ã€China Aluminum Industry Network】 1. Features of Aluminum Alloy Profiles Aluminum alloy profiles have the advantages of light weight, attractive appearance, high heat dissipation rate, and good plasticity. They have been widely used in air conditioners, coolers and radiators. In China, the use of aluminum extrusions is becoming more and more popular. Aluminum is mainly used for extrusion. This is due to the fact that the extruded blanks have a good dimensional consistency, a short production cycle, and a relatively low cost. In the extrusion production process of aluminum alloy profiles, the extrusion die has a very important significance to achieve the entire extrusion process. Extrusion dies are basic tools that ensure product formation and have the correct shape, size, and accuracy. Reasonable extrusion tool mold structure, shape and size, to a certain extent, can control the internal structure and mechanical properties of the product, especially in the control of aluminum profile hollow products, weld structure and mechanical properties, the size and shape of the shunt hole and Its distribution position, the shape and size of the welding chamber, and the structure of the core play a decisive role.
2 Aluminum Profile Analysis Figure 1 is a cross-section of an LED lamp radiator aluminum alloy profile. It can be seen from the figure that the aluminum alloy extruded hollow profile of the LED lamp radiator is characterized by large circumcircle size and complex sectional shape. The cross section is large, its length is 340mm, height is 100mm; fins are thin, cantilever is long, tongue ratio is large at the cantilever, and the tongue is relatively large up to 8, while the spacing between the fins is small, there is a dangerous section between the teeth. When the teeth are pressed, it is easy to cause partial teeth and broken teeth to cause mold scrap; secondly, there is a great difference in wall thickness of the profile sections, especially the base thickness of the section root is thick (thickness up to 28mm), and the heat sink The thickness of the thinner part of the tooth is only 2mm, and the ratio of wall thickness to thickness 14 is very high. This results in extremely uneven aluminum flow rate and extrusion flow rate, and also increases the fracture coefficient of the dangerous section. Therefore, it is very difficult for the mold design, manufacture and production of the radiator profile. If the design of the extrusion die is unreasonable, the biased, broken teeth of the die, and the twisting, wave, bending, and cracks of the profile may be scrapped during the extrusion and be scrapped. Therefore, the reasonable design of the extrusion die is the LED lamp radiator profile. The decisive factor for normal extrusion.
3 Design Points for Extrusion Dies In view of the difficulties in the analysis of aluminum extrusion products, we use the wide-extrusion extrusion method for production. After sufficient research, the wide angle of 30° is applied to the two end regions, which is conducive to natural metal flow and the formation of a sufficient pressure chamber at both ends. In order to ensure the straightness of the cross-section of the product after extrusion, the metal flow rate at the center and the edge must be balanced. In the design of the mold structure, the divergent hole, working belt, air knife, welding room, and shunt bridge are the key considerations. 5 aspects of the design, LED lamp radiator aluminum alloy mold structure shown in Figure 2.
3.1 Split hole The split hole is the passage through which the metal leads to the hole. In general, the greater the number of orifices, the more uniform the flow velocity of the metal, the larger volume of the orifice, and the relatively faster flow rate. Therefore, the design of the use of six shunt pore structure and make the shunt bridge to block the wall thickness of the part, so as to play a role in blocking the flow of metal, thereby reducing the flow rate of the metal here, so that the profile extrusion speed tends to be smooth; The hole directly provides a small part of the wall thickness of the teeth, so that the flow velocity of the metal is accelerated, and the flow velocity at the thick and thin part is relatively uniform, so that the flow velocity of the metal tends to be uniform, and the fracture coefficient of the dangerous section can be effectively reduced.
3.2 Working band The working band is the section of the working end of the vertical mould in the mould and used to ensure the shape, size and surface quality of the extruded product and to regulate the flow of the metal and plays an important role in regulating the metal flow rate. In order to make the speed of each part of the profile extrusion uniform and smooth extrusion, the working part of the teeth with thin wall thickness, large cantilever, covered by the mold body is designed to be lower, which is beneficial to reduce the friction of the metal and reduce Metal flow resistance.
3.3 Air knife The air knife is used to reduce the friction so that the product can pass through smoothly and avoid scratches to ensure the product surface quality. In order to prevent the cantilever from breaking or yawing, the design of the empty knife between the teeth is as small as possible; in order to prevent plug molding, the design of the empty knife at the tooth end is as large as possible.
3.4 Welding chamber The welding chamber is a collection of metals flowing out of the split orifices, and the static pressure is continuously increased, so that the die holes are extruded after the metal welding between the split orifices. In order to make the tooth speed faster when the upper and lower welding, thicker parts of the flow rate slower, take the height of the weld chamber 45mm, a smooth transition around the R5, reducing the dead zone, is conducive to metal flow, and reduce the extrusion Resistance.
3.5 Splitter Bridge In order to reduce the chance of weld stripe or to reduce the degree of weld streaks, the chamfer of the diverting bridge is designed as a teardrop shape, and the bridge tip of the diverting bridge is designed as a 20° cone, the smaller the diverging bridge abutment angle The greater the welding pressure of the aluminum alloy flow after the splitter bridge, this is advantageous for metal flow welding, as shown in FIG. 3 .
4 Conclusion In addition to the expansion function, the wide-extension die also plays the role of pre-distribution of metal and adjustment of the flow rate of the exit profile. Practice has proved that the LED lamp radiator aluminum alloy profile with a wide exhibition die design, you can increase the radius of both sides of the end of the radius of the exhibition mold radius and die split hole, working belt, empty knife, welding room, shunt bridge, etc. Optimizing the design not only effectively adjusts the flow rate of the metal during extrusion, but also improves the uniformity of the extruded aluminum profile and reduces the fracture of the dangerous section of the die hole due to the large frontal pressure of the extrusion die. The normal extrusion is achieved, the service life of the extrusion die is greatly extended, and the production efficiency is improved.
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