What is the nitriding process of multi-purpose carburizing furnace?

What is the nitriding process of multi-purpose carburizing furnace?

According to the workpiece material and infiltration layer requirements of 3-90 hours, so that nitriding workpiece surface to obtain a nitrogenous strengthening layer, high hardness, high wear resistance, high fatigue limit and good wear resistance.

Carburizing multi-purpose furnace operation method:

1. The mold before nitriding must be a workpiece that has been normalized or tempered first.

2. Scrub the surface of the workpiece with gasoline and alcohol first, and there shall be no rust, oil and dirt.

3. After loading into the furnace, tighten the furnace cover compression bolt symmetrically.

4. The water inlet of the furnace tank and the furnace cover is passed into the cooling water for circulating water cooling. The lower end of the cooling water in the pipe on the furnace cover is the water inlet, and the upper end is the water outlet. The furnace pot is separately fed into and drained separately. All the water pipes on the furnace cover can be connected in series according to the principle of low inlet and high inlet.

5. Nitrogen exhaust should be sent before heating up, and the flow rate of exhaust should be more than twice that of use.

During ion nitriding, the quality of nitriding layer and the nitriding period are directly affected by the working temperature. Due to the influence of high voltage, glow and atmosphere, the temperature measurement is difficult. Currently used in ions

The temperature measurement methods of nitriding furnace are as follows:

(1) Visual measurement

Turn off the high-voltage power supply, through the observation window, and judge the temperature by looking at the color of the workpiece with the naked eye (in the dark furnace cover, the metal is slightly red at about 520 ° C, and the metal is dark red at about 550 ° C). Obviously, this method varies from person to person, the temperature difference may be large, and the quality of nitriding is poorly controlled.

(2) Thermocouple temperature measurement

This method usually uses armored thermocouples to make a special temperature probe, which is closely attached to the workpiece, and measures and controls the nitriding temperature through the display instrument.

In order to avoid the thermocouple with negative high voltage, there is usually a mica sheet or quartz tube insulation between the head of the thermocouple and the workpiece, but this will make the temperature indication low, and after long-term work, due to the cathode sputtering effect, the surface of the insulation contaminated with metal powder and become a conductor. The thermocouple will still be nitrided with negative high voltage, and the indication error will increase. Sometimes due to the poor contact between the insulation and the workpiece, the glow discharge will be unstable, causing arc, and the carburizing multi-purpose furnace will affect the normal operation.

(3) photoelectric pyrometer or photoelectric colorimetric pyrometer temperature measurement

Both thermometers are used to observe the glass of the window on the closed container to achieve continuous, rapid and non-contact temperature measurement and control outside the nitriding furnace, which is a more advanced method. When measuring temperature with photoelectric pyrometer, it is necessary to consider the change of workpiece surface condition (surface finish and geometric shape), the influence of workpiece surface emissivity, window pollution, ionized gas in the furnace, glow discharge and cathode sputtering on the temperature measurement accuracy. When the photoelectric colorimetric pyrometer is used to measure the temperature, the influence of these factors is much less, so it is an ideal thermometer for measuring the workpiece temperature of ion nitriding furnace at present.