Welding process for reinforcing double-mainboard micro-channel radiating pipe and automobile radiator

Abstract

The invention discloses a welding process for reinforcing a double-mainboard micro-channel radiating pipe and an automobile radiator, and relates to the technical field of welding. According to the welding process, firstly, the range of welding parameters is adjusted, and under the conditions that the assembling gap between a main board and a radiating pipe is 0.15-0.17 mm and the thickness of an aluminum-silicon brazing filler metal coating is 80-94 microns, the brazing temperature is controlled to be 606-618 DEG C, the preheating time is controlled to be 5-7 min, and the cooling speed after welding is controlled to be 4-6 DEG C / s; secondly, a brazing filler metal coating online detection system is arranged, chemical components of a brazing filler metal coating of the radiating pipe are detected online before the radiating pipe is assembled to the mainboard, and the brazing filler metal coating online detection system is in data communication with a brazing control system; and the brazing control system receives a detection result of the brazing filler metal coating online detection system and dynamically optimizes welding parameters according to the detection result after the radiating pipe assembled with the mainboard enters a brazing furnace. By the adoption of the scheme, the welding qualification rate is 99% or above.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular to a welding process for strengthening dual-mainboard micro-channel heat dissipation pipes and an automobile radiator. Background Art

[0002] Dual-core microchannel heat pipes are a common heat pipe design used in automotive radiators. These heat pipes are connected to independent cores at both ends, forming a bidirectional, reinforced support structure. Previously, dual-core microchannel heat pipes typically had cores between 3 and 3.5 mm thick, and existing brazing parameters maintained a soldering pass rate exceeding 98%. However, with the development of reinforced dual-core microchannel heat pipes with cores thicker than 4 mm, despite maintaining the same structural and dimensional characteristics, the soldering failure rate exceeded 12% during mass production using existing brazing parameters. This issue stems from two factors: Firstly, while the reinforced dual-core microchannel heat pipes only increase core thickness, the heat capacity significantly changes, increasing the difference between the cores and the heat pipe ends. This leads to more severe problems with cold or poor solder joints. Secondly, while the coating workshop currently uses aluminum-silicon brazing filler metal that meets technical requirements, frequent changes in supplier and brand occur during production. This, combined with the inherent influence of the coating process, results in variations in the actual soldering properties, which in turn impacts the quality of subsequent brazing operations. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides a welding process for strengthening dual-mainboard micro-channel heat dissipation pipes and an automobile radiator.

[0004] The technical solutions of the present invention are as follows:

[0005] A welding process for strengthening micro-channel heat dissipation pipes of dual mainboards, wherein the mainboard thickness is 4 to 5 mm, comprises:

[0006] (1) Welding parameter range adjustment

[0007] Under the conditions of a 0.15-0.17mm gap between the mainboard and the heat pipe assembly and an aluminum-silicon brazing filler metal coating thickness of 80-94μm, the brazing temperature is controlled within the range of 606-618℃, the preheating time is controlled within the range of 5-7min, and the cooling rate after welding is controlled within the range of 4-6℃ / s;

[0008] (2) Dynamic optimization of welding parameters

[0009] An online detection system for the solder coating is provided to perform online detection of the chemical composition of the solder coating of the heat pipe before the heat pipe is assembled to the mainboard. The online detection system for the solder coating communicates data with a brazing control system. The brazing control system receives the detection results of the online detection system for the solder coating and dynamically optimizes the welding parameters within the range defined in step (1) based on the detection results after the heat pipe assembled with the mainboard enters the brazing furnace.

[0010] As described above, a welding process for strengthening the dual-mainboard micro-channel heat dissipation pipes, the mainboard thickness is 4.5 mm.

[0011] In the welding process for strengthening the dual-mainboard micro-channel heat dissipation pipe as described above, the assembly gap between the mainboard and the heat dissipation pipe is 0.16 mm, and the thickness of the aluminum-silicon solder coating is 84-88 μm.

[0012] In the above-mentioned enhanced dual-motherboard microchannel heat dissipation tube welding process, the solder coating online detection system is a LIBS system.

[0013] In the aforementioned welding process for strengthening the dual-mainboard microchannel heat pipe, the brazing control system dynamically optimizes the welding parameters according to the detection results by comparing the detection results with a preset silicon content threshold, magnesium content threshold and / or silicon-magnesium ratio threshold, and dynamically optimizes the welding parameters based on the comparison results.

[0014] In the aforementioned welding process for strengthening the dual-mainboard micro-channel heat dissipation pipe, the dynamic optimization of the welding parameters is single-parameter optimization or multi-parameter simultaneous optimization.

[0015] The soldering process for strengthening the dual-motherboard micro-channel heat dissipation tubes as described above is optimized including the soldering temperature and / or the preheating time.

[0016] In the aforementioned enhanced dual-mainboard micro-channel heat dissipation pipe welding process, the solder coating online detection system is arranged on one side of the heat dissipation pipe conveying line in the assembly process.

[0017] In the above-mentioned welding process for strengthening the dual-motherboard micro-channel heat dissipation tube, the detection mode of the solder coating online detection system is online interval detection, and the number of workpieces separated by each two adjacent detection actions is the same.

[0018] The present invention also provides an automobile radiator having a reinforced dual-mainboard microchannel heat dissipation pipe, the mainboard thickness of which is 4 to 5 mm. The reinforced dual-mainboard microchannel heat dissipation pipe is welded using the welding process described above, and the welding qualification rate is not less than 99%.

[0019] The beneficial effects of the present invention are:

[0020] The disclosed welding process for the reinforced dual-mainboard micro-channel heat pipe is adaptively optimized and verified based on the variation in mainboard thickness, from the assembly gap between the mainboard and the heat pipe, the thickness of the aluminum-silicon brazing filler metal coating, to the brazing temperature, preheating time, and post-weld cooling rate, thereby reducing the resulting problems of false welds or cold welds. Simultaneously, the welding parameters are dynamically optimized based on the online detection results of the brazing filler metal coating, further eliminating the adverse effects of the brazing quality of subsequent processes due to factors such as the batch size of the brazing filler metal and the coating process itself. Through the implementation of the above multiple measures, the welding qualification rate of the reinforced dual-mainboard micro-channel heat pipe produced has reached over 99%. DETAILED DESCRIPTION

[0021] Comparative Example 1

[0022] The process parameters for welding the dual motherboard microchannel heat pipes before adjustment are as follows:

[0023]

[0024]

[0025] The above welding process parameters were used to weld the reinforced dual-motherboard microchannel heat pipes with a motherboard thickness of 4.5mm. The fine-tuning of the brazing temperature and preheating time by each shift did not exceed the ranges in the above table. The defective rate calculated by shift (only shifts with ≥500 units were selected) was above 7% in all cases, with the highest exceeding 12%.

[0026] Example 1

[0027] For a motherboard with a thickness of 4.5mm, the following assembly gaps and welding process parameters are adjusted:

[0028] parameter Control range Assembly gap between mainboard and heat pipe 0.16mm Aluminum-silicon brazing filler metal (10% Si) coating thickness 86μm Brazing temperature [606℃，618℃] Warm-up time [5min, 7min] Cooling rate 5℃ / s

[0029] The adjusted welding process parameters were used to weld the reinforced dual-motherboard microchannel heat pipes with a motherboard thickness of 4.5 mm. The fine-tuning of the brazing temperature and preheating time in each shift did not exceed the range in the above table. The statistical method for the defective rate was the same. The defective rate of shifts with stable quality could be controlled below 1%, and the defective rate of some shifts was between 1 and 2.6%.

[0030] The heat dissipation pipes and mainboards in the above comparative examples and embodiments are both made of 3003 aluminum alloy.

[0031] Example 2

[0032] According to production feedback over a certain period, the instability of the brazing pass rate may be related to changes in the aluminum-silicon solder manufacturer / brand and the coating process in the coating workshop. For example, although the commonly used ER4015 and B-Al89SiMg only differ in the content of components other than Al and Si (mainly Mg), they can already cause changes in the solder welding performance under the same brazing process, thereby affecting the brazing quality. Even if it is the same ER4015, the Mg content has a floating design. During production, it is impossible to accurately feedback the material or process changes in the coating workshop to the brazing workshop at any time. Therefore, the present invention introduces an online detection system for the solder coating to perform online detection of the chemical composition of the heat pipe's solder coating before the heat pipe is assembled to the motherboard. Since the assembly process is the last process before entering the furnace for brazing, the system is installed on the heat pipe conveyor line side of the assembly process.

[0033] The online detection system for solder coating introduced in the present invention is a LIBS system, which uses laser-induced breakdown spectroscopy to perform non-contact detection of solder coating. It has high detection accuracy and fast detection speed. The pulsed laser can locally vaporize the solder coating. The plasma emission spectrum is analyzed by a spectrometer. The intensity of the characteristic spectral line reflects the element content. Therefore, changes in the solder raw material can be identified by identifying the silicon content and magnesium content in the aluminum-silicon solder or calculating the silicon-magnesium ratio.

[0034] Because the assembly and brazing processes are collinear, the LIBS system communicates data with the brazing control system. The brazing control system receives the LIBS system's detection results and, based on these results, dynamically optimizes the welding parameters within the process-defined range after the heat pipes, assembled with the motherboard, enter the brazing furnace. The optimized parameters primarily focus on the brazing temperature and preheating time, and either a single parameter or multiple parameters can be optimized simultaneously.

[0035] The following is explained in conjunction with a specific example. The welding process parameters adjusted in Example 1 are used to organize production. The LIBS system performs real-time online detection of the chemical composition of the solder coating of the heat pipe. The detection value M of the silicon-magnesium ratio is obtained based on the detection results. The brazing control system stores the more optimal brazing process parameters (brazing temperature, preheating time) corresponding to different intervals of the detection value M determined in advance through control experiments. When the detection value M is detected to change across intervals during production, the corresponding brazing process parameters are also optimized synchronously. Since the present invention stipulates a Si content of 10% for the solder, the adjustment rule is that when the silicon-magnesium ratio value decreases to exceed the set interval threshold, it means that the Mg content increases. The adjusted brazing temperature and preheating time are more conducive to the solder obtaining heat. Otherwise, the heat obtained by the solder is reduced.

[0036] It can be seen that although the silicon-magnesium ratio parameter obtained by the LIBS system in the present invention is much more accurate than simply comparing the silicon and magnesium contents, it is only necessary to determine the correspondence between the range of the test value M and one or more commonly used solders through control experiments in advance. It is not necessary to conduct control experiments on all similar solders from all manufacturers / brands that may be used in production to determine the relationship with the test value M. Because the silicon-magnesium ratio parameter itself reflects the variation pattern of the solder properties, when the test value M is detected to vary significantly across a range during production, it is not necessary to specifically deduce which solder has changed. The optimized brazing parameters can be obtained based on the variation pattern of the test value M. For example, in production, the fluctuation range of the test value M corresponding to ER4015 with 1.5% Mg is used as the benchmark, recorded as the first standard range. The corresponding brazing parameters are taken as the floating range of the reference value median (612°C, 6 minutes), recorded as the first parameter range. Second and third standard ranges are set based on the proportion of the test value M exceeding the threshold of the first standard range. The corresponding brazing temperature and preheating time are also set with second and third parameter ranges.

[0037] In this embodiment, the LIBS system is used to detect the brazing coating using online interval detection. The number of workpieces between each two adjacent detection actions is the same. In production, this number is 3. When the detection value M is first recognized to change across the interval, the heat pipe conveyor line is paused but not retracted. The LIBS system's reciprocating motion is used to re-inspect the three workpieces between the two adjacent detection actions. The brazing control system automatically intercepts the number of workpieces entering the brazing furnace based on the LIBS system's detection results and data from the counter to avoid competition in welding parameters among workpieces in the same furnace.

[0038] Finally, by using the adjusted welding process parameters in Example 1 in combination with the LIBS dynamic detection and optimization method in Example 2, the welding production qualification rate of the reinforced dual-motherboard microchannel heat dissipation pipe with a motherboard thickness of 4.5 mm was stabilized at above 99%.

[0039] In summary, the welding process for the enhanced dual-mainboard micro-channel heat pipe disclosed in the present invention is adaptively optimized and verified based on the change in mainboard thickness, from the assembly gap between the mainboard and the heat pipe, the thickness of the aluminum-silicon brazing filler metal coating to the brazing temperature, preheating time, and post-weld cooling rate, thereby reducing the problems of false solder joints or cold solder joints caused by these factors. At the same time, the welding parameters are dynamically optimized based on the online detection results of the brazing filler metal coating, further eliminating the adverse effects of the brazing quality of subsequent processes due to factors such as the batch size of the brazing filler metal raw materials and the coating process itself. Through the implementation of the above multiple measures, the welding qualification rate of the produced enhanced dual-mainboard micro-channel heat pipes has reached more than 99%.

[0040] The solution of the present invention was also used to organize the welding production verification of reinforced dual-mainboard micro-channel heat dissipation pipes with a mainboard thickness of 4.0 mm or 5.0 mm, and satisfactory results were also achieved.

[0041] The above are only preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the claims.

Claims

1. A welding process for strengthening dual-mainboard micro-channel heat pipes, wherein the mainboard thickness is 4-5 mm, characterized in that: include: (1) Welding parameter range adjustment Under the conditions of a 0.15-0.17mm gap between the mainboard and the heat pipe assembly and an aluminum-silicon brazing filler metal coating thickness of 80-94μm, the brazing temperature is controlled within the range of 606-618℃, the preheating time is controlled within the range of 5-7min, and the cooling rate after welding is controlled within the range of 4-6℃ / s; (2) Dynamic optimization of welding parameters An online detection system for the solder coating is provided to perform online detection of the chemical composition of the solder coating of the heat pipe before the heat pipe is assembled to the mainboard. The online detection system for the solder coating communicates data with a brazing control system. The brazing control system receives the detection results of the online detection system for the solder coating and dynamically optimizes the welding parameters within the range defined in step (1) based on the detection results after the heat pipe assembled with the mainboard enters the brazing furnace.

2. A welding process for strengthening dual-mainboard microchannel heat dissipation pipes according to claim 1, characterized in that: The thickness of the main board is 4.5 mm.

3. The welding process for strengthening the dual-mainboard microchannel heat dissipation pipe according to claim 1, characterized in that: The assembly gap between the mainboard and the heat dissipation pipe is 0.16 mm, and the thickness of the aluminum-silicon solder coating is 84-88 μm.

4. The welding process for strengthening the dual-mainboard microchannel heat dissipation pipe according to claim 1, characterized in that: The solder coating online detection system is a LIBS system.

5. The welding process for strengthening the dual-mainboard micro-channel heat dissipation pipe according to claim 1, characterized in that: The brazing control system dynamically optimizes the welding parameters according to the detection results by comparing the detection results with a preset silicon content threshold, magnesium content threshold and / or silicon-magnesium ratio threshold, and dynamically optimizes the welding parameters based on the comparison results.

6. A welding process for strengthening dual-mainboard micro-channel heat dissipation pipes according to claim 5, characterized in that: The dynamic optimization of welding parameters is single parameter optimization or multi-parameter synchronous optimization.

7. A welding process for strengthening dual-mainboard microchannel heat dissipation pipes according to claim 6, characterized in that: Optimization may include brazing temperature and / or preheating time.

8. The welding process for strengthening dual-mainboard microchannel heat dissipation pipes according to claim 1, characterized in that: The solder coating online detection system is arranged on one side of the heat dissipation pipe conveying line in the assembly process.

9. A welding process for strengthening dual-mainboard micro-channel heat dissipation pipes according to claim 8, characterized in that: The detection mode of the solder coating online detection system is online interval detection, and the number of workpieces spaced between each two adjacent detection actions is the same.

10. An automobile radiator having a reinforced dual-mainboard microchannel heat pipe, the mainboard thickness of which is 4 to 5 mm, characterized in that: The reinforced dual-mainboard micro-channel heat dissipation pipe is welded by using the welding process described in any one of claims 1 to 9, and the welding qualification rate is not less than 99%.

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