CA2190935A1 - Method for continuously extruding tube bundle, and extruded tube bundle so formed - Google Patents

Abstract

A method is provided for continuously extruding a tube cluster. The method include providing a die having a hollow central core and a radial inflow passage leading to an axial annular outflow passage which is concentrically disposed around the hollow central core. The procedural steps of the method comprise continuously passing a t least two synthetic thermoplastic preformed tubes, preferably of different colored syn thetic thermoplastic material longitudinally through the hollow central core. Substantially-simultaneously, a melt of a compatible synthetic thermoplastic mat erial is extruded through the radial inflow passage to provide a continuously extruded tube surrou nding the hollow central core. The speed of the extrusion is correlated to the speed o f the longitudinal passing of the preformed tubes to provide a longitudinally-extendin g surface of each of the preformed synthetic thermoplastic tubes in contact with the extru ded tube. This provides a continuous pipe cluster unit comprising at least two, preferably differently colored pre-formed tubes, at least a longitudinally-extending, perip heral portion of each said preformed tube bag, being in fused longitudinally-extending contact with a longitudinally-extending inner wall of the extruded outer tube. The extru ded pipe cluster unit is a flexible extruded entity of infinite indefinite length.

Description

. 1 (a) TITLE OF THE INVENTION
Method for Continuously Extruding Tube Bundle, and Extruded Tube Bundle So Formed (b) TECHNICAL FIELD TO WHICH THE INVENTION RELATES
This invention relates to a method for continuously extruding a tube cluster unit, and to the continuously-extruded tube cluster unit so produced.

(c) BACKGROUND ART
Tube cluster units are now available where the individual tubes are, after they are 10 manufactured, combined into a tube cluster unit such that at least two adjoining tubes are in a longitudinal linear engagement with one another. In such prior art, the tubes are first fabricated and wound on drums, for transportation to a site. In order to form the tube bundle, such tubes are fed off the drums and then assembled so that a compact configuration of the assembly of tubes is formed, i.e., the tubes are fastened together into 15 a tube bundle. To affix the tubes in the tube bundle, ~rapping was provided around the tubes. Alternatively, the tubes could be formed with connecting elements at their peripheries, so that the tubes of the array can interfit or interlock. The tubes were composed of polyethylene or polyvinylchloride.
One problem with such tube assemblies was that the individual plastic tubes did 20 not fit together or define complementary structures in which other tubes could nest in a fully satisfactory manner. As a consequence, in the prior art structures, the tube bundle was frequently protected by an outer tube or sheath.

In an attempt to solve such problem, it has been proposed to form a tube bundle from a multiplicity of plastic tubes which have modified triangular cross-sections such that the vertices of these cross-sections, corresponding to the edges defined between sides of the tube are greatly rounded. This has not been entirely successful since substantial Sfree space was provided by reason for the considerable rounding of the triangle corners.
These free spaces effectively become dead spaces.
Problems were also encountered with this system in the coiling of the extruded product because the modified triangular shapes of the tubes provided a significant resistance to the coiling operation. Furthermore, in the coiling and uncoiling undesirable 10modifications of the cross-section of the tubes could occur.
Another solution to such problem was provided by a tube cluster which was formed of a plurality of individual tubes which were combined into a mat by means of spacer webs which formed integral, one-piece parts of the tubes. The spacer webs were flexible and were said to permit a relative positioning among the individual tubes such 15that the adjoining pipes were longitudinally in a linear contact with one another. In such prior art structure, no firm bond of the tubes in the cluster was provided.
It is known to jacket a unit which was comprised of a plastic jacket and a core which was sensitive at the extrusion temperature of the jacket by an extrusion of the jacket. Known processes for carrying out these jacketing operations are adapted to carry 20out the jacketing of a single core. In order to cover several different (or identical) cores with the same jacketing material, it was necessary to stop the extrusion of the jacket in 21 90q35 order to clean, or indeed change, the die. It may also be necessary to stop the jacketing operation to modify the parameters of the extruder and of the attached equipment.
In the field of plastics, it is desirable to produce internally sub-divided tubular bodies for, e.g., providing several inner conduits for pumping diverse fluids there-through, etc. Continuous extrusion of such types of tubing has not been possible given the present state of the art in nozzles.
The patent literature provides methods and apparatus for the formation of multiple duct conduits which are similar to, but not adapted for the same purpose as, the extruded tube cluster of this invention. Among them are the following patents:
U.S. Patent No. 1,873,445 patented August 23, 1932 by William McClintock et al provided an apparatus for making interlocking multiple duct conduits. That apparatus included a former plate, and a plurality of core members which were attached to the plate in spaced relation and spaced from the edge of the plate. A flange peripherally extended from the former plate. Spaced air inlet valves were provided in the edge of the former plate. A lip extended in a plane parallel to the plane of the former plate.
U.S. Patent No. 4,273,070 patented June 16, 1981 by Tilman Hoefelmayr, provided a milking hose, which had four elongated, flexible conduits. Two conduits were connected to one another along a first common connecting segment, which extended parallel with respect to the longitudinal axis of the hose. The two other conduits were each arranged on opposite sides of the first connecting segment of the two first conduits and extend parallel therewith and are each connected to the two first conduits along a second and third, and fourth and fifth connecting segment.

2 1 90935 U.S. Patent No. 4,553,573 patented November 19, 1985 by Robert McGarrah, provided a bulk syrup delivery system utili~ing a multi-channel delivery concept for the bulk delivery of a plurality of different flavored syrups. The bulk delivery system included a compartmentized tank delivery truck having a plurality of separate compartments thereon for the storage and delivery of a plurality of different flavored syrups. A multi-channel delivery hose was coupled to the plurality of separate compartments on the delivery truck, such hose having at least one channel for each different flavored syrup. A multi-channel delivery coupling was provided at a delivery end of the multi-channel delivery hose. The delivery coupling had a plurality of closure valves therein, one for each channel in the delivery coupling.
U.S. Patent No. 4,709,730 patented December 1st, 1987 by Hermann Zwilling, provided a pipe cluster unit, in which the pipes were in longitudinal, linear contact with one another. Outer wall portions of the individual pipes, which were spaced from the mutual contact regions between the pipes were provided with an adhesive or an adhesion-enhancing substance or were pre-treated by heating. A pipe cluster unit was then formed by applying a heated plastic cover layer on the pre-treated wall portions, thus firmly bonding adjoining pipes to one another. Immediately thereafter the heated cover layer was cooled and, by utili7ing its propellies of ~hrink~ge, it was pressed additionally onto the pre-treated wall portions of the individual pipes.
U.S. Patent No. 4,975,055 patented December 4, 1990 by Pierre LaPlante, provided a flexible conduit structure for dental appliances, which included a conduit which was formed of a cluster of at least three tubes which were connected by webs 2 1 90q3s extending between adjacent pairs. The tubes and webs were formed by simultaneousextrusion of a suitable plastic through a suitable die. The outer surface of each of the webs was convexly curved in an arc. The inner surface of each of the webs was flat relative to the outer surface but formed a chord of such arc.
U.S. Patent No. 5,036,891 patented August 6, 1991 by Horst Vogelsang, provided a conduit bundle for in-ground cabling, which had a multiplicity of plastic tubes with outer polygonal cross-sections having more than three sides. The tubes wereconnected with webs which were flexible and were so oriented that they were linearly-aligned in an open array of the tubes so that the tubes were coplanar and could be coiled onto a drum or uncoiled from a drum. The cable assembly could be fabricated as a unit by extrusion. As taught, the tubes were unitarily formed with one another and with the respective webs in one piece by extrusion of the thermoplastic material through a suitably-shaped extrusion die.
U.S. Patent No. 5,063,018 patented November 5, 1991 by Carlos A. Fontirroche et al provided an extrusion method for forming a multiple lumen tubing. An inner tube of molten plastic was extruded about a metallic, bore-forming mandrel wire. An outer tube of molten plastic was extruded having a lumen formed by air mandrel means, was extruded around the inner tube. The inner and outer tubes were bonded together by means of a mandrel which was positioned in an extrusion die. The mandrel defined a distal end portion positioned and shaped to form a lumen in the tubing, and an air flow passage extending through the mandrel to provide an air mandrel to the newly-formed lumen to prevent its collapse.

.

U.S. Patent No. 5,236,016 patented August 17, 1993 by Horst Vogelsang, provided a cable-guide assembly of plastic tubes joined by webs. That cable guide assembly consisted of three tubes which were extruded simultaneously with the connecting webs and which abutted at hexagonal segments form with two angularly adjoining surfaces. A subsequently applied sealing strip, or a sealing strip which was formed on one of the tubes which was not interconnected by a connecting web bridged between the two tubes which were not interconnected by such webs when the bundle was formed.
U.S. Patent No. 5,249,945 patented October 5, 1993 by Raymond Bourdon, provided an apparatus for covering at least two cores with the same jacketing material, by passing the cores through respective dies of a plate, while flowing the jacketing material through sub-channels in the plate and into coating relationship with the cores.
U.S. Patent No. 5,305,797 patented April 26, 1994 by John D. Roy, Sr., provided a compartmented conduit tube construction. The conduit tube included intersecting partition walls dividing the associated conduit tube into four compartments to permit transport and positioning of cable within each col~.pallment in a discrete relationship. The first and second ends of the conduit tube included locking blades, with each locking blade arranged for reception within an associated slot of a second tube member to secure a plurality of the conduit tubes together.
U.S. Patent No. 4,450,703 patented September 19, 1995 by Michael J. Furhman et al, provided frame structures formed of double tube components. Such structure was formed by one or more double tube assemblies having a cross-sectional configuration 21 90~35 ..

which includes two circular walls interjoined by two planar walls interconnected with the circular walls substantially at diametrically opposed circumferential locations in the circular walls.
C~n~ n Patent No. 849,984 issued August 25, 1970 to Ronald Campbell provided an extrusion apparatus which included a particular die comprising a convergent die bush shaped to impart the required cross-sectional shape to the extrusion. A pin carrier was positioned at the entry end of the die bush, and a plurality of flexible pins were provided, each such pin being anchored in the pin carrier against movement in the direction of flow of the extrusion. The convergence of the die bush permitted a stable plastic flow pattern to be set up throughout the whole cross-section of the die.C~n~ n Patent No. 945,585 issued April 16, 1974 to Clarence H. Elder et al, provided joints for special types of multi-tubular conduits. A first body member included a planar section. Extensions from the first body member had inner surface thereon defining frusto-conical sections in the ducts at the ends thereof adjacent the bell end.
Extensions from a second body member had inner surfaces defining frusto-conical sections in the ducts at the ends thereof adjacent the spigot end. Sealing means were disposed between the bell and spigot sections whereby the ducts were sealed against the ingress of water or the like.
C~n~ n Patent No. 970,296 issued July 1, 1975 to Donald L. ~nning, provided an extruded conduit bundle and mounting means therefor. Such extruded conduit bundle had a plurality of fluid passages defined by tubular portions connected by integrally-extruded webs extending therebetween. A pair of integrally-extruded legs 21 90~35 extended from the conduit bundle and were flanged inwardly toward one another toprovide a continuous slot opening into a cavity. The conduit bundle was attached to a vehicle body by well-nuts which were inserted through a hole in the body and through the slot into the cavity of the conduit bundle. A bolt screwed into the well-nut spread the nut radially to engage the flanges of the legs against the vehicle body.
C~n~ n Patent No. 984,314 issued February 24, 1976 to Herved Book, provided a heat transfer channel, which consisted of an outer prefabricated protective coating of plastics. Inside the protective coating, one or more tubular channel tubes were embedded in polyurethane foam which filled the space between the protective coating and the outer surfaces of the channel tubes.
C~n~ n Patent No. 1,213,837 issued November 12, 1986 to Hermann Zwilling, provided a process for manufacturing bundled pipe assembly, in which a plurality of pipes were gathered into a cluster in which the pipes were in longitll~in~l, linear contact with one another. Outer wall portions of the individual pipes, which were spaced from the mutual contact regions between the pipes, were provided with an adhesive or an adhesion enhancing substance or were pre-treated by heating. A pipe cluster unit was subsequently formed by applying a heated plastic cover layer on the pre-treated wall portions, thus firmly bonding adjoining pipes to one another. Immediately thereafter, the heated cover layer was cooled and, by utili7ing its properties of shrinkage, it was pressed additionally onto the pre-treated wall portions of the individual pipes.
C~n~ n Patent No. 1,258,038 issued August 1, 1989 to Ragnar Bognaes, provided a pipeline cable for use under water. The pipeline cable included a number of 21 90~35 individual rigid pipelines with filler m~tçri~l around and between the pipelines. A
protective sheath surrounded the pipelines and filler material. A core of filler m~tçri~l received at least some of the pipelines.
C~n~ n Patent No. 1,265,910 issued February 20, 1990 to Guillermo Zertuche, provided a method and appa alus for extruding tubular articles having several inner conduits. The patent provided a method of extruding tubular shapes having inner walls forming separate conduits comprising feeding a continuous flow of m~t~ri~l through a converging zone in a nozzle, the nozzle having several interconnected recesses and air supply conduits located within a confining die for shaping the continuous flow of m~trri~l.

(d) DESCRIPTION OF THE INVENTION
While the above patents provide techniques for the production of pipe clusters, no patent taught the continuous extrusion of a pipe cluster unit which consisted of a plurality of differently-colored internal pipes within a single sheath.
Accordingly, an object of one aspect of this invention is to disclose a method for producing an extruded tube bundle.
An object of another aspect of this invention is to provide an improved tube cluster unit and a method of making the same in which, without the aid of mechanical connecting members, the individual pipes of the cluster are bonded firmly within an outer enclosing pipe.
By the present invention, a method is provided for continuously extruding a tubecluster, the method comprising: providing a die having a hollow central core and a radial 21 90~35 -inflow passage leading to an annular channel which is concentrically disposed around the hollow central core; continuously passing at least two pl~fol.lled tubes of different colored synthetic thermoplastic materials longitudinally through the hollow central core, continuously extruding a melt of the same synthetic thermoplastic material through the 5 radial inflow passage to provide a continuously extruded tube surrounding the hollow central core, the speed of extrusion being correlated to the speed of the longitudinal passing of the pr~fol-lled tubes to provide a longitl1(1in~11y-extending surface of each of the preformed synthetic thermoplastic tubes in contact with the extruded outer tube as it is formed, thereby providing a continuous tube cluster units comprising at least two 10 differently colored preformed tubes at least a longitudinally-extending peripheral portion of each such plefol,lled tube being in fused, longitll~in~lly-extending contact with the longitudinally-extending inner wall of the extruded outer tube, the extruded pipe cluster unit being a flexible extruded entity of long continuous length.
By a variant of this invention, the synthetic thermoplastic is polyethylene or 15 polyvinylchloride.
By another variant of the invention, the preformed tubes are differently colored.
By variants of the invention, three preformed tubes of the same diameter or of different diameters are used.
By another variant of the invention, four preformed tubes of the same diameter 20 or of different diameters are used.

21 90~35 By a variant of the product of this invention, the synthetic thermoplastic is polyethylene or polyvinylchloride, especially where the preformed tubes are differently colored.
The present invention in another aspect also provides an extruded continuous tube S cluster unit comprising at least two differently colored pleroll-led tubes in fused, longitu-lin~lly-extending contact with a longitu-lin~lly-extending, inner wall of the extruded outer tube, the extruded tube cluster unit being a flexible, extruded entity of indefinite continuous length.
By another variant of the product of aspects of this invention, the three preformed tubes of the same diameter or of different diameters are used.
By another variant of the product of aspects of this invention, four plt;folllled tubes of the same diameter or of different diameters are used.
The tube cluster unit produced according to one method of the present invention may include two, three or more plefo.llled tubes and may include tubes having different diameters. With the method according to the invention tube cluster units containing either an even number of preformed tubes or an odd number of preformed tubes may be made.
It is an essential feature of the method according to the invention that external longitudinally-extending wall surfaces of the individual plerolllled tubes be fused to the newly-extruded inner wall of the outer tube.
The outer wall surfaces of the individual prero-llled tubes are heated by the molten extruded thermoplastic m~t~ri~l as it is being formed into the outer tube, which 21 90~35 provides a subsequent plastic welding or fusion process. Such a heating is thus effected simultaneously with the extrusion of the molten synthetic plastic material, whereby the outer tube encasing the individual p~erof-l~ed tubes is formed by the plastic material. The individual preformed tubes may further be connected with one another in the immediate vicinity of the longitudinally-extending line of contact between the prefollned tubes.
It is further of significance that immediately after bonding the adjoining preformed tubes to one another by the heated molten thermoplastic outer tube, that extruded outer tube is cooled. Thus, the ~hrink~ge of the outer tube is so utilized that it exerts a pressure on the wall portions of the individual pipes. In this manner, the tube cluster unit formed of the individual-formed tube connected with one another by the outer conduit is additionally strengthened without reducing the flexibility of the tube cluster unit.

(e) DESCRIPTION OF THE FIGURES
In the accompanying drawings, Fig. 1 is a longitudinal, cross-section of a die for continuously extruding the tube cluster of this invention;
Fig. 2 is a cross-section of one embodiment of the tube cluster of this invention;
and Fig. 3 is a cross-section of a second embodiment of the tube cluster of this invention.

(f) ONE MODE FOR CARRYING OUT THE INVENTION
Fig. 1 shows one embodiment of a die 100 which can be used to provide the tube cluster of embodiments of this invention. The die 10 comprises a hollow metal core which is a cylindrical die element 13 which is constituted by a radial inflow passage 14, which communicates with an axial annular chamber 15, which is defined by outer axial wall 16 of the cylindrical die element, and inner axial wall 17 of the tubular portion 11.
Axial annular chamber lS includes annular axial outflow passage 18. When a thermoplastic synthetic plastic is fed into the radial inflow passage it is extruded outwardly through the annular axial outflow passage to provide a continuously-formed outer tube 19.
As seen in Fig. 2, the extruded tube bundle 200 includes an outer extruded tube 19 encases preformed tubes 20, 21, 22. Rec~llse of the heat during the extrusionprocess, longit~l~in~lly-extending peripheries 23,24,25 of prefollned tubes 20,21,22 respectively, are fused to internal longitudinally-extending position of outer tube 19 at peripheries 23,24,25. Furthermore, because of the shrink~ge of the extruded tube 19 as it cools, longitudinally-extending other peripheral areas of preformed tubes 20,21,22 are pressed into tight eng~ging contact with one another at region 26,27,28.
As seen in Fig. 3, the extruded bundle 300 includes an outer extruded tube 19 encases four preformed tubes 30,31,32,33. Because of the heat during the extrusion process, longitudinally-extendingperipheries 34,35,36,37Ofpreformed tubes 30,31,32,33 respectively, are fused to internal longitudinally-extending position of outer tube 19 at peripheries 34,35,36,37. Furthermore, because of the ~hrink~ge of the extruded tube 19 as it cools, longitudinally-extending other peripheral areas of prefo..lled tubes 30,31,32,33 are pressed into tight eng~ging contact with one another at regions 38,39,40,41.
In order to produce the extruded tube bundle (200,300) a die 100 may be used.
Such die, as previously described, has a hollow central core and a radial inflow passage leading to an annular channel which is concentrically disposed around the hollow central core. The method includes continuously passing at least two preformed tubes (e.g., three to produce bundle 200 or four to produce bundle 300), of different colored synthetic thermoplastic materials longitudinally through the hollow central core. Substantially-simultaneously, a melt of the same synthetic thermoplastic material is continuously extruded through the radial inflow passage to provide a continuously extruded tube surrounding the hollow central core. The speed of the extrusion is correlated to the speed of the longitll(lin~l passing of the preformed tubes to provide that a longitudinally-extending surface of each of the prefo~ ed synthetic thermoplastic tubes is in contact with an internal surface of the extruded tube.
Because of the heat inherent during the extrusion process, longitudinally-extending peripheries of preformed tubes are fused to internal longitudinally-extending portions of outer tubes at such peripheries.
Furthermore, because of the shrinkage of the extruded tube as it cools, longitll-lin~lly-extending other peripheral areas of plefo----ed tubes are pressed into tight eng~ging contact with one another at contacting regions.

21 qoq35 This method thus provides a continuous tube cluster unit comprising at least twopreferably differently colored pleforllled tubes in fused longitudinally-extending contact with the longitudinally-extending inner wall of the extruded outer tube. The extruded tube cluster unit is a flexible extruded entity of long indefinite length.

Claims (14)

(g) CLAIMS
I Claim

1. A method for continuing extruding a tube cluster, said method comprising:
providing a die having a hollow central core and a radial inflow passage leading to an annular axial outflow passage which is concentrically disposed around said hollow central core;
continuously passing at least two preformed, synthetic thermoplastic tubes longitudinally through said hollow central core;
substantially-simultaneously continuously extruding a melt of a compatible synthetic thermoplastic material through said radial inflow passage to provide a continuously-extruded outer tube through said axial outflow passage surrounding said hollow central core;
the speed of the extrusion being correlated to the speed of longitudinal passing of said preformed tubes to provide a longitudinally-extending surface of each of said preformed synthetic thermoplastic tubes in contact with the extruded tube, thereby providing a continuous tube cluster unit comprising at least two preformed tubes, at least a longitudinally-extending peripheral portions of each said preformed tube bag in fused longitudinally-extending contact with a longitudinally-extending inner wall of said extruded outer tube, said extruded tube cluster unit being a flexible extruded entity of long indefinite length.

2. The method of claim 1 wherein said synthetic thermoplastic is polyethylene or polyvinylchloride.

3. The method of claim 1 wherein said preformed tubes are differently colored.

4. The method of claim 1, claim 2, or claim 3 wherein three preformed tubes of the same diameter are used.

5. The method of claim 1, claim 2, or claim 3, wherein three preformed tubes of different diameters are used.

6. The method of claim 1, claim 2, or claim 3, wherein four preformed tubes of the same diameter are used.

7. The method of claim 1, claim 2, or claim 3, wherein four preformed tubes of different diameters are used.

8. An extruded continuous tube cluster unit comprising at least two preformed tubes, at least a longitudinally-extending peripheral portions of each said preformed tube being in fused longitudinally-extending contact with a longitudinally-extending inner wall of said extruded outer tube, said extruded tube cluster unit being a flexible extruded entity of long indefinite length.

9. The extruded continuous tube cluster of claim 8 wherein said synthetic thermoplastic is polyethylene or polyvinylchloride.

10. The extruded continuous tube cluster of claim 8 or claim 9, wherein said preformed tubes are differently colored.

11. The extruded continuous tube cluster of claim 8, claim 9, or claim 10, wherein three preformed tubes of the same diameter are used.

12. The extruded continuous tube cluster of claim 8, claim 9, or claim 10, wherein three preformed tubes of different diameters are used.

13. The extruded continuous tube cluster of claim 8, claim 9, or claim 10, wherein four preformed tubes of the same diameter are used.

14. The extruded continuous tube cluster of claim 8, claim 9, or claim 10, wherein four preformed tubes of different diameters are used.