CNC numerical control device is supported by hardware, and its control process is completed by software. The following describes the working process of CNC device from eight links: input, decoding, data processing, interpolation, position control, input/output processing, display and diagnosis.
1 input
The parts program, control parameters and compensation data are input to CNC device. Common input modes include keyboard manual input (MDI), memory card input, disk input, serial communication interface RS-232 input, DNC input connected to the upper computer and network communication input.
2 decoding processing
The part processing program is processed by the decoding processing program in the unit of Block. Each program segment consists of several codes. The computer recognizes these codes by decoding program and translates them into data formats (such as binary format) which CNC device can recognize according to certain rules, and stores them in memory (decoding result buffer).
3 data processing
The task of data processing program is to process the data stored in the established storage area after pretreatment. Data processing generally includes tool position compensation, tool length compensation, tool radius compensation, tool tip arc radius compensation, feed speed processing and auxiliary function processing.
4 interpolation operation
Interpolation operation and position control are real-time control of CNC system, which are usually carried out in corresponding interrupt service programs.
5 position control
The task of position control is to compare the theoretical position calculated by interpolation with the actual feedback position of the worktable in each sampling period, control the feed motor according to its difference, drive the worktable or tool to move, and process the required parts.
6 input / output processing
Input/output processing mainly deals with the switching signal of CNC device operation panel and the input/output control of machine tool electrical signal (such as tool changing, gear shifting, cooling, etc.). CNC devices and machine tools must be separated by photoelectric isolation circuit to ensure that CNC devices are not affected by strong electrical signals.
7 display
The display of CNC device is mainly to provide convenience for operators. The display contents include parts program display, parameter display, machine tool status display, dynamic display of processing trajectory, alarm diagnosis display, etc.
8 diagnosis
CNC device uses internal self-diagnostic program to diagnose faults, mainly including start-up diagnosis and online diagnosis.
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