CA1044293A - Molded plastic bearing assembly - Google Patents
Molded plastic bearing assemblyInfo
- Publication number
- CA1044293A CA1044293A CA289,231A CA289231A CA1044293A CA 1044293 A CA1044293 A CA 1044293A CA 289231 A CA289231 A CA 289231A CA 1044293 A CA1044293 A CA 1044293A
- Authority
- CA
- Canada
- Prior art keywords
- group
- monomer
- acrylic
- hydrogen
- bearing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Abstract
ABSTRACT OF THE DISCLOSURE
A shaped bearing member comprises a substrate provided with a coating of a cured mixture of an acrylate composition and a particulate solid lubricant, said coating having a thick-ness ranging from 0.002 to 0.125 inch.
A shaped bearing member comprises a substrate provided with a coating of a cured mixture of an acrylate composition and a particulate solid lubricant, said coating having a thick-ness ranging from 0.002 to 0.125 inch.
Description
The preaent inv~ntlon relate~ to a mold~d ~lf-lubricating bearin~ d~embly and particularly to a self-lubricating bear.ing a9~embly capa~le o~ ab~o~bing radial, axial and moment loading, individually, or in combination.
The application is a division of Canadian patent application serial number 212,95~.
In the past, efforts to produce a molded bearing a~mbly compri~ ing an inner bearing member and ~ molded ou~er pla~tic ra::e have not been altogether ~atisfactory.
In certain instances, excessive 1008ene~ between the freely rotatable inner bearing member and the plastic out-er race i~ experienced. In other in~ta~es, the pla~tic material after injection about ~he inner bearing member tend~ to ~hrink around the inner bearing member$ thereby causing a lock up of the plastic race on the inner bearing member. This latter phenomenon seriously interferes with the normal desired relative movement between the bearing men~ers .
Repre~entative of prior art molded bearing as-semblie~ include tho~e described in U~S. patents 2,970,869 and 3, 094, 376 to Thomas and 3~287,071 to Tucker. In ac-c~rdance with Thomas ' U~S . patent 2,970,869, a plas~ic material i~ injected under pre~sure within a housing en-closing a member ~o that the plastic conform3 to the mem-ber and on hardening forms both a rigid supporting backing and a bearing ~urface for the member. Plastic materials di~clo~d for uie in thi~ patent are polyethyl~ne, phenolic
The application is a division of Canadian patent application serial number 212,95~.
In the past, efforts to produce a molded bearing a~mbly compri~ ing an inner bearing member and ~ molded ou~er pla~tic ra::e have not been altogether ~atisfactory.
In certain instances, excessive 1008ene~ between the freely rotatable inner bearing member and the plastic out-er race i~ experienced. In other in~ta~es, the pla~tic material after injection about ~he inner bearing member tend~ to ~hrink around the inner bearing member$ thereby causing a lock up of the plastic race on the inner bearing member. This latter phenomenon seriously interferes with the normal desired relative movement between the bearing men~ers .
Repre~entative of prior art molded bearing as-semblie~ include tho~e described in U~S. patents 2,970,869 and 3, 094, 376 to Thomas and 3~287,071 to Tucker. In ac-c~rdance with Thomas ' U~S . patent 2,970,869, a plas~ic material i~ injected under pre~sure within a housing en-closing a member ~o that the plastic conform3 to the mem-ber and on hardening forms both a rigid supporting backing and a bearing ~urface for the member. Plastic materials di~clo~d for uie in thi~ patent are polyethyl~ne, phenolic
2~3 impregnated gla~ fibrous material, nylon and a phenolic-polyethylene impregnated gla~s fibxou~ m~terial.
In Thomas' IJ.S. patent 3,094,376, a relatively thin coating of polytetrafluoroethylene or nylon i~ ap-plled to the ~urface of a ball retained in a housingO Ahardenable backing m~terial i~ then injected into the housing, around the polytetrafluoroethylene or nylon, und-er heat and pressure to entirely fill the ~pace wit~in the housing ao that ultimately there ie no relative movement 10 be~ween the hardened backing material and the polytetra- ;
fluoroethylene or nylon, the latter being in rotative en-gagement with the ball. Material~ u~ed to fonm the in-jected backing member are phenolic impregnated ylas~
fibrous material, nylon and a phenolic-poly~thylene im-pregnated g 1a83 fibrous material.
An even more xecent development in the molded bearing art is U.S. patent 3,287,071 to Tucker who inject~, ~
~ ~ .
under a pressura of abou~ 1000 p~i, a heated, liquefied low shrink plastic material about an inner bearing member 20 dispo~ed within and spaced from a housing member ~o that ~:
when the plastic material i8 3et it forms a race for the inner bearing member and i9 in line-to-line rotatable en-gagement ther~with ~ut in non-rotative engagem~nt with the wall surface of the hou~ing, generally by means of a keying element extending radially through the hou~ing : . ~ -.. .: . : .: .
member and integral with the pla~t ic race . ~Fhe low 3hrink pla~tic materlal disclo~ed in thi~ patent i~ 20% glasA
~illed nylorl.
Contrary to the3e prior art moldad b~aring a~-5 ~emblie~ which utilize, as the plastic mat~ri~l for pro-ducing a molded race or bearing member, a polytetra~luoro-ethylen0 or a nylon based materlal wllich require~ the ap-plication of heat and/or elevated pre~sure in order to .
liquefy and to inject the same into the ~pace ~urrounding 10 the inner member, the present invention provide~ a bearirlgassembly utilizing an acrylate compo~ition which is liquid at an~ient temperature and pre~ure, thus permitting the :
formation of the outer bearing member therefrom under these condition~. Advantageously, the production of the 15 outer bearing member at ambient temperature el.i~inates the absolute need to heat the plastic material to a molten state which heating operation i~ required in prior art method~ of producing molded pla~tic bearings. A ~ignifi-cant economy in pxoduction costs can thu~ be achieved.
Fur~her, the use of the acrylate compo~ition in the pres-ent invention avoids the need for the ad ition to the :
: plastic material of solvents to liquefy the same, a~
required in prior ar~ compositions, thus avoiding the pos-sibility of adver~e after effect3 r~sulting from driving off the ~olvent durlng the curing operation. Such advers~
. ~5~
' :
- . , -4~3 effects can b0 refl~cted in th~3 introdu~tion o~ unde~ir-able play between tha bearing members and/or the pre~ence ~f voids in portions of the cured material.
Mor~over, the us~ of ~he acryla~o canpo~ition ln the prelsont invention ha~ boen found particularly ad-vantageou0, sincs the compo~ition remains in a liquid ~tat~ until it i~ either deprivad of oxyyen or raised to an olovated temperature, thu~ easing hand~ g, ~torag~ and manufacturing operation~ involving the eame and permitting, for insta~ce ~ the use of in j E3ctlon pressureB a~ low a~ ;
about 0.25 1bs/in2, wh~n ar~ lnjaction operation i~ desir-ed. Thus, the pre~ent invention repre~ente a ~ignificant departure from the prior art molded boaring a~emblie~ and from prior art methods of producing the same, while achiev-ing equal ~Ind even sup~Drior re~ulta.
In Canadian patent application 212,954, from ~ :
which the present application is divided, there is dis-closed a bearing assembly comprising an inner and an outer co- :
engaging bearing members movable relative to one another, the inner bearing member having a bearing surface made of a member selected from the group consisting of metal and ceramic ;~
and the outer bearing being produced from a mixture of a cured acrylic composition and a solid lubricant, organic or inorganic, in partlculate form. In an advantageous embodiment the inner bearing member comprises a ceramic bearing surface provid-ed by a thin ceramic coating on a metal substrate, the thickness of the ceramic coating ranging from O . 0001 to 0.02 inches~
According to the present invention there i~ provided a shaped bearing member compri~ing a substrate provided with a coating of a cured mixture of an acrylate composition and a particulate solid lubricant, th~ ooating having a thickness withisl :
the range fxom 0.002 to 0.125 inch, Said coating prefera41y has ~ thickness within the range from 0.0~5 to 0 a 06 inch.
Preferably said acrylate composition in the cured mixture`forming said coating is selected from the group consist-ing of:
(a) a mixture of a major amoun~ of a liquid acrylic ester selected from the group consis~ing of di~, ~ri- and tetraesters of an acrylic acid and a polyhydric alcohol, a minor amount of a low molecular weight PrePolymer o an ester of a low molecular weight alcohol having a terminal vinyl group and an aromatic polycarboxylic acid in solution in said O
acrylic ester and an organic amide of the formula R~C-NH2 ~herein R is selected from the group consisting of hydrogen and aliphatic hydrocarbon of 1-20 carbon atoms in an amount sufficient to copolymerize said acryli~ ester and prepolymer.
~ b) a mixture of acrylic ester monomer, a peroxidic initiator in an amount suf~icient to initiate polymerization of said monomer and an aminoalkoxyalkylamine of the formula Rl-N(H)R21OR3]XN(H)R~ wherein x ic an integer of 1-6 inclusive, each of Rl and R4 is sele~ted from the group consisting of hydrogen and lower alkyl and ~ -7 `~ L~''' ' .
each of ~2 and r~3 is a lower alkyl linking bridge between N and 0, in an amount sufficient to acceler-ate -the polymeri~ation of said monomer, (c) a mixture of an acrylic ester of an alkyl amino alkyl alcohol and an ei'fective amount of a hydroperoxide catalyst, said acrylic ester having the formula O
CH3 ( CH2) x N ~ 2 ~ 0-C-C=CH2 wherein x is an integer of 0-5 inclusive, y is an integer of 1-6 inclu~ive 2 R is selected from the group consisting of hydrogen, halogen, hydroxy, cyano and lower alkyl and Rl is selected from the group con-sisting of hydrogen and alkyl having 1-6 carbon atoms, (d) a mixture of a liquid acrylic ester monomer selected from the group consisting of diesters of an acrylic acid and a polyhydric alcohol, acrylic es-ters of cyclic etheralcohol~s, acrylic esters of amino alcohols and mixtures thereof, a peroxidic initiator and an oxyalkylaminelof the formula (H)mN (CH2)(0R1)y OR2~n wherein m and n are each integers of 1 to 2 inclusive, the total of m and n is 3, x is an integer of 1 to 6 inclusive, y is an integer of O to 6 inclu-sive, Rl is lower alkyl and R2 is hydrogen or lower alkyl, . (e) a mixture of an acrylic ester monomer selec-~: ted from the group consisting of di-, tri-, and te-tra-esters of an acrylic acid and a polyhydric alcohol, acryl-~ .
- 7a -'~ '.
:, .
ic esters oL` cyclic ether alcohols, acrylic esters of amino alcohols and mixtures -thereof, a peroxidic initi-a.tor of an amount su~ficient tO initiate polymerization of sain monomer and a member selected from the group consisting of rhodanine and a hydrazide of the formula H O
HN-N-C-R wherein R and ~ are selected from separate Rl , ,, groups and an interconnected group forming a cyclic ring, R is further selected from the group consisting of hydrogen,-alkyl, cycloalkyl, aryl and alkoxy and R
is selec-ted from the group consisi-ting o~ hydrogen, alkyl, cycloalkyl, and acyl in an amoun-t sufficient to accelerate the polymerization of said monomer; and (f) a mixture of a monomer of the formula 2 2 1 2 f 21 2 OH ~ OH
wherein Rl and R2 are selectedfrom~the group consistin~
of hydrogen and lower alkyl and R3 is selected from the group consisting of lower alkyl, lower hydroxyalkyl, cyano and lower cyanoalkyl; at least one equivalen-t of an acid for each equivalent of ~aid monomer, said acid belng selected from the group consisting of acrylic acid and lower alkyl acrylic acids; an initiator sel-ected from the - 7b -, ..... . , , .. . , , ~ .
group consi~tin-J of t-butyl perbenzoate, t-butyl perace-tate and di-t-butyl diperphthalate, aaid initlator being pre~nt in an amount ~ufflcient to initiate the pol~mer-ization of ~aid monomer; a trihydroxy benzene inhibitor and an aeeelerator ~sleeted from the group eon~isting of ber~zhydrazide and N-aminorhodanine.
Generally, th~ curable acrylat~ present in amoun'c~ o~ about 50-70, preferably ~bout 6~ percer;~ by weight of ~aid mixture, the remainder being es~antially :~:
said partieulate ~olid lubricant which ean b~, for in-9tanee, polytetrafluoroethylene, preferably in floek form, molybdenum di~ulfide, graphite fibers, ~ilver powder, lead powder, fiberglass floek and other~.
The eura~le aerylate compo~ition usefully em-ployed in the pre~ent invention i~ seleeted from the group : eon~i9ting of (a) a mixture of a major amount of a liquid 20 acrylic ester seleeted from th~ group eonsisting o di-, tri- and tetraesters of an acrylic acid and a polyhydric al~ohol, a minor amount of a low molecular weight prepoly-mer o~ an ester of a low molecular weight alcohol having a tenminal vinyl group and an aromatie polycarboxylic acid in solution in ~aid aerylie ester and an organic amide of O
the fonmula R - C - NH~ wherein R ia selected from the group consi~ting of hydrogen and aliphatic hydrocarbon of 1-20 carbon atoms in an amount ~uffieient to eopolymerize s ~aid aerylie ester and pr~polymer, -7 ~
(b) a mlxtur~3 o~ acrylic ~3ter monomer, a per-oxidic initiator in an amount suffi.c1ent to lnitiate poly-merizati~n of said monomer and an aminoalkoxyalkylamine of the formula Rl-N(H)R2tOR3~ )R4 wherein x is an in-teger of 1-6 inclusive, each of Rl and R4 i~ 9elected from the group consi~ting of hydrogen and lower alkyl and each of R2 and R3 1~ a lower alkyl linklng bridge between :
N and o, in an am~unt ~ufficient to accelerate the poly-merization of said monomer, (c) a mixture of an acryli~ eater of an alkyl amino alkyl alcohol and an effective amount of a hydroper-oxide cataly~t, said acrylic ester having the formula O
CE~3 (CH2)x N - (CH2)y 0 - C - C - CH2 ' Rl R
wherein x i9 an integer of 0-5 inclusive, y i9 an integer ~ ;:
of 1-6 inclusi~e, R is selected from the group consisting of hydrogen, halogen, hydroxy, cyano and lower alkyl and ~ selected from the group consisting of hydrogen and alkyl having 1-6 carbon atomY, ~ d) a mixture of a liquid acrylic aster monomer selected from the group consisting of diesters of an acryl-ic acid and a polyhydric alcohol, acryli~ ester~ of cyc~ic .
ether alcohols, acrylic esters of amino alcohols and mix-tures thereof, a peroxidic initiator and an oxyalkylamine 2~3 of t;he fO~rnula ~H)mNI (C~2)~0Rl~y OR2]~ wherein m ~nd n are each lnteger~ of l to 2 inclu~ive, the total of m and n is 3O x i0 ar~ int~ger of 1 to 6 inclusive~ y ~ an in-teger of 0 to 6 inclu~ive, Rl is lower alkyl and R2 i~
hydrogen or lower alkyl, ~e) a mixture of an acrylic eeter monomer ~e-lected from the group consi~ting of di-, tri- and t~tra-esters of an acrylic acid and a polyhydric alcohol, acryl-ic e~ter9 o~ cyclic ether alcohol~, acrylic ~ater~ o amino alcohols and mixture~ thereof, a p~roxidic initiator in an amount ~ufficient to initiate polymerization o~ said monomer and a member selected from the group consisting of rhodanine and a hydrazide of the formula O
H ~
H N - N - C - R
wherein R and R~ are selected from separate group~ and an interconnected group forming a cyclic ring. R is further selected from the group consi~ting of hydrogen, alkyl, cycloalkyl, aryl and alkoxy and R' is selected fxom the group COn~iRtiny of hydrogen, alkyl, cycloalkyl, and acyl in an amount sufficient to accelerate the : polymerizatlon of said monomer and (f~ a mixture of a monomer of the formula R10 0 R2 `' ,.
~ 25 CH2 - C-c-o-cH2-cH-cH2-N-c~2-c~-cH2-o-c-c = CH~
: O~ R O~
_g_ ;
' '~.
~rherein ~1 and R2 are selected fro~n the group con~i~ting of hydrogQn and lower alkyl and R3 i~ ~elected from th~
group con~i~ting of low~3r alkyl, lower hydrc~xy~llcyl, cyano and lower cyanoalXyl; at liea0t one eqllivalent c~ arl 5 acid for each equlvalent of ~aid monomer, ~aid acid b~ing selected from the group con~i~ting of acrylic acid and lower alkyl a~rylic acid~ an ini~iator aelect~d from the group con~i~ting of t-butyl perbenzoa~e, t-butyl p~race-tate and di-t~butyl diperphthalate, 3aid initiator being 10 present in an amount ~ufficient to initiata the polymer-ization of said monomer; a ~rihydroxy b~nzene inhibitor and an acc~lerator ~elected from the group con~isting of ~:
benzhydrazide and ~-aminorhodanine.
In one embodiment of the pre~ent invention, in ~ :
the iacrylate compo~ition (a) de~ined above, the liquid acxylic e~ter employed i9 well known and include~0 for instance, ethylene glycol dimethacrylate, diethylene gly-col dimethacrylate, triethylene glycol dimethacrylate, tetraethylQne glycol dimethacrylate, polyethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tetra-ethylene glycol diacrylate, tetraethylene glycol dichlor-.
acrylate, glycerol trimethacrylate and pentaerythritol tetramethac~ylate.
:
.' , : . .,, : , i , ~4~3\3 U~eful prepolymer~ include the partial polymer-ization product3 of an ester of an ethylenically unsatur-ated low molecular weight alcohol having a terminal vinyl group, such as allyl alcohol, and an aromatic polycar~oxylic acid such a phthalic, isophthalic, terephthalic, mellitic, and naphthalene dicarboxylic acids. The prepolymer6 include, for instance, those of diallyl phtha].ate, diallyl i~ophthalate, triallyl trimellitate and diallyltrimellitat~.
:
~, " '' ' ..
--:
~;
: , ~L~44;2~33 The prepolymer can be present in amounts of about 5 - 60 weight percent, preferably about 15 - 30 weight percent of the acrylate composition. Amounts of about 5 - 20 weight percent can also be employed.
Repxesentative organic amides employed as a catalyst include formamid~, acetamide, propionamide, amides derived from naturally occurring C12 - C20 fatty acids such as palmitic, stearic, oleic and tallow fatty acids, cyclohexyl carboxylic acid and alkyl substituted cyclohexyl carboxyl acid amides, and cyclohexyl hexanoic acid amide. The amide can be pre-sent in amount of 0.1 - 1~% of the ac~ylate composi-tion.
In another embodiment of the present invention, in the acrylate composition (b) defined above, the acrylic ester monomer can be, for in tance, an acrylic diester of ethylene glycol, an acrylic ester of a cyclic ether alcohol, an acrylic ester of an amino alcohol and mix-tures thereof or mixtures of the above with other vinylic mono-:
.
.: '`' : ~ --,, - -, .. ~ ~ ~ . .
~;: . . : , . : , . , mers su~h a~ allylic monamers. R~presentative acrylic e~t~r monomers i~clud~ i~obutyl methacrylate, n-bu~yl methacrylate, mi~*d mono- and di-methacrylates of 2,2,4-tri~ethylpentanediol, t~trahydrofu~furylmethacrylate~
5 polyethylene glycol dimethacrylata, cyclohexyl methacryl-ate and dimethylaminoethyl methacrylate.
The peroxidic cataly~t, employed usually in amount~ o~ about 0.1 10 or 15 percent by weight of the ~crylate compo~ition, includes for in~tance cumene hydro-peroxide, t-butyl hydroperoxide, methylethylketone hydro-peroxide or peroxide, tetralin hydroperoxide, benzoyl per- -oxide, lauroyl peroxide and ditertiary butyl diperphthal-ate.
U~eful aminoalkoxyalkylamine~ include, for in-~tance, ~,N'-dimethyl triethylene glycol diamine~ ~,N'-diethyl diethylene glycol diamine, N,N'-diet~hyl hexa-ethylene glycol diamine, di-6-~methylamino) hexyl ether of 1,6-hexanediol, di-6-(hexylamino) octyl ether of ethyl-ene glycol, methylaminomethyloxyhexylaminohexane, amino-20 propoxye~hyl amine, aminomethoxypropyl amine, methylamino- :
methoxypropyl amine, aminomethoxymethyl amine, hexylamino-::hexyloxyhexyl amine, 2-aminoethoxy-3,4-dimethyl hexyl amine, methylaminobutoxybu~oxy amine, aminoethoxyethoxy-hexyl amin~ and aminobutoxyhexyloxyhexyloxy butyl amine.
25 The aminoalkyloxyalkylamine accelerator can be pre~ent in ~ -.
-~3_ ... .- . . . .
amount~ of about O . 01 - 10 percant hy weight of the acryl-ate ca~npo~itior:.
In a further embodimen~ of the pre~ent inven~ion, in the acrylat~3 canpo~iti:>n (c) defined above, the as:~rylic 5 es~er include~, for in~tance, butylamlnoathyl ~e~hacrylate, ~.
dimethyl aminoethyl ~yanoacrylate or methacrylate or chlor-acrylate, dihe~syl aminoloethyl acrylate, amylaminoethyl ethacrylate, di(t-butyl~ aminoethyl methacrylate, di(t-butyl) aminohexyl methacrylate, hexylaminohexyl pentacryl-ate, methylaminom~thyl methacrylate, ~B w~ll aq othere~ters of acrylic acid~ and alkylaminoalkanol~.
Representative hydroperoxide cataly~t~ include cumene hydroperoxide, t-butyl hydroperoxide~ methyl~hyl-ketone hydroperoxide, tetralin hydroperoxide and 2,5- ~ :
dimethylhexyl-2,5-dihydroperoxide. The cataly~t i9 pre~-ent generally in amount3 o~ about 0.1 - 15 percent by weight of said acrylate composition.
In yet another embodiment of the present inven-tion, in the acrylate compo~ition (d~ defined above, the ~0 liquid acry1ic ester monomer can be that employed, for in~tancet in acrylate compo~itions of (a), (b).and (c).
Representative oxyalkylamines include, for in ~tance, diglycol amine, di-(triethylene glycol) amine and othè~ di-(polyethylene glycol) amines including di-(hexa-ethylene glycol) amine, metho~ypropyl amine, hydroxypropyl .. . , .. . - ~ . . .
2~3 amina, methoxymethyl amine, hexyloxyhexyl amine, 2-ethoxy-
In Thomas' IJ.S. patent 3,094,376, a relatively thin coating of polytetrafluoroethylene or nylon i~ ap-plled to the ~urface of a ball retained in a housingO Ahardenable backing m~terial i~ then injected into the housing, around the polytetrafluoroethylene or nylon, und-er heat and pressure to entirely fill the ~pace wit~in the housing ao that ultimately there ie no relative movement 10 be~ween the hardened backing material and the polytetra- ;
fluoroethylene or nylon, the latter being in rotative en-gagement with the ball. Material~ u~ed to fonm the in-jected backing member are phenolic impregnated ylas~
fibrous material, nylon and a phenolic-poly~thylene im-pregnated g 1a83 fibrous material.
An even more xecent development in the molded bearing art is U.S. patent 3,287,071 to Tucker who inject~, ~
~ ~ .
under a pressura of abou~ 1000 p~i, a heated, liquefied low shrink plastic material about an inner bearing member 20 dispo~ed within and spaced from a housing member ~o that ~:
when the plastic material i8 3et it forms a race for the inner bearing member and i9 in line-to-line rotatable en-gagement ther~with ~ut in non-rotative engagem~nt with the wall surface of the hou~ing, generally by means of a keying element extending radially through the hou~ing : . ~ -.. .: . : .: .
member and integral with the pla~t ic race . ~Fhe low 3hrink pla~tic materlal disclo~ed in thi~ patent i~ 20% glasA
~illed nylorl.
Contrary to the3e prior art moldad b~aring a~-5 ~emblie~ which utilize, as the plastic mat~ri~l for pro-ducing a molded race or bearing member, a polytetra~luoro-ethylen0 or a nylon based materlal wllich require~ the ap-plication of heat and/or elevated pre~sure in order to .
liquefy and to inject the same into the ~pace ~urrounding 10 the inner member, the present invention provide~ a bearirlgassembly utilizing an acrylate compo~ition which is liquid at an~ient temperature and pre~ure, thus permitting the :
formation of the outer bearing member therefrom under these condition~. Advantageously, the production of the 15 outer bearing member at ambient temperature el.i~inates the absolute need to heat the plastic material to a molten state which heating operation i~ required in prior art method~ of producing molded pla~tic bearings. A ~ignifi-cant economy in pxoduction costs can thu~ be achieved.
Fur~her, the use of the acrylate compo~ition in the pres-ent invention avoids the need for the ad ition to the :
: plastic material of solvents to liquefy the same, a~
required in prior ar~ compositions, thus avoiding the pos-sibility of adver~e after effect3 r~sulting from driving off the ~olvent durlng the curing operation. Such advers~
. ~5~
' :
- . , -4~3 effects can b0 refl~cted in th~3 introdu~tion o~ unde~ir-able play between tha bearing members and/or the pre~ence ~f voids in portions of the cured material.
Mor~over, the us~ of ~he acryla~o canpo~ition ln the prelsont invention ha~ boen found particularly ad-vantageou0, sincs the compo~ition remains in a liquid ~tat~ until it i~ either deprivad of oxyyen or raised to an olovated temperature, thu~ easing hand~ g, ~torag~ and manufacturing operation~ involving the eame and permitting, for insta~ce ~ the use of in j E3ctlon pressureB a~ low a~ ;
about 0.25 1bs/in2, wh~n ar~ lnjaction operation i~ desir-ed. Thus, the pre~ent invention repre~ente a ~ignificant departure from the prior art molded boaring a~emblie~ and from prior art methods of producing the same, while achiev-ing equal ~Ind even sup~Drior re~ulta.
In Canadian patent application 212,954, from ~ :
which the present application is divided, there is dis-closed a bearing assembly comprising an inner and an outer co- :
engaging bearing members movable relative to one another, the inner bearing member having a bearing surface made of a member selected from the group consisting of metal and ceramic ;~
and the outer bearing being produced from a mixture of a cured acrylic composition and a solid lubricant, organic or inorganic, in partlculate form. In an advantageous embodiment the inner bearing member comprises a ceramic bearing surface provid-ed by a thin ceramic coating on a metal substrate, the thickness of the ceramic coating ranging from O . 0001 to 0.02 inches~
According to the present invention there i~ provided a shaped bearing member compri~ing a substrate provided with a coating of a cured mixture of an acrylate composition and a particulate solid lubricant, th~ ooating having a thickness withisl :
the range fxom 0.002 to 0.125 inch, Said coating prefera41y has ~ thickness within the range from 0.0~5 to 0 a 06 inch.
Preferably said acrylate composition in the cured mixture`forming said coating is selected from the group consist-ing of:
(a) a mixture of a major amoun~ of a liquid acrylic ester selected from the group consis~ing of di~, ~ri- and tetraesters of an acrylic acid and a polyhydric alcohol, a minor amount of a low molecular weight PrePolymer o an ester of a low molecular weight alcohol having a terminal vinyl group and an aromatic polycarboxylic acid in solution in said O
acrylic ester and an organic amide of the formula R~C-NH2 ~herein R is selected from the group consisting of hydrogen and aliphatic hydrocarbon of 1-20 carbon atoms in an amount sufficient to copolymerize said acryli~ ester and prepolymer.
~ b) a mixture of acrylic ester monomer, a peroxidic initiator in an amount suf~icient to initiate polymerization of said monomer and an aminoalkoxyalkylamine of the formula Rl-N(H)R21OR3]XN(H)R~ wherein x ic an integer of 1-6 inclusive, each of Rl and R4 is sele~ted from the group consisting of hydrogen and lower alkyl and ~ -7 `~ L~''' ' .
each of ~2 and r~3 is a lower alkyl linking bridge between N and 0, in an amount sufficient to acceler-ate -the polymeri~ation of said monomer, (c) a mixture of an acrylic ester of an alkyl amino alkyl alcohol and an ei'fective amount of a hydroperoxide catalyst, said acrylic ester having the formula O
CH3 ( CH2) x N ~ 2 ~ 0-C-C=CH2 wherein x is an integer of 0-5 inclusive, y is an integer of 1-6 inclu~ive 2 R is selected from the group consisting of hydrogen, halogen, hydroxy, cyano and lower alkyl and Rl is selected from the group con-sisting of hydrogen and alkyl having 1-6 carbon atoms, (d) a mixture of a liquid acrylic ester monomer selected from the group consisting of diesters of an acrylic acid and a polyhydric alcohol, acrylic es-ters of cyclic etheralcohol~s, acrylic esters of amino alcohols and mixtures thereof, a peroxidic initiator and an oxyalkylaminelof the formula (H)mN (CH2)(0R1)y OR2~n wherein m and n are each integers of 1 to 2 inclusive, the total of m and n is 3, x is an integer of 1 to 6 inclusive, y is an integer of O to 6 inclu-sive, Rl is lower alkyl and R2 is hydrogen or lower alkyl, . (e) a mixture of an acrylic ester monomer selec-~: ted from the group consisting of di-, tri-, and te-tra-esters of an acrylic acid and a polyhydric alcohol, acryl-~ .
- 7a -'~ '.
:, .
ic esters oL` cyclic ether alcohols, acrylic esters of amino alcohols and mixtures -thereof, a peroxidic initi-a.tor of an amount su~ficient tO initiate polymerization of sain monomer and a member selected from the group consisting of rhodanine and a hydrazide of the formula H O
HN-N-C-R wherein R and ~ are selected from separate Rl , ,, groups and an interconnected group forming a cyclic ring, R is further selected from the group consisting of hydrogen,-alkyl, cycloalkyl, aryl and alkoxy and R
is selec-ted from the group consisi-ting o~ hydrogen, alkyl, cycloalkyl, and acyl in an amoun-t sufficient to accelerate the polymerization of said monomer; and (f) a mixture of a monomer of the formula 2 2 1 2 f 21 2 OH ~ OH
wherein Rl and R2 are selectedfrom~the group consistin~
of hydrogen and lower alkyl and R3 is selected from the group consisting of lower alkyl, lower hydroxyalkyl, cyano and lower cyanoalkyl; at least one equivalen-t of an acid for each equivalent of ~aid monomer, said acid belng selected from the group consisting of acrylic acid and lower alkyl acrylic acids; an initiator sel-ected from the - 7b -, ..... . , , .. . , , ~ .
group consi~tin-J of t-butyl perbenzoate, t-butyl perace-tate and di-t-butyl diperphthalate, aaid initlator being pre~nt in an amount ~ufflcient to initiate the pol~mer-ization of ~aid monomer; a trihydroxy benzene inhibitor and an aeeelerator ~sleeted from the group eon~isting of ber~zhydrazide and N-aminorhodanine.
Generally, th~ curable acrylat~ present in amoun'c~ o~ about 50-70, preferably ~bout 6~ percer;~ by weight of ~aid mixture, the remainder being es~antially :~:
said partieulate ~olid lubricant which ean b~, for in-9tanee, polytetrafluoroethylene, preferably in floek form, molybdenum di~ulfide, graphite fibers, ~ilver powder, lead powder, fiberglass floek and other~.
The eura~le aerylate compo~ition usefully em-ployed in the pre~ent invention i~ seleeted from the group : eon~i9ting of (a) a mixture of a major amount of a liquid 20 acrylic ester seleeted from th~ group eonsisting o di-, tri- and tetraesters of an acrylic acid and a polyhydric al~ohol, a minor amount of a low molecular weight prepoly-mer o~ an ester of a low molecular weight alcohol having a tenminal vinyl group and an aromatie polycarboxylic acid in solution in ~aid aerylie ester and an organic amide of O
the fonmula R - C - NH~ wherein R ia selected from the group consi~ting of hydrogen and aliphatic hydrocarbon of 1-20 carbon atoms in an amount ~uffieient to eopolymerize s ~aid aerylie ester and pr~polymer, -7 ~
(b) a mlxtur~3 o~ acrylic ~3ter monomer, a per-oxidic initiator in an amount suffi.c1ent to lnitiate poly-merizati~n of said monomer and an aminoalkoxyalkylamine of the formula Rl-N(H)R2tOR3~ )R4 wherein x is an in-teger of 1-6 inclusive, each of Rl and R4 i~ 9elected from the group consi~ting of hydrogen and lower alkyl and each of R2 and R3 1~ a lower alkyl linklng bridge between :
N and o, in an am~unt ~ufficient to accelerate the poly-merization of said monomer, (c) a mixture of an acryli~ eater of an alkyl amino alkyl alcohol and an effective amount of a hydroper-oxide cataly~t, said acrylic ester having the formula O
CE~3 (CH2)x N - (CH2)y 0 - C - C - CH2 ' Rl R
wherein x i9 an integer of 0-5 inclusive, y i9 an integer ~ ;:
of 1-6 inclusi~e, R is selected from the group consisting of hydrogen, halogen, hydroxy, cyano and lower alkyl and ~ selected from the group consisting of hydrogen and alkyl having 1-6 carbon atomY, ~ d) a mixture of a liquid acrylic aster monomer selected from the group consisting of diesters of an acryl-ic acid and a polyhydric alcohol, acryli~ ester~ of cyc~ic .
ether alcohols, acrylic esters of amino alcohols and mix-tures thereof, a peroxidic initiator and an oxyalkylamine 2~3 of t;he fO~rnula ~H)mNI (C~2)~0Rl~y OR2]~ wherein m ~nd n are each lnteger~ of l to 2 inclu~ive, the total of m and n is 3O x i0 ar~ int~ger of 1 to 6 inclusive~ y ~ an in-teger of 0 to 6 inclu~ive, Rl is lower alkyl and R2 i~
hydrogen or lower alkyl, ~e) a mixture of an acrylic eeter monomer ~e-lected from the group consi~ting of di-, tri- and t~tra-esters of an acrylic acid and a polyhydric alcohol, acryl-ic e~ter9 o~ cyclic ether alcohol~, acrylic ~ater~ o amino alcohols and mixture~ thereof, a p~roxidic initiator in an amount ~ufficient to initiate polymerization o~ said monomer and a member selected from the group consisting of rhodanine and a hydrazide of the formula O
H ~
H N - N - C - R
wherein R and R~ are selected from separate group~ and an interconnected group forming a cyclic ring. R is further selected from the group consi~ting of hydrogen, alkyl, cycloalkyl, aryl and alkoxy and R' is selected fxom the group COn~iRtiny of hydrogen, alkyl, cycloalkyl, and acyl in an amount sufficient to accelerate the : polymerizatlon of said monomer and (f~ a mixture of a monomer of the formula R10 0 R2 `' ,.
~ 25 CH2 - C-c-o-cH2-cH-cH2-N-c~2-c~-cH2-o-c-c = CH~
: O~ R O~
_g_ ;
' '~.
~rherein ~1 and R2 are selected fro~n the group con~i~ting of hydrogQn and lower alkyl and R3 i~ ~elected from th~
group con~i~ting of low~3r alkyl, lower hydrc~xy~llcyl, cyano and lower cyanoalXyl; at liea0t one eqllivalent c~ arl 5 acid for each equlvalent of ~aid monomer, ~aid acid b~ing selected from the group con~i~ting of acrylic acid and lower alkyl a~rylic acid~ an ini~iator aelect~d from the group con~i~ting of t-butyl perbenzoa~e, t-butyl p~race-tate and di-t~butyl diperphthalate, 3aid initiator being 10 present in an amount ~ufficient to initiata the polymer-ization of said monomer; a ~rihydroxy b~nzene inhibitor and an acc~lerator ~elected from the group con~isting of ~:
benzhydrazide and ~-aminorhodanine.
In one embodiment of the pre~ent invention, in ~ :
the iacrylate compo~ition (a) de~ined above, the liquid acxylic e~ter employed i9 well known and include~0 for instance, ethylene glycol dimethacrylate, diethylene gly-col dimethacrylate, triethylene glycol dimethacrylate, tetraethylQne glycol dimethacrylate, polyethylene glycol dimethacrylate, dipropylene glycol dimethacrylate, tetra-ethylene glycol diacrylate, tetraethylene glycol dichlor-.
acrylate, glycerol trimethacrylate and pentaerythritol tetramethac~ylate.
:
.' , : . .,, : , i , ~4~3\3 U~eful prepolymer~ include the partial polymer-ization product3 of an ester of an ethylenically unsatur-ated low molecular weight alcohol having a terminal vinyl group, such as allyl alcohol, and an aromatic polycar~oxylic acid such a phthalic, isophthalic, terephthalic, mellitic, and naphthalene dicarboxylic acids. The prepolymer6 include, for instance, those of diallyl phtha].ate, diallyl i~ophthalate, triallyl trimellitate and diallyltrimellitat~.
:
~, " '' ' ..
--:
~;
: , ~L~44;2~33 The prepolymer can be present in amounts of about 5 - 60 weight percent, preferably about 15 - 30 weight percent of the acrylate composition. Amounts of about 5 - 20 weight percent can also be employed.
Repxesentative organic amides employed as a catalyst include formamid~, acetamide, propionamide, amides derived from naturally occurring C12 - C20 fatty acids such as palmitic, stearic, oleic and tallow fatty acids, cyclohexyl carboxylic acid and alkyl substituted cyclohexyl carboxyl acid amides, and cyclohexyl hexanoic acid amide. The amide can be pre-sent in amount of 0.1 - 1~% of the ac~ylate composi-tion.
In another embodiment of the present invention, in the acrylate composition (b) defined above, the acrylic ester monomer can be, for in tance, an acrylic diester of ethylene glycol, an acrylic ester of a cyclic ether alcohol, an acrylic ester of an amino alcohol and mix-tures thereof or mixtures of the above with other vinylic mono-:
.
.: '`' : ~ --,, - -, .. ~ ~ ~ . .
~;: . . : , . : , . , mers su~h a~ allylic monamers. R~presentative acrylic e~t~r monomers i~clud~ i~obutyl methacrylate, n-bu~yl methacrylate, mi~*d mono- and di-methacrylates of 2,2,4-tri~ethylpentanediol, t~trahydrofu~furylmethacrylate~
5 polyethylene glycol dimethacrylata, cyclohexyl methacryl-ate and dimethylaminoethyl methacrylate.
The peroxidic cataly~t, employed usually in amount~ o~ about 0.1 10 or 15 percent by weight of the ~crylate compo~ition, includes for in~tance cumene hydro-peroxide, t-butyl hydroperoxide, methylethylketone hydro-peroxide or peroxide, tetralin hydroperoxide, benzoyl per- -oxide, lauroyl peroxide and ditertiary butyl diperphthal-ate.
U~eful aminoalkoxyalkylamine~ include, for in-~tance, ~,N'-dimethyl triethylene glycol diamine~ ~,N'-diethyl diethylene glycol diamine, N,N'-diet~hyl hexa-ethylene glycol diamine, di-6-~methylamino) hexyl ether of 1,6-hexanediol, di-6-(hexylamino) octyl ether of ethyl-ene glycol, methylaminomethyloxyhexylaminohexane, amino-20 propoxye~hyl amine, aminomethoxypropyl amine, methylamino- :
methoxypropyl amine, aminomethoxymethyl amine, hexylamino-::hexyloxyhexyl amine, 2-aminoethoxy-3,4-dimethyl hexyl amine, methylaminobutoxybu~oxy amine, aminoethoxyethoxy-hexyl amin~ and aminobutoxyhexyloxyhexyloxy butyl amine.
25 The aminoalkyloxyalkylamine accelerator can be pre~ent in ~ -.
-~3_ ... .- . . . .
amount~ of about O . 01 - 10 percant hy weight of the acryl-ate ca~npo~itior:.
In a further embodimen~ of the pre~ent inven~ion, in the acrylat~3 canpo~iti:>n (c) defined above, the as:~rylic 5 es~er include~, for in~tance, butylamlnoathyl ~e~hacrylate, ~.
dimethyl aminoethyl ~yanoacrylate or methacrylate or chlor-acrylate, dihe~syl aminoloethyl acrylate, amylaminoethyl ethacrylate, di(t-butyl~ aminoethyl methacrylate, di(t-butyl) aminohexyl methacrylate, hexylaminohexyl pentacryl-ate, methylaminom~thyl methacrylate, ~B w~ll aq othere~ters of acrylic acid~ and alkylaminoalkanol~.
Representative hydroperoxide cataly~t~ include cumene hydroperoxide, t-butyl hydroperoxide~ methyl~hyl-ketone hydroperoxide, tetralin hydroperoxide and 2,5- ~ :
dimethylhexyl-2,5-dihydroperoxide. The cataly~t i9 pre~-ent generally in amount3 o~ about 0.1 - 15 percent by weight of said acrylate composition.
In yet another embodiment of the present inven-tion, in the acrylate compo~ition (d~ defined above, the ~0 liquid acry1ic ester monomer can be that employed, for in~tancet in acrylate compo~itions of (a), (b).and (c).
Representative oxyalkylamines include, for in ~tance, diglycol amine, di-(triethylene glycol) amine and othè~ di-(polyethylene glycol) amines including di-(hexa-ethylene glycol) amine, metho~ypropyl amine, hydroxypropyl .. . , .. . - ~ . . .
2~3 amina, methoxymethyl amine, hexyloxyhexyl amine, 2-ethoxy-
3,4-dimethylh~xyl amine, ethoxy-ethoxyethoxyethoxyethoxy-ethoxy~t:hyl amine, bu~oxybutoxy amine, ethoxyethoxyhexyl amine, hydroxyhexyloxyhexyloxy butyl amine, di-(hydroxy-5 butoxybutoxy bu~yl) amine and di~(methoxypropyl) alnine.
The oxyalkylamine accelerator can be present in amounts of about 0~1 - 10 percent or more by weight of the acryl-ate composition.
ExampleY of suitable peroxidic initiator~ in~
clude cumene hydroperoxide, t-butyl hydroperoxide, methyl-ethylketone hydropero~ide or peroxide, tetralin hydroper-oxide, benzoyl peroxide, lauroyl peroxide and ditertiary butyl diperphthalate~ The initiator is present generally in amount~ 0.1 - 10 or 15 percent by weight of the acryl-15 ate compo~itionO
In a further embodiment of the present inven-tion, in the acrylate composition (e) defined above, the acrylic e~ter monomer can alRo be that employed, for in-tance, in acrylate compo~itions (a), (b) and (c).
U~eful accelerator~ include rhodanine and or~
: ganic hydrazides having the formula H O
.
H - N - N - C - R
:; : R' wherein R is selected from the group con~iRting of hydro-~15-2~3 gen, alkyl, cycloalkyl, aryl and alko~cy and R ' is3 ~elect-ed from the grDup con~ieting of hydrogen, alkyl, cyclo-alkyl, and acyl. The group R and FZ' can b~3 connected to ~ach other dir~ctly or indirectly throu~h S other atom~ or group~ to ~orm a ring ~y~tem, a~ ill N-aminor hodanine H2M-N-CO-CH2-S~S, N-aminourazole H2N N-CS~-~H-~H~0 and P~-aminophthalimlde _' ~
0 H2N-N-CO ~:~ . 'rhU9 R and R' can con~titute the ring CO ~
~tructure of a cyclic amide ~uch as the ring ~tructure of rhodanine, glyoxalylurea, mesoxalylurea, alloxanic ~cid, pyrazolone and pherlazone. Representatives ac-, , ~4~3 celerators include rhodanirle and N-amino rhodanine.
The accelerator can be pre~ent in amount8 of about 0.001 to 10 or more weight percen~ o the acrylat~ compo~i~lo~. :
Representative peroxidi~ initiatoxe include cumene hydroperoxide, t butyl hydroperoxide, methylethyl- -ketonQ hy~roperoxide, tetxalin hydrop~roxi~e, di t-butyl peroxide, t-butyl peracetate and di-t-butyl diperphthal-ate. The initiator i~ generally pre~0nt in amounts of about 0.05 to 10 or 20 psrc2nt or more by weig~t of the acrylate compo~ition. ` : :
In another embod~ment of ~che pre~ent invention, -in the acrylate compo~ition (f) defin~d above, the mono- :
mer can be prepared by the reaction of one mole for in-stance of i~opropyl amine, n-butyl amine or cyanamide wit~
two moles of glycidyl methacrylate. Generally, tha mono-mer will be present in amount3 of about 5 - 80 percent by weight of 3aid compo~ition.
Repr03entative vinyl organic acida includ~
acrylic and the lower alkyl acrylic acid~, preferably me~hacrylic acid.
: Th~ initiator employed i~ t-butyl peracetat2, di-t-butyl dipe~rphthalate or ~-bu~yl perbenzoate, present in amounta of about 1-3 parcent by weight of said compoai-25 ~io~.
., --17-- ' : . .. : :,, : ~ . : -- . -.
~ 3 Th~ trihydroxy ben~ene lnhibitor, preferably pyrogallol i~ pres~nt in amount~ of about 0.1-1.0 and preferably about 0.2-0.5 percent by weight of ~aid com-position.
The accelerator, benzhydrazide or N-amino-r~odanine, i~ pre~ent in amounts of about 0.05 to 0.2 and preferably about 0.10 to 0.15 percent by weight of Raid acrylate compo~ition.
If de~ired, the composition can al80 includ~ ~s a stabilizer an e~ter prepared by reacting acrylic or low-er alkyl a~rylic acid~ with lower alkanol The stabiliz-er can be pre~ent in amounts of about 0-60 percent by weight of the total compo~ition. Moreover~ i~ de~ired a visco~ity-increasing component BUC~ a~ dimerii and tri-meric aliphatic organic acids having from 36 ~o 54 carbonatom~ in amount~ of 0-60 percent by weight of the total composition can be employed.
The inner bearing member of the pre~ent inven-tion can have a bearing 8urface made of a member selected from the group consisting of metal and ceramic. T~us, .
when the inner bearing member i~ metal, it i~ preferably 9tainle~s steel ~wrought or powder metallurgy) ~uch as 440C, 17-4PH and 304 althou~h other metals 9uch a~ case hardened titanium and anodized aluminum can also be em-ployed. When a ceramic 5urface bearing member is employ-:.; , ~ ... .. .. ,. ., " . j - , ,........... ~ .
ed genarally it i~ in the form of a thin ceramic coating on a metal substrate~ The ceramic coat1ng mu~t b~ 8U~fi- :
ciently thin to permit a ~light defonmation th~reof with-out fracturing ~o $hat 8tr~8se8 which would norma~ly build up within t.he coating can be tran~ferred to the ~ubs~rate which has the greate~ ~en ile ~treng~h. Furthermore, the ten~ils ~trangth of t~e ~ubstrat~ mu~t be within a partic ::
ular range. If the ten~ile strength i~ too low, the ~ub-3trate will not provîde prope.r ~upport for the coating 10 with the re~ulting deformation of the ~ubstrate under ~ - :
load, thereby causing fracture~ in the ceramic coating. ~ .
If the ten~ile strength of the ~ubstrate ia too high, the substrate will not provide a proper cushioning effect, ~urface stresses will not be transferred to the ~ub~trate 15 ! and the coating will fracture or otherwisa ~ail a~ a re-sult of such ~tre~ses. In particular, it i9 found that the ten~ile strength of the sub9trate should lie within the range of ~5,000 to 250,000 p9i to achieve a proper balance between ~he tendency of the coating to fracture 20 a8 a resul~ of deformation and the tendency of the coat- .
ing to fracture a~ a reYult of ~urface stresse~. Al90, the~coating~mu~t have a thickness ranging between 0~0001 to 0.02 inch with a t~ickne~ of approxLmate1y 0.004 inch ;
being pre~erred.
Th~ use of titanium or a titanium-ba~ed alloy .
:`
a~ a sub~trate is particularly desirable ~ince thi~ metal provide~ an e9peci~11y good bond with the ceramic coating.
In addlti~n, thi~ tr~te mat~rlal i~ more ch~ically inert than most mat~rial~ which can be used, i~ light in weight and maintain~ its ~trength when ~ubjec:t~d to.rela-tively high t~mperature~ approa~hing 800F~ Al~o, and perhaps most importan~, it has a coef~icient of thermal expan~ion gub~tantially equal to ~hat of the various coat-ing material~ which may be u~ed for the ceramic coating and, therefore, little or no ~tre~9es a~e built up on the coating as a re~ult of differential expan~ion of the ~ub-trate~ and the coating when operating over a wide temper-ature range.
The material of the ceramic coating u~ed on the ~ub~trate may vary widely~ However, it ha~ been found that coating materials made up predominately of one or the other of five specific ba~e compounds provide particu-larly good results, especially in comb~ination with a ~ub- ~
~trate of ti~anium or a titanium-ba~ed alloy such as al~ ~ :
20 loy~ which, in addition to titanium, comprise 5 percent by weight of aluminwm and 2.5 percent by weight of tin (Ti-5Al-2.55n) or 6 percent by weight of aluminum and 4 percent by weight of vanadium (Ti-~1-4V~. ~e five base compounds preferred for the coating materials are: Chro ~5 mi~n oxide (Cr203 ), titanium dioxide (l`iO2 ), aluminu~n :
. i- . . , ':
2~3 oxid~ (A1203), titanium c~rbide tTiC) and tungsten carbide (WC). ~ach of the~e compound~ can ba used in eub~tanti~
ly pure fonm or in combination wit~ other additive~ intend- ~:
ad to produce a more de~irable coating or to ~acilita~e the application of the coating to the sub~trate. $xample~
of mixtures which can be u~ed are: (B0 percent Cr20~ +
20 percent NiCr), (TiC + 5-20 percent ~i), (50 percent ~C + 35 percent ~iCx ~ 15 percent NiAl) and (WC + 9 per~
cent Co), where ~iCr i8 made up of 80 percent Ni and 20 ~, .
percent cr and wherein the percentage~ given are volu~e percentagesO
The inner bearing surface, prior to injection therearound of aaid molded outer bearing i~ provided with a coating o~ a parting or release agent. Representative of ~uch agent~ are polytetrafluoroethylene, ~ilicone, wax emul~ion and the like, said parting agent being employed to protect again~t any adhesion between the inner bearing member and the outer bearing member during the fabrication o~ the latter~
20 ~ In one embodiment of the present invention, the ~: bearing a~se~bly i8 produced by locating the inner bearing member within an outer hou~ing member wi~h the spacing therebetween being ~officient ~o that on injection of the ~i :~ . mixture o~ the curable acryla~e and particulate solid lu-b~icant, no appreciable separation of the latter from the . ~ . ' ;
~4~3 mlxture is experienced. It has been observed that if the gap or spacing between the inner bearing member and the outer housing is too small, such a separation occurs, thereby creating a deEiciency of particulate solid lubri-cant in that portion of the finished or molded outer bearing member which contacts or engages the inner bearing member.
This adverse phenomenon causes a diminution of the otherwise highly favorable room and ele~ated temperature characteris-tics of the bearing assembly. Generally, the spacing between the inner bearing member and the outer housing will be within the range from about 5 to 60 mils (0.005 to 0.06 inch, which is consequently the thickness of the coating of the cured mixture), although it will be recognized, that depending upon the ultimate use to which the bearing assembly is put, as well as the particular configuration of the bearing assembly chosen, the maximum dimension of th~ spacing can be even greater.
The moldable composition of the outer bearing member can be injected into the spacing between the inner bearing member and the outer housing member at a significantly lower pressure than heretofore considered feasible. Thus pressures as low as about 0.25 psi-50 psi can be employed. It will be recognized, however, that because of the flexibility in injection pressure offered by the moldable composition of this invention, higher pressures can be utilized if it is ~ound convenient to do so, the point ' .
- -22~
-, . . . : . . . , ,i. ~
being that a minimum high pr~9ure limitation (in the ord-er of about 1000 pei) i~ not impo~ed on the present de-velo~nent. Further, the moldable outer bearing compo~
tion of the pre~ent invention i8 suficiently flowable at 5 ambi~nt tQmpexature ~ha~ its injection at ~h~ ~tated ~ow pres~ure~ can be effected at ambient temperature, thue eliminating the need for extraneou~ heating device~ and controls to maintain the composition in a state ~u~table .
for injection at the ~tated low pre~3~Ure~;.
If desired, the interior surface oP the outer `
hou~ing m~mber can be treated to enhancs the bonding of the moldable outer bearing compo~ition therewith, 9uch treatment including vapor blas~ing, chemical etching and the like. Importantly, however, it has been found that 15 the moldable outer bearing me~b~sr composition of thi~ in . vention for~ns a l~ond with the outer housing member 9uffi-ciently strong without the need of a mechanical key or , lock through the outer hou~ lng member 90 that in use there ~ ~ ^
i~ no relative movement between the outer houeing member ; 20 and the molded outer bearing member .
: The bearinq as~embly, after injection of the ~ ~ :
moldable outer bearing me~er into the ~pace between the inner bearing member and the outer housing member i8 then cuxed. When it is desired to take advantage of the an-25 aerobic characte.ristic~3 of the acrylate compo9ition, cur-~ 3 ing can be efected in an i~ert a1:mo~ph~re es3entially fre~ from an oxygen-containing ga~ for a period r~nging from about 1/4 to 24 hour~ at a temperakuro ranging fr~m about ambient temp~ratur~ to 325F. On the other h~nd, when it is not de~ired to cure the acrylate compo~ition under an2erobic conditions, it ha~ been found the ~ame can conveniently be cured in the presence of an oxygen~
containing ga3 at a temperature ranging from about 100- ~
325F. for a period ranging from about 1/4 to 2 hour~ -Generally, ~he uae of lower temperaturas require~ a some-what lon~er cure time.
In another embodiment of the present invention, the outer bearing member can be produced by applying ~he curable acrylate compo~ition in the form of a 31urry to ~he inner surface of the outer housing member, curing the 3ame under the conditions set forth above and ~ub~equently machining the cured composition to t~e desired dimensions and tolerance~.
The bearing a~sembly of the present invention ?o exhibits long life and low wear characteri~tics, ls ~elf~
lubricating and thu~ re~uires little or no servicing or maintenance, e~hibite relatively high str2ngth and load carrying characteri~tic~. Furth~r, unlike bearing a~em-; . blie~ utilizing nylon a~ a bearlng member, the acrylate : 25 bearing member of the present inventinn exhibits no tend-.
24~
;
, ~ 2~ 3 ency to ab~orb mol~ture and thu9 .i~ ideally suite~ for ~ :
u~e in a moi~ture environment wlthout ~ny degradation of th~ bond creat~d between the molded outer bearing m~mber and the outer hou~ing member. . .-~efe~ring now to the drawing~ in which prefer-red embodimen~ of the invention are ~hown:
FIGURE 1 i~ a section~l view illustrating the :~ ~
placement of the paxt~ in a mold cavity to produca the ::
bearing a~embly of thi~ invention;
FIGURE 2 i~ a sectional view of the bearing as-sembly of the invention FIGURE 3 i~ a fragmentary ~ectional view of one half of the bearing asse~ly of FIGURE 2 -FI~URE 4 iB a fragmentary sectional view of the 15 inner bearing member of the bearing a3~emh1y of thi~ in-vention;
. FIGURE 5 is a parspective view of a rod end con-, talning a bearing assembly embodying the present invention, parts of the rod end and bearing assembly being broken : ~ 20 away FIG~RE 6 i~ a vertical ~ectional view taken through the rod end of FIGURE 5;
PIGURE 7 is a fragmentary ~ectional view of one .~ ~ : . half o~a bearing assembly con~truction illu~trating an- : :
, .
other embodim~nt of the pre~ent invention:
, ~' ~. ,.
F:~GURE a is a ver~ical ~ectional vi8w of another bearing a~sembly eMbod~m~t of the pr0~ent 1nv~ntion;
FIGURE ~ is a vertical ~ectional view of a metal .,i ~leeve bearing made in accordance with the pre~ent inven- ;
tion;
FIGURE 10 is a vertical ~ectional view o a rod bearing made in accordance with the pres~nt invention;
FIGUR~ 11 is a vertical ~ctional view of a plas-tic ~leeve bearing made in accordance with the pre~ent invention; and FIGURE 12 i~ a fragmentary ~ectional view o a plate bearing made in accordance with the pre~ent inven- ;
tion.
FIGURE 1 shows a mold in whi~h the outer hou~ing ~:
and inner bearing member are po~itioned during the injec~
tion of the curable acrylate compo~ition into the clear-ance between the two member~. The mold i~ compri~ed of ~ ;
upper ~nd lower m~mber~ 10 and 12, respectively, and i8 provided with filling orifice 14 which is in alignment 2n with filling orifice 16 (approx. 0.08 inch in diameter) : -: of the hou~ing me~ber 18. Located laO from filling ori~
fice 16 i~ vent orifice 20 (approx-. 0.04 inch in diameter~
; : in the hou~ing member 18 aligned with vent orifiee 21 of the mold. The inner bearing memher 22 i~ centered within the housing member 18 by means of O-rings 24 and 26 to _26-j :
provide a clearance 28 therebetwe~sn. Tha mold mem~er~, -the hou~ing members and the cen~ered inn~r bearin~ m~mber can be retained in th~ir r~lative po~ition~ by mean~ o a bolt 29 pa~sing ~hrough the base lO and 12 of the a~-S Rembly and fastened tight by nut 31. In forming the oUter beaxirlg merrber 30, the flowable mixture of curable acryl-ate compo3ition and particulate solid luhricant i~ inject-ed under relatively sligh~ pressure at a~ient temp8rature through the aligned filling orifice~3 14 and 16 to fill the 10 clearance 2~. Thi~ mixture can be injected into ~e clear- :
ance or cavity by mean~ of a ~yringe and its introduction i9 continu~sd until it i~ vi~lbly ejected through the vent :
orifices 20 and 21~ The acrylate composiltion i~ then eur- : :
ed either (1) by placing th~ total mold assen~ly into an 15 enclo~ure maintained with an essentially oxygen gas-free environment and at a temperature ranging from anibient tem-perature to 325F, for a period ranging from about 1/4 to 24 hours or (2) by placing ths mold a~embly in an enclos-ure maintained with an oxygen-containing ga~ environment and at a temperature ranging from about lQ0-325F, for a : period ranging from about 1/4 to 2 hours.
FIGURE 2 9h~w~ one embodLment of the bearing aa3embly 23 of the preeent invention after being cured ; and removed ~rom the mold a~sembly and a~ can be seen in ~25 FIGURE 3, the minimum inn~r diameter of the hou~ing mem-: . ,... .. ,. ~,. ... .
ber 1~3 can be l~s~ than the maximwn oUte:r diameter of the inner bearing member 22.
In FIGURE 4 there i~ illustratsd in detail the inner bearing membar 22 having on the bearing ~urface en~
S gaging the molded outer bearing memb~r ~0 a thln film of parting or release agent 32 which i~ applied to ~he ~ur-fac~ of tha inner bearing member 22 prior to molding ~aid outer bearing men~3r thereabout. ~e outer b~3aring mem-ber 30 ~hown in FIGURE 4 i~ one produced from a metal ~ub-lt) strate 34 coated with a ce~amic l~yer 36, ~3ach a1 he~rein- :
~be f o re de f ined .
FIGURES 5 an~ 6 show, by way of e~ ple, a rod end containing a beaxing a3~mbly of the pre~ent invention. ~ :
The rod end i~ oompri9ed of an externally threaded ~anjo 15 38 having a tran~verse bore whic~ receive~ the bearing as-~embly of thi~ invention, generally indica~ed at 23. The .
two coengaging and relatively ~lidab~ member3 of the bear-ing a~embly con~i~t of the inner ball member 22 and the outer molded pla~tio bearing member 30 which i8 in molded non-rotative engagement with outer hou~ing member 18 which in turn is in fixed non-rotative engagement with the annu-lar 9eating ~urface on the banjo 38 by ~waging both sid~
of the housing member 18.
In use, the threaded portion of the banjo 38 is ~5 threadably conn~cted with one mechani~m part and another --2~3--~ 3 mechani3m part l~ connected to t~l~ inner b~aring member 22 by ~ connecting member insert3d throu~h its bore 2~'~
FIGURE 7 qhow~ another embodiment of the inYen-tlon where the b~aring as~embly compri~é~ an outer bear-ing housing 18, an ou~er molded pla~tic bearlng 30, a split inner race 22 and an inner race tllrough bu~hing 40. :.
The outer pla~tic race 30 i~ molded between the houeing 18 and innQr bearing 22 in a manner e~entially a~ de-~cribed above 80 that while there i~ no relative movement --between the outex bearing 30 and the outer race hou~ing 18 thera is rela-tive mov~ment between th~ outer bearing 30 and the inner bearing 22. -~
~ he inner ~ide of th~ outex b~aring 30 ~orm~ a pair of oppo~ed annular be~ring surface~ 42 and 44 having concave ~pherical curvature~ which cooperate with the in-ner bearing 22 to permit relative sliding movement between the inner and outer bearing members even though the bear-ing i~ ~ubjected to radial, axial and moment loading indi-vidually or in combination.
20 ~: ThQ Bplit inner bearing member 22 comprises two annular member~ 46 and 48. The~e annular member~ are -~
formed with hardened metal or with me~al Bubstrate~ coated . ~
~ with:a~c-ramic material a~ di~closed her~tofora. In t~e : ~ .:
preferred form, the substrates 50, 52 are titanium and the c~ramic coating~ 54, 56 ar~ chrom~um oxide. The outer , : ~ :
. . . .
' bearing ~urfa~e3 54, 56 of each n~e,Q~ber 46, 4E3 of the in-ner bearing 22 are comp~ementary to the annular bearing surface~ 42, 44 c~f the outer bearing 30 having 3pheri~al ~urvature~ whereby the coengaging ~urface~ coop~rate to 5 form a bearing capable of ab~30rbing radial, axial and moment loading individually or in co~bination.
The member~ 46 and 48 of the eplit inner bear-ing 22 are held in contact with the bearing ~urfac~3 42, 44 of the outer bearing member 30 by means of a cylindrl-cal bushing 40 which ha3 an integral shoulder 58 at one end and a snapping or 8imilar locking means 60 on the oth-er end to retain the members on the ~u~hing. The split inner bearing is pre~s fit; bonded or otherwise secured -to bu~hing 40 ~o prevent relative movement between the 15 bu~hing and the inner bearing. It will be appr~ciated ~:
that complementary conical rather than ~p~erically curved bearing surfaces can be provided and that maans equivale~t to the 9plit bearing bu~hing mean~ 40 can al90 be utilized.
FIGU~E 8 ~how~ another embodiment of the inven-tion where the bearing as~emhly compri~ee an outer bear-ing houeing 62, an outer molded pla9tic bearing 64 and an inner bearing member 66 which can compri8e a thru~t wa3her or ring mechanically locked in place. The outer pla~tic bearing 64 is molded between the housing 62 and the inner bearing 66 in a manner es~entially a~ described above ~o ' . . ', , ' : ' . . ' , ~
that while there i9 no relative movement between th~ out-er bearing 64 and the outer bearing hou~ ing 62 thsre i~
relative movement b~twe~n th~ outer bearlng 64 and the .:
inner bearlng 66.
FIGURE 9 show~ ~ another ~mbodiment o~ the in-vention a hollow cylindrical ~leeve bearing 6~, th~ inter- -nal ~urface 70 of the hollow cylindrical backing member 72 being provided with a plastic bearing member 74, ~here being no relative mov~ment between bearing member 74 and the internal surface 70 of the backing member 72. 1'}~
plastic bearing member 74 can be applied to the internal surface 70 of the ~leeve b~3aring backing member 72 by any convenient mean~, such a~ by molding the same thereto, or by coating the internal surface by ~preading or ~praying the acrylate compo~ition onto the ~aid internal ~urface~
If de~ired, after the acrylate compo~ition ~a8 cured, the ~ame can be machined to the desired dimen8i~n.
FIGURE 10 shows another embodiment of 301id cy-lindrical sleeve bearing 76, the external surface 78 of 20 :the solid cylindrical backing rnember B0 being provided with à plastic bearing member 82. Again there i9 no rel~
atlve moveJnent~ b~etween the plastic bearing member 82 and ~ .
the external surface 78 of the backing member 80. q~he pla~tic bearing meniber 82 can be applied to the exte.rnal 25 sur~ace of th~ ~leeve bearing backing member 80 also by a ~ .
.... . . . ,. . . . . . , -: -- .. ~ . . . . ... .. . .
J3L~9~ L~ 3 molding technique or by spraying, dippi~g or ~preading the acrylate ~ompoeition onto ~aid external ~urface. obviou~-ly other conventional coating techniqueA can al~o be em-ployed. Again th~ d~sired thickne6~ of ~h~ pla~tic bear-ing member 74 can be achieved by machining the same.
FIGURE 11 show~ a hollow cylindrical slee~e bearing 84 ~imilar to that of FI~URE 9. The internal 3ur~
face B6 of the holl~w cylindrical backing member 88 i8 provided with 2 pla~tic bearing memb~r 90 compri~ing the cured acrylate composition of this invention. ~he hollow cylindr.ical backing member 88 in thi~ in~tanca can be, for instance, a cured phenolic re~in or the like and the ; :~
bearing can be made in a manner outlined above. ~ -FIGU~E 12 ~hows a plate bearing 92, the 9Ub-strate 94 being provided on at least one planar ~urface 96 thereof with a plastic bearing member 98 compriRing the cured acrylate composition of this invention. Again this pla~tic bearing member 98 can be provided on the planar surface 96 by any conventional mean~ and can be machined, if desired to the desired dimension~.
- i . ~ . - -. : . , .
The oxyalkylamine accelerator can be present in amounts of about 0~1 - 10 percent or more by weight of the acryl-ate composition.
ExampleY of suitable peroxidic initiator~ in~
clude cumene hydroperoxide, t-butyl hydroperoxide, methyl-ethylketone hydropero~ide or peroxide, tetralin hydroper-oxide, benzoyl peroxide, lauroyl peroxide and ditertiary butyl diperphthalate~ The initiator is present generally in amount~ 0.1 - 10 or 15 percent by weight of the acryl-15 ate compo~itionO
In a further embodiment of the present inven-tion, in the acrylate composition (e) defined above, the acrylic e~ter monomer can alRo be that employed, for in-tance, in acrylate compo~itions (a), (b) and (c).
U~eful accelerator~ include rhodanine and or~
: ganic hydrazides having the formula H O
.
H - N - N - C - R
:; : R' wherein R is selected from the group con~iRting of hydro-~15-2~3 gen, alkyl, cycloalkyl, aryl and alko~cy and R ' is3 ~elect-ed from the grDup con~ieting of hydrogen, alkyl, cyclo-alkyl, and acyl. The group R and FZ' can b~3 connected to ~ach other dir~ctly or indirectly throu~h S other atom~ or group~ to ~orm a ring ~y~tem, a~ ill N-aminor hodanine H2M-N-CO-CH2-S~S, N-aminourazole H2N N-CS~-~H-~H~0 and P~-aminophthalimlde _' ~
0 H2N-N-CO ~:~ . 'rhU9 R and R' can con~titute the ring CO ~
~tructure of a cyclic amide ~uch as the ring ~tructure of rhodanine, glyoxalylurea, mesoxalylurea, alloxanic ~cid, pyrazolone and pherlazone. Representatives ac-, , ~4~3 celerators include rhodanirle and N-amino rhodanine.
The accelerator can be pre~ent in amount8 of about 0.001 to 10 or more weight percen~ o the acrylat~ compo~i~lo~. :
Representative peroxidi~ initiatoxe include cumene hydroperoxide, t butyl hydroperoxide, methylethyl- -ketonQ hy~roperoxide, tetxalin hydrop~roxi~e, di t-butyl peroxide, t-butyl peracetate and di-t-butyl diperphthal-ate. The initiator i~ generally pre~0nt in amounts of about 0.05 to 10 or 20 psrc2nt or more by weig~t of the acrylate compo~ition. ` : :
In another embod~ment of ~che pre~ent invention, -in the acrylate compo~ition (f) defin~d above, the mono- :
mer can be prepared by the reaction of one mole for in-stance of i~opropyl amine, n-butyl amine or cyanamide wit~
two moles of glycidyl methacrylate. Generally, tha mono-mer will be present in amount3 of about 5 - 80 percent by weight of 3aid compo~ition.
Repr03entative vinyl organic acida includ~
acrylic and the lower alkyl acrylic acid~, preferably me~hacrylic acid.
: Th~ initiator employed i~ t-butyl peracetat2, di-t-butyl dipe~rphthalate or ~-bu~yl perbenzoate, present in amounta of about 1-3 parcent by weight of said compoai-25 ~io~.
., --17-- ' : . .. : :,, : ~ . : -- . -.
~ 3 Th~ trihydroxy ben~ene lnhibitor, preferably pyrogallol i~ pres~nt in amount~ of about 0.1-1.0 and preferably about 0.2-0.5 percent by weight of ~aid com-position.
The accelerator, benzhydrazide or N-amino-r~odanine, i~ pre~ent in amounts of about 0.05 to 0.2 and preferably about 0.10 to 0.15 percent by weight of Raid acrylate compo~ition.
If de~ired, the composition can al80 includ~ ~s a stabilizer an e~ter prepared by reacting acrylic or low-er alkyl a~rylic acid~ with lower alkanol The stabiliz-er can be pre~ent in amounts of about 0-60 percent by weight of the total compo~ition. Moreover~ i~ de~ired a visco~ity-increasing component BUC~ a~ dimerii and tri-meric aliphatic organic acids having from 36 ~o 54 carbonatom~ in amount~ of 0-60 percent by weight of the total composition can be employed.
The inner bearing member of the pre~ent inven-tion can have a bearing 8urface made of a member selected from the group consisting of metal and ceramic. T~us, .
when the inner bearing member i~ metal, it i~ preferably 9tainle~s steel ~wrought or powder metallurgy) ~uch as 440C, 17-4PH and 304 althou~h other metals 9uch a~ case hardened titanium and anodized aluminum can also be em-ployed. When a ceramic 5urface bearing member is employ-:.; , ~ ... .. .. ,. ., " . j - , ,........... ~ .
ed genarally it i~ in the form of a thin ceramic coating on a metal substrate~ The ceramic coat1ng mu~t b~ 8U~fi- :
ciently thin to permit a ~light defonmation th~reof with-out fracturing ~o $hat 8tr~8se8 which would norma~ly build up within t.he coating can be tran~ferred to the ~ubs~rate which has the greate~ ~en ile ~treng~h. Furthermore, the ten~ils ~trangth of t~e ~ubstrat~ mu~t be within a partic ::
ular range. If the ten~ile strength i~ too low, the ~ub-3trate will not provîde prope.r ~upport for the coating 10 with the re~ulting deformation of the ~ubstrate under ~ - :
load, thereby causing fracture~ in the ceramic coating. ~ .
If the ten~ile strength of the ~ubstrate ia too high, the substrate will not provide a proper cushioning effect, ~urface stresses will not be transferred to the ~ub~trate 15 ! and the coating will fracture or otherwisa ~ail a~ a re-sult of such ~tre~ses. In particular, it i9 found that the ten~ile strength of the sub9trate should lie within the range of ~5,000 to 250,000 p9i to achieve a proper balance between ~he tendency of the coating to fracture 20 a8 a resul~ of deformation and the tendency of the coat- .
ing to fracture a~ a reYult of ~urface stresse~. Al90, the~coating~mu~t have a thickness ranging between 0~0001 to 0.02 inch with a t~ickne~ of approxLmate1y 0.004 inch ;
being pre~erred.
Th~ use of titanium or a titanium-ba~ed alloy .
:`
a~ a sub~trate is particularly desirable ~ince thi~ metal provide~ an e9peci~11y good bond with the ceramic coating.
In addlti~n, thi~ tr~te mat~rlal i~ more ch~ically inert than most mat~rial~ which can be used, i~ light in weight and maintain~ its ~trength when ~ubjec:t~d to.rela-tively high t~mperature~ approa~hing 800F~ Al~o, and perhaps most importan~, it has a coef~icient of thermal expan~ion gub~tantially equal to ~hat of the various coat-ing material~ which may be u~ed for the ceramic coating and, therefore, little or no ~tre~9es a~e built up on the coating as a re~ult of differential expan~ion of the ~ub-trate~ and the coating when operating over a wide temper-ature range.
The material of the ceramic coating u~ed on the ~ub~trate may vary widely~ However, it ha~ been found that coating materials made up predominately of one or the other of five specific ba~e compounds provide particu-larly good results, especially in comb~ination with a ~ub- ~
~trate of ti~anium or a titanium-ba~ed alloy such as al~ ~ :
20 loy~ which, in addition to titanium, comprise 5 percent by weight of aluminwm and 2.5 percent by weight of tin (Ti-5Al-2.55n) or 6 percent by weight of aluminum and 4 percent by weight of vanadium (Ti-~1-4V~. ~e five base compounds preferred for the coating materials are: Chro ~5 mi~n oxide (Cr203 ), titanium dioxide (l`iO2 ), aluminu~n :
. i- . . , ':
2~3 oxid~ (A1203), titanium c~rbide tTiC) and tungsten carbide (WC). ~ach of the~e compound~ can ba used in eub~tanti~
ly pure fonm or in combination wit~ other additive~ intend- ~:
ad to produce a more de~irable coating or to ~acilita~e the application of the coating to the sub~trate. $xample~
of mixtures which can be u~ed are: (B0 percent Cr20~ +
20 percent NiCr), (TiC + 5-20 percent ~i), (50 percent ~C + 35 percent ~iCx ~ 15 percent NiAl) and (WC + 9 per~
cent Co), where ~iCr i8 made up of 80 percent Ni and 20 ~, .
percent cr and wherein the percentage~ given are volu~e percentagesO
The inner bearing surface, prior to injection therearound of aaid molded outer bearing i~ provided with a coating o~ a parting or release agent. Representative of ~uch agent~ are polytetrafluoroethylene, ~ilicone, wax emul~ion and the like, said parting agent being employed to protect again~t any adhesion between the inner bearing member and the outer bearing member during the fabrication o~ the latter~
20 ~ In one embodiment of the present invention, the ~: bearing a~se~bly i8 produced by locating the inner bearing member within an outer hou~ing member wi~h the spacing therebetween being ~officient ~o that on injection of the ~i :~ . mixture o~ the curable acryla~e and particulate solid lu-b~icant, no appreciable separation of the latter from the . ~ . ' ;
~4~3 mlxture is experienced. It has been observed that if the gap or spacing between the inner bearing member and the outer housing is too small, such a separation occurs, thereby creating a deEiciency of particulate solid lubri-cant in that portion of the finished or molded outer bearing member which contacts or engages the inner bearing member.
This adverse phenomenon causes a diminution of the otherwise highly favorable room and ele~ated temperature characteris-tics of the bearing assembly. Generally, the spacing between the inner bearing member and the outer housing will be within the range from about 5 to 60 mils (0.005 to 0.06 inch, which is consequently the thickness of the coating of the cured mixture), although it will be recognized, that depending upon the ultimate use to which the bearing assembly is put, as well as the particular configuration of the bearing assembly chosen, the maximum dimension of th~ spacing can be even greater.
The moldable composition of the outer bearing member can be injected into the spacing between the inner bearing member and the outer housing member at a significantly lower pressure than heretofore considered feasible. Thus pressures as low as about 0.25 psi-50 psi can be employed. It will be recognized, however, that because of the flexibility in injection pressure offered by the moldable composition of this invention, higher pressures can be utilized if it is ~ound convenient to do so, the point ' .
- -22~
-, . . . : . . . , ,i. ~
being that a minimum high pr~9ure limitation (in the ord-er of about 1000 pei) i~ not impo~ed on the present de-velo~nent. Further, the moldable outer bearing compo~
tion of the pre~ent invention i8 suficiently flowable at 5 ambi~nt tQmpexature ~ha~ its injection at ~h~ ~tated ~ow pres~ure~ can be effected at ambient temperature, thue eliminating the need for extraneou~ heating device~ and controls to maintain the composition in a state ~u~table .
for injection at the ~tated low pre~3~Ure~;.
If desired, the interior surface oP the outer `
hou~ing m~mber can be treated to enhancs the bonding of the moldable outer bearing compo~ition therewith, 9uch treatment including vapor blas~ing, chemical etching and the like. Importantly, however, it has been found that 15 the moldable outer bearing me~b~sr composition of thi~ in . vention for~ns a l~ond with the outer housing member 9uffi-ciently strong without the need of a mechanical key or , lock through the outer hou~ lng member 90 that in use there ~ ~ ^
i~ no relative movement between the outer houeing member ; 20 and the molded outer bearing member .
: The bearinq as~embly, after injection of the ~ ~ :
moldable outer bearing me~er into the ~pace between the inner bearing member and the outer housing member i8 then cuxed. When it is desired to take advantage of the an-25 aerobic characte.ristic~3 of the acrylate compo9ition, cur-~ 3 ing can be efected in an i~ert a1:mo~ph~re es3entially fre~ from an oxygen-containing ga~ for a period r~nging from about 1/4 to 24 hour~ at a temperakuro ranging fr~m about ambient temp~ratur~ to 325F. On the other h~nd, when it is not de~ired to cure the acrylate compo~ition under an2erobic conditions, it ha~ been found the ~ame can conveniently be cured in the presence of an oxygen~
containing ga3 at a temperature ranging from about 100- ~
325F. for a period ranging from about 1/4 to 2 hour~ -Generally, ~he uae of lower temperaturas require~ a some-what lon~er cure time.
In another embodiment of the present invention, the outer bearing member can be produced by applying ~he curable acrylate compo~ition in the form of a 31urry to ~he inner surface of the outer housing member, curing the 3ame under the conditions set forth above and ~ub~equently machining the cured composition to t~e desired dimensions and tolerance~.
The bearing a~sembly of the present invention ?o exhibits long life and low wear characteri~tics, ls ~elf~
lubricating and thu~ re~uires little or no servicing or maintenance, e~hibite relatively high str2ngth and load carrying characteri~tic~. Furth~r, unlike bearing a~em-; . blie~ utilizing nylon a~ a bearlng member, the acrylate : 25 bearing member of the present inventinn exhibits no tend-.
24~
;
, ~ 2~ 3 ency to ab~orb mol~ture and thu9 .i~ ideally suite~ for ~ :
u~e in a moi~ture environment wlthout ~ny degradation of th~ bond creat~d between the molded outer bearing m~mber and the outer hou~ing member. . .-~efe~ring now to the drawing~ in which prefer-red embodimen~ of the invention are ~hown:
FIGURE 1 i~ a section~l view illustrating the :~ ~
placement of the paxt~ in a mold cavity to produca the ::
bearing a~embly of thi~ invention;
FIGURE 2 i~ a sectional view of the bearing as-sembly of the invention FIGURE 3 i~ a fragmentary ~ectional view of one half of the bearing asse~ly of FIGURE 2 -FI~URE 4 iB a fragmentary sectional view of the 15 inner bearing member of the bearing a3~emh1y of thi~ in-vention;
. FIGURE 5 is a parspective view of a rod end con-, talning a bearing assembly embodying the present invention, parts of the rod end and bearing assembly being broken : ~ 20 away FIG~RE 6 i~ a vertical ~ectional view taken through the rod end of FIGURE 5;
PIGURE 7 is a fragmentary ~ectional view of one .~ ~ : . half o~a bearing assembly con~truction illu~trating an- : :
, .
other embodim~nt of the pre~ent invention:
, ~' ~. ,.
F:~GURE a is a ver~ical ~ectional vi8w of another bearing a~sembly eMbod~m~t of the pr0~ent 1nv~ntion;
FIGURE ~ is a vertical ~ectional view of a metal .,i ~leeve bearing made in accordance with the pre~ent inven- ;
tion;
FIGURE 10 is a vertical ~ectional view o a rod bearing made in accordance with the pres~nt invention;
FIGUR~ 11 is a vertical ~ctional view of a plas-tic ~leeve bearing made in accordance with the pre~ent invention; and FIGURE 12 i~ a fragmentary ~ectional view o a plate bearing made in accordance with the pre~ent inven- ;
tion.
FIGURE 1 shows a mold in whi~h the outer hou~ing ~:
and inner bearing member are po~itioned during the injec~
tion of the curable acrylate compo~ition into the clear-ance between the two member~. The mold i~ compri~ed of ~ ;
upper ~nd lower m~mber~ 10 and 12, respectively, and i8 provided with filling orifice 14 which is in alignment 2n with filling orifice 16 (approx. 0.08 inch in diameter) : -: of the hou~ing me~ber 18. Located laO from filling ori~
fice 16 i~ vent orifice 20 (approx-. 0.04 inch in diameter~
; : in the hou~ing member 18 aligned with vent orifiee 21 of the mold. The inner bearing memher 22 i~ centered within the housing member 18 by means of O-rings 24 and 26 to _26-j :
provide a clearance 28 therebetwe~sn. Tha mold mem~er~, -the hou~ing members and the cen~ered inn~r bearin~ m~mber can be retained in th~ir r~lative po~ition~ by mean~ o a bolt 29 pa~sing ~hrough the base lO and 12 of the a~-S Rembly and fastened tight by nut 31. In forming the oUter beaxirlg merrber 30, the flowable mixture of curable acryl-ate compo3ition and particulate solid luhricant i~ inject-ed under relatively sligh~ pressure at a~ient temp8rature through the aligned filling orifice~3 14 and 16 to fill the 10 clearance 2~. Thi~ mixture can be injected into ~e clear- :
ance or cavity by mean~ of a ~yringe and its introduction i9 continu~sd until it i~ vi~lbly ejected through the vent :
orifices 20 and 21~ The acrylate composiltion i~ then eur- : :
ed either (1) by placing th~ total mold assen~ly into an 15 enclo~ure maintained with an essentially oxygen gas-free environment and at a temperature ranging from anibient tem-perature to 325F, for a period ranging from about 1/4 to 24 hours or (2) by placing ths mold a~embly in an enclos-ure maintained with an oxygen-containing ga~ environment and at a temperature ranging from about lQ0-325F, for a : period ranging from about 1/4 to 2 hours.
FIGURE 2 9h~w~ one embodLment of the bearing aa3embly 23 of the preeent invention after being cured ; and removed ~rom the mold a~sembly and a~ can be seen in ~25 FIGURE 3, the minimum inn~r diameter of the hou~ing mem-: . ,... .. ,. ~,. ... .
ber 1~3 can be l~s~ than the maximwn oUte:r diameter of the inner bearing member 22.
In FIGURE 4 there i~ illustratsd in detail the inner bearing membar 22 having on the bearing ~urface en~
S gaging the molded outer bearing memb~r ~0 a thln film of parting or release agent 32 which i~ applied to ~he ~ur-fac~ of tha inner bearing member 22 prior to molding ~aid outer bearing men~3r thereabout. ~e outer b~3aring mem-ber 30 ~hown in FIGURE 4 i~ one produced from a metal ~ub-lt) strate 34 coated with a ce~amic l~yer 36, ~3ach a1 he~rein- :
~be f o re de f ined .
FIGURES 5 an~ 6 show, by way of e~ ple, a rod end containing a beaxing a3~mbly of the pre~ent invention. ~ :
The rod end i~ oompri9ed of an externally threaded ~anjo 15 38 having a tran~verse bore whic~ receive~ the bearing as-~embly of thi~ invention, generally indica~ed at 23. The .
two coengaging and relatively ~lidab~ member3 of the bear-ing a~embly con~i~t of the inner ball member 22 and the outer molded pla~tio bearing member 30 which i8 in molded non-rotative engagement with outer hou~ing member 18 which in turn is in fixed non-rotative engagement with the annu-lar 9eating ~urface on the banjo 38 by ~waging both sid~
of the housing member 18.
In use, the threaded portion of the banjo 38 is ~5 threadably conn~cted with one mechani~m part and another --2~3--~ 3 mechani3m part l~ connected to t~l~ inner b~aring member 22 by ~ connecting member insert3d throu~h its bore 2~'~
FIGURE 7 qhow~ another embodiment of the inYen-tlon where the b~aring as~embly compri~é~ an outer bear-ing housing 18, an ou~er molded pla~tic bearlng 30, a split inner race 22 and an inner race tllrough bu~hing 40. :.
The outer pla~tic race 30 i~ molded between the houeing 18 and innQr bearing 22 in a manner e~entially a~ de-~cribed above 80 that while there i~ no relative movement --between the outex bearing 30 and the outer race hou~ing 18 thera is rela-tive mov~ment between th~ outer bearing 30 and the inner bearing 22. -~
~ he inner ~ide of th~ outex b~aring 30 ~orm~ a pair of oppo~ed annular be~ring surface~ 42 and 44 having concave ~pherical curvature~ which cooperate with the in-ner bearing 22 to permit relative sliding movement between the inner and outer bearing members even though the bear-ing i~ ~ubjected to radial, axial and moment loading indi-vidually or in combination.
20 ~: ThQ Bplit inner bearing member 22 comprises two annular member~ 46 and 48. The~e annular member~ are -~
formed with hardened metal or with me~al Bubstrate~ coated . ~
~ with:a~c-ramic material a~ di~closed her~tofora. In t~e : ~ .:
preferred form, the substrates 50, 52 are titanium and the c~ramic coating~ 54, 56 ar~ chrom~um oxide. The outer , : ~ :
. . . .
' bearing ~urfa~e3 54, 56 of each n~e,Q~ber 46, 4E3 of the in-ner bearing 22 are comp~ementary to the annular bearing surface~ 42, 44 c~f the outer bearing 30 having 3pheri~al ~urvature~ whereby the coengaging ~urface~ coop~rate to 5 form a bearing capable of ab~30rbing radial, axial and moment loading individually or in co~bination.
The member~ 46 and 48 of the eplit inner bear-ing 22 are held in contact with the bearing ~urfac~3 42, 44 of the outer bearing member 30 by means of a cylindrl-cal bushing 40 which ha3 an integral shoulder 58 at one end and a snapping or 8imilar locking means 60 on the oth-er end to retain the members on the ~u~hing. The split inner bearing is pre~s fit; bonded or otherwise secured -to bu~hing 40 ~o prevent relative movement between the 15 bu~hing and the inner bearing. It will be appr~ciated ~:
that complementary conical rather than ~p~erically curved bearing surfaces can be provided and that maans equivale~t to the 9plit bearing bu~hing mean~ 40 can al90 be utilized.
FIGU~E 8 ~how~ another embodiment of the inven-tion where the bearing as~emhly compri~ee an outer bear-ing houeing 62, an outer molded pla9tic bearing 64 and an inner bearing member 66 which can compri8e a thru~t wa3her or ring mechanically locked in place. The outer pla~tic bearing 64 is molded between the housing 62 and the inner bearing 66 in a manner es~entially a~ described above ~o ' . . ', , ' : ' . . ' , ~
that while there i9 no relative movement between th~ out-er bearing 64 and the outer bearing hou~ ing 62 thsre i~
relative movement b~twe~n th~ outer bearlng 64 and the .:
inner bearlng 66.
FIGURE 9 show~ ~ another ~mbodiment o~ the in-vention a hollow cylindrical ~leeve bearing 6~, th~ inter- -nal ~urface 70 of the hollow cylindrical backing member 72 being provided with a plastic bearing member 74, ~here being no relative mov~ment between bearing member 74 and the internal surface 70 of the backing member 72. 1'}~
plastic bearing member 74 can be applied to the internal surface 70 of the ~leeve b~3aring backing member 72 by any convenient mean~, such a~ by molding the same thereto, or by coating the internal surface by ~preading or ~praying the acrylate compo~ition onto the ~aid internal ~urface~
If de~ired, after the acrylate compo~ition ~a8 cured, the ~ame can be machined to the desired dimen8i~n.
FIGURE 10 shows another embodiment of 301id cy-lindrical sleeve bearing 76, the external surface 78 of 20 :the solid cylindrical backing rnember B0 being provided with à plastic bearing member 82. Again there i9 no rel~
atlve moveJnent~ b~etween the plastic bearing member 82 and ~ .
the external surface 78 of the backing member 80. q~he pla~tic bearing meniber 82 can be applied to the exte.rnal 25 sur~ace of th~ ~leeve bearing backing member 80 also by a ~ .
.... . . . ,. . . . . . , -: -- .. ~ . . . . ... .. . .
J3L~9~ L~ 3 molding technique or by spraying, dippi~g or ~preading the acrylate ~ompoeition onto ~aid external ~urface. obviou~-ly other conventional coating techniqueA can al~o be em-ployed. Again th~ d~sired thickne6~ of ~h~ pla~tic bear-ing member 74 can be achieved by machining the same.
FIGURE 11 show~ a hollow cylindrical slee~e bearing 84 ~imilar to that of FI~URE 9. The internal 3ur~
face B6 of the holl~w cylindrical backing member 88 i8 provided with 2 pla~tic bearing memb~r 90 compri~ing the cured acrylate composition of this invention. ~he hollow cylindr.ical backing member 88 in thi~ in~tanca can be, for instance, a cured phenolic re~in or the like and the ; :~
bearing can be made in a manner outlined above. ~ -FIGU~E 12 ~hows a plate bearing 92, the 9Ub-strate 94 being provided on at least one planar ~urface 96 thereof with a plastic bearing member 98 compriRing the cured acrylate composition of this invention. Again this pla~tic bearing member 98 can be provided on the planar surface 96 by any conventional mean~ and can be machined, if desired to the desired dimension~.
- i . ~ . - -. : . , .
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A shaped bearing member comprising a substrate provided with a coating of a cured mixture of an acrylate composition and a particulate solid lubricant, said coating having a thickness within the range from 0.002 to 0.125 inch.
2. The shaped bearing member of claim 1 wherein said coating has a thickness within the range. from 0.005 to 0.06 inch.
3. The shaped bearing member of claim 1 or 2 wherein said acrylate composition in the cured mixture forming said coating is selected from the group consisting of:
(a) a mixture of a major amount of a liquid acrylic ester selected from the group consisting of di-, tri-and tetraesters of an acrylic acid and a polyhydric alcohol, a minor amount of a low molecular-weight prepolymer of an ester of a low molecular weight alcohol having a terminal vinyl group and an aromatic polycarboxylic acid in solution in said acrylic ester and an organic amide of the formula wherein R is selected from the group consisting of hydrogen and aliphatic hydrocarbon of 1-20 carbon atoms in an amount sufficient to copolymerize said acrylic ester and prepolymer, (b) a mixture of acrylic ester monomer, a per-oxidic initiator in an amount sufficient to initiate polymer-ization of said monomer and an aminoalkoxyalkylamine of the formula R1-N(H)R2[OR3]xN(H)R4 wherein x is an integer of 1-6 inclusive, each of R1 and R4 is selected from the group consisting of hydrogen and lower alkyl and each of R2 and R3 is a lower alkyl linking bridge between N and O, in an amount sufficient to accelerate the polymerization of said monomer, (c) a mixture of an acrylic ester of an alkyl amino alkyl alcohol and an effective amount of hydro-peroxide catalyst, said acrylic ester having the formula wherein x is an integer of 0-5 inclusive, y is an in-teger of 1-6 inclusive, R is selected from the group consisting of hydrogen, halogen, hydroxy, cyano and lower alkyl and R1 is selected from the group consisting of hydrogen and alkyl having 1-6 carbon atoms, (d) a mixture of a liquid acrylic ester monomer selected from the group consisting of diesters of an acrylic acid and a polyhydric alcohol, acrylic esters of cyclic etheralcohols, acrylic esters of amino alcohols and mixtures thereof, a peroxidic initiator and an oxyalkylamine of the formula (H)mN [(CH2)x(OR1) yOR2]n wherein m and n are each integers of 1 to-2 inclusive, the total of m and n is 3, x is an integer of 1 to 6 inclusive, y is an integer of 0 to 6 inclu-sive, R1 is lower alkyl and R2 is hydrogen or lower alkyl, (e) a mixture of an acrylic ester monomer se-lected from the group consisting of di-, tri-, and tetra-esters of an acrylic acid and a polyhdric alcohol, acrylic esters of cyclic ether alcohols, acrylic esters of amino alcohols and mixtures there-of, a peroxidic initiator of an amount sufficient to initiate polymerization of said monomer and a member selected from the group consisting of rhodanine and a hydrazide of the formula wherein R and R1 are selected from separate, groups and an interconnected group forming a cyclic ring, R is further selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl and alkoxy and R1 is selected from the group consisting of hydrogen and alkyl, cycloalkyl, and acyl in an amount sufficient to accelerate the polyerization of said monomer; and (f) a mixture of a monomer of the formula wherein R1 and R2 are selected from the group consisting of hydrogen and lower alkyl and R3 is selected from the group consisting of lower alkyl, lower hydroxyalkyl, cyano and lower cyanoalkyl; at least one equivalent of an acid for each equivalent of said monomer, said acid being selected from the group consisting of acrylic acid and lower alkyl acrylic acids; an initiator selected from the group consisting of t-butyl per-benzoate, t-butyl peracetate and di-t-butyl diperphtha-late, said initiator being present in an amount suf-ficient to initiate the polymerization of said monomer;
a trihydroxy benzene inhibitor and an accelerator sel-ected from the group consisting of benzhydrazide and N-aminorhohanine.
(a) a mixture of a major amount of a liquid acrylic ester selected from the group consisting of di-, tri-and tetraesters of an acrylic acid and a polyhydric alcohol, a minor amount of a low molecular-weight prepolymer of an ester of a low molecular weight alcohol having a terminal vinyl group and an aromatic polycarboxylic acid in solution in said acrylic ester and an organic amide of the formula wherein R is selected from the group consisting of hydrogen and aliphatic hydrocarbon of 1-20 carbon atoms in an amount sufficient to copolymerize said acrylic ester and prepolymer, (b) a mixture of acrylic ester monomer, a per-oxidic initiator in an amount sufficient to initiate polymer-ization of said monomer and an aminoalkoxyalkylamine of the formula R1-N(H)R2[OR3]xN(H)R4 wherein x is an integer of 1-6 inclusive, each of R1 and R4 is selected from the group consisting of hydrogen and lower alkyl and each of R2 and R3 is a lower alkyl linking bridge between N and O, in an amount sufficient to accelerate the polymerization of said monomer, (c) a mixture of an acrylic ester of an alkyl amino alkyl alcohol and an effective amount of hydro-peroxide catalyst, said acrylic ester having the formula wherein x is an integer of 0-5 inclusive, y is an in-teger of 1-6 inclusive, R is selected from the group consisting of hydrogen, halogen, hydroxy, cyano and lower alkyl and R1 is selected from the group consisting of hydrogen and alkyl having 1-6 carbon atoms, (d) a mixture of a liquid acrylic ester monomer selected from the group consisting of diesters of an acrylic acid and a polyhydric alcohol, acrylic esters of cyclic etheralcohols, acrylic esters of amino alcohols and mixtures thereof, a peroxidic initiator and an oxyalkylamine of the formula (H)mN [(CH2)x(OR1) yOR2]n wherein m and n are each integers of 1 to-2 inclusive, the total of m and n is 3, x is an integer of 1 to 6 inclusive, y is an integer of 0 to 6 inclu-sive, R1 is lower alkyl and R2 is hydrogen or lower alkyl, (e) a mixture of an acrylic ester monomer se-lected from the group consisting of di-, tri-, and tetra-esters of an acrylic acid and a polyhdric alcohol, acrylic esters of cyclic ether alcohols, acrylic esters of amino alcohols and mixtures there-of, a peroxidic initiator of an amount sufficient to initiate polymerization of said monomer and a member selected from the group consisting of rhodanine and a hydrazide of the formula wherein R and R1 are selected from separate, groups and an interconnected group forming a cyclic ring, R is further selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl and alkoxy and R1 is selected from the group consisting of hydrogen and alkyl, cycloalkyl, and acyl in an amount sufficient to accelerate the polyerization of said monomer; and (f) a mixture of a monomer of the formula wherein R1 and R2 are selected from the group consisting of hydrogen and lower alkyl and R3 is selected from the group consisting of lower alkyl, lower hydroxyalkyl, cyano and lower cyanoalkyl; at least one equivalent of an acid for each equivalent of said monomer, said acid being selected from the group consisting of acrylic acid and lower alkyl acrylic acids; an initiator selected from the group consisting of t-butyl per-benzoate, t-butyl peracetate and di-t-butyl diperphtha-late, said initiator being present in an amount suf-ficient to initiate the polymerization of said monomer;
a trihydroxy benzene inhibitor and an accelerator sel-ected from the group consisting of benzhydrazide and N-aminorhohanine.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US452359A US3929396A (en) | 1972-04-04 | 1974-03-18 | Molded plastic bearing assembly |
| CA212,954A CA1026812A (en) | 1974-03-18 | 1974-11-04 | Molded plastic bearing assembly |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1044293A true CA1044293A (en) | 1978-12-12 |
Family
ID=25667737
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA289,231A Expired CA1044293A (en) | 1974-03-18 | 1977-10-21 | Molded plastic bearing assembly |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1044293A (en) |
-
1977
- 1977-10-21 CA CA289,231A patent/CA1044293A/en not_active Expired
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