Mixing chamber of casting head for PU material

The invention provides a mixing chamber of a casting head for a PU material. The mixing chamber comprises a fixed plate, n cylinders and (n+1) needle-valves, wherein n is a natural number; the fixed plate is axially provided with a through hole; the sidewall of the fixed plate is provided with a plurality of material injecting holes; the through hole communicates with the material injecting holes;the (n+1) needle-valves are mounted on the sidewall of the fixed plate via the material injecting holes; an m cylinder is arranged between an m needle-valve and an (m+1) needle-valve, andm is any natural number smaller than or equal to n; the m cylinder comprises a left connecting rod, a right connecting rod and a piston rod; one ends of the left connecting rod and the right connecting rod are connected with the piston rod; and the other ends of the left connecting rod and the right connecting rod are respectively connected with the valve stems of the m needle-valve and the (m+1) needle-valve. The mixing chamber of t