JPS6224664B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Field of Industrial Application) The present invention relates to a central butterfly valve, and particularly to a method for manufacturing its valve plate.

(Prior Art and Problems to be Solved) The valve shaft is generally formed into a substantially disk shape as a whole, and the valve shaft is passed through the valve shaft in the diametrical direction, and the protrusions at both ends of the valve shaft are connected to the annular valve body surrounding the valve plate. In the well-known central type butterfly valve, which is pivotally mounted, the outer periphery of the valve plate is formed to have a medium height when viewed in radial cross section, and when the valve is closed, an elastic member is stretched over the inner periphery of the valve body. It has been widely used in practical use for a long time to have a structure that not only presses well against the seat ring to provide a sufficient sealing effect, but also escapes from the seat ring as quickly as possible when opening and closing the valve to prevent the rotational torque from increasing. has been done.

The valve plate of such a butterfly valve has an irregular shape in the vicinity of the part of the valve shaft that protrudes from the periphery of the valve plate at both ends of the valve shaft that is attached through the valve plate, so machining is not easy and costs increase. It was the cause.

This will be briefly explained with reference to FIGS. 1 and 2.

FIG. 1 is a front view showing a valve plate of a central butterfly valve, and FIG. 2 is a plan view of the same.The valve plate 1 is formed into a generally disk shape as a whole and has a generally uniform thickness. A thin-walled portion 33 with
It is formed from a bulge 32 having a shape.

It should be noted that the thin wall portion 3 which is the main body portion of the valve plate
3 should be as thin as possible, and at the same time, the valve stem must be thick enough to prevent the valve plate and valve stem from bending due to fluid pressure. The portion having the hole 2a for supporting the shaft has no choice but to protrude from the surface of the thin wall portion 33 to form the bulge portion 32 as described above.

In addition to this configuration, most of the periphery of the valve plate is formed into the middle and high part 31 as described above, and an assembly is formed around the valve stem where both ends of the valve stem protrude from the periphery of the valve plate. Since the flat portion 2 is later formed to form a seal to prevent leakage in the axial direction of the valve shaft, it is difficult to perform continuous work and the number of machining steps increases even when processing with a lathe, etc. This causes an increase in costs.

In other words, when the valve plate shown in Fig. 1 is rotated within the plane of the paper and its outer periphery is cut with a concave blade corresponding to its medium-height shape, a flat portion is first formed. Regardless of whether the outer peripheral edge is cut with a blade or a flat part is formed after cutting the outer peripheral edge, the cutter must come into contact with the end of the bulge 32, that is, with any part of the flat part 2. At this time, the impact may chip the cutter or valve plate material, or an excessive load may be applied to the machine, making machining difficult. Processing is required, which requires a considerable amount of time and effort, which inevitably increases costs.

The present invention has been made to deal with this situation, and as described above, the outer peripheral edge is formed to have a medium height, and a bulge part for supporting the valve shaft and a flat part for sealing are provided at both ends of the bulge part. To provide a method for manufacturing a valve plate, which allows the work to be carried out continuously regardless of the presence of the bulge when processing the outer peripheral edge of the valve plate, greatly reduces the number of processing steps, and provides an inexpensive valve plate. The purpose is to provide

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, in the present invention, the outer peripheral edge is formed to have a middle height when viewed in a radial cross section, and two When cutting especially the middle and high parts of a valve plate that has a bulge and a flat surface for sealing formed on its outer surface, a substantially disk-shaped valve plate material is rotated in a plane that includes the valve plate surface. Straight blades are arranged at both corners of the outer periphery of the valve plate material at an angle so that their positions are outside the radius of rotation of any part of the outer end of the bulge. It is characterized by cutting continuously over the entire circumference.

With this configuration, even if there is a bulge for supporting the valve shaft on the outer circumference of the valve plate, only the outer periphery of the part other than the bulge can be continuously machined to a medium height. becomes possible.

(Explanation of Examples) FIG. 3 shows the thin wall portion 33 when the valve plate material for configuring the valve plate as shown in FIG. 1 is rotated.
The outer peripheral portions of the bulge portion 32 and the bulge portion 32 are shown by two-dot chain lines, respectively.

In the illustrated example, the outer periphery of the thin walled part of the valve plate material is flat, but this part may have been formed into a raised shape from the beginning, but in any case, there is no essential difference. .

From the outside of the thin walled part of the valve plate material rotating as described above, from the outside (from above in the drawing) with a cutter (not shown) arranged at a predetermined angle inclination with respect to the axis of rotation,
One corner of the thin-walled portion is cut one after another, and the machining is stopped when a position C1, indicated by reference numeral 32 in the figure, does not collide with the rotation locus of the bulge.

Next, change the angle and position of the cutter and cut the other corner to the position C2 in the figure.

By cutting in this way, the cutter does not come into contact with the bulge 32 during processing, so
The periphery can be formed into a medium-height shape by continuously rotating the valve plate.

When the above processing is completed, slopes 35 and 34 are formed on the periphery of the thin portion 33 of the valve plate material by chain lines C1 and C2, as shown in FIG.
The overall shape will be medium-high.

In the illustrated example, there is a flat part 36 between both slopes, but this part does not need to be formed in particular. The joint has a sharp edge, and there is a risk that this part may bite the seat ring after the valve is assembled. Therefore, as shown in Figure 5, use a smooth concave cutter to smooth the joint. It is well known that it is preferably formed into a curved line.

In the above embodiment, the middle and high portions of the valve plate periphery were cut twice with a straight cutter, but it is also possible to form the middle and high edges in one operation using a concave arc cutter. would be easy to understand.

(3) Effects of the Invention Since the present invention has the configuration described above, it includes a bulge for supporting the valve stem in the diametrical direction;
When manufacturing a valve plate for a butterfly valve that has flat parts for axial sealing on both ends, the outer periphery of the valve plate is removed from the processing equipment and its rotation is stopped at the position where the bulge exists. Since this type of valve plate can be processed continuously without any problems, this type of valve plate can be processed extremely quickly and easily, which greatly contributes to cost reduction.

[Brief explanation of the drawing]

Fig. 1 is a front view of a valve plate to which the present invention is applied, Fig. 2 is a plan view of the same as above, Fig. 3 is an explanatory diagram for explaining the present invention, and Fig. 4 is a valve plate formed according to the present invention. FIG. 5 is a radial sectional view of the valve plate showing the peripheral edge, and FIG. 5 is a radial sectional view showing the shape of the valve plate with the upper chamfered. 1... Valve plate, 2... Plane part, 32... Swelling part,
33...Thin section.

Claims (1)

[Claims] 1. A thin valve plate material having a substantially disc-shaped thin wall portion, a bulge portion for supporting the valve shaft in the diametrical direction of the thin wall portion, and a sealing flat portion continuous to the thin wall portion at both ends of the bulge portion. In order to form the outer periphery of the thin part into a medium-height shape when viewed in radial cross section, the thin part is rotated in its plane about the center of the disc-shaped thin part, and a linear cutter is attached to the outer periphery of the thin part. Continuously cutting only the thin-walled portion by tilting the thin-walled portion so that its center surface side has a larger diameter when viewed from the rotational axis of the valve plate material when viewed in the thickness direction of the thin-walled portion, and displacing the thin-walled portion within a range that does not contact the bulge. How to make a valve plate for a central butterfly valve.