Tube for pinch valve and method of manufacturing same

Abstract

This tube for a pinch valve has a uniform wall thickness, does not cause a concentration of load at a specific point during use, and, even when the tube is used for a pinch valve device, the tube is highly durable and is highly functional as a valve. The tube for a pinch valve is a long object having a given shape in the longitudinal direction, and comprises a flow path 12 passing through the inside in the longitudinal direction, and a resin part 13 surrounding the periphery of the flow path 12. The resin part 13 is a laminate constituted by alternately stacking porous resin layers 16, which are arranged in the radial direction of the flow path 12, and an elastomer layer 18 for bonding the porous resin layers 16. The elastomer layer 18 is composed of at least one kind of elastomer, the porous resin layers 16 each have voids, and the voids are impregnated with some of the elastomer. A tube 10 has elasticity such that, when an opening and closing mechanism of a pinch valve device 1 is operated while applying an air pressure of 100 kPa to the IN side, the response time required from the time when the pressure on the tube 10 is released until the flow path 12 of the tube is opened and a pressure gauge on the OUT side detects the pressure is 20 ms or less.

Description

Pinch valve tube and its manufacturing method

[0001] The present invention relates to a pinch valve tube that is applied to a pinch valve device that functions as an opening / closing valve for a pipe through which a liquid or the like flows, and to a method for manufacturing the same.

[0002] Pinch valves, tube pumps, and the like are known that use holes that penetrate both ends of a soft tube made of rubber, resin, or the like as a fluid flow path. In these pinch valves and tube pumps, the fluid does not come into contact with any part of the tube other than the inner surface of the holes. Therefore, for example, by replacing the tube after use, the fluid flow path can be kept clean at all times, which is effective in preventing cross-contamination of fluids.

[0003] Furthermore, the pinch valves and tube pumps can be used effectively even when the fluid is, for example, a slurry containing solid particles, without causing clogging or malfunctions, etc. For this reason, pinch valves and tube pumps are widely used in various fields, such as chemistry, semiconductors, food, and biology.

[0004] In a pinch valve, the flow of fluid through the hole is controlled by selecting a state in which a portion of the tube is compressed and closed by radially compressing a portion of the tube, and a state in which the tube returns to its original state by its own elasticity and resilience when the pressure is released, thereby opening and closing the hole. Therefore, in order to improve the responsiveness of a pinch valve, it is important that the tube for a pinch valve be able to recover to its original state and open the hole as quickly as possible after the pressure is released.

[0005] In a tube pump, a portion of the tube is radially pressed in one direction along its length to compress the through-hole, and the compressed region is then moved in one direction along the length of the tube, thereby pumping the fluid in the through-hole in the same direction. Therefore, in order to improve the fluid transport performance of the tube pump, it is important that the tube for a tube pump recovers to its original state as quickly as possible using its own elasticity and restoring ability after the compressed region has passed and the compression is released, thereby ensuring a volume in the through-hole that can accommodate a sufficient amount of fluid.

[0006] Examples of tubing used in tube pumps and pinch valves include flexible fluororubber and silicone rubber tubing. Pinch valve devices mechanically compress or pinch highly elastic tubing, such as silicone rubber, from the outside to close the flow path inside the tubing, thereby closing the flow path. Such valves are used, for example, by attaching them to piping in plants that produce food, dairy beverages, pharmaceuticals, cosmetics, and the like.

[0007] A typical pinch valve device is installed in a line that includes piping for the flow of liquids or powders, and therefore, it must meet certain requirements, such as not causing clogging inside the pinch valve device, being easy to clean inside the device, and being easy to disassemble and assemble.

[0008] A known example of a pinch valve device that excels in these respects is disclosed in Patent Document 1, which includes a disk-shaped valve housing, a rotor rotatably disposed within the valve housing, a tube made of an elastic material disposed inside the rotor, a pair of pinch levers swingably disposed outside the center of the tube, and a pinch lever that serves as clamping means that drives the pair of pinch levers in a direction that clamps the tube.

[0009] Patent No. 5363692

[0010] In the pinch valve device disclosed in Patent Document 1, once the tube is attached to the valve housing, the attachment position of the tube is fixed, so the same part of the tube is always pinched by the pair of pinch levers. When the valve is repeatedly opened and closed over a long period of time in this usage state, only the part of the tube surface that is in contact with the pinch levers is subjected to load, causing deterioration or wear, and ultimately leading to breakage, which is an issue of durability. Also, as the tube deteriorates or wears, the return force decreases, which deteriorates the function of the pinch valve (consistently flowing a constant amount and quickly fully opening the valve).

[0011] Furthermore, when a high-pressure fluid or the like flows through the tube, the tube is made of the softest material among the components of the pinch valve device, so when the pressure of the fluid or the like acts on the tube, the tube expands, deforms, and may even break.Furthermore, if a negative pressure or vacuum is created inside the tube and the tube itself shrinks inward, this can cause problems in use.

[0012] Therefore, if the above-mentioned problems occur in the tube, the tube must be replaced, and if the frequency of tube replacement increases, the cost of the tube as a consumable item increases.

[0013] The present invention has been made in consideration of the problems in the background art described above, and aims to provide a pinch valve tube that has a uniform wall thickness, is resistant to deterioration even when a load is concentrated at a specific point during use, is highly durable when used in a pinch valve device, and has high valve functionality (always allowing a constant flow rate and quickly fully opening the valve), as well as a method for manufacturing the same.

[0014] The present invention provides a tube (1) that is an elongated object having a fixed shape in the longitudinal direction, and that includes a flow path penetrating the inside in the longitudinal direction, and a resin part surrounding the flow path, the resin part being configured as a laminate in which porous resin layers that are laminated in the radial direction of the flow path and elastomer layers that bond between the porous resin layers are alternately laminated, the elastomer layers being made of at least one type of elastomer, the porous resin layers having voids, and the voids being impregnated with a part of the elastomer, The tube is attached to a pinch valve of a solenoid-driven opening and closing mechanism, and one end of the tube is connected as the IN side to an air supply unit, and the other end is connected as the OUT side to a pressure gauge.The opening and closing mechanism is operated to press the tube radially and close the flow path that passes through both ends of the tube, and then an air pressure of 100 kPa is applied to the IN side of the tube while the opening and closing mechanism is operated to release the pressure on the tube, and the response time is the time required from the point at which the flow path of the tube opens and the pressure gauge on the OUT side detects the air pressure, and the tube for the pinch valve has elasticity such that the response time is 20 ms or less.

[0015] (2) In one cross section at any position in the longitudinal direction of the tube, the average value of the wall thickness of the resin portion in at least four directions perpendicular to each other in the radial direction of the flow path is calculated, and the wall thickness ratio, which is the average value of the ratio of the wall thicknesses facing each other among the four directions, and the number of laminations of the porous layer and the elastomer layer, are calculated. When the average value of the wall thickness is 0.5 mm or more and less than 2.8 mm, the wall thickness ratio is 1.0 to 1.2, and when the average value of the wall thickness is 2.8 mm or more and less than 10.3 mm, the wall thickness ratio is 1.0 to 1.1. Furthermore, with regard to the number of layers, when the average wall thickness is 0.5 mm or more and less than 1.4 mm, the number of layers is 5 or more and less than 35; when the average wall thickness is 1.4 mm or more and less than 2.0 mm, the number of layers is 14 or more and less than 50; when the average wall thickness is 2.0 mm or more and less than 2.8 mm, the number of layers is 20 or more and less than 70; when the average wall thickness is 2.8 mm or more and less than 4.0 mm, the number of layers is 28 or more and less than 100; when the average wall thickness is 4.0 mm or more and less than 6.2 mm, the number of layers is 40 or more and less than 155; when the average wall thickness is 6.2 mm or more and less than 7.7 mm, the number of layers is 62 or more and less than 193; and when the average wall thickness is 7.7 mm or more and less than 10.3 mm, the number of layers is 77 or more and less than 258.

[0016] (3) The pinch valve tube according to (1) or (2), wherein the porous resin layer has a porosity of 70% or more. (4) The porosity of the porous resin layer is preferably 70% to 85%. (5) The pinch valve tube according to (1), (2), or (4), wherein the inner surface of the liquid-contacting side of the pinch valve tube is smooth, and the surface satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 3.00 (μm). (6) The pinch valve tube according to (1), (2), or (4), wherein the hardness of the inner surface (liquid-contacting side) of the pinch valve tube of the present invention is a Shore A hardness of 40 to 70. (7) The pinch valve tube of the present invention has a smooth inner peripheral surface (liquid-contacting side) that satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 3.00 (μm). (8) The pinch valve tube of the present invention has a smooth inner peripheral surface (liquid-contacting side) that satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 3.00 (μm). (9) The pinch valve tube of the present invention has a smooth inner peripheral surface (liquid-contacting side) that satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 3.00 (μm). (10) The pinch valve tube of the present invention has a smooth inner peripheral surface (liquid-contacting side) that satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 3.00 (μm). (11) The pinch valve tube of the present invention has a smooth inner peripheral surface (liquid-contacting side) that satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 3.00 (μm). (12) The pinch valve tube of the present invention has a smooth inner peripheral surface (liquid-contacting side) that satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean

[0017] (9) The present invention is a method for producing a tube comprising the steps of: drawing out a polytetrafluoroethylene film from an original roll of polytetrafluoroethylene film; applying a liquid elastomer to the polytetrafluoroethylene film to impregnate it; winding up the polytetrafluoroethylene film coated with and impregnated with the liquid elastomer in multiple layers on a winding shaft; and heat-treating the polytetrafluoroethylene film to promote a crosslinking reaction of the liquid elastomer and bond the layers of the polytetrafluoroethylene film together; and forming a laminate in which polytetrafluoroethylene layers made of the polytetrafluoroethylene film and elastomer layers made of the liquid elastomer are alternately laminated; the tube is attached to a pinch valve device of a solenoid-driven opening and closing mechanism; The liquid elastomer application step involves supplying the liquid elastomer onto the upper surface of the polytetrafluoroethylene film, pressing a first blade vertically from above the polytetrafluoroethylene film surface to bring it into contact with the upper surface of the polytetrafluoroethylene film, scraping off excess liquid elastomer to achieve a uniform thickness, and then contacting the upper surface of the polytetrafluoroethylene film from above with a second blade that is pressed against the upper surface of the polytetrafluoroethylene film and is inclined so that its lower end that contacts the polytetrafluoroethylene film faces downstream to again scrape off excess liquid elastomer to achieve a uniform thickness. The liquid elastomer is applied to a uniform thickness by the first blade and the second blade, and at the same time, the polytetrafluoroethylene film is impregnated with the liquid elastomer, thereby forming the tube, which is an elongated object of a uniform shape in the longitudinal direction, has a flow path penetrating therethrough in the longitudinal direction, and has a resin portion surrounding the periphery of the flow path. the resin portion is formed by alternately winding a plurality of the polytetrafluoroethylene layers stacked in a radial direction of the flow path and the elastomer layers bonding the polytetrafluoroethylene layers together, the elastomer layers being made of at least one type of elastomer, the polytetrafluoroethylene layers having voids, the voids being impregnated with a portion of the elastomer,In one cross section at an arbitrary position in the longitudinal direction of the tube, an average value of wall thicknesses of the resin portion in four mutually orthogonal directions in the radial direction of the flow path is calculated, and a wall thickness ratio, which is the average value of the ratios of the wall thicknesses in opposing directions among the four directions, is calculated. With respect to the number of laminations of the polytetrafluoroethylene layers and the elastomer layers, when the average wall thickness is 0.5 mm or more and less than 2.8 mm, the wall thickness ratio is 1.0 to 1.2, and when the average wall thickness is 2.8 mm or more and less than 10.3 mm, the wall thickness ratio is 1.0 to 1.1; Furthermore, in this method for manufacturing a tube for a pinch valve, the number of layers is 5 or more and less than 35 when the average wall thickness is 0.5 mm or more and less than 1.4 mm; 14 or more and less than 50 when the average wall thickness is 1.4 mm or more and less than 2.0 mm; 20 or more and less than 70 when the average wall thickness is 2.0 mm or more and less than 2.8 mm; 28 or more and less than 100 when the average wall thickness is 2.8 mm or more and less than 4.0 mm; 40 or more and less than 155 when the average wall thickness is 4.0 mm or more and less than 6.2 mm; 62 or more and less than 193 when the average wall thickness is 6.2 mm or more and less than 7.7 mm; and 77 or more and less than 258 when the average wall thickness is 7.7 mm or more and less than 10.3 mm.

[0018] By using the tube of the present invention in a pinch valve device, it is possible to suppress breakage due to increased internal pressure and damage due to negative pressure within the tube, and to improve durability against repeated pinching operations, thereby reducing the burden of maintenance on the tube of the pinch valve device, the pinch valve device, and the fluid supply system equipped with them.

[0019] In addition, the tube of the present invention has a consistent wall thickness, no variation in deformation depending on the location, and high durability without concentrating loads on specific areas during use. Furthermore, because the inner surface is smooth and has low surface roughness, when the tube is crushed to close the internal space, friction is reduced when the inner wall of the tube adheres tightly, preventing minute separation of the innermost surface. This makes it possible to prevent foreign matter from being mixed into the discharged fluid. Furthermore, the valve opening responsiveness is high.

[0020] Furthermore, according to the method for manufacturing a tube for a pinch valve of the present invention, a tube having the above-mentioned effects can be provided easily, efficiently and at low cost.

[0021] 1 is a perspective view showing the appearance of a typical pinch valve device to which the tube of the present invention is attached. 2 is an exploded perspective view showing the internal structure of the valve body of the pinch valve device shown in FIG. 1. 3 is a cross-sectional view of a pinch valve tube according to one embodiment of the present invention. 4 is a schematic diagram of a manufacturing process for a pinch valve tube according to this embodiment. 5 (a) is a cross-sectional view illustrating an outline of an apparatus used to measure the reaction force by applying a load to a pinch valve tube in an example of the adhesiveness evaluation method of the present invention. 6 (b) to (f) are cross-sectional views illustrating a process of measuring the change in the reaction force of the pinch valve tube by applying a constant load in the radial direction to press the pinch valve tube to a closed state using the above apparatus, and then releasing the load at a constant speed. 7 is a graph schematically illustrating an example of the change in the reaction force over time measured through the process of FIGS. 5 (b) to (f).

[0022] The pinch valve tube of the present invention is described in detail below. The pinch valve tube of the present invention is a long, elongated tube having a uniform shape in the longitudinal direction, and includes a flow path that is a through-hole penetrating the inside in the longitudinal direction, and a resin portion surrounding the flow path, the resin portion being a laminate formed by alternately laminating porous resin layers having a porosity of 70% or more that are stacked in the radial direction of the flow path and elastomer layers that bond between the porous resin layers, and the tube is for use in a pinch valve device, and the average value of the wall thickness of the resin portion in at least four directions perpendicular to each other in the radial direction of the flow path is calculated, and the wall thickness ratio calculated from the wall thicknesses of opposing sides of the four directions and the number of laminations of the porous resin layers having a porosity of 70% to 85% and the elastomer layers satisfy the following conditions:

[0023] When the average value of the thickness in four directions of the resin part is 0.5 mm or more and less than 2.8 mm, the thickness ratio is 1.0 to 1.2, and when the average value of the thickness is 2.8 mm or more and less than 10.3 mm, the thickness ratio is 1.0 to 1.1.

[0024] Furthermore, with regard to the number of layers, when the average thickness is 0.5 mm or more and less than 1.4 mm, the number of layers is 5 or more and less than 35; when the average thickness is 1.4 mm or more and less than 2.0 mm, the number of layers is 14 or more and less than 50; when the average thickness is 2.0 mm or more and less than 2.8 mm, the number of layers is 20 or more and less than 70; when the average thickness is 2.8 mm or more and less than 4.0 mm, the number of layers is 28 or more and less than 100; when the average thickness is 4.0 mm or more and less than 6.2 mm, the number of layers is 40 or more and less than 155; when the average thickness is 6.2 mm or more and less than 7.7 mm, the number of layers is 62 or more and less than 193; and when the average thickness is 7.7 mm or more and less than 10.3 mm, the number of layers is 77 or more and less than 258.

[0025] Within the range of the average thickness of each tube, if the number of layers is excessively increased beyond the specified range, the adhesive strength between the elastomer layers will be insufficient, causing the porous resin layer and the elastomer layer to easily peel off, resulting in a loss of durability. Also, if a tube is manufactured with a small number of layers that does not fall within the specified range, the elastomer layer will be too thick, causing thickness variations, and the tube will not satisfy the wall thickness ratio requirement.

[0026] The porous resin of the porous resin layer may be, for example, a thermoplastic resin film uniaxially or biaxially stretched, but is not limited to this example and may be any resin film that can be made porous by stretching.

[0027] The thermoplastic resin is polytetrafluoroethylene, a polyolefin such as polyethylene or polypropylene, a polyester such as polyethylene terephthalate or polybutylene terephthalate, a polysulfide such as polyphenyl sulfide or polyethylene sulfide, a polyamide, a polyimide, a polyvinyl alcohol, or a combination thereof.

[0028] The elastomer is silicone, urethane, nitrile rubber, styrene-butadiene rubber, chloroprene, phosphazene, fluoroelastomer, perfluoroelastomer, perfluoropolyether elastomer, methylsilicone, phenylsilicone, fluorosilicone, or a combination thereof. If the elastomer is not liquid at room temperature, it is dissolved in a solvent to be liquefied before use.

[0029] Particularly preferred elastomers are silicones, methylsilicones, phenylsilicones, fluoroelastomers, perfluoroelastomers, or combinations thereof.

[0030] The pinch valve tube of the present invention is a laminate in which porous resin layers having a porosity of 70% or more and elastomer layers bonding the porous resin layers are alternately laminated. The inner surface (liquid-contacting side) of the pinch valve tube of the present invention preferably has a Shore A hardness of 40 to 70.

[0031] Furthermore, in the present invention, in order to optimize the tube for use in a pinch valve mechanism as described below, the pinch valve tube of the present invention was attached to a pinch valve of a solenoid-driven opening and closing mechanism and the following measurements were carried out.

[0032] One end of the tube was connected to an air supply as the IN side, and the other end was connected to a pressure gauge as the OUT side. The opening and closing mechanism was operated to press the tube radially, closing the through-holes that were the flow paths that passed through both ends of the tube. Then, while applying an air pressure of 100 kPa to the IN side of the tube, the opening and closing mechanism was operated to release the pressure on the tube. The response time was measured as the time required from the point at which the tube's through-hole actually opened and the OUT-side pressure gauge detected the air pressure of 100 kPa. Here, the response time was defined as the time it took for the valve of the tube in the pinch valve mechanism to open and for the OUT side to obtain the same flow rate and pressure as the IN side of the tube.

[0033] As a result, the thickness of the porous resin layer to provide the elasticity required for a response time of 20 ms or less must be 20 to 150 μm, with a porosity of 70% or more; more preferably, the thickness of the porous resin layer must be 20 to 100 μm, with a porosity of 70 to 85%. If the porous resin layer is too thin, the tube after impregnating and curing the elastomer will be too soft; if it is too thick, it will be too hard, requiring a greater load for opening and closing operations, which will result in increased load on the tube and reduced durability, which is undesirable. Furthermore, if the porosity is low, the tube after impregnating and curing the elastomer will be too hard, making it difficult to yield as a pinch valve and unsuitable for practical use.

[0034] In particular, optimizing the degree of curing of the elastomer makes it possible to produce a tube that is even more suitable for a pinch valve mechanism. The degree of curing is such that the inner surface (liquid-contacting side) of the pinch valve tube of the present invention has a Shore A hardness of 40 to 70, and the inner peripheral surface of the inner surface (liquid-contacting side) of the pinch valve tube of the present invention is smooth, with the inner peripheral surface satisfying at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a 10-point mean roughness Rz of 0.01 to 3.00 (μm). By achieving these ranges, the inner surface is free of adhesion, and the full-opening speed as a pinch valve is good.

[0035] Next, an embodiment of the present invention will be described with reference to the drawings. As shown in Figures 1 and 2, a pinch valve tube 10 of the present invention is applied to a pinch valve device 1, and the pinch valve device 1 will be described in the examples below.

[0036] First, a pinch valve tube 10 (hereinafter simply referred to as the tube 10) according to one embodiment of the present invention will be described with reference to Figure 3. The tube 10 of this embodiment is an elongated object having a fixed shape in the longitudinal direction, and includes a flow path 12 with a circular cross section that penetrates the inside in the longitudinal direction, and a cylindrical resin portion 13 that surrounds the periphery of the flow path 12. Figure 3 shows the structure of a cross section of the tube 10 taken approximately perpendicular to the longitudinal direction.

[0037] The resin part 13 is configured as a laminate in which porous resin layers 16, which are stacked in the radial direction of the flow path 12, and elastomer layers 18, which bond between the porous resin layers 16, are alternately stacked. The porous resin layers 16 are wound around the flow path 12 multiple times to form a cylindrical body. The porous resin layers 16 have voids, and the voids are impregnated with parts of the elastomer layers 18.

[0038] Here, the porous resin layer 16 will be described. The porous resin layer 16 is made of a uniaxially or biaxially stretched porous resin film 17 made of a thermoplastic resin. The stretched porous resin film 17 has a thickness of 30 to 300 μm and a porosity of 70% to 85%.

[0039] Next, the elastomer layer 18 will be described. The elastomer layer 18 is composed of at least one type of elastomer, such as silicone that is liquid at the time of application and has a hardness of 60 on the durometer A scale, a viscosity of 25 Pa·S, a tensile strength of 7.3 MPa, and an elongation of 180%. In addition to silicone, a fluorine-based elastomer may also be used. Fluorine-based elastomers have excellent chemical resistance and sufficient flex resistance even in the presence of aggressive chemicals (acids, alkalis, and solvents such as toluene and MEK). If the viscosity is too high and the elastomer does not penetrate the voids of the porous resin layer 16 during application, the elastomer is diluted with a solvent before use.

[0040] The inner peripheral surface of the flow channel 12 is formed to be smooth. The smoothness of the inner peripheral surface of the flow channel 12 satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 3.00 (μm).

[0041] In the tube 10, the wall thickness t and wall thickness ratio of the resin portion 13, and the number I of layers of the porous resin layer 16 and the elastomer layer 18 satisfy the conditions shown in Table 1 below. By satisfying these conditions, durability is improved. The wall thickness t of the resin portion 13 is the average value of the wall thicknesses ta, tb, tc, and td of the resin portion 13 in at least four mutually orthogonal directions A, B, C, and D from the center 0 shown in FIG. 3 in a cross section of the tube 10 in a plane approximately perpendicular to the longitudinal direction, i.e., four mutually orthogonal directions A, B, C, and D in the radial direction of the flow path 12. The wall thickness ratio is the average value of the ratio between opposing wall thicknesses in the four directions. The tube 10 of this embodiment is manufactured by setting the optimal wall thickness ratio between opposing wall thicknesses in the four directions and the number I of layers to satisfy the optimal conditions for obtaining high durability, corresponding to the value of the wall thickness t. The optimum conditions for the thickness t, thickness ratio, and number of layers I are shown in Table 1 below.

[0042] Here, for the thickness t, thickness ratio, and number of layers I, for each value of the thickness ratio in Table 1, values ​​are rounded to two decimal places, taking into account the allowable error. As a result, the suitable thickness, thickness ratio, and number of layers I for high durability are as follows: When the average value of the thickness t is 0.5 mm or more and less than 2.8 mm, the thickness ratio is 1.0 to 1.2, and when the average value of the thickness t is 2.8 mm or more and less than 10.3 mm, the thickness ratio is 1.0 to 1.1. The number of layers is as shown in Table 1.

[0043] Next, a method for manufacturing the pinch valve tube 10 of this embodiment will be described with reference to Figure 4. This manufacturing method produces a tube 10 in which the wall thickness t, wall thickness ratio, and number of layers I fall within the optimum ranges for high durability, as shown in Table 1 above.

[0044] First, the porous resin film 17 that will become the porous resin layer 16 is pulled out from an original roll 20 of the porous resin film 17 while being guided by a plurality of film support rollers 22, and sent to a coating step 24 in which a liquid elastomer 19 that will form the elastomer layer 18 is applied. In the coating step 24, the porous resin film 17 that has been impregnated with and thinly coated with the liquid elastomer 19 is taken up around a take-up shaft 26.

[0045] The winding shaft 26 has a circular cross-sectional shape corresponding to the shape of the flow path 12. The winding shaft 26 is coated with a fluororesin to facilitate peeling. Furthermore, since the surface condition of the shaft 26 is transferred to the inner surface of the tube, a tube with a smooth inner surface can be obtained by finishing the surface of the shaft 26 as smooth as possible or by covering it with a heat-shrinkable tube made of fluororesin. A preferred range for the surface roughness of the inner surface of the flow path 12 of the tube 10 is one that satisfies at least one of the following conditions: an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 0.3 (μm).

[0046] The film wound around the winding shaft 26 is then heated to promote the crosslinking reaction of the liquid elastomer 19, bonding the layers of the porous resin film 17 together, and forming a laminate in which the porous resin layers 16 and the elastomer layers 18 are alternately stacked. The heat treatment is performed, for example, by heating in an oven. Thereafter, the winding shaft 26 is pulled out, the flow path 12 is formed, and the tube 10 is completed.

[0047] 4, the coating process 24 for coating the liquid elastomer 19 is carried out in the vicinity of the film support roller 22a immediately before the winding shaft 26. First, the apparatus for the coating process 24 will be described.

[0048] A first blade 28 is provided upstream of the film support roller 22a, between the film support roller 22b and the next film support roller 22b located upstream, for scraping off the liquid elastomer 19 to achieve a uniform thickness. The first blade 28 is pressed against the upper surface of the porous resin film 17 almost vertically from above the surface of the porous resin film 17. The lower end 28a of the first blade 28 pressed against the upper surface of the porous resin film 17 is located lower than the film support roller 22a and presses the porous resin film 17 downward below the film support roller 22a. The film support roller 22b located upstream of the film support roller 22a is located lower than the film support roller 22a and at approximately the same height as the lower end 28a of the first blade 28. The porous resin film 17 is fed almost horizontally between the film support roller 22b and the first blade 28.

[0049] A liquid elastomer supplying device (not shown) is provided between the first blade 28 and the film support roller 22 b , and applies liquid elastomer 19 to the upper surface of the porous resin film 17 .

[0050] A second blade 30 is provided downstream of the film support roller 22a and between it and the winding shaft 26 to further scrape off the liquid elastomer 19 to achieve a more uniform thickness. The second blade 30 is pressed against the upper surface of the porous resin film 17 from above the surface of the porous resin film 17. The second blade 30 is inclined so that its lower end 30a, which contacts the porous resin film 17, faces downstream. The lower end 30a of the second blade 30 is located slightly lower than the upper end of the film support roller 22a and presses the porous resin film 17 slightly downward from the upper end of the film support roller 22a. The winding shaft 26, located downstream of the second blade 30, is located slightly lower than the lower end 30a, and the porous resin film 17 flows between the second blade 30 and the winding shaft 26 at an incline downward toward the downstream.

[0051] Next, the application step 24 will be described. Liquid elastomer 19 is supplied from a liquid elastomer supply device (not shown) onto the upper surface of the porous resin film 17 that is flowing in contact with the film support roller 22b, and the liquid elastomer 19 comes into contact with the first blade 28 to scrape off excess material to achieve a uniform thickness. The film then passes through the film support roller 22a, and then comes into contact with the second blade 30 to scrape off excess material again to achieve a uniform thickness. The first blade 28 and second blade 30 apply the liquid elastomer 19 to a uniform thickness, while also ensuring that the liquid elastomer 19 is impregnated into the micropores of the porous resin film 17.

[0052] According to the tube 10 of this embodiment, the wall thickness t, wall thickness ratio, and number of layers I of the resin portion 13 are set such that, for thicknesses greater than 2.8 mm, the wall thickness ratio is kept relatively small, thereby reducing the absolute value of wall thickness variation and improving durability. Furthermore, by setting the number of layers I within the above-described preferred range, even greater durability can be achieved. In other words, under these conditions, the wall thickness of the tube 10 can be set relatively uniformly within a predetermined range, eliminating variations in thickness depending on the location when the tube 10 deforms, and preventing loads from concentrating on specific locations, thereby improving durability.

[0053] Furthermore, according to the tube 10 of this embodiment, the inner surface has low surface roughness and is smooth. This reduces friction when the inner walls of the tube 10 adhere to each other when the tube 10 is crushed to close the internal space, preventing minute separation of the innermost surface. This reduces the inclusion of foreign matter in the discharged fluid. The tube 10 can be easily manufactured by applying a liquid elastomer 19 to a porous resin film 17. In the liquid elastomer 19 application step 24, the first blade 28 and the second blade 30 contact the film twice to scrape off excess liquid elastomer 19, ensuring a uniform thickness. This ensures that the liquid elastomer 19 is reliably impregnated into the voids in the porous resin film 17, thereby enabling the manufacture of a tube 10 that meets optimal conditions for achieving high durability.

[0054] The tube of the present invention is not limited to the above embodiment, and other methods for manufacturing the porous resin film may be used. The material of the elastomer layer may also be other than those described above. The number and positions of film support rollers and the position of the coating process in the manufacturing process may be changed as appropriate. The longitudinal length of the tube is free, and the tube can be used for a variety of purposes.

[0055] Next, a method for evaluating the adhesiveness of the inner surface of a tube will be described. Japanese Patent Application Laid-Open No. 2018-91718, which is a prior art, can be used as a reference. The adhesiveness evaluation method of this example will be described with reference to FIG. 5. First, a tube A to be measured is inserted between the upper movable member B and the lower fixed member C in FIG. 5(a). Although not shown, a load cell, for example, is connected to the movable member B in order to measure the reaction force generated when the movable member B presses the tube A.

[0056] Next, while supporting tube A with fixed member C, movable member B is lowered as shown by the white arrow in the figure, applying a constant load to tube A in the radial direction and pressing it, closing through-hole D in tube A as shown in Figure 5(b). In this state, the reaction force F (N) of tube A measured by the load cell, as shown by the length of the black arrow in the figure, reaches its maximum value during measurement.

[0057] Next, the load applied to the tube A by the movable member B is released at a constant speed. Specifically, the movable member 2 is raised at a constant speed from the state shown in FIG. 5(b). As a result, as shown in FIGS. 5(b) to 5(e) and 6, the tube A follows the rise of the movable member B and gradually returns to its original shape over time T, reducing the reaction force F (F1 > F2 at T1 and T2 in FIGS. 5(c), 5(d), and 6). Finally, the tube A returns to the state shown in FIG. 1(f) (where reaction force F = 0), which is the same as the state shown in FIG. 5(a) before pressing.

[0058] Specifically, the pinch valve tube of the present invention (e.g., inner diameter 1 mm to 10 mm, length 50 mm to 200 mm) is attached to a pinch valve device with a solenoid-driven opening / closing mechanism, one end of the tube is connected to an air supply as the IN side and the other end is connected to a pressure gauge as the OUT side, and the opening / closing mechanism is operated to press the tube radially to close the passage hole. Then, while applying 100 kPa of air pressure to the IN side of the tube, the opening / closing mechanism is operated to release the pressure on the tube, and the time required for the passage hole of the tube to actually open and the pressure gauge to detect pressure is defined as the response time. By providing the tube with elasticity such that the response time is 20 ms or less, the pinch valve can be made highly responsive to opening. The pressure detected by the pressure gauge depends on the detection sensitivity of the pressure gauge, but a preset minimum detection sensitivity pressure, for example, a pressure of about 1 kPa, may be set.

[0059] By using the tube 10 of this embodiment in the pinch valve device 1, it is possible to suppress breakage of the tube 10 when the internal pressure in the device or the tube 10 increases, and to suppress damage caused by negative pressure within the tube 10, and it is also possible to improve durability against repeated pinching operations. As a result, it is possible to reduce the burden of maintenance on the tube 10, the pinch valve device 1, and the fluid supply system equipped with them.

[0060] Next, an embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a perspective view showing the appearance of a pinch valve device 1 to which a tube 10 of the present invention is applied. Figure 2 is a perspective view showing the internal structure of a valve body 2 of the pinch valve device 1 shown in Figure 1. The pinch valve device 1 comprises a valve body 2 having a disk-shaped appearance and a drive device 4 that drives a mechanism provided inside the valve body 2.

[0061] As shown in FIG. 2 , the valve body 2 shown in FIG. 1 includes a first valve housing 40, a pipe mounting portion 42 provided on the first valve housing 40, a second valve housing 44, and a pipe mounting portion 46 provided on the second valve housing 44.

[0062] The tube 10 is attached to the inside of the first valve housing 40 and the second valve housing 44 in a manner that it straddles and penetrates them, and is attached so that a flange portion 11 (described later) comes into contact with the pipe mounting portion 42 and the pipe mounting portion 46, respectively. Therefore, the flange portion 11 also functions as a positioning portion when attaching the pinch valve tube 10 to the pinch valve device 1. An outer peripheral member 60 is provided on the outer periphery of the tube 10 and covers the tube 10.

[0063] 2, a rotor 50 is rotatably inserted inside the first valve housing 40 and second valve housing 44 that make up the valve body 2. A gear portion 52 is formed on part of the outer periphery of the rotor 50, and a pair of opposing cam lobes 54 and second cam lobes 55 are provided inside the rotor 50. A drive gear meshes with the gear portion 52 and is connected to a drive device (not shown).

[0064] The tube 10 of the present invention is inserted and disposed inside the rotor 50. The flange portions 11 at both ends of the tube 10 are fitted into and firmly held by the pipe mounting portions 42, 46 of the first valve housing 40 and the second valve housing 44.

[0065] Also, inside the rotor 50, outside the center of the tube 10, a pair of pinch levers 56 are provided which are rotatable about a pair of supports 58 to clamp the tube 10 and stop the flow of fluid inside.

[0066] As a result, when the rotor 50 rotates, the pinch levers 56 are pressed inward by the first cam lobes 54 formed inside the rotor 50, causing them to rotate. This rotation reduces the gap between the pair of pinch levers 56, pinching and squeezing the center of the tube 10 of the pinch valve device 1, thereby closing the internal space of the tube 10.

[0067] In this embodiment, the tube 10 is a cylindrical member having the same wall thickness and same inner diameter in the longitudinal direction (e.g., inner diameter 2 mm, length 100 mm). Flanges 11 are integrally formed on both longitudinal ends of the tube 10, but the flanges 11 may be formed on only one end of the tube 10. Furthermore, the flanges 11 function as a connection part for connecting the tube 10 to other piping when the tube 10 is attached to the pinch valve device 1, and can also function as a positioning part during attachment.

[0068] The outer member 60 is formed with an inner diameter the same as the outer diameter of the tube 10 and is positioned so as to be in close contact with the outer surface of the tube 10, or is formed with an inner diameter slightly larger than the outer diameter of the tube 10 and is positioned so as to be able to rotate freely around the outer surface of the tube 10.

[0069] Since the tube 10 of the present invention is used in the pinch valve device 1, it must immediately and completely shut off the flow of fluid when the pinch lever 56 is closed, and immediately ensure a fluid flow path when the pinch lever 56 is opened. Therefore, when the tube 10 of the embodiment of the present invention is repeatedly opened and closed at a cycle of 1 opening and closing of the pinch lever 56 per second, it is preferable that the number of opening and closing cycles before cracks and / or a decrease in flow rate occur in the tube 10 is 1 million or more. The tube 10 of the embodiment of the present invention satisfies this condition, and the evaluation results are shown in Table 2.

[0070] Furthermore, since the tube 10 of the present invention is used in the pinch valve device 1, it must immediately and completely shut off the flow of fluid when the pinch lever 56 is closed, and immediately ensure a fluid flow path when the pinch lever 56 is opened. Therefore, the tube 10 of the embodiment of the present invention must immediately return to its original shape in a short response time when the pinch lever 56 is opened. To achieve this, the adhesive strength of the inner surface of the tube (substitute for the valve opening response time) must be low.

[0071] An example of a method for measuring the adhesive force of the inner surface of a tube (substituted by the valve opening response time) is shown below. A pinch valve was made by combining a tube for a pinch valve of the present invention with a solenoid-driven opening / closing mechanism, and one end of the tube was connected to an air supply as the IN side, and the other end was connected to a pressure gauge as the OUT side. The length of the tube in this example is the length required for the pinch valve device and is set according to the device.

[0072] The opening and closing mechanism was then operated to press the tube radially to close the through-hole, and the opening and closing mechanism was operated while applying an air pressure of 100 kPa to the IN side of the tube, releasing the pressure on the tube. The time required from the point at which the through-hole of the tube actually opened and the pressure gauge on the OUT side detected pressure (for example, 1 kPa) was measured as the response time to evaluate responsiveness. The results are also shown in Table 2.

[0073] (Measurement of tube inner surface roughness and hardness) A tube for a pinch valve of the present invention (inner diameter 2 mm, length 100 mm) was cut in the longitudinal direction, and the inner surface was examined using a confocal laser microscope (Olympus Corporation laser microscope (LEXT-OLS4100), magnification 50x, objective lens with a numerical aperture of 0.95) to measure the surface roughness in accordance with the contact-type standard (JIS B 0633: 2001). Ten measurements were taken for each sample, and the arithmetic mean roughness Ra (μm) and maximum height roughness Rz (μm) were determined. The measurement direction was perpendicular to the processing direction for samples with a fixed processing direction, and was in an arbitrary direction for samples with an unfixed processing direction. The average of 10 values ​​of Ra and Rz and the 95% confidence limit using Student's t-distribution were determined for each sample.

[0074] Furthermore, the tube for a pinch valve of the present invention was cut in the longitudinal direction, and its inner surface was measured using a durometer hardness tester (type: A, load: 1 kgf, measurement location: points 12 mm or more away from the end of the sample, reading time: 15 seconds, number of tests: 5 points 6 mm or more away) in accordance with JIS K6253. The median of these values ​​was taken as the hardness of the inner surface of the tube. The measurement results are also shown in Table 2.

[0075] From these results, it was found that the pinch valve tube of the present invention has high valve opening response and excellent durability, and the pinch valve opening response is superior to that of conventional tubes.

[0076] REFERENCE SIGNS LIST 1 pinch valve device 2 valve body 4 drive device 10 tube 11 flange portion 12 flow path 13 resin portion 16 porous resin layer 17 porous resin film 18 elastomer layer 19 liquid elastomer 24 application process 40 first valve housing 42, 46 pipe mounting portion 44 second valve housing 50 rotor 52 gear portion 54 first cam lobe 55 second cam lobe 56 pinch lever 58 support

Claims

1. A tube having a constant shape in the longitudinal direction, with a flow path penetrating the inside in the longitudinal direction and a resin part surrounding the flow path, the resin part being configured as a laminate in which porous resin layers laminated in the radial direction of the flow path and elastomer layers bonding the porous resin layers are alternately laminated, the elastomer layers being made of at least one type of elastomer, the porous resin layers having voids, the voids being impregnated with a portion of the elastomer, the tube being attached to a pinch valve device of a solenoid-driven opening and closing mechanism, one end of the tube is connected as the IN side to an air supply section and the other end is connected as the OUT side to a pressure gauge, and the opening and closing mechanism is operated to press the tube radially to close the flow path that passes through both ends of the tube, and while applying an air pressure of 100 kPa to the IN side of the tube, the opening and closing mechanism of the pinch valve device is operated; the response time is the time from the point at which the pressure on the tube is released to the point at which the flow path of the tube is opened and the OUT side pressure gauge detects the air pressure, and the tube has an elasticity such that the response time is 20 ms or less.

2. In one cross section at any position in the longitudinal direction of the tube, an average value of the thickness of the resin portion in at least four directions perpendicular to each other in the radial direction of the flow path is calculated, and a thickness ratio, which is an average value of the ratio of the thicknesses of opposing ones of the four directions, and the number of layers of the porous layer and the elastomer layer are calculated. When the average thickness is 0.5 mm or more and less than 2.8 mm, the thickness ratio is 1.0 to 1.2, and when the average thickness is 2.8 mm or more and less than 10.3 mm, the thickness ratio is 1.0 to 1.

1. Furthermore, with regard to the number of layers, when the average thickness is 0.5 mm or more and less than 1.4 mm, the number of layers is 5 or more and less than 35, when the average thickness is 1.4 mm or more and less than 2.0 mm, the number of layers is 14 or more and less than 50, and when the average thickness is 2.0 mm or more and less than 2.8 mm, the number of layers is 20 or more and less than 70.

2. The tube for a pinch valve according to claim 1, wherein when the average thickness is 2.8 mm or more and less than 4.0 mm, the number of layers is 28 or more and less than 100; when the average thickness is 4.0 mm or more and less than 6.2 mm, the number of layers is 40 or more and less than 155; when the average thickness is 6.2 mm or more and less than 7.7 mm, the number of layers is 62 or more and less than 193; and when the average thickness is 7.7 mm or more and less than 10.3 mm, the number of layers is 77 or more and less than 258.

3. A tube for a pinch valve as claimed in claim 1 or 2, wherein the porous resin layer has a porosity of 70% or more.

4. The tube for a pinch valve according to claim 3, wherein the porosity of the porous resin layer is 70% to 85%.

5. A tube for a pinch valve as described in claim 1, 2 or 4, wherein the inner surface of the liquid-contacting side of the tube for a pinch valve is smooth, and the surface satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 3.00 (μm).

6. A tube for a pinch valve according to claim 1, 2 or 4, wherein the inner surface of the tube for a pinch valve on the liquid-contacting side has a hardness of 40 to 70 on the Shore A scale.

7. A tube for a pinch valve as described in claim 6, wherein the inner surface of the liquid-contacting side of the tube for a pinch valve is smooth, and the surface satisfies at least one of an arithmetic mean roughness Ra of 0.01 to 0.80 (μm) and a ten-point mean roughness Rz of 0.01 to 3.00 (μm).

8. The pinch valve tube of claim 7, wherein the elastomer is silicone, urethane, nitrile rubber, styrene-butadiene rubber, chloroprene, phosphazene, methyl silicone, phenyl silicone, fluoroelastomer, perfluoroelastomer, perfluoropolyether elastomer, or combinations thereof.

9. A method for producing a tube comprising the steps of: drawing out a polytetrafluoroethylene film from an original roll of polytetrafluoroethylene film; coating and impregnating the polytetrafluoroethylene film with a liquid elastomer; winding up the polytetrafluoroethylene film coated and impregnated with the liquid elastomer in multiple layers on a winding shaft; heat treating the polytetrafluoroethylene film to promote a crosslinking reaction of the liquid elastomer and bond the layers of the polytetrafluoroethylene film together; and forming a laminate in which polytetrafluoroethylene layers made of the polytetrafluoroethylene film and elastomer layers made of the liquid elastomer are alternately laminated; wherein the tube is attached to a pinch valve device of a solenoid-driven opening and closing mechanism; the liquid elastomer application step comprises: supplying and placing the liquid elastomer on the upper surface of the polytetrafluoroethylene film; pressing a first blade against the upper surface of the polytetrafluoroethylene film vertically from above to bring it into contact with the surface, scraping off excess liquid elastomer to obtain a uniform thickness; and contacting the upper surface of the polytetrafluoroethylene film from above with a second blade, the second blade being pressed against the upper surface of the polytetrafluoroethylene film and having a lower end inclined so that the lower end that contacts the polytetrafluoroethylene film faces downstream, to scrape off excess liquid elastomer again to obtain a uniform thickness; applying the liquid elastomer to a uniform thickness by the first blade and the second blade, and simultaneously impregnating the polytetrafluoroethylene film with the liquid elastomer; forming the tube, which is an elongated object having a uniform shape in the longitudinal direction, and which is provided with a flow path penetrating therethrough in the longitudinal direction on the inside, and which is provided with a resin portion surrounding the flow path, the resin portion is formed by alternately winding a plurality of the polytetrafluoroethylene layers stacked in a radial direction of the flow path and the elastomer layers bonding the polytetrafluoroethylene layers together, the elastomer layers being made of at least one type of elastomer, the polytetrafluoroethylene layers having voids, the voids being impregnated with a portion of the elastomer,In one cross section at an arbitrary position in the longitudinal direction of the tube, an average value of wall thicknesses in four mutually perpendicular directions in the radial direction of the flow path of the resin portion is calculated, and a wall thickness ratio, which is an average value of a ratio of the wall thicknesses in opposing directions among the four directions, and the number of laminations of the polytetrafluoroethylene layer and the elastomer layer are calculated. When the average wall thickness is 0.5 mm or more and less than 2.8 mm, the wall thickness ratio is 1.0 to 1.2, and when the average wall thickness is 2.8 mm or more and less than 10.3 mm, the wall thickness ratio is 1.0 to 1.

1. Furthermore, with regard to the number of laminations, when the average wall thickness is 0.5 mm or more and less than 1.4 mm, the number of laminations is 5 or more and less than 35, when the average wall thickness is 1.4 mm or more and less than 2.0 mm, the number of laminations is 14 or more and less than 50, and when the average wall thickness is 2.0 mm or more and less than 2.8 mm, the number of laminations is 20 or more and less than 70. a number of layers being 28 or more and less than 100 when the average wall thickness is 2.8 mm or more and less than 4.0 mm; a number of layers being 40 or more and less than 155 when the average wall thickness is 4.0 mm or more and less than 6.2 mm; a number of layers being 62 or more and less than 193 when the average wall thickness is 6.2 mm or more and less than 7.7 mm; and a number of layers being 77 or more and less than 258 when the average wall thickness is 7.7 mm or more and less than 10.3 mm.

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