The process of steering knuckle kingpin quenching with rectangular inductor by medium frequency induction heating machine

The steering knuckle kingpin is one of the important parts of the automobile's front axle steering structure and is a security component. Over the years. We generally use medium frequency induction heating machines for quenching heat treatment. However, there are some defects. The newly developed rectangular inductor developed by Zhengzhou Gou's solves these defects. Today, we will briefly talk about the heat treatment process of medium frequency induction heating machine using rectangular inductor for quenching.

We have explored previous problems and found in a large number of experiments that applying rectangular sensors can achieve better results. At the same time, a larger-power medium-frequency induction heating machine is used, which has significant economic benefits for energy saving.

The development and production of the rectangular inductor has allowed the old process of quenching the kingpin in stages to be replaced by a new process of heating and quenching the entire body. During quenching, the inductor does not move and the parts rotate at a fixed speed, realizing two-stage quenching areas and a central quenching area. Adjacent areas are heated, quenched and tempered at the same time, thereby completing the kingpin quenching process in one go.

The effective conductor of the kingpin rectangular inductor is a complete rectangular structure. Due to the high hardness requirements of the parts, the effective conductors are not equipped with magnets to enhance cooling capacity. Its effective conductor is a loop composed of two axial copper tubes, two small half rings and one half ring. A main water spray ring and two auxiliary water spray rings made of cloth-laminated bakelite material are installed in front and behind the effective conductor. Spray the water ring so that the parts can be spray-cooled immediately after heating. The sensor has the advantages of simple structure, easy manufacturing, and convenient maintenance.

Through calculation, it is known that the surface area of the effective conductor is 61cm2, and the surface area of the required heating part is 234cm2. At a certain output power, the specific power on the effective conductor is 3 times the specific power on the part. Since a large specific power is concentrated on the effective conductor, the main pin can be quickly heated and quenched.

The rectangular inductor uses a transverse magnetic field to heat the parts. The magnetic field formed by the longitudinal current on the effective conductor better controls the direction of the current, so that the current intensity is the same along the entire length of the effective conductor, which affects the surface of the part. The heating belt is heated repeatedly, that is, pulse heating is achieved. The heating layer on each part of the part is also uniform and reaches the temperature required for quenching at the same time. During cooling, the surface of the part is spray-cooled in sequence, so that each part is cooled to the martensite transformation temperature basically at the same time, which is beneficial to improving the stability of martensite. Therefore, the quenching quality is improved.

After using the new process, no quenching cracks were found, which shows that the king pin can effectively avoid the occurrence of quenching cracks after being heated and quenched by the rectangular inductor. The heating status is easy to observe, control and adjust, and the direct measurement of temperature can also be easily carried out. The heating and quenching of parts was also completed from two times to one, avoiding repeated operations. The output per hour was also increased to 90 pieces, which improved production efficiency and reduced labor intensity. The heating time of a single piece is also shortened from the original 15s to 7s.

The adjacent distance between the two hardened areas is only 18mm. According to the data, when using an 8000Hz medium frequency induction heating machine, the minimum distance between the two hardened areas is 20mm. The tensile stress in the adjacent areas is too large. Under the combined effects of tissue stress and thermal stress , forming a very dangerous stress state in the slotted part. When the peak tensile stress reaches or exceeds the fracture strength of the material, it can induce cracks here and reduce the fatigue strength. This is the reason why the kingpin cracks after quenching using the original process. main factors. This situation can be better avoided by adopting the method of overall one-time quenching.

Zhengzhou Gou's is a manufacturer specializing in the production of medium frequency induction heating machines. We have been engaged in the induction heating industry for 15 years. We have a good understanding of equipment manufacturing, sensor design and workpiece heat treatment. If you want to know more about workpiece heat treatment, please call us.