PURPOSE: To always stably carry out tempering work of a saw blade by moving the position of a nozzle by the specified quantity when a flame blown up from the nozzle of a heating means approaches a specified place of the saw blade formed by depositing hard metal on the edge.

CONSTITUTION: When the hard metal 1a is deposited on the edge of the saw blade 1 by a deposition means 2, a delivery means 3 operates in the arrow direction 16 and the saw blade 1 is moved by the specified quantity and comes to the specified position. At this time, a piston 8 is operated and a blowpipe holding means 11 at the chain line position pushes a damper 14 with a rotation axis 13 as a center and rotates up to the position of a solid line and the specified place of the saw blade 1 is heated by the flame 10 blown up from the nozzle 9a of a blowpipe 9. Further, a nozzle moving means 15 is operated and the nozzle 9a of the blowpipe 9 is slightly receiprocated and the flame 10 is moved in the vicinity of the edge and the specified place of the saw blade 1 is heated surely. When this tempering work is completed, the piston 8 is again operated and the blowpipe holding means 11 is returned up to the former chain line position and the flame 10 is also separated from the vicinity of the edge of the saw blade 1. The stable tempering of the saw blade 1 is always carried out by repeating this operation.