Heat treatment apparatus and heat treatment method

Abstract

A heat treatment apparatus 10 comprises a supporting unit 20 for supporting a columnar workpiece 12 turnably, and an induction-heating coil 30 for induction-heating the workpiece 12 supported turnably by the supporting unit 20 . Below the workpiece 12 supported by the supporting unit 20 , a cooling tank 50 is provided which contains a liquid coolant. The workpiece 12 is made of steel such as carbon steel for mechanical structure, and spring steel. The workpiece 12 is made of a material which has a magnetic transformation point at 770° C. The material is ferromagnetic below this temperature, and becomes paramagnetic above this temperature.

1 . A heat-treatment apparatus, comprising a supporting means for supporting a workpiece turnably around a turning axis, and 
 a fixed induction-heating coil for induction-heating a belt zone, extending parallel to the turning axis, of the workpiece supported by the supporting means.    
   
   
       2 . A heat-treatment apparatus, comprising a supporting means for supporting a workpiece turnably around a turning axis, and 
 an induction-heating coil opposed to a belt zone, extending parallel to the turning axis, of the workpiece supported by the supporting means.    
   
   
       3 . A heat-treatment apparatus, comprising a supporting means for supporting a columnar workpiece to be turnable in a periphery direction around a turning axis extending in a length direction, and 
 an induction-heating coil opposed to a belt zone, extending parallel to the turning axis, of a peripheral face of the workpiece supported by the supporting means.    
   
   
       4 . A heat-treatment apparatus, comprising a rod-shaped supporting means for supporting a tubular workpiece, inserted into a hollow of the workpiece, to be turnable in a periphery direction around a turning axis extending in a length direction, and 
 an induction-heating coil opposed to a belt zone of a peripheral face of the workpiece and extending parallel to the turning axis of the workpiece supported by the supporting means.    
   
   
       5 . The heat treatment apparatus according to any of  claims 1  to  4 , wherein the supporting means supports a workpiece which is ferromagnetic at a temperature below the magnetic transformation point thereof and becomes paramagnetic at a temperature above the magnetic transformation point.  
   
   
       6 . The heat treatment apparatus according to any of  claims 1  to  5 , wherein the supporting means is movable from a position for supporting the workpiece to another position to release the workpiece to fall, and is provided with a cooling tank containing a coolant below the workpiece supported by the supporting means.  
   
   
       7 . The heat treatment apparatus according to any of  claims 1  to  6 , wherein the induction-heating coil is constituted of a pair of partial coils placed in opposition on both sides of the workpiece.  
   
   
       8 . The heat treatment apparatus according to any of  claims 1  to  7 , wherein the induction-heating coil is in a rectangle shape, and 
 the supporting means is placed between a pair of long sides of the rectangle-shaped induction-heating coil, and    supports the workpiece extending parallel to the pair of the long sides.    
   
   
       9 . A heat-treatment apparatus, comprising 
 a ceramic supporting rod inserted in a hollow of a helix member for supporting the helix member formed from a wire material which is transformed from ferromagnetic to paramagnetic by temperature elevation above the magnetic transformation point, to be turnable in the periphery direction of the helix member, and    an induction-heating coil placed to face counterposed portions, on both sides of the supporting rod, of the peripheral face of the helix member supported by the supporting rod.    
   
   
       10 . The heat treatment apparatus according to claims  9 , wherein the induction-heating coil is constituted of a pair of partial coils placed in opposition on both sides of the helix member.  
   
   
       11 . The heat treatment apparatus according to  claim 10 , wherein the pair of the partial coils extend along the peripheral face of the helix member in the length direction thereof, and 
 the supporting rod is placed between the pair of the partial coils, and extends parallel to the pair of the partial coils.    
   
   
       12 . The heat treatment apparatus according to any of claims  9 ,  10 , and  11 , wherein the supporting rod is movable from a position for supporting the helix member to another position to release the helix member to fall, and is provided with a cooling tank containing a coolant below the helix member supported by the supporting rod.  
   
   
       13 . A heat treatment method for a workpiece, comprising supporting the workpiece turnably around a turning axis, induction-heating a belt zone, extending parallel to the turning axis, of the workpiece by bringing an induction-heating coil near to the belt zone, 
 allowing the workpiece to turn by a magnetic force, when the belt zone has been heated above a predetermined temperature, to bring another portion other than the belt zone near to the induction coil, and    induction-heating the portion.    
   
   
       14 . A heat treatment method for a columnar workpiece, comprising supporting the columnar workpiece turnably in a periphery direction, 
 induction-heating a belt zone, extending in a height direction, of the columnar workpiece by bringing an induction-heating coil near to the belt zone,    allowing the columnar workpiece to turn by a magnetic force, when the belt zone has been heated above a predetermined temperature, to bring another portion other than the belt zone near to the induction coil, and    induction-heating the portion.    
   
   
       15 . A heat treatment method for a tubular workpiece, comprising supporting the tubular workpiece to be turnable in a periphery direction of the tubular workpiece by a rod-shaped supporting means inserted into a hollow of the workpiece, 
 induction-heating a belt zone, extending parallel to the supporting means, of the peripheral face of the tubular workpiece by bringing an induction-heating coil near to the belt zone,    allowing the tubular workpiece to turn by a magnetic force, when the belt zone has been heated above a predetermined temperature to bring a portion other than the belt zone near to the induction coil, and    induction-heating the portion.    
   
   
       16 . A heat treatment method for a helix member, comprising 
 supporting the helix member turnably in a direction of the periphery thereof by a ceramic supporting rod inserted into a hollow of the helix member formed from a material which is transformed from ferromagnetic to paramagnetic by temperature elevation above the magnetic transformation point,    induction-heating opposed portions of the peripheral face of the helix member, supported by the supporting rod on the both sides of the supporting rod, by bringing an induction-heating coil near to the opposed portions,    allowing the helix member to turn by a magnetic force, when the belt zone has been heated above a predetermined temperature, to bring portions other than the opposed portions near to the induction coil, and    induction-heating the portions.    
   
   
       17 . The heat treatment method according to  claim 16 , wherein the helix member is allowed to fall, when the helix member has heated up to a predetermined hardening temperature, into a cooling tank containing a coolant by pulling the supporting rod out of the hollow portion of the helix member.  
   
   
       18 . A heat-treatment apparatus, comprising 
 a ceramic supporting rod inserted in a hollow of a coil spring for supporting the coil spring formed from a wire material which is transformed from ferromagnetic to paramagnetic by temperature elevation above the magnetic transformation point to be turnable in the periphery direction of the coil spring, and    an induction-heating coil placed to face counterposed portions, on both sides of the supporting rod, of the peripheral face of the coil spring supported by the supporting rod.    
   
   
       19 . The heat treatment apparatus according to claims  18 , wherein the induction-heating coil is constituted of a pair of partial coils placed in opposition on both sides of the coil spring.  
   
   
       20 . The heat treatment apparatus according to  claim 19 , wherein the pair of the partial coils extend along the peripheral face of the coil spring in the length direction thereof, and 
 the supporting rod is placed between the pair of the partial coils, and extends parallel to the pair of the partial coils.    
   
   
       21 . The heat treatment apparatus according to any of claims  18 ,  19 , and  20 , wherein the supporting rod is movable from a position for supporting the helix member to another position to release the helix member to fall, and is provided with a cooling tank containing a coolant below the coil spring supported by the supporting rod.  
   
   
       22 . A heat treatment method for a coil spring, comprising supporting the coil spring turnably in a direction of the periphery thereof by a ceramic supporting rod inserted into a hollow of the coil spring formed from a material which is transformed from ferromagnetic to paramagnetic by temperature elevation above the magnetic transformation point, 
 induction-heating opposed portions of the peripheral face of the coil spring, supported by the supporting rod on the both sides of the supporting rod, by bringing an induction-heating coil near to the opposed portions,    allowing the coil spring to turn by a magnetic force, when the belt zone has been heated above a predetermined temperature, to bring portions other than the opposed portions near to the induction coil, and    induction-heating the portions.    
   
   
       23 . The heat treatment according to  claim 22 , wherein the coil spring is allowed to fall, when the coil spring has heated up to a predetermined hardening temperature, into a cooling tank containing a coolant by pulling the supporting rod out of the hollow portion of the coil spring.