Welding process for needle plate radiator with cavity

Abstract

The invention relates to the technical field of radiator welding processes, and discloses a welding process for a needle plate type radiator with a cavity, which comprises the following steps: S1, pretreating the surface of a weldment, removing impurities, oil stains and oxide layers on the surfaces of a radiating needle plate, a bottom plate and the cavity, S2, assembling a needle surface brazing sheet, and S3, constructing a friction stir welding sealing cavity. The heat dissipation needle plate and the bottom plate are welded, S4, needle face brazing operation is carried out, S5, appearance visual inspection and verification are carried out, and S6, performance comprehensive detection is carried out. Through FSW welding, the heat dissipation needle plate and the bottom plate (with the cavity) can be connected more tightly and reliably, the airtight yield is effectively improved, the leakage risk of a product is greatly reduced, the sealing performance of the cooling cavity in the long-term use process is ensured, stable operation of a heat dissipation system is guaranteed, meanwhile, the FSW welding process period is short, and the production efficiency is improved. And compared with traditional brazing, a large amount of production time can be saved, and production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of radiator welding processes, and specifically to a welding process for a cavity - type pin - plate radiator. Background Art

[0002] The cavity - type pin - plate radiator combines the advantages of the cavity structure and the pin - plate structure, aiming to improve the heat dissipation efficiency and meet the high - performance heat dissipation requirements in different fields. Its cavity structure draws on the principle of high - efficiency heat transfer using the phase change of working fluids such as heat pipes and vapor chambers, while the pin - plate structure is an optimized design of traditional heat dissipation fins, strengthening heat dissipation by increasing the surface area. In the field of modern electronic device heat dissipation, the cavity - type pin - plate radiator plays a key role. Its working principle is to weld the heat - dissipating pin - plate and the base plate (with cavity) into one body to form a cooling cavity, and introduce coolant through the base plate to take away the heat generated when the heating component works, ensuring the long - term stable operation of the heating component.

[0003] However, in the actual production and processing process, after connecting the heat - dissipating pin - plate and the base plate (with cavity) by the full - surface brazing method, the yield of leakage and air pressure testing of the product is only 85%. This means that a large number of products have potential leakage risks. During long - term use, there is a risk of coolant leakage, resulting in the failure of the heat dissipation system, seriously affecting the normal operation of the heating component, and shortening the service life of the device. In addition, the brazing process on the pin surface of the heat - dissipating pin - plate is prone to poor soldering. Poor soldering will block the heat conduction path, significantly reduce the thermal conductivity, and lower the heat dissipation efficiency of the radiator. At the same time, poor soldering will also weaken the overall strength of the radiator. When subjected to external forces or vibrations, the welded part is prone to cracking and other problems, further affecting the reliability and stability of the product. In view of this, we propose a welding process for a cavity - type pin - plate radiator. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a welding process for a cavity - type pin - plate radiator, which solves the problems of poor airtight performance, heat conduction, and strength during the processing of the existing cavity - type pin - plate radiator.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: A welding process for a cavity - type pin - plate radiator includes the following steps: S1: Pretreatment of the surface of the welded parts Pretreat the heat - dissipating pin - plate, the base plate, and the cavity to remove surface impurities, oil stains, and oxide layers; S2: Assembly of pin - surface brazing sheets Assemble pin - surface brazing sheets on the pin surface of the heat - dissipating pin - plate; S3: Construction of a friction - stir welding - sealed cavity Adopt the friction stir welding process to weld the heat dissipation pin plate and the bottom plate to form a sealed cavity; S4: Needle surface brazing operation Put the welded part completed by friction stir welding into a brazing furnace to complete the brazing of the needle surface of the heat dissipation pin plate and the bottom plate; S5: Appearance visual inspection and verification Use a visual inspection device to inspect the appearance of the welded radiator to check for welding defects; S6: Comprehensive performance detection Conduct airtightness detection, thermal conductivity detection and strength detection on the radiator.

[0006] Preferably, in the S1 surface pretreatment of the welded part, for heat dissipation pin plates and bottom plates of different materials, if it is a copper material, use a mixed solution with a volume ratio of nitric acid to ammonium sulfate of 1:2 for chemical cleaning, and then use sandpaper with a particle size of 800 - 1200 mesh for mechanical polishing until the surface roughness reaches Ra0.8 - Ra1.6μm; if it is an aluminum material, first use an alkaline degreaser to remove oil stains, and then perform anodic oxidation pretreatment to form a uniform oxide film on the surface, and the thickness of the oxide film is controlled at 5 - 10μm.

[0007] Preferably, in the S2 needle surface brazing chip assembly, the needle surface brazing chip uses a new type of composite brazing material. This brazing material is based on a silver-based alloy and adds nano-silicon carbide particles with a mass fraction of 3% - 5%. The nano-silicon carbide particles are uniformly dispersed in the brazing material through a high-energy ball milling process to prepare a brazing chip with a thickness of 0.2 - 0.4 mm.

[0008] Preferably, in the S3 construction of the friction stir welding sealed cavity, the friction stir welding equipment is equipped with an intelligent parameter regulation system. According to the parameters of the heat dissipation pin plate and the bottom plate including material and thickness, the initial welding parameters are calculated through an algorithm model.

[0009] Preferably, during the welding process of the S3 construction of the friction stir welding sealed cavity, use temperature sensors and pressure sensors installed on the welding tool and the welded part to collect data in real time. When the temperature fluctuation exceeds ±10℃ or the pressure fluctuation exceeds ±1MPa, the intelligent regulation system automatically adjusts the welding speed, rotation speed and axial pressure.

[0010] Preferably, in the S4 needle surface brazing operation, an ultrasonic generator is set in the brazing furnace. During the brazing process, the ultrasonic frequency is set to 20 - 40kHz and the power is 100 - 300W. At the same time, a protective gas with a specific ratio is filled in the brazing furnace, and the mixed gas is composed of 95% argon and 5% hydrogen.

[0011] Preferably, in the visual inspection and calibration of the S5 appearance, a three-dimensional detection technology based on machine vision is adopted. The CCD vision detection device is used to take pictures of the radiator from different angles to obtain the three-dimensional image data of the welding part, and the data is analyzed through an image recognition algorithm. For the detected defects, the position and size information are automatically marked and recorded.

[0012] Preferably, in the visual inspection and calibration of the S5 appearance, the three-dimensional detection technology based on machine vision adopts an improved ResNet structure. An attention mechanism module is added on the basis of the original residual block. This module can automatically learn the weighted division of the importance of different regions in the image during the image detection process and has the ability to extract the characteristics of tiny welding defects.

[0013] Preferably, in the comprehensive performance detection of S6, the airtightness detection adopts the combination of a helium mass spectrometer leak detector and a vacuum chamber. The radiator is placed in the vacuum chamber, and the vacuum chamber is evacuated to below 1×10⁻³ Pa, and helium is filled into the radiator. The helium mass spectrometer leak detector detects the concentration of leaked helium; the thermal conductivity detection adopts the laser flash method. A layer of graphite coating is evenly applied on the surface of the radiator, and the thermal conductivity is calculated by measuring the temperature change after the laser pulse excitation; the strength detection adopts a multi-axial tensile testing machine to conduct multi-directional tensile tests on the welded joints.

[0014] Preferably, after the comprehensive performance detection of S6, the radiator is placed in an environment of 150 - 250 °C and kept warm for 2 - 6 hours, and then cooled with the furnace or cooled in a specific cooling medium. During the process, the surface characteristic points of the radiator are monitored at multiple points through an infrared temperature measurement device, and the temperature change curve is measured at the same time. The temperature of the heat treatment process is supplemented and auxiliary heat dissipation is carried out through the difference between the preset temperature change curve and the actual temperature change curve.

[0015] Working principle: The heating element is the working heating element. During operation, the heat generated is taken out by the cavity fluid through the heat dissipation pin plate (made of copper or aluminum). The heat dissipation pin plate and the bottom plate (made of copper or aluminum) form a sealed cavity through the FSW method. Before the FSW of the heat dissipation pin plate and the bottom plate, the pin surface of the heat dissipation pin plate is assembled with pin surface brazing fins. After the FSW of the heat dissipation pin plate and the bottom plate, it enters the brazing furnace to complete the brazing of the pin surface of the heat dissipation pin plate and the bottom plate.

[0016] The present invention provides a welding process for a cavity pin plate type radiator. It has the following beneficial effects: 1. Through FSW welding, the present invention can form a tighter and more reliable connection between the heat dissipation pin plate and the bottom plate (with a cavity), effectively improving the airtightness yield, greatly reducing the leakage risk of the product, ensuring the sealing performance of the cooling cavity during long-term use, and guaranteeing the stable operation of the heat dissipation system. At the same time, the FSW welding process has a short cycle and can save a large amount of production time compared with traditional brazing, improving production efficiency.

[0017] 2. In the present invention, since the strength of FSW welding itself is superior to that of traditional brazing and the process stability is good, and after FSW welding, due to the action of the welding shoulder pressure, the heat dissipation pin plate and the brazing surface can achieve gapless tight fitting. When subsequent needle surface brazing is carried out, this tight fitting can further optimize the heat conduction path and improve the thermal conductivity; at the same time, the overall strength of the radiator is enhanced, effectively avoiding the problem of strength reduction caused by poor soldering and improving the comprehensive performance of the product.

[0018] 3. The present invention compresses the feature map into a channel vector through an extrusion operation, then learns the importance weight of the channel through an excitation operation, and finally recalibrates the feature map, enabling the model to pay more attention to the channel features that are important for the recognition of micro welding defects, enhancing the model's ability to extract micro welding defect features, and thus improving the accuracy and reliability of defect detection at the welding part of the radiator.

[0019] 4. Based on the difference between the preset temperature change curve and the actual temperature change curve, the present invention works in coordination through three links: proportional, integral, and derivative. The proportional link responds quickly according to the current temperature deviation; the integral link accumulates the past temperature deviations to eliminate the steady-state error and ensure long-term temperature accuracy; the derivative link adjusts the control amount in advance according to the change rate of the temperature deviation to avoid excessive temperature fluctuations. During the entire heat treatment process, the surface temperature data of the radiator is obtained in real time through an infrared temperature measurement device, and the temperature difference is continuously calculated to achieve precise temperature control of the heat treatment process of the radiator. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the process flow chart of the welding process for the radiator with a cavity needle plate; Figure 2 is the schematic structural diagram of the radiator with a cavity needle plate of the present invention; Figure 3 is the schematic diagram of conventional brazing in the prior art; Figure 4 is the schematic diagram of brazing of the improved structure of the radiator with a cavity needle plate of the present invention; Figure 5 is the flow chart of the temperature control algorithm steps of the present invention.

[0021] Among them, 1. heating element; 2. heat dissipation pin plate; 3. bottom plate (with cavity); 4. FSW welding; 5. brazing surface; 6. FSW welding head. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Next, in combination with the accompanying drawings in the specification of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] Embodiment: Please refer to the attached Figure 1 - attached Figure 5 , the embodiment of the present invention provides a welding process for a cavity needle plate type radiator, including the following steps: S1: Pretreatment of the surface of the welded part Pretreat the heat dissipation needle plate, bottom plate and cavity to remove surface impurities, oil stains and oxide layers; S2: Assembly of needle surface brazing sheets Assemble needle surface brazing sheets on the needle surface of the heat dissipation needle plate; S3: Construction of a friction stir welding sealed cavity Adopt the friction stir welding process to weld the heat dissipation needle plate and the bottom plate to form a sealed cavity; S4: Needle surface brazing operation Put the welded part completed with friction stir welding into a brazing furnace to complete the brazing of the needle surface of the heat dissipation needle plate and the bottom plate; S5: Appearance visual inspection and verification Use a visual inspection device to inspect the appearance of the welded radiator to check for welding defects; S6: Comprehensive performance detection Conduct airtightness detection, thermal conductivity detection and strength detection on the radiator.

[0024] In the S1 surface pretreatment of the welded part, for heat dissipation needle plates and bottom plates of different materials, if they are copper materials, use a mixed solution with a volume ratio of nitric acid to ammonium sulfate of 1:2 for chemical cleaning, and then use sandpaper with a particle size of 800 - 1200 mesh for mechanical polishing until the surface roughness reaches Ra0.8 - Ra1.6μm; if they are aluminum materials, first use an alkaline degreaser to remove oil stains, and then perform anodic oxidation pretreatment to form a uniform oxide film on the surface, and the thickness of the oxide film is controlled within 5 - 10μm.

[0025] In the S2 assembly of needle surface brazing sheets, the needle surface brazing sheets adopt a new type of composite brazing material, which is based on a silver-based alloy matrix and adds nano-silicon carbide particles with a mass fraction of 3% - 5%. The nano-silicon carbide particles are uniformly dispersed in the brazing material through a high-energy ball milling process to prepare brazing sheets with a thickness of 0.2 - 0.4 millimeters.

[0026] In the construction of the friction stir welding sealed cavity of S3, the friction stir welding equipment is equipped with an intelligent parameter regulation system. According to the parameters of the heat dissipation needle plate and the bottom plate, including the material and thickness, the initial welding parameters are calculated through an algorithm model.

[0027] During the welding process of the friction stir welding sealed cavity of S3, temperature sensors and pressure sensors installed on the welding tool and the welded part are used to collect data in real time. When the temperature fluctuation exceeds ±10°C or the pressure fluctuation exceeds ±1 MPa, the intelligent regulation system automatically adjusts the welding speed, rotation speed, and axial pressure.

[0028] In the needle surface brazing operation of S4, an ultrasonic generator is installed in the brazing furnace. During the brazing process, the ultrasonic frequency is set to 20 - 40 kHz, and the power is 100 - 300 W. At the same time, a specific proportion of protective gas is filled in the brazing furnace, and the mixed gas is composed of 95% argon and 5% hydrogen.

[0029] In the appearance visual inspection and verification of S5, a three-dimensional detection technology based on machine vision is adopted. The radiator is photographed from different angles by a CCD vision detection device to obtain three-dimensional image data of the welding part, and the data is analyzed through an image recognition algorithm. For the detected defects, the position and size information are automatically marked and recorded.

[0030] In the appearance visual inspection and verification of S5, the three-dimensional detection technology based on machine vision adopts an improved ResNet structure. An attention mechanism module is added on the basis of the original residual block. This module can automatically learn the weighted division of the importance of different regions in the image during the image detection process and has the ability to extract the characteristics of tiny welding defects. Therefore, the following algorithm is proposed: Step 1: Input data Let the input image data be , where is the number of input channels, and H and W are the height and width of the image respectively.

[0031] Step 2: ResNet residual block operation Before entering the attention mechanism module, traditional ResNet residual block operations are first performed.

[0032] Convolution operation: Assume that there are two convolutional layers in the residual block. The convolutional kernel of the first convolutional layer is , where is the number of intermediate channels, is the size of the first convolutional kernel. The convolution operation can be expressed as:

[0033] where Denotes a convolution operation.

[0034] The convolution kernel of the second convolutional layer is , where is the number of output channels, is the size of the second convolution kernel. The convolution operation yields:

[0035] Residual connection: If the number of input channels and the number of output channels are not equal, a 1x1 convolution operation is required to adjust the number of channels. Let the convolution kernel for adjusting the channels be , then:

[0036] Otherwise, The output of the residual block is:

[0037] Step 3: Attention mechanism module Squeeze: Perform global average pooling operation on the output of the residual block to obtain a vector z of length .

[0038]

[0039] Where is the feature map of the c-th channel of

[0040] Excite: Learn the channel importance weights through two fully connected layers.

[0041] The weight of the first fully connected layer is , and the bias is , then:

[0042] The weight of the second fully connected layer is , and the bias is , then:

[0043] Where r is the reduction ratio, ReLU is the rectified linear unit activation function, and Sigmoid is the Sigmoid activation function; Feature recalibration: Multiply the learned weights Multiply with the output of the residual block to obtain the final output feature map .

[0044]

[0045] Step 4: Output result The output of the finally improved ResNet structure (with an attention mechanism module) is , which will be used as the input of the next layer to continue the defect calculation in the subsequent defect judgment program

[0046] In the S6 performance comprehensive detection, the airtight detection adopts the combination of a helium mass spectrometer leak detector and a vacuum chamber. The radiator is placed in the vacuum chamber, and the vacuum chamber is evacuated to below 1×10⁻³ Pa, and helium is filled into the radiator. The helium mass spectrometer leak detector detects the concentration of leaked helium; the thermal conductivity detection adopts the laser flash method. A layer of graphite coating is evenly applied on the surface of the radiator, and the thermal conductivity is calculated by measuring the temperature change after the laser pulse excitation; the strength detection adopts a multi-axis tensile testing machine to conduct multi-directional tensile tests on the welded joints

[0047] After the S6 performance comprehensive detection, the radiator is placed in an environment of 150 - 250 °C and kept warm for 2 - 6 hours, and then cooled with the furnace or in a specific cooling medium. During the process, the surface characteristic points of the radiator are monitored at multiple points through an infrared temperature measuring device, and at the same time, its temperature change curve is measured. The temperature supplement and auxiliary heat dissipation for the heat treatment process are carried out through the difference between the preset temperature change curve and the actual temperature change curve. For the temperature control during the heat preservation and cooling processes, the following algorithm is established Initialize parameters: Set the proportionality coefficient , integral coefficient , differential coefficient , and the initial time . At the same time, set the initial value of the integral term , the temperature difference of the previous time . The setting of these parameters depends on the material, size, characteristics of the heat treatment equipment of the radiator and the requirements of the preset temperature change curve Obtain temperature data: At each sampling moment , obtain the actual temperature of the surface characteristic points of the radiator through the infrared temperature measuring device . At the same time, determine the preset temperature at this moment according to the preset temperature change curve ; Calculate the temperature difference: According to the formula , calculate the temperature difference at the current moment Calculate the integral term: The integral term is calculated according to the formula Update, where is the sampling time interval. The role of the integral term is to accumulate past temperature deviations to eliminate the steady-state error of the system; Calculate the differential term: The differential term According to the formula:

[0048] The differential term reflects the rate of change of the temperature deviation, can react to the temperature change trend in advance, and suppress the sharp fluctuations of the temperature; Calculate the control quantity: According to the control formula Calculate the control quantity, and the control quantity will be used to control the working state of the heating or cooling device, including controlling the power output of the heating device or the rotation speed of the cooling fan; Update the parameters and loop: Assign the current temperature difference to for the next calculation of the differential term. Then, the time increases by a sampling time interval and returns to the step of obtaining temperature data to continue the next round of temperature control calculation, continuously adjusting the temperature to make the actual temperature as close as possible to the preset temperature.

[0049] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A welding process for a pin-plate heat sink with a cavity, characterized in that: The following steps are involved: S1: Weldment surface preparation Pre-treat the heat dissipation pin plate, base plate and cavity to remove surface impurities, oil stains and oxide layers; S2: Needle face drill bit assembly Assemble the needle surface brazing piece on the needle surface of the heat dissipation needle plate; S3: Friction stir welding sealed cavity construction The heat dissipation pin plate and the bottom plate are welded to form a sealed cavity by using a stir friction welding process; S4: Pin surface brazing operation Put the weldment after friction stir welding into the brazing furnace to complete the brazing of the needle surface of the heat dissipation needle plate and the bottom plate; S5: Visual inspection of appearance Perform visual inspection on the welded radiator to check for welding defects; S6: Comprehensive performance test Conduct air tightness test, thermal conductivity test and strength test on the radiator.

2. The welding process of a pin-plate heat sink with cavity according to claim 1 is characterized in that: In the S1 weldment surface pretreatment, for heat sink pin plates and base plates of different materials, if the copper material is used, a mixed solution of nitric acid and ammonium sulfate in a volume ratio of 1:2 is used for chemical cleaning, and then mechanical grinding is performed with sandpaper with a particle size of 800-1200 mesh until the surface roughness reaches Ra0.8-Ra1.6μm; If it is aluminum material, use alkaline degreasing agent to remove oil first, and then perform anodizing pretreatment to form a uniform oxide film on the surface. The thickness of the oxide film is controlled at 5-10μm.

3. The welding process of a pin-plate heat sink with cavity according to claim 1 is characterized in that: The S2 needle face brazing piece assembly adopts a new type of composite brazing material, which is based on a silver-based alloy and has 3%-5% nano-silicon carbide particles added thereto by mass. The nano-silicon carbide particles are evenly dispersed in the brazing material through a high-energy ball milling process to prepare a brazing piece with a thickness of 0.2-0.4 mm.

4. The welding process of a pin-plate heat sink with cavity according to claim 1 is characterized in that: In the construction of the S3 friction stir welding sealed cavity, the friction stir welding equipment is equipped with an intelligent parameter control system, which calculates the initial welding parameters through an algorithm model based on the parameters of the heat dissipation needle plate and the base plate including material and thickness.

5. The welding process of the pin-plate heat sink with cavity according to claim 4 is characterized in that: During the welding process of the S3 friction stir welding sealed cavity, temperature sensors and pressure sensors installed on the welding tool and weldment are used to collect data in real time. When the temperature fluctuation exceeds ±10°C or the pressure fluctuation exceeds ±1MPa, the intelligent control system automatically adjusts the welding speed, rotation speed and axial pressure.

6. The welding process of a pin-plate heat sink with cavity according to claim 1 is characterized in that: In the S4 pin surface brazing operation, an ultrasonic generator is arranged in the brazing furnace. During the brazing process, the ultrasonic frequency is set to 20-40kHz and the power is 100-300W. At the same time, a specific proportion of protective gas is filled into the brazing furnace, and the mixed gas is composed of 95% argon and 5% hydrogen.

7. The welding process of a pin-plate heat sink with cavity according to claim 1 is characterized in that: In the S5 appearance visual inspection and verification, a three-dimensional inspection technology based on machine vision is adopted. The CCD visual inspection device is used to photograph the radiator from different angles to obtain three-dimensional image data of the welding parts. The data is analyzed by an image recognition algorithm. For the detected defects, the position and size information are automatically marked and recorded.

8. The welding process of the pin-plate heat sink with cavity according to claim 7 is characterized in that: In the S5 appearance visual inspection and verification, the three-dimensional inspection technology based on machine vision adopts an improved ResNet structure, and adds an attention mechanism module based on the original residual block. This module can automatically learn the weighted division of the importance of different areas in the image during the image detection process, and has the ability to extract the characteristics of tiny welding defects.

9. The welding process of a pin-plate heat sink with cavity according to claim 1 is characterized in that: In the comprehensive performance test of S6, the airtightness test is carried out by combining a helium mass spectrometer leak detector with a vacuum box. The radiator is placed in a vacuum box, which is evacuated to below 1×10⁻³Pa, and helium is filled into the radiator. The helium mass spectrometer leak detector detects the concentration of leaked helium. The thermal conductivity test uses the laser flash method to evenly apply a layer of graphite coating on the surface of the radiator, and calculates the thermal conductivity by measuring the temperature change after laser pulse excitation. The strength test uses a multi-axial tensile testing machine to perform multi-directional tensile tests on the welded joints.

10. A welding process for a pin-plate heat sink with a cavity according to claim 9, characterized in that: After the comprehensive S6 performance test, the radiator is placed in an environment of 150-250°C for 2-6 hours, and then cooled with the furnace or in a specific cooling medium. During the process, the characteristic points on the surface of the radiator are monitored at multiple points through an infrared temperature measuring device, and its temperature change curve is measured at the same time. The difference between the preset temperature change curve and the actual temperature change curve is used to supplement the temperature of the heat treatment process and assist in heat dissipation.

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