The independent valve seat of the globe valve is usually connected by welding. Because the welding rod should go deep into the valve body during welding, the convenience of welding must be considered when designing the valve seat fitting surface. According to the past experience, two structures are recommended for reference. One is to weld from the top with an oblique angle (see Fig. 1), and the welding rod is welded in a circle at the bottom of the inclined angle. The other method is to groove the bottom of the valve seat (see Fig. 2), and the electrode goes deep into the bottom of the groove for circumferential welding. According to the existing equipment and welding process, more favorable ways can be adopted for specific application.
Due to the change of valve installation mode, the sealing performance of the valve may be affected. When designing the valve, it is usually necessary to design the valve disc guiding mechanism. If the guide rib is added to the valve body to guide the valve disc, the setting of the guide rib should avoid the processing part of the valve seat. As shown in Fig. 3, there should be a certain distance between the machined surface and the guide rib to avoid interference with the cutting tool. This distance generally needs to be more than or equal to 20 mm.
Because the casting surface is rough and uneven, the flange nut supporting surface plays a role in supporting the nut smoothly. The machining of the supporting surface is generally the turning plane on the back of the flange until the turning surface can easily place the nut. When the tool can not enter into the machining surface for machining, the countersink processing is adopted (see Fig. 4).
The application of CAD software greatly shortens the design cycle of pump products. With the development of pump industry, the requirement of pump CAD technology is higher and higher. However, the current domestic pump CAD software still relies on the secondary development technology of foreign commercial CAD software, and is restricted by the copyright and the open application program interface of the dependent software, and its functions are relatively limited. Some foreign design softwares, such as cfturbo and bladegen, are based on independent three-dimensional platform, and their modeling is more free. There is a significant gap between domestic and foreign pump CAD technology.
