17-4PH steel has low thermal conductivity and large billet size (cross section). It needs to be heated for a long time to reach the forging temperature. In order to shorten the residence time of forging billet in the high temperature furnace, it is generally required to preheat it for about 2h at 990-1020 ℃. Then put the preheated blank into the high temperature furnace for heating. When the temperature reaches the forging temperature (1180~1230 ℃), it should be immediately taken out of the furnace for forging after holding for about 1.5h to prevent overheating, overburning of the workpiece and similar copper rich phase precipitation of the alloy when the heating temperature is too high.

The pneumatic regulating butterfly valve has the smallest operating torque among all valves. It can be opened and closed quickly, powered by compressed air, through the mechanical transmission valve rod of the piston rack and gear, and rotate the valve plate 0~90o with the torque output from the angular stroke. It has simple structure, small volume, light weight, small flow resistance, large flow coefficient, and good sealing performance. Large adjustment range. It is the execution unit of instruments in the automatic control system;