A continuous unblocked flow surface can be obtained at the die lip. The full push-type adjusting screw equipped with small intervals plays a role in the upward and downward rebound of the metal. The die lip can be bent to adjust the gap between the die mouth. The movable lower die lip is designed to meet the different thickness equirements of the extruded sheet. The mould is plated with chromium inside and outside, and the mould cavity runner is plated with hard chromium to achieve anticorrosion and anti-adhesion effect. The fasteners are made of 12.9 grade high-strength bolts with high quality, and the built-in stainless steel heating rod is used for partition control of heating.