Wondery Vacuum Plasma Ion Nitriding Furnace Heat Treatment Furnace pit type furnace
1.Composition
The complete set of ion nitriding heat treatment furnace is composed of ion power supply, vacuum furnace body, vacuum acquisition system, temperature measurement and control system and gas supply system.
1.1 Ion power supply
Ion power supply is divided into DC ion power supply and pulse ion power supply, which users can choose according to their needs.
(A)DC ion power supply
DC ion power supply mainly includes rectifier transformer, controllable rectifier circuit, L-C oscillation arc extinguishing circuit, cut-off feedback circuit and control circuit.
(B)pulse ion power supply
Pulse ion power supply is a chopper composed of IGBT components and control circuit, which is added on the basis of DC ion power supply. Through chopping, the pulse current with adjustable duty cycle can be obtained.
Compared with DC ion power supply, pulsed ion power supply can better improve the hollow cathode effect.
The pulse ion power supply returns the current to zero and the glow goes out once in each working cycle (when the frequency is 1kHz, the cycle is 1ms), so the arc extinguishing efficiency is improved.
Pulse ion power supply can realize independent regulation of voltage and current, and can meet different process requirements.
Compared with DC ion power supply, the energy saving of pulse ion power supply is more than 20/100-25/100.
1.2 Vacuum furnace body
The vacuum plasma ion nitriding furnace body of the equipment is divided into three forms: well type (parts hanging), bell type (parts stacking) and integrated type.
The vacuum furnace body is composed of a furnace barrel and a furnace chassis.
The furnace barrel is welded with steel plates and has a double-layer structure, with water cooling in the middle. All sealing surfaces (grooves) are sealed with vacuum rubber sealing rings. The furnace is equipped with stainless steel heat shield and cathode plate. An observation window is opened on the furnace barrel. The air inlet port is installed on the top of the furnace body.
The furnace chassis is equipped with cathode power transmission interface, temperature measurement interface, pressure measurement interface, air extraction interface, etc.
The cathode transmission device is composed of cathode rod, seal, insulating pad, bearing column and air gap sleeve. The cathode lead is connected with the cathode plate through the cathode power transmission device.
The vacuum heat treatment furnace body is well sealed to ensure the vacuum degree required by the process.
According to the requirements of the size of processed parts and production capacity, the vacuum furnace body has sufficient working volume.
1.3 Vacuum system
The vacuum acquisition system is composed of rotary vane mechanical vacuum pump, vacuum solenoid valve and vacuum butterfly valve, which are connected with the vacuum furnace body through vacuum pipes.
Resistance vacuum gauge is used to measure the vacuum degree of vacuum furnace.
1.4 Temperature measurement and control system
The temperature measurement and control system is composed of thermocouple, temperature control circuit and temperature control instrument. The temperature millivolt signal is obtained by the thermocouple, and the workpiece temperature is accurately controlled through the PID adjustment of the temperature control instrument and related circuits.
1.5 Air supply system
The gas supply system is composed of ammonia cylinder, ammonia pressure reducer, flowmeter and gas transmission pipeline.
The vacuum plasma ion nitriding furnace is equipped with two flow meters, one for ammonia flow regulation and the other for carburizing gas flow regulation. The two gases are mixed into the furnace after passing through the flowmeter, and the nitrocarburizing process (soft nitriding) can be realized by adjusting the flow ratio.
2. Main technical parameters of vacuum nitriding furnace
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Input power supply: three-phase 380V 50Hz DC output voltage: 0-1000v adjustable Large output current (DC power supply): Peak current (pulse power supply): Average current: Duty cycle (pulse power supply):0.10-0.85 adjustable Pulse frequency (pulse power supply):1000hz Control mode (pulse power supply): constant frequency and width adjustment Output waveform (pulse power supply): rectangular square wave Effective working volume of furnace body: Working temperature: ≤ 650 ℃ Large charging capacity: Very small vacuum degree: ≤ 6.67pa Pressure rise rate: ≤ 0.133pa/min
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3.What is an ion nitriding furnace?
Speaking of the ion nitriding furnace, we may be a little strange. Ion nitriding furnace is made by ion nitriding process. Let's explain the ion nitriding process in detail.
The nitriding temperature of plasma ion nitriding furnace is basically the same as that of gas, generally between 500~540℃. The nitriding hardness of different materials corresponds to the temperature, generally between 450~540℃. When the temperature is higher than 590 ℃, the hardness will be significantly reduced due to the accumulation of nitrogen.
The heating rate depends on the current density of the surface layer of the workpiece, the ratio of the volume of the workpiece to the total area of the surface layer causing brilliance, and the complexity and heat dissipation coefficient of the workpiece. Reduce the deformation, and the heating rate is not suitable for too fast, generally 150~250 ℃/h. The holding temperature should be stable and the fluctuation should be small. The stability of holding temperature is closely related to furnace pressure and voltage. According to the stable furnace pressure, the current density is stabilized, so as to improve the stability of insulation temperature. The current density is stabilized according to the stable voltage, so as to improve the stability of insulation temperature.
The holding time of nitrogen leakage depends on the material of nitrided parts and the thickness and hardness of nitrided layer. The insulation time ranges from tens of minutes to tens of hours. When the nitriding time is within 20h, ion nitriding is significantly greater than gas nitriding. When the nitriding time is above 20h, the leakage rate of the two types of nitrogen is close. It can be seen that ion nitriding is more suitable for workpieces with nitriding layer less than 0.5mm. When the depth of nitriding layer is 0.2~0.5mm, it is generally 8~20h.
