US2246380A - Electrolytic method of producing screens - Google Patents

Description

mMme 17', 1941. E, Q NORRIS 2,246,380

ELECTROLYTIC METHOD OF PRODUCING SCREENS Filed Feb. 19, 1938 3 Sheets-Sheet l ,y C7 DDD/ 75D n Jaune 17, 1941. E ro, NORRIS 2,246,381

ELEGTROLYTIC METHOD OF PRODUCING SCREENS Filed Feb. 19, 1938 5 SheeLS---SheetI 2 INVENTOR June l?, 1941.. E; 0, NQRRlS 2,246,380

ELECTROLYTIG METHOD 0F PRODUCING SCREENS Filed Feb. 19, 1938 3 Sheets-s116912 5 DDDDDDD DDDDDDDDC? l r s f2 Patented June 17, 41941 aziasso ELECTRQLYTIC METHOD OF PRODUCING SCREENS.

Edward 0." Norris, Westport, Conn., assigner to Edward 0. Norris, lne., New Work, N. Y., a corporation of New York ,Application retrasarse. 19st,' serian Nofisiaas Claims.

This application contains matter taken from my application Ser. No. 138.301, filed April 22. 1937, and is a continuation in part thereof.

The present invention has for an object to provide a metallic screen having reinforcements integrally united therewith and also to provide a process for. the manufacture of such screensl or for applying' 'such reinforcements to existing screens.. g

My process is particularly adapted for the production or reinforcement oi' tine mesh screens, although it is not limited thereto but may be applied to advantage in the manufacture of screens of relatively coarse mesh,since the product comlaines strength and a desired degree of rigidity with lightness and economy due to the reduction in weight of metal used.

In the manufacture of tine mesh sheet metal screens iormed by electrolytie deposition of metal, l.

where Vthere are practical limits to the thickness oi metal that can be deposited 'without closing np the apertures, rny process is ot special value as a means of adding requisite strength to the screen.

v lin my eo-pending application Serial No. 52,334, died November 30, 1935, now Patent No. 2,166,366, li describe a matrix comprising a metallic plate formed with a pitted surface, the pits being filled with insulating material to the level oi' said surface, thusmasking or electrically blanidng out dots thereon, so that when metal is deposited electrolytically on the matrix it will form a sheet with an aperture thereinA at each dot. It is found. however, that as the electrolytic process continues the metal tends to grow over the spots of insulation, and if the process is continued long enough, the metal" will close the apertures completely. llt will be obvious. therefore, that with such a matrix the mesh of the screen imposes limits upon the thickness of 4metal that may be deposited, for. as` the sheet grows thicker. the apertures grow smaller.y and, obviously, the spacing of the apertures grows greater. In the case of. very fine screens the sheet may be too fragile or flimsy for practical use, and my reinforcing process is particularly adapted to give desired strength to such fine mesh screens.

A.more specinc object of `my invention is to y form a line mesh screen in the manner described screen as aY wholev is of substantial strength.-

While I prefer to apply the reinforcement in the form of a relatively coarse screen or grid, it is within the purview of my invention to apply the reinforcement in parallel non-intersecting ribs, or, in any other'desired pattern. The reinforcement may he applied to one face only 'of the screen leaving the opposite face .smooth, or, if desired. the reinforcing ribs may project from each surface of the screen.

Other objects andy advantages of my invention will appear in the following description of certain forms of reinforced screens and processes of forming the same, and thereafter the novelty and scope of the invention will be pointed out in the claims.

In the' aecgmpanying drawings:

Fig. l is aview in perspective of part of a`y matrix on which the initial fine mesh screen is to be formed;

Fig. 2 is a similar view showing a fine mesh screen formed onthe matrix by electrolytic deposition of metal;

Fig. 3 is a view in cross-section illustrating a further step ofthe process.v wherein a grid or coarse mesh 'screen is formed on the `tine mesh screen; g

Fig. d is a view in cross-section of the finished screen;

Fig. v5 and Fig. 6 illustrate certain steps of a modified process, Fig. 5 being a view in perspective illustrating one of the steps, and Fig. 6 a view in cross-section illustrating another step in the process:

Fig. '7 is a view in cross-section oi' the screen produced by such modiiiedy process;

Figs. 3 and 9 illustrate certain steps of another modification of the process, Fig. 8 being a view in perspective of part of a speciallyprepared matrix and Fig. 9 being a view in cross-section showing the reinforced screen formedV on said matrix; and

Flg. 10 is a view in cross-section of a screen produced by the process illustrated in Figs. 8 and 9. e

The matrix, shown in Fig. 1, comprises a metallic plate l2 formed with depressions to receive inserts I3 of a material that is an insulator of electricity. The exposed faces I4 of these inserts are flush with the upper face of the plate I2 and are separated by intersecting lanes it of conducting material constituting the exposed metallic surface of the plate l. The present application is not concerned with the manufacture of the matrix which may be formed in the manner described in said copending application Serial Number 52,334. It will be understood,V oi course, that in actual practice the areas ii need not necessarily be square nor so uniformly contoured, as shown in Fig. 1. Actually the areas I il may be of microscopic dimensions and spacing.

The matrix I2 is suitably treated and used as the cathode in an electro-plating bath, whereby metal will be deposited upon the exposed metallic lanes I 5 but not on the surfaces Id. Thus, e. screen will be built up on the matrix, as shown in Fig. 2, composed of intersecting ribs it overlying the lanes I5. The electro-deposition is conltinued until a predetermined thickness of metal is formed, but, as clearly shown in Fig. 2, the deposited metal will form ribs of semi-cylindrical cross-section which, as they grow, must necessarily overlap the surfaces It, and the reduction in size of the apertures in the screen imposes a limit on the thickness of metal that may be deposited.

The next step in the process consists in blanking out areas of the fine screen by printing or otherwise applying thereon spots of ink or other non-conducting material, as indicated at IB in Fig. 3. Each spot I8 covers a large number of the apertures in the flne screen and the spots are separated by bare spaces exposing the metal surface ci the screen. These spaces are preferably in the form of intersecting lanes much broader and much more widely spaced than the lanes I5. The screen thus treated and still on its matrix is again placed in an clectroplating Y bath, and metal is again deposited, this time forming only in the exposed lanes between the flanged out portions I8. The electro-deposition may be continued to such an extent as to build up relatively heavy ribs I9 of sumcient crosssection to provide the desired reinforcement to the screen. The final step in the process is to wash of the ink or coating material I8 and strip the product from the matrix. The resultant reinforced screen will then appear as shown, in Fis. d, comprising a coarse screen portion formed of intersecting ribs I 9 integrally united to the line mesh screen portion formed of the intersecting ribs I6.

In applying the reinforcement to the line mesh screen I prefer to maintain the screen on the matrix. However, 1t will be obvious that the screen may be stripped from the matrix before the reinforcement is applied. InV such case, one face of the screen may be completely blanked out, or both faces may have insulation areas I8 printed thereon, so that reinforcing ribs I9 will be formed on each iace oi' the line mesh screen.

If it be desired to form a screen with a heavier reinforcing the modified process illustrated in Figs. 5 and 6 may be employed. In this modiiied process, after forming the original une mesh screen, as shown in Fig. 2, a layer 29 of a dinerent metal is electrolytically deposited upon the screen, as shown in Fig. 5. After the layer@ has been deposited upon the screen to desired thickness, the surface thereof is printed or other- Wise coated with spots ZI of a suitable resist material, leaving intervening bare spaces exposing the metallic surface of layer in. Each spot 2| covers a. relatively broad area suiilcient to embrace a. large number of apertures ol' the nue mesh screen. The product thus prepared is then e@ l assenso placed in an electro-plating bath and metal is deposited on the exposed areas, building up ribs The next step ci the process consists in reo moving the resist to expose the layer 2B so that r it may be eaten away by a suitable etching duid.

The ribs 22 as `:veli as the ribs it must be formed of a metal that is either immune to attack by said etching uid or oiers high resistance therelo to. For instance, the ribs I@ and 22 may be formed of nickel and the layer 2t of copper.

Suitable etching reagents for etching out the copper layer are (1) a solution of potassium cyanide or (2) a mixture of chromic and sulphuric 16 acids in water, suitable proportions being about as follows:

Sulphur-ic acld pounds s 2 Chromic acid an 1 Wage? Eallnnq 0 2 Neither of these reagents will have any appreinstead ci' eating out the copper` with an etch-L ing uid it may be removed by deplatlng or electro-etching. InV other words, the work is connected .up as the anode in a suitable electroplating bath and the copper that is not protected by the overlying nickel ribs is then removed electrolytlcally.

Another method oi' producing a reinforced fine mesh screenisshowninFigs.8and 9. In this case, the deposit receiving surface of the matrix i2 is machined to form grooves 26 therein, which intersect preferably at right angles to each other, 5 so as to leave islands 2B therebetween. Each island surface consists of a portion of the original matrix surface, comprising exposed metal lanes l5 and insulated surfaces lli. The grooves 25 are out to a depth well below that of the inserts i3.

The matrix thus prepared is now placed in an electroplating bath and metal is deposited on the lanes I5, to form the ribs I 6. 'Ihe electro-plating is stopped when the aperturesbetween the ribs are reduced to a predetermined extent by overlap of the ldeposited metal on the insulated areas I4. This-metal is also deposited in the grooves 25, forming channel-shaped walls 21 running lengthwise and transversely of the screen. Upon the screen thus produced a metal layer 281s then deposited. This metal completely covers the original screen and also forms depressed webs 28 in the channel-shaped portions 28. The surface of layer 28 is then printed or coated with a suitable resist, as indicated at 30. This coating is interrupted by the depressed webs 28 which are left bare.

The next step of the process consists in placing the web in another electro-plating bath to form a third deposit 'of metal thereon. This metal will form only on the webs 2S, and the deposition ot metal is continued until the channelshaped webs are completely filled and the metal has been built up to a desired heightV4 above layer 28, thus forming a grid or coarse screen com- 76 posed of ribs 3|. Thelayer 28 is formed of metal which is soluble in an etching fluid thatV has little or no effect on the metal of ribs I6 and ribs 3|, or which may be deplated without appreciable effect on said ribs. Preferably, the layer 28 is formed of copper, while the ribs I 6, channels 2l, and ribs 3l, maybe made of nickel.

'The iinal step of the process consists in washing oi the insulation 30 and removing the copper layer 28 either with an etching reagent, such as has been already mentioned, or by deplating. Part of the Webs 29 will be protected by the overlying ribs 3| and will provide means anchoring said ribs in the channels 2l. y stripped from the matrix,-producing a finished screen, such as shown in Fig. 10. This,l it will be seen, consists of the original fine mesh screen reinforced by a coarse mesh screen composed of the ribs 30. This reinforcement projects below as well as above the plane of the ribs' I6 which form the'iine mesh screen.

In the following claims the word etching" is used in its broad sense to include the removal of metal either by electro-etching or by iiuids which attack the metal without the aid of electric current. l l

I have described above certain embodiments of my invention and a preferred process with certain modifications thereof, but I Wish it to be understood that these are illustrative and not limitative of my invention and that I reserve the rightto make various changes in forni, construction and arrangement of partsv and also to make various changes in process of manufacture falling within the, spirit and scope of my invention, as set forth in the claims.

l l. A lprocess of reinforcing a thin metallic screen, which comprises the steps of electro-depositing onv the screen a layer of metal that may be selectively etched to the exclusion of the metal ofthe screen, blanking out spaced areas of said layer'withy electric .insulation material but leaving intersecting lanes of bare metal between said areas, electro-depositing in said lanes ribs of a metal resistant to an etching reagent that reacts on the metal of the said layer, removing said insulation material, and etching out all of said layer except narrow web portions integrally connecting said ribs to the screen by means of an etching reagent that reacts on the metal of the said layer but does not react on the material of the screen or the materialof said ribs.

l 2. A process of making a Vreinforced metallic screen, which comprises the steps of electro-depcsiting metal on the surface of a matrix dotted with electric insulation and thereby forming a thin, ilnely apertured, metal sheet, electro-depositing on said sheet ala-yer of metal reactive to an etching reagent that does not react on the material of said screen, blanklng out spaced areas The `work is then y by means of an etching reagent that acts corrodably on the metal of said layer but is substantially inert `with respect to the metal of said screen and the metal deposited in said lanes, and stripping the screen from the matrix.

3. VA process of making a reinforcedvmetallic screen, which comprises the steps of' electro-depositing nickel on the surface of a matrix dotted y with electric insulation and thereby forming a comprises the steps of preparing a metallic matrix with a plurality of electrically insulated dots on a surface thereof, groovingsaid surface to form a plurality of spaced lands, each land including a multiplicity of said dots, electro-de positing metal on said' surface to `form a thinn ymetallic sheet with apertures therein at said dots,

.. protectingA the outer`suriace of the sheet over each of said lands, electro-depositing metal'betwen said lands and thereby forming; ribs Wlthin said grooves integrally connected to said metallic sheet, and stripping the sheet from the matrix.

5. A process of making a reinforced metallic screen, which comprises the steps of forming a metallic matrix having a surface thereof dotted with electric insulation material, grooving said surface to form isolated lands, each land including a multiplicity of such insulation dots, electro-depositing nickel on the matrix to produce a thin nickel sheet with apertures therein at said dots and with channel webs formed in said grooves, electro-depositing a layer of copper onsaid apertured sheet and said channel webs, ap-

. plying a coating of electric insulation on said layer over said lands but not over said channel webs, electrofdepositing nickel ribs on the copper layer over the channel webs, removing said insulation, and etching to remove all of the copper except narrow portions thereof connecting the ribs to, said sheet.

EDWARD O. NRRIS.

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