Sep 04, 2023
Classification and characteristics of machine tool servo motion control systems
Machine tool servo motion control systems can be divided into open loop servo systems, semi-closed loop servo systems, and closed-loop servo systems:
1. Open loop servo system
The open-loop servo system, in general, only has input and output without feedback, and its driving components are mainly power stepper motors or hydraulic pulse motors. The essence of the working principle of these two driving components is the transformation from digital pulses to angular displacement. It does not use position detection components to achieve positioning but relies on the driving device itself, and the angle rotated is proportional to the number of command pulses; The motion speed is determined by the frequency of the feed pulse.
The open loop servo system has a simple structure and is easy to control, but has poor accuracy, unstable low speed, and low torque at high speed. In the past, it was generally used on light-load CNC machine tools with little change in load or economical CNC machine tools. However, due to the development of technology and market demand, it is no longer suitable for large, high-speed, high torque, and high-precision servo systems.
2. Semi closed-loop servo system
The position detection component is not directly installed on the final moving component of the feed coordinate but undergoes position conversion through mechanical transmission components in the middle, which is called indirect measurement. That is to say, a part of the coordinate motion transmission chain is outside the position closed-loop, and the transmission error outside the loop is not compensated by the system, so the accuracy of this servo system is lower than that of the closed-loop system.
The control structures of semi-closed loop and closed loop systems are consistent, with the only difference being that the closed loop system includes a large number of mechanical transmission components, and transmission errors can be compensated. In theory, the accuracy can be very high. However, due to the influence of mechanical deformation, temperature changes, vibration, and other factors, the system stability is difficult to adjust. In addition, after the machine tool has been running for a period of time, due to the wear and deformation of mechanical transmission components, as well as changes in other factors, it is easy to change the stability and accuracy of the system. Therefore, there are currently many uses of semi-closed loop systems. Only use a fully closed loop servo system on high-precision CNC machine tools with high tightness of transmission components, stable performance, and little variation in temperature difference during use.
3. Closed loop servo system
A closed-loop servo system is an error controlled servo system. The error of the CNC machine tool feed system is the difference between the position command output by the CNC and the actual position of the machine tool workbench (or tool holder). The motion execution components of the closed-loop system cannot reflect the position of the motion, so a position detection device is required. The device measures the actual displacement or position and feeds the measured value back to the CNC device. It is compared with the command to obtain the error, which in turn constitutes a closed-loop position control.
Due to the feedback control of the closed-loop servo system, the accuracy of the feedback measurement device is very high. Therefore, the errors of the system transmission chain, the errors of various components in the loop, and the errors caused by movement can be compensated, greatly improving the following and positioning accuracy.
Common well-known European servo motion control system providers
B&R, Austria
B&R is a global leader in the field of automation technology, headquartered in Eggelsberg, Austria. It was co founded by Mr. Erwin Bernecker and Mr. Josef Rainer in 1979. The belief in innovation has accompanied Baccarat's continuous growth and led to the trend of technological development. Today, Baccarat has established branches in 60 countries worldwide and has 155 offices. The Baccarat servo driver and inverter module are equipped with hard wiring or integrated safety technology to facilitate intelligent response to hazardous situations. In addition to minimizing downtime as much as possible, this also significantly improves machine output. Baikalai servo technology is very suitable for centralized and distributed architectures. Whether located in the control cabinet or directly installed on the machine, this product portfolio includes drive solutions for any situation.
A wide range of motors, reducers, and motor/reducer combinations are available for selection. The components developed by Baikalai meet the specific needs of various industries, whether standard or specialized machinery - from metal processing to food and beverage. To achieve extremely fast delivery, you can choose from a list of standard motors.
Beckhoff, Germany
Since its establishment in 1980, Beifu has always adhered to PC based control technology and developed a large number of innovative products and solutions, which is why Beifu has been able to continue its development. The concept proposed by Beckhoff earlier has become a standard for many automation technologies and has been successfully introduced into the market.
Based on the concept of PC control technology and the launch of Lightbus systems, bus terminal modules, and TwinCAT automation software, Beckhoff has a milestone historical significance in the field of automation technology. In the traditional control industry, these products have been widely accepted as high-performance solutions. EtherCAT - Real Time Ethernet Solution - is a forward-looking high-end technology and a new generation product of cutting-edge control concepts.
Siemens, Germany:
Motion control system SIMOTION
SIMOTION holds a pivotal position in the field of motion control. It is a scalable, modular, and high-performance motion control system that can adapt to centralized or distributed machine designs and provide various solutions based on PC, controller, or driver. The system has excellent performance, high flexibility, convenient engineering configuration, and fast debugging, which can meet various unique needs of users.
Siemens Other Drive Technologies: The drive technology series products provided by Siemens are unparalleled globally, including Siemens frequency converters SINAMICS, CNC systems SINUMERIK, reducers, reduction motors, couplings, hybrid drives, and Siemens motor SIMOTICS, covering all torque ranges, performance levels, and voltage levels.
Bosch Rexroth, PhD, Germany
Rexroth's IndraMotion servo system is a system solution for rapid machining centers in harsh industrial environments. Its superior performance and extensive technical functions make it a control system that can meet specific requirements. Up to 64 axes can be controlled with 12 independent CNC channels, of which 32 are axes with spindle function. The system also includes industrial Ethernet with Sercos for the future, as well as PROFIBUS and Fast Ethernet. In addition, there are a wide range of functions available for complex interpolation, axis coupling, special motion, fast input/output coupling, and more.
Heidelberg is a world-renowned expert in measurement and servo motion control systems. Heidelberg's precision measurement technology and products are widely used in almost all mid to high end CNC servo system manufacturers worldwide, making it an industry benchmark for servo systems and measurement feedback products
Spain Fage is a renowned European manufacturer of CNC servo systems and measurement products, and enjoys a high reputation in China. With its excellent market performance and cost-effectiveness, it has won the trust and support of a large number of customers.
France NUM
As the second largest manufacturer of CNC systems in Europe, NUM has been committed to the development and research of machine tool automation and motion control for many years. For 30 years, NUM has been renowned globally for its high-precision, high-speed machining technology, close cooperation with customers, and providing professional technical support and services.
With over 30 years of professional experience in the field of industrial automation CNC, we specialize in providing CNC solutions and comprehensive CNC products. We are an active European company headquartered in Switzerland, the second largest CNC system provider in Europe, and one of the three major professional CNC system providers worldwide.
NUM Company is widely involved in fields such as CNC systems, drives, motors, application software, microcomputer communication, and new IT networks, while providing global technical services and training.
The main products of NUM company include: Num power1000 series, Axium power series, Flexium series, Num drive, Num axis motor, and spindle motor.
OstBridge is based on the market in China and Europe to provide our clients with original HEIDENHAIN, PRECIZIKA, SIEMENS, B & R, BOSCH REXROTH, EATON VICKERS, PARKER, Large stock, accept MOQ, fast delivery If you are looking for the fields of precise motion control, electronic control, automation, and hydraulic system, the OstBridge team must be your first choice to bring you the right solution.