Surface hardening treatment device and surface hardening treatment method

Abstract

The present, invention includes: an in-furnace atmospheric gas concentration detector configured to detect a hydrogen concentration or an ammonia concentration in a processing furnace; an in-furnace nitriding potential calculator configured to calculate a nitriding potential in the processing furnace based on the hydrogen concentration or the ammonia concentration detected by the in-furnace atmospheric gas concentration detector; and a gas-introduction-amount controller configured to change an introduction amount of each of the plurality of furnace introduction gases except for the ammonia decomposition gas while keeping an introduction amount of the ammonia decomposition gas constant. based on the calculated nitriding potential in the processing furnace and a target nitriding potential, such that the nitriding potential in the processing furnace is brought close to the target nitriding potential.

1 . A surface hardening treatment device for performing a gas nitrocarburizing treatment as a surface hardening treatment for a work arranged in a processing furnace by introducing a plurality of furnace introduction gases including an ammonia gas and an ammonia decomposition gas, the surface hardening treatment device comprising
 an in-furnace atmospheric gas concentration detector configured to detect a hydrogen concentration or an ammonia concentration in the processing furnace,   an in-furnace nitriding potential calculator configured to calculate a nitriding potential in the processing furnace based on the hydrogen concentration or the ammonia concentration detected by the in-furnace atmospheric gas concentration detector, and   a gas-introduction-amount controller configured to change an introduction amount of each of the plurality of furnace introduction gases except for the ammonia decomposition gas while keeping an introduction amount of the ammonia decomposition gas constant, based on the nitriding potential in the processing furnace calculated by the in-furnace nitriding potential calculator and a target nitriding potential, such that the nitriding potential in the processing furnace is brought close to the target nitriding potential.   
     
     
         2 . The surface hardening treatment device according to  claim 1 , further comprising
 an in-furnace oxygen concentration detector configured to detect an oxygen concentration in the processing furnace,   wherein   the in-furnace nitriding potential calculator is configured to calculate the nitriding potential in the processing furnace based on the hydrogen concentration or the ammonia concentration detected by the in-furnace atmospheric gas concentration detector and the oxygen concentration detected by the in-furnace oxygen concentration detector.   
     
     
         3 . The surface hardening treatment device according to  claim 1  wherein
 the gas-introduction-amount controller is configured to control the introduction amount C1, * * * , CN (N is an integer of one or more) of each of the plurality of furnace introduction gases except for the ammonia gas and the ammonia decomposition gas, using a factor of proportionality c1, * * * , cN assigned to each of the plurality of furnace introduction gases except for the ammonia gas and the ammonia decomposition gas, such that
     C 1= c 1×( A+x×B ), * * * , cN=cN ×( A+x×B )
 
 
 wherein the introduction amount of the ammonia gas is represented by A, the introduction amount of the ammonia decomposition gas is represented by B, and a predetermined constant is represented by x. 
 
     
     
         4 . The surface hardening treatment device according to  claim 3 , wherein
 the predetermined constant x is within 0.4 to 0.6.   
     
     
         5 . The surface hardening treatment device according to  claim 4 , wherein
 the predetermined constant x is 0.5.   
     
     
         6 . The surface hardening treatment device according to  claim 1 , wherein
 the plurality of furnace introduction gases includes a carbon dioxide gas.   
     
     
         7 . The surface hardening treatment device according to  claim 1 , wherein
 the plurality of furnace introduction gases includes a carbon monoxide gas.   
     
     
         8 . The surface hardening treatment device according to  claim 1 , wherein
 the plurality of furnace introduction gases includes a carbon dioxide gas and a nitrogen gas.   
     
     
         9 . The surface hardening treatment device according to  claim 1 , wherein
 the plurality of furnace introduction gases includes a carbon monoxide gas and a nitrogen gas.   
     
     
         10 . A surface hardening treatment method of performing a gas nitrocarburizing treatment as a surface hardening treatment for a work arranged in a processing furnace by introducing a plurality of furnace introduction gases including an ammonia gas and an ammonia decomposition gas, the surface hardening treatment method comprising
 an in-furnace atmospheric gas concentration detecting step of detecting a hydrogen concentration or an ammonia concentration in the processing furnace,   an in-furnace nitriding potential calculating step of calculating a nitriding potential in the processing furnace based on the hydrogen concentration or the ammonia concentration detected at the in-furnace atmospheric gas concentration detecting step, and   a gas-introduction-amount controlling step of changing an introduction amount of each of the plurality of furnace introduction gases except for the ammonia decomposition gas while keeping an introduction amount of the ammonia decomposition gas constant, based on the nitriding potential in the processing furnace calculated at the in-furnace nitriding potential calculating step and a target nitriding potential, such that the nitriding potential in the processing furnace is brought close to the target nitriding potential.   
     
     
         11 . A surface hardening treatment device for performing a gas nitrocarburizing treatment as a surface hardening treatment for a work arranged in a processing furnace by introducing a plurality of furnace introduction gases including an ammonia gas, an ammonia decomposition gas and a carburizing gas, the surface hardening treatment device comprising
 an in-furnace atmospheric gas concentration detector configured to detect a hydrogen concentration or an ammonia concentration in the processing furnace,   an in-furnace nitriding potential calculator configured to calculate a nitriding potential in the processing furnace based on the hydrogen concentration or the ammonia concentration detected by the in-furnace atmospheric gas concentration detector, and   a gas-introduction-amount controller configured to change an introduction amount of each of the ammonia gas and the carburizing gas while keeping an introduction amount of the ammonia decomposition gas constant, based on the nitriding potential in the processing furnace calculated by the in-furnace nitriding potential calculator and a target nitriding potential, such that the nitriding potential in the processing furnace is brought close to the target nitriding potential.   
     
     
         12 . The surface hardening treatment device according to  claim 11 , wherein
 the gas-introduction-amount controller is configured to control the introduction amount C1 of the carburizing gas, using a factor of proportionality c1 assigned to the carburizing gas, such that
     C 1= c 1×( A+x×B )
 
   wherein the introduction amount of the ammonia gas is represented by A, the introduction amount of the ammonia decomposition gas is represented by B, and a predetermined constant is represented by x.   
     
     
         13 . A surface hardening treatment device for performing a gas nitrocarburizing treatment as a surface hardening treatment for a work arranged in a processing furnace by introducing a plurality of furnace introduction gases including an ammonia gas, an ammonia decomposition gas, a carburizing gas and a nitrogen gas, the surface hardening treatment device comprising
 an in-furnace atmospheric gas concentration detector configured to detect a hydrogen concentration or an ammonia concentration in the processing furnace,   an in-furnace nitriding potential calculator configured to calculate a nitriding potential in the processing furnace based on the hydrogen concentration or the ammonia concentration detected by the in-furnace atmospheric gas concentration detector, and   a gas-introduction-amount controller configured to change an introduction amount of each of the ammonia gas, the carburizing gas and the nitrogen gas while keeping an introduction amount of the ammonia decomposition gas constant, based on the nitriding potential in the processing furnace calculated by the in-furnace nitriding potential calculator and a target nitriding potential, such that the nitriding potential in the processing furnace is brought close to the target nitriding potential.   
     
     
         14 . The surface hardening treatment device according to  claim 13 , wherein
 the gas-introduction-amount controller is configured to control the introduction amount C1 of the carburizing gas and the introduction amount C2 of the nitrogen gas, using a factor of proportionality c1 assigned to the carburizing gas and a factor of proportionality c2 assigned to the nitrogen gas, such that
     C 1= c 1×( A+x×B ) and  C 2= c 2×( A+x×B )
 
   wherein the introduction amount of the ammonia gas is represented by A, the introduction amount of the ammonia decomposition gas is represented by B, and a predetermined constant is represented by x.   
     
     
         15 . The surface hardening treatment device according to  claim 2 , wherein the gas-introduction-amount controller is configured to control the introduction amount C1, * * * , CN (N is an integer of one or more) of each of the plurality of furnace introduction gases except for the ammonia gas and the ammonia decomposition gas, using a factor of proportionality c1, * * * , cN assigned to each of the plurality of furnace introduction gases except for the ammonia gas and the ammonia decomposition gas, such that
     C 1= c 1×( A+x×B ), * * * , cN=cN ×( A+x×B )
   wherein the introduction amount of the ammonia gas is represented by A, the introduction amount of the ammonia decomposition gas is represented by B, and a predetermined constant is represented by x.   
     
     
         16 . The surface hardening treatment device according to  claim 15 , wherein the predetermined constant x is within 0.4 to 0.6. 
     
     
         17 . The surface hardening treatment device according to  claim 16 , wherein the predetermined constant x is 0.5.