US2508902A - Apparatus for helically coiling flat metal strips - Google Patents

Description

y 23, 1950 N. H. BOLZ 2,508,902

APPARATUS FOR HELICALLY COILING FLAT METAL STRIPS Filed July 22, 1948 INVENTOR. NORMA/V H. 504,2

ATTO/EK/EXS.

Patented May 23, 1950 pasoapoz AI PARATUS FOR HELICALLY COIIIING if; .JMETAL STRIPS FLAT NormanjiH. Bclz, Euclid, omb, asslgnorto" The Paterson -L'eitch" Comp: corporation-of Ohio I ny, Cleveland, Qhio, a V

Application July 22,=1948,.Serial hi0. 40,176,,

3 Claims. (Cl. 153'.64;5

11 The present improvements, relating generally as indicated, to the helical coiling of. flat metal strips,. have more particular. regard to the. coiling'of relatively wide thin strips on edge for forming the heat radiating fins or ribs, on heat. ex-

change tubes and the like. p

Generally, helical coiling of wide. thin. strips on edge to a relatively small diameter has been regarded as aratherdifficulttask involving, either transversely corrugating the strippriontowrapping it aroundan arbor. or onto the tube to which A itisto be ultimately permanently. fixed, or wrapping the strip whileit is ina heatedconditionand tensioning thesame. to preclude. wrinkling or. buckling at the edgev constituting the inneredge. of the coil or-transverselyslitting.the stripfrom.

the edge constituting the outeredge of the coil to be formed therefrom. Cold wrapping has.

been considered practical only in caseswhere the radius, of bending is large relative to the width,

of the strip.'

Accordingly, it isa pr ncipal object;

vention to provide a unique apparatus wherewith wide thin metal strips may be helically coiled on. edge and to a relatively smallpitch-and-diameter without priorcorrugation .or heating and .tem

sioning, thereby effecting. substantial economies.

in the manufacture thereof.

,Another object is to provide an. apparatusbywhich coils may be consistently made to a high degree of accuracy whereby to,have, awsnug. fit

with the outer surface of thetube. to which the coil is subsequently adapted-to besecured .as by a welding or likeoperation.

Another objectis to provide an apparatusen-, abling production .of edge ,coiled strips without wrinkles and other imperfections and in which the outer and inneredges arenotperceptibly.

changed .in thickness as a result ,of the coiling operation. p

Another object, is to provide an apparatus in which the entire periphery of the transverse cross section of the strip at the. point of bending is confined against distortion whereby to attain the aforesaid advantages.

Other objects and advantages will: become ap; 7

parent as the followingrdescription proceeds.

To the accomplishment of the foregoing and related ends, said invention, then, comprisesthe features hereinafter fully describedand particularly pointed out .in the claims, the following description and the annexed drawinglsetting forth, in detail'one illustrative embodiment. of the invention, this being indicative, however, of but one of the various Waysin which jthe prin'iple of the invention may be employed.

. n said-annexed. drawine .7

Figs. 1 and 2 are diametral cross section views of. typicalhheat exchange tubes having helically coiled-,stripsof thetypeformedby the present 7 method and apparatus welded thereonto; ,Fig. 3 is atop plan viewiwith the top bearing block removed). of a preferred apparatus, for helicallyicoiling a fiat strip of metal on edge, said apparatus being illustrated in its starting posi- ,Fig., 4 is a crosssection viewtaken substane tially along the line 44, Fig. 3, illustrating the apparatus in a position with a portion of the strip formed, into. a .coil; and 7 Fig.5 .is-a view similar to 3 eXceptillushating the apparatus in a condition for stripping the finished coil therefrom.

Referring now to thedrawing and first more especiallytoFigsl and zthereof there is shown therein a tube I having a. helical fin or rib 2 weld- 'ed.,ther conto as indicatedbythe numeral 3,;

said fin being welded on one side only in Fig. l and on both sides in Fig. 2. Said fin 2 preferably comprises a metal. strip, usuallysteel, helically coiled on edge so as to provide relativelylarge areaheat radiating surfaces, Formation of the heat exchange tube assembly in this manner is obviously. preferred over casting the same or machining a helical groove in a thick wall tube or welding separatewashers in axially spaced v relation onto a tube. To further render the formationpf heat exchange tube assemblies in the preferred manner indicated above in a yet, more feasible manner, thepresent invention has to do with the formation of the helical coil component of the assembly in a most simple and expeditious 50. reversible driving means (not shown). The roll flhe coiling apparatus illustrated in Figs. 3, 4, and 5 cor npri ses a base structure 4 including a vertically: extending plate member 5 provided with a fixed transversely projecting bearing block 6 at its lower end and a removable bear-p ing block 'l at its upper end held on p1ate5 as by' ti'lQ'bQll} 8. Journalledin the, bearing blocks Band rare the reduced ends of 'a pair of parallel steel rolls 9 and Ill which have their outer cylin drical surfaces substantially in contact or at least very closely adjacent one another. The roll 9 hasits "lower-end ti -projecting throughthe'g bearing block 6 for connection to any suitable H i le ollo r r 1 .fr rotatable in the. flll s. 3. 691 e dthe q The driven roll is iorrnedwith ,aphelical groove litherin of desiredgpitch' corresponding with that'of "the coil to be formed, such groove having The strip 's which isto be coiled.,is .attached to the roll 9 as by a bolt l3 projecting through a hole long heat exchange tubes, the coils are made in relatively short lengths and positioned end to formed in the end of the strip and threaded into,

the top convolution in roll 9 as best shown in Fi 4.

The strip S may be taken from a coil or maybe. in the form of a straight sectiomoi conyement,

length.

With the strip S attached to roll 9 and its free end unconstrained, the roll 9 is d r ive rr in the direction indicated by the arrow in Fig; 3 where-f upon the strip is caused to be wrappedinto the;

helical groove 12 by the pressure exerted against the outer edge of the strip,by r911 10, It is to be noted that at thepoint. o'fb'ending oi the strip andpressure application thereon the entire periphery .of. the transyerse eross section thereat is confined inacavity'oi thesai ne silzeL and shape definedby ,theuthr eewalls of thej groove l2 al ong opposite side sland at the inner edge of the strip.

and the outer wall of roll; lll at thetouter. edge V e ia he s' re w n e tri d, roll In causes the latter to rotate in the direction.

of the arrowin Fig. 3,,withouts1idi2 ,friction with the ,strip, such irotatio n'being a't same,

speed as; roll 9.. 7

With the above arrangement it has been dis;- covered :thatbthe coil formed lirithe' helical groove l Z of .roll 9; is .rree fromlwri lkls and other flaws,

Also, because the strip Siscpntined tovrtitangu lar radial crossv section therei's noi 'opportunity for thickening: at the, inner edge and; thinning at the .outer "edge. Inpractice it is desirable to.

apply a suitable lubricant ontof opposites'ides of the strip to, facilitate;forcingitherept into. the helical. groove, [2, and removing of the finished coil from thev grooves When. the coil is, of, desired axial length or, when the free endof thefstripfil iswithi'n a. few' inches frorn rolls i and. I0, thedriven, roll 9 is stopped wherebyftoleave anfuncoil'edtail end 14 5 on the, strip." The top, bearing, block 1 i and, belt. l3 are, then removedand,thej'roll, 9,;driven] inra reverse, direction as indicated by the arrow.

in Fig. 5,, whereupon the tail: I Q. of. the strip engages. plate, 5, the; finished-- cqil thus unjthreadi ing and risingaxially -irpm; roll- 9. "Thetail end l4 ,and the other, end oi theicqil are. their trimmed. 011 and the. coil v slippedover a tube, Fahd jvvelded' thereontoj With a coil'made as justdescribed, there is no perceptible spring back in th'e strip whereby the root diametercoi -the helicaLgrooi/e, I2 in roll Smaybeequ'al to the,diar etejr'.v of the; tubes! so astoionma coillhavingasfnug fit over,

said tube. and. thus establish good heat: confdncting contact;betvveen thefcoil, and, tube,

With the present, invention itlis a versasimple, matter to coil relatigelywideltl'iiri stripsgoj metalto unusually smalldiameter. and pitch without the supaementary heating, "r asoning, slittin or corrugatin operationsheretoforejregarded as imperative to the satisfactoryproduction 'of small diameter edge coiled widefthin. strips", For. example, in the practice of, the? present invention hot rolled steelstr %;.'xfl%ff andlf it 1 4' have been formed'ifnto coils o'ff2 5' insidegdiameter, and /2 pitch without uiaasu'at attendant difficulties and without requiring, any of, the aforeaisi' surnames? iere 1' the as 15 end on the tube, the ends being welded to ether if desired. With the particular apparatus described the rolls 9 and ID if longer than about three feet, require intermediate supports against bending.

"Other modes of applying the principle of the invention ma be employed, change being made asregards the details described, provided the features statedginlanymof the following claims, or the equivalent of such, be employed.

I thereiorepar 'eularly point out and distinctly claim a'sjn'y'inl n:

"lg-Apparatus; r, coiling fiat metal strips on edge comprising a base, a pair of parallel rolls meiudmg'""cy1mdria1 portions of equal length substantially in contact with one another throughout their respective lengths, said rolls hayinared g dvpposite x dsl.iour ailed in a ase; aeosaurma .1 ormed. with an'fexternal: helical groove the reabout ex telridingjfrom orie e nd to'jthe otherv o f jhe cylin width and radial depth closelv, cpr e ppnq n f 1 li k e'f swd .l lbr l l si; mea s r pi i c ro ve; "from said; one roll ki lw da a s? d, t iris}. with.thel'transverse, c ss- -s ha w ee-b a edi/ U p es i eIforcinglb l 'firs tini l ghd hei' fwi into such, groti'ye; by ,pressure egiejrteig lgoh an edge of the strip by'theothe'r of said ro'ns, said roll being, driyen by frictional engage rn' h strin andlbeirsx ne a ivetor retain: the ,edr stripf wh n" within suchfgroo e, with] the outer one of -said roll'sbe g driven and'f, i

5 an external helical groove thereabout extending from one end to the other of the cylindrical portion thereof, such groove being of axial width and radial depth closely corresponding with the transverse cross-section thickness and width respectively of a strip to be coiled, means for attaching an end of a strip in such groove so as to extend tangentially from the upper end of the cylindrical portion of said one roll whereby driving of said one roll efiects progressive forcing 10 of the strip attached thereto into such groove by pressure exerted on an edge of the stri by the other of said rolls, said other roll being driven by frictional engagement with the strip and being operative to retain the coiled strip wholly within 15 such groove with the outer edge of the strip substantially flush with the cylindrical portion of saidone roll.

NORMAN H. BOLZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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