CA1051105A - Article and method for covering substrates and composite structures so made - Google Patents
Article and method for covering substrates and composite structures so madeInfo
- Publication number
- CA1051105A CA1051105A CA237,213A CA237213A CA1051105A CA 1051105 A CA1051105 A CA 1051105A CA 237213 A CA237213 A CA 237213A CA 1051105 A CA1051105 A CA 1051105A
- Authority
- CA
- Canada
- Prior art keywords
- article
- substrate
- recoverable
- outwardly extending
- sheds
- 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
Links
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
- B29C65/66—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by liberation of internal stresses, e.g. shrinking of one of the parts to be joined
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C63/00—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor
- B29C63/38—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor by liberation of internal stresses
- B29C63/42—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor by liberation of internal stresses using tubular layers or sheathings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/01—General aspects dealing with the joint area or with the area to be joined
- B29C66/05—Particular design of joint configurations
- B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
- B29C66/11—Joint cross-sections comprising a single joint-segment, i.e. one of the parts to be joined comprising a single joint-segment in the joint cross-section
- B29C66/112—Single lapped joints
- B29C66/1122—Single lap to lap joints, i.e. overlap joints
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/01—General aspects dealing with the joint area or with the area to be joined
- B29C66/05—Particular design of joint configurations
- B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
- B29C66/12—Joint cross-sections combining only two joint-segments; Tongue and groove joints; Tenon and mortise joints; Stepped joint cross-sections
- B29C66/122—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section
- B29C66/1222—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section comprising at least a lapped joint-segment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/01—General aspects dealing with the joint area or with the area to be joined
- B29C66/05—Particular design of joint configurations
- B29C66/10—Particular design of joint configurations particular design of the joint cross-sections
- B29C66/12—Joint cross-sections combining only two joint-segments; Tongue and groove joints; Tenon and mortise joints; Stepped joint cross-sections
- B29C66/122—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section
- B29C66/1226—Joint cross-sections combining only two joint-segments, i.e. one of the parts to be joined comprising only two joint-segments in the joint cross-section comprising at least one bevelled joint-segment
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
- B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
- B29C66/53—Joining single elements to tubular articles, hollow articles or bars
- B29C66/532—Joining single elements to the wall of tubular articles, hollow articles or bars
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C66/00—General aspects of processes or apparatus for joining preformed parts
- B29C66/50—General aspects of joining tubular articles; General aspects of joining long products, i.e. bars or profiled elements; General aspects of joining single elements to tubular articles, hollow articles or bars; General aspects of joining several hollow-preforms to form hollow or tubular articles
- B29C66/51—Joining tubular articles, profiled elements or bars; Joining single elements to tubular articles, hollow articles or bars; Joining several hollow-preforms to form hollow or tubular articles
- B29C66/53—Joining single elements to tubular articles, hollow articles or bars
- B29C66/534—Joining single elements to open ends of tubular or hollow articles or to the ends of bars
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B17/00—Insulators or insulating bodies characterised by their form
- H01B17/32—Single insulators consisting of two or more dissimilar insulating bodies
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
- H02G15/00—Cable fittings
- H02G15/02—Cable terminations
- H02G15/06—Cable terminating boxes, frames or other structures
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/34—Electrical apparatus, e.g. sparking plugs or parts thereof
- B29L2031/3412—Insulators
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Insulating Bodies (AREA)
- Lining Or Joining Of Plastics Or The Like (AREA)
Abstract
ABSTRACT
Disclosed is a covering for a substrate which may be a shedded electrical insulator. The covering is formed, e.g. by moulding, of heat recoverable material and has internal transverse dimensions (diameter, if round) slightly smaller than the transverse dimensions of the substrate. The covering is converted to a heat-recoverable form by heating, expanding on a mandrel and cooling, followed by removal of the mandrel. The covering is then placed over the substrate and heated to shrink it tightly around the substrate, there being a small amount of unresolved recovery.
Disclosed is a covering for a substrate which may be a shedded electrical insulator. The covering is formed, e.g. by moulding, of heat recoverable material and has internal transverse dimensions (diameter, if round) slightly smaller than the transverse dimensions of the substrate. The covering is converted to a heat-recoverable form by heating, expanding on a mandrel and cooling, followed by removal of the mandrel. The covering is then placed over the substrate and heated to shrink it tightly around the substrate, there being a small amount of unresolved recovery.
Description
s~o~
This invention rela-tes to an artlcle and method : ~or co~ering substrate~ and more particularly relates to an article and method suitable for making an insulator for use in the high voltage field. The invention also relate~ -to composite structures made using the article and/or method.
In the high voltage ~ield insulator~ (or insulating units) may be used, ~or example, to support overhead pow~r ;~ lines, the insulators being either under compres~ion or under tension, or, in the case of~ for example9 post i~sulatoræ
in sub-stations and bushing~ on trans~ormer~ and ~witch~ear, to provide a satisfactory leakage dista~ce betwee~ those parts of the equipment that are at a high pot~n~ial and ; those parts whi¢h are groundea. The outer sur~aoe of an insulatQr u~ed as indicated above i~ generall~ provided - 15 with a ~wmber of sheds to increase the creepage distan¢e . and flash-over voltage and to reduce leakage currentsO
The sheds also provide a number o-~ protected areas which help to improve the overall per-~ormance of the insulator.
Aæ i$ well known to those skilled in ~he art, a ~hed is a member which exte~ds outw~rdly from the ~x~ace of the .' in~ulator and around the circum~erence thereo~ to provide the ln~ulator with a circumferential rib~ ~kirt or ~in~
In the past, insulators of the above type h~e generally been ~abricated ~rom an in~ulating material such as porcelai~ or~ in the case o~ ~uspension in~ulators, glas~.
. The 3mal1er units, ~or examplo 3~ EV po~t in~ulator~ and : 11 and 33 E~ bu~hings ~or tran~formers a~d switchgear, are : ~abricated as single unit~, the bushing~ being hollow to allow them to receive the metal compone~t at high pote~tial.
~0 ~s the SiZ8 a~d comple~lty o~ shape increa~e~ the ma~acture
This invention rela-tes to an artlcle and method : ~or co~ering substrate~ and more particularly relates to an article and method suitable for making an insulator for use in the high voltage field. The invention also relate~ -to composite structures made using the article and/or method.
In the high voltage ~ield insulator~ (or insulating units) may be used, ~or example, to support overhead pow~r ;~ lines, the insulators being either under compres~ion or under tension, or, in the case of~ for example9 post i~sulatoræ
in sub-stations and bushing~ on trans~ormer~ and ~witch~ear, to provide a satisfactory leakage dista~ce betwee~ those parts of the equipment that are at a high pot~n~ial and ; those parts whi¢h are groundea. The outer sur~aoe of an insulatQr u~ed as indicated above i~ generall~ provided - 15 with a ~wmber of sheds to increase the creepage distan¢e . and flash-over voltage and to reduce leakage currentsO
The sheds also provide a number o-~ protected areas which help to improve the overall per-~ormance of the insulator.
Aæ i$ well known to those skilled in ~he art, a ~hed is a member which exte~ds outw~rdly from the ~x~ace of the .' in~ulator and around the circum~erence thereo~ to provide the ln~ulator with a circumferential rib~ ~kirt or ~in~
In the past, insulators of the above type h~e generally been ~abricated ~rom an in~ulating material such as porcelai~ or~ in the case o~ ~uspension in~ulators, glas~.
. The 3mal1er units, ~or examplo 3~ EV po~t in~ulator~ and : 11 and 33 E~ bu~hings ~or tran~formers a~d switchgear, are : ~abricated as single unit~, the bushing~ being hollow to allow them to receive the metal compone~t at high pote~tial.
~0 ~s the SiZ8 a~d comple~lty o~ shape increa~e~ the ma~acture
- 2 - ~ .
. ~ . -, SliOS
o.~ o~e-piece insulator~ become~ more di~icult and inæulators are normally manufactured in a number of separate unit~
which, in the case of bushing~ and po~t insulators, are . generally cemented together to -~orm the complete ~tructure .~, 5 and, in the case o~ suspen~ion insulator~, are ge~erally connected by metal fi~ting~ which are cemented to the glass or ceramic. ~lthough ineulators made ae i~di~ated above are advantageous in that relatively inexpen~ive st~rting materials are used ~ they have the disadvantage that bhey are e~pensive to manufacture9 heavy, and relativel~ ~ragile.
Recently, propo~als have been made to make insulators rom pla~tics materials. The most commonly usea materials have been ~po~y re~ , and the in~ulator~, or in~ulator components, have been made by a ca~tin~ or mouldi~g proces~.
~hu~, ~or e~ample, British Patent Speci~ioation No. 1,~45,566 in the name o~ General ~lectric Co., published ~Oth January, 1974, de~cribes a method in which a central rod and the ,. . . .
desired number of sheds are i~tegrally moulded from a pla~tic~ -material. Such an i~tegral moulding method~ howe~erl has the disadvantage that a di~erent mould is required ~or each ;~ compo~nt~ and it would be an advantage if the sheds could be made ~eparately from the central rod so that the sheds could be applied to any desired insulator. ~oreover, i~ the sheds are made separatel~ ~rom bhe body o~ the in~ulator it is po~ible to make the shed~ and, if desired, the outer : sur~ace of the insulator, ~rom a di~fere~t .material ~rom .
that used for the body of the insulator~ ~hus, ~or e~ample, ::
a material which, although other~ise sultable ~for example, because of it~ cheapness a~d/or light~ess) for use as an insulator, has rel~tivel~ poor electrical properties~
.
.
` ~ ~ 5 1 ~ ~ 5 may be u~ed to form the body o~ the in~ulator i~ it i~
provided with n ou~er ~ur~a~e and ~hed~ o~ a non-tracking in~ulating material.
A proposal has been made to m~ke an in~ulator by ; 5 cementing a number of individual ~hed~ to a glass ~ibre core. Thus, for example, Briti~h Speci~ication ~o.
1,292,276 i~ the name o~ Raychem ~imited9 published 11th October9 1972, describes the in~tallation o~ a n~nber o~
indlvidual heat-~hri~kable shed~ on a central ~upport.
: 10 Even ~hen heat-~hrinkable sheds are u~ed~ however, the .~ manufacture and i~stallation o~ a number o~ ~epara-te ~hed~
inevitably time-consuming, and may lea~ to undesired ~. variation~ in ~uality in the fin~l product, and it would be .. advantageou~ i~ the ~hed~ could form part o~ an outer covering ~` 15 which could be applied to the central ~upport as a single :, unit. My previou~ e~perimental attempts to provide an '~; in~ulator with an outer ~overi~g by moulding a tubular member having a nwmber of shed~ converting the member to a heat-~hr~nkable ~orm, and then shrinking it round the insulator -~
did ~ot, however~ pro~e success~ul as air became trapped . ~ between the member a~d the insulator and the shed~ became distorted such that they were no lo~er perpendicular to the .` surfaoe o~ the ~use. Such distortion occurred at random, some ~hed~ ~orming an aoute angle with the longitudinal :- 25 a~is of the member and some an obtuse angle, with the result that not only was the final appearance unsatis~actory, bu~
in some oases the outer extremities o~ the sheds ~ere so close together that arcin~ could occur betwee~ adjacent sheds. ~urthermore, upwardly ~nclined sheds would tend to colleot water lf ths 1~sulator were used out o~ door~, .
with the re~ult that the ele~tric~l prope~tie~ of the assembly would be impairea.
It is there~ore an object of -the prese~t invention to provide an outer covering ~or a substrate which can be quic~ly and ~imply applied and which~ after in~tallation, will have a d~sired con~iguration.
It is another object of the pre~ent in~ention to provide a recoverable article which be~ore de*ormation ;~ to~ the recoverable state haæ a particular d~sired configuration and which, a~ter being reoovered round a sub~trate, wlll return to, or maintai~, the said con~iguration.
It is another ob;ect of the pre~ent inve~tion ::
. . to provide a ~hedded electrically in~ulating covering : which can be applied to an electrically in~ulating member to provide that member with an electrically insulatin~
~ur~ace o~ a desired con~iguration.
~ It i~ ~nother ob~ect o~ the preBen~ in~ention : to provide a reco~erable i~sulati~g covering which includes a plurality of substantially perpendicular ~hed~ and ¢an be recovered round an electrical component ~uch a~ a :
tran~former bu~hing~ in~ulator po~t, or fuee with sub~ta~
tially no de~ormatio~ of the shedsO :.
:- It i~ a~other ob;ect of the pre~e~t in~e~tion to provide a composite ~tructure, for e~ample an eleotri¢al in~ulator7 the 3ur~ace of ~hich has a particulax desired configuratio~, and a method ~or making such a compoæi-te ~tru¢ture.
The present inYentio~ provide~ a recoverable : hollo~ article for use i~ ¢overing a substrate, whi¢h . ~ 30 arti¢le ha~ at lea~t one open end and e~-}es~ s~ :
- 5 ~
. .
-i ~a~Sl~L~5 two or more outwardly e~tending portions whioh extend around at least par~ o~ the perlphery o~ the article~ at least the portion o~ the artiole radially inwards of the radiall~ inner-i most portio~ o~ at least two out~ardly extending po~tion~ being re¢overable, the inner dimensions of the article re~ulting ,; from substrats-~ree recovery bei~ slightly smaller than the outer dimensions o~ the sub3trate, so thab, on reco~er~ o~ the article arou~d the substrate, the angle between each said at .q least two outwardly e~tending portions ~ld the longitudinal a~i~
o~ the article i~ sub~tantially that obtained on substrate-~ree recove~y.
~ he in~rentio~ al~o provides a composite structlLre which ¢omprlses a ~ubstrate having a~plied to the outer ~r~a¢e thero~ a hollo~ recoYerable article ha~ing at least one open end and t~o or more outwardly e~tendi~g portions which extend around at least part o~ the periphery o~ the article, at . least the portion o~ the article radially inwards o~ the radially i~nermo~t portio~ o~ at least two outwardly e~tending .`. portions being recoverable, the article e~hibiti~g o~ly a :-.
small degree of u~resolYed recovery. ~he unresol~ed recoveTy is such that, i~ the sub~trate wer0 removed and the article were ~ully recovered, there would be sub~tantially no ch~nge in the angle bet~een each ~aid at least t~o outwardly e~tending portions and the longitudinal a~i3 of the article. The maximum . ~ 25 degree o~ recovery that i3 within the ambit of "smalll' will of course vary from article to article, but the llmitin~ values will be readil~ determined by si~ple routi~e e~perime~t.
he in~ention ~urther provides a method/co~ering . ~, . .
a substrate comprising: positioning around the sabstrate a reo~verable hollow artiole having at leaet ore open end and :. 6 -, ; .
s ; ~ ~ " . . . ~ - .
~ 5~1~5 two or more outwardly e~tending portio~s which extend around at lea~t par~ o~ the periphery o~ the articl~, at least the portion of the artiele radially in~Jards o~ the radially in~er-most portion o~ at lea~t two outwardly e~tending portions being recoYerable, the inner dimensio~ that the article wo~ld ha~e i~ recovered in the ab~ence of a ~ubstrate being slightl~
.; smaller than the outer dimen~ions Qf the substrate so that~ on `: recovery o~ the article arouad the 3ubstrate, the angle betwaen each ~aid at least two outwardly e~tendi~lg portion3 and i 10 the lo~gitudi~al ~xi~ o~ the article is substantiall~ the æame I as the angle that would be obtained i~ the arti¢le were re- :
.~ covered in the absence o~ a ~ub~t~ate; and oausing the ar~icle ~i to recover around the sub~trate.
~he i~ve~tion al~o provides a method o~ making a ~5 hollow article, which compri~es ~orming a hollow article having at lea~t one open end and having two or more outwardl~ :~
e~tending portion~ each of which exta~ds round at least part : -o~ the periphery o~ the article, and increa~ing the inner -:
dimen~io~ o~ the article to conver,t it to a reco~erable ~tate in which at least the portion of the article radi~lly inward~
o~ th~ rad~ally innermo~t portion of at leaæt two outwardly e~tending portion~ i9 recoverable and in whioh each said at least t~o outwardly extending portion~ is such that, on re- :
cove~y o~ the arti¢le around a substrate, the angle between eac~ said at least two outwardly e2tendlng portions and the longitudinal axi~ of the article is subætantially that : obtained on a substrate-~ree recoveryO
The invention ~urther pro~ide~ a recoverable article ;-which comprises an elo~gate hollo~ member ha~ing at lea~t vne ~0 ope~ end and two ~r more shed~ which ~te~d outwardl~ ~rom the hollow member a~d are s~bstantially perpendicular (as `' .
~ 7 "' ' ' ''' " .. ,'' ' '. ' ~'' . " ' ' ' ' , ' .
-~I~S~ 5 hereinafter defined) to tha longitudinal axis o-f the hollow member~ at least the portion of the hollow member radially .inwards of the radially inner~ost portion of at least two said sheds being recoverable, the article being such that~ on recovery ; 5 o~ the article into contact with a substantially cylindrical sub-strate, the said sheds are substantially perpendioular (as hereinafter de~ined~ to the longi-tudinal aXiB of the hollow member and being such that9 on sub~trate-~ree reco~ery, the said sheds are substantially perpendicular (a~ hereinafter defined)to the longitudinal a~is of the hollow member.
~ he invention also provides a m~thod of makin~ a recoverable article which comprises ~orming an article com-prising an elongate hollow member having at least one open end and two or more sheds e~tending outwardly ~rom the hollow ; 15 member and substantially perpendicular (as hereinafter defined) to the longitudinal a~is of the hollow member, and increasing the inner dimensions o~ the a~ticle to con~ert it to a recoverable state in which the said sheds are ~ubstantiall~
perpendicular ~as hereina~ter defined) to the longitudinal axis of the hollow member9 in ~hich at least the por~ion o~
the hollow member radia~ly inwards o~ the radially innermost portion of at least two said shed~ is recoverable, and in whioh the article is such that, on recovery of the article into contact with a substantiall~ cylindrical substrate, the said sheds are substantially perpendicular (as hereina~ter defined) to the longitudinal axi~ o~ the hollow member.
~he inven~ion ~ur~her provides a composite structure ; which comprises a substrate having applied to the outer sur~ace thereo~ a recoverable article comprising an elongate hollow ~0 mem~er ha~ing at least one open end and two or more sheds which - 7a -e~-tand ou-twardly irom the hol~ow member and are ~ubstantially perpendicular (a~ hereina~ter de*ined) to the longitudinal axis o~ the composite structure~ at least the portion of the hollow member radially inwards of the radially innermost portion o~ at least ~o said sheds being reco~erable, a~d the article i s~hibiting only a small degree of unresolved recovery such ,~ that~ i~ the substrate were removed and the article were ~ully .; recovered, the said sheds would be substantially perpendicular ~as hereina~ter defined) to the longitudinal aæis o~ the hollo~
member.
~he invention also provides a method of ma~in~ a compo~ite structure comprising positioning round a substrate :~
: a recoverable article compri~in~ an elongate hollow member having at least one open end and two or more sheds which e~tend outwardly from the hollow member and are substantially perpendicular (a~ hereina~ter defined) to the longitudinal axis of the hollow member, at least the portion of the hollow ~ member radially inwards o~ the radially innermost portion o~
- at least two said she~s bei~g recoverable, the ~aid sheds after substrate *ree recovery o~ the article being substantially perpendicular (a~ hereina~ter defined~ to the longitudinal axis of the hollow member and the inn~r dimen~ions that the article would have a~ter sub~trate-~ree recovery being slightly smaller than the outer dimensions o~ the substrate 30 25 that, on recovery o~ the article into contact with the sub- :
strate, the said sheds are substantially perpendicular (as hereina~ter de~ined) to the longi~udinal axis o~ the article, and causing the article to recover into contact with the substrate O
~s indicated above, the arti¢le of the in~ention ~ - 7b _ ~ .
'', . . . .......... . .
~, . . .. . - .
~ ~5 ~
; includes a hollow member and at le~* t~o outwardly ex-tending portions each of which outwardly extending poxtions extends around at least part of the peripher~ of the article. If the outwardly eætending portions are sheds of electrically insulating material, these sheds are advantageously continuou~, extending round the entire periphery of the hollow member.
Where th~ outwardly extending portions extend round o~ly part o~ the periphery of the article, the article may~ i* desired~
be ~ade in a wrap-around ~:~rm, a longitudinal seam being made in the article a~ter, ~or e~ample, moulding. ~he out~7ardly e~tending portions are pre~erably integral with (that is, *ormed in one piece with) the remainder of the article~
~he article o~ the invention i8 advantageously and made by moulding/each o~ the outwardly e~tending por~ion~ i~, in the "as moulded" form of the article (and thus al~o in the fully recovered ~orm), preferably substantially perpendicular to the longitudinal axis of the hollo~ rnember.
- 7e --o~
It is to be understood that the term "~ub~tantially per-pendicular" covers all con~igurations ~uch that a mould spl~t only longitudinally could be removed ~rom the article with substantially no deformation o~ the outwardl~ exterldi~g portions.
In the article o~ the invention, the i~ner dime~ion~ of the reoo~erable hollow member when reoovered in the absence of a sub~trate are onl~ ~lightly s~aller ;~
than -the outer dimensionæ o~ the ~ubstrate. ~ome ~ ht difference in dimen~iorls i~ nece~ary as if the~e two dimensions were identical the article would ~ot e~ert any recovery force on the ~ubstrate9 and could thus relatively eaæil~ be remo~ed ~rom the ~ubstrate. ~y ensurin~ that the difference i~ small, however, it is po~sible -to enæure that the article when fitted exhibit~ minimal unre~olved recovery (that is it ha~ almost returned to the original ; dimen~ions in which it was moulded), ~o that there i~ little or no tendency ~or the outwardly e~tending portions to be de~ormed by inte~nal stresse~ I~ the article. Moreover, .
if the article i~ heat-recovsrable and i~ made of a material o~ which the thermal expansion i~ high compared with th~t o~ the substrate, forces between the article ana the substrate a~ter reoovary of the article into contaot with the æubstrate will ~e virbually zero at the recovery temperature; in other words, at that temperature, although not at room ~emperature~ the article ~ill have virtually the same dimensions a~ the original article would have had at the -same temperature, so there are substantlally no stre~seæ
arising ~rom the de~ormation to the heat;recoverable ætate, and thus substa~tially no tendency ~or the outwardly . , .
` 105:~L05 : e~tending por-tion~ to be deformed duri~g installation.
Although the preferred difference in the outer dimensions of the substrate and the inner dImen~ion~ of : the fully recovered article will depend on the cir¢umstance~, - 5 the inner li~ear dimensisns o~ the fully recovered article are preferably not more than 13 ~0 smaller9 calculated on the : inner dimension~, than the outer l.inear dimensio~ o~ the ~ubstrate. If the di~erence in dimens.ions is too small, ho~ever, there w~ll be a dan~er that a heat-recoverable artiole made of a ~aterial of which the thermal expansion is high compared with that of the ~ub~trate will not contact the sub~trate at the recovery temperature9 thus enabling air to be trapped between the article and the ~ub~trate. ~or ~uch ~ ;
a heat-recoverable article, the di~ference in the linear dimensio~s is pre~erably not les~ than 2 ~0.
The in~er ~urface of the article o~ the inve~tion i~ advantageou~ly shaped to fa~ilitate escape of air from between the article and the ~ub~trate d~rlng recovery.
Thus, ~or example~ the inner 3ur~aoe may haYe one or . ., , :
_ g _ .
~s~
more longitudinally extending grooves therein. Alternatively, the cross-section of the inner surface of the article in its recoverable state may be different from the cross-section of the substrate, giving channels along which air can escape during recovery. Thus for example, the article may have a polygonal inner surface ~which may, for example, be produced by the use of a mandrel having a polygonal outer surface to expand the article)~ while the substrate has a generally cylindrical outer surface.
The hollow article used in accordance with the invention exists, from the time of its manufacture to the time when it has finally been installed on the substrate, in at least three different states. These are the substan-tially dimensionally stable state in which it is formed, a first recoverable state, wherein its inner dimensions are large enough for it to be slipped over the substrate, and a second recoverable state wherein it has been recovered around the substrate to form a composite article but is prevented by the sub-strate from recovering completely to its orginal dimensionally stable state.
In the second recoverable state it is said to be partially recovered or to exhibit "unresolved recovery" and, according to the present invention, the un-resolved recovery is kept to a minimum. The article is advantageously such that recovery is effected by heating, but if desired may be such that recovery may be effected by means of a solvent or by removal of a rigid member which holds the article in the recoverable state.
The degree of expansion of the article from the substantially dimen-sionally heat-stable state to the first heat-recoverable state, resulting in an increase in the internal dimensions of the article can be smallJ for example up to about 13 per centJ or large. Advantageously when the degree is small, and preferably also when it is large, the or eaGh outwardly extending ~ portion, for example the or each shed, is prevented from moving appreciably ; from the perpendicular during the expansion process. This can readily be done by mechanical means, for example by clamping the sheds or, in the case in which there is a plurality of outwardly extending portions, by using comb-like ' . : - . . : . : ~ . , ~: , .
~ ~05~: LQ5 .
means havin,~ a number OI ~3uitably ~paced teeth or plate~ whi¢h oan be brought into abutti~g relation~hip with the outwardlg exte~ding portion~
Although the invention i~ in no way limited to parti¢ular type~ o~ artiole a~d substrate, the i~entl~n i8 . e~pecially useful for providing an electric cable or an .: electrical component ~or e~ample a ~use, tran~ormer bu~h; or i~ulator post, with a o~e-piece outer covering t~t inolude~ ~.
.i~ a pluralit~ o~ ~heds. ~s indicated a~ove9 ~or ease o* con-~ 10 ~truotion the~e ~hed~ ars advantageou~ly perpendicular to the . ~ .
longitudinal a2i~ of the in~ulatQr, ~nd perpe~dicular shed~
also have the advantage that they pre0ent a bidier appearanoe ; than i~clined sheds ~hen a ~umber of insulators are arranged . ~ .
at di~ferent angles to one another. Moreover, if the article -~
o~ the inve~tion i~ used to cover an in~ulator which i0 to be u~d in a vertical position, the artiole can be used either way up; i~ inclined sheds were used they would have to be downwardly inolined to avoid oollecting rain water.
~he article of the inventiQn may comprise ang . 20 material that can be converted to the recovera~le ~tQte, by ,.; , oro~slinking it, if nece~ary, and e~panding it, the nature o~ the material being dictat~d by the u~e to which the compo~ite ~tructure i~ to be put. '~hu~, ~or e~ample, when the article i~ to be u~ed a~ an outer covering ~or a high ; 25 voltage insul~tor, it preferably compri~es a ~o~-tracki~g electrio~lly i~ula~i~g materi~l. A non-tra~klng materlal may be de~ined as one whi~h ha~ an i~itial traoki~g voltage : o~ more than 3 KV when tested 1~ accordanee with A~'~M-D230~-64'~
~wettin~ agent 'Triton X-100), a test method which u~es the ~0 inolined plar3e llquid corltam1nation test and is de~igned to . ., .
~5~
represe~t eervice e~po~ure o~ in~ulator~ under polluti~g cnnditions. Examples of non-tracki~g ~aterial~ which may be converted -to a heat~rec~verable state are given in Briti~h Patent Specification~ Nos. 1,292,276 and 1,284,081 both i~ the ~ame o~ Raychem ~imited~ published 11th October, 1972 and 2nd August, 1972 respectively, and in DO~ 2,237,459 ~nd DOS 2,237~354 both publiæhed 7th ~'ebruary, 19'74, and DOS 2,050,581 publi~hed 29th ~pril, 1971, all in ~;he name o~
Raychem Corporation. ~he article o~ the invention may b~
moulded by, ~or e~ample, ~ompre~ion, tran~fer or in~ection mouldl~g, and7 when a~y ~uper~luous material ha~ been removed, may be e~pa~ded by any de~ired method~ eîther automatlc or manual.
I~ de~ired, an adhe~ive may be used to bond the 17 article oi the in~ention to the substrate, and/or at lea~t part of the ~urface o~ th~ arti¢le ~hich ie to contact the ~ubstrate may be pro~i~ed with a stre~s-grading material or layer, that i~ a material or layer whioh can act to reduce the electrical ~tress whlch may exi~t in variou~ area8 o~ a high voltage component, ~or example at the e~d o~ the ~¢reen o~ a high voltage cable. ~ ~uitable adhesi~eæ there may be me~tioned, ~or example, epoxy re~ (either hot or cold cured) and polyester~, which resin~ and polye~ter~ may be u~ed with or without ~ er~, and ~ilico~e-containing adhe~ivee, , -e~.peci~lly tho0e ~ith ~on-traoking propertie~. Other suitable adhe~lve ~ompo~ition~ include thoee compri~ing a ¢opolymer o~ a hydrocarbon co~taining a~ leaet one polymerizable double bond and a compou~d contæi~ing a polymerizable double bo~d to~ether with one or more carbo~lic a¢id group~, which ~0 carbox~lic acid group~ ma~ be in the ~or~ o~ a derivative~
. .
-- 12 - :
. . ~ : . .............................. .
. : .
~Sl~S
~or example an a~ter or a~ anhydrideO ~ examplea o~ such copolymer~ there may be mentioned ethylene/vinyl aceta~e .
copolymere, ethylene/eth~l acrylate copolymers9 methyl vi~yl ether/maleic anhydride copolymer~ and, pre~erably, ~lk~l e~ters o~ methyl vinyl ether/maleic a~hgdride copol~meræ.
A ~tre~s-grading ~aterial or la~er is ~ui~ably a ~terial or layer with lin~ar, or pre~erably non~ ear9 electrlcal re~i~tance properti~s and may hav~ .~orm ~tability or comprlæe a substan~ially non oryetalli~e material (~or exa~ple a ma~tic-like material) whlch haæ a visco~ity o~ le~ than 1013 cp at 25a. ~xamples Q~ ~uitable ~tre~s-grading materials are ~iven i~ DOS 20344,067 publ~hed 11th April, 1974 and DOS 2~413,475 publi~hed 2nd January7 1975, bo~h in the name o~ Raychem ~imitedO ~he a~pect~ of stre~s-gradi~g -a~
anti-tracking ma~ be combined i~/~article or compo~ite structure of the in~e~tion a~ de~oribed in Canadlan Pate~ Application ~o. 237,197 i~ the name of R. J. T. Clabburn a~d ~. J. Penneck, filed 7th O¢tober, 1975.
~he i~ve~ion will now be desoribed in more detail, by w~y o~ e~ample onl~, with reference to the accompanyin~
dra~ingæ in whi¢h: :
Figure 1 i~ a lo~gitudinal section through a covering for an in~ulator, the covering being in a heat-stable co~dition;
Figure 2 shows the covering of Pi~ure 1 in ~n ; expa~ded, heat-reco~era~le conditlon;
and ~igure 3 shows the covering o~ ~igure 2 recovered around a fuse.
_ 13 _ Re~er~i~g now -to the dr~wing~, ~igure 1 i~ a longitudinal ~ection through an articl~ ~e~erally indicated . at 10 which include~ a longitudinally egte~di~g central ; portion 11 and a number of shed~ 12 which ar0 ~ub~tantially perpendicular to the ce~tral portion 11 ~o that the article can readily be moulded. In ~igurc ~, the article i~ i~ a ':~ d.umensionally heat-3table ~orm. A heat-recoverable form 10' o~ the arti¢le 10 is 3how~ in Figure 2, ~nd, :in thi~
f~rm, the article may be poæitioned around an in~ulator with ~n outer diameter bet~aen the in~er diameter~ o~ the ~orm~ 10 and 10' (~or e~ample a ~ibre-gla~s rod 13 with metallic end cap~ 14 - ~ee ~igure ~) and may be heated to cau~e lt to ~hr~k clo~el~ into co~tact ~ith the rod, as ~ ~hown in ~igure 3, .~ 15 ~ can be ~een from the Flgure~ the sheds 12 are sub~tantia~ly perpendi~ r to the ce~tral portion 11 in all thrae ~igureæ. ~ccording to the in~ention, the inner d~ame-ter of the central portion 11 and the outer diameter of the rod 1~ are chose~ so that thi~ ~ub~ta~tially p~rpendioular arrangeme~t ls obtained in the composite article (Fi~ure 3).
not e~se~tial, however, that the perpendicul~r arrange-ment be mai~tained in the heat-recoverable ~tate indioated in ~igure 2; some de~ormatio~ o~ the ~heds may occur in this ~tate provided that dimensions are ~uoh that the desired ~5 perpendioular ~tate i~ obtained ~i~ the oompo~ite arti~le)~
The arti~le5an~ composite ~tructures of the in~entio~ are illu~trated in the following E~mples:
B x a m ~_l e ~ 1 to ~
~hree sleeve~ provided with a plurality of ~heds _ 14 :
.. ' .
:- .
~s~
~ere mould~d from electricall~ in~ulating material~ In each case the sheds, which were es~entially eimilar to those shown in ~igure 1, were ~ubstantially perpendicular to the - longltudinal axi~ o-~ the ~lee~e and were ~ymmetrioal about a plane perpendicular to ~aid longitudinal axis~ ~ach ~leeve wa~ co~verted to a heat~recoverable form by heati~, ~ e~panding on a mandrelt and cooling9 ~ollowed by removal o~
.; the mandrel. ~ach of the heat-recove~able ~rti~le~ wa~ ;
~ the~ po~itioned round an appropriate cyllndrical ~use ar~d - 10 heated ~o shrink it into clo3e oontact with the ~u~e~ In a separate experlment, heat-reco~erable articles ide~tical to those shrunk round the ~u~eæ were heated in the ab~enoe o~ any sub3trate to determ~ne the ~ully re¢overed diameter of the articles.
:.... 15 The inner diameter oi the heat-recoverable article~
and the outer diameter of the ~uses~ as well a~ the internal diameter of the ~ully recovered ~leeves are given in the Table below. ~he T~bls al~o give~ the perce~tage unreeolved recovery of the sleeves when recovered round the fu~es, this : ~0 bei~g calculated accGrding to the followi~g equation:
% unr2solved recovery = outer diameter of fu~e - :
inner diameter of fullg recovered ~leeve ~ 1 00 inner diameter o~ fulIy recovered ~leeve ~LC)5~
:;
.
T ~ B ~_E
, , .
I~ner Outer I ! . .- ~ ~, ~umber diameter diameter diameter unre~olved Example of o~ heat- o~ ~u~e o~ ~ully recovery sheds recoverable (inches) recovered ~ .
; article sleeve .
(inches) (i~ohe~3 _________ _______ ____________. ,~ _ ________, ___________ :. 1 5 2.53 2.47 2.27 8.81 2 ~ 2.78 2.72 2.50 8.79 `.:
. ~ . -, SliOS
o.~ o~e-piece insulator~ become~ more di~icult and inæulators are normally manufactured in a number of separate unit~
which, in the case of bushing~ and po~t insulators, are . generally cemented together to -~orm the complete ~tructure .~, 5 and, in the case o~ suspen~ion insulator~, are ge~erally connected by metal fi~ting~ which are cemented to the glass or ceramic. ~lthough ineulators made ae i~di~ated above are advantageous in that relatively inexpen~ive st~rting materials are used ~ they have the disadvantage that bhey are e~pensive to manufacture9 heavy, and relativel~ ~ragile.
Recently, propo~als have been made to make insulators rom pla~tics materials. The most commonly usea materials have been ~po~y re~ , and the in~ulator~, or in~ulator components, have been made by a ca~tin~ or mouldi~g proces~.
~hu~, ~or e~ample, British Patent Speci~ioation No. 1,~45,566 in the name o~ General ~lectric Co., published ~Oth January, 1974, de~cribes a method in which a central rod and the ,. . . .
desired number of sheds are i~tegrally moulded from a pla~tic~ -material. Such an i~tegral moulding method~ howe~erl has the disadvantage that a di~erent mould is required ~or each ;~ compo~nt~ and it would be an advantage if the sheds could be made ~eparately from the central rod so that the sheds could be applied to any desired insulator. ~oreover, i~ the sheds are made separatel~ ~rom bhe body o~ the in~ulator it is po~ible to make the shed~ and, if desired, the outer : sur~ace of the insulator, ~rom a di~fere~t .material ~rom .
that used for the body of the insulator~ ~hus, ~or e~ample, ::
a material which, although other~ise sultable ~for example, because of it~ cheapness a~d/or light~ess) for use as an insulator, has rel~tivel~ poor electrical properties~
.
.
` ~ ~ 5 1 ~ ~ 5 may be u~ed to form the body o~ the in~ulator i~ it i~
provided with n ou~er ~ur~a~e and ~hed~ o~ a non-tracking in~ulating material.
A proposal has been made to m~ke an in~ulator by ; 5 cementing a number of individual ~hed~ to a glass ~ibre core. Thus, for example, Briti~h Speci~ication ~o.
1,292,276 i~ the name o~ Raychem ~imited9 published 11th October9 1972, describes the in~tallation o~ a n~nber o~
indlvidual heat-~hri~kable shed~ on a central ~upport.
: 10 Even ~hen heat-~hrinkable sheds are u~ed~ however, the .~ manufacture and i~stallation o~ a number o~ ~epara-te ~hed~
inevitably time-consuming, and may lea~ to undesired ~. variation~ in ~uality in the fin~l product, and it would be .. advantageou~ i~ the ~hed~ could form part o~ an outer covering ~` 15 which could be applied to the central ~upport as a single :, unit. My previou~ e~perimental attempts to provide an '~; in~ulator with an outer ~overi~g by moulding a tubular member having a nwmber of shed~ converting the member to a heat-~hr~nkable ~orm, and then shrinking it round the insulator -~
did ~ot, however~ pro~e success~ul as air became trapped . ~ between the member a~d the insulator and the shed~ became distorted such that they were no lo~er perpendicular to the .` surfaoe o~ the ~use. Such distortion occurred at random, some ~hed~ ~orming an aoute angle with the longitudinal :- 25 a~is of the member and some an obtuse angle, with the result that not only was the final appearance unsatis~actory, bu~
in some oases the outer extremities o~ the sheds ~ere so close together that arcin~ could occur betwee~ adjacent sheds. ~urthermore, upwardly ~nclined sheds would tend to colleot water lf ths 1~sulator were used out o~ door~, .
with the re~ult that the ele~tric~l prope~tie~ of the assembly would be impairea.
It is there~ore an object of -the prese~t invention to provide an outer covering ~or a substrate which can be quic~ly and ~imply applied and which~ after in~tallation, will have a d~sired con~iguration.
It is another object of the pre~ent in~ention to provide a recoverable article which be~ore de*ormation ;~ to~ the recoverable state haæ a particular d~sired configuration and which, a~ter being reoovered round a sub~trate, wlll return to, or maintai~, the said con~iguration.
It is another ob;ect of the pre~ent inve~tion ::
. . to provide a ~hedded electrically in~ulating covering : which can be applied to an electrically in~ulating member to provide that member with an electrically insulatin~
~ur~ace o~ a desired con~iguration.
~ It i~ ~nother ob~ect o~ the preBen~ in~ention : to provide a reco~erable i~sulati~g covering which includes a plurality of substantially perpendicular ~hed~ and ¢an be recovered round an electrical component ~uch a~ a :
tran~former bu~hing~ in~ulator po~t, or fuee with sub~ta~
tially no de~ormatio~ of the shedsO :.
:- It i~ a~other ob;ect of the pre~e~t in~e~tion to provide a composite ~tructure, for e~ample an eleotri¢al in~ulator7 the 3ur~ace of ~hich has a particulax desired configuratio~, and a method ~or making such a compoæi-te ~tru¢ture.
The present inYentio~ provide~ a recoverable : hollo~ article for use i~ ¢overing a substrate, whi¢h . ~ 30 arti¢le ha~ at lea~t one open end and e~-}es~ s~ :
- 5 ~
. .
-i ~a~Sl~L~5 two or more outwardly e~tending portions whioh extend around at least par~ o~ the perlphery o~ the article~ at least the portion o~ the artiole radially inwards of the radiall~ inner-i most portio~ o~ at least two out~ardly extending po~tion~ being re¢overable, the inner dimensions of the article re~ulting ,; from substrats-~ree recovery bei~ slightly smaller than the outer dimensions o~ the sub3trate, so thab, on reco~er~ o~ the article arou~d the substrate, the angle between each said at .q least two outwardly e~tending portions ~ld the longitudinal a~i~
o~ the article i~ sub~tantially that obtained on substrate-~ree recove~y.
~ he in~rentio~ al~o provides a composite structlLre which ¢omprlses a ~ubstrate having a~plied to the outer ~r~a¢e thero~ a hollo~ recoYerable article ha~ing at least one open end and t~o or more outwardly e~tendi~g portions which extend around at least part o~ the periphery o~ the article, at . least the portion o~ the article radially inwards o~ the radially i~nermo~t portio~ o~ at least two outwardly e~tending .`. portions being recoverable, the article e~hibiti~g o~ly a :-.
small degree of u~resolYed recovery. ~he unresol~ed recoveTy is such that, i~ the sub~trate wer0 removed and the article were ~ully recovered, there would be sub~tantially no ch~nge in the angle bet~een each ~aid at least t~o outwardly e~tending portions and the longitudinal a~i3 of the article. The maximum . ~ 25 degree o~ recovery that i3 within the ambit of "smalll' will of course vary from article to article, but the llmitin~ values will be readil~ determined by si~ple routi~e e~perime~t.
he in~ention ~urther provides a method/co~ering . ~, . .
a substrate comprising: positioning around the sabstrate a reo~verable hollow artiole having at leaet ore open end and :. 6 -, ; .
s ; ~ ~ " . . . ~ - .
~ 5~1~5 two or more outwardly e~tending portio~s which extend around at lea~t par~ o~ the periphery o~ the articl~, at least the portion of the artiele radially in~Jards o~ the radially in~er-most portion o~ at lea~t two outwardly e~tending portions being recoYerable, the inner dimensio~ that the article wo~ld ha~e i~ recovered in the ab~ence of a ~ubstrate being slightl~
.; smaller than the outer dimen~ions Qf the substrate so that~ on `: recovery o~ the article arouad the 3ubstrate, the angle betwaen each ~aid at least two outwardly e~tendi~lg portion3 and i 10 the lo~gitudi~al ~xi~ o~ the article is substantiall~ the æame I as the angle that would be obtained i~ the arti¢le were re- :
.~ covered in the absence o~ a ~ub~t~ate; and oausing the ar~icle ~i to recover around the sub~trate.
~he i~ve~tion al~o provides a method o~ making a ~5 hollow article, which compri~es ~orming a hollow article having at lea~t one open end and having two or more outwardl~ :~
e~tending portion~ each of which exta~ds round at least part : -o~ the periphery o~ the article, and increa~ing the inner -:
dimen~io~ o~ the article to conver,t it to a reco~erable ~tate in which at least the portion of the article radi~lly inward~
o~ th~ rad~ally innermo~t portion of at leaæt two outwardly e~tending portion~ i9 recoverable and in whioh each said at least t~o outwardly extending portion~ is such that, on re- :
cove~y o~ the arti¢le around a substrate, the angle between eac~ said at least two outwardly e2tendlng portions and the longitudinal axi~ of the article is subætantially that : obtained on a substrate-~ree recoveryO
The invention ~urther pro~ide~ a recoverable article ;-which comprises an elo~gate hollo~ member ha~ing at lea~t vne ~0 ope~ end and two ~r more shed~ which ~te~d outwardl~ ~rom the hollow member a~d are s~bstantially perpendicular (as `' .
~ 7 "' ' ' ''' " .. ,'' ' '. ' ~'' . " ' ' ' ' , ' .
-~I~S~ 5 hereinafter defined) to tha longitudinal axis o-f the hollow member~ at least the portion of the hollow member radially .inwards of the radially inner~ost portion of at least two said sheds being recoverable, the article being such that~ on recovery ; 5 o~ the article into contact with a substantially cylindrical sub-strate, the said sheds are substantially perpendioular (as hereinafter de~ined~ to the longi-tudinal aXiB of the hollow member and being such that9 on sub~trate-~ree reco~ery, the said sheds are substantially perpendicular (a~ hereinafter defined)to the longitudinal a~is of the hollow member.
~ he invention also provides a m~thod of makin~ a recoverable article which comprises ~orming an article com-prising an elongate hollow member having at least one open end and two or more sheds e~tending outwardly ~rom the hollow ; 15 member and substantially perpendicular (as hereinafter defined) to the longitudinal a~is of the hollow member, and increasing the inner dimensions o~ the a~ticle to con~ert it to a recoverable state in which the said sheds are ~ubstantiall~
perpendicular ~as hereina~ter defined) to the longitudinal axis of the hollow member9 in ~hich at least the por~ion o~
the hollow member radia~ly inwards o~ the radially innermost portion of at least two said shed~ is recoverable, and in whioh the article is such that, on recovery of the article into contact with a substantiall~ cylindrical substrate, the said sheds are substantially perpendicular (as hereina~ter defined) to the longitudinal axi~ o~ the hollow member.
~he inven~ion ~ur~her provides a composite structure ; which comprises a substrate having applied to the outer sur~ace thereo~ a recoverable article comprising an elongate hollow ~0 mem~er ha~ing at least one open end and two or more sheds which - 7a -e~-tand ou-twardly irom the hol~ow member and are ~ubstantially perpendicular (a~ hereina~ter de*ined) to the longitudinal axis o~ the composite structure~ at least the portion of the hollow member radially inwards of the radially innermost portion o~ at least ~o said sheds being reco~erable, a~d the article i s~hibiting only a small degree of unresolved recovery such ,~ that~ i~ the substrate were removed and the article were ~ully .; recovered, the said sheds would be substantially perpendicular ~as hereina~ter defined) to the longitudinal aæis o~ the hollo~
member.
~he invention also provides a method of ma~in~ a compo~ite structure comprising positioning round a substrate :~
: a recoverable article compri~in~ an elongate hollow member having at least one open end and two or more sheds which e~tend outwardly from the hollow member and are substantially perpendicular (a~ hereina~ter defined) to the longitudinal axis of the hollow member, at least the portion of the hollow ~ member radially inwards o~ the radially innermost portion o~
- at least two said she~s bei~g recoverable, the ~aid sheds after substrate *ree recovery o~ the article being substantially perpendicular (a~ hereina~ter defined~ to the longitudinal axis of the hollow member and the inn~r dimen~ions that the article would have a~ter sub~trate-~ree recovery being slightly smaller than the outer dimensions o~ the substrate 30 25 that, on recovery o~ the article into contact with the sub- :
strate, the said sheds are substantially perpendicular (as hereina~ter de~ined) to the longi~udinal axis o~ the article, and causing the article to recover into contact with the substrate O
~s indicated above, the arti¢le of the in~ention ~ - 7b _ ~ .
'', . . . .......... . .
~, . . .. . - .
~ ~5 ~
; includes a hollow member and at le~* t~o outwardly ex-tending portions each of which outwardly extending poxtions extends around at least part of the peripher~ of the article. If the outwardly eætending portions are sheds of electrically insulating material, these sheds are advantageously continuou~, extending round the entire periphery of the hollow member.
Where th~ outwardly extending portions extend round o~ly part o~ the periphery of the article, the article may~ i* desired~
be ~ade in a wrap-around ~:~rm, a longitudinal seam being made in the article a~ter, ~or e~ample, moulding. ~he out~7ardly e~tending portions are pre~erably integral with (that is, *ormed in one piece with) the remainder of the article~
~he article o~ the invention i8 advantageously and made by moulding/each o~ the outwardly e~tending por~ion~ i~, in the "as moulded" form of the article (and thus al~o in the fully recovered ~orm), preferably substantially perpendicular to the longitudinal axis of the hollo~ rnember.
- 7e --o~
It is to be understood that the term "~ub~tantially per-pendicular" covers all con~igurations ~uch that a mould spl~t only longitudinally could be removed ~rom the article with substantially no deformation o~ the outwardl~ exterldi~g portions.
In the article o~ the invention, the i~ner dime~ion~ of the reoo~erable hollow member when reoovered in the absence of a sub~trate are onl~ ~lightly s~aller ;~
than -the outer dimensionæ o~ the ~ubstrate. ~ome ~ ht difference in dimen~iorls i~ nece~ary as if the~e two dimensions were identical the article would ~ot e~ert any recovery force on the ~ubstrate9 and could thus relatively eaæil~ be remo~ed ~rom the ~ubstrate. ~y ensurin~ that the difference i~ small, however, it is po~sible -to enæure that the article when fitted exhibit~ minimal unre~olved recovery (that is it ha~ almost returned to the original ; dimen~ions in which it was moulded), ~o that there i~ little or no tendency ~or the outwardly e~tending portions to be de~ormed by inte~nal stresse~ I~ the article. Moreover, .
if the article i~ heat-recovsrable and i~ made of a material o~ which the thermal expansion i~ high compared with th~t o~ the substrate, forces between the article ana the substrate a~ter reoovary of the article into contaot with the æubstrate will ~e virbually zero at the recovery temperature; in other words, at that temperature, although not at room ~emperature~ the article ~ill have virtually the same dimensions a~ the original article would have had at the -same temperature, so there are substantlally no stre~seæ
arising ~rom the de~ormation to the heat;recoverable ætate, and thus substa~tially no tendency ~or the outwardly . , .
` 105:~L05 : e~tending por-tion~ to be deformed duri~g installation.
Although the preferred difference in the outer dimensions of the substrate and the inner dImen~ion~ of : the fully recovered article will depend on the cir¢umstance~, - 5 the inner li~ear dimensisns o~ the fully recovered article are preferably not more than 13 ~0 smaller9 calculated on the : inner dimension~, than the outer l.inear dimensio~ o~ the ~ubstrate. If the di~erence in dimens.ions is too small, ho~ever, there w~ll be a dan~er that a heat-recoverable artiole made of a ~aterial of which the thermal expansion is high compared with that of the ~ub~trate will not contact the sub~trate at the recovery temperature9 thus enabling air to be trapped between the article and the ~ub~trate. ~or ~uch ~ ;
a heat-recoverable article, the di~ference in the linear dimensio~s is pre~erably not les~ than 2 ~0.
The in~er ~urface of the article o~ the inve~tion i~ advantageou~ly shaped to fa~ilitate escape of air from between the article and the ~ub~trate d~rlng recovery.
Thus, ~or example~ the inner 3ur~aoe may haYe one or . ., , :
_ g _ .
~s~
more longitudinally extending grooves therein. Alternatively, the cross-section of the inner surface of the article in its recoverable state may be different from the cross-section of the substrate, giving channels along which air can escape during recovery. Thus for example, the article may have a polygonal inner surface ~which may, for example, be produced by the use of a mandrel having a polygonal outer surface to expand the article)~ while the substrate has a generally cylindrical outer surface.
The hollow article used in accordance with the invention exists, from the time of its manufacture to the time when it has finally been installed on the substrate, in at least three different states. These are the substan-tially dimensionally stable state in which it is formed, a first recoverable state, wherein its inner dimensions are large enough for it to be slipped over the substrate, and a second recoverable state wherein it has been recovered around the substrate to form a composite article but is prevented by the sub-strate from recovering completely to its orginal dimensionally stable state.
In the second recoverable state it is said to be partially recovered or to exhibit "unresolved recovery" and, according to the present invention, the un-resolved recovery is kept to a minimum. The article is advantageously such that recovery is effected by heating, but if desired may be such that recovery may be effected by means of a solvent or by removal of a rigid member which holds the article in the recoverable state.
The degree of expansion of the article from the substantially dimen-sionally heat-stable state to the first heat-recoverable state, resulting in an increase in the internal dimensions of the article can be smallJ for example up to about 13 per centJ or large. Advantageously when the degree is small, and preferably also when it is large, the or eaGh outwardly extending ~ portion, for example the or each shed, is prevented from moving appreciably ; from the perpendicular during the expansion process. This can readily be done by mechanical means, for example by clamping the sheds or, in the case in which there is a plurality of outwardly extending portions, by using comb-like ' . : - . . : . : ~ . , ~: , .
~ ~05~: LQ5 .
means havin,~ a number OI ~3uitably ~paced teeth or plate~ whi¢h oan be brought into abutti~g relation~hip with the outwardlg exte~ding portion~
Although the invention i~ in no way limited to parti¢ular type~ o~ artiole a~d substrate, the i~entl~n i8 . e~pecially useful for providing an electric cable or an .: electrical component ~or e~ample a ~use, tran~ormer bu~h; or i~ulator post, with a o~e-piece outer covering t~t inolude~ ~.
.i~ a pluralit~ o~ ~heds. ~s indicated a~ove9 ~or ease o* con-~ 10 ~truotion the~e ~hed~ ars advantageou~ly perpendicular to the . ~ .
longitudinal a2i~ of the in~ulatQr, ~nd perpe~dicular shed~
also have the advantage that they pre0ent a bidier appearanoe ; than i~clined sheds ~hen a ~umber of insulators are arranged . ~ .
at di~ferent angles to one another. Moreover, if the article -~
o~ the inve~tion i~ used to cover an in~ulator which i0 to be u~d in a vertical position, the artiole can be used either way up; i~ inclined sheds were used they would have to be downwardly inolined to avoid oollecting rain water.
~he article of the inventiQn may comprise ang . 20 material that can be converted to the recovera~le ~tQte, by ,.; , oro~slinking it, if nece~ary, and e~panding it, the nature o~ the material being dictat~d by the u~e to which the compo~ite ~tructure i~ to be put. '~hu~, ~or e~ample, when the article i~ to be u~ed a~ an outer covering ~or a high ; 25 voltage insul~tor, it preferably compri~es a ~o~-tracki~g electrio~lly i~ula~i~g materi~l. A non-tra~klng materlal may be de~ined as one whi~h ha~ an i~itial traoki~g voltage : o~ more than 3 KV when tested 1~ accordanee with A~'~M-D230~-64'~
~wettin~ agent 'Triton X-100), a test method which u~es the ~0 inolined plar3e llquid corltam1nation test and is de~igned to . ., .
~5~
represe~t eervice e~po~ure o~ in~ulator~ under polluti~g cnnditions. Examples of non-tracki~g ~aterial~ which may be converted -to a heat~rec~verable state are given in Briti~h Patent Specification~ Nos. 1,292,276 and 1,284,081 both i~ the ~ame o~ Raychem ~imited~ published 11th October, 1972 and 2nd August, 1972 respectively, and in DO~ 2,237,459 ~nd DOS 2,237~354 both publiæhed 7th ~'ebruary, 19'74, and DOS 2,050,581 publi~hed 29th ~pril, 1971, all in ~;he name o~
Raychem Corporation. ~he article o~ the invention may b~
moulded by, ~or e~ample, ~ompre~ion, tran~fer or in~ection mouldl~g, and7 when a~y ~uper~luous material ha~ been removed, may be e~pa~ded by any de~ired method~ eîther automatlc or manual.
I~ de~ired, an adhe~ive may be used to bond the 17 article oi the in~ention to the substrate, and/or at lea~t part of the ~urface o~ th~ arti¢le ~hich ie to contact the ~ubstrate may be pro~i~ed with a stre~s-grading material or layer, that i~ a material or layer whioh can act to reduce the electrical ~tress whlch may exi~t in variou~ area8 o~ a high voltage component, ~or example at the e~d o~ the ~¢reen o~ a high voltage cable. ~ ~uitable adhesi~eæ there may be me~tioned, ~or example, epoxy re~ (either hot or cold cured) and polyester~, which resin~ and polye~ter~ may be u~ed with or without ~ er~, and ~ilico~e-containing adhe~ivee, , -e~.peci~lly tho0e ~ith ~on-traoking propertie~. Other suitable adhe~lve ~ompo~ition~ include thoee compri~ing a ¢opolymer o~ a hydrocarbon co~taining a~ leaet one polymerizable double bond and a compou~d contæi~ing a polymerizable double bo~d to~ether with one or more carbo~lic a¢id group~, which ~0 carbox~lic acid group~ ma~ be in the ~or~ o~ a derivative~
. .
-- 12 - :
. . ~ : . .............................. .
. : .
~Sl~S
~or example an a~ter or a~ anhydrideO ~ examplea o~ such copolymer~ there may be mentioned ethylene/vinyl aceta~e .
copolymere, ethylene/eth~l acrylate copolymers9 methyl vi~yl ether/maleic anhydride copolymer~ and, pre~erably, ~lk~l e~ters o~ methyl vinyl ether/maleic a~hgdride copol~meræ.
A ~tre~s-grading ~aterial or la~er is ~ui~ably a ~terial or layer with lin~ar, or pre~erably non~ ear9 electrlcal re~i~tance properti~s and may hav~ .~orm ~tability or comprlæe a substan~ially non oryetalli~e material (~or exa~ple a ma~tic-like material) whlch haæ a visco~ity o~ le~ than 1013 cp at 25a. ~xamples Q~ ~uitable ~tre~s-grading materials are ~iven i~ DOS 20344,067 publ~hed 11th April, 1974 and DOS 2~413,475 publi~hed 2nd January7 1975, bo~h in the name o~ Raychem ~imitedO ~he a~pect~ of stre~s-gradi~g -a~
anti-tracking ma~ be combined i~/~article or compo~ite structure of the in~e~tion a~ de~oribed in Canadlan Pate~ Application ~o. 237,197 i~ the name of R. J. T. Clabburn a~d ~. J. Penneck, filed 7th O¢tober, 1975.
~he i~ve~ion will now be desoribed in more detail, by w~y o~ e~ample onl~, with reference to the accompanyin~
dra~ingæ in whi¢h: :
Figure 1 i~ a lo~gitudinal section through a covering for an in~ulator, the covering being in a heat-stable co~dition;
Figure 2 shows the covering of Pi~ure 1 in ~n ; expa~ded, heat-reco~era~le conditlon;
and ~igure 3 shows the covering o~ ~igure 2 recovered around a fuse.
_ 13 _ Re~er~i~g now -to the dr~wing~, ~igure 1 i~ a longitudinal ~ection through an articl~ ~e~erally indicated . at 10 which include~ a longitudinally egte~di~g central ; portion 11 and a number of shed~ 12 which ar0 ~ub~tantially perpendicular to the ce~tral portion 11 ~o that the article can readily be moulded. In ~igurc ~, the article i~ i~ a ':~ d.umensionally heat-3table ~orm. A heat-recoverable form 10' o~ the arti¢le 10 is 3how~ in Figure 2, ~nd, :in thi~
f~rm, the article may be poæitioned around an in~ulator with ~n outer diameter bet~aen the in~er diameter~ o~ the ~orm~ 10 and 10' (~or e~ample a ~ibre-gla~s rod 13 with metallic end cap~ 14 - ~ee ~igure ~) and may be heated to cau~e lt to ~hr~k clo~el~ into co~tact ~ith the rod, as ~ ~hown in ~igure 3, .~ 15 ~ can be ~een from the Flgure~ the sheds 12 are sub~tantia~ly perpendi~ r to the ce~tral portion 11 in all thrae ~igureæ. ~ccording to the in~ention, the inner d~ame-ter of the central portion 11 and the outer diameter of the rod 1~ are chose~ so that thi~ ~ub~ta~tially p~rpendioular arrangeme~t ls obtained in the composite article (Fi~ure 3).
not e~se~tial, however, that the perpendicul~r arrange-ment be mai~tained in the heat-recoverable ~tate indioated in ~igure 2; some de~ormatio~ o~ the ~heds may occur in this ~tate provided that dimensions are ~uoh that the desired ~5 perpendioular ~tate i~ obtained ~i~ the oompo~ite arti~le)~
The arti~le5an~ composite ~tructures of the in~entio~ are illu~trated in the following E~mples:
B x a m ~_l e ~ 1 to ~
~hree sleeve~ provided with a plurality of ~heds _ 14 :
.. ' .
:- .
~s~
~ere mould~d from electricall~ in~ulating material~ In each case the sheds, which were es~entially eimilar to those shown in ~igure 1, were ~ubstantially perpendicular to the - longltudinal axi~ o-~ the ~lee~e and were ~ymmetrioal about a plane perpendicular to ~aid longitudinal axis~ ~ach ~leeve wa~ co~verted to a heat~recoverable form by heati~, ~ e~panding on a mandrelt and cooling9 ~ollowed by removal o~
.; the mandrel. ~ach of the heat-recove~able ~rti~le~ wa~ ;
~ the~ po~itioned round an appropriate cyllndrical ~use ar~d - 10 heated ~o shrink it into clo3e oontact with the ~u~e~ In a separate experlment, heat-reco~erable articles ide~tical to those shrunk round the ~u~eæ were heated in the ab~enoe o~ any sub3trate to determ~ne the ~ully re¢overed diameter of the articles.
:.... 15 The inner diameter oi the heat-recoverable article~
and the outer diameter of the ~uses~ as well a~ the internal diameter of the ~ully recovered ~leeves are given in the Table below. ~he T~bls al~o give~ the perce~tage unreeolved recovery of the sleeves when recovered round the fu~es, this : ~0 bei~g calculated accGrding to the followi~g equation:
% unr2solved recovery = outer diameter of fu~e - :
inner diameter of fullg recovered ~leeve ~ 1 00 inner diameter o~ fulIy recovered ~leeve ~LC)5~
:;
.
T ~ B ~_E
, , .
I~ner Outer I ! . .- ~ ~, ~umber diameter diameter diameter unre~olved Example of o~ heat- o~ ~u~e o~ ~ully recovery sheds recoverable (inches) recovered ~ .
; article sleeve .
(inches) (i~ohe~3 _________ _______ ____________. ,~ _ ________, ___________ :. 1 5 2.53 2.47 2.27 8.81 2 ~ 2.78 2.72 2.50 8.79 `.:
3 11 ~ 2.97 2.74 8.38 :
,; .
I~ each case the shed~ o~ tho~e ~leeves that were reco~ered round the fuæe~ rema~ned sub~tantially perpe~dicular ~-to the lo~itudinal axl~ o~ the slee~e~
, ,, ' .
". ~ .
'`, :; .
- ' .: ,' .
. ' .
: - 16 - :~
' ' ' - ' ' ' ' . ' . , . ' . ~ :.
,; .
I~ each case the shed~ o~ tho~e ~leeves that were reco~ered round the fuæe~ rema~ned sub~tantially perpe~dicular ~-to the lo~itudinal axl~ o~ the slee~e~
, ,, ' .
". ~ .
'`, :; .
- ' .: ,' .
. ' .
: - 16 - :~
' ' ' - ' ' ' ' . ' . , . ' . ~ :.
Claims (44)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A recoverable hollow article for use in covering a substrate, which article has at least one open end and two or more outwardly extending portions which extend round at least part of the periphery of the article, at least the portion of the article radially inwards of the radially innermost portion of at least two outwardly extending portions being recoverable, the inner dimensions of the article re-sulting from substrate-free recovery being slightly smaller than the outer dimensions of the substrate, so that, on recovery of the article around the substrate, the angle between each said at least two outwardly extending portions and the longi-tudinal axis of the article is substantially that obtained on substrate-free recovery.
2. An article as claimed in claim 1, wherein there are at least four outwardly extending portions.
3. An article as claimed in claim 1 or claim 2, wherein each outwardly extending portion extends around the entire periphery of the article.
4. An article as claimed in claim 1, wherein each outwardly extending portion is integral with the remainder of the article.
5. An article as claimed in claim 1, which is made of electrically insulating material.
6. An article as claimed in claim 5, wherein each outwardly extending portion is a shed,
7. An article as claimed in claim 1, wherein each outwardly extending portion is substantially perpendicular to the longitudinal axis of the article.
8. An article as claimed in claim 1, which is heat-recoverable.
9. An article as claimed in claim 1, wherein the inner surface of the article has at least one longitudinally extending deformity therein so that escape of air from between the article and the substrate during recovery of the article is facilitated.
10. An article as claimed in claim 1, wherein the inner surface of the article is shaped to facilitate escape of air from between the article and the substrate during recovery.
11. A heat-recoverable hollow article for use in covering a substrate, which article has at least one open end and two or more outwardly extending portions which extend round at least part of the periphery of the article, at least the portion of the article radially inwards of the radially innermost portion of at least two outwardly extending portions being recoverable, the inner dimension of the article being such that, on recovery of the article into contact with the substrate, the force between the article and the substrate is substantially zero at the temperature to which the article is heated to cause recovery thereof.
12. A hollow article for covering a substrate, which article has at least one open end and two or more out-wardly extending portions which extend round at least part of the periphery of the article, at least the portion of the article radially inwards of the radially innermost portion of at least two outwardly extending portions being recoverable, the article having been deformed from an original form to a recoverable form and the inner dimensions of the article in its original form being slightly smaller than the outer dimensions of the substrate so that, on recovery of the article round the substrate, the angle between each said at least two outwardly extending portions and the longitudinal axis of the article is substantially the same as the angle between that portion and that axis is the original form of the article.
13. A recoverable hollow article suitable for use in covering a substrate, which article has at least one open end and two or more outwardly extending portions which extend around at least part of the periphery of the article, at least the portion of the article radially inwards of the radially innermost portion of at least two outwardly extending portions being recoverable, the linear inner dimensions of the article resulting from substrate-free recovery being smaller, but more than 13% smaller, calculated on said inner dimensions, than the linear outer dimensions of the substrate.
14. An article as claimed in claim 13, wherein said linear inner dimensions of the article are between 2 and 13% smaller than the linear outer dimensions of the sub-strate.
15. A hollow recoverable article suitable for use in covering an electrically insulating substrate, which article comprises electrically insulating material and includes a longitudinally extending central portion with two or more sheds which extend outwardly therefrom, at least the portion of the central portion radially inwards of the radially inner-most portion of at least two sheds being recoverable, the inner diameter that the article would have if it were recovered in the absence of a substrate being slightly smaller than the outer diameter of the substrate so that, after recovery of the article round the substrate, the said at least two sheds are substantially perpendicular to the longitudinal axis of the article.
16. An article as claimed in claim 15, which comprises non-tracking material.
17. An article as claimed in claim 15 or claim 16, wherein the sheds are integral with the remainder of the article.
18. An article as claimed in claim 15, wherein the inner surface of the article has at least one longitudinally extending deformity therein to facilitate escape of air from between the article and the substrate during recovery of the article.
19. An article as claimed in claim 15, wherein the inner surface of the article is shaped to facilitate escape of air from between the article and the substrate during recovery.
20. An article as claimed in claim 15, wherein said inner diameter is about 2 to 13% smaller than the outer diameter of the substrate, calculated on said inner diameter.
21. A composite structure which comprises a substrate having applied to the outer surface thereof a hollow recoverable article having at least one open end and two or more outwardly extending portions which extend round at least part of the periphery of the article, at least the portion of the article radially inwards of the radially innermost portion of at least two outwardly extending portions being recoverable, the article exhibiting only a small degree of unresolved recovery such that, if the substrate were removed and the article were fully recovered, there would be substantially no change in the angle between each said at least two outwardly extending portions and the longitudinal axis of the article.
22. A composite structure as claimed in claim 21, wherein there are at least four outwardly extending portions.
23. A composite structure as claimed in claim 21 or claim 22, wherein each outwardly extending portion extends round the entire periphery of the article.
24. A composite structure as claimed in claim 21, wherein each outwardly extending portion is integral with the remainder of the article.
25. A composite structure as claimed in claim 21, which is made of electrically insulating material.
26. A composite structure as claimed in claim 21, wherein each outwardly extending portion is a shed.
27. A composite structure as claimed in claim 21, wherein each outwardly extending portion is substantially perpendicular to the longitudinal axis of the composite structure.
28. A composite structure as claimed in claim 21, which is heat-recoverable.
29. A composite structure which comprises a substrate having applied to the outer surface thereof a hollow recoverable article having at least one open end and two or more outwardly extending portions which extend around at least part of the periphery of the article, at least the portion of the article radially inwards of the radially innermost portion of at least two outwardly extending portions being recoverable, the linear inner dimensions of the article resulting from substrate-free recovery being smaller, but not more than 13%
smaller, calculated on said linear inner dimensions, than the linear outer dimensions of the substrate.
smaller, calculated on said linear inner dimensions, than the linear outer dimensions of the substrate.
30. A composite structure as claimed in claim 29, wherein said inner dimensions are between 2 and 13%
smaller than the outer dimensions of the substrate.
smaller than the outer dimensions of the substrate.
31. A composite structure which comprises an electrically insulating substrate having applied to the outer surface thereof a hollow recoverable article, which article comprises electrically insulating material and includes a longitudinally extending central portion with two or more sheds which extend outwardly therefrom, at least the portion of the central portion radially inwards of the radially innermost portion of at least two sheds being recoverable, the inner diameter of the article resulting from substrate-free recovery being smaller, but not more than about 13% smaller, calculated on the inner diameter, than the outer diameter of the substrate, the sheds in the composite structure being substantially per-pendicular to the longitudinal axis of the article.
32. A composite structure as claimed in claim 71, wherein the substrate is a fuse body, bush or insulator post.
33. A composite structure as claimed in claim 31 or claim 32, wherein the article comprises non-tracking material.
34. A composite structure as claimed in claim 31, wherein the sheds are integral with the remainder of the article.
35. A method of covering a substrate comprising:
positioning round the substrate a recoverable hollow article having at least one open end and two or more outwardly extending portions which extend round at least part of the periphery of the article, at least the portion of the article radially in-wards of the radially innermost portion of at least two out-wardly extending portions being recoverable, the inner dimensions that the article would have if recovered in the absence of a substrate being slightly smaller than the outer dimensions of the substrate so that, on recovery of the article round the substrate, the angle between each said at least two outwardly extending portions and the longitudinal axis of the article is substantially the same as the angle that would be obtained if the article were recovered in the absence of a substrate; and causing the article to recover round the substrate.
positioning round the substrate a recoverable hollow article having at least one open end and two or more outwardly extending portions which extend round at least part of the periphery of the article, at least the portion of the article radially in-wards of the radially innermost portion of at least two out-wardly extending portions being recoverable, the inner dimensions that the article would have if recovered in the absence of a substrate being slightly smaller than the outer dimensions of the substrate so that, on recovery of the article round the substrate, the angle between each said at least two outwardly extending portions and the longitudinal axis of the article is substantially the same as the angle that would be obtained if the article were recovered in the absence of a substrate; and causing the article to recover round the substrate.
36. An article as claimed in claim 15, wherein at least part of the inner surface of the central portion is provided with a layer of material having linear or non-linear electrical resistance properties or other suitable stress control properties.
37. A method of making a hollow article as claimed in claim 1, which comprises forming a hollow article having at least one open end and having two or more outwardly extending portions each of which extends round at least part of the periphery of the article, and increasing the inner dimensions of the article to convert it to a recoverable state in which at least the portion of the article radially inwards of the radially innermost portion of at least two outwardly extending portions is recoverable and in which each said at least two outwardly extending portions is such that, on recovery of the article around a substrate, the angle between each said at least two outwardly extending portions and the longitudinal axis of the article is substantially that obtained on substrate-free recovery.
38. A method as claimed in claim 37. wherein, during increase of the inner dimensions of the article, each outwardly extending portion is prevented from moving appreciably from the perpendicular.
39. A method as claimed in claim 38, wherein the outwardly extending portions are prevented from moving appreciably from the perpendicular by comb-like means in abutting relationship with the outwardly extending portions.
40. An article as claimed in claim 1, which is such that on substrate-free recovery the outwardly extending portions are substantially perpendicular to the longitudinal axis of the article.
41. A recoverable article which comprises an elongate hollow member having at least one open end and two or more sheds which extend outwardly from the hollow member and are substantially perpendicular (as hereinbefore defined) to the longitudinal axis of the hollow member, at least the portion of the hollow member radially inwards of the radially innermost portion of at least two said sheds being recoverable, the article being such that, on recovery of the article into contact with a substantially cylindrical substrate, the said sheds are substantially perpendicular (as hereinbefore defined) to the longitudinal axis of the hollow member and being such that, on substrate-free recovery, the said sheds are sub-stantially perpendicular (as hereinbefore defined) to the longitudinal axis of the hollow member.
42. A method of making a recoverable article which comprises forming an article comprising an elongate hollow member having at least one open end and two or more sheds extending outwardly from the hollow member and substantially perpendicular (as hereinbefore defined) to the longitudinal axis of the hollow member, and increasing the inner dimensions of the article to convert it to a recoverable state in which the said sheds are substantially perpendicular (as herein before defined) to the longitudinal axis of the hollow member, in which at least the portion of the hollow member radially inwards of the radially innermost portion of at least two said sheds is recoverable, and in which the article is such that, on recovery of the article into contact with a substantially cylindrical substrate, the said sheds are substantially per-pendicular (as hereinbefore defined) to the longitudinal axis of the hollow member.
43. A composite structure which comprises a substrate having applied to the outer surface thereof a recoverable article comprising an elongate hollow member having at least one open end and two or more sheds which extend out-wardly from the hollow member and are substantially per-pendicular (as hereinbefore defined) to the longitudinal axis of the composite structure, at least the portion of the hollow member radially inwards of the radially innermost portion of at least two said sheds being recoverable, and the article exhibiting only a small degree of unresolved recovery such that, if the substrate were removed and the article were fully recovered, the said sheds would be substantially perpendicular (as hereinbefore defined) to the longitudinal axis of the hollow member.
44. A method of making a composite structure comprising positioning round a substrate a recoverable article comprising an elongate hollow member having at least one open end and two or more sheds which extend outwardly from the hollow member and are substantially perpendicular (as hereinbefore defined) to the longitudinal axis of the hollow member, at least the portion of the hollow member radially inwards of the radially innermost portion of at least two said sheds being recoverable, the said sheds after substrate-free recovery of the article being substantially perpendicular (as hereinbefore defined) to the longitudinal axis of the hollow member and the inner dimensions that the article would have after substrate-free recovery being slightly smaller than the outer dimensions of the substrate so that, on recovery of the article into contact with the substrate, the said sheds are substantially perpendicular (as hereinbefore defined) to the longitudinal axis of the article, and causing the article to recover into contact with the substrate.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US51311174A | 1974-10-08 | 1974-10-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1051105A true CA1051105A (en) | 1979-03-20 |
Family
ID=24041933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA237,213A Expired CA1051105A (en) | 1974-10-08 | 1975-10-07 | Article and method for covering substrates and composite structures so made |
Country Status (5)
| Country | Link |
|---|---|
| AU (1) | AU504492B2 (en) |
| CA (1) | CA1051105A (en) |
| DE (1) | DE7531935U (en) |
| FR (1) | FR2287755A1 (en) |
| GB (1) | GB1530995A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2170360B (en) * | 1979-03-12 | 1988-10-12 | Lapp Insulator Co | High voltage resistant members and method for producing same |
| GB8333249D0 (en) * | 1983-12-13 | 1984-01-18 | Raychem Ltd | Electrically insulating articles |
| FR2587827B1 (en) * | 1985-09-24 | 1988-03-18 | Alsthom | METHOD FOR MANUFACTURING AN INSULATING STAY, AND STAY PERFORMED ACCORDING TO THE PROCESS |
| AT389185B (en) * | 1986-12-18 | 1989-10-25 | Isovolta | Electrically insulating component, and a method for producing it |
| IT1208237B (en) * | 1987-01-29 | 1989-06-12 | Fip Formatura Inienzione Poli | PERFECTED INSULATOR WITH THERMOPLASTIC RESIN COATING |
| GB8923408D0 (en) * | 1989-10-17 | 1989-12-06 | Raychem Ltd | Electrical insulator |
-
1975
- 1975-10-07 AU AU85524/75A patent/AU504492B2/en not_active Expired
- 1975-10-07 CA CA237,213A patent/CA1051105A/en not_active Expired
- 1975-10-07 GB GB40986/75A patent/GB1530995A/en not_active Expired
- 1975-10-08 FR FR7530785A patent/FR2287755A1/en active Granted
- 1975-10-08 DE DE7531935U patent/DE7531935U/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1530995A (en) | 1978-11-01 |
| FR2287755B1 (en) | 1982-02-05 |
| AU8552475A (en) | 1977-04-21 |
| AU504492B2 (en) | 1979-10-18 |
| FR2287755A1 (en) | 1976-05-07 |
| DE7531935U (en) | 1976-12-23 |
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