Heat treat furnace with multi-bar high convective gas quench

In a process for heat treating metal work in a cylindrical furnace having a heat treat chamber containing the work, a circular plenum plate suspended within said chamber adjacent the rearward end of said chamber to define an exit space between said plate's outer edge and said chamber, said plate having a central underpressure opening and a fan between said plate and said rearward end for generating a wind mass, said furnace also having means for heating said work and means for cooling said wind mass, said process including the steps of:

• (a) providing first and second fixed fan diffusers extending radially outwardly from said central underpressure opening and extending longitudinally between said plate and said rearward end, said first diffuser adjacent said plate and having first vane passageways permitting a wind mass when swirling in a first direction to enter and exit said first vane passageways while preventing flow therethrough when said wind mass swirls in an opposite second direction;
• said second diffuser adjacent said rearward end and having second vane passageways permitting said wind mass when swirling in a second direction opposite to said first direction to enter and exit said second vane passageways while preventing flow therethrough when said wind mass swirls in said first direction and at least one cooling coil in fluid communication only with at least one of said second vane passageways;
• (b) rotating said fan in a first direction while actuating said heat means to cause said wind mass to flow through said first diffuser while blocking said wind mass from entry into said second diffuser, the pressure of said wind mass caused by the rotation of said fan being sufficient to cause said wind mass to pass through the annular exit space between the circumferential edge of said plate and the wall of said heat treat chamber, enter said heat treat chamber to convectively heat work therein to a temperature of about 1000.degree. to 1200.degree. F. and be thereafter withdrawn from said heat treat chamber by exiting through said central underpressure opening;
• and, thereafter
• (c) rotating said fan in said second direction while actuating said cooling means to cause said wind mass to flow through said second diffuser while being blocked from flowing through said first diffuser for quenching said work;
• said wind mass being cooled by passing said wind mass over said cooling coil when leaving said second diffuser and the pressure of said wind mass caused by the rotation of said fan being sufficient to cause said wind mass to pass through said annular exit space, enter said heat treat chamber to convectively cool said work and be withdrawn therefrom through said central underpressure opening.

In a heat treat furnace for heat treating metal work, said furnace having a cylindrical heat treat chamber with a door sealed forward end and a closed rearward end and a plenum plate suspended within said heat treat chamber, said plate having a central, underpressure opening and defining an exit space between its' outer edge and said heat treat chamber, a fan between said plenum plate and said rearward end, the improvement comprising:

• a first, stationary fan diffuser adjacent said plenum plate permitting wind mass generated by said impeller to travel therethrough when said fan is rotated in a first direction while blocking flow of wind mass when said fan is rotated in a second opposite direction;
• a second, stationary fan diffuser adjacent said rearward end permitting said wind mass generated when said fan is rotated in said second direction to travel through said second fan diffuser while blocking flow of said wind mass when said fan is rotated in said first direction;
• and
• cooling coil means associated with one of said first and second diffusers for passing said wind mass over said cooling coils when leaving said one of said diffusers for cooling said wind mass.