Preparatory heat treatment is mainly divided into quenching and tempering and spheroidizing annealing. Under normal circumstances, the quenching and tempering process is selected, but if the total length of the screw is ≤300mm and the nominal diameter is ≥25mm, spheroidizing annealing is selected. Whether it is quenching and tempering or spheroidizing annealing, a medium frequency induction heating machine can be used, and the effect is very good.
(1) Quenching and tempering
1) Quenching. It is carried out using a medium frequency heating induction heating machine. The heating temperature is 840-860°C, and then it is cooled in stages: first, the screw is immersed in oil at 160-200°C for cooling. After cooling to the oil temperature, the screw is placed in a heat sink at 100-140°C. Continue to cool in the oil, and finally transfer the screw to 20-60°C oil to cool.
The hardness of the screw after quenching can reach 60-64HRC, and the quenched structure is mainly cryptocrystalline martensite + 8%-10% (volume fraction) undissolved carbides + a small amount of retained austenite (volume fraction <10%).
2) High temperature tempering. The medium frequency induction heating machine is also used, and the heating temperature is 700-720°C. After inspection, its structure is mainly tempered sorbite, and its hardness reaches 23-35HRC.
(2) Spheroidizing annealing. It is carried out using a medium frequency induction heating machine, the heating temperature is 780-810°C, and it is air-cooled or air-cooled. At this time, the tissue contains granular pearlite.
This article briefly introduces the preparatory heat treatment process of the ball screw, hoping to be helpful to your work. Here, the editor also reminds everyone that when performing process operations, you must be serious and careful to avoid unnecessary defects caused by operating errors.
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GS-ZP-1200
