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Pipe annealing furnace
Yiran manufacturer supplies energy-saving thermal storage gas natural gas high-temperature hot air stove equipment, with high hot air temperature, goo
Product details
1. Equipment structural characteristics
A heating furnace that uses resistance wires or resistance strips as heating elements is called a resistance furnace. Electric heating elements have high heat resistance and high-temperature strength, low temperature coefficient of resistance, and good chemical stability. The commonly used materials are divided into two categories: metallic and non-metallic. Metal electric heating element materials include nickel chromium alloy, chromium aluminum alloy, tungsten, molybdenum, tantalum, etc. They are generally made into spiral wires, waveform wires, waveform bands, and waveform plates. Non metallic electric heating element materials include silicon carbide, molybdenum disilicide, graphite, and carbon, which are generally made into shapes such as rods, tubes, plates, and strips. The distribution and wiring of electric heating elements depend on the power and temperature requirements of the furnace.
2. Main purpose
Mainly used for vacuum heat treatment, vacuum brazing, and vacuum sintering of high-speed steel, cold and hot work mold steel, martensitic stainless steel, elastic alloys, high-temperature alloys, magnetic materials, and titanium alloys.
This furnace is suitable for both mass production of the same steel grade and single piece or small batch production of multiple specifications and varieties. This furnace has good economy and versatility.
3. Main models and technical parameters
A resistance furnace is an electric furnace that uses Joule heating generated by current passing through a conductor as its heat source.
A resistance furnace uses electricity as a heat source and converts electrical energy into thermal energy through electric heating elements to heat metals inside the furnace. Resistance furnace has a higher thermal efficiency compared to flame, reaching 50-80%. The thermal system is easy to control, the working conditions are good, and the furnace body has a long service life. It is suitable for heating workpieces with strict requirements, but the power consumption cost is high.
According to the heat transfer method, resistance furnaces are divided into radiation resistance furnaces and convection resistance furnaces. Radiation resistance furnace mainly relies on radiation heat transfer, with less convective heat transfer effect; Convection resistance furnaces are mainly based on convective heat transfer, commonly known as air circulation resistance furnaces, which rely on hot air for heating, and the furnace temperature is often below 650 ℃. According to the method of electric heating, resistance furnaces are divided into two types: direct heating and indirect heating.
Direct heating type
Direct heating resistance furnace refers to the process where current passes directly through the heated material, causing it to generate heat energy. Commonly used for graphitization of carbonaceous electrodes and dense sintering of refractory metals [2].
In a direct heating resistance furnace, current passes directly through the material. Due to the concentration of electric heating power on the material itself, the material heats up quickly, making it suitable for processes that require rapid heating, such as heating forging billets. This type of resistance furnace can heat materials to very high temperatures, such as carbon material graphitization electric furnace, which can heat materials to over 2500 □. Direct heating resistance furnace can be used as a vacuum resistance heating furnace or a gas shielded resistance heating furnace. In powder metallurgy, it is commonly used for sintering products such as tungsten, tantalum, niobium, etc.
When using this furnace for heating, attention should be paid to: ① To ensure uniform heating of the material, it is required that the conductive cross-section and conductivity of each part of the material are consistent; ② Due to the relatively small resistance of the material itself, in order to achieve the required electric heating power, the working current is quite large. Therefore, the contact between the power transmission electrode and the material should be good to avoid arcing and burning the material. In addition, the resistance of the power transmission busbar should be small to reduce circuit losses When supplying AC power, it is necessary to configure the short network reasonably to avoid excessive inductance and low power factor.
Indirect heating type
Indirect resistance furnace is a resistance furnace in which a power source is connected to a heating element or other conductive medium (such as molten metal salt), causing the heating element or conductive medium to generate resistance heat. The furnace material is indirectly heated through heat conduction, convection, and radiation.
Most resistance furnaces are indirect heating furnaces, which are equipped with resistors specifically designed to achieve electric thermal conversion, called electric heating bodies, which transfer thermal energy to the materials in the furnace.
This electric furnace shell is made of steel plate, the furnace is lined with refractory materials, and materials are placed inside. The most commonly used electric heating elements are iron chromium aluminum electric heating elements, nickel chromium electric heating elements, silicon carbide rods, and molybdenum disilicide rods. According to the needs, the atmosphere inside the furnace can be a normal atmosphere, a protective atmosphere, or a vacuum. The general power supply voltage is 220 volts or 380 volts, and an intermediate transformer with adjustable voltage can be configured if necessary. Small furnaces (<10 kW) are powered by single-phase power supply, while large furnaces are powered by three-phase power supply. For materials with a single variety and large batch size, continuous furnace heating is recommended. Most resistance furnaces with a furnace temperature below 700 degrees are equipped with blowers to enhance heat transfer inside the furnace and ensure uniform heating. A resistance furnace used for melting easily melted metals such as lead, lead bismuth alloys, aluminum, magnesium, and their alloys, which can be made into a crucible furnace; Or it can be made into a reflector furnace with a molten pool, and an electric heating element can be installed on the top of the furnace.
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