Self-protection type large conical sand making machine

The utility model relates to a self-protection type large conical sand making machine which can radically avoid damaging upper and lower racks of the conical sand making machine when the thickness of iron passing through a grinding discharge hole of the large conical sand making machine exceeds the maximum opening measurement of the discharge hole. The self-protection type large conical sand making machine comprises a large conical sand making machine body, wherein a plurality of pressure maintaining cylinders are arranged around an upper rack of the large conical sand making machine body; upper lifting lugs are respectively arranged at the lower ends of the plurality of pressure maintaining cylinders; the upper lifting lugs and lower lifting lugs are respectively arranged on a lower rack; the upper lifting lugs are inserted in the space between the lower lifting lugs and are connected with the lower lifting lugs by oil injection axle pins; oil guide channels communicated with axle pin end caps and axle walls are formed in the axes of the oil injection axle pins. The self-protection type large conical sand making machine has the advantages that the damages caused to the pressure maintaining cylinders in the upper and lower racks of the conical sand making machine, the lifting lugs and the racks when the thickness of iron passing through the discharge hole of the conical sand making machine exceeds the maximum opening stroke of the discharge hole are radically overcome; change of the oil injection axle pins becomes normal simple change.