JPH0350150B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a valve box for a butterfly valve, particularly to a novel structure of a valve box formed by pressing a metal plate.

[Prior art] In the past, valve bodies for butterfly valves were manufactured by machining finished castings made from ferrous or non-ferrous metals, but in recent years, they have been manufactured using advances in sheet metal press machines to manufacture ferrous or non-ferrous metals. By forming a non-ferrous metal plate by press working and omitting the subsequent machining, or by minimizing the machining, we can efficiently produce large quantities of valve boxes that guarantee precise dimensions, and reduce the manufacturing cost. It is also dramatically reduced compared to cast products.

In addition, since the weight is significantly reduced, construction benefits can be obtained when installing the pipe into a pipeline, and since the load on the pipeline is small during use, there is a great benefit in terms of maintenance.

However, while press-molded butterfly valves have the above advantages, they also have problems that do not occur with cast products because of their small wall thickness.

The connection state of a general butterfly valve is shown in FIG. 7, and this point will be explained.

In this figure, 1a is a valve box with a cylindrical body 6a.
A packing 9a is fitted into this packing accommodating part, and flanges 10a of the left and right pipes are formed.
It is in contact with 10a.

Several common circular holes are bored in the left and right pipe flanges, and the holes are tightened with bolts 28 and nuts 29, and the fitted packing 9a is press-fitted to achieve a water seal. There is.

[Problems to be Solved by the Invention] If this tightening force is applied in the left and right horizontal directions, the stress will be concentrated on the bending line L of the packing accommodation portion 7a, and since the thickness of the molded material is thin, there is a risk of deformation or breakage. .

In particular, this part may be pressed out with a press so that its outer diameter is larger than that of the cylindrical part 6a, so that the wall thickness is thinner than the original thickness, or a separately molded annular packing housing part may be tightly fixed here. Because of this, it is the part of the valve box that tends to be the weakest in terms of strength.

Therefore, the risk of breakage and deformation is further exacerbated.

Incidentally, there have been several attempts to solve this problem in the past. For example, as shown in FIG. A configuration in which multiple welds are applied or the cylindrical body 6c is widened from the middle toward the outer end as shown in FIG. ))and so on.

The former is a well-known technique, but since the durability against internal pressure varies depending on the location, a large number of ribs are required, reducing work efficiency and making it unsuitable for mass production.

The latter has the effect of being able to withstand compressive stress much better because the load is applied by decomposing the compressive stress into an inclined vector, but the load acting in the circumferential direction of the pipe due to fluid pressure is proportional to the pipe line, so it expands toward the end. A large load is placed on the inner wall.

Therefore, when integrally formed using a press, the plate thickness becomes thinner in inverse proportion to the expansion, so the original plate thickness must be selected by calculating in advance the plate thickness that can withstand the increased load, and then calculating the thinning due to processing. .
Next, as an issue with valve boxes in general (including not only those formed by press processing but also cast valve boxes),
The elasticity of the packing itself deteriorates over time, and as a result, the sealing performance deteriorates, so it is necessary to compensate for this deterioration by replacing the packing or retightening the connecting bolts.

Furthermore, if the packing loses its adhesion and a gap is created between the packing and the packing accommodating portion, so-called crevice corrosion may occur depending on the material, which may significantly shorten the life of the valve. As is well known, this tendency is particularly noticeable in valve bodies made of austenitic stainless steel.

In order to solve the above problems, the present invention has a structure that can sufficiently withstand compressive stress even if it is inserted in a pipe and is tightened from the left and right sides for water sealing, and can also withstand internal pressure. The purpose of the present invention is to provide a butterfly-shaped valve that has a structure that does not lose its compressibility with the packing accommodating part and therefore does not lead to deterioration of sealing performance, and that uses press forming as the main process with high productivity. .

[Means for Solving the Problems] In the butterfly valve according to the present invention, the valve box is formed of a double structure of an inner shell 4 and an outer shell 5 formed by press molding a thin metal plate, and the inner shell 4 consists of a cylindrical part 6 that limits the flow path, and packing accommodating parts at both ends that deform from this cylindrical part into a substantially S-shaped cross section and expand in outer diameter, and the outer shell 5 surrounds the entire outer periphery of this inner shell. to form a space 8, the inner shell 4 and the outer shell 5 are overlaid and integrally fixed at both ends of the valve box, and the width W ₁ on the outer diameter side of the packing 9 accommodated in the packing accommodating portion The above problem was solved by making W2 larger than the width _W2 on the inner diameter side.

[Function] Since the valve box of the butterfly valve according to the present invention has the above-described configuration, when it is sandwiched between the left and right pipes and tightened from both sides, the compressive stress applied to the packing housing part is transferred to the end of the valve box. Since the overlapping end surfaces of the inner and outer shells that form the inner and outer shells receive it evenly, the burden on the bending line L of the inner shell is halved.

On the other hand, it is the cylindrical part of the inner shell that receives the internal pressure from the fluid passing through the valve box, and since this part cannot be thinned by expansion processing, it is sufficient to do so without increasing the wall thickness. Can withstand internal pressure.

In addition, in the thinner packing housing part of the inner shell, the outer shell behind backs up the internal pressure and receives it in a complex manner.

In addition, elasticity occurs on the wall surface of the S-shaped packing housing made of thin metal, creating a kind of spring action and shock absorption, which greatly increases the adhesion of the fitted packing, and the packing itself deteriorates over time. Even if its elasticity deteriorates due to the packing accommodating portion, the elasticity of the wall surface of the packing accommodating portion is not lost and the adhesion with the packing is maintained for a long time. Therefore, the conventional valve box is freed from the troublesome work of retightening the connecting bolts, which deteriorates the sealing performance due to aging of the packing.

Furthermore, the width of the outer diameter side of the packing to be accommodated here
Since the shape is formed such that W ₁ is larger than the width W ₂ on the inner diameter side and is fitted into the S-shaped packing housing part, even if the pipe is twisted or curved, it can be easily removed from the housing part. There is no need to worry about leaving.

[Example] A preferred embodiment of the present invention will be described based on FIG. 1 (front partial sectional view), FIG. 2 (side partial sectional view), and FIG. 3 (perspective view).

The valve box 1 is sandwiched between flanges 10, 10 of the left and right pipes, and is formed by an inner shell 4 and an outer shell 5.

The inner shell 4 is made of a thin cylindrical steel plate, and the center serves as a cylindrical portion 6 which serves to limit the flow path, but both sides are expanded into an S-shape by press working to form packing accommodating portions 7, 7. do.

Width W ₁ on the outer diameter side of packing 9 to be accommodated here
The S-shape is inclined so that W2 is larger than the inner diameter side _W2 .

The outer shell 5 is a thin-walled cylindrical body made of a steel plate, and is fitted onto the outer periphery of the inner shell, with both ends aligned and fixed together by welding together.

The valve stem 2 is a shaft member having a square cross section, and is rotatably supported by an upper bearing 12 via an upper bush 11 and by a lower bearing 14 via a lower bush 13, respectively.

The valve stem 2 can be rotated within the valve body 1 by receiving driving means (not shown) such as a spanner, a special lever, or a round handle from a drive unit 15 that protrudes above the valve body from the upper bearing of the valve stem 2. .

The inner peripheries of the upper and lower bushes 11 and 13 have a square shape similar to the outer periphery of the valve stem 2, and are fixed to the valve stem with a stopper (press fit), and the outer peripheries are cylindrical and can freely rotate with the upper and lower bearings 12 and 14. It is becoming.

A valve body 3 is attached to the valve stem 2 in a non-rotatable manner within the valve box, and the valve body has a valve plate 16, which is a pair of disc-shaped thin steel plates facing each other and sandwiching the valve stem in the center. ,
It is composed of a cover 17 made of an elastic material such as rubber, which overlaps two valve plates and covers the entire outer surface thereof.

A valve rod 2 that passes through the cylindrical center of the inner shell, which serves as a flow path.
An upper plane seat 18 and a lower plane seat 19 are provided around the upper and lower plane seats by partially pressing the inner shell, and a plane seat is also provided on the outer peripheral surface of the valve body 3 around the valve stem corresponding to the upper and lower plane seats. 20 and 21 are provided, respectively, so that the valve body and the valve body can slide in a sealed manner as the valve shaft rotates.

In addition, the flange 22 is a place where a driving means for rotating the valve stem is attached, and the packing 22
3. Split rings 24, 25, a retainer ring 26, etc. are attached directly below the flange to seal the valve stem and the upper bearing.

FIG. 4 shows a second embodiment of the present invention, in which the end of the packing accommodating portion 7 of the inner shell is folded back to form a U-shaped cross section, and the end of the outer shell is inserted into this and fixed by welding. FIG. 5 similarly shows the third embodiment, in which the outer shell end is folded back to form a U-shaped cross section, into which the end of the inner shell packing accommodating portion 7 is fitted and fixed by welding.

It goes without saying that components other than the valve box 1 can be replaced by any known technique; for example, the valve stem 2 may be a hexagonal member instead of a rectangular member;
The valve body 3 is not entirely covered with an elastic body, but is made by overlapping two valve plates to form a concave groove on the outer periphery as shown in Fig. 6, into which a packing 27 is fitted and slid while sealing. You may let them.

Secondly, in any embodiment of the present invention, the inner shell 4 and the outer shell 5 can be made of different types of metal materials.

This is because both are pressed and molded separately.

There are countless combinations of these different materials, but
For example, a wide variety of materials can be selected as long as the inner shell can be pre-processed, such as high-tensile steel and mild steel, stainless steel and mild steel, stainless steel and monel metal, mild steel and titanium, and nickel and copper.

[Effects of the Invention] The first result of the present invention is that both the inner shell and the outer shell share the compressive stress caused by the tightening that occurs when the pipe is inserted into the pipe, so that the bending line L of the expansion is The load is small and the weak point of thinning due to molding can be overcome, and damage and deformation of the valve box can be prevented.

In addition, the inner and outer shells can sufficiently withstand the internal pressure passing through the flow path, which solves the technical problem.

A more detailed study shows that by constructing the valve box with an inner shell and an outer shell, the section modulus increases even if these are thin-walled members. There is no risk of damage to the valve box even if bending is applied.

Further, since the curved protrusion of the packing accommodating portion has a surface pressure greater than that of the other contact portions, the joint portion between the metal and the packing exposed to the fluid is crimped and there is no room for a gap to occur.

Therefore, crevice corrosion at the wetted parts, which tends to occur depending on the material (for example, austenitic stainless steel), hardly occurs.

The above-mentioned effect is produced by the fact that the valve body is made of a thin sheet metal, and the irregularly shaped packing is housed in the S-shaped irregularly shaped packing accommodating portion.

To further discuss the packing accommodating part (S-shaped) and the special packing shape (W ₁ > W ₂ ), a problem with the prior art is that the cross sections of the packing accommodating parts 7a and 7c in FIGS. 7 and 9 are As shown in the figure, the widths Wa ₂ and Wc ₂ on the inner diameter side are larger than the widths Wa ₁ and Wc ₁ on the outer diameter side, or at least both are the same, so the liquid passing inside the valve body causes packing 9a, 9c
There was a risk that the seal would be sucked inward, resulting in incomplete sealing or damage to the packing.
This made it possible to almost completely eliminate the problem.

In addition, the outer shell surrounds the entire outer periphery of the inner shell to form a space 8.
This is useful to prevent energy loss due to heat radiation from high-temperature fluids due to the formation of a thermally defective conductive layer, to prevent personal injury due to high temperatures, or to prevent exposure of gaseous fluids and freezing of liquid fluids due to a drop in outside temperature. It has the advantage of not requiring insulation materials or heat insulation (heating) equipment.

In addition, the inner shell is not affected by the outside temperature and follows the temperature of the pipe fluid in the same state as the valve body, so unlike the conventional technology, when the outside temperature rises, only the valve body expands and causes a seal failure. There is no risk of problems such as the valve box contracting due to a drop in outside air temperature, resulting in poor opening/closing.

Next, effects specific to the embodiment will be explained.

The unique effects of claims 3 and 4 are that the end face of the inner shell or outer shell is folded back to form a three-layer valve box end, so that the pressure resistance is further increased and the fit is improved. Therefore, it is necessary to shorten the weld bead length or apply spot welding to reduce the number of welding steps and to reduce thermal deformation.

Further, the specific effect of claim 5 is that the outer shell is made of high tensile strength steel (high tensile strength steel) with high material strength, and the inner shell is made of mild steel that is easily plastically deformed. Deep drawing etc. can be carried out easily.

Another important advantage is that an appropriate material can be selected depending on the atmosphere outside the pipe and the properties of the fluid inside the pipe.

For example, if the fluid is alkaline and the outside air is acidic, the valve box is constructed by combining an alkali-resistant material for the inner shell and an acid-resistant material for the outer shell.

In addition, metal plates with special resistance such as corrosion resistance, heat resistance, and abrasion resistance can be selected as the material in response to the special characteristics of the outside air and the flow path.

In each case, if an appropriate mold is prepared, precise molding is possible through press processing, and it can be easily mass-produced at a low price, so the advantages of the conventional press-formed butterfly mold are still maintained. Tama,
In addition to solving the problems of the prior art, we were able to add a number of secondary features.

[Brief explanation of drawings]

FIG. 1 is a front partial sectional view of the first embodiment, FIG. 2 is a side partial sectional view, FIG. 3 is a partially cutaway perspective view, FIG. 4 is a second embodiment, and FIG. FIG. 6 is a front partial sectional view showing another embodiment of the valve plate, FIG. 7 (front sectional view), FIG. 8 (perspective view), and FIG. Figure 9 (front sectional view)
The three drawings are drawings showing separate prior art. 1... Valve box, 2... Valve stem, 3... Valve body, 4...
Inner shell, 5... Outer shell, 6... Cylindrical section, 7... Packing storage section, 8... Space section, 9... Packing.

Claims (1)

[Scope of Claims] 1. An annular valve body 1, a valve stem 2 rotatably mounted across the flow path at right angles at the center of the valve body, and sealed on the inner surface of the valve body as the valve stem rotates. In a butterfly-shaped valve consisting of a substantially disk-shaped valve body 3 that slides while moving, the valve body is formed of a double structure of an inner shell 4 and an outer shell 5 formed by press molding a thin metal plate, and the inner shell Numeral 4 consists of a cylindrical part 6 that limits the flow path, and packing accommodating parts at both ends that are deformed from this cylindrical part into a substantially S-shaped cross section and have an expanded outer diameter, and the outer shell 5 surrounds the entire outer periphery of this inner shell. to form a space 8, the inner shell 4 and the outer shell 5 are overlapped and integrally fixed at both ends of the valve box,
The butterfly valve is characterized in that the width W ₁ on the outer diameter side of the packing 9 accommodated in the packing accommodating portion is larger than the width W ₂ on the inner diameter side. 2. The butterfly valve according to claim 1, wherein the inner shell 4 and the outer shell 5 are substantially horizontally overlapped and fixed at both ends of the valve body. 3. At both ends of the valve box where the inner shell 4 and outer shell 5 are fixed, the end of the inner shell is folded back into a "U" shape, and the outer shell end is inserted and fixed between the ends. Butterfly valve as described in section. 4 At both ends of the valve box where the inner shell 4 and outer shell 5 are fixed, the end of the outer shell is folded back into a "U" shape, and the end of the inner shell is inserted and fixed between the ends. Butterfly valve as described in section. 5. The butterfly valve according to any one of claims 1 to 4, wherein the metal material forming the inner shell 4 and the metal material forming the outer shell 5 are different combinations.