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Foreword: The quality and efficiency of aluminum profile production are closely related to the design and structure of the extrusion die. Based on the work practices and production experience of the past few years, the author briefly introduces several optimizations of the aluminum extrusion die that often occur in practical production. Design practice, discuss with your peers.
1. Optimization of some large section hollow profile moulds
In the case of conventional design, the hollow section with large hollow section has often appeared large surface wave, plane clearance is very bad, obvious weld and other defects. These problems are usually caused by the irrationality of the mold design structure. To this end, the author in the mold design: the upper mold uses a partial bridge, the lower mold in the silo plus ribs design.
In the production process, defects such as large surface wave and out-of-plane clearance of profiles are generally due to the fact that the large-surface diverging hole is close to the center and the metal flow velocity is high. Therefore, a large amount of die holes in the welding chamber must be set beforehand. The length of the ribs is such that when the metal flows into the die hole, the rib acts as a barrier against the flow of the metal, and if the barrier is too great, it is easy to repair the die.
At the same time, the quality of certain welds has also been optimized accordingly.
For some rectangular cavities, square pipe profiles with relatively large aspect ratios, the weld line often appears on the large-surface decorative surface. The symmetry bridge can now be changed to a partial bridge type. The weld is formed because the metal flow is not fully welded before passing through the split hole into the hole under the bypass bridge. It is of course ideal for us to obtain high-strength and high-quality welds. However, if in the production process, the weld seam inevitably appears on the large or decorative surface of the profile, it may be as far away as possible from the large surface or the decorative surface. In the case of a splitter orifice (Figure 1-2), the midline of the mold bridge is shifted outward (a:b=2:1, a1=a2). In general, since the flow rate of the metal in the large-surface diverging hole is fast, when the form of the diversion bridge is designed to be a partial bridge type, the space filled in both sides of the material flow in the large-surface diverging hole is increased, and the center of the diverging bridge is added. With the outward shift of the line, the position of the flow soldering station also shifts outward. Therefore, the flow rate of the large-surface metal is adjusted in this way, and the weld is further away from the large center surface.
2ã€Optimization of double-mode hole easy-walled hollow profile mold
Normally, regardless of whether the two holes are ejected up or down or left and right, the metal flow near the center side will be fast, and the material supply will be sufficient to cause the upper mold core to elastically deform outwards to cause the profile to be far away from the center. Partial wall defects. Therefore, in the process of mold design, when the profile section size is heavy, the section size that normally generates the offset wall is left with an offset margin in advance. If the two die holes share the center diverting hole, in order to ensure relative stability of the feeding of the two die holes, a partition type diverting tendon may be added in the middle position of the two holes in the bin, which is also favorable for repairing the die.
3ã€Optimization of flat profile molds with small openings and large wall area
In the case of a planar mold design where the material is usually fully straightened, it is prone to large elastic deformations of the cantilever so that breakage, missing blocks, etc. may occur. In this case, it can be designed as a hanging mandrel, but repairing the mold is not easy. Some profile openings are very small, almost closed, this can be combined mode, but the opening needs to be tight.
In general, the flat profile with small opening and large arm area can design the straight feed plate as a bridge feed plate or a cantilever bridge feed plate, and the forced wall surface under the bridge can be applied to the profile. Cantilever protection, when the metal stream fills the mold hole, the metal flow from the feed plate through the bridge feed plate bridge does not directly affect the cantilever shield, which reduces the positive pressure on the cantilever of the mold, thus Improve the cantilever's stress state. Extended mold life.
4ã€Optimum Design of Long Profile Plane Profile Mould with Long Thickness Ratio
Due to the relatively large thickness-to-thickness ratio of the profile, the wall thickness is sometimes relatively thin, and the metal flow velocity near the center is relatively fast. It is limited to adjust the material flow velocity in the die hole only by the length of the working belt, so deformation defects are easily generated. The bridge type feeding rice shown in Fig. 4-2 is adopted, which can effectively adjust the intermediate metal flow rate, so that the velocity of the material flow in the die holes can be equalized and good results can be obtained.
5 Conclusion
Practice has proved that the above-mentioned optimization of aluminum extrusion die design is effective in actual production. Extrusion of aluminum alloy profiles compared to the past, molding, dimensional accuracy, easy to guarantee, the surface quality has also been a good improvement. Thus, the production efficiency of the profile extrusion is greatly improved and the production cost of the product is reduced.
For the extrusion die design of aluminum extrusion products, along with the rapid development of various industries in the society, the shape of the profile of the profile is complicated and diversified, and it is designed according to the common and common forms, and there are many deficiencies. Therefore, in order to obtain high-quality profiles, we must constantly learn and accumulate in production and life, and constantly reform and innovate.