PURPOSE: To improve the antiabrasive property of a device by welding and setting metallic rods to the side wall and the bottom surface of a spiral groove, and to the inner surface of a V-shaped blade plate installed in the groove, in an adequate interval in the direction crossing the spiral groove.

CONSTITUTION: As the parts metallic rods are welded, the parts exposed to the flow of sand, that is, the bottom 2 of a spiral groove, the side wall 1 of the groove, and the inner surface of a V-shaped blade plate 3 installed to the inside of the groove are used. And the V-shaped blade plate 3 is provided in the spiral groove, and it gives an effect to make the friction among the sand grains stronger by combing and churning the sand when the sand runs in the spiral groove following the rotation of a drum. By setting steel rods inside the spiral groove and the V-shaped blade plate in such a way, the operation for about 5 years can be realized with no repairing. Therefore, not only the service life of the device is extended and the repairing cost is reduced, but also the additional effect to improve the quality of the sand after the polishing process is obtained.