JPH0233494B2 - CHOGATABENNOSHIITORINGUSEIKEIHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of forming a seat ring for use in a butterfly valve.

A seat ring made of an elastic material such as rubber is stretched around the inner circumference of the valve body, and when the valve is closed, this seat ring is compressed between the valve body and the outer circumference of the valve plate to create a sealing effect. In the well-known post-shaped valve, the rebound elasticity of this seat ring is adjusted,
In order to substantially reinforce the seat ring, seat rings having a rigid material such as a metal ring encapsulated therein have been widely used. FIG. 1 shows an example of such a seat ring, in which an annular core metal 12 made of a rigid material is enclosed inside the inner surface of a valve body 2 shown by a chain line, and an elastic material 11 such as rubber is enclosed on the outside. A seat ring 1 covered with is stretched.

In order to form such a conventionally known seat ring, as shown in FIG.
An annular cavity is formed between the inner mold and an inner mold 4 corresponding to the core, and the inner mold has pins 5 and 6 at diametrically opposed positions for forming a hole through which the valve stem is inserted. The core bar 12 mounted on the pin is disposed within the annular cavity. Note that FIG. 2 is a cross section showing a location on the mold side corresponding to the position indicated by the line XX in FIG. 1.

After the core metal is arranged in this way, elastomer is injected into the annular cavity.In order to accurately position and hold the core metal 12, the core metal is inserted from the outer mold 3 as shown in FIG. It is common practice to perform molding work by arranging pins 7 and 8 that reach up to .

However, if such a molding method is used,
Naturally, holes will remain in the seat ring after molding at the locations corresponding to pins 7 and 8, and if left as is, the core bar will be exposed to the outside air and have a negative impact on the life of the seat ring. It would be possible to fill it up after molding, but this is not preferable as it increases the cost.

Furthermore, the accuracy of positioning the core metal in the cavity within the mold is affected by the accuracy of the pins 7 and 8 or the accuracy of the matching holes on the core metal side, and this adjustment is difficult.

Furthermore, the core metal portion located between the pins may be locally distorted due to the injection pressure of the elastomer. To prevent this, pins 7 and 8
Although it is possible to increase the number of core metal means members corresponding to , it is undesirable as described above because a correspondingly large number of holes remain on the outer surface of the seat ring after molding.

This invention was made in view of the above-mentioned defects in the known seat ring forming method, and the core metal part between the pins 5 and 6 for forming the valve shaft insertion hole is provided with appropriate elasticity. The elastomer is injection molded by arranging an appropriate number of the support members provided, and after molding, the support members are used as they are as part of the seat ring material 11, thereby solving the drawbacks of the known molding method as described above. The aim is to provide a molding method that

FIG. 3 is an explanatory view of a mold showing the molding method according to the present invention, and in this figure, the same parts as in FIG. 2 are given the same reference numerals. As shown in FIG. 3, a support member 9 made of, for example, phenol resin and having appropriate elasticity is attached to the outer periphery of the core metal 12, which is supported by pins 5 and 6 in the annular cavity inside the mold. A plurality of them are attached to support and position the core metal. These support members 9 are
The outer mold 3 shall be installed as shown in the figure when the upper and lower molds are open, and its height (height in the direction perpendicular to the page) is slightly higher than that of the annular cavity. The support member is made large so that when the upper and lower molds are closed, each support member is compressed by the mold. For this reason, when the mold is closed, the support member is pressed by the mold from a direction perpendicular to the plane of the paper and tends to expand in a direction parallel to the plane of the paper. It will be firmly pressed inward and firmly hold its position.

After elastomer injection molding, the support member 9 may be used as a part of the seat ring material without being removed.

Since the present invention has the above configuration, the holes formed by the support pins 7, 8, etc. in the above-mentioned known means do not remain after molding, and the support member 9
Since a large number of pins 7 and 8 can be arranged around the core metal, the core metal parts in areas where no pins are present will not be locally deformed, unlike when a small number of pins 7 and 8 are used. Since rigid materials are not mechanically joined to each other unlike in the case of joining the metal core with the metal core, there is no possibility of positioning misalignment of the metal core due to mechanical error.

Furthermore, in the present invention, the support of each support member and the pressing action on the core metal are achieved by using a pressing force applied in a direction perpendicular to the plane on which the core metal exists (a plane parallel to the plane of the paper). This is an extremely effective invention, as it allows for accurate positioning without causing any shift in the position of the core metal.

FIG. 4A shows another embodiment of the present invention, in which a portion of the elastic support member 9 is engaged with a recess 41 formed at a predetermined position in the outer mold 3. . With this configuration, the support member does not move unnecessarily within the mold, and after molding, this part protrudes from the outer circumferential surface of the seat ring, which locks the seat ring to the valve body. Become a guide in case.

In FIG. 4B, a protrusion 42 is formed on the outer mold 3 at a portion where the support member 9 is located, and protrudes inward into the cavity. This prevents the support member from protruding from the outer peripheral surface of the seat ring after molding.

In addition, when the supporting members 9 are arranged as shown in the third figure, it is of course possible to arrange the supporting members at opposite positions of each supporting member on the opposite side of the core bar.
This allows for more accurate positioning of the core metal.

Furthermore, in order to improve the positioning accuracy of the support member, it is also possible to form a recess corresponding to the recess 41 for receiving the support member 9 on the outer peripheral surface of the core bar 12 as shown in FIG. 4A. .

FIG. 4c shows still another embodiment of the present invention, in which a plurality of through holes are provided in the core metal 12, and the support member 9 is penetrated through the core metal 12 to allow both the inner and outer metal members to pass through the core metal 12. The supporting member is supported by the mold surface, and since the supporting member is supported by both end faces thereof, it has the effect of improving the supporting accuracy. In this case as well, the length of the support member 9 is such that it does not reach the inner mold 3, or the support member 9 is made to have a length that does not reach the inner mold 3, or a support member 9 is provided on the outer mold side of these materials for stabilizing support as shown in FIG. 4A. Of course, it is also possible to add means.

Furthermore, pins made of a rigid material are inserted into each of the supporting members 9 in FIGS. 3, 4A, B, and C from the outside of the outer mold 4 as shown by dotted lines in FIG. 4C. The configuration may be such that the positioning of the support member is reinforced.

[Brief explanation of drawings]

Fig. 1 is a partially cut-away perspective view showing the configuration of a typical known seat ring, Fig. 2 is a plan sectional view showing a seat ring molding method using a known mold for forming the seat ring, and Fig. 3 4A and 4B are plan sectional views showing the seat ring forming method according to the present invention,
and C are plan sectional views of essential parts showing other embodiments of the present invention. 1... Seat ring, 2... Valve body, 3... Outer mold, 4... Inner mold, 5, 6... Valve stem hole forming pin, 7, 8... Support pin, 9... Support Part, 12
... Core metal.

Claims (1)

[Claims] 1. Forming an annular cavity between the outer mold and the inner mold,
An annular core metal is supported in this space by a pair of pins for forming a valve shaft insertion hole, and at least a portion of the core metal that is not supported by the pins is formed between the core metal and the circular wall surface on the outer mold side. A plurality of support members made of an elastic material are inserted in between, and each support member is pressed and compressed when the upper and lower molds forming the outer mold are closed to form the annular cavity. A method of forming a seat ring for a chiseled valve in which the member is pressed in the direction of the core metal.