Raised face flange ，According to the different types of flange sealing surfaces, flanges are commonly used in three types: flanges (also called flat flanges), concave and convex flanges, and tongue and groove flanges. The sealing surface of the protruding flange is flat and has a large contact area with the gasket. After pre-tightening, the gasket is easy to stretch or move to both sides, and the sealing is poor. Concave-surface flange and tongue-and-groove surface flange have better sealing performance, suitable for higher pressure applications.
The main production processes are mainly divided into forging, casting, cutting and rolling.
The cast flange has accurate blank shape and size, small processing volume and low cost, but has casting defects (porosity, cracks, inclusions); the internal organization of the casting is less streamlined (if it is a cutting part, the streamlined shape is worse);
Forged flanges have low carbon content, are generally less rusty than cast flanges, and have better streamlined forgings, denser structures, and better mechanical properties than cast flanges;
Improper forging process will also cause large or uneven grains, hardening cracks, and the cost of forging is higher than that of cast flanges.
Raised face blind flange
Forgings can withstand higher shear and tensile forces than castings.
The advantage of casting is that it can get a more complicated shape and the cost is lower;
The advantage of forging is that the internal structure is uniform, and there are no harmful defects such as pores and inclusions in the casting;
The difference between cast flanges and forged flanges from the production process, such as centrifugal flanges are a type of cast flanges.
The centrifugal flange belongs to the production flange of precision casting method. This type of casting is much thinner than ordinary sand casting, and the quality is improved a lot. It is not easy to have problems such as loose tissue, porosity and trachoma.
First of all, we need to understand how centrifugal flanges are produced. The process and products of centrifugal casting to make flat welded flanges are characterized by the following process steps:
① The selected raw material steel is smelted in an intermediate frequency electric furnace so that the temperature of the molten steel reaches 1600-1700 ° C;
② Preheat the metal mold to 800-900 ℃ to keep constant temperature;
③ start the centrifuge and inject the molten steel in step ① in step ② after preheating the metal mold;
④The castings are naturally cooled to 800-900 ℃ for 1-10 minutes;
The forging process generally consists of the following procedures, namely, selecting high-quality steel billets, heating, forming, and cooling after forging. The methods of forging 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, large machining allowance, but simple tools and great versatility, so it is widely used to forge single-piece and small-batch forgings with simpler 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. Die forging has high productivity, simple operation and easy mechanization and automation. Die forgings have high dimensional accuracy, small machining allowances, and more reasonable fiber organization for forgings, which can further increase the service life of parts.
⑤ Cool with water to near normal temperature, and remove the casting from the mold.