What are the characteristics of the valve stem? How does the valve stem operate? Let's take a look at it with the valve stem manufacturer. The valve stem is used to open and close the parts and transmit the sealing force. the opening and closing action of the valve is realized by the power plant, the stem and the stem nut. The valve stem not only bears the axial force, but also bears the torque of the transmission mechanism, and its force is more complex.

The valve stem is a shaft part whose length is greater than its diameter. It is generally composed of outer cylinder, external thread, outer conical surface and outer four aspects. According to the different end structure, the valve stem can be divided into two forms with sealing cone and without sealing cone. Although the structure of the valve stem is different, it also has its common characteristics.

1, high degree requirements: the valve stem has an outer cylindrical surface with high roughness requirements. The outer cylinder surface of the valve stem is in close contact with the packing. In order to prevent the valve stem from scratching the packing during rotation or axial movement, and to ensure the seal between the stem and the packing, the roughness of the outer cylinder is required to be high, generally Ra3.2~0.8um.

2, with external thread: except for the stem of individual valves such as ball valve, most of the stem has external thread. The external thread is used to convert the rotational motion of the power plant or transmission into the axial movement of the valve stem to realize the opening and closing of the valve. In order to withstand a large axial load, the valve stem usually uses a single standard trapezoidal thread.