Background Introduction In recent years, with the development of computer networks, the application of Enterprise Resource Planning (ERP) has become increasingly widespread, and the research and application of Manufacturing Execution Systems (MES) have also received high attention from the industry. Induction heat treatment machine tools are a type of clean heat treatment equipment that meets the 3S standards of modern industrial production (Sure, Safe, Saving). They can also be installed on production lines for online metal heat treatment and are widely used in the domestic and international mechanical heat treatment industry. In manufacturing our multi-functional rotary quenching machine tool, we developed a CNC system supporting fieldbus, enabling the machine tool to support industrial Ethernet, allowing for information exchange with workshop-level networks and remote setting of quenching parameters. Introduction to Multi-functional Rotary Quenching Machine Tools Induction heating utilizes electromagnetic induction to heat conductive materials. Its main advantages are: high efficiency, low cost, energy saving, and ease of automatic control. Induction heating equipment for metal heat treatment mainly includes: a heating power supply, an induction heat treatment machine tool, an inductor, and a quenching transformer. The multi-functional rotary quenching machine tool is essentially an automated processing line with comprehensive safety features. Its rotary structure allows loading and unloading to be completed at the same station, making operation convenient. This machine tool can simultaneously process three different surfaces of the same part, enabling one workpiece to be quenched in a single operation on a single machine. It can also quench three identical or different parts simultaneously. Each processing station has flexible parameters, allowing for various quenching methods such as simultaneous, continuous, continuous-simultaneous, and multi-stage quenching. It is primarily used in the automotive and motorcycle manufacturing industries to meet the quenching needs of diverse, small parts. 1. Integrated Design To reduce floor space and installation time, an integrated design is adopted, combining the machine tool with the quenching fluid circulation system, coolant circulation system, heating power supply, and quenching transformer into one unit. 2. Production Line Implementation CNC System Design The requirements for a multi-functional rotary induction hardening machine tool are: ① Three machining stations can operate independently simultaneously (equivalent to three machine tools); ② The speed can change continuously without interruption during continuous hardening; ③ It has self-correction functions for incomplete descent of the three stations and incomplete rotation of the rotary table. Conventional CNC systems cannot meet these requirements, so we independently developed a CNC system based on an industrial PC, and implemented the above functions using thread technology under Windows 2000. The industrial PC host is the core of the system. On the one hand, it detects and controls the various moving parts of the machine tool. On the other hand, it connects to the workshop-level network through a network card, allowing the system to input quenching parameters remotely and display the machine tool's working status. The PCI-1240 is used for stepper motor speed and positioning control, and also detects various abnormal signals of the stepper motor. The PCI-1751 is a 48-channel TTL level parallel input/output board, of which 32 channels are set as inputs for operation button input, including start, pause, and emergency stop buttons, manual heating, spraying, rotation, and switching of the three stations, rapid forward and slow forward and reverse rotation of the turntable, and rapid and slow rise and fall of the workpiece at the three stations. The 16 channels are set as outputs for enabling control of the turntable and the stepper motors at the three stations. The PCL-724 is a TTL level input board used to detect signals such as arrival, material shortage, water shortage, and tip abnormality. Since it lacks level conversion and signal isolation functions, and the proximity switch level is 24V, the PCLD-785 is used as the input level conversion and signal isolation circuit. The PCLD-885 is a 16-channel high-power relay output board with extremely strong output drive capability and a contact capacity of AC 220V 5A. The PCL720 is a 64-channel switch input/output board, mainly used in conjunction with the PCLD-885 to control the switching of various workstations, heating, liquid spraying, blow-off, and tempering. Anti-interference Design Because quenching machine tools are specialized machine tools, the high-frequency or medium-frequency power supplies used in them, due to their modulated wave output, cause particularly severe radiated interference to the power grid and other equipment. Therefore, the control system adopts the following anti-interference measures. Software Design The system software design mainly considers the software's versatility, reliability, and ease of use. Therefore, the following issues are emphasized: ① Switching function when the three workstations use the heating power supply independently and when they share the heating power supply; ② Software design for simultaneous independent operation of the three workstations, with multiple quenching functions such as simultaneous, continuous scanning, segmented simultaneous, and segmented continuous scanning; ③ The ability to store more than 100 workpiece quenching programs, facilitating workpiece management and retrieval; ④ Convenient parameter input, requiring no programming, allowing even those without computer knowledge to input workpiece parameters; ⑤ Online help function, providing prompts at any time; ⑥ Fault self-diagnosis and fault alarm functions. Figure 6 shows the overall block diagram of the system software design. After the computer is powered on, the quenching program runs directly. "System initialization" includes initializing each board, recalling the running parameters of the last run, and determining the position of the "Automatic/Manual" button on the operation panel, automatically switching to the corresponding main screen. After entering the main program, the system periodically checks the status of the [Automatic/Manual], [Start], and [Emergency Stop] buttons on the operation panel and triggers corresponding events. In automatic mode, the system mainly manages workpieces, sets quenching parameters, sets turntable parameters, sets stepper motor acceleration, and performs automatic quenching. In manual mode, the system mainly performs manual operation of each station, manual operation of the turntable, sets the ABC three stations and the turntable zero position, performs automatic zero-position return, and sets manual parameters. Workpiece selection is done in the workpiece management screen. After selecting a workpiece, the system first checks if the parameter files for each station exist. If not, it automatically creates the parameter file names for each station, sets a prohibition flag, and provides a prompt. After the quenching parameters for each station are set, the system automatically removes the prohibition flag. The program exit section is not shown in the overall block diagram. The software exits in two ways: returning to the Windows 2000 desktop or directly exiting the operating system (shutting down). Threading Technology Since three workstations operate simultaneously, the system is configured with four threads: three threads for quenching at workstations A, B, and C; and one thread for indicating the operating status of each workstation. Turntable indexing is handled by the main program. If an abnormality occurs during quenching, the system immediately exits the quenching program and issues an alarm. An abnormality at one workstation does not affect the operation of other workstations. If a workstation fails to descend to its designated position or the turntable indexes incorrectly, the system automatically repositions itself. Remote Parameter Modification Due to cost considerations, the program does not use a client/server architecture and does not support remote ODBC. To support remote modification of quenching parameters, this software can be installed on a remote computer. After modifying the parameter file, the file can be copied to the machine tool control computer. Then, the application can be exited and rerun on the machine tool control computer. Conclusion The small-scale induction heat treatment center is a nine-station induction heat treatment center developed by integrating key aspects of international induction heat treatment machine tools, including compactness, flexibility, multi-axis operation, production line integration, and computerization. In China, it has been applied to the quenching and tempering of motorcycle crankshafts in several manufacturers, including Luoyang Northern Yichu Motorcycle Co., Ltd. and the Heat Treatment Plant of Qianjiang Group Engine Division. In September 2000, it received funding from the Ministry of Science and Technology's Small and Medium-sized Enterprise Technology Innovation Fund (project code: 00C26224100631). In September 2001, it passed the technical appraisal hosted by the Henan Provincial Science and Technology Commission. Expert testing showed that the machine tool's lifting repeatability is ≤±0.03mm, indexing accuracy is ≤±0.02°, and workpiece movement speed is 1～300mm/s. Compared with a similar imported machine tool (one power supply powering three quenching machine tools), the small-scale induction heat treatment machining center is significantly superior in terms of function, price, structure, floor space, worker labor intensity, and processing efficiency. Its fault diagnosis and protection capabilities are comparable to those of imported machine tools. The prototype of the machine tool was exhibited at the Beijing International Heat Treatment Exhibition in October 2001 and received unanimous praise from industry professionals.