Long shaft heavy forging is also a kind of common forging. The following article mainly talks about the relevant specifications for forging heating process of long shaft heavy forging.
Long shaft heavy forgings are generally used for transmission shafts, which are the key and core components of mechanical equipment and the basic components for manufacturing major equipment. The quality requirements are very strict. The production process of large shaft forgings is pre heating and post heating. Because the production of large forgings is mainly single piece production, the scrap of forgings will cause huge economic losses and construction period delay. Therefore, reasonable heating specifications must be formulated to ensure the safety of ingot heating, reduce heating time, and achieve the purpose of energy saving.
The specific research contents and conclusions are as follows:
1. During charging at room temperature, the heating capacity of the heating furnace can be used for ingot heating. The stress field and temperature field of ingot during heating are obtained through simulation. The stress of the steel ingot center is three direction tensile stress and axial stress. In addition, the peak values of axial stress and surface center temperature difference occur at low temperature and during the phase transformation of ingot core. From the point of view of rapid heating, the optimal parameters of heating specification are 850 ℃ for rudder stock ingot during phase transformation, 1 hour for phase transformation, and 1235 ℃ for forging; The heat preservation temperature of propeller shaft ingot during phase transformation is 850 ℃, the heat preservation time during phase transformation is 0.8 hours, and the heat preservation temperature for forging is 1220 ℃.
2. During high temperature charging, the heating speed of steel ingots under low temperature is obviously accelerated, but the stress of the heart is also greatly increased, that is, high temperature charging can effectively reduce the heating time, but the charging temperature must be controlled. The holding time at charging temperature is 2 hours, the propeller shaft is 1.5 hours, and the rest is the same as that at low-temperature charging.
3. The heating of subsequent fires is different from the previous heating. Since the internal temperature of the forging is high and the surface temperature is low, when the furnace temperature reaches the forging insulation temperature, the temperature difference between the internal surfaces of the forging is not large, so a smaller forging insulation temperature of 1220 ℃ should be selected. When the forging length is greater than the heating furnace length, the forging not installed will have a great impact on the temperature of the forging near the furnace door. In order to reduce the heating time, it is necessary to increase the length of the furnace.