CA1209493A - Flexible tubing and apparatus for and method of manufacturing same - Google Patents
Flexible tubing and apparatus for and method of manufacturing sameInfo
- Publication number
- CA1209493A CA1209493A CA000440447A CA440447A CA1209493A CA 1209493 A CA1209493 A CA 1209493A CA 000440447 A CA000440447 A CA 000440447A CA 440447 A CA440447 A CA 440447A CA 1209493 A CA1209493 A CA 1209493A
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- core
- coating
- thermoplastic material
- tubing
- reinforcing material
- Prior art date
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Abstract
Abstract of the Disclosure Reinforced flexible tubing of thermoplastic material is provided. The tubing includes a tubular core of thermo-plastic material having on the outer surface thereof a multi-plicity of contiguous formations integral with the core, the formations defining valleys therebetween, reinforcing material disposed on the outer surface of the core in intimate contact with the surface of the core and a coating of thermoplastic mate-rial covering the outer surface of the core and the reinforcing material, the thermoplastic material of the coating being directly and intimately bonded to the thermoplastic material of the core. Also provided is an apparatus for manufacturing rein-forced flexible tubing of thermoplastic material. The apparatus includes a core supply for supplying a flexible tubular core, a reinforcing material supply device for supplying reinforcing material to the outer surface of the core and an extruder arranged to extrude a coating of thermoplastic material onto the outer surface of the core and the reinforcing material, the extruder being adapted to enable a positive air pressure differ-ential to be applied between the exterior and interior of the coating around the core during extrusion of the coating.
further provided is a method for manufacturing reinforced flex-ible tubing of thermoplastic material which includes providing a flexible tubular core of thermoplastic material, supplying rein-forcing material to the surface of the core and extruding, by means of an extruder, a thermoplastic coating on the outer sur-face of the tubular core and the reinforcing material while creating a positive air pressure differential between the exterior and interior of the coating in the extruder during extrusion to urge the coating into intimate contact with the core and the reinforcing material. The reinforced tubing of the invention permits a reduction of up to 30° of the material used to form the coating while maintaining the resistance to bursting.
further provided is a method for manufacturing reinforced flex-ible tubing of thermoplastic material which includes providing a flexible tubular core of thermoplastic material, supplying rein-forcing material to the surface of the core and extruding, by means of an extruder, a thermoplastic coating on the outer sur-face of the tubular core and the reinforcing material while creating a positive air pressure differential between the exterior and interior of the coating in the extruder during extrusion to urge the coating into intimate contact with the core and the reinforcing material. The reinforced tubing of the invention permits a reduction of up to 30° of the material used to form the coating while maintaining the resistance to bursting.
Description
~ 2~ g 49 3 4319-47 FLEXIBLE TUBING AND
METHOD OF MANUFACTURING SAME
Background of the Invention Field of the Invention The present invention relates to reinforced flexible tubing of thermoplastic material and, more particularly, to rein-forced flexible tubing having high resistance to bursting.
The present invention also relates to a method of manu-facturing flexible tubing of thermoplastic material.
Description of the Prior Art It is known to form a plastic tube, for example, by extrusion through a circular die, to reinforce that tube by applying a reinforcing material such as a textile or a metallic material, normally in braid or lap form, over the exterior sur-face thereof, and to apply a second (outer) tube, generally by extrusion over the inner tube of the reinforcing material. Pre-ferably, the outer tube is applied over the inner tube and the reinforcing material while the inner tube is still warm from its own formation, which is generally by extrusion, so that the mate-rials of the inner and outer tubes can blend together and trap the reinforcing material therebetween. It is desirable to en-sure that the outer tube does adequately bond to the inner tube in order to provide for sufficient peel strength of the finished tubing and it is known to apply substances such as adhesives and bonding agents to the exterior surface of the inner tube to assist in the bonding of the outer tube thereto. Problems some-times arise with known reagents and misbonding occurs, in which event the inner and outer tubes are often separated from one an-other with the reinforcing material being bonded to neither the inner nor outer tube which reduces the strength and thus the ability to withstand internal pressure.
--1-- ~ ~
12~9493 Summary of the Invention According to the invention, there is provided rein-forced flexible tubing of thermoplastic material comprising:
a) a tubular core of thermoplastic material having on the outer surface thereof a multiplicity of contiguous forma-tions integral with said core, said formations defining valleys therebetween;
b) reinforcing material disposed on said outer sur-face of said core in intimate contact with said surface of said core; and c) a coating of thermoplastic material covering said outer surface of said core and said reinforcing material, said thermoplastic material of said coating being directly and intimately bonded to said thermoplastic material of said core.
According to another aspect of the invention, there is provided a method for manufacturing reinforced flexible tubing of thermoplastic material comprising the steps of:
a) providing a flexible tubular core of thermo-plastic material;
b) supplying reinforcing material to the surface of said core; and c) extruding, by means of an extruder, a thermo-plastic coating on the outer surface of said tubular core and said reinforcing material while creating a positive air pressure differential between the exterior and interior of said coating in said extruder during extrusion to urge said coating into intimate contact with said core and said reinforcing material.
Brief Description of the Drawings The present invention will be further described with reference to the following drawings which are merely illustra-tive of the invention and are not intended to limit the inven-tion.
Figure 1 is a prospective, partly-cut away view of tub-ing according to the present invention;
Figure 2 is a transverse cross-section of tubing similar to that shown in Figure 1 but having more formations on the inner tube;
Figure 3 is a prospective, partly-cut away view of tub-ing of another embodiment of the present invention;
Figure 4 is a schematic diagram illustrating the apparatus used in practising the invention;
Figure 5 is a sectional plan of an extruder forming part of an embodiment of the apparatus;
Figure 6 is a transverse cross-section of an extrusion die useful in an embodiment of the apparatus;
Figure 7 is a sectional plan view of nip rollers use-ful in an embodiment of the apparatus;
Figure 8 is a transverse cross-sectional view of tub-ing of an embodiment of the present invention; and Figure 9 is a transverse cross-sectional view of tub-ing of an embodiment of the present invention.
Description of the Preferred embodiments Referring to Figures 1-3, reinforced flexible tubing 1 has a tubular core 2 of thermoplastic material having a multi-plicity of contiguous formations 3 integral with the core. The formations 3 define valleys, each of which contains (Figure 1) or is bridged by (Figure 3) reinforcing material 4. Extruded over and covering core 2 and reinforcing material 4 is coating 5 of thermoplastic material.
The outer surface core 2 is formed with contiguous formations 3, such as, for example, ridges, ribs or unduiations.
Preferably, the formations comprise a series of ridges or ribs defining the valleys therebetween and, most preferably, the formations comprising a series of ridges which run longitudin-ally of the core 2 so that the ridges 3 are parallel to the main central axis of core 2. When a series of ribs or ridges are pro-vided, it is convenient for the valleys defined therebetween to 1~094g3 be V-shaped ln cross-section, the ridges or ribs thus being cor-respondingly tapered from their base. It is, however, possible to provide ribs or ridges having other shaped cross-sections such as trapezoidal cross-section. Where a trapezoidal cross-section is used, the shortest side of the trapezoidal cross-section is preferably adjacent to the outer surface of core 2.
The provision of the aforementioned formations increases the external surface area for a given outer diameter of core 2.
Tubular core 2 may be formed of any suitable thermo-plastic material. A preferred thermoplastic material for form-ing core 2 is polyvinyl chloride. Tubular core 2 may be formed of an anti-static thermoplastic material where anti-static pro-perties are required in the final product, such as in some types of tubing for medical purposes. Tubular core 2 having forma-tions 3 on the outer surface thereof is preferably formed by extrusion.
The reinforcing material 4 disposed on the outer sur-face of core 2 may be comprised of, for example, a textile mate-rial, such as yarn or thread, or a metallic material, such as wire. A textile yarn, such as polyamide or polyester yarn, is preferred. For many tubing constructions, a yarn size of 1100 decitex gauge is suitable. Other yarn sizes can be selected, depending on the size of tubing and the reinforcement required.
The reinforcing material 4 may be disposed on the outer surface of core 2 in lapped or braided fashion, for example in criss-cross fashion. When reinforcing material 4 is in lapped or braided form, it is preferable that a plurality of, for example, textile yarns be disposed on the core to produce the braid effect with half the reinforcing material running in a spaced apart, somewhat clockwise direction and the other half ~209493 running in a spaced apart, somewhat counterclockwise direction, the yarns crossing but leaving generally diamond-shaped spaces therebetween. However, i~ core 2 has the aforementioned longi-tudinally disposed ribs or ridges, reinforcing material 4 may also be conveniently placed along the length of valleys defined thereby, thus increasing the longitudinal as well as hoop strength.
A coating 5 of thermoplastic material covers reinforc-ing material 4 and tubular core 2. The thermoplastic material of coating 5 is generally similar to or compatible with that used for tubular core 2. Preferably, coating 5 is of the same thermoplastic material as core 2. Most preferably, both tubular core 2 and coating 5 are polyvinyl chloride. When both the tubular core and coating are of polyvinyl chloride, the finished tube is usable over a temperature range of at least about -20C
to about 65 C.
The thermoplastic material of coating 5 is directly and intimately bonded to the thermoplastic material of the core
METHOD OF MANUFACTURING SAME
Background of the Invention Field of the Invention The present invention relates to reinforced flexible tubing of thermoplastic material and, more particularly, to rein-forced flexible tubing having high resistance to bursting.
The present invention also relates to a method of manu-facturing flexible tubing of thermoplastic material.
Description of the Prior Art It is known to form a plastic tube, for example, by extrusion through a circular die, to reinforce that tube by applying a reinforcing material such as a textile or a metallic material, normally in braid or lap form, over the exterior sur-face thereof, and to apply a second (outer) tube, generally by extrusion over the inner tube of the reinforcing material. Pre-ferably, the outer tube is applied over the inner tube and the reinforcing material while the inner tube is still warm from its own formation, which is generally by extrusion, so that the mate-rials of the inner and outer tubes can blend together and trap the reinforcing material therebetween. It is desirable to en-sure that the outer tube does adequately bond to the inner tube in order to provide for sufficient peel strength of the finished tubing and it is known to apply substances such as adhesives and bonding agents to the exterior surface of the inner tube to assist in the bonding of the outer tube thereto. Problems some-times arise with known reagents and misbonding occurs, in which event the inner and outer tubes are often separated from one an-other with the reinforcing material being bonded to neither the inner nor outer tube which reduces the strength and thus the ability to withstand internal pressure.
--1-- ~ ~
12~9493 Summary of the Invention According to the invention, there is provided rein-forced flexible tubing of thermoplastic material comprising:
a) a tubular core of thermoplastic material having on the outer surface thereof a multiplicity of contiguous forma-tions integral with said core, said formations defining valleys therebetween;
b) reinforcing material disposed on said outer sur-face of said core in intimate contact with said surface of said core; and c) a coating of thermoplastic material covering said outer surface of said core and said reinforcing material, said thermoplastic material of said coating being directly and intimately bonded to said thermoplastic material of said core.
According to another aspect of the invention, there is provided a method for manufacturing reinforced flexible tubing of thermoplastic material comprising the steps of:
a) providing a flexible tubular core of thermo-plastic material;
b) supplying reinforcing material to the surface of said core; and c) extruding, by means of an extruder, a thermo-plastic coating on the outer surface of said tubular core and said reinforcing material while creating a positive air pressure differential between the exterior and interior of said coating in said extruder during extrusion to urge said coating into intimate contact with said core and said reinforcing material.
Brief Description of the Drawings The present invention will be further described with reference to the following drawings which are merely illustra-tive of the invention and are not intended to limit the inven-tion.
Figure 1 is a prospective, partly-cut away view of tub-ing according to the present invention;
Figure 2 is a transverse cross-section of tubing similar to that shown in Figure 1 but having more formations on the inner tube;
Figure 3 is a prospective, partly-cut away view of tub-ing of another embodiment of the present invention;
Figure 4 is a schematic diagram illustrating the apparatus used in practising the invention;
Figure 5 is a sectional plan of an extruder forming part of an embodiment of the apparatus;
Figure 6 is a transverse cross-section of an extrusion die useful in an embodiment of the apparatus;
Figure 7 is a sectional plan view of nip rollers use-ful in an embodiment of the apparatus;
Figure 8 is a transverse cross-sectional view of tub-ing of an embodiment of the present invention; and Figure 9 is a transverse cross-sectional view of tub-ing of an embodiment of the present invention.
Description of the Preferred embodiments Referring to Figures 1-3, reinforced flexible tubing 1 has a tubular core 2 of thermoplastic material having a multi-plicity of contiguous formations 3 integral with the core. The formations 3 define valleys, each of which contains (Figure 1) or is bridged by (Figure 3) reinforcing material 4. Extruded over and covering core 2 and reinforcing material 4 is coating 5 of thermoplastic material.
The outer surface core 2 is formed with contiguous formations 3, such as, for example, ridges, ribs or unduiations.
Preferably, the formations comprise a series of ridges or ribs defining the valleys therebetween and, most preferably, the formations comprising a series of ridges which run longitudin-ally of the core 2 so that the ridges 3 are parallel to the main central axis of core 2. When a series of ribs or ridges are pro-vided, it is convenient for the valleys defined therebetween to 1~094g3 be V-shaped ln cross-section, the ridges or ribs thus being cor-respondingly tapered from their base. It is, however, possible to provide ribs or ridges having other shaped cross-sections such as trapezoidal cross-section. Where a trapezoidal cross-section is used, the shortest side of the trapezoidal cross-section is preferably adjacent to the outer surface of core 2.
The provision of the aforementioned formations increases the external surface area for a given outer diameter of core 2.
Tubular core 2 may be formed of any suitable thermo-plastic material. A preferred thermoplastic material for form-ing core 2 is polyvinyl chloride. Tubular core 2 may be formed of an anti-static thermoplastic material where anti-static pro-perties are required in the final product, such as in some types of tubing for medical purposes. Tubular core 2 having forma-tions 3 on the outer surface thereof is preferably formed by extrusion.
The reinforcing material 4 disposed on the outer sur-face of core 2 may be comprised of, for example, a textile mate-rial, such as yarn or thread, or a metallic material, such as wire. A textile yarn, such as polyamide or polyester yarn, is preferred. For many tubing constructions, a yarn size of 1100 decitex gauge is suitable. Other yarn sizes can be selected, depending on the size of tubing and the reinforcement required.
The reinforcing material 4 may be disposed on the outer surface of core 2 in lapped or braided fashion, for example in criss-cross fashion. When reinforcing material 4 is in lapped or braided form, it is preferable that a plurality of, for example, textile yarns be disposed on the core to produce the braid effect with half the reinforcing material running in a spaced apart, somewhat clockwise direction and the other half ~209493 running in a spaced apart, somewhat counterclockwise direction, the yarns crossing but leaving generally diamond-shaped spaces therebetween. However, i~ core 2 has the aforementioned longi-tudinally disposed ribs or ridges, reinforcing material 4 may also be conveniently placed along the length of valleys defined thereby, thus increasing the longitudinal as well as hoop strength.
A coating 5 of thermoplastic material covers reinforc-ing material 4 and tubular core 2. The thermoplastic material of coating 5 is generally similar to or compatible with that used for tubular core 2. Preferably, coating 5 is of the same thermoplastic material as core 2. Most preferably, both tubular core 2 and coating 5 are polyvinyl chloride. When both the tubular core and coating are of polyvinyl chloride, the finished tube is usable over a temperature range of at least about -20C
to about 65 C.
The thermoplastic material of coating 5 is directly and intimately bonded to the thermoplastic material of the core
2 and reinforcing material 4 is securely entrapped between core 2 and coating 5. This direct intimate bonding of the material of coating 5 to the outer surface of core 2 may preferably be achieved by extruding coating 5 over core 2 and reinforcing mate-rial 4 with a positive air pressure differential between the exterior and interior of the coating, as will be described in de-tail hereinafter with regard to the method of the invention.
Often the coating of the tubing of the present inven-tion does not have a smooth surface, this being particularly so when the material of the coating is extruded under pressure, and in general the outer surface of the coating will follow the con-tours of the formations of the core and/or the reinforcing mate-120~493 rial. Tubing of the present invention having an outer surface which is not smooth affords advantages in the coiling thereof.
This is because tubing having a smooth outer surface tends to stick to itself, especially with smooth polyvinyl chloride sur-faces, and this causes problems in automatic coiling which do not occur with tubing of the present invention having a non-smooth surface.
If it is desirous to provide tubing of very high strength, reinforcing material may be applied on the outer sur-face of the coating, and a second coating applied thereover asshown in Fig. 9. The tubing thus formed includes a tubular core 2 having the aforementioned formations 3, reinforcing material 4A on the outer surface of tubular core 2, a coating 5A applied over the core and its reinforcing material 4A, reinforcing mate-rial 4B on the outer surface of the first coating and a second coating 5B applied over the first coating 5A and its association reinforcing material 4B. The first and second coatings are applied so as to entrap the reinforcing materials between the core and first coating, and first and second coatings, respec-tively. The thermoplastic material of the first coating isdirectly and intimately bonded to the thermoplastic material of the core and the thermoplastic material of the second coating is directly and intimately bonded to the thermoplastic of the outer surface of the first coating.
The outer surface of this second coating may be smooth or non-smooth, although any tube produced in the aforementioned manner greatly reduces the interface bond stress since the flex-ing shear load on the interface between the substrate and the subsequent layers is spread over a large percentage of the resultant wall thickness of the whole tubing thereby reducing 1~2094~3 the necessity for high artificial bond strength. Of course, further layers of reinforcing material and thermoplastlc mate-rial may be provided as required for even greater strength.
A further embodiment of the present invention is flat tubing of ribbon-like form as shown in Fig. 8. Such tubing is substantially flat with the volume of the inside of the core be-ing substantially zero and contains substantially no air within the inner part of the tubing when not in use. The tubing is cap-able of assuming a tubular form by introduction of internal fluid pressure. Such flattened tubing may be used as hosepipe, being self draining, by virture of the elastic memory of the material for the ribbon-like form. This tubing is more easily formed into a roll and occupies less space for storage than con-ventional round tubing.
The ridges and valleys provide an additional function in this flat embodiment in that they act as hinge-like parts, allowing the hose to readily assume a traditional shape under internal pressure. When the pressure is removed, the hose re-turns to a substantially completely flat profile, due to the elastic memory of the tubing urging evacuation of the fluid with-in the tubing.
The present invention generally enables a reduction of up to 30% of the material used to form the second tube in com-parison with prior art composite tubing and still is capable of achieving the same resistance to bursting as the conventional tubing. For example, fully flexible polyvinyl chloride tubing according to the present invention can be produced having an overall thickness of no more than about 3 mm and an inside dia-meter of up to about 19 mm, with a capability of working pres-sures as high as 60 BAR at 20 C.
The excellent flexibility of the tubing of the presentinvention is high due to the need for less material for a given strength.
The apparatus for manufacturing flexible reinforced tubing of the present comprises a core supply for supplying a flexible tubular core, a reinforcing material supply device for supplying at least one reinforcing material to the outer surface of the core and an extruder arranged to extrude a tubular coat-ing of thermoplastic material onto the outer surface of the core in the reinforcing material, the extruder being adapted to en-able a positive air pressure differential to be applied between the exterior and the interior of the coating around the core dur-ing extrusion of the coating.
The method of manufacturing flexible reinforced tubing of the present invention includes providing a flexible tubular core of thermoplastic material, supplying reinforcing material to the surface of the core and extruding, by means of an extruder, a thermoplastic coating on the outer surface of the tubular core while creating a positive air pressure differential between the exterior and interior of the coating in the extruder during extrusion to urge the coating into intrinsic contact with the core and the reinforcing material. This positive air pres-sure differential during extrusion causes a bond to form directly between the core and the coating.
Preferably, the exterior of the coating is at atmos-pheric pressure, and a vacuum is applied to the interior of the coating as it is extruded. The coating is suitably extruded as a tube uniformly spaced from the surface of the core, the vacuum drawing the coating down onto the core while the coating is still in a plastic state.
_g_ ~ rhe core supply may be a reel, but is preferably an-other plastics extruder, continuously forming a tubular core which is cooled in water before passing through the winding de-vice. The reinforcing material supply device is preferably arranged to apply a plurality of reinforcing threads, half the thread running in the opposite direction to the other half.
The apparatus and method are capable of producing tub-ing having typically one third less material than conventional tubing of the same general structure, internal diameter and burst pressure. The amount of tubing which has to be discarded through bond failure is substantially reduced and higher produc-tion speeds can be achieved.
The apparatus, shown in Figure 4, includes a first extruder 11 which is a conventional screw feed extruder receiv-ing thermoplastic material, such as polyvinyl chloride, in the form of granules. The arrangement of the granule feed hopper and feed screw barrel is conventional and these parts are there-fore not shown in detail, only a part of the barrel being shown.
The granules are melted and the molten thermoplastic material is forced through an annular die to extrude a tubular core 2, pre-ferably having an external surface consisting of longitudinal ridges and valleys of generally triangular configuration around the tube. Dies suitable for extruding tubular core 2 are des-cribed in further detail hereinafter with regard to Figure 6.
The core 2 is preferably extruded at a temperature of about 140 to 150C and at a linear speed of about 2000 ft/hr (170 mm/s) and passes through a cooling bath 13 containing a flow of cool-ing water. The cooling bath 13 cools the core 2 to about 70 C
before it reaches a reinforcing material supply, such as winding device 14 for the application of reinforcing material. Wlnding device 14 is com-prised of two contra-rotating drums 14A and 14B, each of which contain a plurality of reels 15 of reinforcing material. The reinforcing material may be comprised of, for example, a textile material, such as yarn or thread, or a metallic material, such as wire. The reels are arranged to feed the reinforcing mate-rial to the core under a very light tension and spaced apart so as to produce a braided effect, the yarns crossing but leaving generally diamond-shape spaces therebetween.
The core with the reinforcing material thereon passes from winding device 14 into a second extruder 16 of similar general configuration to the first extruder 11. The coating material is a thermoplastic material, preferably a material which is similar to or compatible with that used for the core.
Most preferably both the core and the coating material are poly-vinyl chloride. The coating material is supplied to an annular die which is described hereinafter in more detail with reference to Fig. 5. A vacuum pump 17 is connected to the extruder 16 by means of a vacuum pipe 18. The coated core passes through a second cooling bath 19 whose length, coolant flow rate and tem-perature are selected to reduce the temperature of the coating from the extrusion temperature, which may be from about 140 to 150 C, to a suitable temperature to permit manual handling of the tube, for example, forming into rolls such as on a reel 10.
Referring to Fig. 5, the extruder comprises an elon-gated screw 20 which drives the molten thermoplastic coating material into the extrudina head 21. Head 21 comprises a two part extruding tool 22, having an outer part 22A containing a frusto-conical bore 22B therethrough and a generally frusto-conical inner part 22C whose conical surface contains an angle ~209493 smaller than that contained by the surface of the bore 22B. Theinner part 22C has a cylindrical bore 22D therethrough, the dia-meter of which is larger than the external diameter of the core 2 with the reinforcing material wound onto the surface thereof so that the prevailing gas pressure at the rear face 22E of the inner part 22C is substantially the same as that of the opposite end of the bore 22D.
The rear face 22E is attached to one end of a tubular vacuum chamber 23 which is in turn attached to an adjusting ring 24 which is externally screw-threaded and screws into a corres-pondingly-threaded socket 25 in the body of extruding head 21.
Rotation of the adjusting ring 24 thus moves the inner part 22C
of the extruding tool relative to outer part 22A which in turn alters the thickness of the coating extruded.
A vacuum connector piece 26 extends axially from adjusting ring 24 and has a bore 27 therethrough which communi-cates with the interior of vacuum 23 and with vacuum tube 28 which is connected by flexible hose 8 to vacuum pump 7 (see Fig.
4). An inlet tube 29, having a tube guide, typically of PTFE, in sealing bushing 30 in the end thereof, extends axially from connector piece 26 and the interior of the tube communicates with the interior of connector piece 26.
Bushing 30 makes sealing contact with the core as it enters the inlet tube 29 and passes through the vacuum chamber to the extruding tool, thus maintaining the vacuum.
The coating material delivered to the extruding head 21 by screw 20 passes into an annular space 31 surrounding the vacuum chamber 23 and from there into the space between the inner and outer parts 22C and 22A of the extruding tool. The material is extruded at a rate such that it flows out of the ~20949:~
annular gap at the outlet of the extruding tool 22 at substanti-ally the same speed as out of the annular gap at the outlet of the extruding tool 22 and substantially the same speed as that at which the core 2 passes through the extruder, typically 170 mm/sec. The vacuum in the vacuum chamber is communicated to the inside of the coating at the point of extrusion. The coat-ing is extruded substantially parallel to the core and the vacuum, of the order of about 20 to 40 inch water gauge, draws the coating into intimate contact with the core and with the reinforcing material wound onto the core. The coating thickness, after being drawn onto the core, is less than the thickness of the core, and the texture of the reinforcing material may be felt and may also be seen after coating.
In a first alternative embodiment, the coated tubing passes from the second extruder 16 through cooled nip rollers 32 as shown in Fig. 7 before entering cooling bath 19. Nip rollers 32 flatten the tubing into a ribbon-like form which may be re-turned to a tubular form by internal fluid pressure. Such flat-tened tubing 33 may be used as hosepipe, being self-draining, by virtue of the elastic memory of the material for the ribbon-like form, more easily formed into a roll, and occupying less space for storage than conventional round tubing.
In a second alternative embodiment, the coated tubing from the second extruder 6 passes through a cooling bath which brings the temperature down to about 70C then to a second wind-ing device identical to the first winding device 4 where a second set of reinforcing material is applied, and from there to a third extruder, of a generally identical construction to the second extruder 16, where a final outer coating is applied, again of a thin thermoplastic material, such as polyvinyl ~Z0~4~3 chloride. Tubin~ produced in this manner is suitable for ~Jery high pressure applications, with operating pressures, for example, for a 10 mm internal diameter tube, in excess of 60 BAR
at 20 C.
The apparatus for and the method of manufacturing of reinforced flexible tubing of thermoplastic material provides efficient low cost production because production may be carried out in a continuous manner. Such continuous production permits a thin outer coating to be applied over the braid and core and in multilayer tubing prevents problems such as "cold flow" when the tubing is assembled with connectors. Further, tubing pro-duced according to the present invention can be produced at lower cost due to tremendous saving in material weight. Work in progress is non-existent as tubing may be continuously produced and scran levels are exceedingly low.
In a preferred embodiment of the invention, approxi-mately 80% of the thermoplastic material is in the inner core and a maximum of about 20% of the thermoplastic is in the outer coating. This allows the outer coating to assume the configura-tion of the ribbed inner core giving the tubing an abrasionresistant cover since the contact point at any abrasion area is reduced.
In a preferred embodiment of the invention, tubular core 2 may be extruded utilizing a die of the type shown in Figure 6 to produce the tubular core 2 having an external sur-face consisting of longitudinal ridges and valleys of generally triangular configuration extending longitudinally on the tube.
Reinforced flexible tubing of thermoplastic material has been successfully produced utilizing dies 34, having the configura-12094g3 tions shown in Table 1, in first extruder of an apparatus similar to that shown in Fig. 4. The inside diameter of the core thus produced is also shown in Table 1.
Table I
Die Dimensions Die Core Right Angle Bore Width of Ridge Ridge Peak Inside A(degrees) Diameter Valley Base Height Angle Diameter B(in.) C(in.) D(in.) E(degrees) (in.) 1 84 0.480 0.012 0.035 18 0.937 2 84 0.550 0.009 0.035 15 0.937
Often the coating of the tubing of the present inven-tion does not have a smooth surface, this being particularly so when the material of the coating is extruded under pressure, and in general the outer surface of the coating will follow the con-tours of the formations of the core and/or the reinforcing mate-120~493 rial. Tubing of the present invention having an outer surface which is not smooth affords advantages in the coiling thereof.
This is because tubing having a smooth outer surface tends to stick to itself, especially with smooth polyvinyl chloride sur-faces, and this causes problems in automatic coiling which do not occur with tubing of the present invention having a non-smooth surface.
If it is desirous to provide tubing of very high strength, reinforcing material may be applied on the outer sur-face of the coating, and a second coating applied thereover asshown in Fig. 9. The tubing thus formed includes a tubular core 2 having the aforementioned formations 3, reinforcing material 4A on the outer surface of tubular core 2, a coating 5A applied over the core and its reinforcing material 4A, reinforcing mate-rial 4B on the outer surface of the first coating and a second coating 5B applied over the first coating 5A and its association reinforcing material 4B. The first and second coatings are applied so as to entrap the reinforcing materials between the core and first coating, and first and second coatings, respec-tively. The thermoplastic material of the first coating isdirectly and intimately bonded to the thermoplastic material of the core and the thermoplastic material of the second coating is directly and intimately bonded to the thermoplastic of the outer surface of the first coating.
The outer surface of this second coating may be smooth or non-smooth, although any tube produced in the aforementioned manner greatly reduces the interface bond stress since the flex-ing shear load on the interface between the substrate and the subsequent layers is spread over a large percentage of the resultant wall thickness of the whole tubing thereby reducing 1~2094~3 the necessity for high artificial bond strength. Of course, further layers of reinforcing material and thermoplastlc mate-rial may be provided as required for even greater strength.
A further embodiment of the present invention is flat tubing of ribbon-like form as shown in Fig. 8. Such tubing is substantially flat with the volume of the inside of the core be-ing substantially zero and contains substantially no air within the inner part of the tubing when not in use. The tubing is cap-able of assuming a tubular form by introduction of internal fluid pressure. Such flattened tubing may be used as hosepipe, being self draining, by virture of the elastic memory of the material for the ribbon-like form. This tubing is more easily formed into a roll and occupies less space for storage than con-ventional round tubing.
The ridges and valleys provide an additional function in this flat embodiment in that they act as hinge-like parts, allowing the hose to readily assume a traditional shape under internal pressure. When the pressure is removed, the hose re-turns to a substantially completely flat profile, due to the elastic memory of the tubing urging evacuation of the fluid with-in the tubing.
The present invention generally enables a reduction of up to 30% of the material used to form the second tube in com-parison with prior art composite tubing and still is capable of achieving the same resistance to bursting as the conventional tubing. For example, fully flexible polyvinyl chloride tubing according to the present invention can be produced having an overall thickness of no more than about 3 mm and an inside dia-meter of up to about 19 mm, with a capability of working pres-sures as high as 60 BAR at 20 C.
The excellent flexibility of the tubing of the presentinvention is high due to the need for less material for a given strength.
The apparatus for manufacturing flexible reinforced tubing of the present comprises a core supply for supplying a flexible tubular core, a reinforcing material supply device for supplying at least one reinforcing material to the outer surface of the core and an extruder arranged to extrude a tubular coat-ing of thermoplastic material onto the outer surface of the core in the reinforcing material, the extruder being adapted to en-able a positive air pressure differential to be applied between the exterior and the interior of the coating around the core dur-ing extrusion of the coating.
The method of manufacturing flexible reinforced tubing of the present invention includes providing a flexible tubular core of thermoplastic material, supplying reinforcing material to the surface of the core and extruding, by means of an extruder, a thermoplastic coating on the outer surface of the tubular core while creating a positive air pressure differential between the exterior and interior of the coating in the extruder during extrusion to urge the coating into intrinsic contact with the core and the reinforcing material. This positive air pres-sure differential during extrusion causes a bond to form directly between the core and the coating.
Preferably, the exterior of the coating is at atmos-pheric pressure, and a vacuum is applied to the interior of the coating as it is extruded. The coating is suitably extruded as a tube uniformly spaced from the surface of the core, the vacuum drawing the coating down onto the core while the coating is still in a plastic state.
_g_ ~ rhe core supply may be a reel, but is preferably an-other plastics extruder, continuously forming a tubular core which is cooled in water before passing through the winding de-vice. The reinforcing material supply device is preferably arranged to apply a plurality of reinforcing threads, half the thread running in the opposite direction to the other half.
The apparatus and method are capable of producing tub-ing having typically one third less material than conventional tubing of the same general structure, internal diameter and burst pressure. The amount of tubing which has to be discarded through bond failure is substantially reduced and higher produc-tion speeds can be achieved.
The apparatus, shown in Figure 4, includes a first extruder 11 which is a conventional screw feed extruder receiv-ing thermoplastic material, such as polyvinyl chloride, in the form of granules. The arrangement of the granule feed hopper and feed screw barrel is conventional and these parts are there-fore not shown in detail, only a part of the barrel being shown.
The granules are melted and the molten thermoplastic material is forced through an annular die to extrude a tubular core 2, pre-ferably having an external surface consisting of longitudinal ridges and valleys of generally triangular configuration around the tube. Dies suitable for extruding tubular core 2 are des-cribed in further detail hereinafter with regard to Figure 6.
The core 2 is preferably extruded at a temperature of about 140 to 150C and at a linear speed of about 2000 ft/hr (170 mm/s) and passes through a cooling bath 13 containing a flow of cool-ing water. The cooling bath 13 cools the core 2 to about 70 C
before it reaches a reinforcing material supply, such as winding device 14 for the application of reinforcing material. Wlnding device 14 is com-prised of two contra-rotating drums 14A and 14B, each of which contain a plurality of reels 15 of reinforcing material. The reinforcing material may be comprised of, for example, a textile material, such as yarn or thread, or a metallic material, such as wire. The reels are arranged to feed the reinforcing mate-rial to the core under a very light tension and spaced apart so as to produce a braided effect, the yarns crossing but leaving generally diamond-shape spaces therebetween.
The core with the reinforcing material thereon passes from winding device 14 into a second extruder 16 of similar general configuration to the first extruder 11. The coating material is a thermoplastic material, preferably a material which is similar to or compatible with that used for the core.
Most preferably both the core and the coating material are poly-vinyl chloride. The coating material is supplied to an annular die which is described hereinafter in more detail with reference to Fig. 5. A vacuum pump 17 is connected to the extruder 16 by means of a vacuum pipe 18. The coated core passes through a second cooling bath 19 whose length, coolant flow rate and tem-perature are selected to reduce the temperature of the coating from the extrusion temperature, which may be from about 140 to 150 C, to a suitable temperature to permit manual handling of the tube, for example, forming into rolls such as on a reel 10.
Referring to Fig. 5, the extruder comprises an elon-gated screw 20 which drives the molten thermoplastic coating material into the extrudina head 21. Head 21 comprises a two part extruding tool 22, having an outer part 22A containing a frusto-conical bore 22B therethrough and a generally frusto-conical inner part 22C whose conical surface contains an angle ~209493 smaller than that contained by the surface of the bore 22B. Theinner part 22C has a cylindrical bore 22D therethrough, the dia-meter of which is larger than the external diameter of the core 2 with the reinforcing material wound onto the surface thereof so that the prevailing gas pressure at the rear face 22E of the inner part 22C is substantially the same as that of the opposite end of the bore 22D.
The rear face 22E is attached to one end of a tubular vacuum chamber 23 which is in turn attached to an adjusting ring 24 which is externally screw-threaded and screws into a corres-pondingly-threaded socket 25 in the body of extruding head 21.
Rotation of the adjusting ring 24 thus moves the inner part 22C
of the extruding tool relative to outer part 22A which in turn alters the thickness of the coating extruded.
A vacuum connector piece 26 extends axially from adjusting ring 24 and has a bore 27 therethrough which communi-cates with the interior of vacuum 23 and with vacuum tube 28 which is connected by flexible hose 8 to vacuum pump 7 (see Fig.
4). An inlet tube 29, having a tube guide, typically of PTFE, in sealing bushing 30 in the end thereof, extends axially from connector piece 26 and the interior of the tube communicates with the interior of connector piece 26.
Bushing 30 makes sealing contact with the core as it enters the inlet tube 29 and passes through the vacuum chamber to the extruding tool, thus maintaining the vacuum.
The coating material delivered to the extruding head 21 by screw 20 passes into an annular space 31 surrounding the vacuum chamber 23 and from there into the space between the inner and outer parts 22C and 22A of the extruding tool. The material is extruded at a rate such that it flows out of the ~20949:~
annular gap at the outlet of the extruding tool 22 at substanti-ally the same speed as out of the annular gap at the outlet of the extruding tool 22 and substantially the same speed as that at which the core 2 passes through the extruder, typically 170 mm/sec. The vacuum in the vacuum chamber is communicated to the inside of the coating at the point of extrusion. The coat-ing is extruded substantially parallel to the core and the vacuum, of the order of about 20 to 40 inch water gauge, draws the coating into intimate contact with the core and with the reinforcing material wound onto the core. The coating thickness, after being drawn onto the core, is less than the thickness of the core, and the texture of the reinforcing material may be felt and may also be seen after coating.
In a first alternative embodiment, the coated tubing passes from the second extruder 16 through cooled nip rollers 32 as shown in Fig. 7 before entering cooling bath 19. Nip rollers 32 flatten the tubing into a ribbon-like form which may be re-turned to a tubular form by internal fluid pressure. Such flat-tened tubing 33 may be used as hosepipe, being self-draining, by virtue of the elastic memory of the material for the ribbon-like form, more easily formed into a roll, and occupying less space for storage than conventional round tubing.
In a second alternative embodiment, the coated tubing from the second extruder 6 passes through a cooling bath which brings the temperature down to about 70C then to a second wind-ing device identical to the first winding device 4 where a second set of reinforcing material is applied, and from there to a third extruder, of a generally identical construction to the second extruder 16, where a final outer coating is applied, again of a thin thermoplastic material, such as polyvinyl ~Z0~4~3 chloride. Tubin~ produced in this manner is suitable for ~Jery high pressure applications, with operating pressures, for example, for a 10 mm internal diameter tube, in excess of 60 BAR
at 20 C.
The apparatus for and the method of manufacturing of reinforced flexible tubing of thermoplastic material provides efficient low cost production because production may be carried out in a continuous manner. Such continuous production permits a thin outer coating to be applied over the braid and core and in multilayer tubing prevents problems such as "cold flow" when the tubing is assembled with connectors. Further, tubing pro-duced according to the present invention can be produced at lower cost due to tremendous saving in material weight. Work in progress is non-existent as tubing may be continuously produced and scran levels are exceedingly low.
In a preferred embodiment of the invention, approxi-mately 80% of the thermoplastic material is in the inner core and a maximum of about 20% of the thermoplastic is in the outer coating. This allows the outer coating to assume the configura-tion of the ribbed inner core giving the tubing an abrasionresistant cover since the contact point at any abrasion area is reduced.
In a preferred embodiment of the invention, tubular core 2 may be extruded utilizing a die of the type shown in Figure 6 to produce the tubular core 2 having an external sur-face consisting of longitudinal ridges and valleys of generally triangular configuration extending longitudinally on the tube.
Reinforced flexible tubing of thermoplastic material has been successfully produced utilizing dies 34, having the configura-12094g3 tions shown in Table 1, in first extruder of an apparatus similar to that shown in Fig. 4. The inside diameter of the core thus produced is also shown in Table 1.
Table I
Die Dimensions Die Core Right Angle Bore Width of Ridge Ridge Peak Inside A(degrees) Diameter Valley Base Height Angle Diameter B(in.) C(in.) D(in.) E(degrees) (in.) 1 84 0.480 0.012 0.035 18 0.937 2 84 0.550 0.009 0.035 15 0.937
3 84 0.725 0.035 0.023 12 0.875
4 84 0.915 0.013 0.028 8 0.812
5 84 0.980 0.014 0.035 9 0.750
6 84 1.512 0.003 0.035 5 The present invention will be further illustrated by the following examples which are intended merely to illustrate the present invention and are not intended to limit the scope of the invention which is defined in the claims.
EXAMPLE
A flat hose was produced in accordance with the method described hereinbefore with reference to Figures 4 and 7, as the first alternative embodiment. The internal diameter of the tube before passage through the nip rollers was 12 mm. The nominal overall wall thickness was 2 mm, with the height of the ridges, relative to the valleys, being 0.58 mm. The outer coating thick-ness was approximately 1 mm relative to the valleys. The over-all weight of the hose was 93 g/m. Samples of the tube were tested for burst pressure by applying gradually increasing hydro-static pressure to a sealed section of the tube. The minumum -lZ094g3 burst pressure out of a number of samples was found to be 450 p.s~i.g. (3.1 MNm ) and burst pressures were generally in ex-cess of 500 p.s.i.g. (3.45 MNm ).
Round hoses were prepared in accordance with the main method hereinbefore described with reference to Figures 4 and 5.
Hoses of exactly the same nominal dimensions were produced by a similar process, but without the application of vacuum. Each hose was tested for burst pressure as in the Example herein-before.
The results were as follows:
BURST PRESSURE
(at 20C) (psig) Nominal Internal COATING COATING
Diameter (mm) WITHOUT WITH
VACUUM VACUUM
12 790 ~50 19 575 6~5 Hoses were produced using the methods as in Comparative Example 1, but, in the case of the hoses coated with-out application of vacuum, the coating thickness was such that the burst pressures of the hoses coated with the without vacuum were generally the same. The resulting weights of the hoses for a unit length were compared, and Table 2 gives the result.
20Nominal Internal WEIGHT (g/m) Diameter (mm) COATING COATING
WITHOUT WITH
VACUUM VACUUM
6 90.8 54 165 ~5 19 334 ~58 12099~93 A hose manufactured in accordance with the method here-inbefore described with reference to Figures 4 and 5 was tested to compare the strength of bonding between the coating and the core with a conventional gas hose having a similar general con-struction, but a smooth core tube and coating applied without vacuum. The hoses were both high pressure gas hoses of 10 mm internal diameter.
300 mm lengths of each type of hose were used as test specimens. A hypodermic needle was inserted at one end of the hose at the junction between the coating and the core. The hose was plugged and secured with hose clips, the needle extending beyond the clip at one end. Each sample was immersed in water during the test, and air was supplied under pressure to the hypodermic needle.
Samples in accordance with the invention were pres-surized for 20 hours at 50 p.s.i.g. (343 kNm 2), and for one hour at 60 p.s.i.g. (414 kNm 2) at 80 p.s.i.g. (552 kNm 2), and no leak was detected at the end of this time.
A sample of the conventional hose showed air leaks from both ends, from between the layers, after only a few minutes at a pressure of 10 p.s.i.g. (69 kNm ).
EXAMPLE
A flat hose was produced in accordance with the method described hereinbefore with reference to Figures 4 and 7, as the first alternative embodiment. The internal diameter of the tube before passage through the nip rollers was 12 mm. The nominal overall wall thickness was 2 mm, with the height of the ridges, relative to the valleys, being 0.58 mm. The outer coating thick-ness was approximately 1 mm relative to the valleys. The over-all weight of the hose was 93 g/m. Samples of the tube were tested for burst pressure by applying gradually increasing hydro-static pressure to a sealed section of the tube. The minumum -lZ094g3 burst pressure out of a number of samples was found to be 450 p.s~i.g. (3.1 MNm ) and burst pressures were generally in ex-cess of 500 p.s.i.g. (3.45 MNm ).
Round hoses were prepared in accordance with the main method hereinbefore described with reference to Figures 4 and 5.
Hoses of exactly the same nominal dimensions were produced by a similar process, but without the application of vacuum. Each hose was tested for burst pressure as in the Example herein-before.
The results were as follows:
BURST PRESSURE
(at 20C) (psig) Nominal Internal COATING COATING
Diameter (mm) WITHOUT WITH
VACUUM VACUUM
12 790 ~50 19 575 6~5 Hoses were produced using the methods as in Comparative Example 1, but, in the case of the hoses coated with-out application of vacuum, the coating thickness was such that the burst pressures of the hoses coated with the without vacuum were generally the same. The resulting weights of the hoses for a unit length were compared, and Table 2 gives the result.
20Nominal Internal WEIGHT (g/m) Diameter (mm) COATING COATING
WITHOUT WITH
VACUUM VACUUM
6 90.8 54 165 ~5 19 334 ~58 12099~93 A hose manufactured in accordance with the method here-inbefore described with reference to Figures 4 and 5 was tested to compare the strength of bonding between the coating and the core with a conventional gas hose having a similar general con-struction, but a smooth core tube and coating applied without vacuum. The hoses were both high pressure gas hoses of 10 mm internal diameter.
300 mm lengths of each type of hose were used as test specimens. A hypodermic needle was inserted at one end of the hose at the junction between the coating and the core. The hose was plugged and secured with hose clips, the needle extending beyond the clip at one end. Each sample was immersed in water during the test, and air was supplied under pressure to the hypodermic needle.
Samples in accordance with the invention were pres-surized for 20 hours at 50 p.s.i.g. (343 kNm 2), and for one hour at 60 p.s.i.g. (414 kNm 2) at 80 p.s.i.g. (552 kNm 2), and no leak was detected at the end of this time.
A sample of the conventional hose showed air leaks from both ends, from between the layers, after only a few minutes at a pressure of 10 p.s.i.g. (69 kNm ).
Claims (20)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Reinforced flexible tubing of thermoplastic material comprising:
a) a tubular core of thermoplastic material having on the outer surface thereof a multiplicity of contiguous forma-tions integral with said core, said formations defining valleys therebetween;
b) reinforcing material disposed on said outer sur-face of said core in intimate contact with said surface of said core; and c) a coating of thermoplastic material covering said outer surface of said core and said reinforcing material, said thermoplastic material of said coating being directly and intimately bonded to said thermoplastic material of said core.
a) a tubular core of thermoplastic material having on the outer surface thereof a multiplicity of contiguous forma-tions integral with said core, said formations defining valleys therebetween;
b) reinforcing material disposed on said outer sur-face of said core in intimate contact with said surface of said core; and c) a coating of thermoplastic material covering said outer surface of said core and said reinforcing material, said thermoplastic material of said coating being directly and intimately bonded to said thermoplastic material of said core.
2. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said formations are ridges defin-ing V-shaped valleys therebetween.
3. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said formations are disposed long-itudinally of said tubular core parallel to the main central axis of said tubular core.
4. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said reinforcing material is selected from the group consisting of yarn, thread and wire.
5. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said reinforcing material is poly-amide yarn.
6. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said reinforcing material is dis-posed on said tubular core in braided fashion.
7. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said reinforcing material com-prises a multiplicity of yarns disposed on said core with half of said yarns running in a spaced apart, clockwise direction and the other half of said yarns running in a spaced apart, counter-clockwise direction, said yarns crossing but leaving generally diamond-shaped spaces therebetween.
8. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said reinforcing material is dis-posed longitudinally in said valleys.
9. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said thermoplastic material of said core and said coating are polyvinyl chloride.
10. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said thermoplastic material of said core is at least about 80% of the total weight of thermo-plastic material of said tubing.
11. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said outer surface of said coat-ing follows the contours of said formations of said core and said reinforcing material.
12. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, further comprising:
d) reinforcing material disposed on said outer sur-face of said coating (c); and e) an outer coating of thermoplastic material cover-ing the outer surface of said coating (c) and reinforcing mate-rial (d), said thermoplastic material of said outer coating be-ing directly and intimately bonded to said coating (c).
d) reinforcing material disposed on said outer sur-face of said coating (c); and e) an outer coating of thermoplastic material cover-ing the outer surface of said coating (c) and reinforcing mate-rial (d), said thermoplastic material of said outer coating be-ing directly and intimately bonded to said coating (c).
13. Reinforced flexible tubing of thermoplastic material as claimed in claim 1, wherein said tubing is ribbon-like in cross-section, substantially flat and the volume of the inside of said tubular core is substantially zero.
14. A method for manufacturing reinforced flexible tubing of thermoplastic material comprising the steps of:
a) providing a flexible tubular core of thermo-plastic material;
b) supplying reinforcing material to the surface of said core; and c) extruding, by means of an extruder, a thermo-plastic coating on the outer surface of said tubular core and said reinforcing material while creating a positive air pressure differential between the exterior and interior of said coating in said extruder during extrusion to urge said coating into intimate contact with said core and said reinforcing material.
a) providing a flexible tubular core of thermo-plastic material;
b) supplying reinforcing material to the surface of said core; and c) extruding, by means of an extruder, a thermo-plastic coating on the outer surface of said tubular core and said reinforcing material while creating a positive air pressure differential between the exterior and interior of said coating in said extruder during extrusion to urge said coating into intimate contact with said core and said reinforcing material.
15. A method for manufacturing reinforced flexible tubing as claimed in claim 14, wherein the step of providing a flexible tubular core includes extruding thermoplastic material through an annular die.
16. A method for manufacturing reinforced flexible tubing as claimed in claim 14, wherein the step of providing a flexible tubular core includes extruding said core through a die to pro-vide longitudinal ridges and valleys of generally triangular con-figuration around the external surface of said tube.
17. A method for manufacturing reinforced flexible tubing as claimed in claim 14, wherein the step of supplying reinforc-ing material includes winding at least two reinforcing yarns onto said core under very light tension, at least one said yarn being wound in a clockwise direction on said core and at least one said yarn being wound in a counterclockwise direction on said core, in a spaced apart manner to produce a braid effect, said yarns crossing and leaving generally diamond-shaped spaces therebetween.
18. A method for manufacturing reinforced flexible tubing as claimed in claim 14, wherein the step of extruding includes creating a positive air pressure differential by vacuum means.
19. A method for manufacturing reinforced flexible tubing as claimed in claim 14, further comprising flattening said coat-ing tubing into a substantially flat ribbon-like form.
20. A method for manufacturing reinforced flexible tubing as claimed in claim 14, further comprising:
d) supplying a second reinforcing material to the surface of said coated tubing; and e) extruding by means of a second extruder, a thermo-plastic coating on the outer surface of said coated tubing and said second reinforcing material while creating a positive air pressure differential between the exterior and interior of said second coating in said second extruder during extrusion to urge said coating into intimate contact with said coated tubing and said second reinforcing material.
d) supplying a second reinforcing material to the surface of said coated tubing; and e) extruding by means of a second extruder, a thermo-plastic coating on the outer surface of said coated tubing and said second reinforcing material while creating a positive air pressure differential between the exterior and interior of said second coating in said second extruder during extrusion to urge said coating into intimate contact with said coated tubing and said second reinforcing material.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000440447A CA1209493A (en) | 1983-11-04 | 1983-11-04 | Flexible tubing and apparatus for and method of manufacturing same |
| CA000515733A CA1227313A (en) | 1983-11-04 | 1986-08-11 | Flexible tubing and method of manufacturing same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000440447A CA1209493A (en) | 1983-11-04 | 1983-11-04 | Flexible tubing and apparatus for and method of manufacturing same |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000515733A Division CA1227313A (en) | 1983-11-04 | 1986-08-11 | Flexible tubing and method of manufacturing same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1209493A true CA1209493A (en) | 1986-08-12 |
Family
ID=4126446
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000440447A Expired CA1209493A (en) | 1983-11-04 | 1983-11-04 | Flexible tubing and apparatus for and method of manufacturing same |
| CA000515733A Expired CA1227313A (en) | 1983-11-04 | 1986-08-11 | Flexible tubing and method of manufacturing same |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000515733A Expired CA1227313A (en) | 1983-11-04 | 1986-08-11 | Flexible tubing and method of manufacturing same |
Country Status (1)
| Country | Link |
|---|---|
| CA (2) | CA1209493A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10744696B2 (en) | 2017-02-17 | 2020-08-18 | Fermatex Vascular Technologies, Llc | Reinforced coreless tube extrusion systems and methods |
-
1983
- 1983-11-04 CA CA000440447A patent/CA1209493A/en not_active Expired
-
1986
- 1986-08-11 CA CA000515733A patent/CA1227313A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10744696B2 (en) | 2017-02-17 | 2020-08-18 | Fermatex Vascular Technologies, Llc | Reinforced coreless tube extrusion systems and methods |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1227313A (en) | 1987-09-29 |
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