在一个感应线圈上同时产生中频和高频电流,在工件表面感应漩涡电流,使工件表面在极短的时间内迅速加热,然后急速冷却,在工件表面获取轮廓硬化层的感应淬火技术。德国eldec在2000年第一台同步双频SDF?感应发生器注册专利并交付使用;2004年第一台功率为1MW的SDF?同步双频淬火系统交付使用;2006年 Produce intermediate frequency and high frequency current on one induction coil at the same time, induce eddy current on the surface of the workpiece, make the surface of the workpiece rapidly heated in a very short period of time, then rapidly cool down and obtain the hardening hardening layer induction hardening technology on the surface of the workpiece. Germany eldec registered the first patent of synchronous SDF? Induction generator in 2000 and delivered it for use; the first SDF? Synchronous dual-frequency quenching system with power of 1 MW was delivered in 2004;