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Brazing Heater Assembly Requirements Are Relatively High

May 26, 2017

The use of Brazing Heater

First, the heat treatment: a variety of metal parts or the overall quenching, annealing, tempering, heat;

  Second, the thermoforming: the whole forging, local forging, hot forging, hot rolling;

  Third, welding: all kinds of metal products brazing, all kinds of tool blades, saw blade sawtooth welding, steel pipe, copper pipe welding, the same kind of dissimilar metal welding;

Fourth, metal smelting: gold, silver, copper, iron, aluminum and other metal (vacuum) smelting, casting molding and evaporation coating;

5, high-frequency heating machine Other applications: semiconductor single crystal growth, thermal fit, bottle heat sealing, toothpaste leather heat sealing, powder coating, metal implantation plastic.

Brazing Heater and process

I. Overview 

    Brazing is a solid-phase connection, he and welding method is different from the base material is not melting brazing, the use of lower than the parent metal melting temperature of the brazing filler metal, the heating temperature is lower than the base material solid line and higher than the brazing filler metal Line of a connection method. When the connected parts and the brazing material are heated to the solder to melt, the liquid solder is wetted on the surface of the base metal by the liquid solder, and the base material is dissolved and diffused with each other and wetted in the base material gap, and the capillary flow, Mutual dissolution and diffusion to achieve the connection between parts.

    Compared with the welding method, brazing has the following advantages:

    1) brazing heating temperature is low, the parent metal structure and performance of the smaller;

    2) brazed joints smooth, beautiful appearance;

    3) The deformation of the weldment is small, especially the use of uniform heating (such as furnace brazing) brazing method, the deformation of the weldment can be reduced to a minimum, easy to ensure the dimensional accuracy of the weldment;

    4) some brazing method can be welded into a few tens or hundreds of brazing seam, high productivity;

    5) can be achieved heterogeneous metal or alloy, metal and non-metallic connection.

    However, brazing also has its own shortcomings, brazing joint strength is relatively low, heat resistance is relatively poor, due to the difference between the base metal and solder composition caused by large electrochemical corrosion caused by poor corrosion resistance and assembly requirements are relatively high The

    According to the use of different solder, brazing is generally divided into:

    1) Solder - solder The liquidus temperature is below 450 ° C.

    2) brazing - solder liquidus temperature higher than 450 ℃.

    In addition, some countries will brazing the temperature of more than 900 ℃ without the use of flux brazing methods (such as Brazing Heater, gas protection brazing) called high temperature brazing.

    Second, the brazing method

    Brazing method is usually named after the application of the heat source, its main role is to rely on the heat source to heat the workpiece to the necessary temperature, with the development and use of new heat sources, in recent years there have been many new brazing method.

1, flame brazing

    Flame brazing is the use of combustible gases (including liquid fuel fan) blowing air or pure oxygen ignited after the flame for heating. Flame brazing because the equipment is simple, wide gas source, flexibility, and therefore widely used.

    The torch used for flame brazing can be a universal gas torch or a special brazing torch. Special brazing torch is characterized by relatively scattered flame, heating concentration is low, so the heating is relatively uniform. Brazing relatively large parts or mechanized flame brazing can be used with a multi-flame nozzle special brazing torch.

    The combustible gas used in the hot pot brazing may be acetylene, propane, liquefied petroleum gas, atomized gasoline, gas and the like. The combustion gas is oxygen and compressed gas. Heating range is very broad, from the hundreds of degrees of alcohol torch to oxygen acetylene flame more than 3000 ℃. Flame has two layers of structure, the outer layer of light blue flame is flame oxidation, burning completely, the highest temperature, oxygen, excessive heating easy to make the workpiece metal surface oxidation: inner dark blue flame is reduced flame, the temperature is low , Hypoxia, rich in carbon monoxide, can protect the metal from oxidation. Combustible gas combustion products are CO2 and high temperature water vapor (hydrogen flame only water vapor), whether it is flux or solder, taboo high temperature water vapor should consider this factor.

    Oxygen acetylene flame is the most commonly used flame, because the flame temperature is high, while the brazing temperature is much lower. So the flame is usually used to heat the flame, because the flame temperature is low and large volume, heating more uniform. Generally use neutral flame or slightly acetylene flame.

    When the heating temperature does not require too much, you can use compressed air instead of oxygen, with propane, LPG, atomized gasoline instead of acetylene. The temperature of these flames is low, and the flame without acetylene does not contaminate the flux, which is suitable for relatively small brazing parts and aluminum and aluminum alloys.

    When the flame is brazed, the flux solution is pre-coated on the surface of the joint or the brazing rod is heated, dipped in flux, and then onto the heated joint surface. The brazing filler metal can be pre-installed or manually fed. Brazing the workpiece should be evenly heated to the brazing temperature, and then add solder, or solder can not even fill the gap. For the pre-brazing filler metal joints, should also be heated to avoid the workpiece in direct contact with the flame, so that premature melting, brazing brazing, you can also use a torch to heat.

    Flame brazing, in addition to single flame soldering can also be used multi-flame torch. Brazing in addition to manual operation, there are special automatic flame brazing machine. Figure 2 shows the special flame brazing equipment.