There are three commonly used assembly methods for valves, namely the complete replacement method, the repair method, and the matching method.
1 Complete interchange method
When the valve is assembled by the completely interchangeable method, each part of the valve can be assembled without any trimming and selection, and the assembled product can meet the specified technical requirements. At this time, the valve parts must be processed in full accordance with the design requirements to meet the requirements of dimensional accuracy and geometric tolerance. The advantages of the complete interchange method are: the assembly work is simple and economical, the workers do not need a high level of skill, the production efficiency of the assembly process is high, and it is easy to organize the assembly line and organize specialized production. However, absolutely speaking, when the assembly is completely replaced, the machining accuracy of the parts is relatively high. It is suitable for valves with relatively simple structures such as globe valves, check valves, ball valves, as well as valves with medium and small diameters.
2 Matching method
The valve is assembled by the matching method, and the whole machine can be processed according to economical precision. During assembly, a certain dimension with adjustment and compensation function is selected to achieve the specified assembly accuracy. The principle of the matching method is the same as that of the repairing method, but it is different in the way of changing the size of the compensation ring. The former uses the method of selecting accessories to change the size of the compensation ring, and the latter uses the method of trimming the accessories to change the size of the compensation ring. For example, the top core and the adjustment gasket of the control valve type double gate wedge gate valve, the adjustment gasket between the two bodies of the split ball valve, etc., are chosen special parts as compensation parts in the dimension chain related to the assembly accuracy. Adjust the thickness of the gasket to achieve the required assembly accuracy. In order to ensure that the fixed compensator can be selected in different situations, it is necessary to pre-manufacture a set of gaskets and shaft sleeve compensator hydraulic control valve models of different thicknesses for selection during assembly.
3 Repair method
The valve is assembled by the repair method, and the parts can be processed according to economic precision. During assembly, a certain dimension with adjustment and compensation effect is repaired to achieve the specified assembly goal. For example, for the gate plate and valve body of the wedge gate valve, because the processing cost of realizing the interchange requirements is too high, most manufacturers use the repair method. That is, in the final grinding of the gate sealing surface to control the opening size, the plate should be matched with the opening size of the valve body sealing surface to achieve the ultimate sealing requirements. Although this method increases the plate matching process, it greatly simplifies the dimensional accuracy requirements of the previous processing process. The skilled operation of the plate matching process will not affect the production efficiency in general. Valve assembly process: Valves are individually assembled on a fixed site. The parts, components, and general assembly of the valve are carried out in the assembly workshop, and all the required parts and components are transported to the assembly site. Usually, the assembly of components and the general assembly are distinguished by how many groups of workers are carried out at the same time, which not only shortens the assembly cycle, but also facilitates the application of special assembly tools, and the requirements for the technical level of the workers are relatively low.
Some foreign manufacturers or high-tech valves also adopt the mode of assembling suspension lines or assembling rotary tables.