US2762149A - Method and apparatus for producing perforated metal webs - Google Patents

Description

Sept. 11, 1956 N. B. Ml-:ARs 2,762,149

METHOD AND APPARATUS Foa PRODUCING PERFORATED METAL WEBS Filed April 27, 1953 2 Sheets-Sheet 1 sept. 11,1956 N. B. MEARS l 2,762,149

TAL WEBS METHOD AND APPARATUS FOR PRODUCING PERFORATED ME Filed April 27, 1953 2 Sheets-Sheet 2 METHOD AND APPARATUS FR PRODUCING 'PERFORATED lvETAL WEBS Numan B. Mears, St. Paul, Minn., assignor to Buckhea- Mears Company, St. Paul, Minn a corporation of Minnesota Application April 27, 1953, Serial No. 351,127 14 Claims. (Cl. 41-9) spection of the work. Such manual operations greatly increase the cost of producing such articles. The present etching resistant coating.

The principal objects of my invention a method Ously etching a predetermined aperture pattern through an elongated metal web whereby the cost of the perfo` rated web is greatly reduced and perforations of precise size or sizes,- accurately located a-re obtained.

A'particular object is to provide treating apparatus of the class described which receives the Web to be etched from a spool determined path under tension While subjecting it successively to suitable preliminary cleaning and then to etching, mask removal and drying treatment and n'ally Winding the perforated web on a spool or reel. continuous treatment may also include the automatic scanning of the perforated web to test for its light transmission properties and variations from a predetermined perforation size requirement.

A further object is to provide an improved method of forming predetermined patterns of perforations in a metal web having exposed areas and masked areas defined by an etching resistant coating, the method comprising continuously moving the web along a determined path and in a substantially vertical plane while causing an etching uid to impinge against the exposed areas of the web uniformly until the ldesired pattern penetrates completely through the web over the exposed areas.

Other objects will appear and be more fully pointed out in the following specication and claims.

Among the articles of 'manufacture which may be produced rapidly at reduced cost by the present invention are aperture masks for television tubes, ne screens for mechanical separation of solid particles, reticles for re control and other precision instruments, electric shaving and clipper heads, Ventilating screens, and other articles requiring precise location of minute perforations in metal For such articles the metal web or sheet is less silver, nickel or tin, as super nickel, are best suited for accurately controlled perforation by etching treatment and the web should Ybe of uniform, thickness and purity. Thin webs of this character are d iiicult to handle because of their malleability, flexibility Iand general tendency to be locally deformed as by wrinkles, creases and other indentations which destroy the accuracy and utility of the product. Moreover, after the photo-printing and development of the pattern or design in the etching resistant coating on duction of tained.

Figure l is a somewhat diagrammatic side elevational View of the apparatus;

Fig. 2 is Ia top plan view of the same;

Fig. 3 is an end view showing the preliminary cleaning and etching apparatus;

Fig. 4 is a cross sectional view taken approximately on the line 4`4 of Fig. 2;

Fig. 5 is an end elevational View of the power driven reel and speed control;

Fig. 6 is a fragmentary cross sectional proximately on the line 6-6 of Fig. l;

Fig. 7 is a vertical sectional View taken approximately on the line 7-7 of Fig. 6, and

Fig. 8 is a side elevational view showing the friction retarding device for the feed reel.

In the drawings the metal web, indicated generally by the numeral 19, is Withdrawn from a spool or reel 11 and passes over the view taken ap- 11 the web 10 carries an etching resistant coating (not shown) defining protected surface areas and 4exposed areas of the metal forming the pattern or design which is to be etched into or through the web. In the event that moved along a determined path continuously. The guide rollers 12 and 13 are preferably provided with rubber covered peripheries for contact with the web. p

As shown in Figs. l and 2, apparatus is provided alongv the path of the moving web for treating it. appa; ratus may comprise a pair of rollers 15 adapted to coat the lower margin of the web as it leaves the reel 11 with 'a protective wax, cleaning mechanism includingpower actuated scrubbing members 16 and 17, water sprays 18,` etching means contained in a chamber 19, sprays 20 for lluid from the web, a chamber 21 wherein a solvent for the etching resistant coating on the web is applied, scrubbing mechanism 22 for remov ing the etching resistant residue, sprays 23 containingl a wetting agent, a drying chamber 24 and an electronic scanning device contained in a housing 25 for testing the light transmission properties of the perforated web at various points.

Preparatory treatment apparatus zontal. then moved between a pair of vertically extending scrub- Y The "scrubbing Y connections'therewith so Y fthem.may be adjusted by angular movement in a planev Vwhich is parallel to the Vof perforation widths is Vof the zweb, as indicated in at oppositegfaces.

tion at an angle of approximately 45 degrees The wax quickly solidies on the web which is bingijmembers 16 and then between similar .scrubbing members 17. Both pairs of lscrubbing members are power actuatedY to'y oscillate invertical planes and are preferably provided'w'ith brous facings for contact with'the web, e.;g.,rfsheep skin with the wool in contact with the web.

providedjwithix'ed vertical guides 26 upon which tubular @members Z7'are slidable vertically. The scrubbing membersare supported are oscillated'relative to the guide members by pairs of Vlinlgs llconnected extending shafts 3Q support and rotate .the eccentric on the tubular members and the latter to eccentric heedsl?. Horizontally heads and 'are operatively connected toV an electric motor 31. As shown'inFigs. l', 2 and 3, a cleaning fluid or tluids is fed to the scrubbing members 16 and 17 through feed pipes 32 and the iluid is collected'in a tray`33 from which it is withdrawn by a motor operated pumpY 34 and circulated through-a pipe extending to the tray 33 and a delivery pipe connected to the feed pipes 32. YSu-itable cleaning fluids for this preliminary treatment of the metal web are those used in the photo-engraving art for de- Y scurnming photographically produced and developed One such iluid comprises a solu-V images on the plates. tion of lnickel-,salts and a Vsaponifying agent to which Yan VV`abrasive. substancesuch as pumice powder may be added. V A Ysuitable permanganate solution may A also be used on the 'scrubbing members 17. The metal web, after passing between the scrubbing members 16 and 17, is washed by passage through water sprays 18 from a pair of nozzles 3,5which v are disposed to direct the water at high velocity obliquely against `opposite sides of the web'shortly before it Venters the etching 'chamber 19. The nozzles-35 are disposed above `a suitable catch basin ,and are shielded by walls 35aand supplied with water through a pipe 35h.

Etching apparatus 'Y My improved etching apparatus includes the spray chamber 19 of generally rectangular shapehaving transparentside and end walls 36, a transparent and removable top 37 and an open toprtank 38 containing aisupplyy of 'suitable etching fluid, e. g., a

of the fric-.quired concentration. Y The metal web to be etched enters and leaves the etching chamber 19 through vertically elongated slots in opposite walls 36. The etchingluid is/.caused to impinge againstV the exposed face orfacesfof the web 10 in the etching chamber by a series of nozzles 39 and 40. The nozzles 39 are spaced Yalong arsupply header 41 and the nozzles, 40 along a similar headerl 42 and both of these headers extend generally along and in parallelrelation to the web 10, the header 41 being at a lower elevation than the header 39. These headers are branches of a supply'pipe 43 and have swivel that the elevation of eachv of exposed face of the Vmetal web 10, indicated in broken lines in indicated inFig. 7, the nozzles 39 are staggered longi-v tudinally of the web relative to the nozzles 40 and the several nozzle oriiices are vertically elongated so that the sprays. indicated bythe numeral l44 impinge against theV web X10 in Y vertically elongated at right anglesto the surface ofthe web. VBy this apparatusand method the sprays of etching fluid lare'distributed uniformly over the face or faces of the web as it movesithrou'gh the etching Vchamber and a controlled rate of penetration ofthe web with resulting uniformity oijetching, the sprays may be duplicated at opposite faces Figs. 2 and 6. VThe etching fluid vis'supplied to the pipes. 43 under the required, efg.

members at each side ol the web areV solution of yferrie chloride 1 Fig. 7. As Y furtherY Y ,These rollers have beveled peripheries and may be' revolubly supported with their axes of rotai to the hori- Y 'members 56 are operated by motor actuated'mechansms Y lweb and a 1not solvent l0 lbs. to 40 lbs.per square a motor driven pump 45 which is supplied through a suction pipe 46 communicating wth the tank 38 containing the etching lluid. During the etching, the progress of the perforatingV operation may be observed through the transparent walls 36, suitable illumination being provided at the side of the etching chamber opposite that wherev the observer is stationed. Y Upon emerging from the etching c amber, the is subjected to the VWater sprays 20 Whichremove the excess etching fluid. Fl `hese sprays are supplied with waterv Y under pressure through a pipeV 47. and are a suitable housing48. Y Y

Coating removal and scrubbing apparatus From the housing 48 the web 10 passes into the cham-V ber 2i wherein it is submerged in a solvent for resistant coating or masking material remaining on the web. Solvents 'suitablepfor this purpose are welllinownV vSome of them are 'applied V in the photo-engraving art. in ay hot'condition, e. g., a 40% solutionwof sodium hydroxide (NaOH) at approximately 200V degrees F. brest shownin Figs. l, 2 and 4, my treating apparatus includes a long, narrowtankv 49 arranged Vto contain the and having verticallyY elongatedV slots in the ends ofthe tank Yfor the passage of the web. These slots are substantially closed by squeegee-likeweb engaging members.

supplied through a plurality of branch pipes V5,0 which feed it into the top of the tank at a rate Vwhich insures the complete submersion of the web inthe solventf The latter is heated through a pipe 52 extending in a tank 51 from which it is withdrawn to a motor driven lCentrifugal pump 53j andthe latter forcesV the vhot solvent'throughv Y a pipe 54 extending tothe branch pipes 50. VTheoverflow,

solvent is returned to the tankSl from the bottom ofthe chamber V2,1,through a pipe 55 (Fig. 4). Y

VFrom the chamber 21'the web 10 passes to the scrubwhich ,removes vfrom residue of the coating and solvent., This scrubb ingrnech-y anism includespairs of Yvertically reciprocating members 56 which are provided Vwith nelexible suitable facing material for'contact with the web V10. The

similar to that hereinhefore described withreference to the scrubbing members Y16 and V17.v A suitable cleaning iluid is Vcontinuously `supplied toV the` members 56 throughbranch pipes 15,7 extendingfroma water ,supply pipe 53- f Wash water Ycarrying ,the coating sprays 18 and patterns and-substantially obtained. For maximum rate V residue is collected inY an beneath thel web 10 and scrubbing members extending beneath the web where it is lsul'iectY to the 20. Y After passingebetween pairs of the scrubbing 'members 56 the web 10 is sprayed withasuitable lwettingfagent, Y

such as the common photo ow solution.' Y'This,solution is applied tothe workv by the spray pipes23 whichare supplied with a solutioniof thewettingagentfroma pipe 62. extending to a motor driven pump 63 and the latter is supplied' from' a tank 64 v,extendingbeneath 'the web 'to receive the solution' from thelower edge thereof. lThe thoroughly cleaned web then passes through the drier chamber`24 wherein'warm dry'air iszblown against'the web surfacesiby a suitable fan. i'

As the nal treatment, the scanning .chamber 25 containing an electronic :scam ning'devicewhich detects iandindicates defectsfifany, in particular units comprisingthe several portions of the web. A defect Vmaybe indicated when the perforations in Vany portion ofthe web Vvary from a predetermined de Y sirablesize, as indicated by vitslight transmissioncharac4 teristics. i Y i' Finally, tlielweb is guidedby ihe roller r143 to the reel 14.Y Thsreel comprises aspool which is fixed 'on'.aver.-

tical shaft 6775 and the later is adapted to'be continuously inch, pressure by-means-of vweb 10 contained in the etching.A

The liquid Vsolvent 1s continuously Y Y bristlesY or other the working ffaces .of

elongated `iank6l) 'extending 5h6-and also Y the :dried .webVY passes Y rotated through speed reduction gearing in a housing 66 and a belt drive extending from an electric motor 67. 'Ihe belt drive is preferably of the V type having a speed control pulley 68, the sides of which are relatively movable, one to and from the other, under control of a lever 69 whereby the rate of movement of the web to the power-driven reel 14 may be adjusted. Suicient tension is maintained in the web as it passes from the reel 11 to the reel 14 to maintain it in substantially straight line movement in a substantially vertical plane. Suitable retarding friction is created largely by the weight of the web carried by the reel 11 which rests on a friction support 70 and'by a brake indicated generally by the numeral 71 (Figs. l, 2 and 8). This brake has an arm 72 which is iixed at one end on an axial shaft 73 and carries a friction shoe 74 confined on a vertically movable bolt 76 carrying the shoe on its lower end. The pressure applied' by the shoe is adjustable by means of a set screw 77 connecting the arm 72 to the shaft 73 which is xed against rotation. Some additional frictional resistance to the movement of the web is caused by the scrubbing members 16 and 17 and 56 and, to a lesser extent, by the squeegee Contact members carried by the ends of the solvent tank 49.

The rate of Having described my invention, what I claim as new and desire to protect by Letters Patent is:

l. The method of forming predetermined patterns of perforations in a thin elongated metal web having exposed areas and masked areas defined by an etching reto impinge in the form of uid pressure induced line sprays against the exposed areas of the moving web equally at all points along each longitudinally extending elemental area of the web until the desired pattern penetrates completely through the web.

2. The method according to claim l wherein the metal web is maintained under tension and in the same substantially vertical plane during its movement along said path.

3. The method according to claim 1 wherein the respective sides of the web have registering areas of etching resistant coating and the etching uid is applied in the form of sprays simultaneously to both sides of the web.

4. The method of forming predetermined patterns of perforations in a thin elongated metal web having exposed areas and masked areas dened by an etching resistant coating which comprises continuously moving said web endwise along a determined path and maintaining it under longitudinal tension and ina substantially vertical plane while causing an etc 'ng uid to impinge against the exposed areas of the web uniformly and repeatedly until the desired pattern penetrates completely through the web, and then removing the etching resistant coating from the web while it is in continuous motion along said path.

5. The method of forming a predetermined pattern of perforations in a thin elongated metal web having exposed areas and masked areas deiined by an etching resistant coating which comprises continuously moving said web endwise along a determined path and with one longitudinal edge above the other while successively applying an etching uid from a plurality of sources to a multiplicity of longitudinally spaced exposed areas of the masked areas defined by an etching resistant coating' treating apparatus comprising, means for supporting the web in a substantially vertical plane and with one longi Y tudinal edge above the other, means for maintaining the web under tension and for moving it continuously along web disposed successively along said path.

8. For a thin metal web having exposed areas and masked areas defined by an etching resistant coating, treating apparatus comprising, a roll having a substanoperatively connected to said reel for winding the web thereon and for moving the web along a determined path, friction means for retarding the withdrawal of the web from said roll, an etching chamber disposed to receive the web from said roll and to contain a portion of the web in its movement along said path toward the reel and spray means disposed in said chamber to deliver streams of etching fluid against the exposed areas of the web therein uniformly.

9. For an elongated metal web having a succession of longitudinally spaced exposed areas and masked areas ber having vertically elongated openings at opposite ends for the passage of said web into one end of said chamber and out from the opposite end thereof, means for continuously moving said web with one longitudinal edge above the other longitudinal edge longitudinally through said openings and chamber at a controlled and etching means operative within said chamber to cause through said chamber.

l0. For a thin elongated metal Web having exposed areas and masked areas defined by an etching-resistant coating, treating apparatus comprising a roll carrying a supply of the web to second chambers spaced along said path and disposed to successively receive the web from said roll, etching means operative in said rst chamber to apply etching fluid to the exposed areas of the web successively, means in said second chamber for applying to the etched web a solvent for the etching-resistant coating, and poweractuated means operatively connected to said web for continuously moving it at a predetermined speed successively through said first and second chambers, the duration of the treatment of the successive areas of the web being determined by the rate of movement thereof through said chambers.

ll. For a thin elongated metal web having exposed areas and masked areas defined by an etching-resistant Y 7 coating; treating'apparatus comprising, a rollrcarrying a supply'of the @web to be treated, means for guiding the web 'from said roll along a determined path, rst and second'cl'iain'bers spaced along said path and disposed to successively receive the web yfrom saidroll, etching means t operative in said first chamber to apply etching Yfluid to ,the exposed areas of theV web successively, means in said secondA chamber for applying to the etched web a solvent for the etching-resistant coating,V cleaning means for re- 'moving the coating and excess solvent from the surfaces ofthe ,movingweb,- driving .means for the web engaging vit ata positionspaced along sadpath from the cleaning means, and power-actuated means operatively connected t to saidV driving means Vfor continuously moving the web at a predetermined speed successively 'through said first and second chambers and then totand beyond said cleaning means..

12. For anielongate treating apparatus comprising, means for supporting said t blank for longitudinal movementalong a determined path with a face of the blank exposedpforV treatment, cleaning means including power actuated scrubbing members-and sprays disposed to clean saidv face of the blank in its movement Valong said path, etching means operative to cause etching fluid to impinge against the i cleaned face of the blank during its movementalong said path andmeans for continuously moving said blank'along said path at al controlled rate of speed whereby the duration of the cleaning and etching treatment is determined by therate of travel ofthe blank along said path.

13. rlhe method of forming predetermined patterns of periorations in an elongated thin rnetal web having a blank having exposed areas and' Vmasked areas defined Vby an etching resistant coating,

succession of longitudinally spaced exposed areas land masked areas ,dein'ed' by an'etching-resistant coating which ycomprises,continuously moving said web in a substantially ver-tical'plane vvith one longitudinaledge Vabove the other Vlongitudinal edge, iat a Ycontrolled velocity endwise through andthen out of anetching zone While causing an etching fluid to vimpingeaganst .the exposed areastof the moving web equally at all points along eachelemental longituclin'alY Yarea thereofV untilY the ,patterns penetrate completely through the web and continuouslyf removing the remaining etching resistant `coating from the successive etchedtareas Vupon the passage of the Yweb t from the etchingzone;

zone and then through and out of 1an etching zone and cleaning the snccessive'exposed areas ofV the blank Whilel in the cleaning zone vMild applying aneetching ud to said exposed areasof the blank forthe perodf time required for -the'passage of each of the successive exposed areas through the etchingrzone.

References Cited in the le of thisrpatent: UNITED .STATES PATENTSV Powers V 1 Aug. 2K8, 1951` Y

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