Hoses and Hose Use

Abstract

To provide a hose and a use method for a hose that can prevent damage to an inner layer due to a metal cord that forms a reinforcing layer even under conditions of high internal pressure and movable hose.SOLUTION: After a fiber layer 7 and an interlayer rubber layer 6a are interposed between an inner layer 2 of a hose 1 and an innermost reinforcing layer 3a of a spiral structure, a fiber cord 8 forming the fiber layer 7 is twisted to improve strength, and surface treatment of making RFL liquid adhere to a surface is applied to perform strong adhesion to the inner surface layer 2 and the interlayer rubber 6a, so that the internal pressure of the hose 1 is high, and even when at least one of longitudinal end parts of the hose 1 is attached to a movable part 12 and used, the inner layer 2 is protected by the fiber layer 7 and the interlayer rubber layer 6a against a metal cord 4 forming the innermost reinforcing layer 3a, to prevent damage to the inner surface layer 2 due to the movement of the metal cord 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hose and a method for using the hose, and more specifically, to a hose and a method for using the hose that can suppress a problem in which an inner layer is damaged by metal cords forming a reinforcing layer, even under usage conditions where the internal pressure is high and the hose is movable. [Background technology]

[0002] In hydraulic hoses and the like, a reinforcing layer having a spiral structure formed by, for example, winding a metal cord in a spiral shape is interposed between the inner layer and the outer layer in order to withstand high internal pressure. Such high-pressure hoses are sometimes used with their longitudinal ends fixed to moving parts of devices or equipment. Under such conditions of use, the hose is repeatedly bent as the moving parts move. When the hose moves and is repeatedly bent, the metal cord forming the reinforcing layer may damage the inner layer.

[0003] There are also hoses with a structure in which a rubber layer and a fiber layer are interposed between the innermost reinforcing layer and the inner layer (see, for example, Patent Document 1). However, even if a rubber layer and a fiber layer are interposed, if the internal pressure of the hose is considerably high and the hose is movable, the metal cord may wear down the rubber layer and the fiber layer, leading to damage to the inner layer. Therefore, there is room for improvement in preventing the problem of damage to the inner layer under the conditions in which such a hose is used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-304165 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a hose and a method for using the hose that can suppress the problem of damage to the inner layer by metal cords forming the reinforcing layer, even under usage conditions where the internal pressure is high and the hose is movable. [Means for solving the problem]

[0006] In order to achieve the above object, a hose of the present invention comprises an inner layer and an outer layer laminated coaxially, a plurality of reinforcing layers laminated with an interlayer rubber layer interposed between the inner layer and the outer layer, a fiber layer laminated on the outer peripheral surface of the inner layer, and an interlayer rubber layer interposed between the fiber layer and the innermost reinforcing layer, each of the reinforcing layers having a spiral structure formed by winding a metal cord in a spiral shape, The operating pressure of the hose is between 20MPa and 50MPa. The fiber layer is made of fiber cords which have been twisted and have been subjected to a surface treatment for adhering an RFL liquid to the surface. By braiding Formed The braid structure has a fiber cord fineness of 2100 dtex or more and 5500 dtex or less. It is characterized by:

[0007] The method for using the hose of the present invention comprises attaching at least one of the longitudinal ends of the hose to a moving movable part for use. The hose is repeatedly bent by the movement of the movable part. It is characterized by:

[0008] According to the present invention, a fiber layer and an interlayer rubber layer are interposed between the inner layer and the innermost reinforcing layer of the hose. Furthermore, the fiber cords constituting the fiber layer are twisted to improve their strength, and the RFL liquid is applied to the surface to more strongly bond the inner layer and the interlayer rubber layer. As a result, even under conditions where the internal pressure of the hose is high and at least one of the longitudinal ends of the hose is attached to a moving part, the inner layer is protected by the fiber layer and the interlayer rubber layer from the metal cords constituting the innermost reinforcing layer. This is therefore advantageous in suppressing problems such as damage to the inner layer caused by the movement of the metal cord. [Brief description of the drawings]

[0009] [Figure 1]1 is a partially cut-away explanatory diagram illustrating an embodiment of a hose of the present invention. FIG. [Diagram 2] 2 is an explanatory diagram illustrating the hose of FIG. 1 in cross section. FIG. [Diagram 3] FIG. 2 is an explanatory diagram illustrating a state in which the hose of FIG. 1 is used. [Figure 4] FIG. 2 is an explanatory diagram illustrating a method for testing a hose for durability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a hose and a method of using the hose according to the present invention will be described with reference to the embodiments shown in the

[0011] The embodiment of the hose 1 of the present invention illustrated in Figures 1 and 2 is used as a so-called hydraulic hose, etc. The hose 1 belongs to the category of high-pressure hoses, for example, with a hose operating pressure of 20 MPa to 50 MPa. The hose outer diameter is, for example, 20 mm to 75 mm, and the hose inner diameter is, for example, 10 mm to 55 mm.

[0012] In this hose 1, an inner surface layer 2, reinforcing layers 3 (3a, 3b, 3c, 3d), and an outer surface layer 5 are laminated coaxially in this order from the inner periphery side. Furthermore, interlayer rubber layers 6 (6b, 6c, 6d) are interposed between adjacent reinforcing layers 3 laminated in the radial direction of the hose 1. Furthermore, the hose 1 includes a fiber layer 7 laminated on the outer periphery of the inner surface layer 2, and an interlayer rubber layer 6a interposed between the fiber layer 7 and the innermost reinforcing layer 3a. The dashed dotted line CL in the drawing indicates the hose axis.

[0013] 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 be a multi-layer structure of resin and rubber, a single layer structure of rubber only, or a single layer structure of resin only. For example, the inner surface layer 2 may be a multi-layer structure in which a rubber layer is laminated on the outer peripheral surface of a resin layer. For the inner surface layer 2 and the outer surface layer 5, appropriate materials are selected according to the performance required for the hose 1, and appropriate layer thicknesses are set. There are no particular limitations on the materials used, but for example, butyl rubber, nitrile rubber, fluororubber, chlorinated polyethylene, nylon 11, nylon 6, nylon 6-66, EVOH, etc. are used for the inner surface layer 2. For example, EPDM, silicone rubber, natural rubber, butyl rubber, ethylene acrylic rubber, etc. are used for the outer surface layer 5.

[0014] The thickness of the interlayer rubber layer 6 varies depending on the outer diameter of the hose, but is, for example, 0.1 mm to 0.5 mm. The interlayer rubber layers 6b to 6d bond and integrate the reinforcing layers 3 stacked adjacent to each other in the radial direction, and function as a buffer between these reinforcing layers 3. The innermost interlayer rubber layer 6a bonds the innermost reinforcing layer 3a and the fiber layer 7, and functions as a buffer between them. Each of the interlayer rubbers 6a to 6d may function as a barrier to prevent the permeation of gas, moisture, etc. flowing through the hose 1. Examples of rubber types for the interlayer rubber layer 6 include acrylonitrile-butadiene rubber, styrene-butadiene rubber, chloroprene rubber, and blends thereof.

[0015] In this embodiment, the hose 1 has four reinforcing layers 3. The reinforcing layers 3 have a spiral structure in which metal cords 4 are wound helically at a predetermined braiding angle A (A1, A2, A3, A4) around the hose axis CL. Specifically, the innermost reinforcing layer 3a is set to a braiding angle A1, and the reinforcing layers 3b, 3c, 3d positioned successively on the outer periphery side are set to braiding angles A2, A3, A4. The winding directions of the metal cords 4 of the reinforcing layers 3 arranged adjacent to each other in the radial direction are opposite to each other.

[0016] Each of the braid angles A1 to A4 is set to 52° or more and 57° or less. In this embodiment, each of the braid angles A1 to A4 is substantially the same, but the braid angle A can be made larger or smaller as it approaches the outer periphery of the reinforcing layer 3.

[0017] The number of layers of the reinforcing layer 3 is, for example, 2 to 8, and a desired number of layers can be adopted. Each reinforcing layer 3 is formed of metal cords 4 of the same specifications, and in this embodiment, all the reinforcing layers 3 have substantially the same specifications.

[0018] The metal cord 4 is made by twisting together a number of metal wires. Various steel wires that are used as members forming the reinforcing layer of a general rubber hose are used as the metal cord 4. The wire diameter of the metal cord 4 is, for example, 0.20 mm or more and 1.00 mm or less.

[0019] The fiber layer 7 has a braided structure formed by braiding fiber cords 8. The braid angle A5 of the fiber cords 8 is set to, for example, about 54° or more and 55° or less. The fiber cords 8 are formed by twisting fiber strands together. The number of twists of the fiber cords 8 is, for example, 3 to 20 times per 10 cm. The fineness of the fiber cords 8 is, for example, 235 dtex or more and 5500 dtex or less.

[0020] The braid density of the fiber layer 7 is, for example, 65% or more and 95% or less, more preferably 75% or less. % or more The braid density should be 85% or less. This braid density indicates the area ratio of the fiber cords 8 in the fiber layer 7 as a percentage, and is 100% when the fiber cords 8 are braided without any gaps. If the braid density is too high, it is disadvantageous for firmly joining the fiber layer 7 to the inner layer 2 and the interlayer rubber layer 6a. If the braid density is too low, the performance of protecting the inner layer 2 from the metal cords 4 will be insufficient. Therefore, it is preferable that the braid density of the fiber layer 7 is in the above-mentioned range.

[0021] Examples of materials for the fiber cord 8 include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), aramid, polyparaphenylene benzoxazole (PBO), nylon 66, rayon, vinylon, cotton, etc. The fiber cord 8 can be made of one of these fibers or a mixture of multiple types.

[0022] The fiber cords 8 are twisted as described above and are surface-treated by applying an RFL liquid (resorcinol-formaldehyde-latex liquid) to the surface. The RFL liquid may be an NBR or SBR liquid. In the vulcanization process when manufacturing the hose 1, the fiber cords 8 (fiber layer 7) that have been subjected to this surface treatment are more firmly bonded to the adjacent interlayer rubber layer 6a and inner surface layer 2 and integrated.

[0023] The amount of RFL liquid adhered to the fiber cord 8 by this surface treatment should be 2% or more of the mass of the fiber cord 8. The amount of RFL liquid adhered can be determined by measuring the mass of the fiber cord 8 before and after this surface treatment and calculating the difference between the two. If the amount of RFL liquid adhered is less than 2% of the mass of the fiber cord 8, the adhesive strength between the fiber cord 8 (fiber layer 7) and the adjacent interlayer rubber layer 6a and inner surface layer 2 may be insufficient. On the other hand, if the amount of RFL liquid adhered is excessive, the fiber cord 8 may become too hard and its durability may decrease, so the amount of RFL liquid adhered is set to, for example, 5% or less of the mass of the fiber cord 8.

[0024] The amount of RFL liquid applied can be adjusted, for example, by adjusting (changing) the concentration of the RFL liquid, or by adjusting the degree of squeezing when squeezing the fiber cord 8 with a roll after immersing it in the RFL liquid, or the extent to which air is blown to blow away the RFL liquid.

[0025] The adhesive strength between the fiber layer 7 and the inner surface layer 2 and the adhesive strength between the innermost interlayer rubber layer 6a and the fiber layer 7 are each preferably 2.5 kN / m or more, and more preferably 3.5 kN / m or more. These adhesive strengths are values ​​obtained in accordance with the method specified in JIS K6330.

[0026] As illustrated in Fig. 3, this hose 1 is used with at least one of its longitudinal ends attached to a movable part 12 of a device or equipment that moves. In this embodiment, a hose fitting 9a crimped to one longitudinal end of the hose 1 is connected to a fixed part 11 of the device or equipment that does not move via a fitting 10. A hose fitting 9b crimped to the other longitudinal end of the hose 1 is connected to a movable part 12 of the device or equipment that moves via the fitting 10. Therefore, this hose 1 is used with only one of its longitudinal ends attached to the movable part 12. There is also a case where both longitudinal ends of the hose 1 are attached to the movable part 12. An example of the movable part 12 is the arm or boom of a construction machine such as a power shovel.

[0027] Movable part 12 may move in a fixed direction or in an arbitrary direction, for example. Hose 1 is repeatedly bent as movable part 12 moves. During this bending, particularly large loads act on both longitudinal ends of hose 1 (near hose fittings 9a, 9b) and the longitudinal center.

[0028] In this hose 1, a fiber layer 7 and an interlayer rubber layer 6a are interposed between the inner surface layer 2 and the innermost reinforcing layer 3a. Furthermore, the fiber cords 8 constituting the fiber layer 7 are twisted to improve convergence, thereby improving strength and abrasion resistance. In addition, the fiber cords 8 are surface-treated to allow the RFL liquid to adhere to their surfaces, which is advantageous for more strongly bonding the fiber cords 8 (fiber layer 7) to the inner surface layer 2 and the interlayer rubber layer 6a.

[0029] As a result, even under conditions where the internal pressure of the hose 1 is high and at least one of the longitudinal ends of the hose 1 is attached to a moving movable part 12 for use, the inner layer 2 is protected from the metal cords 4 forming the innermost reinforcing layer 3a by the interposed fiber layer 7 and interlayer rubber layer 6a. Therefore, even if the metal cords 4 forming the reinforcing layer 3a move as the hose 1 moves (bends), the fiber layer 7 and interlayer rubber layer 6a firmly integrated with the inner layer 2 cooperate to resist and absorb the movement of the metal cords 4. This is advantageous in preventing a problem in which the inner layer 2, fiber layer 7, and interlayer rubber layer 6a peel off from each other, making it difficult to restrain the movement of the metal cords 4 forming the innermost reinforcing layer 3a, and the fiber layer 7 and interlayer rubber layer 6a gradually wear out, even damaging the inner layer 2.

[0030] In order to fully integrate the inner surface layer 2, the fiber layer 7, and the interlayer rubber layer 6a, the amount of RFL liquid attached to the fiber cord 8 is set to 2% or more of the mass of the fiber cord 8, as described above. The adhesive strength between the fiber layer 7 and the inner surface layer 2 and the adhesive strength between the interlayer rubber layer 6a and the fiber layer 7 are preferably 2.5 kN / m or more, and more preferably 3.5 kN / m or more, as described above. If the difference between the adhesive strength between the fiber layer 7 and the inner surface layer 2 and the adhesive strength between the interlayer rubber layer 6a and the fiber layer 7 is excessively large, the weaker adhesive strength is more likely to cause interlayer peeling, which is disadvantageous in protecting the inner surface layer 2 from the metal cord 4. Therefore, when the absolute value of the adhesive strength is low (for example, 1.5 kN / m or more and 2.5 kN / m or less), the difference between the adhesive strength between the fiber layer 7 and the inner surface layer 2 and the adhesive strength between the interlayer rubber layer 6a and the fiber layer 7 should be within 0.2 kN / m, more preferably within 0.1 kN / m. EXAMPLES

[0031] As shown in Table 1, six types of hoses with similar structures to those shown in Figs. 1 and 2 were manufactured by varying only the fiber cord specifications (Examples 1 to 4, Comparative Example, and Conventional Example), and bending durability tests were conducted. Each metal cord was a steel wire (brass-plated steel wire) with a wire diameter of 0.38 mm, which was made by twisting together metal wires. The number of layers of the reinforcing layer was six, and the braid angle A of the metal cord in each reinforcing layer was roughly the same, about 54° to 55°. The thickness of each interlayer rubber layer was about 0.3 mm. The inner layer was made of acrylonitrile-butadiene rubber and styrene-butadiene rubber, the outer layer was made of chloroprene rubber and styrene-butadiene rubber, and the interlayer rubber layer was made of acrylonitrile-butadiene rubber. The braid angle A of the fiber cord in each test sample was roughly the same, about 54° to 55°, and the braid density was also roughly the same, about 80%.

[0032] As shown in FIG. 4, a hose metal fitting 9a was attached to one end of each test sample (hose 1) having a length of 1800 mm and an outer diameter of 38 mm, and connected to a fixed member 11 via a mounting fixture 10. A hose metal fitting 9b was attached to the other end of the test sample, and attached to the tip of a cylinder rod 13a of a hydraulic cylinder 13. This caused the test sample to be bent at approximately 90°. Each test sample was filled with hydraulic oil at approximately 100°C, and internal pressures of 33.5 MPa and 43.9 MPa were repeatedly applied by a trapezoidal wave with a frequency of 0.58 Hz, while the cylinder rod 13a was moved back and forth to repeatedly bend the hose 1. The stroke of the cylinder rod 13a was 430 mm, and the movement cycle was 0.5 Hz. The bending durability test was continued until the test sample was damaged, and the number of times the test sample was bent (the number of times the cylinder rod 13a was moved back and forth) at the time of damage was shown in Table 1 as the number of times of durability. The adhesive strength between the fiber layer and the inner surface layer, and the adhesive strength between the fiber layer and the innermost interlayer rubber layer are shown as the adhesive strength to the inner surface layer and the adhesive strength to the interlayer rubber layer, respectively, in Table 1. These adhesive strengths were values ​​measured by the test method described above.

[0033] [Table 1]

[0034] It can be seen from the results in Table 1 that the durability is improved compared to the conventional example in Examples 1 to 4. In particular, the durability is significantly improved in Examples 1 and 2. [Explanation of symbols]

[0035] 1 Hose 2. Inner layer 3(3a, 3b, 3c, 3d) Reinforcement layer 4 Metal Cord 5 Outer layer 6(6a, 6b, 6c, 6d) Interlayer rubber layer 7 Fiber layer 8 Textile Code 9a, 9b Hose fittings 10 Mounting fixture 11 Fixed part 12 Moving parts 13 Fluid cylinder (vibration mechanism) 13a Cylinder rod CL Hose shaft center

Claims

1. A hose having a spiral structure comprising an inner layer and an outer layer laminated coaxially, a plurality of reinforcing layers laminated with an interlayer rubber layer interposed between the inner layer and the outer layer, a fiber layer laminated on the outer peripheral surface of the inner layer, and an interlayer rubber layer interposed between the fiber layer and the innermost reinforcing layer, each of the reinforcing layers being formed by winding a metal cord in a spiral shape, The operating pressure of the hose is 20 MPa or more and 50 MPa or less, The hose is characterized in that the fiber layer has a braid structure formed by braiding fiber cords that have been twisted and surface-treated to adhere RFL liquid to the surface, and the fineness of the fiber cords is 2100 dtex or more and 5500 dtex or less.

2. A hose as described in claim 1, wherein the number of twists of the fiber cord is 3 to 10 times per 10 cm.

3. A hose as described in claim 1 or 2, wherein the amount of the RFL liquid adhered to the fiber cord by the surface treatment is 2% or more of the mass of the fiber cord, and the adhesive strength between the fiber layer and the inner layer and the adhesive strength between the interlayer rubber layer laminated on the outer surface of the fiber layer and the fiber layer are each 2.5 kN / m or more.

4. 4. The hose according to claim 3, wherein the adhesive strength between the fiber layer and the inner surface layer and the adhesive strength between the interlayer rubber layer laminated on the outer peripheral surface of the fiber layer and the fiber layer are each 3.5 kN / m or more.

5. A hose as described in claim 1 or 2, wherein the amount of the RFL liquid adhered to the fiber cord by the surface treatment is less than 2% of the mass of the fiber cord, and the adhesive strength between the fiber layer and the inner layer and the adhesive strength between the interlayer rubber layer laminated on the outer surface of the fiber layer and the fiber layer are each 1.5 kN / m or more and less than 2.5 kN / m, and the difference between the respective adhesive strengths is within 0.2 kN / m.

6. A method for using a hose according to any one of claims 1 to 5, comprising: A method for using a hose, wherein at least one of the longitudinal ends of the hose is attached to a moving movable part, and the hose is repeatedly bent by the movement of the moving part.

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