A method for determining the acceptable level of residual flux in brazed radiators based on multi-condition testing

Abstract

This invention discloses a method for determining the pass / fail status of residual flux in brazed radiators based on multi-condition testing, belonging to the field of brazed radiator testing technology. The method establishes a set of multi-condition judgment values ​​for direct extraction without cleaning, extraction after cleaning at 80℃ for 5 hours, extraction after cleaning at 80℃ for 3 hours, and extraction after cleaning at 70℃ for 3 hours. It determines the weld length L of the radiator to be tested, extracts and detects the potassium ion concentration C according to the target conditions, calculates the residual flux weight G and the residual flux per unit weld length E, and then compares these values ​​with the corresponding judgment values ​​to determine whether the radiator is pass / fail. This invention can improve the consistency, accuracy, and repeatability of residual flux detection and pass / fail determination in brazed radiators.

Description

Technical Field

[0001] This invention relates to the field of brazed radiator testing technology, specifically to a method for determining the qualification of residual flux in brazed radiators based on multi-condition testing. Background Technology

[0002] With the development of new energy vehicles, pure electric, hybrid, plug-in hybrid, and range-extended vehicles all require thermal management for components such as batteries, motors, and electronic controls. The demand for low-conductivity antifreeze in the cooling systems of new energy vehicles is increasing. Its composition differs from ordinary antifreeze, and when circulating in the cooling system, it may react with residual flux in the brazed radiator, posing a risk to sensitive components in the cooling system.

[0003] Brazed radiators inevitably contain some flux residue during the manufacturing process. For these radiators, the main quality control measure is to detect and control the amount of flux residue to keep it within a reasonable range to meet the requirements of the vehicle manufacturer or customer.

[0004] According to relevant test data, flux residue testing can be performed by rinsing the radiator with deionized water and then measuring the potassium ion content in the rinsing solution to calculate the residual flux weight. For low-temperature radiators, the allowable residual amount can also be calculated based on the weld length. While these methods provide basic testing criteria, they do not establish one-to-one corresponding acceptance criteria for measured residual levels in the uncleaned state and under different cleaning temperatures and times. This results in a lack of a unified and repeatable acceptance method for different customer residual requirements and different pretreatment conditions. Summary of the Invention

[0005] Technical problems to be solved The technical problem solved by this invention is to establish a judgment method based on multi-condition testing, which objectively determines whether the residual flux of brazed radiators is qualified by means of potassium ion extraction detection, flux residual weight conversion, weld length normalization, and judgment value comparison under different cleaning / extraction conditions. Technical solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for determining the acceptable level of flux residue in brazed radiators based on multi-condition testing, comprising the following steps: S1, establishing a set of multi-condition judgment values, wherein the set of multi-condition judgment values ​​includes: a judgment value Emax of 0.06 g / m for the unwashed direct extraction condition, a judgment value Emax of 0.007 g / m for the extraction condition after cleaning at 80℃ for 5 hours, a judgment value Emax of 0.008 g / m for the extraction condition after cleaning at 80℃ for 3 hours, and a judgment value Emax of 0.009 g / m for the extraction condition after cleaning at 70℃ for 3 hours; S2, obtaining the brazed radiator to be tested, and determining the length L of the internal weld seam of the brazed radiator to be tested, where L is the sum of the lengths of all weld seams in the product, in meters; S3, based on the brazed radiator to be tested... The flux residue control requirements are as follows: S4, select a target test condition from the set of multi-condition judgment values, and perform potassium ion extraction on the brazed radiator under test according to the target test condition to obtain an extract; S5, detect the potassium ion concentration C in the extract and calculate the flux residue weight G according to G=(C×V / 1000) / P, where C is the potassium ion concentration in milligrams per liter, V is the circulating liquid volume of the equipment in liters, P is the mass fraction of potassium element in the flux, and G is in grams; S6, calculate the flux residue E per unit weld length according to E=G / L, where E is in grams per meter; S7, compare E with the judgment value Emax corresponding to the target test condition. When E≤Emax, the flux residue of the brazed radiator under test is deemed qualified; when E>Emax, it is deemed unqualified.

[0007] Preferably, when the brazed radiator to be tested is a low-temperature radiator, the length L of the internal weld is calculated according to the formula L=nT×(lT+2×(2×(wT-hT)+π×hT)), where nT is the number of cooling tubes, lT is the length of the cooling tube, wT is the width of the cooling tube, hT is the height of the cooling tube, and π is pi.

[0008] Preferably, the unwashed direct extraction condition includes: connecting the brazed radiator to be tested to a cyclic test device, the cyclic test device including a water pump, a temperature regulator, a thermometer and pipeline, so that deionized water enters the inlet of the brazed radiator to be tested from the temperature regulator through the pipeline, and flows out from the outlet of the brazed radiator to be tested and then flows back to the temperature regulator through the water pump.

[0009] Preferably, in the unwashed direct extraction condition, the volume of deionized water is 7.5L, the temperature of deionized water is 80℃, the circulation flow rate is 8L / min, and the circulation extraction time is 24h; after the circulation extraction is completed, the extract is cooled to 25±5℃, and 50ml of the extract is taken to detect the potassium ion concentration.

[0010] Preferably, in the unwashed direct extraction condition, the volume of deionized water is 15L, the temperature of deionized water is 80±2℃, the circulation flow rate is 15L / min±0.5L / min, and the circulation extraction time is 24h. After the circulation extraction is completed, the solution is cooled to 25℃ and 50ml of the extract is taken for ICP analysis of potassium ion content. The circulation extraction is repeated twice, and the deionized water is replaced before the second circulation extraction, and C=C1+C2, where C1 is the potassium ion concentration obtained from the first circulation extraction and C2 is the potassium ion concentration obtained from the second circulation extraction.

[0011] Preferably, when the target test conditions are 80℃ cleaning for 5 hours followed by extraction, 80℃ cleaning for 3 hours followed by extraction, or 70℃ cleaning for 3 hours followed by extraction, an intermediate cleaning step is performed first. The intermediate cleaning step includes: adding 40L of deionized water to the temperature regulator, allowing the deionized water to enter the brazed radiator under test through the pipeline and circulate, and turning the water pump to 0.75kW; after cleaning, draining the deionized water from the brazed radiator under test, and then performing potassium ion extraction.

[0012] Preferably, the deionized water temperature and cleaning time in the intermediate cleaning step are any one of the following: 80℃, 5h; 80℃, 3h; 70℃, 3h.

[0013] Preferably, the chemical composition of the flux includes KAlF4, which is a potassium aluminum fluoride; when the mass fraction of potassium in the flux is 27.5%, P is 0.275.

[0014] Preferably, when the automobile manufacturer or customer has specified requirements for the amount of flux residue, the qualification is determined according to the unit weld length limit specified by the automobile manufacturer or customer. Beneficial effects

[0015] Compared with the prior art, the present invention provides a method for determining the qualification of residual flux in brazed heat sinks based on multi-condition testing, which has the following beneficial effects: 1. This invention uses potassium in the flux as the detection target. By converting the potassium ion concentration in the extract into the residual flux weight, it can correspond to the dissolution of potassium-containing flux in deionized water medium, thus providing a quantifiable data basis for flux residue detection.

[0016] 2. This invention establishes a set of multi-condition judgment values ​​for direct extraction without cleaning, extraction after cleaning at 80℃ for 5 hours, extraction after cleaning at 80℃ for 3 hours, and extraction after cleaning at 70℃ for 3 hours, so that both ordinary residue requirements and low residue requirements can be mapped to specific test conditions and judgment values.

[0017] 3. This invention converts the residual flux weight into the residual flux amount per unit weld length and uses it as a qualification criterion, which can reduce the judgment deviation caused by size differences in brazed heat sinks with different weld lengths.

[0018] 4. This invention clarifies the process of cyclic extraction, intermediate cleaning, potassium ion detection, residual weight calculation and qualification comparison, which facilitates the repeated execution of the flux residue test of brazed radiators under fixed conditions, and also facilitates the determination of the amount of flux determined by automobile manufacturers or customers. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the experimental apparatus for circulating extraction and intermediate washing used in this invention.

[0020] Figure 2 This is a schematic diagram for calculating the weld length of a low-temperature radiator.

[0021] Figure 3 This is a flowchart for determining the acceptable level of flux residue according to the present invention.

[0022] Figure 4 This is a comparison chart of multi-condition test data and judgment values ​​for the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings. The following description is based on experimental apparatus and multi-condition test data on flux residue in brazed radiators, and is intended to enable those skilled in the art to practice the present invention.

[0024] The flux contains KAlF4, a potassium aluminum fluoride, where K represents potassium. Since potassium can serve as a tracer for the dissolution of potassium-containing flux in an aqueous medium, this invention measures the K ion content in the extract during testing; the K ion content is equivalent to the potassium ion concentration.

[0025] refer to Figure 1 The circulating extraction and intermediate cleaning test apparatus used in this invention includes a water pump, a brazed radiator under test, a thermometer, a temperature regulating thermostat, and piping. The temperature regulating thermostat is used to contain deionized water and regulate its temperature; the thermometer is used to measure the temperature of the deionized water; and the piping connects the temperature regulating thermostat, the water pump, and the brazed radiator under test. During the test, deionized water enters the inlet of the brazed radiator under test through the piping, flows out from the outlet of the brazed radiator under test, enters the water pump, and finally flows back to the temperature regulating thermostat.

[0026] I. Determination of Weld Length and Allowable Residual Amount in Foundation The length of the internal weld seam of the radiator is the sum of the lengths of all weld seams in the product. (Reference) Figure 2 For low-temperature radiators, the weld length L (in meters) can be calculated using formula (1): L=nT×(lT+2×(2×(wT-hT)+π×hT)); (1) In the formula, nT is the number of cooling tubes, in units; lT is the length of the cooling tube, in meters; wT is the diameter of the cooling tube, in meters; hT is the height of the cooling tube, in meters; and π is the mathematical constant pi.

[0027] According to the basic flux residue requirements, the allowable residual flux weight G0 (in grams) can be calculated using formula (2): G0 = 0.1 × L; (2) In the formula, 0.1 represents the flux content per unit length, expressed in grams per meter. If the vehicle manufacturer or customer has other requirements, those requirements shall apply.

[0028] II. Direct extraction without washing refer to Figure 1 In the direct extraction process without cleaning, the brazed radiator under test is connected to the circulating test device. Deionized water is added to the temperature control thermostat and the temperature of the deionized water is kept constant at 80℃ or 80±2℃. The deionized water enters the inlet of the brazed radiator under test through the pipeline, then flows out from the outlet of the brazed radiator under test, enters the water pump, and finally flows back to the temperature control thermostat.

[0029] Under specific experimental conditions, the volume of deionized water was 7.5 L, the circulation flow rate was 8 L / min, and the circulation extraction time was 24 h. After the circulation extraction was completed, the extract was cooled to room temperature (25 ± 5 °C), and 50 ml of the extract was taken to determine the potassium ion concentration.

[0030] Under another flux residue test condition, the volume of deionized water was 15 L, the temperature was 80 ± 2 °C, the flow rate was 15 L / min ± 0.5 L / min, the rinsing time was 24 h, and after rinsing, the solution was cooled to 25 °C. 50 ml of the rinsing solution was taken, and the potassium ion content was analyzed by ICP. This cycle was repeated twice, with the deionized water replaced before the second cycle. ICP is an inductively coupled plasma analysis method.

[0031] III. Extraction after intermediate washing refer to Figure 1 During the intermediate cleaning step, 40L of deionized water is added to the temperature control thermostat, and the temperature of the deionized water is controlled at 80℃ or 70℃, and the temperature is measured by a thermometer. The deionized water enters the inlet of the brazed heat sink under test through the pipeline, and then flows out from the outlet of the brazed heat sink under test into the water pump. The water pump is turned up to 0.75kW, and finally flows back to the temperature control thermostat.

[0032] Intermediate cleaning can be performed under the following three conditions: 80℃ for 5 hours, 80℃ for 3 hours, and 70℃ for 3 hours. After intermediate cleaning, the deionized water inside the brazed radiator to be tested is drained, and then potassium ion extraction and testing are performed on the brazed radiator to be tested.

[0033] IV. Calculation of residual flux weight and residual flux per unit weld length When two extraction cycles are performed, the potassium ion concentration C (in milligrams per liter) used for conversion is calculated according to formula (3): C = C1 + C2; (3) In the formula, C1 represents the potassium ion content detected during the first rinse, in mg / L; C2 represents the potassium ion content detected during the second rinse, in mg / L. When performing one extraction cycle, C represents the potassium ion concentration detected in that extraction.

[0034] The residual flux weight G (in grams) is calculated according to formula (4): G=(C×V / 1000) / P;(4) In the formula, V is the volume of circulating liquid in the equipment, in liters; P is the mass fraction of potassium in the flux. When the flux is KAlF4 and calculated based on a potassium mass fraction of 27.5%, P is taken as 0.275. In formula (4), C×V gives the mass of potassium ions, in milligrams; after dividing by 1000, it is converted to grams; then divided by P gives the residual weight based on flux.

[0035] The residual flux amount E per unit weld length (in grams per meter) is calculated according to formula (5): E=G / L; (5) Formula (5) normalizes the residual flux weight according to the weld length, which can be used to determine the brazed radiator with different weld lengths.

[0036] V. Multi-condition qualification criteria refer to Figure 3 First, determine the target test conditions based on the flux residue control requirements of the brazed radiator to be tested; second, perform direct extraction without cleaning, or perform extraction after intermediate cleaning; third, detect the potassium ion concentration and calculate G and E; finally, compare E with the judgment value Emax (in grams per meter) corresponding to the target test conditions. If E is not greater than Emax, it is considered qualified; if E is greater than Emax, it is considered unqualified.

[0037] refer to Figure 4 Based on the results of the multi-condition test, the judgment values ​​are shown in the table below: 1 Extraction without washing No intermediate cleaning 73 2.0 0.06 2 Extraction after washing at 80℃ for 5 hours 40L deionized water, 80℃, 0.75kW, 5h 8.6 0.2 0.007 3 Extraction after washing at 80℃ for 3 hours 40L deionized water, 80℃, 0.75kW, 3h 9.8 0.3 0.008 4 Extraction after washing at 70℃ for 3 hours 40L deionized water, 70℃, 0.75kW, 3h 10.0 0.3 0.009 As shown in the table above, when brazed radiators are extracted directly without cleaning after brazing, a flux residue of 0.06 g / m per unit weld length can be used as the judgment value for ordinary residual levels. If the customer requires a lower flux residue, an intermediate cleaning step can be added before extraction. The judgment value corresponding to extraction after cleaning at 80℃ for 5 hours is 0.007 g / m, the judgment value corresponding to extraction after cleaning at 80℃ for 3 hours is 0.008 g / m, and the judgment value corresponding to extraction after cleaning at 70℃ for 3 hours is 0.009 g / m.

[0038] Example 1: Direct extraction without cleaning Select the brazed heat sink to be tested and determine its weld length L. Connect the brazed heat sink to be tested. Figure 1 The cyclic test apparatus shown was used to add 7.5L of deionized water at 80℃ and circulated for extraction at a flow rate of 8L / min for 24h. After extraction, the solution was cooled to 25±5℃ and 50ml of the extract was taken to detect the potassium ion concentration. The detected potassium ion concentration was taken as C. C, V and P were substituted into formula (4) to obtain G. Then G and L were substituted into formula (5) to obtain E. If E≤0.06g / m, it was deemed qualified.

[0039] Example 2: Extraction process after washing at 80℃ for 5 hours Select the brazed radiator to be tested. First, perform intermediate cleaning with 40L of 80℃ deionized water, with the water pump running at 0.75kW. After cleaning for 5 hours, drain the deionized water from the inside of the brazed radiator. Then, perform potassium ion extraction, detection, and calculation. If E≤0.007g / m, it is considered qualified.

[0040] Example 3: Extraction process after washing at 80℃ for 3 hours Select the brazed radiator to be tested. First, perform intermediate cleaning with 40L of 80℃ deionized water, with the water pump turned up to 0.75kW. After cleaning for 3 hours, drain the deionized water from the inside of the brazed radiator. Then, perform potassium ion extraction, detection, and calculation. If E≤0.008g / m, it is considered qualified.

[0041] Example 4: Extraction process after washing at 70℃ for 3 hours Select the brazed radiator to be tested. First, perform intermediate cleaning with 40L of 70℃ deionized water, with the water pump turned up to 0.75kW. After cleaning for 3 hours, drain the deionized water from the inside of the brazed radiator. Then, perform potassium ion extraction, detection, and calculation. If E≤0.009g / m, it is considered qualified.

[0042] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art, without departing from the technical concept of the present invention based on multi-condition testing, potassium ion extraction detection, flux residual weight conversion, and unit weld length qualification judgment, can make adaptive adjustments to specific operating parameters based on customer requirements or automobile manufacturer regulations.

Claims

1. A method for determining the acceptable level of residual flux in brazed radiators based on multi-condition testing, characterized in that, Includes the following steps: S1. Establish a set of multi-condition judgment values, which includes: the judgment value Emax corresponding to the unwashed direct extraction condition is 0.06 g / m, the judgment value Emax corresponding to the extraction condition after washing at 80℃ for 5 hours is 0.007 g / m, the judgment value Emax corresponding to the extraction condition after washing at 80℃ for 3 hours is 0.008 g / m, and the judgment value Emax corresponding to the extraction condition after washing at 70℃ for 3 hours is 0.009 g / m. S2, Obtain the brazed radiator to be tested, and determine the length L of the internal weld of the brazed radiator to be tested. L is the sum of all the lengths in the product, and the unit is meters. S3, according to the flux residue control requirements of the brazed radiator to be tested, select the target process from the set of multi-condition judgment values, and extract the radiator according to the target process to obtain the extract; S4, detect the potassium ion concentration C in the extract, and calculate the residual flux weight G according to G=(C×V / 1000) / P, where C is the potassium ion concentration in milligrams per liter, V is the circulating liquid volume in the equipment in liters, P is the mass fraction of potassium in the flux, and G is in grams. S5. Calculate the residual flux E per unit weld length according to E=G / L, where E is in grams per meter. S6. Compare E with the judgment value Emax corresponding to the target test condition. When E≤Emax, the flux residue of the brazed radiator under test is deemed qualified. When E>Emax, it is deemed unqualified.

2. The method for determining the acceptable amount of residual flux in a brazed radiator based on multi-condition testing according to claim 1, characterized in that, When the brazed heat sink to be tested is a low-temperature heat sink, the length L of the internal weld is calculated according to the formula L=nT×(lT+2×(2×(wT-hT)+π×hT)), where nT is the number of cooling tubes, lT is the length of the cooling tube, wT is the width of the cooling tube, hT is the height of the cooling tube, and π is pi.

3. The method for determining the acceptable level of residual flux in a brazed radiator based on multi-condition testing as described in claim 1, characterized in that, The unwashed direct extraction condition includes: connecting the brazed radiator to be tested to a cyclic test device, which includes a water pump, a temperature regulator, a thermometer, and pipelines, so that deionized water enters the inlet of the brazed radiator to be tested from the temperature regulator through the pipelines, and flows out from the outlet of the brazed radiator to be tested and then flows back to the temperature regulator through the water pump.

4. The method for determining the acceptable amount of residual flux in a brazed radiator based on multi-condition testing according to claim 3, characterized in that, In the unwashed direct extraction process, the volume of deionized water is 7.5L, the temperature of deionized water is 80℃, the circulation flow rate is 8L / min, and the circulation extraction time is 24h. After the circulation extraction is completed, the extract is cooled to 25±5℃, and 50ml of the extract is taken to detect the potassium ion concentration.

5. The method for determining the acceptable amount of residual flux in a brazed radiator based on multi-condition testing according to claim 3, characterized in that, In the unwashed direct extraction condition, the volume of deionized water is 15L, the temperature of deionized water is 80±2℃, the circulation flow rate is 15L / min±0.5L / min, and the circulation extraction time is 24h. After the circulation extraction is completed, the solution is cooled to 25℃ and 50ml of the extract is taken for ICP analysis of potassium ion content. The circulation extraction is repeated twice. Before the second circulation extraction, the deionized water is replaced, and C=C1+C2, where C1 is the potassium ion concentration obtained from the first circulation extraction and C2 is the potassium ion concentration obtained from the second circulation extraction.

6. The method for determining the acceptable amount of residual flux in a brazed radiator based on multi-condition testing according to claim 1, characterized in that, When the target test conditions are 80℃ cleaning for 5 hours followed by extraction, 80℃ cleaning for 3 hours followed by extraction, or 70℃ cleaning for 3 hours followed by extraction, an intermediate cleaning step is performed first. The intermediate cleaning step includes: adding 40L of deionized water to the temperature regulator, allowing the deionized water to enter the brazed radiator under test through the pipeline and circulate, and turning the water pump to 0.75kW; after cleaning, draining the deionized water from the brazed radiator under test, and then performing potassium ion extraction.

7. The method for determining the acceptable amount of residual flux in a brazed radiator based on multi-condition testing according to claim 6, characterized in that, The deionized water temperature and cleaning time in the intermediate cleaning step are any one of the following: 80℃, 5h; 80℃, 3h; 70℃, 3h.

8. The method for determining the acceptable amount of residual flux in a brazed radiator based on multi-condition testing according to claim 1, characterized in that, The chemical composition of the flux includes KAlF4, which is a potassium aluminum fluoride; when the mass fraction of potassium in the flux is 27.5%, P is taken as 0.

275.

9. The method for determining the acceptable amount of residual flux in a brazed radiator based on multi-condition testing according to claim 1, characterized in that, When the automaker or customer has specified requirements for the amount of flux residue, the acceptance shall be determined according to the unit weld length limit specified by the automaker or customer.

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