Regarding the production process and function of industrial flanges

First, the production process of flanges
The forging process generally consists of the following steps: selecting high-quality steel billets, heating, forming, and cooling after forging. Forging methods include free forging, die forging, and mold forging. During production, different forging methods are selected according to the size of the forging and the production batch.

(1) Free Forging
Free forging has low productivity and a large machining allowance, but the tools are simple and versatile, so it is widely used for forging simple single-piece and small-batch forgings. Free forging equipment includes air hammers, steam-air hammers, and hydraulic presses, which are suitable for the production of small, medium, and large forgings, respectively. Die forging has high productivity, simple operation, and is easy to mechanize and automate. Die forgings have high dimensional accuracy, small machining allowance, and a more reasonable fiber structure distribution, which can further improve the service life of parts.

Basic steps of free forging: In free forging, the shape of the forging is gradually forged from the billet through some basic deformation steps. The basic processes of free forging include upsetting, drawing, punching, bending, and cutting.
1. Upsetting: Upsetting is the process of forging the original billet axially to reduce its height and increase its cross-section. This process is commonly used for forging gear blanks and other disc-shaped forgings. Upsetting is divided into full upsetting and partial upsetting.
2. Drawing: Drawing is a forging process that increases the length of the billet and reduces its cross-section. It is usually used to produce shaft blanks, such as lathe spindles and connecting rods.
3. Punching: A forging process that punches through or through holes in the billet using a punch.
4. Bending: A forging process that bends the billet into a specific angle or shape.
5. Twisting: A forging process that rotates one part of the billet relative to another part at a specific angle.
6. Cutting: A forging process that divides the billet or removes the sprue.

(2) Die Forging
Die forging, also known as die forging, involves placing a heated billet into a die fixed on a forging machine and forging it into shape.
1. Basic Die Forging Process
The die forging process includes: blanking, heating, pre-forging, final forging, punching, trimming, tempering, and shot peening. Common processes include upsetting, drawing, bending, punching, and forming.
2. Common Die Forging Equipment
Common die forging equipment includes forging hammers, hot forging presses, flat forging machines, and friction presses.
In layman's terms, forged flanges are of higher quality, generally produced through die forging, with a finer crystal structure and higher strength, but are also more expensive. Both cast and forged flanges are common manufacturing methods. The choice depends on the strength requirements of the component being used. If the requirements are not high, machined flanges can also be used.

(3) Cut Flange
A flange is made by directly cutting a disc with the inner and outer diameters and thickness of the flange from the plate, leaving room for machining, and then machining bolt holes and water lines. Flanges produced in this way are called cut flanges. The maximum diameter of such flanges is limited to the width of the medium plate.

(4) Rolled Flanges 
The process of cutting and rolling a medium plate into a circle is called rolling, and it is often used in the production of large flanges. After successful rolling, welding is performed, followed by flattening, and then the water line and bolt holes are processed.

Second, the function of flanges. A flange, also called a flange plate or flange, is a part that connects pipes to each other. It is connected to the pipe end. Flanges have holes through which bolts can be inserted to tightly connect two flanges. A gasket is used to seal between flanges. Flange fittings refer to pipe fittings with flanges (flanges or flange plates). They can be cast, threaded, or welded. A flange joint consists of a pair of flanges, a gasket, and several bolts and nuts. The gasket is placed between the sealing surfaces of the two flanges. After tightening the nuts, the specific pressure on the surface of the gasket reaches a certain value, causing deformation and filling the uneven areas on the sealing surface, making the connection tight and leak-proof. Some pipe fittings and equipment already come with flanges, which are also considered flange connections. Flange connections are an important connection method in pipeline construction.

Flange connections are convenient to use and can withstand high pressure. They are widely used in industrial pipelines. In homes, where pipe diameters are small and pressure is low, flange connections are not visible. However, in a boiler room or production site, flanged pipes and equipment are ubiquitous.

The function of a flange is to secure and seal the connection between pipe fittings. Flanges are mainly used to connect and fasten pipes and fittings, maintaining their sealing performance; flanges are removable, facilitating pipe inspection. Reducing flanges are corrosion-resistant and acid and alkali-resistant, and can be used in water conservancy, power, power plants, pipe fittings, industry, and pressure vessels.

Stainless steel flanges can be used in boilers, pressure vessels, petroleum, chemical, shipbuilding, pharmaceutical, metallurgical, machinery, and food industries, facilitating the replacement of specific pipe sections.

Gearbox flanges are mainly used for connecting motors to gearboxes, and for connecting gearboxes to other equipment. Welding flanges are used to transfer pressure in pipes, thereby reducing stress concentration at the flange base.