Self-maintained friction stir welding method with reversely rotating upper and lower shaft shoulders

Abstract

The invention discloses a self-maintained friction stir welding method with reversely rotating upper and lower shaft shoulders, and relates to a self-maintained friction stir welding method to solve the problems that: the upper and lower shaft shoulders have unequal diameters but rotate in the same direction with equal speed, and in the welding process, the weld heat input is large, a workpiece is easy to deform, a mixing needle is inclined to fracture, and the distribution of a weld zone temperature field, a joint structure and residual stress are asymmetric, so that the joint performance is asymmetric, and the bearing capacity of a welding structure is reduced. The method comprises the following steps of: 1, determining the size of a stirring head, namely determining the diameter of the upper shaft shoulder, the stirring needle and the lower shaft shoulder according to the thickness of a first welded workpiece and a second welded workpiece; 2, determining the use length of the stirring needle; 3, fixing the first welded workpiece and the second welded workpiece; 4, positioning the stirring head; and 5, performing friction stir welding on the first welded workpiece and the second welded workpiece, namely integrally forming the upper shaft shoulder and the stirring needle, and allowing the lower shaft shoulder and the upper shaft shoulder to rotate in opposite directions. The self-maintained friction stir welding method is used for self-maintained friction stir welding.

Description

technical field [0001] The invention relates to a self-sustaining friction stir welding method. Background technique [0002] The invention patent application with the patent application number 2010102964802 discloses a "self-sustaining friction stir welding method with different diameters of upper and lower shoulders and its stirring head". The stirring head used in this application is that the diameter of the lower shoulder is smaller than that of the upper shaft The diameter of the shoulder, during the welding process, the rotation direction of the upper shoulder and the lower shoulder is the same, and the two rotate at the same speed, the lower shoulder plays the role of the backing plate of the conventional friction stir welding, but due to the welding process, the lower shoulder It produces a large friction force with the lower surface of the workpiece, which increases the welding heat input, and makes both the workpiece and the stirring pin bear a large torque, which ...

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Problems solved by technology

[0003] The purpose of the present invention is to solve the problem of large welding heat input caused by the rotation of the upper and lower shaft shoulders in the same direction, the workpiece is easily deformed, the stirring pin has a tendency to break, the temperature field in the weld zone, the joint structure and the distribution of residual stress are asymmetrical, resulting in poor performance of the joint. Asymmetry reduces the problem of the bearing capacity of the welded structure, and provides a self-sustaining friction stir welding method in which the upper and lower shoulders rotate in reverse

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