Two forms of heat treatment for external tooth parts using medium frequency and high frequency induction heating equipment

Before talking about the two methods of heat treatment of external gear parts using medium-frequency and high-frequency induction heating equipment, let’s first talk about the crank connecting rod mechanism, which is the power transmission system in the reciprocating internal combustion engine. The crank connecting rod mechanism is the main moving part of the engine to realize the working cycle and complete energy conversion. In the power stroke, the heat energy generated by fuel combustion causes the piston to reciprocate, converting the crankshaft rotation into mechanical energy to output power; in other strokes, it relies on the rotational inertia of the crank and flywheel to drive the piston up and down through the connecting rod. , to create conditions for the next work. The flywheel is a disc with a large moment of inertia. There is a ring gear pressed on the outer edge, which meshes with the drive gear of the starter and is used by the starter. This ring gear is called the flywheel ring gear. There is no flywheel ring gear on the flywheel of a hand-started single-cylinder tractor engine.

Example: The flywheel ring gear is pre-heated to normalizing, with a hardness of 160~220HB.

Pre-processing steps: gear hobbing, chamfering and cleaning.

Post-processing process: hot loading.

Production process route: forging, normalizing, rough turning, fine turning, hobbing and chamfering, quenching, inspection, and hot charging.

Technical requirements: The material used is 45# steel (carbon content 0.42‰ to 0.47%), the tooth part is high-frequency quenched, the hardness is 41-49HRC, the depth of the hardened layer on the tooth top surface and tooth side is ≥1.5mm. The teeth are allowed to be hardened through.

There are usually two forms of heat treatment for flywheel ring gears: one is heated with high-frequency induction heating equipment; the other is heated with medium-frequency induction heating equipment. See the following description for details.

1. Heating with high-frequency induction heating equipment

(1) Adjustment of process parameters. The high-frequency mass production of flywheel ring gears is carried out on a 10OkW, WH-VI high-frequency quenching and quenching machine. Through extensive experiments, better process parameters were finally optimized. Because it is mass production, the residual temperature is 180°C and is tempered at low temperature using self-tempering technology.

(2)Quenching sensor and fixture. The inductor for high-frequency quenching of flywheel ring gear belongs to the ring type quenching inductor.

Since the high-frequency quenching machine uses upper and lower center positioning, in order to ensure that the quenched parts rotate more smoothly during the quenching process, the induction quenching of the flywheel ring gear was positioned and satisfactory results were achieved.

(3) Quenching results. The tooth surface hardness is 47--50HRC; the metallographic structure is quenched martensite grade 5; the depth of the hardened layer at the tooth root is 1.7mm.

2. Heating with medium frequency induction heating equipment

(1) Adjustment of process parameters. The intermediate frequency mass production of flywheel ring gear is carried out on 160kW, 8000Hz 29 intermediate frequency generator and hydraulic transmission vertical quenching machine tool equipment. Through extensive experiments, the optimal process parameters as shown in Table 5-29 were finally optimized. Because it is mass production, the residual temperature is 180°C and is tempered at low temperature using self-tempering technology.

(2)Quenching sensor and fixture. The inductor for medium frequency quenching of flywheel ring gear belongs to the ring type quenching inductor. Since the intermediate frequency quenching machine uses upper and lower center positioning, in order to ensure that the quenched parts rotate more smoothly during the quenching process, the induction quenching of the flywheel ring gear was positioned and satisfactory results were achieved.

The flywheel ring gear was positioned by induction hardening with satisfactory results.

(3) Quenching results. The tooth surface hardness is 45~49HRC; the metallographic structure is quenched martensite grade 5; the depth of the hardened layer at the tooth root is 2.1mm.