When debugging the proportional valve, I feel that the speed and pressure are uncontrollable. How to debug proportional valve?

Under normal circumstances, the flow and pressure of injection molding machine have been strictly adjusted, and generally no adjustment is needed. Under special circumstances, it is necessary to readjust the pressure and flow limit control potentiometer on the computer CPU. Inspection method of numerical control pressure linear proportional control;

1. Location of four "flow and pressure limit control" potentiometers on the CPU unit of the computer.

2. Adjust the four-stage glue injection speed to 50 and the pillow pressure to 00 with preset parameters.

3. Start the oil pump motor. When the temperature of the sol barrel reaches the sol temperature, press the manual glue injection key to make the screw go to the bottom. Check the oil pressure gauge to indicate a pressure value less than 20kg. It can be adjusted by a potentiometer controlled by the minimum pressure limit, and the pressure can be reduced by rotating counterclockwise.

4. The preset parameters can be used to gradually increase the pillow pressure, and the indication of the oil pressure gauge should be increased in proportion. When the numerical control value of pressure reaches 50 and 90, the error of oil pressure gauge should be less than 2.5 kg, which exceeds the minimum potentiometer adjustment.

5. Stop inputting the injection signal, repeat the above steps 2 and 4, and use the numerical control value of the injection pressure as the check point. Commonly used 50 and 99, when one of the detection points 99 reaches the required pressure indication, the pressure indication error of the other detection point 50 does not exceed 2.5kgf/cm2. However, when the numerical control value of the injection pressure is 00, the pressure index of the oil pressure gauge should not be higher than 20kgf/cm2, but generally between 5~ 15kgf/cm2.

6. In order to avoid adjusting the oil pressure indicator for a long time within the check point of pillow pressure 99, resulting in overheating of the oil temperature or motor overload, the thermal relay should act and adjust quickly and correctly. 2 minutes when the thermal relay trips, wait for 2 minutes. After the metal sheet of the thermal engine electrical appliance is reset, reduce the numerical control value of the glue injection pressure, and then press the reset button of the thermal engine electrical appliance to continue the adjustment.

7. It is normal that the pressure indicator of the oil pressure gauge may be out of linear proportion when adjusting the parameters of the pillow pressure between 05~ 10 and 90~99. If the error is not higher than 6kgf/cm2, no adjustment is required. .

8. Different types of injection molding machines have different maximum system pressures. When the highest system pressure is 145kgf/cm2, the indication of the oil pressure gauge should be 72.5kgf/cm2 when the numerical control pressure reaches 50. When the error does not exceed 2.5kgf/cm2, no adjustment is required.