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What are the heating methods of welding tool heat treatment furnace

by:Kehua     2022-07-28
I believe everyone has seen electric welding. Some construction sites or in the process of decoration will see electric welders, and these are only some basic electric welding environments, such as making some metal parts such as knives, tools and some auto and motorcycle parts. Lamps, all need to use welding tool heat treatment furnace. The welding residual stress is caused by the uneven temperature distribution of the weldment caused by welding, the thermal expansion and contraction of the weld metal, etc., so the residual stress will inevitably be generated along with the welding construction. The most common method for eliminating residual stress is high temperature tempering, that is, heating the weldment in a heat treatment furnace to a certain temperature (below Ac1) and holding it for a certain period of time, using the reduction of the yield limit of the material at high temperature to make the place with high internal stress. Plastic flow occurs, the elastic deformation gradually decreases, and the plastic deformation gradually increases to reduce the stress. The effect of post-weld heat treatment on the tensile strength and creep limit of the metal is related to the temperature and holding time of the heat treatment. The influence of post-weld heat treatment on the impact toughness of weld metal varies with different steel types. Welding tool heat treatment furnace. Fuel heating method: The fuel used can be solid (coal), liquid (oil) and gas (gas, natural gas, liquefied petroleum gas). Coal-fired heating: Kehua coal is rich in resources, and coal-fired reverberatory furnaces have played a certain role in heat treatment heating methods. The nature of the coal and the structure of the reverberatory furnace determine that the coal is not easy to burn completely, so the thermal efficiency of the coal furnace is low, the heating quality and working conditions are poor, and the soot pollutes the environment. These shortcomings make the coal-fired heating method gradually replaced by other heating methods. Liquid fuel heating: mainly use heavy diesel fuel as fuel, suitable for heating in large heating furnaces, and also for heating external heating salt bath furnaces. Generally, nozzles are installed on one or both sides of the furnace heating outdoor wall. When the liquid fuel is used to heat the externally heated salt bath furnace, the nozzle is installed on the furnace shell outside the crucible. The liquid fuel is mixed with air in the nozzle and atomized under the action of compressed air, and then sprayed out of the nozzle and burned in the heating chamber (or outside the crucible of the salt bath furnace) to heat the workpiece (or crucible). Reasonable design and arrangement of nozzles play a key role in maintaining uniform furnace temperature and saving fuel. The atomized oil sprayed from the nozzle can also be burned in the radiant tube in the furnace, which heats the radiant tube to indirectly heat the workpiece. Compared with coal, fuel oil is easier to control the heating temperature, and it is suitable for the overall heating of large parts and areas with sufficient fuel supply. Gas fuel heating: In the nozzle, the gas is mixed with a certain proportion of air and then ejected for combustion. This method can directly heat the workpiece placed in the heating chamber, or can spray the flame into the radiant tube installed in the heating chamber to indirectly heat the workpiece. When used in a salt bath furnace, the nozzle is mounted on the furnace shell outside the crucible, and the flame is shot to the outside of the crucible to heat the molten salt. The gas fuels used for heating include coal gas, natural gas and liquefied petroleum gas. Adjusting the ratio of air to gas can obtain an oxidizing or reducing combustion atmosphere, thereby reducing the degree of oxidative decarburization when the workpiece is heated. This Kehua heating method is suitable for bulk heating and areas with ample gas supply. Another way is to directly heat the surface of the workpiece with the flame of the nozzle. At this time, the nozzle and the workpiece move relative to each other. The gas used is oxygen-acetylene, oxygen-propane, oxygen-methane, etc. This heating method is flame quenching, which is suitable for surface quenching of workpieces. Welding tool heat treatment furnace Electric heating method: Using electricity as the heat source, the electric energy is converted into heat energy by various methods to heat the workpiece. When electric heating, the temperature is easy to control, there is no environmental pollution, and the thermal efficiency is high. There are various methods of electrical heating. Electric heating element heating: The workpiece is heated by the resistance heat generated when the power frequency (50-60 Hz) alternating current passes through the electric heating element. Electric heating elements are often arranged around or on both sides of the heating chamber to ensure uniform temperature in the heating chamber; some are installed in the radiant tube to indirectly heat the workpiece. For externally heated salt bath furnace or metal bath furnace, the electric heating element is arranged in the space outside the crucible and inside the shell. This heating method can also be used in floating particle furnaces for alumina particles. It is suitable for areas where the workpiece is heated as a whole and has sufficient power. Workpiece resistance heating: The alternating current after depressurization directly passes through the workpiece, and the heat generated by the resistance of the workpiece itself increases the temperature of the workpiece. This method is suitable for the overall heating of workpieces with uniform cross-sections. Another way is to use a rolling copper wheel to press on the metal workpiece, pass an alternating current of low voltage and high current, and use the contact resistance between the copper wheel and the workpiece to generate heat to heat the surface of the workpiece. Induction heating of the workpiece: The workpiece is placed in a spiral coil, and the coil is connected with alternating current of a certain frequency (generally higher than the power frequency), so that the workpiece placed in the coil generates eddy current, and the resistance of the workpiece itself is used to generate heat and be heated. . The depth of this heating can become shallower as the current frequency increases, which is called induction heating heat treatment. Induction heating is mainly used to heat the surface of the workpiece, but with a lower frequency and the diameter of the workpiece is small, it can also be heated overall. This heating method has high efficiency and low power consumption, and is mostly used for heating and quenching of medium and small parts. Heating medium resistance heating: The low-voltage alternating current of industrial frequency is introduced into the electrode buried in the medium, and the resistance heat generated when the current flows through the medium is used to make the medium itself reach a high temperature. The workpiece is heated in this high temperature medium, which can reduce or avoid oxidative decarburization. This medium is all electrical conductors, such as salt, graphite particles, etc. The furnace types of the heating furnace include an internal heating salt bath furnace and a graphite floating particle furnace. This heating method is mainly used for heating and quenching of medium and small parts. Then let's talk about whether the welding tool heat treatment furnace must be used. The answer is: yes, in the production of many metal workpieces, the welding tool heat treatment furnace must be used.
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