There are many types of aluminum alloy wheels, but the production processes of aluminum alloy wheels are mainly as follows: the same material, through different production processes, the quality of the aluminum alloy wheels produced is also different. In fact, when we buy and choose aluminum alloy wheels, we can clearly feel that the appearance of wheels of any brand looks the same, but the price is very different. The main reason is that the manufacturing process is different, and the difference in the process means that the difficulty is different. , The quality of the products made is also different, the craftsmanship is difficult, the output is not high, and the price is reasonable, so when we buy and choose the wheel brand, how should we choose the craft? Is it necessary to pursue the best The most expensive is the best. Let's take a look at the difference between these processes and how important they are in daily use, and then decide which brand of aluminum alloy wheels to choose. 1, gravity casting Metal gravity casting refers to a casting method in which liquid metal fills the metal mold by gravity under normal pressure to obtain castings. This is also an ancient casting method. Due to the faster cooling rate of molten metal in the metal mold, the structure of the casting is denser than that of sand casting. This method has simple procedures, high production efficiency, less equipment investment, and lower production cost. It is suitable for small and medium-sized production. However, the internal quality of the aluminum wheel produced by this method is poor, and the shrinkage cavities and porosity are serious. In the casting process, the oxide film and slag are easily involved in the casting, and sometimes the gas is involved to form pore defects. At the same time, the molten metal is collected. The yield is also low. Most OEMs have now rejected wheels produced by this process, and there is a tendency to gradually be marginalized in the aluminum wheel manufacturing industry. 2, low pressure casting low pressure casting is to place the mold on a closed furnace, and use a tube (called a riser tube) below the cavity to communicate with the metal in the furnace. If pressurized air is added to the molten metal surface in the furnace, the molten metal will flow into the cavity from the riser pipe. After the molten metal has solidified, the compressed air in the furnace is released, and the unsolidified metal flows back into the furnace from the riser pipe. By controlling the pressure and speed of the air flowing into the furnace, the speed and pressure of the metal flowing into the cavity can be controlled, and the metal can be crystallized and solidified under pressure. The characteristics of this process are that the casting crystallizes under pressure, the structure is dense, the mechanical properties are good, and the metal utilization rate is high. The low-pressure casting process is quite mature in mainland China and is suitable for humanized production management. It has been recognized by all OEMs as the current mainstream process for aluminum alloy wheel manufacturing in mainland China. The products are mainly sold to OEM and overseas retail markets. Aluminum alloy wheels manufactured by low-pressure casting process, because the spokes are finally cooled and solidified, the spokes of some special-shaped wheels are prone to shrinkage and other quality problems, while the rim part has better strength due to the earliest crystallization. 3, squeeze casting method Squeeze casting, also known as liquid die forging, is a new process that integrates casting and forging features. This process is to directly pour a certain amount of metal liquid into an open metal mold, and use a punch with a certain pressure. On the liquid metal, it is filled, shaped and crystallized and solidified, and a certain amount of plastic deformation is generated during the crystallization process. Squeeze casting is stable in filling, without turbulence and no entrapment gas. The metal crystallizes and solidifies directly under pressure, so the casting will not produce casting defects such as porosity, shrinkage and porosity, and the structure is dense, the grain is refined, and the mechanical properties are Higher than low-pressure castings. The product not only has excellent mechanical properties close to forgings, but also has high efficiency and high precision for one-time precision forming of precision castings, and the investment is much lower than the low-pressure casting method. The disadvantage is that liquid die forging products are the same as traditional forging products, which require milling to complete the shape of the spokes. A considerable part of automobile aluminum wheels in Japan are produced by squeeze casting process. Toyota Motor Corporation has more than a dozen fully automatic squeeze casting equipment, each of which can produce an aluminum wheel in less than 2 minutes, from pouring molten metal to taking it out The whole process of casting is controlled by computer, and the degree of automation is very high. A modern squeeze casting automobile aluminum alloy wheel factory has also been built in Guangdong in China, which has produced automobile aluminum wheels of various specifications and models, and the product quality has been verified to reach the advanced level of similar foreign products. At present, all countries in the world regard squeeze casting as one of the directions of automobile aluminum wheel production. 4, casting spinning casting spinning is divided into "low pressure casting + spinning" and "gravity casting + spinning" two processes. At present, Korean car companies have a trend of fully adopting "low pressure casting + spinning" for the forming process of aluminum wheels. Other car series also have some products that require this process. This process is the mainstream process in the casting and spinning process and is used as an OEM product. Most of the companies use this process; at the same time, a small number of companies engaged in overseas retail markets use the "gravity casting + spinning" process. Theoretically speaking, this process is feasible. The advantages of the gravity casting and spinning processes are combined, and the product quality has been improved. However, because the blanks are produced by the gravity casting process, the economics of this process are very poor and the production cost is very high. In short, the cast-spinned product, because the spoke part is cast, has the same advantages and disadvantages as the product produced by the casting process; and the rim part is spun, so the air tightness is better. In theory, cast-spinning products can reduce weight, but the effect is not obvious in practical applications. 5, conventional forging Forging is one of the earlier forming processes for aluminum wheels. Forged aluminum wheels have the advantages of high strength, good corrosion resistance, precise dimensions, and small processing volume. Generally, their weight is only 1/2 or less of that of steel wheels of the same size. The grain flow direction of the forged aluminum wheel is consistent with the direction of the force, and its strength, toughness and fatigue strength are significantly better than that of the cast aluminum wheel. At the same time, the performance has good reproducibility, almost every wheel has the same mechanical properties. The typical elongation of forged aluminum wheels is 12%~17%, so it can well absorb the vibration and stress of the road. Usually cast wheels have a strong ability to withstand compressive forces, but their ability to withstand impact, shear and tensile loads is far inferior to that of forged aluminum wheels. Forged wheels have a higher strength-to-weight ratio. In addition, the forged aluminum wheel has no pores on the surface, so it has a good surface treatment ability, not only can ensure uniform coating, firm bonding, but also good color. The biggest disadvantage of forged aluminum wheels is that there are many production processes and the production cost is much higher than that of casting. 6, casting and forging method It is a method in which castings are used as blanks in the forging process and plastically processed. Since forging is used as the final forming process of parts, casting defects can be eliminated, the structure of the product can be improved, and the mechanical properties of the product can be greatly improved compared with castings. At the same time, the advantages of the casting process in forming complex parts can be fully utilized, making the shape complex The forging process of the product is reduced, the material utilization rate is greatly improved, and the production cost is reduced. Using casting forging technology to produce aluminum wheels, its performance can fully reach the mechanical properties of forgings, but the production cost can be reduced by 30% compared with ordinary forgings. At present, since the process was successfully applied to mass production in September 1996, it has been adopted by many Japanese companies with good economic results. At present, only a few companies in the mainland (mainly in Taiwan's Liuhe System) are adopting this process, and the equipment and technology are from Bulgaria. 7, semi-solid die forging process The so-called semi-solid die forging is a process of heating the semi-solid billet to a semi-solid state with about 50% of the volume liquid phase and then forming a die forging to obtain the required close-sized finished parts. This is a process between solid forming and A new process between liquid forming. The advantages of semi-solid die forging: less shrinkage of parts in the die, easy near-final forming, and reduced machining volume; semi-solid die forgings have smooth surface, dense internal structure, fine grains, and higher mechanical properties than die-casting and extrusion Casting parts; forming is not easy to entrap air, macroscopic pores and microscopic porosity are much less than those in conventional castings; forming temperature is low, and mold life is long.
