CA1097874A - Helically wound hose from co-extruded profile with reinforcing ribs interlocked at adjacent convolutions - Google Patents

Abstract

ABSTRACT
A strip is provided for forming a flexible hose having resistance to radial crush from bonded and interlocked helically wound convolutions of the strips which is formed as a plastic co-extrusion. The co-extruded pro-file of the strip is defined by a pair of matable rib components which are joined by a web. The rib components are to be bonded, sealed and interlocked together at adjoining convolutions of the profile not only to form the hose but also to form a composite rib integrated into the hose for resisting radial crushing and axially directed deformation forces exerted on the hose. The composite rib is formed from a material having a hardness which is greater than that of at least a part of the web for rendering the rib with a relative-ly stiff bend resistance characteristic and the web with a relatively soft and flexible characteristic. The web itself may be a co-extrusion of two materials placed in series, or in parallel as a laminate, or a combination thereof. If a laminate, one of its materials may be the same as that of the rib but much thinner so as to provide a larger surface area for greater bond-ing or adhesion among the several parts of the extruded profile. Different materials, especially in a laminate, enable the hose to be tailored for spe-cific uses and environments which come into contact with either or both the inside and outside of the hose.

Description

1~97874 This is a division of Canadian Patent Application Serial No. 276498, filed April l9, 1977, entitled "~lelically Wound Hose from Co-extruded Profile with Reinforcing Ribs Interlocked at Adjacent Convolutions".
The present invention relates to a strip for use in forming a flex-ible hose from helically wound convolutions of said strip, as well as a method for fabricating such strip.
While the present invention was originally conceived as being for use in the production of an all-plastic equivalent of solid or stranded wire--reinforced vinyl hose, it is to be understood that this original concept is adaptable to the general class of flexible hoses. Nevertheless, ~o provide a background to the present invention, it will be useful to discuss some aspects of its development.
As is well known in the art, a wire-reinforced vinyl hose comprises in general a hard rib of wire, with or without a plastic casing, which is sur-rounded by or connected to a relatively thin and/or flexible web. Such a hose is, by one conventional method, fabricated by winding the wire about a support-ing mandrel, over which the web is placed such as by a shrink-fit, wrapping or acombination thereof. While such a construction forms a flexible and dur-able hose, certain drawbacks result therefrom. First, it is not possible to fabricate such a hose in continuously extended lengths because a mandrel is required for supporting the wire about which the web is placed. Thus, one limitation primarily relates to the length to which a mandrel can reasonably be made. Of course, mandrels can be made to any desired length, so long as there is proper space and support for the mandrel; however, the problem is one of reasonableness. The second limitation is one of cost. Wire has become very expensive and, as a result, such a hose becomes less competitive with other hoses. Secondary cost limitations are the requirement for two or three ~ components comprising the wire, whether bare or plastic covered, and the web .~ - 1 -, :

~' ' '. ' :
' : .

~ ~097874 which must be placed thereover. A further cost is the increase in handling fabrication which is required.
Several efforts have been made to overcome the above problems as illustrated, for example, in United States Patents 3,890,181 of Stent et al, issued June 17, 1975 and 3,910,808 of Steward, issued October 7, 1975. In the former patent, a strip of first plastic material is extruded along with a rein-forcing element of a second plastic material. The strip is wound into a helix around a driven mandrel and bonded at adjacent turns together by pressure and heat or solvent. At the same time, the reinforcing element is wound about the helix of the first plastic material in spaced apart helical turns impressed into and partially embedded within the strip. While such a process is stated to permit the use of different plastic materials for achieving any desired hose characteristics, one difficulty is the ability to maintain definite and advantageous shapes, leading to distortion, as a result of assemb]y of the hose during the semi-molten condition of its component materials.
Patent 3,910,808 describes a plastic strip having a longitudinal rib in which one edge of each convolution overlaps and is heat bonded to an edge of a preceding convolution, with the rib being on the exterior of the thus-formed tube. Since such a hose is formed of a single material, its rib strength is derived from the mass of material necessary to obtain the desired resistance to radial crush. Accordingly, one major problem is the cost resul-ting from the mass of material needed for the rib. It also is subject to similar assembly distortion problems as with the previously described hose.
In view of the above problems with the prior art, a different approach involved use of the profile shown in United States Patent 3,255,780 of Peras, issued June 14, 1966 in which its axially extending base planar leg was lengthened Further prior art of interest, United States Patent 3,199,541 of :::

~~~
10~787~

Richitelli, issued August lO, 1965 describes a flexible hose ~hich is formed from a helically arranged elongated strip in which adjacent convolutions are interlocked by opposed mating male and female connecting elements on the strip.
As least one of the male and female connecting elements is said to have a com-posite structural formation defined in part by the strip and in part by a resinous plastic material substantially stiffer than the strip material. The resinous plastic material is said to contribute to the crush resistance of the hose. Flexibility, however, is obtained from a radially extending leg using the same flexible loop concept described in above-mentioned Patent 3J255~780.
Other prior art of interest herein includes a heavy section hose which the Assignee (Plastiflex Company International) hereof has sold for more than one year prior to the filing hereof under the trademark "Hi-Vac", which is an all plastic hose formed from two components. One component com-prises an extruded thick and heavy web section of general W-shape with a bel-low which imparts flexibility to the hose. Radially outwardly extending legs abut at adjacent convolutions of the W-shaped web section and are joined to-gether by a U-shaped heavy rib which is bonded to the radial legs, and the radial legs themselves are bonded to one another. The radial legs are re-quired in part for bonding purposes and for imparting resistance to radial crush, and in part for holding and handling of the web section during forma-tion of the hose, without which the web section could not be readily convolu-ted. The web section is of generally softer material than the rib, which has a greater hardness to enhance the abrasion resistance and the hoop strength of the hose. Notwithstanding the softness of the web section, the bellow centrally formed therein is required to impart flexibility to the hose.
; While such "Hi-Vac" hose functions very well for its intended pur-; pose, its purpose is primarily for resisting radial crush forces exerted when ~` internal pressures of the hose are reduced below that of atmosphere, i.e., , i i ., '`,`

:
, partial or complete vacuum, and for heavy duty industrial use where, for ex-ample, it is required to resist the weight of trucks and trailers and to con-vey heavy sludge. One general limitation is similar to those described above in that the bonding of the two radial legs together as well as the rib bonded thereto produces a very heavy and massive rib and a hose of large external diameter as compared to its internal diameter. The result precludes the ob-taining of a smaller outer to inner diameter. Another limitation of the hose is the requirement that its radially extending legs are needed for assembly of its components.
As a result of the above problems, it was necessary to investigate new approaches, from which the present invention arose.
Accordingly, in a broad aspect, the invention comprises a strip for use in forming a flexible hose from helically wound convolutions of said strip comprising: a co-extruded profile including means for defining a web and means for defining two sides continuously attached at the edges of said web means for forming an integral article of manufacture, said side means compris-ing material having a hardness higher than that of at least a part of said web means for rendering said side means with a relatively stiff and bend resistant characteristic and said web means with a relatively flexible characteristic.
In another broad aspect, the invention comprises a method for fabricating a strip for use in forming a flexible hose from helically wound convolutions of said strip comprising the steps of: co-extruding a profile having a web and two sides continuously attached at the edges of said web for forming an integral article of manufacture, in which said sides comprise mate-rial having a hardness higher than that of at least a part of said web for rendering said sides with a relatively stiff and bend resistant characteristic and said web with a relatively flexible characteristic.
Accordingly, a co-extruded profile is defined by a flexible web :~

, .

' : ~ , ' ,~ - :

9787~

having a pair of relatively rigid rib components extending along the opposite margins ~f the web. Both rib components have a higher hardness than that of the web so that, when the rib components are bonded and sealed together at adjacent convolutions to form a helically wound hose, the rib components form a rib having a relatively stiff and crush resistant characteristic with res-pect to that of the web which, as a result of its relative softness, imparts flexibility to the helically wound hose. Flexibility of the web is addi-tionally attained by making it as thin as possible.
The rib components may be of several shapes but preferably comprise a matable or interlocking physical construction so as to enable and maximize bonding therebetween at adjacent convolutions as well as to facilitate reten-tion of bonding materials during assembly of the strip into a hose. The web also may be of a single material or a co-extrusion of two or more materials placed in series, or in parallel as a laminate, or combinations thereof. In one embodiment, in order to maximize surface contact and bonding between the web material and the rib component material, the web is formed as a laminate in which one part of the laminate comprises a material which is the same as that of the rib components, albeit having a much thinner thickness~ even as compared to the remainder of the web.
The strip comprising a web joining one or more rib components com-prises a co-extrusion of materials. In the co-extrusion, it is preferred that the bonding of the component materials occurs in the same extruder die and prior to exit of the streams of the materials from the die thereby producing an integral extruded profile.
For purposes of definition, the mechanisms for co-extrusion include devices that combine the material streams before they exit the die as well as devices that perform the marriage outside it. While both types of co-extru-sion are useful to form the strip of the present invention, it is preferred that the co-extrusion formed depends on material union before leaving the die.
~ - 5 -`~:
,:

.~ .
~ ' ' ~ ' ' ' ' 1~9787~1 Lt is also preferred, for maintaining the defined shapes of the co-extruded profiles and commensurate with a minimum quantity of material for maximum hose strength, that the profiles first be extruded and cooled to fix the defined profile before being formed into the hose. In this regard, the rib components function additionally to facilitate handling of the strip when wound into the hose, to interlock the wound strip together, and to ensure proper location of the bonding material.
In drawings which il]ustrate embodiments of the invention, Figure 1 is a side elevation of a prior art hose having a smooth interior surface;
Figure 2 depicts a cross-sectional view or profile of a strip of material formed in accordance with one embodiment of the present invention which, when helically wound and bonded together at its adjacent convolutions, forms the hose illustrated in partial cross-section in Figure 2a;
Figure 3 is a cross-sectional view showing another embodiment of the present invention comprising an improved profile over that shown in Figure 2, allowing for a thinner overall wall thickness with good hoop strength and improved defined bonding area, with Figure 3a being a partial cross-section of a hose formed from convolutions of the profile of Figure 3;
Figure 4 cross-sectional view illustrates a further embodiment of the present invention whose strip profile is slightly modified from that shown in Figure 3, with the profile of Figure 4 being helically wound and joined at adjacent convolutions to form the hose shown in flexure in Figure 4a (last ` sheet of drawings);
Figures 5 and 6 ~last sheet of drawings) are cross-sectional views depicting other profiles formed according to the teachings of the present in-vention and used to enhance adhesion between the several parts thereof, with Figure 6 illustrating in phantom a partial section of an adjacent convolution ..;, :

` ~ ~

of the strip bonded to its prior convolution; and Figures 7-10 are cross-sectional views depicting additional embodi-ments of the present invention whose profiles are configured as further com-posites of web structure as laminates and series connections of different materialsJ as well as a laminate of both the web and rib components. ;~
As described above, Figure 1 comprises prior artJ which employs a profile somewhat similar to that shown in United States Patent 3J255J780 but which differs from the product of the patent. In contradistinction to utiliz-ing the flexibility of the loops required by Patent 3J255~780~ loops 12 of the 10 hose 11 shown in Figure 1 are completely filled with bonding material 14 about both sides of inner radial leg 16 so as to form a helically extending solid and heavy rib 18. This heavy rib mass gives good resistance to radial crush exerted on hose ll while elongated axially-extending base planar leg 19 is capable of flexing or bending to impart the entire hose with flexibility. Such a hose was in fact sold in 1973; however, because of cost problems due to the use of the relative large amount of plastic material required, it was not suf-~ ficiently competitive in the market.
- Accordingly, with reference to Figure 2, a strip 20 is shown in ; cross-section as a co-extruded profile, comprising a thin web or membrane 21 and a pair of relatively thicker rib components 22 and 23. As shown in Figure 2a, a length of strip 20 is helically coiled and is bonded by a bonding agent 24 at its helical convolutions 25 to form a hose 26. In this particular embod-iment, component 22 is substantially circular in cross-section while component 23 has a U-shaped hook cross-section to permit the configuration of component 22 to substantially fit within cavity 27 defined by the U-shaped hook of com-ponent 23.
While bonding agent 24 is il]ustrated as completely contacting all surfaces of components 22 and 23, this preferred arrangement is not abso-. .

~: h ,~ .
,' , ' ' : ' , , , :: , ', . :
' ' ~ ' ' . .. , ' , 1~7~r74 lutely necessary and the bonding can be less than complete if the service of hose 26 and its use permits a lesser degree of bonding. It is to be under-stood that this philosophy is as applicable to all embodiments of the present invention as it is to Figures 2 and 2a.
Components 22 and 23, when convolutedand bonded together at adjacent convolutions 25, form a composite rib 28. In the practice of the present invention, rib components 22 and 23 are formed of a material or composition which provides them with a greater hardness than that of the material of web 21. As a consequence, composîte rib 28, when bonded together and formed as a helix, is characterized by a high rigidity and a resistance to radial crush forces exerted on hose 26. Also, because of the relative stiffness and the solid construction of rib 28, the hose further resists axially imposed com-pressive forces arising from such negative pressures as establish0d by inter-nal vacuum. Thus, it limits contraction. The construction of the strip addi-tionally limits expansion and elongation due to application of positive inter-nal pressures.
It will be appreciated, of course, that web 21 (as well as all other ' webs of other embodiments hereof) is made as thin as possible also to enhance flexibility.
Furthermore, in this and all other embodiments of the present inven-tion, various components of strip 20 comprise a co-extruded web 21 and rib components 22 and 23 which, as-formed are bonded together to form an integral - strip. It is preferred to form this co-extrusion from the component plastic materials in the same die before the material streams exit the die which, because of the great pressures exerted on the materials, more efficiently and securely integrates the whole.
In this respect, while it is believed that co-extrusion and the technique for effecting a co-extrusion is known in the art, to ensure com-.:
~, - . . - , . .

. ~ .
~ ~ .

~097874 ple~eness of the present disclosure, reference is made to a publication entitled "Plastics Technology Magazine" published by Rubber/Automotive Divi-sion of Hartman Co~munications, Inc., a subsidiary of Bill Communications, Inc., 633 Third Avenue, New York, N.Y. 10017, which in Volume 22, No. 2, February 1976, pages 45-49 describes "Basic Co-extrusion Techniques".
In the practice of the present invention, because the web, such as web 21, is thin and flexible, e.g., being about 0.020 to 0.040 inches (0.05 `
to 0.1 cm) in thickness and 1/8 inch (0.32 cm) in width, it is difficult to handle an extrusion thereof, especially with edges that are flaccid.! Its flexibility and lack of rigidity is even more of a problem in the assembly of such a wispy web into a helically wound hose, notwithstanding the problem of lack of its resistance to radial crush, because of the great difficulties first in handling such a web when driving it through a winding head, second in bonding and interlocking its edges together when they have no rigidity, third in precisely locating bonding material between the edges, and fourth in ` maintàining the bond and edges from separating. In contrast to these problems encountered with the web due to its thin and flexible nature, more rigid and solid forms can be mOTe easily extruded into more easily handled profiles whose shapes can also be maintained with greater precision. Such relatively more rigid shapes can also be handled with greater ease in hose forming ma-chinery and be used to form crush resistant hose ribs. However, the required rigidity militates against hose flexibility.
The present invention not only has recognized the above features but has adapted these features to advantage in overcoming the problems inherent in the web. Specifically, since the web edges must be reinforced to avoid the above-noted handling and hose formation problems, the intended hose rib is divided into a pair of components which are respectively married to the web at its edges as a co-extrusion. Thus, the problem of flaccid and possibly _ 9 _ ., ~

- . , `

~.

. - ~
~097874 ill-defined web edges is overcome. In addition, because the rib components can be made of a relatively stiff material, they greatly facilitate handling in the hose forming machinery. Also, they can be precisely shaped by extru-sion into a form most conducive not only to enabling bonding material to be precisely placed between adjoining convolutions of themselves but also to ; forming an interlocked engagement also between themselves. The result, there-fore, is a hose whose constituent parts are tailored to maximize flexibility and resistance to radially directed crush forces. In addition, such other advantages as resistance to internally exerted negative and positive pressures and minimizing hose wall thickness are designable into the co-extruded profile, as will become hereinafter clearer.
Figures 3 and 3a show a strip 30 having rib components 32 and 33, respectively having rectangular configurations, as distinguished from the rounded configurations of Figures 2 and 2a. The rectangular configuration of rib component 32 is provided with a pair of rails 32a and 32b forming there-between a channel 32c. Rib component 33 is of generally rectangularly shaped hook configuration to provide an inner surface 37 into which component 32 fits.
- By virtue of channel 32c, a bonding agent 34 may be more easily and precisely located and deposited to insure adherence of the two rib components into a 20 single rib 38. As before, components 32 and 33 are formed of a material whose hardness is considerably greater than that of web 31 so that, upon the joining together of the components at adjacent convolutions 35, resistance to radial crush is provided by the composite rib while flexing is permitted by web 31.
The rectangular configuration of the rib components is conducive to defining a low profile of rib 38 to enable hose 36 to have the thinnest possible wall thickness with the least amount of material while preserving the other desired objects afforded by the invention. This low profile is preferably established by a narrow height h and a relatively wide width w so that the width is signi-: ,, .

. 1097~q4 ficantly greater than the height. It is to be understood, however, that the height and width dimensions may be adjusted as desired.
Referring now to Figures 4 and 4a, a strip 40 includes a web 41 and rib components 42 and 43 which are similar in configuration and numbering system as that of Figure 3, with the exception that rail 42a is slightly less in height than rib 42b to provide for slightly more space for bonding by a bonding material or agent, similar to agent 34 of Figure 3a. As shown in Figure 4a, hose 46 is flexed, so that upper web portions 41' are in tension and lower web portions 41 " are folded upon themselves to demonstrate the flexibility of the hose. Ribs 48 impart radial crush resistance and limit axial contraction, as before.
While the flexibility representation in Figure 4a is demonstrated primarily with respect to the extruded profile of Figure 4, it is to be under-stood that the illustration of Figure 4 is as apropos to all ambodiments of the present invention.
In Figure 5, web 51 is thickened at its ends Sla with respect to its middle 51b to increase the extent of its bonding surfaces 59 contacting with its rib components 52 and 53. In other respects, striy 50 is similar to that of the previous strips 20, 30, and 40.
Referring to Figure 6, still another configuration of the profile is shown as strip 60. Here, as compared to the embodiment of Figure 5, even greater surface areas 69a and 69b on both web 61 at ends 61a and components 62 and 63 at their surfaces 62a, 62b, 62c and 63a, 63b and 67 are provided to increase further the amount of adhering or bonding area. In addition, a space 64' for receipt of bonding material is defined by a pair of mutually offset portions and is formed by cavity 67 and channel 62c respectively of rib components 63 and 62 when mated at adjacent convolutions. Space 64' enables bonding material 64 not only to join the adjacent convolutions but ~0978-74 also to interlock them. 5uch a condition is of value, for example, when a bonding material of greater streng*h than the rib materials is needed. In other respects strip 60 is similar to the previously described strips.
Figures 7 and 8 are similar and depict strips 70 and 80 respectively.
In both configurations, rib components 72, 73 and 82, 83 are similar to those rib components shown before. Webs 71 and 81, however, are modified to provide laminates comprising materials 71a and 81a of different hardness respectively than materials 71b and 81b, for example, to alter the tear, puncture, tempera- -ture, etc. responses of the hose. In this configuration, materials 71b and 81b may be the same as their respective rib components 72, 73 and 82, 83.
Thus, during the co-extrusion of profiles 70 and 80, there is a larger area provided for bonding or adhering of the molecular structures of the plastic materials, that is, not just at the rib components as shown in prior embodi-ments but also along the entire lengths of webs 70 or 80, defined as the con-tacting surfaces of portions 71b and 81b. The only difference between Figures 7 and 8 is that in Figure 7 portion 71b is placed outwardly of web portion 71a while in Figure 8 the reverse is true. The difference between the two con-figurations may be used, for example, if a particular plastic material is required for a particular use. Thus, if detrimental harm were to be exerted upon the hose from the outside, Figure 7 would be used and, if from the inside, , Figure 8 would be preferred. Thus, the use of web parts 71b and 81b have twofold uses, as described above. In other respects, these embodiments are similar to that shown before.
In Figure 9, during co-extrusion a laminate 99 is provided over both rib components 92 and 93 as well as web 91, in order to extend the adhering surfaces of strip 90. Again, laminate 99 may be made of a special material ` suited to a particular environment and, accordingly, may be placed on the `- exterior of the profile as shown in Figure 9 or fully on its interior or fully ~ - 12 -,: :
.' ' .
~-: :, -. .
. . . " .

1097~74 on both its interior and exterior.
Referring now to Figure 10, all components are similar as before with the exceptio~ of web 101 which forms a composite of series connected web portions lOla and lOlb. This combination of web materials is generally pre-ferred if it is desired that one portion be colored differently from the other portion, primarily for aesthetic purposes. Other uses may suggest themselves to the user as required. It is to be understood, of course, with respect to Figures 7-9, that different colors may also be utilized for the additional laminae 71b, 81b and 99. It is to be further understood that any of the rib components and webs of all Figures l-lO may be colored differently, e.gA for aesthetic and/or coding purposes, or where color may enhance the environmental use of the hose, such as from heat or ultra-violet considerations.
In addition, two or more hoses having different diameters selected from any of the above embodiments, or combinations thereof amongst themselves or with other hoses~ may be combined, one inside the other, for any desired purpose. For example, a vacuum cleaner hose is known tUnited States Patent No. 3,965,526, of Doubleday, issued June 29, 1976, entitled "Suction Hose With ; Conductor Means For Electric Current," which comprises one hose inserted with-; in another hose between which an electrical cord extends for powering a power brush or other attachment at the floor end of the hose. Because some hoses of the present invention have a very low radial profile, e.g., those depicted in Figures 3a and 4a, resulting from the rectangular shaped ribs 38 and 48, it is possible to obtain an optional combination of maximum inner hose dia-meter and minimum outer hose diameter.
The materials of the various profiles or strips preferably comprise such suitable plastics which include, by way of example and not of limitation, the polyethylenes, polypropylenes, polyvinyl chlorides, and combinations there-of whose formulations may be varied or colored in accordance with end uses . , "

-:
~ .

~ lQ97874 and environments for which the hose is intended, or in accordance with the desired combinations of material streams used to form the several co-extruded profiles. Thus, the co-extrusions and laminates can be formed from or be of differently formulated plastic materials.
Although the invention has been described with reference to parti-cular embodiments thereof, it should be realized that various changes and modifications may be made therein without departing from the spirit and scope of the invention.

; 20 .

:
, .

,, ~
,' ~

i' ~ : ~ , - . .

- ;

Claims (26)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A strip for use in forming a flexible hose from helically wound convolutions of said strip comprising: a co-extruded profile including means for defining a web and means for defining two sides continuously attached at the edges of said web means for forming an integral article of manufacture, said side means comprising material having a hardness higher than that of at least a part of said web means for rendering said side means with a relatively stiff and bend resistant characteristic and said web means with a relatively flexible characteristic.

2. A strip as in claim 1 wherein said two side means have means respec-tively for defining interfitting configurations for enabling a substantially mating interconnection between said two side means at adjacent convolutions of said strip.

3. A strip as in claim 2 wherein said interfitting configuration means respectively comprise a circular configuration and a generally U-shaped hook configuration.

4. A strip as in claim 2 wherein said interfitting configuration means comprise a generally rectangular configuration and a generally rectangular-shaped hook configuration.

5. A strip as in claim 4 wherein said generally rectangular configura-tion further includes means for defining a channel therein for receiving in said channel means means for defining a bonding agent.

6. A strip as in claim 1 wherein said web means comprises a membrane which is significantly thinner than said side means to enhance the relative stiff and flexible characteristics respectively of said side means and said web means.

7. A strip as in claim 1 wherein the material of said co-extruded pro-file of said side means and said web means comprises differently formulated plastic materials.

8. A strip as in claim 1 wherein the material of said web means com-prises a co-extrusion of differently formulated plastic materials.

9. A strip as in claim 8 wherein said web means co-extrusion comprises a series connection of at least the two differently formulated plastic mate-rials extending between said two side means.

10. A strip as in claim 8 wherein said web means co-extrusion comprises a laminate of at least the two differently formulated plastic materials ex-tending in parallel between said two side means.

11. A strip as in claim 10 wherein said side means is formed from the same co-extrusion as that of said web means, and wherein the material of said side means comprises the same material as that of one of said plastic materi-als of said web means.

12. A strip as in claim 11 wherein said differently formulated materials have compatible molecular structures for enabling interfacial bonds and adhe-sion to and between all contacting surfaces of said side means and said web means.

13. A strip as in claim 12 wherein said differently formulated materials are selected from the group of plastics consisting of the polyethylenes, poly-propylenes, polyvinyl chlorides, and mixtures thereof.

14. A method for fabricating a strip for use in forming a flexible hose from helically wound convolutions of said strip comprising the steps of: co-extruding a profile having a web and two sides continuously attached at the edges of said web for forming an integral article of manufacture, in which said sides comprise material having a hardness higher than that of at least a part of said web for rendering said sides with a relatively stiff and bend resistant characteristic and said web with a relatively flexible character-istic.

15. A method as in claim 14 further comprising the step of forming said two sides with means respectively for defining interfitting configurations for enabling a substantially mating interconnection between said two sides at adjacent convolutions of said strip.

16. A method as in claim 15 further comprising the step of forming said interfitting configuration means respectively with a circular configuration and a generally U-shaped hook configuration.

17. A method as in claim 15 further comprising the step of forming said interfitting configuration means with a generally rectangular configuration and a generally rectangular-shaped hook configuration.

18. A method as in claim 17 further comprising the step of forming means for defining a channel in said generally rectangular configuration for receiv-ing a bonding agent in said channel means.

19. A method as in claim 14 further comprising the step of forming said web with a membrane which is significantly thinner than said sides to enhance the relative stiff and flexible characteristics respectively of said sides and said web.

20. A method as in claim 14 wherein said co-extruding step includes the step of constituting the material of said profile of said sides and said web with different plastic formulations.

21. A method as in claim 14 wherein said co-extruding step includes the step of co-extruding the material of said web from differently formulated plastic materials.

22. A method as in claim 21 wherein said web co-extruding step includes the step of series connecting at least the two differently formulated plastic materials extending between said two sides.

23. A method as in claim 21 wherein said web co-extruding step includes the step of laminating at least the two differently formulated plastic materi-als extending in parallel between said two sides.

24. A method as in claim 23 further including the steps of forming said sides from the same co-extrusion as that of said web, and formulating the material of said sides from the same material as that of one of said plastic materials of said web.

25. A method as in claim 24 further including the steps of constituting said differently formulated materials with compatible molecular structures and thereby interfacially bonding and adhering all contacting surfaces of said sides to and between said web.

26. A method as in claim 25 wherein said differently formulated materi-als are selected from the group of plastics consisting of the polyethylenes, polypropylenes, polyvinyl chlorides, and mixtures thereof.