Pure aluminum and pure nickel welding methods

Abstract

This invention relates to the field of laser welding technology, and more particularly to a method for welding pure aluminum and pure nickel. The method includes: determining an initial welding power based on the thicknesses of the pure aluminum and pure nickel materials to be welded; generating a sawtooth power waveform based on the initial welding power according to a preset waveform rule; and controlling a laser welding device to output a corresponding laser beam according to the sawtooth power waveform to weld the pure aluminum and pure nickel materials. Because this invention uses a sawtooth power waveform to direct the laser welding device to output a corresponding laser beam for welding, compared to existing laser welding devices that output a laser beam at a constant power, this invention can output a corresponding laser beam based on the sawtooth power waveform for welding, reducing the evaporation and loss of low-melting-point materials and improving the welding success rate.

Description

Technical Field

[0001] This invention relates to the field of laser welding technology, and more particularly to a method for welding pure aluminum and pure nickel. Background Technology

[0002] Currently, when laser welding pure aluminum and pure nickel, welding is generally carried out by laser welding equipment using a laser beam with constant power output. However, since the melting points of pure aluminum and pure nickel are different, when the low-melting-point material melts, the high-melting-point material is still in a solid state. At this time, the molten material is easy to penetrate into the grain boundaries of the overheated area, causing the low-melting-point material to be lost, resulting in a low welding success rate.

[0003] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0004] The main objective of this invention is to provide a welding method for pure aluminum and pure nickel, which aims to solve the technical problem that welding pure aluminum and pure nickel with constant power in the prior art easily leads to the loss of low melting point materials and a low welding success rate.

[0005] To achieve the above objectives, the present invention provides a method for welding pure aluminum and pure nickel, the method comprising the following steps:

[0006] The initial welding power is determined based on the thickness of the pure aluminum material to be welded and the thickness of the pure nickel material to be welded.

[0007] Based on the initial welding power, a sawtooth power waveform is generated according to a preset waveform rule;

[0008] The laser welding equipment is controlled to output a corresponding laser beam according to the sawtooth power waveform in order to weld the pure aluminum material and the pure nickel material to be welded.

[0009] Optionally, before the step of controlling the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform, the method further includes:

[0010] The sawtooth power waveform is adjusted according to the material properties of the pure aluminum material to be welded and the pure nickel material to be welded to obtain a sawtooth power waveform with a gradually rising power band.

[0011] The laser welding equipment is controlled to output a corresponding laser beam according to the gradually increasing power band, so as to heat up the pure aluminum material and the pure nickel material to be welded.

[0012] Optionally, after the step of generating a sawtooth power waveform based on the initial welding power according to a preset waveform rule, the method further includes:

[0013] The sawtooth power waveform is adjusted according to the material properties of the pure aluminum material to be welded and the pure nickel material to be welded to obtain a sawtooth power waveform with a gradually decreasing power band.

[0014] Accordingly, after the step of controlling the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform, the method further includes:

[0015] The laser welding equipment is controlled to output a corresponding laser beam according to the gradually decreasing power band, so as to cool down the pure aluminum material and the pure nickel material to be welded.

[0016] Optionally, before the step of determining the initial welding power based on the thickness of the pure aluminum material to be welded and the thickness of the pure nickel material to be welded, the method further includes:

[0017] The pure aluminum material and the pure nickel material to be welded are stacked and then pressed together using a pressing device.

[0018] Optionally, after the step of stacking the pure aluminum material to be welded and the pure nickel material to be welded, and pressing the pure nickel material to be welded and the pure aluminum material to be welded together using a preset pressing device, the method further includes:

[0019] Determine the welding points of the pure nickel material to be welded after pressing;

[0020] Accordingly, the step of controlling the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform includes:

[0021] The laser welding equipment is controlled to output a corresponding laser beam to the point to be welded according to the sawtooth power waveform.

[0022] Optionally, the laser welding equipment includes: a laser, a collimator, a galvanometer, and a field lens;

[0023] The laser beam emitted by the laser is output to the welding point through the collimator, galvanometer, and field mirror.

[0024] Optionally, the laser beam output by the laser has a wavelength of 1070 nm.

[0025] Optionally, after the step of controlling the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform to weld the pure aluminum material and the pure nickel material to be welded, the method further includes:

[0026] The welded areas are then inspected.

[0027] When the welding point meets the welding process requirements, welding material is obtained.

[0028] Optionally, the step of inspecting the welded point after welding includes:

[0029] Weld joint inspection is performed on the weld joints at the welded locations after welding.

[0030] After the weld point inspection is completed, metallographic section inspection is performed on the weld point.

[0031] Accordingly, the welding process requires that the welding point be free of spatter, blasts, and cracks, and that the molten pool at the welding point be free of porosity, collapse, and cracks.

[0032] Optionally, after obtaining the welding material when the welding point meets the welding process requirements, the method further includes:

[0033] The welding material is subjected to tensile testing, and welding is completed when the tensile testing meets a preset tensile condition, wherein the preset tensile condition is that the single-point pull-out force of the welding material is greater than 70N.

[0034] This invention determines the initial welding power based on the thicknesses of the pure aluminum and pure nickel materials to be welded; generates a sawtooth power waveform according to a preset waveform rule based on the initial welding power; and controls the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform to weld the pure aluminum and pure nickel materials. Because this invention uses a sawtooth power waveform to direct the laser welding equipment to output a corresponding laser beam for welding, compared to existing laser welding equipment that outputs a laser beam at a constant power, this invention can output a corresponding laser beam based on the sawtooth power waveform for welding, reducing the evaporation and loss of low-melting-point materials and improving the welding success rate. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the first embodiment of the pure aluminum and pure nickel welding method of the present invention;

[0036] Figure 2 This is a schematic diagram of the sawtooth power waveform in the first embodiment of the pure aluminum and pure nickel welding method of the present invention;

[0037] Figure 3 This is a flowchart illustrating the second embodiment of the pure aluminum and pure nickel welding method of the present invention;

[0038] Figure 4 This is a schematic diagram showing the welding points after welding is completed in the second embodiment of the pure aluminum and pure nickel welding method of the present invention.

[0039] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0040] It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0041] This invention provides a method for welding pure aluminum and pure nickel, as described in the following embodiment. Figure 1 , Figure 1 This is a schematic flowchart of the first embodiment of the pure aluminum and pure nickel welding method of the present invention.

[0042] In this embodiment, the method for welding pure aluminum and pure nickel includes the following steps:

[0043] Step S10: Determine the initial welding power based on the thickness of the pure aluminum material to be welded and the thickness of the pure nickel material to be welded.

[0044] It should be noted that the method provided in this embodiment can be applied to the scenario of welding pure aluminum and pure nickel. The pure aluminum can be 1100 pure aluminum, and its chemical composition may include: 99% aluminum, 0.45% silicon, 0.05-0.2% copper, 0.01% zinc, 0.035% manganese, 0.05% vanadium and 0.35% iron; the pure nickel can be N6 pure nickel, and its chemical composition may include: 99.5% nickel, 0.06% copper, 0.1% iron, 0.05% manganese, 0.1% carbon, 0.1% silicon and 0.005% sulfur.

[0045] Understandably, both pure aluminum and pure nickel can be used in the field of power batteries, for example, in the welding of cell tabs and terminals, the welding of battery casings, the welding of cell tabs, and the welding of cell tabs and caps.

[0046] It should be understood that the above-mentioned pure aluminum material to be welded can be 1100 pure aluminum material, with a melting point of 660℃, a boiling point of 2327℃, a specific heat capacity of 232J / (kg·K), a thermal conductivity of 222W / (m*K), and a linear expansion coefficient of 23.6×(10^(-6) / K); the above-mentioned pure nickel material to be welded can be N6 pure nickel material, with a melting point of 1435℃, a boiling point of 2732℃, a specific heat capacity of 473J / (kg·K), a thermal conductivity of 71.4W / (m*K), and a linear expansion coefficient of 13.3×(10^(-6) / K).

[0047] It should be noted that in existing laser welding, due to the different melting points of the two dissimilar metals, when the low-melting-point material melts, the high-melting-point material is still in a solid state. At this time, the molten material is prone to penetrate into the grain boundaries of the overheated zone, causing the loss of low-melting-point material, the burning and evaporation of alloying elements, which changes the chemical composition of the weld and makes it difficult to control the mechanical properties.

[0048] Meanwhile, due to the different coefficients of linear expansion of dissimilar metals, large welding stress and welding deformation are generated during the crystallization of the molten pool. Because the stress states on both sides of the weld are different, cracks are easily generated in the weld and heat-affected zone, and even the weld metal may peel off from the base metal.

[0049] Secondly, the difference in thermal conductivity and specific heat capacity between dissimilar metals leads to a deterioration in the crystallization conditions of the weld metal, resulting in coarse grains and affecting the wetting properties of refractory metals. Furthermore, the changes in thermophysical parameters such as the coefficient of linear expansion, thermal conductivity, and specific heat capacity with temperature make the laser welding process of dissimilar metals more complex.

[0050] Furthermore, since dissimilar metal welding easily produces intermetallic compounds and causes changes in the microstructure, the mechanical properties of the weld joint decrease, especially the heat-affected zone, which is prone to cracking. Based on the above reasons, this embodiment provides a welding method for pure aluminum and pure nickel to solve the above problems.

[0051] It is understandable that the aforementioned initial welding power can be a constant power when welding pure aluminum and pure nickel. Since the existing welding of pure aluminum and pure nickel uses a constant power, the aforementioned initial welding power can be the aforementioned constant power.

[0052] It should be understood that different thicknesses require different welding power. The larger the thickness, the greater the initial welding power required, and the smaller the thickness, the smaller the initial welding power required. Therefore, in this embodiment, the initial welding power can be determined first based on the thickness of the pure aluminum material to be welded and the thickness of the pure nickel material to be welded.

[0053] Furthermore, to prevent the pure aluminum and pure nickel materials to be welded from shifting during the welding process, in this embodiment, before step S10, the following steps are also included:

[0054] Step S01: Stack the pure aluminum material to be welded and the pure nickel material to be welded, and press the pure nickel material to be welded and the pure aluminum material to be welded together using a pressing device.

[0055] It should be noted that the above stacking can be the process of stacking the pure nickel material to be welded on top of the pure aluminum material to be welded, and the above pressing equipment can be the equipment used for pressing and fixing during welding. Pressing can be continuously performed through the above pressing equipment during the welding process. The specific equipment is not limited in this embodiment.

[0056] In practice, the pure nickel material to be welded can be stacked on top of the pure aluminum material to be welded and pressed together using a pressing device. The initial welding power is then determined based on the thickness of the pure aluminum material and the thickness of the pure nickel material to be welded.

[0057] Step S20: Generate a sawtooth power waveform based on the initial welding power according to a preset waveform rule.

[0058] It is understandable that the aforementioned preset waveform rules can be rules for adjusting the initial welding power. For ease of understanding, refer to... Figure 2 To explain, Figure 2 This is a schematic diagram of the sawtooth power waveform in the first embodiment of the pure aluminum and pure nickel welding method of the present invention, as shown below. Figure 2 As shown, the horizontal axis represents time in milliseconds (ms), and the vertical axis represents power in watts (W). Four coordinate points are set in the sawtooth power waveform for illustration: a, b, c, and d. The dashed line in the figure can represent the initial welding power. The preset waveform rules can be adjusted based on the initial welding power to increase or decrease the power, thereby obtaining the bc band as the sawtooth power waveform.

[0059] It should be emphasized that the above-mentioned preset waveform rules do not limit the increase or decrease of the initial welding power in this embodiment.

[0060] In practice, after determining the initial welding power, the initial welding power can be adjusted according to the preset waveform rules to generate a sawtooth power waveform.

[0061] Step S30: Control the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform, so as to weld the pure aluminum material and the pure nickel material to be welded.

[0062] It should be understood that the aforementioned laser welding equipment can be used for laser welding of pure aluminum and pure nickel materials.

[0063] In practical implementation, the laser welding equipment is controlled according to... Figure 2 The sawtooth power waveform output in the mid-bc band corresponds to the laser beam, which in turn agitates the molten pool during welding, preventing the evaporation and vaporization of low-melting-point materials, reducing welding stress, and reducing the generation of impurities during welding, thereby improving welding quality.

[0064] Furthermore, since spot welding can be used when welding pure aluminum and pure nickel materials, after step S01, the method further includes: determining the welding points of the pressed pure nickel material; correspondingly, step S30 includes: controlling the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform to weld the pure aluminum and pure nickel materials.

[0065] It should be noted that the location of the welding point can be set according to the actual situation, and this embodiment does not impose any restrictions.

[0066] It should also be noted that the laser welding equipment described above in this embodiment may include: a laser, a collimator, a galvanometer, and a field lens; the laser beam emitted by the laser is sequentially output to the welding point through the collimator, galvanometer, and field lens. The laser may be a single-mode QCW (quasi-continuous) laser with a wavelength of 1070nm, an fiber core diameter of 14µm, and a pulse width in the millisecond range. The purpose of using this laser is to ensure good laser beam quality and a divergence of less than 1.2, which is beneficial for overcoming the absorption threshold of the material.

[0067] Understandably, the collimator mentioned above can be an F120 collimator, and the field lens can be an F210 field lens. The purpose of using such a small core diameter, large collimation and large field lens is to make the focused spot smaller, obtain higher power density and transmission performance. The purpose of choosing a galvanometer is to achieve faster speed. The time required for a single solder joint can be less than 0.2 seconds. The processing speed is fast and the efficiency is high, which is conducive to the needs of industrial mass production.

[0068] This embodiment first determines the initial welding power based on the thicknesses of the pure aluminum and pure nickel materials to be welded. Then, based on the initial welding power, a sawtooth power waveform is generated according to a preset waveform rule. Finally, the laser welding equipment is controlled to output a corresponding laser beam according to the generated sawtooth power waveform to weld the pure aluminum and pure nickel materials. Compared to existing welding methods based on constant power, this embodiment welds by outputting a laser beam corresponding to the sawtooth power waveform. During the welding process, the molten pool is stirred, preventing the evaporation and vaporization of low-melting-point materials, reducing welding stress, and also reducing the generation of impurities during the welding process, thus improving welding quality.

[0069] Furthermore, in order to enable the material to better absorb the energy of the laser beam during the welding process, existing methods generally output the laser beam directly based on the sawtooth power waveform at the start of welding, as referenced. Figure 3 , Figure 3 This is a schematic flowchart of the second embodiment of the pure aluminum and pure nickel welding method of the present invention. Figure 3 As shown, in this embodiment, before step S30, the following steps are also included:

[0070] Step S301: Adjust the sawtooth power waveform according to the material properties of the pure aluminum material to be welded and the pure nickel material to be welded to obtain a sawtooth power waveform with a gradually rising power band.

[0071] It should be noted that the aforementioned material properties can include the melting point, boiling point, specific heat capacity, thermal conductivity, coefficient of linear expansion, etc. In this embodiment, the start time of the sawtooth power waveform can be adjusted according to the material properties of the pure aluminum material to be welded and the pure nickel material to be welded. For ease of understanding, please refer to... Figure 2 To explain, Figure 2The ab band is the aforementioned gradually increasing power band.

[0072] It should be emphasized that the time corresponding to the aforementioned gradually increasing power band can be set according to the material characteristics, and this embodiment does not impose any restrictions.

[0073] Step S302: Control the laser welding equipment to output the corresponding laser beam according to the gradually increasing power band, so as to heat up the pure aluminum material and the pure nickel material to be welded.

[0074] In practice, the power waveform of the sawtooth pattern can be adjusted according to the material characteristics, and the laser welding can be controlled to output the corresponding laser beam according to the gradually increasing power band. The gradually increasing power band can make the material heat up slowly, which prepares the material to better absorb the laser beam energy in the future.

[0075] Furthermore, considering that the laser beam is typically stopped immediately after the sawtooth power band ends, which could lead to porosity and cracks in the molten pool, affecting welding quality, this embodiment further includes the following step after step S20:

[0076] Step S21: Adjust the sawtooth power waveform according to the material properties of the pure aluminum material to be welded and the pure nickel material to be welded to obtain a sawtooth power waveform with a gradually decreasing power band.

[0077] It is understandable that the time corresponding to the power descent band can also be set according to the material properties. This embodiment does not limit the specific setting method, and will continue to refer to [the relevant documentation]. Figure 2 To explain, Figure 2 The medium CD band is the aforementioned band with gradually decreasing power.

[0078] Accordingly, after the step of controlling the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform, the method further includes: controlling the laser welding equipment to output a corresponding laser beam according to the slow-decreasing power band, so as to cool down the pure aluminum material and the pure nickel material to be welded.

[0079] For easier understanding, please refer to Figure 4 To explain, Figure 4 This is a schematic diagram showing the welding points after completion in the second embodiment of the pure aluminum and pure nickel welding method of the present invention;

[0080] from Figure 4 It can be seen that the welding points after welding using the above method are free of pores and cracks, and the welding quality is good.

[0081] In practice, after the sawtooth power waveform of the bc band ends, the laser welding equipment can be controlled to output the corresponding laser beam according to the slow-decreasing power band of the cd band, so that the molten pool cools down slowly and prevents the generation of pores and cracks.

[0082] Furthermore, in order to inspect the welding quality, in this embodiment, after step S30 above, the following step is also included:

[0083] Step S40: Inspect the welded points after welding;

[0084] Step S50: When the welding point meets the welding process requirements, obtain the welding material.

[0085] It should be understood that the inspection of the welding point may specifically include: inspecting the weld point after welding; performing metallographic sectioning on the welding point after the weld point inspection is completed; correspondingly, the welding process requires that the welding point be free of spatter, blasts, and cracks, and that the molten pool of the welding point be free of porosity, collapse, and cracks.

[0086] It should be noted that the above-mentioned weld point inspection can detect whether there is spatter, blasting, or cracks at the weld point, while the above-mentioned metallographic section inspection can detect whether there is porosity, collapse, or cracks in the molten pool at the weld point.

[0087] Furthermore, a tensile test is required on the welding material. The specific process is as follows: after obtaining the welding material when the welding process requirements are met at the welding point, the process further includes: performing a tensile test on the welding material, and completing the welding when the tensile test meets a preset tensile condition, wherein the preset tensile condition is that the single-point pull-out force of the welding material is greater than 70N.

[0088] It should be emphasized that the equipment for weld point inspection, metallographic section inspection, and tensile testing mentioned above can be selected according to the actual situation in this embodiment, and there are no restrictions in this embodiment.

[0089] This embodiment can control the output of the laser welding equipment by gradually increasing and decreasing the power band, thereby further improving the welding quality.

[0090] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0091] The sequence numbers of the above embodiments of the present invention are merely for description and do not represent the superiority or inferiority of the embodiments. Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as read-only memory / random access memory, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0092] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for welding pure aluminum and pure nickel, characterized in that, The method includes the following steps: The initial welding power is determined based on the thickness of the pure aluminum material to be welded and the thickness of the pure nickel material to be welded. Based on the initial welding power, a sawtooth power waveform is generated according to a preset waveform rule; The sawtooth power waveform is adjusted according to the material properties of the pure aluminum material to be welded and the pure nickel material to be welded to obtain a sawtooth power waveform with a gradually rising power band. The sawtooth power waveform is adjusted according to the material properties of the pure aluminum material to be welded and the pure nickel material to be welded to obtain a sawtooth power waveform with a gradually decreasing power band. The laser welding equipment is controlled to output a corresponding laser beam according to the gradually increasing power band, so as to heat up the pure aluminum material and the pure nickel material to be welded; The laser welding equipment is controlled to output a corresponding laser beam according to the sawtooth power waveform; The laser welding equipment is controlled to output a corresponding laser beam according to the gradually decreasing power band, so as to cool down the pure aluminum material and the pure nickel material to be welded, and then weld the pure aluminum material and the pure nickel material to be welded.

2. The method for welding pure aluminum and pure nickel as described in claim 1, characterized in that, Before the step of determining the initial welding power based on the thickness of the pure aluminum material to be welded and the thickness of the pure nickel material to be welded, the method further includes: The pure aluminum material and the pure nickel material to be welded are stacked and then pressed together using a pressing device.

3. The method for welding pure aluminum and pure nickel as described in claim 2, characterized in that, After the step of stacking the pure aluminum material and the pure nickel material to be welded, and pressing the pure nickel material and the pure aluminum material to be welded together using a preset pressing device, the method further includes: Determine the welding points of the pure nickel material to be welded after pressing; Accordingly, the step of controlling the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform includes: The laser welding equipment is controlled to output a corresponding laser beam to the point to be welded according to the sawtooth power waveform.

4. The method for welding pure aluminum and pure nickel as described in claim 3, characterized in that, The laser welding equipment includes: a laser, a collimator, a galvanometer, and a field lens; The laser beam emitted by the laser is output to the welding point through the collimator, galvanometer, and field mirror.

5. The method for welding pure aluminum and pure nickel as described in claim 4, characterized in that, The laser outputs a laser beam with a wavelength of 1070 nm.

6. The method for welding pure aluminum and pure nickel as described in claim 3, characterized in that, After the step of controlling the laser welding equipment to output a corresponding laser beam according to the sawtooth power waveform to weld the pure aluminum material and the pure nickel material to be welded, the method further includes: The welded areas are then inspected. When the welding point meets the welding process requirements, welding material is obtained.

7. The method for welding pure aluminum and pure nickel as described in claim 6, characterized in that, The step of inspecting the welded points after welding includes: Weld joint inspection is performed on the weld joints at the welded locations after welding. After the weld point inspection is completed, metallographic section inspection is performed on the weld point. Accordingly, the welding process requires that the welding point be free of spatter, blasts, and cracks, and that the molten pool at the welding point be free of porosity, collapse, and cracks.

8. The method for welding pure aluminum and pure nickel as described in claim 7, characterized in that, After obtaining the welding material when the welding process requirements are met at the welding point, the method further includes: The welding material is subjected to tensile testing, and welding is completed when the tensile testing meets a preset tensile condition, wherein the preset tensile condition is that the single-point pull-out force of the welding material is greater than 70N.

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