Seven-series aluminum alloy small piece and die-casting die thereof

The utility model discloses a seven-series aluminum alloy small piece and a die-casting die thereof. A branch runner cavity is communicated between a main runner cavity and a main cavity. An extrusionbag cavity is formed in the rear die, the main cavity is communicated between the extrusion bag cavity and the sub-runner cavity, and delay extrusion is conducted on the extrusion bag cavity in the die-casting process through an air cylinder arranged on the die-casting die in combination with the pressure of an energy accumulator of the horizontal cold chamber die-casting machine. The extrusion bag cavity is adopted; delayed extrusion mode, no-load packing during pressure maintaining, the filler which is not completely solidified in the main cavity is extruded in volume through an extrusion bag of the mold; according to the aluminum alloy small part die-cast by the method, the situation that the structure is loose at the core position with the large wall thickness is avoided, and the defects of local cracks, crac