Optimized design of hollow, planar, and long-section aluminum profile dies

1. Optimization of molds for hollow sections with large cross-sections
　　Hollow sections with large hollow cross-sections often exhibit defects such as large-area waviness, excessive planar gaps, and obvious weld seams under conventional design conditions. These problems are usually due to unreasonable mold design structures. Therefore, the author uses a skewed bridge for the upper mold and adds convex ribs inside the hopper for the lower mold in the mold design.
　　During the production process, defects such as waviness on the large surface and excessive planar gaps of the profile are generally caused by the high metal flow velocity near the center of the large surface distribution holes. Therefore, a convex rib of appropriate length is placed in front of the large surface mold hole in the welding chamber. When the metal flows towards the mold hole, the convex rib acts as a low wall to obstruct the flow of the metal. If the obstruction is too great, it is also convenient for mold modification.
　　At the same time, it also optimizes the quality of certain welds.
　　For some rectangular cavities, square tube profiles with a large length-to-width ratio often have weld lines that appear prominently on the large surface decorative surface. The symmetrical bridge can now be changed to an offset bridge. The weld seam is formed because the metal flow does not fully weld before entering the mold hole through the distribution hole under the distribution bridge. Obtaining high-strength, high-quality welds is, of course, our ideal. However, if weld seams inevitably appear on the large surface or decorative surface of the profile during production, it is better to keep them as far away from the large surface or decorative surface as possible. In the case of distribution holes as shown in (Figure 1-2), the center line of the mold bridge is offset outwards (a:b=2:1, a1=a2). Usually, due to the high metal flow velocity in the large surface distribution holes, when the distribution bridge is designed as an offset bridge, this increases the space for the material flow from the large surface distribution holes to fill both sides, and as the center line of the distribution bridge moves outwards, the material flow welding position also moves outwards. Therefore, this adjusts the metal flow velocity on the large surface and moves the weld seam away from the central large surface.
　　2. Optimization of molds for hollow sections with easily biased double mold holes
　　Normally, regardless of whether the two mold holes are arranged vertically or horizontally, due to the high metal flow velocity and sufficient material supply on the side closer to the center, the upper mold core will undergo elastic deformation, resulting in a thin-walled defect on the side of the profile away from the center. Therefore, during the mold design process, when the cross-sectional dimensions of the profile are increased, the cross-sectional dimensions where wall thinning usually occurs are pre-reserved with an offset allowance. If the two mold holes share a central distribution hole, in order to ensure the relatively stable material supply for the two mold holes, a partition-type distribution rib can be added in the middle of the two holes in the hopper, which is also beneficial for mold modification.
　　3. Optimization of molds for planar profiles with small openings and large cantilever areas
　　For this type of profile, under the condition of a conventional full-surface straight feeding planar mold design, it is easy to have large cantilever elastic deformation, resulting in fracture, dropping, etc. In this case, it can be designed as a hanging core mold, but mold modification is not easy. Some profiles have very small openings, almost closed, which can be achieved using a combination mode, but the openings need to be closely matched.
　　For general planar profiles with small openings and large cantilever areas, the straight feeding plate can be designed as a bridge-type feeding plate or a cantilever bridge-type feeding plate, placing the stressed cantilever surface under the bridge. This can protect the cantilever of the profile. When the metal material flow fills the mold hole, the metal flow from the feeding plate passes through the bridge of the bridge-type feeding plate without directly acting on the cantilever, thus reducing the positive pressure on the cantilever of the mold, thereby improving the stress state of the cantilever and extending the service life of the mold.
　　4. Optimized design of molds for long planar profiles with a large length-to-thickness ratio
　　Because the length-to-thickness ratio of the profile is relatively large, and the wall thickness is sometimes relatively thin, the metal flow velocity near the center is relatively fast, and it is limited to adjust the material flow velocity at various parts of the mold hole by simply adjusting the length of the working belt, so deformation defects are easy to occur. The bridge-type feeding plate shown in (Figure 4-2) is now used, which can effectively adjust the metal flow velocity in the middle, so that the material flow velocity at various parts of the mold hole is balanced, and good results can be achieved.
　　5. Conclusion
　　Practice has proved that the above optimization of aluminum profile extrusion mold design is effective in actual production. Compared with the past, the extruded aluminum alloy profiles have better forming, dimensional accuracy, easy to ensure, and improved surface quality. Therefore, the production efficiency of profile extrusion is greatly improved, and the production cost of products is reduced.