Numerical control machine tools, or CNC machine tools for short, are mechatronic products that have been integrated with mechanical, electrical, hydraulic, pneumatic, microelectronic and information technologies for the past thirty years. In modern machine tool production, they generally use multiple motor drives, with the spindle and each feed system driven by their own motor.
I. Overview
Numerical Control (NC) machine tools are mechatronic products that integrate mechanical, electrical, hydraulic, pneumatic, microelectronic, and information technologies. Over the past thirty years, they have been widely adopted. In modern machine tool production, multiple motors are typically used, with the spindle and each feed system driven by its own motor. Because machine tools handle a wide range of processes, different workpieces, different operations, and different cutting tools require different speeds for their actuators. Therefore, the main motion of the machine tool should be infinitely variable, and the spindle speed control system generally uses an AC spindle system.
With the development of variable frequency speed control technology, AC drive of CNC machine tool spindles can also meet the needs well. The main drive motor drives the spindle to rotate via belt drive, or via belt drive and reduction gears in the spindle box (to obtain greater torque). Because the spindle motor has a wide speed range and can be steplessly adjusted, the structure of the spindle box is greatly simplified.
II. Working Principle
1. The structure of a CNC numerical control system is shown in the following diagram:
2. Configuration:
Inverter: ALPHA6000-37R5GB
Braking resistor: 80Ω/750W 7.5KW speed-regulating motor
III. System Configuration
1. Requirements for the motor
Typically, a variable frequency motor or a regular motor with a fan is required to meet the motor's heat dissipation requirements at low frequencies, and a wide speed range is also required.
2. Technical requirements for frequency converters
a requires high low-frequency torque
At low frequencies (1~10Hz), it can deliver 150% of the rated torque.
b. Fast torque dynamic response and high speed stability.
It can achieve excellent dynamic response, responding quickly to changes in output torque based on load changes, thereby stabilizing the shaft speed.
c. Deceleration and stopping speed is fast.
The acceleration and deceleration times of CNC machine tools are usually quite short. The acceleration time is guaranteed by the performance of the frequency converter, while the deceleration time relies on an external braking resistor or braking unit.
d High reliability
The frequency converter has a low failure rate and operates stably and reliably.
electromagnetic compatibility issues
CNC machine tools are used in industrial environments, requiring not only strong anti-interference capabilities from the frequency converter itself, but also preventing interference with peripheral control equipment. As the working principle of a frequency converter shows, its output contains certain harmonic components. Improper handling during use can interfere with other equipment, with the CNC controller being the most vulnerable. Once the CNC controller is interfered with, the system will malfunction. In particular, the frequency and operating commands of the frequency converter may also be affected, with severe interference causing frequency instability and malfunctions. The solution is to ensure that frequency converters undergo rigorous EMC testing at the factory, using only those products that have passed EMC testing.
3. Inverter Wiring Diagram
IV. Parameter Adjustment
P0.01 = Terminal AI1 is an analog input.
P0.04=1 External terminal control
P0.07 = 150 (maximum output frequency)
P3.03=14 (External fault shutdown)
P3.17 = 2 (speed reaches)
P3.14=19 (Fault Output)
P2.06 = 6 (carrier frequency)
P9.00 = 100 (Slip frequency compensation gain)
P3.01=1 (X1 rotates forward)
P3.02 = 2 (X2 inverted)
P3.04=6 (X4 reset)
V. System Advantages
The ALPHA 6000 series frequency converters offer high output torque at low speeds, high speed accuracy, reasonable pricing, comprehensive functions, and stable and reliable quality, making them an ideal choice for machine tool equipment. The ALPHA 6000 series frequency converters have the following characteristics:
1. Dedicated CPU for motor control, space vector PWM control, ultra-quiet and stable operation.
2. It exhibits excellent low-frequency torque characteristics and stable operation at low-speed rated torque output.
3. Passed EMC testing and has strong anti-interference ability.
4. Advanced automatic torque compensation function design, with strong load adaptability.
It features real-time monitoring and control of 5 pairs of output currents, providing excellent dynamic response capabilities.
It features 6 comprehensive functions, including up to 40 protection and alarm functions.
