AMENDED CLAIMS [Received by the International Bureau on 24 April 2003 (24.04. 03); original claims 1-35 replaced by amended claims 1-48 (11 pages)]

1.

An extruded composite structure comprising at least one axially elongated, substantially rigid inner cylindrical member having an outwardly directed wall, at least one axially elongated, substantially rigid outer tubular member, having an inwardly directed wall directed toward and spaced from said outwardly directed wall, and a plurality of substantially rigid struts disposed in at least part of the annular space between the inwardly and outwardly directed walls; wherein at least some of said struts are joined to both said inwardly and outwardly directed walls along a sufficient portion of the axial length of said walls to maintain a predetermined spacing between said walls; wherein at least some of said struts are altematingly disposed at opposite angles, other than perpendicular, with respect to said inwardly directed and said outwardly directed walls; wherein said composite structure has an outside diameter that is not substantially greater than the outside diameter of a fluid form extrudate comprising said inner cylindrical member, said outer tubular member and said angularly disposed struts in contact with both said inwardly directed wall and said outwardly directed wall; and wherein said inner cylinder and said outer tubular member as well as said angularly disposed struts are twisted, so as to have an alignment that has longitudinal and a circumferential components, wherein said alignmentis fixed into said composite structure by passing said twisted moldable extrudate through a cooling zone along a predetermined path that corresponds to said alignment.

2.

Canceled.

3.

A composite tube as claimed in claim 1 wherein at least some of said struts are simultaneously contacted with and adhered to said inwardly directed and said outwardly directed walls, respectively, at location (s) that are spaced from the location where the next adjacent struts are contacted with and adhered to said inwardly and outwardly directed walls, respectively, so as to form generally longitudinal/circumferential strutdefining cells having a substantially trapezoidal cross section.

4.	A composite tube as claimed in claim 3 wherein all of said struts are angularly disposed at alternating positive and negative angles away from normal with respect to said inwardly and outwardly directed walls.

5.	A composite tube as claimed in claim 1 wherein all of said struts extend the entire longitudinal length of said composite tube.

6.	A composite tube as claimed in claim 1 wherein said inner cylinder is a hollow tube.

7.	A drainage pipe comprising a plurality of composite tubes as claimed in claim 6 joined together end to end.

8.	A drainage pipe as claimed in claim 7 having at least one perforation in at least one of said tubular members.

9.	A drainage pipe as claimed in claim 7 wherein said composite tubes are joined together end to end.

10.	A composite tube as claimed in claim 6, further comprising at least one hole through said outer tubular member.

11.	A composite tube as claimed in claim 6, further comprising a plurality of holes through said inner and outer tubular members, said holes being positioned such that a volume inside said inner tubular member is adapted to communicate with a volume outside said outer tubular member.

12.	A pipe comprising a plurality of joined together composite tubes as claimed in claim 11.

13.	A septic field comprising a plurality of composite tubes as claimed in claim 11.

14.	A septic field comprising a plurality of composite tubes as claimed in claim 11, wherein said composite tubes are joined together end to end.

15.

A method of draining underground water comprising burying at least one composite tube as claimed in claim 11 proximate to a source of said water and in a position adapted to permit said water to drain by gravity and in a condition adapted to cause underground water to seep into said inner tube through said holes, and providing an outlet for said composite tube.

16.

A method of making a composite cylindrical structure, comprising an outer tubular member, an inner cylindrical member and a plurality of struts disposed in an annular space therebetween in spacing and supporting relationship to said inner cylindrical member and said outer tubular member, said method comprising: extruding a cylindrical profile extrudate, having an outer cross sectional dimension, of moldable material comprising, as the extrudate, said inner cylindrical member, said outer tubular member and at least some of said struts in spacing and supporting contact with said inner cylindrical member and said outer tubular member; while in a moldable condition, causing said extrudate to be twisted circumferentially and pulled down stream; passing said extrudate through a cooling zone, along a twisting path that has longitudinal and circumferential directional components that substantially correspond to a rate of circumferential twisting and a rate of down stream pulling, and cooling said structure an amount sufficient to solidify said inner cylindrical member, said outer tubular member, and said struts in said twisted orientation; downstream of said cooling step, drawing said solidified composite structure downstream while simultaneously twisting it so as to cause said molten extrudate, at a location between said extrusion and said cooling, to be pulled downstream and twisted, whereby causing said structure to become oriented in both longitudinal and circumferential directions prior to cooling/solidifying it; and carrying out said method under conditions such that the outer cross sectional dimension of said solid product is not substantially larger than the outer cross sectional dimension of said molten extrudate.

17.

A method as claimed in claim 16 wherein said inner cylindrical member is tubular and further comprising drawing said inner tubular member over a cooling mandrel and through a cooling sleeve under conditions sufficient to cool and solidify said extrudate from the inside as well as from the outside, wherein said method further comprises passing said extrudate along a path through said cooling zone that has both longitudinal and circumferential components.

18.	A method as claimed in claim 17 further comprising cooling and solidifying said inner tubular member, said outer tubular member and said struts at substantially the same time.

19.	A method as claimed in claim 17 further comprising cooling said outer tubular member by spraying cooling water on an outwardly directed surface thereof.

20.	A method as claimed in claim 17 further comprising drawing a vacuum through apertures in said mandrel an amount sufficient to cause an inwardly directed surface of said inner tubular member to maintain close proximity to said mandrel.

21.

A method as claimed in claim 20 further comprising intermittently releasing said vacuum whereby permitting said inwardly directed surface to move away from said mandrel for a period of time that is sufficient to prevent said inwardly directed surface from adhering to said mandrel during said cooling operation.

22.	A method as claimed in claim 16 further comprising pulling and twisting said solidified extrudate an amount sufficient to form said molten extrudate into a substantially helical orientation before it is fully solidified, and solidifying said twisted molten extrudate in said helical configuration.

23.

A method as claimed in claim 22 wherein said inner cylindrical member is tubular and further comprising pulling and twisting said solidified extrudate such that said cooling extrudate follows a helical path about a cooling mandrel, and rotating said mandrel at a sufficient speed and direction to adjust the rotational speed of said inner tubular member relative to the rotational speed of said outer tubular member such as to cause said struts to not substantially deform prior to and during cooling.

24.

A method as claimed in claim 16 further comprising twisting and pulling said solidified extrudate by closely contacting a plurality of driven belts about an outwardly directed surface of said outer tubular member; wherein different of said belts encounter said outwardly directed surface from different positions such that bending of said composite article is minimized; and driving said belts at a speed sufficient to cause said extrudate to be twisted circumferentially.

25.	A method as claimed in claim 24 further comprising contacting all of said belts with said tubular article at different positions.

26.	A method as claimed in claim 24 further comprising contacting at least some of said belts with said tubular article at complementary positions.

27.	A method as claimed in claim 24 further comprising adjusting the length of said belts to compensate for a change in the diameter of said tubular article.

28.	A method as claimed in claim 16 further comprising feeding said moldable material to said extruder die from a plurality of feed locations disposed about the periphery of said extruder die.

29.	A method as claimed in claim 28 further comprising feeding said moldable material to said extruder die from a plurality of feed locations substantially equally spaced about the periphery of said extruder die.

30.

A method as claimed in claim 28 further comprising: A. subdividing a feed of said moldable material into a plurality of first feed streams; B. subdividing at least some of said plurality of first feed streams into a plurality of second feed streams C. repeating step B a sufficient number of times to produce a plurality of feed streams each of which has a substantially smaller volume than said feed; and D. feeding the product of step C substantially evenly distributed about the periphery of an extrusion die.

31.

A method of transversely cutting a composite tubular body as claimed in claim 16 comprising: circumferentially applying a"v"shaped cutter about said composite tube, whereby cutting a "v"groove partially through said composite tube and leaving a web of uncut tubular material; and thereafter, in a separate step, cutting all the way through the web of tubular material.

32.

A method as claimed in claim 31 further comprising: axially rotating said tubular body while longitudinally progressing said body; causing said"v"cutter to move longitudinally at substantially the same speed as said cylindrical body is longitudinally progressing: and rotating said"v"cutter while pressing it into said rotating cylindrical body while rotating said"v"about said cylindrical body; and pressing said"v"cutter into said rotating cylindrical body whereby said rotation of said"v" cutter causes said"v"cutter to cut a"v"groove in said cylindrical body.

33.	A method as claimed in claim 21 further comprising, during release of said vacuum, and applying an overpressure of air through at least some of said apertures in an amount and at a velocity sufficient to cause said inwardly directed surface to move away from said mandrel.

34.

A method of producing a composite tubular article which comprises: A. feeding a moldable material through an extrusion die to form a molten extrudate having a more inward tubular member, at least one spaced apart more outward tubular member, and a plurality of struts extending between said more inward tubular member and a next adjacent more outwardly spaced apart tubular member; B passing said molten extrudate through a cooling zone under conditions sufficient to substantially cool said extrudate and form a solidified extrudate ; C. pulling said solidified extrudate in a downstream direction while simultaneously twisting the solidified extrudate ; whereby causing said molten extrudate to be twisted circumferentially and be pulled downstream into cooling relation with said cooling zone; whereby causing said extrudate to traverse said cooling zone along a path that has both longitudinal and circumferential components and substantially corresponds to the degree of twisting and downstream pulling imparted to said extrudate ; and D. while said tube is progressing downstream along a path having longitudinal and circumferential vectors, cutting said tube into discrete lengths.

35.	A method as claimed in claim 34 further comprising forming the opposite ends of at least some of said discrete lengths of tubing into male and mating female profiles, respectively.

36.	A composite tube as claimed in claim 1 in the form of a monolith.

37.	A method as claimed in claim 16 wherein said struts are joined to said outer tubular member and said inner cylindrical member, respectively, only as they are being extruded.

38.

An extruded composite structure as claimed in claim 1 wherein at least some of said alternatingly angularly disposed struts are simultaneously contacted with and adhered to said inward cylindrical member and said outwardly directed tubular member, respectively, at location (s) that are adjacent to the location where a next adjacent strut is contacted with and adhered to said inward cylindrical member and said outwardly directed tubular member, respectively, whereby said next adjacent, angularly disposed struts together with the portion of respectively intercepted inwardly directed or outwardly directed walls of said tubular member and said cylindrical member, respectively, define cells having a substantially triangular cross section.

39.

An extruded structure as claimed in claim 1 wherein at least some of said alternatingly angularly disposed struts are simultaneously contacted with and adhered to said inward cylindrical member and said outwardly directed tubular member, respectively, at location (s) that are proximate to but not in contact with a next adjacent strut where said next adjacent strut is contacted with and adhered to said inward cylindrical member and said outwardly directed tubular member, respectively, whereby said next adjacent, angularly disposed struts together with the portions of respectively intercepted inwardly directed and outwardly directed walls of said tubular member and said cylindrical member, respectively, define cells having a substantially trapezoidal cross section.

40.

Apparatus for forming a cylindrical structure, wherein said structure comprises an inner cylindrical member, an outer tubular member and a plurality of struts, disposed in an annular space between said inner and outer members, respectively, in spacing and supporting relationship to said members; which apparatus comprises: an extruder adapted to simultaneously extrude a molten extrudate comprising said inner cylindrical member, said outer tubular member spaced from said inner cylindrical member, and a plurality of said spacing and supporting struts ; a cooling means disposed downstream of said extruder, comprising a path adapted to be followed by said molten extrudate during said cooling, wherein said cooling means is adapted to convert said molten extrudate to solid extrudate ; and pulling and twisting means downstream of said cooling means, and comprising means to twist said solid extrudate in a circumferential direction and means to pull said solid extrudate in a downstream, longitudinal direction; wherein said pulling and twisting means is adapted to cause said molten extrudate to be twisted into a product configuration having a circumferential component and a longitudinal component; and wherein said path is adapted to cause said molten extrudate to pass through said cooling zone along a path that is consistent with the twisted configuration of said product.

41.	The apparatus as claimed in claim 40 wherein said path is a substantial helix.

42.	The apparatus as claimed in claim 40 wherein said pulling and twisting means are a single means enabling said pulling and twisting to be accomplished substantially simultaneously.

43.

The apparatus as claimed in claim 40 wherein said inner member is tubular and wherein said cooling means further comprises: a cooling mandrel adapted to fit within said inner tubular member; a cooling sleeve adapted to substantially surround said outer tubular member; means to apply cooling from said mandrel in an amount sufficient to solidify at least said inner tubular member and at least a portion of said struts that are proximate to said inner tubular member ;. and means to apply cooling from said sleeve in an amount sufficient to solidify at least said outer tubular member and at least a portion of said struts that are proximate to said outer tubular member.

44.	The apparatus as claimed in claim 43 wherein said mandrel is tapered in a downstream direction and said taper is at an angle that corresponds to an amount of shrinkage that said inner tubular member will realize in passing through said cooling zone.

45.

The apparatus as claimed in claim 43 wherein said mandrel comprises apertures in a surface that is adapted to be proximate to said inner tubular member and further comprising vacuum drawing means operatively associated with said apertures in an amount sufficient to maintain said inner tubular member in close proximity to said cooling mandrel during said cooling.

46.	The apparatus as claimed in claim 45 further comprising means to periodically relieve said vacuum at a frequency such that said inner tubular member will not permanently adhere to said mandrel.

47.	The apparatus as claimed in claim 46 further comprising means to intermittently release said vacuum and exert gas pressure through said apertures in an amount and frequency such as to cause said inner tubular member to move away from said mandrel.

48.	The apparatus as claimed in claim 40 further comprising cutting means adapted to cut said solidified product while said product is moving longitudinally and turning circumferentially.