The working principle of the feeder: There are some subtle differences in the working principle of different types of feeders, but the overall principle is similar. For the roller feeder, it is divided by the feeding device, the conveying wheel, the transmission rod, the bracket, and the control. The circuit is composed of five parts, and the material distributing device discharges the material to the conveying wheel with one bar at a time, and the conveying wheel feeds the bar material into the grinding zone. When working, the bar is above the conveying wheel. When the bar is worn and rotated, the friction of the bar is reduced in the state in which the rotation of the conveying wheel advances, thereby improving the grinding accuracy. The vibration and noise during operation are very small, especially suitable for long bar and precision workpiece machining. At present, the roller type automatic feeder which is widely used at home and abroad can be used in various types of centerless grinding machines.