The roller device is mounted on the rack at an Angle. The motor is connected with the drum device by a reducer through a coupling, and the drum device is driven to rotate around its axis. When the materials enter into the drum device, due to the tilt and rotation of the drum device, the materials on the screen surface are turned over and rolled, so that the qualified materials (products under the screen) are discharged through the outlet at the bottom of the back end of the drum, and the unqualified materials (products on the screen) are discharged through the outlet at the end of the drum. Because of the material in the roller of the turnover, rolling, so that the material stuck in the sieve hole can be ejected, prevent the sieve hole blocked. The principle and structure of the roller screen sand machine, the roller screen and the roller screen are almost the same.