The automatic line workpiece transfer system generally includes a machine tool loading and unloading device, a conveying device, and a material storage device. In the rotary body processing automatic line, the transfer device includes a gravity-feeding or forced-feeding chute or channel, lifting, indexing, and distribution devices. Robots are sometimes used to perform certain functions of the conveyor. In the automatic line of the combined machine tool, when the workpiece has a suitable conveying base surface, the direct conveying method is adopted, and the conveying device includes various step-type conveying devices, indexing devices and inverting devices, etc., which are irregular in shape and have no suitable conveying base surface. The workpieces are usually positioned and transported on pallets, in which case the return device of the pallets is added.