The inner side of the concave valve plate die forging body is provided with a long installation groove. The depth of the long installation groove is less than the thickness of the concave valve plate die forging body. The long installation groove is provided with a positioning hole that penetrates the concave valve plate die forging body. The two sides of the long installation groove are respectively provided with several limit bumps, The upper end of the limit protrusion is lower than or equal to the upper end of the long installation groove. The limit protrusion is set on both sides of the long installation groove, and the parts installed in the long installation groove are limited by the limit protrusion, so as to prevent mutual friction and damage, and reduce the generation of abnormal noise and noise.