1. Overview Currently, the application of frequency converter and electro-hydraulic proportional composite control technology in injection molding machines is still in the exploratory stage. The use of frequency converters in injection molding machines offers advantages such as energy saving and low noise, attracting the interest of some injection molding machine and frequency converter manufacturers, who have conducted careful research to effectively integrate the injection molding machine controller with the frequency converter. Through joint control, the advantages of the frequency converter are fully utilized. The injection molding machine frequency converter control device, jointly developed by Ningbo Huaye Machinery Manufacturing Co., Ltd. and the Institute of Mechanical and Electronic Control Engineering of Zhejiang University, is a practical achievement based on the company's invention technology "Combined Speed ​​Regulation System and Method of Frequency Conversion and Electro-hydraulic Proportional Technology" (ZL01126526.4). It integrates frequency conversion technology and electro-hydraulic proportional control technology and is one of the key components of new energy-saving injection molding machines and rubber and plastic molding machines. It has passed expert evaluation, and its comprehensive performance indicators have reached the international advanced level. This device has been successfully applied to the hydraulic control systems of injection molding machines, rubber molding machines, etc. It uses a Chinese-language interface to set the operating parameters of the frequency converter and the process parameters of the injection molding machine, achieving optimal control of the system and saving 30% to 60% of electricity while meeting various control requirements. The registered trademark of this product is "Huaye Nengbao". While upgrading downstream industries, it meets the energy-saving requirements of different users for injection molding machines (rubber machines, extruders, and other molding machinery), improves the overall technological content of the machine, and conforms to the development direction of intelligent, environmentally friendly, and energy-saving industries. 2. Structure and Working Principle The hydraulic system of an injection molding machine (rubber molding machine) is generally an electro-hydraulic proportional control system. A fixed-displacement pump supplies oil, and a proportional pressure-flow composite valve controls the pressure and flow rate of the system. As an important piece of production equipment, injection molding machines typically operate continuously for 24 hours a day in many plastic product manufacturers, consuming a considerable amount of electricity. The load changes very significantly in a single work cycle, thus presenting significant energy-saving potential. [b][align=center]For more details, please click: Variable Frequency and Electro-hydraulic Proportional Technology Composite Speed ​​Regulation System and Its Application[/align][/b]