The editor talks about the heat treatment process of quenching the lead screw using a medium frequency induction heating machine

As a relatively energy-saving and environmentally friendly equipment at present, the medium frequency induction heating machine has been widely used in the quenching heat treatment of machine tools, automobiles and other parts, and its heat treatment effect is quite good. As an important component of machine tools, the screw can convert linear motion into rotational motion, and it can also convert rotational motion into linear motion. Therefore, the requirements for the screw are particularly strict, requiring high hardness, wear resistance and service life. At this time, its heat treatment process becomes increasingly important. Today, the editor will tell you about the heat treatment process of the lead screw using a medium frequency induction heating machine for quenching.

As an important component of machine tools, the screw is of different types depending on the type of machine tool. Although today I want to tell you about the medium frequency heat treatment process of screws, I cannot introduce all types of screws one by one. I will take our more common S7332 thread grinder level 5 precision screw as an example. , introduce the medium frequency heat treatment process.

S7332 thread grinder grade 5 precision screw is made of 9Mn2V steel. During heat treatment, the depth of the hardened layer is generally 5.5~6.0mm, the hardness is ≥56HRC, and the radial circular runout is ≤0.7mm. Its heat treatment process specifications are as follows:

①Quenching and tempering treatment. The main purpose of quenching and tempering treatment is to eliminate free ferrite in the hardened layer on the surface of the workpiece and uniformize the structure, so that the workpiece as a whole can obtain good comprehensive mechanical properties. Under normal circumstances, a medium frequency induction heating machine is used for heating. The quenching heating temperature is 780-820°C, holding for 1 to 2 hours, oil cooling and quenching; and then high-temperature tempering in the temperature range of 500-650°C.

②Medium frequency induction heating surface quenching. The outer circle with a diameter of 6Omm is heated by a medium frequency induction heating machine. The equipment is a 160kW, 2KHz medium frequency induction heating machine and a horizontal quenching machine with three quenching brackets, one at the tail and two in the middle. The process output power is 40kw and the voltage is 400V. Current 120A, medium frequency heating at 850℃, the inner diameter of the inductor used during heating is 80mm, height 20mm, the moving speed of the inductor is 100mm/min, and it is cooled and hardened by tap water; after the screw is surface quenched by medium frequency induction heating, the hardened layer The depth should be 5.5~6.0mm, the hardness should be ≥56HRC, and the radial circular runout should be ≤0.7mm. The radial circular runout of most workpieces is ≤0.7mm.

③Cryogenic treatment and low temperature tempering. After intermediate frequency quenching, a cold treatment of -70℃×2h should be carried out, followed by tempering at 200~240℃ for 6~8h.

The purpose of quenching is to improve the hardness, wear resistance and service life of the workpiece. Therefore, quenching heat treatment is widely used in industry. Although traditional equipment can also perform quenching heat treatment on the screw, it has defects such as uneven heating, oxide layers, and environmental pollution. The newer medium-frequency induction heating machine has solved these defects well and is larger. Improved screw heating efficiency.