What are the methods of heating the surface of free forging forgings?

If dual-frequency induction heating of free forging forgings, covered with circular sensors, continuous heating from bottom to top, water quenching. Such as cold roller, piston, cement grinding wheel, etc. Extremely long forgings, due to their limited length, cannot be lifted vertically on the quenching machine, but can only lie horizontally, using special sensors and transformers, crawling on the shaft or sliding along the guide rail.

Free forging should be supported in special rotating platform, forgings by weight of support on the return roller rotation, inside and outside the circle itself can freely adjustable, fixed position sensor with circular expand the gap between the hot surface heating and sensor before and after expansion is mainly local heating, change the sensor and the heating surface of clearance, clearance changes will affect heating speed and heating temperature.

In order to maintain the stability of the gap between the sensor and the heating surface, when the cyclic heating expands, the sensor also moves synchronously. Therefore, when the internal and external circulation of the heating cycle is heated, the sensor and the cycle always have a certain locator, which can make the sensor forward or backward with the expansion of the cyclic heating surface.

For the intermediate frequency hardening of the forging, the height of the boss on both sides of the pedal exceeds the clearance distance between the sensor and the pedal, so that the sensor ring cannot be inserted into the pedal. Similar forgings can be made using a split separation sensor, which is buckled on to heat the pedal. After heating to the temperature, separate the sensor and take out the running wheel for quenching or directly quench with water, then open the sensor and take out the running wheel.

The heating method of forging flame surface quenching is roughly similar to that of induction surface heating, which is also divided into fixed method and continuous moving heating method. In the fixation method, a flame nozzle can be sprayed onto the surface of a portion of the forging to heat it. When the quenching temperature is reached, remove the nozzle and cool with water hose spray (or compressed air). In the fixation method, the flame nozzle can also be fixed in one position (or several nozzles surrounding the outer circle of the forgings), and the forgings can be rotated, heated to quenching temperature, and cooled with a spray of water from the nozzles.

The continuous moving heating method is to move the nozzle with the cooling nozzle on the heating surface of the forging, while heating and quenching.

Carefully observe the flame can be divided into three regions: see it near the center of the dark part of the nozzle is flame, is composed of oxygen and its decomposition gases, the temperature is low, the outer white to reduction zone, is a flame area (up to 3100 ℃), high temperature metal rapid heating, melting, even outer for complete combustion zone, the temperature is lower than the reduction zone.

When the flame is heated, the heat of the inner layer is conducted by the surface. In order to rapidly heat the forgings to the quenching temperature within a certain depth, it is necessary to maintain high surface temperature, which often makes the surface temperature too high, coarse particles, and even burns.