The vacuum system consists of diffusion pump, mechanical pump, main valve, high vacuum flapper valve and bypass valve. The mechanical pump is a coarse vacuum device, and its power source is a three-phase AC motor. The pump stops and works through the opening and closing of the AC contactor. The high vacuum oil diffusion pump is a high vacuum device, which completes the air extraction work required by high vacuum degree with the help of diffusion pump oil, front mechanical pump and electric furnace heating, and controls the on-off of its electric heating furnace through the opening and closing of AC contactor, and then controls the stop and action of diffusion pump.
The dependence on people in the control process brings about unstable factors. Due to the long production cycle, the influence of people's emotion, experience, sense of responsibility, fatigue degree, etc., the quality is difficult to guarantee; the monitoring instruments are old and backward, and the measurement data is inaccurate, which seriously affects the quality of products. Vacuum heat treatment technology developed in the 1950s abroad, in which high temperature vacuum furnace is mainly used for smelting, metallurgy and other aspects, mainly using coke as fuel. And the low temperature vacuum furnace is mainly electric baking, which has low energy consumption and low price.
Generally, low temperature vacuum furnace is used for baking of power transformer body. In the 1970s, the high temperature vacuum furnaces for metal heat treatment, such as smelting and metal treatment, began to adopt microcomputer control and programmable controller, while the low temperature vacuum furnaces for power transformer baking were controlled by power temperature and solid temperature. There is still a certain distance between process control and production automation.
The structure, temperature control, heating process and atmosphere of high temperature vacuum furnace will directly affect the product quality after the production of vacuum furnace. In forging furnace, increasing the temperature of metal can reduce melting resistance, but too high temperature will cause grain oxidation or overburning, which will seriously affect the quality of products in vacuum furnace.
In the process of heat treatment, if the steel is heated to a point above the critical temperature, and then cooled suddenly with cooling engine, the hardness and strength of the steel can be improved; if it is heated to a point below the critical temperature and cooled slowly, the steel can be made more ductile.
On 2018-08-08 11:45:46
