阅读说明：本技术 材料连续继承填充摩擦点焊工具及方法 (Continuous material succession filling friction spot welding tool and method ) 是由 封小松 王瑾 李送斌 宋学成 崔凡 赵慧慧 于 2019-11-25 设计创作，主要内容包括：本发明涉及材料连续继承填充摩擦点焊工具及方法,摩擦点焊工具包括由外到内依次嵌套的压紧套、中空回填内套环和中心轴；中心轴包括本体和焊接部位,焊接部位固连于本体一端；本体为圆柱体,本体的外径尺寸与中空回填内套环的内径尺寸相匹配；焊接部位的横截面的面积小于本体的横截面的面积,在焊接部位的外侧壁与中空回填内套环的内侧壁之间形成能容纳连续继承填充材料的空腔。本发明的材料连续继承填充摩擦点焊工具及方法,解决传统回填式摩擦点焊技术套环下压方式存在的焊点竖直界面弱连接、中心轴下压方式存在的下压阻力大、焊点回填成形不良导致的焊点力学性能一致性差、可靠性不足等问题。(The invention relates to a friction spot welding tool and a method for continuously inheriting and filling materials, wherein the friction spot welding tool comprises a pressing sleeve, a hollow backfill inner sleeve ring and a central shaft which are sequentially nested from outside to inside; the central shaft comprises a body and a welding part, and the welding part is fixedly connected to one end of the body; the body is a cylinder, and the outer diameter of the body is matched with the inner diameter of the inner sleeve ring of the hollow backfill; the area of the cross section of the welding part is smaller than that of the cross section of the body, and a cavity capable of containing continuous inherited filling materials is formed between the outer side wall of the welding part and the inner side wall of the inner sleeve ring of the hollow backfill. The tool and the method for continuously inheriting and filling the friction spot welding with the material solve the problems of weak connection of a welding spot vertical interface in a lantern ring pressing mode, large pressing resistance in a central shaft pressing mode, poor welding spot mechanical property consistency and poor reliability caused by poor welding spot backfill forming and the like in the traditional backfill type friction spot welding technology.)

1. The material continuous succession filling friction spot welding tool comprises a pressing sleeve, a hollow backfill inner sleeve ring and a central shaft which are sequentially nested from outside to inside; the central shaft is characterized by comprising a body and a welding part, wherein the welding part is fixedly connected to one end of the body; the body is a cylinder, and the outer diameter of the body is matched with the inner diameter of the inner sleeve ring of the hollow backfill; the area of the cross section of the welding part is smaller than that of the cross section of the body, and a cavity capable of containing continuous inherited filling materials is formed between the outer side wall of the welding part and the inner side wall of the hollow backfill inner sleeve ring.

2. A continuous succession filling friction spot welding tool according to claim 1 wherein said weld is centrally symmetrical in cross section, at least two of said cavities being formed between an outer side wall of said weld and an inner side wall of said inner collar of said hollow backfill.

3. The material continuous succession filling friction spot welding tool of claim 1, characterized in that the pattern of the cross section of the weld is a regular triangle, a cross, a knife edge or a centrosymmetric crescent.

4. A continuous succession filling friction spot welding tool according to claim 1 wherein the end face of the central axis weld remote from the body has at least one continuous line or plane which rotates to scan a plane which completely covers the cylindrical surface of the central axis.

5. The material continuous succession filling friction spot welding tool of claim 1, wherein the top end face of said cavity is a closed, smooth flat surface.

6. The continuous succession filling friction spot welding tool of material as claimed in claim 1, wherein the length of the welding site in the axial direction is 1.2 to 1.5 times the welding depth.

7. A continuous succession filling friction spot welding method of material, characterized in that a continuous succession filling friction spot welding tool of material according to any of claims 1 to 7 is used, the friction spot welding method comprising:

1) the end face of the welding part of the central shaft, the welding end face of the hollow backfill inner sleeve ring and the bottom end face of the compression sleeve are flush and are pressed on a workpiece to be welded at the same time, and the cavity is filled with a welding parent metal homogeneous material; before or after the welded workpiece is compressed, the hollow backfill inner sleeve ring and the central shaft are driven to rotate to drive materials in the cavity to rotate together, so that the surface of the welded workpiece is rubbed;

2) keeping the central shaft and the hollow backfill inner sleeve ring rotating, driving the hollow backfill inner sleeve ring to move upwards along the axis, driving the central shaft to move downwards along the axis, and driving the materials in the cavity to be pressed into the welded workpiece together; in the process of pressing the central shaft downwards, part of the welded workpiece material and part of the material in the cavity are extruded out and enter a space left by the hollow retraction inner lantern ring for retraction to flow and mix, and part of the welded workpiece material and part of the material in the cavity flow and mix below a welding part;

3) after the central shaft is pressed down to a preset position, the central shaft and the hollow backfill inner sleeve ring rotate, the central shaft moves upwards along the axis, and the hollow backfill inner sleeve ring moves downwards along the axis; backfilling the extruded material to a space left in the welded workpiece due to the central shaft; the welding end face of the rotating hollow backfill inner sleeve ring continuously rubs the extruded material, and the shearing and rubbing motion is kept between the rotary boundary formed by the rotation of the welding part of the central shaft and the extruded material and the welded parent metal, so that the continuous heating of the welding process is realized;

4) when the end face of the welding position of the central shaft, the welding end face of the hollow backfill inner sleeve ring and the bottom end face of the pressing sleeve are leveled again, the central shaft and the hollow retraction inner sleeve ring stop moving axially, and the central shaft and the hollow retraction inner sleeve ring press materials at a welding point and keep rotating; and (3) trimming the surface of the welding spot by a rotating surface formed by rotating the end surface of the central shaft, simultaneously cutting the adhesion between the material refilled in the cavity and the surface of the welding spot, and then lifting the friction spot welding tool to obtain the welding spot with a smooth surface.

8. The continuous succession filling friction spot welding method of the material according to claim 7, characterized in that the welded workpiece is formed by overlapping at least two welding pieces, and in the step 3), the preset position is less than 0.3mm of the upper surface of the lowermost welding piece.

9. The method for friction spot welding by continuous succession of materials according to claim 8, wherein the material filling the cavity is the material left by the last welding, the material is mixed with the material of the workpiece to be welded in a flowing mode during the current welding process, the cavity is refilled with the material after the welding, and the material in the cavity is transferred to the next welding process, so that the continuous succession of the materials among different welding points is realized.

Technical Field

The invention relates to a lap spot welding technology, in particular to a tool and a method for continuous succession filling friction spot welding of materials.

Background

In the fields of aerospace, automobiles, rail transit and the like, the aluminum alloy structure is more and more widely used due to the requirement of light weight, and the aluminum alloy point connecting structure is widely concerned as an important light-weight high-strength structure. Conventional attachment methods for such structures include welding, mechanical attachment, and the like. The welding is an ideal connecting means for the structure because of higher connecting strength, better corrosion resistance, simple process, structure weight reduction performance and the like. However, in the conventional resistance spot welding method, due to the existence of an oxide film on the surface of the aluminum alloy and the characteristics of high heat conductivity, high electric conductivity and the like of the aluminum alloy, the reliability of the resistance spot welding of the aluminum alloy is difficult to obtain an ideal effect, and the application of the resistance spot welding method is limited by the problems. Solid phase welding techniques have received much attention because they avoid many of the problems associated with welding methods based on melting of materials. The friction stir spot welding technology and the backfill type friction spot welding technology are typical solid phase welding technologies.

The friction stir spot welding technology is developed from the friction stir welding technology, and has the advantages that the welding process is simple and efficient, an exit hole of a stirring pin is left on the surface of a workpiece, the connection performance of a welding spot is reduced due to the existence of the exit hole, and the friction stir spot welding technology is applied to occasions with low requirements on the surface and the mechanical property of the welding spot. The backfill type friction spot welding technology is a solid phase spot welding technology developed by Germany GKSS research center (HZG), a welding tool of the backfill type friction spot welding technology consists of a central shaft, an inner sleeve ring and a pressing sleeve, the pressing sleeve presses and restrains a welded workpiece, and during welding, the inner sleeve ring rotates and presses downwards, and the central shaft is drawn back to accommodate materials extruded by the pressing of the inner sleeve ring; and when the inner sleeve ring is pressed down to a preset depth, the inner sleeve ring starts to be drawn back, the central shaft is pressed down at the moment, the extruded material is backfilled into the workpiece, and finally the welding point with the smooth surface is obtained. The welding method solves the problem that keyhole exists on the surface of the welding spot in the friction stir spot welding method, but the weak bonding defect is easily generated at the position because the contact time of the material and the base material around the welding spot is short, the temperature is low and no material is transferred when the material is backfilled. The defects cause low positive tensile strength and poor consistency of welding spots, and limit the engineering application of the welding spots. In the welding method for pressing the central shaft downwards, because the end face of the central shaft is a plane and the friction linear velocity is low, the welding method can be greatly resisted in the pressing process; on the other hand, the amount of material filled from both sides to the center is relatively large, and it is difficult to obtain a well-formed appearance of the solder joint. Therefore, in general, the filling type friction spot welding is more performed by pressing down the inner collar.

In order to reduce the problem of higher resistance of the center shaft pressing welding mode and enhance the material stirring effect in the welding process, the improved filling type friction spot welding method (ZL 201410077971.6; ZL201410077972.0) designs the center shaft into a non-cylindrical shape and matches with the corresponding lantern ring shape for welding. The method enhances the material flow driving force in the welding process to a certain extent, but the material flow space is not fundamentally changed compared with the original filling type friction spot welding, and the special-shaped welding central shaft and the inner lantern ring have difficulties in the aspects of processing cost and processing matching precision.

Disclosure of Invention

The invention aims to provide a tool and a method for continuously inheriting and filling friction spot welding of a material, and solves the problems of poor consistency of mechanical properties of welding spots, insufficient reliability and the like caused by weak connection of vertical interfaces of the welding spots in the traditional backfill type friction spot welding technology.

In order to achieve the aim, the invention provides a material continuous succession filling friction spot welding tool, which comprises a pressing sleeve, a hollow backfill inner sleeve ring and a central shaft which are sequentially nested from outside to inside; the central shaft comprises a body and a welding part, and the welding part is fixedly connected to one end of the body; the body is a cylinder, and the outer diameter of the body is matched with the inner diameter of the inner sleeve ring of the hollow backfill; the area of the cross section of the welding part is smaller than that of the cross section of the body, and a cavity capable of containing continuous inherited filling materials is formed between the outer side wall of the welding part and the inner side wall of the hollow backfill inner sleeve ring.

The material is continuously inherited to a filling friction spot welding tool, wherein the cross section of the welding part is in a central symmetry shape, and at least two cavities are formed between the outer side wall of the welding part and the inner side wall of the hollow backfill inner sleeve ring.

The material is continuously inherited to a filling friction spot welding tool, wherein the pattern of the cross section of the welding part is in a regular triangle shape, a cross shape, a blade shape or a centrosymmetric crescent shape.

The material continuously inherits the filling friction spot welding tool, wherein the end face of the welding part of the central shaft far away from the body is at least provided with a continuous line or plane, and the scanned surface can completely cover the cylindrical surface of the central shaft during rotation.

The material continuously inherits the filling friction spot welding tool, wherein the top end surface of the cavity is a closed and smooth plane and can drive the material in the cavity to flow.

The material is continuously inherited to a filling friction spot welding tool, wherein the length of the welding position in the axial direction is 1.2-1.5 times of the welding depth.

The invention provides another technical scheme which is a continuous succession filling friction spot welding method for materials, wherein the continuous succession filling friction spot welding tool for the materials is adopted, and the friction spot welding method comprises the following steps:

1) the end face of the welding part of the central shaft, the welding end face of the hollow backfill inner sleeve ring and the bottom end face of the compression sleeve are flush and are pressed on a workpiece to be welded at the same time, and the cavity is filled with a welding parent metal homogeneous material; before or after the welded workpiece is compressed, the hollow backfill inner sleeve ring and the central shaft are driven to rotate to drive materials in the cavity to rotate together, so that the surface of the welded workpiece is rubbed;

2) keeping the central shaft and the hollow backfill inner sleeve ring rotating, driving the hollow backfill inner sleeve ring to move upwards along the axis, driving the central shaft to move downwards along the axis, and driving the materials in the cavity to be pressed into the welded workpiece together; in the process of pressing the central shaft downwards, part of the welded workpiece material and part of the material in the cavity are extruded out and enter a space left by the hollow retraction inner lantern ring for retraction to flow and mix, and part of the welded workpiece material and part of the material in the cavity flow and mix below a welding part;

3) after the welding position of the central shaft is pressed down to a preset position, the central shaft and the hollow backfill inner lantern ring rotate, the central shaft moves upwards along the axis, and the hollow backfill inner lantern ring moves downwards along the axis; backfilling the extruded material to a space left in the welded workpiece due to the central shaft; the welding end face of the rotating hollow backfill inner sleeve ring continuously rubs the extruded material, and the shearing and rubbing motion is kept between the rotary boundary formed by the rotation of the welding part of the central shaft and the extruded material and the welded parent metal, so that the continuous heating of the welding process is realized;

4) when the end face of the welding position of the central shaft, the welding end face of the hollow backfill inner sleeve ring and the bottom end face of the pressing sleeve are leveled again, the central shaft and the hollow retraction inner sleeve ring stop moving axially, and the central shaft and the hollow retraction inner sleeve ring press materials at a welding point and keep rotating; and (3) trimming the surface of the welding spot by a rotating surface formed by rotating the end surface of the welding part of the central shaft, simultaneously cutting the adhesion between the material refilled in the cavity and the surface of the welding spot, and then lifting a friction spot welding tool to obtain the welding spot with a smooth surface.

The continuous succession filling friction spot welding method for the material is characterized in that a welded workpiece is formed by overlapping at least two welding pieces, and in the step 3), the preset position is that the upper surface of the welding piece at the lowest layer is less than 0.3 mm.

The material continuous succession filling friction spot welding method is characterized in that the material for filling the cavity is the material left by the last welding, the material and the material of the workpiece to be welded flow and mix in the welding process, the cavity is refilled with the material after welding, and the material in the cavity is transferred to the next welding process, so that the continuous succession of the materials among different welding points is realized.

Compared with the prior art, the invention has the following characteristics and advantages:

the tool and the method for continuously inheriting and filling the friction spot welding with the materials adopt a welding mode of pressing the central shaft downwards and backfilling the inner sleeve ring, and solve the problems of insufficient connection strength, low consistency and the like of the backfilling materials and the friction interface around a welding point caused by backfilling the central shaft in the traditional backfilling type friction spot welding, namely the tool and the method can completely solve the problem of weak connection of the vertical interface of the welding point in the prior art; the central shaft consists of a body and a welding part, the area of the cross section of the welding part is smaller than that of the cross section of the body, namely, a welding tool with smaller pressing-in area and smaller pressing-in volume is adopted to press in a welded workpiece, so that the problems that the tool is deformed due to overlarge resistance when the traditional welding tool is pressed in the welded workpiece, the backfilling defect is caused due to overlarge pressing-in volume (overlarge volume of extruded material) and the like are solved;

according to the tool and the method for continuously inheriting and filling friction spot welding of the material, the welding position adopts the end surface shapes of a triangle, a cross, a knife edge, a crescent and the like, so that the internal resistance of the material pressed in is greatly reduced, the welding efficiency is improved, good backfilling of the material is realized, and the surface of a welding spot is smooth;

the invention provides a material continuous succession filling friction spot welding method, which is characterized in that a welding tool cavity is filled with a material which is completely the same as a welded workpiece material and is left in the last welding, and during the current welding, the material enters a plastic state to be mixed with the welded workpiece material, the mixing drives the welded material to flow, and an instantaneous cavity caused by rotary stirring after a central shaft is pressed downwards can be filled with the filling material and the welded workpiece material is extruded;

the tool and the method for continuous succession filling friction spot welding of the material are not only suitable for spot welding between low-melting-point metals (such as aluminum alloy and magnesium alloy), but also suitable for spot welding between the low-melting-point metals and high-melting-point metals (steel and titanium alloy), and effective and efficient friction processing can be performed on the high-melting-point metals by pressing the central shaft downwards, so that interface reaction is promoted, and welding spots with high strength and good reliability are formed.

Drawings

The material continuous succession filling friction spot welding tool and method of the present invention are given by the following examples and figures.

FIG. 1 is a schematic diagram of a welding preparation stage in the continuous succession filling friction spot welding method of the material of the present invention.

FIG. 2 is a schematic diagram of a welding pressing stage in the continuous succession filling friction spot welding method of the material of the present invention.

FIG. 3 is a schematic diagram illustrating a welding backfill stage in the continuous succession filling friction spot welding method of the material of the present invention.

FIG. 4 is a schematic diagram of the welding spot trimming and welding ending stage in the continuous succession filling friction spot welding method of the material of the present invention.

FIG. 5 is a schematic cross-sectional view of a welding portion according to a first embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a welding portion according to a second embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view of a welded portion according to a third embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view of a welding portion according to a fourth embodiment of the present invention.

FIG. 9 is a cross-sectional profile of a solder joint in an embodiment of the invention.

Detailed Description

The material continuous succession fill friction spot welding tool and method of the present invention will be described in further detail below in conjunction with fig. 1-9.

FIG. 1 is a schematic diagram of a welding preparation stage in a continuous succession filling friction spot welding method of a material according to the present invention; FIG. 2 is a schematic diagram of a welding pressing stage in the continuous succession filling friction spot welding method of the material of the present invention; FIG. 3 is a schematic diagram illustrating a welding backfill stage in the continuous succession filling friction spot welding method of the material of the present invention; FIG. 4 is a schematic diagram illustrating the finishing stages of spot welding and welding in the continuous succession filling friction spot welding method of the present invention.

Referring to fig. 1 to 4, the continuous succession filling friction spot welding tool for the material comprises a pressing sleeve 3, a hollow backfill inner sleeve ring 2 and a central shaft 1 which are sequentially nested from outside to inside; the central shaft 1 comprises a body and a welding part 4, and the welding part 4 is fixedly connected to one end of the body; the body is a cylinder, and the outer diameter of the body is matched with the inner diameter of the hollow backfill inner sleeve ring 2; the area of the cross section of the welding position 4 (namely the radial area) is smaller than that of the cross section of the body, and a cavity capable of containing continuous inherited filling materials 7 is formed between the outer side wall of the welding position 4 and the inner side wall of the hollow backfill inner sleeve ring 2; the cross section of the welding part 4 is in a centrosymmetric pattern, and at least two cavities are formed between the outer side wall of the welding part 4 and the inner side wall of the hollow backfill inner lantern ring 2.

The central shaft 1 can rotate and move relative to the hollow backfill inner sleeve ring 2 (the central shaft moves in the axial direction); the hollow backfill inner sleeve ring 2 can rotate and move (move along the axis direction of the central shaft) relative to the pressing sleeve 3.

The depth of the cavity (length along the axis direction of the central shaft) is related to the welding depth, and preferably, the depth of the cavity is 1.2 times of the welding depth; the top end surface of the cavity is a closed and smooth surface, and the material in the cavity can be driven to flow along with the rotation of the central shaft 1.

Referring to fig. 5, in the first embodiment, the cross section of the welding part 4 is regular triangle, that is, a regular triangle cylinder is processed at one end of the body, and three cavities capable of containing continuous inherited filling materials 7 are formed between the outer side wall of the regular triangle cylinder and the inner side wall of the hollow backfill inner sleeve ring 2. The material of the first embodiment has better wear resistance by continuously succeeding the filling friction spot welding tool.

Referring to fig. 6, in the second embodiment, the cross section of the welding part 4 is cross-shaped, that is, a cross-shaped column is processed at one end of the body, and four cavities capable of containing continuous inherited filling materials 7 are formed between the outer side wall of the cross-shaped column and the inner side wall of the hollow backfill inner sleeve ring 2. The material of the second embodiment continuously inherits the filled friction spot welding tool with less resistance to depression, greater material flow space.

Referring to fig. 7, in the third embodiment, the cross section of the welding part 4 is a blade shape, the middle of the blade shape is thin, and the two ends of the blade shape are thick, namely, a blade-shaped cylinder is processed at one end of the body, and two cavities capable of containing continuous inherited filling materials 7 are formed between the outer side wall of the blade-shaped cylinder and the inner side wall of the hollow backfill inner sleeve ring 2. The material of the third embodiment continuously inherits the filling friction spot welding tool to have small press-down resistance, and simultaneously can also take the wear resistance and the strength of the welding tool into consideration.

Referring to fig. 8, in the fourth embodiment, the cross section of the welding portion 4 is a central symmetrical crescent, that is, a central symmetrical crescent is processed at one end of the body, and two cavities capable of containing the continuous inherited filling material 7 are formed between the outer side wall of the central symmetrical crescent and the inner side wall of the hollow backfill inner sleeve ring 2. The material continuous succession filling friction spot welding tool of the fourth embodiment has a strong circumferential material transfer capability, and the rigidity of the welding part 4 is high, so that the material continuous succession filling friction spot welding tool has a strong stirring effect on the material of the welding area.

Before formal welding, trial welding is carried out on a test board which has the same material and the same state as the welded material, and after trial welding, the cavity is filled with the welded material.

FIG. 1 shows a welding preparation stage, in which an upper plate 10 of a workpiece to be welded and a lower plate 11 of the workpiece to be welded are overlapped to form two plate materials; at the moment, a cavity formed by the outer side wall of the welding part 4, the top end surface 5 and the inner side wall 12 of the hollow backfill inner sleeve ring is filled with the material which is subjected to the previous welding (trial welding); continuously inheriting the end face of the filling material 7 far away from the body, the end face of the welding part 4 far away from the body, the welding end face 13 of the hollow backfill inner sleeve ring 2 and the bottom end face of the pressing sleeve 3 to be flush, placing the workpiece to be welded below a friction spot welding tool, enabling the axes of the pressing sleeve 3, the hollow backfill inner sleeve ring 2 and the central shaft 1 to be vertical to the surface of the workpiece to be welded, and enabling the position to be welded to be located under the friction spot welding tool; the friction spot welding tool and the continuous succession filling material 7 are integrally pressed down to the surface of the workpiece to be welded, before the workpiece is compressed or after enough pressing force is ensured between the pressing sleeve 3 and the workpiece to be welded, the hollow backfill inner sleeve ring 2 and the central shaft 1 are driven to rotate at high speed (the continuous succession filling material 7 is driven to rotate at high speed), so that the surface of the workpiece to be welded is rubbed, and the local material on the surface of the workpiece to be welded enters a plastic state.

FIG. 2 shows a welding pressing-down stage, in which the central shaft 1 and the hollow backfill inner sleeve ring 2 are kept rotating at a high speed, and meanwhile, the central shaft 1 (with the continuous inherited filling material 7) is driven to move downwards along the axis, a workpiece to be welded is pressed in, and the hollow backfill inner sleeve ring 2 is driven to move upwards along the axis; the rotation of the welding part 4 forms a welding part rotating boundary 6 (the material in the welding part rotating boundary 6 rotates with the welding part 4 at a high speed), the outer part of the welding part rotating boundary 6 is extruded by the material of the welding workpiece and enters the space left by the hollow internal drawing lantern ring 2, meanwhile, the continuous succession filling material 7 also enters the space left by the hollow internal lantern ring 2 by drawing under the action of the depression of the top of the cavity, and the two materials are mixed to form an extruded material 8; the partially continuous inherited filler material 7 is mixed with the flow of the workpiece material to be welded in the rotation space 9.

FIG. 3 shows a welding backfill stage, when the welding position 4 is pressed down to a preset position, the central shaft 1 starts to move back upwards while keeping rotating, the hollow backfill inner sleeve ring 2 moves downwards while keeping rotating, the extruded material 8 backfills to a space left in a workpiece to be welded due to the central shaft drawing back, and a cavity between the outer side wall of the welding position 4 and the inner side wall of the hollow backfill inner sleeve ring 2; the welding end face 13 of the rotating hollow backfill inner sleeve ring 2 continuously rubs the extruded material 8, the filling material 7 and the extruded material 8 are continuously attached, the central shaft 1 rotates at a high speed, so that the shearing motion is kept between the rotary boundary 6 of the welding position and the extruded material 8 and between the materials of the welding point 14, the continuous heating of the welding process is realized, and the materials of the welded area are kept in a plastic state.

Fig. 4 shows the welding point trimming and welding end stage, when the end face of the welding part 4 far from the body, the welding end face 13 of the hollow backfill inner sleeve ring 2 and the bottom end face of the pressing sleeve 3 are level again, the central shaft 1 and the hollow withdrawal inner sleeve ring 2 stop moving up and down (i.e. stop moving the axis), and the central shaft 1 and the hollow withdrawal inner sleeve ring 2 press the welded material and keep rotating; the central shaft 1 and the hollow withdrawing inner lantern ring 2 apply upsetting force to the welding spot 14, a revolution surface formed by the rotation of the end surface of the welding part 4 trims the surface of the welding spot 14, the revolution surface simultaneously cuts the adhesion between the continuous succession filling material 7 refilled at this time and the surface of the welding spot 14, and then the friction spot welding tool is lifted to obtain the welding spot 14 with a smooth surface.

The surface (i.e., the surface of revolution) of the end surface of the welding portion 4 away from the main body scanned during high-speed rotation should completely cover the surface of the weld spot 14, i.e., the area of the cross section of the center axis main body is equal to the area of the surface of the weld spot 14.

When the friction spot welding tool is in an initial state, the welding position 4 is far away from the end face of the body, the welding end face 13 of the hollow backfill inner sleeve ring 2 and the bottom end face of the pressing sleeve 3 are flush, the material for filling the cavity (namely the space between the outer side wall of the welding position and the inner side wall of the hollow backfill inner sleeve ring) is the material left by the last welding, the material and the material of the workpiece to be welded are mixed in a flowing mode in the welding process, the cavity is backfilled with the material after welding, the material in the cavity is transferred to the next welding process, and continuous succession of the materials among different welding spots is achieved.

The welded workpiece is formed by overlapping at least two welding pieces. As shown in fig. 1 to 4, the workpiece to be welded is formed by overlapping an upper plate 10 and a lower plate 11, the upper plate 10 is preferably an aluminum alloy, and the lower plate 11 may be a same-type or different-type aluminum alloy or other materials.

The pressing position of the welding part 4 is at least below 0.3mm of the upper surface of the lowest welding part.

As shown in fig. 9, in one embodiment, the upper plate 10 of the workpiece to be welded is 5a06 aluminum alloy, the lower plate 11 of the workpiece to be welded is 2219 aluminum alloy (T6 state), the end face of the welding portion 4 away from the main body is regular triangle, the diameter of the main body of the central shaft is 5.2mm, the welding rotation speed is 3000rpm, and the pressing depth of the welding portion 4 is 2.4 mm. As can be seen from FIG. 9, the weak connection with the vertical interface is completely eliminated by the welding spot, the tensile-shear strength test is carried out on the joint, the average shear strength of the welding spot is 223MPa, and the fracture position is located near the faying surface.

In conclusion, compared with the prior art, the material of the invention continuously inherits the filling friction spot welding technology and the welding tool thereof, innovatively adopts the design of reducing the volume of the welding tool and optimizing the shape, simultaneously enlarges the material flowing space of the welding area, comprehensively utilizes the heat generating effect of friction and shearing movement to weld, can obtain the welding spot with smooth surface and without the weak connection phenomenon of a vertical connection interface, has simple and high-efficiency welding process, and does not need to greatly change equipment.

The foregoing detailed description of the embodiments and specific examples is intended only to illustrate the inventive content of the present invention in order to better understand the present invention, but these descriptions should not be construed as limiting the present invention for any reason, including other embodiments in which the various features described in the different embodiments can be combined in any way, and similar features outside of this embodiment, unless explicitly stated to the contrary, should be understood as being applicable to any one embodiment, not just the described embodiment.