Patent ID: 7514035

Claim:
A vacuum furnace for carburizing and gas quenching a stationary work piece in the same furnace chamber, having low pressure capability down to approximately 10 −3 torr and high pressure capability up to approximately 10 bar comprising a single furnace body chamber and an access door, said single furnace body chamber including a work zone having a length to height ratio of at least 3 to 1 and having a plurality of centered jet tube carburizing nozzles, each of said carburizing nozzles having a chamfer thereon and being located throughout said work zone for maximizing radial distribution of a low pressure reactant gas over the work piece, and said access door being operatively attached to said furnace body and including a plurality of angled jet tube carburizing nozzles located in said door for maximizing longitudinal distribution of the low pressure reactant gas over the work piece, said work zone and said access door each further including a plurality of high velocity gas quench nozzles located throughout said work zone and said access door for providing a high pressure quench gas up to approximately 10 bar to the stationary work piece located in said work zone, and said single furnace body chamber further including an outer wall, an inner wall and a plenum therebetween, said inner wall forming the exterior of said work zone, and said plenum being formed to receive the quench gas at a pressure up to approximately 10 bar and a speed up to approximately 322 km/hr, said furnace further including a large curved external duct operatively attached to said single furnace body chamber, said duct having a low angle arc with no sharp corners for producing a low pressure drop of the quench gas, and wherein the diameter of said duct is larger than approximately 70% to 90% of the shortest work zone dimension.