Segmented temperature control and welding flux vision cooperative control method for high-frequency welding side cold plate

Abstract

The invention relates to the technical field of high-frequency welding, and provides a segmented temperature control and welding flux visual cooperative control method for a high-frequency welding side cold plate, which comprises the following steps of: adopting multi-stage temperature field cooperative optimization, designing a five-stage temperature control curve, quickly heating to 320 DEG C at normal temperature, eliminating the initial temperature difference of a substrate, preserving heat for 5 seconds to reduce the temperature difference by 70%, and balancing the temperature field. Then accurately heating to 600 DEG C at 5.3 DEG C / s, triggering a 4047 aluminum welding eutectic reaction, then cooling to 590 DEG C and preserving heat for 5 seconds to provide a stable temperature field for AOI visual judgment and heat compensation, and finally performing camera shooting to judge the diameter shrinkage rate and the edge ambiguity of the welding wire through AOI intelligent analysis, so that heat compensation is performed according to a judgment result, and thus, the pre-judgment of the melting state of the welding flux is realized. And through the coordination of segmented temperature control and visual real-time feedback of the solder form, the problems of non-uniform solder melting and overburning caused by insufficient temperature uniformity are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-frequency welding, and particularly relates to a method for segmented temperature control and solder vision collaborative control of a high-frequency welded side cold plate. Background Art

[0002] For the cooling plate of new energy batteries, high-frequency welding is usually used. The flux-cored wire is melted at high temperature to weld the corrugated pipe cooling plate (aluminum part) and the current collector together. On the one hand, the flux-cored wire improves the fluidity of the molten slag, reduces slag splashing, and enhances welding stability, thus optimizing the welding process performance. On the other hand, it can improve the high-temperature oxidation resistance and corrosion resistance of the high-deposit metal, making the weld have excellent resistance to hot cracks and low-temperature toughness. Among them, the side cold plate needs to weld the 3003 aluminum alloy corrugated pipe and the current collector together with 4047 aluminum solder. At present, a simple vision control scheme is adopted in the welding process, relying only on the camera to capture the solder state. However, the temperature distribution in the welding area is uneven, such as fast heat dissipation at the edge and overheating in the center, resulting in local overburning or incomplete internal melting of the 4047 aluminum solder. The deviation between the visual judgment result and the actual melting state is significant. Some studies have shown that through the combined detection of infrared thermal imaging and machine vision, the misjudgment rate of the traditional vision system reaches 23% when the temperature difference > 15°C. Lack of temperature collaborative regulation ability: The pure vision closed-loop control does not integrate temperature data and cannot actively optimize the temperature field distribution by dynamically adjusting the heating parameters, easily causing periodic overburning or insufficient welding problems. The traditional temperature control scheme uses an infrared temperature sensor to identify the temperature. Limited by the surface reflectivity of the workpiece, the error of different workpieces is about 20°C, which is difficult to adjust and easily causes problems such as overburning and non-melting of the welding wire. A single control mode, only temperature or only vision, cannot synchronously achieve temperature field optimization and accurate determination of the solder state, resulting in periodic quality defects, such as a non-melting rate of the welding wire reaching 40% or an internal non-melting rate of 10%. Therefore, it is very important to solve the above problems. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to propose a method for segmented temperature control and solder vision collaborative control of a high-frequency welded side cold plate, which solves the problems in the background art.

[0004] Based on the above purpose, the present invention provides a method for segmented temperature control and solder vision collaborative control of a high-frequency welded side cold plate, including the following steps: Step 1: Heat up from room temperature to 320°C at a rate of 10°C / s to eliminate the initial temperature difference of the substrate; Step 2: Heat up from 320°C to 490°C at a rate of 10°C / s to balance the temperature field; Step 3: Heat up from 490°C to 600°C at a rate of 5.3°C / s to trigger the eutectic reaction of the solder; Step 4: Cool down to 590°C to provide a stable temperature field for subsequent vision judgment; Step 5: Trigger the camera to take pictures, and perform heat preservation or heat supplement operations according to the AOI vision determination result.

[0005] Preferably, in Step 2, after heating up to 490°C, keep it warm for 5 seconds; in Step 4, after cooling down to 490°C, keep it warm for 5 seconds.

[0006] Preferably, in Step 5, use an HDR industrial camera to collect the solder morphology image, and compare and identify the welding state with the database established by AOI semi-supervised learning.

[0007] Preferably, the determination conditions in Step 5 are: the shrinkage rate of the wire diameter ≤ 15% of the initial value, and the edge blur degree ≤ 5% of the initial value; If the determination passes, after performing heat supplement for the preset heat supplement duration of 2S, stop heating and end the welding; If the determination fails, start heat supplement with a constant power of 65%, and perform visual determination in a loop until the solder wire is completely melted.

[0008] Preferably, for heating up, a double helix high-frequency induction heating coil is used, with the power density uniformity of ±5%, and it can be dynamically adjusted within 0 - 50kW.

[0009] Preferably, during the whole process, an infrared thermal imager is used to monitor the temperature field distribution in real time. The wavelength of the infrared thermal imager is 7.5 - 14μm, the accuracy is ±2°C, and the frame rate is 50Hz.

[0010] Preferably, the frame rate of the HDR industrial camera is 200fps, the resolution is 1280×1024, and it has a global shutter, which is used for high-precision acquisition of the solder morphology.

[0011] Preferably, it further includes an adaptive control strategy: when there is no feedback from the HDR industrial camera and the infrared thermal imager, it is default to end the welding after keeping it warm for 2 seconds.

[0012] Advantages of the present invention: By adopting multi-stage temperature field collaborative optimization, designing a five-stage temperature control curve, first quickly heating from room temperature to 320°C to eliminate the initial temperature difference of the substrate, then keeping it warm for 5 seconds to reduce the temperature difference by 70% and balance the temperature field, then precisely heating to 600°C at a rate of 5.3°C / s to trigger the 4047 aluminum solder eutectic reaction, then cooling down to 590°C and keeping it warm for 5 seconds to provide a stable temperature field for visual determination, and finally taking pictures with the camera to determine the shrinkage rate of the wire diameter and the edge blur degree through AOI intelligent analysis, and then performing heat supplement according to the determination result, thus realizing the prediction of the solder melting state, ensuring the complete melting of the solder wire, and solving the problems of uneven solder melting and overburn caused by insufficient temperature uniformity through the collaboration of segmented temperature control and real-time visual feedback of the solder morphology. Specific embodiments

[0013] To make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below with reference to specific embodiments.

[0014] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those with ordinary skills in the field to which the present invention belongs. The "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. The terms such as "comprising" or "including" mean that the elements or objects appearing before this term cover the elements or objects listed after this term and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left" and "right" are only used to represent relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0015] This embodiment provides a method for coordinated control of segmented temperature control and solder vision of a high-frequency welded side cold plate, including the following steps: Based on the Fourier heat conduction equation and the thermal diffusion time constant τ≈8s, a five-stage temperature control curve is designed: S1, heating from room temperature to 320°C at a rate of 10°C / s to eliminate the initial temperature difference of the substrate; S2, heating from 320°C to 490°C at a rate of 10°C / s and holding for 5 seconds to balance the temperature field. Calculations using the Fourier heat conduction equation show that a 5-second hold can reduce the temperature difference by 70%; S3, heating from 490°C to 600°C at a rate of 5.3°C / s to trigger the solder eutectic reaction. The eutectic temperature of 4047 aluminum is 580°C; S4, cooling to 590°C and holding for 5 seconds to provide a stable temperature field for subsequent vision determination. The temperature upper limit is 590°C, with a safety margin of 67°C reserved; S5, triggering the camera to take pictures, collecting solder morphology images through an HDR industrial camera, and performing AOI intelligent analysis. The exposure time of the HDR industrial camera is 1ms, the dynamic range is 60dB, the frame rate is 200fps, the resolution is 1280×1024, and it has a global shutter; The HDR industrial camera determines the shrinkage rate of the wire diameter and the edge blur degree through AOI intelligent analysis: when the shrinkage rate of the wire diameter ≤ 15% of the initial value and the edge blur degree ≤ 5% of the initial value, after preheating for 2 seconds according to the preset preheating duration, stop heating and end the welding; when the above conditions are not met, start reheating with a constant power of 65% and loop through the visual determination until the wire is completely melted; when there is no feedback from the HDR industrial camera and the infrared thermal imager, it is defaulted to end the welding after 2 seconds of heat preservation.

[0016] The heating for temperature rise uses a double - helix high - frequency induction heating coil with a power density uniformity of ±5% and can be dynamically adjusted within 0 - 50 kW. The entire process uses an infrared thermal imager to monitor the temperature field distribution in real - time. The wavelength of the infrared thermal imager is 7.5 - 14 μm, the accuracy is ±2°C, and the frame rate is 50 Hz.

[0017] By adopting multi - stage temperature field collaborative optimization, designing a five - stage temperature control curve, and using the HDR industrial camera to take AOI visual determination of the shrinkage rate of the wire diameter and the edge blur degree, and then performing reheating according to the determination results, thus realizing the prediction of the solder melting state, ensuring that the wire is completely melted, and solving the problems of uneven solder melting and over - burning caused by insufficient temperature uniformity through the collaboration of segmented temperature control and real - time visual feedback of the solder morphology.

[0018] Those of ordinary skill in the art should understand that: the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity. Any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for segmented temperature control and solder visual coordinated control of a high-frequency welding side cold plate, characterized in that: The following steps are included: Step 1: heating from room temperature to 320°C at 10°C / s to eliminate the initial temperature difference of the substrate; Step 2: Raise the temperature from 320°C to 490°C at 10°C / s to balance the temperature field; Step 3: Raise the temperature from 490°C to 600°C at 5.3°C / s to trigger the solder eutectic reaction; Step 4: Cool down to 590°C to provide a stable temperature field for subsequent visual judgment; Step 5: trigger the camera to shoot and perform heat preservation or supplementary heating operations based on the AOI visual judgment results.

2. According to claim 1, the segmented temperature control and solder visual coordinated control method of the high-frequency welding side cold plate is characterized in that: In step 2, the temperature is raised to 490° C. and then kept at this temperature for 5 seconds; in step 4, the temperature is lowered to 490° C. and then kept at this temperature for 5 seconds.

3. According to claim 2, the segmented temperature control and solder visual coordinated control method of the high-frequency welding side cold plate is characterized in that: In the step 5, the solder morphology image is collected by an HDR industrial camera, and the database established by AOI semi-supervised learning is used to compare and identify the welding status.

4. The method for segmented temperature control and solder visual coordinated control of high-frequency welding side cold plate according to claim 3 is characterized in that: The determination conditions of step 5 are: the shrinkage rate of welding wire diameter is ≤ 15% of the initial value, and the edge fuzziness is ≤ 5% of the initial value; If the judgment is passed, the heating will be stopped and the welding will be ended after the preset heating time of 2S; If the judgment fails, start constant 65% power supplementary heating and repeat the visual judgment until the welding wire is completely melted.

5. According to claim 1, the segmented temperature control and solder visual coordinated control method of the high-frequency welding side cold plate is characterized in that: The heating system uses a double-helix high-frequency induction heating coil with a power density uniformity of ±5%, which can be dynamically adjusted from 0 to 50kW.

6. The method for segmented temperature control and solder visual coordinated control of high-frequency welding side cold plate according to claim 3 is characterized in that: The entire process uses an infrared thermal imager to monitor the temperature field distribution in real time. The infrared thermal imager has a wavelength of 7.5-14μm, an accuracy of ±2℃, and a frame rate of 50Hz.

7. The method for segmented temperature control and solder visual coordinated control of high-frequency welding side cold plate according to claim 3 is characterized in that: The HDR industrial camera has a frame rate of 200fps, a resolution of 1280×1024, and a global shutter, and is used for high-precision acquisition of solder morphology.

8. The method for segmented temperature control and solder visual coordinated control of high-frequency welding side cold plate according to claim 6 is characterized in that: It also includes an adaptive control strategy: when there is no feedback from the HDR industrial camera and the infrared thermal imager, welding ends after 2 seconds of heat preservation by default.