Welded components are positioned so that they are in contact with the faces. The following stages can be distinguished in the spark butt welding process:
- preheating
- wyiskrzanie
- upsetting
Heating is carried out at low pressure. As soon as the joint heats up, there is a sparking-out stage in which the material of the joint surface is fired, resulting in a smooth, clean surface.
When the spark plug allowance is removed, the upsetting step occurs, in which a effluent containing molten and oxidized metal is formed.
Welded objects are fixed in the jaws of the welding machine and pressed down with a slight force sufficient to ensure contact in several places. After switching on the flow of current through contact areas with a small area and high contact resistance, a very high-density current flows, causing the metal of the contact areas to melt, the formation of liquid current bridges and their violent rupture due to the effects of electromagnetic forces and metal vapor pressure. With the liquid ego metal ejected from the bridges, all contaminants are removed simultaneously. Progressing at the right speed, in a continuous way, the sparking process causes that heat from the new current bridges is flowing away deep into the welded objects and heats the adjacent areas to a state of strong plasticization.
SPARK WELDING PARAMETERS:
- current,
- sparking out speed in mm / s,
- allowance for sparking out in mm,
- upsetting speed in mm / s,
- upset pressure in kN,
- upset allowance in mm,
- clamping length in mm,
APPLICATION:
Spark resistance welding is used for butt joints of pipes, wires, profile rods, rail rails, belts, sheets, chain links, cutting tools, shafts, etc. Welded items made of carbon steel, low alloy, high alloy, copper and copper alloys, aluminum and his alloys. It is possible to combine steel with copper, copper with aluminum, low carbon steel with tool steel. Spark resistance welding enables joining steel objects with cross-sections over 100,000 mm2, aluminum and aluminum alloys up to 90,000 mm2 as well as copper and copper alloys up to 30,000 mm2.
ADVANTAGES OF A SPARK WELDING COMPARISON WITH A SHORT CIRCUIT:
- greater strength and plasticity from the link
- a wider range of welding options for different metals (the sparking period can last as long as each metal has reached its melting point)
- prostsze przygotowanie przedmiotów
- lower energy consumption and faster welding speed and therefore higher efficiency
- narrow heat affected zone
