The driving conditions of large vehicles are changeable and harsh. In addition to changes in the front axle load caused by load, sideslip and uphill, the front axle also bears variable loads and impact loads. The main components of the automobile front axle are prone to fatigue damage, which affects the safety and reliability of the automobile. Therefore, it is required to select materials with better mechanical properties for automobile front axle parts. To ensure strength.
1. Front axle (front axle)
The front axle is mostly made of No. 35 and No. 40 carbon structural steel or Cr steel. After forging and normalizing, it is quenched and tempered. Mechanical properties of carbon structural steel and alloy structural steel. The front axle of some brands of cars is made of nickel-chromium steel, which has been quenched and tempered and kept for 2 to 3 hours during tempering. After tempering, the front axle is cooled in water or oil. The hardness of the front axle after the heat treatment should be HB229~355. The load of the rear axle will be larger than the load of the front axle, because the front axle needs to be guided. If the front axle load is distributed too much, the steering torque will be too large, so the force required for steering will naturally be greater. It is not conducive to the needs of the driver to drive.
2. Knuckle
The steering knuckles on the front axles of automobiles are mostly made of 40Cr, such as Jiefang Heavy Truck, Dongfeng Special Automobile, Jinan Heavy Duty Truck, etc. The steering knuckles made of gold structural steel are all quenched and tempered. The steering knuckle is processed in three parts: rod, flange and fork.
(1) The machining of the rod is mainly based on the center hole positioning, turning and grinding, and the key to the machining is grinding.
(2) The flange processing is mainly the processing of the brake mounting hole, and its position must be ensured, and the processing efficiency must be taken into account at the same time. In addition, one of the holes is used for positioning the machining fork.
(3) Fork processing is a difficult point in steering knuckle processing. Two pins are used for positioning on one side. The processing is mainly to ensure the coaxiality of the king pin hole of the front axle and the perpendicularity between the king pin hole and the inner end surface. Investment focus and the key to equipment selection.
3.The king pin of the steering knuckle.
The king pin of the steering knuckle bears a strong impact load. Therefore, it requires high surface hardness and wear resistance, and requires a certain degree of toughness in the core. The steering knuckle king pin is mostly made of 40# steel, but also made of cast steel. After carburizing treatment, it can meet the above requirements.
4. Front wheel hub
The front wheels are mostly made of malleable cast iron KT35-10, such as Jiefang CA10B and Beijing BJ212 cars, which have high strength, plasticity and toughness, which can meet the working conditions of automobile front wheels. However, it has poor casting performance, long annealing cycle and low production efficiency. Therefore, some models use ductile cast iron, and some wheels are cast with carbon steel.
5. Knuckle king pin bushing
The steering knuckle king pin bushing has poor working conditions and heavy load. It is mostly made of impact-resistant and wear-resistant bronze, special Kangbak copper-based alloy or iron-based powder metallurgy.
