To provide a boss heating apparatus that is able to heat a boss up to such a temperature as necessary for any shrinkage fitting even in a narrow place, and besides, it will get off without installing an electric furnace equivalent to a factory.
This boss heating apparatus is so constituted that plural pieces of heaters 19 are set up in a boss hole 13 along a lower semicircumferential surface of this boss hole 13, and both ends of this hole 13 are covered with two thin metal plates 21 and 22, whereby the boss hole 13 is hermetically sealed, and further both ends of a blowhole 23 is covered with two separate thin metal plates 24 and 25, whereby this blowhole 23 is hermetically sealed, and thereby the lower semicircumferential surface of the boss hole 13 is heated by radiation, while heated air in the boss hole 13 in a state of being enclosed goes up by dint of a convection, through which an upper semicircumferential surface of the boss hole 13 is also heated. With this constitution, the whole boss 12 is uniformly heatable with little heating value.
FUJITANI KENICHI
YAMAKI MASAMITSU
YOSHIDA ISAO
HITACHI MITO ENG KK
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