vacuum gas quenching furnace design principle
The main structural parts of the vacuum gas quenching furnace in the vacuum furnace, the structural composition of the furnace shell, furnace door and gear ring that affect the safety of the equipment. Due to the particularity of alternating use of positive pressure and negative pressure in vacuum gas quenching furnace, in order to ensure the safety of the equipment and realize the economy of the equipment, the theoretical calculation of the furnace shell and gear ring is carried out by the calculation method and the check diagram method, and the safety analysis of the structure is carried out by the finite element analysis method. Through the mechanical model, the weak links in the design structure are optimized to meet the requirements of structural safety.
There are two kinds of quenching in vacuum: gas quenching and liquid quenching. Gas quenching means that the workpiece is cooled by filling a high purity neutral gas (such as nitrogen) into the cooling chamber after being heated in vacuum. Materials with low critical cooling rate, such as high speed steel and high carbon high chromium steel, are suitable for air quenching. Liquid quenching is to heat the workpiece in the heating chamber, move it to the cooling chamber, fill it with high-purity nitrogen and send it to the quenching oil tank immediately for rapid cooling. If high surface quality is required, tempering and precipitation hardening of workpieces after vacuum quenching and solution heat treatment shall still be carried out in vacuum furnace.
Vacuum quenching furnace: vacuum quenching furnace can be divided into vacuum oil quenching furnace and vacuum gas quenching furnace
Vacuum tempering furnace: the vacuum tempering furnace can be divided into single chamber, double chamber and vertical type. Generally, the highest temperature of nickel chromium belt heating is 800 ℃. The vacuum tempering furnace is generally applicable to parts with bright surface and no oxidation color after tempering.
Vacuum annealing furnace: it can be divided into single chamber, double chamber and vertical type. According to the part material, the vacuum annealing furnace can choose medium high temperature and low temperature (medium high temperature 800 ℃ ~ 1350 ℃, low temperature 800 ℃).
Vacuum oil quenching furnace is suitable for vacuum heat treatment of die steel, spring steel, stainless steel, bearing steel, high temperature alloy steel, etc. Its main features are wide range of applicable materials, strong hardenability, low cost and reusable quenching oil. The defects are: the deformation is relatively large, and the workpiece needs to be cleaned later. The vacuum oil quenching furnace can be divided into two chamber furnace and three chamber furnace.
Vacuum high pressure gas quenching furnace is suitable for vacuum heat treatment of high speed steel, stainless steel, die steel and other materials with good hardenability, characterized by small deformation of parts and no need to clean after heat treatment. The disadvantages are that quenching gas can not be recovered and the cost is high. Vacuum high pressure gas quenching furnace can be divided into horizontal and vertical structure. Horizontal type can be divided into single chamber, double chamber and three chambers.