How much do you know about these key points of aluminum extrusion mold? Small series for you to summarize:

1. Size and deviation of aluminum profile

The size and deviation of aluminum profile are determined by extrusion die, extrusion equipment and other related technological factors.

2. Choose the correct tonnage of aluminum extruder

The selection of extruder tonnage is mainly based on the extrusion ratio to determine. If the extrusion ratio is less than 10, the mechanical properties of aluminum products are low; If the extrusion ratio is too high, aluminum products are prone to surface roughness and Angle deviation defects. Solid aluminum profiles are often recommended at about 30 extrusion ratio, hollow aluminum profiles are around 45.

3. Determine the profile of aluminum extrusion mold

The dimension of extruding die refers to the diameter and thickness of extruding die. The external dimension of extrusion die is determined by the size, weight and strength of the section.

4. Determination of die hole size of extrusion mold

For aluminum profiles with large wall thickness difference, the hard to form thin wall parts and edge sharp corners should be appropriately enlarged. And for the width ratio of large flat wide thin wall profile and wall plate profile of the die hole, the size of the truss part can be designed by the general profile, and the web thickness of the size, in addition to consider the factors listed in the formula, still need to consider the extrusion mold elastic deformation and plastic deformation and overall bending, distance from the center of the extrusion tube and other factors. In addition, the extrusion speed and the presence or absence of traction devices also have certain effects on the hole size.

5. Reasonably adjust the flow rate of aluminum metal

Reasonable adjustment of the flow rate of aluminum metal is to ensure that each particle on the profile section should flow out of the die hole at the same speed. In the design of extrusion die, it shall try to adopt porous symmetrical arrangement. According to the shape of aluminum profile, the difference of the wall thickness of each part, the difference of the specific circumference and the distance from the center of the extrusion cylinder, different diameter bands of different lengths shall be designed. Generally speaking, the thinner the wall thickness, the larger the circumference, the more complex the shape, and the farther away from the center of the extrusion cylinder, the shorter the diameter belt here should be. If it is still difficult to control the flow rate of aluminum metal with the diameter belt, the aluminum profile section shape is particularly complex, the wall thickness is very thin, far from the center of the part can be used to accelerate the flow Angle or guide cone aluminum metal. For those parts with much thicker walls or close to the center of the cylinder, the obstruction Angle should be used to supplement the obstruction to slow down the flow rate here. In addition, the flow rate of the aluminum metal can be adjusted by using process balance hole, process margin or by using front chamber mold, diversion mold and changing the number, size, shape and position of shunt holes.

6. Aluminum extrusion mold strength check

Because the working conditions of the aluminum extrusion die are very bad, the strength of the die is a very important problem in the design of the die. In addition to the reasonable layout of die holes, selection of appropriate die materials, design of reasonable die structure and shape, it is also very important to accurately calculate the extrusion pressure and check the allowable strength of each dangerous section. At present, there are many formulas to calculate the extrusion pressure, but the modified bellein formula still has engineering value. The upper limit method of extrusion pressure also has good application value, and the empirical coefficient method is simple to calculate extrusion pressure. As for the mold strength check, should be based on the type of products, mold structure, etc. General plane mold only need to check the shear strength and bending strength. The tongue mold and plane shunt mold need to check the shear, bending and compression strength, the tongue and tip part also need to consider the tensile strength. An important basic problem in strength checking is to choose proper strength theory formula and more accurate allowable stress. In recent years, the finite element method can be used to analyze the stress and check the strength of the especially complicated dies.

7. Reasonable size of working tape

It is much more complicated to determine the working zone of the shunt composite die than that of the semi-die, not only considering the difference of the profile wall thickness, the distance from the center, and the surface, but also considering that the die hole is covered by the shunt bridge. For the die hole under the shunt bridge, it is difficult for the metal to flow in. In determining the work belt, first of all to find out under the split-section bridge section wall thickness that metal flow resistance big place, the small work belt here is determined to be twice the wall thickness, wall thickness is thicker or metal easy to reach the place, the work belt to consider the appropriate thickening, generally according to a certain proportion, plus easy to flow of the correction.

8. Structure and size of die hole empty knife

Die hole empty tool is die hole work with outlet cantilever support structure. When the aluminum profile wall thickness ≥2mm, can use the relatively easy to process the straight air knife structure; When t<2mm, can choose to have cantilever processing inclined empty knife.