Elbow Flange

Elbow flanges are mostly used for flange connections or flange joints. They refer to detachable connections that are connected by flanges, gaskets and bolts as a combined sealing structure. Pipe flanges refer to flanges used for piping in pipeline installations, and are used on equipment to refer to the inlet and outlet flanges of equipment.

Elbows are pipe fittings that change the direction of pipelines. Flanges are parts that connect pipes to each other and are connected to the ends of pipes. There are holes on the flanges, and bolts connect the two flanges tightly. Gaskets are used to seal the flanges. Flanges are divided into threaded (threaded) flanges and welded flanges. The ways to connect elbow flanges to pipes include: direct welding (the most common way) flange connection, hot melt connection, electric fusion connection, threaded connection and socket connection.

Production process

The production process is mainly divided into four types: forging, casting, cutting and rolling.

Casting flange and forging flange
The flanges cast out have accurate blank shape and size, small processing volume and low cost, but there are casting defects (pores, cracks and inclusions); the internal structure of the casting is poor in streamline (if it is a cutting part, the streamline is even worse);

Forged flanges generally have lower carbon content than cast flanges and are not easy to rust. Forgings have good streamlines, denser structures and better mechanical properties than cast flanges;
Improper forging process will also cause large or uneven grains and hardening cracks, and the forging cost is higher than that of cast flanges.
Forgings can withstand higher shear and tensile forces than castings.

The advantage of castings is that they can produce more complex shapes and are relatively low in cost;

The advantage of forgings is that the internal structure is uniform, and there are no harmful defects such as pores and inclusions in castings;

The difference between cast flanges and forged flanges can be distinguished from the production process. For example, centrifugal flanges are a type of cast flanges.
Centrifugal flanges are produced by precision casting. This type of casting has a much finer structure than ordinary sand castings, and the quality is much improved. It is not easy to have problems such as loose structure, pores, and sand eyes.

First of all, we need to understand how centrifugal flanges are produced, the process method and products of centrifugal casting flat welding flanges, which are characterized by the following process steps:
① Put the selected raw steel into the medium frequency electric furnace for smelting, so that the temperature of the molten steel reaches 1600-1700℃;
② Preheat the metal mold to 800-900℃ and keep it constant;
③ Start the centrifuge and inject the molten steel in step ① into the preheated metal mold in step ②;
④ The casting is naturally cooled to 800-900℃ and maintained for 1-10 minutes;
⑤ Cool with water to near room temperature, demold and remove the casting.

The Production process of forged flanges

The forging process generally consists of the following steps, namely, selecting high-quality steel billets for blanking, heating, forming, and cooling after forging. The forging process methods include free forging, die forging and membrane forging. During production, different forging methods are selected according to the quality of the forgings and the number of production batches.
Free forging has low productivity and large machining allowance, but the tools are simple and versatile, so it is widely used to forge single pieces and small batches of forgings with simpler shapes. 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 more reasonable fiber structure distribution of forgings, which can further improve the service life of parts.

The Basic process of free forging

During free forging, the shape of the forging is gradually forged into the blank through some basic deformation processes. The basic processes of free forging include upsetting, drawing, punching, bending and cutting.

1. Upsetting is the process of forging the original blank along the axial direction to reduce its height and increase its cross-section. This process is often used to forge 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 blank and reduces the cross-section. It is usually used to produce shaft blanks, such as lathe spindles, connecting rods, etc.

3. Punching A forging process that uses a punch to punch through holes or non-through holes on the blank.

4. Bending A forging process that bends the blank into a certain angle or shape.

5. Twisting A forging process that rotates one part of the blank relative to another part at a certain angle.

6. Cutting A forging process that splits the blank or cuts off the head.

Die forging

Die forging is called model forging, which places the heated blank in a forging die fixed on the die forging equipment for Elbow flange forging.

1. Basic process of die forging Die forging process: 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 die forging hammers, hot die forging presses, flat forging machines and friction presses.
Generally speaking, forged flanges are of better quality and are generally produced by die forging. They have fine crystal structure and high strength, and of course, they are more expensive.
Both cast flanges and forged flanges are common flange manufacturing methods. It depends on the strength requirements of the parts to be used. If the requirements are not high, turning flanges can also be used.

Cut flanges

Directly cut the inner and outer diameters and thickness of the flange on the middle plate, and then process the bolt holes and waterlines. The flanges produced in this way are called cut flanges, and the maximum diameter of such flanges is limited to the width of the middle plate.

Rolled flanges

The process of cutting strips from the middle plate and then rolling them into a circle is called rolling, which is mostly used in the production of some large Elbow flanges. After the rolling is successful, welding is carried out, then flattening, and then the waterline and bolt hole processes are processed.