JP3708177B2 - Butterfly valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a butterfly valve in which a rubber sheet made of an elastic material is baked and molded on the inner diameter side of a body, and more particularly to a butterfly valve that can exhibit stable performance even under a pressure of 10 kgf / cm ² or more.
[0002]
[Prior art]
In general, as shown in FIGS. 6 and 7, the butterfly valve rotates to a cylindrical body 11, an annular rubber sheet 12 mounted on the inner diameter side of the body 11, and a facing position along the diameter direction of the body. The stems 13 and 13 are freely mounted, and the discs 14 are connected to the stems 13 and 13 and are rotatably disposed on the inner diameter side of the rubber sheet 12. By rotating the stems 13, the discs 14 are moved. By rotating, the inner peripheral surface of the rubber sheet 12 and the outer peripheral surface of the disc 14 are brought into contact with and separated from each other, and the opening / closing of the valve or the flow rate is controlled. In particular, the seal between the rubber sheet 12 and the disc 14 presses the outer peripheral surface of the disc 14 to the inner peripheral surface of the rubber sheet 12 by using both the elastic repulsive force of the rubber sheet 12 and the self-tightening effect due to the fluid pressure. High sealing performance is guaranteed.
[0003]
Further, in a conventional butterfly valve, an inner mold (not shown) separately molded inside the body 11 is combined with the cast body 11 as an outer mold, and an elastic material is injected between these molds, followed by vulcanization molding. The rubber sheet 12 is molded and bonded to the inner peripheral surface of the body 11. Normally, the body 11 of this butterfly valve has an inner peripheral surface processed to make the rubber sheet 12 uniform in thickness. As disclosed in Japanese Utility Model Laid-Open No. 60-64824, the inner peripheral surface 11a of the body 11 is processed in order to increase the adhesive strength between the body 11 and the rubber sheet 12, and to reduce the cost by reducing the processing points. There is also a case in which the rubber sheet 12 is baked and molded on the inner peripheral surface 11a of the body in an as-cast state.
[0004]
[Problems to be solved by the invention]
Among the butterfly valves in which the rubber sheet 12 is baked and molded as described above, the inner peripheral surface of the body 11 is machined, and the inner diameter size, crushing allowance, and thickness of the rubber sheet 12 are accurately molded. Therefore, the rubber sheet 12 is hardly deformed or peeled off due to fluid pressure or flow velocity, and the torque is stable. Therefore, the rubber sheet 12 can be used under a condition where the pressure exceeds 10 kgf / cm ² . Moreover, what left the inner peripheral surface 11a of the body 11 as-cast has the advantage that adhesive strength is high and it is hard to peel off, and the manufacturing cost can be reduced by reducing the number of processing steps.
[0005]
However, the method of baking and molding the rubber sheet 12 while leaving the inner peripheral surface 11a of the body 11 as-cast can accurately mold the inner diameter of the rubber sheet 12, but the inner diameter error of the body 11 due to casting size tolerance. As a result, the thickness of the rubber sheet 12 varies, and the sealing performance and the operating torque change in proportion to the thickness, so that stable performance cannot be obtained. As can be seen from the fact that the crushing allowance of the O-ring is defined according to the thickness of the O-ring, the crushing allowance according to the thickness of the rubber sheet 12 is required to obtain the same sealing performance. Even if the inner diameter of the rubber sheet 12 and the size of the crushing allowance are accurately molded, the ratio of the crushing allowance to the thickness of the rubber sheet 12 varies, so that the operating torque increases and the sealing performance decreases. Problems occur. In particular, the influence on the operating torque applied to the disc is significant.
[0006]
This is explained by taking a butterfly valve having a nominal diameter of 100A as an example. Generally, the thickness of the rubber sheet 12 is 5 mm and the dimensional tolerance of the inner diameter of the casting body 11 is 1.8 mm. If the thickness tolerance of the rubber sheet 12 is 0.0 mm, the thickness of the rubber sheet 12 is 5.00 ± 0.45 mm, which results in a variation of ± 9.0%.
[0007]
The present invention has been made in order to solve the above-described problem, and is a butterfly valve having a stable performance by suppressing variation in the thickness of a rubber sheet and preventing an increase in operating torque and fluid leakage while reducing cost. The purpose is to provide.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is characterized in that a substantially annular rubber sheet made of an elastic material is baked on the inner diameter side of a substantially cylindrical body formed with the inner peripheral surface being in a rough state as cast. A butterfly valve that is molded and has a stem rotatably mounted in a diametrical direction of the body, and a disc-shaped disc fixed to the stem on the inner diameter side of the rubber sheet and rotatably disposed ; The inner diameter is small in the stem direction and large in the stem vertical direction, and the thickness of the rubber sheet in the stem direction is smaller than the thickness in the stem vertical direction, and the stem is formed around the stem on the inner peripheral surface of the body. A butterfly valve in which a concentric annular recess is formed, and a rubber sheet extending in the stem direction is extended in the annular recess. The invention according to claim 2 provides a center line of the body perpendicular to the stem. A butterfly valve in which the inner diameter of the body is about ± 70 ° to ± 120 ° and the stem periphery is small, and about ± 0 ° to ± 70 ° and about ± 120 ° to ± 180 ° are large. It is .
[0009]
[Action]
In the present invention configured as described above, since the inner diameter of the body is small in the stem direction and large in the stem vertical direction, the thickness of the rubber sheet is cast in the stem direction, and the tolerance of the dimension is 2.5-3. It can be molded 0 times and 4.0 to 4.5 times in the stem vertical direction.
[0010]
In addition, by changing the thickness of the rubber sheet in this way, the variation in the thickness of the rubber sheet in the stem vertical direction can be suppressed, sealing performance and operating torque can be stabilized, and rubber close to the stem that is the center of rotation. Since the thickness of the sheet in the stem direction has little influence on the operating torque, it can be molded thinner than the thickness in the stem vertical direction to improve the sealing performance of the stem peripheral portion.
[0011]
Further, by extending the rubber sheet around the stem, the expansion of the stem hole of the rubber sheet can be prevented, and the sealing performance around the stem can be improved.
[0012]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a schematic longitudinal sectional view showing an embodiment of a butterfly valve according to the present invention, FIG. 2 is an enlarged transverse sectional view of the butterfly valve of the embodiment, and FIG. 3 is an enlarged longitudinal section of the periphery of the stem of the butterfly valve of the embodiment. FIG.
[0013]
The butterfly valve of the present embodiment is formed by baking a rubber sheet 2 so as to cover the inner peripheral surface 1a of the substantially cylindrical body 1, and through the stem holes 3a, 2a of the rubber sheet 2 through the stems 3, 3, respectively. The disk 1 is rotatably mounted in the shaft holes 1b and 1b of the body 1, and the disk-shaped disc 4 is fixed to the stems 3 and 3 so as to be rotatably disposed on the inner diameter side of the rubber sheet 2. By rotating the disc 4 through the stem 3, the outer peripheral surface of the disc 4 is brought into contact with and separated from the rubber sheet 2, and the valve is opened and closed or the flow rate is controlled.
[0014]
The body 1 is cast into a substantially cylindrical shape by appropriately using a steel-based material such as gray cast iron or spheroidal graphite cast iron, and burrs appearing on the surface are removed, but the inner peripheral surface 1a is cast without being processed. A rough cast skin is left in a free state. Further, by molding the inner diameter of the body 1 small in the stem direction and large in the stem vertical direction, the thickness of the rubber sheet 2 to be baked and molded on the inner peripheral surface 1a is cast in the stem direction to a dimensional tolerance of 2.5. Molded up to 3.0 times and 4.0 to 4.5 times in the stem vertical direction. Further, shaft holes 1b and 1b for mounting the stems 3 and 3 are formed on the upper and lower portions of the body 1 that face each other along the diameter direction.
[0015]
The rubber sheet 2 has a body 1 as an outer mold, an inner mold (not shown) separately molded in the outer mold, and an elastic material such as NBR or EPDM is injected into a molding space between the molds, followed by vulcanization molding. As a result, the annular rubber sheet 2 is integrally molded and bonded to the body 1. The rubber sheet 2 thus molded is accurately molded in terms of inner diameter and crushing allowance, and has a thickness of 2.5 to 3.0 times the dimensional tolerance in the stem direction and 4. in the stem vertical direction. Molded from 0 to 4.5 times. Further, stem holes 2 a and 2 a for penetrating the stems 3 and 3 are formed with the shaft centers aligned with the shaft holes 1 b and 1 b of the body 1. The rubber sheet 2 may be molded by selecting appropriate blending and vulcanization conditions according to the use conditions.
[0016]
Further, as shown in FIG. 4, an annular recess 5 concentric with the stem 3 is provided in the periphery of the shaft hole 1b molded in the body 1, and an elastic material is injected into the annular recess 5 and vulcanized. The rubber sheet 2 may be extended.
[0017]
Here, a butterfly valve having a nominal diameter of 100A will be described as an example.
Body 1 inner diameter dimensional tolerance is 1.8mm, rubber sheet 2 thickness tolerance is 0.0mm, rubber sheet 2 thickness is cast in the stem direction, 2.5 to 3.0 times the dimensional tolerance, stem vertical The thickness of the rubber sheet 2 is 4.50 ± 0.45 mm to 5.4 ± 0.45 mm in the stem direction and 7.20 ± 0.4 in the stem vertical direction, assuming 4.0 times the as-cast dimension tolerance in the direction. 45mm. As a result, the thickness of the rubber sheet 2 varies ± 10.0 to ± 8.3% in the stem direction and ± 6.3% in the stem vertical direction.
[0018]
As shown in the figure, the inner diameter of the body 1 in this case is about ± 70 ° to ± 120 ° around the axial holes 1b and 1b, with the center line of the body 1 perpendicular to the stem 3 being 0 °, and is about The part of ± 0 ° to ± 70 °, about ± 120 ° to ± 180 ° is greatly molded, and the thickness of the rubber sheet 2 is 4.50 ± 0.45mm to 5.4 ± 0.45mm in the stem direction. Molded to 7.20 ± 0.45mm in the vertical direction. In addition, the thickness in the stem direction and the thickness in the stem vertical direction of the rubber sheet 2 are appropriately cast in the stem direction so that the performance suitable for the use conditions can be obtained. In the range of 4.0 to 4.5 times, the inner diameter of the body 1 may be determined.
[0019]
In the butterfly valve formed in this way, the variation in the thickness of the rubber sheet 2 in the stem vertical direction is suppressed to ± 6.3%, so that the sealing performance and the operating torque are stabilized. On the other hand, the variation in the thickness in the stem direction of the rubber sheet 2 is as large as ± 10.0 to ± 8.3% compared to the variation in the thickness in the stem vertical direction. This is because, as the thickness of this portion increases, the force for expanding the stem holes 2a, 2a of the rubber sheet 2 increases and causes fluid leakage (see FIG. 5). However, since this portion is close to the stems 3 and 3 and has little influence on the operating torque, it is molded thinner than the thickness in the stem vertical direction to improve the sealing performance around the stems 3 and 3.
[0020]
Further, as shown in FIG. 4, by extending the rubber sheet 2 around the stems 3 and 3, the expansion of the stem holes 2 a and 2 a of the rubber sheet 2 can be prevented. Sealing performance is improved.
[0021]
Furthermore, since the rubber sheet 2 is baked and molded without processing the inner peripheral surface 1a, the adhesive strength between the body 1 and the rubber sheet 2 is increased, and the rubber sheet 2 is peeled off due to repeated operation of the valve, etc. It is possible to prevent deformation, movement, etc., to prevent an increase in operating torque and fluid leakage, and because the inner peripheral surface 1a of the body 1 is processing-free, the number of processes can be reduced and costs can be reduced.
[0022]
【The invention's effect】
As described above, in the present invention described in detail, the inner diameter of the body is formed small in the stem direction and large in the stem vertical direction, and the thickness of the rubber sheet is cast in the stem direction, so that the dimensional tolerance is 2.5 to 3.0. A butterfly valve having a uniform and stable performance can be provided by suppressing a variation in the thickness of the rubber sheet due to a dimensional tolerance of a cast body by molding the stem to 4.0 to 4.5 times in the stem vertical direction. be able to.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing an embodiment of a butterfly valve according to the present invention.
FIG. 2 is a partially enlarged cross-sectional view of the butterfly valve.
FIG. 3 is an enlarged longitudinal sectional view of a peripheral portion of a stem of the butterfly valve.
FIG. 4 is an enlarged longitudinal sectional view of a peripheral portion of a stem of a butterfly valve according to another embodiment.
FIG. 5 is an enlarged longitudinal sectional view of a portion around a stem of a butterfly valve in which a rubber sheet is baked and molded to substantially the same thickness.
FIG. 6 is a schematic longitudinal sectional view showing a butterfly valve obtained by baking and molding a conventional rubber sheet.
FIG. 7 is a partial enlarged cross-sectional view of the butterfly valve.
[Explanation of symbols]
1 Body 1a Inner peripheral surface 2 Rubber sheet 3 Disc 4 Stem 5 Annular recess

Claims (2)

A substantially annular rubber sheet made of an elastic material is baked and molded on the inner diameter side of a substantially cylindrical body that has been molded with the inner peripheral surface in an as-cast rough state, and a stem is rotatably mounted in the diameter direction of the body. Furthermore, in a butterfly valve in which a disk-shaped disc is fixed to the stem on the inner diameter side of the rubber sheet and is rotatably disposed, the inner diameter dimension of the body is small in the stem direction and large in the stem vertical direction, A thickness of the rubber sheet in the stem direction is molded to be thinner than a thickness in the stem vertical direction, and an annular recess concentric with the stem is formed in the periphery of the stem on the inner peripheral surface of the body, and the rubber in the stem direction is formed in the annular recess. A butterfly valve characterized by extending the seat . When the center line of the body perpendicular to the stem is 0 °, the inner diameter of the body is about ± 70 ° to ± 120 ° and the stem peripheral portion is small, about ± 0 ° to ± 70 °, about ± 120 ° to ± 180. The butterfly valve according to claim 1, wherein a portion of ° is formed to be large .

Images