Vacuum tempering furnace rapid heating and cooling technology and design

As is known to all, the purpose of the vacuum tempering furnace is the advantage of vacuum quenching (products oxidation, decarbonization, surface light corrosion, no pollution, etc.) to keep down, at the same time, complete removal of quenching stress tempering process, reduce the deformation and cracking and perfect the technical requirements of material organization; Without vacuum tempering, the advantage of vacuum quenching is lost. At present domestic vacuum tempering equipment and process all shortcomings, vacuum quenching after good light become grey or beige color after vacuum tempering, between corrosion phenomenon, will also bring hardness uneven, some domestic vacuum tempering furnace cooling speed slow, for some steel produced the second kind of temper brittleness danger. To sum up, the vacuum tempering technology and equipment design have attracted the attention of heat treatment circles.

（1）the purpose of fast heating and cooling of vacuum back furnace
1:Shorten process time and improve equipment productivity;
2:Economize on energy and materials consumption;
3:The tempering of certain materials is inhibited.

(2) quick heating design measures
1:In the low temperature heating stage, in order to improve the uniformity and heating speed of the furnace, it is necessary to refill the gas, and the pressure of the vacuum 3:return furnace can exceed the atmospheric pressure. The WZH vacuum furnace USES 0. 06 ~ 0. 07 mpa (0. 6 x 105 ~ 0. 7 x 105Pa is a rechargeable gas, which can effectively improve the heating speed and the uniformity of furnace temperature.
2:The heat exchanger does not work, such as the WZH 60 furnace, where the heat exchanger is in the lifting position.
3:Set the air guide board, adjust the best Angle to make the heat transfer effect best.
4:The fan agitates the air circulation and increases the heating speed.

(3) rapid cooling design measures
1: filling the positive pressure in the furnace gases, high purity N2 can be used, or the mixture (such as the volume fraction of 90% 10% N2 + H2) in order to obtain high tempering brightness surface of workpiece, filling the gas circulation by fan agitation air-cooled cooling artifacts, can effectively improve the cooling speed of tempering artifacts, inhibition of some materials of the second kind temper brittleness.
2:The heat exchanger (descending) is in the working state, so that the large amount of heat of the flow air is carried away by the heat exchanger, speeding up the cooling rate.
3:The direction of air flow and flow rate are best.