3. Reasonably adjust the flow speed of metal
The so-called reasonable adjustment is to ensure that each particle point on the section of the product should flow out of the die hole at the same speed under ideal conditions. Try to use a porous symmetrical arrangement. According to the shape of the profile, the difference in wall thickness of each part and the difference in circumference and the distance from the center of the extrusion tube, the sizing belts of unequal length are designed. In general, the thinner the wall thickness of a part of the profile, the larger the circumference, the more complex the shape, and the farther away from the center of the extrusion cylinder, the shorter the sizing belt here.
When the sizing belt is still difficult to control the flow rate, the shape is particularly complicated, the wall thickness is very thin, and the portion farther from the center can adopt the flow angle or the guide cone to accelerate the metal flow. Conversely, for those parts with much larger wall thickness or close to the center of the barrel, the obstruction angle should be used to supplement the obstruction to slow the flow rate here. In addition, it is also possible to adjust the flow rate of the metal by using a process balance hole, a process margin or using a front chamber mold, a flow guiding mold, changing the number, size, shape and position of the split holes.