Lining type butterfly valve and manufacturing method of lining type butterfly valve

Abstract

The objective of the present invention is to provide a lined butterfly valve which has excellent chemical resistance and heat resistance, and with which, even if provided with a large aperture, penetration and permeation of liquid is prevented by ensuring that there is an adequately thick lining layer on a metal core, without providing the metal core with high precision, and a method for manufacturing the same. A valve body 2 in which a metal core 20 is covered with a lining layer 22 is provided with freedom to rotate inside a body 3 by means of a stem 5. The lining layer 22 is provided with front and rear side lining portions 32 provided respectively on the front and rear sides of the metal core, and an outer circumferential lining portion 33 provided on the outer circumferential side of the metal core, wherein: the front and rear side lining portions are provided respectively on the front and rear sides of the metal core, which is assumed not to be warped, in such a way as to have, at least in a position at the outer circumferential edge of the metal core, a thickness T1 obtained by adding a prescribed lining thickness to a thickness that is the same as the maximum warping width assumed on the valve blade side of the metal core; and the thickness of the outer circumferential lining portion, from the outer circumferential edge of the metal core to the distal end seal surface at the outer circumferential edge of the valve body is a thickness T2 obtained by adding the prescribed lining thickness to a prescribed crushed thickness.

Description

[Technical Field]

[0001] The present invention relates to a lined butterfly valve in which a resin lining is applied to the inner peripheral surfaces of a valve body and a valve body, and a method for manufacturing a lined butterfly valve. [Background technology]

[0002] For example, when highly corrosive fluids are flowing in chemical plants or food-related fluid passages, so-called lined butterfly valves, in which the metal core of the valve disc is resin-lined and a resin seat ring is attached to the inner circumferential surface of the valve body, are often used. This type of valve typically uses a fluororesin lining, which has excellent chemical and heat resistance. This fluororesin is applied to a certain thickness to prevent penetration or permeation of special fluids such as chemicals. However, because fluororesin also has poor elasticity, it is necessary to ensure sufficient sealing, particularly near the seal portion between the valve blade side of the valve disc and the valve body side, when the valve is closed, and ultimately to prevent leakage around the entire seal portion on the outer periphery of the valve disc.

[0003] For example, the applicant has filed a patent application for a butterfly valve in Patent Document 1. The valve body of this valve has a disc-shaped core metal with a disc slanting made of fluororesin. This disc slanting has gently inclined surfaces on both sides, which are connected to tapered surfaces at a predetermined angle on the tip of the valve blade. A seal is provided between the tapered surfaces on both sides, which press against the seat liner when the valve is closed. The inclined surfaces, tapered surfaces, and seal are all formed from the core metal with approximately the same thickness, and when the valve is closed, they exert a high sealing surface pressure to prevent leakage.

[0004] On the other hand, the butterfly valve disc in Patent Document 2 has a lining layer covering the outside of a reinforcing core metal, and a two-stage seal section with different radii of curvature formed on the outer periphery of this lining layer, consisting of a low-pressure seal section with a small radius of curvature and a medium- to high-pressure seal section with a large radius of curvature. This seal section allows only the low-pressure seal section to be pressed against the seat ring with little biting when under low pressure, and the low-pressure seal section and the medium- to high-pressure seal section to be pressed against the seat ring with large biting when under high pressure, thereby reducing the burden on the coating material.

[0005] A lining mold is generally used to apply a resin lining to the core of the lining type butterfly valves of Patent Documents 1 and 2. When lining is performed using a lining mold, the core is usually supported horizontally in the mold and the lining material is poured into the cavity in this state, thereby lining the entire surface of the core, including the front and back surfaces, to produce the valve body. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6495243 [Patent Document 2] Patent No. 3086783 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when the diameter of the lining-type butterfly valves described in Patent Documents 1 and 2 is increased, the valve disc core also becomes larger, resulting in increased weight. This increases the likelihood of warping, especially around the valve blades, during casting of the core. When lining the core in a lining mold, the core is likely to bend downward due to its own weight near the valve blades. During lining molding, the core is placed inside a resin mold and then resin is supplied and molded, resulting in a warped or flexed core placed inside a resin lining of a fixed outer shape. This makes it difficult to apply a lining evenly to both sides of the core. This can lead to insufficient lining thickness on one side of the core, particularly near the valve blades, resulting in the core being exposed to the surface, or to an excessive lining thickness on the other side. In these cases, the insufficient lining layer can allow fluid to penetrate or permeate during use.

[0008] In the valve bodies of these valves, the inclined or tapered surfaces on the front and back sides of the core bar and the seal portion for pressing the seat liner against the core bar are provided with approximately the same thickness. To achieve these uniform thicknesses, the core bar must be formed with high precision. However, when coating the surface of the core bar with a resin lining layer, variations in the resin molding are likely to occur, making it particularly difficult to form a seal with the specified width near the outer periphery of the core bar. For this reason, the outer periphery of the core bar is often formed with a peripheral seal surface that extends from the front and back sides. In this case, in order to achieve a uniform, specified width for the peripheral seal surface, it may be necessary to carefully design the shape of the core bar or to precisely cut off the excess extension of the peripheral seal area while taking into account the crushing allowance of the peripheral seal surface.

[0009] For these reasons, there has been a demand for a lining type butterfly valve that can easily form a lining thick enough to prevent the penetration or permeation of chemicals, etc., without the need to install a highly accurate core bar, even when installing a lining type butterfly valve with a large diameter, and that is equipped with a valve body that ensures sealing performance around the entire periphery when the valve is closed.

[0010] The present invention was developed to solve the problems of the past, and its purpose is to provide a lining-type butterfly valve with excellent chemical and heat resistance, which, even when installed in a large diameter, ensures a lining layer of sufficient thickness relative to the core metal to prevent fluid penetration or permeation, without the need to install the core metal of the valve body with high precision, and a method for manufacturing such a lining-type butterfly valve. [Means for solving the problem]

[0011] In order to achieve the above object, the invention of claim 1 is a lining type butterfly valve in which a valve disc, which is made of a core bar covered with a lining layer, is rotatably mounted within a body by a stem, the lining layer comprising front and back lining portions respectively provided on the front and back sides of the core bar, and a peripheral lining portion provided on the outer periphery of the core bar, the front and back lining portions being provided on the front and back sides of the core bar assuming no warping, at least at the outer periphery of the core bar, with a thickness equal to the sum of a predetermined lining thickness and a thickness equal to the maximum warping width expected on the valve blade side of the core bar, and the outer periphery lining portion having a thickness from the outer periphery of the core bar to the tip seal surface of the outer periphery of the valve disc being the sum of the predetermined lining thickness and a predetermined crushing thickness.

[0012] The invention of claim 2 is a lining type butterfly valve in which a convex portion that protrudes toward the outer periphery of the valve body is formed in a substantially annular shape on the outer periphery of the valve body on the outer lining portion, and the end face of the convex portion on the outer periphery of the valve body forms a tip seal surface with a predetermined seal width.

[0013] The invention of claim 3 is a lining type butterfly valve in which the core has an outer peripheral side portion at its outermost periphery, and this outer peripheral side portion has a width that allows it to face the center in the thickness direction of the convex portion provided on the outer peripheral lining portion even if the core warps to the maximum expected warp width on the valve blade side of the core.

[0014] The invention according to claim 4 is a lining type butterfly valve in which each side surface of the protrusion on the tip seal surface is formed as an inclined surface at an angle of 10° or less with respect to the pressure sealing direction of the tip seal surface.

[0015] The invention of claim 5 is a lining type butterfly valve in which a pair of washers facing each other in the direction of stem insertion are attached inside the mounting portion into which the stem is inserted, and this pair of washers is made up of a combination of concave and convex shapes that ensures that the surface pressure applied to the boss portion formed on the valve body from the stem side is approximately uniform even when there is a misalignment or tilt between the stem and the valve body.

[0016] The invention of claim 6 is a lining type butterfly valve in which the washer comprises a convex washer with a convex spherical surface and a concave washer with a concave spherical surface with which the convex spherical surface makes surface contact, and the convex washer and the concave washer are mounted in a state where they are pressed in opposing directions by the elastic force of a spring mounted inside the mounting portion.

[0017] The invention of claim 7 is a lining type butterfly valve in which a valve disc, which is made of a core bar covered with a lining layer, is rotatably mounted within the body by a stem, the lining layer comprising front and back lining portions respectively provided on the front and back sides of the core bar, and a peripheral lining portion provided on the outer periphery of the core bar, the front and back lining portions having at least a predetermined lining thickness on the front and back sides of the core bar, and at least at the outer periphery end position of the core bar, the total thickness of the front and back sides is twice the predetermined lining thickness plus a thickness equal to the maximum warp width expected on the valve blade side of the core bar, and the outer periphery lining portion has a thickness from the outer periphery end of the core bar to the tip seal surface of the outer periphery end of the valve disc which is the thickness obtained by adding the predetermined lining thickness and a predetermined crushing thickness.

[0018] The invention of claim 8 is a method for manufacturing a lining type butterfly valve according to any one of claims 1 to 7 above, comprising inserting stems or stem jigs into stem insertion holes provided in the core bar at positions opposite the valve wing portions of the core bar to fix the core bar and the stem or stem jig to each other, placing the core bar in a molding space of a mold for molding a lining layer, and holding the upper and lower stems or the upper and lower stem jigs to fix the core bar so that it does not move within the molding space, and then introducing a material for forming a lining layer into the molding space to form a lining layer on the surface of the core bar. [Effects of the Invention]

[0019] According to the invention of claim 1, in a lining-type butterfly valve with excellent chemical resistance and heat resistance, the front and back lining portions of the disc are provided at least at the outer peripheral edge of the core bar, on both the front and back sides of the core bar (assuming no warping occurs), with a thickness that is the sum of a predetermined lining thickness and a thickness equal to the maximum expected warp width on the blade side of the core bar. Therefore, even if the core bar actually warps, a lining portion with at least the predetermined lining thickness is ensured on the front and back sides of the disc. Meanwhile, the outer peripheral lining portion has a thickness that is the sum of the predetermined lining thickness and a lining thickness that is a predetermined crushed thickness, so that a lining portion with at least the predetermined lining thickness is also ensured on the outer peripheral side of the disc. Therefore, even when provided on a large diameter, a lining layer of sufficient thickness can be ensured relative to the core bar to prevent fluid penetration or permeation. This allows the front and back lining portions and the outer peripheral lining portion to be formed into the desired shape without having to finely set the shape of the core metal, and in particular, the outer peripheral side can be easily formed to the desired thickness and width, and since this outer peripheral side has the thickness and sealing width necessary to ensure sealing performance, leakage from the outer peripheral side of the valve body can be prevented when the valve is closed, and sealing performance can be achieved around the entire circumference of the valve body.

[0020] According to the invention of claim 2, a convex portion is formed on the outer peripheral lining portion, and the outer peripheral end face of this convex portion becomes a tip seal surface having a predetermined seal width. This makes it possible to form the outer peripheral lining portion to the required thickness regardless of the outer diameter or thickness of the core bar, while providing this convex portion with the predetermined seal width required for sealing. Therefore, even when the valve diameter is increased, it is possible to form the minimum necessary outer peripheral seal portion, and it is also easy to process.

[0021] According to the invention of claim 3, in order for the convex portions of the peripheral lining portion to exhibit good sealing properties, it is preferable that the outer peripheral portion of the core bar acts as a support, and for this purpose, it is preferable that the outer peripheral side surface of the core bar faces at least the center of the convex portions even if the core bar warps. In particular, since the width is set to be such that it can face the center portion in the thickness direction of the convex portions provided on the peripheral lining portion, even if the core bar warps, the convex portions and the outer peripheral side surface of the core bar can be reliably faced to each other, and the sealing properties provided by the convex portions can be ensured.

[0022] According to the invention of claim 4, each side surface is formed with an inclined surface at an angle of 10° or less relative to the pressure sealing direction of the tip seal surface, which reduces variations in seal width after lining molding and makes it easier to form a peripheral seal portion with a uniform seal width around the outer periphery of the valve disc. When the valve is closed and sealing, the peripheral seal portion exerts a constant sealing surface pressure over the entire outer periphery of the valve disc, reliably preventing fluid leakage.

[0023] According to the invention of claim 5, even if the valve body and the stem side tilt or move when fluid pressure is applied, the pair of washers maintains the attached state between the valve body and the stem side, maintaining smooth rotational operability. In this case, the washers are made of a combination of concave and convex shapes, and the same surface pressure is applied from the stem side to the boss part of the valve body as before tilt or movement occurred, ensuring sealing between the boss part and the body side, and reliably preventing leakage even if the valve body side and the stem side tilt or move.

[0024] According to the invention of claim 6, even if the convex washer and the concave washer are tilted or misaligned relative to each other, the spring force brings the convex spherical surface and the concave spherical surface into close contact, thereby applying uniform surface pressure over a wide range of contact positions, thereby achieving excellent sealing between the boss portion and the body side.

[0025] According to claim 7, in a lining-type butterfly valve with excellent chemical resistance and heat resistance, the front and back lining portions of the disc are provided at least at the outer circumferential edge of the core bar, on both the front and back sides of the core bar (assuming no warping occurs), with a thickness equal to the sum of a predetermined lining thickness and a thickness equal to the maximum expected warpage width on the blade side of the core bar. Therefore, even if the core bar actually warps, a lining portion with at least the predetermined lining thickness is ensured on the front and back sides of the disc. Meanwhile, the outer circumferential lining portion has a thickness equal to the sum of the predetermined lining thickness and a lining thickness equal to the predetermined crushing thickness, so that a lining portion with at least the predetermined lining thickness is also ensured on the outer circumferential side of the disc. Therefore, even when provided on a large diameter, a lining layer of sufficient thickness can be ensured relative to the core bar to prevent fluid penetration or permeation. This allows the front and back lining portions and the outer peripheral lining portion to be formed into the desired shape without having to finely set the shape of the core metal, and in particular, the outer peripheral side can be easily formed to the desired thickness and width, and since this outer peripheral side has the thickness and sealing width necessary to ensure sealing performance, leakage from the outer peripheral side of the valve body can be prevented when the valve is closed, and sealing performance can be achieved around the entire circumference of the valve body.

[0026] According to the invention of claim 8, a stem or stem jig is inserted into the core bar in advance and fixed, and by holding this stem or stem jig, the core bar is fixed within the molding space of the mold (metal mold) for molding the lining layer so that the core bar does not move, and the lining layer material is introduced into this molding space to form the lining layer.This allows the core bar to be positioned in an accurate position within the lining layer, the outer shape of which is determined in advance by the mold (metal mold), so that a lining layer with the thickness required to prevent fluid penetration can be reliably formed even if the core bar warps. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a central vertical cross-sectional view showing an embodiment of a lining type butterfly valve of the present invention. FIG. [Figure 2] 1(a) is a partially cutaway perspective view of the valve body, and FIG. 1(b) is a central cross-sectional view of the valve body. [Figure 3] FIG. 3 is an enlarged cross-sectional view of part A in FIG. [Figure 4] FIG. 2 is a cross-sectional view of a valve body with a portion thereof omitted. [Figure 5] FIG. 2 is a partially enlarged cross-sectional view showing the vicinity of the boss surface of FIG. 1. [Figure 6] FIG. 2 is a schematic explanatory view showing a molding die for a butterfly valve. DETAILED DESCRIPTION OF THE INVENTION

[0028] An embodiment of a lining type butterfly valve according to the present invention will be described in detail below with reference to the drawings. Figure 1 is a central vertical cross-sectional view of an embodiment of a lining type butterfly valve according to the present invention, Figures 2(a) and 2(b) show the valve body, and Figure 3 is an enlarged cross-sectional view of part A in Figure 2(b).

[0029] In the figure, the lining type butterfly valve (hereinafter referred to as valve body 1) is provided with a large diameter, for example, a nominal diameter of about 350A to 600A, and is used as part of pipelines in semiconductor manufacturing plants, food-related plants, etc. Valve body 1 comprises a valve element 2, a substantially cylindrical body 3, a seat liner 4, and a stem 5, with this stem 5 consisting of an upper stem 5a and a lower stem 5b.

[0030] The body 3 is molded from cast iron, such as ductile cast iron, and is provided in a form that can be separated into upper and lower bodies, 3a and 3b, which can be fixed together with bolts (not shown). The body 3 is provided with a flow path port 10 and a flange 11, and the inner peripheral side of the body 3, including these, is covered with a seat liner 4. A mounting portion 12 is formed on the mounting side of the stem 5 of the upper body 3a and the lower body 3b, and a mounting hole 13 is formed inside this mounting portion 12, into which the upper stem 5a and the lower stem 5b are respectively attached. A polygonal angular portion 5c is formed at the bottom of the upper stem 5a.

[0031] The valve body 2 has a roughly circular disk-shaped core 20 formed of a metal material such as a stainless steel alloy at its center, and this core 20 is covered with a lining layer (lining portion) 22. This lining portion 22 has front and back lining portions 32 provided on the front and back sides of the core 20, respectively, and an outer periphery lining portion 33 provided on the outer periphery of the core 20.

[0032] Stem insertion holes 23 are formed on the top and bottom sides of the valve body 2, and in particular, the top-side stem insertion hole 23 is formed with a square hole 24 into which the square portion 5c of the stem 5 can fit. The upper stem 5a is inserted into the top-side stem insertion hole 23 so that the square portion 5c fits into the square hole 24, and the lower stem 5b is inserted into the bottom-side stem insertion hole 23. As a result, the valve body 2 is mounted on the upper stem 5a and lower stem 5b and is installed inside the body 3, and the flow path inside the body can be opened and closed by rotating the upper stem 5a.

[0033] The lining portion (lining layer) 22 is made of a resin material such as a fluororesin such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), and is provided with boss portions 30 and shaft tube lining portions on the upper and lower sides (top and bottom sides) in addition to the above-mentioned front and back side lining portions 32 and peripheral lining portion 33. The lining portion 22 is integrally covered on the outer periphery of the front and back sides of the core 20 by communication portions 21 formed at appropriate positions on the core 20, and is formed in a state where it is prevented from coming off the core 20.

[0034] The sealing portion of the lining portion 22 of the valve disc 2 with the seat liner 4 consists of a boss portion 30 near the top and bottom sides and a valve wing portion 31 which is the portion other than the boss portion 30, and the boss portion 30 ensures sealing on the top and bottom sides with the seat liner 4 from the valve open to the valve closed state, and the valve wing portion 31 ensures sealing on the valve wing side with the seat liner 4 in the valve closed state. In this way, when the valve is closed, the boss portion 30 and the valve wing portion 31 provide sealing with the seat liner 4 over the entire inner peripheral surface.

[0035] Here, when molding the lining portion 22, as the diameter of the valve body 1 (core metal 20) increases, more warping is likely to occur on the valve blade side of the core metal 20 around the rotation axis during casting, and when the subsequent lining process is performed, the area near the valve blade side of the core metal 20 is likely to bend downward and deform due to its own weight.

[0036] In contrast, in Figures 2 and 3, the front and back lining portions 32 are provided on the front and back sides of the core 20, assuming no warpage, to have a thickness T1 at least at the outer periphery of the core 20, which is the sum of a predetermined lining thickness and a thickness equal to the maximum warpage width expected on the valve blade side of the core 20. The front and back lining portions 32 reliably cover the front and back sides of the core 20, even on the valve blade side. Figures 2 and 3 illustrate an ideal state in which the core 20 is not warped. In reality, this state does not occur, and the core 20 may warp. The form in which the core 20 warps will be described later with reference to Figure 4. In this example, the front and back lining portions 32 are provided on the front and back sides of the core 20 with a uniform thickness, but this is not necessarily limited to this. Since warpage of the core 20 tends to increase toward the valve blade side, the thickness may accordingly increase toward the valve blade side.

[0037] Specifically, in the case of a large-diameter butterfly valve with a nominal diameter of about 350A to 600A as in this example, it is desirable that the predetermined lining thickness on each of the front and back sides of the core 20 be at least 3 mm, and in this example, it is set to about 3 mm. On the other hand, the thickness equivalent to the maximum warp width expected on the valve blade side of the core 20 is set to about 2 mm on the front and back sides of the core 20, assuming that the maximum warp width around the rotation axis of the core 20 near the valve blade is 2 mm. As a result, the front and back lining portions 32 are set to a thickness T1 of about 5 mm, which is the sum of the predetermined lining thickness of 3 mm and the thickness of 2 mm, which is the same as the maximum warp width expected on the valve blade side of the core 20, on each of the front and back sides of the core 20 assuming no warp.

[0038] On the other hand, the peripheral lining portion 33 is provided on the outer peripheral side of the core bar 20 with a thickness T2 from the outer peripheral end of the core bar 20 to the tip seal surface 41 of the outer peripheral end of the valve body 2, and this thickness T2 consists of a predetermined lining thickness on the outer peripheral side of the core bar 20 plus a predetermined crushing thickness, and the outer peripheral side of the core bar 20 is covered by this peripheral lining portion 33.

[0039] Specifically, the predetermined lining thickness on the outer periphery of the valve body 2 is set to about 3 mm, and a predetermined crushing thickness is added to this predetermined lining thickness to form the outer periphery lining portion 33. In this example, the predetermined crushing thickness is set to about 1 mm, and the predetermined lining thickness and the predetermined crushing thickness ensure a thickness required for pressing the outer periphery of the valve body 2 against the seat liner 4 and a crushing allowance.

[0040] Here, the "predetermined lining thickness" refers to the minimum thickness of the lining layer required to prevent fluids that may come into contact with the valve disc 2 from penetrating to the core metal 20, and varies depending on the material of the lining layer and the type of fluid. Note that this "minimum thickness" does not need to be a value proven by theory or empirical evidence, but rather may be a conventional value that is the minimum required to prevent fluid penetration based on the experience of a person skilled in the art. Furthermore, the "predetermined crushing thickness" refers to the amount of irreversible crushing that can occur when the sealing portion of the valve disc 2 repeatedly comes into contact with and is crushed by the seat liner 4 when the valve disc 2 is opened and closed. This "predetermined crushing thickness" can be set taking into consideration the size of the valve disc 2, the material of the lining portion 22, the amount of crushing of the sealing portion, etc.

[0041] Furthermore, "the maximum expected warpage width near the valve wing of the core bar 20" refers to the deviation width from the design value from the end of the core bar 20 when the maximum warpage occurs within the expected range, with respect to warpage centered near the valve wing that may occur during casting of the core bar 20, etc.

[0042] A convex portion (annular convex portion 40) is provided at a predetermined height on the sealing side of the outer peripheral lining portion 33, and this annular convex portion 40 protrudes toward the outer periphery of the valve body 2 and is formed in a substantially annular shape continuous with the outer periphery of the valve body 2, and a tip seal surface 41 is formed on the end surface of the outer periphery of the valve body 2 at this annular convex portion 40. The tip seal surface 41 is provided with a predetermined seal width W.

[0043] In this case, the annular protrusion 40 is set to a predetermined height (predetermined crushed thickness) that can maintain sufficient sealing performance, taking into consideration irreversible leakage that may occur as a result of contact between the seat liner 4 and the valve seat. As a result, in the peripheral lining portion 33, a layer having a predetermined lining thickness is formed on the outer periphery of the core bar 20, and the annular protrusion 40 having a predetermined crushed thickness is formed on the outer periphery of that layer. With this structure, it is possible to reliably ensure the predetermined lining thickness on the outer periphery of the core bar 20, while also forming the minimum necessary peripheral seal portion.

[0044] The predetermined seal width W means a large width required for obtaining sufficient sealing performance from the leading end seal surface 41, which is the main sealing portion between the annular protrusion 40 and the seat liner 4. This predetermined seal width W can also be set to a value conventionally known to those skilled in the art.

[0045] In this example, the annular convex portion 40 is formed to a height of approximately 1 mm with a predetermined seal width W of approximately 3 mm, and the entire outer peripheral lining portion 33 is formed to a thickness of approximately 4 mm, which is the sum of the predetermined lining thickness (3 mm) and the predetermined crushed thickness (1 mm).

[0046] 3, side surfaces 42 are provided on both sides (top and bottom in the figure) of the annular protrusion 40 toward the tip seal surface 41, and each side surface 42 is formed by an inclined surface that is inclined with respect to the pressure sealing direction of the tip seal surface 41. The angle θ of the tip seal surface 41 with respect to the pressure sealing direction is set to 10° or less.

[0047] That is, when forming the lining layer (lining portion 22) on the core bar 20, the annular protrusion 40 can be formed much higher than the intended height (larger in the right direction in FIG. 3) during molding of the lining portion 22, and then cut at a position of the height required for the annular protrusion 40 after molding. In this case, if the angle θ is 10° or less, the side surfaces 42 of the annular protrusion before cutting become nearly parallel to each other, and the change in the width between the side surfaces 42 due to the cutting position can be reduced, so that the required seal width W can be formed at the tip seal surface 41.

[0048] In Figure 3, the thickness of the front and back lining portions 32 (the thickness from the surface of the core 20 to the outer surface of the lining portion 22) is greater than the thickness of the peripheral lining portion 33. However, it is more preferable that the thickness of the lining portion from the front and back lining portions 32 to the annular convex portion 40 be uniform. If there is a difference in the thickness of the lining portion, differential shrinkage occurs during molding of the lining portion, and stress may concentrate in the thinnest part, making it prone to fracture. In particular, the base of the annular convex portion 40 is prone to stress concentration. However, by making the thickness uniform from the front and back lining portions 32 through the peripheral lining portion 33 to the annular convex portion 40, stress concentration due to differences in thickness is less likely to occur, making it easier to prevent fracture of the lining portion 22.

[0049] An annular C-chamfered surface 45 is formed between the tip seal surface 41 and both side surface portions 42, and the provision of the C-chamfered surface 45 (C-chamfer) prevents excessive force from being applied to a portion of the annular protrusion 40 when the annular protrusion 40 comes into contact with the seat liner 4. Furthermore, by appropriately setting the size and angle of the C-chamfered surface 45, the seal width W of the tip seal surface 41 can be set to any size.

[0050] By forming the above-mentioned lining portion 22 on the valve body 2, even when the core metal 20 is warped or bent, the thickness T1 of the front and back lining portions 32 and the thickness T2 and seal width W of the peripheral lining portion 33 are of a size that reliably exhibits sealing properties when the valve is closed, and moreover, the thickness of the peripheral lining portion 33 at this time is kept to the minimum necessary thickness to maintain sealing properties.

[0051] Hereinafter, a case where warpage or deflection occurs in the core bar 20 will be described with reference to Fig. 4. In Fig. 4, a cross-sectional view of the valve body is shown with a portion omitted, in which Fig. 4(a) shows the state where the core bar of this embodiment is not warped, Fig. 4(b) shows the state where warpage occurs in the core bar of this embodiment, and Fig. 4(c) shows a comparative example.

[0052] 4(a) shows a state in which the front and back side lining portions 32 are formed with a uniform thickness on the front and back sides of the core bar 20, and the peripheral lining portion 33 is formed with a uniform thickness on the outer periphery side. In this case, the front and back side lining portions 32 and the peripheral lining portion 33 are ensured to have a sufficient thickness.

[0053] As shown in Figure 4(b), even if upward warping occurs, the front and back side lining portions 32 have a thickness that is the specified lining thickness plus the thickness of the maximum warping width of the core bar 20 that is assumed in advance.Therefore, at least the specified lining thickness is ensured in the front and back side lining portions 32 on the upper surface side of the core bar 20, and at least the specified lining thickness is also ensured in the outer peripheral lining portion 33, which prevents fluid penetration and ensures sealing for the seat liner 4 when the valve is closed.

[0054] In the case of the lining portion 25 provided in the comparative example of Figure 4(c), the front and back surfaces of the core bar 20 are not provided with a lining thickness equal to the maximum warp width expected on the valve blade side, and the lining thickness of the specified seal thickness is not provided on the outer periphery of the core bar 20. In this case, the specified lining thickness is insufficient in the front and back lining portions on the upper surface side, and particularly in this example, since the core bar 20 is exposed from the top of the front and back lining portions 25, it is no longer possible to prevent fluid penetration and the thickness of the outer periphery lining portion is insufficient, making it difficult to ensure sealing when the valve is closed.

[0055] When the valve element 2 of this embodiment is applied to a butterfly valve, the annular protrusion 40 is crushed between the annular protrusion 40 and the sealing surface on the body side, thereby achieving a seal. In this case, to obtain a good seal, it is preferable that the outer peripheral side surface 20a of the core 20 is reliably positioned opposite the annular protrusion 40. This ensures that the annular protrusion 40 is supported by the core 20. Furthermore, as described above, the larger the diameter, the more likely the core 20 is to warp or bend. However, if the warping or bending of the core 20 causes the outer peripheral side surface 20a of the core 20 to shift from the annular protrusion 40, sufficient sealing may not be obtained.

[0056] Therefore, in this example, the outer peripheral side surface portion 20a of the core 20 has a width that allows it to face the center in the thickness direction of the annular protrusion 40 even if the core 20 warps to the maximum expected warp width on the valve wing side. For example, if it is expected that the core 20 will warp by a maximum of about 2 mm, it is preferable that the width of the outer peripheral side surface portion 20a be greater than 4 mm. Even if the core 20 warps by a maximum of 2 mm, the center of the annular protrusion 40 is located in a position that faces the outer peripheral side surface portion 20a of the core 20, so that a deterioration in sealing performance due to warping or deflection of the core 20 can be prevented.

[0057] The valve body 2 having the lining portion 22 on the surface of the core metal 20 can be manufactured, for example, as follows: Figure 6 is a schematic explanatory diagram showing a molding die for a butterfly valve, in which a stem or stem jig (not shown) is inserted into the stem insertion hole and held by the lower die.

[0058] First, prepare the core bar 20, and insert the stem 5 or upper and lower stem jigs (not shown) of the same shape as the stem into the stem insertion holes 23 of the upper stem 5a and lower stem 5b of this core bar 20, respectively, to fix the core bar 20 (see Figure 1, etc. for the stem insertion holes 23 of the core bar 20).

[0059] Next, while the core bar 20 is laid substantially horizontally, the core bar 20 is placed in a molding area D for molding a predetermined resin in the lower mold 100b of the molding die (mold) 100 while holding the upper and lower stems 5a, 5b or the upper and lower stem jig (hereinafter referred to as the stem jig). At this time, the upper and lower stems 5a, 5b or the stem jig are fixed with a holding member or the like so that the core bar 20 does not move in the rotational direction. Here, the holding member may be fixed by any method as long as it does not rotate the core bar 20. For example, it may be a holding member that fixes the upper and lower stems 5a, 5b or the stem jig by sandwiching them from both sides, or it may be a holding member that is integrated with the mold by providing a stem holding recess or the like in the mold.

[0060] Next, the upper mold 100a is placed over the lower mold 100b, and the mold 100 is fixed with a fixing member (not shown) or the like. At this time, a space S for forming a lining portion 22 around the core metal 20 is provided between the upper mold 100a, the lower mold 100b, and the area where the core metal 20 is disposed.

[0061] In Figure 6, after filling the pot 200 with resin material 300, the resin material 300 is extruded by the extrusion member 201 and injected (introduced) into the space S through the injection port 100c provided in the mold 100, and the resin material 300 is hardened to form a lining portion 22 that covers the core wire 20. The mold 100 is also provided with an annular step 100d, and the resin material 300 can be pressed into this annular step 100d to form an annular protrusion 40 on the outer periphery of the lining layer 22 of the core 20.

[0062] After the resin material has sufficiently hardened, the core bar 20 on which the lining layer has been formed is removed from the mold 100, and the unnecessary portion is cut off by the annular protrusion 40 formed on the outer periphery of the valve body, thereby manufacturing a lining-type butterfly valve equipped with a tip seal surface 41 having a predetermined seal width W.

[0063] Furthermore, in the above-described method, by fixing and holding the upper and lower stems 5a, 5b or stem jigs, etc., the core wire 20 can be positioned accurately within the molding area D in the mold 100, thereby preventing distortion or misalignment when forming the lining layer and making it easier to form the lining portion 22 of the required thickness.

[0064] In this example, particularly in the case of large-diameter butterfly valves, warping and bending of the core 20 is more likely to occur than in small-diameter butterfly valves, and so the shape of the lining portion 22 is made to satisfy predetermined conditions so that the lining portion 22 can be formed to the required thickness even if warping or bending occurs in the core, and it is particularly important to accurately align the position of the core 20 within the molding area in the mold when molding this lining portion 22. In the above-mentioned method, the upper and lower stems 5a, 5b or a stem jig fixed to the core 20 are fixed and held, making it possible to accurately align the core 20 within the mold 100.

[0065] In Figure 5, the boss portions 30 on the top and bottom sides of the valve body are arranged in a pressure-sealed state against boss surfaces 4d formed on the top and bottom sides of the seat liner 4 attached to the body 3, and these boss portions 30 and boss surfaces 4d ensure sealing in the boss portion from the valve open to the valve closed state.

[0066] 1, the seat liner 4 is made of the same resin material as the lining portion 22 of the valve body 2, such as PFA, and has a predetermined thickness, and as described above, is provided to cover the inner periphery of the body 3 to provide high corrosion resistance and heat resistance. The seat liner 4 has an annular portion 4a attached to the inner periphery of the body 3 and flange portions 4b protruding from the outer periphery of both ends of the annular portion 4a. At the attachment positions of the upper and lower stems 5a, 5b of the annular portion 4a, cylindrical lining portions 4c, 4c are integrally formed so as to protrude in the attachment direction of the stem 5, and the upper and lower stems 5a, 5b are attached to these cylindrical lining portions 4c.

[0067] A washer 51, a ring body 52, a sealing bush 53, an O-ring 54, and a cylindrical bearing 55 are provided inside the mounting portions 12 into which the above-mentioned upper and lower stems of the body 3 are inserted, and furthermore, a spring 56 consisting of a coil spring is attached to the upper and lower sides of each mounting portion 12. The valve disc 2 is rotatably mounted inside the body 3 with the upper and lower sides covered by the lining portions 22 and axially sealed by the mounting portions 12.

[0068] A pair of washers 51 facing each other is attached to each of the upper and lower mounting portions 12 in the insertion direction of the upper stem 5a and the lower stem 5b. This pair of washers 51 has a combination of concave and convex shapes that allows the surface pressure applied to the boss portion 30 of the valve body 2 from the stem 5 (upper and lower stems 5a, 5b) side to be approximately the same as when there is no misalignment or tilt between the stem 5 and the valve body 2.

[0069] Specifically, washer 51 is made up of a convex washer 60 and a concave washer 61. Convex washer 60 has a convex spherical surface 62 on one side, and concave washer 61 has a concave spherical surface 63 on one side with which convex spherical surface 62 makes surface contact, and these convex washer 60 and concave washer 61 are mounted in a state where they are pressed in opposing directions by the elastic force of spring 56 mounted inside mounting part 12. The mounting structure for this washer 51 is provided so that it is mounted symmetrically on the upper and lower mounting parts 12.

[0070] When fluid pressure is applied to the valve disc 2, it moves in that direction, which is thought to cause the stem 5 (upper stem 5a, lower stem 5b) to tilt around the center position of the upper and lower bearings 55. Therefore, from the perspective of sliding on a spherical surface along the tilt of the stem 5, the center position of the upper and lower bearings 55 is set as the center position of the sphere, and the virtual spherical surface formed at the position of the washer 51 is made to coincide with the opposing spherical surfaces of the convex washer 60 and the concave washer 61.

[0071] Since the stem 5 will be tilted at a maximum by the amount of space around its end portion with the valve body 2, the convex spherical surface 62 and the concave spherical surface 63 are formed in a shape that can accommodate this tilt. For example, if the stem 5 is tilted at an angle of 1° at most, the convex spherical surface 62 and the concave spherical surface 63 will be formed in a spherical shape that can accommodate a tilt of an angle of 1° at most. In this example, the radius of the imaginary sphere is set to 110 mm, and this radius forms the convex spherical surface 62 and the concave spherical surface 63. As a result, even if the stem 5 (upper stem 5a, lower stem 5b) is tilted and a misalignment or tilt occurs between the stem 5 and the valve body 2, the surface pressure due to the tilt of the bearing 55 is transmitted uniformly from the convex spherical surface 62 to the concave spherical surface 63.

[0072] It is desirable that the convex spherical surface 62 and the concave spherical surface 63 are formed in a manner that allows them to slide easily against each other, and in this embodiment, the inner and outer diameters of the convex washer 60 are set slightly smaller than the inner and outer diameters of the concave washer 61, and appropriate spaces are provided on the inner and outer peripheries of the convex washer 60 (not shown). This allows the convex washer 60 to easily swing circumferentially relative to the concave washer 61.

[0073] The bearing 55 is disposed between the spring 56 and the ring body 52, and the upper stem 5a and the lower stem 5b are supported by the bearing 55 in a rotatable and centered state near the O-ring 54, respectively.

[0074] The ring body 52 is made of stainless steel and has a cylindrical shape that allows it to apply strong pressure from above to a position near the outer periphery of the boss portion 30 of the valve body 2, and this ring body 52 allows the elastic force of the spring 56 to be transmitted to the valve body 2 side through the bearing 55 while allowing the valve body 2 to rotate.

[0075] A bearing member 70 that rotatably supports the upper stem 5a is positioned on the upper side of the upper body 3a and is engaged with a retaining ring 71, and this bearing member 70 holds the spring 56 in a state in which it can be elastically pushed downward.

[0076] On the other hand, a bearing member 72 is arranged on the lower body 3b side while being locked by a retaining ring 71, and a bearing member 73 that rotatably supports the lower stem 5b is placed on top of this bearing member 72, and the spring 56 is held in a state in which it can be resiliently pushed upward through this bearing member 73. The upper and lower springs 56, 56 are resiliently pushed toward the valve body 2 by the bearing members 70, 73 and bearing member 72. Dust-proof and waterproof O-rings 74, 74 are attached to the inner and outer peripheries of the bearing member 70 and bearing member 72, respectively.

[0077] The sealing bush 53 is molded from a resin material such as carbon fiber-reinforced PTFE (polytetrafluoroethylene), and is provided as a sealing portion between the ring body 52 and the lining part 22 and the seat liner 4. An annular flange 53a is formed on the lower side of the sealing bush 53 so as to be bent in the outer circumferential direction. The flange 53a is provided so that the end face side of the ring body 52 can abut against it, and thereby the ring body 52 presses against the seat liner 4 through the flange 53a.

[0078] With the above-described configuration, in the valve body 1 of FIG. 1, the spring force of the spring 56 provided in the mounting hole 13 of the body 3 presses the seat liners 4 located on the top and bottom boss portions 30 of the valve body 2 through the ring body 52, thereby ensuring sealing at both the top and bottom portions.

[0079] In the above embodiment, the front and back lining portions 32 and the peripheral lining portion 33 may have additional thickness added to them in accordance with the warping of the core bar 20, or may have a thickness added to the entire surface of the core bar 20 corresponding to the maximum expected warping width.

[0080] The washer 51 can be placed at any position on the mounting portion 12, and as long as the convex washer and the concave washer can slide relative to each other, they can be tapered rather than spherical, or their vertical positional relationship can be reversed. Also, these pairs of washers can be placed in a non-oscillating manner. Although a coil spring is used as the spring 56, the spring is not limited to this, and for example, a disc spring or the like may be used.

[0081] Next, the operation of the above-described embodiment of the lining type butterfly valve of the present invention will be described. In Figures 1 to 3, the valve body 1 is provided with a lining portion 22 that includes front and back lining portions 32 and an outer peripheral lining portion 33, and this lining portion 22 covers the core metal 20. Therefore, even when the valve body 1 is enlarged to a nominal diameter of approximately 350A to 600A, chemical resistance and heat resistance can be maintained.

[0082] In this case, the front and back lining portions 32 are set to a thickness T1 of 5 mm on each of the front and back sides of the core bar 20, which is the sum of the specified lining thickness of 3 mm and a thickness of 2 mm, which is the same as the maximum expected warp width on the valve wing side of the core bar 20.Therefore, even if the core bar 20 warps during casting or the valve wing side bends downward and deforms due to its own weight when lining using the lining molding mold of Figure 6, the required lining thickness can be applied to the front and back sides of the core bar 20, and the lining portions 32 can reliably prevent fluid penetration and permeation, ensuring chemical resistance and heat resistance.

[0083] On the other hand, the outer peripheral lining portion 33 is set to a thickness T2 of 4 mm, which is the sum of the specified lining thickness of 3 mm on the outer peripheral side of the core bar 20 and the specified crushed thickness of 1 mm, and an annular convex portion 40 is formed on the seal side of this outer peripheral lining portion 33.Therefore, it is possible to easily form an outer peripheral seal portion having the required seal width W without having to finely set the shape of the core bar 20 and without being concerned about the thickness or tapered shape of the outer peripheral end side of the core bar 20.

[0084] The predetermined sealing width W of the annular protrusion 40 is set to 3 mm, which is the width required for a valve body 2 of the size of this embodiment. Therefore, when the valve is closed, the outer peripheral surface of the core metal 20 presses against the outer peripheral lining portion 33 including the annular protrusion 40, and the tip sealing surface 41 of the annular protrusion 40 is pressed against the annular sealing surface 43 on the inner circumference of the seat liner 4, reliably preventing leakage.

[0085] Furthermore, the outer peripheral side surface portion 20a of the core wire 20 is designed to have a width that allows it to face the center of the annular protrusion 40 in the thickness direction even if warping occurs to the maximum expected warping width on the valve wing side of the core wire 20.Therefore, even if the warping of the core wire 20 reaches its maximum, the outer peripheral side surface portion 20a and the center of the annular protrusion 40 will always face each other, so that a decrease in sealing performance can be prevented even if warping or bending of the core wire 20 occurs.

[0086] Furthermore, the angle θ of both side surfaces 42 of the annular protrusion 40 is set by an inclined surface that is 10° with respect to the pressure sealing direction of the tip seal surface 41, so the side surfaces 42 of the annular protrusion 40 become nearly parallel in relation to the pressure sealing direction of the tip seal surface 41. Therefore, the annular protrusion 40 can be formed longer during molding, and the excess portion can be cut off to make it easier to process to the specified seal width W.

[0087] As shown in FIG. 5 , a pair of washers 51 consisting of a convex washer 60 and a concave washer 61 is installed inside the upper and lower mounting portions 12, and the convex spherical surface 62 and the concave spherical surface 63 are pressed by the elastic force of the spring 56. As a result, even if the valve disc 2 moves and tilts the stem 5, the convex spherical surface 62 slides against the concave spherical surface 63, causing the convex washer 60 to tilt along with the stem 5, while the predetermined orientation of the concave washer 61 is maintained. Therefore, even if the pressing force of the spring 56 is applied in a direction tilted relative to the boss surface 4d due to the tilt of the stem 5, the washer 51 converts this force into a force perpendicular to the boss surface 4d. Without this washer 51, the pressing force of the spring 56 would be applied to the boss surface 4d at an angle, causing the pressing force on the circular boss surface 4d to be inconsistent in the circumferential direction, which could result in leakage at the weakened portion. In contrast, the washer 51 converts the pressing force perpendicular to the boss surface 4d, so that the force is applied uniformly in the circumferential direction of the boss surface 4d.

[0088] As a result of the above, when the valve is closed, sealing is ensured on both the boss side of the valve body 2 and the valve blade side other than the boss part. For example, even if the valve body 1 is enlarged to a nominal diameter of approximately 350A to 600A, it is possible to improve sealing all around the valve body 2.

[0089] The above describes in detail the embodiments of the present invention, but the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the spirit of the invention described in the claims of the present invention. [Explanation of symbols]

[0090] 1 Valve body 2 Valve body 3 Body 4 Seat Liner 5 Stem 5a upper stem 5b lower stem 12 Mounting section 20 Core 20a Outer periphery side part 22 Lining part (lining layer) 23 Stem insertion hole 30 Boss section 32 Front and back lining 33 Peripheral lining 40 Annular convex part (convex part) 41 Tip seal surface 42 Inclined surface (side part) 51 Washer 56 Coil spring 60 Convex washer 61 Concave washer 62 Convex spherical surface 63 Concave spherical surface 100 Molding mold (mold) 100a Upper mold 100b Lower mold T1, T2 thickness W: specified seal width θ angle

Claims

1. 1. A lining-type butterfly valve comprising a valve element having a core bar covered with a lining layer and rotatably mounted within a body by a stem, the lining layer comprising front and back lining portions respectively provided on the front and back sides of the core bar, and a peripheral lining portion provided on the outer periphery of the core bar, the front and back lining portions being provided on the front and back sides of the core bar assuming no warping, at least at the outer periphery of the core bar, with a thickness equal to the sum of a predetermined lining thickness and a thickness equal to the maximum warping width expected on the valve blade side of the core bar, and the outer periphery lining portion having a thickness from the outer periphery of the core bar to the tip seal surface of the outer periphery of the valve element being the sum of the predetermined lining thickness and a predetermined crushing thickness.

2. 2. A lining-type butterfly valve according to claim 1, wherein the outer peripheral lining portion has a convex portion that protrudes toward the outer peripheral side of the valve body and is formed in a generally annular shape continuous with the outer periphery of the valve body, and the end face of the convex portion on the outer peripheral side of the valve body forms the tip seal surface having a predetermined seal width.

3. 3. A lining type butterfly valve according to claim 2, wherein the core metal has an outer peripheral side surface portion at its outermost periphery, and this outer peripheral side surface portion has a width that allows it to face the center in the thickness direction of the convex portion provided on the outer peripheral lining portion even if the core metal warps to the maximum warp width expected on the valve blade side of the core metal.

4. 4. The lining type butterfly valve according to claim 2, wherein each side surface of the protrusion facing the tip seal surface is formed as an inclined surface at an angle of 10° or less with respect to the pressure sealing direction of the tip seal surface.

5. 5. A lined butterfly valve according to claim 1, wherein a pair of washers facing each other in the direction of insertion of the stem are attached within the mounting portion into which the stem is inserted, and the pair of washers have a combination of concave and convex shapes that ensure that the surface pressure applied from the stem side to a boss portion formed on the valve body is approximately constant even when there is a misalignment or tilt between the stem and the valve body.

6. 6. A lining type butterfly valve according to claim 5, wherein the washer comprises a convex washer having a convex spherical surface and a concave washer having a concave spherical surface with which the convex spherical surface makes surface contact, and the convex washer and the concave washer are mounted in a state where they are pressed in opposing directions by the elastic force of a spring mounted within the mounting portion.

7. a butterfly valve in which a valve body, the valve body being formed by a core bar covered with a lining layer, is rotatably mounted within a body by a stem, the lining layer comprising: a front and back lining portion provided on the front and back sides, respectively, of the core bar, and a peripheral lining portion provided on the outer periphery of the core bar, the front and back lining portions having at least a predetermined lining thickness on the front and back sides of the core bar, and at least at the outer periphery end position of the core bar, having a total thickness on the front and back sides that is twice the predetermined lining thickness plus a thickness equal to the maximum warp width expected on the valve blade side of the core bar, and the outer periphery lining portion has a thickness from the outer periphery end of the core bar to the tip seal surface of the outer periphery end of the valve body that is the sum of the predetermined lining thickness and a predetermined crushing thickness.

8. 8. A method for manufacturing a lining type butterfly valve according to claim 1, wherein stems or stem jigs are inserted into stem insertion holes provided in the core bar at positions opposite to the valve wing portions of the core bar to fix the core bar and the stem or stem jig to each other, the core bar is placed in a molding space of a mold for molding the lining layer, and the core bar is fixed so as not to move within the molding space by holding upper and lower stems or upper and lower stem jigs, and then a material for forming the lining layer is introduced into the molding space to form the lining layer on the surface of the core bar.

Images