First, the material of the main automobile castings

¡¡¡¡The materials used for automobile castings are mainly cast iron and aluminum alloy, and a small amount of magnesium alloy, copper alloy, and zinc alloy. Magnesium alloy is considered to be a promising material due to its low density and meets the needs of lightweight cars. However, due to its low strength and relatively low production cost, it will take time for it to be widely used. Currently, it is mainly used to make parts such as steering wheels, dashboards, pedals, and seats.

¡¡¡¡ Aluminum alloy castings were originally only used for a few parts such as pistons. With the increasing requirements for the lightweight of cars, the development of aluminum castings has been widely used in car cylinder heads, intake pipes, gearbox housings and other parts, and the application of car cylinders is also increasing. The casting workshop of Dongfeng Honda Engine Company with an annual output of 50,000 aluminum cylinder blocks was put into operation in 2001, and Shenyang is also building a large-scale automobile aluminum cylinder casting plant. With the development of motorcycles and automobiles, the output of aluminum castings in Chongqing has increased astonishingly. Now there are many enterprises with an annual output of 50,000 tons of die castings and 10,000 to 30,000 tons of gravity casting aluminum castings. The total output has exceeded 20 Million tons. The production methods of aluminum castings also include gravity casting, die casting, low pressure casting and other methods.
¡¡¡¡ Cast iron is still the main material for automobile castings, especially for medium and heavy commercial vehicles. Cast iron still accounts for the vast majority of castings. Light commercial vehicles also use cast iron to reduce costs. Gray cast iron, ductile iron, vermicular iron and chilled cast iron in cast iron are used in automobile castings with different requirements.

Second, the heat treatment process control of aluminum alloy wheels

¡¡¡¡ 1. Quality control of heat treatment
¡¡¡¡ Heat treatment quality control is to control the factors that affect the heat treatment quality of aluminum alloy wheels during the entire heat treatment process. All employees participate in the heat treatment quality work in the whole process, implement the active control mode that focuses on prevention, combining prevention and inspection, and transfer the passive check of the final inspection to the quality control during the production process to eliminate the heat treatment defects of the aluminum alloy wheel. In the process of quality formation, the heat treatment quality of the product, the product life and the service life are stabilized. Quality control can grasp the quality dynamics at any time, eliminate quality accidents in the bud, reduce and avoid quality problems, thereby reducing manpower, material resources and time waste in production and inspection, and create heat treatment quality and benefits. The key points of quality control are: employee quality control, operating environment control, equipment and instrument control, process control, quality inspection, product defects and their control, etc.

¡¡¡¡2, process control
¡¡¡¡ When the equipment is in good working condition, the cast aluminum wheel hub will complete the heat treatment process under stable process conditions. However, when an abnormal condition of the equipment causes process fluctuations, it is far from enough to simply require the operator to find out in time. For the stability of process control, this requires the improvement of various alarms from the equipment control aspect, such as over temperature (low temperature) alarm, fan speed alarm, heating system (power failure, circuit break, quenching alarm, drive stop alarm, quenching transfer time) Overtime alarms, water temperature and water level alarms, etc. These alarms can be directly received by the on-site operator in the form of sound and light, so that timely countermeasures can be taken to restore the normal operation of the equipment in a short time.

For each aluminum casting wheel to complete the heat treatment process normally, the operator should perform process and equipment inspections at the time interval. The detailed product specifications, production batch number, quantity, process and operator should be recorded on the production quality record sheet. Name, this record is used as the original data for heat treatment process control, and should be organized and archived for traceability. In order to track the product performance, the work site must establish a product performance fluctuation diagram of each device, and through statistical process control, factors that cause abnormal performance fluctuations can be discovered in time.
¡¡¡¡In order to stabilize the process, the furnace temperature is checked regularly. For continuous production furnaces, the furnace temperature tracker should be used to detect the process conditions throughout the process. When there is a difference between the actual temperature measurement curve and the process curve, the equipment is adjusted accordingly, and finally the fluctuation range of the temperature measurement curve is within the range set by the process.