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欲使压铸件轮廓清晰,表面光洁,内部无夹杂气孔,则必须对高压下的充填成型过程有一清楚的了解。对此向题可由以下四方面入手进行探讨。一、压力铸造时的充填型式: 液体金属是在高压下以很高的速度充填型腔。在大多数情况下,其充填型式如下。若型腔的形状为矩形板状,浇口开设在型腔之一端,如图1。金属流以很高的速度由浇口射出,穿过型腔直接射到其对面的型壁上,然后冲击到侧壁上,向浇口方向回流。由于侧壁对回流金属流的摩擦阻力,在流动过程中温度降低,使粘度迅速增高,因而使此回流金属流的流速减慢,与此同时,一部分液体金属积聚在型腔的中部。由于沿侧壁回流的流速不断减慢,中部积聚的液体金属的阵面赶上了回流
To make the outline of the die-casting clear, smooth surface, no inclusions within the pores, you must have a clear understanding of the filling process under high pressure. This question can be discussed from the following four aspects. First, the pressure casting filling type: liquid metal is under high pressure to fill the cavity at a high speed. In most cases, the fill type is as follows. If the shape of the cavity is a rectangular plate, the gate is opened at one end of the cavity, as shown in FIG. 1. Metal flow at a high rate of injection from the gate through the cavity directly to the wall opposite the type, and then hit the side wall, the direction of the return gate. Due to the frictional resistance of the sidewall to the recirculating metal flow, the temperature drops during the flow, causing the viscosity to increase rapidly, thereby slowing the flow of the recirculating metal stream while a portion of the liquid metal accumulates in the center of the cavity. As the flow rate along the side wall continued to slow down, the central accumulation of liquid metal front catch up with the return flow