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List of the catalogue of this article:

• 1. What is the all-digital servo system of CNC machine tools?
• 2. What are the common faults and elimination methods of the machine tool feed servo system?
• 3, The relationship between the performance of servo system parameters and CNC machine tools
• 4, What types of CNC machine tools can be classified according to the control method of the servo system? What is the difference between them...

What is the all-digital servo system of CNC machine tools?

All-digital servo system With the development of microelectronic technology, computer technology and servo control technology, the servo system of CNC machine tools has begun to adopt a high-speed and high-precision all-digital servo system. Make servo control technology move from analog and hybrid to all-digital.

CNC means computer digital control, which is now used specifically to refer to: numerical control and numerical control machine tools.The servo system is a feeding system that controls the movement of the machine tool. It is a numerical control system that uses a numerical control system to control the rotation of the servo motor to control the movement of the machine tool. Most of the CNC machine tools are used in mechanical manufacturing.

CNC servo system is the electric transmission link between the numerical control system and the machine tool body. It is mainly composed of servo motor, drive control system and position detection feedback device, etc. The servo motor is the executive component of the system, and the drive control system is the power source of the servo motor.

What are the common faults and elimination methods of the machine tool feed servo system?

1. The following are common faults of the servo system. Overtake When the feed movement exceeds the soft limit set by the software or the hard limit set by the limit switch, an overshoot alarm will occur. Generally, the alarm content will be displayed on the CRT. According to the CNC system instructions, the fault can be eliminated and the alarm can be lifted.

2. The fault of the feed servo system can generally be eliminated by referring to the operating instructions. If you encounter a fault that cannot be ruled out by the reference operating instructions, you need to analyze and solve the specific problem.

3. The common reasons for such failures caused by mechanical oscillation (when adding/decelerating) are: 1 The failure of the pulse encoder.

4. First, the servo motor does not rotate. Common diagnostic methods are to check whether the CNC system has a pulse signal output and whether the enable signal is turned on. The motor position error checks whether the system setting error is too small, and the motor rotation is reduced to check whether the load is too large. Motor vibration check to find the speed ring problem.

5. Intuitive inspection method Intuitive inspection method is that maintenance personnel determine the scope of the fault based on the observation of various abnormal phenomena such as light, sound and smell when the fault occurs. The scope of the fault can be narrowed to a module or a circuit board, and then eliminate it.

6. Position ring fault diagnosis if the position servoThe position feedback and speed feedback of the system each adopt a feedback device, which can disconnect the control of the position loop and let the speed loop run separately, so as to judge whether the fault comes from the position ring or the speed ring.

The relationship between servo system parameters and CNC machine tool performance

1. The function of CNC machine tool is determined by the CNC system. The performance of the CNC machine tool is determined by the configuration of the machine tool itself, such as the servo drive unit, various detection feedback units and the accuracy of installation, etc., which determine the performance of the machine tool.

2. The servo system is equivalent to the nervous system in the human body, with high sensitivity and rapid response. Among CNC machine tools, the servo system with excellent and poor performance of a machine tool accounts for a considerable proportion.

3. The servo system is an automatic control system that controls the position of the moving parts of the machine tool. It accurately converts the position instructions generated by the interpolation operation of the CNC system into the displacement (including linear displacement and angular displacement) of the moving parts of the machine tool, which directly reflects the tracking motion command and positioning of the coordinate axis of the machine tool. Can.

4. At the same time, the relative stability of the system is required. When the system is disturbed, the oscillation is small and the recovery time is fast. ( 3) The speed regulation range is wide. In CNC machine tools, the speed of the feeding servo system is required to reach the range of 1-24000mm/min, that is, within the speed regulation range of 1:24000, the speed is required to be uniform, stable, no crawling, and small speed reduction.

5. Reversible operation and frequent and flexible start and stop. ( 6) The system is highly reliable, easy to maintain and use, and the cost is low.In summary, the requirements for the servo system include both static and dynamic characteristics; for high-precision CNC machine tools, the requirements for their dynamic performance are stricter.

6. Function: Accurately execute the position and speed command signals sent by the CNC device. After certain conversion and amplification by the servo drive circuit, the servo motor and mechanical transmission mechanism drive the machine tool workbench and other moving parts to realize the rapid movement of work feed and position control.

What types of CNC machine tools can be classified according to the control method of the servo system? What is the difference between them...

Semi-closed-loop control CNC machine tools are in the axis or number of servo motors.The transmission screw of the control machine tool is equipped with an angular displacement current detection device (such as photoelectric encoder, etc.), which indirectly detects the actual displacement of moving parts by detecting the angle of the screw, and then feedbacks to the numerical control device and corrects the error.

II) Classified according to the way of controlling movement, it is divided into three types: point control, linear control and contour control. The point control CNC machine tool only controls the coordinate position of the tool relative to the positioning point of the workpiece in the machining plane, and does not require the trajectory of positioning and movement.

__ There are three forms of CNC machine tools classified according to the control mode of the feed servo system: open-loop control system, closed-loop control system and semi-closed-loop control system.

Open-loop control CNC machine tools: This kind of machine tool does not have a position detection feedback device, and usually uses a stepper motor as the actuator.