US1426549A - Printing surface - Google Patents

Description

J. A. COREY. PRINTING SURFACE.

APPLICATION FILED MAR- 4, I919.

Patented Au. 22, 1922.

IIIII I Inventor Attorney-- UNITED sTAras T OFFICE.

PRINTING SURFACE.

Application filed March 4, 1919. Serial No. 280,668.

(GRANTED UNDER THE PROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STA T. L, 1313.)

To all whom it may concern:

Be it known that 1, JAMES ALBERT COREY, an American citizen, residing at 18 Manor Mansions, Belsize Grove, Hampstead, Lon: don, N. England, have invented certain new and useful Improvements Relating to Printing Surfaces (for which I have filed application in Great Britain February 25, 1918, application No. 3,269), of which the following is a specification.

This invention relates to printing surfaces.

The invention has for one of its objects to produce cylindrical printing surfaces by electrotyping and has especial utility in ts application to repetition work such for 1nstance as bank notes, postage stamps, and the like with respect to which it is diflicult in a practical way to ensure substantial identity of image and tone from a number of printing surfaces repeated by engraving or photogravure from the same original.

The use of fiat intaglio printing surfaces duplicated from the original by eleotrotyping is known for printing in flat bed printing-machines but the use of intaglio and other printing surfaces in rotary printing machines is restricted bythe practical difliculty referred to.

The invention has thus among its objects to secure substantial identity of impression and tone values from a number of cylindrical printing surfaces by their production by electrotyping from the original.

The invention broadly comprises the.production of cylindrical printing surfaces as relatively thin, hard and dense deposits by electrotyping, and it comprises the methods hereinafter described v and the products thereof.

According to the invention the electrotype printing cylinder may be produced as arelatively thin and hard deposit from an original of identical cylindrical form or it may be produced from an original in the flat, or again the electrotype in the form of a relatively thin and hard deposit may be produced in the fiat and subsequently shaped to a cylindrical form as hereinafter described.

The invention is illustrated diagrammatioall in the accompanying drawing in whic Figure 1 represents a diagrammatic section lllustrating the manner in which the mother is formed upon the master.

Figure 2 is a similar section showing the manner in which the electrotype is produced within the mother, and c F gure 3 illustrates in a similar view a sectlonal viewof the electrotype produced.

In carrying the invention into effect according to one modification in the productlon of an intaglio printing cylinder, I produce an original a of identical cylindrical form to that to be electrotyped and from this original or master a I produce a number of identical cylindrical electrotypes d which are relatively thin and hard. For repetition work such as postage stamps the original image may be multiplied as many times as required, assembling these copies in register and then proceeding in the samev way as in reproducing the original of a single image. The master cylinder 0. is prepared for the production of a relief or Specification of Letters Patent. Patented Aug, 22, 1922,

mother 6 by treating the surface so that the deposit may be separated from it without injuryor loss of definition to the engraved image. This may be conveniently done by 'a deposit of silver upon. .the engraved surface or by any other methods commonly practised by the el'ectrotyper. A layer of metal such as copper is then electro-deposited upon the master cylinder a and the deposit while being relatively thin may be made sufliciently thick for example for the cylinder to be self-supporting when stripped from themaster, that is, it may be of such a thickness and degree of hardness that it will spring back or not be so thick as to be incapable of being gently forced back into exact circular form, thus understood that a very thin deposit is practicable and the most economical. For this purpose the electro-deposition isv effected in the use of high current densit es and in the circulation of the electrolyte, or in the movement of the cathode therein. The relief or mother cylinder b thus produced together with the master a may be mount ed upon a mandrel in a lathe or grinding machine and be ground true and the deposit trimmed to the desired length by cutting just through the deposit to the original or master cylinder a at both ends. A longitudinal cut as at e is then made through the deposit 6 parallel with the longitudinal printing cylinder having a continuous doctoring or wlping surface from such a mother cylinder, the following method may be employed. v

The longitudinal edges of the mother or relief cylinder 6 where the gylinder is slit at e are brought together in alignment, and in order to maintain the edges in position and'to make good electrical contact I may tack the edges with solder at a number of points and fill in any slight gap that re mains in theintervals between the solder points with the wax or other suitable non conducting material and carefully scrape away any superfluous wax so as to make an uninterrupted curved surface over the slit posit.

ate. The wax may then carefully be polished with graphite to make it electrically conductive and so that the deposit may then be made continuous around the entire surface ofthe relief or mother cylinder.

The mother cylinder or relief 6 is then mounted in a holder by which it may be fixed to a spindle by which it may be rotated within the electrolyte. The inner surface carrying the image may be prepared for separating the deposit by silvering or by other means and the deposltmay then be made under the same conditions and to the posit will be now made on the inside of the ,cylinder 6 instead of upon the outside, and

may be confined tominima thicknesses of de- The deposlt having reached the desired thickness the mother cylinder or relief I) is separated from the mother I). For this purpose the solder joints at e are melted away and boiling water may be poured as before upon the outer cylinder 5 which will then expand and facilitate separation from movement.

the face plate of the machine concentric the inner cylinder 0!. The outer cylinder 5 can then be grasped by the two ed es and gently sprung open sufliciently to a low of slipping clear oil the inner cylinder d without damage to either. Any traces of the image that may appear in relief on the inner surface of the cylinder are removed and in the same operation any inequality in thickness may be corrected by turning or grindin For t is purpose a clamping forme may be employed composed of two semi-circular concave members provided with a flange at one end by which it may be clamped to the face plate of a drilling or similar machine. The cylinder is now enclosed in thisforme and the two semi-circular concave members are drawn up by binding screws until they grip the cylinder sufliciently to prevent its The forme is now clamped on with the grinding or tool head and the plate and forme are graduall moved so that the full length of the cyllnder will pass the grinding or tool head fitted upon the spindle, or the cylinder may remain stationary and the spindle carrying the grinding or tool head may be gradually moved. The cylinder carrying the intaglio image on its outer surface identical in every respect with the image on the master cylinder or original is now slipped over the expanding mandrel for mounting in the printing machine ready for printing.

Where cylindrical electrotypes of exceptional thickness are produced, ll may provide metal filling strips for insertion into the gaps of the expanding mandrel.

When producing relief printing surfaces according to the invention and where the surface of the relief has deep cuts or recesses, the relief mother may be out on two longitudinal lines in diametrically opposite positions with a view to ensure its separation from the final product. Furthermore the outside of the mother may be ground so that the mother may be fitted into a holder adapted to receive it. Thus the inside as well as the outside surface of the mother may have a constant diameter.

It will be understood that in the production of a cylindrical elect-rotype as hereinbefore described, there will be a relief formed on the back of the deposit and this relief will be removed in grinding or turning. Furthermore in deposition the layer is apt to become thicker at the ends and the grinding of the inner surface or the bore of the electrotype may remove the increased thickness'of the ends and render the bore uniform. With a View however to avoid 'the thickening of the deposit at the respec-' tive ends of the electrotype to which the respective connections are made, the anode which in depositing the electrotype upon towards the end or ends and the respective shapes or sizes of the sections of the anode may be determined by trial with a view to ensure a substantially uniform deposit.

In carrying-the invention-into effect ac-.

cording to another modification of method, the original is produced in the flat and a thin and hard metal relief is deposited thereon of such a thickness that it may be bent to a circular shape. This relief is then mounted in hollow circular fo-rmes so that the image ison the inside and so that a complete cylinder or mother is produced of true cylindrical form. A tube of suflicient thickness as hereinbefore described is then deposited as a relatively thin and hard layer within the mother cylinder or relief.

In carrying the invention into effect according to another modification of method in the use of an original in the flat or otherwise, I may produce a mould preferably in lead from the original preferably in the flat and produce a flat electrotype from the lead mould. This flat or sheet electrotype is deposited as a hard layer and to a suflicient thickness as hereinbefore described so that it may be bent into a true cylindrical form. Its edges are soldered, brazed or welded and the cylindrical electrotype produced is finished in the same manner as described according to the first method.

In carrying the invention into effect according to another modification of method, the mould preferably in lead, may itself be formed into a cylindrical shape and a thin and hard cylindrical electrotype produced from the lead mould, the product being then finished as before. It will be understood that this modification is not preferred-for fine work. I

I claim 1. A method of producing a jointless cylindrical electrotype printing surface, comprising the production of a flexible cylindric-al mother of'relatively thin, hard and dense metal b electrotyping from a cylindrical origina, splitting and stripping the mother from the original and using the mother as a mould, substantially as described.

2. A method of producing a jointless cylindrical electrotype printing surface, comprising the production of a flexible cylindrical mother of relatively thin, hard and dense metal b electrotyping from a cylindrical origina after the exterior surface of the original has first been treated for the. ready separation from it of the mother without injury or loss of definition, splitting and stripping the mother from the original and using the mother as a mould, substantially as, described.

3. A method of producing a jointless cylindrical electrotype printing surface, comprising the production of a flexible cylindrical mother of hard and dense metal by elect-rotyping from a cylindrical original, the metal being sufficiently thick to permit of the mother being self-supporting but sufliciently thin to be incapable of permanent distortion on release from the original,

splitting and stripping the mother from the original and using themother as a mould, substantially as described.

4;. A method of producing a jointless cylindrical electrotype printing surface, com.- prising the production of a flexible cylindrical mother of relatively thin, hard and dense metalby electrotyping from a cylindrical original, splitting the mother from the original and stripping the mother from the original by pouring hot liquid over it, and then using the mother as a mould, substantially as described.

5. A method of producing a jointless cylindrical electrotype printing surface, comprising the production of a flexible cylindrical mother of relatively thin, hard and dense metal by electrotyping from a cylindrical original, splitting the mother by cutting on a longitudinal line, stripping the mother from the original and then bringing together into alignment and contact the edges of the-mother at the part at which it is cut and securing the edges together temporarily, then using the mother as an electrotyping mould, then disconnecting'the edges and stripping the mother from the electrotype produced, substantially as described.

6. A method ofproducing a jointless cylindrical electrotype printing surface, comprising the production of a flexible cylindrical mother of relatively thin, hard and dense metal by electrotyping from a cylindrical original, splitting the mother by cutting on a longitudinal line, stripping the mother from the original and then bringing together into alignment'and contact the edges of the mother by the use of solder at the part at which it is cut and securing the edges together temporarily, then using the mother as an electrotyping mould,

then disconnecting the edges and stripping the mother upon a holder and using the mother as a mould, siibstantially as described.

8. A method of producinga' jointless cylindrical electrotype printing surface, comprising the production of a flexible cylindrical mother of relatively thin, hard and lindrical electrotype printing surface, comprising the production of a flexible cylindrical mother of relatively thin, hard and dense metal by electrotyping from a cylindrical original, splitting and stripping the mother from the original, then mounting the mother upon a support and depositing the jointless cylindrical electrotype printing surface Within the mould after first treating the inner face of the mother so that the jointless cylindrical printing surface may be separated from it Without injury or loss of definition, substantially as described.

10. A method of producing a jointless cylindrical'ele ctrotype printing surface, comprising the production of a flexible cylindrical mother of relatively thin, hard and dense metal by electrotyp-ing from a cylindrical original, using the mother as a mould and then splitting the mother and stripping the mother from 'the original by pouring hot liquid over it, substantially as described.

11. A method of producing a jo-intless cylindrical electrotype printing surface, com-' the inner surface of the jointless cylindrical electrotype printing surface stantially as described.

12. A. method of producing a jointless cylindrical electro'type printing surface, comprising the production of a flexible cylindrical mother of relatively thin, hard and dense metal by electrotyping from a cylindrical original, mounting the original with the mother upon it Within a machine tool for grinding or machining the exterior of the mother, splitting and stripping the mother from the original, and using the mother as a mould, substantially as described.

13. A cylindrical electrotype mother of hard, dense and flexible metal sufficiently thick to be self-supporting but sufliciently thin to be incapable of permanent distortion on release from the original or from the electrotype produced therein, substantially as described.

produced, sub- JAMESA-LBERT COREY:

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