JP2019138312A - Method for manufacturing high pressure hose - Google Patents

Abstract

To provide a method for manufacturing high pressure hose capable of preventing damage even in a case where high hose inner pressure acts repeatedly, and excellent in durability.SOLUTION: Upon molding a hose molded body 1A in which a reinforcing layer 3 made of a fiber reinforcing material 4 is coaxially laminated between an unvulcanized rubber layer 2b and an unvulcanized outside rubber layer 5 that are coaxially laminated, a high-pressure hose 1 is manufactured by vulcanizing the molded hose molded body 1A using the fiber reinforcing material 4 that has been heat-treated in advance to reduce the dry heat shrinkage rate to a predetermined range.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing a high-pressure hose, and more particularly to a method for manufacturing a high-pressure hose that is not easily damaged even when a high internal pressure acts repeatedly and has excellent durability.

  In a high-pressure hose, in order to withstand a high internal pressure, a reinforcing layer having a spiral structure or a blade structure formed of, for example, a fiber reinforcing material is interposed between the inner rubber layer and the outer rubber layer. This fiber reinforcing material shrinks after being heated in the vulcanization process when manufacturing the hose. When the so-called dry heat shrinkage rate of the fiber reinforcement is large, the disturbance of the fiber reinforcement in the manufactured hose becomes large. In a region where the fiber reinforcing material is disturbed and the gap between the fiber reinforcing materials becomes large, if an excessive internal pressure acts repeatedly, a problem that the rubber layer is damaged along the gap between the fiber reinforcing materials is likely to occur.

  A hose for preventing such a problem has been proposed (see Patent Document 1). In Patent Document 1, it is proposed to devise a technique that does not cause an unbalanced yarn gap in spiral winding while using a reinforcing yarn having a large dry heat shrinkage rate, or on the outer periphery of the inner rubber layer when forming a hose. It has been proposed to provide relief in the inner rubber layer itself against the expansion pressure of the inner rubber layer by forming irregularities (claims, paragraphs 0008, 0009, etc.).

  When using a reinforcing yarn having a high dry heat shrinkage rate, there are fewer choices of materials that can be used. When the irregularities on the outer periphery of the inner rubber layer are formed, the reinforcing yarn is hardly disturbed during braiding, but there are irregularities, so there are disadvantages that the inner rubber layer is thin and lacks dimensional stability. Since the work and jig | tool which form such an unevenness | corrugation are needed, complexity will increase. Therefore, there is room for improvement in obtaining a hose that prevents the above-described problems.

JP 11-325331 A

  An object of the present invention is to provide a method for producing a high-pressure hose that is not easily damaged even when a high internal pressure acts repeatedly and that has excellent durability.

  In order to achieve the above object, the high-pressure hose according to the present invention is manufactured by coaxially reinforcing a reinforcing layer made of fiber reinforcing material between an unvulcanized inner layer and an unvulcanized outer rubber layer that are laminated coaxially. In the high pressure hose manufacturing method for manufacturing a high pressure hose by vulcanizing the hose molded body laminated on, the fiber reinforcement is preheated to reduce the dry heat shrinkage rate to a predetermined range, The hose molded body is formed using the heat-treated fiber reinforcing material.

  According to the present invention, when forming a hose molded body, the reinforcing layer is formed using the fiber reinforcing material that has already been heat-treated to reduce the dry heat shrinkage rate to a predetermined range. Therefore, in the high-pressure hose manufactured by vulcanizing the hose molded body, the shrinkage of the fiber reinforcing material is suppressed. Along with this, the disturbance of the fiber reinforcing material is reduced, so that a problem that the rubber layer is damaged is less likely to occur even when a high internal pressure is repeatedly applied. Moreover, since the dry heat shrinkage rate of the fiber reinforcing material is small, the dimensional stability of the hose (reinforcing layer) before and after vulcanization is improved.

It is a side view which illustrates typically the high-pressure hose manufactured by this invention partially cut. It is explanatory drawing which illustrates typically the high pressure hose of FIG. 1 by a cross-sectional view. FIG. 2 is an explanatory diagram schematically illustrating a part of the high-pressure hose in FIG. It is explanatory drawing which illustrates the manufacturing process of the high pressure hose of FIG. FIG. 6 is a side view schematically illustrating another high-pressure hose manufactured according to the present invention with a part thereof cut.

  Hereinafter, the high-pressure hose of the present invention will be described based on the embodiments shown in the drawings.

  In the high-pressure hose 1 manufactured by the present invention illustrated in FIGS. 1 to 3, the inner layer 2 (2a, 2b), the reinforcing layer 3 (3a, 3b), and the outer rubber layer 5 are coaxial in order from the inner peripheral side. Are stacked. Further, an interlayer rubber layer 6 is interposed between the reinforcing layers 3a and 3b stacked adjacent to each other in the radial direction of the hose 1. A one-dot chain line CL in the drawing indicates a hose axis. In this embodiment, the inner surface layer 2 is formed of a resin layer 2a and a rubber layer 2b that is coaxially laminated on the outer peripheral surface of the resin layer 2a. The resin layer 2a and the rubber layer 2b are firmly joined. The inner surface layer 2 may be formed of only the rubber layer 2b.

  In the high-pressure hose 1, the use internal pressure is set to a high pressure of, for example, 3.5 MPa or more, or a higher pressure of 5.3 MPa or more. The upper limit of the use internal pressure is, for example, 10.0 MPa. The hose outer diameter is, for example, 13 mm or more and 20 mm or less. Examples of the fluid flowing through the high-pressure hose 1 include hydraulic oil, refrigerant, and refrigeration oil.

  For the inner layer 2 and the outer rubber layer 5, an appropriate material is selected according to the required performance for the high-pressure hose 1, and an appropriate layer thickness is set. Although the material to be used is not particularly limited, for example, nylon 11, nylon 6, nylon 6-66, EVOH, or the like is used for the resin layer 2a. Nylon is mixed with a plasticizer. For example, butyl rubber, nitrile rubber, fluorine rubber, chlorinated polyethylene or the like is used for the rubber layer 2b, and EPDM, silicone rubber, natural rubber, butyl rubber, ethylene acrylic rubber or the like is used for the outer rubber layer 5, for example.

  The reinforcing layer 3 is formed of a fiber reinforcing material 4, and an appropriate material, structure, or the like is selected based on pressure resistance performance, bending performance, and the like required for the hose 1. Examples of the fiber reinforcing material 4 include polyethylene terephthalate (PET) fiber, polyethylene naphthalate (PEN) fiber, aramid fiber, polyparaphenylene benzoxazole (PBO) fiber, 66 nylon fiber, rayon fiber, vinylon fiber, and cotton fiber. To do. These fibers can be used alone or in combination of a plurality of types to form the fiber reinforcement 4. The outer diameter (thickness) of the fiber reinforcement 4 is, for example, not less than 0.2 mm and not more than 1.2 mm.

  In this embodiment, the reinforcing layer 3 has two layers, but may be set to a plurality of layers such as one layer, three layers, and four layers. In this embodiment, the reinforcing layer 3 has a spiral structure in which the fiber reinforcing material 4 is wound around the spiral at a predetermined braiding angle with respect to the hose axis CL. In the reinforcing layer 3, the winding direction of the fiber reinforcing material 4 is reversed in the stacking order.

  As illustrated in FIG. 3, in each of the reinforcing layers 3a and 3b, the fiber reinforcements 4 are arranged at substantially equal intervals in the longitudinal direction of the hose (the extending direction of the hose axis CL), and the radial direction of the hose. Are arranged at substantially the same level, and the arrangement is such that the disturbance is suppressed. Further, the layer thickness of the interlayer rubber layer 6 is substantially uniform in the hose longitudinal direction. In addition, although the cross section of the actual fiber reinforcing material 4 becomes an elliptical shape slightly crushed in the hose radial direction, it is described as a circular cross section for convenience in FIG.

  The layer thickness of the interlayer rubber layer 6 varies depending on the hose outer diameter and the like, but is, for example, 0.1 mm or more and 0.5 mm or less. The interlayer rubber layer 6 joins the reinforcing layers 3a and 3b stacked adjacent to each other in the radial direction, and becomes a cushioning material for the fiber reinforcing materials 4 forming the reinforcing layers 3a and 3b. Yes. The case where the interlayer rubber layer 6 is not interposed between the reinforcing layers 3 is also an object of the present invention.

  The present invention was created by paying attention to the dry heat shrinkage of the fiber reinforcing material 4 constituting the reinforcing layer 3. The high-pressure hose 1 is manufactured by vulcanizing the molded hose molded body 1A. In the present invention, the dry heat shrinkage rate is reduced to a predetermined range by heat-treating the fiber reinforcement 4 in advance. The hose molded body 1 </ b> A is molded using the fiber reinforcement 4. In addition, in this specification, the same code | symbol is attached | subjected to the same hose structural member before vulcanization of 1A of hose molded objects.

  The dry heat shrinkage rate is measured by the dry heat shrinkage rate (Method B) after heating specified in JIS L 1017: 2002. The predetermined range of the heat shrinkage rate is, for example, 1.2% or less.

  In the above heat treatment, for example, under a condition in which a tension is not substantially applied to the fiber reinforcement 4, the state heated to a predetermined temperature is maintained for a predetermined time, and then cooled to room temperature. The predetermined temperature to be heated in this heat treatment is preferably, for example, equal to or higher than the vulcanization temperature (the highest vulcanization temperature) of the hose molded body 1A.

  The predetermined time for maintaining the heated state in this heat treatment may be set within a time range necessary for reducing the dry heat shrinkage rate within the predetermined range. In addition, in order to cool the heated fiber reinforcement 4 to normal temperature, natural cooling may be sufficient and it can also be forcedly cooled using a cooler etc. In the case of forced cooling, the cooling time is preferably 50% or less of the natural cooling.

  In the present invention, the fiber reinforcing material 4 that has been previously heat-treated in this way is prepared, and for example, the high-pressure hose 1 is manufactured as follows.

  As illustrated in FIG. 4, the hose forming body 1 </ b> A is formed by sequentially stacking hose constituent members on the outer peripheral side of the mandrel 7 that moves forward. Specifically, first, the resin layer 2 a and the unvulcanized rubber layer 2 b are laminated on the outer peripheral surface of the mandrel 7. Next, the reinforcing layer 3a is laminated on the outer peripheral surface of the inner layer 2 (rubber layer 2b). The reinforcing layer 3a is formed by laminating the fiber reinforcing material 4 from the reinforcing layer molding machine 8 while rotating the reinforcing layer molding machine 8 around the mandrel 7, and laminating.

  Next, an unvulcanized interlayer rubber layer 6 is laminated on the outer peripheral surface of the reinforcing layer 3a. Next, the reinforcing layer forming machine 8 is rotated around the mandrel 7 while the fiber reinforcing material 4 is fed out from the reinforcing layer forming machine 8 on the outer peripheral surface of the interlayer rubber layer 6, and the reinforcing layer 3 b is formed and laminated. At this time, the reinforcing layer forming machine 8 rotates in the opposite direction to the case of forming the reinforcing layer 3a. Next, the hose formed body 1A is formed by laminating the unvulcanized outer rubber layer 5 on the outer peripheral surface of the reinforcing layer 3b. In addition, the tension at the time of laminating | stacking (winding) the fiber reinforcement 4 may be the same as the conventional method.

  Next, the covering member 9 is laminated on the outer peripheral surface of the hose molded body 1A. The covering member 9 is made of polymethylpentene resin or the like as in the conventional method. The hose molded body 1A covered with the covering member 9 is heated at a predetermined vulcanization temperature for a predetermined time in a vulcanizing can or a vulcanizing tank to steam vulcanize the hose molded body 1A. By this vulcanization step, the unvulcanized rubber layer 2b (inner layer 2), the interlayer rubber layer 6 and the outer rubber layer 5 become vulcanized rubber and are integrated with the resin layer 2a and the reinforcing layer 3. Then, the high pressure hose 1 illustrated in FIGS. 1 to 3 is completed by removing the covering member 9 and the mandrel 7.

  According to the present invention, the reinforcing layer 3 of the hose molded body 1A is formed using the fiber reinforcing material 4 that has been subjected to the above-described heat treatment to reduce the thermal shrinkage rate within a predetermined range. That is, the fiber reinforcement 4 is subjected to heat treatment that suppresses in advance heat shrinkage between the hose molded body 1A before vulcanization and after vulcanization. Therefore, the fiber reinforcement 4 heated in the vulcanization process of the hose molded body 1A does not shrink excessively in the completed high-pressure hose 1. Therefore, in the high-pressure hose 1 that has undergone the vulcanization process, the shrinkage that causes the disorder of the arrangement of the fiber reinforcements 4 is suppressed, and the disorder of the fiber reinforcements 4 is reduced as illustrated in FIG. It becomes possible.

  In the high-pressure hose 1, the gap between the fiber reinforcements 4 arranged adjacent to each other in the reinforcing layers 3 a and 3 b does not become larger than necessary. Therefore, even if a high internal pressure is repeatedly applied to the high-pressure hose 1, it is advantageous for preventing a problem that the rubber layers 2 b, 6, and 5 are damaged due to cracks generated in the gaps between the fiber reinforcements 4. As a result, the durability of the high-pressure hose 1 is improved.

  Since the shrinkage of the fiber reinforcement 4 after vulcanization is suppressed, the dimensional stability before and after vulcanization is improved (the dimensional change between the hose molded body 1A and the high-pressure hose 1 is reduced). Since the reduction of the layer thickness of the inner layer 2 (rubber layer 2b) accompanying the shrinkage of the fiber reinforcement 4 can be suppressed, the sealing property between the inner layer 2 and the hose fitting is ensured, the leakage of the hose circulation fluid is prevented, and the inner layer 2 There is also an advantage in improving durability.

  In the present invention, even if the material has an essentially large dry heat shrinkage rate, it can be used as the fiber reinforcement 4 if the heat shrinkage rate can be reduced to a predetermined range by heat treatment in advance. Therefore, there is an advantage that there are many choices of materials that can be used as the fiber reinforcement 4.

  Further, when the hose molded body 1A is molded, it is not necessary to laminate the fiber reinforcing material 4 on the outer peripheral surfaces of the rubber layers 2a and 6 having irregularities. Therefore, there is also a low risk that the fiber reinforcing material 4 is disturbed in the forming stage of the hose molded body 1A.

  As the dry heat shrinkage rate of the fiber reinforcement 4 is reduced, it becomes advantageous to suppress the turbulence by suppressing the shrinkage of the fiber reinforcement 4 after vulcanization. Therefore, by performing the heat treatment described above, the dry heat shrinkage rate of the fiber reinforcing material 4 may be reduced to 1.2% or less, more preferably 0.9% or less, and even more preferably 0.1% or less.

  Further, as the braid density of the fiber reinforcement 4 is increased, it is advantageous to suppress the turbulence by suppressing the shrinkage of the fiber reinforcement 4 after vulcanization. Therefore, the braid density of the fiber reinforcement 4 is preferably 90% or more, more preferably 95% or more, and even more preferably 100%. The braided density indicates the area ratio of the fiber reinforcing material 4 in the reinforcing layer 3 as a percentage, and is 100% when the gap between the braided (arranged) fiber reinforcing materials 4 is zero.

  In the present invention, another layer (such as a resin layer) can be added to the inner peripheral side of the inner layer 2, and another layer (such as a resin layer) can be added to the outer peripheral side of the outer rubber layer 5. Alternatively, another layer (such as a resin layer) can be added between the inner layer 2 and the outer rubber layer 5.

  In another high-pressure hose 1 manufactured according to the present invention illustrated in FIG. 5, the reinforcing layer 3 has a blade structure in which fiber reinforcing materials 4 are woven in a knitted pattern. The fiber reinforcing material 4 forming each of the reinforcing layers 3a and 3b is braided at a predetermined braiding angle with respect to the hose axis CL. Other configurations are the same as those of the high-pressure hose 1 illustrated in FIG.

  Therefore, even when manufacturing the high-pressure hose 1, when the hose molded body 1 </ b> A is molded, the fiber reinforcing material 4 in which the dry heat shrinkage rate is reduced to a predetermined range by heat treatment in advance is used. Moreover, also in this high pressure hose 1, the arrangement similar to the high pressure hose 1 illustrated in FIG. 1 can be performed.

  As shown in Table 1, the test of the high-pressure hose having the structure illustrated in FIG. 1 is made by changing only the presence or absence of the prior heat treatment of the fiber reinforcement made of PET (polyethylene terephthalate) used when forming the hose molded body. Three types of samples (Comparative Examples, Examples 1 and 2) were prepared, and durability and changes in the thickness of the inner layer before and after vulcanization were confirmed. The resin layer constituting the inner surface layer was made of nylon 6 and the layer thickness before vulcanization was 0.12 mm, and the rubber layer constituting the inner surface layer was made of butyl rubber and the layer thickness before vulcanization was 1.0 mm. The test results are shown in Table 1.

  In the durability test, an internal pressure of 5.3 MPa was repeatedly given 350,000 times at a cycle of 30 times per minute under the condition of 135 ° C. for each test sample. The number of times the internal pressure is applied until the hose is broken is measured, and the greater the number, the better the durability.

  In the preliminary heat treatment, the fiber reinforcement was naturally cooled by heating at 160 ° C. for 30 minutes under a condition in which no tension was applied to the fiber reinforcement. Each test sample was produced by vulcanizing the hose molded body for a predetermined time at a predetermined vulcanization temperature equal to or lower than the temperature of the prior heat treatment of the fiber reinforcement.

  From the results shown in Table 1, it can be seen that Examples 1 and 2 are superior in durability to the comparative example, and the change in the thickness of the inner layer is small. Moreover, it has confirmed that the disorder | damage | failure of the arrangement | sequence of a fiber reinforcement material was suppressed compared with the comparative example.

DESCRIPTION OF SYMBOLS 1 High pressure hose 1A Hose molded object 2 Inner layer 2a Resin layer 2b Rubber layer 3 (3a, 3b) Reinforcement layer 4 Fiber reinforcement 5 Outer rubber layer 6 Interlayer rubber layer 7 Mandrel 8 Reinforcement layer molding machine 9 Cover member CL Hose axis

Claims (5)

High pressure is achieved by vulcanizing a hose molded body in which a reinforcing layer made of a fiber reinforcing material is coaxially laminated between an unvulcanized inner layer and an unvulcanized outer rubber layer laminated coaxially. In the manufacturing method of the high pressure hose for manufacturing the hose,
A high-pressure hose characterized by preliminarily reducing the dry heat shrinkage rate to a predetermined range by heat-treating the fiber reinforcement, and forming the hose molded body using the heat-treated fiber reinforcement. Production method.   The method for manufacturing a high-pressure hose according to claim 1, wherein the predetermined range is 1.2% or less.   The manufacturing method of the high pressure hose of Claim 1 or 2 which heats the said fiber reinforcement in the said heat processing more than the vulcanization temperature of the said hose molded object.   The fiber reinforcing material is at least one of polyethylene terephthalate fiber, polyethylene naphthalate fiber, aramid fiber, polyparaphenylene benzoxazole fiber, 66 nylon fiber, rayon fiber, vinylon fiber, and cotton fiber. A method for producing a high-pressure hose according to claim 1.   The method for producing a high-pressure hose according to any one of claims 1 to 4, wherein the reinforcing layer is formed by forming a braid density of the fiber reinforcing material to 90% or more when forming the hose formed body.

Images