Retort Furnace for Heat Treating Metal Workpieces

Abstract

In a retort furnace having a heating assembly, a circulation unit, and an assigned cooling unit, uniform and rapid cooling of the heat-treated workpieces is achieved by three solution variants. The first variant includes a second floor ( 9.1 ) assembled to a floor ( 9 ) to form an intermediate space which is divided into two ring spaces which are isolated gastight from one another including a first volume space ( 16 ) and a second volume space ( 17 ). The second variant includes situating throttle valves ( 20, 21 ) in a housing ( 36 ), each valve having a receptacle space ( 33 ), into which a valve plug is movable. In the third variant which is a combination of the first and second variants, the first volume space ( 16 ) and the second volume space ( 17 ) are adapted to interact for flow technology in such a manner that in the open position of the plug, the flow cross-section of each line ( 11, 14 ) is completely unblocked and provides circulation of a cold gas with favorable flow and therefore rapid cooling of the batch ( 7 ).

1 . A retort furnace ( 1 ) for the heat treatment of metal workpieces, having a cylindrical retort ( 3 ), which is enclosed by a furnace housing ( 2 ) having a heating assembly ( 5 ), and which
 a) encloses a treatment space ( 6 ) for a batch ( 7 ) of workpieces,   b) is closed gastight at one end using a floor ( 9 ) and has flow connections to at least first and second gas-conducting lines ( 11 ,  14 ), which are each closable using a throttle valve ( 20 ,  21 ), and   c) has a gastight closable charging opening ( 10 ) at the other end, wherein a gas stream can be suctioned out of the retort ( 3 ), conducted through an external cooling unit, and subsequently returned back into the retort ( 3 ), and wherein a cold gas can be circulated to cool the workpieces, and wherein the improvement comprises the floor ( 9 ) including a cylindrical second floor ( 9 . 1 ) that forms an intermediate space and the intermediate space is divided into two ring spaces isolated gastight from one another including a first volume space ( 16 ) and a second volume space ( 17 ), the first volume space ( 16 ) being connected to the first gas-conducting line ( 14 ) and the second volume space ( 17 ) being connected to the second gas-conducting line ( 11 ), whereby the circulation of the cold gas can be accelerated using a coolant volume flow having favorable flow and whereby cooling of a batch ( 7 ) can be accelerated.   
     
     
         2 . A retort furnace ( 1 ) for the heat treatment of metal workpieces, having a cylindrical retort ( 3 ), which is enclosed by a furnace housing ( 2 ) having a heating assembly ( 5 ), and which
 a) encloses a treatment space ( 6 ) for a batch ( 7 ) of workpieces,   b) is closed gastight at one end using a floor ( 9 ) and has flow connections to at least two gas-conducting lines ( 11 ,  14 ), which are each closable by means of first and second throttle valves ( 20 ,  21 ), and   c) has a gastight closable charging opening ( 10 ) at the other end, wherein the improvement comprises the first and second throttle valves ( 20 ,  21 ) each have a housing ( 36 ) comprising a receptacle space ( 33 ), into which a valve plug ( 25 ) is movable in such a manner that the flow cross-section of each line ( 11 ,  14 ) is completely unblocked in the open position of the valve plug ( 25 ), and an implementation of the receptacle space ( 33 ) for favorable flow is provided and a gaseous volume stream can be guided with favorable flow in each line ( 11 ,  14 ).   
     
     
         3 . A retort furnace ( 1 ) for the heat treatment of metal workpieces, having a cylindrical retort ( 3 ), which is enclosed by a furnace housing ( 2 ) having a heating assembly ( 5 ), and which
 a) encloses a treatment space ( 6 ) for a batch ( 7 ) of workpieces,   b) is closed gastight at one end using a floor ( 9 ) and has flow connections to at least first and second gas-conducting lines ( 11 ,  14 ), which are each closable by means of first and second throttle valves ( 20 ,  21 ), and   c) has a gastight closable charging opening ( 10 ) at the other end, wherein the improvement comprises:   d) the floor ( 9 ) comprises a second floor ( 9 . 1 ) that forms an intermediate space and the intermediate space is divided into two ring spaces isolated gastight from one another including a first volume space ( 16 ) and a second volume space ( 17 ), the first volume space ( 16 ) being connected to the second gas-conducting line ( 14 ) and the second volume space ( 17 ) being connected to the first gas-conducting line ( 11 ),   e) the first and second throttle valves ( 20 ,  21 ) each have a housing ( 36 ) comprising a receptacle space ( 33 ), into which a valve plug ( 25 ) is movable in such a manner that the flow cross-section of each line ( 11 ,  14 ) is completely unblocked when the plug is in the open position, and   f) the first volume space ( 16 ) and the second volume space ( 17 ), in flow interaction with the functions of the plug ( 25 ) which completely unblocks the flow cross-section of each gas-conducting line ( 11 ,  14 ) in the open position of the plug ( 25 ), and permits a circulation of the cold gas with favorable flow to provide rapid cooling of the batch ( 7 ).   
     
     
         4 . The retort furnace according to  claim 1  or  3 , wherein the external diameter of the second floor ( 9 . 1 ) is dimensioned smaller than the internal diameter of the retort ( 3 ). 
     
     
         5 . The retort furnace according to  claim 1  or  3 , wherein the first volume space ( 16 ) has a flow connection with the second gas-conducting line ( 14 ) to an external coolant gas fan ( 13 ). 
     
     
         6 . The retort furnace according to  claim 1  or  3 , wherein the second volume space ( 17 ) has a flow connection with the first gas-conducting line ( 11 ) to an external cooler ( 12 ). 
     
     
         7 . The retort furnace according to  claim 1  or  3 , wherein the second volume space ( 17 ) is connected to suction pipes ( 19 ), which are connected to the treatment space ( 6 ) enclosed by the retort ( 3 ). 
     
     
         8 . The retort furnace according to  claim 1  or  3 , wherein the first volume space ( 16 ) and the second volume space ( 17 ) are formed as two concentric ring spaces isolated gastight from one another by a ring ( 18 ). 
     
     
         9 . The retort furnace according to  claim 2  or  3 , wherein the valve plug ( 25 ), which is movable into the receptacle space ( 33 ) of the housing ( 36 ) of each throttle valve ( 20 ,  21 ), has a pivot arm ( 22 ), which is connected to a holding arm ( 27 ) so it is pivotable around a pivot point ( 32 ). 
     
     
         10 . The retort furnace according to  claim 9 , wherein the pivot arm ( 22 ) is connected to the holding arm ( 27 ) so it is pivotable through an angle that is greater than about 90°. 
     
     
         11 . The retort furnace according to  claim 9 , wherein the pivot arm ( 22 ) is connected to a drive mechanism ( 28 ). 
     
     
         12 . The retort furnace according to  claim 11 , wherein the drive mechanism ( 28 ) comprises a pneumatic positioning cylinder. 
     
     
         13 . The retort furnace according to  claim 2  or  3 , wherein the housing ( 36 ) is removably connected to one of the gas-conducting lines ( 11 ,  14 ) using a first flange connection ( 23 ) and a second flange connection ( 24 ). 
     
     
         14 . The retort furnace according to  claim 13 , wherein the housing ( 36 ) has an installation opening ( 34 ), which is closable by means of a cover lid ( 35 ). 
     
     
         15 . The retort furnace according to  claim 14 , wherein the drive mechanism ( 28 ) is mounted on the cover lid ( 35 ) and has a piston rod ( 29 ) which extends through the cover lid ( 35 ) gastight, and which is linked to the pivot arm ( 22 ) using a coupling element ( 30 ) of the piston rod ( 29 ) and an oblong hole ( 30 ) of the pivot arm ( 22 ) to actuate the plug ( 25 ). 
     
     
         16 . The retort furnace according to  claim 15 , wherein the holding arm ( 27 ) is connected to the cover lid ( 35 ).