Vacuum Gas Quenching Furnace Cautions
Vacuum gas quenching furnace is mainly used for bright quenching and sintering of magnetic materials, bright annealing and vacuum brazing of various alloy steel or steel structure, tool and die steel, spring steel, stainless steel, bearing steel, precision alloy steel, etc. Therefore, many steel processing enterprises need a large number of vacuum gas quenching furnace welding and other heat treatment construction, in the steel industry for a long time has been in short supply. Now let's introduce some points for attention in the use of vacuum gas quenching furnace.
1. Vacuum sealing should be firm:
As we all know, vacuum heat treatment of most parts is carried out in a sealed vacuum air quenching furnace. Therefore, it is of great importance to obtain the original leakage rate of the vacuum furnace and ensure that the vacuum furnace is not vacuum. Therefore, a key problem of the vacuum heat treatment furnace is to have a reliable vacuum sealing structure in order to ensure the quality of the vacuum heat treatment of the parts. In order to verify the vacuum performance of vacuum furnace, a basic principle must be followed in the structural design of vacuum heat treatment furnace, that is, the furnace body should be welded with air tightness, and at the same time, the furnace body should be opened or not opened as little as possible, and the dynamic sealing structure should be adopted or avoided to minimize the chance of vacuum leakage. The components and accessories installed on the vacuum furnace body, such as water-cooled electrodes and thermocouples, should be exported and installed. The stomach must also be sealed.
2. Most heating and insulation materials can only be used in straight air
The heating and insulating lining of classical air heat treatment furnace works in vacuum and high temperature. As a result, the requirements of high temperature resistance, low vapor pressure, good radiation effect, low thermal conductivity and low oxidation performance are put forward for this material. Therefore, tungsten, platinum and graphite are widely used as heating and insulating materials in classical air heat treatment furnace. This material is very easy to track in atmospheric state. Therefore, conventional heat treatment furnace can not use this heating and insulation material.
3. Using Low Voltage and High Current
In stone vacuum vessel, glow discharge will occur when the conductor in vacuum vessel beats high voltage. In vacuum heat treatment furnace, arc discharge will occur seriously, which will destroy the electric heating elements and insulation layer, causing serious accidents and loss. Therefore, the working voltage of the electric heating elements in vacuum heat treatment furnace generally does not exceed 80-100 volts, and at the same time, the junction of the electric heating elements will occur. Effective measures should be taken in the design of the structure, such as avoiding cutting-edge parts as far as possible, and the spacing between electrodes should not be too narrow to prevent glow discharge or arc discharge.
4. Higher degree of automation
The high degree of automation of vacuum heat treatment furnace is due to the fact that the operation of heating and cooling of metal workpiece needs dozens or even dozens of actions to complete. These actions are carried out in vacuum heat treatment furnace, which is inaccessible to operators. At the same time, if the heating and heat preservation are finished, the quenching process of workpiece should take six actions and be completed in less than 15 seconds. In such a fast condition, it is easy to cause operator tension and misoperation. Therefore, only a higher degree of self-function can coordinate work accurately and timely according to the procedure.
5. Setting up water cooling devices according to different situations
Water-cooled devices, shell, cover and electrothermal components of vacuum heat treatment furnace, which are disposed of separately (water-cooled electrode) and heat insulation components in the middle vacuum, all work in the vacuum and heating state. In this extremely unfavorable condition, the structure of each component must be guaranteed to be deformed, minor damage, and the vacuum sealing ring is not hot or burnt. Therefore, each component should be based on different conditions. In order to ensure the normal operation of vacuum heat treatment furnace and sufficient service life, water cooling device is set up.