Structural characteristics of vacuum quenching furnace
In the category of vacuum furnace, vacuum quenching furnace is the most widely used and typical equipment.
The vacuum quenching furnace has the following characteristics:
1. The strict vacuum sealing it is well known that vacuum heat treatment heating and quenching workpiece were conducted in airtight vacuum furnace, so ensure vacuum degree of vacuum quenching furnace, and to ensure the quality of the parts of the vacuum heat treatment has very important significance. In order to ensure the vacuum performance of the vacuum furnace, kejia vacuum furnace body adopts airtight welding, with few holes in it to minimize the chance of vacuum leakage. The components and accessories installed on the vacuum furnace such as water-cooled electrode and thermocouple export device are also sealed.
2. Most of the heating and insulation materials can only be used in the vacuum of the vacuum quenching furnace heating and insulation lining is working under vacuum and high temperature, these materials have high temperature resistant, low steam, radiation effect is good, low coefficient of thermal conductivity, etc. As most domestic vacuum quenching furnace mainly adopts graphite heating and heat insulation structure material, it is heated extremely easy oxidation under atmospheric conditions, therefore, the conventional heat treatment furnace can not use these heating and insulation materials, families, poor vacuum furnace chamber of a stove or furnace adopts imported alumina fiber made from vacuum adsorption heat preservation and heat insulation effect is better.
3. The furnace shell, cover, electric heating element (water-cooled electrode) and heat insulation heating element of the vacuum furnace of the water cooling device all work under vacuum and heat. Working under such extremely unfavorable conditions, it is necessary to ensure that the structure of each component is not deformed or damaged, and the vacuum seal ring is not overheated or burnt down. Therefore, each component is equipped with water cooling device according to different conditions to ensure the normal operation of the vacuum furnace and sufficient service life.
4. Heating the workpiece with low voltage large current In the vacuum heat treatment furnace, when the vacuum degree to a few hundred mpa (Pa), electric conductor under high voltage, can produce glow discharge phenomenon, serious can produce arc discharge, burning electric heating element, insulation, etc., cause serious accident and loss. Therefore, the working voltage of the electric heating element in the vacuum heat treatment furnace is generally no more than 80-100 volts. At the same time, the electric heating element should avoid the parts with the tip, and the distance between electrodes should not be too narrow, so as to prevent the occurrence of glow discharge or arc discharge.
5. The high degree of automation requires more than ten or even dozens of actions to complete the heating and cooling operations of metal workpieces. All these actions are carried out in the vacuum furnace, which is inaccessible to the operator. At the same time, some actions, such as the end of heating and heat preservation, the quenching process of metal workpieces requires multiple actions and should be completed in a short time. In such a rapid condition to complete a lot of actions, it is easy to cause the operator tension and misoperation. Therefore, the vacuum furnace is controlled by a high degree of automation.