Process analysis of heat treatment of machine taps using ultrasonic induction heating machine

Machine taps are used to process ordinary internal threads on nuts or other machine parts. In order to better meet the needs of their work, machine taps generally use ultrasonic induction heating machines for heat treatment. Today, the editor will briefly tell you about the ultrasonic heat treatment process of machine taps.

1) Preheat. Generally, there are two preheatings: the first preheating temperature is 500-55O℃, the second time is 850-870℃, and the preheating time is twice the heating time.

2) Heating. The ultrasonic induction heating machine heats machine taps. The heating temperature is shown in Table 1. The heating time of taps of different specifications is shown in Table 2.

Table 1: Tap heating temperature

Table 2: Tap heating time

3) Cool down. Cool in the 5-3-2 neutral salt bath furnace to half of the high-temperature heating time and then come out of the furnace for air cooling. The cooling furnace temperature should be controlled at 580-620°C; if conditions permit, it can also be isothermal after grading, that is, 580-620 After ℃ classification, enter 260-280℃×1h nitrate salt isotherm.

4) Tempering. After the quenched tap is cooled to room temperature and cleaned, it needs to be tempered with an ultrasonic induction heating machine. The process is 550℃xlhx3 times. For isothermal quenching, four temperings are required, and sampling is performed after the third tempering.

5) Sampling. Sampling mainly checks three indicators: ① Overheating degree: ≤1 level is qualified, and some units and enterprises’ internal control standards do not allow overheating; 2. Tempering degree: ≤1 level is qualified. If level 2 is found during the random inspection, an additional tempering will be added: ③ Hardness check. There is no upper limit to the hardness of the tap, but it cannot be too high.

Some domestic tap manufacturers, in order to cater to market competition and customer needs, also have higher requirements for hot hardness, that is, the room temperature hardness after 600℃X4h is ≥61HRC.

As one of the commonly used tools, machine taps generally require heat treatment to improve their hardness, wear resistance and service life to meet their working needs. This article briefly introduces the ultrasonic heat treatment process of machine taps. I hope everyone can strictly follow the above process when heat treating taps to produce high-quality taps.