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 volume and low cost, but has casting defects (pores, cracks, inclusions); the internal structure of the casting is poor in streamline (if it is a cutting part, the streamline is worse);
Forged flanges generally have lower carbon content than cast flanges and are not easy to rust. Forgings are streamlined, have a denser structure, and have better mechanical properties than cast flanges;
Improper forging process will also cause large or uneven crystal grains, hardening cracks, and forging costs higher than 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 lower costs;
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;
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 flanges belong to the precision casting method to produce flanges. Compared with ordinary sand casting, the structure of this type of casting is much finer and the quality is improved a lot. It is not prone to problems such as loose structure, pores, and trachoma.
First of all, we need to understand how centrifugal flanges are produced, the process method and products of centrifugal casting to make flat welded flanges, which are characterized in that the product is processed through the following process steps:
① Put the selected raw material steel into an intermediate frequency electric furnace for smelting, so that the temperature of molten steel reaches 1600-1700℃;
② Preheat the metal mold to 800-900℃ to maintain a constant temperature;
③ Start the centrifuge, and pour the molten steel in step ① into the preheated metal mold in step ②;
④ The casting is naturally cooled to 800-900℃ and kept for 1-10 minutes;
⑤ Cool with water to near normal temperature, demould and take out the casting.
Let us understand the production process of forged flanges:
The forging process generally consists of the following procedures, namely, selecting high-quality steel billets for cutting, heating, forming, and cooling after forging. The forging process methods include free forging, die forging and membrane forging. During production, choose different forging methods according to the quality of 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 simpler 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 realization of mechanization and automation. The die forgings have high dimensional accuracy, small machining allowances, and more reasonable fiber structure distribution of the forgings, which can further improve the service life of the parts.
The basic process of free forging: In 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 the process of forging the original blank in the axial direction to reduce the height and increase the cross section. This process is often used for forging gear blanks and other disc-shaped forgings. Upsetting is divided into two types: total upsetting and partial upsetting.
2. Stretching Stretching is a forging process that increases the length of the blank and reduces the cross-section. It is usually used to produce blanks for shafts, such as lathe spindles and connecting rods.
3. Punching A forging process in which through holes or non-through holes are punched out on the blank with a punch.
4. Bending A forging process in which a blank is bent into a certain angle or shape.
5. Twisting A forging process in which one part of the blank is rotated by a certain angle relative to the other part.
6. Cutting The forging process of dividing the blank or cutting off the material head.
