In a nutshell, it is: correct analysis and judgment, and reasonable adjustment of the metal flow rate.
Various methods such as adjusting the metal flow distribution ratio (such as: adjusting the size of the shunt hole or diversion groove, adjusting the depth of the electro-erosion drainage groove, etc.), adjusting the contact friction coefficient, hindering interception, etc., and adjusting the length of the die hole working belt are adopted. To change the speed at which the metal flows out of the die hole, so that the metal flows out of the die hole evenly, and a qualified extrusion product is produced.
Therefore, mold repairers must be proficient in relevant inspection techniques, so that aluminium alloy profiles can correctly analyze and judge the causes of product defects, so as to carry out effective mold correction.
When the mold is made, the distribution ratio of the metal is basically fixed. Designers must strive for reasonable distribution. If the distribution is unreasonable, the flow rate of each part of the aluminium profile will be uneven, which will bring certain difficulties to the mold repair, and even the mold cannot be repaired in severe cases. For most molds, the frictional resistance between the metal and the mold can be changed, although the amount of metal dispensed has been determined. So as to achieve the purpose of adjusting the metal flow rate.
The friction force between the metal and the die consists of three parts: the contact friction force between the metal and the die surface, the contact friction force between the working belts of the die hole, and the friction force of the relative movement between the metal and the metal.
Improving the frictional conditions between the metal and the die surface can adjust the flow rate of the metal. The speed of the metal flowing out of the die hole can be adjusted by changing the distribution amount of metal, friction conditions, the length of the working belt and the extrusion speed.
Die correction mainly focuses on adjusting the metal distribution ratio, contact friction conditions and the length of the working belt of the die hole and other effective methods to change the flow characteristics of the metal, so that the metal can flow out of the die hole evenly, and produce qualified aluminium profile products.
In order to overcome the defects caused by uneven metal flow, it is necessary to study how to make the metal outflow speed of each part of the aluminium profile section consistent. This is the principle that should be followed in mold design and the basic principle followed by mold repairers.
Although there are many factors that affect the speed of metal flowing out of the die hole, they can be summarized into two basic factors:
1. Whether the metal distribution flow of each part of the aluminium profile section is appropriate. That is, whether the ratio of the cross-sectional area of each part of the aluminium profile is equal to the ratio of the metal flow of the corresponding supply part;
2. When the metal flows, the size of the frictional resistance. When the amount of metal supplied to a certain part of the aluminium profile, the smaller the frictional resistance, the faster the outflow speed of the die hole of this part of the aluminium profile, and vice versa.