Valve manufacturing process characteristics
At first glance, there are not many valve parts, the structure is simple and the precision is general. It belongs to a simple part in the machinery industry. However, the core sealing part of the valve requires a very high degree. The sealing anastomosis must be zero to zero to achieve zero leakage of the airtight test. So its manufacturing process is complex, technical difficulty is also large, has the following characteristics:
(1) Speaking from the manufacturing materials, due to the wide range of valve specifications, the valves are used in various fields of the national economy with varied uses, such as high temperature and pressure, cryogenic cryogenic, flammable, highly toxic and highly corrosive media Conditions conditions, the valve material made of harsh requirements. In addition to cast iron, carbon steel, alloy steel, but also extensive use of CrNi stainless steel, CrMoAl nitrided steel, CrMoV heat-resistant steel, CrMnN acid-resistant steel, precipitation hardened steel, duplex stainless steel, low temperature steel, titanium, Monel alloy , Due to Cornell alloy, Hastelloy and G0CrW cemented carbide. These high-alloy materials, casting, welding, processing performance is poor, to the manufacturing process has brought great difficulty. Coupled with these materials are mostly high alloy, high strength, high hardness of precious materials, from the material selection, preparation, procurement, there are many difficulties. Some materials due to the use of small, difficult procurement procurement.
(2) From the structure of foundry blanks, most of the valve blanks are made of thin-walled castings with complicated structure, which not only requires good appearance quality, but also has a dense intrinsic quality and good metallurgical structure, and can not have Porosity, shrinkage, sand, cracks and other defects. Therefore, its casting process is complex, heat treatment technology is difficult. In the machinery industry, it is more difficult and harder to cast the valve bearing shell castings than other mechanical components.
(3) From the machining process, most of the high strength, high hardness, high corrosion resistance of the cutting performance of materials are not good, such as high alloy stainless steel, acid-resistant steel with toughness, high strength, heat dissipation, chip Sticky and processing hardenability tendency and other shortcomings, it is difficult to achieve the required dimensional accuracy and finish, to the machining of tools, processes and equipment to bring some difficulties. In addition, the valve sealing surface in the machining accuracy, with the angle, finish and matching the requirements of the pair is also very high, to bring great difficulty machining.
(4) From the technical aspects of the valve parts, the main parts of the valve is small, the structure is relatively simple, most of the size of the machining accuracy is not high, the external rough, which gives the impression of a simple mechanical. In fact, the heart of the valve sealing parts but extremely sophisticated, the sealing surface of the "three degrees" (flatness, finish, hardness) demanding, and the sealing surface of the two sealing surface of the fit must reach zero to zero, To meet the airtight test of zero leakage. This rough benchmark to ensure that the precision of the heart of the zero-to-zero requirements, the valve is the largest processing difficulties.
(5) From the valve test and inspection, the valve is an important opening and closing of the pressure pipe, regulating components, and the use of pressure pipe conditions vary, high temperature and pressure, cryogenic, flammable, highly toxic corrosion. However, the valve manufacturing test and inspection conditions can not meet the same requirements of the working conditions, international and domestic standards for testing various valves are close to room temperature conditions, the use of gas or water as a medium for testing. This there is a fundamental risk, that is, the normal factory test valve products, under harsh real conditions may result in material selection, casting quality and seal damage and other problems and difficult to meet the requirements, but also a significant The quality of the accident. No wonder some old valve experts who worked for a lifetime, the older the more formal, the more dry the more worried.
Heat Transfer,Hing Speed Rolling,Big Roller
Printing Machine, Embossing Machine,Pleating Machine Co., Ltd. , http://www.nsprintingmachine.com
没有评论:
发表评论