CN-121535319-B - Stirring head for friction stir welding of dissimilar materials with different thicknesses and welding method

CN121535319BCN 121535319 BCN121535319 BCN 121535319BCN-121535319-B

Abstract

The invention belongs to the technical field of welding, in particular to a stirring head for friction stir welding of dissimilar materials with different thicknesses and a welding method, wherein the stirring head comprises a large shaft shoulder, a small shaft shoulder and a stirring pin which are coaxially arranged from top to bottom, the diameters of the large shaft shoulder, the small shaft shoulder and the stirring pin are sequentially reduced, the length of the stirring pin is not greater than the thickness of the thin plate to be welded, and the sum of the lengths of the small shaft shoulder and the stirring pin is not greater than the thickness of the thick plate to be welded. When the stirring head is used for welding, the step is machined on the edge of the length of the thick plate, the height of the step is equal to the thickness of the thin plate, the thin plate is assembled on the step, and the thick plate and the thin plate are subjected to friction welding. The invention can improve the welding performance between different plates with different thicknesses.

Inventors

SU HAO
ZHANG FENG
CHEN JI
WU CHUANSONG

Assignees

山东大学

Dates

Publication Date: 20260512
Application Date: 20260121

Claims (4)

1. The stirring head comprises a large shaft shoulder, a small shaft shoulder and a stirring pin which are coaxially arranged from top to bottom, the diameters of the large shaft shoulder, the small shaft shoulder and the stirring pin are sequentially reduced, the length of the stirring pin is not greater than the thickness of a thin plate to be welded, and the sum of the lengths of the small shaft shoulder and the stirring pin is not greater than the thickness of the thick plate to be welded, and the stirring head is characterized by comprising the following specific steps: S1, processing steps on the edges of the length of two different plates with different thicknesses, wherein the heights of the steps are the same as those of the thin plates, and cleaning the two plates; s2, assembling the thin plate into a step of the thick plate, clamping the thick plate on the upper side and the thin plate on the lower side, assembling a stirring tool on a friction stir welding machine, positioning the stirring tool and the clamped plates, and enabling the bottom of a stirring pin to be tangent to a butt joint surface on the inner sides of the two plates; S3, starting a friction stir welding machine, controlling a stirring tool to rotate and press down, stopping for a period of time after all stirring pins enter materials, plasticizing a thick plate through friction heat generation between the bottoms of small shaft shoulders and the plates, and controlling the stirring tool to press down continuously until the small shaft shoulders enter the materials completely, wherein at the moment, the small shaft shoulders contact and rub the joint surfaces of two plates, and the sides of the stirring pins contact and rub the interface surfaces of the two plates; s4, controlling a friction stir welding machine to realize friction stir welding according to a set path and parameter welding, and always maintaining the contact friction between the small shaft shoulder and the lap joint surface and the contact friction between the side surface of the stirring pin and the butt joint surface in the welding process; S5, after the processing is completed, the stirring tool is removed, then the friction stir welding machine is closed, and the processed plate is placed in air and cooled to room temperature.
2. The friction stir welding method for dissimilar materials according to claim 1, wherein the step width machined on the thick plate is 20-30mm.
3. The friction stir welding method for dissimilar materials according to claim 1, wherein the thin plate has a hardness greater than the thick plate.
4. The friction stir welding method for dissimilar materials of unequal thickness according to claim 1, wherein the large shoulder is H13 tool steel and the small shoulder and pin are tungsten-rhenium alloy.

Description

Stirring head for friction stir welding of dissimilar materials with different thicknesses and welding method Technical Field The invention mainly relates to the technical field of welding, in particular to a stirring head for friction stir welding of dissimilar materials with different thicknesses and a welding method. Background Friction stir welding (Friction STIR WELDING, FSW) has been increasingly used as a solid phase joining technique with great attention and application in high-end manufacturing, especially in the field of lightweight smart manufacturing, the welding principle of which is well known. Compared with the traditional fusion welding method, the FSW has the advantages of green and environment-friendly welding process, low energy consumption, small welding deformation, high welding seam quality and the like, and is particularly suitable for the connection of aluminum alloy, magnesium alloy and other difficult-to-weld materials. In the FSW process, geometric characteristics such as the shape, size, etc. of the welding tool (or stirring head) play a decisive role in the welding quality. The typical stirring head consists of a shaft shoulder and a stirring head, and the stirring head is in intense friction with a welded material and generates heat to drive the material to plastically flow so as to form a welding seam. At present, FSW technology has been applied to the fields of aerospace, automobile manufacturing and the like. Because of the unique advantages, the FSW technology is also very suitable for the efficient welding of dissimilar materials. Particularly, for materials with larger performance differences such as aluminum/steel, aluminum/copper, aluminum/titanium, magnesium/copper and the like, in practical application scenes, the thicknesses of the adopted plates often have differences, and generally, the plates with lower strength (such as light alloys of aluminum, magnesium and the like) are thicker, and the plates with higher strength (such as steel, copper, titanium and the like) are thinner. For dissimilar materials with different thicknesses, FSW welding is carried out by adopting a conventional butt joint mode, the connection between the dissimilar materials is definitely limited by the thickness of a thin plate (such as steel, copper, titanium and the like) and the effective bonding area is insufficient, FSW welding is carried out by adopting a conventional lap joint mode, and a thick plate (such as light alloy of aluminum, magnesium and the like) is generally arranged on the thin plate (such as steel, copper, titanium and the like), so that the length of a stirring pin is longer (the thickness of the stirring pin is generally the same as or slightly smaller than that of the thick plate), the bottom of the stirring pin is subjected to intense friction of a high-strength plate (such as steel, copper, titanium and the like) in the welding process, abrasion or fracture is easy to occur, the thickness of a finally obtained connecting piece is the sum of the thicknesses of the two plates, and the obtained connecting piece occupies excessive longitudinal space when in use and is subjected to larger bending moment, and has poor overall performance. Disclosure of Invention In order to solve the defects of the prior art, the invention combines the prior art, and provides the stirring head for friction stir welding of the dissimilar materials with different thicknesses and the welding method, which can improve the welding performance between the dissimilar plates with different thicknesses. The technical scheme of the invention is as follows: The stirring head for friction stir welding of different materials with different thicknesses comprises a large shaft shoulder, a small shaft shoulder and a stirring pin which are coaxially arranged from top to bottom, wherein the large shaft shoulder and the small shaft shoulder are made of different materials. The diameters of the large shaft shoulder, the small shaft shoulder and the stirring needle are sequentially reduced. The length of the stirring pin is not greater than the thickness of the thin plate to be welded, specifically, the length of the stirring pin is equal to or slightly smaller than the thickness of the thin plate to be welded, and the sum of the lengths of the small shaft shoulder and the stirring pin is not greater than the thickness of the thick plate to be welded, namely, the sum of the lengths of the small shaft shoulder and the stirring pin is equal to or slightly smaller than the thickness of the thick plate to be welded. Preferably, the large shaft shoulder is made of H13 tool steel, and the small shaft shoulder is made of tungsten-rhenium alloy, so that the manufacturing cost is effectively controlled while the performance of key parts is ensured. The friction stir welding method for dissimilar materials with different thicknesses is characterized in that a step is processed on the edge of the length of a thick plate,