METHOD FOR REMELTING AND HARDENING MEMBER MADE OF CAST IRON

摘要

PURPOSE:To maintain the depth and hardness of a hardened layer at approximately specified values by preheating a member made of cast iron under specified conditions, measuring the time when a prescribed temp. is attained, comparing the time with a predetermined value and controlling the energy output of a treating torch by the difference therebetween. CONSTITUTION:The member made of the cast iron, for example, a cam shaft 1 is supported by supporting electrodes 2, 3 in a preheating station I and is pulse heated by a preheating power source 4 via a preheating controller 5 by the command of a program unit 6. The time when the cam shaft 1 attains the prescribed temp. or the temp. after the specified heating time is measured by a temp./time measuring instrument 9 via a temp. sensor 8 and is outputted to the preheating controller 5. The cam shaft 1 preheated to the prescribed temp. is supported by supporting centers 11, 12 in a remelting station II and is rotationally driven. A TIG torch 13 connected to a melting power source 14 is moved axially to irradiate the cam part 1a with the beam of high-density energy, by which the cam part is remelted and heated. The heating energy is controlled by the program unit 6 in accordance with the measurement data of the measuring instrument 9 at this time.