Introduction to CNC machine tool CNC machine tool is an automated machine tool equipped with a program control system. The control system is able to logically process and decode programs with control codes or other symbolic instructions so that the machine can move and the parts are machined. According to the process use, it can be divided into metal cutting CNC machine tools, including CNC lathes, CNC drilling machines, CNC milling machines, CNC grinding machines, CNC boring machines and machining centers. These machines are suitable for single-piece, small batch and multi-mix machining with good dimensional consistency, high productivity and automation, as well as high flexibility.
The drive components of the actuator of the CNC machine tool include the spindle drive unit, the feed unit, the spindle motor and the feed motor. The spindle and feed drive can be realized by means of an electrical or electro-hydraulic servo system under the control of a numerical control device. When several feeds are linked, positioning, straight lines, plane curves and spatial curves can be processed.
There are two common spindles on the market, one is a mechanical spindle, and the motor is connected to the spindle through a synchronous belt; The other is the electric spindle, where the motor is directly connected to the tool. The speed of the mechanical spindle motor is generally not high, within 8000r, the speed of the electric spindle motor can be more than 15000.
The following takes the MSD100A spindle servo as an example to introduce its application in CNC machining centers
First. General requirements for spindle control:
1. The spindle drive system needs to have fast response, high speed and strong overload capacity;
2. The spindle drive system needs to realize the orientation and feed functions;
3. It can meet the processing requirements of the system for automatic tool change, rigid tapping, spindle feed function, etc., which have high requirements for spindle position control performance.
Second. MSD100A spindle servo characteristics
1. The servo frequency of the MSD100A spindle is 1200Hz, which can easily drive the electric spindle and mechanical spindle motor.
2. Support a variety of encoders, support resolver and ordinary incremental encoders.
3. It can drive synchronous motor and asynchronous motor, and can easily cope with synchronous and asynchronous spindle systems.
4. The rare high-power servo drive in China can achieve 400KW
5. Compatible with all CNC systems, such as Xindai, Baoyuan, Siemens, Mitsubishi, Fanuc, Guangshu, Huazhong CNC and so on.
6. Fast response speed, high positioning accuracy, no overshoot phenomenon, 0Hz can output 200% of the starting torque, speed control accuracy ± 0.02%, speed fluctuation ± 0.1%; When the encoder is not mounted on a motor, it can also be controlled by PG vector; It has the function of over-speed and over-speed deviation detection.
7. It has the functions of zero-speed locking, spindle orientation and carrying, and rigid tapping: the spindle orientation has multiple positions, which can be switched, and can be used for multi-tool systems, such as tool magazine tool change. Rigid tapping can be controlled by analog quantities as well as by pulses. Spindle orientation, pulse position control, and pulse speed control can be switched between each other through terminals, and the position control accuracy is high, and the positioning accuracy can reach ±1 line pulse.
8. High torque control accuracy, suitable for multi-process processing of various materials; The torque control accuracy is ±5%, and it supports a variety of torque setting methods and a variety of forward and reverse speed limiting methods.
9. Support automatic identification of motor parameters:
In addition to identifying the parameters of asynchronous or synchronous motors, the encoder is also identified and the encoder direction is automatically adjusted. It has the function of online identification of the motor to eliminate the influence of motor heating on the control characteristics.
Third. Introduction to spindle orientation
The drive receives a spindle orientation signal to make the spindle stop quickly in a defined position and provide a certain holding torque to the motor position ring. The spindle orientation customary control is to use an encoder, and the encoder is connected with the spindle 1:1, so as to ensure the accuracy of the orientation.
Fourth, practical application
CNC machining center spindle servo positioning, requiring 485 bus type, can quickly respond to the machine start and stop (0-5000 rpm 0.5 seconds) under energy consumption braking, quasi-stop function, zero servo, in order to achieve cutting, drilling, angle positioning, rigid tapping and other functions.
Fifth. Debugging process and results
1. Tap the hole of No. 45 steel plate M20.
2. M20 tapping, tooth spacing 2.5, excellent effect.
3. A total of more than 80 continuous and uninterrupted tapping without any problems, and the effect is excellent.
