CA1194819A - Tubular plastics objects - Google Patents
Tubular plastics objectsInfo
- Publication number
- CA1194819A CA1194819A CA000417373A CA417373A CA1194819A CA 1194819 A CA1194819 A CA 1194819A CA 000417373 A CA000417373 A CA 000417373A CA 417373 A CA417373 A CA 417373A CA 1194819 A CA1194819 A CA 1194819A
- Authority
- CA
- Canada
- Prior art keywords
- strip
- rib
- longitudinal edges
- body portion
- socket
- 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
Abstract
Abstract of the Disclosure This invention relates to the formation of tubular objects by spirally winding and seaming a relatively rigid strip of plastics material. In the prior form of this rigid plastic strip, it was difficult to control and change the diameter of the resulting the due to the forces required to overcome the extreme frictional engagement between the interlocking portions of that prior art strip. This invention provides a sealing flap (15, 215) along one longitudinal edge (5, 25) of the strip, and an engaging surface (16, 216) along the other edge (11, 211) positioned close to but separate from the interlocking portions (8 and 12, 28, 212) of these longitudinal edges. The provision of these sealing flaps and engaging surfaces permit the interlocking portions at the edges to be designed independent of the ability of the these interlocking portions to create a fluid seal.
This results in optimum operation of these interlocking portions to, for example, permit relatively rapid changes in the diameter of the tube as it is formed, as well as subsequent to its formation.
This results in optimum operation of these interlocking portions to, for example, permit relatively rapid changes in the diameter of the tube as it is formed, as well as subsequent to its formation.
Description
~:~9~
IMPRCVED TUBULAR PL~STICS QBJE~TS
Backqrou~d o~_~he InYen~ion In the past, generally, spirally wour.d tubes formed Erom plastics have been made from soft rubber-like plastics or from rigid plastics that have keen heated and softened and then wound into a spiral tubular configuration.
In U.S. Patent No. 4~209tO43, Julian M. Menzel, a new approach is desc~ibed according to which a unique ribbed ribbon is usedO m e ribbon is shaped so that a spirally wound tube can ke produced with interlocking edges of the ribkon fonned ~v ~he shaFe of the ribs on the xibbon itself.
Also known is a machine for spirally winding such a strip to produce an elonyated tubular article. In the operation cf this ~achine, a differential pressure or force is applied to the parts of the strip being brought into con~act with one another for interlocking ~e edgas of the ribkon to form a spiral joint~ m ese parts are ed ~der differential force so that the diameter oE the tube can be controlled according to the extent oE the difference in the force applied to the two interengaging edges. Also, the method oE
interengaging the two edges oE the tuba which are to k~ locked toget~er is such that the ap~lication of this differential force -forces ~hese interengaging edges Eirmly together to give an effecti~e joint.
Hc~ever; it is possible to wind such strip on a .~andre~. But whether ~he machine described above is used to pro~c~ the ~ube, or whether a mandrel ls use~, it is only pQssjble t~ ~aintain con'ro' ~ver relatively very minor changes in ~iam~ter that ca~ occur ~Lin~J t~
windin~ process.
I~ is an o~,e~ the present in~ention to provl~e cert~-n ~mprovem2nts to the ~or~n o~ the strip wi~ch wi~l e~lch g~eat~r charges in dia~e~er to occur during ~he ac~ual wi~ding o-~ the ~*rip in~o a tubeO and such chan~es in ~ia~eter can ~e relati~ely rapid or quite slow, to ~ e a~prox~mately a range of from 1 ~r ~Fe~ ~r_ ~ao or r~e of ta~er.
,.
.
~1 ~ 9 L~
It is a furthe.r object of the lnvention to so construct the spiral joint that, even when made of a ve.ry rigid plastic for ~ tu~e of considerable rigidity, either with ribs as an outer part of the configuration, or the ribs as an inner part of the con~lguration~ or both, the strip can readily be spirally wound into a tu~e, yet have a spiral seam of such integrity that it will seal into a watertight jolnt with or without the r.eed for using a sealing compound.
This special feature is achieved by using a particular type of snap lock continuous joint which is so designed that ~hen snapped into place, ~y whatever means, for example by means of a ~air of pinch rollers in one type of the above-descri~ed tube forming machines, the spiral ~oint will seal and yet still allow itself to ~e manipulated into a larger or smaller diameter anywhere along the lengt~ of the tu~e by simply a~plying a circumferential twisting moment, applied either within the confines of the a~ove-descri~ed machine which is winding the tube, or even after the tu~e has ~een wound.
Brie~ Summary of the_In~entio~
The invention comprises an improved elongated strip which includes a member, namely a sealing flap, which is generally parallel and flush with the maln body portion o the strip, and thus the inner wall of the tube made thereby, extending substantially at right angles to the portion o~ the locking device, namely upstanding rib; which rib is generally of the type as descri~ed in the earlier referred to U~SO
~atent No. 4,209,043.
Dhe member or sealing ~lap extends across the actual spiral seam joint onto the adjacent wall from which the opposite portion of the lock, namely the socket which receives ~le headed ribr is extended, and in this portion of the wall there is a recess equal to ~he dimensions of the aforementioned extended member or sealing flap, which is o~ such a configuration that lts extreme edge can ~e feathered so that it tends to be somewhat resilient eT~en in a rigid plastlrs material, so that when inter~al pressure ls applied to ~he fini~hed spirally wound tube, this extended mem~er or seal..ng flapt wiLJh its feathered edge, will increase tne seal.
~owever~ in the case where external pres6ure is appl.ied, ~he mating surfaces can ce bonded together ~hus pr~v~cing a relatively large ~nkinuous ~ealing s~rface~
In addition, the extending m~ber or sealing flap can have locking protuberances on its upper surface that can engage in the configuration created in the surface of ~he mating parts.
This construction results in a locking device in which the joint can sli~e within itself, and as changes in diameter are required it ls just a rnatter of circumferentially clinching the spiral tube with a differential movesnent within the con~ines where changes of diameter are required.
All these configurations can be carried out usin~ a rigid plastic profile that is at ambient ~em~erature, which of course adds to the feature because of the spring-like tension i~arted to the plastics profile when wound into a tu~e allowing it to naturally take a circular configuration which of course is important in order that the sliding between the two parts of the joir.t can occur, More specifically, to facilitate sliding along the joint, the multiple barbs of the locking device of Menzel, U.S. Patent No.
4,209,043, are eliminated in favor of a single enlarged head or hook which is received within a mating recess or soc~et. In addition, the components of the lo~king device are provided with increased clearance space to rurther facilitate the sliding movement necessar~ ~o allow changin~g of the diameter of the tu~e. ~owever, the increa~ed clearance space correspondingly increases the likellhood of Eluid leakage throuyh the joint, and to seal the joint, the sealiny member~ namely the seali~g flap referred to above, can be employed.
In order, however, to enable the nature of the invention to be more f~lly appreclated, but without necessarily limitins the invention to the form illustrated, embodiments are ~hown in the accompanying drawing in which:
Bri~f Des~xlptlQn of ~he Draw~nqs FIG. 1 is a portion of a tube in cross section shcwir.g the t~o edges of the strip which in~erlock to form a spiral seam.
FIGn 2 shows a further embodlmenk of the invention similar ~o thak of FI~
DetaileG De$c~iPtiQn 2~ the Inve~
~n FIG. 1, ~he body portion 1 of the strip has a n~mber of upstandin~ webs 2 on i , each of which have webs or enlarged ~r.d portions ~ of pr~eraDl~f- a ~tee" confiGurc,tior.. ~hat is, ~eb~ 7 comprise tl-e upstan~ing por~ion 3 and the enlarged end portion ~. The functions of these webs are more fully set forth in the above-refel-enced ~.S. Patent No. ~,209,043. Also, as in this V.S. patent, a first longltudina] edge 5 of the strip has a shorter locking rib 6. However, in this invention this rib 6 is headed and is provided with a hook 7 at its top arran~ed to forn~ a ridce ~ to engage, when wound into tubular form, a corres-ponding rid~e 9 of extension 10 at the second longitudinal edge 11 of the body portion 1 oE the strip. The web portion 3 including a socket 12 which mechanically locks over the locking rib 6. Lock-web 13 projects angularly upwardly so that this part 13 can have its extreme edge 14 engage beneath the enlarged end portion 4 of the first full web 3 at the firs-t edge 5 of the strip such as more fully set forth in the abo~e-re~erenced patent.
~n extended tapering sealing 1ap 15 is provided on the edge 5 of the strip and outwardly beyond the shorter locking rib 6. The sealing flap 15 is arranged to engage a mating surface 16 on the second edge 11 of the strip body portion 1 on the side of the body portion 1 opposite socket 12 when pressure is exerted on the inside of the tube. The relatively thin and resilient sealing flap 15 is forced against the mating surface 16 to increase the fluid-tight seal in the manner of a hydraulic cup washer.
~n optional feature of the invention is the pro~ision of a second resilient sealing flap 15' which is integral with the lock-web 13 and which projects axially from the base of the loc~-web 13. With the strip joined together in a tubular form, the sealing flap 15' resiliently engages a corresponding mating surface 16' on the outer surface of the body portion 1 to seal the tube against the ingress of fluids, such as water.
FIG. 2 shGws a portion of a tube which is formed with a str~p which is identical to the strip shown in FIG. 1 in all respects not shown or described herein. However, portions of the tube and the strip of FIG. 2 corresponding to those shown in FIG. 1 are designated by corresponding reference characters preceeded by the numeral 2. Here, the first edge 25 oE the body portion 21 of the strip includes sealing flap 215 which further includes a hook-like edge portion 217. ~lso~
, flap 215 differs from sealing flap 15 of FIG. 1 in that flap 215 also includes an elongated central portion 218 of generally uniforrn thickness intercornecring the first porkicn of flap 215 connected to body portion 21 with the hook portion 217c The extrerne edge of flap 215 is feathered as in FIG. 1. The other edge 211 of body portion ~1 includes a rnat.ing surface 216 comprising a recess which is shaped to conform to the upFer surface of sealing flap 215.
Ridge 28 of hook 27 in this ernbodiment faces ~he opposice direction from that shown in FIG. 1. Although the operation is essentlally identical, the corresponding ridge 29 of the extension 210 preferably is spaced from ridge 28 in order to provide a slisht clearance.
As in the embodiment of FIG. 1, the strip and tube fo~ned thereby of FIG. 2 employs the sealing flap 215 and the mating surface 216 to provide most, if not all, of the fluid s~aling f~mction m e addition of the hook portion 217 and the corresponding portion o the ~ating surface 216 has a further advantage in assuring alignment and mating of flap 215 with surface 216.
~he slight clearance between ridges 28 and 29 permit a slight displacement of edge 211 relative to e~ge 25 of the strip in order to facilitate rapid changes in the diameter of the t~l~e fonmed there~y.
This slight radial displac~ment, either brought on by the o~eraticn of ~he above-referenced machine (via the application of the differential force as the spiral seam is formed) or by subsequent ~anipulation of the strip in the tube form, has li-ctle o~ no effect on the sealing function provided by the sealing flap ~15 ar.d mating surface 216. I, will be realiæed from the foregoing that, so far as longitudinal m.~ve-ment of the one edge 5 or 25 of the strip in relation to the other e~e 11, 211 oE tle strip is concerned, the arrangemerlt is such that t~e one edge of the striE~ ~an move in relation to the other inter~ngaginy edge~
of the strlp to all~w the changes in diameter tc ~e effected as opposed co the more riqid form o~ interlocking discio~ed in ~.S~ Pate}lt ~
4,209,043~ In this patent, the differe.n~ial !nD~em~n. existed p~ m~ y ~or the ~ur~ose of forclng the ~oint together and for maint.~srling a given constant ci~m~t~rF but g~nerc~ could nct all~ ar.y ~lgrifi~-l-t sliding .~ov~Jment therea~ter wit.~out ~he exertlon of consid~rakle f~r;~
in -the for~ o~ a ~i~c~m~e~rentia~ twisti.ng mr~.ert ,~ring wini~r.~ c~f ~i~e . . .
tube. With this i~ventlon, ha~ev~r, suficient clear~nGe is provided between the short rib 6 or 26 and the socket 12 or 215 to allow significant sliding movement between these interengaging portions to thereby allcw the di~neter of the tube formed from the strip to ~
increased or decreased as desired~ m e sealing flap 15 cooperate~ with the mating suxface 16 to seal ~he joint, notwithstanding the clearance space referred to above.
Clearance be~ween the locking rib and socket of ~he disclosed embodiments is not necessary to the operation of the disclosed inven-tion. Indeed, a relatively snug fit between the locking rib 6 or 26and the socket 12 or 21X respectively can be tolerated and in some cases desired, depending on the structural characteristics of the strip itself (the stiffnRss~ etc.), the frictional characteristics of ~he rnaterial used ~whether the material is FVC or PTFE, each of which have vastly different frictional co-efficients~, and whether the tube to be formed frorn the strip is to have a relatively cons~ant diameter or a diameter which rapidly changes. What is most signlficant is that the provision of a sealing flap as disclosed permits these interlocking features on the e~ges to be designe~ to fulrill a mechanical inter-locking function without regard to whether their ultlmate design wouldresult in an adequate fluid seal. ~liS fluid seal function, of course, is entirely or at least mostly fulfilled by the æ parately provi~ed seali~g fl p and mating surface. Due to the rel~tively flexible and/or resilient nature of the sealing flap, its sealing engagement with the corresponding mating surface would effect only minimall~ the operation of the remainder of the seam structure.
m e sealing flaps 15, 15', and 215 c n be longitudinally corrugated at the mating surface or otherwise formed to still further increase the sealing actionO Also, for example, a thermoplastic material of a softer characteristic than the rest of the strip could be e~truded onto mating surfaces 16~ 16', or 216, or sealing ~laps 15, i5', or 215 b~ ~nown tecnnlques to aid in sealing a~ these mut~aliy mating surfaces. ~lso, se~ling flap~ 15, 151, ~nd 215 could ~e initially formed so as to be mecham cally deflected ~Y ~leir respecti-~e mating suxfaces 16 ~nd 1~' when in~erengaged in the tu~e formillg p~ocess, thus formlng a eontiiluou3 seal ~hich is b1ased clos2d~ FIG. 2 sh~s sealinq flap ~15 in p~lanto~n ln lts Fosition ~.s ini~iaily formed and prior to engaging mating surfaces 216. The final sealing position is as shown.
In one embodiment of the invention, a strip of un-plasticized PVC having lingitudinal edges as in FIG. 2 had a total width from the outer edge of lock-web 213 to the feathered edge 218 of sealing flap 215 of about 20 cm. The total thickness of the strip was about 2.5 cm and the body portion 21 had a thickness of about .5 cm. The thickness of the elongated central portion of sealing flap 215 was about one-half the thickness of body portion 21 or about .25 cm. This sealing flap extended outwardly past the headed rib 26 away from the rest of the strip about 1.8 cm. The hook portion 217 had a maximum thickness of about .381 cm. Tubes and pipes made from this strip were wound on the machine described supra. The tubes could be made to have a constant diameter ranging from about 45 cm to about 122 cm, and could be made to have a rapidly changing diameter as the strip was spirally wound and the edges interengaged. A solvent cement was placed within the seam structure. The resulting seam was water-tight.
IMPRCVED TUBULAR PL~STICS QBJE~TS
Backqrou~d o~_~he InYen~ion In the past, generally, spirally wour.d tubes formed Erom plastics have been made from soft rubber-like plastics or from rigid plastics that have keen heated and softened and then wound into a spiral tubular configuration.
In U.S. Patent No. 4~209tO43, Julian M. Menzel, a new approach is desc~ibed according to which a unique ribbed ribbon is usedO m e ribbon is shaped so that a spirally wound tube can ke produced with interlocking edges of the ribkon fonned ~v ~he shaFe of the ribs on the xibbon itself.
Also known is a machine for spirally winding such a strip to produce an elonyated tubular article. In the operation cf this ~achine, a differential pressure or force is applied to the parts of the strip being brought into con~act with one another for interlocking ~e edgas of the ribkon to form a spiral joint~ m ese parts are ed ~der differential force so that the diameter oE the tube can be controlled according to the extent oE the difference in the force applied to the two interengaging edges. Also, the method oE
interengaging the two edges oE the tuba which are to k~ locked toget~er is such that the ap~lication of this differential force -forces ~hese interengaging edges Eirmly together to give an effecti~e joint.
Hc~ever; it is possible to wind such strip on a .~andre~. But whether ~he machine described above is used to pro~c~ the ~ube, or whether a mandrel ls use~, it is only pQssjble t~ ~aintain con'ro' ~ver relatively very minor changes in ~iam~ter that ca~ occur ~Lin~J t~
windin~ process.
I~ is an o~,e~ the present in~ention to provl~e cert~-n ~mprovem2nts to the ~or~n o~ the strip wi~ch wi~l e~lch g~eat~r charges in dia~e~er to occur during ~he ac~ual wi~ding o-~ the ~*rip in~o a tubeO and such chan~es in ~ia~eter can ~e relati~ely rapid or quite slow, to ~ e a~prox~mately a range of from 1 ~r ~Fe~ ~r_ ~ao or r~e of ta~er.
,.
.
~1 ~ 9 L~
It is a furthe.r object of the lnvention to so construct the spiral joint that, even when made of a ve.ry rigid plastic for ~ tu~e of considerable rigidity, either with ribs as an outer part of the configuration, or the ribs as an inner part of the con~lguration~ or both, the strip can readily be spirally wound into a tu~e, yet have a spiral seam of such integrity that it will seal into a watertight jolnt with or without the r.eed for using a sealing compound.
This special feature is achieved by using a particular type of snap lock continuous joint which is so designed that ~hen snapped into place, ~y whatever means, for example by means of a ~air of pinch rollers in one type of the above-descri~ed tube forming machines, the spiral ~oint will seal and yet still allow itself to ~e manipulated into a larger or smaller diameter anywhere along the lengt~ of the tu~e by simply a~plying a circumferential twisting moment, applied either within the confines of the a~ove-descri~ed machine which is winding the tube, or even after the tu~e has ~een wound.
Brie~ Summary of the_In~entio~
The invention comprises an improved elongated strip which includes a member, namely a sealing flap, which is generally parallel and flush with the maln body portion o the strip, and thus the inner wall of the tube made thereby, extending substantially at right angles to the portion o~ the locking device, namely upstanding rib; which rib is generally of the type as descri~ed in the earlier referred to U~SO
~atent No. 4,209,043.
Dhe member or sealing ~lap extends across the actual spiral seam joint onto the adjacent wall from which the opposite portion of the lock, namely the socket which receives ~le headed ribr is extended, and in this portion of the wall there is a recess equal to ~he dimensions of the aforementioned extended member or sealing flap, which is o~ such a configuration that lts extreme edge can ~e feathered so that it tends to be somewhat resilient eT~en in a rigid plastlrs material, so that when inter~al pressure ls applied to ~he fini~hed spirally wound tube, this extended mem~er or seal..ng flapt wiLJh its feathered edge, will increase tne seal.
~owever~ in the case where external pres6ure is appl.ied, ~he mating surfaces can ce bonded together ~hus pr~v~cing a relatively large ~nkinuous ~ealing s~rface~
In addition, the extending m~ber or sealing flap can have locking protuberances on its upper surface that can engage in the configuration created in the surface of ~he mating parts.
This construction results in a locking device in which the joint can sli~e within itself, and as changes in diameter are required it ls just a rnatter of circumferentially clinching the spiral tube with a differential movesnent within the con~ines where changes of diameter are required.
All these configurations can be carried out usin~ a rigid plastic profile that is at ambient ~em~erature, which of course adds to the feature because of the spring-like tension i~arted to the plastics profile when wound into a tu~e allowing it to naturally take a circular configuration which of course is important in order that the sliding between the two parts of the joir.t can occur, More specifically, to facilitate sliding along the joint, the multiple barbs of the locking device of Menzel, U.S. Patent No.
4,209,043, are eliminated in favor of a single enlarged head or hook which is received within a mating recess or soc~et. In addition, the components of the lo~king device are provided with increased clearance space to rurther facilitate the sliding movement necessar~ ~o allow changin~g of the diameter of the tu~e. ~owever, the increa~ed clearance space correspondingly increases the likellhood of Eluid leakage throuyh the joint, and to seal the joint, the sealiny member~ namely the seali~g flap referred to above, can be employed.
In order, however, to enable the nature of the invention to be more f~lly appreclated, but without necessarily limitins the invention to the form illustrated, embodiments are ~hown in the accompanying drawing in which:
Bri~f Des~xlptlQn of ~he Draw~nqs FIG. 1 is a portion of a tube in cross section shcwir.g the t~o edges of the strip which in~erlock to form a spiral seam.
FIGn 2 shows a further embodlmenk of the invention similar ~o thak of FI~
DetaileG De$c~iPtiQn 2~ the Inve~
~n FIG. 1, ~he body portion 1 of the strip has a n~mber of upstandin~ webs 2 on i , each of which have webs or enlarged ~r.d portions ~ of pr~eraDl~f- a ~tee" confiGurc,tior.. ~hat is, ~eb~ 7 comprise tl-e upstan~ing por~ion 3 and the enlarged end portion ~. The functions of these webs are more fully set forth in the above-refel-enced ~.S. Patent No. ~,209,043. Also, as in this V.S. patent, a first longltudina] edge 5 of the strip has a shorter locking rib 6. However, in this invention this rib 6 is headed and is provided with a hook 7 at its top arran~ed to forn~ a ridce ~ to engage, when wound into tubular form, a corres-ponding rid~e 9 of extension 10 at the second longitudinal edge 11 of the body portion 1 oE the strip. The web portion 3 including a socket 12 which mechanically locks over the locking rib 6. Lock-web 13 projects angularly upwardly so that this part 13 can have its extreme edge 14 engage beneath the enlarged end portion 4 of the first full web 3 at the firs-t edge 5 of the strip such as more fully set forth in the abo~e-re~erenced patent.
~n extended tapering sealing 1ap 15 is provided on the edge 5 of the strip and outwardly beyond the shorter locking rib 6. The sealing flap 15 is arranged to engage a mating surface 16 on the second edge 11 of the strip body portion 1 on the side of the body portion 1 opposite socket 12 when pressure is exerted on the inside of the tube. The relatively thin and resilient sealing flap 15 is forced against the mating surface 16 to increase the fluid-tight seal in the manner of a hydraulic cup washer.
~n optional feature of the invention is the pro~ision of a second resilient sealing flap 15' which is integral with the lock-web 13 and which projects axially from the base of the loc~-web 13. With the strip joined together in a tubular form, the sealing flap 15' resiliently engages a corresponding mating surface 16' on the outer surface of the body portion 1 to seal the tube against the ingress of fluids, such as water.
FIG. 2 shGws a portion of a tube which is formed with a str~p which is identical to the strip shown in FIG. 1 in all respects not shown or described herein. However, portions of the tube and the strip of FIG. 2 corresponding to those shown in FIG. 1 are designated by corresponding reference characters preceeded by the numeral 2. Here, the first edge 25 oE the body portion 21 of the strip includes sealing flap 215 which further includes a hook-like edge portion 217. ~lso~
, flap 215 differs from sealing flap 15 of FIG. 1 in that flap 215 also includes an elongated central portion 218 of generally uniforrn thickness intercornecring the first porkicn of flap 215 connected to body portion 21 with the hook portion 217c The extrerne edge of flap 215 is feathered as in FIG. 1. The other edge 211 of body portion ~1 includes a rnat.ing surface 216 comprising a recess which is shaped to conform to the upFer surface of sealing flap 215.
Ridge 28 of hook 27 in this ernbodiment faces ~he opposice direction from that shown in FIG. 1. Although the operation is essentlally identical, the corresponding ridge 29 of the extension 210 preferably is spaced from ridge 28 in order to provide a slisht clearance.
As in the embodiment of FIG. 1, the strip and tube fo~ned thereby of FIG. 2 employs the sealing flap 215 and the mating surface 216 to provide most, if not all, of the fluid s~aling f~mction m e addition of the hook portion 217 and the corresponding portion o the ~ating surface 216 has a further advantage in assuring alignment and mating of flap 215 with surface 216.
~he slight clearance between ridges 28 and 29 permit a slight displacement of edge 211 relative to e~ge 25 of the strip in order to facilitate rapid changes in the diameter of the t~l~e fonmed there~y.
This slight radial displac~ment, either brought on by the o~eraticn of ~he above-referenced machine (via the application of the differential force as the spiral seam is formed) or by subsequent ~anipulation of the strip in the tube form, has li-ctle o~ no effect on the sealing function provided by the sealing flap ~15 ar.d mating surface 216. I, will be realiæed from the foregoing that, so far as longitudinal m.~ve-ment of the one edge 5 or 25 of the strip in relation to the other e~e 11, 211 oE tle strip is concerned, the arrangemerlt is such that t~e one edge of the striE~ ~an move in relation to the other inter~ngaginy edge~
of the strlp to all~w the changes in diameter tc ~e effected as opposed co the more riqid form o~ interlocking discio~ed in ~.S~ Pate}lt ~
4,209,043~ In this patent, the differe.n~ial !nD~em~n. existed p~ m~ y ~or the ~ur~ose of forclng the ~oint together and for maint.~srling a given constant ci~m~t~rF but g~nerc~ could nct all~ ar.y ~lgrifi~-l-t sliding .~ov~Jment therea~ter wit.~out ~he exertlon of consid~rakle f~r;~
in -the for~ o~ a ~i~c~m~e~rentia~ twisti.ng mr~.ert ,~ring wini~r.~ c~f ~i~e . . .
tube. With this i~ventlon, ha~ev~r, suficient clear~nGe is provided between the short rib 6 or 26 and the socket 12 or 215 to allow significant sliding movement between these interengaging portions to thereby allcw the di~neter of the tube formed from the strip to ~
increased or decreased as desired~ m e sealing flap 15 cooperate~ with the mating suxface 16 to seal ~he joint, notwithstanding the clearance space referred to above.
Clearance be~ween the locking rib and socket of ~he disclosed embodiments is not necessary to the operation of the disclosed inven-tion. Indeed, a relatively snug fit between the locking rib 6 or 26and the socket 12 or 21X respectively can be tolerated and in some cases desired, depending on the structural characteristics of the strip itself (the stiffnRss~ etc.), the frictional characteristics of ~he rnaterial used ~whether the material is FVC or PTFE, each of which have vastly different frictional co-efficients~, and whether the tube to be formed frorn the strip is to have a relatively cons~ant diameter or a diameter which rapidly changes. What is most signlficant is that the provision of a sealing flap as disclosed permits these interlocking features on the e~ges to be designe~ to fulrill a mechanical inter-locking function without regard to whether their ultlmate design wouldresult in an adequate fluid seal. ~liS fluid seal function, of course, is entirely or at least mostly fulfilled by the æ parately provi~ed seali~g fl p and mating surface. Due to the rel~tively flexible and/or resilient nature of the sealing flap, its sealing engagement with the corresponding mating surface would effect only minimall~ the operation of the remainder of the seam structure.
m e sealing flaps 15, 15', and 215 c n be longitudinally corrugated at the mating surface or otherwise formed to still further increase the sealing actionO Also, for example, a thermoplastic material of a softer characteristic than the rest of the strip could be e~truded onto mating surfaces 16~ 16', or 216, or sealing ~laps 15, i5', or 215 b~ ~nown tecnnlques to aid in sealing a~ these mut~aliy mating surfaces. ~lso, se~ling flap~ 15, 151, ~nd 215 could ~e initially formed so as to be mecham cally deflected ~Y ~leir respecti-~e mating suxfaces 16 ~nd 1~' when in~erengaged in the tu~e formillg p~ocess, thus formlng a eontiiluou3 seal ~hich is b1ased clos2d~ FIG. 2 sh~s sealinq flap ~15 in p~lanto~n ln lts Fosition ~.s ini~iaily formed and prior to engaging mating surfaces 216. The final sealing position is as shown.
In one embodiment of the invention, a strip of un-plasticized PVC having lingitudinal edges as in FIG. 2 had a total width from the outer edge of lock-web 213 to the feathered edge 218 of sealing flap 215 of about 20 cm. The total thickness of the strip was about 2.5 cm and the body portion 21 had a thickness of about .5 cm. The thickness of the elongated central portion of sealing flap 215 was about one-half the thickness of body portion 21 or about .25 cm. This sealing flap extended outwardly past the headed rib 26 away from the rest of the strip about 1.8 cm. The hook portion 217 had a maximum thickness of about .381 cm. Tubes and pipes made from this strip were wound on the machine described supra. The tubes could be made to have a constant diameter ranging from about 45 cm to about 122 cm, and could be made to have a rapidly changing diameter as the strip was spirally wound and the edges interengaged. A solvent cement was placed within the seam structure. The resulting seam was water-tight.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS-
1. 1. In an elongated strip of plastics material for forming articles by spiral winding said strip to overlap and interlock the two longitudinal edges of a body portion of the strip to form a continuous spiral seam, a first of said longitudinal edges having a locking rib upstanding from said body portion and a second of said longitudinal edges including a longitudinally extending socket for receiving said rib such that said spiral seam is formed, the improvement comprising one of said longitudinal edges includes a relatively resilient sealing flap extending laterally from and generally parallel to said body portion and the other of said longitudinal edges includes a mating surface for mating with said sealing flap.
2. A strip as set forth in Claim 1 wherein said one of said longitudinal edges is said first longitudinal edge, and said sealing flap extends outwardly from said body portion beyond said rib.
3. A strip as set forth in Claim 1 wherein said rib is headed and includes a ridge extending along one side and wherein said socket includes a corresponding ridge for engaging said ridge on said rib.
4. A strip as set forth in Claim 3 wherein said headed rib and said socket are mutually dimensioned so that, when said headed rib is engaged in said socket, a clearance exists between said ridge and said corresponding ridge.
5. A strip as set forth in Claim 1 wherein said sealing flap is feathered at its extreme edge.
6. An elongated strip as set forth in Claim 2 wherein said mating surface comprises a longitudinally extending recess in said body portion.
7. An elongated strip as set forth in claim 3 wherein said strip includes a plurality of upstanding webs, each of said webs including an enlarged end portion.
8. A strip as set forth in Claim 7 wherein one of said longitudinal edges further includes a lock-web, said lock-web being dimensioned to extend between a first of said upstanding webs adjacent said headed rib and said socket when said rib is engaged within said socket.
9. A strip as set forth in Claim 7 wherein said upstanding webs are generally T-shaped in cross section and wherein said longitudinally extending socket further includes an expanded end portion dimensionally corresponding to the upper ends of said upstanding webs.
10. In a tube comprising an elongated strip having a body portion with two longitudinal edges, the strip being spirally wound to overlap and interlock said two longitudinal edges, a first of said longitudinal edges including a lock rib and a second of said longi-tudinal edges including a longitudinal socket sized to mechanically receive and engage said lock rib, the improvement comprising one of said longitudinal edges has a sealing flap extending laterally from and generally parallel to said body portion, said sealing flap being resilient relative to said body portion, the other of said longitudinal edges including a mating surface on said body portion shaped to engage a surface of said sealing flap when said longitudinal edge portions are interlocked, whereby said tube includes an helically extending, fluid-tight seam.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000417373A CA1194819A (en) | 1982-12-09 | 1982-12-09 | Tubular plastics objects |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000417373A CA1194819A (en) | 1982-12-09 | 1982-12-09 | Tubular plastics objects |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1194819A true CA1194819A (en) | 1985-10-08 |
Family
ID=4124120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000417373A Expired CA1194819A (en) | 1982-12-09 | 1982-12-09 | Tubular plastics objects |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1194819A (en) |
-
1982
- 1982-12-09 CA CA000417373A patent/CA1194819A/en not_active Expired
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| MKEX | Expiry |