Technical Analysis of Electro-hydraulic Servo System for Metal Forming Machine

The application of electro-hydraulic servo technology originated in the 1980s and was first introduced by European industrial powers and became popular worldwide in the 1990s.

(1) Basic concepts

The servo system is a general term for the AC servo system and the electro-hydraulic servo system. Its function is to achieve precise control of the movement of the mechanical equipment by receiving the instructions of the numerical control device. The metal forming machine electro-hydraulic servo system is an important function of the automatic control of the metal forming machine. The function is to control the servo valve (or proportional valve) and the hydraulic pump after the instruction of the numerical control device is processed by the amplifier to convert the electric energy into hydraulic energy. The cylinder is transferred to the equipment actuator to be converted into mechanical energy, and the mechanical motion trajectory and state are fed back to the numerical control system through the detecting component to realize closed-loop control to ensure safe, efficient and high-precision operation of the metal forming machine. In addition to being applied to the machine tool industry, the AC servo system is mainly used in textile machinery, injection molding machinery, packaging machinery, printing machinery and other subdivided mechanical equipment industries. The function is to drive the moving parts of mechanical equipment by executing the control instructions of the numerical control device. Closed-loop control ultimately achieves closed-loop, precise control of the speed, load and position of mechanical equipment movements.

(2) Development history and status

The application of electro-hydraulic servo technology originated in the 1980s and was first introduced by European industrial powers and became popular worldwide in the 1990s. After 2000, the electro-hydraulic servo technology has been very mature. With the development of miniaturization, high-pressure, automation and intelligentization of hydraulic systems, the functional integration of electro-hydraulic servo systems is getting higher and higher, and the volume and weight of devices are becoming more and more important. Small, the scope of application is wider and wider. The current leading-edge electro-hydraulic servo technology includes: electro-hydraulic servo control technology that complies with European safety standards, adds redundant safety design and strict safety protection measures, and more energy-saving and electro-hydraulic servo-mixed drive valve control technology and electro-hydraulic Servo hybrid drive pump control technology. In industrial powers such as Germany and Japan, metal forming machines that are driven by servo motors and hydraulic systems have become more common.

In the mid-1990s, China began to introduce electro-hydraulic servo control technology, which is applied to CNC bending machines and shearing machines, CNC turret punching machines and large high-precision hydraulic presses. In recent years, it has been popularized in rapid forging and ceramic pressing. Machines, injection molding machines and other industries. The level of electro-hydraulic servo system used in domestic metal forming machine tools is comparable to that of foreign countries, but there are still a few technologies that are not available to domestic manufacturers, such as four-quadrant piston pumps, servo hydraulic pad technology, and high-speed stamping systems. In recent years, the more energy-saving and environmentally friendly hybrid drive servo system has shown great market potential in China. The SVP hybrid drive pump system gradually occupied most of the market share of the injection molding machine hydraulic system. It is in the ascendant in the die casting machine market, starting in the bending machine market and the hydraulic press market; the DSVP hybrid drive servo pump control system simplifies the original The proportional servo system replaces the servo valve and the proportional valve, which greatly reduces the energy consumption under the condition that the control accuracy is significantly improved.

At present, from a global perspective, except for a few metal forming machine tool companies that have the ability to independently develop and produce CNC systems, most metal forming machine tool companies rely on professional manufacturers to provide CNC system products. The numerical control system of the metal forming machine usually includes components such as a numerical control device, an AC servo system, a detecting device, and an electrical control system. Affected by factors such as production cost and gross profit margin, internationally renowned manufacturers mainly provide component products with high technical content, such as numerical control devices and testing devices.

The international manufacturers engaged in the research and development and production of metal forming machine CNC systems mainly include Japan Fanuc, Germany Siemens, Italy ESA, Switzerland Cybelec, etc.; domestic manufacturers mainly include the company, Shenzhen Huadel, Nanjing Zerong, Yangzhou Daxie and so on. Among them, the company's CNC system is widely used in various CNC metal forming machine tools, and has a large market share in the field of CNC machine tools for domestic shearing machine tools; Japan Fanuc, Germany Siemens products are mainly used in CNC turret punch presses, CNC laser cutting machines; Switzerland Cybelec, Italy ESA, Shenzhen Huadel products are mainly used in the field of CNC shearing machine tools; Nanjing Zerong and Yangzhou Daxie products are mainly used in the field of CNC presses.

The application of domestic CNC systems has long been based on international brand products. According to the “Twelfth Five-Year Development Plan for Machine Tool Industry” of the Equipment Industry Department of the Ministry of Industry and Information Technology, the domestic market share of domestically-made mid-range CNC systems is only 35%, while over 95% of high-end CNC systems rely on imports; the domestic market share of domestic functional components is about 30%. %, among which the market share of high-end functional components is lower, Taiwan's brand functional components account for about 50% of the domestic market, and the remaining 20% ​​are brand products of the European Union and Japan; in 2010, China's imported CNC system amounted to 1.81 billion US dollars, machine tool accessories Products (including functional components and fixtures) reached $1.62 billion.

Domestic enterprises still have a certain gap with international first-class manufacturers in terms of technology, brand and financial strength. The opportunities for greater competition are also huge. Some domestic enterprises have differentiated competitive advantages in terms of localized service advantages, response speed and cost performance. As the scale continues to grow and develop, the technology continues to mature, and the soft power of brands and services continues to improve. Domestic excellent enterprises will gain a broader Market survival and development space.