Aluminum alloys are widely used in radiator materials due to their light appearance, good thermal conductivity and easy processing into complex shapes. There are three main types of aluminum alloy radiators: flat and wide, comb or fishbone; round or The elliptical outer fins are radial and dendritic. Their common feature is that the distance between the fins is short, and a groove shape is formed between the adjacent fins, and the aspect ratio thereof is large; the wall thickness difference is large, the fin is generally thin, and the bottom of the root has a large thickness. Therefore, it is very difficult for heat sink manufacturers.
The radiator profile has a part of small size and symmetrical shape, which is relatively easy to produce. Most of the radiator profiles are flat and wide, the outer dimensions are large, some are asymmetrical, and the groove has a large aspect ratio between the fins. Production is difficult. It is necessary to cooperate with the ingot, mold and extrusion process in order to smoothly produce the radiator profile. Alloys for standard custom heat sink profile must have good squeezability and thermal conductivity. Alloys such as 1A30, 1035 and 6063 are commonly used. At present, 6063 alloy is widely used because it has good mechanical properties in addition to good squeezability and thermal conductivity.
The production of aluminum alloy radiator profiles begins with the quality of the ingot, the material and design of the mold, the reduction of the pressing force and the extrusion process.
1. Quality requirements of ingots
The alloy composition of the ingot must strictly control the impurity content to ensure the purity of the alloy melt. The ingot is subjected to sufficient homogenization treatment to make the structure and performance of the ingot uniform. The surface of the ingot should be smooth and no segregation or sticking of sand is allowed. The end face of the ingot should be flat and cannot be cut into steps or the slope is too large.
2. The requirements of the mold
The quality of the heat sink hot extrusion mould steel must be reliable. It is best 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 best to use high-pressure pure nitrogen quenching to ensure uniform performance of the various parts of the mold after quenching. The mold must have sufficient toughness, the design should be reasonable, and the manufacturing must be precise. For the flat wide heat sink, in order to ensure a certain rigidity of the mold, the thickness of the mold should be appropriately increased.
3. Reduce the pressing force
In order to prevent the die from breaking the teeth, the pressing force should be minimized, and the pressing force is related to the length of the ingot, the magnitude of the alloy deformation resistance, the state of the ingot, and the degree of deformation.
4. Extrusion process
The key to the production of radiator profiles is the first test of the extrusion die. When the die is successfully pressed after the test, the extrusion speed should be controlled to achieve smooth operation. When manufacturing the radiator profile, pay attention to the heating temperature of the mold, so that the mold temperature is close to the temperature of the ingot. If the temperature difference is too large, the temperature of the metal will decrease due to the slow extrusion speed when the pressure is applied, and the phenomenon of blockage or uneven flow rate may occur.