Provided is an external-heat vacuum cementation furnace of tank type, which belongs to the field of heat treatment industry, in particular to an external-heat
vacuum furnace with a muffle tank to heat. To resolve the
pollution problem of carburization of a heating chamber, the carburization cella of the device is designed to be a sealing structure, the muffle tank body is firstly vacuumized before
carburizing gas is charged in, and then the
carburizing gas is charged in to carry on
diffusion carburization, as the muffle tank is of sealed type, the
heating system of the heating chamber can not be polluted, and the heating chamber can not be damaged. The device is in a bottom feeding vertical structure, the furnace body is in a double-walled water-cooling structure, the upper portion is a heating carburization chamber, the lower portion is a high-pressure air
quenching chamber which is provided with a hydro cylinder, work pieces can be directly conveyed into the muffle tank to be heated and the muffle tank can be sealed by the hydro cylinder, when the heating carburization is completed, the hydro cylinder drops down and gets into a
quenching area, then the
high pressure positive blower is charged and starts to quench. Simultaneously, a middle gate
locking plate valve is closed and the heating chamber can be continuously kept in a high temperature state, which brings
heat energy and
efficacy to secondary operation. The device is composed of a water-cooling furnace wall, a heating chamber, a muffle tank, an air charging
system, a vacuum-pumping
system, a
high pressure positive blower, a heat interchanger, a feeding structure, and the like.