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Publication numberUS3623965 A
Publication typeGrant
Publication dateNov 30, 1971
Filing dateOct 8, 1969
Priority dateOct 8, 1969
Publication numberUS 3623965 A, US 3623965A, US-A-3623965, US3623965 A, US3623965A
InventorsOwren Erling B
Original AssigneeCranston Print Works Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Cathodic protection of printing apparatus
US 3623965 A
Abstract  available in
Images(1)
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Claims  available in
Description  (OCR text may contain errors)

llnited States Patent [72] Inventor Erling B. Owren Foster,R.1. [21] AppLNo. 864,731 [22] Filed Oct. 8,1969 [45] Patented Nov. 30, 1971 [73] Assignee Cranston Print Works Company Webster, Mass.

[54] CATIIODIC PROTECTION OF PRINTING APPARATUS 6 Claims, 3 Drawing Figs.

[52] U.S.Cl 204/148, 101/l57,101/169 [51] 1nt.Cl B41f9/10, C23fl3/00 [50] FieldofSearch 101/148, 157,169;204/147,|48,196,197

[5 6] References Cited UNITED STATES PATENTS 1,777,914 10/1930 Davis 204/197 1,895,125 l/1933 Durham.. 101/148 2,283,169 5/1942 Atwood 204/197 2,404,689 7/1946 Carlsenetal. 101/169 2,752,308 6/1956 Andrus 204/106 Primary Examiner-T. Tung Anorney-Martin Kirkpatrick ABSTRACT: A rotary printing machine for fabrics which includes a color box containing a printing paste constituting a liquid electrolyte, a rotatable print roll having an engraved cylindrical outer printing surface, a rotatable brush roll in the color box for supplying to the printing surface an excess of printing paste as the print roll rotates, a steel doctor blade with a horizontally extending longitudinal edge positioned against the printing surface to remove the excess printing paste for gravity flow across one side of the blade in a direction perpendicular to its edge and a printing cylinder traversing and pressing a fabric web against the print roll printing surface following supplying of the printing paste thereto by the brush roll and after removal of the excess by the doctor blade. The doctor blade has a more electropositive strip of metal, such as magnesium, or aluminum, in electrical contact with the steel doctor blade spaced from the edge thereof and extending generally throughout the length thereof on said one side for flow of the excess printing paste thereacross in electrical contact therewith, thereby providing a sacrificial anode to prevent electrolytic corrosion and pitting ofthe doctor blade edge.

CATI-IODIC PROTECTION OF PRINTING APPARATUS This invention relates to rotary printing machines and more particularly to novel apparatus and methods for preventing electrolytic corrosion and pitting of the edges of doctor blades when used with printing rolls in such equipment.

As set forth in my earlier U.S. Pat. No. 3,l66,487, in known rotary printing machines for textile fabrics, and the like there is included a reservoir called a color box, containing a printing paste constituting a liquid electrolyte, which is spread upon a rotatable print roll having an engraved cylindrical outer printing surface by a rotatable brush roll in the color box. A steel or other metallic doctor blade with a horizontally extending longitudinal edge is positioned against the printing surface to remove excess printing paste from the unengraved portions of the print roll. A printing cylinder is also provided for traversing and pressing a fabric web against the print roll printing surface following supplying of said paste thereto by said brush roll and after removal of the excess by said doctor blade, with enough pressure between the print roll and printing cylinder to transfer or print the paste from the engraved depressions to the moving fabric. If the doctor blade does not remove all the unwanted excess printing paste from the surface of the engraved print roll, streaks will be left on the roll which will appear as undesirable stripes on the fabric when the printing cylinder applies the fabric against the print roll. Any cracks, nicks or other unevenness in the edge of the doctor blade must therefore be avoided or unsalable streaked printed fabric will be produced. But, unfortunately, it has been long known that deleterious pitting and corrosion of the edge of the doctor blade frequently appeared after operation of such roller printing equipment for a relatively short period of time.

As a result of the development work leading to the inventions of my US. Pat. No. 3,166,487, it was discovered that such corrosion and pitting of the edge of the doctor blade is largely due to the electrolytic action occurring in a voltaic cell which includes the usual steel doctor blade as the anode; the printing paste as the liquid electrolyte and the color box and print roll in contact with the paste as the cathode of the cell. The inventions of that patent approached the solution to the problem by adding an electrode to the color box and applying a small direct current thereto which transferred the corrosive etching or pitting action to the interposed electrode.

It is the major object of the present invention to solve the corrosive etching and pitting problems of doctor blades in rotary printing machines in a much simplified yet even more effective manner, and at the same time eliminate the inconvenience of having to utilize supplemental direct current for such control.

The above and further objects of the invention are accomplished by mounting on the doctor blade in electrical contact with it and with the printing paste flowing across it a strip of metal more electropositive than that of the doctor blade. Such strip is preferably spaced from the doctor blade edge and extends generally throughout the length thereof. It may be of aluminum or magnesium to act as a sacrificial anode for the steel doctor blade to prevent electrolytic corrosion and pitting of the doctor blade edge.

Other objects and features of the invention will be apparent from the following description of a preferred embodiment of the invention, together with the accompanying drawings, wherein:

FIG. 1 is a vertical section through the active printing parts of a roller printing machine showing somewhat diagrammatically one form of the present invention applied thereto;

FIG. 2 is an enlarged sectional view of the doctor blade portion of FIG. 1, and

HO. 3 is an enlarged partial elevational view of the doctor blade portion of FIG. 2. In the rotary printing machine shown in the drawings, there is included a color box 12 which contains the printing paste l4 constituting a liquid electrolyte.

A rotatable fiber or nylon brush roll 16 clips into the reservoir of printing paste 14 in said color box and upon rotation carries the paste and spreads onto the engraved cylindrical outer printing surface of rotatable print roll 18 an excess of said paste as said print roll rotates. Print roll 18 has on its outer surface a repetitive design in the form of depressions 19 for carrying the printing paste to be applied to the fabric F. It is from the depressions 19 on this roll that the paste is printing or applied against the fabric F, carried by the traversing printing machine cylinder 22 past the print roll to transfer or set" the engraved design on the fabric.

The printing paste 14 being supplied in substantial excess to the surface of print roll 18, there is provided a doctor blade 24, generally of steel, having a horizontally extending longitudinal edge 26 positioned against the surface of the print roll 18 in advance of the place where the roll reaches the fabric, so

.that the excess printing paste I4 is removed for gravity flow across one side of the doctor blade, and in a direction perpendicular to said edge as shown by arrows 14a. The excess printing paste 14 is thus removed from the print roll 18 and is returned to color box 12 by gravity flow. The doctor blade 24 is firmly but adjustably secured as by a mounting bar 28 on a suitable portion of the frame of the machine so that the engagement of the edge of the blade with the surface of the print roll may be carefully adjusted and maintained. A clamping bar 30, held in place as by a series of bolts 32 assists in securing the blade to the mounting bar in proper position.

According to the present invention, there is provided, clamped between clamping bar 30 and mounting bar-28 and extending thereabove, a novel strip 34 of a metal more electropositive than the metal of doctor blade 24. As so clamped, strip 34 is in electrical contact with the doctor blade 24, spaced below the edge 26 thereof and extending generally throughout the length of the doctor blade on the side thereof across which the excess printing paste flows, so that strip 34 is in electrical contact with the excess printing paste flowing downwardly across it and mounting bar 28 for return to color box 12. Metals such as aluminum and magnesium have been utilized as strip 34 and have been highly effective in eliminating electrolytic corrosion and pitting ofthe doctor blade.

ln carrying out the invention, it has been found to be important that the strip 34 extend generally along the entire length of the doctor blade, which is commonly of the order of 40 to 60 inches in fabric-printing machines, and that sufficient excess printing paste be applied to print roll 18 so that doctor blade 24 and strip 34 is bathed therein throughout their entire length. Of course, the doctor blades surface must slop downwardly for gravity flow of printing paste 14 thereacross the strip 34 must be positioned on the leading side thereof on which such flow occurs. Under these circumstances, the invention provides a galvanic cell which includes the doctor blade and the strip as the dissimilar metal electrodes and the excess of printing paste as the liquid electrolyte and provides a sacrificial anode in the metal strip to prevent electrolytic corrosion and pitting of the edge of the doctor blade.

Although the metal strip shown and described herein is in the form of a separate strip clamped beside the steel doctor blade, it may as well take other forms, such as metal sprayed or plated onto the doctor blades, for example, and metals other than aluminum, more electropositive than the metal of the doctor blade may be used as well.

What is claimed is:

1. In a rotary printing machine for fabrics which includes a color box containing a printing paste constituting a liquid electrolyte a rotatably print roll having an engraved cylindrical outer printing surface.

a rotatably brush roll in said color box for supplying to said printing surface an excess of said paste as said print roll rotates a doctor blade with a horizontally extending longitudinal edge positioned against said surface to remove said excess for gravity flow across one side of said blade in a direction perpendicular to said edge and a printing cylinder traversing and pressing a fabric web against said print roll printing surface following supplying of said paste thereto by said brush roll and after removal of said excess by said doctor blade that improvement which consists of a strip of metal more electropositive than said doctor blade in electrical contact with said blade spaced from the edge thereof and extending generally throughout the length thereof on said one side for flow of said excess printing paste thereacross in electrical contact therewith, thereby providing a sacrificial anode to prevent electrolytic corrosion and pitting of said doctor blade edge. 2. In a rotary printing machine as claimed in claim 1, wherein said doctor blade is of steel. 3. In a rotary printing machine as claimed in claim 2, wherein said strip of metal is of the class including aluminum and magnesium. 4. The method of preventing electrolytic corrosion in a rotary printing machine for fabrics which includes a color box containing a printing paste constituting a liquid electrolyte a rotatable print roll having an engraved cylindrical outer printing surface a rotatable brush roll in said color box for supplying to said printing surface an excess of said paste as said print roll rotates a doctor blade with a horizontally extending longitudinal edge positioned against said surface to remove said excess for gravity flow across one side of said blade in a direction perpendicular to said edge and a printing cylinder traversing and pressing a fabric web against said print roll printing surface following supplying of said paste thereto by said brush roll and after removal of said excess by said doctor blade comprising providing a strip of metal more electropositive than said doctor blade in electrical contact with said blade spaced from the edge thereof and extending generally throughout the length thereof on said one side for flow of said excess printing paste thereacross in electrical contact therewith, thereby providing a sacrificial anode to prevent electrolytic corrosion and pitting of said doctor blade edge.

5. The method as claimed in claim 4, wherein said doctor blade is of steel.

6. The method as claimed in claim 5, wherein said strip of metal is aluminum or magnesium.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1777914 *Nov 19, 1928Oct 7, 1930Davis Ernest WSafety razor
US1895125 *Feb 2, 1931Jan 24, 1933Durham Hobart NPlanographic printing
US2283169 *May 13, 1939May 19, 1942Atlantic Res Associates IncSpinning fibers
US2404689 *Jan 16, 1945Jul 23, 1946Aspinook CorpDoctor blade
US2752308 *Aug 18, 1952Jun 26, 1956Smith Corp A OCathodically protected water storage tank with safety shutoff
US3166487 *Feb 14, 1962Jan 19, 1965Cranston Print Works CoCathodic protection of printing apparatus
US3216916 *Nov 13, 1962Nov 9, 1965Continental Oil CoAnodic passivation of wetted wall vessels
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3986453 *Apr 1, 1975Oct 19, 1976Ahlen & Akerlunds Forlags AbDevice for stripping excess ink from a rotating printing roll in rotogravure presses
US4184429 *Jan 29, 1976Jan 22, 1980Max Datwyler & Co.Constant bevel doctor blade and method and apparatus using same
US4945832 *Feb 21, 1989Aug 7, 1990Odom Jimmie LDoctor blade system
US5184552 *Oct 17, 1989Feb 9, 1993Rockwell International CorporationInk roller for rotary press
US5366784 *Feb 3, 1993Nov 22, 1994Herbison Paul RCorrosion inhibiting offset printing blanket
US5711079 *Oct 15, 1996Jan 27, 1998Underwater KineticsCorrosion resistant knife
US6360660 *Nov 24, 1999Mar 26, 2002Allison Tech Sales IncorporatedDoctor blade systems
US8281491 *Mar 14, 2006Oct 9, 2012The Gillette CompanyShaving razor and shaving cartridges
DE19829491A1 *Jul 1, 1998Jan 5, 2000Spectris GmbhVorrichtung zum kathodischen Korrosionsschutz von Auftragslementen einer Papierstreichanlage
EP0716922A1 *Dec 14, 1995Jun 19, 1996Denend Mark E. VanPrinting press having doctor blade with integral tape seal thereon
Classifications
U.S. Classification205/732, 205/733, 101/157, 101/169
International ClassificationB41F9/10, B41F9/00
Cooperative ClassificationB41F9/1072
European ClassificationB41F9/10H