& nbsp; The wheel hub is one of the most important safety components in automobiles, divided into steel and aluminum wheels. The wheel hub bears the pressure of the vehicle and the load, is subjected to the dynamic torque of the vehicle during starting and braking, and is also subjected to irregular alternating forces generated by dynamic loads from different directions such as turning, bumpy roads, and road obstacles during driving. The quality and reliability of the wheel hub are not only related to the safety of the vehicle and its personnel and materials, but also affect the smoothness, handling, comfort, and other performance of the vehicle during driving. This requires good dynamic balance, high fatigue strength, good stiffness and elasticity, high size and shape accuracy, and light weight of the wheel hub. Aluminum wheels meet the above requirements with their excellent comprehensive performance, and perform outstandingly in safety, comfort, and lightweight aspects, It has won the favor of the market and is gradually replacing steel wheels as the best choice& nbsp;& nbsp; & nbsp; Manufacturing Equipment, Technology, and Trends of Aluminum Wheel Hub& nbsp; & nbsp; The main production process for automotive aluminum wheels is: melting→ Refining→ Material Inspection→ Low pressure casting→ X-ray inspection→ Heat treatment→ Mechanical processing→ Dynamic balance inspection→ Air tightness inspection→ Painting& nbsp; 1. Melting& nbsp; & nbsp; The melting equipment for wheel hub aluminum alloy is divided into tower furnace, induction furnace, tilting converter, and fixed furnace according to the furnace type, and is divided into diesel, natural gas, coal to gas, and electric energy according to the energy form. Tower furnace has fast melting speed, low burning loss, and low energy consumption; The induction furnace has fast melting speed, uniform alloy composition, and good production environment; The tilting converter can be used as a batching or insulation furnace, ensuring safe use and easy maintenance; The fixed furnace can be used for ingredients or insulation, and is easy to use and maintain; High fuel calorific value, high melting efficiency, convenient use and maintenance, good gas production environment, cleanliness, and convenient use and maintenance; Coal to gas is economical and affordable, with easy control of electricity and a good production environment. The tower type rapid melting furnace with oil or gas is preferred, and the aluminum chip melting chamber is more convenient to use, making it the main equipment of choice& nbsp;& nbsp; & nbsp; The key to melting equipment lies in the control of furnace temperature. Due to the need for on-site manufacturing, domestic production is preferred, and construction and maintenance are convenient. Due to the strict requirement of Fe (iron) content (≤ 0.15%) for the aluminum alloy of the wheel hub, the furnace lining must be made of non-metallic materials. High grade pure aluminum should be used for batching, and the proportion of returning materials should be strictly controlled& nbsp;& nbsp; & nbsp; A few domestic manufacturers have purchased liquid aluminum alloys for production and directly transported them to the production site. The process of directly casting aluminum wheels using liquid aluminum alloys greatly reduces the burning loss of raw materials during melting and energy consumption during secondary melting, which is a new direction for the development of aluminum wheel manufacturing technology. Casting production site2. Refining& nbsp; & nbsp; The refining methods of aluminum liquid include gas method and flux method, and the processing methods include pipeline method, bell jar pressing method, refining machine, etc. The equipment for refining aluminum liquid is divided into fixed, mobile, lifting, and simple through tube types according to the form, and is divided into single gas, double gas, and gas with flux according to the refining medium. Fixed equipment runs smoothly, reliably, and has good refining effects. Mobile equipment is flexible and convenient to use, while lifting equipment is convenient to use, and simple to use through pipe type is simple to use. In order to improve refining efficiency and avoid environmental pollution, the use of a dual gas fixed refining machine is the most effective and the main equipment. The key to this refining equipment lies in the technical level of the control system and the reliability of the equipment, which can be imported or domestically produced& nbsp;& nbsp; & nbsp; The use of rod-shaped AlTiB and AlSr alloys is preferred for refinement and modification, and the use of pollution-free fluxes has become a development direction for refinement and modification treatment; The use of thermal analysis and density equivalent instruments for furnace analysis of refining, refining, and modification effects is a new trend in the development of rapid analysis technology for aluminum liquid& nbsp; 3. Casting& nbsp; & nbsp; The forming process of automotive aluminum wheels is divided into metal mold gravity casting, low-pressure casting, squeezing 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 has become the mainstream process internationally in recent years. In the domestic automobile aluminum wheel hub forming technology, over 85% of the total production is produced using low-pressure casting technology, while the rest is produced using metal mold gravity casting, extrusion casting, and forging technology& nbsp;& nbsp; & nbsp; The key to low-pressure casting machines lies in the control accuracy of furnace pressure and the reliability of equipment. Domestic manufacturers choose low-pressure casting machines with insulation furnaces as the main melting pool type, and the mold is mainly in the form of four open molds. The mold cooling is a combination of water and air. Due to the development of aluminum wheels towards large-scale, the equipment must have good rigidity and sufficient force for mold opening and closing& nbsp; 4. X-ray inspection& nbsp; & nbsp; The X-ray inspection equipment for aluminum wheel hubs adopts an industrial real-time imaging system. The X-ray tube used is an imported 160KVA metal tube, which can penetrate aluminum alloys above 50mm and clearly observe defects such as shrinkage and pinholes. The recognition of defects can be achieved through manual recognition and automatic program recognition, as well as image processing and storage functions. This equipment can be imported and domestically produced, but there is still a significant gap in the reliability and development of automatic recognition programs between domestic equipment and foreign equipment, which cannot be compared. Therefore, imported X-ray inspection equipment with automatic recognition function is the best choice for this type of equipment, and it is the main equipment. Considering the degree of automation in production, there should be a conveyor system at the inlet and outlet of the equipment, which can automatically separate qualified and unqualified products. Equipment with production statistics software functions is a trend in the industry's application and development& nbsp; 5. Heat treatment& nbsp; & nbsp; The heat treatment process for aluminum wheels is solid melting and aging treatment (T6 treatment), which requires furnace temperature uniformity& plusmn; 5℃。 Heat treatment equipment is divided into periodic furnace and continuous furnace according to furnace type, and natural gas and electric energy according to energy form. The placement of wheel hubs in the furnace often uses material racks, and the products are placed separately to prevent wheel hub deformation. The continuous heat treatment furnace is divided into roller bar type, hanging basket type, push plate type, and stepper type according to the transmission mode. Among them, continuous heat treatment furnaces have good temperature uniformity (± 3 ℃), good product quality, high production efficiency, and energy conservation, making them the main equipment for mass production. Gas hanging basket and basket free continuous heat treatment furnaces are the development direction of this type of equipment. A cycle furnace can be used for small batch intermittent production. Due to the large production capacity of continuous heat treatment furnaces, the reliability and control level of equipment are very important. In order to ensure the traceability of the process, temperature recorders should be equipped. To facilitate operation and improve the utilization rate of workshop area, the heat treatment production line is preferably arranged in a U-shaped or double-layer layout. The equipment should be made domestically, which is convenient for construction and maintenance& nbsp; 6. Mechanical processing& nbsp; & nbsp; In terms of the processing of aluminum wheels, domestic manufacturers generally use imported or domestically produced single axis vertical or horizontal CNC machines, high-precision CNC machining units, cutting fluid cooling, and the traditional processing sequence is to remove the riser outside the line, and then position the workpiece with the outer circle first turning and then drilling. For aluminum wheels, the processing accuracy is sufficient. In order to reduce machining processes, improve production efficiency and machining accuracy, and meet environmental requirements, the new technology adopts high-precision CNC dual axis vertical machining units, dry machining without cutting fluid&flash& mdash; The micro lubrication air cooling method for cutting tools, with a processing sequence of drilling first and then turning, is positioned based on product bolt holes, with a turning speed of at least 2500r/min, and the removal of the riser is completed on the drilling machine, reducing the drilling riser process, which is a new trend in aluminum wheel hub processing technology. Machining production site7. Air tightness inspection& nbsp; & nbsp; The methods for inspecting the airtightness of aluminum wheels include hydraulic test and helium mass spectrometry leak test. The hydraulic test is conducted on≥ Maintain pressure for 30 seconds at a pressure of 0.4 MPa, and visually observe the bubbles when the aluminum wheel hub leaks in water to check the air leakage of the aluminum wheel hub. This is the air tightness inspection method chosen by the vast majority of domestic manufacturers, with domestically produced equipment being the main equipment. The new airtightness inspection method is to use helium mass spectrometry leak test, which utilizes the principle of helium mass spectrometry analysis and can quickly and automatically detect helium leakage (leak rate≤ 1× 10-6 Pa? Cm3/s). Considering the degree of automation in production, there should be a conveyor material system at the inlet and outlet of the equipment's workpiece, and qualified and unqualified products can be automatically separated. This technology is a new trend in airtightness inspection technology, Imported equipment is preferred. 8. Painting& nbsp; & nbsp; The appearance styles of aluminum wheels include coating, transparent paint on the bright surface of the spoke car, polished transparent paint, electroplating, etc. The colors of coating include silver gray, sports silver, fine silver, smoke gray, black, etc. Due to the significant impact of electroplating technology on environmental protection, its application is gradually decreasing, and painting is the dominant process& nbsp;& nbsp; & nbsp; Painting is the final process in the production of aluminum wheels, with the aim of improving the corrosion resistance and aesthetics of aluminum wheels. In order to ensure the quality of painting, the production site is required to be clean and dust-free. The methods of coating include manual spraying and automatic spraying. The thickness and quality of the manually sprayed coating are difficult to control. Automatic spraying can control the accuracy of the coating thickness to 10mm and evenly, and the thickness can be adjusted according to customer requirements; There are electrostatic spray guns and air spray guns, which are only suitable for spraying paint; The process flow of painting is: pre-treatment→ Spray primer→ Spray paint→ Spray transparent powder, special ones also have pre-treatment→ Spray paint→ Spray transparent powder or pre-treatment→ Spray transparent powder, but the corrosion resistance of the latter two process coatings is not as good as the former. The advanced technology and equipment currently used are pre-treatment→ Spray primer→ Spray paint→ An automatic production line for spraying transparent powder& nbsp;& nbsp; & nbsp; The advanced automatic coating production line consists of surface pretreatment, drying, electrostatic powder spraying, painting, curing, etc. The transmission system places the aluminum wheels horizontally in a ground chain, and the aluminum wheels can rotate into good ones. It is equipped with a handling robot, powder recovery system, powder replacement system, and wastewater treatment device. Among the automated coating process equipment used, electrostatic spray guns and high-speed electrostatic rotary cup spray gun technology (with a speed of over 20000r/min), environmentally friendly chromium free pre-treatment technology, powder spraying technology, and environmentally friendly water-based paint technology have been selected. Due to the high production efficiency, coating saving, and good environmental protection of the production line, it is a new trend in the development of aluminum wheel hub coating technology. Among them, imported products are preferred for spray guns, treatment agents, powders, and water-based paint, Currently, only a few manufacturers are using it.   & nbsp; Painting production siteConclusion& nbsp; Automotive aluminum wheels are developing towards large diameter, lightweight, high-strength, and aesthetically pleasing features. The mainstream automotive market is dominated by 15-18 inch (1 inch=25.4mm) wheels, with 16 inch wheels accounting for the largest market share. The main development trends of aluminum wheel hub manufacturing technology are automation, intelligence, economy, energy conservation, and environmental protection. Specific measures include: direct delivery of liquid aluminum alloy to the production site, pollution-free refining of aluminum liquid, thermal analysis of aluminum liquid, automatic X-ray inspection, helium automatic leak testing, dry mechanical processing, high-speed electrostatic cup spray gun, chromium free treatment, powder spraying and water-based paint, and other new technologies and processes. At present, the annual production capacity of 65 million pieces has made China a major producer of aluminum wheels in the world. The automotive aluminum wheel hub industry in China is striving to become a strong country in the production of aluminum wheels as soon as possible.