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1, low pressure casting
Low pressure casting is to put the mold on a closed furnace above, below the cavity with a tube (called liquid riser) and the furnace in the metal liquid. If the air with pressure is added to the metal surface in the furnace, the metal liquid flows into the cavity from the liquid rising pipe. After the solidification of molten metal, the furnace in the compressed air is released, solidification of metal from the lift tube flow back to the furnace. Controlling the pressure and velocity of the air in the furnace can control the velocity and pressure of the metal flowing into the cavity, and can make the metal solidification under pressure. This process is characterized by casting in the pressure of crystallization, dense structure, good mechanical properties, high metal utilization.
Low pressure casting process is currently in mainland China is already quite mature, suitable for a small production of humanized management, has been all OEMs recognize but the China aluminum alloy wheel manufacturing technology mainstream, and products are mainly exported to OEM and overseas retail markets.
The manufacturing of low pressure casting aluminum alloy wheel hub, as spokes is finally cooled and solidified, so special shape wheel spokes prone to shrinkage and other quality problems, and rim due in part to the first crystallization, the intensity is better.
2, squeeze casting method
Squeeze casting also known as liquid die forging, is a set of casting and forging characteristics in one of the new process, the process is a certain amount of liquid metal directly poured into the open metal type, punch through to a certain pressure on the liquid metal, the filling, forming and solidification, and in the crystallization process to produce a certain amount of plastic deformation. Squeeze casting filling smoothly, no turbulence and do not pack the gas volume, direct metal under pressure crystallization solidification, so casting will not produce pores, shrinkage hole and shrinkage porosity in casting defects and dense microstructure, grain refinement, mechanical properties than the low-pressure casting piece. Products are both forging close to the excellent mechanical properties, and casting a precision forming of high efficiency, high precision, and the investment is greatly lower than low pressure casting. The disadvantage is the liquid forging products and traditional forging products, need to complete the modeling of milling wheel.
Squeeze casting process production with Japan has been a considerable part of the automobile aluminum wheel hub, Toyota has a dozen automatic extrusion casting equipment, each device not to minutes a piece of aluminum wheel production, from pouring molten metal to the casting is taken out the whole process is controlled by the computer to, degree of automation is very high. Domestic construction of a modern squeeze casting aluminum alloy wheel plant in Guangdong, has produced a variety of specifications and models of automotive aluminum wheels, the quality of the product has reached the advanced level of similar products abroad. At present, all the countries in the world regard squeeze casting as one of the direction of the production of automobile aluminum wheel hub.
3, casting spinning
Two kinds of technology of casting and rotating, "low pressure casting, spinning" and "gravity casting and spinning". The forming process of aluminum wheel car prices have Korean full use of low pressure casting + spinning "trend, other cars are also part of this process of product demand, the technology is the mainstream technology of rotary casting process, OEM products do most of the companies are using this process; at the same time, there are few to do overseas retail enterprises adopt" gravity casting process + spinning ", this process is theoretically feasible, it really put the gravity casting and spinning process of two kinds of strengths together, the product quality has been improved, but because the blank is the production of gravity casting process, so the economy of the the process is not very good, the production cost is very high. Anyway, spin cast products, because the spoke is cast out. It has casting process for production of products with the same advantages and disadvantages, and rim portion is spinning out, so good air tightness. Casting rotary products can theoretically lose weight, but the effect is not obvious in practical application.
4, conventional forging
Forging is one of the earliest forming processes for aluminum wheels. Forged aluminum wheels have the advantages of high strength, good corrosion resistance, accurate size, small size and other advantages, in general, the weight is equivalent to the same size of the steel wheel 1/2 or lower. The grain flow direction and the force direction of the forging aluminum wheel hub are consistent, and the strength, toughness and fatigue strength are significantly better than that of the cast aluminum wheel. At the same time, the performance has a very good reproducibility, almost every wheel hub has the same mechanical properties. The typical elongation of the forged aluminum wheel is 12%~17%, which can absorb the vibration and stress of the road very well. Generally, the casting wheel hub has a very strong capacity to withstand the compressive force, but the ability to withstand impact, shear and tensile load is far less than that of forged aluminum wheels. Forged wheels have a higher strength to weight ratio. In addition, the forged aluminum wheel hub surface without pores, and therefore has a good surface treatment capacity, not only to ensure that the coating is uniform, solid, but also good color. The biggest disadvantage of forging aluminum wheels is the production process, production cost is much higher than the casting.