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, small processing amount and low cost, but there are casting defects (porosity, cracks, inclusions);
Forged flanges are generally lower than cast flanges with lower carbon content and less prone to rust, forgings are streamlined, the structure is relatively dense, and the mechanical properties are better than those of cast flanges;
Improper forging process will also cause large or uneven grains, hardening cracks, and the forging cost is higher than that of casting flanges.
Forgings can withstand higher shear and tensile forces than castings.
The advantage of castings is that they can be manufactured with a more complex shape and a relatively low cost;
The advantage of forging is that the internal structure is uniform, and there are no harmful defects such as porosity and inclusions in the casting;
From the production process, the difference between cast flange and forged flange is different, for example, centrifugal flange is a kind of cast flange.
Centrifugal flange belongs to the precision casting method to produce flanges, this kind of casting is much finer than ordinary sand casting structure, the quality is improved a lot, and it is not easy to have loose tissue, porosity, trachoma and other problems.
First of all, we need to understand how the centrifugal flange is produced, and the process method and product of centrifugal casting to make flat welded flange are characterized by the following process steps:
1) Put the selected raw steel into the intermediate frequency electric furnace for smelting, so that the temperature of the molten steel reaches 1600-1700°C;
2) Preheat the metal mold to 800-900°C to maintain a constant temperature;
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°C and kept for 1-10 minutes;
5) Cool down with water to close to room temperature, and remove the casting.
Let's understand the production process of forged flanges:
The forging process is generally composed of the following processes, namely, selecting high-quality billets for blanking, heating, forming, and cooling after forging. The forging process methods include open forging, die forging and fetal membrane forging. During production, different forging methods are selected according to the quality of the forging and the number of production batches.
Open forging has low productivity and large machining allowance, but the tool is simple and versatile, so it is widely used for forging forgings with simple shapes for single piece and small batch production. Open forging equipment includes air hammers, steam-air hammers and hydraulic presses, which are suitable for the production of small, medium and large forgings. Die forging has high productivity, simple operation, and easy to realize mechanization and automation. The dimensional accuracy of die forgings is high, the machining allowance is small, and the fiber structure distribution of forgings is more reasonable, which can further improve the service life of parts.
The basic process of open forging: In 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, lengthening, punching, bending, and cutting.
1. Upsetting Upsetting is an operation process in which the raw blank is forged along the axial direction to reduce its height and increase its cross-section. This process is commonly used to forge gear blanks and other disc-shaped forgings. Upsetting is divided into two types: full upsetting and partial forging.
2. Lengthening Lengthening is a forging process that increases the length of the blank and reduces the cross-section, and is usually used to produce shaft blanks, such as lathe spindles, connecting rods, etc.
3. Punching: A forging process in which a punch is punched out of a blank with or without a punch.
4. Bending The forging process that bends a blank into a certain angle or shape.
5. Torsion: A forging process that rotates one part of the blank at a certain angle relative to the other.
6. Cutting: The forging process of dividing the blank or cutting off the material head.
(2) Die forging
Die forging is called model forging, and the heated blank is placed in a forging die fixed on the die forging equipment for forging.
1. The basic process of die forging Die forging process: blanking, heating, pre-forging, final forging, punching skin, trimming, quenching and tempering, shot peening. The commonly used processes include upsetting, lengthening, bending, punching, and forming.
2. Common die forging equipment Commonly used die forging equipment includes die forging hammer, hot die forging press, flat forging machine and friction press.
Generally speaking, the quality of forged flanges is better, generally produced by die forging, with fine crystal structure and high strength, and of course the price is more expensive.
Whether it is a cast flange or a forged flange is a common manufacturing method of flanges, depending on the strength requirements of the parts that need to be used, if the requirements are not high, you can also choose the turning flange.
(3) Cut flange
The inner and outer diameters and thickness of the flange are cut directly from the middle plate, and the bolt holes and waterlines are processed. The flange produced in this way is called a cut flange, and the maximum diameter of this type of flange is limited to the width of the middle plate.
(4) Rolled flange
The process of cutting slivers with a medium plate and then rolling them into circles is called rolling, and it is mostly used in the production of some large flanges. After the rolling, it is welded, then flattened, and then processed by the process of waterline and bolt holes.