Commonly used multi-purpose furnace heat treatment furnaces include box-type resistance furnaces, well-type resistance furnaces, gas carburizing furnaces, and salt bath furnaces.
(1) Box-type resistance furnace. Its working principle is to use electric current to generate heat through electric heating elements arranged in the furnace, and to heat parts by electric current and radiation. It is a widely used heating equipment in heat treatment workshop. Suitable for heating of steel materials and non-steel materials (non-ferrous metals) for annealing, normalizing, quenching, tempering and solid carburizing. It has the advantages of easy operation, accurate temperature control, protective gas can be passed in to prevent oxidation when the parts are heated, and good working conditions.
(2) Well resistance furnace. The working principle of the well-type resistance furnace is the same as that of the box-type resistance furnace. There are three commonly used medium temperature well furnaces, low temperature well furnaces and gas carburizing furnaces. The well type resistance furnace uses cranes to lift parts, which can reduce labor intensity, so it is widely used.
The medium temperature well furnace is mainly used for heat treatment such as quenching, annealing and normalizing of dry long parts. Its high working temperature is 950 ° C. Compared with the box furnace, the pit furnace has better heat transfer. The furnace top can be equipped with a fan to make the temperature distribution more uniform. The vertical placement of the slender parts can overcome the bending deformation caused by the self-weight when the parts are placed horizontally.
(3) Salt bath furnace. The salt bath furnace is a furnace type using molten salt as a heating medium. The salt bath furnace has a simple structure, convenient manufacturing, low cost, good heating quality, and fast heating speed, so it is widely used. However, when heating the salt bath furnace, there are processes such as tying and clamping parts, complicated operations, high labor intensity, poor working conditions, and shortcomings such as long heating time at startup. Therefore, the salt bath furnace is often used for small and medium-sized parts with high surface quality requirements.