Double Thread Rod,Double End Thread Rod,Double Threaded Rod,Double Nut Threaded Rod Hebei Kangjin Metal Products CO.,Ltd , https://www.kjmetalproducts.com
"M" type butterfly valve design
At present, there are many kinds of butterfly valves that are widely used in the water supply and drainage industry such as municipal, petroleum, chemical, light industry, etc. There are many kinds of butterfly valves, such as centerline type, single-eccentricity, double-eccentricity and even three eccentricities, Features: Usually have a valve cover, but also because the butterfly plate is cast iron, long-term exposure to air, water and other media, serious corrosion, polluting the environment, while the valve stem is used throughout the butterfly plate, circulation area is small, torque Too large, coupled with more valves in the parts, resulting in maintenance difficulties. "M" type butterfly valve is a new type of unique valve, which completely overcomes some of the existing technical deficiencies in the butterfly valve industry, and comprehensively improve the valve performance. Second, the structure and working principle "M" -type butterfly valve structure is simple, it is a single eccentric soft-seal butterfly valve, with upper and lower two-stage stem, butterfly plate surface with a layer of sealant, sealing the two ends of the disc surface Designed to be "M" shaped, this creates a double seal between the disc and the valve body and seals the air between the "M" seals so that the seal will be better. The valve is mainly composed of the valve body, the upper and lower stems, all-inclusive plastic valve plate, cylindrical pin and other components. The structure shown in Figure 1. Turn on the valve, with a wrench counterclockwise slowly turn the upper part of the main stem tenon, the butterfly plate and the flange perpendicular to the valve, turn the valve with a wrench clockwise slowly turn the upper part of the main stem tenon, the butterfly plate Parallel to the flange. Third, the assembly method Assembly, with kerosene cleaning all the components, the first butterfly moved to the valve body, the main valve stem surface coated with silicone grease, install the ring 2 and the "O" ring 4, so that The inner hole of the butterfly plate is connected, and then the butterfly plate is tapped with a rubber mallet so as to be fully embedded in the valve body, matched with the internally threaded cylindrical pin 5. After the test water is completed, a liquid sealant is injected into the upper end of the pin. Fourth, the performance of "M" butterfly valve butterfly valve sealing surface at both ends of the design into a "M" shape (see Figure 1), so that when sealed with the valve, forming a double seal, effectively solve the valve Opening and closing sealing surface wear problems, long service life, combined with the valve with the upper and lower two-stage stem, single eccentric structure, an increase of the valve flow area, head loss and operating torque than the same size of the ordinary butterfly valve small. Butterfly overall plastic package, does not pollute the water quality, but also protect the butterfly, especially for food and beverage industries. Stem and disc connections using the internal thread cylindrical pin, the pin end with irrigation liquid sealant, demolition and maintenance in the actual use of extremely convenient, lower production costs. V. DESIGN AND CALCULATION 1. The minimum wall thickness of "M" butterfly valve body is calculated by the formula of ASME B16.34 appendix. Eccentric butterfly valve stem torque calculation using the following formula, torque calculation diagram in Figure 2. MD = MM + MT + Mj + Md (1) where MD --- butterfly valve stem torque, in units of N · mm; MM --- sealing surface friction torque, in units of N · mm. qM --- sealing surface required specific pressure, in MPa (look-up table or calculation); R --- disc sealing radius in mm; bM --- sealing surface contact width in mm; fM - - friction coefficient between sealing surfaces (018 ~ 110 for rubber); h --- eccentricity between stem and disc center in mm; MT --- sealing packing friction torque (due to the stem with "O "Ring seal can be neglected); Mj --- hydrostatic torque in N · mm (look-up table or calculation); Md --- Moment of motion in N · mm (look-up table or calculation). 3. The thickness of the disc calculation (Figure 3) b = 01054 D3 H (3) Where b --- the maximum thickness of the disc, in mm; D --- butterfly valve flow path diameter in mm (look-up table , The general b / D = 0115 ~ 0125 (Figure 2); H --- maximum hydrostatic head (water hammer pressure medium), in units of m. H = 100 (p + Δp) Pressure (often p = PN), the unit is MPa. Δp --- butterfly valve quickly off valve, the water hammer generated in the pipeline pressure boost value in units of MPa; v --- medium flow rate, For m / h; t --- butterfly from full open to fully closed by the time (look-up table selection), the unit is s 4. Section strength check (1) butterfly A2A cross-section of the strength of the check In the σWA --- verify A2A section of the bending stress in MPa; MA --- A2A bending moment on the cross section, in units of N · mm; MA = 01113 pD31 (7) p --- design pressure P = PN), the unit is MPa; D1 --- disc outer diameter, in mm WA --- A-A section of the flexural strength of the cross-section coefficient, in units of mm3; JA --- A-A off Of the moment of inertia (look-up table or calculation) unit mm4; b --- the maximum thickness of the disc, in mm. If the actual bending stress A-A section, that is, σWA (2) B2B cross- The valve adopts upper and lower two-stage stem support, disc deformation is small, so here do not go into details. VI Conclusion "M" shaped butterfly valve design lies in the transmission member, the lower stem, body and the strength of the butterfly Calculation, as well as the body, disc, stem, pin and other parts of the rational selection and heat treatment.The valve is a single eccentric butterfly valve, torque is small, the entire surface of the butterfly plate with a sealant, sealing performance, does not pollute the environment , Disassembly and maintenance is very convenient.Driving methods are hand-type, worm-type, electric and pneumatic, etc., is a wide range of adaptable valves.