How to Pressure and Inflate the Vacuum Hot Press Furnace
Vacuum hot pressing furnace is widely used because of its own structural advantages.
The vacuum hot pressing furnace is a vertical structure with double water interlayer structure. The inner, outer walls and flanges are 304 stainless steel. The furnace body is divided into two parts, one third of which is that the furnace cover can be opened completely by hand, and two thirds of which are fixed furnace body. The design is unique and easy to operate. The vacuum system of vacuum hot pressing furnace consists of oil diffusion pump, Roots pump, mechanical pump distribution electromagnetic pressure differential valve (to prevent sudden power outage, mechanical pump oil backfilling) inflatable valve, exhaust valve, vacuum butterfly valve, vacuum pressure gauge (+Pa) bellows, vacuum pipeline and support, etc.
Pressure operation steps of vacuum hot pressing furnace:
1. Put two graphite pillars at the bottom, then put a mould, and put a graphite pillar on top.
2. The pressure rises to the graphite pillar level with the insulating barrel.
3. Close the furnace cover;
4. Vacuum first and lock the three screw locks on the furnace cover.
5. Turn on the "hydraulic pump" and select the cylinder to "rise" to the pressure block on the furnace cover to move up 3-4 mm, and then the cylinder to "drop" to 0 mm.
6. Manually turn the upper pressure head on the furnace cover down, hold the furnace cover, lock, and turn the round one up to protect the lock.
7. Cold pressure, choose the cylinder to "rise" until the displacement and pressure are constant.
8. Choose the "stop" of the cylinder and switch the pressure control from the "potentiometer" to the "instrument" until the pressure gauge is consistent, then the "heating" can be achieved.
9. Set up the heating curve to raise the temperature, and then select the cylinder to "rise" pressure after the temperature reaches 200 C.
10. After heating, when the furnace temperature drops below 1000 C, the cylinder "stops" and "instrument" is switched to "potentiometer".
Note: The pressure gauge shows 16MPa, which is equivalent to the computer display of 20t, and the graphite mould can bear the maximum pressure of 30MPa. According to the force area of the specific die, the required pressure can be calculated, such as: the diameter of the die is 30, the maximum force is 2.1t, if the pressure is 1.7t, the pressure gauge is set to 1.4MPa, then the sample pressure in the die is 23 MPa; the diameter of the die is 50, the maximum force is 6.0t, such as the pressure of 3.0t, the pressure. The force meter can be set to 2.4 MPa, and the sample pressure in the die is 15 MPa.
The air charging operation steps of vacuum hot pressing furnace are as follows:
1) No matter whether the furnace is heated or not, it can be inflated.
2) Wash the furnace three times for the first time. Close the butterfly valve, the main baffle valve, the diffusion pump and the inflatable valve.
3) When the pressure is - 0.06MPa, close the "inflatable" and open the "upper butterfly valve" to exhaust to - 0.1MPa.
4) Open the "inflatable" again, so three times, the fourth "inflatable" to + 0.01 MPa can be closed "inflatable", argon (nitrogen) cylinder can be closed;
5) One hour later, close the "lower butterfly valve" and "mechanical pump".
6) Cool down to below 1000 C, open "mechanical pump", open "upper butterfly valve", open "lower butterfly valve", and vacuum less than 20Pa.