JPH10141551A - Hose for hydraulic pressure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hose for hydraulic pressure which is soft and flexible throughout and which is capable of preventing slippage of yarn of a reinforcing yarn layer without increasing the braiding density of the reinforcing yarn layer. SOLUTION: The hose for hydraulic pressure is provided with a tubular inner layer 1 and an outer layer 3 laminated-formed on the outer peripheral surface of the tubular inner layer 1 through a reinforcing yarn layer 2. Besides, the tubular inner layer 1 is formed of a two layer structure consisting of the innermost layer 1a, the surface hardness of which is set in the range of 53 to 67 (ASTEM Shore D), and an inner layer 1b which is formed on the outer peripheral surface of the innermost layer 1a, and the surface hardness of which is set in the range of 40 to 53 (ASTEM Shore D).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic hose used for general industrial machines, construction machines, civil engineering machines and the like.

[0002]

2. Description of the Related Art In general, hydraulic hoses used in general industrial machines, construction machines, civil engineering machines and the like have a multilayer structure in which various layers formed from various resins are combined.
As an example of the multi-layered hydraulic hose, for example, as shown in FIG. 6, the inner layer 10 is formed of a polyamide resin having excellent oil resistance, and a polyester-based reinforcing yarn or the like is formed on the outer peripheral surface of the inner layer 10. A three-layer hydraulic hose 13 (hydraulic hose) in which a reinforcing yarn layer 11 braided by using the above-described method is formed and a polyurethane outer layer 12 is formed on the outer peripheral surface of the reinforcing yarn layer 11 is awarded. ing. Further, as another example of the hydraulic hose, for example, a polyolefin elastomer (TPO) may be used instead of the polyamide resin which is a material for forming the inner layer 10 of the hydraulic hose 13.
Hydraulic hoses (hydraulic hoses) have been awarded.

As shown in FIG. 7, for example, such a hydraulic hose is bent in a substantially U-shape, and both ends of a hydraulic hose 9 are fitted to metal fittings 14 respectively, and the periphery thereof is further tightened. It is fixed and used with the attachment 15.

[0004]

However, when the hydraulic hose is used as described above, the following problems occur. For example, the above-described hydraulic hose has an inner layer formed of a polyamide resin and has high mechanical strength, and therefore has excellent strength of the hose itself. In this case, the minimum bending radius must be set to be large, and there is a problem that the handleability as a hydraulic hose is inferior.

On the other hand, the above-mentioned hydraulic hose has an inner layer made of TP.
Although TPO is rich in flexibility because it is formed of O, TPO has low mechanical strength and poor adhesion to reinforcing yarns such as polyester, which is a material for forming the reinforcing yarn layer. Weak to power. Therefore, as described above, when the hydraulic hose is bent and used in a substantially U-shape, the gap between the reinforcing yarns on the outer peripheral surface side of the reinforcing yarn layer becomes large,
Since the TPO, which is the material forming the inner layer, protrudes from the gap, a yarn misalignment of the reinforcing yarn layer occurs, causing a problem that the hose is broken. Therefore, by increasing the braiding density of the reinforcing yarn layer, it is conceivable to reduce the gap between the reinforcing yarn layers and prevent the yarn from shifting in the reinforcing yarn layer. However, in this case, excessive reinforcing yarn is required. As the cost increases,
Problems such as poor workability when forming the reinforcing yarn layer occur. Therefore, a hydraulic hose capable of preventing the yarn displacement of the reinforcing yarn layer without increasing the braid density of the reinforcing yarn layer has been desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to prevent a yarn displacement of a reinforcing yarn layer without increasing the braid density of the reinforcing yarn layer as a whole. It is an object of the present invention to provide a hydraulic hose that can perform pressure reduction.

[0007]

In order to achieve the above object, a hydraulic hose according to the present invention comprises a tubular inner layer and an outer layer laminated on the outer peripheral surface of the tubular inner layer via a reinforcing yarn layer. A hydraulic hose provided with a configuration in which the tubular inner layer has a two-layer structure of the following innermost layer (A) and the following inner layer (B) formed on the outer peripheral surface of the innermost layer (A). Take. (A) The innermost layer having a surface hardness set in the range of 53 to 67 (ASTM Shore D). (B) An inner layer having a surface hardness set in the range of 40 to 53 (ASTM Shore D).

[0008] The surface hardness of the innermost layer (A) and the inner layer (B) of the above-mentioned tubular inner layer refers to the hardness of the surface of each layer alone, and is obtained as follows. That is, first, the air conditioning equipment (23 ± 2 ° C in principle)
Shore D hardness meter (JIS K7)
215-1986) is prepared. Next, a test piece having a thickness of 6 mm or more is prepared. When the thickness of the test piece is less than 6 mm,
The test pieces are stacked to a thickness of 6 mm or more. Then, the test piece is kept vertical, the worked surface is brought into contact with the test piece so that the indenter is perpendicular to the test piece measurement surface, and after pressing with a load, the scale is read immediately.

That is, the present inventors have developed a hydraulic hose capable of preventing the yarn displacement of the reinforcing yarn layer while maintaining the flexibility of the conventional hydraulic hose and without increasing the braid density of the reinforcing yarn layer. Research was focused on obtaining
As a result, the tubular inner layer formed on the inner peripheral surface of
The inner layer (B) on the side in contact with the reinforcing yarn layer is formed of a material which is flexible and has good adhesion to the reinforcing yarn, and is formed on the inner peripheral surface of the inner layer (B). It has been found that if the innermost layer (A) to be formed is formed of a hard material, it has flexibility and appropriate strength, so that the yarn displacement of the reinforcing yarn layer can be prevented. As a result of repeated studies on the surface hardness of each layer, when the surface hardness of the innermost layer (A) and the inner layer (B) is set to the specific range, flexibility is maintained, and
The present inventors have found that the yarn displacement of the reinforcing yarn layer can be prevented without increasing the braid density of the reinforcing yarn layer, and reached the present invention.

Further, when the braiding density of the reinforcing yarn layer formed by braiding the reinforcing yarn is set in the above-mentioned specific range, the yarn displacement of the reinforcing yarn layer can be sufficiently prevented. They found that there was no need to increase the density excessively.

[0011]

Next, embodiments of the present invention will be described in detail.

As shown in FIG. 1, the hydraulic hose according to the present invention has a two-layer tubular inner layer 1 having an inner layer 1b formed on the outer peripheral surface of an innermost layer 1a, and is formed on the outer peripheral surface of the tubular inner layer 1. And a four-layer structure of an outer layer 3 formed on the outer peripheral surface of the reinforcing yarn layer 2. The hydraulic hose of the present invention is characterized in that the innermost layer 1a and the inner layer 1b constituting the tubular inner layer 1 have special characteristics.

The tubular inner layer 1 has a two-layer structure including an innermost layer 1a and an inner layer 1b formed on the outer peripheral surface of the innermost layer 1a. When the innermost layer 1a and the inner layer 1b have the following characteristics, the hydraulic hose of the present invention is excellent in flexibility and can prevent yarn displacement.

The innermost layer 1a has a surface hardness of 53
６７67 (ASTM Shore D), and more preferably 55-65 (ASTM Shore D).
Shore D). That is, the surface hardness is 53
If it is less than (Shore D), the mechanical strength is too low, and if it is used after being bent in a substantially U-shape, the material for forming the inner layer 1b may protrude from the gap between the reinforcing yarns and the hose may be damaged, Conversely, if the surface hardness exceeds 67 (Shore D), the mechanical strength becomes too high, and when used in a substantially U-shape, the minimum bending radius must be set large. This is because the handleability is poor.

As a material for forming the innermost layer 1a, polyamide 11 is used because of its excellent heat resistance and oil resistance.
It is particularly preferable to use a polyamide resin such as (PA11), polyamide 12 (PA12), a copolymer of polyamide 6 and polyamide 66 (PA6 / 66), or a thermoplastic polyester elastomer (TPEE).

The inner layer 1b formed on the outer peripheral surface of the innermost layer 1a must have a surface hardness in the range of 40 to 53 (ASTM Shore D), more preferably 45 to 53 (ASTM Shore D). ASTM Shore D). That is, if the surface hardness is less than 40 (Shore D), the mechanical strength becomes too low, and the hose is easily broken. Conversely, if the surface hardness exceeds 53 (Shore D), the mechanical strength increases. This is because when used in a substantially U-shape, the minimum bending radius must be set large, and the handling as a hydraulic hose is inferior.

As a material for forming the inner layer 1b, a material having good adhesion to a reinforcing yarn as a material for forming the reinforcing yarn layer 2 is preferable. In particular, thermoplastic polyurethane (TPU), TPU,
PEE and the like are preferred.

The reinforcing yarn layer 2 formed on the outer peripheral surface of the inner layer 1b preferably has a braid density of 60 to 85%, more preferably 65 to 80%. That is, if the braid density of the reinforcing yarn layer 2 is smaller than 60%, the gap between the reinforcing yarns becomes too large, and it is not possible to sufficiently prevent the yarn displacement, and conversely, the gap is higher than 85%. If, for example, the reinforcing yarn is excessively required, the cost increases, and the workability in forming the reinforcing yarn layer also deteriorates.

The braid density is, as shown in FIG.
The ratio of the outer unit surface of the tubular inner layer 1 covered by the reinforcing yarn 2a, which is a material for forming the reinforcing yarn layer 2, is obtained by the following equation (1).

[0020]

[Formula 1] Braid density (%) = (d · J · K / 2π · E · cosα) × 100 (1) [In the formula (1), d is a diameter of the reinforcing yarn in a normal state (m
m), J is the number of arrangements, K is the number of strokes, E is the outer diameter (mm) of the tubular inner layer, and α is the braid half angle (°) of the reinforcing yarn. ]

Examples of the reinforcing yarn which is a material for forming the reinforcing yarn layer 2 include polyester yarn, polyamide yarn, vinylon yarn, rayon yarn, aromatic polyamide yarn, hard steel wire, stainless steel wire and the like. Among them, polyester yarns are mainly used from the viewpoints of strength, versatility, cost and the like.

The material for forming the outer layer 3 formed on the outer peripheral surface of the reinforcing yarn layer 2 is not particularly limited, and a conventionally known material can be used. For example, TPU, PA, TP
O, TPEE and the like.

The hydraulic hose of the present invention is manufactured using the above-described materials, for example, as follows.

First, the tubular inner layer 1 is produced, for example, as follows. That is, a polyamide resin or the like as a material for forming the innermost layer 1a of the tubular inner layer 1 and a thermoplastic polyurethane or the like as a material for forming the inner layer 1b of the tubular inner layer 1 are prepared, and are simultaneously extruded using an extruder. A tube having a two-layer structure and serving as the tubular inner layer 1 having a specific surface hardness is prepared. Alternatively, the tubular inner layer 1
After extruding the innermost layer 1a forming material to form the innermost layer 1a, the surface of the innermost layer 1a is subjected to a plasma treatment,
By extruding the material for forming the inner layer 1b of the tubular inner layer 1 on the outer peripheral surface of the innermost layer 1a, a tube having the same two-layer structure as described above is produced.

Next, a reinforcing yarn such as a polyester yarn is braided on the outer peripheral surface of the tube having the two-layer structure by using a braiding machine to form a reinforcing yarn layer 2. Subsequently, the outer layer 3 is formed on the outer peripheral surface of the reinforcing yarn layer 2 by extruding a material for forming the outer layer 3 using an extruder. Thus, as shown in FIG. 1, the tubular inner layer 1 having a two-layer structure including the innermost layer 1a and the inner layer 1b formed on the outer peripheral surface of the innermost layer 1a,
A hydraulic hose having a four-layer structure of the reinforcing yarn layer 2 formed on the outer peripheral surface of the tubular inner layer 1 and the outer layer 3 formed on the outer peripheral surface of the reinforcing yarn layer 2 is obtained.

The thickness of each layer in the four-layer hydraulic hose is set as follows. The thickness of the innermost layer 1a of the tubular inner layer 1 is preferably set in the range of 0.2 to 2.8 mm, particularly preferably in the range of 0.5 to 1.0 mm. The thickness of the inner layer 1b of the tubular inner layer 1 is preferably in the range of 0.2 to 2.8 mm, particularly preferably 0.5 to 2.8 mm.
It is set in the range of 1.0 mm. The thickness of the outer layer 3 is usually set in a range of 0.3 to 3.0 mm, preferably in a range of 0.3 to 1.5 mm.

Next, examples will be described together with comparative examples.

[0028]

Examples 1 to 4 and Comparative Examples 1 to 4 First, materials for forming the innermost layer and the inner layer of the tubular inner layer shown in Tables 1 and 2 described below were prepared, and these were formed using an extruder according to the above-described method. By extruding two layers at the same time, a tube having a two-layer structure to be a tubular inner layer was prepared. Next, a reinforcing yarn layer (braid density: 66%) was formed by braiding polyester yarn on the outer peripheral surface of the tube having the two-layer structure using a braiding machine. Further, an outer surface of the reinforcing yarn layer is coated with a TPU using an extruder.
(Pandex T-8195, manufactured by Dainippon Ink and Chemicals, Inc.) to form an outer layer. Thus, FIG.
As shown in the figure, a four-layer hydraulic hose (9.5 m inside diameter)
mx 14 mm outside diameter). The surface hardness of the innermost layer and the inner layer of the tubular inner layer of the hydraulic hose is also shown in Tables 1 and 2 below. In the hydraulic hose, the innermost layer of the tubular inner layer has a thickness of 0.5 m, the inner layer has a thickness of 0.5 mm, and the outer layer has a thickness of 0.5 mm.
Met.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

Conventional Examples 1 and 2 Using a material for forming a tubular inner layer shown in Table 3 below, a tube having a one-layer structure to be a tubular inner layer was prepared by extruding using an extruder. Otherwise, by performing the same operation as in Example 1, a three-layer hydraulic hose (inner diameter 9.5 mm × outer diameter 1) as shown in FIG.
4 mm). In the hydraulic hose thus obtained, the thickness of the tubular inner layer was 1.0 mm, and the thickness of the outer layer was 0.5 mm.

[0032]

[Table 3]

Using the hydraulic hoses of the example product, the comparative example product and the conventional example product thus obtained, the adhesive strength between the tubular inner layer and the reinforcing yarn layer, the impact pressure test,
Comparative evaluation of hose bending repulsion (flexibility) and bending limit bending radius was performed. The results are shown in Tables 4 and 5 below.

[Adhesive Strength Between Tubular Inner Layer and Reinforcing Yarn Layer] The adhesive strength between the tubular inner layer and the reinforcing yarn layer was measured using each hydraulic hose as follows. That is, as shown in FIG.
From the tubular inner layer 31 through the iron core 30 to the reinforcing yarn layer 32
Of the reinforcing yarn layer 32
Of the tubular core 31 and the reinforcing yarn layer 3 when the iron core 30 is pulled upward in the A direction.
The adhesive strength of No. 2 was measured using an autograph.

[Impact pressure test] According to the method specified in 7.7 of JIS K 6375, the maximum operating pressure is 70 kgf.
An impact pressure test was performed by applying an impact pressure of 125% / cm ² . Then, the case where no abnormality such as oil leakage or breakage did not occur until the number of impacts of 200,000 was displayed as ○, and the case where the above abnormality occurred up to 200,000 times of impacts was displayed as x.

[Hose Bending Repulsive Force (Flexibility)] As shown in FIG. 4, one end of each hydraulic hose 20 is attached and fixed to a flat plate 21, and the fixed hydraulic hose 20 is placed in a vertical state (broken line). , And was bent into a substantially L-shape to have a bending radius (C) of 90 mm. Then, the force in the direction of arrow F when the straight line portion AB on the other end side of the hydraulic hose 20 becomes parallel to the flat plate 21 is measured, and this is bent to obtain a repulsive force (kg).
f) was used as an index of flexibility evaluation. That is, it can be said that the smaller the bending repulsion force, the more excellent the flexibility.

[Bending critical bending radius] As shown in FIG.
A ring was made using the hydraulic hose 40 having a length of 1 m, and the end was held by hand, and the hydraulic hose 40 was pulled in the direction of the arrow. Then, the diameter of the wheel was gradually reduced, and the diameter of the wheel at the R portion when the hydraulic hose 40 was broken was measured.

[0038]

[Table 4]

[0039]

[Table 5]

From the results shown in Table 4 above, all the hydraulic hoses of the examples had excellent adhesion between the tubular inner layer and the reinforcing yarn layer, and also had good evaluation in the impact pressure test. In addition, since the hose bending repulsion is small and the breaking limit bending radius is small, it is understood that the hose is flexible and has high flexibility. On the other hand, from the results in Table 5 above, the hydraulic hose of the comparative example was
Since the surface hardness of any one of the innermost layer and the inner layer is out of the above-mentioned specific range, it can be seen that the impact pressure test, the evaluation of the hose bending repulsion and the bending limit bending radius are inferior. Also, the conventional product having a one-layer structure of the tubular inner layer has poor adhesion between the tubular inner layer and the reinforcing yarn layer, has a large hose bending rebound, and has a large breaking limit bending radius. It can be seen that the hose has a poor evaluation in the impact pressure test.

[0041]

As described above, the hydraulic hose of the present invention has a two-layer tubular inner layer consisting of the innermost layer (A) and the inner layer (B) formed on the outer peripheral surface of the innermost layer (A). An outer layer laminated on the outer peripheral surface of the tubular inner layer with a reinforcing yarn layer interposed therebetween, and the surface hardness of the innermost layer (A) and the surface hardness of the inner layer (B) are both within specific ranges. Is set. Therefore, the surface hardness of the inner layer (B) is small and rich in elasticity, and the surface hardness of the innermost layer (A) is high and has appropriate strength, so that yarn displacement can be prevented and breakage of the hose can be prevented. it can.

Further, by setting the braiding density of the reinforcing yarn layer formed by braiding the reinforcing yarn to a specific range, it is possible to sufficiently prevent the yarn displacement of the reinforcing yarn layer. Therefore, it is not necessary to excessively increase the braid density of the reinforcing yarn layer, and the cost can be reduced accordingly, and the workability when forming the reinforcing yarn layer is remarkably improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a configuration of a hydraulic hose of the present invention.

FIG. 2 is an explanatory view showing a method of measuring a braid density.

FIG. 3 is an explanatory diagram showing a method for measuring the adhesive force between a tubular inner layer and a reinforcing yarn layer.

FIG. 4 is an explanatory diagram showing a method for measuring a hose bending repulsion force.

FIG. 5 is an explanatory view showing a method of measuring a bending limit bending radius.

FIG. 6 is an explanatory view showing a configuration of a conventional hydraulic hose.

FIG. 7 is an explanatory diagram showing a use state of a hydraulic hose.

[Explanation of symbols]

 Reference Signs List 1 tubular inner layer 1a innermost layer 1b inner layer 2 reinforcing yarn layer 3 outer layer

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[Procedure amendment]

[Submission date] December 6, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

The innermost layer 1a has a surface hardness of 53
６７67 (ASTM Shore D), and more preferably 55-65 (ASTM Shore D).
Shore D). That is, the surface hardness is 53
If it is less than (ASTM Shore D), the mechanical strength will be too low, and if used in a substantially U-shape, the material of the inner layer 1b will protrude from the gap between the reinforcing yarns and the hose may be damaged. Conversely, if the surface hardness exceeds 67 (ASTM Shore D), the mechanical strength becomes too high, and if it is used in a substantially U-shape, the minimum bending radius must be set large. This is because it is inferior in handleability as a hose for use.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

The inner layer 1b formed on the outer peripheral surface of the innermost layer 1a must have a surface hardness in the range of 40 to 53 (ASTM Shore D), more preferably 45 to 53 (ASTM Shore D). ASTM Shore D). That is, if the surface hardness is less than 40 (ASTM Shore D), the mechanical strength is too low, and the hose is easily broken. Conversely, if the surface hardness exceeds 53 (ASTM Shore D), the mechanical strength is low. This is because, if it is too high and is bent in a substantially U-shape, the minimum bending radius must be set large, and the handleability as a hydraulic hose is poor.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0029

[Correction method] Change

[Correction contents]

[0029]

[Table 1]

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

[0030]

[Table 2]

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0032

[Correction method] Change

[Correction contents]

[0032]

[Table 3]

Claims (2)

[Claims] 1. A hydraulic hose comprising: a tubular inner layer; and an outer layer formed by laminating an outer peripheral surface of the tubular inner layer via a reinforcing yarn layer, wherein the tubular inner layer has the following innermost layer (A): ,
A hydraulic hose comprising a two-layer structure of the following inner layer (B) formed on the outer peripheral surface of the innermost layer (A). (A) The innermost layer having a surface hardness set in the range of 53 to 67 (ASTM Shore D). (B) An inner layer having a surface hardness set in the range of 40 to 53 (ASTM Shore D). 2. The hydraulic pressure according to claim 1, wherein the reinforcing yarn layer is a layer formed by braiding reinforcing yarns, and a braid density of the reinforcing yarn layer is set in a range of 60 to 85%. For hose.