Valve manufacturing process characteristics
Lead: The first few valve parts, simple structure, accuracy in general, are simple parts in the machinery industry, but the valve core sealing parts are particularly demanding. Valve manufacturing process is complex, technical difficulty is also large, which process characteristics we need to pay attention?
1. Make the material
Due to the wide range of valve specifications, the application of the valve in various fields of national economy, its use varies widely, such as high temperature and pressure, cryogenic cryogenic, flammable, highly toxic and corrosive media and other working conditions, the material of the valve Harsh requirements.Control Valve, Flow Control Valve, Hydraulic Control Valve, Proportional Directional Control Valve
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.
Casting rough structure
Most of the valve blank is a complex structure of the shell casting, not only requires a good appearance quality, but also have a dense inner quality and good metallurgical structure, can not have pores, 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. Machining process
Because most of the high strength, high hardness, high corrosion-resistant materials, cutting performance is not good, such as high-alloy stainless steel, acid-resistant steel has a toughness, high strength, heat dissipation, chip viscosity and work hardening tendency and other shortcomings, Difficult to meet 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. Valve parts of the process
The small number of the main parts of the valve, 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. Valve test and inspection
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 cryogenic, flammable, highly toxic and highly corrosive. 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.
Looked at the characteristics of the valve manufacturing process, have not been shocked yet? Up knowledge it! ! ! Looks like a simple valve, it is actually not so easy to create? So, how the valve step by step to create ... ... valve manufacturing process
The first step: the valve body manufacturing
Valve body (casting, sealing surface surfacing)
Casting procurement (by standard) ➱ factory inspection (by standard) ➱ pile welding ➱ ultrasonic flaw detection (by design) ➱ surfacing and post-weld heat treatment ➱ finishing ➱ grinding sealing surface ➱ seal hardness testing, coloring inspection.
The second step: valve trim manufacturing process
A, the inner surface of the sealing surface to be welded, such as disc, seat and so on
Raw material procurement (according to the standard) ➱ inspection into the factory (according to the standard) ➱ blank (round steel or forgings, according to the drawing process requirements) ➱ roughing ultrasonic flaw detection surface (when drawing requirements) ➱ roughing surfacing ➱ surfacing and welding After heat treatment ➱ finishing ministries ➱ grinding sealing surface ➱ sealing surface hardness testing, coloring inspection.
B, stem
Raw material procurement (by standard) ➱ Factory inspection (by standard) ➱ Production of blank (round or forgings, according to drawing process requirements) ➱ Roughing surfacing ➱ Surfacing and postweld heat treatment ➱ Finishing parts ➱ Grinding of external ➱ stem surface treatment (nitriding, quenching, electroless plating) ➱ final treatment (polishing, grinding, etc.) ➱ grinding sealing surface ➱ sealing surface hardness testing, coloring testing.
C, without welding sealing surface of the inner parts
Procurement of raw materials (by standard) ➱ factory inspection (by standard) ➱ blank (round or forgings, according to the drawing process requirements) ➱ roughing ultrasonic flaw detection (when required) ➱ finish the ministries.
The third step: fastener manufacturing
Fastener Manufacturing Standard DL439-1991.
Raw materials procurement (by standard) ➱ inspection into the factory (according to the standard) ➱ blank (round or forgings, according to the drawing process requirements) and sampling for the necessary testing ➱ roughing ➱ finishing ➱ spectrum test.
The fourth step: assembly
零 Hydrostatic test (according to drawing, process) ➱ Disassemble, wipe clean ➱ Final assembly 调 Commissioning with electrical or actuator (for electric valves) ➱ Paint Package ➱ shipping.
Step five: product production and inspection process
1, the company purchased a variety of raw materials. 2, with a spectrometer on the raw material for material testing, and print out the raw material test report for backup. 3, with the cutting machine for raw material cutting. 4, inspectors test the diameter and length of raw material cutting. 5, Forging workshop Forging raw materials for forming. 6, the inspectors for forming a variety of blank size inspection. 7, workers in the blank scrap removal. 8, sand throwing workers blank blasting surface treatment. 9, inspectors sandblasting after the surface treatment test. 10, workers rough machining. 11, the body sealing thread processing --- staff in the processing of self-test after the inspection staff on the product after processing inspection. 12, the valve body thread connection. 13, in the hole processing. 14, inspection staff to conduct a total inspection. 15, qualified semi-finished products were sent to semi-finished products warehouse. 16, semi-finished products for electroplating. 17, semi-finished plating surface treatment test. 18, all kinds of accessories (ball, stem, seal seat) inspection. 19, the assembly shop assembly of products - assembly line inspection staff to test the product. 20, the assembly of the product after pressure testing and drying into the next process. 21, the assembly shop for product packaging ---- packing line inspection staff on the product of sealing, appearance, torque testing. Unqualified products are never allowed to be packed. 22, qualified products are bagged packaging and sent to the finished product warehouse. 23, all inspection records will be classified stored in the computer for inquiries. 24, qualified products are sent to the container at home and abroad.
