A method for laser welding of copper sheets

Abstract

The invention relates to a method for laser welding of copper sheets. The method adopts a dual-beam mode of a blue laser beam and an infrared laser beam to weld the copper sheets, and reasonably sets the relative positions of the light spots of the blue laser beam and the infrared laser beam. In the welding direction, the centers of the two light spots do not overlap. The blue laser is arranged in front of the infrared laser. During the welding process, the power of the front blue laser is at a lower level, and the to-be-welded part of the copper sheet is mainly heated to improve the absorption rate of the infrared laser. On this basis, the infrared laser that follows closely performs high-speed welding on the to-be-welded part, thereby effectively suppressing welding spatter, overcoming the problem of uneven heat dissipation, and obtaining a uniform and high-quality weld, thereby meeting the requirements of laser welding of thin copper sheets with hollow patterns.

Description

Technical Field

[0001] The invention relates to the technical field of copper sheet welding, and in particular to a copper sheet laser welding method, which is suitable for precision welding of copper sheets with uneven heat dissipation structures such as hollow patterns. Background Art

[0002] Copper sheets have good thermal and electrical conductivity and are widely used in electronic and electrical products and facilities. For example, copper sheets can be used to make LED bracket products by stamping. Compared with traditional stainless steel brackets, brackets made by copper sheet stamping have the characteristics of high electrical conductivity and thermal conductivity, good heat dissipation, and are not easy to rust, which has obvious advantages in LED production applications. In actual production, it is often necessary to splice copper sheet brackets of different rolls to achieve continuous production, improve efficiency and reduce production costs. However, since the thickness of this copper bracket is very thin, and the weldable position reserved at the stamping is very narrow, only 200-400um (the width of the two pieces to be welded after splicing is 400-800um), the hollow structure on both sides of the welding part before splicing leads to serious uneven heat dissipation. It is obviously difficult to meet the requirements by using conventional welding methods (such as argon arc welding). It is necessary to use a high power density and a precision laser welding method with low heat impact.

[0003] At present, the lasers with more mature applications in the market, including fiber lasers and solid-state lasers, are all infrared lasers. Since copper has an absorption rate of only 5% for infrared lasers, it is very easy to produce defects such as spatter and holes when copper is welded with infrared lasers, resulting in poor welding quality and low reliability. In other words, direct welding with a small spot infrared laser has the problem of high reflectivity, which is prone to welding spatter and holes, and poor welding quality. Copper has an absorption rate of up to 65% for blue lasers, so blue light is very suitable for copper welding. However, the only blue lasers that can be used for welding on the market are semiconductor lasers. When using existing semiconductor blue lasers for welding, due to the low quality of the semiconductor blue laser beam, usually only heat conduction welding can be performed, and the hollow structure on both sides leads to uneven heat dissipation, and a good weld connection cannot be achieved. During the welding process, the good heat dissipation area is prone to not being fused, and the hollowing out leads to poor heat dissipation areas that are easy to be welded through. Therefore, the existing semiconductor blue laser welding method has the problems of too large spot size and low energy density, which cannot meet the needs of laser welding of thin copper sheets with hollow patterns. Summary of the invention

[0004] Based on this, one object of the present invention is to provide a method for laser welding of copper sheets, which adopts a dual-beam method of a blue laser beam and an infrared laser beam to weld copper sheets, which can suppress welding spatter, overcome the problem of uneven heat dissipation, and meet the needs of laser welding of thin copper sheets with hollow patterns.

[0005] A method for laser welding of copper sheets, comprising the steps of:

[0006] S1. Use a welding fixture to fix and assemble the two copper sheets to be spliced; and

[0007] S2. Use a blue laser beam and an infrared laser beam, and make sure that the spot centers of the blue laser beam and the infrared laser beam coincide with the center line of the joint seam between the two copper sheets to be joined. Place the blue laser beam in front of the infrared laser beam along the center line of the joint seam, and make sure that the spot center of the blue laser beam leads the spot center of the infrared laser beam in the welding feed direction, so as to weld the joint seam between the two copper sheets to be joined.

[0008] In one embodiment of the present invention, in step S1, the size of the joint seam between the two copper sheets to be spliced ​​is Δ≤20 um.

[0009] In one embodiment of the present invention, in step S2, the wavelength of the blue laser beam is 450nm±10nm, and the wavelength of the infrared laser beam is 1080nm±10nm.

[0010] In one embodiment of the present invention, in step S2, it is assumed that during the welding process, the spot center of the blue laser beam leads the spot center of the infrared laser beam in the welding feed direction by a distance L, and the spot diameter of the blue laser beam is d B , the spot diameter of the infrared laser beam is d IR , where L satisfies: 0.5d IR ≤L≤d B -0.5d IR , so that the spot of the infrared laser beam falls entirely within the spot of the blue laser beam.

[0011] In one embodiment of the present invention, the spot diameter d of the blue laser beam is B The spot diameter of the infrared laser beam is 600-800um. IR 20~50um.

[0012] In one embodiment of the present invention, the copper sheet laser welding method also includes the step: S3, using a higher welding speed, setting the power of the blue light laser and the infrared laser, wherein the blue light laser power is set to satisfy the blue light laser beam to heat the welding area without melting the copper sheet, and the infrared laser power is set to satisfy the infrared laser beam to melt the copper near the joint and ensure that the copper sheet is melted through.

[0013] In one embodiment of the present invention, in step S3, the welding speed adopted is: 100 mm / s-300 mm / s.

[0014] In one embodiment of the present invention, the copper sheet laser welding method further includes the step: S4, turning on the blue light laser, the infrared laser and the welding feed execution structure to complete the copper sheet splicing to obtain the welded plate.

[0015] In one embodiment of the present invention, the copper sheet laser welding method further includes the step: S5, turning off the blue laser, the infrared laser and the welding feed execution structure, loosening the welding fixture, taking out the welded plate, and completing the welding.

[0016] In one embodiment of the present invention, the copper sheet laser welding method is suitable for welding copper sheets with a thickness of 0.2 to 0.5 mm and an uneven heat dissipation structure with a hollow pattern.

[0017] The present invention adopts a dual-beam method of a blue laser beam and an infrared laser beam to weld the copper sheets, and reasonably sets the relative positions of the light spots of the blue laser beam and the infrared laser beam. Since the selected blue laser has low power and only performs preheating, the absorption rate of the infrared laser increases with the increase of temperature. Under the action of the infrared laser and the blue laser, the generation of welding defects such as holes and spatters during the welding process is avoided, and the problem of poor weld formation caused by the large size of the blue light welding spot, the large size of the welding molten pool, and the uneven heat dissipation on both sides of the welding area is solved. A uniform and high-quality weld is obtained.

[0018] The present invention adopts a small-sized infrared laser spot and ensures that the welding melting process only occurs in a very narrow area equivalent to the size of the infrared laser spot. In addition, a higher welding speed is adopted, so that the influence of uneven heat dissipation on both sides of the copper sheet on the weld molten pool can be minimized, thereby overcoming the problems of narrow area to be welded and uneven heat dissipation, and ensuring the uniformity of the welding process of the entire weld.

[0019] Further objects and advantages of the present invention will be fully apparent from an understanding of the following description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a flowchart of the copper sheet laser welding method of the present invention.

[0021] Figure 2 Schematic diagram of the splicing of copper sheets with uneven heat dissipation structure.

[0022] Figure 3 This is a schematic diagram of the cross-section welding assembly perpendicular to the welding direction.

[0023] Figure 4 for Figure 3 Magnified schematic diagram of the blue laser beam and the infrared laser beam in FIG.

[0024] Figure 5 for Figure 4 Schematic diagram of the relative positions of the light spots of the blue laser beam and the infrared laser beam shown.

[0025] Description of the accompanying drawings: copper sheets to be spliced ​​10; hollow area 11; non-hollow area 12; splicing seam 13; welding fixture 20; welding fixture upper pressure plate 21; welding fixture lower pad 22; blue laser beam 30; infrared laser beam 40; blue laser beam spot 31; infrared laser beam spot 41. DETAILED DESCRIPTION

[0026] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, deformation schemes, improved schemes, equivalent schemes, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0027] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "vertical", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0028] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] like Figures 1 to 5 As shown, the specific steps of a copper sheet laser welding method according to the present invention are explained.

[0031] In view of the shortcomings of the prior art, the present invention uses a dual beam consisting of a blue laser with a wavelength of about 450nm and an infrared laser with a wavelength of 1080nm to complete the welding of copper sheets, wherein the spot size of the blue laser is slightly smaller than the area to be welded, specifically 600-800um, while the spot size of the infrared laser is within 50um. In the welding direction, the centers of the two beams of light spots do not overlap. By arranging the blue laser in front of the infrared laser, the power of the front blue laser during welding is at a lower level, mainly heating the part to be welded of the copper sheet to improve the absorption rate of the infrared laser; on this basis, the infrared laser following closely behind performs high-speed welding on the position to be welded. By adopting dual beams and reasonably setting the relative positions of the dual beams of light spots, welding spatter is greatly suppressed, the problem of uneven heat dissipation is overcome, and a uniform and high-quality weld can be obtained, meeting the needs of laser welding of thin copper sheets with hollow patterns.

[0032] Specifically, Figure 1 As shown, the copper sheet laser welding method comprises the steps of:

[0033] S1, copper sheet assembly: two copper sheets 10 to be spliced ​​are fixed and assembled using a welding fixture 20;

[0034] S2. Adjusting the welding path and the spot position: using a blue laser beam 30 and an infrared laser beam 40, the spot centers of the blue laser beam 30 and the infrared laser beam 40 are both coincident with the center line of the joint seam 13 between the two copper sheets 10 to be joined, and the blue laser beam 30 is arranged in front of the infrared laser beam 40 along the center line direction of the joint seam 13, and the spot center of the blue laser beam 30 is ahead of the spot center of the infrared laser beam 40 in the welding feed direction, so as to weld the joint seam 13 between the two copper sheets 10 to be joined;

[0035] S3, process parameter setting: adopt a higher welding speed, set the power of blue laser and infrared laser, wherein the power of blue laser is set to meet the blue laser beam 30 to heat the welding area without melting the copper sheet, and the power of infrared laser is set to meet the infrared laser beam 40 to melt the copper near the joint 13 and ensure that the copper sheet is melted through;

[0036] S4, start welding: turn on the blue laser, infrared laser and welding feed execution structure to complete the splicing of copper sheets and obtain the welded plate;

[0037] S5, welding is finished: turn off the blue laser, infrared laser and welding feed execution structure, loosen the welding fixture 20, take out the tailor-welded blank, and the welding is completed.

[0038] like Figure 2As shown, the copper sheets 10 to be spliced ​​have a hollow area 11 and a non-hollow area 12 , and a splicing seam 13 is formed between the two copper sheets 10 to be spliced.

[0039] In particular, since a too wide joint seam will lead to welding through, it is generally required that the laser welding joint seam is as small as possible. Therefore, in step S1, the size of the joint seam 13 between the two copper sheets 10 to be spliced ​​is Δ≤20um to ensure that the size of the joint seam 13 can match the diameter of the infrared laser spot to avoid the problem of welding through.

[0040] It is worth mentioning that the welding fixture 20 used in step S1 includes an upper pressing plate 21 of the welding fixture and a lower pad 22 of the welding fixture. The copper sheet 10 to be spliced ​​is clamped between the upper pressing plate 21 of the welding fixture and the lower pad 22 of the welding fixture. Figure 3 shown.

[0041] It is understandable that the present invention can also design a hollow structure corresponding to the copper sheet on the welding fixture 20, and make the hollow part of the copper sheet correspond to the non-hollow part of the fixture during welding, so that the heat is taken away by the fixture to offset the uneven heat dissipation caused by the hollow structure of the copper sheet itself.

[0042] Particularly, in the step S2, the wavelength of the blue laser beam 30 is 450 nm, and the wavelength of the infrared laser beam 40 is 1080 nm.

[0043] That is to say, in this specific embodiment, the present invention adopts a dual-beam high-speed welding method of a blue laser with a wavelength of 450nm and an infrared laser with a wavelength of 1080nm, which solves the problem of single infrared laser welding that is prone to welding spatter and holes due to high reflectivity, and solves the problem of single blue light laser welding that is caused by a large blue light welding spot size, a large welding molten pool size, and uneven heat dissipation on both sides of the welding area, resulting in poor weld formation.

[0044] In some embodiments of the present invention, the blue laser beam 30 and the infrared laser beam 40 may also use other wavelengths, such as the wavelength of the blue laser beam 30 is within the range of 450nm±10nm, and the wavelength of the infrared laser beam 40 is within the range of 1080nm±10nm, and the present invention is not limited to this.

[0045] In particular, if Figure 4 and Figure 5 As shown, in step S2, it is assumed that during the welding process, the spot center of the blue laser beam 30 leads the spot center of the infrared laser beam 40 by a distance L in the welding feed direction, and the diameter of the spot 31 of the blue laser beam 30 is d B , the diameter of the spot 41 of the infrared laser beam 40 is d IR , where L satisfies: 0.5dIR ≤L≤d B -0.5d IR , so that the spot 41 of the infrared laser beam 40 falls as a whole within the spot 31 of the blue laser beam 30, so that by using the blue laser for preheating, the absorption rate of the infrared laser increases with the increase of temperature, and under the action of the infrared laser and the blue laser, the generation of welding defects such as spatter and holes during the welding process can be avoided; in addition, by using a small-sized infrared laser spot and ensuring that the welding melting process only occurs in a very narrow area equivalent to the size of the infrared laser spot, coupled with a higher welding speed, the influence of uneven heat dissipation on both sides on the weld molten pool is minimized, the problems of narrow area to be welded and uneven heat dissipation are overcome, and the uniformity of the welding process of the entire weld is ensured.

[0046] Specifically, in this embodiment of the present invention, the spot diameter d of the blue laser beam 30 is B The spot diameter d of the infrared laser beam 40 is 600~800um. IR 20~50um.

[0047] It is worth mentioning that the spot of the blue laser beam 30 can be a circular spot, a rectangular spot or a spot of other shapes, and the present invention is not limited to this.

[0048] Particularly, in step S3, the welding speed adopted is: 100 mm / s-300 mm / s.

[0049] It is understandable that through high-speed welding, during the welding process, the blue laser only needs to heat the welding position without producing a melting effect. The infrared laser with a small spot size achieves welding connection by melting the metal. The high-speed welding and small spot ensure that the uneven heat dissipation in the hollow area minimizes the impact on the welding effect. In this way, the best welding effect can be obtained.

[0050] It is worth mentioning that the welding feed execution structure in step S4 and step S5 can be a motion structure such as a welding robot or a machine tool, which is used to realize the movement of the blue laser and the infrared laser, and the present invention does not limit this.

[0051] It is worth mentioning that the copper sheet laser welding method of the present invention is particularly suitable for welding copper sheets with a thickness of 0.2 to 0.5 mm and an uneven heat dissipation structure with a hollow pattern. It is also suitable for welding other thin metal sheets or alloy metal sheets. The present invention does not limit the specific application of the copper sheet laser welding method.

[0052] In general, the present invention adopts a dual-beam welding method of a blue laser beam 30 and an infrared laser beam, and reasonably sets the relative positions of the dual-beam spots to avoid the problems of poor quality of infrared laser welding, many spatter and hole defects, and large blue light welding spot size, large welding pool size, and poor weld formation due to uneven heat dissipation on both sides of the welding area. A uniform and high-quality weld is obtained.

[0053] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for laser welding of copper sheets, characterized in that: Includes steps: S1. Use a welding fixture to fix and assemble the two copper sheets to be spliced; and S2. Using a blue laser beam and an infrared laser beam, the spot centers of the blue laser beam and the infrared laser beam are coincident with the center line of the joint seam between the two copper sheets to be joined, and the blue laser beam is arranged in front of the infrared laser beam along the center line of the joint seam, and the spot center of the blue laser beam is ahead of the spot center of the infrared laser beam in the welding feed direction, so as to weld the joint seam between the two copper sheets to be joined; S3, using a welding speed of 100 mm / s-300 mm / s, setting the power of the blue laser and the infrared laser, wherein the power of the blue laser is set to meet the blue laser beam to heat the welding area without melting the copper sheet, and the power of the infrared laser is set to meet the infrared laser beam to melt the copper near the joint and ensure that the copper sheet is melted through; The welding fixture is designed with a hollow structure corresponding to the copper sheet. During welding, the hollow part of the copper sheet is aligned with the non-hollow part of the fixture. The fixture takes away the heat to offset the uneven heat dissipation caused by the hollow structure of the copper sheet itself. The spot diameter of the blue laser beam is d B The spot diameter of the infrared laser beam is 600-800um. IR The copper sheet laser welding method is suitable for welding copper sheets with a thickness of 0.2 to 0.5 mm and an uneven heat dissipation structure with a hollow pattern.

2. The copper sheet laser welding method according to claim 1, characterized in that: In the step S1, the size of the joint seam between the two copper sheets to be spliced ​​is Δ≤20 um.

3. The copper sheet laser welding method according to claim 1, characterized in that: In step S2, the wavelength of the blue laser beam is 450nm±10nm, and the wavelength of the infrared laser beam is 1080nm±10nm.

4. The copper sheet laser welding method according to any one of claims 1 to 3, characterized in that: In step S2, it is assumed that during the welding process, the spot center of the blue laser beam leads the spot center of the infrared laser beam in the welding feed direction by a distance L, and the spot diameter of the blue laser beam is d B , the spot diameter of the infrared laser beam is d IR , where L satisfies: 0.5d IR ≤L≤d B -0.5 d IR , so that the spot of the infrared laser beam falls entirely within the spot of the blue laser beam.

5. The copper sheet laser welding method according to claim 4, characterized in that: The copper sheet laser welding method also includes the step: S4, turning on the blue laser, the infrared laser and the welding feed execution structure to complete the copper sheet splicing and obtain the welded plate.

6. The copper sheet laser welding method according to claim 5, characterized in that: The copper sheet laser welding method also includes the following steps: S5, turning off the blue laser, the infrared laser and the welding feed execution structure, loosening the welding fixture, taking out the welded plate, and completing the welding.

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