Sand-gravel unloading mechanism for annular casting machining and sand spraying device

The invention discloses a concrete structure of a sand-gravel unloading mechanism for an annular casting machining and sand spraying device. In order to solve the technical problems in the prior art,the invention particularly provides a double-layer sand falling structure. In the double-layer sand falling structure, the first-layer sand falling structure is dynamic sand falling, and sand-gravel on an elastic rib plate can uniformly drop on a fixed screen by controlling the expansion or contraction state of the elastic rib plate. That is to say, the elastic rib plate is provided with a slot, the two edges of the slot are fixedly connected with edge sealing plates, and sand falling holes are uniformly formed in the elastic rib plate. The second-layer sand falling structure is static sand falling, and the fixed screen can be horizontally arranged and only plays a basic screening role on sand-gravel to prevent particles with too large particle size from falling on the surface of a casting. Compared with the prior