1 Introduction
With the development of electronic information technology, the global machine tool industry has entered the era of mechatronics, with digital manufacturing technology at its core, and CNC machine tools are one of the representative products. CNC machine tools are the mother machines of manufacturing and an important foundation of the national economy. They provide equipment and means for various sectors of the national economy, and have an infinitely amplified economic and social impact.
The spindle is a crucial component of CNC machine tools, playing a vital role in improving machining efficiency, expanding the range of workable materials, and enhancing machining quality. Spindle drive systems employing frequency converters offer advantages such as stepless speed regulation, a wide speed range, simple structure, and cost savings, making them widely used in machine tools.
The HiPumont HD30 series frequency converters have achieved excellent results in CNC machine tool applications due to their superior performance and high reliability.
2. Technical requirements for CNC machine tool spindle drive
The spindle drive of a CNC machine tool is an important component of a CNC machine tool, and the drive system has the following technical requirements:
It can achieve rapid acceleration and deceleration: CNC machine tools usually require a short acceleration and deceleration time, generally around 1 to 2 seconds, so the dynamic performance requirements of the frequency converter are high.
It needs to have strong overload capacity at low speeds: the frequency converter needs to have reliable overload protection function.
Sufficient torque output at low speeds : According to the working characteristics of CNC machine tools, the spindle drive system is generally required to output 150% of the rated torque at 1~2Hz.
High speed stability : For high-speed rotating spindle motors, excessive speed fluctuations will affect the machining quality of the workpiece. Therefore, the speed stability of the drive system is required to be very high.
Convenient interface : Generally, the control and operation commands of CNC machine tools come from terminal inputs, and the frequency input commands come from analog signals. Therefore, the frequency converter is required to have matching terminal inputs and analog signal interfaces.
3. Introduction to HD30 Vector Control Frequency Inverter
The HD30 series vector control general-purpose frequency converter is a new generation of vector control frequency converter developed by Shenzhen Haipumont Technology Co., Ltd. It features strong low-speed torque capability, high control precision, and ultra-quiet operation. Built-in features include process PID control, programmable analog curves, 16-segment multi-speed operation, programmable input/output terminals, and multi-frequency command channel design. It organically combines general needs with the personalized requirements of industry users, providing a highly integrated solution. It also boasts strong adaptability to power grids and environments, high reliability, and simple and convenient operation.
4. Features of HD30 Vector Inverter
The HD30 series frequency converters offer numerous targeted advantages based on the technical requirements of CNC machine tool spindle drive systems:
1. It has reliable overload protection capability and can reliably output more than 150% of the rated output current for more than 2 minutes;
2. The starting torque can reach more than 180% at 0.5Hz, which meets the requirements of low speed and high torque for machine tool spindle drive;
3. At least two standard analog input interfaces (AI1 voltage 0~10V, AI2 voltage/current selectable -10V~+10V/0~20mA DC), which are compatible with most CNC system interfaces and have strong versatility;
4. Employing the latest algorithms, analog inputs exhibit high linearity and high accuracy;
5. The output terminal logic is programmable. It can output signals such as zero speed, running, speed reached, and fault indication, meeting the system's monitoring requirements for spindle speed status;
All models with power ratings of 6.55KW and below have built-in braking units, eliminating the need for external braking units.
7. The carrier frequency range is 1~16kHz, which effectively reduces the howling noise of the spindle system;
8. Standard configuration includes RS485 communication interface, MODBUS communication protocol, and dedicated PC debugging software;
9. Online identification of motor parameters ensures system stability and accuracy;
10. Adaptive control of grid voltage effectively avoids interference caused by voltage fluctuations.
5. Application of HD30 Vector Control Frequency Converter on Machine Tool Spindle
The machine tool system used in this application adopts the Fanuc CNC system. The debugging process and results are as follows.
5.1 Debugging Process
(1) Wiring according to Figure 1;
(2) Set the motor parameters according to the motor nameplate;
(3) Disconnect the motor load, use the jog function to determine the motor rotation direction, and change the wiring to the forward rotation direction;
(4) Perform motor parameter self-tuning;
(5) Set the maximum output frequency and upper limit frequency;
(6) Set the command to specify the channel and frequency for the channel;
(7) Set acceleration and deceleration time;
(8) Configure analog quantity function;
(9) Set terminal functions;
(10) Set the operating voltage of the braking unit;
(11) Cancel overvoltage stall and automatic current limiting functions.
5.2 Final Parameter Settings
Function code | illustrate | Settings and Explanations |
|---|---|---|
F00.06 | Maximum output frequency | 200.00Hz (Motor rated frequency 50.00) |
F00.08 | Upper limit frequency | 200.00Hz |
F00.10 | Frequency given channel | 3 (Analog quantity given) |
F00.11 | Command given channel | 1 (Terminal command given) |
F03.01 | Acceleration time | 1 second (acceleration time refers to the time from zero frequency to maximum frequency) |
F03.02 | deceleration time | 1 second (deceleration time refers to the time from maximum frequency to zero frequency) |
F05.04 | Maximum given value of line 1 | 100% (External 10V corresponds to maximum output frequency) |
F15.00 | DI1 terminal function selection | 2 (FWD function) |
F15.01 | DI2 terminal function selection | 3 (REV function) |
F15.02 | DI3 terminal function selection | 41 (Terminal Free Stop Normally Open Input) |
F15.03 | DI4 terminal function selection | 46 (External Reset RST Input) |
F16.01 | Analog Input AI1 Function Selection | 2 (Frequency Setting Channel) |
F16.07 | Analog input AI1 filtering time | 0.1s (Analog input AI1 filtering time) |
F19.18 | Overvoltage stall function allows | 0 (Prohibition of overpressure stall) |
F19.20 | Automatic rate limiting action selection | 0 (Automatic rate limiting function disabled) |
F19.24 | Braking unit operating voltage | 680V |
The inverter wiring diagram is shown below:
DI1, DI2, DI3, and DI4 are respectively configured as FWD, REV, terminal free stop input, and external fault reset command, while AI1 serves as the frequency command input channel. Programmable relays are often used as fault relays to output to the controller.
5.4 Debugging Results
Under no-load conditions (when the machine tool is not machining parts), the actual operating speed deviates from the set target speed by no more than 1 RPM. When the machine tool is machining parts (the actual torque is equivalent to 80% of the motor's rated torque), the cutting speed drops momentarily during the cutting process, but after passing through the vector control speed loop, the speed quickly recovers to near the given speed; the measured speed deviation also does not exceed 1 RPM.
5.5 Debugging Precautions
1. Since vector control has better low-frequency torque and speed stability than V/f control, it is best to use vector control when driving machine tool spindles.
2. Since the vector control process requires accurate acquisition of motor parameters, it is necessary to accurately input the motor nameplate values and perform motor parameter self-tuning.
3. Since the frequency command of the machine tool system is generally given by analog signal, and the requirements for the frequency command tracking characteristics are very high, it is recommended to minimize the analog input filtering time as much as possible while meeting the requirements of noise immunity, so as to meet the requirements of fast frequency command tracking.
6 Conclusion
The HD30 vector control frequency converter has been successfully applied in the field of CNC machine tool drive control. Its superior performance (high low-frequency torque, wide speed range, high steady-state accuracy, fast acceleration and deceleration, flexible and convenient operation, and comprehensive function protection) and high reliability have been fully verified, and it fully meets the requirements of CNC machine tool spindle control.
