The production processes are mainly divided into forging, casting and cutting. Cast flange and forged flange flange The shape and size of the blank are accurate, the processing amount is small, and the cost is low, but there are casting defects (pores, cracks, inclusions); The internal structure of the casting has poor streamline (even worse if it is a cutting part); Forged flanges generally contain less carbon than cast flanges and are not easy to rust. Forged flanges have good streamline, compact structure and better mechanical properties than cast flanges; Improper forging process may also lead to large or uneven grains and hardening cracks, and the forging cost is higher than that of cast flanges.
Forgings can withstand higher shear force and tensile force than castings. The advantage of the casting is that it can produce a more complex shape, and the cost is relatively low; The forging has the advantage that the internal structure is uniform, and there are no harmful defects such as pores and inclusions in the casting; Distinguish the difference between cast flange and forged flange from the production process flow. For example, centrifugal flange is a kind of cast flange. Centrifugal flange is produced by precision casting. Compared with ordinary sand casting, this kind of casting has much finer structure and better quality. It is not easy to have problems such as loose structure, porosity, and trachoma. First of all, we need to understand how the centrifugal flange is produced. The process method and product of centrifugal casting for making flat welding flange are characterized by that the product is processed through the following process steps:
① Put the selected raw material steel into the medium frequency electric furnace for melting, so that the temperature of molten steel can reach 1600-1700 ℃;
② Preheat the metal mold to 800-900 ℃ to maintain constant temperature;
③ Start the centrifuge, inject molten steel in step ① into the preheated metal mold in step ②;
④ The casting shall be naturally cooled to 800-900 ℃ for 1-10 minutes;
⑤ Cool with water to near normal temperature, demould and take out the casting.
Forging process of blind flange:
Generally, it consists of the following processes, namely, blanking, heating, forming and cooling after forging of high-quality steel billets. The forging process includes free forging, die forging and mould forging. During production, different forging methods shall be selected according to the forging quality and production batch. Free forging has low productivity and large machining allowance, but its tools are simple and versatile, so it is widely used to forge single piece and small batch forgings with simple shapes. Free forging equipment includes air hammer, steam air hammer and hydraulic press, which are suitable for the production of small, medium and large forgings respectively. Die forging is characterized by high productivity, simple operation, 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.
