To manufacture a set of high-quality aluminum extrusion molds, not only good processing equipment and skilled extrusion mold manufacturing workers are required, but another very important factor is to have a good extrusion mold design.
The design of a die extrusion tool is:
On the premise of meeting customer requirements, the processing cost is low, the processing difficulty is small, and the processing time is short. The mold can produce qualified products in the shortest time. To do this, it is not only necessary to fully understand the customer's requirements, but also to require the mold designer to have an understanding of the extruder, extrusion mold structure and processing technology, and the processing capabilities of the factory. Therefore, as an extrusion mold designer In order to improve the design level of extrusion die, the following points should be done:
1. Familiar with the size and deviation of aluminum profiles
The size and deviation of aluminum profile are determined by extrusion die, extrusion equipment and other related process factors.
2. Choose the right aluminum extrusion press tonnage
The tonnage of the extruder is mainly determined according to the extrusion ratio. If the extrusion ratio is lower than 10, the mechanical properties of the aluminum profile product will be low; if the extrusion ratio is too high, the aluminum profile product is prone to defects such as surface roughness and angular deviation. The recommended extrusion ratio for solid aluminum profiles is about 30, and that for hollow aluminum profiles is about 45.
3. Determine the shape of the extrusion die
The external dimensions of the extrusion die refer to the outer diameter and thickness of the extrusion die. The external dimensions of the extrusion die are determined by the size, weight and strength of the profile section.
4. Determining the size of the die hole of the extrusion die
For aluminum profiles with large wall thickness differences, the difficult-to-form thin-walled parts and edge sharp corners should be appropriately enlarged in size; for flat-width thin-walled profiles with large width-to-thickness ratios, the die holes of the wall profile and the beams The size can be designed according to the general profile, and the thickness of the web, in addition to the factors listed in the formula, also needs to consider the elastic deformation and plastic deformation of the extrusion die, the overall bending, and the distance from the center of the extrusion cylinder. In addition, the extrusion speed, the presence or absence of a traction device, etc. also have a certain influence on the size of the die hole.
5. Reasonably adjust the flow rate of aluminum metal
Try to ensure that every particle on the section of the aluminum profile should flow out of the die hole at the same speed. When designing the extrusion die, try to use multiple holes and symmetrical arrangements. According to the shape of the aluminum profile, the difference in the wall thickness of each part, the difference in the circumference and the distance from the center of the extrusion cylinder, design sizing belts of unequal length.
6. Extrusion die strength check
Mold strength is a very important issue in mold design. In addition to rationally arranging the positions of the die holes, selecting suitable die materials, and designing a reasonable die structure and shape, it is also very important to calculate the extrusion force and check the allowable strength of each dangerous section. As for the check of mold strength, it should be carried out separately according to the type of product, mold structure, etc. Generally, flat molds only need to check the shear strength and flexural strength. Tongue molds and flat split molds need to check the shear, flexural and compressive strengths. The tongue and needle tip parts also need to consider the tensile strength. In recent years, the finite element method can be used to analyze the stress and check the strength of particularly complex molds.
7. Reasonable working belt size
Determining the working zone of the split combined mold is much more complicated than determining the working zone of the half mold. Not only the thickness difference of the profile wall, the distance from the center, the surface, but also the situation that the mold hole is shielded by the split bridge must be considered. For the die hole under the shunt bridge, because of the difficulty of metal flow, the working belt must be thinner. When determining the working zone, first find out where the wall thickness of the profile under the shunt bridge is the thinnest, that is, where the metal flow resistance is greater. The minimum working zone here is set at twice the wall thickness. The wall thickness is thicker or the metal is easy to flow. Where it is reached, the working belt should be thickened appropriately, generally according to a certain proportion, plus a correction value for easy flow.
8. The structure and size of the die hole empty knife
The die hole empty knife is a cantilever support structure at the outlet end of the die hole working belt. When the wall thickness of the aluminum profile is ≥2mm, the straight hollow knife structure that is easier to process can be used; when the wall thickness of the aluminum profile is less than 2mm, you can choose to process the oblique hollow knife at the cantilever.
