US1780948A - Method of and apparatus for making conduits by extrusion - Google Patents

Description

Now 11, 1930. -.1. c. EHERMAN 1,780,948

METHOD OF AND APPARATUS FOR MAKING GONDUITS BY EXTRUSION Filed Aug.

"III-Inn m/ZW am a: glam Patented Nov. 11, 1930 ean 0. ennui/IAN,

or scanner, MAINE, Assrenoa tro Bnown coivrrAnY, on NEW HAMIESHIRE, n oon-none'r ox or AIN I Bnnmn,

' METHOD ornn'n ArPAnArus roe. Maxine connurrs BY EXTRUSION' Application filed August 5, 1928. Serial No. 127,260.

This invention relates to articles formed by extrusion, and a method and apparatus. for making the same, special reference being had to tubing or conduit made by extruding a ;plast1c waterproof compound.

to supply a conduit having these and other advantages as will appear from the disclosure given hereinafter. By my invention, I make conduit consisting of fibers with which is incorporated a cementitious or plastic binder preferably of a type which hardens, upon cooling. Any kind of fiber may be utilized such for example as rag or asbestos fibers or a mixture of these with each other or with other kinds of fiber. The plastic binder may con- 510 sist of asphalt, pitch, wax, oilor any equivacially when used with a suitable amount of lent material which softens under the ac tion ofheat or can be vulcanized. I have found that partially oxidized linseed oil is a binder which has excellent properties espefiowers-of-sulphur to harden it. Inorder to obtain maximum qualities of strength, toughness'and durability, I use-from sixty to seventy-five per cent. of asbestos or other fiber 80 combined with forty to twent-y-five-per cent.

of partially oxidized linseed oil. In addition to the sulphur. I also may add a small amount of lamp black to impart a smooth grain and external finish to the conduit.

This materialwhen set can readily be turned in a lathe or threaded. Instead of a thermoplastioor vulcanizable binder, I may use cements, if desired, such cementitious material being suitably mixed with other ingredients to form a thick. plastic mass which can be extruded through an orifice and will hold its shape. With thecement I may mix sawdust, wood flour, crushed coke, or any other finely divided material suitablefor the purpose.

The cementitiousbinder may comprise such substances as silicate of soda and lime which with sawdust will harden into a: water-resistant body. I

y Inmixing the plastic mass of fiber and binder for extrusion, I preferably grind the Face-j T fibrousmaterial, such as old rags or asbestos I mill waste-or the like, on heated rolls with sufficient adhesive material to keep the mass on the rolls. The grinding breaks up the fibrous materialand works the adhesive binder thoroughlyinto the fibers.- More adhesive binder is thenaddeduntil the desired proportions of fiber and adhesive are ob,- tained- This results in a' far morethorough impregnation of the fibrous body With the water-proofing binder than can possibly be obtainedwhere a tube orother object is first made of fibrous material, as forexampleby rolling upa'sheet of paper or byforming a fiber tube directly-from a Fourdrinier roll, and then saturating thedried fibrous tube with waterproofing compound. This is evidenced by the fact that where fibrous tubes are made and subsequently saturated, the sat;

uration is most complete in the "cases where v the fibers constituting the tube have been most completely destroyed in the process of making the tube, as for example where the tube is I made of newspaper fiber or ground wood. I Vhile by my process the grinding of the fibrous material on the rolls destroys the fibers to a small extent, yet the intimate intermixture of'theplastic binder with the fibers during the process of rolling produces a high degree of saturation or-impregnation of the fibrous structure with the adhesive with a relatively small degreeof destruction of the fibers.

- Further advantageous featuresof my in-' scription and on the drawing, of which 2+ Figure 1 is perspective of a length of conduit formed according to my invention.

Figure 2 is a diagrammatic elevation of apparatus for carrying out the invention.

Figure 3 is a sectional detail of a part of the apparatus shown in; Figure 2.

Figure 4 is a fragmentary view of alength of conduit on which a sleeve of waterproof material has been formed by extrusion.

Figure 5 is a modified form of the apparatus shown in Figure 3 adapted to extrude a sleeve upon a core, as shownin Figure 4; 3

Figure 6 is a fragmentaryview of .a section of conduit having a lining extruded therein. 7 1 T vention will; appear from the following de feo v rFigurg i a modifiedf rm of apparatus forv extruding the lining, as shown n I Figure 6.

' Figure 8' is acrosssectional View ofa multiple conduit which can be formed by extrusion;

I Referringhto the drawings in 'detail lO -represents ahopper through whichithe raw -inaterials may beyfed to a pair ofrolls 11- which are heated asby steam pipes 12 and driven by [any suitable means (not shown). The fibrous material, such as rags or asbestos V mill waste, are mixed with sufficient adhesive Qmaterial, such as partially oxidized linseed oil with or Without rubber or other equivalent, and fed to the rolls 11 through the hop per 10.; After athorough grinding of the mixture on the hot rolls,more-adhesive to gether with a suitable amount of fiowers-of- ,4 1 sulphur, powvdered mica and lampblack,

desired, is added to the mixture on the rolls to form a: soft, workable mass of proper con-' 1 sistency." Whenthefmass has been thorough-:

'ly'intermi'xe'dfit' is'fscraped from the surface of the rolls and allowed todrop' down through ,a hopper 13 which opens fa'sjat let intoa suitable'cylinder 15 hich-is preferably steama This press ina'ybeof a-nydesired type such j acketedat" 1 6jto niaintain'itat a suitable tenaper'ature, Injorde'r' to i apply pressure to the plastic mass for the purposes of extrusion, I- provide a piston1'7 which'may'be raised or lowered'by any desired means, such 'asa screw shaft or a hydraulic press indicated at: 181

' ascan be boughtonthe open market suitable mass may be extruded; Inorderto providei I j for the hollow center of the tubular'conduit,

preferably extends to the further wallof the {for the servicerequir'ed; *An'extrusionorifice 19 is formedat any suitable point ina wall of the*"cylinder15,' through which the plastic I locate in the-orifice 19a'mandrel 20 which cylinder 15.' This mandrel 20 is; preferably a hollow for purposes to' be described,and is I "supported by any suitable means, such as strut-s or fins 191, preferably located near the mou'thoffthe orifice 19. Multiple conduit 7 sucha's that'illustr'ated in Figure 8 {Canbemade by" shaping the orifice inaccordance withgthe' desiredoutline ofthe cross section;

This may be as'illustrated to 'minimize Weightand-cost of materia'L-or may be rectangular or any other desiredshape.

[may extend through the orifice and be sup- A number of mandrels 20, one for eachduct, in the conduit,

ported in spaced relation to the sides of the 1 'oriliceand to each other.

When plastic mate-rialioff the naturedescribed is extruded int-o the open air, it has av tendency to: cool rapidlyand to shrink slightlyltoward th'e n edian line of' the material. The cooling is usually more rapid on the outer surface" 1 than the inner. surface and [consequently internal strains are set up'in' the material "which render the conduit brittle and liable to crack. Another frequent cause of outer end of the member 21.

"rate from suchsurfaces. I

brittleness of conduit of this type is the ten clencyv of the extruded material to form in" V laminations under the influence of pressure used in forcing the 'Inaterial through; the orifice. Such laminations are apt to form} in planes substantially normal to" the applied pressure, instances of this tendency innature.

being fOllIlCllll the case ofslateandsha'le tormation.- Inorder to produce aconduit of maximum durability andminimum fbrittle ness, it is necessary first to'use proper materials in c orrect;proportion; second, to'mix to apply the pressures on the-material in the course of extrusion 1n such a way as to 1mmmize t-he tendency 'to laminate in anyone the ingredientsthoroughly and evenly third,

direction; and fourth,tocontrol 'the cooling of the mass in such away as toavoid the;s etting up of internal stresses'in the material .off-

the conduit. I provide for the first twdof these considerations, above mentioned,- I by selecting ingredients as hereinbefo-re describedand by mixing the-same onthe steaniheated rolls ll. :Inorder; to-provide against unduela-minations in any onedirection, Iiproform ed integrally with a wall of the cylinder 15; and extends outwardly from'theorilice l9 r with a constantly decreasing diameter.' This member 21' also surrounds and is c'oncentrlc with the mandrel '20; The function of the member21 v is to causethe plastic mass'whi'ch a lol'igitudinal pressure which causes the mass to move forward, a radial reactive pressureis develop radial laminations. =I may also ac-- complish "the same purpose by giving the member 21' a cylindrical shape, but tapering the mandrel 20 in the other" directionso that it increases in diameter to its maximum at the iIn orderfto preventtheflex'truding tubing from pilingup'on theimandrel 20 as it might supplied by thejtap'er ofthemeniber 21 whicli" i prevents excessive tendency 0f the massto do if allowed "to" emerge, from the narrowest Y a portion ot the member. Zliht'o'the open air I'provide a cylindrical extension- 2201 the member 2 1 which is preferably formed-fin-jj tegrally therewith and'is also concentricwith the mandrel 20; The mandrel 2 0 and the extension 22 are 1 constructed of suitable" length to maintain' the conduit inproper shape whileit sets sufficiently to .hold its j shape as it leavestheendyof theextension. The surfaces of the mandrel -20 and the ex tension-22 on which the extruding mass slides are preferably of 'polished steel as plastic 5 mixtures of the class described readilysepa a a In order to providefo'r suitable temperature control so as to enable the extruding vide' aconical member a 21 which may the,

conduit to cool in a manner designed to leave I it with the least possible internal stresses, I

.course of extrusion until it reaches the second compartment 24 which is preferably maintained at a somewhat lower temperature. The compartment is maintained at a still lower temperature, the extension 22 having no jacket at all. As an example of the temperatures at which the compartments may i be maintained when a conduit is being made of a mixture of fiber and partially oxidized linseed oil with sulphur, as previously described, the steam jacket 16 and the compartment 23 may be maintained at a temperature I of approximately 250, the chamber 24 at about 200, and the chamber 25 at about 100. These temperatures may be maintained by any suitable means, such as steam and water, heated air, oil or other fluid, or by electric resistance coils. The heated fluid may be fed through the various chambers as by suitable inlet pipes 26, 27 and 28 for the respective chambers and by corresponding outlets 29,.

30 and 31. In the cooling of the conduit, it

is found advantageous to allow the interior surface of the conduit to cool somewhat more rapidly than the exterior surface. To this end I introduce into the hollow mandrel 20 a suitable pipe 32 which may pass through the closed end ofv the mandrel 20 and extend to any desired distance within the mandrel. An outlet 33 is placed at the end of the mandrel so that air which is introduced at a suit able temperature circulates from the open end ofthe pipe 32 and travels back through the conduit 20 and out through the exhaust pipe 33. The temperature of the air or other fluid which is introduced through the pipe 32 is preferably at or slightly below the melting point of the adhesive used in the extruded material. This serves to bring the material near the inner surface of the tube close to the congealing point before the temperature of the material near the outer surface has been reduced to that extent, so that the tube hardens from the inside out. This process is duly retarded by the heated jacket and the extension 22 which is warmed by the material itself, so that internal stresses are largely avoided, but by the time the tube has reached the open air at the end of the mandrel 20, it has sufliciently set to hold its shape and to complete the hardening process without becoming brittle.

As the conduit 34 emerges from the extension 22, it may be cut ofi by any suitable" means into the desired lengths "and carried: off as by a conveyor 35;

This method of extruslon is 'capable of beijng used to form a coating 01 1a pre-forme'd tube of the same or of different material, such as iron or fiber pipe, or'it maybe used to form a liner in such a pipe. For this purpose, I'may use a cylinder15' and fa" tapering extrusion member 21 constructed as previously described, and illustrated in Figures.

5 and 7.- The extrusion members 21 are'prejf erably jacketed for-temperature c'ontr'oL the' chamber 24 in these cases being shown. as

also connected with the jacket lfi in order to maintain the mass at its extrusion tempera ature until a later pointis reached than" in the'case of the'extrusion'of-plain conduit. This keeps thewm'ateri-al'; more plastic and enables it toslipxmore readily :0n the pipe or core 36"on which the plastic'materiallis to form asleeve or'covering layer. As shown in Figurei5, a ma ndrel 37 is provided withla' suitable shoulder 38, this shoulder being formed to receive the end ofa' pipe-36 {over which the plastic material is togbe extruded.

The further steps of extruding'tlie mass over? the pipe 36'are as pr'eviou'sly describedfolfthe making of plain; conduit. As shown in: Figure 4,."the finished product comprises the pipe or tube'36 withasubstantial'evenlayer 39of-the plastic material covering-'its 'upperi surface. In like manner, a liner 4010f plastic mraterial maybe formed in a t-ubeorpi'pe41 by forming a shoulder 42, as shown in F igure' 7 in the'inner wall of the e-xtension;22,soa

t at-the pipe ermav be-inserted .intothe extension 22cagainst the shoulder 42 and the plastic material will a be extruded between the mandrel 2O 'and the pipe 41. The'pro'cess of coating or? lining pipes, as illustrated in Figures 4*and 6', is intermittent, the'extruding pressurein the'cylind'er- 15 being applied after a pipe'is put in position against the shoulder 38 "or 42 and beingremoved when the plastic matter has been squeezed throughto the 'further'endxof the eXt'ens-ion22, after.

which the lined'or coated pipe may drawn and another] one inserted. a; p

. Having thus described anflembodiment of. my invention, it shouldbegevident to those skilled inthe art that many changes and modifications may be made therein without departing from its spirit or scope as defined by the appended claims. "Iclaim: v

1. The method of making tubular conduit, which comprises, hot-grinding -rags with a thermo-plastic binder, and extruding the mass intubular-form. i

2, Themethod of making tubular conduit, which compriseshot-mixing fibers with a waterproof plastic binder, and extruding the mass in the form of'a-tube, the walls of theijtube in the jlcourseof extrusion being I ituhe mo'r'e rapidly than-,the'outer surface.

signature.

i jackets about said shaperfml m a s f lf s pt it rately supplying said jackets with fluids, A

y whereof I- have afiixed my,"

- I In testimon Y 4;;Apparatus forniaking conduit by 'ex- 3 l J I trusion, {comprising j an, extrusion chamber ltud-inally thereoflfthe clearance between the;

wallflof I'the chamber and the core prog'res- 7 'sivellyzand gradually diminishing in the-dia} re'ctiofnk-of extrusion, and means for pro-,

gressively coolingtheconduit inthe course. mot extrusion; I e y a '5 a The method of making tubular conduit,

whlchsgcoinprisesfl heating and grindingja ql' antitygof fiber with a thermoplastic bindery; extrudingzthe hotmixture into tubular shape,

.which -r comprises" hot-mixing t fiber and a: ,*binderito"form;a plastic mass, and extruding cooling-the inner'surface ofthe tube quickly .toIthecongealing point, and cooling the ex terior' surface of the tube more slowly;

' the massiintoj tubular' form; thethickness of '30; withinzduring extrusion :theredf- V the ltubefwalls being gradually decreased and the tube-being. progressively cooled from Themethodofmaking tubulariconduit; I Q 7 d I of extrusion beingrapidly cooled from with V Which comprises 'hot-mixing' fibe'r" and a binder into a plastic mass, -.andextruding the i t mass, into tubular form the tube in the course ei inf and slowly cooled from'; without;

' 8."The'1method of makingtubular conduit, 'which'zco'mprisesz hot mixin'g' fiber and 5a 10;

binder into a plasticmass, and extruding the 7 mass into tubular form; the tubein the course a of extrusion being rapidly cooled from within and slowly cooled from without; and having its thickness of w allgradually decreased.) 45" i9i*Apparatus for making conduit comprising; a' container having an orifice, a core ex? truding plastic material through said orifice .'tending-throughsaid orifice, means for extinto tub'ularIfo'rm,-V a tubular 'shaperextend ing from-{around sa dorifice and surround- ,lng said core, saldjshaper having'a't'apering internalidiameter 'With its maximum diam a 7 v I ete'r adjac'e'nt. to said orifice,"and m'eans for w lna'intainingend separately controlling a series of temperature zones along said shaper;

10. Apparatus for making conduiticom prising a'c'ontainer having an orifice, a core extending through said orifice, means for extruding plastic'lnate'zrial through said orifice into tubular formyatubular shaper extending from said orifice and surrounding said core, said shaperhaving a tapering lIl-f ternal diameter withfits maximum diameter adjacent said orifice, a series of peripheral

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