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Rubber Plastic

01. Overview

In recent years, the plastics industry has developed more and more rapidly, and the injection molding industry is also ushering in a rapid development opportunity. But at the same time, the competition in the industry is becoming more and more fierce. In addition to the product quality and brand, the manufacturers also pay more and more attention to the control of production costs. From the injection molding machine process, it is known that the cost of electric energy consumption accounts for a large proportion of the cost of injection molding products. Therefore, whether the electric energy loss can be effectively reduced has attracted the attention of various injection molding machine manufacturers and users. With the popularization of frequency conversion speed regulation technology, frequency conversion speed regulation has been widely used in the field of transmission control and energy saving.

02. Process introduction

Ordinary injection molding machine usually adopts hydraulic transmission, and its structure is shown in Figure 1, which mainly includes injection device, mold opening and closing device, hydraulic transmission device and electrical control device.


The molding process of the injection molding machine is a process that operates according to a predetermined cycle, that is, the processing steps such as mold clamping - mold clamping - nozzle advancement - glue injection - pressure holding - cooling - pre-molding - injection table retreat - mold opening - product removal to reach a certain level. product forming.
The loss in the ordinary injection molding process mainly comes from the following points:
1. Overflow loss. With different products and processing procedures, the hydraulic pressure, flow rate and pressure required for each procedure are different. Therefore, for the oil pump motor, the load during the injection molding process of the injection molding machine is in a state of change. The flow rate of the pump is designed according to the required maximum flow rate. The hydraulic flow rate provided by the oil pump at a constant speed during operation. When the flow rate required by the injection molding machine is less than the maximum flow rate, the excess hydraulic pressure will flow back through the relief valve. Some of the energy is lost.

2. Throttle loss. When the hydraulic oil flows through the throttle port of the valve, there will be a certain pressure drop, which is the throttling loss. Since the throttling area of the directional valve is relatively large, most of the throttling loss occurs on the proportional valve. At the same time, due to the long-term full-speed circulation of the hydraulic pressure and the severe mechanical friction of the hydraulic parts, the oil temperature is too high, the noise is too large, and the mechanical life is shortened.

3. Design margin loss. Usually in the design, the commonality is generally considered, and the design is based on the maximum capacity. Therefore, the designed capacity of the user's oil pump motor is much higher than the actual need.  

03. Application of H500 series inverter in injection molding machine

1. Frequency conversion transformation of injection molding machine

The injection molding machine equipment is transformed with a frequency converter. As shown in the figure below, the injection molding machine synchronization signal not only controls the pressure and flow proportional valve accurately for the injection molding process, but also uses the proportional pressure synchronization signal to control the frequency converter, so that the frequency converter can dynamically follow the injection molding. Automatic speed regulation based on machine pressure signal, flexible control and strong anti-interference. Transform the traditional quantitative pump into a variable frequency variable pump. The backflow through the relief valve is minimized, the output of the oil pump matches the pressure and flow required for the operation of the whole machine, and there is no high pressure overflow energy loss. Significantly improve the phenomenon of high energy consumption, high oil temperature, high noise, and short service life of machinery and seals in the injection molding machine.


Injection molding machine frequency conversion circuit diagram

2. Effect of injection molding machine after transformation:

① Remarkable power saving effect

② Stable operation and quick system response

③ Low noise, weak vibration

④ Easy to operate

⑤ Extend service life


3. Inverter setting parameters

P0.02=1 (running command channel)

P0.17=20 (acceleration time)


4. On-site pictures

04. Conclusion

With the maturity of frequency conversion technology, frequency converters are increasingly widely used in the transformation of injection molding machines. Practice has proved that the use of frequency conversion control in injection molding machines has obvious energy-saving effects and is worthy of promotion and application. The H300 inverter solution provided by Huixunjun has the advantages of short acceleration and deceleration time, rapid system response, and stable system operation.