Billet induction heating device providing fast heating changeover for different size billets

A billet induction heating device comprising:

• a plurality of heating coil units defining columnar holes which are different in size from one another for accommodating a billet, respectively, each of said plurality of heating coil units having a polyphase winding surrounding said columnar hole and liquid cooling means;
• said heating coil units being held in such a manner that the central axis lines of said columnar holes are in parallel with one another and are in a vertical plane;
• first reciprocating means having a first movable part which is movable in parallel with the central axial line of said hole;
• billet holding means which is coupled to said movable part of said first reciprocating means, for holding said billet at one end face thereof which is being subjected to induction heating;
• second reciprocating means having a second movable part which is movable in parallel with the central axial line of said hole;
• billet pushing means coupled to said second movable part of said second reciprocating means, for pushing the other end face of said billet when accommodating a billet in said hold;
• moving means for moving and holding one of said plurality heating coil units which is selected to accommodate a given billet therein;
• flow path opening and closing means connected in series, as flow paths, to said liquid cooling means of said plurality of heating coil units, said flow path opening and closing means supplying cooling liquid to said heating coil unit which is selected when said billet therein is subjected to induction heating;
• and
• flow rate adjusting means provided in bypass flow paths which are connected in parallel to said flow path opening and closing means, respectively.