Process analysis of surface quenching of duplex gears and bevel gears using high-frequency induction heating machine

Technical conditions for quenching heat treatment of duplex gears. A high-frequency induction heating machine is used for surface quenching. The gear surface quenching hardness is 45-55HRC, and the depth of the hardened layer is 2.5-3.5mm. The processing process of the double gear is forging blank - normalizing - rough machining - modulation treatment - half Fine machining - local high frequency induction heating machine quenching on the tooth surface - low temperature tempering - fine machining - finished product.

Heat treatment specifications for double gears: a. The normalizing temperature is 870-890 degrees Celsius, the holding time is about 4 hours, and it is air-cooled after coming out of the furnace. b. Use a salt bath furnace for heating during the modulation process. The quenching heating temperature is 840-860 degrees Celsius and the holding time is 10-20 minutes. The oil is quenched and the high-temperature tempering is carried out in a box-type electric furnace at 600-650 degrees Celsius and the holding time is about 2 hours. After the fire, let it cool in the air. c. Surface quenching by high-frequency induction heating machine. The heating temperature range of high-frequency quenching is 860-900. Polyvinyl alcohol quenching medium is used for quenching and cooling. d. Low-temperature tempering means that the workpiece is subjected to low-temperature tempering in a low-temperature oven at around 180°C, with a holding time of 2 hours, and then comes out of the oven for air cooling.

Heat treatment process analysis: 1. Normalizing is mainly used to eliminate the residual internal stress of forgings, uniformly combine with the structure, and refine the grains, so that the same batch of blanks can obtain uniform hardness to facilitate further cutting. 2. The modulation treatment enables the workpiece to obtain higher comprehensive mechanical properties as a whole, improves the strength of the gear tooth core, so that it can carry larger loads, and can reduce the tendency of deformation caused by subsequent high-frequency quenching. 3. The surface is quenched by a high-frequency induction heating machine to obtain high hardness on the tooth surface, high wear resistance and high compressive stress, which can greatly improve the fatigue strength of the tooth surface. 4. Low-temperature tempering improves the ability of the workpiece to withstand impact loads.

Key points in the implementation of heat treatment technology: 1. Measures to reduce the distortion defects of high-frequency quenching of gears. From the experimental results of dimensional changes of gears after high-frequency induction heating surface quenching, it can be seen that after high-frequency induction heating surface quenching of gears, due to high Frequency induction heating has a relatively fast speed and a short time, and the structural transformation only occurs on the surface of the workpiece, so the overall distortion is relatively small. The distortion of high-frequency induction heating surface quenching is small, and most workpieces can meet the technical requirements and production requirements. For high-precision parts and workpieces with special requirements, the following measures can be taken to reduce the distortion of high-frequency induction quenching.

a. Use lower frequency high-frequency induction heating to reduce distortion.

b. Increase the gap between the sensor and the workpiece appropriately.

c. Control the lower limit of quenching temperature to reduce distortion.