Quartz sand grinder

A quartz sand grinder comprises concrete supporting frames, two cross beams are fixed to the top ends of the concrete supporting frames, and the middle portions of the cross beams are welded to a positioning sleeve. A supporting plate is welded between the two cross beams, and a speed reducer is fixed to the supporting plate. A motor is fixed to the tops of the two cross beams and connected with the speed reducer through a conveyor belt, a small gear of the speed reducer is engaged with a large gear disc which is arranged on a central sleeve in a sleeving mode, and the large gear disc is supported by a plane bearing; the central sleeve penetrates through a central shaft hole of the positioning sleeve, and the upper end of the central sleeve is locked through a cap; a central shaft is mounted in the central shaft hole, and a thrust bearing is arranged between the central shaft and the wall of the central shaft hole; two big arms are symmetrically mounted at the bottom of the large gear disc, and a transverse s