Abstract : This paper introduces the application of PLC and frequency converter in the variable frequency feed control system of circular saw, and analyzes the system control scheme and software structure design. This control system has strong functions, good performance, and high reliability. Keywords: PLC; variable frequency speed regulation; feed; circular saw 0 Overview Our company currently has 3 sawing machines, all of which are ingot sawing equipment designed and manufactured in the former Soviet Union. According to their uses, they can be divided into flat, round, and square machine sets. The original circular saw feed system adopts a DC generator-motor speed regulation system controlled by an AC magnetic amplifier (KFD system). The entire system is bulky, energy-intensive, noisy, has low control accuracy, and poor stability at low speed feed, which cannot meet the increasingly demanding requirements for product sawing accuracy. 1 Circular Saw Cutting Process The circular saw cutting process includes: roller conveyor advance, ingot turning machine unloading, guiding, length positioning, clamping, sawing, conveyor advance, and pushing, etc. The simplified process flow diagram of the system is shown in Figure 1. The system's process sequence is as follows: The overhead crane lifts the ingot to the ingot turning machine – after rotation via roller conveyor , the ingot is transported to the specified length – the guiding cylinder guides the ingot – the clamping cylinder clamps the ingot – the saw cuts – the conveyor transports the ingot to the pusher position – the pusher pushes the ingot to the material box. 2. Before the Modification, the saw's feed transmission system: The saw's feed transmission motor drives the reducer, which in turn drives the rack mounted at the bottom of the saw bed, driving the saw bed's movement. The original saw's feed speed was achieved by adjusting the speed of the feed motor, which was controlled by two excitation regulators. One excitation regulator was installed on the electromagnetic station to control the speed at which the saw quickly approaches the ingot (adjusting the strength of the amplifier feedback; generally, this is set during equipment overhaul and no further adjustment is needed); the other excitation regulator was installed on the operating table to control the feed speed when the saw enters the cutting stroke (adjusting the magnitude of the DC motor's excitation magnetic field), which could be adjusted as needed. The feed reducer has a transmission ratio of i=8, so the relationship between the feed rate of the saw and the motor speed can be calculated using the formula s=n/8. Typically, the feed speed range of a circular saw body is 5–20 mm/s, and the rapid return speed is 150 mm/s. [b][align=center]For more details, please click: Automated Control of Circular Saw Feed System[/align][/b]