阅读说明：本技术 一种激光空间三维向下内螺旋点焊多层高强钢的方法 (Method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel ) 是由 王刚 郭浩然 张闰勃 付知易 于 2021-10-09 设计创作，主要内容包括：一种激光空间三维向下内螺旋点焊多层高强钢的方法,本发明涉及多层高强钢点焊方法领域。本发明要解决现有焊接接头强度降低的技术问题。方法：一、对待焊高强钢进行预处理；二、将高强钢多层搭接固定；三、采用激光飞行焊扫描振镜系统按螺旋线向内方向进行激光空间三维向下内螺旋点焊。本发明可以获得更大的宽深比,激光空间三维向下内螺旋点焊可以起到固定焊缝,减少焊接接头变形的作用,有效改善高强钢点焊接头变形的问题,实现有间隙多层高强钢的搭接焊接,增加接头强度,提高焊件整体温度,消除裂纹。本发明用于点焊多层高强钢。(The invention discloses a method for performing three-dimensional downward inner spiral spot welding on multilayer high-strength steel in a laser space, and relates to the field of spot welding methods for multilayer high-strength steel. The invention aims to solve the technical problem that the strength of the existing welding joint is reduced. The method comprises the following steps: firstly, preprocessing high-strength steel to be welded; secondly, overlapping and fixing the high-strength steel in multiple layers; and thirdly, performing laser space three-dimensional downward inner spiral spot welding in the inward direction of the spiral line by adopting a laser flight welding scanning galvanometer system. The invention can obtain larger width-depth ratio, the laser space three-dimensional downward inner spiral spot welding can play a role in fixing welding seams, reducing the deformation of welding joints, effectively improving the problem of the deformation of spot welding joints of high-strength steel, realizing the lap welding of gapped multilayer high-strength steel, increasing the joint strength, improving the integral temperature of a welding part and eliminating cracks. The invention is used for spot welding of the multilayer high-strength steel.)

1. A method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel is characterized by comprising the following steps:

firstly, polishing and cleaning the lap joint part of the high-strength steel to be welded to expose the metallic luster;

fixing the high-strength steel treated in the step one, and assembling in a multi-layer lap joint mode;

and thirdly, performing laser space three-dimensional downward internal spiral spot welding on the high-strength steel assembled in the second multi-layer lap joint mode according to the spiral line in the inward direction by adopting a laser flight welding scanning galvanometer system.

2. The method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel according to claim 1, wherein the thickness of the high-strength steel in the step one is 0.8-1.5 mm.

3. The method for laser space three-dimensional downward inner spiral spot welding of the multilayer high-strength steel according to claim 1, wherein the number of the second high-strength steel lap joints is 3-4, and the lap joint interval of the adjacent high-strength steels is 0.1-0.5 mm.

4. The method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel according to claim 1, wherein the laser power of the laser welding in the third step is 4-8 kW.

5. The method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel according to claim 1, wherein the diameter of a focused light spot of the laser welding in the third step is 0.4-0.8 mm; the defocusing amount is-3-0 mm.

6. The method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel according to claim 1, wherein the focal point rotation frequency of the laser welding in the third step is 10-60 Hz.

7. The method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel according to claim 1, wherein the maximum radius of the spiral rotation of the focus of the laser welding in the third step is 1.0-2.5 mm, and the minimum radius is 0.5-1.2 mm.

8. The method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel according to claim 1, wherein the spot welding time of the laser welding in the third step is 0.4-3.0 s.

9. The method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel according to claim 1, wherein the distance of vertical movement of the laser focus in the third step is 1-3 mm.

10. The method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel according to claim 1, wherein the residence time of the spiral center of the laser welding in the third step is 0.1-1 s.

Technical Field

The invention relates to the field of multilayer high-strength steel spot welding methods.

Background

At present, high-strength steel is gradually used for automobile body frames, the connection of the high-strength steel mainly refers to the lap joint of steel plates, and resistance spot welding and laser welding are main welding processes of the high-strength steel of the automobiles in order to achieve light weight of the automobiles. The spot welding process is the main welding process of high-strength steel of automobiles. In the automobile manufacturing process, there are usually many spot welds, typically around 5000 welds. The safety and durability of the automobile body are closely related to the spot-welded joint. Because the temperature is high in the spot welding process, the cooling speed is high after welding, the softening phenomenon of a heat affected zone is easy to occur, and the protection capability is reduced, the welded joint is easy to break in a spot welding joint stretching and shearing test, namely the spot welding joint cannot meet the use requirement, and the joint quality does not reach the standard. For the other two commonly used welding methods of the automobile body, namely laser welding and arc welding, the two methods have large heat input quantity and high welding temperature, and need a large amount of heat to melt metal, so that welding parameters and quality cannot be guaranteed, and other defects such as air holes, shrinkage cavities and the like are easily caused besides softening of a heat affected zone, thereby reducing the strength of a welding joint. The present invention is intended to solve the problems associated with conventional laser spot welding.

Disclosure of Invention

The invention provides a method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel, aiming at solving the technical problem of strength reduction of the existing welding joint.

A method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel specifically comprises the following steps:

firstly, polishing and cleaning the lap joint part of the high-strength steel to be welded to expose the metallic luster;

fixing the high-strength steel treated in the step one, and assembling in a multi-layer lap joint mode;

and thirdly, performing laser space three-dimensional downward internal spiral spot welding on the high-strength steel assembled in the second multi-layer lap joint mode according to the spiral line in the inward direction by adopting a laser flight welding scanning galvanometer system.

Further, the thickness of the high-strength steel in the step one is 0.8-1.5 mm.

And furthermore, in the second step, the number of the high-strength steel lapping layers is 3-4, and the lapping interval between adjacent high-strength steels is 0.1-0.5 mm.

Further, the laser power of the laser welding in the third step is 4-8 kW.

Further, the diameter of a focusing light spot of the laser welding in the third step is 0.4-0.8 mm; the defocusing amount is-3-0 mm.

Further, the focal point rotation frequency of the laser welding in the third step is 10-60 Hz.

Further, the maximum radius of the spiral rotation of the focus of the laser welding in the third step is 1.0-2.5 mm, and the minimum radius is 0.5-1.2 mm.

Further, in the third step, the spot welding time of the laser welding is 0.4-3.0 s.

And further, in the third step, the vertical movement distance of the laser focus is 1-3 mm.

And further, the residence time of the center of the spiral line of the laser welding in the step three is 0.1-1 s.

The high-strength steel is domestic NP550 bulletproof steel, and the tensile strength reaches 1600MPa

The invention has the beneficial effects that:

the method is optimized and improved on the basis of relatively stable laser spiral welding in the prior art, compared with the traditional external spiral plane laser welding, the method changes the direction of a laser spiral line, uses a laser galvanometer system to carry out laser internal spiral welding, simultaneously changes the traditional plane two-dimensional spiral line mode, is matched with the movement of a robot, and introduces a spatial three-dimensional downward path into the welding process. And secondly, the internal spiral three-dimensional downward laser spot welding can realize the lap welding of the gapped multilayer high-strength steel and increase the joint strength. And thirdly, for high-strength steel, welding cracks are the main welding defects, the overall temperature of a weldment can be improved by using an internal spiral welding mode and the process step of finally staying a laser beam at the center of a spiral line, and the method has great significance for eliminating the cracks, so that the laser space three-dimensional downward internal spiral spot welding of the multilayer high-strength steel has obvious production advantages.

The invention is used for spot welding of the multilayer high-strength steel.

Drawings

FIG. 1 is a schematic view of the assembly of the multi-layer lap joint method according to step two of the preferred embodiment;

FIG. 2 is a weld scan line diagram of helical spot welding according to step three of the present embodiment, wherein R is₁Representing the maximum radius of rotation of the focal helix, R₂Represents the minimum radius of the focal spiral rotation;

FIG. 3 is a schematic structural diagram of a scanning galvanometer system for laser flight welding according to one embodiment, where 1 represents a laser, 2 represents a laser control system, 3 represents a robot control system, 4 represents a six-axis linkage robot, 5 represents a to-be-welded lapping plate, and 6 represents a flight galvanometer control system;

FIG. 4 is a photograph of a lap weld of the first embodiment welded to high strength steel;

FIG. 5 is a photograph of the microstructure of the center of a lap weld of the first example welded to high strength steel.

Detailed Description

The technical solution of the present invention is not limited to the specific embodiments listed below, and includes any combination of the specific embodiments.

The first embodiment is as follows: a method for laser space three-dimensional downward inner spiral spot welding of multilayer high-strength steel is specifically carried out according to the following steps:

firstly, polishing and cleaning the lap joint part of the high-strength steel to be welded to expose the metallic luster;

fixing the high-strength steel treated in the step one, and assembling in a multi-layer lap joint mode;

and thirdly, performing laser space three-dimensional downward internal spiral spot welding on the high-strength steel assembled in the second multi-layer lap joint mode according to the spiral line in the inward direction by adopting a laser flight welding scanning galvanometer system.

The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: step one, the thickness of the high-strength steel is 0.8-1.5 mm. The rest is the same as the first embodiment.

The third concrete implementation mode: the present embodiment differs from the first or second embodiment in that: and step two, the number of the high-strength steel lapping layers is 3-4, and the lapping interval of adjacent high-strength steels is 0.1-0.5 mm. The other is the same as in the first or second embodiment.

The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: and step three, the laser power of the laser welding is 4-8 kW. The others are the same as in one of the first to third embodiments.

The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is: thirdly, the diameter of a focusing light spot of the laser welding is 0.4-0.8 mm; the defocusing amount is-3-0 mm. The other is the same as one of the first to fourth embodiments.

The sixth specific implementation mode: the difference between this embodiment and one of the first to fifth embodiments is: and step three, the focal point rotation frequency of the laser welding is 10-60 Hz. The other is the same as one of the first to fifth embodiments.

The seventh embodiment: the difference between this embodiment and one of the first to sixth embodiments is: and step three, the maximum radius of the spiral rotation of the focus of the laser welding is 1.0-2.5 mm, and the minimum radius is 0.5-1.2 mm. The other is the same as one of the first to sixth embodiments.

The specific implementation mode is eight: the present embodiment differs from one of the first to seventh embodiments in that: and thirdly, the spot welding time of the laser welding is 0.4-3.0 s. The other is the same as one of the first to seventh embodiments.

The specific implementation method nine: the present embodiment differs from the first to eighth embodiments in that: and step three, the vertical movement distance of the laser focus is 1-3 mm. The rest is the same as the first to eighth embodiments.

The detailed implementation mode is ten: the present embodiment differs from one of the first to ninth embodiments in that: and step three, the residence time of the center of the spiral line of the laser welding is 0.1-1 s. The other is the same as one of the first to ninth embodiments.

The residence time at the center of the spiral line is the residence time at the end point in fig. 2.

The following examples were used to demonstrate the beneficial effects of the present invention:

the first embodiment is as follows:

the embodiment of the invention relates to a method for performing three-dimensional downward inner spiral spot welding on multilayer high-strength steel in a laser space, which comprises the following steps of:

firstly, polishing and cleaning the lap joint part of the high-strength steel to be welded to expose the metallic luster; the processing range is within 50mm of the area to be welded;

fixing the high-strength steel treated in the step one, and assembling in a multi-layer lap joint mode;

and thirdly, performing laser space three-dimensional downward inner spiral spot welding on the high-strength steel subjected to multilayer lap joint assembly in the second step by adopting a laser flight welding scanning galvanometer system to match a robot mechanical arm in the inward direction of the spiral line.

Step one, the thickness of the high-strength steel is 0.8 mm.

And step two, the number of the high-strength steel lap joints is 3, and the lap joint interval of adjacent high-strength steels is 0.1 mm.

The laser power of the laser welding in the third step is 4 kW; the diameter of the focusing light spot is 0.4 mm; the defocusing amount is 0 mm; the focal point rotation frequency is 10 Hz; the maximum radius of the spiral rotation of the focus is 1.0mm, and the minimum radius is 0.5 mm; the spot welding time was 0.4 s.

And step three, the laser welding robot mechanical arm moves downwards for a distance of 1mm, namely the distance of the vertical movement of the laser focus is 1 mm.

And step three, the residence time of the center of the spiral line of the laser welding is 0.1 s.

The tensile strength of the high-strength steel welded in this example was 1301 MPa.

The photograph of the lap weld of the high-strength steel welded in this example is shown in fig. 4;

the photograph of the microstructure of the center of the lap weld of the high-strength steel welded according to the present example is shown in fig. 5;

the welding seam pictures show that the steel plates are well lapped and fused in gaps, no cracks are formed, and no welding defects are generated.

The laser space three-dimensional downward inner spiral spot welding multilayer high-strength steel solves the problems of poor fusion of steel plates in a gap lap joint and deformation of joints in a welding process, effectively controls the formation of cracks, reduces the generation of welding defects, and improves the production quality and efficiency to a certain extent.

Example two:

the embodiment of the invention relates to a method for performing three-dimensional downward inner spiral spot welding on multilayer high-strength steel in a laser space, which comprises the following steps of:

firstly, polishing and cleaning the lap joint part of the high-strength steel to be welded to expose the metallic luster; the processing range is within 50mm of the area to be welded;

fixing the high-strength steel treated in the step one, and assembling in a multi-layer lap joint mode;

and thirdly, performing laser space three-dimensional downward inner spiral spot welding on the high-strength steel subjected to multilayer lap joint assembly in the second step by adopting a laser flight welding scanning galvanometer system to match a robot mechanical arm in the inward direction of the spiral line.

Step one, the thickness of the high-strength steel is 1.5 mm.

And step two, the number of the high-strength steel lap joints is 4, and the lap joint interval of adjacent high-strength steels is 0.2 mm.

The laser power of the laser welding in the third step is 8 kW; the diameter of the focusing light spot is 0.6 mm; the defocusing amount is-3 mm; the focal point rotation frequency is 10 Hz; the maximum radius of the spiral rotation of the focus is 2.5mm, and the minimum radius is 1.2 mm; the spot welding time was 3.0 s.

And step three, the laser welding robot mechanical arm moves downwards for a distance of 1mm, namely the distance of the vertical movement of the laser focus is 1 mm.

And step three, the residence time of the center of the spiral line of the laser welding is 0.1 s.