In recent years, the growth rate of forged wheels is faster than that of cast wheels. Although the production cost of the former is higher than that of casting, the former has a higher performance price. At present, the forming of forged wheel hubs at home and abroad can be mainly divided into the following categories:
- Casting and forging method
It is a method of using a casting as a blank in a forging process and plastically processing it. Because forging is the final forming process of the part. Thus casting defects can be eliminated. Improving the microstructure of the product greatly improves the mechanical properties of the product compared to castings. At the same time, the advantages of the casting process in forming complex parts are fully utilized, so that the forging process of products with complex shapes can reduce the utilization rate of materials and greatly improve the production cost.
The performance of aluminum wheels produced by casting and forging technology can fully meet the mechanical properties of forgings, but the production cost can be reduced by 30% compared with ordinary forgings. At present, the process has been adopted by many Japanese companies since it was successfully applied to mass production in September 1996, and the economic effect is good. Although there is some research and application in the casting and forging process in China, there is no report that it is applied to the production of aluminum alloy wheels.China wheels
Classification and characteristics of aluminum alloy wheels
- Semi-solid die forging
The so-called semi-solid die forging is a process in which the semi-solid billet is heated to a semi-solid state with about 50% of the volume liquid phase, and then it is formed by one-time die forging to obtain the required close-sized finished parts. This is a new process between solid-state forming and liquid-forming. Semi-solid die forging has many unique advantages. The shrinkage of the parts in the mold is small, it is easy to form near finalization, and the amount of machining is reduced. Microporosity is much less than in conventional castings, forming temperatures are low, and mold life is long.
- Conventional forging method
Forging is one of the earlier forming processes for aluminum wheel applications. Forged aluminum wheels have the advantages of strength, good corrosion resistance, accurate size, and small processing volume. In general, its weight is only equivalent to 1/2 or less of the same size steel wheel, and the grain flow direction of the forged aluminum wheel is consistent with the direction of the force. Its strength, toughness and fatigue strength are significantly better than those of cast aluminum wheels.
At the same time, the performance is very reproducible. Almost every wheel has the same mechanical properties. The typical elongation of forged aluminum wheel is 12%~17%, so it can absorb the vibration and stress of the road very well. Cast wheels are generally quite capable of withstanding compressive forces, but are far less capable of withstanding shock-shear and tensile loads than forged alloy wheels.