Flange production process
The production process is mainly divided into four types: forging, casting, cutting and rolling.
(1) Cast flange and forged flange
The cast flange has accurate shape and size of the blank, small processing volume and low cost, but has casting defects (porosity, crack, inclusion); the internal organization of the casting is less streamlined (if it is a cutting part, the streamlined shape is even worse);
Forged flanges generally have lower carbon content than cast flanges and are not easy to rust, the forgings are streamlined, the structure is relatively dense, and the mechanical properties are better than cast flanges;
Improper forging process will also cause large or uneven grains, hardening cracks, and forging costs are higher than casting flanges.
Forgings can withstand higher shear and tensile forces than castings.
The advantage of casting is that it can produce a more complex shape and the cost is relatively low;
The advantage of forgings is that the internal structure is uniform, and there are no harmful defects such as pores and inclusions in the casting;
The difference between casting flanges and forging flanges is distinguished from the production process. For example, centrifugal flanges are a type of casting flanges.
Centrifugal flanges belong to the casting method to produce flanges. Compared with ordinary sand castings, this kind of casting has much finer structure and improved quality, and is not prone to problems such as loose organization, pores, and trachoma.
First of all, we need to understand how the centrifugal flange is produced, the process method and product of centrifugal casting to make flat welding flange, which is characterized by the following process steps:
①Put the selected raw material steel into the intermediate frequency electric furnace for smelting, so that the molten steel temperature reaches 1600-1700℃;
②Preheat the metal mold to 800-900℃ to maintain a constant temperature;
③Start the centrifuge and inject the molten steel in step ① into the preheated metal mold in step ②;
④The castings are naturally cooled to 800-900℃ for 1-10 minutes;
⑤Cool with water to near normal temperature, demould and take out the casting.
Let's take a look at the production process of forged flanges:
The forging process is generally composed of the following procedures, that is, selecting high-quality billets for blanking, heating, forming, and cooling after forging. Forging process methods include free forging, die forging and fetal 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 for forging single-piece and small-batch forgings with simple shapes. Free forging equipment includes air hammer, steam-air hammer and hydraulic press, etc., which are respectively suitable for the production of small, medium and large forgings. Die forging has high productivity, simple operation, and easy mechanization and automation. Die forgings have high dimensional accuracy, small machining allowance, and more reasonable distribution of fiber structure, which can further improve the service life of parts.
Basic process of free forging: During free forging, the shape of the forging is gradually forged from the blank through some basic deformation processes. The basic processes of free forging include upsetting, drawing, punching, bending and cutting.
1. Upsetting Upsetting is an operation process in which the raw material is forged in the axial direction 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 two types: full upsetting and partial forging.
2. Elongation Elongation 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 is a forging process in which a punch is used to punch through holes or non-through holes in the blank.
4. Bending A forging process in which the billet is bent into a certain angle or shape.
5. Torsion is a forging process in which one part of the billet rotates at a certain angle relative to another part.
6. The forging process of cutting and dividing blanks or cutting heads.
(2) Die forging
The full name of die forging is model forging, which is formed by placing the heated billet in a forging die fixed on the die forging equipment.
1. The basic process of die forging Die forging process: blanking, heating, pre-forging, final forging, punching and skinning, trimming, quenching and tempering, shot peening. Common processes include upsetting, drawing, bending, punching, and forming.
2. Commonly used die forging equipment Commonly used die forging equipment includes die forging hammer, hot die forging press, flat forging machine and friction press.
In layman's terms, the quality of forged flanges is better, generally produced by die forging, with fine crystal structure and high strength. Of course, the price is also more expensive.
Whether it is a cast flange or a forged flange, it is a common manufacturing method for flanges. It depends on the strength requirements of the parts to be used. If the requirements are not high, turning flanges can also be used.
(3) Cut flange
The inner and outer diameters and thicknesses of the flange are directly cut on the middle plate, and then the bolt holes and water lines are processed. The flanges produced in this way are called cut flanges, and the large diameter of such flanges is limited by the width of the middle plate.
(4) Rolled flange
The process of cutting the sliver with a medium plate and then rolling it into a circle is called rolling, which is mostly used in the production of some large flanges. After the roll is successful, it is welded, then flattened, and then processed in the process of water line and bolt hole.
