Plasticized material flows from the front to the back of the welding tool under the action of rotating friction of the welding tool, and forms a dense solid weld under the extrusion of the welding tool.
Friction stir welding is the same as traditional friction welding. Friction stir welding also uses friction heat and plastic deformation heat as welding heat source. The difference is that the welding process of friction stir welding is that the welding needle of cylinder or other shapes (such as threaded cylinder) extends into the weld seam of the workpiece;
Through the high-speed rotation of the welding head, the material of the workpiece is rubbed and welded, so that the temperature of the material at the joint increases and softens. At the same time, the material is stirred and rubbed to complete the welding. The welding process is shown in the figure. In the welding process, the workpiece should be rigidly fixed on the back pad, the edge of the welding head rotates at high speed, and the welding seam of the edge workpiece moves relative to the workpiece.
The protruding section of the welding head extends into the material for friction and stirring, and the shoulder of the welding head rubs against the surface of the workpiece to generate heat, which is used to prevent the plastic state material from overflowing and remove the oxide film on the surface.
Extended data
The main advantages of friction stir welding are as follows:
(1) The microstructure of the heat affected zone of the welded joint changes little, the residual stress is low, and the welded workpiece is not easy to deform.
(2) The welding of long seam, large section and different positions can be completed at one time. Seam height:
(3) The operation process is convenient to realize mechanization and automation, with simple equipment, low energy consumption, high efficacy and low requirements for working environment;
(4) There is no need to add welding wire when welding aluminum alloy, and the oxide film and shielding gas are removed before welding, so the cost is low;
(5) It can weld materials sensitive to hot cracks, and is suitable for welding dissimilar materials.
(6) The welding process is safe, pollution-free, smokeless and radiation-free.
References:
Baidu encyclopedia-friction stir welding