US2372118A - Coating apparatus - Google Patents

Description

Mardi 20 1945. T. J. RADCLIFFE 2,372,118

COATING APPARATUS Filed April 2:5, 194s' :s sheets-snm 1 T. J. RADCLIFFE COATING APPARATUS 5 Sheets-Sheet Filed April 23, 1943 Aww March 20, 945. T 1 RADCLlFF-E 2,372,118

GOATING APPARATUS Filed April 23, 1945 3 Sheets-Sheet 3 Fig 4. i @Z His Aftftoneg.

Pnenfea M.r.zo,1s4s Y ooA'r'mG APPARATUS Thomas J. Radcliffe, Belleville, N. J., assigner to General Electric Company, a corporation oi' New York Application April 23, 1943, Serial No.' 484,219

` Claims.

My invention relates, in general, to apparatus for applying coatings to electrically conductive strip and similar material. More particularly, my invention relates to apparatus for applying a coating of glow-preventing material to selected portions of a metal strip from which' glow lamp electrodes are to be later punched. The present application is a continuation-impart of` my prior United States application Serial No. 449,027, filed June 29, 1942.

Glow discharge lamps comprising closely spaced electrodes mounted within a sealed envelope-are well-known in the art. A species of such lamps comprising two spaced, juxtapositioned electrodes shaped as quadrants of 'a hollow sphere and so arranged as to jointly present a hemispherical surface is disclosed in United States Patent No. 1,965,586, issued July l0, 1934 to T. E. Foulke. This patent also discloses the use of aluminum or aluminum oxide, among other materials, for excluding the glow discharge from the inner surface of the electrodes and confining comprising-my invention; Fig. 2 is a section on theline 2 2 of Fig. l; Fig. 3 is a, forward end view of the guiding and feed means of the apparatus comprising my invention as viewed fromv the line 3 3of Fig. 1; Fig. 4 is a longitudinal vertical section through the coating applicator means and associated parts, the section being taken on the line 4 4 of Fig. 3; Fig. 5 is a top view, partly in section, taken along the line 5 5 of Fig. 4; Fig. 6 is a vertical section taken on the line 6 6 of Fig. 1; and Fig. 7 is a diagrammatic i wiring diagram showing the arrangement for said discharge to the outer hemispherical surface thereof. Heretofore the aluminum or aluminum oxide, hereinafter calledanti-glow material, has been painted on the inner surface of the electrodes by hand with a small brush. This is a slow, expensive method not suitable for mass production, and one in which complete and uniform coverage of the desired surface is not always obtained.

'Ihe prior application mentioned hereinabove relates to the method of manufacturing such electrodes or cathodes while the present application relates to apparatus for applying the antiglow material to a given portion of the metal strip out of which the electrodes are to be shaped or punched.

One objectof my invention is to provide apparatus for applying a. coating to a given surface area of electrically conductive strip material or the like.

y Another object of my invention is to'provide out impairing the ductility of the metal supportl passing electrical current through the coated metal strip.

Referring to the drawings, the machine there shown comprises vertically spaced supply and collector reel holders I0, II, respectively, rotatably mounted on an upstanding support bracket I2 rigidly-secured to an inverted channel iron I3 bolted to the table portion I4 of a stationary stand or bed member I5. The two reel holders I0 and II each comprise a pair of flanges or discs I6, II between which supply and take-up reels or spools I8, I9, respectively, are held. The supply reel i8 on the lower or supply reel holder I0 is provided with a coil 2II of the metalstrip material 2|- to beprocessed 'or coated, and the said metal strip 2| is drawn or pulled through the variousparts ofthe machine and then wound up on the take-up or collector reel I9.

As shown in Fig. 2, the. two flanges I6, I1 of each reel holder I0, I I are mounted on vertically-spaced horizontal shafts 22, 23, respectively, which are journaled in bearings 2l on the support bracket I2. The flange I6 of each reel holder I0, Il is threaded onto its respective support shaft 22 or 23 and is locked in position against rotation thereon by a nut 25 threaded on the said shaft and screwed uptight against the flange.. Each of the threaded anges I 6 is provided with a small concentric boss or centering hub 25 on its inner side for centering the reels or spools I8, I9 in the reel holders I0, Il. The other flange Il of each reel holder I0, II is slidably mounted on its respective support shaft 22 or 23, the flange Il of the lower or supply reel holder I0 being held in position on the shaft 22 by a retaining nut 21 threaded -on the shaft 22 and locked against ro,-

tation by a second or locking nut 28 threaded on the said shaft and screwed up tight against the retaining nut 21. The said flange I1 of the supply reel holder Il) is so positioned on the shaft 22 as to hold the supply reel I8 loosely between the two flanges I6, I1 so as to permit free rotation of the said reel on the reel holder I0. The flange I1 of the upper or collector reel holder Il is continuously urged against the collector reel I9 thereon byaI compression coil spring 29 tting over the shaft '23'outwardly of the ange I1 and compressed between the said ange and a retaining nut 30 threaded on the shaft 23. The said re- `taining nut 38 is locked against rotation or unloosenlng by a second' or locking nut 3i threaded on the shaft 23.4

Thecollector reel holder II and the collector reel I9,mounted thereon are rotated in a clockwise direction, as viewed from the front of the machine .(Fig. I), by suitable means, as by an electric motor. 32 connected through a speed reducer 33" to the shaft 23 of the collector reel holder II. 'Ihe electric motor 32 and speed reducer 33 are xedly mounted on the machine stand or base I below the table I4 thereof and are interconnected by a belt 34 and pulleys 35, 36 on the motor and speed reducer/ shafts 37, 38, respectively. The shaft123 of the collector reel holder I I is driven by the speed reducer 33 through suitable drive' means, such as by a roller chain 39 and sprockets 40, 4I on the rear ends of the speed 'reel holder Il may be considered as forming a friction or slipping clutch for driving the take-up reel I9.

As shown in Fig. 1, the metal strip 2l is continuously unwound from the supply reel i3 by a pair of motor-driven feed rollers 4 2, 43 which feed the metal strip'to a coating applicator device et comprising a coating pot or tank 45 mounted on the channel I3 and containing a bath d6 of the coating material (such as aluminum paint) tobe applied to the metal strip. As the metal vInasniuchv as the take-up reel I9 is thereof. The said feed rollers 42, 43 are preferably made of rubber and are provided with shafts 55, 56, respectively, which are journaled in bearings 5'I in the support bracket arms '52. The feed rollers are driven by the speed reducer 33 through suitable drive means, such as by a roller chain 58 and sprockets 59, $0 on the speed reducer shaft 38 and the upper feed roller shaft 55, re-

spectively. The lower feed roller 43 is rotated ln a direction opposite to that of the upper feed roller 42 by means of similar intermeshing spur gears 5I, '52 on the feed roller shafts 55. 56,'respectively.

Following its passage through the feed rollers d2, 43, the metal strip 2i is next drawn under a front guide roller 63, thence over a coating applicator roller E4 which runs in the bath 46 of coating material, and then under a rear guide roller 55. The front and rear guide rollers 63, 35 are rotatably mounted on horizontal pins or shafts 66 supported in ears 67, 61' on the coating pot 45 and are formed with annular grooves or channels 58 (Fig. 5) corresponding in width to the width of the metal strip 2l so that the said strip is received therein as it passes under the guide rollers 63, 65. The grooves 68 in the said guide rollers thus serve as guideways for laterally centering and directing the metal strip 2l over the applicator roller S4. To permit the interchange of the guide rollers 6.3, 35 with other strip 2l is unwound'from the supply reel t8 by n the feed rollers '42, 43, it is first drawn under a guide roller 4! rotatably mounted on an upstanding U-shaped support bracket 48 fastened to the channel I3, the guide rcller 4l being mounted between the upstanding arms of the said bracket.

Fromthe guide roller 4l, the metal strip 2l is then drawnv inasubstantially horizontal direction by the feed rollers 42, 43 through lateral guiding means 'in the. form of a. pair of laterally spaced guide plates or fingers :39, 49 (Fig. 3) between which the metal strip passes. 'I'he said guide fingers 49, 49 extend at rightl angles to the metal strip andfhave their inner.opposed ends notched, as indicated at 5o, to provide a guide-v and proper guiding of metal strip of different widths, the roller support pins 8E are removably mounted in place in the support ears 6 1, 61', as by set screws 69 for instance.

The applicator roller 64, which maybe made of steel or which may have a steel surface, is rotatably mounted on a pin or shaft i0 having a head '1I at one end thereof and journaled in bearings 'I2 in the coating pot 45..i The said roll-` er 54 is formed with a :dat edge or face 'i3 narrower than the width of the metal strip 2l so that it applies an even coating of the coating material or aluminum paint 46 along the center portion of one side only (the underside) of the said strip as the strip is drawn over the applicator roller 84.

To permit the interchange lof the applicator roller 64 with other rollers having faces 7130i holds the head II of the pin against the outer side of the coating pot 45, thus locking the pin in place in its bearings 12. By moving the spring ill about its pivot point so as to clear the end of the pin 1t, the said pin can then be slid out of its bearings I2 and a different sized applicator.

roller 64 substituted for the one theretofore in use.

The metal strip 2l is continuously pressed down against the applicator roller 54 by a pressure roller 18 so that minor deviations in the flatness of the strip do not result in uneven coating thereof. The said pressure roller 18 is preferably made of soft rubber and is rotatably mounted on a weighted lever or arm 11 pivoted on a pin 18 which is supported on the arms 82 of the feed roller support bracket The free end of the said lever 11 is provided with a ldepending U-shaped bracket 18 which supports a pin' or shaft 88 on which the pressure rol-ler 18 isl rotatably mounted. A weight 8|., fastened to the lever 11 (as by bolt 82) at a point adjacent the free end thereof, insures the exertion of sutilcient pressure on the metal strip by the pressure roller 18 to causev the applicator roller 84 to rotate as the strip passes over it, thus bringing up a constant supply of the coating material from the bath 48 for application to the continuously Y moving strip.

'I'he face 13 of the applicator roller 84 is made slightly narrower than the strip 2l to be coated so as to leave a narrow uncoated portion at each side of the strip, thus avoiding any-possibility of the applied coating material 83 creeping or iiowing over the edges of the strip onto the other side thereof. To insure the application of the coating material 46 to the strip 2i only up to the width of the roller face 13 and in an even amount, the excess coating material carried up by the applicator roller 84 is removed from the face 13 and sides 84 thereof by a wiper plate or blade 85 pivoted at one end on a pin 8B supported on the coating pot ears 61 and resting at its other end on the face 13 of the applicator roller.` The free mounted on the stand I8 while the intermediate or second contact 88 is connected to the midpoint of the secondary 88, as indicated in Fig. 7. The primary 88 of the transformer 81 is connected across the terminals of a suitable source of alternating current, such as a 22o-volt, 60 cycle current source. I have found that a current of about 50 amperes through the ever-changing coated portion of the metal strip 2| bridging the contacts is effective for heating the said portion sufficiently to produce `an adherent, uniform baked-on coating of aluminum paint on a nickel strip having. a width of approximately inch and a thickness of approximately 0.810 inch when the speed of movement of the strip 2| over the contacts 88, 88 and 88 is such that a given point accomplished, according to the invention, by

drawing the coated strip tightly, coated side out, over a seri of three vertically-spaced stationary contact drums 88, 88 and 88 whereby the uncoated side of the metal strip makes electrical contact withthe said drums. The contact drums 88, 88 and 88 are mounted on, and insulated from, an upstanding support bracket or channel iron 8| fastened to the channel iron I3 on the table |4. As shown inFig. 6, each of the said contacts 88, 88 and 88 are secured to the channel 8| by a bolt 82 and are insulated from the channel by a flanged bushing 83 and a washer 84 both of suitable insulating material, preferably a plastic such as that commercially known as 'Iransite. To prevent the metal strip 2| from sliding or creeping oi the contact drums 88, 88 and 88, each of the said drums is' provided with out-turned annular anges 85 at each side thereof which serve to guide and hold the metal strip in place A transformer 81 capable of changing a 22o-volt current supply of commercial (S0-cycle) frequency to 2.5 volts between the midpoint and the opposite ends of the secondary .88 is suitable for the above purpose.

While the center contact 88 and its connection to the transformer secondary may be omitted, I have found that it minimizes sparking at the end contacts 88 and 88 and is therefore desirable. Furthermore, the said center contact 88 avoids overheating portions and underheating other portions of the metal strip 2| at the beginning and at the end of a run. At such times, the machine is stopped and current passed through that portionl of the strip which would not otherwise be suiiiciently cr properly heated. The center contact 88 avoids such undesired temperature distribution and thus eliminates spoilage of material.

After passing over the last contact drum 88, the `metal strip 2| is then drawn over a anged sheave or idler pulley 88 rotatably mounted on a stud |88 extending from the support channel 8|. The said sheave guides the coated strip 2| from the last contact 88 to the take-up or collecting reel I8 onto which the strip is then wound.

'I'he drive connections for the feed rollers .42, 43 and the collector reel I8 are so arranged that the motor 32, acting through the friction clutch formed by the stationary flange I6 and the spring-pressed ange I 1 of the collector reel holder tends to rotate thecollector reel I8 at' a higher rate of speed than that of the feed rollers 42, 43 and to thus pull the metal strip 2| through the apparatus at a higher speed than the feed rollers vwill allow. Sufncient tension is therefore exerted on the loop-like portion of the. strip 2| between the feed rollers 42, 43 and the collector reel |8 to hold the said strip portion taut and firmly against the electrical'contacts 88, 88 and 88 so as to avoid excessive sparking between the strip and the said contacts.

The strip 2| is continuously passed over and between the contacts 88, 88 and 88 at a rate such that the coating material 83 is thoroughly baked thereon without impairing the ductility of the strip for subsequent fabrication or shaping into articles such as the glow lamp electrodes referred to hereinbefore. 'Ihis rate may be determined by trial runs of the apparatus.

Undue heating of the electrical contacts 88, 88 and 88, particularly the last contact 88, by the hot portion of the strip 2| passing over its surface may be prevented by providing sufficient heat dissipating capacity for the contacts. If the heat dissipating area of the contact itself is not suiiicient for this purpose, then heat radiating the aluminum paint sold by the Sahlin Chemical and Color Company of Camden, New Jersey, un-

' der the designation of No. 2056 Aluminum, is

eminently satisfactory for use as the coating 83 of anti-glow material.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. Apparatus for coating a metal strip with a bakable material comprising in combination, applicator means for applying the coating material to one side only of said strip,'electrical means comprising spaced contacts for engaging with the uncoated side of said strip and for passing electrical energy through said strip to heat it suiciently to bake the coating thereon, and means for moving said strip successively into effective relation to said applicator means and over said contacts. n

2. Apparatus for coating a metal strip with a bakable material comprising in combination, applicator means for applying the coating material to one side only of said strip, electrical means comprising spaced *contactsl for engaging with the uncoated side of said strip and for passing electrical energy through said strip to heat it suiciently to bake the coating thereon, means lor moving said strip successively into effective relation to said applicator means and over said contacts, and adjustable guide means for laterally aligning said .strip with said applicator means, said guide means providing a guide opening of preselectable width to accommodate strip said strip over said applicator roller and thence over said contacts.

4. Apparatus for coating a metal strip with a layer of bakable coating material comprising applicator means for continuously applying the coating material to a restricted mid-portion of one side only of the strip, electrical means comprising spaced contacts for engaging with the uncoated side of the coated strip and -forpassing electrical energy through said strip to heat it sufliciently to bake the coating material thereon, and means for continuously moving said strip into effective coating relation to said applicator means and thence over said contacts, said lastnamed means exerting suiiicient tension on said strip to draw it taut and hold it firmly against the saidcontacts.

5. Apparatus for coating a metal strip with a layer of bakable coating material comprising applicator means for continuously applying the coating material to one side only of the strip,

va plurality of spaced contacts for engaging with -the uncoated side of the coated strip, a transformer having a, secondary connected to said contacts to pass an electrical current through those portions of the metal strip which bridge the said contacts at a given instant, and means for continuously moving said strip into eiective nected to said contacts for passing electrical encoating relation to said applicator means and thence over said contacts.

6. Apparatus for coating a-metal strip with av layer of bakable coating material comprising applicator means for continuously 'applying the coating material to one side only of the strip, a set of threev spaced contacts for successively engaging with the uncoated side of the coated strip, a transformer having a secondaryg the opposite ends of which are connected to 'the first and -third ones of said contacts and an intermedial-.e point ycf which is connected to the inten mediate one of said contacts, and means for continuously moving said strip into eiective coating relation to said applicatorl means and thence over said contacts.

7. Apparatus for coating a'metal strip with a layer of bakable coating material comprising supply and collector reel holders for rotatably supporting supply and collectorreels, roller-applicator means for continuously applying the coating material to one side only of thestrip, feedroller means for continuously drawing the metal strip oi the supply reel and feeding it to said roller-applicator means, a plurality of spaced contacts for enagging with the uncoated side of the coated strip, -a source of current supply connected to said contacts for passing electrical energy through those portions of the metal strip which bridge the said contacts at a given instant to heat the said strip portions suiciently to bake the coating material thereon, and means including a slipping clutch for rotating said collector reel ata speed tending to collect the metal strip faster than it is fed to the roller-applicator means by said feed-roller means whereby suilicient tension is exerted on the coated portion of the strip to draw it taut and hold it rmly against the said contacts. s

8. Apparatus for coating a metahstrip with a layer of bakable coating material comprising supply and collector reel holders forrotatably supporting supply and collector reels, a coating pot containing a bath of the-coating material to be applied to the strip, an applicator roller rotatably mounted on said coating pot to run in said bath of coating material, said applicator roller having an applicating surface of a width less than the width of said strip, feed-roller means for continuously drawing the strip off the supply reel and feeding it over said applicator roller, guide means for laterally aligning said strip with respect to said applicator roller, a pressure roller for pressing said strip into rm contact with said applicator roller, a wiper plate rest. ing on and straddling said applicator roller for removing excess coating 'materialfrom the applicating surface and side walls lof the applicator roller prior to the engagement of said applicating surface withsaid strip, a plurality of spaced contacts for engaging with the uncoated side of the coated strip, a source of currentsupply conergy through those portions ofthe. metal strip which bridge the said contacts at a given instant to heat the said strip portions suiiciently to' bake the coating material thereon, and means including a slipping clutch for rotating said collector reel at a speed tending to collect the metal strip faster than it is fed to the said applicator roller 9. Apparatus for coatinga metal strip with a bakable material comprising in combination, applicator means for applying the coating material to the underside only of the strip while the latter is continuously advanced past said applicator means in a transversely level position, and electrical means comprising' spaced contacts for engagement with the uncoated side only of the advancing strip to thereby pass an electric current through said strip to heatiit suiiciently to bake the coating thereon.

10. Apparatus for coating a metal strip with a bakable material comprising in combination, ap-

plicator means for applying the coating material 1 to the strip while the latter is continuously advanced past said applicator means in a transversely level position, said applicator means applying the coating material to the underside onlyA to thereby pass an electric current through said strip to heat it suiiciently to bake the coating thereon.

THOMAS J. RADCLIFFE.

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