JP7716201B2 - diaphragm valve - Google Patents

Description

The present invention relates to a diaphragm valve having a stress distribution plate.

In the manufacture of precision devices such as semiconductor devices and liquid crystal display devices, ultrapure water refined to an extremely high level has traditionally been used in wet processes such as cleaning. If metal ions or other impurities are present in the water at a concentration above a certain level, they can be adsorbed onto wafer surfaces and have a negative impact on the quality of the precision devices, so the amount of impurities in the ultrapure water is strictly controlled.

Impurities can also get mixed into ultrapure water in the piping that makes up the ultrapure water transport line. Metals such as stainless steel, which have excellent gas barrier properties, have been used as piping materials, but considering the impact of metal leaching from the piping, it is considered preferable to use resin.

Among the resins used for ultrapure water piping, polyvinylidene fluoride (PVDF) is used in all practical applications in the semiconductor industry, including piping within ultrapure water production equipment and piping for transporting ultrapure water from the equipment to use points, and has become the technical standard for ultrapure water piping.

Patent Document 1 discloses that PVDF is used in diaphragm valves for ultrapure water.

Recently, as the integration density of semiconductor chips has increased, circuit patterns have become increasingly finer, making them more susceptible to even low-level impurities. As a result, the quality requirements for ultrapure water are becoming increasingly strict.

PVDF is also used as a fluororesin material with excellent chemical resistance and contamination resistance, making it suitable for use as a chemical-resistant piping material.

Patent Document 2 discloses that PVDF is used in diaphragm valves for chemical-resistant applications.

JP 1-231984 Patent Publication No. 2019-184063

Piping made of fluororesin such as PVDF has disadvantages in terms of workability and cost compared to other common piping. However, as the required quality of ultrapure water becomes stricter, fluororesin piping is effectively the only option for piping that meets the required water quality.
The present inventors have deliberately focused on alternative materials for ultrapure water valves. For example, polyethylene-based resins, which are easy to install and cost-effective, are commonly used as piping materials. However, polyethylene-based resins have low long-term compressive strength, and when a bolted joint is tightened with a bolt and nut, creep deformation of the polyethylene occurs over time, reducing the bolt axial tension and leading to watertightness problems. For this reason, polyethylene is not currently used in valves that require long-term strength.

The purpose of this disclosure is to provide a diaphragm valve that can improve watertightness.

To achieve the above object, a diaphragm valve according to a first aspect comprises a first flange portion, a second flange portion, a diaphragm, a drive mechanism, a first stress distribution plate, and a second stress distribution plate. The first flange portion has a flow path inlet formed therein and is intended for connection to another member. The second flange portion has a flow path outlet formed therein and is intended for connection to another member. The diaphragm opens and closes the flow path. The drive mechanism closes or opens the flow path by driving the diaphragm. The first stress distribution plate is disposed on a first surface of the first flange portion opposite the side connected to the other member. The second stress distribution plate is disposed on a second surface of the second flange portion opposite the side connected to the other member. The first flange portion is connected to the other member by a first bolt passing through it together with the first stress distribution plate and a first nut threaded onto the first bolt. The first flange portion is connected to the other member by a second bolt passing through it together with the second stress distribution plate and a second nut threaded onto the second bolt. The first flange and second flange are made of polyethylene resin. The thickness of each of the first stress distribution plate and second stress distribution plate is 1.5 mm or more and 4 mm or less.

In this way, by placing a stress dispersion plate at the part where the bolt and nut are fastened to another component, compressive creep deformation due to tightening can be suppressed, making it possible to improve watertightness.

Furthermore, even when polyethylene-based resin is used for the first flange portion and second flange portion, water-stopping properties can be improved.

In addition, by specifying the thickness of the stress dispersion plate, it is possible to further improve water-stopping properties.

The diaphragm valve of the second aspect is the diaphragm valve of the first aspect, except that the first stress distribution plate is formed to span two or more bolt fastening holes in the first flange portion. The second stress distribution plate is formed to span two or more bolt fastening holes in the second flange portion.

By forming a stress dispersion plate in this way so that it spans two or more bolt fastening holes, it is possible to further improve watertightness.

The diaphragm valve of the third aspect is the diaphragm valve of the first or second aspect, wherein the area of the first stress distribution plate in contact with the first surface is 50% or more of the area of the first surface. The area of the second stress distribution plate in contact with the second surface is 50% or more of the area of the second surface.

By setting the installation area of the stress distribution plate to 50% or more of the installation surface in this way, it is possible to further improve water-stopping properties.

The diaphragm valve of the fourth aspect is the diaphragm valve of any one of the first to third aspects, in which the first stress distribution plate and the second stress distribution plate are each made of stainless steel.

By forming it from stainless steel in this way, it is possible to further improve its water-stopping properties.

The diaphragm valve according to the fifth aspect is a diaphragm valve according to any one of the first to fourth aspects, in which the Young's modulus of the material of each of the first bolt and the second bolt is 200 GPa or less.

In this way, by setting the Young's modulus of the material of the first bolt and second bolt to 200 GPa or less, water-stopping properties can be improved.

The diaphragm valve of the sixth aspect is the diaphragm valve of any one of the first to fifth aspects, in which the first bolt and the second bolt are each made of stainless steel.

By forming it from stainless steel in this way, it is possible to further improve its water-stopping properties.

The diaphragm valve of the seventh aspect is a diaphragm valve of any one of the first to sixth aspects, in which the first bolt and the second bolt are each made of SUS304.

By using SUS304, which has a relatively low Young's modulus, bolts made of SUS304 elongate more when tightened with the same tightening torque than bolts made of a material with a higher Young's modulus than SUS304. This reduces the collapse of the polyethylene resin present near the bolt fastening holes in the flange of the diaphragm due to compression. As a result, the axial force of the bolt is maintained for a longer period of time, and it is believed that torque retention is higher even after a certain period of time has passed.

The diaphragm valve of the eighth aspect is a diaphragm valve of any one of the first to seventh aspects, wherein the diaphragm valve is used for ultrapure water or chemical-resistant purposes.

The diaphragm valve of this embodiment can improve long-term watertightness, making it suitable for use in ultrapure water or chemical-resistant applications.

This disclosure provides a diaphragm valve that can improve watertightness.

FIG. 1 is an external perspective view of a diaphragm valve according to an embodiment of the present disclosure; FIG. 1 is a partial cross-sectional view of a diaphragm valve according to an embodiment of the present disclosure. 1 is a perspective view showing a valve body 11 of a diaphragm valve according to an embodiment of the present disclosure. FIG. FIG. 1 is a cross-sectional view of a diaphragm valve according to an embodiment of the present disclosure. FIG. 1 is a front view showing a state in which a diaphragm valve according to an embodiment of the present disclosure is connected to another member. 1A is a front view showing a stress distribution plate according to an embodiment of the present disclosure; FIG. 1B is a front view showing a stress distribution plate according to an embodiment of the present disclosure; FIG. 1A is a front view showing a surface on which two stress distribution plates are arranged; FIG. 1B is a front view showing a surface on which two stress distribution plates are arranged. FIG. 1 is a front view showing a state in which a diaphragm valve according to an embodiment of the present disclosure is connected to another member. FIG. 8B is an exploded view of the connection between the other member and the first flange portion in FIG. 8A. FIG. 2A is a schematic cross-sectional view showing a state in which a flow channel is closed, and FIG. 2B is a schematic cross-sectional view showing a state in which the flow channel is open.

The following describes a diaphragm valve according to an embodiment of the present disclosure.

<1. Structure>
Fig. 1 is a perspective view of the appearance of a diaphragm valve 10 according to an embodiment of the present disclosure. Fig. 2 is a partial cross-sectional view of the diaphragm valve 10 according to the embodiment.

As shown in Figures 1 and 2, the diaphragm valve 10 of this embodiment comprises a valve body 11, a diaphragm 12 (also called a diaphragm), a bonnet 13, a drive mechanism 14, and a stress dispersion plate 15 (see Figure 4).

The first flange portion 21 and second flange portion 22 of the valve body 11 are connected to flanges and piping of other components, and a flow path 24 through which fluid flows is formed in the valve body 11. The diaphragm 12 opens and closes the flow path 24. The bonnet 13 is attached to the valve body 11 so as to cover the diaphragm 12. A portion of the drive mechanism 14 is located within the bonnet 13 and drives the diaphragm 12. The stress distribution plate 15 is installed on the side of the first flange portion 21 or second flange portion 22 opposite the side connected to the other component (see Figure 4, described below).

(Valve body)
Fig. 3 is a perspective view showing the valve body 11. Fig. 4 is a cross-sectional view of the diaphragm valve 10. Fig. 4 is a cross-sectional view taken along the line A-A' in Fig. 1. Fig. 5 is a front view showing the piping structure in which the diaphragm valve is connected to other components. In Fig. 4, the stress dispersion plate 15 is shown in place but not fixed with bolts or the like in order to show the position of the stress dispersion plate 15.

PE (polyethylene) is used for the valve body 11 due to its ease of installation and low leaching properties. PE's properties can be modified to the desired level by changing the catalyst used during polymerization. Examples of catalysts that can be used include polymerization catalysts such as Ziegler-Natta catalysts, metallocene catalysts, and chromium oxide catalysts.

Polyethylene resins may be copolymerized with α-olefins as needed. Examples of α-olefins that can be copolymerized with polyethylene resins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-butene-1-hexene, 1-butene-4-methyl-1-pentene, and 1-butene-1-octene.

The valve body 11 is made of a material whose main component is the aforementioned PE. The main component refers to the component with the highest content by mass. The main component is a component whose content is at least 50%.

As shown in Figures 3 and 4, the valve body has a first flange portion 21, a second flange portion 22, a central portion 23, and a flow path 24.

The first flange portion 21, the second flange portion 22, and the central portion 23 are integrally formed, and the flow path 24 is formed across the first flange portion 21, the central portion 23, and the second flange portion 22, as shown in Figure 4.

The first flange portion 21 is connected to the flange 72 and piping 73 of the other member 71. As shown in FIG. 4, the first flange portion 21 has a first flange surface 21a on which an inlet 24a through which fluid flows into the valve body 11 is formed, a surface 21b (an example of a first surface) on the valve body 11 side opposite the first flange surface 21a, and a bolt fastening hole 21c (see FIG. 5) that penetrates from the first flange surface 21a to surface 21b. As shown in FIG. 1, multiple bolt fastening holes 21c are formed around the inlet 24a; in this embodiment, for example, four bolt fastening holes are formed.

As shown in Figure 5, the other member 71 has a pipe 73 and a flange 72 located at the end of the pipe 73. The flange 72 has a flange surface 72a that contacts the first flange surface 21a of the valve body 11, a surface 72b opposite the flange surface 72a, and a bolt fastening hole 72c that penetrates from the flange surface 72a to the surface 72b. Multiple bolt fastening holes 72c are formed around the inlet to the pipe 73 formed in the flange surface 72a; in this embodiment, for example, four bolt fastening holes are formed.

The flange 72 of the other member 71 is connected to the first flange portion 21 with the other member 71 positioned relative to the first flange portion 21 so that the flange surface 72a faces the first flange surface 21a and the bolt fastening holes 21c and 72c face each other. It is preferable to place a gasket or similar between the first flange portion 21 and the flange 72.

The first flange portion 21 and the flange 72 of the other member 71 are connected using a first bolt 81 and a first nut 82. The first bolt 81 is inserted into the bolt fastening hole 21c of the first flange portion 21 and the bolt fastening hole 72c of the flange 72. The first nut 82 is screwed onto the tip of the first bolt 81 that passes through the bolt fastening hole 21c and the bolt fastening hole 72c. This fastens the first flange portion 21 and the flange 72 together with the first bolt 81 and the first nut 82.

The head of the first bolt 81 is positioned on the surface 72b of the flange 72, and the first nut 82 is positioned on the surface 21b side of the first flange portion 21. Furthermore, a stress distribution plate 15 (described below) is positioned between the first nut 82 and the valve body 11 (specifically, surface 21b). The stress distribution plate 15 positioned on the surface 21b of the first flange portion 21 corresponds to an example of a first stress distribution plate.

The second flange portion 22 is connected to a flange 76 and a pipe 77 of another member 75. As shown in FIG. 4, the second flange portion 22 has a second flange surface 22a on which an outlet 24b through which fluid is discharged from the valve body 11 is formed, a surface 22b (an example of a second surface) on the valve body 11 side opposite the second flange surface 22a, and a bolt fastening hole 22c (see FIG. 5) that penetrates from the second flange surface 22a to the surface 22b. Multiple bolt fastening holes 22c are formed around the outlet 24b; in this embodiment, for example, four bolt fastening holes are formed.

As shown in FIG. 5, the other member 75 includes a pipe 77 and a flange 76 located at the end of the pipe 77. The flange 76 has a flange surface 76a that contacts the second flange surface 22a of the valve body 11, a surface 76b opposite the flange surface 76a, and a bolt fastening hole 76c that penetrates from the flange surface 76a to the surface 76b. Multiple bolt fastening holes 76c are formed around the inlet to the pipe 77 formed in the flange surface 76a; in this embodiment, for example, four bolt fastening holes are formed.

The flange 76 of the other member 75 is connected to the second flange portion 22 with the other member 75 positioned relative to the second flange portion 22 so that the flange surface 76a faces the second flange surface 22a and the bolt fastening holes 22c and 76c face each other. It is preferable to place a gasket or the like between the second flange portion 22 and the flange 76.

The second flange portion 22 and the flange 76 of the other member 75 are connected using a second bolt 85 and a second nut 86. The second bolt 85 is inserted into the bolt fastening hole 22c of the second flange portion 22 and the bolt fastening hole 76c of the flange 76. The second nut 86 is screwed onto the tip of the second bolt 85 that passes through the bolt fastening hole 22c and the bolt fastening hole 76c. This fastens the second flange portion 22 and the flange 76 together with the second bolt 85 and the second nut 86.

The head of the second bolt 85 is positioned on the surface 76b of the flange 76, and a second nut 86 is positioned on the surface 22b side of the second flange portion 22. A stress distribution plate 15, described below, is also positioned between the second nut 86 and the valve body 11 (specifically, surface 22b). The stress distribution plate 15 positioned on the surface 22b of the second flange portion 22 corresponds to an example of a second stress distribution plate.

The first bolt 81 and the second bolt 85 can be made from metals such as iron, copper, copper alloy, brass, aluminum, and stainless steel, but it is preferable to make them from stainless steel in order to maintain watertightness for a long period of time.

Examples of stainless steel include SUS303, SUS304, SUS316, SUS310S, SUS410, and SUS430. The Young's modulus of SUS303, SUS304, and SUS316 is 193 GPa, while the Young's modulus of SUS310S, SUS410, and SUS430 is 200 GPa. Therefore, it is preferable that the Young's modulus of the material of the first bolt 81 and the second bolt 85 be 200 GPa or less.

The first nut 82 and the second nut 86 can be made from metals such as iron, copper, copper alloy, brass, aluminum, and stainless steel.

The first flange portion 21 and the second flange portion 22 are arranged opposite each other as shown in Figures 3 and 4, and the first flange surface 21a and the second flange surface 22a are formed to face each other and be parallel, as shown in Figure 4. The positions of the inlet 24a and the outlet 24b are also opposite each other.

As shown in FIG. 4, the central portion 23 is located between the first flange portion 21 and the second flange portion 22. The central portion 23 has a connecting portion 23a to the first flange portion 21 and a connecting portion 23b to the second flange portion 22. The above-mentioned surface 21b refers to the surface on the central portion 23 side of the first flange portion 21 and surrounding the connecting portion 23a. Surface 21b refers to the portion parallel to the first flange surface 21a. Furthermore, the above-mentioned surface 22b refers to the surface on the central portion 23 side of the second flange portion 22 and surrounding the connecting portion 23b. Surface 22b is parallel to the second flange surface 22a.

The central portion 23 has a first surface 31 with an opening 31a formed in the center. As shown in Figures 3 and 4, the first surface 31 is generally planar and is formed perpendicular to the first flange surface 21a and the second flange surface 22a. As shown in Figure 3, the opening 31a has a curved periphery. A protrusion 34 is formed along the periphery of the opening 31a. The diaphragm 12 is positioned inside this protrusion 34. In addition, a plurality of bolt holes 32 are formed in the first surface 31 around the opening 31a.

The direction along the line connecting the inlet 24a and the outlet 24b is defined as the first direction X, the direction perpendicular to the first direction X and parallel to the first surface 31 is defined as the second direction Y, and the direction perpendicular to the first surface 31 is defined as the third direction Z. The first direction X can also be said to be a direction along a straight line perpendicular to the first flange surface 21a and the second flange surface 22a.

As shown in Figure 4, the flow path 24 extends from the inlet 24a to the outlet 24b. The wall 33 is formed in the center of the flow path 24, protruding toward the first surface 31. The wall 33 is formed so that the inner surface of the flow path 24 rises gently toward the first surface 31, creating a slope in the flow path 24. The opening 31a described above is formed in a position corresponding to the wall 33. The diaphragm 12, described below, is pressed against the tip surface 33a of the wall 33 on the first surface 31 side.

The flow path 24 has an inlet-side flow path 241 formed from the inlet 24a of the first flange portion 21 to the wall portion 33, an outlet-side flow path 242 formed from the outlet 24b of the second flange portion 22 to the wall portion 33, and a communication portion 243 connecting the inlet-side flow path 241 and the outlet-side flow path 242.

As shown in Figure 4, the width of the inlet-side flow path 241 in a direction perpendicular to the first surface 31 (width in the third direction Z) narrows toward the wall portion 33. On the other hand, the width of the inlet-side flow path 241 in a direction parallel to the first surface 31 (width in the second direction Y) widens toward the wall portion 33 (see Figure 2).

The outlet-side flow path 242 is formed from the outlet 24b of the second flange portion 22 to the wall portion 33. As shown in FIG. 4, the width of the outlet-side flow path 242 in a direction perpendicular to the first surface 31 (width in the third direction Z) narrows toward the wall portion 33. On the other hand, the width of the outlet-side flow path 242 in a direction parallel to the first surface 31 (width in the second direction Y) widens toward the wall portion 33.

The communication section 243 is the portion of the flow path 24 on the first surface 31 side of the wall section 33, and connects the inlet side flow path 241 and the outlet side flow path 242.

(Diaphragm 12)
As shown in FIGS. 2 and 4, the diaphragm 12 is disposed on the first surface 31 so as to close the opening 31 a, and includes a diaphragm body 41 and an engaging member 42 .

The material of the diaphragm body 41 may be any rubber-like elastic material, such as ethylene propylene rubber, isoprene rubber, chloroprene rubber, chlorosulfonated rubber, nitrile rubber, styrene butadiene rubber, chlorinated polyethylene, fluororubber, EPDM (ethylene propylene diene rubber), and PTFE (polytetrafluoroethylene), among others. PTFE is used due to its high cleanability.

In addition, a high-strength reinforcing cloth may be inserted into the diaphragm body 41, and it is preferable that the reinforcing cloth be made of nylon. This is preferable because it makes it possible to prevent deformation or damage to the diaphragm body 41 when fluid pressure is applied to the diaphragm body 41 when the diaphragm valve 10 is closed.

As shown in Figures 2 and 4, the outer peripheral edge 43 of the diaphragm body 41 is sandwiched between the bonnet 13 and the valve body 11, which will be described later.

The diaphragm 12 is moved downward by the drive mechanism 14 (described later) and comes into contact with the tip surface 33a of the wall portion 33, thereby closing the communication portion 243 and closing the flow path 24. The diaphragm 12 is also moved upward by the drive mechanism 14 and moves away from the tip surface 33a, thereby opening the flow path 24.

(Hood 13)
Like the valve body 11, the bonnet 13 can be formed from resins such as PE (polyethylene), PVC (polyvinyl chloride), HT (heat-resistant polyvinyl chloride pipe), PP (polypropylene), PVCF (polyvinylidene fluoride), polystyrene, ABS resin, polytetrafluoroethylene, perfluoroalkyl vinyl ether copolymer, polychlorotrifluoroethylene, etc., or metals such as iron, copper, copper alloy, brass, aluminum, stainless steel, etc., or porcelain, etc., and it is preferable to use PE (polyethylene) from the viewpoint of workability and cost.

As shown in Figures 1 and 2, the bonnet 13 is fixed to the first surface 31 of the valve body 11 by a third bolt 88 and a third nut (not shown). The bonnet 13 is arranged to cover the opening 31a via the diaphragm 12.

As shown in Figures 2 and 4, the bonnet 13 has an opening 13a corresponding to the first surface 31, and a through-hole 13b opposite the opening 13a in which a sleeve 62 and stem 63 (described below) are disposed.

(Drive mechanism 14)
The drive mechanism 14 includes a compressor 61 , a sleeve 62 , a stem 63 , and a handle 64 .

The compressor 61 is made of PVDF (polyvinylidene fluoride) or similar material and is connected to the diaphragm 12. An engagement member 42 is embedded in the diaphragm body 41, and the engagement member 42 protrudes from the opposite side (non-liquid-contacting side) of the valve body 11. The protruding portion of the engagement member 42 engages with the compressor 61, connecting the compressor 61 and the diaphragm 12.

The sleeve 62 is supported in the through-hole 13b of the bonnet 13. A threaded shape is formed on the inside of the sleeve 62.

The stem 63 is positioned inside the sleeve 62, and the threaded portion formed on its outer periphery is threadedly engaged with the threaded portion formed inside the sleeve 62. The compressor 61 is fixed to the end of the stem 63 that is positioned inside the bonnet 13.

The compressor 61 engages with the diaphragm 12 on the valve body 11 side and is fixed to the stem 63 on the opposite side from the valve body 11.

The handle 64 is engaged with the outer periphery of the stem 63 at the portion located outside the bonnet 13.

(Stress dispersion plate 15)
The stress dispersion plate 15 can be made of strong metals such as iron, copper, copper alloy, brass, aluminum, and stainless steel, or porcelain, among which stainless steel is preferred from the viewpoint of achieving both strength and ease of installation. Examples of stainless steel that can be used include SUS304, SUS316, SUS303, SUS317, and SUS403.

As shown in Figure 5, the stress dispersion plate 15 is fixed between the valve body 11 and the first nut 82 and between the valve body 11 and the second nut 86 using a first bolt 81 and a second bolt 85.

Figures 6(a) and 6(b) are plan views showing the stress dispersion plate 15.

As shown in Figures 6(a) and 6(b), each stress distribution plate 15 is shaped to span two or more bolt fastening holes 21c or bolt fastening holes 22c of the first flange portion 21 or the second flange portion 22.

The stress dispersion plate 15 shown in Figure 6(a) has a substantially semicircular shape. A circular notch 15b is formed in the center of the radial shape of the stress dispersion plate 15.

Figure 7(a) is a front view showing the surface 21b on which two stress distribution plates 15 are arranged. Figure 7(a) is a view taken along arrow B shown in Figure 1, which is parallel to the first direction X. Note that for the sake of explanation, the stress distribution plates 15 are indicated by dots in Figure 7(a).

As shown in Figure 7(a), two stress distribution plates 15 are arranged adjacent to each other to form a circular shape on the surface 21b. The connection portion 23a (see Figure 4) of the center portion 23 to the first flange portion 21 passes through the cutouts 15b of the two adjacent stress distribution plates 15.

Two bolt holes 15a are formed in each stress distribution plate 15, and the bolt holes 15a face the bolt fastening holes 21c on the surface 21b. As shown in FIG. 5, a first bolt 81 is inserted through the bolt fastening holes 72c in the flange 72, the bolt fastening holes 21c in the first flange portion 21, and the bolt hole 15a in the stress distribution plate 15, and a first nut 82 is threaded onto the tip of the first bolt 81 protruding from the bolt hole 15a. The stress distribution plate 15 is sandwiched between the first nut 82 and the surface 21b.

Figure 7(b) is a front view showing the surface 22b on which two stress distribution plates 15 are arranged. Figure 7(b) is a view taken along arrow C shown in Figure 1, which is parallel to the first direction X. Note that in Figure 7(b), the stress distribution plates 15 are indicated by dots for illustrative purposes.

As shown in Figure 7(b), two stress distribution plates 15 are arranged adjacent to each other to form a circular shape on surface 22b. The connection portion 23b (see Figure 4) of the center portion 23 to the second flange portion 22 passes through the cutouts 15b of the two adjacent stress distribution plates 15.

Two bolt holes 15a are formed in each stress distribution plate 15, facing the bolt fastening holes 22c on the surface 22b. A second bolt 85 is inserted through the bolt fastening holes 76c in the flange 76, the bolt fastening holes 22c in the second flange portion 22, and the bolt holes 15a in the stress distribution plate 15, and a second nut 86 is threaded onto the tip of the second bolt 85 protruding from the bolt hole 15a. The stress distribution plate 15 is sandwiched between the second nut 86 and the surface 22b.

In this way, in this embodiment, a stress distribution section is provided to distribute the stress caused by fastening bolts and nuts when connecting the flange of another component to the flange portion of the diaphragm valve. This stress distribution section is composed of, for example, two semicircular members (stress distribution plates 15) as shown in Figure 6(a), but it may also be a single member in which two semicircular stress distribution plates 15 are connected at connecting portion 15c with screws or the like, as shown in Figure 6(b).

In order to distribute the stress caused by fastening the bolts, the area of the stress distribution plate 15 is at least 50%, more preferably at least 70%, and even more preferably at least 80% of the area of the surface 21b on the central portion 23 side of the first flange portion 21 or the area of the surface 22b on the central portion 23 side of the second flange portion 22.

The thickness of the stress distribution plate 15 is set to 1.5 mm or more and 4 mm or less so that it can withstand the axial tightening force of the bolts and does not cause any problems with installation.

Note that although connection to other components has been described using Figure 5, this is not limiting. For example, connection to other components 71' and 75' may be possible as shown in Figure 8A. Compared to the other component 71 of the piping structure shown in Figure 5, the other component 71' shown in Figure 8A has a flange 72' with a smaller diameter than the first flange portion 21 (this can be considered a small face seat). Also, compared to the other component 75 of Figure 5, the other component 75' shown in Figure 8A has a flange 76' with a smaller diameter than the second flange portion 22. Note that in the configuration shown in Figure 8A, the connection portions 23a' and 23b' of the center portion 23' of the valve body 11 are also thinner than those shown in Figure 5.

In the configuration shown in FIG. 8A, the other member 71' is connected to the first flange portion 21 by a pressing member 91, a first bolt 81, and a first nut 82. The other member 75' is connected to the second flange portion 22 by a pressing member 92, a second bolt 85, and a second nut 86.

The connection between another member 71' and the first flange portion 21 will be described as an example. Figure 8B is an exploded view of the connection between another member 71' and the first flange portion 21. As shown in Figure 8B, the other member 71' has a flange 72' and a pipe 73'. The flange 72' has a flange surface 72a' facing the first flange surface 21a, and a surface 72b' opposite the flange surface 72a'. Unlike the flange 72, the flange 72' does not have bolt fastening holes 72c.

The pressing member 91 presses the flange 72' against the first flange surface 21a. The pressing member 91 is a plate-shaped member with a through hole 91d through which the piping 73' passes. The pressing member 91 has a pressing surface 91a that presses against the surface 72b' of the flange 72', a surface 91b opposite the pressing surface 91a, and a bolt fastening hole 91c formed from the pressing surface 91a to the surface 91b. A first bolt 81 is inserted into the bolt fastening hole 91c of the pressing member 91, the bolt fastening hole 21c of the first flange portion 21, and the bolt hole 15a of the stress distribution plate 15, and a first nut 82 is threaded onto the tip of the first bolt 81 protruding from the bolt hole 15a. By tightening the first nut 82, the pressing member 91 presses the flange 72' against the first flange portion 21. The head of the first bolt 81 is positioned on the surface 91b of the pressing member 91, the first nut 82 is positioned on the surface 21b side of the first flange portion 21, and a stress dispersion plate 15 is positioned between the first nut 82 and the first flange portion 21.

In this way, even another member 71' equipped with a small face seat flange 72' can be connected to the first flange portion 21.

The same applies to the connection between the other member 75 and the second flange portion 22.

The other component 75' has a flange 76' and a pipe 77'. The flange 76' has a flange surface 76a' facing the second flange surface 22a and a surface 76b' opposite the flange surface 76a'. Unlike the flange 76, the flange 76' does not have bolt fastening holes 76c.

The pressing member 92 presses the flange 76' against the second flange surface 22a. The pressing member 92 is a plate-shaped member with a through hole 92d through which the piping 77' passes. The pressing member 92 has a pressing surface 92a that presses against the surface 76b' of the flange 76', a surface 92b opposite the pressing surface 92a, and a bolt fastening hole 92c formed from the pressing surface 92a to the surface 92b. A second bolt 85 is inserted into the bolt fastening hole 92c of the pressing member 92, the bolt fastening hole 22c of the second flange portion 22, and the bolt hole 15a of the stress distribution plate 15, and a second nut 86 is threaded onto the tip of the second bolt 85 protruding from the bolt hole 15a. By tightening the second nut 86, the pressing member 92 presses the flange 76' against the second flange portion 22. The head of the second bolt 85 is positioned on the surface 92b of the pressing member 92, the second nut 86 is positioned on the surface 22b side of the second flange portion 22, and a stress dispersion plate 15 is positioned between the second nut 86 and the second flange portion 22.

In this way, even another member 75' provided with a faceplate flange 76' can be connected to the second flange portion 22.

<2. Operation＞
Next, the operation of the diaphragm valve 10 of this embodiment will be described. Figures 9(a) and 9(b) are diagrams that schematically show the operation of the diaphragm 12.

When the handle 64 is rotated in the direction to close the flow path 24 from an open state as shown in Figure 9(a), the stem 63 moves toward the flow path 24 as the handle 64 rotates. As the stem 63 moves, the compressor 61 fixed to the end of the stem 63 also moves toward the flow path.

As the compressor 61 moves toward the flow path 24, the diaphragm 12 curves convexly toward the wall portion 33, as shown in Figure 9(b), and is pressed against the tip surface 33a of the wall portion 33.

This blocks the flow path 24 of the diaphragm valve 10.

On the other hand, when the handle 64 is rotated in the opening direction, the stem 63 moves to the side opposite the flow path 24 as the handle 64 rotates. As the stem 63 moves, the compressor 61 also moves, and the central portion of the diaphragm 12 engaged with the compressor 61 moves as shown in Figure 9(a).

This opens the flow path 24 of the diaphragm valve 10.

<3. Application>
(Ultra pure water applications)
The diaphragm valve 10 according to the embodiment of the present disclosure can be used in ultrapure water transport piping. Specifically, the diaphragm valve 10 according to the embodiment of the present disclosure can be used in piping within an ultrapure water production apparatus, piping for transporting ultrapure water from an ultrapure water production apparatus to a use point, piping for returning ultrapure water from a use point, etc.

The diaphragm valve 10 of the embodiment disclosed herein is preferably used in water piping for nuclear power generation, where the required quality of ultrapure water is particularly strict, or in ultrapure water transport piping used in pharmaceutical manufacturing processes, or in wet processing processes such as cleaning in the manufacturing of semiconductor devices or liquid crystals, more preferably semiconductor devices. The semiconductor devices in question are preferably those with a higher degree of integration, and more specifically, are more preferably used in manufacturing processes for semiconductor devices with a minimum line width of 65 nm or less. Examples of standards related to the quality of ultrapure water used in semiconductor manufacturing include SEMIF75.

(chemical resistant applications)
The diaphragm valve 10 according to the embodiment of the present disclosure can be used for transporting chemical liquids, and can also be used for transporting highly corrosive fluids or fluids that require contamination prevention in industries such as chemical plants, semiconductor manufacturing, liquid crystal manufacturing, and food manufacturing.

Semiconductor manufacturing processes involve cleaning the surface of silicon wafers (substrates) with diluted chemical solutions. This is done to remove particles, metal contaminants, oxide films, etc., and a processing solution made by mixing multiple chemical solutions and pure water in appropriate ratios is used. Examples of processing solutions include APM (ammonia, hydrogen peroxide, and pure water), HPM (hydrochloric acid, hydrogen peroxide, and pure water), DHF (hydrofluoric acid and pure water), and SPM (sulfuric acid and hydrogen peroxide).

The diaphragm valve 10 of the embodiment disclosed herein is preferably used as a transport pipe for APM (ammonia, hydrogen peroxide, and pure water), HPM (hydrochloric acid, hydrogen peroxide, and pure water), DHF (hydrofluoric acid and pure water), SPM (sulfuric acid and hydrogen peroxide), etc.

4. Other Embodiments
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

(A)
In the above embodiment, the stress distribution plate 15 is disposed between the first nut 82 and the surface 21b. However, this is not limiting, and the positions of the first nut 82 and the head of the first bolt 81 may be reversed. That is, in the example of the piping structure of FIG. 5 , the first nut 82 may be disposed on the surface 72b of the flange 72, and the stress distribution plate 15 may be disposed between the head of the first bolt 81 and the surface 21b. Similarly, the stress distribution plate 15 may not be disposed between the second nut 86 and the surface 22b, and the positions of the second nut 86 and the head of the second bolt 85 may be reversed. That is, the second nut 86 may be disposed on the surface 76b of the flange 76, and the stress distribution plate 15 may be disposed between the head of the second bolt 85 and the surface 22b. The same applies to the piping structure of FIG. 8A .

(B)
In the above embodiment, two bolt holes 15a are formed in one stress distribution plate 15, but this is not limited to this. For example, three or more bolt holes may be formed. The number of bolt fastening holes 21c in the first flange portion 21 and the number of bolt fastening holes 22c in the second flange portion 22 are not limited to four.

(C)
In the above embodiment, two stress distribution plates 15 or one stress distribution member consisting of two stress distribution plates 15 connected to each other are arranged on surfaces 21b and 22b, but if the number of bolt fastening holes 21c and bolt fastening holes 22c is five or more, three or more stress distribution plates 15 may be arranged on surfaces 21b and 22b.

(D)
In the above embodiment, the stress dispersion plate 15 is formed in a circular shape so as to follow the outer shapes of the surfaces 21b and 22b, but the shape is not limited to a circular shape.

(E)
In the diaphragm valve 10 of the above embodiment, a manual handle 64 is provided as an example of a drive unit, but the stem 63 may be driven by an air-driven or electrically driven drive unit.

Next, we will explain the embodiments of this disclosure using examples.

[Valve body configuration]
The valve body 11 of the diaphragm valve 10 is injection molded using the following materials by a conventional molding method.

HB534N (Japan Polyethylene Corporation)
[Stress distribution plate configuration]
In Examples 1 and 2 and Comparative Examples 1 to 3, diaphragm valves were used in which the thickness t of the stress dispersion plate 15 made of SUS304 was changed to 5.0 mm, 3.0 mm, 2.0 mm, 1.0 mm, or 0 mm (no stress dispersion plate).

The area occupancy of the prepared stress distribution plate was measured. The area occupancy is the value obtained by dividing the area of the stress distribution plate 15 by the area of the surface 21b on the central portion 23 side of the first flange portion 21.

[Stress relaxation test]
A stress relaxation test was carried out on a flange portion (for example, the first flange portion 21) of a diaphragm valve according to the following procedure.
1) Only the flange portion of the diaphragm valve was cut using a band saw to prepare a flange cutting piece.
2) A sample was prepared by connecting four M16 bolts (material: SCM435) to, in order from the head side of the bolts, a stress dispersion plate, flange cuttings, packing (Eslon PTFE packing 50A JIS10K (PP50) manufactured by Sekisui Chemical Co., Ltd.), and a stainless steel pipe flange (SUSF304-TRFF-10K-50A manufactured by MIE Techno Co., Ltd.). Hereinafter, this sample will be referred to as the "stress relaxation test sample."
3) The sample for the stress relaxation test was set in a uniaxial testing machine (RTF-2430-W-XL-S, manufactured by Orientec Co., Ltd.), and then the lifting plate of the uniaxial testing machine was brought into contact with the bolt of the sample for the stress relaxation test, and an initial load of 43.75 kN was applied to the bolt of the sample for the stress relaxation test.
4) After the initial load was applied, the height of the lifting plate of the uniaxial testing machine was fixed for 3 hours, and the load applied to the uniaxial testing machine was measured.

[evaluation]
Table 1 shows the load after 3 hours, the load retention rate, and the evaluation results of workability for the diaphragm valves of Examples 1 and 2 and Comparative Examples 1 to 3.

The load retention rate is the load after three hours divided by the initial load. If the stress distribution plate could be installed, the workability was rated as "OK", and if it could not be installed, the workability was rated as "X".

If the load retention rate was 85% or more and the workability was good, it was rated as good (〇), and if the load retention rate was less than 85% or the workability was poor, it was rated as poor (×).

In Example 1, the load and workability were evaluated using a diaphragm valve with a stress dispersion plate thickness t of 2.0 mm. The diaphragm valve of Example 1 had a load retention rate of 89.5%, and the workability was rated as good.

In Example 2, a diaphragm valve with a stress distribution plate thickness t of 3.0 mm was used to evaluate the load and ease of installation. The diaphragm valve of Example 2 had a load retention rate of 94.3%, and its ease of installation was rated as good.

In Comparative Example 1, a diaphragm valve without a stress distribution plate was used to evaluate the load and ease of installation. For the diaphragm valve of Comparative Example 1, the load retention rate was 52.6%, and the ease of installation was rated as good, resulting in a poor evaluation.

In Comparative Example 2, a diaphragm valve with a stress distribution plate thickness t of 1.0 mm was used to evaluate the load and ease of installation. For the diaphragm valve of Comparative Example 2, the load retention rate was 57.4%, and the ease of installation was rated as good, resulting in a poor evaluation.

In Comparative Example 3, workability was evaluated using a diaphragm valve with a stress dispersion plate thickness t of 5.0 mm. The workability of the diaphragm valve in Comparative Example 3 was rated x and was judged to be poor.

[Long-term tightening torque measurement]
A long-term tightening torque evaluation of a flange portion (for example, the first flange portion 21) of a diaphragm valve was carried out according to the following procedure.
1) A sample was prepared by connecting four M16 bolts, in this order from the head side of the bolts, a stainless steel pipe flange (MIE Techno Corporation, SUSF304-TRFF-10K-50A), a packing (Sekisui Chemical Co., Ltd., Eslon PTFE packing 50A JIS10K (PP50)), a flange portion of a diaphragm valve, a stress dispersion plate, and an M16 nut.
2) Using an M16 wrench and a digital torque wrench, four M16 bolts were tightened to 35 N·m each.
3) The sample was left to stand in a constant temperature environment of 23°C for 1,500 hours.
4) Using an M16 wrench and a digital torque wrench, the tightening torque of the four bolts was measured after 1,500 hours had elapsed using the retightening method.

Table 2 shows the tightening torque (average tightening torque of the four bolts) and tightening torque retention rate after 1,500 hours for the diaphragm valves of Examples 3-4 and Comparative Examples 4-7.

The tightening torque retention rate is the tightening torque after 1,500 hours divided by the initial tightening torque (35 N·m).

A tightening torque retention rate of 50% or more and workability of ○ was rated as good (○), and a tightening torque retention rate of less than 50% or workability of × was rated as poor (×).

As shown in Table 2, the diaphragm valve (Examples 3-6) equipped with a stress dispersion plate having a thickness of 1.5 mm or more and 4 mm or less had a good tightening torque retention rate, and was able to improve watertightness.

On the other hand, a sufficient tightening torque retention rate could not be achieved with diaphragm valves without stress dispersion plates (Comparative Examples 4 and 5) or with diaphragm valves with stress dispersion plates having a thickness of 1.5 mm or less (Comparative Example 6).

Furthermore, the diaphragm valve equipped with a 5 mm thick stress dispersion plate (Comparative Example 7) had a good tightening torque retention rate, but its workability was rated as x, resulting in a poor evaluation.

Furthermore, as shown by a comparison between Example 3 and Example 4, and a comparison between Example 5 and Example 6, the use of SUS304 bolts results in a better tightening torque retention rate than the use of SCM435 bolts. The following are presumed to be the reasons for this.

In other words, SUS304 has a smaller Young's modulus than SCM435, and when the bolts are tightened with the same tightening torque, the bolt elongates more when tightened with a SUS304 bolt. This reduces the collapse caused by compression of the polyethylene resin present near the bolt fastening holes (e.g., bolt fastening hole 21c) in the flange portion of the diaphragm. As a result, the axial force of the bolt is maintained for a longer period of time, and it is believed that the torque retention rate is higher even after a certain period of time has passed.

As described above, we have discovered that by installing a stress distribution plate at the bolt fastening point of a diaphragm valve made of polyethylene resin, compressive creep deformation caused by bolt tightening can be suppressed and watertightness can be maintained without impairing the valve's functionality as a valve for ultrapure water.

The diaphragm valve disclosed herein has the effect of improving watertightness and can be used in ultrapure water applications, chemical-resistant applications, etc.

10: Diaphragm valve 15: Stress dispersion plate 21: First flange portion 21b: Surface 22: Second flange portion 22b: Surface 24: Flow path 24a: Inlet 24b: Outlet 71: Other member 75: Other member

Claims (7)

a first flange portion in which an inlet of the flow path is formed and which is intended to be connected to a first other member;
a second flange portion in which an outlet of the flow path is formed and which is intended to be connected to a second other member;
a diaphragm that opens and closes the flow path;
a driving mechanism that drives the diaphragm to close or open the flow path;
a first stress dispersion plate disposed on a first surface of the first flange portion opposite to a side connected to the first other member;
a second stress dispersion plate disposed on a second surface of the second flange portion opposite to the side connected to the second other member , the second stress dispersion plate being not connected to the first stress dispersion plate;
the first flange portion is connected to a flange at the tip of the first other member by a first bolt that penetrates together with the first stress distribution plate and a first nut that screws onto the first bolt, the flange of the first other member is sandwiched between a first pressing member through which the first bolt penetrates and the first flange portion, the flange of the first other member has a smaller diameter than the first pressing member and the first flange portion, and the first bolt is disposed outside the flange of the first other member,
the second flange portion is connected to a flange at the tip of the second other member by a second bolt that penetrates together with the second stress distribution plate and a second nut that screws onto the second bolt, the flange of the second other member is sandwiched between a second pressing member through which the second bolt penetrates and the second flange portion, the flange of the second other member has a smaller diameter than the second pressing member and the second flange portion, and the second bolt is disposed outside the flange of the second other member,
the first flange portion and the second flange portion are formed of a polyethylene-based resin,
The thickness of each of the first stress dispersion plate and the second stress dispersion plate is 1.5 mm or more and 4 mm or less,
The Young's modulus of the material of each of the first bolt and the second bolt is 200 GPa or less.
Diaphragm valve. the first stress dispersion plate is formed to extend over two or more bolt fastening holes of the first flange portion,
2. The diaphragm valve according to claim 1, wherein the second stress dispersion plate is formed so as to span two or more bolt fastening holes of the second flange portion. an area of the first stress dispersion plate in contact with the first surface is 50% or more of an area of the first surface;
an area where the second stress dispersion plate is in contact with the second surface is 50% or more of an area of the second surface;
3. The diaphragm valve according to claim 1 or 2. The first stress dispersion plate and the second stress dispersion plate are each made of stainless steel.
The diaphragm valve according to any one of claims 1 to 3. A diaphragm valve as described in any one of claims 1 to 4, wherein the first bolt and the second bolt are each made of stainless steel. The diaphragm valve described in any one of claims 1 to 5, wherein the first bolt and the second bolt are each made of SUS304. The diaphragm valve is used for ultrapure water or chemical resistance.
The diaphragm valve according to any one of claims 1 to 6.