JP7401741B2 - How to set the minimum bending radius of hoses and hoses - Google Patents

Description

The present invention relates to a method and hose for setting the minimum bending radius of a hose having a wire reinforcement layer with a spiral structure, and more particularly to a setting method and hose that can more easily set an appropriate minimum bending radius.

A reinforcing layer is embedded in the hose to withstand the internal pressure of use. For example, a hose with a relatively high operating internal pressure has a wire reinforcement layer with a spiral structure (see, for example, Patent Document 1). Since hoses are often used in a bent state, they are required to have excellent bending durability. In a hose having a wire reinforcing layer having a spiral structure, if the bending radius of the bent hose is too small, the wires of the innermost wire reinforcing layer protrude inward and strongly interfere with the inner surface layer of the hose. This may cause damage to the inner layer. Therefore, it is necessary to set a minimum bending radius of the hose that can ensure bending durability without causing such problems.

On the other hand, if the minimum bending radius is set too large, the conditions under which the hose can be used will be excessively restricted, so it is desirable to make the minimum bending radius as large as possible within a range that can ensure the bending durability of the hose. In order to set such an appropriate minimum bending radius, it is necessary to conduct tests using hose samples and obtain a large amount of data. Therefore, there is room for improvement in easily setting an appropriate minimum bending radius.

Japanese Patent Application Publication No. 9-26062

An object of the present invention is to provide a method for setting the minimum bending radius of a hose that can more easily set an appropriate minimum bending radius for a hose having a spiral-structured wire reinforcement layer, and a method for setting the minimum bending radius using this setting method. The purpose is to provide a hose.

In order to achieve the above object, the method for setting the minimum bending radius of a hose according to the present invention is to at least 1 layer , the inner layer and the outer layer are made of rubber or resin, and the inner diameter is 12.7 mm to 63.5 mm. Using the outer diameter D of the wire reinforcing layer disposed at the outermost periphery and the arrangement density F of the wire forming this wire reinforcing layer when the hose is in a straight line state, When the hose of the wire reinforcement layer is bent into an arc shape, a standard bending radius R at which the winding interval of the wire on the inside of the bend becomes zero is calculated, and a predetermined tolerance value is added to this standard bending radius R. A value is set to the minimum bending radius Rx. The arrangement density F is calculated by the following equation (1).
Arrangement density F (%) = {(d・n/2)/(P・sin(α/2))}×100...(1)
Here, d is the outer diameter of the wire in the wire reinforcing layer disposed at the outermost periphery, n is the number of wires in this wire reinforcing layer, and P is the outer diameter of the wire in this wire reinforcing layer. The winding pitch in the axial direction of the hose, α/2, is the braiding angle (°) of the wire in the wire reinforcement layer with respect to the axial direction of the hose.

The hose of the present invention is characterized in that the minimum bending radius is set by the above setting method.

According to the present invention, the outer diameter D of the wire reinforcing layer disposed at the outermost periphery of the wire reinforcing layers and the outer diameter D of the wire forming the wire reinforcing layer and the outer diameter D of the wire forming the wire reinforcing layer are Using the arrangement density F, when the hose of this wire reinforcement layer is bent into an arc shape, the minimum bending radius Rx is determined based on the reference bending radius R at which the winding interval of the wire on the inside of the bend becomes zero. , it is possible to easily set the minimum bending radius of the hose to an appropriate value that is as large as possible within the range that can ensure the bending durability of the hose.

FIG. 2 is an explanatory diagram illustrating a partially cut away hose of the present invention. 2 is a sectional view taken along line AA in FIG. 1. FIG. 2 is a sectional view taken along line BB in FIG. 1. FIG. FIG. 4 is an explanatory diagram illustrating a state in which the hose of FIG. 3 is bent.

EMBODIMENT OF THE INVENTION Hereinafter, the setting method of the minimum bending radius of the hose of this invention and a hose are demonstrated based on embodiment shown in the figure.

As illustrated in FIGS. 1 and 2, the hose 1 of the present invention is formed by coaxially laminating an inner surface layer 2, a wire reinforcing layer 3, and an outer surface layer 5 in order from the inner circumferential side. A dashed line CL in the figure indicates the central axis of the hose 1.

The inner surface layer 2 is located at the innermost circumferential side and forms a fluid flow path. Since the inner layer 2 comes into direct contact with the fluid flowing through the hose 1, an appropriate type of rubber or resin is selected in consideration of durability against this fluid. Examples of the fluid include hydraulic oil, air conditioner refrigerant, water, etc., but are not particularly limited.

In this embodiment, four wire reinforcing layers 3 (3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ ) are laminated. The reinforcing layer 3 ₁ disposed on the innermost side of the wire reinforcing layer 3 is wound around the outer circumferential surface of the inner surface layer 2 , and the outer surface layer 5 is wound on the outer circumferential surface of the reinforcing layer 3 ₄ disposed on the outermost circumferential side. Laminated.

Each wire reinforcement layer 3 has a spiral structure in which a predetermined number of wires 4 are spirally wound at a predetermined braiding angle (α/2) with respect to the central axis CL. In the wire reinforcing layers 3 that are stacked next to each other, the winding directions of the respective wires 4 are opposite to each other. The material of the wire 4, the number of laminated wire reinforcing layers 3, the specifications of the wire 4, and the predetermined number of wires 3 in each wire reinforcing layer 3 are determined in consideration of the pressure resistance required of the hose 1, etc. An intermediate rubber layer may be laminated between the wire reinforcing layers 3.

The outer layer 5 is made of rubber, resin, or the like. For the outer layer 5, an appropriate material is selected in consideration of trauma resistance, weather resistance, and the like. The hose 1 is provided with other members (layers) as necessary.

The inner diameter of the hose 1 is, for example, about 12.7 mm to 63.5 mm. The operating pressure of the hose 1 is, for example, about 10.5 MPa to 42 MPa.

When setting the minimum bending radius of the hose 1 according to the present invention, the longitudinal cross-sectional structure of the hose 1 is taken into consideration, as illustrated in FIG. In FIG. 3, the wire 4 is shown for the reinforcing layer 3 ₄ arranged on the outermost side of the wire reinforcing layer 3, but the wire 4 is shown for the other reinforcing layers 3 ₁ to 3 ₃ . Not yet. Note that since the wire 4 is wound at a predetermined braiding angle (α/2) with respect to the central axis CL, the cross-sectional shape of the wire 4 in FIG. 3 is strictly close to an ellipse; It is simplified and shown as a simple circle. Similarly, in FIG. 4, which will be described later, the cross-sectional shape of the wire 4 is simplified and shown as a simple circle.

In this embodiment, the reinforcing layer ₃₄ is formed by winding three wires 4 (4a, 4b, 4c) in the axial direction of each hose 1 at a predetermined winding pitch P. Each of the wires 4a, 4b, and 4c has the same specifications and has an outer diameter of d. The two-dot chain line in FIG. 3 is a line connecting the center positions of the respective wires 4 and extending in the axial direction of the hose 1. The outer diameter of the reinforcing layer ₃₄ formed in a cylindrical shape is D.

As illustrated in FIG. 3, in the straight hose 1, the wire 4 forming the wire reinforcing layer 3 is wound with a slight gap in the axial direction. When the wire 4 is wound around the straight hose 1 without any gaps in the axial direction, the arrangement density F of the wire 4 is 100%. If the arrangement density F is 100%, the flexibility (flexibility) of the hose 1 will be impaired, so it is generally about 70% to 80%, for example.

This arrangement density F is calculated by the following (1).
Arrangement density F (%) = {(d・n/2)/(P・sin(α/2))}×100...(1)
Here, d is the outer diameter of the wire 4 in the wire reinforcement layer 3 ₄ , n is the predetermined number of wires 4 in the wire reinforcement layer 3 ₄ , P is the winding pitch of the wire 4 in the wire reinforcement layer 3 ₄ , α /2 is the braiding angle (°) of the wire 4 in the wire reinforcement layer ₃₄ .

This placement density F indicates how much wire 4 is implanted within the implantation width of P·sin(α/2). In other words, the arrangement density F indicates the ratio of the total value of the width (outer diameter d) of the wires 4 being driven in to the driving width of P sin (α/2) in the straight hose 1. There is.

To set the minimum bending radius Rx of the hose 1, the outer diameter D and the arrangement density F are used. Calculate the reference bending radius R at which the winding interval of the wire 4 on the inside of the bend of the wire reinforcing layer 3 ₄ becomes zero when the straight hose 1 in FIG. 3 is bent into an arc shape as shown in FIG. 4. do. Then, a value obtained by adding a predetermined allowable value Ax to the calculated reference bending radius R is set as the minimum bending radius Rx (Rx=R+Ax).

In FIG. 4, the hose 1 is bent in an arc shape around the Z point, and the wires 4 (4a, 4b, 4c) are wrapped around the reinforcing layer ₃₄ without gaps inside the bend. (Wires 4 adjacent to each other in the axial direction of the hose 1 are in contact with each other). When the hose 1 is further bent from the state shown in FIG. 4, the wire 4 can only move in the radial direction of the bend inside the reinforcing layer ₃₄ . Therefore, the wire 4 moves toward the inner surface layer 5 on the inner side of the bend of the reinforcing layer ₃₄ , and the wire 4 presses and interferes with the inner surface layer 5. If this degree of interference increases, the inner layer 5 may be pressed by the wires ₄ of the reinforcing layer 34 and be damaged. Let the radius R be the reference bending radius R. The minimum bending radius Rx is set to be larger than the reference bending radius R.

The reference bending radius R is calculated, for example, using equation (2) below.
Standard bending radius R=outer diameter D/{2(1-placement density F)}...(2)

To explain in detail, the circumferential length L of the circle around the central axis CL of the hose 1 in the state shown in FIG. 4 is πR. On the other hand, the circumference L1 of the circle at the innermost position of the wire 4 on the inner side of the bend of the reinforcing layer 3 ₄ (innermost bending position of the reinforcing layer 3 ₄ ) is π{R-(D/2)}. When the hose 1 is in a straight line and has an arrangement density F, F=L1/L, so F={R-(D/2)}/R, which can be rearranged to give the above equation (2).

Alternatively, the reference bending radius R can also be calculated using the following equation (3).
Standard bending radius R = (Outer diameter D - Outer diameter d) / {2 (1 - Arrangement density F)}... (3)

To explain in detail, the circumferential length L of the circle around the central axis CL of the hose 1 in the state shown in FIG. 4 is πR. On the other hand, the circumference L2 of the circle at the center position of the wire ₄ (the position indicated by the two-dot chain line) on the inner side of the bend of the reinforcing layer 34 is π{R-{(Dd)/2)}}. When the hose 1 is in a straight line and the arrangement density is F, F=L2/L, so F={R-{(D-d)/2)}/R, and rearranging this, we get the above (3). ) becomes the formula.

In the above equation (3), it is assumed that the wires 4 adjacent in the axial direction of the hose 1 come into contact with each other at the center position of the wires 4, so the above equation (3) has a stricter standard than the above equation (2). Calculate the raising radius R. However, since the outer diameter d of the wire 4 is usually a sufficiently smaller value than the outer diameter D, there is no big difference in the calculated standard bending radius R even if either of the above (3) and (2) is used. Therefore, when using the above equation (2), the calculation work is simpler than when using the above equation (3).

Since the reference bending radius R is calculated with sufficient consideration given to the bending durability of the hose 1 as described above, the allowable value Ax may be a very small adjustment value, for example, 0 to 10 mm. That is, the reference bending radius R may be set to the minimum bending radius Rx by setting the allowable value Ax to zero, but it is preferable to set the allowable value Ax to exceed zero in consideration of the safety factor. In this way, the minimum bending radius Rx of the hose 1 is set.

According to the present invention, the outer diameter D of the wire reinforcing layer 3 ₄ disposed at the outermost periphery of the wire reinforcing layers 3 and the above formula (1) of the wire 4 forming this wire reinforcing layer 3 ₄ are determined. Using the calculated arrangement density F, the minimum bending radius Rx can be easily set. The minimum bending radius Rx is based on the standard bending radius R at which the winding interval of the wire 4 on the inside of the bend of the wire reinforcing layer 3 ₄ is zero when the hose 1 is bent into an arc shape. Sufficient bending durability can be ensured. Since the allowable value Ax added to the reference bending radius R is an extremely small value, the minimum bending radius Rx can be set to an appropriate value as large as possible within a range that can ensure the bending durability of the hose 1.

A hose with typical specifications having a four-layer wire reinforcement layer with a spiral structure was set in a bent state at this minimum bending radius Rx, and a durability test was conducted in which a predetermined internal pressure was repeatedly applied to confirm durability. As a result, it was confirmed that the hose had sufficient durability for practical use.

The hose 1 with the minimum bending radius Rx set in this way has sufficient bending durability under usage conditions in which the minimum bending radius Rx is observed, so damage to the hose 1 is suppressed and the hose 1 can be used for a long period of time. It will be possible to use it across the board. Furthermore, since the minimum bending radius Rx is not set excessively, there are fewer restrictions on usage conditions, and the locations (environments) where the hose 1 can be used are more diverse.

1 Hose 2 Inner layer 3 (3 ₁ , 3 ₂ , 3 ₃ , 3 ₄ ) Wire reinforcement layer 4 (4a, 4b, 4c) Wire 5 Outer layer

Claims (5)

At least one wire reinforcing layer with a spiral structure is coaxially arranged between an inner layer and an outer layer that are laminated coaxially , and the inner layer and the outer layer are made of rubber or resin. A method for setting a minimum bending radius for a hose having an inner diameter of 12.7 mm to 63.5 mm , the wire reinforcing layer being arranged at the outermost periphery of the wire reinforcing layer, Using the arrangement density F of the wire forming the reinforcing layer when the hose in this wire reinforcing layer is in a straight state, calculate the density on the inside of the bend when the hose in this wire reinforcing layer is bent into an arc shape. A minimum bending radius R of a hose, characterized in that a reference bending radius R at which the winding interval of the wire becomes zero is calculated, and a value obtained by adding a predetermined tolerance value to this reference bending radius R is set as the minimum bending radius Rx. How to set the radius.
The arrangement density F is calculated by the following equation (1).
Arrangement density F (%) = {(d・n/2)/(P・sin(α/2))}×100...(1)
Here, d is the outer diameter of the wire in the wire reinforcing layer disposed at the outermost periphery, n is the number of wires in this wire reinforcing layer, and P is the outer diameter of the wire in this wire reinforcing layer. The winding pitch in the axial direction of the hose, α/2, is the braiding angle (°) of the wire in the wire reinforcement layer with respect to the axial direction of the hose. The method for setting the minimum bending radius of a hose according to claim 1, wherein the reference bending radius R is calculated by the following equation (2).
Standard bending radius R=outer diameter D/{2(1-placement density F)}...(2) The method for setting the minimum bending radius of a hose according to claim 1, wherein the reference bending radius R is calculated by the following equation (3).
Standard bending radius R = (Outer diameter D - Outer diameter d) / {2 (1 - Arrangement density F)}... (3) The method for setting the minimum bending radius of a hose according to any one of claims 1 to 3, wherein the allowable value is set to 0 to 10 mm. A hose in which the minimum bending radius Rx is set by the method for setting the minimum bending radius of a hose according to any one of claims 1 to 4.

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