Die-casting machine is a series of industrial casting machinery that presses metal into a mold under pressure to cool and shape, and obtain solid metal castings after the mold is opened. The pressure control is extremely important. In the original plan, a power frequency pump and an oil pressure valve were used to control the pressure. Now, a frequency conversion is used to drive the oil pump. While the pressure is accurately controlled, it also achieves energy-saving effects.
2. Process requirements:
The die casting process is generally divided into the following steps: The process of completing a casting is: moving 1 core insert-moving 2 core insert-closed type-low pressure closed type-system pressure lock type-closed type completed-static insert-slow pressure-one Fast-two fast (simultaneous pressurization)-(cooling time is up) static core pulling-open type-dynamic 2 extraction-dynamic 1 extraction-delay before ejection-ejection-delay after ejection-press back-top return- Restore the original position-delay unloading. This repeats the cycle for casting production. The entire workflow of the die casting machine is simplified into two stages: mold opening and mold closing. The pressure, speed, and position required for the two stages of mold opening and mold closing are completely different. The switching time between the two needs to be quite accurate, so as to meet the process requirements of the die casting machine.
3. System plan:
According to the different pressures, speeds, positions and switching time between the mold opening and mold clamping stages, considering the simplicity and cost reduction, we decided to adopt segmented control, that is, divided into two speeds. Specifically, in In the process of mold opening and mold closing, the two-speed mutual switching can be realized by installing a travel switch or proximity switch at the position where the die casting machine must pass. Clamping requires high pressure, the inverter runs at high speed, and mold opening requires low pressure and can run at low speed. In addition, considering the process requirements of the die casting machine, the time for switching from low frequency to high frequency should be appropriate, that is, the acceleration time should be as short as possible.
4. System advantages:
1. After the transformation, the frequency converter automatically adjusts the motor speed according to the pressure and flow required by the die-casting machine, which has obvious power-saving effects, improves the power factor of the grid, and reduces the reactive power loss.
2. Soft start reduces the impact on the power grid, prolongs the life of power supply equipment, and at the same time increases the capacity of the transformer and relieves the pressure of capacity increase.
3. As the motor speed is reduced, the wear of the oil pump is also reduced, the noise is reduced, the maintenance cost is reduced, and the service life is prolonged.
4. There are many intelligent protection functions for the motor: such as undervoltage, overvoltage, phase loss, overload, overcurrent, overheating, etc.
The application of frequency converter die-casting machine is an energy-saving and high-efficiency; it not only extends the life of the equipment, but also overcomes the change in the speed of the ordinary asynchronous motor fixed pump system due to changes in the grid voltage, frequency and other changes, which in turn causes changes in flow and reduces product yield Shortcomings. And it has been actually used and is worth promoting.