In the initial stage of forging deformation of flat welding flange, due to the easy deformation of the porous preform, the deformation force is small, and the density increases rapidly. In the later stage of forging, since most of the pores are closed, the deformation resistance increases, and the deformation force required to eliminate the remaining pores increases rapidly. The deformation resistance is closely related to the deformation temperature, and a higher deformation temperature is beneficial to densification and reduces the deformation resistance. The higher deformation rate is also beneficial to the densification of the flat welded flange.
The flat welding flange forging process has stricter equipment requirements than traditional die forging, and the displacement characteristics of the punch must match the deformation and dense characteristics of the preform. The contact time between the blank and the mold should be as short as possible. The forging press must have good rigidity, and the movable beam and piston must have good guiding accuracy to ensure the accuracy of the forgings. Therefore, the flat welding flange forging generally chooses a mechanical press, such as a crankshaft press, or a friction press with higher precision.
1. The characteristics of flat welding flange
The flat welding flange not only saves space and weight, but also ensures that the joints will not leak and have good sealing performance. The reduction in size of the compact flange is due to the reduced diameter of the seal, which reduces the cross-section of the sealing face. Second, the flange gasket has been replaced by a sealing ring to ensure the matching of the sealing face to the sealing face. As the required pressure decreases, the size and required number of bolts can be reduced accordingly, so a new small and light weight (70% to 80% lighter than the traditional flange) is finally designed. product. Therefore, the flat welding flange type is a relatively high-quality flange product, which reduces the quality and space and plays an important role in industrial use.
Second, the technical parameters of flat welding flange:
(1) Flange outer diameter: 75mm-2190mm
(2) Bolt hole center circle diameter: 50mm----2130mm
(3) Bolt hole diameter: 11mm-30mm
(4) Number of bolt holes: 4-48
(5) Thread: M10-M27
(6) Flange thickness: 12mm-58mm
(7) Tube outer diameter: A(17. 2-2032MM) B(14-2020MM)
(8) Flange inner diameter: A(18-2036MM) B(15-2024MM)
(9). Theoretical weight of flange: 0.36kg--234.6kg (DN1800)
(10).Material: A105, 20#, Q235, 16Mn, 304, 304L, 316, 316L, 321
(11). Production standards: HG/T20592-2009, GB/T9119-2000, SH3406-1996, JB/T81-1994, DIN 2573, DIN 2576, EN1092-1
Product Name Flat Welding Flange
Working pressure PN0.25MPa, PN0.6MPa, PN1.0MPa, PN1.6MPa, PN2.5MPa
Product Category Full Flat Panel Flange (FF), Raised Panel Flange (RF)
Manufacturing materials 304 316 304L 316L 321 2025Q23516MN, etc.
The connection form is single-sided welding and double-sided nut connection.
Product features Beautiful appearance, smooth surface, acid and alkali resistance, anti-corrosion, strong texture performance
3. Forging method of flat welding flange
The forging of flat welding flange can be divided into free forging, upsetting, extrusion, die forging, closed die forging and closed upsetting. Closed die forging and closed upset forging have high material utilization due to no flash. It is possible to complete the finishing of complex forgings in one or several operations. Since there is no flash, the stressed area of ​​the forging is reduced and the required load is also reduced. However, it should be noted that the blank cannot be completely restricted. For this reason, the volume of the blank should be strictly controlled, the relative position of the forging die should be controlled and the forging should be measured, and efforts should be made to reduce the wear of the forging die.
According to the movement mode of the forging die, forging can be divided into pendulum rolling, pendulum rotary forging, roll forging, cross wedge rolling, ring rolling and skew rolling. Pendulum rolling, pendulum swaging and ring rolling can also be processed by precision forging. In order to improve the utilization rate of materials, roll forging and cross-rolling can be used as front-end processing of slender materials. Rotary forging, like free forging, is also locally formed, and its advantage is that it can be formed even when the forging force is small compared to the size of the forging. In this forging method, including free forging, the material expands from the vicinity of the die surface to the free surface during processing, so it is difficult to ensure accuracy. high forging force to obtain products with complex shapes and high precision. For example, forgings such as steam turbine blades with many varieties and large sizes are produced.
When the temperature exceeds 300-400°C (blue brittle zone of steel) and reaches 700-800°C, the deformation resistance will decrease sharply and the deformation energy will be greatly improved. According to the forging in different temperature regions, according to the different forging quality and forging process requirements, it can be divided into three forming temperature regions: cold forging, warm forging and hot forging. Originally, there is no strict boundary for the division of this temperature range. Generally speaking, forging in the temperature range with recrystallization is called hot forging, and forging at room temperature without heating is called cold forging.
During low temperature forging, the dimensional change of the forging is small. Forging below 700 ℃, less oxide scale is formed, and there is no decarburization on the surface. Therefore, as long as the deformation energy is within the range of forming energy, cold forging can easily obtain good dimensional accuracy and surface finish. As long as the temperature and lubricating cooling are well controlled, warm forging below 700°C can also achieve good accuracy. During hot forging, large forgings with complex shapes can be forged due to the small deformation energy and deformation resistance. To obtain forgings with high dimensional accuracy, hot forging can be used in the temperature range of 900-1000 °C. In addition, pay attention to improving the working environment of hot forging. The life of the forging die (20,000 to 5,000 for hot forging, 10,000 to 20,000 for warm forging, and 20,000 to 50,000 for cold forging) is shorter than forging in other temperature ranges, but it has a large degree of freedom and low cost .
The blank is deformed and work hardened during cold forging, so that the forging die bears a high load. Therefore, it is necessary to use a high-strength forging die and a hard lubricating film treatment method to prevent wear and adhesion. In addition, in order to prevent billet cracks, intermediate annealing is performed when necessary to ensure the required deformability. In order to maintain a good lubricating state, the blank can be phosphated. In the continuous processing of bar and wire rod, the section can not be lubricated at present, and the possibility of using phosphating lubrication method is being studied.