Application of X-rays in Defect Detection of Automotive Wheel Hubs
Wheel hub is one of the important safety components in automotive parts, which is divided into steel wheel hub and aluminum wheel hub. The wheel hub bears the pressure of the car itself and the weight of the carrier, and is affected by dynamic torque during starting and braking, as well as irregular alternating stresses generated by dynamic loads in different directions, such as turning, uneven road surfaces, and road obstacle impacts.
The quality and reliability of wheel hubs not only affect the safety of vehicles and passengers, but also affect the stability, operability, and comfort of vehicles during driving. Wheel hubs require good dynamic balance and high fatigue strength, while aluminum wheels have good comprehensive performance in terms of stiffness, elasticity, size, shape, weight, etc., which can meet the above requirements. They have excellent performance in safety, comfort, and lightness, winning the favor of the market and gradually replacing steel wheels as the most preferred choice.
The main production process of automotive aluminum wheels is: melting → refining → material inspection → low-pressure casting → X-ray inspection → heat treatment → mechanical processing → dynamic balance inspection → airtightness inspection → coating.
The forming process of casting aluminum wheels for automobiles is divided into metal gravity casting, low-pressure casting, extrusion casting, forging process, and spinning process. Low pressure casting has the characteristics of high production efficiency, dense casting structure, and high degree of automation, which can meet the needs of automotive aluminum wheels and have become the mainstream process internationally in recent years
In the domestic automotive aluminum wheel hub forming technology, low-pressure casting technology accounts for more than 85% of the total output, while the rest is produced using metal mold gravity casting, extrusion casting, and forging technology. The key to a low-pressure casting machine lies in the precision of furnace pressure control and the reliability of the equipment. The low-pressure casting machines selected by domestic manufacturers mainly use insulation furnaces as the melting pool, and the molds mainly adopt four types of mold opening forms. Mold cooling is a combination of water vapor, and because aluminum wheels are developing in a large direction, the rigidity of the equipment must be very good, and there must be sufficient power to open and close the mold.
However, regardless of the casting process, due to various environmental factors during the manufacturing process, castings will inevitably have certain defects to varying degrees. Common defects in castings include porosity, looseness, and slag inclusion. Therefore, X-ray non-destructive testing is required during the wheel hub manufacturing process to ensure the quality of the castings.
The aluminum wheel X-ray inspection equipment adopts an industrial real-time imaging system, which can penetrate aluminum alloys of different thicknesses using X-ray tubes of different powers. After the inspection is completed, defects such as porosity, looseness, and slag inclusion in the castings can be clearly observed in the inspection image.
The recognition of casting defects includes manual recognition and software automatic recognition, and has image processing and storage functions. The X-ray wheel hub inspection equipment is equipped with defect automatic recognition software, which automatically identifies and screens out products with problems, and marks the location and size of defects. Considering the current level of automation in wheel hub production, online X-ray wheel hub inspection equipment has been widely used. The equipment is equipped with a conveyor channel system at the inlet and outlet, which automatically judges and separates qualified and unqualified products. X-ray wheel hub inspection equipment is an indispensable quality inspection equipment for wheel hub manufacturers, reducing manual intervention and improving inspection efficiency
