For the die-casting product industry, power consumption is the main part of its production cost, and the die-casting machine is one of the main energy-consuming equipment of the product factory, known as the electric tiger. Therefore, reducing the energy consumption of die-casting machines has become an effective way for the die-casting industry to reduce costs and improve product competitiveness.
2. Industry introduction
At present, most of the die-casting machines are hydraulic drive die-casting machines, and the power in the hydraulic drive system is provided by an oil pump driven by a motor. During the change in the die-casting cycle, the die-casting machine requires different flow rates and pressures in different processes, and it must rely on flow valves and pressure valves to adjust the different flow rates and pressures required by different processes. And when the load change is relatively large, because the output power of the fixed pump cannot be adjusted, the excess energy can only be consumed in the baffle plate, oil circuit leakage, and the increase of oil temperature, which also aggravates the wear of various valves and causes the oil temperature. Excessive high, excessive motor noise, and shortened mechanical life. In addition, the capacity of the motor is usually much higher than the actual need when designing the motor. There is a phenomenon of "big horse-drawn trolley", which causes a large amount of waste of electric energy. Therefore, popularizing the application of frequency converters on die-casting machines is of great significance for reducing energy waste.
3. Process description
Die-casting machine mold clamping and demolding, mold opening system requires lower oil pressure and shorter time; while injection, pressure holding, and cooling systems require higher oil pressure and longer time. Generally, it is 40%~60% of a working cycle. The length of each stage is related to the workpiece; the length of the intermittent period is also related to the condition of the workpiece, and sometimes the intermittent period is not necessary. If the injection screw is driven by a liquid oil motor, the system oil pressure during injection will be higher. The weight of the workpiece processed by the die-casting machine ranges from tens of grams to tens of thousands of grams. Therefore, the die-casting machine is divided into small and medium-sized and large-scale. The processing time of one cycle for processing small workpieces of tens of grams and processing large workpieces of thousands of grams is also different. The pressure and time required in the process flow also need to be changed.
4. Power consumption of die casting machine
The power consumption of die casting machine is mainly manifested in the following parts:
1) Electricity consumption of the oil pump of the hydraulic system
2) Electricity consumption of the heater
3) Electricity consumption of circulating cooling water pump
In the die-casting workshop, generally multiple die-casting machines share a cooling water pump, and the power consumption of the hydraulic oil pump motor accounts for more than 80% of the power consumption of the entire die-casting machine, so reducing its power consumption is the key to energy-saving die-casting machines.
5. Principles of energy-saving transformation
According to the working principle of the die-casting machine, the high-pressure cut-off is a waste of energy consumption of the oil pump motor. The KE300A inverter produced by our company utilizes this feature. According to the requirements of the production process of the die-casting machine, the inverter is used to adjust the speed of the oil pump motor, and the pressure or flow parameters required by the die-casting machine during operation and the action feedback signal of the die-casting machine are synchronously controlled. The proportional flow valve and proportional pressure valve of the die-casting machine realize automatic adjustment of pressure and flow. The effect is equivalent to transforming a quantitative pump into a variable pump to minimize the return flow through the overflow valve. The output of the oil pump is required for the operation of the whole machine. The pressure and flow are matched, and there is no high-pressure overflow energy loss. The frequency converter tracks the pressure and flow changes of each working stage through the feedback signal, and automatically adjusts the speed of the oil pump motor. In this way, the power consumption of the oil pump motor will follow the change of the output load, which can save electricity to the greatest extent, which is economical and practical. Many factories have achieved significant economic benefits through transformation.
6. Transformation effect
High power saving rate:
After the transformation, the quantitative pump becomes an energy-saving variable pump, and the hydraulic system of the die-casting machine basically matches the power required for the operation of the whole machine. There is no high-pressure throttling and overflow energy loss, and the power saving rate can reach 20% to 60%.
The power factor before the transformation is generally 0.5 to 0.8, and can reach more than 0.96 after the transformation. Therefore, the power factor of the power grid can be significantly improved, the reactive current can be reduced, and the line loss can be reduced. For power supply equipment, it plays a role in increasing the capacity.
Keep the original control mode and oil circuit of the die-casting machine as a backup, and give an alarm in time when a failure occurs. It has multiple protections such as overvoltage, overcurrent, overload, overheating, undervoltage and short-circuit to ground, and can effectively protect the oil pump motor. Adopting mains/energy-saving operation control mode, once the failure does not affect production, prolong the life of the machine
Improve the environment
The soft start reduces the vibration of the start-up and mold clamping, prolongs the service life of equipment and molds, and reduces noise. Improve the working environment, the system heat is obviously reduced, the oil temperature is stable, and the cooling water consumption can be saved by more than 30%. Extend the service life of sealing components, reduce downtime maintenance opportunities, and save a lot of maintenance costs.
Saving electricity is to create benefits. After the entire power system is transformed into a one-time investment, it will benefit in the long term. This power-saving transformation not only reduces electricity costs, but also provides excellent safety protection for the die-casting machine. It will help protect the service life of motors, electronic components, switching components and other equipment. It can also play a role in soft-starting of the motor and reduce Equipment investment costs, maintenance costs, improve the production efficiency of enterprises, and create enterprise benefits. Enhance the market competitiveness of enterprise products.