CN114811207B

CN114811207B - Method for determining specification of metal wire for hose and hose

Info

Publication number: CN114811207B
Application number: CN202210054779.XA
Authority: CN
Inventors: 末藤亮太郎
Original assignee: Yokohama Rubber Co Ltd
Current assignee: Yokohama Rubber Co Ltd
Priority date: 2021-01-28
Filing date: 2022-01-18
Publication date: 2023-11-10
Anticipated expiration: 2042-01-18
Also published as: JP2022115307A; CN114811207A

Abstract

The application provides a specification determining method of a metal wire for a hose, which can simply select a metal wire with proper specification for effectively improving the pressure durability of the hose, and a hose with a reinforcing layer composed of the metal wire with proper specification. Based on the ratio (Ta/Tx) of 0.2% yield strength (Ta) relative to the maximum tensile stress (Tx) of the metal wire (4) forming the reinforcing layer (3) of spiral structure interposed between the inner surface layer (2) and the outer surface layer (5) of the hose (1) and the result of the pressure endurance test of repeatedly applying an internal pressure to the hose (1) under the condition of a predetermined internal pressure, an appropriate range (R) of the ratio (Ta/Tx) in which the result of the pressure endurance test satisfies a preset target value is grasped, and the metal wire (4) having the grasped appropriate range (R), that is, the specification of the ratio (Ta/Tx) of 0.85 to 0.99 is selected as a member forming the reinforcing layer (3) of the hose (1).

Description

Method for determining specification of metal wire for hose and hose

Technical Field

The present application relates to a method for determining a specification of a wire for a hose and a hose, and more particularly, to a method for determining a specification of a wire for a hose, which can easily select a wire of an appropriate specification for improving pressure durability of a hose more effectively, and a hose having a reinforcing layer formed of a wire of an appropriate specification.

Background

In a hydraulic hose, a vehicle air conditioning hose, or the like, a reinforcing layer having a spiral structure, for example, formed by winding a metal wire into a spiral shape, is interposed between an inner surface layer and an outer surface layer in order to withstand a high internal pressure. In order to evaluate the pressure durability of the hose, a pressure durability test (pulse test) in which a predetermined internal pressure is repeatedly applied to the hose is performed (for example, see paragraphs 0022 to 0026 of patent document 1).

On the other hand, a fatigue test was performed on the wire on which the reinforcing layer was formed, and the degree of the tensile durability of the wire alone was grasped. For example, it is conceivable to select a wire having sufficient tensile durability by applying a tensile force to the wire under the use condition of the hose. Then, a pulse test was performed on a hose having a reinforcing layer formed of a selected metal wire to confirm whether the hose had the aimed pressure durability. Since the fatigue test of the wire alone requires a long time and labor, there is room for improvement in simply selecting a wire of an appropriate specification that can effectively improve the pressure durability of the hose.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2004-060747

Disclosure of Invention

Problems to be solved by the application

The purpose of the present application is to provide a specification determination method for a metal wire for a hose, which can easily select a metal wire of an appropriate specification that can more effectively improve the pressure durability of the hose, and a hose having a reinforcing layer formed of a metal wire of an appropriate specification.

Means for solving the problems

In order to achieve the above object, a method for determining a specification of a metal wire for a hose according to the present application is a method for determining a specification of a metal wire for forming a reinforcing layer having a spiral structure interposed between an inner surface layer and an outer surface layer of a hose, wherein a proper range of the ratio, in which a result of a pressure durability test meets a preset target value, is grasped based on a ratio of 0.2% yield strength to a maximum tensile stress of the metal wire and a result of a pressure durability test in which an internal pressure is repeatedly applied to the hose under a predetermined internal pressure condition, and a metal wire having the specification of the ratio in the proper range grasped is selected as a member for forming the reinforcing layer of the hose.

In a hose comprising an inner surface layer and an outer surface layer which are coaxially laminated, and a reinforcing layer having a spiral structure formed of a metal wire interposed between the inner surface layer and the outer surface layer, the ratio of 0.2% yield strength of the metal wire to the maximum tensile stress is 0.85 or more and 0.99 or less.

Effects of the application

According to the specification determining method of the metal wire for hose of the present application, the ratio of 0.2% yield strength to the maximum tensile stress of the metal wire is used. Since this ratio is closely related to the degree of pressure durability of the hose, an appropriate specification of the metal wire for more effectively improving the pressure durability of the hose can be selected based on this ratio. Further, since this ratio can be obtained by performing a tensile test of the wire alone, a fatigue test of the wire alone is not required, and a wire of an appropriate specification can be selected easily.

According to the hose of the present application, since the reinforcing layer is formed by using the metal wire having the specification of 0.85 to 0.99, the pressure-resistant durability of the hose can be improved more effectively.

Drawings

Fig. 1 is an explanatory view of an embodiment of a hose according to the present application, partially cut away.

Fig. 2 is an explanatory view illustrating the hose of fig. 1 in a cross-sectional view.

Fig. 3 is a graph illustrating a relationship between tensile stress and tensile strain of the metal line of fig. 1.

Fig. 4 is a graph schematically illustrating a relationship between a ratio of 0.2% yield strength to a maximum tensile stress of a wire and a result of a pressure durability test of a hose.

Fig. 5 is a graph showing the relationship illustrated in fig. 4 as an actual measurement value.

Description of the reference numerals

1: flexible pipe

2: inner surface layer

3 (3 a, 3b, 3c, 3 d): reinforcing layer

4: metal wire

5: outer surface layer

6: interlayer rubber layer

CL: hose axle center

Detailed Description

The specification determining method of the metal wire for a hose and the hose according to the present application will be described below based on the embodiments shown in the drawings.

The embodiment of the hose 1 of the present application illustrated in fig. 1 and 2 is used as a so-called hydraulic hose or an air conditioning hose for circulating a refrigerant of a vehicle air conditioner. The hose use pressure is, for example, a hose 1 belonging to the category of high-pressure hoses of 15MPa to 50 MPa. The outer diameter of the hose is, for example, 20mm to 75mm, and the inner diameter of the hose is, for example, 10mm to 55 mm.

The hose 1 is laminated with an inner surface layer 2, a reinforcing layer 3 (3 a, 3b, 3c, 3 d), and an outer surface layer 5 coaxially in this order from the inner peripheral side. The interlayer rubber layer 6 is interposed between the reinforcing layers 3 stacked adjacently in the radial direction of the hose 1. The single-dot chain line CL of the drawing indicates the hose axis.

The inner surface layer 2 and the outer surface layer 5 are formed of resin or rubber. The inner surface layer 2 and the outer surface layer 5 may have a multilayer structure of resin and rubber, and may be composed of only rubber, or may be composed of only resin. For example, the inner surface layer 2 may have a multilayer structure in which a rubber layer is laminated on the outer peripheral surface of a resin layer. In the inner surface layer 2 and the outer surface layer 5, an appropriate material is selected according to the performance required for the hose 1, and an appropriate layer thickness is set. The material used is not particularly limited, and for example, butyl rubber, nitrile rubber, fluororubber, chlorinated polyethylene, etc., nylon 11, nylon 6-66, EVOH, etc., are used for the inner surface layer 2. The outer surface layer 5 is made of EPDM, silicone rubber, natural rubber, butyl rubber, ethylene acrylic rubber, or the like.

The layer thickness of the interlayer rubber layer 6 varies depending on the outer diameter of the hose, and is, for example, 0.1mm or more and 0.5mm or less. The interlayer rubber layer 6 integrally bonds the reinforcing layers 3 stacked adjacently in the radial direction, and functions as a buffer material for the reinforcing layers 3, and also functions as a barrier for preventing permeation of gas, moisture, and the like. Examples of the rubber type of the interlayer rubber layer 6 include acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and a mixed rubber thereof.

In this embodiment, the hose 1 is provided with 4 reinforcing layers 3. The reinforcing layer 3 has a spiral structure in which the metal wire 4 is spirally wound at a predetermined braiding angle a (A1, A2, A3, A4) with respect to the hose axis CL. Specifically, the knitting angle A1 is set for the innermost reinforcing layer 3a, and knitting angles A2, A3, and A4 are set for the reinforcing layers 3b, 3c, and 3d located on the outer peripheral side in this order. The winding direction of the metal wires 4 of the reinforcing layers 3 disposed adjacent to each other in the radial direction is opposite.

Each of the knitting angles A1 to A4 is set to 52 ° or more and 57 ° or less. In this embodiment, the knitting angles A1 to A4 are substantially the same, but the knitting angle a may be larger or smaller as the knitting angle a is closer to the reinforcing layer 3 on the outer peripheral side.

The number of layers of the reinforcing layer 3 is, for example, 2 to 8 inclusive, and a desired number of layers is used. Each reinforcing layer 3 is formed of a metal wire 4 of the same specification, and in this embodiment, all reinforcing layers 3 are of substantially the same specification.

The wire 4 is formed by twisting a plurality of wires. As the wire 4, various steel wires used as members for forming a reinforcing layer of a general rubber hose are used. The wire diameter of the metal wire 4 is, for example, 0.20mm or more and 1.00mm or less.

The ratio Ta/Tx of the 0.2% yield strength Ta to the maximum tensile stress Tx of the wire 4 is 0.85 or more and 0.99 or less. The ratio Ta/Tx is more preferably 0.90 or more and 0.94 or less.

The maximum tensile stress Tx is the tensile strength of the so-called wire 4, and the maximum tensile stress Tx and the 0.2% yield strength Ta are obtained by the method according to JIS Z2241: 2011, and a tensile test value obtained by a tensile test method of a metal material. The maximum tensile stress Tx is grasped by the stress-strain curve D of the metal line 4 illustrated in fig. 3. The tensile stress at the intersection of the dashed-dotted line L2 and the curve D, which is shifted in the horizontal axis direction by the amount of 0.2% strain in the elastic deformation region (dashed-dotted line L1 in fig. 3) of the curve D, was grasped as 0.2% yield strength Ta.

The specification of the wire 4 is determined by the specification determining method of the hose wire of the present application. An example of the procedure of the specification determination method will be described.

First, the tensile test described above was performed in order to obtain the stress-strain curve D for the metal wire 4 of various specifications as candidates. By this tensile test, the maximum tensile stress Tx and 0.2% yield strength Ta of each wire 4 were grasped, and the ratio Ta/Tx was calculated.

Further, a hose 1 having a reinforcing layer 3 of a spiral structure formed of each wire 4 was manufactured, and the result was grasped by performing a pressure-proof endurance test in which a predetermined internal pressure was repeatedly applied to each hose 1. The pressure-resistant endurance test is performed by filling the inside of the hose 1 extending in a straight line with a liquid, repeatedly applying an internal pressure at a predetermined frequency until the hose 1 is broken, and grasping the number of times the internal pressure is applied until the hose is broken as a measurement result. For example, the hose 1 is filled with a hydraulic oil at about 100 ℃, and an internal pressure of 42mpa×150% is applied by a trapezoidal wave having a frequency of 1.33 Hz.

The type of liquid filled in the hose 1, the temperature, the magnitude of the internal pressure applied to the hose 1, the frequency, and the type of waveform thereof (trapezoidal wave, triangular wave, sin wave, etc.) in the pressure-resistant endurance test are not limited to the above-described conditions, and may be slightly changed according to the use conditions of the hose 1. As a required performance of the hose 1, a target value G was set in advance for the result (durability number) of the pressure-resistant durability test.

Then, based on the calculated ratio Ta/Tx and the result of the pressure-resistant endurance test (endurance number), the appropriate range R of the ratio Ta/Tx satisfying the target value G is grasped. The ratio Ta/Tx is closely related to the degree of pressure durability of the hose 1, and may be set to a specific range in order to improve the pressure durability (number of times of durability) of the hose 1, as illustrated in fig. 4. That is, the present inventors found that there is an appropriate range R of the ratio Ta/Tx at which the pressure durability of the hose 1 becomes a peak state as illustrated in fig. 4, and the present application has been devised.

In fig. 4, the range of the ratio Ta/Tx where the number of times of durability becomes equal to or larger than the target value G becomes the appropriate range R. The wire 4 having the specification of the ratio Ta/Tx in the proper range R is selected as a member for forming the reinforcing layer 3 of the hose 1. In order to make the ratio Ta/Tx different, 1 or more of the wire diameter, the material, the heat treatment, the number of turns, the structure (the number of wires, etc.) and the like of the wire 4 are combined to be different (changed).

Therefore, by using this ratio Ta/Tx, it is possible to select the metal wire 4 of an appropriate specification that more effectively improves the pressure durability of the hose 1. The ratio Ta/Tx can be obtained by performing a tensile test of the wire 4 alone. Since it is not necessary to perform a fatigue test of the wire 4 alone as in the conventional art, a wire 4 of an appropriate specification can be selected easily.

In the case of the general structure of the high-pressure hose as illustrated in fig. 1 and 2, if the ratio Ta/Tx is 0.85 or more and 0.99 or less, it is advantageous to improve the pressure-resistant durability of the hose 1. Therefore, in the hose 1 of the present application in which the reinforcing layer 3 is formed of the metal wire 4 having a ratio Ta/Tx of 0.85 or more and 0.99 or less, it is advantageous to more effectively improve the pressure durability.

In order to efficiently improve the pressure durability of the hose 1, the ratio Ta/Tx is more preferably 0.94 or less. Similarly, the ratio Ta/Tx is more preferably 0.90 or more. The appropriate range R of the ratio Ta/Tx does not vary significantly as long as the hose 1 is of the construction of the commonly employed high pressure hose described hereinbefore.

[ example ]

As shown in table 1, test samples of hoses having the structures illustrated in fig. 1 to 2 were produced by differentiating only the specifications of the wire into 4 types (examples 1 to 3 and comparative example). Each wire was a steel wire (brass-plated steel wire) having a wire diameter of about 0.38mm, which was formed by twisting metal wires. The wire diameters of the 4 kinds of metal wires are substantially the same, and the characteristic values (elongation at break, maximum tensile stress, 0.2% yield strength) are different by changing conditions such as the roll diameter, the number of rolls, and the amount of press-in by performing a leveling roll process after the wire drawing process. The leveling roller process is a process of: a plurality of pairs of opposing rollers are arranged at intervals in the longitudinal direction of the wire, and the wire is sequentially passed through a gap D1 (a gap narrower than the outer diameter D0 of the wire) between the outer peripheral surfaces of the respective pairs of rollers. The number of rollers is the number of pairs of rollers arranged at intervals in the longitudinal direction of the wire. The amount of press-in was a value calculated from { (outer diameter D0-gap D1)/outer diameter D0} ×100 (%). The number of layers of reinforcement was 4, and the braiding angle a of the metal wires in each layer of reinforcement was approximately the same, and was about 54 ° to 55 °. The thickness of each interlayer rubber layer is about 0.3 mm. The inner surface layer is formed of acrylonitrile-butadiene rubber and styrene-butadiene rubber, the outer surface layer is formed of chloroprene rubber and styrene-butadiene rubber, and the interlayer rubber layer is formed of acrylonitrile-butadiene rubber.

For each test specimen, the above pressure-resistant durability test was performed by filling the inside with a working oil at about 100℃and applying an internal pressure of 42 MPa.times.150% using a trapezoidal wave with a frequency of 1.33 Hz. The results are shown in Table 1 and FIG. 5. Fig. 5 is a graph plotting the results of table 1. In example 1, the target value G of the number of times of endurance was 100 ten thousand times, and even if the number of times of endurance exceeded 200 ten thousand times, the test sample was not broken, and thus the test was stopped in the middle.

[ Table 1 ]

From the results shown in Table 1 and FIG. 5, examples 1 to 3 in which the ratio Ta/Tx was 0.93 or more and 0.99 or less had pressure durability satisfying the target value of the number of times of durability. When the ratio Ta/Tx is around 0.93, the number of times of durability is estimated to be a peak.

Claims

1. A specification determining method of a metal wire for a hose, the specification determining method of a metal wire for a hose is a method of determining a specification of a metal wire forming a reinforcing layer of a spiral structure between an inner surface layer and an outer surface layer of a hose,

the metal wire is formed by twisting a plurality of metal wires, and a proper range of the ratio, in which the result of the pressure resistance and durability test satisfies a preset target value, is grasped based on the ratio of the 0.2% yield strength to the maximum tensile stress of the metal wire and the result of the pressure resistance and durability test in which the internal pressure is repeatedly applied to the hose under a predetermined internal pressure condition, and a metal wire having a specification of the ratio in the grasped proper range is selected as a member for forming the reinforcing layer of the hose.