1. Static effects
The formula for calculating the flow rate of the extruder is: Q = Qd-Qp-Ql is equal to the algebraic sum of positive flow Qd, pressure flow Qp and leakage flow Ql. Among them, the extruder leakage Ql is a flow in the radial direction of the screw in the gap δ formed by the screw rib and the barrel. Flow. Since the gap δ is very small, under normal circumstances, the leakage flow is much smaller than the positive flow. But it cannot be completely ignored.
2 Dynamic impact
The above only statically analyzes the influence of the screw barrel gap on the performance of the extruder, mainly the assembly gap in the greenhouse. When the extruder is running, due to the processing temperature and the pressure screw on the screw, the actual gap between the screw and the barrel will change. When the processing temperature is much higher than that in the greenhouse, the screw and the barrel have different thermal expansion coefficients, or when the screw temperature and the barrel temperature are different, the gap will change. The change of the gap may cause the screw to lock.