US3624731A

US3624731A - Printing apparatus and process for controlling ink fog

Info

Publication number: US3624731A
Application number: US842121A
Authority: US
Inventors: Eugene T Lindberg
Original assignee: Denver Post Inc
Current assignee: Denver Post Inc
Priority date: 1969-07-16
Filing date: 1969-07-16
Publication date: 1971-11-30
Anticipated expiration: 1988-11-30

Abstract

Ink fog is controlled or reduced by mixing with the ink finely divided particles of a magnetic material, such as iron oxide, and feeding the ink from the ink fountain to the impression cylinder by a series of rollers, at least some of which are magnetized, so as to attract ink-fog-containing magnetic particles. The magnetized rollers preferably include alternating north and south poles on the outside, as through the use of a series of magnetic rings having alternating poles on the outside, interspaced between unmagnetized discs, by electromagnetic coils wound to produce the alternating poles on spools formed of a core material, or by induced magnetism. In the latter instance, the outer layer of the roller may be formed of a magnetizable metal, or of rubber in which is embedded finely divided magnetic particles. The spacing of the permanent magnet discs may also be adjusted by sponge rubber discs interspaced therebetween.

Description

United States Patent 101/382 MU 252/6253 101/348 X Denver, FOREIGN PATENTS 1,142,671 9/1957 France 101/382 MU Primary Examiner-J. Reed Fisher CONTROLLING INK FOG Anorney-Van Valkenburg and Lowe 14 Claims, 11 Drawing Figs.

U.S. CL............-.--.U....-n.n"........................ f g i ee oned of reduFed In a B4 31/06 the mktincly divided particles of a magnetic material, such as [so] me. 101,349 iron oxide and feeding the ink from he ink founmin to the 5 c pression cylinder by a series of rollers, at least some of which 350, 351,352, 363, 364,206,207, 208,210,211, 426 353462 205 117/234 235 236 238 are magnetized, so as to attract ink-fog-cont alning magnetic 18/821 623 3 5 particles. The magnetized rollers preferably include altemating north and south poles on the outside, as through the use of Ram CM a series of magnetic rings having alternating poles on the outside, interspaced between unmagnetized discs, by electromag- UNITED STATES PATENTS netic coils wound to produce the alternating poles on spools formed of a core material, or by induced magnetism. 1n the latter instance, the outer layer of the roller may be formed of a magnetizable metal, or of rubber in which is embedded finely divided magnetic particles. The spacing of the permanent m.r m m mm m m HI "1"" L k m m 14. m e d k u e mn na o o BMRMMC 467890 666667 999999 111111 ///ll/ 207245 1 8649 34842 w 909089 272730 J 333333 m m I u 1, M a 1 mm mu T Jm er 0 mnnmaom nz v u M o .m EmMJNT r 0, de m Wwmm a .m AFPA 11.1] 2 253 7 2247 l. [[[1 [54] PRINTING APPARATUS AND PROCESS FOR magnet discs may also be adjusted by sponge rubber discs interspaced therebetween.

uwxxxu UU7 2l 2n2 81 68 3 H03 U w mm m 1 F1 "ea mr wk... aev ae un 0:0 0 me mmlu -l o MHJKSH 50 233 246666 999999 111111 [Ill/l 322237 111 PATENTEUNHV 30 I971 SHEET 1 BF 2 INVENTOR. Eugene T. Lindberg BY I/MAW r A TTOR/VE Y5 PRINTING APPARATUS AND PROCESS FOR CONTROLLING INK FOG This invention relates to printing. and more particularly to a method and apparatus for controlling ink fog produced by printing presses.

In the production of various printed media. particularly newspapers, the tendency has been to increase the speed of the presses. With increase of the press speed, however. the problem which has not been overcome and has become acute, despite better control of the amount of ink fed to the fountain or better design of rollers which transfer the ink from a supply fountain to a printing cylinder, is the problem of ink fog. The mist or fog of finely divided ink particles which emanates from high speed presses not only deposits upon surfaces of the press and elsewhere in the press room, but is also inhaled by the press men, resulting in lung infections or other lung diseases. It appears that the higher the press speed, the greater the amount of fog or mist produced. It is theorized that this ink fog is produced by the nipping action of the various rollers which transfer the ink from a supply fountain to a printing cylinder. As the rollers inked surfaces separate after contact, they pull out some of the ink into extremely fine threads which break up into a fog of particles. Floating in air, these particles spread out to be deposited on various surfaces, and also to be inhaled by men working in the press room. Although printers ink is usually a viscous fluid, the production of ink fog to an undesirable extent thus results not only in maintenance and cleaning problems, but also in a health hazard.

Attempts have been made to overcome the problems produced by ink fog through the use of charged housing parts or wires located as closely as possible to the inking rolls, in

order to attract articles of the ink fog or mist, due to an electrostatic charge imparted thereto or created thereon. However, such attempts have not been successful, since the voltage utilized is necessarily high, such as up to l00,000 volts, with a consequent serious danger of injuring or even electrocuting a workman in the press room.

Among the objects of this invention are to provide a novel method and apparatus for reducing or overcoming the problem of ink fog produced by printing presses; to provide such a method and apparatus which tends to eliminate or reduce the fog at the source thereof, i.e. at the rolls which supply ink from a fountain or the like to the printing cylinder; to provide such a method and apparatus which may be readily applied to the ink used in printing presses and the ink rolls of the printing presses; to provide such a method and apparatus which may have numerous variations; to provide such a method and apparatus which does not produce a health or accident hazard; to provide such a method and apparatus which requires a minimum of modification of the ink and of the rolls which transfer the ink from an ink fountain to a printing cylinder; and to provide such a method and apparatus which are each simple yet effective in use and operation.

The foregoing and additional objects, as well as the novel features of this invention, will become apparent from the description which follows, taken in conjunction with the accompanying drawings, in which:

FIG. .1 is a partly diagrammatic, isometric vertical section of a portion of a conventional printing press, including the ink fountain and the rolls which transfer the ink to the printing cylinder;

FIG. 2 is an isometric view, on an enlarged scale, of one of the rolls of FIG. 1, bearing thereon an indication of the location of magnetic poles and a representation of magnetic lines of force;

FIG. 3 is a plan view of one of a series of magnetized discs used in the roll of FIG. 2, bearing an indication of the magnetic poles thereof;

FIG. 4 is a similar view of an alternating disc having oppositely disposed poles;

FIG. 5 is a condensed side elevation of a roll which may be utilized in the press of FIG. 1, showing a series of magnets through which magnetic poles may be induced in the roll;

FIG. 6 is a condensed longitudinal section of a roll which may be used in the press of FIG. 1, having a series of electromagnets installed therewithin and illustrating one manner in which,electrical currentmay be supplied to the electromagnets;

FIG. 7 is a fragmentary, longitudinal section illustrating a roll including magnet discs in which the distance between the magnets is adjustable;

FIG. 8 is a fragmentary section similar to a portion of FIG. 7. illustrating the spacing adjustment of a pair of magnetic discs of the roll of FIG. 7, to produce a weaker magnetic field;

FIG. 9 is a similar fragmentary. longitudinal section illustrating the adjustment of the pair of magnetic discs, so as to be spaced closer together and produce a stronger magnetic field;

FIG. 10 is a condensed longitudinal section of a roll useful as a rubber-covered roll in the press of FIG. I; and

FIG. 11 is a fragmentary radial section showing a portion of the roll of FIG. 10 and a portion of a metal roll of larger diameter disposed thereabove.

In accordance with this invention, the ink used in printing, such as a newspaper, magazine or the like, is provided with very finely divided magnetic particles, as on the order of -300 to 600 screen size. The particles added to the ink are conveniently black magnetic iron oxide, of substantially the same size as the carbon black particles in the ink. Ideally. each micro particle of magnetic powder would be surrounded by a cluster of carbon particles, all suspended by the liquid ingredients of the ink. The magnetic particles, of course, being a part of the ink, should not affect the color of the ink, since they become part of the ink, after printing and drying. Thus, black magnetic iron oxide particles are useful in the ordinary black newsprint ink. For colored inks, the magnetic particles may be dye-coated to have colors other than black. in many cases, the colored ink itself will mask the particle it surrounds, regardless of the particles color.

In further accordance with this invention. one or more of the rollers by which the ink is transferred from the fountain to the printing cylinder, such as each roller or alternate rollers, if desired, are magnetized, e.g. provided with a magnetic field. so that the magnetic particles in the ink will be attracted to each magnetized roller, thereby reducing or eliminating the ink mist or fog.

As shown in FIG. I of the drawings, a conventional highspeed printing press includes a series of plates 10 mounted on a rotating plate cylinder or impression cylinder C, for printing on a continuous paper sheet 11, which is fed between the plate cylinder C and a blanket or impression cylinder 12. The ink, which is applied to the plates [0 for printing purposes, is supplied from a fountain F, the ink being fed thereto from an ink feed trough 13, of conventional construction, to maintain the level 14 of the ink at a desired height. An ink roller 15, which is partially submerged in the ink below level 14, is rotated by a conventional mechanism, not shown, by which the remainder of the rolls and drums, described below, are also rotated. The fountain roller 15 moves a layer ofink to a feed roller 16, also called a spiral roller because it normally is provided with a spiral groove, from which the ink is received by a transfer roller 17 which, in turn, carries the ink to a lower ink drum [8. The layer of ink of the lower ink drum 18 is smoothed and made more uniform by a pair of distributing

rollers

19 and 20. The fountain roller 15, spiral roller 16 and lower ink drum 18 are normally provided with a metal exterior surface, whereas the transfer roller 17 and distributing

rollers

19 and 20 are normally rubber covered, but the normal surface may be utilized when the principles of the invention are applied thereto. From the lower ink drum 18, the ink is conveyed by a transfer roller 21 to an ink drum 22, with a distributing roller 23 smoothing and making more uniform the layer of ink on the ink drum 22. The ink drum 22 is nonnally provided with a metal surface, while the transfer roller 21 and distributing roller 23 are again rubber covered. From the ink drum 22, the ink is supplied to the plates 10 of the plate cylinder C by a pair of transfer rollers 24 and 25, which are again rubber covered.

The plates 10 shown are normally of the type cast in arcuate molds, with the type to be printed extending outwardly from the. periphery of the plate, but it will be understood that the principles of this invention may be applied to a printing press in which the ink is applied to a plate having recesses or grooves, then wiped substantially clean, as by a doctor blade, in order that the printing will be accomplished by the ink remaining in the grooves or recesses. This latter type of printing plate is, of course, more often used for color printing.

Although not necessarily completely correct, one theory of the operation of the method of this invention is that, while there may be some ink fog or mist produced through the spattering of a coarser drops at or adjacent the fountain F, the principal production of ink fog or mist is along the line where two rollers separate. Thus, the action of this nip may be' referred to as a micro-taffypull", in which minute, sticky threads of ink form as the rollers draw apart radially during the course of rotation. It is theorized that these sticky threads break and separate into fog particles, on which an electrical charge is developed but which is concentrated on the particle surfaces. Since each particle has a like charge, each particle is repelled by and repels its neighboring particles. Thus, the magnetic force which is to attract the fog or mist particles to the surface of the rollers should be sufficient to overcome the electrostatic repulsion between the particles. Being drawn onto the layer of ink on the roller, each fog or mist particle will, by contact, lose its electrostatic charge to the remainder of the ink and then become amenable to coalesce with the remainder of the ink.

In order to exert the maximum magnetic effect, i.e. provide a magnetic field or series of magnetic fields of sufficient strength, as to overcome the electrostatic repulsion, the magnetized rollers are preferably provided with alternating magnetic poles, as through the use of previously magnetized discs, through the use of electromagnets within a roller having a nonmagnetic layer on the outside, but as thin as possible, or through magnetic poles created through induction. These alternatives are particularly useful for an ink roll having a metal surface.

In FIG. 2 is illustrated a composite roll R, which is provided with a pair of end discs 30 providing a mounting for stub shafts 31 and a series of spaced intermediate discs 32 which may be unmagnetized. Interspaced between the discs 32 are an alternating series of magnetic discs 33, such as shown in FIG. 3, and magnetic discs 34, such as shown in FIG. 4. The discs 33 of FIG. 3 are magnetized so that north poles are on the outside and south poles are on the inside, as indicated by the corresponding letters N and S applied thereto, while the magnetic discs 34 of FIG. 4 are magnetized so that south poles are on the outside and north poles are on the inside, as indicated by the corresponding letters S and N applied thereto. Since a magnetic field is necessarily created between a north pole and a south pole, the fields of magnetic force will extend between the alternating magnetic discs 33 and 44, exemplified by the dotted arcs 35 of FIG. 2, which are illustrative only of the magnetic field, rather than being an attempt to show the actual extent of the magnetic fields or the intensity at any specific point. Nevertheless, with magnetic fields so produced, the particles of ink tending to produce fog or mist will, through the magnetic particles contained therein, be drawn toward a magnetized roller, particularly at the tangential intersection of a pair of rollers where the greatest amount of fog or mist appears to be produced. It will be understood, of course, that the width of the intermediate discs 32, as well as of the

magnetic discs

33 and 34, may be varied from the proportions shown. The roller R of FIG. 2 is particularly adapted to be utilized as one of the rollers of FIG. 1 having a metal surface, such as the spiral roller 16, lower ink drum 18 or ink drum 22.

The induced magnetic roller I of FIG. is also particularly adapted to be used as one of the rollers of FIG. 1 having a metal surface, and includes an outer tube 38 formed of magnetizable material, such as magnetic steel, supported by conventional end plates mounted on a single shaft or on stub shafts 31. This cylinder is treated to produce a series of alternating magnetic poles, as indicated by the letters N and S of FIG. 5, with the dotted arcs 35 again representing, albeit diagrammatically, the magnetic field, between adjacent poles. Such magnetic poles may be produced by slowly rotating the surface of the cylinder past a series of magnets, illustrated in FIG. 5 as a series of horseshoe-type

permanent magnets

39 and 40 disposed in alternating relation, with common or abutting north and south poles between each adjacent pair of magnets, indicated by the letters N and S. As a result, induced magnetic fields within the roll R will be produced, represented diagrammatically by the dotted arcs 41. It will be understood, of course, that electromagnets may and usually preferably will be utilized, instead of the

permanent magnets

39 and 40 shown.

The electromagnetic roller E of FIG. 6 is also particularly adapted to be utilized as one of the rollers of FIG. 1 having a metal surface, thus including an outer metal tube 45, such as formed of nonmagnetic material, such as brass, and as thin as possible consonant with the required strength. Tube is mounted on

end discs

46 and 47, in turn supported by a shaft 48. A series of spools 49 formed of a suitable electromagnetic core material, such as a silicon steel, are also mounted on shaft 48, with the disc-type flanges 50 of each spool in abutting relation to the flanges of the adjacent spools. Within each spool is wound an electromagnetic coil 51 formed of wire of a suitable diameter and wound in such a manner that, when each coil is energized, a magnetic field will be produced having a north pole at one flange 50 and a south pole at the opposite flange 50, as indicated by the letters N and S, the winding of the coils 51 being alternated between the spools. A direct current is, of course, passed through the coils 51, being supplied thereto by a lead 52 which extends through a hole 53 in end disc 47. The coils may be connected in either series or parallel relationship, with only one coil being connected by a wire 54 with shaft 48, or each coil connected to the shaft. If the latter, the lead 52 will be connected with each of the coils, as by extending through the respective spools, but if the former, the coils will be connected in series, the last coil only being connected to the shaft. Lead 52 is connected to a conductive layer 55 on the outside of an insulating disc 56, with a brush 57 in engagement with conductive layer 55. A conductive disc 58 may also be mounted on shaft 46 for engagement with a brush 59, with the brush 57 being connected to a battery 60 or other suitable source of direct current, and brush 59 being connected to an adjustable resistance 61. Resistance 61 is utilized primarily to adjust the amount of current flowing to the coils 51, in the event of a change in the strength of the magnetic fields required, due to changes in the speed at which the press is run, or other changes in conditions, including the type of ink employed. As will be evident, the magnetic fields produced by the coils 51 will attract to the outer surface of the tube 45 ink particles which would otherwise produce a fog or mist.

The magnetically adjustable roller A of FIG. 7 is again particularly adapted to be utilized as a roller having a metal surface, thus including an outer tube 64 mounted on an end disc 65 and a corresponding disc at the opposite end and supported by a shaft 66. A nut 67 at one end, with a corresponding nut at the other end of the shaft 66, clamps together the assembly comprising the end discs, an alternating series of magnetic discs 33 and 34', similar to the discs of FIGS. 3 and 4 and having alternating north and south poles on the inside and outside, as indicated by the letters N and S, and a series of compressible rings 68 formed of rubber or other suitable material between the respective discs. The compressible rings 68 are supported from shaft 66 by narrower, hollow support cylinders 69 which encircle the shaft, so that a suitable number of magnetic discs 33' and 34 may be placed within the end discs 65 to provide a desired spacing of the magnetic discs 33' and 34'. Thus, as in FIG. 8, a smaller number of magnetic discs 33 and 34' may be spaced along the length of the shaft 66 a greater distance apart, to produce a weaker magnetic field, as indicated by the dotted lines 70, while, as illustrated in FIG. 9,

a greater number of magnetic discs 33' and 34' may be spaced closer together between the end discs 67, with the compressible rings 68 accommodating the closer spacing when the magnetic discs are moved to a position substantially abutting the support cylinders 65. A stronger magnetic field, indicated by the dotted lines 71 will be produced by the closer spacing of the magnetic discs 33' and 34 of FIG. 9. As in FIGS. 9 and 10, the metal supporting cylinders 69, between discs 33' and 34', provide a magnetic flux path between the discs. The spacing of the magnetic discs 33' and 34' will depend upon the strength of the magnetic field necessary, as required by the differences in the diameter of the outer tube 64, or by the location of the metal surface roller in the roller train of FIG. 1.

The rubber-covered roller R of FIG. 10 is particularly adapted to be used as one of the rubber-covered rollers of FIG. 1, such as the transfer rollers 17 or 21, the distributing

rollers

19, 20 or 23 and the final transfer rollers 24 or 25. The roller R is provided with a rubber covering 75 in which is embedded a number of magnetic particles, as indicated, such as formed of silicon steel or other suitable magnetizable material. The magnetizable particles in the rubber covering 75 are mag- I netized in any suitable manner, as by a series of permanent magnets, in a manner similar to the magnetization of the roller of FIG. 5, or by electromagnets. Rubber covering 75 is mounted on and adhered to a metal tube 76, supported by end discs 77 and stub shafts 78. As in the case of the roller of FIG. 5, the magnetization of the embedded magnetizable particles in the rubber covering 75 of the roller R of H0. 10 is preferably such as to produce an alternating series of north and south poles, as indicate by the letters N and S. It will be noted that the thickness of the rubber covering 75 is such that the magnetic field produced by permanent magnets or elec tromagnets inside tube 76 would not be satisfactorily effective. However, if the rubber covering 75 is sufficiently thin, then permanent magnets may be substituted for tube 76 or electromagnets placed inside the tube.

As illustrated in F IG. 1], when the rubber-covered roller R of FIG. 10, such as corresponding to a transfer roller 17 or 21, in engagement with a metal surface roller 79, such as corresponding to an

ink drum

18 or 22, is rotated in the direction of the arrow 80, and the metal surface' roller is rotated in the same peripheral direction, as indicated by the arrow 81, the rubber-covered roller will be flattened, as at 82. The ink carried by roller R will normally collect as a globular body between the rollers on the entrance side, with a series of ink filaments 83, indicated diagrammatically, produced at the opposite side, due to the nipping action between the rollers as they separate. However, due to the magnetic attraction of both roller R and roller 79 of FIG. 11, these filaments will be attracted to one or the other of the rollers by the magnetic fields thereof, because of the magnetic particles contained in the ink. Thus, the fog particles tending to be formed by the filaments 83 will be attracted to roller R or roller 79 to coalesce with the ink on the surface of the respective rollers, thus controlling or preventing the production of ink fog at its source. The amount of ink transferred from roller R to roller 79 for instance, should not be decreased by the attraction of too much ink to the roller R. Thus, the relative strength of the magnetic fields of the rollers R and 79 may be such that roller 79 will have a stronger field. Also, it may happen that, by the time the ink has been transferred from the ink fountain F to the plate cylinder C, the magnetic particles in the ink will themselves become permanently magnetized, at least to a certain extent. However, this effect can be overcome by alternating the north and south poles adjacent the exterior of consecutive rollers, to alternate the induced magnetization of the partides in the ink, as the ink moves up the roller train.

' From the foregoing, it will be evident that this invention fulfills to a marked degree the requirements and objects hereinbefore set forth. Thus, the extreme danger of high voltage electrostatic wires and charges is avoided, while the extremely small, finely divided magnetic particles in the ink should not affect to any appreciable degree the viscosity or transfer qualities of the ink. However, the magnetized rollers will attract the particles at and from the point of origin of ink fog and will thus overcome? or minimize the problem of ink fog. Upon coalescence with the body of ink carried by the respective rollers, the charged particles will lose their charge and will therefore be rendered innocuous, with respect to the electrostatic repulsion of similarly charged particles. The permanent magnetization of rollers or the use of electromagnets in the rollers does not afi'ect the ability of the rollers to transfer the ink from one to another and, in fact, should increase the efficiency of the transfer, since the loss through ink fog will be reduced.

Although several preferred embodiments of this invention have been illustrated and described, it will be understood that other embodiments may exist and that various changes may be made therein, all without departing from the spirit and scope of this invention.

What is claimed is:

l. A method of controlling ink fog in a printing press which is generated when the ink moves from one rapidly revolving roller to a second rapidly revolving roller contacting the first, and including the steps of:

a. providing a group of not less than three rollers arranged in sequence with one roller at one end of the sequence adapted to receive ink from a fountain roller and the roller at the other end of the sequence adapted to apply ink to a plate cylinder;

b. rendering the ink responsive to magnetic stimulus; and

c. magnetizing at least one of every pair of contacting rollers whereby the ink which is normally ejected from the contacting region of the said rollers as fog particles will be attracted to the said magnetizedroller.

2. In the method defined in claim 1, wherein the ink is rendered magnetic by the addition of comminuted iron oxide as a pigment to the ink vehicle. a

3. A method as defined in claim 1, wherein said magnetized rollers have a rubber-type outer layer, which includes:

embedding a plurality of magnetizable particles in said outer layer prior to inducing magnetism therein.

4. A method as defined in claim 1, including:

producing said magnetized rollers to provide alternating magnetic poles longitudinally of said rollers.

5. In a printing press combination;

a group of not less than three rollers arranged in sequence with one roller at one end of the sequence adapted to receive ink from afountain roller and a roller at the other end of the sequence adapted to apply ink to a plate cylinder;

means for supplying magnetic ink to said rollers;

means for rotating said rollers thereby producing ink fog particles at the contacting nips thereof;

at least one of each contacting pair of rollers in the said sequence being magnetized, whereby to eliminate ink fog in a printing operation when said magnetic ink is used in the operation.

6. ln printing apparatus as defined in claim 5, wherein:

at least one of said magnetized rollers is magnetized to provide alternating magnetic poles longitudinally thereof.

7. ln printing apparatus, as defined in claim 5, wherein:

some of said magnetized rollers have a metallic outer surface and other rollers have an outer, rubber-type layer; and

at least one of said outer, rubber-type layers is provided with embedded, magnetized particles.

8. ln printing apparatus as defined in claim 5, wherein:

at least one of said magnetized rollers has a metallic outer surface and includes a series of circumferentially magnetized, metallic discs having alternating magnetic poles longitudinally of said roller.

9. in printing apparatus as defined in claim 7, wherein:

each said disc is hollow and has a magnetic pole on the inside opposite to the magnetic pole on the outside.

10. ln printing apparatus, as defined in claim 7, wherein:

said magnetized roller is provided with unmagnetized discs alternating with said magnetized discs.

l 1. ln printing apparatus as defined in claim 5. wherein:

at least one said magnetized roller has an exterior metal surface formed by a relatively thin tube of nonmagnetic metal; and

a series of electromagnets disposed longitudinally within said tube.

12. in printing apparatus as defined in claim 11, wherein:

said electromagnets comprise wire coils wound within spools formed of electromagnetic materials, said coils being wound so as to produce alternating magnetic poles longitudinally of said roller; and

means for supplying a direct current to said coils.

13. In printing apparatus as defined in claim 5. wherein:

at least one said magnetized roller has an exterior metal sur face formed by a relatively thin tube of nonmagnetic material; and

a series of permanent magnets disposed longitudinally within said tube.

14. In printing apparatus as defined in claim 13. wherein:

said permanent magnets comprise a spaced series of hollow discs having a different magnetic pole at the inside than at the outside, said discs being disposed to provide alternating magnetic poles longitudinally of said roller;

a series of hollow rings of compressible, nonmagnetic material interspaced with said magnetized discs;

a central shaft for supporting said roller for rotation;

a series of hollow cylinders formed of magnetic material and surrounding said shaft for supporting said compressible rings, said support cylinders having a lesser width than the uncompressed width of said rings; and

means exerting force longitudinally of said roller for holding said magnetized discs against said compressible rings.

i ll i i l UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 24,731 Dated November 30, 1971 Inv n Euqene T. Lindberq It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 33, "articles" should read -particles-.

Column 6, line 70 (claim 9) "7" should read 8--; line 73 (claim 18) "7 should read 8-- Signed and sealed this 2nd day of May 1972.

(Sm) Attest:

EDWARD M.FLETCHER, J'R.

ROBERT GOTTSCHALK Arresting fiff'icer Commissioner of Patents USCOMM-DC 00376-1 59 a u s GDVEDNMENY PRINTING 0FF|C 19 0-360-331

Claims

1. A method of controlling ink fog in a printing press which is generated when the ink moves from one rapidly revolving roller to a second rapidly revolving roller contacting the first, and including the steps of: a. providing a group of not less than three rollers arranged in sequence with one roller at one end of the sequence adapted to receive ink from a fountain roller and the roller at the other end of the sequence adapted to apply ink to a plate cylinder; b. rendering the ink responsive to magnetic stimulus; and c. magnetizing at least one of every pair of contacting rollers whereby the ink which is normally ejected from the contacting region of the said rollers as fog particles will be attracted to the said magnetized roller.

2. In the method defined in claim 1, wherein the ink is rendered magnetic by the addition of comminuted iron oxide as a pigment to the ink vehicle.

3. A method as defined in claim 1, wherein said magnetized rollers have a rubber-type outer layer, which includes: embedding a plurality of magnetizable particles in said outer layer prior to inducing magnetism therein.

4. A method as defined in claim 1, including: producing said magnetized rollers to provide alternating magnetic poles longitudinally of said rollers.

5. In a printing press combination; a group of not less than three rollers arranged in sequence with one roller at one end of the sequence adapted to receive ink from a fountain roller and a roller at the other end of the sequence adapted to apply ink to a plate cylinder; means for supplying magnetic ink to said rollers; means for rotating said rollers thereby producing ink fog particles at the contacting nips thereof; at least one of each contacting pair of rollers in the said sequence being magnetized, whereby to eliminate ink fog in a printing operation when said magnetic ink is used in the operation.

6. In printing apparatus as defined in claim 5, wherein: at least one of said magnetized rollers is magnetized to provide alternating magnetic poles longitudinally thereof.

7. In printing apparatus, as defined in claim 5, wherein: some of said magnetized rollers have a metallic outer surface and other rollers have an outer, rubber-type layer; and at least one of said outer, rubber-type layers is provided with embedded, magnetized particles.

8. In printing apparatus as defined in claim 5, wherein: at least one of said magnetized rollers has a metallic outer surface and includes a series of circumferentially magnetized, metallic discs having alternating magnetic poles longitudinally of said roller.

9. In printing apparatus as defined in claim 7, wherein: each said disc is hollow and has a magnetic pole on the inside opposite to the magnetic pole on the outside.

10. In printing apparatus, as defined in claim 7, wherein: said magnetized roller is provided with unmagnetized discs alternating with said magnetized discs.

11. In printing apparatus as defined in claim 5, wherein: at least one said magnetized roller has an exterior metal surface formed by a relatively thin tube of nonmagnetic metAl; and a series of electromagnets disposed longitudinally within said tube.

12. In printing apparatus as defined in claim 11, wherein: said electromagnets comprise wire coils wound within spools formed of electromagnetic materials, said coils being wound so as to produce alternating magnetic poles longitudinally of said roller; and means for supplying a direct current to said coils.

13. In printing apparatus as defined in claim 5, wherein: at least one said magnetized roller has an exterior metal surface formed by a relatively thin tube of nonmagnetic material; and a series of permanent magnets disposed longitudinally within said tube.

14. In printing apparatus as defined in claim 13, wherein: said permanent magnets comprise a spaced series of hollow discs having a different magnetic pole at the inside than at the outside, said discs being disposed to provide alternating magnetic poles longitudinally of said roller; a series of hollow rings of compressible, nonmagnetic material interspaced with said magnetized discs; a central shaft for supporting said roller for rotation; a series of hollow cylinders formed of magnetic material and surrounding said shaft for supporting said compressible rings, said support cylinders having a lesser width than the uncompressed width of said rings; and means exerting force longitudinally of said roller for holding said magnetized discs against said compressible rings.