In the past, to verify the correctness of the program during CNC machining, wooden or plastic molds were often used for trial cutting. This method was inefficient and wasteful of materials. Using CNC simulation for verification is a new technology developed in recent years. It has advantages such as reducing manufacturing costs, shortening the design and manufacturing cycle, speed and intuitiveness, and saving time and effort. It allows operators to pre-detect errors through graphical displays and perform tool interference and collision checks. This paper mainly introduces the simulation software design for the CNC camshaft grinding process. 1 System Implementation of Simulation Software The CNC camshaft machining process does not require CNC programming and is directly controlled by the computer. The key technology for its simulation is to dynamically and intuitively display the formation process of the cam profile and the machining efficiency of the machine tool using graphics. To realize the simulation of the CNC camshaft machining process, the system adopts two-dimensional graphics technology. Functionally, it mainly includes the display of the cam lift curve, the simulation of the motion curve during machining, the simulation of the camshaft machining process, the simulation of machining accuracy, the simulation of grinding wheel dressing, and the simulation of production efficiency. The system block diagram is shown in Figure 1. The software is written in Turbo C2.0 and can run on a 486 microcomputer running DOS 5.0 or higher. In the camshaft machining simulation window, the entire display screen is divided into three windows. The main window occupies the left half of the screen and displays the machining process. The right side of the screen is divided into upper and lower windows, which display dynamic information during the cam machining process to help the operator understand the status of the CNC machining. This includes: camshaft rotation angle, distance between the grinding wheel head and the cam center, camshaft rotation speed, grinding wheel head travel speed, grinding wheel rotation speed, grinding wheel diameter, grinding allowance, current machining time, and cam extreme diameter error. 2. System Menu Structure The CNC camshaft grinding machine simulation system uses a menu-driven approach. The main menu provides seven options: cam lift curve display, motion curve simulation display, camshaft machining process simulation, cam generation via reverse method, machining accuracy simulation, grinding wheel dressing simulation, and return to the CNC system. For CNC camshaft grinding machines, the cam lift curve display and machining motion curve simulation are crucial. The cam lift table is either user-inputted or stored in the system's data file library. By calling this module, the system opens the file library and graphically displays the cam lift curve for users and operators to observe and verify its accuracy. Based on the cam lift table data file and its follower type, considering factors such as machining allowance, changes in the grinding wheel radius after dressing, and constant linear speed control during machining, the mathematical model of the XC linkage coordinate system calculates the C-axis rotational angular velocity and angular acceleration, and the X-axis movement speed and acceleration at various point values. The values ​​are read point by point and plotted point by point, displayed on the computer screen, and stored in the corresponding file. By observing the smoothness and continuity of the curve, the system can predict potential vibrations and impacts during machining, as well as their timing and location, assessing the machine tool's dynamic characteristics and the magnitude of impacts, facilitating the design of the machine tool's moving parts. Cam Machining Process Simulation Cam machining process simulation is a vital part of the overall simulation. Users can observe the entire cam machining process through this window. The working process is as follows: the front and rear centers clamp the cam, the worktable moves along the Z-axis for tool setting, the camshaft rotates for tool setting, the grinding wheel advances rapidly, and cam profile machining begins. After one cam is machined, the grinding wheel retracts rapidly, the worktable moves along the Z-axis, and the next machining cycle begins. During the simulation machining process, to facilitate observation of various parts during machining, the system allows switching between three windows: the axial position simulation window on the machine tool, the production efficiency simulation window, and the cam profile simulation machining window. The system dynamically displays various machining parameters and the time required for machining, verifying whether the production efficiency meets the requirements. Figure 2 shows the simulation results of cam profile machining for automotive camshafts. The drawing-erasing computer animation technology was used in the graphic drawing process. The camshaft, grinding wheel, and centers are drawn with different colors to make the graphics clear and aesthetically pleasing. Machining Accuracy Simulation Machining accuracy is a core indicator of CNC camshaft grinding machines. The simulation software system has a dedicated module for accuracy analysis. During CNC machining, many factors affect the accuracy of the cam profile, primarily mathematical model errors and interpolation errors. To analyze the profile accuracy of the machined cam, the theoretical profile of the cam is compared with the ground cam profile, which incorporates calculation and interpolation errors, and an analysis report is provided. Figure 3 shows the simulation of the machining accuracy of an automotive camshaft. Grinding Wheel Dressing Simulation Grinding wheel dressing of a CNC camshaft includes five processes: 1) Grinding wheel retraction; 2) Table movement along the Z-axis; 3) Tool setting, rapid feed, feed, and dressing according to the dressing amount; 4) Reciprocating movement along the Z-axis during dressing; 5) Returning to the original position after dressing. Through grinding wheel dressing simulation, one can intuitively see whether there is interference or collision during grinding wheel dressing, as well as the time required for dressing, providing a basis for selecting the grinding wheel size and dressing amount. To meet user needs, the system has hotkeys for quick window switching. In the simulation machining window, users can switch between profile simulation, production efficiency simulation, and other windows using the menu and function key F1. Simultaneously, drawing-erasing animation technology is used to define the grinding wheel spindle, grinding wheel, grinding wheel dresser, and machine tool center with different colors, making the simulation results intuitive and clear. 3. Conclusion The development of a simulation system for the CNC camshaft grinding machine machining process enables operators to quickly and intuitively observe the cam machining process, saving design and manufacturing costs, shortening the trial production cycle, and demonstrating good economic benefits.