How to guarantee the strength and toughness of the trailer axle?

When buying a trailer axle, some owners like to go to the axle factory to visit the field and see the scale and production process of the manufacturer, so as to judge the production level and quality of the manufacturer. For the trailer axle, its main role is to carry the weight of the body, so the stiffness and toughness requirements are higher.

So, how does the axle factory ensure the rigidity or toughness of the axle?

This also relies on the three major production processes of the axle plant: hot rolling, tempering heat treatment, and medium-frequency strengthening treatment. Whether these three production processes meet the standards directly reflects the production level of the axle plant. Next, DARO Axle will explain the role of these three processes in detail.

1, hot spin rolling

Hot spin rolling is a key process in the production of trailer axle rod, and it is also the first process after raw materials are cut. After hot rolling, the shaft head is initially formed, which provides a certain basis for the subsequent series of roughing and finishing.

However, the main function of hot spinning is to improve the internal mechanical properties of seamless steel pipes.

As we all know, the material of the raw material has a very significant impact on the organization and comprehensive mechanical properties of the finished trailer axle, if the metallurgical quality of the raw material is poor, there will be a large number of non-metallic impurities, when it exists in continuous, aggregated, network, series, it is easy to cause the continuity of the local matrix metal, plasticity and strength will be reduced, and the metal will be reduced. In the subsequent processing or use, it is easy to form microscopic cracks or internal acute angles, and eventually lead to stress concentration and fatigue failure.

The maximum temperature of hot rolling can be close to 1300℃, which can crush the acicular preeutectoid ferrite inside the raw material grains, so that the Weil structure inside the material can be significantly improved and corrected, greatly reduce the molding resistance and deformation energy consumption of the raw material, reduce or eliminate casting defects, and provide a solid foundation for the rigidity of the finished axle.

2, tempering heat treatment

The heat conditioning here mainly refers to quenching + tempering, which is also a common treatment process in the steel processing process.

The DARO trailer axle uses a fully automatic quenching machine, and its temperature is generally set at about 865 ° C, which greatly reduces manual intervention and has higher operating accuracy.

During the heating process, the austenite content inside the steel will gradually increase, and then through water cooling, austenite will be converted to martensite, and martensite is the product of the quenching process, because of its high carbon content, it is very hard in nature, and has a very key role in the stiffness and strength of the axle.

However, the stability of the martensite that has just been converted is relatively poor, and there is a part of the residual austenite that has not been completely converted, which will be transformed once it meets the appropriate conditions, causing the deformation of the axle and changing the processing size. In addition, after quenching, there is generally a large residual thermal stress and organizational stress inside the axle, which often likes to be distributed in the corners or some holes, and if it is not eliminated in time, it is also easy to lead to deformation or cracking of the axle.

Therefore, although the stiffness and strength of the quenched axle are improved, the toughness is relatively poor, at this time, it is necessary to carry out high temperature tempering in time. The tempering process temperature of the DARO trailer axle is generally set at about 480 ° C, which can fully reduce or eliminate the quenching internal stress and improve the ductility and toughness of the shaft.

In this way, the strength and toughness of the axle can achieve "double standards".

3, medium frequency induction processing

Although the axle after quenching and tempering heat treatment can already meet the load requirements in subsequent use, the medium frequency induction treatment is still not less.

Medium frequency induction treatment is also a strengthening process, mainly for the shaft head position. The axle head is used to connect key parts such as bearings and hubs. The performance of the axle head is crucial to ensure the stable performance output of each part under high-speed operation.

Medium frequency induction treatment adopts non-contact heat treatment strengthening technology, through the input of medium frequency current to form an alternating electromagnetic field, through the induction coil to transmit alternating current to the shaft head, the formation of the same frequency induction electrodynamic force, heating rapidly, can reach 800-1000℃ in a few seconds, the depth of heat penetration, internal and external temperature difference is small, uniform temperature field, It can not only enhance the strength and toughness of the axle to a greater extent, but also play a positive role in its magnetism, corrosion resistance and oxidation resistance, improve its safety and stability, and extend the service life of the axle body.

The axle factory that can do the above three processes can basically rest assured of the strength and toughness of its products. It is worth mentioning that in addition to the above three processes, DARO trailer axle has also opened a special fatigue test workshop to spot check the finished product, only through millions of fatigue tests and data qualified, in order to successfully ship the factory, which is also a guarantee for the strength, toughness and fatigue resistance of the axle.

Of course, to determine the quality of the axle and the production strength of the manufacturer, but also a comprehensive consideration of processing accuracy, parts quality, assembly technology, personnel quality and other multiple factors, but the strength and toughness of the standard, you can to a large extent to ensure the performance of the finished product. The owner can pay more attention when investigating the axle factory.