What are the defects caused by the quenching of the guide rail by the medium frequency induction heating power supply?

When it comes to guide rails, we all know that they are an important part of the machine tool and play a very important role in the overall operation of the machine tool. They generate huge friction during the working process, so the guide rails generally require high hardness and wear resistance. and service life. We usually use medium frequency induction heating power for the quenching heat treatment of guide rails. However, during the heat treatment process, there will be many influences and some quenching defects will occur. Today, we will focus on the defects of medium frequency induction quenching of guide rails.

(1) The deformation is too large. After the cast iron guide rail is quenched by a medium frequency induction heating power supply, the hardened layer of the guide rail has a certain depth. If the deformation is too large, the depth of the hardened layer will be too thin and the hardness will be reduced after grinding, which will reduce the wear resistance of the guide rail. For this reason, the problem of preventing deformation must be considered during the entire heat treatment and machining process. During the heating process of each process, the workpiece should be in a free vertical state. Before the final heat treatment, aging treatment for stress relief should be carried out to prevent deformation. The cold working stress is reflected in the final heat treatment process to increase the amount of deformation. Unless it is unavoidable, it is generally better not to use pressure straightening. Special attention should be paid to the selection of process parameters and operation methods to minimize the amount of deformation , such as lowering the heating temperature, using a milder cooling medium, and cooling all surfaces of the parts evenly, etc.

(2) Poor metallographic structure. After induction heating, there will be white bright layer or network (vein-like) nitrides on the surface of the workpiece, severe band-like carbides in the alloy tool steel, etc., which will cause grinding cracks during guide rail grinding.

(3) Dimensional stability is poor. The guide rails that have been treated by medium frequency induction heat treatment are all in a metastable quenching-tempering state, and all have varying amounts of retained austenite. After staying at room temperature for a long time, changes in scale, recovery of alignment stress and mechanical stress will occur. The processing stress changes the original stress balance state into a new uneven state, and a new equilibrium state is reached through stress relaxation and trace plastic deformation. This is a common dimensional instability phenomenon of precision parts. In order to further transform the retained austenite and eliminate the impact of grinding stress on accuracy as much as possible, cold treatment or long-term tempering should be carried out depending on the guide rail material. This process should be placed in the middle of the two grinding processes. .

As the important working surface of the machine tool, the guide rail is the basis for the working accuracy of the machine tool, and its heat treatment is very important. Today, this article briefly analyzes the causes of defects caused by quenching guide rails using medium-frequency induction power, and briefly introduces some preventive measures. I hope it will be helpful to everyone's work.