Process analysis of heat treatment of spindle rod by medium frequency induction heating machine

The spindle rod is a slender part with large consumption in textile machinery. Its function is the twisting and winding mechanism of fiber bundles. It is divided into roving spindle rod and fine yarn spindle rod. Its working environment is very harsh. Therefore, the spindle rod is generally required to have good toughness and elasticity, as well as high wear resistance. Many manufacturers use medium frequency induction heating machines to heat treat spindle rods, and the results are very good and meet its working requirements. Today, let’s take a look at the medium-frequency heat treatment process of spindle rods.

1. Heat treatment of the roving frame spindle bar. The heat treatment process of the spindle bar made of T10A is relatively complicated. Considering that the base body has to withstand wear, bending and other effects during the working process, the base body should be normalized to obtain good comprehensive mechanical properties before surface treatment. The heat treatment should be carried out separately according to the different requirements of each part.

In the middle section, a medium frequency induction heating machine is used for induction heating, the temperature is 800-830°C, water cooling is used, and the depth of the hardened layer is about 3mm. The heat treatment length of the ingot tip and tail is short, so flame quenching treatment is considered; finally, the ingot scale is subjected to low-temperature tempering at 130-150°C to stabilize the structure and eliminate residual internal stress. The hardness and deformation after heat treatment meet the technical requirements.

2. Heat treatment of spinning machine spindle bar. The processed spindle rod needs to be heat treated. GCr15 is used for material washing. The technical requirements for heat treatment are: hardness 62-65HRC, microstructure is martensite (level 3) + granular carbide, residual deformation ≤0.01mm, The deformation (flatness) is not greater than 0.15mm, the brittleness meets the requirements, and there is no decarburization or oxidation on the surface. The heat treatment process is as follows:

1) Preheat. Considering that the part is a slender part that is easily deformed and the cross-sectional size changes significantly, preheating heat treatment is required. Preheating can help eliminate the machining stress of the part and reduce the impact on the heat treatment. Two preheatings are used, 300-300 350℃ and 650-700℃, preheating is carried out by medium frequency induction heating machine, which can ensure the consistent temperature of the entire spindle bar (internal and external sections) and reduce the thermal stress of heating to the minimum.

2)Quenching heating and cooling. The austenitizing temperature of GCr15 steel is above 810°C. Considering that the diameter of the spindle rod is not large, a medium frequency induction heating machine is used for heating. The hardness requirement after quenching can be achieved by using a lower heating temperature. Therefore, 830-830- The heating temperature is 850℃, and then quenched into a nitrate salt bath of 140-160℃ for graded quenching for 5-7 minutes. Do not shake. If conditions permit, it is better to keep the temperature in the nitrate salt bath stable (a circulating water cooling device can be designed to ensure that the workpiece The heat released by cooling is consistent with the heat taken away by the cooling water).

3) Low temperature tempering. After quenching and heating, the spindle rod should be subjected to induction tempering heat treatment at 140-160°C using a medium frequency induction heating machine.

The quality of the spindle bar is directly related to the use of textile machinery. Its operating status has an important impact on the quality and output of yarn. Therefore, the quality requirements of the spindle bar are usually relatively high. The above briefly introduces the medium-frequency heat treatment process of spindle bars. After many manufacturers adopt the above process, the quality of the spindle bars produced is good and meets their working requirements.