1 Introduction The horizontal precision honing machine developed by Delta Electronics Shanghai Branch boasts high working efficiency and performance. This system not only precisely hones the inner circle of workpieces but also accurately detects the "protrusions" on the inner circle. Its processing efficiency far exceeds that of internal grinding machines, as shown in Figures 1 and 2. Figure 1: Horizontal Precision Honing Machine Figure 2: Delta Grinding Machine Electrical Control System 2 System Design 2.1 System Architecture Design The CNC automation of the horizontal precision honing machine is based on Delta Electronics' electromechanical technology integration platform. The platform's main hardware control scheme includes a Delta PLC DVP32EH00M; a Delta frequency converter VFD075V43/full vector; and a Delta servo system 3000W/medium inertia, etc. The control system architecture is shown in Figure 1. 2.1 Core Process and Control Analysis of the Control System This system requires honing and "bump" detection to be performed simultaneously. The honing thickness is mainly achieved by the honing stone, the hydraulic pressure control detection grating, and the PLC. Since the grating signal input is in EA-422 (line drive/5V) format, and the Delta PLC/32EH00M series can receive 2-channel differential input, no other conversion circuit is needed. The grating ruler can be directly connected to the PLC, and the frequency division output of the servo drive is also directly input to the PLC to detect the absolute position of the machine in real time. In the actual honing process, due to the presence of "bumps" on the inner circle of the workpiece, a peak current of the honing variable frequency motor is formed instantaneously. The core PLC of the system remembers the position when this current peak is formed, and then controls the number of times the servo carriage swings at this "bump" to achieve the expected honing accuracy. At the same time, it can automatically grind to the set thickness based on the detection of the inner circle radius of the grating ruler. Therefore, the system adopts the linear correspondence between frequency conversion load and current to complete the detection of "protrusions" on the inner circle of the workpiece. Delta V-series frequency converters are full-vector high-performance drives that can quickly and accurately reflect changes in load current, while Delta PLC uses communication to quickly sample the frequency converter current, which is the key to the system. 2.2 Design features and key control parameters (1) The performance and features of the control system are mainly reflected in the fact that Delta PLC/EH series provides a large-capacity power-off data register (8000 items), so no other peripherals are needed to realize the storage of user process recipes, which is convenient for flexible scheduling of on-site production. (2) The key control parameters consist of the monitoring home page and the parameter setting page, as shown in Figure 2. Figure 2 Key control parameters 2.3 System technical specifications The design of the machining hole diameter is 3-250mm. The maximum machining length is 2500mm. The spindle speed is 50-600 rpm, stepless speed regulation. The honing speed is 1.00m-22m/min. The spindle power is 7.5KW. The machine power is 3KW. The oil pump power is 400W. 3 Conclusion The project was accepted, and the system basically achieved the expected design effect. This machine tool can process inner cylindrical workpieces of various materials, from hardened steel, boron cast iron, cemented carbide, ceramics to aluminum alloy, bronze, plexiglass and other hard and soft materials, as well as inner cylindrical workpieces of other difficult-to-machine materials. References [1] Delta Electronics Group. Delta ASDA Servo Driver Manual [2] Delta Electronics Group. Delta PLC Programming User Manual