GB1589130A

GB1589130A - Synthetic resin hose

Info

Publication number: GB1589130A
Application number: GB23204/78A
Authority: GB
Original assignee: Kakuichi Co Ltd
Current assignee: Kakuichi Co Ltd
Priority date: 1977-09-06
Filing date: 1978-05-26
Publication date: 1981-05-07
Also published as: IT7827305A0; JPS5440329A; FR2402147B1; DE2835344C2; IT1099050B; NL172362C; NL172362B; NL7808352A; FR2402147A1; AU3587778A; ZA782647B; DE2835344A1; AU508698B2

Description

(54) SYNTHETIC RESIN HOSE (71) We, KAKUICHI CO., LTD., of No. 1415, Midori-Cho, Nagano City, Japan, a company organized according to the laws of Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a synthetic resin hose, in particular a foldable and flat synthetic resin hose having a fibrous reinforcing member embedded therein.

As used in this specification the term "synthetic resin material" includes not only thermosetting and thermoplastic soft synthetic resin materials but also soft elastic materials such as rubber.

A synthetic resin hose of this type is so designed as to be readily adapted even to an extremely rough ground or road, thus enabling water supply or drainage only by being coupled to a required portion by a coupling means, and can be readily folded after use, thus affording easiness of carriage and storage. By virtue of these advantages, such synthetic resin hoses are applicable to various usages as fluid transportation hoses for water supply, water drainage, water distribution and waste-water treatment in various fields such as civil engineering works, construction works, agriculture, engineering and mining.

The synthetic resin hose should have, as prerequisites, the following characteristics in order to be serviceable for the above-described purposes.

1) The bore of the hose has a small thickness in comparison with the diameter thereof, from the viewpoints of saving of resources and economy.

2) The hose itself is flexible and light in weight for easiness of transportation and maintenance.

3) The hose is highly resistant to pressure, and does not undergo a large variation in size until being burst due to pressure exerted thereon, as a result of which meandering and torsion are prevented.

4) The hose can withstand a tensile force, bending force or torsional force, if such force should act thereon repeatedly.

5) The hose is highly weatherproof and highly resistant to wear.

Among these characteristics, the weatherproof and wear-resisting characteristics are dependent on inner and outer synthetic resin layers of the hose, and the other characteristics are closely related to the construction of a fibrous reinforcing member embedded in the hose. Having regard to the construction of a fibrous reinforcing member having a substantial influence on the above-described desirable characteristics of the synthetic resin hose, the strength compensation between warps and braiding yarns has not been clearly solved.

Various types of synthetic resin hose having a fibrous reinforcing member embedded therein and having an increased pressure-resistance strength have hitherto been proposed.

Among these synthetic resin hoses, the most used is one in which the reinforcing member is formed of braiding yarns mutually intertwined at a braiding angle of 54"44' with respect to the axial direction of the hose, which is an angle of equilibrium between braiding yarns in the absence of warps. A hose thus arranged is well balanced in construction, thus resisting deformation due to stress which might be caused by a fluid pressure acting on the hose in the longitudinal direction as well as in the circumferential direction thereof, with freedom of fluctuation in size except for elongation of braided yarns or freedom of torsion about the axis of the hose, when an internal pressure is exerted thereon. However, because the mesh of the braided yarns is biased with respect to the axis of the hose, the braided yarns tend to freely elongate in the axial direction of the hose, and hence have little or nothing to contribute to providing an increased tensile strength for the hose, although the tensile force acts on the hose, particularly when such a hose is used while being pulled lengthwise thereof. The frequent bending and stretching of the hose during service causes undesirable movement of the reinforcing member between the outer and inner synthetic resin layers of the hose, and hence separation of the reinforcing member from the inner and outer resin walls occurs, thus resulting in breakage of the hose. In addition, a tensile force and bending force acting on the hose cause a change in the braiding angle in the reinforcing braided member, and as a result braided reinforcing yarns suffer from friction repeatedly at the intercrossings thereof, thus shortening the service life of the hose. Because of the above-described shortcomings, the necessity arises of increasing the thickness of the inner and outer layers of the hose so as to increase the tensile strength of the hose, and to prevent elongation of the reinforcing member in the axial direction of the hose or a change in the braiding angle of the braided yarns. The above requirement is partly met by providing a hose having an increased wall thickness, but at the expense of sacrificing the foldable characteristic prerequisite to such a hose.

To solve the above drawbacks, a flat synthetic resin hose has been developed as disclosed in British Patent No. 1,452,850, wherein the reinforcing member is comprised of braided yarns of the same construction as described above and a plurality of core yarns, namely warps, intertwined with the braided yarns in the axial direction of the hose. With this synthetic resin hose, the reinforcing member itself acts to resist elongation in the axial direction of the hose, thus enabling the thickness of the inner and outer layers of the hose to be reduced. Since the warps are braided with respective wefts over the entire peripheral surface of the inner wall of the hose, these two woven members are maintained in register with each other even when pressure is applied to the hose, whereby a uniform pressure-resisting ability is provided for the hose, and hence the hose no longer suffers from torsion. On the other hand, this synthetic resin hose, because of the arrangement of the reinforcing member in which warps intercross with braided wefts or yarns, has the following drawbacks. First, the number of warps cannot be determined independently of the number of braided yarns, but should be less than one-half of the total number of braided yarns. This necessarily imposes a limitation on designing hoses of different types which meet the purposes of different applications. The reinforcing yarns suffer from friction due to the bending force acting on the hose, which is responsible for lowering the durability of the hose.

Furthermore, since the reinforcing yarns are intertwined with each other in a curved fashion, an increased extensibility of the reinforcing member, an increased thickness of the reinforcing member itself and an extreme roughness of the surfaces thereof are bound to result, thus also imposing a limitation on reducing the wall thickness of the hose.

There is known another type of synthetic resin hose which is somewhat similar to the aforesaid synthetic resin hose having warps, but is different from the latter in having a reinforcing member of a non-braided structure, which consists of warps and wefts inclined positively and negatively with respect to the axis of the hose such that these three kinds of reinforcing yarn, namely warps, positively inclined yarns and negatively inclined yarns, are maintained independent of one another, without being intertwined with one another. This type of synthetic resin hose is free from the drawbacks encountered with the aforesaid synthetic resin hose having warps. However. this type of synthetic resin hose has the following drawbacks. which originate from the fact that all the reinforcing yarns remain unbraided. Because of lack of curving of the reinforcing yarns and low extensibility thereof, there results the difficulty in expansion of the opening in the base portion of the hose as well as in insertion or fitting of a metal coupling in the opening of the hose. When a bending stress or torsional stress acts on the pipe, the unbraided reinforcing yarns which lack extensibility are liable to move between the inner and outer synthetic resin layers sandwiching these yarns therebetween, leading to the separation of these yarns from the inner and outer walls of the hose. This curtails the service life of the hose.

As is apparent from the foregoing description, known synthetic resin hoses having a reinforcing member have inherent advantages and disadvantages, but there is no hose that has all of the above-described desirable characteristics.

The present invention aims to provide a foldable and flat and synthetic resin hose having an improved reinforcing member embedded therein, which has all of the above-described desirable characteristics and is readily alterable in design so as to be suitable for the various application purposes.

The present invention provides a foldable and flat synthetic resin hose, comprising an outer layer and an inner layer each made of a synthetic resin material, and a fibrous reinforcing member sandwiched between the inner and outer layers, the said reinforcing member consisting of a plurality of warps drawn in the axial direction of the hose and arranged circularly in cross-section around the outer peripheral surface of the inner layer and a plurality of braiding yarns disposed on the outer surface of the said plurality of warps in an overlying fashion, the said warps and braiding yarns being bonded together by a bonding agent at the contacts therebetween to form a tubular fibrous reinforcing body, the braiding yarns being braided with each other at an angle within a range of 60 to 80" with respect to the said warps, and the said inner and outer layers being bonded together through the mesh of the fibrous reinforcing member into an integral body, wherein the pressure-resisting strength Px in the axial direction of the hose is substantially the same as or more than the pressure-resisting strength P, in the circumferential direction thereof, and wherein the ratio of the number of warps N; to the number of braiding yarns N is within a range of 1-10.

Heretofore, it has been customary that warps are only used as a reinforcing member for - increasing the tensile strength in the axial direction of a tubular body or for the purpose of preventing elongation of a tubular body which occurs at the time of moulding thereof.

According to the present invention, a balanced braiding angle that allows the warps to effectively act to impart an increased pressure-resisting strength to the hose has been theoretically proven. This makes it easy to determine the pressure resisting strength of a hose, and also makes clear the permissable range of modification of a hose that meets the application purposes. At the same time, the specific strength of a hose, namely the pressure-resisting strength per unit number of yarns, will greatly increase. Thus, there is obtained a foldable and flat synthetic resin hose having reduced wall thickness and weight, increased pressure-resisting strength and durability, and low fluctuation in size during service, which can prevent meandering and torsion, as compared with the previously known hoses. In order to manufacture synthetic resin hoses of different type to be suitable for the various applications, all that is necessary is to increase or decrease the number of warps, with the number of braiding yarns remaining unchanged, or to change the braiding angle of braiding yarn. According to the present invention, there is no need to remold the manufacturing equipment, so that such expensive remolding for changing the number of braiding yarns may be avoided.

The primary and important characteristic of the present invention resides in that the reinforcing member is formed by braiding yarns and warps disposed inwardly of the braiding yarns independently thereof and adhered thereto. As a result, an optimum extensibility is provided for the reinforcing member, thus facilitating insertion or fitting of a metal coupling in the opening in the base portion of the hose. The number of warps may be optionally determined independently of the number of braiding yarns. In addition, the warps may be arranged at an equi-angular spacing from one another in the circumferential direction of the hose, or alternatively may be locally distributed. Since an inner layer of synthetic resin is formed on the inner surface of a comparatively flat warp member, the unevenness of the inner wall surface of the hose and hence the resultant fluid resistance may be greatly diminished.

A bonding agent is suitably applied to the warps beforehand at the time of manufacturing the synthetic resin hose, so that the warps are bonded by the bonding agent to the braiding yarns at the crossings therebetween, and also the warps may be firmly bonded to the inner layer of synthetic resin itself. The strong and firm bonding of the warps to the braided yarns as well as to the inner layer of synthetic resin effectively prevents unwanted separation of the warps from the inner layer of the hose which has been occasionally experienced with a hose having a non-braided reinforcing member at the time of fitting a metal coupling in the opening of the hose.

The invention will be further described, by way of example only, with reference to the accompanying drawings, wherein: Figure 1 is a perspective view of a synthetic resin hose according to the present invention; Figure 2 is a fragmentary view of a reinforcing member of the synthetic resin hose; Figure 3 diagrammatically shows the adhesion of one yarn to another in the reinforcing member; Figure 4 is a graph representing the relationship between the ratio of the total number of warps to the total number of braiding yarns (Nx/Ny) and the braiding angle ; and Figure 5 is a graph representing the relationship between the pressure-resisting strength P and the braiding angle , using as a parameter the ratio of the number of warps to the number of braiding yarns.

Figure 1 shows a synthetic resin hose 1 of the most general type according to the present invention, which is comprised of an inner layer 2, an outer layer 3, both of which may be formed of a soft polyvinyl chloride. and a reinforcing member 4 which may be formed of filaments of a polyvinyl alcohol. The reinforcing member 4 consists of a plurality of warps 5 drawn in the axial direction of the hose to be formed and disposed circularly around the outer peripheral surface of the inner layer 2, and a woven member 6 formed by braiding braiding yarns on the outer periphery of the warps arranged in the tubular shape so as to be inclined positively and negativelv with respect to the axis of the hose being formed. The synthetic resin material for the inner and outer layers 2 and 3 is preferably polyvinyl chloride, but, urethane resin. nitrile rubber or chloroprene rubber may be utilized in accordance with the purpose of use of the hose. Yarns 5 and 6 forming the reinforcing member are preferably filaments of a polyvinyl alcohol, although filaments of a polyester, synthetic fibers of a polyamide or polyacryl nitrile, semi-synthetic fibers such as an acetate, regenerated fibers such as a cellulose, natural fibers such as cotton, or a mixture of these fibers may be suitably used instead. The inner layer 2 and outer layer 3 are bonded together through the mesh of the braided yarns of the reinforcing member 4 into an integral body.

As is clear from Figure 2. the braiding yarns 6 are braided with each other by alternating a positively biased yarn with a negatively biased yarn. On the other hand, the warps 5 are maintained independent of the braided yarns 6 (i.e. without being intertwined with these yarns) and are bonded thereto in an underlying fashion. The bonding of the warps to the braided yarns is achieved by a bonding agent. which has been applied to the warps beforehand, in the manner shown in Figure 3.

In a synthetic resin hose having a reinforcing member consisting of braided yarns and warps, the following equations are obtained from the condition in which equilibrium between the fluid internal pressure acting on the hose and the stress resisting thereto is established; 4 Px = (Nx#α + Ny# cos ) ...(1) and 2 Py = (Ny# tan sin ) ...(2).

#D2 wherein Px is the pressure-resisting strength in the axial direction [kg/cm2]; Py is the pressure-resisting strength in the circumferential direction [kg/cm2]; D is the diameter of the fibrous reinforcing hose [cm]; Nx is the number of warps [number]; Ny is the sum of positively and negatively biased braiding yarns [number]; #α is the strength of the warp [kg/one warp]; # is the strength of the braiding yarn [kg/one yarn]; is the braiding angle of braiding yarns with respect to the warps [degree]; and # is the conventional constant of the ratio of circumference to diameter.

The condition in which Px is greater than or equal to Py is represented as; Px # Py ...(3).

The following equation (4) is derived from equations (1). (2) and (3).

4 2 (Nx#α + Ny# cos ) # Ny# tan sin ...(4) #D2 #D2 This equation (4) can be modified as follows; Nx # # (tan sin - 2cos ) Ny 2#α Nx # , sin2 - 2cos2 # . ..(5) Ny 2#α cos Assuming. for simplification, that the warps and braiding yarns are of the same material (#α = # = #). then the equation (5) will be obtained as follows: Nx sin2 - 2cos2 # ....(6).

Ny 2cos And the equations (l) and (2) will respectivelv be: 46 @x = (Nx + Nycos ) ..(7) Py = Nytan sin ...(8).

#D2 From the equation (6). it will be understood that the varn braiding angle (3 relative to the ratio of the number of warps to the number of braiding yarns is primarily determined. which braiding angle can ensure that the pressure-resisting strength in the axial direction of the hose is greater than or equal to that in the circumferential direction thereof. There is shown in Figure 4 a graph corresponding to the equation (6). From Figure 4. it is seen that if Nx/Ny = 0, more specifically if the braiding angle is 54044 in the absence of warps. there is obtained a pressure-resisting strength balanced in both the axial and circumferential directions. Although demonstration in detail is not given herein, if the amount of yarns being used for the reinforcing member, wherein Nx/Ny and are determined by referring to the point on the plot of Figure 4. is usually constant. and if @ represents a length of yarn for producing one meter of a hose reinforced by the plurality of warps in the axial direction and a plurality of braiding yarns disposed on the outer peripheral surface thereon. then there is necessarily a constant amount of yarns which is given by the following equation; #D2P @ = 75 [cm].

# This amount of yarns thus determined is the minimum amount of yarns necessary for providing a pressure-resisting strength P required.

There is shown in Figure 5 a graph corresponding to the equations (7) and (8). From this plot, it is seen that the points of intersection of a curve Py with curves Px corresponding to the values of Nx/Ny represent the yarn braiding angles at which the balance in pressure resisting strength in the axial and circumferential directions is established, and a pressure resisting strength P (= Px. Py).

It is for the following reasons that the yarn braiding angle , in the present invention, is taken in the range of from 60 to 85 . If < 60 . then Nx is small as is apparent from Figure 4, and a hose could be reinforced to have a sufficiently high pressure-resisting strength, but would not satisfactorily withstand a tensile force acting on the hose in the axial direction thereof. as in a known synthetic resin hose. wherein braiding yarns alone are woven with each other at an angle of dwell of 54 44' in the absence of warps. As is apparent from Figure 5, the hose is not so high in pressure resisting strength. On the other hand. if > 85 . Nx is too great, and the resultant increase in flexural rigidity of the hose impairs the flexibility of the pipe, with the impossibility of being bent or folded. In the latter case, an increased pressure-resisting strength is provided. but the mesh of braided yarns becomes fine, leading to the difficulty in bonding the inner layer 2 to the outer layer 3. Taking the above in consideration, the range of braiding angles has been determined.

In order for the warps to positively serve for providing an increased tensile strength for the hose. it is desirable that the varn braiding angle be smaller than the angle of equilibrium obtained from Fieure 4 or 5. or otherwise the value of N, be larger than the value determined at the angle of equilibrium. although it is dependent on the ratio of the pressure-resisting strength to the tensile strength. In the reinforcing member of the synthetic resin hose, Nx/Ny and are determined by referring to a single point included in the aforesaid range of angles in the direction of the transverse axis in Figure 4 or 5 and included in an upper zone defined bv a curve of Figure 4 or a curve of Figure 5 representing the pressure-resisting strength in the circumferential direction.

Examples of a reinforcing member of a synthetic resin hose according to the present invention are given in Table I.

It will be understood from the foregoing description that there is obtained according to the present invention a synthetic resin hose suitable for various purposes and superior in characteristics to previously known synthetic resin hoses.

TABLE 1 Braiding yarns Warps (filament (filament yarns of yarns of Kinds Examples Inner polyester) polyester) Ratio of of hose of use diameter strength Fineness Braiding Number Fineness Number of braiding Bursting of yarn angle of yarns of yarn of yarns yarn to warp pressure (denier) (degree) (Ny) (denier) (Nx) (Nx#α/Ny# ) (kg/cm2) High Mining 65 1000 d/3 73.0 48 1000 d/2 100 1.39 40.7 pressure or fire 78 1000 d/3 77.5 48 1000 d/3 100 2.08 39.8 hose hose 105 1000 d/4 79.5 48 1000 d/3 160 2.50 35.3 Medium Drain hose 65 1000 d/1 77.0 36 1000 d/1 70 1.94 13.7 and low for use pressure in civil 78 1000 d/1 80.0 36 1000 d/1 95 2.64 12.6 hose engineering works 105 1000 d/2 78.0 36 1000 d/2 80 2.22 11.5 High pres- 65 1000 d/3 73.0 48 1000 d/3 125 2.60 40.7 sure hose Irrigation 78 1000 d/3 77.5 48 1000 d/5 120 4.17 39.8 increased hose 105 1000 d/4 79.5 48 1000 d/5 180 4.69 35.3 in tensile strength (Note) #α and # are equal if yarns of the same fineness are used. If yarns of different fineness are used, the ratio of strength of braiding yarn to warp may be substituted by a ratio denier of the former to the latter.

Claims

WHAT WE CLAIM IS:

1. A foldable and flat synthetic resin hose. comprising an outer layer and an inner layer each made of a synthetic resin material. and a fibrous reinforcing member sandwiched between the inner and outer layers. the said reinforcing member consisting of a plurality of warps drawn in the axial direction of the hose and arranged circularly in cross-section around the outer peripheral surface of the inner layer and a plurality of braiding yarns disposed on the outer surface of the said plurality of warps in an overlying fashion, the said warps and braiding yarns being bonded together by a bonding agent at the contacts therebetween to form a tubular fibrous reinforcing body, the braiding yarns being braided with each other at an angle ss within a range of 60 to 80 with respect to the said warps, and the said inner and outer layers being bonded together through the mesh of the fibrous reinforcing member into an integral body, wherein the pressure-resisting strength Px in the axial direction of the hose is substantially the same as or more than the pressure-resisting strength Py in the circumferential direction thereof. and wherein the ratio of the number of warps Nx to the number of braiding yarns NN is within a range of 1-10.

2. A synthetic resin hose as claimed in claim 1. wherein the bonding agent is applied to the overall length of the respective warps. whereby the warps and braided yarns are bonded together by the bonding agent into the tubular fibrous reinforcing body. and the warps are firmly and closely bonded to the said inner layer of synthetic resin by means of the bonding agent.

3. A synthetic resin hose as claimed in claim 1 or 2, wherein: if Nx is the number of warsp; #α, is the strength of the warp; Ny is the number of braiding yarns; #ss is the strength of the braiding yarn; and ss is the yarn braiding angle; then the following equation applies; Nx #ss sin2ss - 2cos2ss @ @ Ny = 26(L cos(3

4. A foldable and flat synthetic resin hose according to Claim l substantially as herein described, with reference to. and as shown in, Figures 1 to 3 of the accompanying drawings.