45 steel valve body in extruded casting was adopted in designing combined mould

in which core and punch adopts H13 tool steel

and sleeve and poisoned structure uses 45# steel or 40Cr steel. And special extruded machine with maximum extruded force of 1 500 kN and closed forces of 2 000 kN is used with punch velocity of 0.30

0

.35 m/s. Drawing-mould declination is 2°

2°and 0.5°for up-punch

down-punch and side-punch

respectively. And the down-punch directly pushes the castings for pushing ways

where fit clearance between punch and the mould is 0.16

0

.2 mm. The position of the die subjected to higher thermal stress has been cooled by tube-cooling combining with inserted-pipe cooling. Four overflow slots on cross-position of parting surface have been set to ensure the accuracy of the casting in height direction. To improve fusion-resistant ability of the die

the coating with thickness of 0.2

0.5 mm using self-developed siliceous earth coating is conducted.