Do you know the factors that affect gear quenching and annealing distortion? Do you know how to control distortion?

In order to greatly improve the strength, hardness, wear resistance, fatigue strength and toughness of gears to meet the working requirements of gears, it is necessary to perform heat treatment processes such as quenching and annealing on gears. Today, Zhengzhou Gou's will tell you the causes of gear quenching and annealing distortion and some measures to control the distortion.

Causes affecting gear quenching and annealing distortion

1. Excessive cutting volume and improper arrangement of process holes affect the quenching quality of the gear, which in turn affects the quality and service life of the equipment.

2. The influence of materials on gear distortion is mainly reflected in the influence of materials on quenching distortion such as uneven grain size, severe banding structure, and hardenability bandwidth.

3. Asymmetric forging streamlines and uneven cooling after forging all affect the quenching of gears.

4. Uneven heating, unreasonable fixture design, improper selection of cooling medium and cooling specifications, all of which will produce distortion in gear quenching.

5. The heating temperature is too high or too low, and the cooling is uneven, which has a great impact on the quenching effect of the gear.

6. Poor shape symmetry, cross-sectional uniformity, and poor spoke stiffness all affect the heat treatment processes such as quenching and annealing of gears.

General measures to control gear heat treatment distortion:

1. Reasonable gear structure design.

The structural design principles for reducing gear heat treatment distortion are roughly as follows:

a. Enlarge the rounded corners b. Dig grooves and drill holes to achieve balanced cooling. c. The shape should be as symmetrical as possible d. Reasonably arrange the keyway e. Change the supporting bottom surface.

2. Control the accuracy of the gear spline hole. Methods include: extruding key width and grinding internal control after heat treatment, extruding spline holes after heat treatment, pre-expanding holes at the end with larger shrinkage before heat treatment, etc.

3. Properly use quenching fixtures and clamping methods.

4. Adjust the gear processing size before heat treatment, master the heat treatment distortion law, and adjust the gear processing size before heat treatment: to compensate for the heat treatment distortion, this is a common method for mass production of gears. 50 pieces of gears are commonly used in production for cold processing and heat treatment under given conditions. After dimensional measurement of this batch of gears before and after heat treatment, and statistical processing of the data, the distortion trend is obtained, and then the position of the tolerance zone is determined. Obviously, the adjustment of processing dimensions is based on stable production.

5. Method to reduce the heat treatment distortion of bevel gears. The carburizing and quenching distortion of bevel gears is mainly made by transverse pressure quenching during production. The distortion of press-hardened gears sometimes still cannot be effectively controlled.