CN114799517B

CN114799517B - Method and device for welding laminated sheet by combining laser

Info

Publication number: CN114799517B
Application number: CN202210449192.9A
Authority: CN
Inventors: 陶武; 杨上陆
Original assignee: Shanghai Institute of Optics and Fine Mechanics of CAS
Current assignee: Shanghai Institute of Optics and Fine Mechanics of CAS
Priority date: 2022-04-25
Filing date: 2022-04-25
Publication date: 2023-05-09
Anticipated expiration: 2042-04-25
Also published as: CN114799517A

Abstract

The invention discloses a method and a device for welding laminated sheet combination laser, wherein the method comprises the following steps: enabling the laser beam to act on the welding area of the upper surface of the thin plate along a periodical repeated path to form a welding line; the thin plate lamination is fixed, and smoke dust and splash generated in the welding process are absorbed. The method also comprises the step of controlling the atmosphere environment in the process of forming the weld; cooling and/or heating control is performed on the laminate of sheets and the heat generated during the welding process. The invention adopts a welding process method of periodically repeating paths and modulating laser energy, is suitable for continuous sealing welding of multi-layer thin plate lamination combinations, has the characteristics of preventing overheating of a molten pool by energy regulation and control and preventing collapse of small holes by periodical scanning of laser beams, and is assisted by controlling lamination combination temperature and welding smoke dust, thereby truly realizing elimination of weld seam pores and cracks and meeting the requirement of non-leakage of weld seam sealing.

Description

Method and device for welding laminated sheet by combining laser

Technical Field

The invention relates to the field of sheet lamination combination welding, in particular to a sheet lamination combination laser welding method and device.

Background

There are a large number of laminated sheet composite structures in the body structures of the transportation industry, sheet metal appearances of general equipment and construction industry, heat management system cooling parts of the energy and power industry and other similar products; in the case of liquid-cooled plate devices, there is generally a requirement for sealing and maintaining pressure, and common materials are aluminum alloy, stainless steel, galvanized steel plate, and the like.

The existing laser welding technology generally cannot meet the conditions of surface quality requirements, no leakage of continuous welding seams and the like, so that the laser welding technology is difficult to obtain large-scale application, and the improvement of production efficiency and the reduction of manufacturing cost cannot be realized. Especially, the aluminum alloy lamination combined laser welding of the cooling plate of the new energy automobile faces the problems of weld holes, cracks, easy penetration of a bottom plate of a thin plate and the like, and can not meet the use requirements of pressure maintaining sealing, contact surface flattening and the like of products.

Besides the challenges to the laser welding process itself required by continuous sealing and pressure maintaining, the thin-plate liquid cooling plate product has the following characteristics: 1. the total length of the welding lines is large, the welding lines of some products can reach tens of meters, heat accumulation is easy to form in the welding process, and the products are easy to generate larger deformation after welding; 2. the flatness requirement of the contact surface is high, and the control requirement of partial products on weld seam surplus height and welding splashing is strict. The laser welding process can generate smoke dust, and the welding smoke dust can prevent laser beam energy from acting on the surface of a material to a certain extent, so that the welding process is unstable and welding splashing is caused; when the material is galvanized steel sheet, the welding fumes formed by the low boiling point zinc coating will cause more severe energy obstruction and zinc vapour will also cause the weld puddle to produce a lot of spatter. In addition, materials such as aluminum alloy and stainless steel are prone to splash during high-power laser welding and beam swing welding. Uneven oil stains on the material can also cause welding fume mutation, and cause welding quality defects.

Therefore, the laser welding of the laminated sheet composite product has the technical problem of weld quality and the appearance and functional requirements of product application, and the prior art cannot simultaneously or independently meet the requirements. Welding fume has adverse effects on weld quality and product quality, which is a place neglected in the prior art.

In the prior art, the effect on welding fumes is generally considered on the production environment, such as the fume removal protection device described in document CN114054987a, for filtering the fumes, protecting the working environment; in addition, there are concerns about the effect of the first air nozzle on the laser head on the butt joint optics, such as described in document CN109153096B, to remove fumes and splatter rising from the shielding gas by high-velocity air.

Disclosure of Invention

In order to solve two problems affecting the use of products in laser welding of a laminated sheet composite structure: firstly, welding seams of materials such as sheet combined aluminum alloy, stainless steel, galvanized sheet and the like are easy to generate defects such as air holes, cracks and the like to influence the pressure maintaining sealing performance of products; secondly, a large amount of weld heat accumulation causes product deformation, and welding smoke and welding dust splashed by the welding smoke cause unstable weld and sticky surface splashed, so that the overall flatness of the product and the flatness of a contact surface are affected. The technical scheme provided by the invention is to solve the problems, and comprises a welding device of a special tool and a corresponding welding process, and is as follows:

a method of laser welding a laminate stack of sheets, comprising:

enabling the laser beam to act on the welding area of the upper surface of the thin plate along a periodical repeated path to form a welding line;

the thin plate lamination is fixed, and smoke dust and splash generated in the welding process are absorbed.

And controlling the atmosphere environment in the process of forming the welding seam.

Cooling and/or heating control is performed on the laminate of sheets and the heat generated during the welding process.

The suction force is applied to the to-be-welded areas of the upper surface and the lower surface so as to absorb substances generated in the action process of laser such as splash and welding smoke dust in the laser welding process and materials; is connected to a vacuum pump through an internal or external connecting channel to provide suction force;

in a preferred embodiment, a remote vibrating mirror is used for scanning a welding head, so that a laser beam acts on the upper surface of a lamination combination between blank spaces of the pressing blocks along a periodical repeated path, and small holes of the pressing blocks and the supporting blocks of the clamping mechanism corresponding to the action positions of the laser beam provide shielding gas or suction force according to the characteristics of welding materials, such as stainless steel or aluminum alloy; the suction force is provided for the surface low-boiling-point coating materials such as galvanized steel plates, and the suction force can be provided under the welding condition when the sputtering is larger, so that welding smoke dust and the sputtering are absorbed, and the consistency and the stability of welding seams are improved; meanwhile, the pressing block and the cavity in the supporting block are circulated with low-temperature circulating cooling water so as to rapidly diffuse laser beam energy absorbed by the lamination combination in the welding line forming process, thereby avoiding heat accumulation and inhibiting the occurrence of post-welding deformation of products.

In another preferred embodiment, the sum of the equivalent rectangular side lengths of the outer contours of the smallest repeating units of the periodically repeating paths is larger than the spot diameter acting on the surface of the material. The equivalent rectangle refers to the smallest rectangle tangent to the outer contour of the smallest repeating unit of the repeating path.

In another preferred example, the interval of the blank spaces of the pressing blocks is not more than 3 times of the width of the welding line, the blank areas of the supporting blocks are not existed, and the welding penetration welding line is not formed on the lower surface of the laminated combination by adjusting the laser welding process.

In another preferred example, the laser beam of the laser welding method is controlled to have a low energy period with periodicity lower than the main body set energy during the laser beam energy application while being applied along the periodically repeated path; the main body sets the energy as high energy, and the shortest unit consisting of a single high energy period and a single low energy period is an energy period, and the length of the energy period is 5-100ms. The low energy period has a lower laser power, which may be 0, or a higher beam scanning speed, or a larger spot diameter. When the process method is used for carrying out the thin plate combination non-penetration welding, the obtained welding seam longitudinal section has the periodic penetration of saw tooth shape.

In another preferred embodiment, the laser welding method further comprises a second laser beam that acts on the surface of the weld bead that has been formed or the molten pool that is being solidified, the second laser beam having an energy level that is not higher than 60% of the high energy; the energy level is proportional to the laser power, inversely proportional to the beam scanning speed, and inversely proportional to the spot area acting on the surface of the material. The second laser beam is used to treat the weld surface and does not produce a weld that penetrates the stack assembly.

The invention also provides a thin plate laminated combined laser welding device, which comprises the following functional modules:

the laser output module is used for outputting the first laser beam and/or the second laser beam;

the control unit is connected with the laser output module and used for controlling the energy and the path of the laser beam output by the laser output module so that the laser beam acts on the welding area on the upper surface of the thin plate along the periodically repeated path;

the fixing module is arranged on the upper surface and the lower surface of the thin plate lamination and is used for fixing the thin plates, and an exposure space is reserved at least in a region to be welded on the upper surface of the thin plates, so that laser beams can act on the region to be welded;

the absorption module is arranged in the fixed module and is externally connected with the vacuumizing system, and in the welding process, the vacuumizing system is started to generate negative pressure, so that smoke dust and splashes generated by welding are absorbed by the absorption module;

in a preferred embodiment, the laser output module is a scanning galvanometer. The fixing module comprises a pressing block and a supporting block, wherein the pressing block is open towards the to-be-welded area.

In another preferred embodiment, the small holes of the pressing block and the supporting block have a closing function, and are connected with the control unit, the small holes are closed before welding, the small holes corresponding to the output laser beam action area are opened in advance before the laser beam reaches the corresponding position, and the small holes are closed after the laser beam leaves the corresponding position for a period of time, so that the laser beam action and the small hole action are in a real-time synchronous state; the small holes can be closed by shielding the small holes by a baffle plate arranged in the small hole connecting channel or at the outlet position of the small holes, and the baffle plate is opened and closed by changing the position of the baffle plate through a back and forth mechanism.

In another preferred embodiment, at least one of the small holes on two sides of the blank area of the pressing block and the supporting block is used for respectively applying protective gas to the upper surface and the lower surface of the area to be welded so as to avoid air influence in the process of forming the welding seam; the shielding gas can be implemented through an external compressed gas cylinder, and the air in the blank areas of the pressing block and the supporting block is discharged through the shielding gas, so that the welding seam is prevented from oxidation in a high-temperature state. The small holes on the two sides of the blank area can provide protective gas and suction force at the same time.

In another preferred embodiment, a communicated cavity is formed in the pressing block, and no intersecting cross-over area exists between the cavity and the continuous channel of the small hole; the distance between the bottom of the cavity and the contact surface of the upper surface of the combination of the pressing block and the lamination is not more than 3mm; the cavity is connected with an external cooling system so that cooling medium circularly flows in the cavity inside the pressing block in the welding process; the cooling system is a cooling water circulator with the water temperature set at 5-15 ℃.

Meanwhile, a communicated cavity is formed in the supporting block, and the cavity is connected with an external cooling system, so that cooling medium circularly flows in the cavity in the pressing block in the welding process.

In another preferred embodiment, at least one of the internal cavities of the briquette or support block is connected to an external heating system such that a high temperature medium is present inside the cavity, the high temperature medium being circulating water having a temperature of 30-90 ℃, or a molten salt or oil having a temperature of 100-300 ℃.

In another preferred example, the interval distance D1 of the blank areas of the pressing blocks of the clamping mechanism of the laser welding device meets the requirement that W1 is less than or equal to D1 and less than or equal to W1+10mm, wherein W1 is the width of the welding seam on the corresponding upper surface of the blank area.

Meanwhile, the spacing distance D2 of the blank areas of the supporting blocks of the clamping mechanism of the laser welding device meets the requirement that W2 is not less than D2 and not more than D1, wherein W2 is the width of a welding line on the lower surface corresponding to the blank areas; when w2=0, i.e. the lower surface of the stack assembly is not welded through, the support blocks may not have a blank area.

The invention has the beneficial effects that:

1. the welding process method which adopts a periodical repeated path and modulates laser energy is suitable for continuous sealing welding of multi-layer thin plate lamination combinations, particularly welding of aluminum alloy thin plate lamination combinations, and energy output is controlled in a high-low energy mode while laser beams are scanned along the periodical path.

2. The second laser beam is used for scanning the welded seam surface, so that the weld seam surplus height is reduced, the undercut is eliminated, the oxidation is reduced, the welded seam surface is formed smoothly, and the welded seam surface has better appearance characteristics.

3. When the laser is welded along a periodical repeated path, the dust and splash in the laser welding process can be absorbed in real time through the suction action of the pressing block of the clamping mechanism and the small hole of the supporting block of the welding device, the sticky damage of the splash to the surface is avoided, and the defects of splash, air holes and the like caused by unstable factors such as low-boiling-point surface coatings, greasy dirt and the like are eliminated.

4. The front and the back of the weld joint can be protected in real time to avoid oxidization; other gases needed by the process are also conveniently provided, and the air holes are eliminated, the tissue is improved and the like are assisted.

5. The characteristic of closing at the non-welding position can effectively reduce the power of the suction equipment or the demand quantity of the shielding gas, and increase the suction effect or the shielding gas effect.

6. The suction or shielding gas is provided through the welding device, no additional requirement is provided for the gas path of the laser welding system, the implementation of a pipeline or a gas external pipeline carried by a laser head in the prior art (such as CN 109153096B) is not needed, the possible accessibility problem is avoided, and the clamping mechanism has wide applicability.

7. The cooling system is connected through the internal cavity of the welding device, so that the rapid diffusion of the energy of the laser beam absorbed by the material in the welding process is realized, the accumulation of the welding laser energy is avoided, and the deformation of the welding product caused by the accumulation of heat in the conventional technology is restrained. By cooling both sides of the weld joint up and down, a better effect can be obtained than in the conventional manner of single-side cooling, cooling gas cooling, and the like. For materials whose tissue is susceptible to temperature gradients, the adverse effects of the welding thermal cycle can be ameliorated by heating the medium. When the distance D1 between the blank areas of the pressing block is smaller, for example, 2 times of the width W1 of the welding line on the upper surface, splash can be prevented from adhering to the surface of the material.

Drawings

FIG. 1 is a schematic view of a partial cross section of a laminate composite laser welding apparatus of example 1 of the present invention.

FIG. 2 is a schematic partial cross-sectional view of a laminate composite laser welding apparatus of example 2 of the present invention.

FIG. 3 is a schematic view of a partial cross section of a laminate composite laser welding apparatus of example 3 of the present invention, the weld being in the form of a lap fillet weld.

FIG. 4 is a schematic illustration of the penetration profile of a bottom plate of a longitudinal section of a weld obtained after modulation using a periodically repeated path of the beam and laser energy.

FIG. 5 is a photograph of the periodic penetration profile of a substrate sheet in a longitudinal section of an actual weld obtained after modulation using a periodically repeating path of the beam and laser energy.

Fig. 6 is a photograph of non-uniform penetration of a longitudinal section floor panel weld (swing weld) obtained using only a periodically repeating path of the beam.

Fig. 7 is a prior art (swing welding) weld surface oxidized without the use of shielding gas.

FIG. 8 is a schematic representation of a technique of the present invention using a second laser beam to scan a weld to form a new weld cross section.

FIG. 9 is a view of the technique of the present invention for achieving a shiny weld surface without the use of shielding gas.

Reference numerals: 1-a laminate stack combination of thin plates; 2-pressing blocks of the clamping mechanism; a small hole of the 21-briquetting; 22-a connecting channel of the small hole of the pressing block; 23-cooling liquid cavity of the briquetting; 24-a block between the small hole of the pressing block and the connecting channel; 3-a supporting block of the clamping mechanism; 31-small holes of the supporting blocks; 32-connecting channels of the small holes of the supporting blocks; 33-coolant cavity of the support block; 4-laser beam output by the laser welding system; 5-a schematic diagram of a laminated combined full penetration weld; 6-an auxiliary block located outside the briquette or support block, which is separately present; 61-small hole connecting channels inside the auxiliary block; 62-a stop for closing between the auxiliary block connecting channel and the aperture.

Detailed Description

The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to fig. 1 to 9, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1

According to the welding seam position of the laminated composite product of the thin plates, a pressing block 2 and a supporting block 3 are arranged in a clamping mechanism of the laser welding device, the pressing block and the supporting block are mutually attached to the multi-layer plates of the laminated composite 1 in a region to be welded through mutually facing acting forces, and the acting forces are implemented through magnetic force or mechanical force. As shown in fig. 1, one embodiment of the present invention is to provide a blank area in the compact 2 so that the laser beam 4 output by the laser welding system acts on the upper surface of the laminate through the blank area to produce a weld 5. Meanwhile, small holes 21 are respectively arranged on two surfaces of the pressing block facing to the upper surface to-be-welded area, and small hole connecting channels 22 are respectively arranged inside the pressing block. Small holes 31 are respectively arranged on two surfaces of the blank area of the supporting block 3 facing the lower surface to be welded, and small hole connecting channels 32 are respectively arranged inside the supporting block. The cross section shape of the briquetting small hole connecting channel 22 and the supporting block small hole connecting channel 32 is preferably round or rectangular or a combination shape thereof, and the small

hole connecting channels

22 and 32 are connected with an external vacuum pump system, so that suction force is generated, welding smoke dust and splash are absorbed in the welding process, the stability of the continuous welding process is improved, and the influence of welding splash on the quality of a welding seam and the peripheral surface is inhibited. The outlet position of the small hole is round, square or elliptic, and the diameter, diagonal or long axis is not more than 6mm, preferably 2-4mm. The holes are uniformly distributed at equal intervals, and the center distance of the holes is not more than 30mm, preferably 10-15mm. The distance between the bottom of the aperture and the upper surface of the stack combination is not more than 20mm, preferably 3-10mm. The small holes are symmetrically distributed or staggered on two sides of the blank area in the pressing block and the supporting block respectively. Depending on the actual product situation, in one embodiment at least one of the press block 2 and the support block 3 may be present on only one side. In another embodiment, at least one side of the small holes on both sides of the blank area of the pressing block 2 and the supporting block 3 is provided with a shielding gas, and the shielding gas is provided by connecting the small

hole connecting channels

22 or 32 with an external gas source such as a steel cylinder gas.

Example 2

As shown in fig. 1, on the basis of the small holes and the connecting channels of the pressing block and the supporting block, cavities 23 are respectively arranged in two sides of a blank area of the pressing block 2, and cavities 33 are respectively arranged in two sides of the supporting block 3; the lowest point of the briquetting cavity 23 is not more than 5mm, preferably 2-3mm, from the upper surface of the laminated assembly 1; the highest point of the support block cavity 33 is no more than 5mm, preferably 2-3mm, from the lower surface of the stack 1. The cross-sectional shapes of the briquetting cavity 23 and the supporting block cavity 33 are preferably circular or rectangular or a combination thereof, and the briquetting cavity 23 and the supporting block cavity 33 are connected with an external cooling system so that cooling liquid circulates in the cavities. In one embodiment, the external cooling system is a circulating water chiller and the cooling liquid is water having a temperature of no greater than 15 ℃, preferably 5-10 ℃. In another embodiment, the cooling liquid is an ethylene glycol type cooling liquid with a temperature of 0-5 ℃. In the laser welding process, cooling liquid circulates in the pressing block and the supporting block, so that heat diffused to the base metal after the material absorbs the laser beam to form a welding line is taken away, heat accumulation is avoided, the influence of the heat on the area outside the welding line is reduced, and the integral deformation degree of a product is reduced.

Example 3

As shown in FIG. 2, in one embodiment, the bottom of the blank area of the pressing block is provided with a space D1, the upper part of the blank area of the pressing block is provided with a larger space distance, and the value of D1 and the value of the width W1 of the welding seam on the upper surface meet the condition that W1.ltoreq.D1.ltoreq.W1+10 (unit mm), and preferably, W1.ltoreq.D1.ltoreq.3.W1. The support block blank area has a spacing D2, the value of D2 and the value of the lower surface weld width W2 satisfy w2.ltoreq.d2.ltoreq.d1, in one embodiment, the weld does not penetrate the lower plate, d2=w2=0, i.e. no pinholes and pinholes channels are present in the support block. In another embodiment, a stop block 24 is arranged at the transition position of the small hole connecting channel 22 and the small hole 21, the small hole is closed or opened by the back and forth translation or rotation of the program editing control stop block, the small hole 21 is closed before welding, the stop block movement control program is linked with the laser beam travelling path control program to ensure that the stop block 24 moves to open the small hole 21 at the corresponding position before the laser beam 4 reaches a certain position of the area to be welded, and the time for opening the small hole in advance is not more than 10s, preferably 3-5s; after the laser beam 4 has completed welding and left the corresponding position for a period of time, the stopper 24 is moved to close the aperture 21 of the corresponding position again, the lag time of aperture closure not exceeding 10s, preferably 3-5s; the suction force or the shielding gas of the small hole continuously acts on the welding area through the early opening and the delayed closing of the small hole in the process of laser beam action and the process of solidification of a molten pool to form a welding line.

Example 4

As shown in fig. 2 and 3, in one embodiment, the small hole 21 of the pressing block 2 or the small hole 31 of the supporting block 3 is communicated with the small hole connecting channel 61 of the external auxiliary block 6, and the opening and closing of the small hole is controlled by the stop block 62. In another embodiment, shown in FIG. 3, the briquette or support block has different structural designs on either side of the blank area.

Example 5

In one embodiment, as shown in fig. 3, where the area to be welded of the laminated assembly 1 is in the form of a lap fillet, a weld cross section 51 is formed, the weld 51 does not penetrate the laminated assembly floor sheet, at which time there is no blank area for the support block, and only the cavity 33 is present inside the support block 3, and cooling liquid circulates through the cavity 33 to remove heat from the floor sheet welding area.

Example 6

In another embodiment, at least one of the internal cavities 23 of the briquette 2 and the internal cavities 33 of the support block 3 is connected to an external heating system so that a high temperature medium, which is circulating water having 30-90 deg.c or molten salt or oil having 100-300 deg.c, exists inside the cavity.

Example 7

On the basis of the embodiment of the clamping mechanism of the laser welding device, several embodiments of the laser welding method are described. The laser welding method uses a remote galvanometer scanning welding head or a swinging welding head.

In one embodiment, the laser beam is caused to act on the region to be welded along a periodically repeating path whose sum of equivalent rectangular side lengths of the outer contours of the smallest repeating units is larger than the spot diameter acting on the surface of the material. The equivalent rectangle refers to the smallest rectangle tangent to the outer contour of the smallest repeating unit of the repeating path. The repetition path period is 100-400Hz, and the process method can eliminate weld pores of the aluminum alloy material.

In another embodiment, the ability of the laser beam is modulated so that there is a low energy period of time during which the laser beam energy is applied that is periodically lower than the subject's set energy; the main body sets the energy as high energy, and the shortest unit consisting of a single high energy period and a single low energy period is an energy period, and the length of the energy period is 5-100ms. The low energy period has a lower laser power, which may be 0, or a higher beam scanning speed, or a larger spot diameter. When the process method is suitable for carrying out the combination non-penetrating welding of the thin plates, the obtained welding seam longitudinal section has the periodic penetration of saw-tooth shape, as shown in fig. 4 and 5, and the situation of local penetration of the welding seam penetration shown in fig. 6 can be avoided.

In another embodiment, weld cracks, including cracks at sensitive weld corner locations, in a 6-series or 3-series aluminum alloy sheet laminate combination can be eliminated by laser beam energy modulation and periodic paths, thereby ensuring that the welded product meets the operating requirements of sealing and pressure maintaining.

Example 8

In one embodiment, the second laser beam is caused to act on the upper surface of the weld bead 5 along a periodically repeated path with a greater coverage, with an energy intensity not higher than 60% of said high energy E0. In another embodiment, the second laser beam acts on the surface of the as yet unset bath produced by the laser beam 4 with an energy intensity of not more than 40% of the high energy E0. In the above embodiment, the cross section of the weld produced is shown in fig. 8, where 8 is the weld formed by the laser beam 4 and 9 is the area where the material melts after the second laser beam scan, which is mixed with the weld 8 or exists in an independently visible form. The actually obtained weld surface is shown in fig. 9, and compared with the oxidized weld morphology of the surface of fig. 7 obtained by the conventional technology, the grey black color of the weld surface is eliminated, the weld surface is flatter, and the surface is almost flat with the base material. Meets the requirement of the product on the appearance. In this embodiment, no protective gas is required, nor is a special polishing and cleaning of the oxide layer required.

The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications could be made by those skilled in the art without departing from the method of the present invention, and such modifications should also be considered as being within the scope of the present invention.

Claims

1. A method of laser welding a laminate stack of sheets, comprising:

controlling the energy of the laser beam while the laser beam acts along the periodical repetitive path, so that a low-energy period with periodicity lower than a set energy of a main body exists in the laser beam energy acting process, wherein the main body sets the energy to be high energy, the shortest unit consisting of a single high-energy period and a single low-energy period is an energy period, the length of the energy period is 5-100ms, the laser beam comprises a first laser beam and a second laser beam, and the second laser beam acts on the surface of a weld joint which is formed or a solidifying molten pool and has an energy level not higher than 60% of the high energy;

the thin plates are laminated and fixed, and smoke dust and splashes generated in the welding process are absorbed;

controlling the atmosphere environment in the welding seam forming process;

2. The method of claim 1, wherein the sum of the equivalent rectangular side lengths of the outer contours of the minimum repeating units of the periodic repeating path is larger than the spot diameter acting on the surface of the material, and the equivalent rectangle is the minimum rectangle tangent to the outer contour of the minimum repeating units of the repeating path.

3. A laser welding apparatus for realizing the method for combining laser welding of laminated sheets as claimed in claim 1 or 2, comprising

the absorption module is arranged in the fixed module and externally connected with the vacuumizing system, and in the welding process, the vacuumizing system is started to generate negative pressure so that smoke dust and splashes generated by welding are absorbed by the absorption module;

the connecting module is arranged in the fixing module, is communicated with the absorbing module, is externally connected with a protective gas source and is used for applying protective gas to the welding area, so that the welding area is prevented from being influenced by air in the welding line forming process;

the cavity is arranged in the fixed module and is externally connected with a cooling system or a heating system so that cooling or heating medium circularly flows in the cavity in the welding process.

4. The laser welding device according to claim 3, further comprising a stopper disposed at a junction of the connection module and the absorption module and connected to the control unit;

the control unit controls the stop block and the laser output module to enable the absorption module to be opened in advance before the laser beam reaches the area to be welded and to be closed after the laser beam leaves the area to be welded.