JPS6215793B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a valve body of a butterfly valve in which a rubber lining is applied for corrosion prevention, rust prevention, etc., and in particular, a method for accurately forming the dimensions and shape of the outer peripheral seal portion of the valve body after rubber lining. The present invention relates to a method for manufacturing a butterfly valve body that eliminates the need for cutting, which is a post-processing process after vulcanization.

Generally, this type of butterfly valve is required to have corrosion resistance, rust resistance, erosion resistance, and cavitation resistance. Therefore, in a typical butterfly valve, an elastic rubber corresponding to a valve seat is adhered or fitted onto the inner surface of the main body. However, the valve body of the butterfly valve must have a fluid pressure resistance strength when the valve is closed, and must have a higher hardness than the elastic rubber in order to maintain sealing performance with the elastic rubber.

Generally, valve bodies are often made of metal materials such as stainless steel and bronze. However, as valves become larger, these materials become less economical and workable, and are therefore not widely used. A rubber lining method was proposed in consideration of economic efficiency, but after the lining was vulcanized, it was necessary to cut the outer periphery. As seen in Japanese Patent Publication No. 55-14308, a screw hole 32 for fixing to a machine tool is formed on the side of the valve body (No. 8).
(see figure). After processing, the screw hole 32 is filled with synthetic resin or the like, but repairing it after rubber vulcanization lacks reliability, and the filling material peels off, exposing the valve body and corroding the rigid material. There was a risk of this happening.

From the above, it is understood that it is important that the rubber-lined valve body requires no machining of the outer peripheral edge, where machining accuracy is important, and that there is no repair of machining jig marks.

In particular, it is most important that the outer peripheral edge of the valve body requires no machining and that the adhesive to the rigid material is reliable. Normally, adhesive is applied to a rigid material and vulcanized by pressing it with a roll or the like, but this creates a void between the rigid material and the rubber and adhesive, allowing air or gas to remain. This will result in insufficient adhesion. When such a valve body is assembled into a main body and used by actually flowing fluid, the gap expands due to changes in fluid pressure, flow rate, humidity, etc., and the lining rubber peels off.

The technical problems of the present invention are as follows. That is, the adhesive strength between the rubber and the rigid material on the outer peripheral edge of the valve body is improved and the sealing performance is maintained when the valve is closed.

The technical means adopted to solve the above technical problem is that the valve stem guide portion is located at a diametrically symmetrical position, and the inner circumferential surface is shaped and dimensioned to correspond to the shape and dimensions of the outer circumferential edge of the valve body to be machined. cutting the ring-shaped mold in a radial direction perpendicular to the diametrical direction passing through the valve stem guide portion to obtain a ring-shaped mold divided into two;
After applying lining rubber to the entire surface of a disk-shaped valve body made of a rigid material, the valve stem guide portion is inserted into each valve stem fixed at a diametrically symmetrical position on the valve body, and the ring-shaped split into two parts is inserted. The valve body is characterized in that a mold is attached to the outer periphery of the valve body and connected, and then the lining rubber is vulcanized.

The above means works as follows.

In other words, if the outer diameter of the valve body is sandwiched between two molds, the adhesive strength between the rubber and the rigid material will be much different than when no mold is used. No air or gas remains in the gap between the In addition, since the mold is inserted into the valve stem and positioned accurately, the boss part around the valve stem can be accurately molded, ensuring roundness while preventing runout, and making it possible to form the left and right sides of the valve stem. It becomes possible to mold the same dimensions.

Next, a specific example of the technical means of the present invention will be shown. 6th
7 and 7 show an example of the structure of a butterfly valve in which the valve body of the present invention is incorporated into the main body.

Referring to FIGS. 6 and 7, a seat ring (valve seat) 3 is fitted into the main body 1, and the valve body 2 is attached to a valve stem 4.
It is rotatable by a and 4b. valve stem 4
Attach an appropriate drive device to a to open and close the valve body,
A seal is achieved by the difference in the inner and outer diameters of the seat ring 3 and the valve body 2, and the difference in the roughness and hardness of their contact surfaces. Therefore, the rigid material and the shape of the rubber of the outer circumferential portion 5 (see FIGS. 3 and 4) of the valve body 2 are important. Third
The figure shows a valve body of a central butterfly valve, and FIG. 4 shows a valve body of an eccentric butterfly valve, in which the outer surface of a rigid material 2a of the valve body 2 is lined with rubber 2b. A suitable lining structure for the peripheral portion of the valve body is as shown in FIG.

The lined rubber 2b is vulcanized at the outer circumference 5 of the valve body 2 using a rubber vulcanization mold 6, as shown in FIGS. 1 and 2, and is firmly adhered to the rigid material 2a. Ru. As shown in the figure, the rubber vulcanization mold 6 consists of two molds 6a and 6b divided into upper and lower parts.
Attach the valve body 2 by sandwiching its outer circumference, and tighten with bolts and nuts 7. Since the inner diameter of the rubber vulcanization mold 6 is precisely machined, there is no need to reprocess the valve body after lining. What should be noted here is that although it is possible to mold a perfectly circular valve body with a lining using these methods, the valve body of a butterfly valve has a certain degree of roundness as well as prevention of deflection against the valve stems 4a and 4b. The meaning of the same dimensions on the left and right sides is important, and runout causes leakage when the valve is closed.

For this purpose, the upper and lower parts 6c and 6d of the rubber vulcanization mold are
A guide part for inserting the valve stems is provided in the valve stems 4a and 4.
It is attached to the outer periphery of the valve body 2 while being guided by b, and the bolts and nuts 7 are tightened in the assembled state. This solves the problem of roundness and prevention of runout.

In this way, the inner surface of the rubber vulcanization mold (the surface in contact with the valve body) immediately becomes the outer diameter of the lining valve body, so it goes without saying that the dimensional accuracy and processing accuracy should be processed as specified. do not have. For this reason, applying hard chrome plating to the inner surface, etc. will increase the durability and abrasion resistance of the mold, as well as give the lining a beautiful finished surface.

Normally, the lining thickness varies depending on the valve diameter, etc., but considering the workability of the lining, corrosion resistance, etc., it is appropriate to be about 3 to 6 mm, and the lining surface hardness is 75° ± 5° as measured by a rubber hardness tester (Shorer D type). The degree is appropriate.

The present invention produces the following unique effects.

That is, the vulcanization mold ensures close contact between the rigid material, adhesive, and rubber, and the adhesive strength thereof is significantly improved. As a result, voids, pinholes, etc. can be prevented, and there is no difficulty in machining the outer diameter of the valve body, making it possible to produce a product with guaranteed quality.

These vulcanization molds can be removed and reused after vulcanization, so if one or several molds with different valve diameters are prepared, they can be used repeatedly, making it possible to save labor through mass production, which is economical. products can be provided. In addition, by applying hard chrome plating to the inside of the mold, the outer peripheral surface of the valve body is formed into a smooth surface, which reduces the coefficient of friction when opening and closing the valve, improving durability and wear resistance, as well as providing corrosion resistance. It is possible to provide a high-performance butterfly valve. Furthermore, since the mold is attached to the valve stem while being guided by the guide part, it is possible to accurately position the valve body, and to obtain the roundness of the outer circumference of the valve body. Can be molded to exact dimensions.

[Brief explanation of the drawing]

Figure 1 shows an example of the structure of a rubber vulcanization mold, showing the state in which it is attached to a valve body, and Figure 2 shows the structure of the mold for rubber vulcanization.
3 is a sectional view along the line, FIG. 3 is a central sectional view of the valve body of a central type butterfly valve, FIG. 4 is a central sectional view of the valve body of an eccentric butterfly valve, and FIG. 5 is a lining structure of the periphery of the valve body. 6 is a front view of the butterfly valve, FIG. 7 is a longitudinal sectional view thereof, and FIG. 8 is a sectional view showing the prior art. 1...Main body, 2...Valve body, 3...Seat ring, 4...Valve stem, 5...Periphery, 6...Rubber vulcanization mold, 7...Bolt/nut.

Claims (1)

[Claims] 1. A ring-shaped mold having valve stem guide parts at diametrically symmetrical positions and whose inner circumferential surface has a shape and dimensions corresponding to the outer peripheral edge shape and dimensions of the valve body to be processed is installed in a diametrical direction passing through the valve stem guide part. The mold is cut in the radial direction orthogonal to the radial direction to form a two-part ring-shaped mold, and after pasting rubber lining over the entire surface of a disc-shaped valve body made of a rigid material, the mold is fixed at a symmetrical position in the diametrical direction of the valve body. A valve stem guide portion is inserted into each valve stem, and the two-split ring-shaped mold is attached to the outer circumference of the valve body to connect them, and then the lining rubber is vulcanized. A method for manufacturing a valve body for a butterfly valve.