Automotive wheel bearing′s main role is to bear the weight of the car and the wheel drive provides a wizard. Wheel bearing are both subjected to radial loads and accommodate axial loads, security is a very important piece. Now China-made cars are still using the traditional two separate sets of tapered roller bearings or angular contact ball bearings, which in automobile Assembly when adjusted clearance and preload, fat and many other processes, make more human controlled factors, Assembly difficult, resulting in automobile assembly lines and long, high costs and poor reliability, difficult to adapt to the fierce competition in the market.
In recent years, with the rapid development of previa front drive car, wheel bearing has undergone great changes, especially foreign well known car manufacturers with bearings manufacturer joint research and development, new wheel hub bearing units are emerging at present were emitted into the fourth generation.
NSK rivet forming uranium for third-generation hub bearing in the traditional design of the third-generation hub bearing units, two inner rings are connected with the lock nut firmly together, NSK new structure was developed through the end of the rivet forming axial forces plastic deformation with flange of the inner ring, and the small inner ring pressure. Remove the nuts can help reduce the weight and size of the wheel unit, improving reliability. Driving wheel and a non-driven wheel is applicable. Riveting press forming technology, will improve reliability, even if the connection itself can also provide preload nut loose bearings guarantee.
Riveting press forming using riveting technology, leaning rivet (punch) on the bearing Assembly when a riveting, with flange on the inner ring shaft under pressure from the lower plastic deformation, until the small inner ring is firmly linked together. In the process of forming, deformation of wheel is divided into three phases: the first phase, rivet decline contact with the wheel shaft deformation begins. The second phase, variants of further extensions, wheel shaft radial expansion, contact with the inner chamfer. Finally, phase III, riveting process is complete. In the first phase, rivet head pressure is used in almost all the initial forming of wheel axis and the inner ring load is small and constant. Entering the second stage, rivet head pressure delivered to the inner ring, inner ring load to grow quickly. In the third phase, due to stress of inner ring load increases in size until the rivet head saturation, riveting end, even riveting head lift, inner ring load have not been eliminated, retains some of the load. Residual load can be considered to form the clamping force.
Forging the entire piece of traditional compression, plastic deformation. Therefore, when machining large workpieces, takes a lot of pressure, and when applied to the bearings when variants are often beyond the Centre zone. Under such great pressure, balls and raceways are squeezed in the processing process is likely to damage the bearing, and riveting technology only in the local deformation and with only a small amount of pressure. By controlling the load pressure, such processing for bearing Assembly is suitable. Through operation under overload durability inspection and test of a riveting in the forming edge of fatigue strength and creep resistance. Static strength test to examine the static strength of rivet forming edge turning torque loading test and bearing, bearing stiffness affects the handling and stability of vehicle when turning.
According to the results of testing, development of NSK new rivet forming inner ring self-locking third-generation hub bearing equivalent or even superior to classic wheel bearing locking nut. On the premise of ensuring high reliability, weight and size reduction, to meet the current market demand, reducing vehicle fuel consumption.