Valve assembly is the final stage in the manufacturing process. Valve assembly is the process of combining various parts and components of the valve to make it a product based on the prescribed technical premises. The whole machine is the most basic unit of valve assembly, and several parts make up the parts of the valve (such as valve cover, valve clack parts, etc.). The assembly process of several parts forming parts is called component assembly, and the assembly process of several parts and components forming a valve is called general assembly. The assembly work has a great influence on the product quality. Even if the design is accurate and the parts are qualified, if the assembly is improper, the valve will not meet the specified requirements, and even seal leakage will occur. Therefore, special care should be taken to adopt a fair assembly method to ensure the quality of the final product of the valve. The assembly process defined by the document situation in production is called the assembly process specification.
Commonly used assembly methods for valves
There are three commonly used assembly methods for valves, namely, complete replacement method, repair method and selection method.
(1) Complete interchange method: When the valve is assembled using the complete interchange 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 completely in accordance with the design requirements to satisfy the requirements of dimensional accuracy and geometric tolerances. The advantages of the complete interchange method are: assembly work is simple and economical, workers do not need a high degree of skill, the assembly process is more productive, and it is easy to organize assembly lines and organize specialized production. However, in absolute terms, when adopting a complete replacement assembly, the machining accuracy of the parts is higher. It is suitable for valves with absolutely simple structures such as globe valves, check valves, ball valves, and valves with medium and small diameters.
(2) Matching method: The valve is assembled by matching method, and the whole machine can be processed according to economic precision. When assembling, a certain size with adjustment and compensation function is selected and matched to achieve the specified assembly accuracy. The principle of the matching method is the same as that of the repair method, except that the method of changing the size of the compensation ring is different. The former is to change the size of the compensation ring by selecting accessories, and the latter is to change the size of the compensation ring by trimming the accessories. For example: the top core and adjusting gasket of the control valve type double-disc wedge gate valve, the adjusting gasket between the two bodies of the split ball valve, etc., is to choose special parts as compensation parts in the dimensional chain related to assembly accuracy. Adjust the thickness of the gasket to achieve the required assembly accuracy. In order to ensure that the fixed compensation parts can be selected in different situations, it is necessary to pre-manufacture a set of gaskets and shaft sleeve compensation parts hydraulic control valve models of different thickness sizes 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. When assembling, a certain size with adjustment and compensation function is repaired to achieve the specified assembly goal. For example, the gate plate and valve body of the wedge gate valve, because the processing cost required to realize the interchange 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 requirement. Although this method adds the plate matching process, it greatly simplifies the dimensional accuracy requirements of the previous processing process. The special personnel of the plate matching process are skillful and will not affect the production efficiency in general. Valve assembly process Valves are individually assembled on a fixed site. Valve parts and components assembly and general assembly are carried out in the assembly workshop, and all required parts and components are transported to the assembly site. Usually component assembly and total assembly are distinguished by how many groups of workers are performed 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 skill level of workers are relatively low.
Some foreign manufacturers or high-tech valves also adopt the mode of assembling the suspension line or assembling the rotary table.