US2022635A - Printing press - Google Patents

Description

NOV. 26, 1935. H DURHAM PRINTING PRESS Filed Feb. 25, 1935 a YhfiJNVEETOR Patented Nov. 26, 1935 PATENT, OFFICE ram-mm rnsss Hobart N. Durham, Manhasset, N. Y., assignor to The Goss Printing Press Company, Chicago, 111.,

a corporation of Illinois Application February 25, 1935, Serial No. 8,153 24 Claims. (01. lol -157) The present invention relates to rotary photogravure printing and more particularly to a novel and improved inking apparatus and method particularly adapted for use with quick-drying inks in rotary photogravure printing.

Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, construction, arrangements, combinations and improvements herein shown and described.

The accompanying drawing, referred to herein and constituting a part hereof, illustrates one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

The single figure of the drawing is a diagrammatic sectional view showing an illustrative embodiment of the present invention in connection with a rotary photogravure printing press.

The present invention has for its object the provision of a novel and improved inking mechanism and method particularly adapted for use in connection with the inking of a rotary photogravure printing cylinder with highly-volatile or quick-drying inks. A further object is the provision of a novel and improved rotary photogravure printing mechanism and method in which the evaporation of the ink is reduced and substantially prevented by the cooling of the ink. Still another object is the provision of an improved inking mechanism which can be applied to existing rotary photogravure printing presses Ivithout extensive rebuilding of the press strucure.

In accordance with the present embodiment of the invention, there is provided a rotary photogravure cylinder and impression roller of con ventional construction, the impression roller pressing the web of paper to be printed into the minute, inked, intagliated cavities on the surface of the printing cylinder so as to transfer the ink from the cavities to the surface of the paper web. The printing cylinder is surrounded for a substantial distance by a concentricshield, and ink is applied to the surface of the cylinder by an ink nozzle projecting through the shield and forcing the ink against the cylinder surface to fill the intagliated design portions of the cylinder. A doctor blade is provided for removing ink from the surface of the cylinder, but not from the inked cavities, as is usual in rotary photogravure printing. An ink reservoir, which may be positioned to one side of the press or wherever convenient, supplies ink under pressure to the nozzle and also receives the surplus ink supplied to the cylinder. For reducing the vapor pressure of the ink and substantially preventing or reducing its evaporation, refrigerating or other cooling means are provided for cooling the ink in the reservoir sufficiently to greatly reduce its vapor pressure 10 and these means are also preferably arranged to cool the shield surrounding a portion of the printing cylinder surface. Preferably, the shield also serves to collect surplus ink supplied by the ink nozzle to the cylinder surface and to return 5 this surplus ink to the ink reservoir, and when so used, the ink is additionally cooled as it is collected by the shield.

Means are provided for removing any water from. the ink which may be condensed therein from the atmosphere during the recirculating of the cooled ink, and filter means are provided for removing solid foreign matter from the ink to prevent injury to the relatively delicate cylinder surface.

In order to further reduce evaporation of the volatile ink, means are provided for drawing air reversely to the direction of rotation of the cylinder between the shield and cylinder, thereby preventing rapid flow of air over the surplus ink flowing down the inner surface of the shield, and these means also serve to draw air into the space between the shield and cylinder along the side edges of the shield. Other means are provided for removing the ink vapors from the freshly printed web and for this purpose a suction nozzle is provided closely adjacent to but beyond the point of impression.

It will be understood that the foregoing general description and the following detailed description as well, are exemplary and explanatory of the invention but are not restrictive thereof.

The apparatus thus briefly described serves to carry out the preferred manner of performing the method of the present invention in which the 45 highly volatile ink is applied under pressure to the cylinder surface after the ink has been cooled to a temperature at which its vapor pressure is relatively low, the surplus ink is collected and returned to an ink reservoir for recirculation and 50 recooling, and the major portion of the surplus ink is collected on a surface maintained at a relatively low temperature. During its recirculation, the cooled ink is filtered to remove foreign particles and is additionally treated to re- 55 move condensed atmospheric moisture therefrom. To reduce evaporation and minimize the amount of moisture collected by the ink, the flow of air with the cylinder is reduced by slowly drawing air between the shield and cylinder reversely to the direction of cylinder rotation. Preferably, the doctor blade is positioned close to the point of impression and Just beyond the impression point the ink solvent vapors are removed from the freshly printed web.

Rotary photogravure inks are generally formed of a volatile liquid in which is suspended or dissolved coloring matter, such as dye. or pigment, and suitable binding substances. Many different solvents and thinners have been employed including liquids such as carbon tetrachloride, petroleum dlstillates, xylol, benzol, etc., and in certain types of presses in which the printing cylinder is tightly enclosed, highly-volatile inks utilizing petroleum ether and similar substances have been used. The use of the less readily volatile solvents and thinners slows the press, requires more time for drying and contaminates the pressroom atmosphere, while the use of the highlyvolatile inks in a tightly sealed compartment necessitates close fitting of all the parts, which is a distinct disadvantage where cylinders of different sizes are employed, as is customary in rotary photogravure printing. The present invention avoids these and other defects of the prior art. I

Referring now in detail to the illustrative embodiment of the present invention as shown in the accompanying drawing, the invention is shown as applied to a conventional rotary photogravure printing couple having a rotary photogravure cylinder l and an impression roller H to press the web of paper l2 to be printed against the surface and into the cavities in the cylinder III For applying ink to the surface of the rotary photogravure cylinder to fill the intagliated design portions of the cylinder there is provided an ink nozzle t5 extending throughout substantially the entire length of the cylinder l0 and axially parallel thereto, this nozzle being positioned very close to the cylinder surface as well as relatively close to the point where the paper is pressed against the cylinder by roller II. The nozzle I5 is preferably reduced at its mouth so that ,the ink is forced against the cylinder and into the design cavities with some pressure, and a sufficient amount of ink is supplied through the nozzle so that some of the ink flows in both directions along the cylinder surface and away from the nozzle l5.

Surplus ink is removed from the cylinder surface by means of a doctor blade I! which extends axially of the cylinder i0 and is positioned relatively close to the impression point. Blade I! may be of conventional construction and may be provided with any suitable adjusting means to vary its pressure against the cylinder surface to insure that the cylinder surface is wiped clean, leaving ink only in the cavities in the cylinder surface.

The surplus ink removed from the cylinder surface by the doctor blade I! is collected and returned to an ink reservoir 20 by means of pipe 2| positioned to one side of and below the press, and this surplus ink may be collected adjacent to the doctor blade I! by means of the inclined plate 23 which extends nearly into contact with the cylinder surface. Plate 23 and blade II are mounted ona support 24 and together with their aosaess end walls 28 form a chamber which communicates with pipe 2| at its rear, and has a relatively long and narrow opening. adjacent to the cylinder surface.

The remainder of the surplus ink supplied to 5 the cylinder surface is collected and returned to the reservoir 20 by means of a parti-cylindrical shield 30 which surrounds a relatively large portion of the cylinder i0, is concentric therewith, and spaced slightly therefrom with nozzle II projecting through this shell. Along both its curved edges, shield 30 is provided with a narrow inwardly turnedlip 32 which extends close to, but is spaced from the cylinder surface, these lips tending to preventing ink running out the side edges of the shield, and also tending to reduce the flow of air over the cylinder It.

At the lowest part of the shield -30, there is provided a trough 33 extending across substantially the entire length of the shield and cylinder to which the ink drains from the inner surface of the shield 30, and this trough 33 is connected with the reservoir by return pipe 85.

In order to facilitate the changing of cylinders in, the shield is divided into two parts, and 25 the smaller of these parts is pivotally mounted at or close to the trough 33, permitting the smaller portion of the shield to be dropped-to a low position when the cylinder is to be replaced by another.

For cooling the rotary photogravure ink to a relatively low temperature at which it has only a. very small vapor pressure and is not readily evaporable, evaporating coils 40 are provided and are immersed in the ink reservoir 20, these coils being supplied with refrigerating fluid by means of a suitable refrigerating mechanism. This mechanism may be of any desired construction, but as shown diagrammatically comprises a compressor 45, a condenser 46, expansion valve 41 and the cooling or evaporating coils 40 which are supplied with the refrigerating fluid under pressure by compressor 45 through expansion valve 41, the evaporated fluid being thereafter returned to the compressor. Suitable controllable thermostatic means 48 are provided for regulating the operation of the compressor to maintain the desired temperature of the ink.

Preferably, the shield 30 is also cooled to prevent evaporation of the ink on the cylinder sur- 60 face and to cool the cylinder surface, as well as the air which is drawn between the cylinder and the shield 30. For this purpose cooling or evaporating coils 50 are provided on the outer side of the shield 30 and adjacent thereto or in contact therewith, cooling the shield and the ink as it flows down the inner surface of the shield into the collecting trough l3. Coils 50 are also supplied with refrigerating fluid by means of the compressor 45 in thesame manner as coils III.

For reducing the amount of cooling required the reservoir 20 is covered with an insulating' jacket 55, the shield II is covered with its insulating jacket 58, while the ink pipes are covered with their insulating jackets 51.

A filter or screen is provided within the reservoir 20 through which the returned ink, and any new ink added to the reservoir is passed to remove any solid foreign matter which might otherwise injure the delicate copper surface of the rotary photogravure cylinder Iii.

Means are also provided for removing water from the ink, thereby keeping it in good printing condition and preventing accumulation of the water which condenses from the atmosphere (6 due to the chilling of the ink. As embodied, the

ink is passed through a very fine screen If, this screen being sufficiently fine to remove the small drops of water which are suspended in the ink, and the water collects in the sump 83. The screen, being wet with the oily ink, tends to repel water, while permitting the ink and its pigment or dye to pass through, while the surface tension of the water is greater than the pressure tending to force the water through the screen. A drain cock it permits the -accum'ulzstted water to be drawn off as necessary.

For recirculating the ink and forcing it through nozzle It and onto the cylinder surface, a motor driven pump 10 is provided, withdrawing ink from the reservoir 20 and supplying it directly to the nozzle". This pump is preferably of variable capacity and is adapted to deliver .a much larger quantity of ink than is actually required to fill the cavities of the design portion of cylinder iii.

In order to reduce the flow of air overthe ink collecting on the inner surface of shield 30 and to prevent evaporation of this surplus ink, means are provided for slowly sucking air into the space between the shield 30 and cylinder it, moving this air reversely with respect to the cylinder rotation and drawing it off at the end of .the shield 30. As embodied, there is provided a pipe 12 extending the length of the cylinder and positioned along the edge of shield 30. this pipe being provided with a longitudinal slot I3 opening onto the cylinder surface. Pipe 12 is removably connected to an exhaust manifold M at one side of the press and may be removed when it is desired to replace the printing cylinder Ill. Thefiow of air through the, slot 13 is preferably regulated so that it is just sufficient to reversely move the air over the shield and produce a slight negative pressure between the shield and cylinder, thereby preventing escape of the ink solvent vapor into the press-room.

Similar suction means are provided for removing the solvent vapors from the freshly printed web, thereby assisting in the rapid drying of the impression and also preventing spreading of the ink solvent vapors throughout the press room. As embodied an exhaust pipe 15 extends axially of the cylinder ill and impression roller I I and is flared to provide an exhausting hood it, relatively long and narrow, closely adjacent to and just beyond the impression point, thereby removing the major portion of the solvent vapors while the impression is still relatively wet. Exhaust pipe 15 is also removably connected to the manifold ll and may be removed while replacing cylinder iii.

In the operation of the described apparatus and in the preferred manner of carrying out the method of the present invention, the temperature of the ink is maintained at from 0 to 10 C. the optimum temperature being determined principally by the ink solvent employed and by the other constituents of the ink, and occasionally by the particular character of the design to be printed, due to the effect of the temperature upon the viscosity of the ink.

The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its chief advantages.

What I claim is:-

l. The method of preventing evaporation of highly volatile rotary photogravure ink as it is applied to a rotating photogravure printing cylinder which includes cooling the ink to a low temperature such that it has a lowvapor pres- 5 sure and reducing entrainment of air by the cylinder by sucking air slowly over the surface of the cylinder reversely to its direction of rotaion.

2. The method of preventing evaporation of 10 highly volatile rotary photogravure ink as it is applied to a rotating photogravure printing cylinder which includes cooling the ink to a low temperature such that it has a low vapor pressure, reducing entrainment of air by the cylin- 15.

der by sucking air slowly over the surface of the cylinder reversely to its direction of rotation and removing condensed atmospheric moisture from the recirculated ink.

3. The method of preventing evaporation of 2 highly volatile rotary photogravure ink as it is applied to a rotating photogravure printing cylinder which includes maintaining a surplus of ink in a reservoir, collecting surplus ink from .the cylinder on a refrigerated surface, cooling the 5 ink in the reservoir to greatly reduce its vapor pressure and applying the ink to the cylinder.

4. The method of preventing evaporation of highly volatile rotary photogravure ink as it is applied to a rotating photogravure printing g cylinder which includes maintaining a surplus of ink in a resorvoir, collecting surplus ink from the cylinder on a refrigerated surface, cooling the ink in the reservoir to greatly reduce its vapor pressure and reducing entrainment of air by, the 35 cylinder by reversely and slowly moving air over the surface of the printing cylinder.

5. The method of preventing evaporation of highly volatile rotary photogravure ink as it is applied to a rotating photogravure printing cyl- 4o inder which includes maintaining a surplus of ink in a reservoir, collecting surplus ink from the cylinder on a refrigerated surface, cooling the ink-in the reservoir to greatly reduce its vapor pressure and removing condensed atmospheric moisture from the recirculating ink.

'6. The method of preventing evaporation of highly volatile rotary photogravure ink as it is applied to a rotating photogravure printing cylinder which'includes maintaining a surplus of ink in a reservoir, collecting surplus ink from the cylinder on a refrigerated surface, cooling the ink in the reservoir to greatly reduce its vapor pressure, reducing entrainment of air by the cylinder by reversely and slowly moving air over the surface of the printing cylinder and removing condensed atmospheric moisture from the recirculating ink. 7. Ina rotary photogravure printing press having a rotatable printing cylinder and a rotatable impression roller for pressing the web to be printed against the inked printing cylinder, the, combination of an ink reservoir, an ink nozzle for applying ink to the surface of the cylinder, means for supplying ink from the reservoir to the nozzle, 65 a shield surrounding a portion of-the cylinder to collect surplus ink and return it to the reservoir and means for cooling the shield.

' 8. In a rotary photogravure printing press having a rotatable printing cylinder and a rotatable impression roller for pressing the web to be printed against the inked printing cylinder, the combination of means for applying a flowing body of ink to the surface of the cylinder, means for reducing the admission of fresh air adjacent 7 the inked cylinder surface and means for cooling the ink for reducing evaporation of the ink solvent.

9. In, a rotary photogravure printing press having a rotatable printing cylinder and a rotatable impression roller for pressing the web to be printed against the inked printing cylinder, the combination of an ink nozzle for applying ink to the surface of the cylinder, means for supplying ink to the nozzle, a doctor blade, means including a reservoir and a shield surrounding a portion of the cylinder for collecting the excess ink supplied to the cylinder, means for recirculating the ink between the reservoir and cylinder, and means for cooling the shield and the ink within the reservoir.

10. In a rotary photogravure printing press having a rotatable printing cylinder and a rotatable impression roller for pressing the web to be printed against the inked printing cylinder, the combination of an ink nozzle for applying ink to the surface of the cylinder, means for supplying ink to the nozzle, a doctor blade, means including a reservoir for collecting the excess ink supplied to the cylinder, means for recirculating the ink between the reservoir and cylinder, means for cooling the ink and means for removing condensed moisture from the ink.

11. In a rotary photogravure printing press having a rotatable printing cylinder and a rotatable impression roller for pressing the web to be printed against the inked printing cylinder, the combination of an ink nozzle for applying ink to the surface of the cylinder, means for supplying ink to the nozzle, a doctor blade, means including a reservoir for collecting the excess ink supplied to the cylinder, means for recirculating the ink between the cylinder and reservoir, means for cooling the ink and means for reversely drawing air over the cylinder surface.

12. In a rotary photogravure printing press having a rotatable printing cylinder and a rotatable impression roller for pressing the web to be printed against the inked printing cylinder, the combination of an ink nozzle for applying ink to the surface of the cylinder, means for supplying ink to the nozzle, a doctor blade, a reservoir for collecting the excess ink supplied to the cylinder, means for recirculating the ink between the reservoir and cylinder, means within the reservoir for cooling the ink including a cooling coil and means for regulating the cooling action of the coil to maintain the ink temperature uniform.

13. In a. rotary photogravure printing press having a rotatable printing cylinder and a rotatable impression roller for pressing the web to be printed against the inked printing cylinder, the combination of an ink nozzle for applying ink to the surface of the cylinder, means for supplying ink to the nozzle, a doctor blade, means including a reservoir for collecting the excess ink supplied to the cylinder, means for recirculating the ink between the cylinder and reservoir, means for cooling the ink including a cooling coil, means for regulating the cooling action of the coil to maintain the ink temperature uniform, and means for reversely drawing air over the cylinder surface.

14. In rotary photogravure printing, the method which includes cooling highly volatile liquid ink to a temperature such that it has a low vapor pressure, applying the ink to the photogravure cylinder, recirculating the ink between the cylinder and'an ink reservoir, and removing condensed atmospheric moisture from the ink.

15. In rotary photogravure printing, the method which includes cooling highly volatile liquid ink, applying the ink to a rotating photogravure printing cylinder and removing condensed atmospheric moisture from saidink. 5

16. In rotary photogravure printing, the method which includes applying a flowing body of highly volatile ink to the surface of a cylinder rotatably mounted within a housing, impeding the admission of fresh air adjacent the cylinder and cooling the ink to further reduce its evaporation.

1'7. In rotary photogravure printing, the method which includes rapidly forcing highly volatile ink against the surface of a cylinder, impeding ii the admission of fresh air adjacent the cylinder, collecting and returning surplus ink to the cylinder and cooling the ink to further reduce its evaporation.

18. In a rotary photogravure printing press, in combination a printing couple including an intaglio printing cylinder and an impression cylinder, a curved casing or shield extending about and slightly spaced from the printing cylinder, means for supplying ink at one end of said curved shield so that it will flow in a thin stream or sheet between said shield and the printing cylinder, means opening from said curved shield for conveying away the ink that has flowed over the surface of the cylinder, a pump for circu- 80 lating the ink, a reservoir in the ink circulating system. means for cooling the ink including a pipe coil within the reservoir, a doctor blade, and

a blade behind the doctor blade, surplus ink being collected between said blades and being conveyed away rearwardly over said last-mentioned blade.

19. In a rotary photogravure printing press, in combination, a printing couple including an intaglio printing cylinder and an impression cyi- 40 inder, a curved casing or shield extending about and slightly spaced from the printing cylinder, means for supplying ink at one end of said curved shield so that it will flow in a thin stream or sheet between said shield and the printing cyli5 inder, means opening from said curved shield for conveying away the ink that has flowed over the surface of the cylinder, means for circulating the ink, and means for cooling the ink in the circulating system.

20. In a rotary photogravure printing press, in combination, a printing couple including an intagllo printing cylinder and an impression cylinder, a curved casing or shield extending about and slightly spaced from the printing cylinder, means for supplying ink at one end of said curved shield so that it will flow in a thin stream or sheet between said shield and the printing cylinder, means for receiving and conveying away the ink that has flowed between said shield and printing cylinder, means for conveying the ink again to said ink supply means, and means for cooling the ink in the circulating system.

21. In a rotary photogravure printing press, in combination, a printing couple including an intaglio printing cylinder, and an impression cylinder, a curved casing or shield extending about and slightly spaced from the printing cylinder, means for supplying ink at one end of said curved shield so that it will flow in a trim stream or sheet between said shield and the printing cylinder, means for receiving and conveying away the ink that has flowed between said sheet and printing cylinder, means for conveying the ink again to said ink supply means, a reservoir in the circulating system and means for cooling the ink in the circulating system.

22. The method of rotary photogravure printing which includes cooling highly volatile liquid ink, and applying the ink to a rotating photogravure printing cylinder and impeding the admission of fresh air adjacent to the cylinder to further reduce the evaporation of the ink.

23. The method of rotary photogravure printing which includes applying ink to a rotating photogravure printing cylinder, impeding the admission of fresh air adjacent to the moving ink on the cylinder surface to reduce the evaporation of the ink, cooling the ink to further reduce its evaporation, removing and collecting the surplus ink applied to the cylinder and returning said surplus ink to the cylinder.

24. In rotary intaglio printing, the method which comprises subjecting a rotary photogra vure cylinder to an application of an ink containing volatile ingredients while continuously circulating a body of said ink between a main liquid bodyspaced from said cylinder and a secondary liquid body in contact with said cylinder, preventing substantial evaporation of said ing'redients from the main liquidbody and the secondary'liquid body during such circulation by impeding the access of fresh air to the liquid and by cooling the liquid, wiping the excess of ink from said cylinder surface and returning the excess ink so wiped to the circulating body of ink.

HOBART N. DURHAM;

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