First, the force analysis of the sealing ring is carried out to determine the type, magnitude and direction of the force when the mechanical sealing ring is in the working state, and then the specific pressure of the sealing end face can be calculated. The O-ring moving ring is exposed to the medium
The mass pressure Fp, the liquid film pressure Fm and the spring force Ft, the sealing ring also acts on the friction force R.
Among the above forces, the spring force Ft and the medium pressure Fp are in the same direction, both of which act to close the sealing surface, so they are called closing forces. The action of the liquid film pressure is to open the sealing end face, which is called the opening force, and the friction force is usually small enough to be ignored. In order to overcome the friction of the auxiliary seal and the rotational inertia of the moving ring, a certain pressure of the sealing surface must be maintained, and the most appropriate spring specific pressure must be carefully selected.
Loosening occurs for many reasons, such as the flame leaving the molten pool too quickly. When repairing the pores, due to carelessness, dense small holes will be found after processing. Loosening can occur if the flame is not handled stably, moved position, or burnt on the weld pool when changing the wire. The measure to exclude is to re-melt with flame. There are three reasons for the uneven hardness. One is that the local matrix is overburned, and a large amount of matrix metal enters the molten pool. One is that the welding gas supply is unstable during oxyacetylene welding, and the flame core of the flame enters the molten pool to increase the carbon content.
The measures taken are mainly to stabilize the flame and operate in strict accordance with the operating instructions. In order to obtain a valve surfacing surface that meets the design and use requirements, it is necessary to strictly follow the requirements in the formulation of work instructions and operations. Although the current main surfacing methods include oxygen-acetylene welding, argon arc welding, manual arc welding and other welding methods, there are many types of welding defects, but as long as they master their operation rules and the reasons for the defects, they can be formulated in the process. and operation to reduce and avoid the occurrence of these defects.