Box-type gas carburizing furnace for metal heat treatment

The invention provides a box-type gas carburizing furnace for metal heat treatment, which comprises a furnace body, the top of the furnace body is fixedly connected with a top cover, the bottom of the top cover is fixedly connected with an instillation plate, and the lower part of the interior of the furnace body is fixedly connected with a circulating air bellow. The instillation pipes are distributed at the bottom of the instillation plate in a triangular shape, the blocking plate is movably arranged in the instillation pipes from top to bottom through the springs, the diameter of the blocking plate is the same as the inner diameter of the instillation pipes, and the through hole is formed in the middle of the interior of the blocking plate, so that pressure is applied downwards through the pressure of liquid, the blocking plate is moved, and therefore the blocking plate is opened; according to the instillation control device, liquid is made to flow, an operator can adjust the flowing speed of the liquid ac