In my country, the development of high-performance CNC systems primarily utilizes standard CNC system products. Development only requires writing PMC software to complete logic control and drive servo axes for accurate feed positioning. Available CNC systems include FANUC and Siemens. The advantage of this approach is that the CNC core software and user interface are already developed by the CNC system developer, resulting in lower development difficulty. The disadvantage is that the CNC kernel is confidential to users, lacking independent intellectual property rights, and incurring higher costs. With the rapid development of electronic technology, computer technology, materials technology, and information control technology, the development of CNC systems in my country has shifted from low-level, economical CNC systems to high-performance CNC system research and development. The development trend is towards high reliability, high flexibility, high machining accuracy, multi-functionality, and manufacturing system automation. This project focuses on researching software and related hardware based on CNC machine tool control systems. Addressing the CNC problems of high-precision internal grinding machines, a PLC product with positioning, analog control, and remote network control functions is used as the control core. Positioning, analog, and network modules are added in a modular fashion, and the CNC functions of the grinding machine are implemented through CNC software development using a human-machine interface. This technical approach involves defining all internal variables, core software, and the CNC touchscreen interface in-house, making development challenging but possessing independent intellectual property rights. It enables direct network control, aligning well with the flexible development direction of the manufacturing industry. From a cost perspective, it reduces the production cost of CNC machine tools. Therefore, the current solution represents a sustainable and innovative CNC system software development approach. After project implementation, the control scheme for CNC machine tools gained more options. 1. Control System Design This grinding machine is a semi-automatic precision grinding machine used for grinding high-roundness inner diameters, suitable for batch processing of various components. Depending on the processing requirements, this machine tool has three working states: adjustment state, semi-automatic state, and parameter tuning state. This system primarily adopts a two-level control structure using a programmable logic controller (PLC) and a touchscreen. The PLC is responsible for inputting button and other switch signals and sending signals to control electrical components such as contactors, relays, and frequency converters, thereby controlling the operation of each motor. It also controls the display of corresponding indicator lights. The touchscreen is used for parameter modification and setting, automatic control, online monitoring, and information transmission. The PC (touchscreen) connects to the PLC via a serial port for communication. Therefore, the touchscreen controls the PLC's operation by issuing commands, achieving semi-automatic control. This machine tool has 13 motors and 1 frequency converter to drive the relevant components. These include a spindle cooling motor, magnetic separation motor, workpiece cooling motor, hydraulic oil pump motor, hydrostatic oil pump motor, oil mist separation motor, hydrostatic oil pump circulation motor, grinding wheel spindle motor, workpiece axis motor, grinding wheel reciprocating motor, hydraulic oil cooling motor, hydrostatic oil cooling motor, grinding wheel dresser motor, and the frequency converter. Among these motors, the grinding wheel spindle motor uses a medium-frequency frequency converter for stepless speed regulation. Feed is divided into grinding wheel axis (axial) feed and headstock axis (radial) feed, with the headstock (radial) feed axis X using servo control. X-axis feed requirements: travel distance 70 mm, position control accuracy 0.003 mm, direct-drive motor and lead screw, lead screw pitch 5 mm. The system requires a medium-inertia motor with a power of 400 W. The hydraulic oil-cooled motor, the hydrostatic oil-cooled motor, and the grinding wheel dresser motor are all DC motors. The reciprocating motion of the grinding wheel is driven by a self-excited DC motor, with speed regulation via a thyristor. The linear (rotary) motion of the machine tool components is achieved by a hydraulic system consisting of 10 solenoid valves. To ensure the reliability of the programmable controller (PLC), an interface circuit is added between the PLC output and the actuators. The control system is shown in Figure 1. The control module uses the FX2N series, with the PLC as the control host and a Mitsubishi 970GOT touchscreen as the human-machine interface. The selected servo positioning unit is model FX2N210GM, the X-axis servo driver is model MR2J 2S260A, the servo motor is model Mitsubishi medium-inertia HC2SFS252, and the encoder resolution is 131072 pulses/revolution. Other components are not described further. [align=center]Figure 1 Control System[/align] 2. System Software Development The software design of the precision internal grinding machine control system consists of three parts: rational planning of internal variables, human-machine interface design, PLC program design, and servo feed program design. Due to space limitations, the PLC and servo program design flowcharts are given, as shown in Figure 2. In the figure, "system power-on" refers to the main power switch; the high-voltage switch is for safety reasons, and the entire system can only work normally when this switch is closed; the working mode will be described later; to ensure the reliability of the machine tool's actions, this system adopts a step-by-step method of logic control and output drive; system initialization includes the initialization of the PLC and positioning parameters. [align=center]Figure 2 PLC and Servo Program Design Flow[/align] 3. CNC Operation Interface Design The CNC operation panel should have a user-friendly interface, convenient operation, strong self-diagnostic functions, and be suitable for the grinding machine's process characteristics. The precision CNC internal grinding machine has five operating modes: motion adjustment, grinding cycle, single wheel dressing cycle, multiple wheel dressing cycles, and new wheel dressing cycle. These operating modes can only be executed after the overall startup. Each step of the machine tool's operation has certain interlocking conditions; the action can only be executed when these conditions are met. To facilitate operator operation, various indicators and necessary prompts are designed on the human-machine interface. The main control interface of the touch screen primarily provides access to these five operating modes or parameter settings. To enhance self-diagnostic capabilities, several operation or fault prompts are displayed to the right of the buttons on the operation entry interface; however, these only appear under certain conditions and remain hidden otherwise. Among the four automatic cycles of the precision internal grinding machine, the "grinding cycle" is the most typical. This design uses the grinding cycle as an example to introduce its control function; the design concept for the other control functions is similar. The grinding cycle control function is as follows: When the conditions for multiple series and parallel grinding cycles are met, pressing the external cycle start button initiates an automatic cycle: First, the feed system automatically returns to the electrical zero position—the longitudinal slide forward solenoid valve, spindle motor, cooling motor, and reciprocating motor are gradually activated according to the working conditions—the feed system feeds to the preset grinding start position—the feed process is completed according to the preset number of feeds, feed amount, and feed speed requirements—the feed system returns to its original position—the longitudinal slide forward solenoid valve, cooling motor, spindle motor, and reciprocating motor are gradually stopped according to the action sequence and conditions, and the reciprocating brake is applied—the cycle ends. An automatic grinding cycle control interface is designed based on the above control function requirements. During the grinding cycle, the cycle conditions, cycle progress, action status, current X-axis position, feed amount, and feed speed can be monitored on the touchscreen. When the cycle conditions are not met, the upper left corner of the automatic grinding cycle control interface will display "Cycle conditions not met"; while during the cycle, a "Cycle Interruption" button will appear on the screen so that the operator can interrupt the cycle at any time. 4. Conclusion The proposed solution has been implemented, resulting in a user-friendly CNC grinding machine operation and display interface. The control logic conforms to the machining process requirements of the CNC grinding machine, and the feed curve for dressing the grinding wheel has been optimized, ensuring accurate positioning as required by the process. Machining accuracy meets the requirements. Practice has proven that this design is a sustainable and innovative CNC system software development solution. After project implementation, the control options for CNC machine tools have increased, and the production cost of CNC machine tools has been reduced.