Cross-shaped center fishtail knife

The utility model belongs to the technical field of shield tunneling machine cutters, and particularly relates to a cross-shaped center fishtail cutter which comprises a fishtail cutter body, the fishtail cutter body comprises a first cutter rest, a second cutter rest and a third cutter rest, the first cutter rest is designed in a fishtail shape, and the second cutter rest and the third cutter rest are arranged front and back in a mirror image mode and are arranged perpendicular to the first cutter rest. Outer tool grooves with gradually increased intervals are sequentially formed in the first tool rest on the left side from outside to inside, inner tool grooves with gradually decreased intervals are sequentially formed in the first tool rest on the right side from outside to inside, and center tool grooves staggered with the outer tool grooves and the inner tool grooves are formed in the second tool rest and the third tool rest correspondingly. Shell cutters are arranged in the outer cutter groove, the inner