The servo system plays a crucial role in CNC machines by translating numerical control data into precise mechanical movement. These systems combine the strengths of traditional automatic, precision, and general-purpose machine tools, offering high efficiency, accuracy, and flexibility. The advancement of CNC technology largely depends on improvements in feed and spindle drive performance, as well as enhanced functionality. As a result, feed servo systems require advanced position control, speed control, servo motors, and efficient mechanical transmission to meet demanding operational requirements.
Since different CNC machines perform various tasks, their requirements for the feed servo system may vary. However, there are common expectations that most systems must fulfill. One of the key features is reversibility. This means the system should allow smooth forward and reverse movement at any time during the machining process. The table can be in any position, and direction changes must occur without backlash or loss of motion. From an energy perspective, reversible energy conversion is essential—during normal operation, the motor draws power from the grid and converts it into mechanical energy. During braking, the motor's kinetic energy is returned to the grid, enabling quick and efficient stopping.
Another important characteristic is a wide speed range. To accommodate different machining conditions—such as material type, size, tooling, and cooling methods—the feed speed must be continuously adjustable over a broad range. This requires the servo motor to have excellent speed regulation capabilities. After accounting for mechanical transmission, the motor’s speed range translates into the feed rate range. Currently, the most advanced systems can adjust the feed rate from 0 to 240 µm/min with a pulse equivalent of 1 µm. For standard CNC machines, a feed speed range of 0 to 24 m/min is typically sufficient. At zero speed, when the table is stationary, the motor must maintain electromagnetic torque to ensure accurate positioning. This leads to a two-part system: a speed control unit and a position control loop.
While some systems may aim for extremely wide speed ranges, it's more practical to focus on stability and reliability. A typical position control system might have a feed speed range of 1:20,000. With an open-loop position gain of 20–1, a speed control unit with a range of 1:1,000 can meet most needs, keeping the system simple and robust. However, cutting-edge experimental systems today can achieve a speed range of up to 1:100,000, showcasing the latest advancements in the field.
In addition to speed, the servo system must also demonstrate strong static and dynamic load characteristics. This means the system should maintain a constant feed rate regardless of load changes or varying cutting conditions. Systems with good rigidity will experience minimal speed fluctuations due to load torque variations. Ideally, the static speed drop should be less than 5%, and the dynamic speed drop should not exceed 10%. These performance standards ensure consistent and reliable operation under diverse machining scenarios.
Curved Lcd Display,Curved Display,Ultra Wide-Color Curved Lcd Monitor,Curved Screen
Shenzhen Risingstar Outdoor High Light LCD Co., Ltd , https://www.risingstarlcd.com