Abstract : This paper describes the process flow and technical parameters of a shot blasting machine unit, introduces the specific functions of the PLC control system, and demonstrates the good performance of the control system after its commissioning. Keywords : PLC; frequency converter; network technology; shot blasting machine; automatic control 1 Process Introduction The shot blasting machine unit mainly includes shot blasting machine roller conveyor and upper pressure roller, four shot blasting machines arranged at 45° to the horizontal, two spiral shot collecting machines, two shot material elevators, one set of shot feeding valve control mechanism, and shot material purification and dust removal equipment. The shot blasting machine layout is shown in Figure 1. After passing through the shot blasting unit, the iron oxide scale on the surface of the round bars can be removed. As the bars pass through the unit, shot is sprayed through four quadrants to polish the surface. The shot and impurities after shot blasting fall into the lower shot trough by gravity. A spiral shot collector then transports the material to the pit of the shot elevator. The shot is lifted to the top of the unit by a scraper on the elevator belt and unloaded onto a fixed receiving inclined plate, flowing into a sorting screen. The screen filters out large iron oxide scale and impurities, which are manually discharged periodically. The shot and dust fall from the screen. Here, a fan carries away the broken shot particles and dust. Normal shot returns to the shot hopper. The surface quality of the shot-blasted bars reaches Asg 2.5-3.0 level, and the maximum equipment noise does not exceed 85dB. [b][align=center]For details, please click: Application of Automatic Control Technology in Shot Blasting Machines[/align][/b]