The cast flange has a precise shape and size, a small amount of processing, and a low cost, but it has casting defects (swells, cracks, and inclusions); the internal streamline of the casting is poor (if it is a cutting part, the streamlined type is worse);
Forged flanges are generally lower in carbon content than cast flanges, are less likely to rust, have better streamlined forgings, denser structures, and have better mechanical properties than casting flanges.
Improper forging process will also appear large or uneven grain, hardening crack phenomenon, forging caused by the higher than the casting flange.
Forgings can withstand higher shear and tensile forces than castings.
The advantage of castings is that they can produce more complex shapes with lower cost.
The advantage of forgings is that the internal structure is uniform and there are no harmful defects such as blowholes and inclusions in the castings.
Different from the production process, the difference between the cast flange and the forged flange, such as a centrifugal flange, is a kind of cast flange.
Centrifugal flanges are flanges produced by precision casting methods. This type of casting is much thinner than ordinary sand casting structures. The quality is improved a lot and problems such as loose structure, porosity, and trachoma are less likely to occur.
First of all, we need to understand how centrifugal flanges are manufactured and manufactured. Centrifugal casting methods and products for making flat welded flanges are characterized by the following process steps:
1 The selected raw material steel is placed in an intermediate frequency furnace for smelting so that the molten steel temperature 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 metal mold after preheating in step 2;
4 castings are naturally cooled to 800-900°C for 1-10 minutes;
5 Cool to near room temperature with water and remove the mold from the mold.
Let's look at the production process flow of the forged flange:
The forging process is generally composed of the following processes, namely, selecting the blank for high quality steel, heating, forming, and cooling after forging. Forging processes include free forging, die forging, and film forging. During production, different forging methods are selected according to the size of the forging mass and the number of production batches.
Forging productivity is low, and the machining allowance is large, but the tool is simple and versatile. Therefore, it is widely used for forging single-piece and small batch production forgings with relatively simple shapes. Free-forging equipment includes air hammers, steam-air hammers and hydraulic presses, which are suitable for the production of small, medium and large forgings, respectively. Die forging productivity, simple operation, easy to implement mechanization and automation. Die forgings have high dimensional accuracy, small machining allowances, and more reasonable distribution of fiber structure for forgings, which can further increase the service life of parts.
The basic process of free forging: When forging freely, the shape of the forging is gradually forging the blank through some basic deformation processes. The basic processes of free forging include upsetting, pulling, punching, bending and cutting.
1. Upsetting is the operation of forging the original billet in the axial direction to reduce its height and increase the cross section. This process is often used for forging gear blanks and other disk-shaped forgings. Upsetting is divided into full upsetting and partial upsetting.
2. Drawing and drawing is the forging process that increases the length of the blank and reduces the cross section. It is usually used to produce shaft type blanks, such as lathe spindles and connecting rods.
3. Punching A punching process in which a punch punches a through hole or a blind hole in a blank.
4. A forging process that bends the blank into a certain angle or shape.
5. Twist the forging process that rotates a portion of the blank relative to the other portion by a certain angle.
6. Forging process to cut the blank or remove the blank.
Die forging is called model forging and the heated billet is forged into a forging die fixed on a die forging apparatus.
1. The basic processes of die forging The process of die forging: blanking, heating, pre-forging, final forging, lapping, trimming, tempering, shot peening. Commonly used processes include upsetting, pulling, bending, punching and forming.
2. Common forging equipment Common forging equipment includes die forging hammers, hot die forging presses, flat forging presses, and friction presses.
In layman's terms, forged flanges are of better quality and are generally produced by die forging. The crystals are finely organised and the strength is high. Of course the price is also higher.
Both cast flanges and forged flanges are commonly used in flange manufacturing. See the strength requirements of the parts that need to be used. If the requirements are not high, flanges can also be selected for turning.
Third, cutting flange
In the middle plate, the discs with the inner and outer diameters and thickness of the flanges are directly cut out, and then the bolt holes and the water line are processed. The flange thus produced is called a cut flange. The maximum diameter of such a flange is limited to the width of the middle plate.
Fourth, roll flange
The process of cutting a strip from a medium plate and then rolling it into a circle is called rolling, and it is used for the production of some large flanges. After successful rolling, welding is performed, and then the flattening is performed, and then the process of waterline and bolt hole processing is performed.
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