Casting technology of vacuum pumping system
The vacuum pumping system is composed of vacuum pump, pressure stabilizing tank, dust removal tank and valve connecting pipe. The selection of vacuum degree and air volume of vacuum pump is the key to the success or failure of V-method modeling. Generally, high vacuum degree is about - 66500pa (- 500mmhg) in production.
The pressure stabilizing tank is a sealed container, its main function is to stabilize the pressure of vacuum system, buffer the influence of pressure on molding, and also play the role of filtering dust.
It is easy to damage the sand box filter screen due to long-term reuse of sand box and molten iron pouring. Sand is sucked into the vacuum pump to cause damage. Fortunately, the dust collector is added into the vacuum pump, and the dust removal tank is connected to the vacuum pump to ensure the service life of the vacuum pump.
1. Place the sand box with filter air suction pipe on the template covered with plastic film;
2. Remove the vacuum in the template, and then carry out the draft. The mold should be vacuumized until the casting solidifies. According to the above legal system, the lower type;
3. When the metal solidifies, stop pumping the mold. When the pressure in the mold is close to atmospheric pressure, the mold will collapse.
4. Manufacturing the plate with air extraction box and hole;
5. Core setting, box closing and pouring;
6. The sand box is filled with dry quartz sand with particle size of 100-200 mesh without binder and additives. The sand is compacted by micro vibration and scraped flat. The sealing film is put on and the air in the molding sand is removed by opening the valve, so that there is a pressure difference between the inside and outside of the mold (about 300 ~ 400mmhg). Because of the pressure difference, the mold is formed and has high hardness. The reading of the wet mold hardness meter can reach about 95;
7. The plastic film in plastic state is covered on the molding plate for heating, and the temperature is generally between 80 ℃ and 120 ℃. At the same time, the vacuum pump is used to pump air to make the film close to the molding plate;