Extrusion technology for radiator profiles
[China Aluminum Industry Network] Aluminum alloys are widely used in radiators because of their light weight, good appearance, good thermal conductivity and easy processing into complex shapes. There are three types of aluminum alloy radiators: flat-width, comb-shaped, or fish-bone-shaped; round or oval-shaped outer radiating fins are radially; dendritic. As shown in Figure 1. Their common characteristics are: the short distance between the fins, the formation of a groove between the adjacent two fins, the depth-width ratio is large; wall thickness difference is large, the general fins thin, and the thickness of the base plate at the root. Therefore, it is very difficult to design, manufacture and produce molds for heat-dissipation profiles. Radiator profiles have a relatively small size and symmetrical shape. Products are relatively easy to produce. Most of the radiator profiles are flat, wide in shape, large in size, and somewhat asymmetric. The ratio of groove to width between the fins is very large. It is difficult to produce. Need to cooperate with the ingot, mold, extrusion process in order to successfully produce radiator profiles. The alloy used to extrude the heat sink profile must have good extrudability and thermal conductivity, and alloys such as 1A30, 1035, and 6063 are commonly used. At present, more commonly used is 6063 alloy, because it has good mechanical properties, in addition to good extrudability, thermal conductivity. The production of aluminum alloy radiator profiles starts with the quality of the ingot, the material and design of the mold, the reduction of extrusion force, and the extrusion process. 1, the quality requirements of the ingot The alloy composition of the ingot must strictly control the impurity content and ensure the purity of the alloy. For 6063 alloy to control the content of Fe, Mg, Si. The content of Fe should be less than 0.2%, and the content of Mg and Si is generally controlled at the lower limit of the national standard. The Mg content is 0.45%-0.55% and the Si content is 0.25%-0.35%. Ingots should be fully homogenized to make the ingot uniform in structure and performance. The surface of the ingot should be smooth and no segregation or sticking of sand should be allowed. The end surface of the ingot must be flat and cannot be cut into steps or cut too much (cutting should be within 3?). Because the step shape or skewness is too large, if there is no design diversion when squeezing the heat-dissipating profile with a planar die, the sword is not designed for diversion.冉哟ツ 冉哟ツ> æ’¸ α α ? æ ¡ ? 装 å© å© å© å© èªæ¸ èªæ¸ 希 希 希 希 希 希 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 蛟 å— å— å— å— èš£èŸ†?/p> 2, the mold requirements Because the radiator profile mold is a lot of slender teeth, to withstand a lot of pressure, each tooth should have high strength and toughness, if the performance of each other is very different, it is easy Those teeth that have poor strength or toughness break. Therefore, the quality of the mold steel must be reliable, it is better to use H13 steel produced by a reliable manufacturer, or use high-quality imported steel. The heat treatment of the mold is very important. It is necessary to use vacuum heating and quenching. It is better to use high-pressure pure nitrogen quenching to ensure that the performance of the various parts of the mold after quenching is uniform. After quenching, three temperings shall be taken to ensure that the hardness of the mold is sufficient in the HRC48-52 premise. This is an important condition to prevent the die from being broken. The key to the successful extrusion of radiator profiles is the rational design of the mold and the accuracy of manufacturing. Generally try to avoid direct extrusion of the ingot to the mold working belt. For flat-width comb-shaped heat sink profiles, a smaller, larger-sized diversion mold is designed to allow the metal to flow to both sides, reducing the pressing force on the mold working belt and evenly distributing the pressure. Due to the large difference in wall thickness of the cross section of the radiator profile, the design mold work zone must maintain their differences, that is, the work zone with a large wall thickness should be particularly enlarged, and can be as large as 20 mm to 30 mm, and the position of the tooth tip should be Break through the routine and reduce the work belt to a smaller one. In short, it is necessary to ensure the homogeneity of the flow of metal throughout. For flat wide radiators, in order to ensure that the mold has a certain degree of rigidity, the thickness of the mold must be appropriately increased. The increase in thickness is about 30% to 60%. The production of the mold must also be very fine. The empty knife must be symmetrical in the up-down, left-right, and middle positions. The machining error between the tooth and the tooth should be less than 0.05mm. The machining error is likely to produce uneven teeth, that is, the thickness of the heat sink is uneven. Even broken teeth may occur. For the relatively mature design of the section, the use of embedded alloy steel mold is also a better method, because the alloy steel mold has better rigidity and wear resistance, is not easy to produce deformation, is conducive to the formation of the radiator profile. 3, reduce the extrusion force In order to prevent the broken teeth of the mold, the extrusion force should be minimized, and the extrusion force is related to the length of the ingot, the resistance of the alloy deformation, the state of the ingot, and the degree of deformation. Therefore, the extruded cast Rods for heat-dissipating aluminum profiles should not be too long, about the length of normal cast rods (0.6-0.85 times). In particular, when trial moulds and extrusions are made on the front roots, in order to ensure the smooth production of qualified products, it is better to use shorter casting rods, ie casting rods of normal casting rod length (0.4-0.6) times. Test mode. For the complex shape of the heat dissipation shouting profile section, in addition to shortening the length of the cast rod, it is also considered to use the pure aluminum short cast for the previous trial extrusion, and after the trial squeezing is successful, the normal ingot is used for the extrusion production. Ingot homogenization annealing not only can make the structure and performance uniform, but also can improve the extrusion performance and reduce the extrusion force, so the ingot must be uniform annealing. As to the effect of the deformation degree, since the sectional area of ​​the heat sink profile is generally relatively large, the extrusion coefficient is generally within 40, so its influence is small. 4, extrusion process The key to the production of heat sink profiles is the previous die test of the extrusion die. If conditions permit, I can do a simulation test on the computer to see if the work zone of the die design is reasonable, and then try the die on the extruder. It is very important to rely on the previous test mode. The operator should allow the main plunger to move forward at a low pressure of less than 8 MPa when it advances and pressurizes. It is better that someone uses the light of the torch to take care of the exit of the die, and each heat of the extrusion die is released. After pressing the die holes uniformly, the sheets can be gradually pressurized and accelerated. After the success of the trial moulding, the extrusion speed should be controlled to achieve a smooth operation. When producing radiator profiles, the heating temperature of the mold should be taken into consideration. The temperature of the mold should be similar to the temperature of the ingot. If the temperature difference is too large, due to the slow extrusion speed during the upper pressure, the metal temperature will drop, and it is easy to cause mold blocking or uneven flow rate. Radiator profile extrusion process parameters are shown in Table 1. Table 1 Heat sink profile extrusion process parameters Gold ingot temperature/°C barrel temperature/°C mold temperature/°C extrusion coefficient extrusion speed min-1 1035, 1A30 400 - 470 400 - 440 400 - 460 20 - 60 15 - 50 6063 500 - 520 400 - 450 480 - 500 15 - 40 10 - 30 5. Concluding remarks In addition to the above factors, the extrusion technology of the radiator profile is also related to the capacity and level of the extruder, the degree of automation of the rear equipment, and the operating skills of the workers. Different sections of the thermal profile should be based on their characteristics. Take corresponding measures and do not generalize. Original Abstract "From Proceedings of the 13th China Light Alloy Processing Academic Conference" ss316 wire Jiangsu Minglu Stainless steel Co.,ltd , https://www.minglufastener.com