Laser welding method

Abstract

The present application provides a laser welding method, comprising clamping and positioning a workpiece to be welded on a clamping tool, determining parameters directly influencing a spatter-free welding effect, wherein the parameters directly influencing a spatter-free welding effect include a laser weld amplitude ratio and a weld temperature of the workpiece to be welded; selecting laser welding parameters and designing a laser welding process test; screening out a welding parameter group data interval that satisfies the laser weld amplitude ratio based on the laser welding process experiment; continuing to perform a laser welding process test on the basis of the welding parameter group data interval to optimize parameters, and screening out welding parameter group data that satisfies the weld temperature; performing a performance test on a sample workpiece welded using the welding parameter group data; and screening out a set of optimized spatter-free process parameter group data for laser welding based on the results of the performance test, thereby achieving spatter-free welding of the welded workpiece and having the beneficial effect of ensuring welding quality and welding efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of laser welding, and in particular to a spatter-free laser welding method. Background Art

[0002] Laser welding is a technology that uses a laser beam to locally melt the surface of a material and cool it to form a weld. Compared with traditional welding methods, laser welding machines do not require the addition of any solder during the welding process, so they do not produce a lot of smoke and exhaust gas like gas welding or arc welding. However, during the laser welding process, due to the high temperature environment and the reaction of the metal surface, a certain amount of smoke and dust will be generated. These smoke and dust are mainly composed of oxides or other compounds formed by the evaporation of the metal surface to be welded and the reaction with oxygen or other gases in the air, which in turn causes spattering on the metal surface of the weldment during the welding process.

[0003] In the existing technology, it is generally believed that spatter generated during laser welding is a normal phenomenon, which has weakened the in-depth research on spatter-free laser welding. Even though the spark spatter is minimized by processing the surface finish of the workpiece to be welded and considering laser welding parameters such as laser pulse width, laser power, laser frequency and welding speed, no specific method for adjusting spatter-free laser welding parameters has been formed.

[0004] Therefore, for researchers in this field, there is an urgent need to develop a laser welding method that can better achieve spatter-free welding with high efficiency. Summary of the Invention

[0005] In view of this, in order to solve the above-mentioned problems, an embodiment of the present invention provides a laser welding method, which screens out a set of optimized spatter-free process parameter group data for laser welding, realizes spatter-free welding of the workpiece to be welded, and has the beneficial effect of ensuring welding quality and high efficiency, avoiding the spark splashing generated in the existing laser welding process and the technical problems of poor welding effect and low efficiency that may be caused.

[0006] To achieve the above object, an embodiment of the present invention provides a laser welding method, comprising the following steps:

[0007] Step S1, clamping and positioning the workpiece to be welded on a clamping tool, and determining parameters directly influencing the spatter-free welding effect, wherein the parameters directly influencing the spatter-free welding effect include the laser weld amplitude ratio and the weld temperature of the workpiece to be welded;

[0008] Step S2: Select laser welding parameters and design laser welding process test;

[0009] Step S3: screening out a welding parameter group data interval range that satisfies the laser weld amplitude ratio according to a laser welding process experiment;

[0010] Step S4: Based on the range of the welding parameter group data, continue to perform laser welding process tests to optimize parameters, and screen out welding parameter group data that meets the weld temperature;

[0011] Step S5, performing a performance test on the sample workpiece welded using the welding parameter group data;

[0012] Step S6: Obtaining optimized spatter-free process parameter group data for laser welding based on the results of the performance test.

[0013] Furthermore, in step S2, the laser welding process test includes an orthogonal test and a single variable test.

[0014] Furthermore, in step S3, based on the laser welding process experiment, the data interval range of the welding parameter group that meets the laser weld amplitude ratio is screened out; specifically, the orthogonal test is used to screen out the data interval range of the welding parameter group that meets the laser weld amplitude ratio.

[0015] Furthermore, in step S4, based on the range of the welding parameter group data, the laser welding process test is continued to be performed to optimize the parameters, and the welding parameter group data that meets the weld temperature is screened out; specifically, based on the range of the welding parameter group data obtained by the orthogonal test, the univariate test is further used to screen out the welding parameter group data that meets the weld temperature.

[0016] Furthermore, the laser welding parameters include laser pulse width, laser frequency, laser power and welding speed.

[0017] Furthermore, the orthogonal test comprises the following steps:

[0018] Step S31, selecting four parameters with better welding effects from the laser welding parameters, and designing a four-factor four-level orthogonal experiment, wherein the four factors are laser pulse width, laser frequency, laser power, and welding speed;

[0019] Step S32: According to the orthogonal test scheme of step S31, a welding parameter group data interval range that meets the laser weld amplitude ratio is screened and obtained.

[0020] Furthermore, the univariate test includes the following steps:

[0021] Step S41, fixing the laser pulse width, laser frequency and welding speed, and changing the laser power so that the weld temperature is not less than the preset temperature for spatter-free welding;

[0022] Step S42: fixing the laser pulse width, laser frequency, and laser power, and changing the welding speed so that the weld temperature is not less than a preset temperature for spatter-free welding;

[0023] Step S43: According to the optimization process of step S41 and step S42, three groups of welding parameter group data that meet the welding seam temperature are screened out.

[0024] Furthermore, in the step S5, a performance test is performed on the sample workpiece welded using the welding parameter group data;

[0025] Specifically, the three sets of welding parameter data selected in step S43 are used to perform laser welding respectively to obtain three laser welded sample workpieces, and tensile tests are performed on the three laser welded sample workpieces to obtain tensile stress-strain curves. The tensile properties of the three sample workpieces are compared to obtain a set of optimized spatter-free process parameter data for laser welding.

[0026] Beneficial effects of the present invention:

[0027] The present invention provides a spatter-free laser welding method, which specifically includes step S1, clamping and positioning the workpiece to be welded on a clamping tool, and determining parameters that directly affect the spatter-free welding effect, wherein the parameters that directly affect the spatter-free welding effect include the laser weld amplitude ratio and the weld temperature of the workpiece to be welded; step S2, selecting laser welding parameters and designing a laser welding process test; step S3, based on the laser welding process experiment, screening out a welding parameter group data interval range that meets the laser weld amplitude ratio; step S4, based on the welding parameter group data interval range, continuing to perform laser welding process tests to optimize parameters, and screening out welding parameter group data that meets the weld temperature; step S5, performing performance testing on a sample workpiece welded using the welding parameter group data; step S6, screening out a set of optimized spatter-free process parameter group data for laser welding based on the results of the performance test, thereby achieving spatter-free welding of the welding workpiece and having the beneficial effect of ensuring welding quality and welding efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The following drawings are used to provide a further understanding of the present application, constitute a part of the present application, and are intended only to illustrate and describe the present invention, and are not intended to limit the scope of the present invention. In the drawings:

[0029] Figure 1 This is a flow chart of a laser welding method according to an embodiment of the present application;

[0030] Figure 2 This is a flow chart of a laser welding method according to another embodiment of the present application;

[0031] Figure 3This is a flow chart of a laser welding method according to another embodiment of the present application;

[0032] Figure 4 In the embodiment of the present application, two sets of welding parameter data are used to respectively perform tensile stress-strain curves of sample workpieces after laser welding. DETAILED DESCRIPTION

[0033] Several embodiments of the present application will be disclosed below with diagrams to clearly and completely describe the technical solution of the present invention. The drawings that constitute part of the specification of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] The technical solutions between the various embodiments of the present application can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0035] The following contents are all examples of specific implementation processes provided for detailed description of the technical solutions to be protected by this application. However, this application can also be implemented in other ways different from the descriptions here. Those skilled in the art can adopt different technical means to implement this application under the guidance of the concept of this application. Therefore, this application is not limited to the specific embodiments below.

[0036] The present application provides a laser welding method, comprising the following steps: step S1, clamping and positioning the workpiece to be welded on a clamping tool, and determining parameters directly affecting the spatter-free welding effect, wherein the parameters directly affecting the spatter-free welding effect include the laser weld amplitude ratio and the weld temperature of the workpiece to be welded; step S2, selecting laser welding parameters and designing a laser welding process test; step S3, based on the laser welding process experiment, screening out a welding parameter group data interval range that meets the laser weld amplitude ratio; step S4, based on the welding parameter group data interval range, continuing to perform laser welding process tests to optimize parameters, and screening out welding parameter group data that meets the weld temperature; step S5, performing a performance test on a sample workpiece welded using the welding parameter group data; step S6, obtaining the optimized spatter-free process parameter group data for laser welding based on the results of the performance test, thereby achieving spatter-free welding of the welded workpiece, while having the beneficial effect of ensuring welding quality and welding efficiency.

[0037] Specifically, see Figure 1The figure shows a flow chart of a laser welding method for screening and obtaining an optimized spatter-free process parameter group data for laser welding.

[0038] This example uses an RF-HQ2000 fiber laser as an example to illustrate the steps for optimizing and screening a set of spatter-free process parameter data for laser welding of a 1.5mm-thick aluminum alloy thin-walled structural component from a combat-damaged aircraft. First, the 1.5mm-thick aluminum alloy sheet is clamped and positioned on a fixture. The welding path is set so that the laser beam, with the laser head height and focal length adjusted, can weld along the welding path. Parameters directly influencing the spatter-free welding effect are determined. These parameters include the laser weld seam amplitude ratio and weld seam temperature of the welded component.

[0039] It should be noted that before the 1.5mm thick aluminum alloy sheet is clamped and positioned on the clamping tool, the surface finish of the workpiece to be welded is processed and the welding path is designed. The design of the welding path is preferably not limited to the design of an S-shaped curved weld joint to fully ensure the welding quality and accurate selection of laser welding parameter data. The clamping tool of this embodiment is a common fixture used in existing laser welding tooling; the laser weld amplitude ratio is defined as the ratio of weld depth to weld width. When the ratio of weld depth to weld width is 0.5 and the weld temperature is not less than 300°C, the aluminum alloy sheet can be efficiently laser welded while ensuring weld quality and achieving the unique effect of spatter-free.

[0040] The laser weld amplitude ratio during laser welding is equal to 0.5. This application first uses the orthogonal test method to explore the parameter range to achieve the experimental goal. For details, please refer to Figure 2 The specific steps of the orthogonal test are as follows: step S31, selecting four parameters for ensuring the welding quality and welding efficiency of the aluminum alloy from the laser welding parameters, and designing a four-factor four-level orthogonal test, wherein the four factors are laser pulse width, laser frequency, laser power, and welding speed; step S32, according to the orthogonal test scheme of step S31, screening and obtaining the welding parameter group data interval range that satisfies the laser weld amplitude ratio equal to 0.5. The orthogonal test table is shown below:

[0041]

[0042] It can be seen that this application changes the four parameter factors of laser welding parameters, namely laser pulse width, laser frequency, laser power and welding speed, and sets four levels for each parameter factor using the orthogonal experimental method to screen out the welding parameter group data range with a laser weld amplitude ratio equal to 0.50: laser pulse width 2000ns, laser frequency 20~40KHz, laser power 600~800W and welding speed 1000~1500mm / min.

[0043] Furthermore, based on the data interval range of the welding parameter group, the process parameters are further optimized through the single variable test method, in order to achieve the unique effect of no spatter while ensuring the welding quality of aluminum alloy plates. Figure 3 The steps of the single variable experiment are as follows: step S41, fix the laser pulse width, laser frequency and welding speed, change the laser power so that the weld temperature is not less than the preset temperature of spatter-free welding; step S42, fix the laser pulse width, laser frequency and laser power, change the welding speed so that the weld temperature is not less than the preset temperature of spatter-free welding; step S43, according to the optimization process of steps S41 and S42, screen out three groups of welding parameter group data that meet the weld temperature.

[0044] It should be noted that the preset temperature for spatter-free welding in this embodiment is set according to the material properties of the welding workpiece. For example, the preset temperature of the aluminum alloy plate is set to 300°C, and the preset temperature of the metal iron is set to 400°C. The preset temperature for spatter-free welding set for different welding materials is also different, and thus the welding parameter group data corresponding to different welding workpieces will also be different, which needs to be obtained based on the specific laser welding process test screening.

[0045] In addition, while the laser pulse width and laser frequency have little effect on weld temperature, when the laser frequency is greater than 40 kHz, the weld depth becomes increasingly shallow as the welding speed increases. Therefore, a fixed laser pulse width of 2000 ns and a laser frequency of 40 kHz were used to continue single-variable experiments by varying the laser power and welding speed, in order to achieve the necessary and sufficient conditions for spatter-free welding of aluminum alloys: while ensuring that the laser weld amplitude ratio is equal to 0.50, the weld temperature must be no less than the preset temperature of 300°C for spatter-free welding. The single-variable experiment table is as follows:

[0046]

[0047] According to the above table, further screening can be directly conducted to obtain the optimization results: under the premise of ensuring that the amplitude ratio of the aluminum alloy laser weld is equal to 0.50, the three groups of welding parameter group data that make the weld temperature not less than the preset temperature of 300°C for spatter-free welding are: parameter group 1: laser pulse width 2000ns, laser repetition frequency 40KHz, laser power 675W, welding speed 1050mm / min; parameter group 2: laser pulse width 2000ns, laser repetition frequency 40KHz, laser power 750W, welding speed 1250mm / min; parameter group 3: laser pulse width 2000ns, laser repetition frequency 40KHz, laser power 750W, welding speed 1350mm / min.

[0048] As a preferred embodiment, in step S5, a performance test is performed on the sample workpiece welded using the welding parameter group data; specifically, laser welding is performed using the three sets of welding parameter group data selected in step S43 to obtain three laser-welded sample workpieces, and a tensile test is performed on the three laser-welded sample workpieces. Figure 4 As shown, the tensile stress-strain curves of parameter group 1, parameter group 2, parameter group 3 and the base material are obtained, and the tensile strength of the sample is calculated by the tensile stress. The tensile strength is calculated using the following formula:

[0049]

[0050] Where σ represents the tensile strength, F b represents the maximum tensile stress, and S represents the cross-sectional area of ​​the specimen.

[0051] By comparing the tensile properties of the three sample workpieces, it can be concluded that parameter group 3 is the optimized spatter-free process parameter group data for aluminum alloy laser welding, namely, laser pulse width 2000ns, laser repetition frequency 40KHz, laser power 750W, and welding speed 1350mm / min.

[0052] It should be noted that since laser welding will affect the material itself and thus affect the material properties, the significance of testing the tensile properties here is to explore whether the welding method has an impact on the material properties. The tensile properties of the plate after welding should reach at least 90% of the parent material itself, which is conducive to ensuring that this application can further confirm the actual use of the material under the premise of achieving the technical effect of spatter-free welding.

[0053] In summary, the laser welding method provided by the present invention specifically includes step S1, clamping and positioning the workpiece to be welded on the clamping tool, determining the parameters directly affecting the spatter-free welding effect, and the parameters directly affecting the spatter-free welding effect include the laser weld amplitude ratio and the weld temperature of the workpiece to be welded; step S2, selecting laser welding parameters and designing a laser welding process test; step S3, based on the laser welding process experiment, screening out the welding parameter group data interval range that meets the laser weld amplitude ratio; step S4, on the basis of the welding parameter group data interval range, continuing to perform laser welding process tests to optimize parameters, and screening out welding parameter group data that meets the weld temperature; step S5, performing performance testing on the sample workpiece welded using the welding parameter group data; step S6, screening out a set of optimized spatter-free process parameter group data for laser welding based on the results of the performance test, so as to achieve spatter-free welding of the welding workpiece, while having the beneficial effect of ensuring welding quality and welding efficiency.

[0054] The present application is described with reference to flowcharts and / or block diagrams of methods and computer program products according to embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as combinations of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. Instructions executed by a processor of a computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0055] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0056] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0057] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0058] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A laser welding method, characterized in that: The steps include: Step S1, clamping and positioning the workpiece to be welded on a clamping tool, and determining parameters directly influencing the spatter-free welding effect, wherein the parameters directly influencing the spatter-free welding effect include the laser weld amplitude ratio and the weld temperature of the workpiece to be welded; Step S2: Select laser welding parameters and design a laser welding process test, wherein the laser welding process test includes an orthogonal test and a single variable test; Step S3, based on the laser welding process test, using the orthogonal test to screen out the welding parameter group data interval range that meets the laser weld amplitude ratio, specifically comprising the following steps: Step S31, selecting four parameters with better welding effects from the laser welding parameters, and designing a four-factor four-level orthogonal experiment, wherein the four factors are laser pulse width, laser frequency, laser power, and welding speed; Step S32: According to the orthogonal test scheme of step S31, a welding parameter group data interval range that satisfies the laser weld amplitude ratio is screened and obtained; Step S4, based on the range of the welding parameter group data obtained by the orthogonal test, continuing the laser welding process test to optimize the parameters, further using the single variable test to screen and obtain the welding parameter group data that meets the weld temperature, specifically includes the following steps: Step S41, fixing the laser pulse width, laser frequency and welding speed, and changing the laser power so that the weld temperature is not less than the preset temperature for spatter-free welding; Step S42: fixing the laser pulse width, laser frequency, and laser power, and changing the welding speed so that the weld temperature is not less than a preset temperature for spatter-free welding; Step S43: According to the optimization process of step S41 and step S42, three sets of welding parameter group data that meet the welding seam temperature are screened out; Step S5, performing a performance test on the sample workpiece welded using the welding parameter group data; Step S6: Obtaining optimized spatter-free process parameter group data for laser welding based on the results of the performance test.

2. The laser welding method according to claim 1, wherein: The laser welding parameters include laser pulse width, laser frequency, laser power and welding speed.

3. The laser welding method according to claim 1, wherein: In the step S5, the performance test is performed on the sample workpiece welded using the welding parameter group data; Specifically, laser welding is performed respectively using the three sets of welding parameter group data screened out in step S43 to obtain three laser-welded sample workpieces, and tensile tests are performed on the three laser-welded sample workpieces to obtain tensile stress-strain curves. The tensile properties of the three sample workpieces are compared to obtain a set of optimized spatter-free process parameter group data for laser welding.

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