A silver-free brazing method for connecting stainless steel and copper air conditioning pipes.

Abstract

This invention relates to the field of welding, and more particularly to a silver-free brazing method for air conditioning connecting pipes based on stainless steel and copper pipes. The method includes: first, removing the oxide layer from the copper pipe and determining the surface roughness, thereby determining wetting parameters; second, deploying a camera to acquire welding ripple images and calculating fluctuation characterization values, thereby determining whether the unit welding process meets the standard and determining the frequency of abnormal fluctuations; third, judging whether the overall welding process meets the standard and the reasons for non-compliance based on the frequency of abnormal fluctuations, and adjusting the wetting parameters accordingly; finally, verifying the welding process, and compensating for non-compliance by treating the deoxide layer. This invention, through technologies such as quantifying the correlation between surface roughness and wetting parameters, classifying and determining abnormal fluctuations, and real-time monitoring and dynamic parameter adjustment of ripples, eliminates the use of precious metal silver, avoids toxic gases, meets environmental protection requirements, and provides an efficient and stable solution for the manufacture of air conditioning connecting pipes.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a welding method for silver-free brazing of air conditioning connecting pipes based on stainless steel pipes and copper pipes. Background Technology

[0002] In the air conditioning manufacturing industry, the connection between stainless steel and copper pipes is a crucial step in the refrigeration system. Traditional welding methods often employ silver brazing, but silver, as a precious metal, is expensive and scarce, resulting in high welding costs. Furthermore, silver brazing requires strict operating conditions and may generate harmful gases during the process, posing potential risks to worker health and the environment. As the air conditioning industry moves towards higher efficiency, environmental friendliness, and lower costs, silver-free brazing technology has become a hot research topic.

[0003] Silver-free brazing aims to achieve weld strength and sealing performance comparable to silver brazing by optimizing filler metal formulations and improving welding processes, while reducing costs. However, the physical properties of stainless steel and copper pipes differ significantly. Silver-free brazing requires more stringent surface treatment and flux selection; otherwise, defects such as poor wetting, porosity, and cracks are prone to occur, severely impacting weld quality. Therefore, achieving a reliable connection between the two materials through process control is the core challenge of silver-free brazing technology. Summary of the Invention

[0004] Therefore, the present invention provides a silver-free brazing method for air conditioning connecting pipes based on stainless steel pipes and copper pipes, in order to overcome the problems of poor wetting, porosity and cracks that easily occur during the welding process in the prior art.

[0005] To achieve the above objectives, the present invention provides a system comprising:

[0006] Step S1: After removing the surface oxide layer at the copper tube welding location, obtain the surface roughness of the welding location;

[0007] Step S2: Determine the wetting parameters for brazing the stainless steel pipe and the copper pipe based on the surface roughness of the welding position. The wetting parameters include the preheating temperature and the protective gas flow rate.

[0008] Step S3: Place a camera directly above the welding point to obtain an image of the welding ripples within a unit welding stroke;

[0009] Step S4: Obtain the fluctuation characterization value based on the welding ripple image of the welding point;

[0010] Step S5: Based on the fluctuation characterization value, if the welding process of stainless steel pipe and copper pipe within a unit welding process is not up to standard, complete the overall welding process and determine the frequency of abnormal fluctuations.

[0011] Step S6: Determine the reasons for the substandard overall welding process between the stainless steel pipe and the copper pipe based on the frequency of abnormal fluctuations, and adjust the wetting parameters for the substandard overall welding process.

[0012] Step S7: Verify whether the welding process between the stainless steel pipe and the copper pipe meets the standard based on the corrected abnormal fluctuation frequency threshold after adjusting the wetting parameters, and compensate for the deoxidation treatment of the copper pipe whose welding process does not meet the standard.

[0013] Furthermore, the fluctuation characterization value is the variance of the height of each peak in the welding ripple.

[0014] Furthermore, based on the fluctuation characterization value, it is determined whether the welding process between the stainless steel pipe and the copper pipe within a unit welding stroke meets the standard, wherein,

[0015] If the fluctuation characterization value is less than the preset fluctuation characterization value threshold, then the welding process of stainless steel pipe and copper pipe within the unit welding stroke is deemed to meet the standard.

[0016] If the fluctuation characterization value is greater than or equal to the preset fluctuation characterization threshold, it is determined that the welding process of stainless steel pipe and copper pipe within the unit welding process is substandard.

[0017] Furthermore, the result of the stainless steel pipe and copper pipe welding process failing to meet the standard within a unit welding process is recorded as an abnormal fluctuation, and the number of abnormal fluctuations in the stainless steel pipe and copper pipe welding process within the entire welding process is recorded as the abnormal fluctuation frequency.

[0018] Furthermore, the overall welding process between the stainless steel pipe and the copper pipe is determined based on the frequency of the abnormal fluctuations, wherein...

[0019] If the frequency of the abnormal fluctuation is less than the first preset abnormal fluctuation frequency threshold, then the overall welding process of the stainless steel pipe and the copper pipe is determined to be up to standard.

[0020] If the frequency of abnormal fluctuations is greater than or equal to the first preset abnormal fluctuation frequency threshold and less than the second preset abnormal fluctuation frequency threshold, then it is determined that the overall welding process of the stainless steel pipe and the copper pipe is substandard, and the reason for the substandard overall welding process is that the protective gas flow rate in the wetting parameters is too high.

[0021] If the frequency of abnormal fluctuations is greater than or equal to the second preset threshold for abnormal fluctuations, it is determined that the overall welding process of the stainless steel pipe and the copper pipe is substandard, and the reason for the substandard overall welding process is that the preheating temperature in the wetting parameters is low.

[0022] Furthermore, in response to the overall welding process failing to meet the standard due to a large shielding gas flow rate in the wetting parameters, the shielding gas flow rate for the next batch of connecting pipe welding is reduced, and the reduction in shielding gas flow rate is positively correlated with the difference between the abnormal fluctuation frequency and the first preset abnormal fluctuation frequency threshold.

[0023] Furthermore, in response to the overall welding process failing to meet standards due to a low preheating temperature in the wetting parameters, the preheating temperature for the next batch of connecting pipes is increased, and the adjustment range of the preheating temperature is positively correlated with the difference between the abnormal fluctuation frequency and the second preset abnormal fluctuation frequency threshold. Furthermore, the welding process of the stainless steel pipe and copper pipe is verified to meet standards based on the corrected abnormal fluctuation frequency threshold after the wetting parameters are adjusted, wherein...

[0024] If the frequency of the abnormal fluctuation is less than the preset threshold for the frequency of the abnormal fluctuation, then the welding process between the stainless steel pipe and the copper pipe is deemed to be up to standard.

[0025] If the frequency of abnormal fluctuations is greater than or equal to the preset threshold for abnormal fluctuations, the welding process between the stainless steel pipe and the copper pipe is deemed substandard.

[0026] Furthermore, in response to substandard welding processes between stainless steel and copper pipes after wetting parameter adjustment, the surface roughness of the welding positions of the next batch of copper pipes is increased.

[0027] Furthermore, the increase in surface roughness at the welding position of the next batch of copper tubes is positively correlated with the difference between the corrected abnormal fluctuation frequency and the preset corrected abnormal fluctuation frequency threshold.

[0028] Compared with existing technologies, the beneficial effects of this invention are as follows: By quantifying the correlation between the surface roughness of copper tubes and wetting parameters, this invention solves the problem of poor wetting caused by the difference in physical properties between stainless steel tubes and copper tubes. For example, dynamically adjusting the preheating temperature according to the surface roughness can ensure that the brazing filler metal is evenly spread at the dissimilar metal interface, eliminate incomplete fusion defects, and improve welding strength.

[0029] Furthermore, based on the abnormal fluctuation frequency classification and judgment mechanism, the root cause of welding defects can be quickly identified, avoiding the inefficiency caused by "blindly adjusting parameters" in traditional methods.

[0030] Furthermore, by capturing welding ripple images in real time using a camera and calculating the variance of the height of each peak, subjective experience-based judgments are transformed into objective data indicators. For example, the system automatically triggers parameter adjustments, shortening the response time and significantly outperforming the lag of traditional post-weld inspection. Based on the difference between the frequency of abnormal fluctuations and preset values, the system dynamically adjusts the shielding gas flow rate or preheating temperature to ensure that the welding process is always within the optimal process window.

[0031] Furthermore, when abnormal fluctuations still exist after adjusting the wetting parameters, the system further improves the surface roughness of the copper tube by increasing the sandpaper grit, thereby eliminating the influence of residual micro-oxide layer on wettability.

[0032] Furthermore, by completely eliminating the precious metal silver, the cost of brazing filler metal is reduced by more than 60%, while avoiding the toxic gases generated during silver brazing and complying with environmental regulations such as RoHS.

[0033] This invention solves the problems of poor wetting and defect location in silver-free brazing of dissimilar metals by using innovative technologies such as quantifying the correlation between surface roughness and wetting parameters, classifying and judging abnormal fluctuations, real-time ripple monitoring and dynamic parameter adjustment. It achieves efficient, low-cost, environmentally compliant and stable welding, providing an efficient, stable and low-cost solution for the manufacturing of air conditioning connecting pipes. Attached Figure Description

[0034] Figure 1 This is a flowchart of a welding method for silver-free brazing of air conditioning connecting pipes made of stainless steel pipe and copper pipe according to an embodiment of the present invention.

[0035] Figure 2 This is a flowchart illustrating how to determine whether the welding process of stainless steel pipe and copper pipe within a unit welding stroke meets the standard based on fluctuation characterization values, according to an embodiment of the present invention.

[0036] Figure 3 This is a flowchart illustrating how to determine whether the overall welding process between stainless steel pipe and copper pipe meets the standard based on the frequency of abnormal fluctuations, according to an embodiment of the present invention.

[0037] Figure 4 This is a flowchart illustrating the verification process of whether the welding process between stainless steel pipe and copper pipe meets the standard based on the corrected abnormal fluctuation frequency threshold adjusted according to the wetting parameters, as per an embodiment of the present invention.

[0038] Figure 5 This is a schematic diagram of the welding structure of the air conditioning connection pipe between the stainless steel pipe and the copper pipe without silver brazing, according to an embodiment of the present invention.

[0039] Figure 6 This is a schematic diagram of the welding ripples at the welding point in an embodiment of the present invention;

[0040] Figure 7 This is a schematic diagram of the overall structure of the air conditioning connection pipe of the present invention, which is based on the non-silver brazing of the stainless steel pipe and the copper pipe.

[0041] In the image: 1. Stainless steel pipe; 2. Copper pipe; 3. Image of welding ripples; 4. Unit welding stroke. Detailed Implementation

[0042] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0043] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0044] Please see Figure 1-6 The following are flowcharts respectively: a flowchart of a silver-free brazing method for air conditioning connecting pipes made of stainless steel and copper pipes according to an embodiment of the present invention; a flowchart of determining whether the welding process of stainless steel and copper pipes within a unit welding stroke meets the standard based on the fluctuation characterization value according to an embodiment of the present invention; a flowchart of determining whether the overall welding stroke of stainless steel and copper pipes meets the standard based on the abnormal fluctuation frequency according to an embodiment of the present invention; a flowchart of verifying whether the welding process of stainless steel and copper pipes meets the standard based on the corrected abnormal fluctuation frequency threshold after adjusting the wetting parameters according to an embodiment of the present invention; a schematic diagram of the welding structure of silver-free brazing of air conditioning connecting pipes made of stainless steel and copper pipes according to an embodiment of the present invention; and a schematic diagram of the welding ripples at the welding point according to an embodiment of the present invention.

[0045] An embodiment of the present invention discloses a silver-free brazing method for air conditioning connecting pipes based on stainless steel pipes and copper pipes, comprising:

[0046] Step S1: After removing the surface oxide layer at the welding position of the copper tube 2, obtain the surface roughness of the welding position;

[0047] Step S2: Determine the wetting parameters for brazing the stainless steel tube 1 and the copper tube 2 based on the surface roughness of the welding position. The wetting parameters include the preheating temperature and the protective gas flow rate.

[0048] Step S3: Place a camera directly above the welding point to obtain an image 3 of the welding ripples at the welding point within a unit welding stroke 4;

[0049] Step S4: Obtain the fluctuation characterization value based on the welding ripple image of the welding point;

[0050] Step S5: Based on the fluctuation characterization value, if the welding process of stainless steel pipe 1 and copper pipe 2 within the unit welding process 4 is not up to standard, complete the overall welding process and determine the frequency of abnormal fluctuations.

[0051] Step S6: Determine the reason why the overall welding process of stainless steel pipe 1 and copper pipe 2 is not up to standard based on the frequency of abnormal fluctuations, and adjust the wetting parameters for the overall welding process that is not up to standard.

[0052] Step S7: Verify whether the welding process of stainless steel pipe 1 and copper pipe 2 meets the standard according to the corrected abnormal fluctuation frequency threshold after the wetting parameters are adjusted, and compensate for the deoxidation treatment of copper pipe 2 if the welding process does not meet the standard; wherein, the overall welding process is the welding perimeter of the contact between copper pipe 2 and stainless steel pipe 1, the overall welding process is divided into 16 segments, and the unit welding process 4 is any one of the segments.

[0053] Specifically, the deoxidation process involves using 400-grit sandpaper to ensure effective removal of the oxide layer without causing excessive damage to the surface of the copper tube 2. Next, the copper tube 2 is uniformly sanded along its axial direction until the oxide layer is completely removed. During sanding, the surface condition of the copper tube 2 must be monitored in real time: avoid local thinning exceeding 20% ​​of the original wall thickness; ensure the surface roughness of the copper tube is less than or equal to 3.2 μm; and sand until the surface contact angle is less than or equal to 20°. After deoxidation, the surface is first blown away with compressed air, then residual debris is cleaned with anhydrous ethanol, and finally dried with a clean cotton cloth. This ensures that the surface cleanliness of the copper tube 2 meets ISO 8593-1 Grade B (or the cleanliness standard required by the specific welding process), providing a good foundation for subsequent welding.

[0054] Specifically, a detailed inspection of the surface of copper tube 2 is required to obtain its specific roughness value. Using specialized measuring tools, such as a surface roughness meter, the surface condition of copper tube 2 can be accurately assessed. Then, based on the obtained roughness data and in conjunction with the welding process requirements, wetting parameters are set.

[0055] Specifically, the wetting parameters include preheating temperature and protective gas flow rate. The appropriate preheating temperature is selected based on the pipe material; for example, welding is performed when copper pipe 2 is heated to a dark red color (approximately 600-700℃). The protective gas flow rate can be set to 10.0 L / min. The fluctuation characterization value is the variance of the height of each peak in the welding ripples.

[0056] Specifically, the welding machine is set in a fixed position, and the stainless steel pipe 1 and the copper pipe 2 are vertically connected. The outer diameter of the contact surface between the stainless steel pipe 1 and the copper pipe 2 is rotated and welded around the brazing material of the welding machine. The brazing material can be BNi-2 or BNi-5, and there is no specific limitation. It is only necessary to meet the requirement that the air conditioning connection pipe between the stainless steel pipe 1 and the copper pipe 2 has a silver-free brazing result.

[0057] Specifically, a camera, such as an infrared camera, is placed directly above the welding point. There are no specific limitations, as long as it can output the corresponding image result based on the recorded image of the welding point.

[0058] Specifically, based on the fluctuation characterization value, it is determined whether the welding process between the stainless steel pipe 1 and the copper pipe 2 within a unit welding stroke 4 meets the standard, wherein,

[0059] If the fluctuation characterization value is less than the preset fluctuation characterization value threshold, then the welding process of stainless steel pipe 1 and copper pipe 2 within the unit welding process 4 is deemed to be up to standard.

[0060] If the fluctuation characterization value is greater than or equal to the preset fluctuation characterization threshold, it is determined that the welding process of stainless steel pipe 1 and copper pipe 2 within the unit welding process 4 is substandard. The preset fluctuation characterization value threshold is set to 2.1. It should be noted that the data in this embodiment are all results obtained through preliminary experimental verification of the system described in this invention before the system was run. Each preset value can be adjusted according to the specific usage, as long as the system method described in this invention can clearly define different specific situations in the single judgment process through the obtained values.

[0061] Specifically, the result of the welding process of stainless steel pipe 1 and copper pipe 2 within a unit welding process 4 being deemed substandard is recorded as an abnormal fluctuation, and the number of abnormal fluctuations in the welding process of stainless steel pipe 1 and copper pipe 2 within the overall welding process is recorded as the abnormal fluctuation frequency.

[0062] Specifically, the overall welding process between the stainless steel pipe 1 and the copper pipe 2 is determined based on the frequency of the abnormal fluctuations, wherein...

[0063] If the frequency of the abnormal fluctuation is less than the first preset abnormal fluctuation frequency threshold, then the overall welding process of the stainless steel pipe 1 and the copper pipe 2 is determined to be up to standard.

[0064] If the abnormal fluctuation frequency is greater than or equal to the first preset abnormal fluctuation frequency threshold and less than the second preset abnormal fluctuation frequency threshold, then it is determined that the overall welding process of the stainless steel pipe 1 and the copper pipe 2 is substandard, and the reason for the substandard overall welding process is that the protective gas flow rate in the wetting parameters is too high.

[0065] If the frequency of abnormal fluctuations is greater than or equal to the second preset abnormal fluctuation frequency threshold, it is determined that the overall welding process of the stainless steel pipe 1 and the copper pipe 2 is substandard, and the reason for the substandard overall welding process is that the preheating temperature in the wetting parameters is low; wherein the first preset abnormal fluctuation frequency threshold is 5 times, and the second preset abnormal fluctuation frequency threshold is 10 times.

[0066] Specifically, in response to the overall welding process failing to meet standards due to excessive shielding gas flow rate in the wetting parameters, the shielding gas flow rate for the next batch of connecting pipe welding is reduced, and the reduction in shielding gas flow rate is positively correlated with the difference between the abnormal fluctuation frequency and the first preset abnormal fluctuation frequency threshold. It is understood that the positive correlation can be linear or nonlinear, and is not specifically limited. The slope of the linear positive correlation is also not specifically limited and can be set according to the actual preparation conditions, as long as the difference between the abnormal fluctuation frequency and the first preset abnormal fluctuation frequency threshold is larger, the reduction in shielding gas flow rate is greater. For example, if the reduction in shielding gas flow rate is set to ΔQ, and the difference between the abnormal fluctuation frequency and the first preset abnormal fluctuation frequency threshold is set to ΔΦ, then ΔQ = α × (ΔΦ + Φ0), where α is the flow rate adjustment coefficient, set to 1.03, and Φ0 is a constant.

[0067] Specifically, in response to the overall welding process failing to meet standards due to low preheating temperature in the wetting parameters, the preheating temperature for the next batch of connecting pipes is increased, and the adjustment range of the preheating temperature is positively correlated with the difference between the abnormal fluctuation frequency and the second preset abnormal fluctuation frequency threshold. It is understood that the positive correlation can be linear or nonlinear, and is not specifically limited. The slope of the linear positive correlation is also not specifically limited and can be set according to the actual preparation conditions, as long as the difference between the abnormal fluctuation frequency and the second preset abnormal fluctuation frequency threshold is larger, the increase in preheating temperature is greater. For example, if the increase in preheating temperature is set to ΔT, and the difference between the abnormal fluctuation frequency and the second preset abnormal fluctuation frequency threshold is set to Δλ, then ΔT = β × (Δλ + λ0), where β is the temperature adjustment coefficient, set to 0.86, and λ0 is a constant.

[0068] Specifically, the welding process between stainless steel pipe 1 and copper pipe 2 is verified to meet the standard based on the corrected abnormal fluctuation frequency threshold after adjusting the wetting parameters.

[0069] If the frequency of the abnormal fluctuation is less than the preset threshold for the frequency of the abnormal fluctuation, then the welding process between the stainless steel pipe 1 and the copper pipe 2 is deemed to be up to standard.

[0070] If the frequency of corrected abnormal fluctuations is greater than or equal to a preset threshold for corrected abnormal fluctuations, the welding process between the stainless steel pipe 1 and the copper pipe 2 is deemed substandard. The preset threshold for corrected abnormal fluctuations is set to 3 times. It should be noted that this threshold is an optimized value derived from statistical analysis of previous experimental data and effectively reflects the stability of the welding process. If the frequency of corrected abnormal fluctuations is lower than this threshold, it indicates that the current welding process parameters have reached an ideal state, and subsequent welding operations can continue. In practical applications, operators can fine-tune the threshold according to specific working conditions to obtain the best welding results.

[0071] Specifically, in response to substandard welding processes of stainless steel pipe 1 and copper pipe 2 after adjusting wetting parameters, the surface roughness of the welding position of the next batch of copper pipe 2 is increased. The method for increasing the surface roughness of the welding position of the copper pipe 2 in cases where the welding process of stainless steel pipe 1 and copper pipe 2 is deemed substandard is to reduce the grit of the sandpaper used for deoxidation. It is worth noting that while low-grit sandpaper can quickly remove the oxide layer, it easily leaves small pits or uneven areas, thus affecting wetting performance. Therefore, in practice, it is recommended to verify the treatment effects of different grits through experiments and establish standardized reference data to achieve the best balance between efficiency and cost while ensuring welding quality.

[0072] Specifically, the increase in surface roughness at the welding position of the next batch of copper tubes 2 is positively correlated with the difference between the corrected abnormal fluctuation frequency and the preset corrected abnormal fluctuation frequency threshold. It is understood that the positive correlation can be linear or nonlinear, and is not specifically limited. The slope of the linear positive correlation is also not specifically limited and can be set according to the actual preparation conditions. The only requirement is that the larger the difference between the corrected abnormal fluctuation frequency and the preset corrected abnormal fluctuation frequency threshold, the greater the reduction in the grit size of the replaced sandpaper. For example, if the reduction in the grit size of the replaced sandpaper is set to ΔM, and the difference between the abnormal fluctuation frequency and the second preset abnormal fluctuation frequency threshold is set to Δμ, then ΔM = γ × (Δμ + μ0), where γ is the grit adjustment coefficient, set to 1.06, and μ0 is a constant.

[0073] Specifically, such as Figure 7 This is a schematic diagram of the overall structure of the silver-free brazing of the stainless steel pipe and copper pipe in an air conditioning connection pipe according to an embodiment of the present invention. The diagram clearly shows the connection between the stainless steel pipe 1 and the copper pipe 2 formed by silver-free brazing. The end of the stainless steel pipe 1 fits tightly with the outer wall of the copper pipe 2. The brazing filler metal layer at the welding point is evenly filled in the gap between the two pipes, and the welding ripples are regularly distributed in a ring shape, without obvious bubbles, cracks, or incomplete fusion defects. The connection structure formed by the above welding method can achieve a high-strength, high-sealing connection between the stainless steel pipe and the copper pipe without using silver-based brazing filler metal. This effectively reduces production costs while meeting the corrosion resistance and mechanical performance requirements of the air conditioning connection pipe during long-term use.

[0074] This invention solves the problems of poor wetting and defect location in silver-free brazing of dissimilar metals by using innovative technologies such as quantifying the correlation between surface roughness and wetting parameters, classifying and judging abnormal fluctuations, real-time ripple monitoring and dynamic parameter adjustment. It achieves efficient, low-cost, environmentally compliant and stable welding, providing an efficient, stable and low-cost solution for the manufacturing of air conditioning connecting pipes.

[0075] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A welding method for air conditioning connecting pipes based on stainless steel pipes and copper pipes without silver brazing, characterized in that, include: Step S1: After removing the surface oxide layer at the copper tube welding location, obtain the surface roughness of the welding location; Step S2: Determine the wetting parameters for brazing the stainless steel pipe and the copper pipe based on the surface roughness of the welding position. The wetting parameters include the preheating temperature and the protective gas flow rate. Step S3: Place a camera directly above the welding point to obtain an image of the welding ripples within a unit welding stroke; Step S4: Obtain the fluctuation characterization value based on the welding ripple image of the welding point; Step S5: Based on the fluctuation characterization value, if the welding process of stainless steel pipe and copper pipe within a unit welding process is not up to standard, complete the overall welding process and determine the frequency of abnormal fluctuations. Step S6: Determine the reasons for the substandard overall welding process of the stainless steel pipe and copper pipe based on the frequency of abnormal fluctuations, and adjust the wetting parameters of the overall welding process. Step S7: Verify whether the welding process of stainless steel pipe and copper pipe meets the standard according to the corrected abnormal fluctuation frequency threshold after adjusting the wetting parameters, and compensate for the deoxidation treatment of copper pipes that do not meet the welding process. The fluctuation characterization value is the variance of the height of each peak in the welding ripple; Based on the fluctuation characterization value, it is determined whether the welding process of stainless steel pipe and copper pipe within a unit welding stroke meets the standard, wherein, If the fluctuation characterization value is less than the preset fluctuation characterization value threshold, then the welding process of stainless steel pipe and copper pipe within the unit welding stroke is deemed to meet the standard. If the fluctuation characterization value is greater than or equal to the preset fluctuation characterization value threshold, it is determined that the welding process of stainless steel pipe and copper pipe within the unit welding stroke is substandard. The result of the stainless steel pipe and copper pipe welding process failing to meet the standard within a unit welding process is recorded as an abnormal fluctuation, and the number of abnormal fluctuations in the stainless steel pipe and copper pipe welding process within the whole welding process is recorded as the abnormal fluctuation frequency. The overall welding process between the stainless steel pipe and the copper pipe is determined based on the frequency of the abnormal fluctuations. If the frequency of the abnormal fluctuation is less than the first preset abnormal fluctuation frequency threshold, then the overall welding process of the stainless steel pipe and the copper pipe is determined to be up to standard. If the frequency of abnormal fluctuations is greater than or equal to the first preset abnormal fluctuation frequency threshold and less than the second preset abnormal fluctuation frequency threshold, then it is determined that the overall welding process of the stainless steel pipe and the copper pipe is substandard, and the reason for the substandard overall welding process is that the protective gas flow rate in the wetting parameters is too high. If the frequency of abnormal fluctuations is greater than or equal to the second preset threshold for abnormal fluctuations, it is determined that the overall welding process of the stainless steel pipe and the copper pipe is substandard, and the reason for the substandard overall welding process is that the preheating temperature in the wetting parameters is low.

2. The welding method for silver-free brazing of air conditioning connecting pipes based on stainless steel pipes and copper pipes according to claim 1, characterized in that, In response to the overall welding process failing to meet the standard due to a large shielding gas flow rate in the wetting parameters, the shielding gas flow rate for the next batch of connecting pipe welding is reduced, and the reduction in shielding gas flow rate is positively correlated with the difference between the abnormal fluctuation frequency and the first preset abnormal fluctuation frequency threshold.

3. The welding method for silver-free brazing of air conditioning connecting pipes based on stainless steel pipes and copper pipes according to claim 2, characterized in that, In response to the overall welding process failing to meet the standard due to low preheating temperature in the wetting parameters, the preheating temperature for the next batch of connecting pipe welding is increased, and the adjustment range of the preheating temperature is positively correlated with the difference between the abnormal fluctuation frequency and the second preset abnormal fluctuation frequency threshold.

4. The welding method for silver-free brazing of air conditioning connecting pipes based on stainless steel pipes and copper pipes according to claim 3, characterized in that, The welding process between the stainless steel pipe and the copper pipe is verified to meet the standard based on the corrected abnormal fluctuation frequency threshold after adjusting the wetting parameters. If the frequency of the abnormal fluctuation is less than the preset threshold for the frequency of the abnormal fluctuation, then the welding process between the stainless steel pipe and the copper pipe is deemed to be up to standard. If the frequency of abnormal fluctuations is greater than or equal to the preset threshold for abnormal fluctuations, the welding process between the stainless steel pipe and the copper pipe is deemed substandard.

5. The welding method for silver-free brazing of air conditioning connecting pipes based on stainless steel pipes and copper pipes according to claim 4, characterized in that, In response to substandard welding processes between stainless steel and copper pipes after wetting parameter adjustment, the surface roughness of the welding positions of the next batch of copper pipes is increased.

6. The welding method for silver-free brazing of air conditioning connecting pipes based on stainless steel pipes and copper pipes according to claim 5, characterized in that, The increase in surface roughness at the welding position of the next batch of copper tubes is positively correlated with the difference between the corrected abnormal fluctuation frequency and the preset corrected abnormal fluctuation frequency threshold.

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