Induction heating device, induction heating equipment, induction heating method, and heat treatment method

Abstract

An induction heating device is provided. The induction heating device comprises a plurality of induction heating devices disposed at intervals along the circumference of a ring-shaped workpiece, a setting unit for setting induction heating conditions, and a switching control unit. Each of the plurality of induction heating devices comprises heating coils disposed facing areas to be heated of the workpiece, a plurality of transformers connected to the heating coils in parallel, a plurality of matching units connected to any one of the plurality of transformers, an inverter unit having a rectifier unit and an inverter unit, an inverter control unit having a rectification control unit, and a group of switches.

What is claimed is: 
     
         1 . An induction heating method, comprising the step of:
 varying the frequency of induction current to be fed to the workpiece depending on the heating temperature or heating time of the workpiece when a workpiece is induction-heated while being moved; and   changing the combinations of matching units and transformers in accordance with the change in frequency.   
     
     
         2 . An induction heating method, comprising the step of:
 disposing a plurality of heating coils along a workpiece;   varying the frequency of the induction current fed to the workpiece depending on the heating temperature or heating time of the workpiece when induction heating is performed by the plurality of heating coils while the workpiece is moved; and   changing combinations of matching units and transformers depending on the change in frequency.   
     
     
         3 . A heat treatment method for providing a plurality of ring-shaped areas to be heated along a ring-shaped workpiece and performing heat treatment sequentially for each of the areas to be heated, comprising:
 a first heating process for heating a first area to be heated; a first cooling process for rapidly cooling the heated first area to be heated;   a tempering process for heating and cooling the first area to be heated after the first cooling process is completed; and   a second heating process for heating the second area to be heated after the tempering process is completed.   
     
     
         4 . The heat treatment method as set forth in  claim 3 , wherein the deformation amount that appears on one edge of the areas to be heated when the areas to be heated are heated is different from that on the other. 
     
     
         5 . The heat treatment method as set forth in  claim 3 , wherein the first area to be heated is induction-heated by using the same heating coils in the first heating process and the tempering process. 
     
     
         6 . The heat treatment method as set forth in  claim 3 , wherein the first area to be heated and the second area to be heated are induction-heated by using the same heating coils in the first heating process and the second heating process. 
     
     
         7 . The heat treatment method as set forth in  claim 6 , wherein the first area to be heated and the second area to be heated are in a plane-symmetrical shape, and the workpiece is inverted after the tempering process.