CA1268913A - Mold assembly for making a composite resin seal - Google Patents

Abstract

ABSTRACT

A mold assembly for manufacturing fluid seal for a liquid and gas-filled damper mechanism. The seal includes a casing unit and a primary sealing ring subdivided into two portions, one portion being adapted to provide a fluid seal with an associated reciprocable rod, and the other to provide a one-way relief valve action to bleed fluid from one side of the lip body to the other when higher pressure is on the rod side; and to increase the sealing force when the higher pressure is on the other side of the lip body opposite the rod. The mold assembly has a fixed part for engaging one surface of the sealing ring and part of a cavity for an annular collar; an intermediate mold member for overlying a casing unit received in the mold; and a third mold member having a frusto-conical surface to engage a margin of the sealing ring on a face opposite the face engaged by the innermost margin of the fixed mold part.

Description

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COMPOSITE T~FLON ~ELIX SEAL
The presen~ inv~ntion relate~ to a mold assembly for making improved shaft seals of specialty materials and adapted for a ~ide variety of application~.
Specialty ~aterials having low friction and favorable wear capabilities, including fluorooarbon ma~erials such as high poly~er~ of etraf7uoroethylene ~TFE), are known as potentially advan~ageou~3 for ~ealing applications, bu~ such ~aterials at the timle al~o have known drawback3.
Such re~inous mat~rial6 per ~e are of a plastlc charac~er~ they ~re subiect ~o cold flow7 and can be nicked or scratch~d during installation.
Obtaining and maintalning propsr ~it clearances and forces wlth as~ociated machin2 parts difficult.
Fllled or composite TFE and like material~ are now known which include a matrix of TFE resin but include inert fil}er~ (carbon blac~ gl~s8 fib~rs, etc.)5 these are better for certain application~O
TFE, being non-ela~tic, i8 poor for static seals. Many TF~ ~eals thus incorporated helices ~crew threads, vanes, e~c.1 to create hydrodynamic action.
Fluid ca~ be returned to th~ seal cavity by a ~pu~ping~
action when there i8 rela~ive motion be~we~n the ~eal and ~he chaft.
TFE i~ not easily bonded ~o a casing, and in 80m~ cases, to rubbsr. Thus, ~anufacturing and a~sembl~ng TF~ seal~ and deYeloping correct sealing lip or surfac~ pro~ile~ i8 a ~erious problem not yet ~ntir~ly ov~rco~e. ~o~vQr, T~ and related low friction material~ ar~ ~ill of intereqt a~ their advan~ages have become more wid~ly known~

~he invention provides a mold assembly for .laking a novel fluorocarbon seal which includes a formed resin ring element adapted to ~exve both a~ the primary lip and a3 an aux~liary or ~xcluder lip. At l~a~t a por~ion o~ the lil? ~urface contain~ hydrody~a~ic ~or~ation~ con5isting o~ groove~
or like inde~ted or debossed ~ur acas rather th n up tanding or pEotruding vanes o~ ribs; th~ re5inous seal ring as a whole is in the form of a gene~ally f~u~toco~ical ring havi~gan inte~m~diat~ portion thereof bond~d ~y an annular collar unit to an associatsd casing, having one radially spac~d apart portion acting aa the primary lip ~ur~ace and haYing a dif ~erent diamet~ than th~ seal diamet~ at the bond area, and ~urther ha~ing an auxlllary lip o~ a third di~meter adapt~d éo ~ngage another relatively movable surface to form an excluder lip. Preferably~ the s~al also co~prise~ an associated o~ acc~ssory casin~ forming a wear slee~e or s~al engagement surfac~ ~o that the primary seal lip c~n be protected a~t~r manuf ac~ure and prior to and during installation.

The invention provides a mold assembly for making a fluid seal as described, the assembly including a first, relatively fixed mold part having surfaces thereon defining at least in part the shape of the article to be manufactured, said surfaces including a radially innermost, generally frusto-conical surface having radially inner and outer margins, with said radially inner margin being adapted to engage one surface of a resinous seal ring placed therein, at least one surface also defining one portion of a cavity for forming an annular collar,~and casing support means in the form of a genera].ly radially extending additional annular surface: A second, intermediate mold member has yenerally ~ X~8~3 annular surfaces directed oppositely to said additi~nal annular surface and in overl.ying relation to a casing received in said mold, the intermediate member also including at least one inlet for fluent elastomeric material and further including surfaces defining an additional portion of said collar-formlng cavity. A third mold member has a generally frusto-conical surface portion adapted to engage a margin of said seal ring on a face thereof opposite the face engaged by said innermost margin of the fixed mold part, the third mold member having colning land and groove formations therein for cold forming hydrodynamic grooves in said resinous ring when said mold is in the fully closed position thereof, the mold also permitting, in the closed position thereof, :Elow of Eluent elastomer to fill said collar-forming cavity and bond said casing to said seal ring.

The accompanying description and the drawi~gs relate to several examples of seals made according to the i2lvention.
BRI~F D~SCRIPTION OF T~E DRAWINGS
FIG. 1 i a perspectlve view of a pre:Eerred ~orm o~ seal made in accordance with the invention;
FIG. 2 is a f ragmentary vertical ~ectional vi~w, of the seal o~ FIG. 1, ~howing c~rtain seal f ~ature~ s EIG. 3 i~ taker~ along line~ 3-3 oiE FIt:. 2 and ~how~ the hellx formed in the face of the ~eal ring;
FIG. 4 ~hows a tubular cylindrical billet of r~sînous material u~ed in ~aking the se~l ring;
~IG . 5 how~ the billet af ter it i~ bev~led or taper~ds FIG. 6 show~ the preferred method o~ maklng r~in ~ea}i~g rings f rom th~ billet FI~i;. 7 shows the coining die used in making sealing rings;

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.3 FIGo 8 shows part o the ~upport fixture and ring forming die and shows a ~e~ling rin9 ready to be ~oined s FI~. 9 shows the pre~erred or~n of mold u~ed to ~ake seals o t~e inventions FIGo 10 show~ part o~ the r~old o.f FIG. 9 in the clo~ed position with the ring and casing therein but before being fillad with ~la~tomer;
FIG . 11 shows the seal in the f inal proce~s 10 of being formed;
FIG. 12 shows a ~eal ins~alled in position of u~e with a plurality of a880ciated machine m~mber~ and FIG. 13 3hows an alternate ~orl3 of seal of a unitized construction and including a wear slQeve as well as a sealing elementO ~ :

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DESC~IPTION OY T~E PREPE~R~D
E~BODIMENTS OF T~E INVENTION
The s~al of the invention may be embodi~d in dif~erent orm~, both unitiz~d and ~on-unitized. Th~
s~allng ~ction ~ay re3ult f~o~ a~ outer casing with a ring having a ~ad~ally inwa~dly directed compressive load, with the exoluder lip acting axially, or in rever~ed fsr~, with the pri~ary cas~ng on the inside an~
the sealing lip being urged radially outwardly against compan~on ~iange or other s~ led surfac~.
The ~eal may also, but ne~d not include an auxiliary, axially acting lip~ ~erein, ~axially inner~ ~ean8 ~ean8 toward th~ sealed region and ~ax~a.lly outer~ m~ans away f~om t~e ~ealed ~e~ionS ~pr~mary~ as appli~d to th~ lip o~ s~al ring ~e~ns that which is intended to retain a fluld within the sealed region and "auxiliary~ ~ef~rR to a lip used to exclude contaminants ~rom the area betwe~n itsel~ and the ~icinity of th~
p~imary lip. ~nitized~ r~fers to a seal having an intended wearing ~u~acs along whic~ the seal band is situatQd on an acc~ssory wear sleeve element associated in use with the principal ~eal assembly. ~Sacondary~
means a se 1 whic~ is for~ed be~we~n t-~o relati~ely immovable or non-rotatable surfacss, (~h~ seal casing and ~he c~unterbore e.g.).
FIG. 1 shows a seal unit 20 and inc lude s a ca s ing un it 2 2, a re s inous ~ealing ring unit 24 whic~ is ~ecured to th~ portion of the casing 2~ by an an~ul ar elasto~@ric bonding and locating ~ollar generally designated 26. ~eferring now in pa~ticular to FIG. 2, it i shown th~t the ca~ing 22 includes an a::iall~r e:~tending ~ountina flange portion 28 . . . . .

~ 3 joined at a radiu~ portion 30 to a radially extending flange or bonding portion 32. The re~in sealing ring 24 i8 preferably made fro~ a resinou~ fluorocarbon ~aterial such as a high polymer of tetra~luoroethylene and i8 in the form of a tapered~ beveled or fru~to-collical ring of thin cross-sec~ion.
The seal ring 24 includes an act.ive surface 34 and a reverse surface 36, and may be subdivid~d (~or purpose~ of description) in.o an inner dia~eter portio~
38 on which the primary seal band 40 will be formed (see al80 FIGS. 12 and 13) an outer diameter portion 42 which will ~orm an auxiliary lip generally de~ignated ~, and an interm~diate or bondlng portion 46.
In FIG. 2 ~how~ that a single spiral groove 48 or a plurality }ike formations 48 are coined, or cut along the activ~ sur~ace 34 of the inner diameter portion 3a of the ring 24. These grooves 4~ are hydrodynamic pumping elements whose construction will be described ~l~ewhere herein.
FIG. 2 al~o ~how~ that a cylindrical elasto~eric body 50 i8 formed on the outer surf~ce 52 of ~he flange 28, and that this body includes ~ plurality of rib~ 54 giving a contoured ch~racter to the out ide dia~eter ~OD~) ~ounting ~urfac~ 56 of the body 5D. ~he elasto~r u~ed to form th~ body 50 i~ ~180 u~ed to proYide a generally annular bumper element 58 ha~ing a flat nose portion 60 and being of ~en~rally rectangular cro~ ection. ~n use, the nose 60 ~urface may b~ u~ed : to abut a port~on o~ a sealed ~echa~ica~ or an 3~ ~ssociated comp~nion ~lange a~ re~erred ~o elsewhere her~in.

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Another element of the ~eal i the annular collar 26 of elastomeric material used to ~cure the sealing ring 24 ~Q the casing 22. It includ1es axi~lly inner and oU~2r bonding body portion~ 62, 64 of thin cross-section, which are ~paced ~part by thle thickne ~
of ~he fla~ge 32 and which meet at their inner diam~ters to form an annul~r c~ter section 66 o the collar 26 A portion of the collar web 26 lying inward.ly of the center ~ection 66 i8 seen to be of increased width and to form an annular mounting pad ~urf~ce 68 which lie~
along ~nd i8 firmly bonded to the intermediate or bonding band portion 46 of the reverse side surface 38 of the re~in ~eallng ring 24~
FI~. 12 Yhow~ the ~eal a~embly 20 in an installed po~ition of use, in a sealed mech~ni~m 70 which include a machine member 72 having a counterbore urface 74 which anugly receive~ the rib~ 54 on th~
outer di~eter of the mounting body 50, thus locating the axial flang~ 28 of the seal s~in~ 22. ~he counterbore 74 al80 rec¢ives an out~r race 76 locating a plurality of tapered roller bearing~ 78 which also roll ~long an inner rdc~ 80, pre~sed over the outer diameter ~urfac~ 82 of a rokary sh~f~ 84.
Th~ in~tallation al~o include~ ~ sp~ce~ 86 or pre~sed over the ~hat 8~ ~nd providing ~n end ~ac~
~urf~c~ 88 for engage~ent by th~ auxiliary lip 44, a~
will appear. The ~eal~d region 90 i8 atle~st p~r~ially filled witb oil or gre~s~, ~nd ~aY its principal part~
@xpos~d to ~uch lubr~c~nt ln liquid or Yapor phas~. A
pri~ry ~eal band ~0 ~8 for~od ~here the inne~ dia~ter portion 38 of the ~eal r~ng 24 i8 ~liqhtly deformed or ~bell-mouthed~ ~o a~ to li~ closely over, ~nd impart a , ~LX~;8S~
radial compressive load to the exterior ~urfac~ 82 o the rotary ~haft 84., ~ere t~e groov~ 4a lie along and face the ~ealed ~ur~ace. The prilQary seal band 40 i~
formed by contact betw~en the actiYe or inn~r surface 34 of the ring 24t while th~ rever~e surface 38 i8 u~ed for bonding and, except for being fluid, ga~ ~nd vapor impermeable, does not per se form an activ~ ~ealing ~urfac~ .
The end ~urface 88 osl the ~pac~r B6 engagas or i~ clo~ely ~paced apart from the nos~ ~urface 60 on the spacer 58. The auxiliary lip 44 i~ dimensioned ~o as to be placed under a sllght ~xial end faca load in thi~ ln~tall~d positlon, thereby drawing it~ outer diameter ~ ~ome~hAt outwardly ~nd also into a ~bell-mouthed~ poaition, enabling lt to obtain and maintain a sliding s~al fit with the end ace ~urfac~
8~ .
FIG. 13 show~ ~n alternate for~ of seal 20a in a mecharlism 70a baving a seal~d region 90a, Th~s seal include~ the ~h~f~ 8~a, the exterior ~ur~ace 82a and lthe be~ring~ and rac~s 76-80a, etc. of it~ countarpart in PI~:. 12. ~owever, the ~eal of FIG. 13 include~ an ~uxiliary sleev~ 92 with an axially extellding mounting Flange 94 for engaging the ~eal ring 24, ~ radius portion ~6 ~nd a radl~lly extending co~binatioll unitizing flange and auxiliary lip companion flange 98 aE~ well ~8 a sraall un~ti~ing curl 100. A wear surface 102 li~ on the outer ~urfac~ OÉ the flange 9~ while a ribbed ~la~to~eric mounting body 10~ i~ bonded to the inner surPace of ~hi~ ~lange 94. In u~e~ the body 104 18 pre~s f it ovQr 1:he ~ur~ace 82~ dur~ng inztallation of th~ seal. The no~e portion 6û~ o~ the spacer 58a ., - .

6~L3 provides the same function a~ its counterpart in FIG.
12, e~cept that it engages the lnner or wear~ng 8urface 106 of the flange 98~ as doeR the auxili ry lip sur~3ee 44a formed on the outer diameter 42a of the pri~ary seal ring 24~. The ~eal ass~mbly 20a i8 thu~ a uni~ized seal.
FIGS. 4-8 ~how c~rtain step~ in the pr~erred method of forming the seal ring of the invention.
Referring to FIG~ 4, there i8 shown a cylindrical flurocarbon billet 200 which i8 preferably made from a gla~3 fiber filled, high polymer of tetrafluroethylene ~TFE)~ a tough ~olid material having a lubrlcous ~urace. The billet 200 ha~ inner side wall~ ~02 and outer 8ide wall8 204, mad~ to any convenient length by known ~ethod~ s w h ~8 Binte~ ing.
The ~ealing rin~s 24 (FIGS. 1-3 and 12 - 13) of the invention are made by chucki~g the bill~t 204 in a su~table tool ~nd rotating it while a knife 206 ie u ed to cut a t~pe~d ~dge or bevel 208 on the billet -~
200. Thereafter, as shown i~ FIG. 6, the kni~e $~ ~oved axially do~nwardly and the proce~a rep~a~ed until 2 plurality of ring~ 2~-1, 24-2, 24-3, etc. ~re cut or ~kived~ ~rom the bill~t 200. The~e r$ng~, 24-1 to 24-3, are of the g~n~ral:fru~to-conic~I shape shown, h~ving ~ cy1irldric~1 inner edge 210, ~ cy1indric~1 outer edg~ 212, and radially inner and outer face surfa~e~
~1q, 216.
~ herea~er, one or more hydrodynamic grooves are forr~ed into the ~eal rings 24 by cutting witb ~
30 knife, awl or like instru~esl'c, or by colnlng. FIG. 7 sho~6 a ring coining die 220, which inc1uqes ~ ~upport fixtur~ 222, having ~ ~;apo~ed, upwardly directedl con~cal _ 9 _ iX61~

face 224 ~nd a cavity 226 for ~upporting a po~ ionlng element 228. The eler~ent 228 may al80 include a b~veled ~urface ~o aid in centering or otherwi~e positloning the ring 24. The other el~ent include~ a coining die 232 ;;
having a relieved inner surface 234 and a contoured end generally de~ignated 236 with (FIG. R) a radially inn~r land-and-groove por ion 238 and a radi~lly outer, flat surface portion 240.
The inner portion 238 includes a plurality of 10 sharpened lands 242 spaced apart f rom each other by grooves 244. The inner diameter 212 of the r~ng 24 i8 sized o as to lie ln a notched annular area 246 ~ormed by coop~ration betwe~n the die part~ 22~ 228. When the ring forming die 220 i8 closed und~r hlgh forc~ or pressure, the lands 242 form grooYes in the inner diameter margin or ~ctive surface portion 34 lyiFIg on the inner diameter 38 o~ the ring 2~.
FIGS. 4-8 thu~ 3how a preferred ~imple, and ePect~ve D~e~hod of making ~nd coining frusto-conical 20 rlng~ suitable for use w$th th~ inv~n~ion.
~ IGS~ 9-11 Elhow an aRsembly 300 ~or the r~oldlng complet~d seal~ using the preiEormed c~sing 22 and a precot bu~ not colned rir1g 24. The mold a~sembly 300 include~ ~ top plat~ 302, an inner core 304, an outer co~e 306~ a sp~ue~pl~te 308~ and ~ 6eaI ~ing holddown pla~e 310. FI6~ 9 al30 ~hs*~ a drawn or stamped ~aAing gener&lly designa~ed 22 po~itloned ~ :
be~weQn the cores 304~ 306 and the spru@ pl~1:e 30~9 wilth $t~ axi~l flange 28 extending downwardly and it~ r~d:la:L
3~ flange 32 being ~hown to pre~ent what wiIl becom~ ~n axl~lly inwaxdly diEected surface 33 ly~ng downw~rd iEor support orl the 2nd f~c~ portion~ 312 of a plurallty o~
stamping suppor~ boss~ 31~. ,!

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The cor~ 304 includes a center reGess 316 for rec~iving ~ locat~ng pin or dowel 318 for alignment purpose~ and include~ portions which help defin~ both the outer and inner ~eal cavities 320, 322. Thes~
include an outermost annular ~urface 324, &urmounted by a locating bead 326. Lo~ated radially inwardly of the stamping support bo~es 314 are contoured surfaces 328 adapted to form a portion of what will become ~-he web 66 in the fini~h~d ealO A tapered or beveled resin rlng support surface 330 i8 al~o provided and terminates at ~8 inner edge in an annular groove 332, upwardly and inwardly og which lies a tapered mAting or registration surface 334.
The outer core 306 includes ~ lowermost annular surface 336 abov~ which i~ ~ grooved or r~bbed surface 338 adap~ed to form ~h~ ribs 54 in ~he ou er di~meter of the seal caslng 22.
The spru~ plate 308 ~8 preferred fcr injection ~olding and includes, in ~ddition to the lo~r flat ~urface 3dO adapted to lie upon the ~urface 341 of the cor~ 306, a tapered ~prue 342 ter~nating ~t an inl~t 344~ It will b~ under~tood th~t the sprue~ 342 are tapered pas~age~ spaced ~part from each other about the p~riph~ry o~ the ~vity ~or~ed in part by the sprue plate 308, and that radially inw~rdly thereof i~ ~ mold elemen~ 344 having a generally cylindrical registration ~urface 346 below which i~ a t~per~d 0urf~ce 348 haYing th~ important func~ion of ~ngaging th~ outer dia~ter port~on ~2 of the ~eal r~ng 24. Con~our~d ~urf~c~, including th~ ~urface 350 a~d 352 al~o deine additional portlon~ of th~ oute~ and inner mold cavities 320, 322.

~X ~8 ~3 The ~eal ring holddown element 310, include~
opposed fla~ suraces 354, 356 enabling it to be ~tacked with the other elementR when the ~old i~ clo~ed. In addition~ it include~ a upper sprue pas~age 358 and an annular formation 360 ter~inating in a pair of beveled annular surfaces 362, 364. The surface 36~ abut~ or lies closely spaced apart from its counterpart surface 334~ and the surface 362 lie~ along and engages the active gur~ace 3~ of the ring 24 ~hen the ~old is closed~ A plurality of coin$ng formation~ 366 are sho~n a~ lying along the r~dially inner margin of th~ surface 3G2, ~or ~n-mo}d coining.
The out~r margin 368 of the ~urface 3~2 i~ in vertic~l ~egistry with the ~upport ~urface 34 for the outer diameter 42 of the ring 24. The mold top plate includes the downwardly directed fl~t surfac~ 370 ~dapt0d to engage the surface 346 on the ~old part 310 as well as a plur~lity of radial grooves 372 ~tanding outwardly from and communicating with the ~ain sp-~ue pa~age 374, through which fluent el~to~eric material passes a8 rubb~r i~ in~ected during manufacture. A
plur~llty of O rlngs 376, 376a, 376b9 are ~ho~n to b~
provided in th~ respecti~e mold section~ and e~ch i8 received w1~h~ a groo~e 378, 378a, etc. in conventional m~nner to in~ure sealing ~nd~or vacuu~
control when the mold i~ clo~ed.
~ IGS. 10 and 11 ~ho~ the ~old 300 with the ele~ent~ in the clo~d po31tion ~nd the ~tampi~g 22 ~upported on the bons~s 31~, and it~ radially i~nermo~t surface 35 lying ~long~ide and being engaged with ~he mold cav~ty for~$ng surf~ce 32~. The bead 326 ~erv~ to c~nter ~he stampi~g 22. With ~he mold clo~edt the - , .~., , ~ .; , ~ 3 construction of the cavity 320 forming the ring around the cylinder or body 50 of elasto~er around the outermost portion of the flange 28 can be ~een, as can the contour~ of the cavity 322 in which the v~rious web portions 62, 64 and th~ coll~r 66 are formed, which elements terminate at their radially innermost portions in the annular mounting or bonding pad 68 which extend~
around the int~r~ediate bonding band portion 46 of ~he ring 24 80 a~ to fix it securely in relation to the ca~ing.
Provision o~ the groove 332, in combination with the pinching ~ction provided between the surfaces 348 and surface~ 36a on the 8prue plate 308 and the holddown plate, re~pectively, insure tha~ the ring 2~
held in pl~ce properly, ~nd further insure that ~fla~h will no flow onto the ~urface 348, and henc~ ~ill not lie along the r~versed surface portion of the auxilliary lip-orming outer diameter 42 of the seal ring 24.
The mold ~urface 352 (PIGS. 10 and 11) i~
8pac~d 81ightly ap~rt from the upper ~urface of the flange c~sing 227 this ~paclng permit8 fluent rubber to 10w from the spru~ lnlet 344 into the cavity 322.
Custor~axily, there ~r~ al80 provid~d hold down pins or tbe like (not sholwn) to bear against the upper surface of the casing and hold it in pl~ce during ~olding.
Be~ng known to those skilled in the ~rt and no~ kor~ g a part o~ th~s in-~ent$on, these ele~ent~ are not shown or described in detail. Lilcewis:~, the l~nd 314 i~
di6corltinuou~ or h. 8 circumf~r~ntially spaced ~part 3û portion~ permi~cting ~ tomer flow between such portiQn O

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1~ ~ 8~3~3 FIG. ll shows the above element~ with the mold clo~ed, with ~he rubber overflow or Wdump" areas 380 filled with rubber and with the ~ounting diameter body 50 and the ~nnular collar n~ck portion ~6 of the rubber a well a~ the remaining elementR bei~g formed as shown in FI~. 3.
Another feature of th~ invention i8 that ~he land and groove surace 366 on the radial}y inner portion of the tapered surface 362 on the hold down ring 0 310 al80 serves to coin the plurality of hydrodynamic grooves 48 in the radially inner diameter margin 38 of the ~eal casing 24. This i8 done lf the ~oovc~ are not pr~form~d by the apparatus o~ FIGS. 7 and 8.
Accordlngly, ~he mold o~ the type shown may accommodate and ~ent~r the ca~ing 22, and with the ~eal ring 24 inser~ed therein when the mold i8 clo~ed, the ring i8 positioned b~ th~ groove 366 and pinched off by the surface 368 ~o as to remain position~d to accept the high pressure flow of fluent rubber into the cavitie~
320, 322 to form a se~l which include~ an outer diameter mounting body por~-ion ~ade from ~n elastomer a~ well as a ~ounting or locating collar portion and ~ounting pad formation which provides ~cellen~ locating and good fl~xibility in use.
The ~eal as described is highly advantageou~ for ~everal rea~ons. Fir~t~ the formation ~-of the primary re~inous Ae~ling ring in the ~ann~r : illustrated enable~ it to be a pr~for~ed ~ru~to-conical tapered or ~b~ mouthed~ con~iguratio~ which i~ ideal for engaging ~n a~ociated ~haft. It achieve~ thi~
shape ~n the relaxed or as-for~ed conditionO ~hi~ not only ~impli~ies a~mbly, but provide a graduatsd load ~ 3 extending from the inne~most diameter gradually along and to a larger diameter port~on of the bevel. ~he hydrodynamic formation~ may be, and pr~ferably are, formed a~ groove~ rather than lands as ha~ co~monly bQen done in the pa~t. Thi allow~ greatly reduced wear on the active ~urface of the riny, inasmuch as the hydrodynamic element~ o~ vanss do not extend outwardly from the active sur~ace of the material where ~hey are ubjected to wear. The co~trolled radial compre~ive load or radially inwardly directed ~ealing force, particularly with its graduated pressure effect, enables a good ~tatic seal to be maint~ined, a~ does the fvrmation of the narrow pitch ~plral or helix for hydrodynamic purpo~e~. While thi~ narrow pitch or like ~p~ral i5 not a necessary feature of the invention, lt i8 a pattern which ha~ been particu~arly ~uccessful with this form of fi~al.
Another ~eature of the invention iB the ~bility to use a ~ingle piece of TFE re~in sealing ring or washer to provide an auxiliary or excluder lip seal from the ~ame material. The tapered construction of the pri~ry se~l ring ~R ~or~d permits the auxiliary or ~xcluder lip to be formed on a l~ger diame~er where it can eng~ge an end ace ~ur~ac~. Thi~ i8 ~ preferred fo~m of exclud~r lip which pre~erably ride~ on a ~urface other th~n th~ ~ame sha~t which i8 being ~ealed by the prlmary ring. Th~ rusto-conic~l or ~ape~ed constr~ction i~ ldeal fro~ thi~ Rtandpoint.
Anoth~r advantag~ of the invention i8 ~hat th~ resin ring may be bond~d ~nd located in ~ highly adYantageou~ manner by the pro~ision of ~h@ novel collar which extends between the webs of el~om~r e~tend$ng .

along the faces of the r~di~l c~sing flange and the annular band on the r~ver~e or inactiYe surf~c~ of the re~in. ~hi~ collar proYides firm but flexible location of the lip as a whole. ~t provide~ ~n excellent bonding surfac~ bu~ it need not undergo ~ignificant bending motion leading to pre~ature failure in u~e. It readily accom~odates radial runout and provide~ a portion of greatly $ncreased flexibility in relation to the modulus of the re~in. Accordingly, in a slightly off centered or like shaft which i~ es~entially round but which iB
not mounted concentrically with the counterbore, the ~xcentricity or radial runout may b~ accommodat~d by the elastomer whil~ th~ re~in ring, whlch i~ not inharently a~ flexible~ or ~t lea~t has a gre~ter modulus, can follow the ~eal 3urface without undergoing high rate deflec io~. The coll~r may b~ made of any deslred thickne~s, but preferably i8 relatively thin~ It thu~
provldes ~ood c~nte~ing action because of it~ geometry, while ~till providi~g ~ rel~tively thin cro~ sec~ion.
It is bell~ved th~t the flexibl~ coll~r ~hich i8 form~d of el~tomer and, 1~ ef~ect, lnter~ect~ th~ surfac~ of the primary seal ring at ~ ~ub~tantial angle i8 ~n importan no~el feAture of th~ inYention for th~ type of loc~tlng action i~ pro~d~.
The seal iB id@~lly ~dapt~d to both unit~zed ~nd nonunitlzed con~truction~ and th2 method~ u~ed ~o m~ke it are highly ~dv~ntageous~ ~ISS. 9-11, show th2t the ~eal can be ~de in ~ ~ingle operation - colning o~
: the hydrodyn~mic surP~ces on the pri~ry rlng snd ~olding bo~h ~ cubber OD and ~he bondlng eoll~r and pad.
The ~e~l de~ign i~ ~ui~able for incorpor~ting a rubber ~: OD ~nd ~ o readily ~uited ~o the u~e o~ a compa~ion .
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flange or unitizing e1ement which may it~el hav~ ~
rubber ID linside diameter)0 The ~eal may be readily adapted to rever~e ~ype in~ tion~ where ~he ~eal ac~ radially outwardly, or wher~in the part illustr~ted a~ the shaft 84 i8 stationary and the machine part 72 ro~ates. In such ca~es~ centrifugal force~ may be taken advantage of as a se~ling para~eter. In u~e~r the ~e~l of ~h~ inYenSion ba proved extremely advanl:ageou~ ~n terms of extended wear, ease of ~anufacture ou~standing ~eal performance and particularly, ease of manufacture~
It ia not necessary to prefor~ the fluroc~rbon resin ring by elaborate proc~sses or form it by th~ u~e of mandrels and o~her t~chniques known ~o the prior ~r~
In th2 abov~ description, the expres~lon ~spir 1,~ or ~hellx~ ~ay be used to d~3cribe the hydrodyn~mic ~or~ations on the active or ~e~l band surface 34 of the primary ring 24 of the seal.
In thi~ ¢onnect1on, it should be understood that a ~ariety o~ p~ttern~ are ~ffective to bring about th~ return of oil to the ~aled cavity upon rotatio~ of the shat, or, of cour~e, return lubricant or the like to the sea1ed cavity $n the event it i3 the seal which rotate~ and th~ 8h~f~ or the like which ~t~nds ~till.
In ~ither ca~, rel~ti~e ~otion between ~h~ two ~erve~
to ~pu~p~ ~he oil, grea~e, or other ~ealed fluid b~ck into the sealed region. In th~ use of 1uorocarbcn seal~, it h~ generally b~en found that a ~crew thr~ad pattern of fine pitch i~ pr~f~rred, and this form of ~e~ illustr~ted in FIG~ 3 of th~ dr~wings t for ex mple, in th~e figure~, th~ d~z~i~gs ~re intend~d to illus~ra~e ~he u~ of ~ helix h~ving two or ~or~
a~tart~ th~t i~, t~o or more point~ At whlch one of the ~ X ~ 9~3 groovea 48 lnters~ct~ the inner~o~t ed~e portio~ 210 of the actual ~al rin~ 24. In ~uch ca8@, oil ~ntering any one particular ~roove along the se~l band 40 will be in communication with oil in the sealed r~gion at ~he point where the ~tart~ occurs 9 that i~, where the groove 48 intersects the ~xially inner~o~t edge 210 of the se~l ring. In some ca~es, there may be only a ~ingle ~tart, as shown or implied in ~IG. 12, for example, but the number of star~ or intersections i~ not a mat~rial par~
of t~e invention, such features p~r se being known to the prior art.
Another form o~ hydrodyn~mic formation whi~h has pro~red ~ucc~ssful in use iB one wherein th~
formation compri~e~ a part of a spiral of a gre~tly differing pitch or t~per, and ~n the oil seal art, such ormations are often referred to a~ ~helices~, that i~, as ele~ent~ of a helix pattern. These separate element~, ~ometime~ al80 referred to a ~v~ne~ rib~, or the lik~, are lllu~trated, for example in U.S~ Pa~ents Nos. 3,640,542 and 3,790,180.
Still further, other hydrodynamic formation~, such ~ triangle~, sinuou~ pattesn~, or the like ~ay al80 be used, depending on the prePerence o~
the d~signer.
~owever~ a pr~ferred fe~ture of the psesent inventio~ i~ that the form~kion, pa~ticularly if it be of the ~crew thr~d, spiral~ or helix form, b~ debo~d or gr~oved into the ~urfac~ of th~ se~l rinyc ~hereby dimi~i~hing wear con~iderably. In other word~, when the : ~0 major w~ar~ng sur~c~ 40 contscting th~ shaft or other ~aled ~urfa~e i~ free ro~ up~t~nding or e~bos~ed forma~ions, extended lif~ in the u~ o~ th~ ~eal i~ ~adle ~1;i89~3 possibl~. If the formations wer~ r~i~ed, for example, they would be expo~ed to prematur~ a~.

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Claims (2)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A mold assembly for manufacturing a fluid seal, said mold assembly including a first, relatively fixed mold part having surfaces thereon defining at least in part the shape of an article to be manufactured, said surfaces including a radially innermost, generally frusto-conical surface having radially inner and outer margins, with said radially inner margin being adapted to engage one surface of a resinous seal ring placed therein, at least one surface also defining one portion of a cavity for forming an annular collar, and casing support means in the form of a generally radially extending additional annular surface: a second, intermediate mold member having generally annular surfaces directed oppositely to said additional annular surface and in overlying relation to a casing received in said mold, said intermediate member also including at least one inlet for fluent elastomeric material and further including surfaces defining an additional portion of said collar-forming cavity, and a third mold member having a generally frusto-conical surface portion adapted to engage a margin of said seal ring on a face thereof opposite the face engaged by said innermost margin of said fixed mold part, said third mold member having coining land and groove formations thereon for cold forming hydrodynamic grooves in said resinous ring when said mold is in the fully closed position thereof, said mold also permitting, in the closed position thereof, flow of fluent elastomer to fill said collar-forming cavity and bond said casing to said seal ring.

2. A mold assembly as defined in Claim 1 which further includes means fixed with respect to said first fixed mold part and which define at least portions of a cavity lying radially outwardly of said casing member and being in communication with said material inlet whereby an outer diameter elastomeric body may be formed on said casing at the same time said collar is being formed.