting upon the ink as used herein is a general term covering means for varying the effective ink flow either as liquid ink or when the ink is in its finely divided state. It is one of the features of the present construction that the particles in the stream are sufficiently widely dispersed so that an even film is formed by direct action of the particles without auxiliary smoothing. Accordingly, the film may be directly deposited upon a form roller which rolls in direct engagement with a plate cylinder, as in the case of the roller 11, without necessity for using a series of intervening ink rollers, or cylinders, for bringing about a smooth and even distribution of the film. Thus the present device possesses a high degree of economy and compactness. Nonetheless, if desired, auxiliary rollers or cylinders may be interposed between the ink roller 11 and the plate cylinder 12 without departing from the invention.

It is one of the further features of the construction that it is easily cleaned. In changing colors, for example, the ink may be drained from the sump and the sump may be charged with a solvent. Operating the pumps, or feed screws 60, at the full rate, and with the apertures 18 closed off, the solvent and entrained ink may be recirculated and then cleanly drained in readiness for a new charge of ink.

In the embodiment of the device illustrated in FIG. 2 the housing 15 will be understood to extend the fully length of the ink roller 11. However, the term housing is not necessarily limited to a unitary structure and includes the concept of using a series of individual enclosures for the respective discs, as in the versions illustrated in FIGS. 3-6. Each of the individual enclosures has its own sump and pumping means for pumping ink from the sump to the central portion of the associated disc. A plurality of such inking units may be assembled upon a longitudinally extending frame member in such number as to span the entire length of the adjacent ink roller. This not only permits the inventive structure to be accommodated to rollers of any length but permits quick and easy substitution for servicing purposes without necessity for removing the entire assembly.

We claim:

1. In an inking device for supplying a film of ink to a printing cylinder in a printing press comprising, in combination, an ink roller, a frame, a cup-like disc horizontally oriented and journaled in the frame, the disc having a peripheral lip, means for continuously depositing ink on the disc, means for rotating the disc at high speed so that the ink deposited thereon flows in a thin layer to the lip of the disc and is ejected radially outwardly therefrom by centrifugal force in a finely divided spray, a shield mounted on the frame and spaced outwardly from the disc to surround the same and having an opening at the bottom, the shield having an aperture adjacent the ink roller, and scraper blade means engaging the lip of the disc in the region remote from the aperture to prevent ejection of ink from the lip in the form of spray in the region of the scraper means while permitting ejection of ink spray in the region of the aperture and onto the surface of the ink roller.

2. The combination as claimed in claim 1 in which the scraper blade means is in the form of a plurality of spaced blades extending inwardly with respect to the shield with the tip portions of the blades being in constant scraping engagement with the lip.

3. The combination as claimed in claim 2 in which the blades are carried by the shield, penetrating the shield at peripherally spaced points and in which the blades bear a uniform direction of angle with respect to the lip, the shield and the blades carried thereby being bodily rotatable with respect to the frame about the axis of the disc.

4. The combination as claimed in claim 1 in which the shield is intimately surrounded by a heating element adjacent the scraper blade means so that the ink which is scraped off is maintained in a freely flowing liquid state for passage through the opening at the bottom of the shield.

5. In an inking device for supplying a film of ink to a printing cylinder in a printing press comprising, in combination, an ink roller, a frame, a cup-like disc horizontally oriented and journaled in the frame, the disc having a flat peripheral lip, means for continuously depositing ink on the disc, means for rotating the disc at high speed so that the ink deposited thereon flows in a thin layer to the lip of the disc and is ejected radially outwardly therefrom by centrifugal force in a finely divided spray, a cylindrical shield mounted on the frame and spaced outwardly from the disc to surround the same and having an opening at the bottom, the shield having an aperture adjacent the ink roller, a plurality of scraper blades mounted in intimate penetrating relation in the shield and convergently angled so that their tips flatly overlie the lip of the disc in the region remote from the aperture to prevent ejection of ink from the lip in the form of spray in the region of the scraper blades while permitting ejection of ink spray in the region of the aperture and onto the surface of the ink roller, the shield having a heating element closely surrounding the same in a position adjacent the blades for insuring that the ink scraped from the lip is in freely flowing liquid form for constant passage from the blades and along the side walls of the shield.