I. Overview
The heavy-duty floor-type CNC milling and boring machine is a machine-, electricity-, and liquid-integrated, technology-intensive product. Its performance requirements can achieve five-axis control and can process large-scale workpieces with complex surfaces. It belongs to the high performance and high efficiency in the machining industry. Key precision equipment with higher accuracy. At present, the electronic control part of such products basically relies on foreign imports. Localization can be achieved on the premise of ensuring performance. In particular, adopting a domestically-adopted all-digital servo control system can significantly reduce costs, break foreign monopoly and restrictions on technology, and promote the development of national industry. After the use of Time Technology servo products by a large-scale machine tool factory in a country, the installation and commissioning of the new vertical floor boring and milling machine TJ6916F was officially completed and delivered to users in March 2004 after nearly one year of design and trial.
Second, project introduction
The floor boring and milling machine TJ6916F (see Fig. 1) was designed on the basis of the mechanical structure of the original simple CNC floor boring and milling machine TJ6916. The feed axis requires a three-phase asynchronous motor with a wide range of speeds of 0.3 to 1800 rpm through analog speed control to meet the machining requirements of high-speed feed, low-speed cutting, and low-speed jog-cutting. Therefore, electrical products with low-speed stability and low-speed and high-torque output capability under the premise of wide-range speed control can meet the application requirements of this boring and milling machine.
Ø Speed ​​control accuracy ± 0.04%, speed range up to 1:25000 (0.01Hz-250Hz).
Ø Constant torque output below rated motor speed (torque control range 0-300% motor rated torque, accuracy ±5%)
Constant power output above the rated speed. With low speed and high torque output, zero speed torque retention function.
Ø It has good acceleration and deceleration control function and fast speed response.
(1) Mechanical Design
The characteristics of time servo low speed and high torque can meet the requirements of low speed machining of this type of machine tool, and can achieve the performance of mid-range imported servo with the same power level. It is not necessary to adopt the complex speed reduction mechanism of simple numerical control boring and milling machine, and it is based on the imported numerically controlled boring and milling machine. Mechanical structure and IMS series servo controller speed range, the motor directly drives the screw through a deceleration to drive the feed axis to move. This maximises the machine structure and eliminates transmission errors.
(2) System connection
According to the requirements of the machine for the drive system, the four feed axes share the same potentiometer and are switched by the relay. Designed with high (+10V) and low (approx. 20mV) regulation circuits and a zero (0V) regulation circuit. Feed axis fast forward speed corresponds to potentiometer high voltage, and slow feed speed corresponds to potentiometer low voltage.
(3) Programming
The main function of the feed motor is realized by writing the motor control language QMCL dedicated to the time servo controller. After receiving the enable signal, the motor is powered on. When there is a direction signal, the corresponding frequency control motor is output according to the input analog quantity (0 to 10 VDC). Operation; according to the voltage input of the machine's feed axis low level circuit, the feed axis is controlled to run smoothly at the lowest speed to meet the requirements of low-speed machining and tool setting; through two analog output (0 ~ 5VDC) external ammeter and tachometer, To display the current motor speed and current.
(4) Hardware Configuration
A total of four controllers and motors are used for the four feed axes. The specific hardware configuration is as follows:
name
Model/Specifications
Quantity
Note
Servo controller
IMS-DCT47P5S
2
Servo controller
IMS-DCT4015S
2
Motor
15kw
2
4P/1500rpm
Motor
7.5kw
2
4P/1500rpm
Encoder
2500 line
4
Braking resistor
40 Euro/2500W
4
Two parallel groups
Braking resistor
50 euro/1100W
2
Third, evaluation
The floor-mounted boring and milling machine TJ6916F was assembled and was normally operated after joint debugging by the machine tool factory and the time company. And by the user's test, in the speed range, speed accuracy, speed response, fast feed and low speed feed to meet the performance requirements of the same category of machine tools, some test data are as follows:
main indicators
Axis
Ram
Column
Headstock
Travel (m)
1.2
1.6
6
3
Motor power (KW)
7.5
7.5
15
15
Minimum feed rate (rpm)
0.5
0.9
1.2
1.5
Note: Motor (4 pole), speed range: 0.01 ~ 60Hz (continuously variable), rated speed: 1500rpm.