Valve seat manufacturing method

Abstract

To provide a manufacturing method of a valve seat which is excellent in seal performance owing to the non-imbalance of polish amounts of both faces at the polishing of a slide face side and a fixed face side of the valve seat, and also excellent in productivity.SOLUTION: In a manufacturing method of a synthetic resin-made valve seat of a disc valve device which switches a flow passage and a flow rate of fluid by making a valve body slide to a valve seat 2, one face of the valve seat 2 is a slide face which slides with the valve body, and the other face is a fixed face 6 fixed to a box body via a packing. The manufacturing method has a polishing process for polishing both faces of a polishing object, and forming the slide face and the fixed face 6. A difference between a polishing area of the polishing object at the slide face side and a polishing area at the fixed face side is within -20% to 20% with respect to a polishing area of the slide face side.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a valve seat of a disk valve device that switches a fluid flow path and flow rate. [Background technology]

[0002] Disk valve devices that switch flow paths and flow rates are used in hot and cold water mixing faucets, body local cleansing devices, etc. (Patent Document 1, Patent Document 2) In this disk valve device, a movable disc, the valve body, is slidably disposed relative to a fixed disc, the valve seat, and grooves and holes that serve as flow paths are formed in the valve seat and the valve body.

[0003] The sliding surfaces of the valve seat and valve disc are precisely polished to prevent fluid leakage and reduce sliding torque.The valve seat and valve disc are injection-molded from lubricating synthetic resin to facilitate the formation of complex shapes and reduce sliding torque.

[0004] The disc valve device contains a disc valve consisting of a valve seat and a valve body, and a packing inside a housing. The counter-sliding surface, which is the surface of the valve seat opposite the sliding surface, is pressed and fixed against the bottom surface of the housing via a rubber packing (hereinafter, the counter-sliding surface will be referred to as the fixed surface). The valve seat is positioned so that it cannot rotate within the housing. The valve seat has multiple through-holes (water passage holes) for water passage, which pass from the fixed surface to the sliding surface. A flow path that supplies tap water to the disc valve is formed in the lower part of the housing, and the flow path and the water passage holes communicate via holes in the packing. The water passage connecting the valve seat and the housing is prevented from leaking by the packing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-336648 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-270863 Summary of the Invention [Problem to be solved by the invention]

[0006] The sliding and fixed surfaces of the valve seat must be smooth to prevent water leakage (ensuring sealing), and are therefore finished by polishing. Therefore, a polishing allowance is provided on the sliding and fixed surface sides of the molded body (molding material) before polishing, and the thickness of the molding material is molded so that it is thicker by the polishing allowance than the thickness of the valve seat after polishing.

[0007] Conventionally, double-sided lapping machines have been used to polish the sliding and fixed surfaces of valve seats. However, after polishing, the amount of polishing on the sliding surface side and the amount of polishing on the fixed surface side of the valve seat are unbalanced, which can result in the intended polishing amount not being achieved. This is because the differences in the designs (flat shape and concave / convex shape) of the sliding and fixed surfaces result in a large difference in the area actually polished on both sides of the molded body, and the polishing height on the surface with a larger polishing area is smaller than the polishing height on the surface with a smaller polishing area. Here, the polishing height refers to the height removed by polishing on each surface.

[0008] Conventionally, as described above, the imbalance in the amount of polishing between the sliding surface side and the fixed surface side has been corrected by repairing the molding die. That is, when the sliding surface side and the fixed surface side are simultaneously polished using a double-sided lapping machine, if the polishing allowance on one side is polished and the polishing allowance on the other side remains, the remaining polishing allowance on the other side is removed by carving it into the mold cavity that forms the other side. Typically, molding dies are formed with multiple cavities to allow for multiple product production, from the perspective of production efficiency. Therefore, repairing a molding die can take a great deal of time and money, potentially leading to increased product costs. Furthermore, a single mold repair may not correct the imbalance in the amount of polishing between the sliding surface side and the fixed surface side, requiring a second or third repair. In such cases, the completion of the molding die and the planned start of production may be delayed.

[0009] The present invention aims to provide a method for manufacturing a valve seat that has excellent sealing properties and productivity by preventing imbalance in the amount of polishing on both the sliding surface side and the fixed surface side of the valve seat when polishing them. [Means for solving the problem]

[0010] The method for manufacturing a valve seat of the present invention is a method for manufacturing a synthetic resin valve seat in a disk valve device that switches the flow path and flow rate of a fluid by sliding a valve body against the valve seat, wherein one surface of the valve seat is a sliding surface that slides against the valve body and the other surface is a fixed surface that is fixed to a housing via a packing, and the manufacturing method includes a polishing step of polishing both surfaces of an object to be polished to form the sliding surface and the fixed surface, and the difference between the polished area on the sliding surface side of the object to be polished and the polished area on the fixed surface side is within -20% to 20% of the polished area on the sliding surface side.

[0011] Here, "the polishing area on the sliding surface side of the object to be polished" refers to the area of ​​the surface on the sliding surface side of the object to be polished that is actually polished, and "the polishing area on the fixed surface side of the object to be polished" refers to the area of ​​the surface on the fixed surface side of the object to be polished that is actually polished. The difference D between the two polishing areas can be expressed by the following formula (1): Difference D (%) = ((polished area on the fixed surface side - polished area on the sliding surface side) / (polished area on the sliding surface side)) × 100 (1)

[0012] The polishing step is characterized in that polishing is performed simultaneously on both sides of the object to be polished, and further characterized in that the polishing is performed by a double-sided grinding machine.

[0013] The manufacturing method is characterized in that it includes a molding step, prior to the polishing step, in which a resin composition is injection molded to obtain a molded body that will be the object to be polished, and in the molding step, the molded body is formed so that the polishing area on the fixed surface side is larger than the polishing area on the sliding surface side.

[0014] The molded body is characterized in that the surface of the molded body facing the fixing surface has a recess formed deeper than the polishing allowance of the surface. [Effects of the Invention]

[0015] The method for manufacturing a valve seat of the present invention includes a polishing step in which both surfaces of an object to be polished are polished to form a sliding surface and a fixed surface of the valve seat. The difference between the polished area on the sliding surface side of the object to be polished and the polished area on the fixed surface side is within -20% to 20% of the polished area on the sliding surface side. This ensures that the difference in polishing rate (thickness that can be polished in a certain time) for the sliding surface side and the fixed surface side of the object to be polished falls within a predetermined range, ensuring uniform polishing without imbalance in the amount of polishing on both sides. As a result, the sealing performance of the fixed portion with the housing via a packing and the contact portion with the valve disc is excellent. Furthermore, repairs to the molding die due to imbalances in the amount of polishing are not necessary, reducing the time and cost required for die repairs and improving productivity.

[0016] In the polishing process, polishing is performed simultaneously on both sides of the object to be polished, using, for example, a double-sided grinding machine, so that the time required to polish the valve seat can be shortened, resulting in superior productivity.

[0017] In the valve seat, the sliding surface, which switches the flow path with the valve body, tends to have a larger concave area than the fixed surface. Therefore, in the object to be polished (molded body), the polishing area of ​​the surface on the fixed surface side is likely to be significantly larger than that of the surface on the sliding surface side. Even in such cases, the molded body obtained by the molding process has a recess formed on the surface on the fixed surface side that is deeper than the polishing allowance of that surface, so that the recess can reduce the polishing area and make it easier to keep the difference in polishing area within a specified range. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 2 is a plan view of the valve body as seen from the sliding surface. [Figure 2] FIG. 2 is a plan view of the valve seat as seen from the sliding surface. [Figure 3] FIG. 2 is a plan view of the valve seat as seen from the fixed surface. [Figure 4] FIG. 4 is an enlarged cross-sectional view of part A in FIG. 3. [Figure 5] FIG. 4 is an enlarged cross-sectional view illustrating a recess in the molded body. [Figure 6] FIG. 2 is a perspective view of a molded body according to an embodiment. [Figure 7] FIG. 10 is a perspective view of a molded body of a comparative example. [Figure 8] FIG. 2 is a side view of the human body local cleansing device. [Figure 9] FIG. 2 is a cross-sectional view of the human body local cleansing device. DETAILED DESCRIPTION OF THE INVENTION

[0019] As an example of a disk valve device using a valve seat manufactured by the manufacturing method of the present invention, a human private parts washing device will be described with reference to Figure 8. The human private parts washing device 14 comprises a housing 15 having a disk valve 21 therein as flow path switching means, and a drive device 16 for driving the flow path switching means within the housing 15. The flow path switching means provided inside the housing 15 is composed of a valve body 1 and a valve seat 2, which will be described later. The housing 15 is also connected to a cleansing water supply device 17 that supplies cleansing water into the housing 15, a human private parts washing nozzle 18 that sprays the cleansing water supplied from the cleansing water supply device 17 onto human private parts, a nozzle cleansing water discharge part 19 that cleans the human private parts washing nozzle 18, and a drain part 20 from which the cleansing water is discharged.

[0020] The human body local cleansing device 14 is configured to switch the flow path within the housing 15 by driving the flow path switching means inside the housing 15 with a drive device 16, and to circulate the cleansing water from the cleansing water supply device 17 to either the human body local cleansing nozzle 18 or the nozzle cleansing water discharge part 19.

[0021] As shown in Figure 8, in disc valve 21, valve seat 2 (fixed disc) is fixed non-rotatably to housing 15, valve element 1 (movable disc) is rotatable relative to valve seat 2, and valve element 1 and valve seat 2 are arranged so that their sliding surfaces can slide freely against each other. Valve element 1 rotates while sliding around the center of its circular shape as the axis of rotation, and the holes and grooves of valve element 1 and valve seat 2 overlap or shift with each other, thereby switching the water flow path and flow rate. In Figure 8, valve seat 2 is manufactured by the manufacturing method of the present invention.

[0022] The internal structure of this human body local cleansing device will be described using Figure 9. Figure 9 is a schematic cross-sectional view taken along the rotation axis of the drive unit. As shown in Figure 9, the housing 15 contains a valve disc 1 that rotates with a drive unit 16, a valve seat 2 that is fixed to the housing 15 and has a water passage hole that communicates with the human body local cleansing nozzle and the nozzle cleansing water discharge unit, and a gasket 13 whose shape and position correspond to the water passage hole. The gasket 13 connects the valve seat 2 to the flow path of the housing 15, allowing cleansing water to flow to the human body local cleansing nozzle, the nozzle cleansing water discharge unit, and the drain unit. As described above, the valve seat 2 is positioned so that one surface faces the valve disc 1 and the other surface faces the gasket 13. The fixed surface 6 of the valve seat 2 that faces the gasket 13 contacts the housing 15 via the gasket 13.

[0023] As an example of a disc valve, FIG. 1 shows a valve disc, and FIG. 2 shows a valve seat. FIG. 1 is a plan view of the valve disc, showing the sliding surface that slides against the valve seat. As shown in FIG. 1, a valve disc recess 1a consisting of grooves and holes of various shapes is formed on the sliding surface of the valve disc 1. The valve disc recess 1a forms a flow path (water passage) for tap water.

[0024] Next, Figure 2 is a plan view of the valve seat, showing the sliding surface that slides against the valve disc. The sliding surface 3 of the valve seat 2 and a portion of the fixed surface behind the sliding surface 3 are polished to a smooth surface using a mechanical method such as a double-sided grinder. As shown in Figure 2, the sliding surface 3 of the valve seat 2 is formed with grooves 4 and water passage holes 5 of various shapes that form the water passage. In Figure 2, the water passage holes 5 are through-holes that pass from the sliding surface 3 to the fixed surface.

[0025] Figure 3 is a plan view of the fixed surface of the valve seat shown in Figure 2. Each water passage hole 5 on the fixed surface is separated by a packing that contacts the valve seat 2. Contact with the packing prevents water from leaking from the housing when the disc valve device is in use. In Figure 3, the fixed surface 6 is composed of a surface 7 that contacts the packing, a surface 8 surrounding the water passage hole 5, and a concave surface 9. The contact surface 7 and the surrounding surface 8 are polished surfaces. The concave surface 9 is a surface other than the polished surface (a non-polished surface) and is recessed to a predetermined depth relative to the polished surface. Here, the polished surface is also called a convex surface, and in Figure 3, the convex surface is the surface that combines the contact surface 7 and the surrounding surface 8.

[0026] The relationship between the convex and concave surfaces on the fixing surface will be explained using FIG. 4. FIG. 4 shows an enlarged cross-sectional view of the boundary between the concave surface 9 and the contact surface 7, which is the area A surrounded by the dotted line in FIG. 3. As shown in FIG. 4, it is preferable to provide a slope on the wall surface that forms the boundary between the concave surface 9 and the contact surface 7. In FIG. 4, the inclined surface 10 connecting the concave surface 9 and the contact surface 7 is inclined at 40° with respect to the contact surface 7. It is preferable that the inclined surface 10 be inclined at an angle of 20° to 45° with respect to the contact surface 7. This makes it easier to prevent the generation of grinding burrs and, even if grinding burrs are generated, to easily remove them. The inclination angle of the inclined surface 10 is more preferably 25° to 40°.

[0027] An example of the method for manufacturing the valve seat of the present invention will be described below, however, the manufacturing method of the present invention is not limited to the method described below.

[0028] The manufacturing method of the present invention includes a molding step of injection-molding a resin composition to obtain a molded body (object to be polished), and a polishing step of polishing both surfaces of the molded body to form a sliding surface 3 (see FIG. 2) and a fixed surface 6 (see FIG. 3). The present invention is characterized in that the difference between the polished area on the sliding surface side of the object to be polished and the polished area on the fixed surface side before polishing is within −20% to 20% of the polished area on the sliding surface side. In other words, the polished area on the sliding surface side of the object to be polished that is actually polished is approximately equal to the polished area on the fixed surface side. This prevents imbalances in the amount of polishing due to polishing. The difference in the polished areas is preferably within −15% to 15%, more preferably within −10% to 10%. This difference is calculated using the above formula (1).

[0029] In the present invention, the size relationship between the polished area on the sliding surface side and the polished area on the fixed surface side is not particularly limited.

[0030] In the molding process, molding pellets obtained by melt-kneading a resin composition (described later) are molded into a predetermined shape by a known injection molding method. For example, considering the flow path design of the disc valve as well as the polishing speed in the polishing process, unevenness is provided on both the sliding surface and the fixed surface. The molded body obtained in this molding process becomes the object to be polished in the subsequent polishing process. Therefore, in this molding process, the molded body is molded so that the difference in the polished area is within -20% to 20%. For example, as described later, the difference in the polished area is adjusted by molding a molded body with a recess formed on the surface facing the fixed surface.

[0031] Generally, the shapes of the sliding surface and the fixed surface of a valve seat are more complex on the sliding surface, which switches the flow path with the valve body. As a result, the area of ​​the concave shape tends to be larger on the sliding surface. Therefore, the polishing area on the object to be polished is likely to be larger on the fixed surface side than on the sliding surface side, and the difference in the polishing area tends to widen.

[0032] To address this issue, it is preferable to form a recess on the surface of the molded body facing the fixed surface to reduce the polishing area on the fixed surface side. This recess can also be considered an adjustment recess for adjusting the polishing area. By forming a recess, the polishing area on the fixed surface side tends to become approximately equal to the polishing area on the sliding surface side. Figure 5 shows an enlarged cross-sectional view of the recess on the molded body. Note that Figure 5 shows the state of the valve seat shown in Figure 4 before polishing.

[0033] As shown in Fig. 5, a recess 12 is formed on the surface 11a of the molded body 11 on the fixing surface side. a is the grinding allowance D of the surface 11a on the fixed surface side. b It is formed deeper than depth D. a is the depth from the surface 11a on the fixed surface side to the concave surface 12a, which is the surface that is not polished. For example, b If is 0.2 mm, the depth D a The depth D is formed to be greater than 0.2 mm, for example, 0.3 mm. a is the grinding allowance D b The thickness is, for example, 0.03 mm to 0.5 mm larger than the thickness.

[0034] In FIG. 5, the polishing allowance D b The surface from which the part is removed becomes the contact surface 7 (see FIG. 4). In addition, the concave surface 12a of the recess 12 is the concave surface 9 on the valve seat (see FIG. 4).

[0035] The recess 12 of the molded body 11 can be formed by changing the shape of the cavity of the injection molding die. The recess 12 is formed by a convex portion in the cavity. Furthermore, it is preferable to provide a slope on the wall surface 12b, which is the boundary between the recess 12 and the surface 11a on the fixing surface side, to prevent burrs from occurring due to polishing. The slope is preferably 20° to 45°, and more preferably 25° to 40°, with respect to the surface 11a on the fixing surface side, which is the surface to be polished.

[0036] The location of the recess on the surface of the molded article facing the fixed surface is not particularly limited, but it is preferable to form it on a surface of the valve seat other than the surface 7 that contacts the packing (see Figure 3) and the surface 8 around the water passage hole 5 (see Figure 3). Typically, the fixed surface is flat except for the portion where the water passage hole is recessed. However, since there is no functional problem with forming a recess in areas other than the portion that contacts the packing, recesses can be formed in those areas. In other words, since the portion that contacts the packing cannot be recessed, adjusting the polishing area depends on the contact area with the packing. Therefore, it may be difficult to eliminate the difference in the polishing area. The "periphery of the water passage hole" refers to the area surrounding the water passage hole, with a predetermined width from the inner edge of the water passage hole when the fixed surface is viewed in plan. Specifically, it refers to the area at least 0.5 mm wide from the inner edge of the water passage hole.

[0037] In the polishing step, for example, a double-sided grinding machine is used, and polishing is performed simultaneously on both sides of the molded body. This polishing removes the polishing stock on each side. The polishing stock is about 0.05 mm to 0.3 mm.

[0038] After the polishing step, shot blasting or barrel polishing may be carried out as necessary to remove polishing burrs and clean the blast material.

[0039] The resin composition used in the present invention is described below. This resin composition contains a base resin having sliding properties. Examples of base resins that can be used include polyacetal resin, polyimide resin, polyamide resin, fluororesin, polyphenylene sulfide (PPS) resin, and polyether ether ketone (PEEK) resin. PPS resin and PEEK resin are particularly preferred because they have low water absorption, excellent water resistance, and are easy to polish. The resin composition may be composed solely of the base resin (100% base resin), or the base resin may be appropriately blended with a filler such as a solid lubricant or spherical filler, as described below.

[0040] As a filler, it is preferable to blend a solid lubricant such as graphite, molybdenum disulfide, or PTFE resin to improve lubrication properties. PTFE resin is particularly preferable because it has a high lubricity-imparting effect. The solid lubricant can be blended in an amount of 5 to 60 parts by mass, preferably 10 to 45 parts by mass, and more preferably 20 to 30 parts by mass, per 100 parts by mass of the base resin. If the amount is less than 5 parts by mass, it is difficult to achieve an improved lubrication effect, while if it exceeds 60 parts by mass, the polished surface tends to be scratched more, resulting in a high reject rate.

[0041] Furthermore, the inclusion of spherical fillers such as spherical graphite or glass beads as fillers facilitates stable sliding characteristics. This is because there is no anisotropy in the blending direction, so the sliding torque does not change depending on the sliding direction. Furthermore, even if the spherical fillers are ground into hemispheres by polishing and the hemispherical spherical fillers exposed on the sliding surface fall off in a subsequent process such as a barrel tumbler, tap water is retained in the recesses left by the fillers during use, improving the lubrication effect in water. The blending amount of spherical filler is 5 to 30 parts by mass, preferably 5 to 20 parts by mass, per 100 parts by mass of base resin. If the amount is less than 5 parts by mass, the reinforcing effect is difficult to obtain, and if it exceeds 30 parts by mass, low friction properties may be reduced.

[0042] As the spherical filler, glass beads are preferably used. The average particle size of the glass beads is not particularly limited, but is preferably 5 μm to 100 μm, and more preferably 5 μm to 50 μm. The average particle size of the glass beads is, for example, a number-average particle size calculated from the particle size measured by extracting glass beads to be measured from an image obtained by observation with an electron microscope.

[0043] Furthermore, the resin composition preferably does not contain a fibrous filler such as glass fiber or carbon fiber, since the inclusion of a fibrous filler may result in non-uniform surface roughness after polishing.

[0044] Taking these factors into consideration, the resin composition for forming the valve seat is particularly preferably one that contains a PPS resin or PEEK resin as a base resin, 20 to 30 parts by mass of PTFE resin, and 5 to 20 parts by mass of glass beads per 100 parts by mass of the base resin, and does not contain any fibrous filler.Furthermore, it is preferable that the average particle size of the glass beads is 5 μm to 50 μm.

[0045] In addition, in the disc valve device of the present invention, the valve body may be made of a synthetic resin. In this case, the resin compositions used for the valve body and the valve seat may be the same or different. From the viewpoint of simplifying the manufacturing process, it is preferable that the resin compositions used for the valve body and the valve seat be the same resin composition. "Different resin compositions" means that the compositions are different, and includes not only cases where the raw materials constituting the valve body are different, but also cases where the raw materials are the same but with different composition ratios. For example, the base resin of the valve seat may be PPS resin, and the base resin of the valve body may be PEEK resin. [Example]

[0046] The effect of the present invention, that is, the influence of the difference in polishing area between the surfaces that are actually polished on both sides of the object to be polished on the amount of polishing, was confirmed. (1) A molded article having a recess on the surface of the fixed surface side (Example: see FIG. 6) and a molded article having no recess on the surface of the fixed surface side (Comparative Example: see FIG. 7) were injection molded using the same resin composition. The resin composition used contained 100 parts by mass of PPS resin, 25 parts by mass of PTFE resin, and 15 parts by mass of glass beads. In Example 1, recesses as shown in FIG. 6 were formed on the surface of the fixed surface side by additional processing, and the difference between the polished area on the sliding surface side and the polished area on the fixed surface side was set to 20% (the polished area on the fixed surface side was 20% larger than the polished area on the sliding surface side). In Example 2, recesses as shown in FIG. 6 were formed on the surface of the fixed surface side by additional processing, and the difference between the polished area on the sliding surface side and the polished area on the fixed surface side was set to 10% (the polished area on the fixed surface side was 10% larger than the polished area on the sliding surface side). In Comparative Example 1, the fixed surface was left in its as-molded state without additional processing. The difference between the polished area on the sliding surface side and the polished area on the fixed surface side was 70% (the polished area on the fixed surface side was 70% larger than the polished area on the sliding surface side).

[0047] The grinding allowance provided on both sides of the molded bodies of Example 1, Example 2, and Comparative Example 1 was 0.2 mm. The depth of the recesses additionally machined on the fixed surface side of the molded bodies of Example 1 and Example 2 was 0.4 mm. Furthermore, on the fixed surface side of the molded bodies of Example 1 and Example 2, the wall surface at the boundary between the polished surface (flat surface) and the recessed portion was formed with an inclination of 40° relative to the flat surface. The shape of the sliding surface of each valve seat was the same in the examples and comparative example.

[0048] (2) The sliding surface side and the fixed surface side of the obtained molded body were polished with a double-sided polisher to finish the thickness dimension. (3) Next, the ground compact was subjected to shot blasting and barrel polishing to remove grinding burrs and clean the shot material. (4) The polishing amounts of the sliding surface and the fixed surface of the valve seat manufactured through the above steps (1) to (3) were measured. The results are shown in Table 1.

[0049] [Table 1]

[0050] As shown in Table 1, the difference in the amount of polishing between the sliding surface side and the fixed surface side in Examples 1 and 2 was 0.024 mm and 0.010 mm, respectively, which was a level that did not affect the amount of water discharge. On the other hand, the difference in the amount of polishing between the sliding surface side and the fixed surface side in Comparative Example 1 was 0.130 mm, which was a level that affected the amount of water discharge. Therefore, in the case of Comparative Example 1, it is thought that repair of the mold would be necessary. [Industrial Applicability]

[0051] The method for manufacturing a valve seat for a disc valve device of the present invention allows for uniform polishing of both the sliding surface and the fixed surface of the molded body, even when both surfaces are polished simultaneously. This eliminates the need to repair the molding die due to an imbalance in the amount of polishing, and prevents the waste of time and money involved in die repair. [Explanation of symbols]

[0052] 1 Valve body 1a Valve body recess 2 Valve seat 3 Sliding surface 4 Groove 5 Water vent 6 Fixed surface 7 Contact surface 8 Surrounding Surfaces 9 concave 10 Slope 11 Molded body (object to be polished) 12 recess 13 Gasket 14. Human body local cleaning device (disc valve device) 15 Case 16 Drive unit 17 Cleaning water supply device 18. Body local washing nozzle 19 Cleaning water discharge section 20 Drainage section 21 Disc Valve 22 Molded body

Claims

1. A method for manufacturing a synthetic resin valve seat in a disk valve device that switches a fluid flow path and a flow rate by sliding a valve body against a valve seat, comprising: one surface of the valve seat is a sliding surface that slides against the valve body, and the other surface is a fixed surface that is fixed to a housing via a packing; The manufacturing method includes a polishing step of simultaneously polishing both surfaces of an object to be polished to form the sliding surface and the fixing surface, and a molding step of injection-molding a resin composition to obtain a molded body to be the object to be polished, prior to the polishing step; the compact has a recess formed on a surface of the compact on the fixing surface side that is deeper than the polishing allowance of the surface, The recess is an adjustment recess for adjusting the polishing area on the fixed surface side, and by forming the recess, the difference between the polishing area on the sliding surface side of the object to be polished and the polishing area on the fixed surface side is set to within -20% to 20% of the polishing area on the sliding surface side.

2. 2. The method for manufacturing a valve seat according to claim 1, wherein the polishing step is performed by using a double-sided grinding machine.

3. 3. The method for manufacturing a valve seat according to claim 1, wherein in the molding step, the molded body is formed so that the polished area on the fixed surface side is larger than the polished area on the sliding surface side.

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