Hose for pouring ready-mix concrete

Abstract

This invention provides a concrete pouring hose that allows for the visual detection of rupture of the pressure-resistant layer caused by the pumping of ready-mix concrete. [Solution] The concrete pouring hose has a tube-shaped inner rubber layer 22 that guides the pumping of concrete 30, a pressure-resistant layer 23 formed on the outer surface of the inner rubber layer 22 that inhibits the penetration of concrete 30 and is reinforced with reinforcing cords 231a and 233a, a first outer rubber layer 24 formed on the outer surface of the pressure-resistant layer 23 and integrally molded with the pressure-resistant layer 23, and a second outer rubber layer 25 formed on the outermost outer surface of the first outer rubber layer 24 and having a higher tensile strength than the first outer rubber layer 24.

Description

Technical Field

[0006] , , ,

[0001] The present invention relates to a hose used for placing fresh concrete compositions.

Background Art

[0002] Patent Document 1 discloses a hose for pumping a fluid. The hose is composed of an inner core tube and an outer cover, and a pressure-resistant reinforcing layer with a braided structure sandwiched therebetween. When the inner core tube is damaged, the internal fluid (hydraulic oil) can pass through the pressure-resistant reinforcing layer to expand the outer cover, making it possible to detect the damage.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Regarding the hose of Patent Document 1, when pumping fresh concrete (fresh concrete) as a fluid, the aggregates of the fresh concrete may clog the gaps between the cords of the pressure-resistant reinforcing layer, and it may not function properly.

[0005] An object of the present invention is to provide a hose for placing fresh concrete capable of detecting the breakage of the pressure-resistant layer by appearance.

Means for Solving the Problems

[0006] The hose for placing fresh concrete of the present invention includes a tube-shaped inner rubber layer for guiding the pumping of fresh concrete, a pressure-resistant layer formed on the outer peripheral surface of the inner rubber layer, which inhibits the penetration of fresh concrete and is reinforced with reinforcing cords, a first outer rubber layer formed on the outer peripheral surface of the pressure-resistant layer and integrally molded with the pressure-resistant layer, and a second outer rubber layer formed on the outer peripheral surface of the first outer rubber layer, which is the outermost peripheral surface and has a higher tensile breaking elongation than the first outer rubber layer.

[0007] This configuration allows the pressure-resistant layer and the first outer rubber layer to rupture as they are worn down by friction from the concrete being pumped. When the integrally molded pressure-resistant layer and the first outer rubber layer rupture, the second outer rubber layer expands radially outward due to internal pressure in the area where the pressure-resistant layer and the first outer rubber layer have been removed, making it possible to detect the damage from the outside before it occurs. [Brief explanation of the drawing]

[0008] [Figure 1] Schematic diagram showing the overall configuration of a concrete pump truck using a concrete pouring hose according to the first embodiment. [Figure 2] Cross-sectional view of one side of a concrete pouring hose according to the first embodiment. [Figure 3] A diagram illustrating the progression of wear on the hose body due to concrete in the concrete pouring hose according to the first embodiment. [Figure 4] A diagram illustrating the progression of wear on the hose body due to concrete in a concrete pouring hose according to the second embodiment. [Modes for carrying out the invention]

[0009] (First Embodiment) A concrete pump truck 1 using the concrete pouring hose 9 of this disclosure will be described with reference to Figure 1.

[0010] The concrete pump truck 1 pours ready-mix concrete, which has been transported by a mixer truck or the like, to the construction site by pumping (transporting under pressure). As shown in Figure 1, the concrete pump truck 1 consists of a hopper 2 that receives the ready-mix concrete, a pump 3 connected to the hopper 2, a transport system 4 connected to the discharge pipe of the pump 3, and a boom 5 that supports the transport system 4.

[0011] Pump 3 draws up ready-mix concrete from hopper 2 and pumps it under pressure. Pump 3 can be a piston type or a squeeze type. A piston type pumps the concrete under pressure using a hydraulic cylinder. A squeeze type pumps the concrete under pressure by pushing up a transport tube with rollers.

[0012] The transport system 4 transports the ready-mix concrete discharged from the pump 3. The transport system 4 comprises a transport pipe 6 connected sequentially from the pump 3, a docking hose 7, a tapered pipe 8, and a tip hose (hereinafter referred to as the "concrete pouring hose") 9.

[0013] The transport pipe 6 receives the ready-mix concrete pumped by the pump 3. The transport pipe 6 is, for example, made of metal.

[0014] The docking hose 7 receives ready-mix concrete from the transport pipe 6. The docking hose 7 is a hose in which a fitting and a flexible hose are integrally molded. The docking hose 7 and the transport pipe 6 are connected by fixing the fitting and the end of the transport pipe 6 with a fastener. The docking hose 7 and the tapered pipe 8, and the tapered pipe 8 and the ready-mix concrete pouring hose 9 are fixed in the same manner. For example, the docking hose 7 is made of rubber. The inner diameter of the docking hose 7 is larger than the inner diameter of the ready-mix concrete pouring hose 9.

[0015] The tapered pipe 8 is a pipe that adjusts the inner diameter between hoses and is connected between the docking hose 7 and the concrete pouring hose 9. For example, the tapered pipe 8 is made of metal.

[0016] The concrete pouring hose 9 is connected at one end to the tapered pipe 8, and the pressurized concrete is pushed out from the other end of the concrete pouring hose 9 and poured at the construction site.

[0017] The boom 5 has multiple arms that rotate relative to each other around a horizontal axis. The boom 5 is configured to be foldable. The transport pipe 6 is attached to the boom 5. The transport system 4 is lifted upward by the action of the boom 5.

[0018] A first embodiment of the fresh concrete placing hose 9 of the present disclosure will be described with reference to FIG. In the following description, the radial direction of the fresh concrete placing hose 9 is the radial direction P (the inner side in the radial direction is referred to as "inner diameter side", and the outer side in the radial direction is referred to as "outer diameter side"), and the circumferential direction is the circumferential direction S.

[0019] As shown in FIG. 2, the fresh concrete placing hose 9 includes a hose body 20 connected to a base fitting. The hose body 20 is a flexible tubular body. The hose body 20 has an inner diameter of about 4 inches to 5 inches, for example. The hose body 20 has an inner rubber layer 22, a pressure-resistant layer 23, a first outer rubber layer 24, and a second outer rubber layer 25 laminated in order from the inner diameter side to the outer diameter side.

[0020] The base fitting is an annular body and is connected to at least one end in the longitudinal direction of the hose body 20. The base fitting is attached to the tapered pipe 8. The material of the base fitting is not particularly limited, but a metal one is used.

[0021] The inner rubber layer 22 is in a tube shape and is formed on the innermost peripheral surface of the hose body 20. The inner rubber layer 22 guides the flow of fresh concrete. The inner rubber layer 22 is formed of, for example, natural rubber (NR), styrene-butadiene rubber (SBR), ethylene-butadiene rubber (EPDM), or a blend composition of rubber selected from NR, cis-1,4-polybutadiene rubber (BR), SBR, and EPDM.

[0022] The pressure-resistant layer 23 has a first pressure-resistant layer 231 on the inner diameter side, a second pressure-resistant layer 233 on the outer diameter side, and a reinforcing wire 232 wound around the outer periphery of the first pressure-resistant layer 231 to reinforce the first pressure-resistant layer 231 and the second pressure-resistant layer 233. The pressure-resistant layer 23 can improve the pressure resistance of the hose body 20 against internal pressure by the first pressure-resistant layer 231 and the second pressure-resistant layer 233, and the reinforcing wire 232 can improve the buckling resistance of the hose body 20 against bending of the hose.

[0023] The first pressure-resistant layer 231 is composed of a pressure-resistant rubber sheet formed by topping a reinforcing cord 231a with topping rubber 231b. The first pressure-resistant layer 231 is reinforced by the reinforcing cord 231a, thereby improving the pressure resistance of the hose body 20. The second pressure-resistant layer 233 similarly includes a reinforcing cord 233a and topping rubber 233b. The first pressure-resistant layer 231 and the second pressure-resistant layer 233 are formed by winding them in a spiral shape, and it is preferable that 2 to 4 layers are laminated so that the orientations of the reinforcing cords 231a and 233a intersect. The first pressure-resistant layer 231 and the second pressure-resistant layer 233 are topped with rubber and then pressed down with a strip of fabric and vulcanized as described later, so that the pressure-resistant layer 23 is molded with rubber filling the gaps. Therefore, even when concrete scrapes away the inner rubber layer 22 and wear progresses, the pressure-resistant layer 23 can inhibit the penetration of the concrete. The topping rubbers 231b and 233b are made of the same material as the inner rubber layer 22.

[0024] Reinforcement cords 231a and 233a use wires made of natural or synthetic fibers. Examples include natural fibers such as cellulose fibers and protein fibers, and synthetic fibers such as nylon, polyester, acrylic, aramid, rayon, steel, and carbon.

[0025] The reinforcing wire 232 is a rigid wire that is spirally wound around the outer surface of the first pressure-resistant layer 231. The reinforcing wire 232 can be, for example, a metal wire or a carbon wire. By winding the reinforcing wire 232 around the hose body 20, the buckling resistance of the hose against bending and other forces can be improved.

[0026] The first outer rubber layer 24 is formed on the outer surface of the pressure-resistant layer 23. This configuration protects the pressure-resistant layer 23 from external impacts and reduces resistance when in contact with the floor during pouring and transportation. Here, the first outer rubber layer 24 and the pressure-resistant layer 23 (topping rubber 233b) are integrally molded. This configuration improves pressure resistance and reduces reaction forces when bending the hose body 20 during use. To improve the fusion strength due to integral molding, it is preferable that the first outer rubber layer 24 is made of the same type of rubber material as the pressure-resistant layer 23 (topping rubber 233b). Furthermore, it is even more preferable that the first outer rubber layer 24 and the pressure-resistant layer 23 (topping rubber 233b) are made of the same type of rubber material and have the same rubber hardness.

[0027] The first outer rubber layer 24 is formed by winding it around more than one turn. The thickness of the first outer rubber layer 24 is, for example, about 1.5 to 3.5 mm.

[0028] The second outer rubber layer 25 is formed on the outer surface of the first outer rubber layer 24 and on the outermost surface of the hose body 20. The second outer rubber layer 25 has a higher tensile strength at break than the first outer rubber layer 24. With this configuration, when wear progresses due to the pumping of ready-mix concrete and the pressure-resistant reinforcement layer ruptures (when the inner rubber layer 22 and pressure-resistant layer 23 rupture, but the first outer rubber layer 24 remains intact), the difference in tensile strength at break between the first outer rubber layer 24 and the second outer rubber layer 25 causes the first outer rubber layer 24 to rupture first, and the internal pressure of the incoming ready-mix concrete causes the second outer rubber layer 25 to expand. As a result, it is helpful for workers to detect the progress of wear due to the pumping of ready-mix concrete by observing the appearance of the ready-mix concrete pouring hose 9. Here, the formation of the first outer rubber layer 24 between the pressure-resistant layer 23 and the second outer rubber layer 25 allows the first outer rubber layer 24 to absorb the stress on the ready-mix concrete when the pressure-resistant layer 23 ruptures. This prevents the second outer rubber layer 25 from rupturing due to the force of the pressure-resistant layer 23 rupturing, and reduces the risk of the first outer rubber layer 24 rupturing due to the force of the pressure-resistant layer 23 rupturing, causing ready-mix concrete to scatter to workers, etc. Furthermore, because the second outer rubber layer 25 is the outermost surface, it is possible to increase the amount of expansion caused by the ready-mix concrete compared to the case where the rubber layer is laminated on the outer surface of the second outer rubber layer 25.

[0029] In this embodiment, the tensile elongation at break of the rubber material used in the second outer rubber layer 25 and the first outer rubber layer 24 is measured according to the method conforming to JIS K 6251:2023. Specifically, the elongation at break Eb is measured at a tensile speed of 500 mm / min using a dumbbell-shaped test piece No. 3 in an environment of 20°C. Here, the thickness of the second outer rubber layer 25 is greater than or equal to that of the first outer rubber layer 24. With this configuration, there is no need to consider the difference in tensile elongation at break due to changes in rubber thickness, and the effects of the present invention can be obtained. The thickness of the second outer rubber layer 25 is, for example, about 1.5 to 3.5 mm. Not limited to this embodiment, the thickness of the second outer rubber layer 25 may be made thinner than that of the first outer rubber layer 24, and adjusted so that the tensile elongation at break of the second outer rubber layer 25 is greater.

[0030] The second outer rubber layer 25 is laminated on a part or the entire circumference of the outer surface of the first outer rubber layer 24. Furthermore, it is preferable that the second outer rubber layer 25 be formed on the parts of the concrete pouring hose 9 that are subjected to severe wear due to the pumping of ready-mix concrete 30. For example, it is preferable that the second outer rubber layer 25 be laminated on the outer part (the part of the hose that stretches when bent) Be when the hose is used, or on the joint Co between the fitting and the hose body 20.

[0031] In this embodiment, it is preferable that the rubber hardness of the second outer rubber layer 25 is lower than that of the first outer rubber layer 24. With this configuration, when the pressure-resistant layer 23 ruptures due to abrasion caused by the pumping of ready-mix concrete, and stress is applied to the first outer rubber layer 24 and the second outer rubber layer 25 due to internal pressure, the stress on the second outer rubber layer 25 can be made smaller than the internal pressure applied to the first outer rubber layer 24 due to the difference in stress relative to the strain rate of the first outer rubber layer 24 and the second outer rubber layer 25. The rubber hardness is measured, for example, in accordance with JIS K 6253:2012 using a Type A durometer. The rubber hardness can be adjusted as appropriate by changing the type of rubber material or the amount of filler added.

[0032] In this embodiment, the first outer rubber layer 24 and the second outer rubber layer 25 are made of the same type of rubber material. This configuration improves the fusion strength when integrally molded. As a result, even when the hose body 20 is bent for a long time or bent to an extreme degree, the outer rubber layers remain fused together, which is advantageous in terms of suppressing wrinkle formation and suppressing an increase in bending reaction force.

[0033] Next, the progression of wear on the hose body 20 due to the pumping of ready-mix concrete 30 in the ready-mix concrete pouring hose 9 will be explained with reference to Figure 3.

[0034] As shown in Figure 3(A), the concrete pouring hose 9 is a hose in which an inner rubber layer 22, a pressure-resistant layer 23, a first outer rubber layer 24, and a second outer rubber layer 25 are sequentially laminated from the inner diameter to the outer diameter, and ready-mix concrete 30 is pumped under pressure from the inner diameter to the inner diameter of the inner rubber layer 22. Here, the ready-mix concrete 30 is composed of aggregate 32 and cement paste 31. The aggregate 32 is mixed into the cement paste 31. The viscosity of the ready-mix concrete 30 is not particularly limited, and it may also be mortar.

[0035] Here, the aggregate 32 is composed of materials selected from sand (fine aggregate) and gravel (coarse aggregate), etc. The cement paste 31 is a fluid mixture of water and cement. The particle shape and type of the aggregate 32, the ratio of water to cement in the cement paste 31, etc. are selected as appropriate depending on the construction site.

[0036] As shown in Figures 3(A) and 3(B), the ready-mix concrete 30 flows in one direction through the concrete pouring hose 9. As shown in Figure 3(B), over time, the inner rubber layer 22 of the concrete pouring hose 9 is worn away from the inside by the aggregate 32 contained in the ready-mix concrete 30, and the wear progresses down to the pressure-resistant layer 23. An abrasion zone 27 is formed. If use continues, as shown in Figure 3(C), a portion of the reinforcing cord 231a in the pressure-resistant layer 23 breaks due to wear, and this becomes the starting point for a rupture in the pressure-resistant layer 23.

[0037] Here, the first outer rubber layer 24 and the pressure-resistant layer 23 are formed by integral molding, the first outer rubber layer 24 is the fusion bonding surface with the pressure-resistant layer, and due to the difference in tensile fracture elongation between the first outer rubber layer 24 and the second outer rubber layer 25, the first outer rubber layer 24 does not exhibit its original rubber stretching performance and ruptures before the second outer rubber layer 25 without bulging outward in diameter. Here, if the pressure-resistant layer 23 and the first outer rubber layer 24 are made of the same type of rubber material, the fusion strength between the pressure-resistant layer 23 and the first outer rubber layer 24 will improve, and the elongation rate at rupture will be smaller. Subsequently, as the ready-mix concrete 30 flows into the inside of the second outer rubber layer 25, stress due to internal pressure is applied to the second outer rubber layer 25, and a bulge 28 is formed outward in diameter. If the crack 29 in the pressure-resistant layer 23 extends in the axial or circumferential direction, the bulge 28 will increase.

[0038] Next, an example of the manufacturing method according to this embodiment will be described with reference to Figure 2. First, a tube-shaped inner rubber 221 for the inner rubber layer 22 is manufactured by extrusion molding.

[0039] Next, the fabricated inner rubber 221 and the fitting are inserted into the mandrel, and the ends of the mandrel and the inner rubber 221 are brought into contact. The inner rubber 221 and the ends of the fitting are secured by wrapping them with a rubber sheet 222. Preferably, the rubber sheet 222 is made of the same type of rubber material as the inner rubber 221. In addition, rubber adhesive is applied to the outer surface of the fitting and the contact points with the inner rubber 221. The rubber sheet 222 and the inner rubber 221 form the inner rubber layer 22.

[0040] Next, the pressure-resistant rubber sheet 231c is wound spirally around the inner rubber layer 22 and the outer surface of the fitting 2 to 4 times. At this time, it is preferable to overlap a portion of the pressure-resistant rubber sheet 231c while winding. This configuration can improve the strength of the concrete pouring hose 9.

[0041] Next, the reinforcing wire 232 is spirally wrapped around the outer surface of the first pressure-resistant layer 231, and the same process is followed for the second pressure-resistant layer 233, wrapping it around the outer surface of the first pressure-resistant layer 231 and the reinforcing wire 232. After that, the end member is wrapped around the outer surface of the pressure-resistant layer 23 laminated on the outer surface of the fitting at least once and fixed in place, and the pressure-resistant layer 23 that protrudes from the end member towards the mouth side is folded back towards the tip side Y. The end member can be made from scraps of pressure-resistant rubber sheet 231c or metal wire.

[0042] Next, an outer rubber sheet for the first outer rubber layer 24 is wrapped around the outer surface of the pressure-resistant layer 23 to form the first outer rubber layer 24. Then, a rubber sheet for the second outer rubber layer 25 is laminated onto part or all of the outer surface of the first outer rubber layer 24 to form the second outer rubber layer 25.

[0043] Finally, the concrete pouring hose 9 is completed by wrapping a strip of cloth around the outer surfaces of the second outer rubber layer 25 and the first outer rubber layer 24 and vulcanizing them. By wrapping the strip of cloth and vulcanizing it, it is possible to suppress the expansion of the hose body 20. The vulcanization method is an indirect vulcanization method in which vulcanization is carried out by the heat of the coil in the vulcanization device and the generation of steam inside the mandrel, but an external bag method may also be used in which vulcanization is carried out by pressing an expanded rubber bag, which is inflated by applying internal pressure from the outside of the concrete pouring hose 9, without wrapping the strip of cloth.

[0044] (Second Embodiment) Next, the concrete pouring hose 9 according to the second embodiment will be described. Note that the following explanation will omit details common to the concrete pouring hose 9 in the second embodiment and the concrete pouring hose 9 in the first embodiment.

[0045] In this embodiment, the second outer rubber layer 25 of the concrete pouring hose 9 uses a different type of rubber material than the first outer rubber layer 24. Compared to the case where the same type of rubber material is used, the fusion force between the first outer rubber layer 24 and the second outer rubber layer 25 after vulcanization is weaker. With this configuration, when the first outer rubber layer 24 ruptures due to wear caused by the pumping of concrete 30 (the inner rubber layer 22, pressure-resistant layer 23, and first outer rubber layer 24 rupture) and internal pressure is applied to the second outer rubber layer 25, the second outer rubber layer 25 expands outward in diameter, and the adhesive surface between the first outer rubber layer 24 and the second outer rubber layer 25 peels off, causing the concrete 30 to spread in the circumferential direction S. This delays the rupture of the second outer rubber layer 25 and expands the range of the bulge 28 of the second outer rubber layer 25. As a result, it is helpful for the worker to detect the progress of wear caused by the pumping of concrete 30 by the appearance of the concrete pouring hose 9.

[0046] The ends of the second outer rubber layer 25 are preferably bonded with an adhesive. This configuration prevents leakage of ready-mix concrete 30 to the outside. The adhesive is appropriately selected depending on the type of rubber.

[0047] Next, the progression of wear of the hose body 20 due to the pumping of ready-mix concrete 30 in the ready-mix concrete pouring hose 9 of the second embodiment will be explained with reference to Figure 4.

[0048] Similar to Figures 3(A) and 3(B), the ready-mix concrete 30 flows in one direction through the concrete pouring hose 9. Over time, the inner rubber layer 22 wears down, and the wear progresses to the pressure-resistant layer 23. If use continues, as shown in Figure 4(C), a portion of the reinforcing cord 231a in the pressure-resistant layer 23 breaks due to wear, and this becomes the starting point for a rupture in the pressure-resistant layer 23.

[0049] Here, the first outer rubber layer 24 is formed integrally with the pressure-resistant layer 23, the first outer rubber layer 24 is the fusion bonding surface with the pressure-resistant layer, and the tensile elongation at break of the first outer rubber layer 24 and the second outer rubber layer 25 are different. As a result, the first outer rubber layer 24 does not exhibit its original rubber elongation performance and breaks before the second outer rubber layer 25 without expanding outward in diameter. Subsequently, the second outer rubber layer 25 is subjected to outward stress due to the inflow of ready-mix concrete 30, causing the second outer rubber layer 25 to stretch outward in diameter. Since the first outer rubber layer 24 and the second outer rubber layer 25 use different types of rubber materials, the fusion strength is lower compared to when they are made of the same type of rubber material. As a result, a load is placed on the adhesive interface between the first outer rubber layer 24 and the second outer rubber layer 25, causing the adhesion to gradually break. This triggers the ready-mix concrete 30 to flow in the circumferential direction S, widening the adhesive interface. The inflow of ready-mix concrete 30 into the adhesive interface reduces the internal pressure on the radially outward side of the second outer rubber layer 25, thereby reducing the stress per unit area and preventing rupture due to localized load. Furthermore, the circumferential spread of the ready-mix concrete 30 in the circumferential direction S expands the area of ​​the radially outward bulge 28 of the second outer rubber layer 25.

[0050] Although each embodiment has been described above, the present invention is not limited to the embodiments described above, and can be modified as appropriate within the scope of the spirit of the present invention. Furthermore, the invention of the concrete pouring hose 9 in the embodiment may also be applied to the docking hose 7. [Explanation of symbols]

[0051] 9. Concrete pouring hose (end hose) 22 Inner rubber layer 23 Pressure-resistant layer 231a Reinforcement Code 233a Reinforcement Code 24 First outer rubber layer 25 First outer rubber layer 30 Ready-mix concrete

Claims

1. A tube-shaped inner rubber layer that guides the pumping of ready-mix concrete, The inner rubber layer has a pressure-resistant layer formed on its outer surface, which inhibits the penetration of fresh concrete and is reinforced with reinforcing cords, The pressure-resistant layer comprises a first pressure-resistant layer, a reinforcing wire wrapped around the outer surface of the first pressure-resistant layer, and a second pressure-resistant layer formed on the outer surface of the reinforcing wire. A first outer rubber layer formed on the outer surface of the pressure-resistant layer and integrally molded with the topping rubber of the second pressure-resistant layer of the pressure-resistant layer, The first outer rubber layer has a second outer rubber layer formed on the outermost outer surface of the first outer rubber layer, which has a higher tensile strength at break than the first outer rubber layer. Concrete pouring hose.

2. The second outer rubber layer has a lower rubber hardness than the first outer rubber layer. The concrete pouring hose according to claim 1.

3. The first outer rubber layer is made of the same type of rubber material as the topping rubber. A hose for pouring ready-mix concrete according to claim 1 or 2.

4. The first outer rubber layer and the second outer rubber layer are made of the same type of rubber material. A hose for pouring ready-mix concrete according to claim 1 or 2.

5. The first outer rubber layer and the second outer rubber layer are made of different types of rubber materials. A hose for pouring ready-mix concrete according to claim 1 or 2.

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