For the plastics industry, electricity consumption is a major part of its production costs. Injection molding machines are one of the main energy-consuming equipments for plastics production plants. The energy consumption of injection molding machines has become an effective way to reduce costs and improve product competitiveness in the injection molding industry. .
I. Overview China's power supply shortage has continued for several years. It has become even more severe. The demand for electricity has been driven by the rapid growth of GDP, and continues to grow at a high rate. It is also stated that “Industrial electricity continues to grow rapidly, and high-power consumption industries continue to use it. Electric growth is high." The increase in power supply capacity is limited, and there is a persistent shortage of supply, resulting in a tension between power supply and demand. The scope of power shortages and continued power shortages have further expanded.
For the plastics industry, electricity consumption is a major part of its production costs. Injection molding machines are one of the main energy-consuming equipments for plastics production plants. The energy consumption of injection molding machines has become an effective way to reduce costs and improve product competitiveness in the injection molding industry. .
At present, the vast majority of injection molding machines are hydraulic injection molding machines. The power in the hydraulic transmission system is provided by the motor-driven oil pump. In the course of injection molding cycle, injection molding machine needs different flow rate and pressure under different working procedures. It must depend on the flow valve and pressure valve to adjust the flow and pressure required for different processes, and the load varies greatly, because the quantitative pump cannot be adjusted. Output power, so the excess energy can only be consumed in the baffle, oil leakage, temperature rise of the oil, aggravated the wear of various valves, resulting in excessive oil temperature, excessive motor noise, and shortened mechanical life. phenomenon. And usually the design of the motor capacity is much higher than the actual need, there is a "big horse car" phenomenon, resulting in the amount of energy wasted. Therefore, the energy-saving transformation of injection molding machines is of great significance for reducing energy costs and improving competitiveness.
Second, the principle of work Plastic injection molding is the use of three states (solid - liquid - solid), by means of injection molding machines and mold out the required plastic products. Although all injection molding machines are not the same, the workflow of injection molding machines is basically the same. As shown in Figure 1, it can be roughly divided into seven processes: mold clamping, plastic injection, pressure keeping, melt molding, cooling, mold opening, thimble (thumb in, thimble out, and shot out). Each action has the delicate combination of time, pressure, speed, position and other parameters, that is to say the displacement in a certain position has the corresponding pressure and speed, and the pressure and the pressure in different positions and times Speed ​​is variable. At the same time, after each action is completed, a termination signal is sent to the program controller. After the program controller receives the signal, it sends an instruction to execute the next action. Each process requires different working pressures and flows. Except that high pressure mode-locking, rubber injection, and plasticizing operations require large pressures, other processes work under very small pressures, and the pressure and flow rate depend on the pressure proportional valve and The flow proportional valve is adjusted to control the pressure and flow rate by adjusting the opening degree of the pressure proportional valve and the flow proportional valve.
Injection molding machine energy saving principle:
Except for the electric injection molding machine, the others belong to the hydraulic drive injection molding machine. The power in the hydraulic transmission system is provided by the motor driven oil pump. In the course of the injection molding cycle, the flow rate and pressure required for the injection molding machine in different processes are different. The flow and pressure required by different processes must be adjusted by the flow valve and the pressure valve. Because the quantitative pump cannot regulate the output power, excess energy is required. Only in the baffle, oil leakage, this part of the leaked energy is where we want to save energy. Energy-saving devices provide the required energy according to the injection molding process requirements, there is no excess energy leakage is the most basic basis for all energy-saving injection molding reform .
Transformation principle:
According to the working principle and characteristics of the injection molding machine, the 6800 series asynchronous servo proportional flow signal for injection is used as the main input signal of the driver. When there is no sense servo operation, the main flow signal controls the speed. When the system pressure is greater than or equal to the set pressure, there is no Sense servo enters PID operation). In addition, the proportional pressure is used as the pressure reference signal of the system servo system. The pressure transmitter signal is feedbacked by the hydraulic system to the non-inductive servo to make the motor to stabilize the system pressure in the entire changing load range. Near the pressure, let the energy consumption reach the minimum range required, and ensure the smooth and accurate operation of the motor, that is, to ensure product quality and save energy, truly economical and practical.
Third, the system configuration
The 6810S injection-only asynchronous servo uses a pressure closed loop to drive the motor of the injection molding machine and controls the entire hydraulic system of the injection molding machine to complete the product processing.
Control circuit wiring:
Main circuit wiring
four. The advantages of the retrofitted equipment
Significant energy savings: up to 30%-65%
Optimize electrical facilities: reduce hydraulic motor load,
Extend the life of the whole machine: Saver control speed is stable, soft start (open grid impact), reduce the mold-locking vibration, avoid equipment impact, reduce the oil temperature, extend the seal mission cycle, and thus extend the life of the whole machine.
Convenient operation: In the production, it is not necessary to adjust the energy saver, and the whole process is automatically followed and controlled, and there are multiple protection functions, which are simple, safe and convenient.
Reduce noise: The noise of the equipment after the transformation is reduced by about 10DB, the equipment movement is more stable, and the operating environment is improved.
Flexible conversion: Non-inductive servo switch cabinet facilitates switching from power frequency to servo or servo to power frequency at any time
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