Features Of Cnc Controller

The following are some basic cnc characteristics in the current mold processing process:

1. Non-uniform rational b-spline (nurbs) interpolation of curves and surfaces This technology uses interpolation along the curve instead of using a series of short straight lines to fit the curve. The application of this technology has become quite common. Many cam softwares currently used in the mold industry provide an option to generate part programs in nurbs interpolation format. At the same time, the powerful cnc also provides five-axis interpolation and related features. These properties improve the quality of surface finishing, improve the smoothness of motor operation, increase the cutting speed, and make the part processing program smaller.

2. Smaller command unit Most cnc systems transmit motion and positioning commands to the machine tool spindle with a unit not less than 1 micron. After making full use of the CPU processing power to improve this advantage, the smallest instruction unit of some cnc systems can even reach 1 nanometer (0.000001mm). After the command unit is reduced by 1000 times, higher machining accuracy can be obtained and the motor can run more smoothly. The smooth running of the motor allows some machine tools to run at higher accelerations without increasing the bed vibration.

3. Bell-shaped curve acceleration/deceleration is also called s-curve acceleration/deceleration, or crawling control. Compared with the linear acceleration method, this method can make the machine tool obtain a better acceleration effect. Compared with other acceleration methods, it also includes straight-line method and exponential method. The bell-shaped curve method can obtain smaller positioning error.

4. The technology of monitoring the trajectory to be processed has been widely used. This technology has many performance differences, which distinguish its working mode in the low-end control system from that in the high-end control system. Generally speaking, cnc is to realize the preprocessing of the program through the monitoring of the processing trajectory, so as to ensure that it can obtain more excellent acceleration/deceleration control. According to the performance of different cncs, the number of program blocks required for monitoring the track to be processed varies from two to hundreds, which mainly depends on the shortest processing time of the part program and the time constant of acceleration/deceleration. Generally speaking, in order to meet the processing requirements, at least fifteen track monitoring program blocks to be processed are required.

5. Digital servo control The development of digital servo system is so rapid that most machine tool manufacturers choose this system as the servo control system of machine tools. After using this system, cnc can control the servo system more timely, and the control of the machine tool by cnc has become more precise. The functions of the digital servo system are as follows:

1) The sampling speed of the current loop will be increased, coupled with the improvement of the current loop control, thereby reducing the temperature rise of the motor. In this way, not only can the life of the motor be extended, but also the heat transferred to the ball screw can be reduced, thereby improving the accuracy of the screw. In addition, the acceleration of the sampling speed can also increase the gain of the speed loop, which helps to improve the overall performance of the machine tool.

2) Since many new cncs use high-speed sequences to connect to the servo loop, through the communication link, cnc can obtain more information about the work of motors and drives. This can improve the maintenance performance of the machine tool.

3) Continuous position feedback allows high-precision machining under high-speed feed. The acceleration of cnc computing speed makes the rate of position feedback become a bottleneck restricting the operating speed of machine tools. In the traditional feedback method, as the sampling speed of the cnc and the external encoder of the electronic device changes, the feedback speed is restricted by the signal type. Using serial feedback, this problem will be well resolved. Even if the machine tool runs at a high speed, it can achieve precise feedback accuracy. 6. Linear motors In recent years, the performance and popularity of linear motors have been significantly improved, so many machining centers have adopted this device. So far, Fanuc has installed at least 1,000 linear motors. Some advanced technologies of Ge Fanuc make the linear motor on the machine tool have a maximum output force of 15,500n and a maximum acceleration of 30g.

The application of other advanced technologies has reduced the size, weight, and cooling efficiency of the machine tool. All these technological advancements make linear motors have stronger advantages when compared with rotating motors: higher acceleration/deceleration rates; more accurate positioning control, higher stiffness; higher reliability; internal dynamic control move.