Wed, 05 Sep 2018 07:25:36 +0000
vacuum hot pressing furnace how to pressurize and inflate
Vacuum hot pressing furnace is widely used because of its structural advantages. The vacuum hot-pressing furnace is a vertical structure with double-layer water sandwich structure. The inner and outer walls and flanges are 304 stainless steel. The furnace body is divided into two parts. One third of the furnace cover can be manually and completely opened on the side. Two thirds of the furnace body is fixed. The design is unique and easy to operate. Vacuum system of vacuum hot-pressing furnace is composed of oil diffusion pump, Roots pump, mechanical pump distribution electromagnetic pressure differential valve (to prevent sudden power failure, mechanical pump oil backfilling) air valve, bleed valve, vacuum butterfly valve, vacuum pressure gauge (+Pa) bellows, vacuum pipeline and support, etc.
The operation steps of vacuum hot pressing furnace are as follows:
First, put two graphite pillars underneath, then put the mold on the top and put a graphite pillar on it.
2. Pressure rises to the graphite pillar and flask.
Close the lid.
First, vacuum and lock the three screw locks on the furnace cover.
_Open the “hydraulic pump”, select the cylinder “up” to the cover of the pressure block moved up 3-4 mm, and then the cylinder “down” to 0 mm;
_Manually turn the top pressure head on the furnace cover down, hold the furnace cover, lock, round also turn up to protect the lock;
When cold pressure is selected, the cylinder should be raised to a constant displacement and pressure.
_Select the cylinder “stop”, select the pressure control from the “potentiometer” to “instrument”, until the pressure gauge is consistent, can be “heated”;
Setting up the heating curve and heating up. After the temperature reaches 200 degrees, the cylinder can be selected to “rise” and pressurize.
_After heating, when the furnace temperature drops below 1000 degrees Celsius, the cylinder stops and the instrument switches to the potentiometer.
Note: The pressure gauge shows 16MPa, which is equivalent to 20t computer display. The maximum pressure of graphite mold is 30MPa.
According to the specific area of the die, calculate the required pressure, for example:
Diameter 30 mold, maximum force 2.1 t, such as pressure 1.7 t, pressure gauge set to 1.4 MPa can be, at this time the mold sample pressure is 23 MPa;
Diameter 50 mold, maximum force 6.0 t, such as pressure 3.0 t, pressure gauge set to 2.4 MPa can be, at this time the mold sample pressure is 15 MPa;
The operation procedure of vacuum hot pressing furnace is as follows:
1) no matter whether the furnace is heated or not, it can be inflated.
2) The first time to wash the furnace three times, the first time to wash the furnace to close the “butterfly valve”, close the “main baffle valve”, close the “diffusion pump”, open the “inflation”;
3) when inflating to a pressure of -0.06MPa, close the “inflation” and open the “upper butterfly valve” to the pressure -0.1MPa.
4) Open “inflatable” again, so 3 times, 4 times “inflatable” to + 0.01 MPa can be closed, “inflatable” can be closed, argon (nitrogen) bottle can be closed;
5) 1 hours later, close the “lower butterfly valve” and turn off the “mechanical pump”.
6) Cooling below 1000 degrees Celsius, open “mechanical pump”, open “upper butterfly valve”, open “lower butterfly valve”, vacuum to less than 20Pa.