(1) Cast flange and forged flange
The casting flange has accurate shape and size, small workload and low cost, but has casting defects (pore, crack, inclusion); the inner structure of the casting is poor streamlined (if it is a cutting part, the streamlined shape is worse);
Forged flanges are generally less carbon and less rusty than cast flanges. Forged flanges have better streamlined shape, compact structure and better mechanical properties than cast flanges.
Improper forging process will also lead to large or uneven grains, hardening cracks and higher forging cost than casting flange.
Forgings can withstand higher shear and tensile forces than castings.
The advantages of castings are that they can produce more complex shapes and lower costs.
The advantage of forging is that its internal structure is uniform and there are no harmful defects such as blowhole and inclusion in the casting.
The difference between casting flange and forging flange can be distinguished from the production process, for example, centrifugal flange is a kind of casting flange.
Centrifugal flange is a kind of flange produced by precision casting method. Compared with common sand casting, this casting method has much finer structure and much better quality. It is not easy to have loose structure, pore and trachoma.
First of all, we need to understand how centrifugal flange is produced. The centrifugal casting process and products for flat welded flange are characterized by the following process steps:
①The selected raw material steel is melted in medium frequency electric furnace, so that the temperature of molten steel reaches 1600-1700℃
②Pre-heating the metal die to 800-900 C to keep constant temperature;
③Start the centrifuge and inject molten steel into the metal mould after preheating.
④The castings are cooled naturally to 800-900 ℃ for 1-10 minutes.
⑤Cooling with water to near normal temperature, demoulding and removing the casting.
orging process generally consists of the following processes, namely, selecting high quality billet blanking, heating, forming and cooling after forging. The forging process includes free forging, die forging and membrane forging. In production, different forging methods are selected according to the quality of forgings and the quantity of batches produced.
Free forging is widely used to forge single and small-batch forgings with simple shape because of its low productivity and large processing allowance, but its simple tools and versatility. 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 has high productivity, simple operation and easy to realize 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.
The basic process of free forging: when forging freely, the shape of forgings is gradually forged by some basic deformation processes. The basic processes of free forging include upsetting, drawing, punching, bending and cutting.
1. Upsetting is the process of forging the billet along the axis to reduce its height and increase its cross section. This process is often used to forge gear blanks and other disc forgings. Upsetting can be divided into total upsetting and partial forging.
2. Drawing and drawing is a forging process that increases the length of blank and decreases its cross-section. It is usually used to produce axle blanks, such as lathe spindle and connecting rod.
3. Forging process of punching through hole or non-through hole on blank with punch.
4. The forging process in which the billet is bent to a certain angle or shape by bending.
5. A forging process in which a part of the billet rotates at a certain angle relative to another part by torsion.
6. Forging process of cutting and cutting blank or cutting blank head.
(2) Die forging
Die forging is called model forging, which is formed by placing the heated billet in the forging die fixed on the die forging equipment.
1. The basic process of die forging: blanking, heating, pre-forging, final forging, punching, trimming, tempering and shot peening. Common processes include upsetting, drawing, bending, punching and forming.
2. Common die forging equipment: die forging hammer, hot die forging press, flat forging machine, friction press, etc.
Generally speaking, the quality of forged flange is better. It is usually produced by die forging. The crystal structure is fine and the strength is high. Of course, the price is more expensive.
Whether casting flange or forging flange belongs to the common manufacturing method of flange, depending on the strength requirement of the parts to be used, if the requirement is not high, turning flange can also be selected.
(3) Cutting flange
In the middle plate, the flange is directly cut out of the disc with the inside and outside diameter and thickness of the processing quantity, and then the bolt hole and the water line are processed. The flange thus produced is called cutting flange. The maximum diameter of such flange is limited to the width of the plate.
(4) Rolled flange
The process of cutting strips with medium plates and rolling them into circles is called rolling, which is mostly used in the production of some large flanges. After successful coiling, welding is carried out, then flattening is carried out, and then the process of water line and bolt hole is processed.
Material
(1). Carbon steel: ASTM A105, 20 #, Q235, 16Mn, ASTM A350 LF1, LF2 CL1/CL2, LF3 CL1/CL2, ASTM A694 F42, F46, F48, F50, F52, F56, F60, F65, F70;
(2)Stainless steel: 304, 304L, 316, 316L, 1Cr18Ni9Ti, 0Cr18Ni9Ti, 321, 201
(3) Alloy steel: ASTM A182 F91, A182F12, A182F11, 16MnR, Cr5Mo, 12Cr1MoV, 15CrMo, 12Cr2Mo1, A335P22
Manufacturing Standards: National Standard, American Standard, Russian Standard, Japanese Standard, etc.
Function
Flange is a part connected between shaft and shaft, which is used to connect pipe ends. It is also used in the import and export of equipment, which is used to connect two equipment, such as reducer flange.
When the pump and valve are connected with the pipeline, the parts of these equipment are also made into corresponding flange shape, also known as flange connection. Where bolts are used around two planes to connect joints that are closed at the same time, they are generally referred to as "flanges", such as the connection of ventilation pipes, which can be called "flanges".
Because of its good comprehensive performance, flange is widely used in chemical engineering, construction, water supply, drainage, petroleum, light and heavy industries, refrigeration, sanitation, water heating, fire protection, electric power, aerospace, shipbuilding and other basic projects.
