WO2020187260A1

WO2020187260A1 - Laser welding method

Info

Publication number: WO2020187260A1
Application number: PCT/CN2020/079968
Authority: WO
Inventors: 杨上陆; 陶武
Original assignee: 中国科学院上海光学精密机械研究所
Priority date: 2019-03-18
Filing date: 2020-03-18
Publication date: 2020-09-24
Also published as: CN111715998B; CN111715998A

Abstract

A laser welding method. The laser energy of multiple laser beams (21, 22) acts on the surface of an overlap joint material combination for a period of time to melt the material, and a weld joint (3) is formed after cooling and solidification, so as to achieve material connection. During the action, the laser beams remain unchanged in position or are moved arbitrarily within a circle having a diameter of 15 millimeters to obtain a large-size welding spot. The shape of the weld joint formed is a circular, elliptical, or arc-shaped contour. The number of the laser beams varies from 2 to 10, the laser beam spots may be in the shape of dots, annuli, polygons, or short lines, the diameter of the focused spot varies from 0.05 to 10 millimeters, the laser power varies from 0.1 to 50 kilowatts, the energy of the laser beams is output continuously or in the form of pulse, and the action duration ranges from 0.1 second to 10 seconds.

Description

A laser welding method

Technical field

The invention relates to a laser welding method and belongs to the technical field of welding.

Background technique

As a heat source, laser has been used in material welding for more than 40 years. It can weld most metal materials and some non-metal materials, such as plastics, ceramics, and glass. The welding methods using laser include pulsed laser spot welding, pulsed laser spot welding lap joint formation seam welding, continuous laser seam welding, continuous laser spot welding through galvanometer scanning, etc. The laser energy comes from a single laser beam, and the welding efficiency is The scope of application is limited.

For example, in the automotive industry, lap welding of uncoated steel plates or galvanized plates is a common welding combination, and the traditional welding method is resistance spot welding. Resistance spot welding is a double-sided welding method. At the same time, a larger diameter electrode cap (usually 16 mm or 19 mm) is required, which requires sufficient operating space and a flange with sufficient width for welding, which is not conducive to Car weight loss. In addition, resistance spot welding requires concentrated current to generate resistance heat through the overlapped plates. Therefore, on the one hand, the energy consumption is high and only a small weld nugget size (usually 5-7 mm in diameter) can be obtained, on the other hand, the welding spot It is necessary to ensure a sufficient distance between them (usually about 25 mm) to avoid current shunting, and the small-sized solder joints and large-spacing distribution are not conducive to improving the stiffness and NVH performance of the vehicle. Laser welding is a single-sided welding method that can achieve continuous welds. It has replaced resistance spot welding in parts of the car body, such as the welding of the roof and side walls, and replaced the overlap resistance spot welding with butt laser brazing. However, laser welding of galvanized steel sheets will face great challenges in the lap combination. The presence of low-boiling zinc vapor will cause defects such as spatter holes during the welding process, resulting in welding failure. The existing method is to use a pre-treatment process to create a gap between the overlapped plates, leaving a channel for the zinc vapor to escape, and then welding. However, this method requires additional investment in fixed assets to establish a pre-processing workstation, and even if the pre-processing method is used, it can only be welded in short-line, C-shaped, S-shaped and other weld shapes. This type of welding form has limited joint strength. , So the application site is limited.

With the development of laser and optical technology and automated control technology, it has become possible to achieve multi-beam laser output through a single laser source and laser head, or to control multiple laser beams by coordinating multiple laser heads. The method of the present invention aims to utilize multiple laser energy Welding of overlapping plates. This welding method can solve the problems and limitations of the existing welding methods mentioned above. For example, it can realize the direct welding of galvanized steel sheet by lap joint, without the need of pre-treatment process; and can realize large-size round spot shape welding seam, and improve the joint strength. Thereby expanding the application range of laser welding.

Summary of the invention

The purpose of the present invention is to provide a laser welding method, which makes the surface of the solder joints have good surface quality and large solder joints, at the same time reduces energy loss, improves efficiency, and is beneficial to use under high cycle conditions in actual production.

The purpose of the present invention is achieved through the following technical solutions:

The invention applies the laser energy of multiple laser beams to the combined surface of the overlapping material for a period of time to melt the material and form a weld after cooling and solidification to realize the material connection; the number of the multiple laser beams varies from 2 to 10, and the light spot The shapes include dots, rings, polygons or short-line shapes, preferably a dot spot, the diameter of the focused spot varies from 0.05 mm to 10 mm, the laser power varies from 0.1 kilowatts to 50 kilowatts, and the beam energy is in continuous or pulsed form Output, the action time range is 0.1 seconds to 10 seconds. During the action, the beam position remains the same or moves arbitrarily within a 15 mm diameter circle to obtain large-size solder joints. The resulting weld shape includes round, oval or arc. contour.

In another preferred embodiment, the light beam originates from a single laser head, and multiple laser beams are output by means of spot shaping or multi-fiber input.

In another preferred embodiment, multiple laser beams are output by two or more laser heads.

In another preferred example, multiple laser energy is applied to the surface of the material, and each laser beam has its own independent spot shape, or presents the same spot shape. The spot shape is preferably a dot, ring, polygon, short line, and Other shapes that may be obtained through the laser optical transmission system.

In another preferred example, the multiple laser energy output modes are continuous output or pulse output, and different laser beams exhibit the same or different output modes at the same time.

In another preferred example, the relative position of the multiple beams remains unchanged during the action period, or can be moved arbitrarily within a certain range, and the moving range is preferably within a circle with a diameter of 15 mm. For multiple laser beams output by a single laser head, the axis of each laser beam is at the same position or distributed within the above-mentioned moving range. Multiple laser beams output by multiple laser heads act on the same position or different positions within the above-mentioned moving range.

In another preferred example, the multiple laser energy has its own independent focal spot diameter and energy density during the action process, and the focal spot diameter remains unchanged during the entire laser action time range, or in the range of 0.05 mm to 10 mm The internal variation is preferably 0.5 mm to 3.0 mm. The energy density remains the same or changes with the laser power. The laser power varies from 0.1 kW to 50 kW, preferably from 0.5 kW to 20 kW.

In another preferred embodiment, when the multiple laser beams are dual laser beams, the beam spacing is 2-6 mm.

In another preferred embodiment, the diameter of the large-size solder joint is 10-20 mm.

In another preferred embodiment, the energy loss required by the dual laser beams is reduced by more than 30% compared with the single beam, and the efficiency is doubled.

In another preferred embodiment, the welding process provides shielding gas to the welding area.

In another preferred embodiment, the soldering process adds solder to the soldering area.

In another preferred example, for the multiple laser beams acting on the surface of the material, the number of beams remains fixed during the entire laser time range, or the number of beams changes, gradually increases, gradually decreases, first increases and then decreases, and then decreases. Increase and other trend changes.

In another preferred example, the material combination used for connection by the multi-beam laser is usually composed of metallic materials, or non-metallic materials, preferably the same or homogeneous materials, or dissimilar or heterogeneous materials.

In another preferred example, the material combination used for connection by the multi-beam laser is usually a combination of two or more layers of plates, and the connection combination can be a combination of plates and profiles, or a combination of plates and castings, or other possible combinations.

In another preferred embodiment, the lap material is galvanized steel sheet.

In another preferred embodiment, when the combined thickness of the plates is 0.8-6.0 mm, the laser energy action time is 0.5-5.0 seconds.

In another preferred example, the diameter of the focused spot is 0.5-3.0 mm, and the laser power is 0.5 kW to 20 kW.

The beneficial effects of the present invention are: the combined effect of multiple laser energy can effectively expand the size of the welding area, the surface quality of the solder joint is good, the solder joint is large, and the energy loss is reduced, the efficiency is improved, and it is beneficial to the actual production. It is used under cycle conditions and has a good effect on zero-gap lap welding of galvanized steel sheets.

Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, without creative work, other alternative implementations can be obtained based on these drawings.

Figure 1 shows a schematic diagram of outputting two beams of laser energy from a single laser head to weld a combination of two overlapping sheets.

Figure 2 shows a schematic diagram of outputting three beams of laser energy from a single laser head to weld a combination of two overlapping sheets.

Figure 3 shows a schematic diagram of two laser heads outputting two beams of laser energy to weld the two-layer overlapping plate combination.

Fig. 4 shows a schematic diagram of outputting three beams of laser energy from two laser heads to weld the combination of two overlapping sheets.

Figure 5 shows a schematic diagram of the weld connection area of the cross-section of the two-layer lap board.

Figure 6 shows a schematic diagram of the weld connection area of the cross-section of the three-layer lap board.

Figure 7 shows a schematic diagram of the cross-sectional weld connection area of a layer of plate and a layer of profile or casting.

Figure 8 shows a schematic diagram of the cross-sectional weld connection area of the overlap between two layers of plates and one layer of profile or casting.

Fig. 9 shows a schematic diagram of providing shielding gas to the welding area through the side pipe during the process of welding the two-layer overlapping plate combination with a single laser head and dual laser beams.

Fig. 10 shows the process of single laser head and dual laser beam welding two-layer overlapped sheet metal assembly, the side wire feeding device provides welding wire material to the welding area.

Figure 11 shows a schematic front view of a weldment with a round spot weld.

Figure 12 shows a front view of a weldment with an oval weld shape.

Figure 13 shows the front view of a weldment whose weld shape is a four-sided arc.

Figure 14 shows a comparison photograph of the welding effect of non-coated materials using dual-beam laser energy and single-beam laser energy.

Figure 15 shows a photo of large-size solder joints obtained using dual-beam laser energy welding.

Fig. 16 shows a comparison photograph of the welding effect of galvanized layer materials using dual-beam laser energy and single-beam laser energy.

Figure 17 shows a photo of the burned part of the galvanized layer of the weld cross-section of the galvanized sheet using dual beam laser energy welding.

It should be noted that the shape of the weld area shown in the schematic diagram does not limit the shape that the actual welding effect should be formed, but merely represents the existence of the welding effect of the present invention.

Reference signs, 1-laser head, 11-laser head, 12-laser head, 21-laser beam, 22-laser beam, 23-laser beam, 3-weld area, 31-circular weld surface shape, 32 -Oval weld surface shape, 33-flower-shaped weld surface shape, 4-plate, 41-plate 4 upper surface, 5-plate, 6-plate, 7-pipe, 8-wire feeder, 9-profile or casting

detailed description

The present invention will be described in detail below in conjunction with accompanying drawings 1-17, and the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all the embodiments. . Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

It should be noted that in the claims and specification of this patent, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or It implies that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a series of elements includes not only those elements, but also includes Other elements of, or also include elements inherent to this process, method, article or equipment. If there are no more restrictions, the element defined by the phrase "including one" does not exclude the existence of other same elements in the process, method, article, or equipment including the element.

Fig. 1 shows an embodiment of the present invention. The laser head 1 outputs a laser beam 21 and a laser beam 22. The two laser energy acts on the upper surface 41 of the overlapping combination of the sheet 4 and the sheet 5, and the welding is formed after a period of continuous action. Seam area 3.

Figures 2, 3, and 4 show in turn three other embodiments of the present invention: the laser head 1 outputs three

laser beams

21, 22, and 23; the laser head 11 and the laser head 12 output two

laser beams

21 and 22, respectively. Laser beam; laser head 11 outputs laser beam 21, laser head 12

outputs laser beams

22 and 23. Other embodiments include using a single laser head or more laser heads to output more laser beams, and the preferred number of beams is less than 10. The energy of two, three or more laser beams is applied to the combined surface 41 of the overlapping material, so that the material in the active area is melted, and the weld area 3 is formed after cooling and solidification.

Figure 5 shows a schematic cross-sectional view of the overlapping combination of plate 4 and plate 5 with weld area 3. The weld area 3 diffuses and grows from plate 4 to plate 5 under the action of multiple laser energy to realize plate 4 and plate 5. Connection.

FIG. 6 shows a schematic cross-sectional view of the overlapping combination of the sheet 4, the sheet 5 and the sheet 6 with the welded area 3.

FIG. 7 shows a schematic cross-sectional view of the overlapped combination of the plate 4 and the profile 9 (or the casting 9) with the welded area 3.

FIG. 8 shows a schematic cross-sectional view of the overlapping combination of the sheet 4, the sheet 5 and the profile 9 (or the casting 9) with the welded seam area 3. The welding material combinations that can be applied to the present invention are not limited to those shown in FIGS. 5, 6, 7, and 8, and may be more layers and more forms of overlapping combinations.

FIG. 9 shows that the shielding gas is delivered to the welding seam area 3 through the pipe 7 at the side of the overlap welding position. The type of shielding gas is usually any welding gas such as argon, helium, nitrogen, carbon dioxide, oxygen and argon mixture.

FIG. 10 shows that the solder is fed to the welding seam area 3 through the wire feeder 8 at the side of the overlap welding position. , The solder state is preferably a solder wire.

Figures 11, 12, and 13 show the possible weld surface shapes after the welding is completed, which are round, oval, and lace shapes composed of four arcs.

Example 1

The material combination is two layers of 1.4 mm thick QP980 uncoated steel plates overlapped, and the double beam laser and single beam laser are used for welding. The same laser power is 2.5 kilowatts and the same action time is 2 seconds. The spot spacing of the double beam is 3 Mm, as shown in Figure 14, the joint size of dual-beam laser energy welding is larger.

Example 2

The material combination is two layers of 1.4 mm thick QP980 uncoated steel plate overlap, the laser power is 3.0 kW, the action time is 4 seconds, and the double beam spot spacing is 5 mm. As shown in Figure 15, the solder joint diameter is 16 mm.

Example 3

The material combination is two layers of 1.4 mm thick QP980 alloyed galvanized steel plate overlapped, the thickness of the galvanized layer is 20 microns, and the double beam laser and single beam laser are used for welding respectively, using the same laser power of 3.0 kW and the same action time of 1.5 Second, the spot spacing of the dual beam is 3 mm. As shown in Figure 16, the dual beam laser energy welding can obtain a complete solder joint without defects, while the solder joint of the single beam laser energy welding produces central perforations and solder joints due to spatter The size is too small. Figure 17 shows the cross-section of the weld and the plate in the welding joint of two-layer galvanized steel plate using dual beam laser energy. It can be seen that the galvanized layer between the plates in the heat-affected zone near the weld area is burned away, There is an unburnt galvanized layer between the base metal plates in the weld zone.

Although the present invention has been disclosed as above in the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various equivalent changes or substitutions without departing from the spirit and scope of the present invention. , All belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the appended claims of this application.

Claims

A laser welding method, characterized in that: the laser energy of multiple laser beams is applied to the combined surface of the overlapping material for a period of time to melt the material, and form a weld after cooling and solidification to realize the material connection; the number of the multiple laser beams The range of variation is from 2 to 10. The spot shape includes dots, rings, polygons or short-line shapes. The diameter of the focused spot varies from 0.05 mm to 10 mm. The laser power varies from 0.1 kW to 50 kW. The beam energy is either continuous or The output is in the form of pulse, and the action time ranges from 0.1 to 10 seconds. During the action, the position of the beam remains unchanged or moves arbitrarily within a circle of 15 mm in diameter to obtain large-size solder joints. The formed weld shape includes circular and elliptical shapes. Or curved outline.
The laser welding method according to claim 1, wherein when the multiple laser beams are dual laser beams, the beam spacing is 2-6 mm.
The laser welding method of claim 1, wherein the diameter of the large-size welding spot is 10-20 mm.
The laser welding method according to claim 2, wherein the energy loss required by the dual laser beams is reduced by more than 30% compared with a single beam, and the efficiency is doubled.
The laser welding method according to claim 1, wherein the welding process provides shielding gas to the welding area.
The laser welding method according to claim 1, wherein the welding process adds solder to the welding area.
The laser welding method according to claim 1, wherein the number of beams changes during the action of the laser beam energy.
The laser welding method of claim 1, wherein the lap material is a galvanized steel sheet.
The laser welding method according to claim 1, wherein the combined thickness of the lap material is in the range of 0.8-6.0 mm, and the laser beam energy action time is 0.5-5.0 seconds.
The laser welding method according to claim 1, wherein the diameter of the focused spot is 0.5-3.0 mm, and the laser power is 0.5 kW to 20 kW.