JPH0438949B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) This invention relates to improvements in ceramic ball valves used under high temperatures and high pressures. (Prior Art) Conventionally, ball valves used to control high-temperature, high-pressure fluids are either entirely made of metal or, as shown in Figure 4, are approximately spherical and have a fluid through hole B in the center. The ball valve A is made entirely of ceramic, and the protrusion C and the recess are fitted so as to be connected to the drive lever on the upper part of the ball valve part, or only the protrusion C on the upper part of the ball valve part is made of metal. There are ceramic ball valves that have been changed to . (Problems to be Solved by the Invention) However, in conventional ball valves, for example, ball valves made entirely of metal,
When used under high pressure conditions, the compressive load applied to the ball valve body through the seat increases significantly, causing uneven deformation, impeding sealing performance, and causing abnormal wear of the ball valve due to the seat. In addition, instead of a metal ball valve that is relatively weak against high pressure, in the case of a ball valve made only of ceramic, which is lightweight and can withstand high temperature and high pressure, the engagement part and drive provided on the upper part of the ball valve body. In the lever-side engaging portion, cracks are likely to occur from the end portion of the engaging portion, which may make normal rotation impossible. Furthermore, in order to solve this drawback, the engaging part is made of metal and is joined to the ceramic ball valve body.
This has the disadvantage that residual stress may cause cracks in the ceramic surrounding the metal engagement portion, and the joint portion with the ceramic ball valve may peel. Therefore, the present invention aims to improve the drawbacks of the above-mentioned conventional valves and to provide a ceramic ball valve that is lightweight and has excellent pressure resistance. (Means for solving the problem) For this purpose, in a ceramic ball valve, a slit is provided at the base of the metal engagement part that is joined to the upper part of the main body, that is, at the joint part with the ceramic, from both ends along the joint surface. , which is engaged with the drive lever side engagement portion. (Function) In a ball valve, the compressive load of the high-pressure fluid acts on the ball valve through the seal part that contacts the outside of the through hole through which the high-pressure fluid passes.The ball valve is rotated against this compressive load and the through hole is closed. By positioning the high-pressure fluid at a certain angle with respect to the inlet of the high-pressure fluid and providing a slit in the engaging portion that suppresses the inflow of fluid, the compressive load of the high-pressure fluid is transferred through the small-diameter portion of the slit. By absorbing the above-mentioned load in the small diameter part and the metal part of the joint, the effect of the load on the joint between the metal engagement part and the ceramic ball valve body is alleviated. It is possible to prevent cracks occurring in the ceramic around the joint portion due to bonding residual stress, and by constructing the ball valve with ceramic, it is possible to prevent deformation of the ball valve due to high pressure fluid. (Example) This invention will be further explained with reference to an example shown in the drawings. Reference numeral 1 is a ceramic ball valve of the present invention, and reference numeral 2 is an engaging portion made of a sintered metal such as cermet or heavy metal. 3 is a slit along the joint surface provided near the joint between the metal engagement portion and the ceramic ball body 5, and 4 is a through hole through which high-pressure fluid flows. If the depth l of the slit 3 shown in FIG. 10 to 30% of the joint diameter is appropriate. or,
The shape of the tip of the slit is preferably approximately R-shaped in order to avoid concentration of stress, and the thickness t of the slit 3 is preferably as small as possible with respect to the height of the engaging portion, but from the viewpoint of processing possibilities, it is preferably 50% or less. . Therefore, in order to confirm the strength of the ceramic ball valve with this slit inserted, the depth l of the slit was set so that the engaging part 2 was in the left-right direction, and a constant compressive load P was applied to the top and bottom through the seat 6. (Figure 3) Table 1 below shows the test results of the breaking load of the engaging portion in that state.

[Table] The test results show that the strength of the ball valve with slits 3 is significantly improved compared to the ball valve without slits. Figure 2 shows a sample in which a cemented carbide shaft is joined to the drive part, the thickness of the joint part is t = 1 mm, the diameter d ₂ = φ = 12 mm, 9 mm, 7 mm and slits 3 are made. Table 2 shows the results of examining the fracture strength of the slit diameter.

[Table] As is clear from the test results, it was confirmed that the strength of the specimen with slits was hardly reduced compared to the specimen without slits.
As mentioned above, by making the slit at the base of the joint, the strength against the residual stress of the joint is clearly improved. Furthermore, by relaxing the tensile force, a metal ball valve can be deformed uniformly and good contact with the seat can be maintained. (Effects of the invention) As described above, it prevents the decrease in strength that occurs in conventional valve balls, prevents cracks due to bonding residual stress that occurs at the joint between the metal protrusion and the ceramic ball valve, and always maintains the optimal It has an excellent effect of maintaining rotation.

[Brief explanation of drawings]

Figures 1a, b, and c are a cross-sectional view, a top view, and a perspective view of an embodiment of the invention, respectively;
The figure is a perspective view of the sample. FIG. 3 shows an apparatus for testing breaking strength according to the present invention, and FIGS. 4a, b, and c show conventional devices. 1... Ceramic ball valve, 2... Metal engaging portion, 3... Slit, 4... Through hole, 5...
Ball valve body.

Claims (1)

[Claims] 1. An engaging part made of metal is joined to the upper part of a ball valve body made of ceramic having a through hole in the center, and a part of the engaging part made of metal near the joining surface with the ball valve body is A ceramic ball valve with a slit along the joint surface in the engaging part itself. 2. The ceramic ball valve according to claim 1, wherein the depth of the slit is 30% or less of the shaft diameter of the metal engaging portion.