The basic components of CNC machine tools in China’s precision machining include processing program carriers, CNC devices, servo drives, machine tool bodies and other auxiliary devices.
1. Processing program carrier
When the CNC machine tool is working, there is no need for workers to directly operate the machine tool. To control the CNC machine tool, a machining program must be compiled. The part processing program includes the relative motion trajectory of the tool and workpiece on the machine tool, technological parameters (feed spindle speed, etc.) and auxiliary motion. The part processing program is stored on a program carrier in a certain format and code, such as perforated paper tape, cassette tape, floppy disk, etc., and the program information is input to the CNC unit through the input device of the CNC machine tool.
2. CNC device
CNC device is the core of CNC machine tool. Modern numerical control devices all adopt the form of CNC (Computer Numerical Control). This CNC device generally uses multiple microprocessors to realize numerical control functions in the form of programmed software, so it is also called Software NC. The CNC system is a position control system, which interpolates the ideal motion trajectory according to the input data, and then outputs it to the parts required for the execution of the component processing. Therefore, the numerical control device is mainly composed of three basic parts: input, processing and output. All these tasks are reasonably organized by the computer’s system program, so that the entire system works in harmony.
1) Input device: input numerical control commands to the numerical control device. According to different program carriers, there are different input devices. There are mainly keyboard input, disk input, CAD / CAM system direct communication mode input and DNC (direct numerical control) input connected to the upper computer. There are still many systems that still retain the paper input mode of photoelectric readers.
(1) Paper tape input method. You can use the paper tape photoelectric reader to read the part program to directly control the machine tool movement, or you can read the paper tape content into the memory and use the part program stored in the memory to control the machine tool movement.
(2) MDI manual data input method. The operator can use the keyboard on the operation panel to input the instructions of the machining program, which is suitable for relatively short programs.
Under the edit state of the control device (EDIT), input the processing program with software and store it in the memory of the control device. This input method can reuse the program. This method is generally used for manual programming.