A valve is a device used to control the direction, pressure, and flow of a fluid in a fluid system. It is a device that allows the medium (liquid, gas, powder) in the piping and equipment to flow or stop and can control its flow. The application range of the valve is very wide. Wide so it is particularly important for the carbide processing of the valve .
The valves used in the fluid control system, from the simplest globe valve to the various valves used in the extremely messy automatic control system, have quite a variety of varieties and specifications, so the statements are not completely consistent, and some are classified according to their uses and effects ( Cut-off valves, regulating valves, check valves, diverter valves, safety valves), some are classified according to their valve body data (non-metallic data valves, metal data valves, metal body lined valves), but currently The most commonly used classification methods in the world and domestic are methods that are divided according to principle, effect and structure. Generally, they are divided into gate valves, globe valves, throttle valves, surface valves, plunger valves, diaphragm valves, plug valves, ball valves, butterfly valves and check valves. Back valve, relief valve safety valve, steam trap, regulating valve, bottom valve, filter, sewage valve, etc., hard alloy processing.   
No matter what kind of valve includes the above three valves, if the valve body and other parts are purchased castings or forgings, they must be rigorously inspected before entering the factory, and the castings that pass the inspection will be repaired again before entering the workshop. It is to repair some shortcomings on the casting. The repaired castings enter the workshop, and the castings such as valve bodies, valve covers or seals are processed on specific machine tools. During this period, the seal castings are divided into hard seal and soft seal processing according to the sealing method. Hard seal means that both sides of the seal pair are metal materials or other hard materials. The sealing function of this kind of seal is poor, but it has high temperature resistance, wear resistance, and good mechanical function; soft seal means that both sides of the seal pair are metal materials, and the other side is elastic non-metallic materials. This kind of seal has a good sealing function, but it is not resistant to high temperature, easy to wear, and has poor mechanical properties. The castings with hard seals are the same as other castings. After turning, they are drilled, milled and inserted, deburred and polished, and then they can be cleaned and blown dry. After anti-rust treatment, they are stored in the warehouse and wait for assembly. After the turning process of the soft seal seal casting, it must also be surfacing, finishing, drilling, milling, inserting, deburring and grinding, and sealing surface grinding before cleaning, blowing and anti-rust, and then waiting for assembly in the warehouse. The reason why the seals of the soft sealing method must be welded is to make the appearance of the seals wear-resistant, heat-resistant or corrosion-resistant, add external hardness and wear resistance, and improve the service life.

Valve body manufacturing
Valve body (casting, surfacing of sealing surface)
Casting purchase (according to specifications), factory inspection (according to specifications), ultrasonic inspection of surfacing welds (according to the drawings), surfacing welding, post-weld heat treatment, finishing, grinding, sealing surface, hardness inspection, color inspection.

Step 2: Manufacturing process of valve trim
A. Internal parts that need to be welded on the sealing surface, such as discs, valve seats, etc.
Raw material acquisition (according to specifications), factory inspection (according to specifications), manufacturing blanks (round steel or forgings, according to drawings and process requirements), rough machining, ultrasonic flaw detection surface (when drawings are required), rough machining, surfacing welding, surfacing welding, and post-welding heat treatment finishing Check the hardness of the sealing surface of the grinding sealing surface of each part, and color the flaw detection. B. Valve stem
Original material acquisition (according to the specifications), factory inspection (according to the specifications), manufacturing blanks (round steel or forgings, according to the drawing process requirements), hard alloy machining, surfacing welding, surfacing welding, post-weld heat treatment, finishing, grinding of the outer stem Treatment (nitriding, quenching, electroless plating) Zui final treatment (polishing, grinding, etc.) Grinding sealing surface Seal surface hardness inspection, color inspection.
C. Internal parts that do not need to be welded on the sealing surface, etc.
The original materials are purchased (according to the specifications) and inspected (according to the specifications) to manufacture the rough (round steel or forgings, according to the drawings and process requirements), rough machining the ultrasonic flaw detection surface (when the drawings are required), and finishing the various parts.

The third step: fastener manufacturing
Fastener manufacturing specification DL439-1991.
The original materials are purchased (according to the specifications), inspected (according to the specifications) to manufacture the blanks (round steel or forgings, according to the drawings and process requirements), and take samples to carry out the necessary inspections, roughing, finishing, and spectral inspection.
At first glance, there are not many valve parts, simple structure, and general accuracy. In the mechanical industry, they are classified as simple parts, but the core sealing parts of the valve are particularly demanding. The valve manufacturing process is messy and the skills are difficult. What process characteristics should we pay attention to?　
Carbide valve processing

1. Manufacturing Information
Because of the wide variety of valve specifications, for example, general valves have gate valves, globe valves, check valves, ball valves, butterfly valves, hydraulic control valves; industrial valves have special valves such as solenoid valves, regulating valves, pressure reducing valves, high-temperature high-pressure valves, low-temperature valves, etc. They are used in various fields of the national economy, and their application occasions are very different, such as high temperature and high pressure, low temperature and deep cold, flammable and explosive, highly toxic, strong corrosive media and other working conditions, which put strict requirements on the raw materials of the valve.
In addition to cast iron, carbon steel, alloy structural steel, a large number of CrNi stainless steel, CrMoAl nitriding steel, CrMoV heat resistant steel, CrMnN acid resistant steel, deposition hardening steel, duplex stainless steel, low temperature steel, titanium alloy, Monel alloy , Inconel, Hastelloy and G0CrW cemented carbide. The casting, welding and processing functions of these high-alloy materials are very poor, which brings great difficulty to the manufacturing process. In addition, most of these materials are valuable materials with high alloy, high strength and high hardness. There are many difficulties in the selection, preparation and acquisition of materials. Some materials are difficult to purchase and supply because of the small amount of use.

2. The structure of the casting blank
Most of the valve blanks are made of thin shell castings with messy structure, which not only requires outstanding appearance quality, but also fine internal quality and excellent metallographic structure, and cannot have defects such as pores, shrinkage holes, sand inclusions, cracks, etc. . Therefore, the casting process is messy and the heat treatment skills are difficult. In the machinery industry, it is more difficult to cast the blank of the pressure-bearing thin shell casting of the valve than the casting of other mechanical components.　　

3. Mechanical processing technology
Because the cutting function of most high-strength, high-hardness, and high-corrosion-resistant materials is not good, such as high-alloy stainless steel and acid-resistant steel have the disadvantages of high resistance, high strength, poor heat dissipation, high chip stickiness, and strong work hardening tendency. It is difficult to reach the required scale accuracy and finish, which brings certain difficulties to the machined tools, processes and equipment cemented carbide. In addition, the valve sealing surface has high requirements on machining accuracy, cooperation angle, smoothness and matching sealing pair, which brings great difficulty to mechanical processing.

4. Process organization of valve parts
The main parts of the valve are not many, the structure is relatively simple, the processing accuracy of most scales is not high, and the exterior is relatively rough, which gives people an image attributed to simple machinery. In fact, the heart sealing part of the valve is extremely delicate. The "three degrees" (flatness, smoothness, hardness) of the sealing surface is very high, and the matching degree of the sealing pair composed of the two sealing surfaces must reach zero to zero. Ability to be satisfied with zero leakage in airtight experiments. This kind of rough reference to ensure the precise zero-to-zero requirements of the heart part is a major difficulty in valve processing.