Method for determining optimal heating temperature of hot rivet

Abstract

The application discloses a hot rivet optimal heating temperature determination method, which comprises the following steps: S1, placing a rivet into a heating hole and collecting temperature data of the surface of the rivet to generate a temperature-time curve; S2, setting a corresponding heating time in each heating temperature interval based on the temperature-time relationship, and preparing a plurality of riveting test pieces in each heating temperature interval; S3, testing and quantifying the multi-dimensional key performance indicators of the riveting test pieces, including the forming state, the shear bearing capacity and the residual clamping force; S4, normalizing the multi-dimensional key performance indicators to 0-100 points, distributing weights according to engineering requirements to calculate the comprehensive performance scores of each heating temperature interval, and determining the median value of the heating temperature interval with the highest comprehensive performance score as the optimal heating temperature. The application significantly improves the stability and reliability of the riveting quality, and is suitable for the process development and quality control of rivet materials used in hot riveting connection.

Description

Technical Field

[0001] This invention relates to the field of hot riveting technology, and specifically to a method for determining the optimal heating temperature of a hot riveting connection rivet. Background Technology

[0002] Hot riveting, as an important mechanical joining process, is widely used in industrial fields such as aerospace, rail transportation, and bridge construction. This process achieves a reliable structural connection by locally heating the rivet, causing it to mold in a plastic state. The heating temperature of the rivet is a key process parameter that determines the quality of the riveting.

[0003] Currently, in actual production practice, the control and selection of heating temperature for hot riveting rivets mainly have the following limitations:

[0004] First, temperature control methods rely on subjective experience and lack quantitative standards. Traditional processes often depend on operators judging whether the heating is "appropriate" by observing the color of the rivets (colorimetry) or by personal experience. This method is greatly affected by ambient light and individual differences, leading to significant temperature fluctuations and poor process consistency. Excessive temperature can cause the rivet material to overheat and develop coarse grains, reducing its mechanical properties; insufficient temperature results in insufficient plasticity, making it difficult to fully form the rivet. This uncontrollability is one of the main reasons for the inconsistent riveting quality and low reliability.

[0005] Secondly, the quality evaluation system is one-sided and fails to reflect the comprehensive performance of the joint. Current technologies for assessing the quality of hot riveting often remain at the macroscopic forming level, such as only checking whether the head shape is full and whether there are cracks. This single visual inspection cannot quantitatively assess the two core mechanical properties of the joint: shear capacity and residual clamping force (preload). Shear capacity directly relates to the static strength of the joint; while residual clamping force is crucial for the joint's fatigue resistance, anti-loosening capability, and long-term service reliability. Neglecting systematic testing of these intrinsic properties leads to a lack of comprehensive basis for process optimization.

[0006] Finally, there is a lack of scientific decision-making methods that link process parameters with overall performance. Even with some performance testing, existing technologies have failed to establish a systematic analytical framework to quantitatively correlate and comprehensively evaluate the key process parameter of "heating temperature" with multi-dimensional performance indicators such as "molding quality," "joint strength," and "long-term reliability." Therefore, it is difficult to scientifically answer the core process question from a data perspective: "What temperature can achieve the best balance between joint strength and long-term performance while meeting molding requirements?"

[0007] In summary, existing hot riveting processes rely on experience for temperature control, suffer from one-sided quality evaluation, and lack systematic quantitative methods for process decision-making. This has become a bottleneck restricting the improvement of hot riveting connection quality and the modernization of the process. Therefore, there is an urgent need for a systematic method that can achieve precise quantitative control of the heating process and integrate multi-dimensional performance indicators for comprehensive evaluation, thereby scientifically determining the optimal heating temperature. Thus, a method that can comprehensively consider multiple parameters and quantitatively determine the heating temperature is urgently needed to improve the quality control level of the hot riveting process. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention proposes a method for determining the optimal heating temperature of rivets used in hot riveting connections. This method enables a shift from "experience-driven" to "data-driven" approaches, providing a scientific, quantitative, and repeatable optimization method for the hot riveting process.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for determining the optimal heating temperature of a hot-riveting rivet includes:

[0011] S1: After a test rivet is placed into the heating hole, the temperature data of the rivet surface is collected from multiple angles to generate a temperature-time curve. When the rivet is heated later, the heating time is set according to the target temperature and the temperature-time curve. After the set heating time is reached, the rivet is automatically ejected by the automatic ejection mechanism.

[0012] S2: Based on the temperature-time curve relationship obtained in step S1, set the corresponding heating time in each heating temperature range, and prepare multiple riveting test pieces in each heating temperature range. During this process, all process parameters except heating temperature remain unchanged.

[0013] S3: Test and quantify the riveted specimens for key performance indicators in multiple dimensions, including forming state, shear bearing capacity and residual clamping force.

[0014] S4: Normalize the multi-dimensional key performance indicators obtained in step S3 to 0~100 points, allocate weights according to engineering requirements, calculate the comprehensive performance score of the riveting test pieces made in each heating temperature range, and determine the median value of the heating temperature range with the highest comprehensive performance score of the riveting test piece as the optimal heating temperature for this type of rivet.

[0015] Compared with the empirical methods of existing hot riveting processes, the above technical solution has the following advantages in temperature control:

[0016] By incorporating three key performance indicators—forming state, shear capacity, and residual clamping force—into a unified evaluation framework and normalizing and assigning weights, the limitations of traditional single-appearance inspection are avoided, and the comprehensive mechanical properties and long-term service reliability of the connection joint can be systematically reflected.

[0017] By preparing sufficient specimens in multiple temperature ranges and conducting multi-dimensional performance tests, a quantitative relationship between heating temperature and comprehensive performance is established, providing objective and repeatable data for the selection of the optimal heating temperature and supporting the scientific optimization of process parameters.

[0018] The weighting coefficients can be dynamically set according to different engineering scenarios (such as aerospace, bridge construction, etc.) to emphasize different aspects of forming quality, static strength, and fatigue performance, giving the method good engineering adaptability and scalability. Through normalization and weighted scoring models, performance indicators with different dimensions and importance are integrated into a single comprehensive score, which clearly points to the heating temperature range with optimal comprehensive performance, achieving the best balance between strength, forming quality, and reliability.

[0019] Furthermore, in step 3, the testing and quantification of the forming state is based on a comprehensive score of the rivet's surface morphology, geometric dimensions, and cross-sectional fill degree, with the average of the three factors being taken, where:

[0020] The surface morphology refers to the qualitative observation of the morphology of the rivet head, with a full score of 100 points. Based on the number and size of the damage, 10 points are deducted for each damage, 20 points are deducted for damage larger than 2mm, and 50 points are deducted for damage larger than 5mm. The damage includes: cracks and indentations. Crack size: refers to its visible length; Indentation size: refers to its maximum outer diameter or the size along its longest direction.

[0021] The geometric dimensions refer to the quantitative measurement of the geometric dimensions of the rivet head, which must meet the following requirements: head diameter D ≥ 1.5d, head height H ≥ 0.5d, and head center offset s < 0.1d, where d is the original diameter of the rivet rod. The full score is 100 points. If any of the three dimensions (head diameter D, head height H, and head center offset s) has an error of less than 0.1d, 15 points will be deducted; if the error is greater than 0.1d, 30 points will be deducted.

[0022] The section filling degree is assessed by measuring the diameters of the rivet shank and rivet hole on multiple cross sections and calculating the difference between the average inner diameter of the rivet hole and the average outer diameter of the rivet shank. The full score is 100 points. For every 0.2mm difference between the maximum and minimum diameters of the rivet shank, 10 points are deducted, and 50 points are deducted if the difference exceeds 0.6mm. For every 0.2mm difference between the average inner diameter of the rivet hole and the average outer diameter of the rivet shank, 10 points are deducted, and 50 points are deducted if the difference exceeds 0.6mm.

[0023] Beneficial effects: Establishing a quantitative molding evaluation system: By using a graded deduction system for scoring surface morphology, geometric dimensions, cross-sectional filling degree, and layer adhesion, subjective visual inspection is transformed into objective quantitative evaluation, improving the consistency and traceability of quality judgment.

[0024] Furthermore, the testing and quantification steps for the forming state also include a layer-to-layer fit test, which is performed as follows: after cutting the riveted specimen along the center of the rivet, a feeler gauge is used to measure the maximum gap between the rivet shank and the hole wall. When the insertion depth of a 0.3mm thick feeler gauge is no more than 20mm, it is defined as qualified.

[0025] Furthermore, the shear bearing capacity test and quantification involves linearly scaling the measured force values, with the maximum value corresponding to 100 points and the minimum value corresponding to 0 points, and calculating using the following formula:

[0026] ,

[0027] Where F is the measured shear capacity of the rivet within the selected heating temperature range, F max F represents the maximum shear capacity of the rivet measured in all temperature ranges. min This represents the minimum shear capacity of the rivet measured across all heating temperature ranges.

[0028] Furthermore, the testing and quantification of the residual clamping force involves linearly scaling the residual axial stress value of the rivet, with the maximum value corresponding to 100 points and the minimum value corresponding to 0 points, calculated using the following formula:

[0029] ,

[0030] in, The residual clamping force of the rivets was measured within the selected heating temperature range. The maximum residual clamping force of the rivets measured across all heating temperature ranges. This represents the minimum residual clamping force of the rivet measured across all heating temperature ranges.

[0031] Furthermore, in step S3, the residual clamping force test of the riveted specimen is performed by implanting a strain gauge in the middle of the rivet. The method for implanting the strain gauge includes: machining a mounting hole in the middle of the rivet shank, the depth of which is... Satisfy the following formula:

[0032] ,

[0033] Where L is the length of the rivet after riveting, and b is the length of the strain gauge; the strain gauge is placed in the mounting hole and cured with adhesive.

[0034] Beneficial effects: By implanting strain gauges into the rivet rod and combining them with calibration coefficients, accurate measurement of residual clamping force under non-destructive or minimal-damage conditions can be achieved, providing key data for connection reliability assessment.

[0035] Furthermore, a calibration coefficient is set for the relationship between the strain value and the axial stress of the rivet, and the calibration coefficient is calculated by the following formula:

[0036] ,

[0037] in, The force applied to the rivet that implants the strain gauge; This represents the corresponding strain value change.

[0038] Furthermore, in step S4, the formula for calculating the comprehensive performance score is as follows:

[0039] ,

[0040] in, For the overall performance score, To score the molding condition, For shear bearing capacity scoring, Scoring for residual clamping force; , , These are the corresponding weight coefficients, and they satisfy:

[0041] ,

[0042] Each weighting coefficient is set according to the specific requirements of engineering applications for molding quality, connection strength and long-term reliability.

[0043] Furthermore, in step S2, no fewer than 30 riveting specimens are prepared within each defined heating temperature range.

[0044] In summary, the present invention provides a method for determining the optimal heating temperature of hot riveting rivets. The method has a clear process, the detection methods are easy to implement, and the evaluation system is highly structured. It is applicable to the process development and production quality control of hot riveting rivets of different materials and specifications, and has broad industrial application prospects. Attached Figure Description

[0045] Figure 1 This is a flowchart of the method for determining the optimal heating temperature of hot riveting rivets in this invention;

[0046] Figure 2 This is a schematic diagram showing the position for measuring the dimensions of the rivets after riveting in this invention;

[0047] Where D is the diameter of the pier head; H is the height of the pier head; d1 is the diameter of the upper end of the rivet rod; d2 is the diameter of the middle part of the rivet rod; and d3 is the diameter of the lower end of the rivet rod.

[0048] Figure 3 This is a record diagram of the dimensional measurement performed in the example description of this invention;

[0049] Among them, 7 is the auxiliary line for measuring the diameter of the pier head, 8 is the key observation area for the surface morphology of the pier head, and 9 is the schematic diagram of the feeler gauge test position when conducting gap filling test.

[0050] Figure 4 These are defects that occurred during the measurements described in the examples of this invention;

[0051] Figure 5 This is a diagram of the riveted specimen used in the shear bearing capacity test as described in the example of this invention;

[0052] Figure 6 This is a graph showing the trend of strength change of the rivet material itself after natural cooling at different temperatures when the material properties of the rivet are tested after heating.

[0053] Figure 7 This is a diagram showing the shear bearing capacity data of the connectors at different heating temperatures in the example illustration of this invention;

[0054] Figure 8 This is a schematic diagram of the pretreatment of the riveted specimen when detecting the residual clamping force of the hot-riveted rivet in this invention.

[0055] Where 1 represents the strain gauge; 2 represents the aperture. l1 is the depth of the mounting hole, and l1 is the distance from the strain gauge to the bottom of the hole.

[0056] Figure 9 This is a photograph of the riveted specimen after the strain gauges were installed, as illustrated in the example of this invention.

[0057] Figure 10 This is a strain data graph collected during the residual clamping force measurement in the example description of this invention. Detailed Implementation

[0058] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] A method for determining the optimal heating temperature of a hot-riveted rivet includes the following steps:

[0061] S1: Acquisition of temperature-time curve during heating process

[0062] A test rivet is placed in a heating device, and its surface temperature data is collected using multi-angle temperature sensors to plot a temperature-time curve. Based on this curve, corresponding heating times are set for different target temperatures. After heating is complete, an automatic ejection mechanism ejects the rivet, achieving standardization and controllability of the heating process.

[0063] S2: Preparation of multi-temperature-range riveting specimens

[0064] Based on the temperature-time relationship obtained from S1, several heating temperature ranges are defined (e.g., in 50°C intervals). Within each range, multiple riveting specimens are prepared according to the corresponding heating time (it is recommended to prepare no fewer than 30). Except for the heating temperature, other process parameters (such as riveting pressure, holding time, etc.) are kept constant to ensure that temperature is the only variable.

[0065] S3: Multi-dimensional Key Performance Indicator Testing and Quantification

[0066] The following three categories of key performance indicators were tested and quantified on the prepared riveted specimens:

[0067] S3.1 Molding State Testing and Quantification

[0068] The molding condition score is derived from the following three sub-indicators, and the average of the three is taken:

[0069] Surface morphology observation: Visually inspect the rivet heads, deducting points based on the quantity and size of defects such as cracks and indentations. The maximum score is 100 points, with 10 points deducted for each defect; 20 points deducted for a size > 2mm; and 50 points deducted for a size > 5mm. Crack size: refers to its visible length; Indentation size: refers to its maximum outer diameter or the dimension along its longest direction.

[0070] Geometric Dimension Measurement: Measure the diameter D of the pier head, the height H of the pier head, and the offset s of the pier head center. The following conditions must be met: D ≥ 1.5d, H ≥ 0.5d, s < 0.1d (d is the original diameter of the rivet rod). Deduct 15 points for each dimensional error < 0.1d, and deduct 30 points for each error ≥ 0.1d.

[0071] Section filling degree test: Measure the diameter of the rivet shank and rivet hole on multiple sections, and calculate the difference between the average inner diameter of the rivet hole and the average outer diameter of the rivet shank. Deduct 10 points for every 0.2mm difference between the maximum and minimum diameter of the shank (deduct 50 points if the difference exceeds 0.6mm); deduct 10 points for every 0.2mm difference between the average diameter of the rivet hole and the rivet shank (deduct 50 points if the difference exceeds 0.6mm).

[0072] Optionally, a panel fit test can also be performed: the specimen is split along the center of the rivet, and a feeler gauge with a thickness of 0.3 mm is used to measure the gap between the rivet shank and the hole wall. An insertion depth of ≤20 mm is considered acceptable.

[0073] S3.2 Shear bearing capacity testing and quantification

[0074] Shear tests were conducted on the riveted specimens using a tensile testing machine, and the maximum shear capacity was recorded. The measured values ​​for each temperature range were linearly normalized to a range of 0-100.

[0075] ;

[0076] Where F represents the measured shear capacity within the selected heating temperature range, F max F represents the maximum measured shear capacity across all heating temperature ranges. min This is the minimum measured value.

[0077] S3.3 Residual clamping force test and quantification

[0078] Residual clamping force was measured using the implanted strain gauge method.

[0079] Drill a mounting hole in the middle of the rivet shank, the depth of the mounting hole is... calculate;

[0080] ,

[0081] Where L is the length of the rivet after riveting, and the 80mm rivet used has a length of 74mm after hot riveting; b is the length of the strain gauge, and the strain gauge used in the example has a length of 8mm.

[0082] The strain gauge is implanted into the hole and cured with adhesive. The bonding process is maintained for a certain time to avoid air bubbles or cracks caused by high-speed curing, which could interfere with the measurement results.

[0083] After installing the strain gauges, connect the wires and use a DH3816 strain gauge to measure and record the strain gauge data.

[0084] Carefully remove the upset head on the other side of the rivet using a band saw. Then, fix the specimen in a fixture and slowly hammer the rivet shank out from the other side using a hand drill and a punch. During this process, record the strain signal generated by the stress release of the rivet in real time. ;

[0085] According to Hooke's Law, the strain value is proportional to the longitudinal stress of the rivet relaxation, but due to the presence of adhesive, the relationship between the strain value and the axial stress of the rivet needs to be calibrated.

[0086] During calibration, each removed rivet is calibrated individually by applying force using a jack equipped with a pressure sensor or a pressure testing machine. Record the strain of the strain gauge during the calibration process. The ratio of the measured strain value to the diameter of the applied force is used as the coefficient k1;

[0087] ;

[0088] Correct the obtained measured strain, evaluate the residual axial force, and calculate the residual axial stress;

[0089]

[0090] .

[0091] The measured residual clamping force values ​​in each temperature range were linearly normalized to 0~100 points:

[0092] ;

[0093] in, To select a heating temperature range, the residual clamping force was measured. This represents the maximum measured residual clamping force across all heating temperature ranges. This represents the minimum measured residual clamping force across all heating temperature ranges.

[0094] S4: Overall Performance Score Calculation and Optimal Temperature Determination

[0095] The normalized scores S1S (forming state), S2 (shear bearing capacity), and S3 (residual clamping force) of the above three indicators are weighted according to engineering requirements, and the comprehensive performance score for each temperature range is calculated:

[0096] ,

[0097] ,

[0098] in, For the overall performance score, To score the molding condition, For shear bearing capacity scoring, The residual clamping force is scored.

[0099] The weights w1, w2, and w3 can be adjusted according to the emphasis on forming quality, connection strength, and long-term reliability in actual engineering projects. For example, for bridge structures, w1=0.2, w2=0.4, and w3=0.4.

[0100] The heating temperature range with the highest overall performance score is determined as the optimal heating temperature for that type of rivet. Example Description

[0101] Taking the hot riveting connection of a certain bridge as an example, rivets made of Q345 steel with a diameter of 24mm were selected as the experimental object. See Figure 1 .

[0102] Determine the time-temperature change curve during the rivet heating process.

[0103] Based on engineering experience, the commonly recommended temperature for this type of rivet is used as the central reference point, and a temperature range is extended to both high and low temperatures. According to past construction experience and relevant specifications, the rivet heating temperature range during the construction of common bridge hot riveting connections is 950-1050℃. To determine the appropriate temperature, the test temperature range is extended to 850-1150℃. This extended temperature range is divided into six heating temperature intervals of 50℃: 850~900℃, 900~950℃, 950~1000℃, 1000~1050℃, 1050~1100℃, and 1100~1150℃.

[0104] Based on the time-temperature curve of the rivet during heating, corresponding heating times were set for the six heating temperature ranges. Test rivets were then placed in the rivets to verify whether the set heating times accurately reached the corresponding heating temperature ranges.

[0105] Within each defined heating temperature range, at least 30 riveting specimens were prepared to ensure statistical significance. During specimen preparation, other process parameters (such as riveting pressure and holding time) were kept consistent. Then, the following three core properties of the riveting specimens were measured and evaluated: w1=0.2, w2=0.4, and w3=0.4.

[0106] Results analysis: The comprehensive score of each interval was calculated. Assuming that the 1000–1050℃ interval had the highest score, the optimal heating temperature was set at 1025℃.

[0107] Any adaptive changes made according to actual needs are within the scope of protection of this invention.

[0108] It should be noted that, for those skilled in the art, it is obvious that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0109] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for determining the optimal heating temperature of a hot-riveting rivet, characterized in that, include: S1: After a test rivet is placed into the heating hole, the temperature data of the rivet surface is collected from multiple angles to generate a temperature-time curve. When the rivet is heated later, the heating time is set according to the target temperature and the temperature-time curve. After the set heating time is reached, the rivet is automatically ejected by the automatic ejection mechanism. S2: Based on the temperature-time curve relationship obtained in step S1, set the corresponding heating time in each heating temperature range, and prepare multiple riveting test pieces in each heating temperature range. During this process, all process parameters except heating temperature remain unchanged. S3: Test and quantify the riveted specimens for key performance indicators in multiple dimensions, including forming state, shear bearing capacity and residual clamping force. S4: Normalize the multi-dimensional key performance indicators obtained in step S3 to 0~100 points, allocate weights according to engineering requirements, calculate the comprehensive performance score of the riveting test pieces made in each heating temperature range, and determine the median value of the heating temperature range with the highest comprehensive performance score of the riveting test piece as the optimal heating temperature for this type of rivet.

2. The method for determining the optimal heating temperature of a hot-riveted rivet according to claim 1, characterized in that, In step 3, the testing and quantification of the forming state is based on a comprehensive score of the rivet's surface morphology, geometric dimensions, and cross-sectional fill degree, with the average of the three factors being taken. The surface morphology refers to the qualitative observation of the morphology of the rivet head, with a full score of 100 points. Based on the number and size of the damage, 10 points are deducted for each damage, 20 points are deducted for damage larger than 2mm, and 50 points are deducted for damage larger than 5mm. The damage includes: cracks and indentations. Crack size: refers to its visible length; Indentation size: refers to its maximum outer diameter or the size along its longest direction. The geometric dimensions refer to the quantitative measurement of the geometric dimensions of the rivet head, which must meet the following requirements: head diameter D ≥ 1.5d, head height H ≥ 0.5d, and head center offset s < 0.1d, where d is the original diameter of the rivet rod. The full score is 100 points. If any of the three dimensions (head diameter D, head height H, and head center offset s) has an error of less than 0.1d, 15 points will be deducted; if the error is greater than 0.1d, 30 points will be deducted. The section filling degree is assessed by measuring the diameters of the rivet shank and rivet hole on multiple cross sections and calculating the difference between the average inner diameter of the rivet hole and the average outer diameter of the rivet shank. The full score is 100 points. For every 0.2mm difference between the maximum and minimum diameters of the rivet shank, 10 points are deducted, and 50 points are deducted if the difference exceeds 0.6mm. For every 0.2mm difference between the average inner diameter of the rivet hole and the average outer diameter of the rivet shank, 10 points are deducted, and 50 points are deducted if the difference exceeds 0.6mm.

3. The method for determining the optimal heating temperature of a hot-riveted rivet according to claim 2, characterized in that, The testing and quantification steps for the forming state also include a layer-to-layer fit test, which is performed as follows: after cutting the riveted specimen along the center of the rivet, a feeler gauge is used to measure the maximum gap between the rivet shank and the hole wall. When the insertion depth of a 0.3mm thick feeler gauge is no more than 20mm, it is defined as qualified.

4. The method for determining the optimal heating temperature of a hot-riveted rivet according to claim 1, characterized in that, The shear bearing capacity test and quantification involves linearly scaling the measured force values, with the maximum value corresponding to 100 points and the minimum value corresponding to 0 points, and calculating using the following formula: ， in, To determine the measured shear capacity of the rivets within a selected heating temperature range, The maximum shear capacity of the rivet measured across all heating temperature ranges. This represents the minimum shear capacity of the rivet measured across all heating temperature ranges.

5. The method for determining the optimal heating temperature of a hot-riveted rivet according to claim 1, characterized in that, The testing and quantification of the residual clamping force involves linearly scaling the residual axial stress value of the rivet, with the maximum value corresponding to 100 points and the minimum value corresponding to 0 points, calculated using the following formula: ， in, The residual clamping force of the rivets was measured within the selected heating temperature range. The maximum residual clamping force of the rivets measured across all heating temperature ranges. This represents the minimum residual clamping force of the rivet measured across all heating temperature ranges.

6. The method for determining the optimal heating temperature of a hot-riveted rivet according to claim 1, characterized in that, In step S3, the residual clamping force test of the riveted specimen is performed by inserting a strain gauge into the middle of the rivet. The method for inserting the strain gauge includes: machining a mounting hole in the middle of the rivet shank, the depth of which is... Satisfy the following formula: ， Where L is the length of the rivet after riveting, and b is the length of the strain gauge; the strain gauge is placed in the mounting hole and cured with adhesive.

7. The method for determining the optimal heating temperature of a hot-riveted rivet according to claim 6, characterized in that, A calibration coefficient is set for the relationship between strain values ​​and axial stress of the rivet, and the calibration coefficient is calculated by the following formula: ， in, The force applied to the rivet that implants the strain gauge; This represents the corresponding strain value change.

8. The method for determining the optimal heating temperature of a hot-riveted rivet according to claim 1, characterized in that, In step S4, the formula for calculating the comprehensive performance score is as follows: ， in, For the overall performance score, To score the molding condition, For shear bearing capacity scoring, Scoring for residual clamping force; , , These are the corresponding weight coefficients, and they satisfy: ， Each weighting coefficient is set according to the specific requirements of engineering applications for molding quality, connection strength and long-term reliability.

9. The method for determining the optimal heating temperature of a hot-riveted rivet according to claim 1, characterized in that, In step S2, no fewer than 30 riveting specimens are prepared within each defined heating temperature range.

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