Connecting rod small end bushing fitting degree detection system

Abstract

The invention discloses a connecting rod small end lining fitting degree detection system. The system is characterized by comprising a base, a positioning mechanism, a detection mechanism, a driving mechanism, a support, a control unit and a data processing unit; the micro hydraulic pump is communicated with the detection mandrel through a hydraulic pipe; a plurality of groups of pressure sensors are arranged on the outer wall of the detection mandrel; the control unit is electrically connected with the positioning mechanism, the micro hydraulic pump, the driving mechanism and the data processing unit. And the data processing unit receives data of the pressure sensor and analyzes the fitting degree of the bushing. The method has the advantages that the whole process from positioning, detection to result output is automatic, manual intervention is not needed, local tiny pressure differences can be captured, pressure distribution is visually presented through a thermodynamic diagram, and manual subjective judgment errors are avoided; by replacing the V-shaped supporting block, the large-head hole positioning pin and the detection mandrel, the detection device can be compatible with detection of various types of connecting rods, the detection mandrel is made of a polyurethane elastic material, the expansion pressure is controllable, the connecting rods or bushings cannot be damaged, and no workpiece loss exists in the detection process.

Description

Technical Field

[0001] This invention relates to the field of automotive engine manufacturing technology, and in particular to a connecting rod small end bushing fit detection system. Background Technology

[0002] Connecting rods are core transmission components of power equipment such as internal combustion engines and compressors. The fit between the small end bore and the bushing directly affects transmission efficiency, wear life, and equipment operation stability. If the fit is insufficient (excessive local gap), the bushing will be subjected to uneven force during operation, resulting in abnormal wear or vibration. If the fit is uneven (excessive local pressure), it may cause bushing deformation or small end bore cracking.

[0003] 1. The current mainstream bushing fit testing methods in the industry have obvious defects:

[0004] Feeler gauge test: This method relies on manual operation. The fit is judged by inserting a feeler gauge into the gap between the bushing and the hole. It is inefficient (it takes 3-5 minutes to test a single piece), highly subjective (different operators have different judgment standards), and cannot quantify the pressure distribution. It can only detect "whether there is a gap" and cannot reflect "fit uniformity".

[0005] 2. Image inspection method: The end face or inner wall of the bushing is photographed by optical equipment. It can only detect dimensional accuracy and appearance defects (such as scratches and deformation), but cannot obtain the actual contact pressure between the bushing and the hole wall, and cannot determine "hidden poor fit" (such as appearance is qualified but local non-contact).

[0006] 3. Manual pressure testing method: This method requires manual handling of the pressure probe to test point by point. The testing range is limited (it can only cover a local area), the data is highly discrete, and it is difficult to form a comprehensive fit evaluation.

[0007] Therefore, it is necessary to propose a connecting rod small end bushing fit detection system for the above technical solution. Summary of the Invention

[0008] To overcome the shortcomings of existing technologies, this invention proposes a connecting rod small end bushing fit detection system.

[0009] The technical solution adopted by this invention to solve its technical problem is:

[0010] A connecting rod small end bushing fit detection system includes a base, a positioning mechanism, a detection mechanism, a drive mechanism, a bracket, a control unit, and a data processing unit. The positioning mechanism is mounted on the base and is used to position and press the connecting rod. The drive mechanism is mounted on the base via the bracket, and its output end is fixed to the detection mechanism. The detection mechanism includes an elastically expandable detection mandrel and a miniature hydraulic pump. The miniature hydraulic pump is connected to the detection mandrel via a hydraulic pipe, and the outer wall of the detection mandrel is provided with multiple sets of pressure sensors. The control unit is electrically connected to the positioning mechanism, the miniature hydraulic pump, the drive mechanism, and the data processing unit. The data processing unit receives pressure sensor data and analyzes the bushing fit.

[0011] Preferably, the positioning mechanism includes a V-shaped support block, a large-end hole positioning pin, and a pneumatic clamping assembly, wherein the large-end hole positioning pin is clearance-fitted with the large-end hole of the connecting rod.

[0012] Preferably, eight pressure sensors are evenly distributed around the outer circumference of the detection mandrel, arranged in two rows along the axial direction; the outer wall of the detection mandrel is made of polyurethane elastic material.

[0013] Preferably, the drive mechanism is a drive electric cylinder or a hydraulic cylinder.

[0014] Preferably, the data processing unit includes a data acquisition card and host computer software, which can generate a heat map of the fit and calculate the percentage of the fit area and the standard deviation of the pressure.

[0015] The algorithm steps for the pressure sensor are as follows:

[0016] S1. Data acquisition triggering and synchronization;

[0017] S2. Data preprocessing (removing invalid values);

[0018] S3, Calculation of core indicators of fit;

[0019] S4. Result visualization and judgment.

[0020] The triggering timing of S1 is as follows: After the PLC receives the "expansion amount meets the standard" signal from the displacement monitor, it sends a start command to the data acquisition card; at the sampling frequency of 1kHz (1000 times per second) set in the document, it synchronously collects the pressure values ​​of 16 sensors for 10 seconds (the "detection time" parameter in the document).

[0021] Data storage: Real-time storage of raw pressure data from each sensor, denoted as... in

[0022] i represents the circumferential sensor number (1-8, corresponding to a 45° interval);

[0023] j represents the axial sensor number (1-2, corresponding to a 10mm spacing).

[0024] t represents the data collection time point (1-10000, a total of 1000×10=10000 data points);

[0025] 7. A connecting rod small end bushing fit detection system as described in claim 6, characterized in that: in step S2, a moving average method is used to reduce fluctuations for 10,000 raw data points from each sensor, calculated using the following formula:

[0026]

[0027] Where k represents the smoothed data points (3-9998). To avoid boundary value errors, the average value of each smoothed sensor data is taken as the representative pressure value of the sensor, denoted as P_avg(i,j).

[0028] S3 includes the calculation of the bonding area ratio and the pressure standard deviation;

[0029] The steps for calculating the percentage of the bonding area are as follows:

[0030] Count the number of valid sensors, N is qualified: iterate through 16 sensors and count to meet the requirement.

[0031] Number of sensors with a strength ≥0.2MPa; Calculate the bonding area ratio:

[0032]

[0033] Where N_total = 16 (a fixed value, corresponding to 16 sensors). The number of sensors with pressure ≥ 0.2 MPa;

[0034] The steps for calculating the standard deviation of pressure are as follows:

[0035] Calculate the average pressure value represented by the 16 sensors:

[0036] , The average pressure value of a single sensor; i = 1-8 (circumference), j = 1-2 (axial direction);

[0037] Calculate the pressure standard deviation (reflecting the dispersion of pressure from each sensor):

[0038] The denominator is 15, which is the unbiased standard deviation calculation, in accordance with engineering data processing conventions. k: data point number. The average of the two data points is taken to reduce instantaneous fluctuations. σ≤0.1MPa indicates that the bonding uniformity is qualified.

[0039] In S6, the heatmap generation utilizes host computer software, mapping different colors according to a coordinate system of "8 sets of circumferential (X-axis) × 2 rows of axial (Y-axis)". The size (e.g., red = ≥ 0.5 MPa, green = 0.2-0.5 MPa, yellow = < 0.2 MPa) is used to generate a "circumferential-axial" fit heat map;

[0040] Final acceptance criteria: The bushing fit is considered acceptable if both of the following conditions are met:

[0041] The bonding area ratio η ≥ 90%;

[0042] Pressure standard deviation σ ≤ 0.1 MPa.

[0043] The beneficial effects of this invention are:

[0044] 1. The entire process from positioning and detection to result output is automated without human intervention. The detection time for a single piece is ≤30 seconds, which is 6-10 times more efficient than feeler gauge detection. It uses 16 sets of high-precision pressure sensors (accuracy ±0.01MPa) to cover the entire inner wall of the bushing. Combined with 1kHz high-frequency sampling, it can capture local small pressure differences and avoid missing "hidden poor fit".

[0045] 2. The bonding measurement is quantified by using "bonding area ratio" and "pressure standard deviation" and the heat map presents the pressure distribution intuitively, avoiding errors from subjective human judgment.

[0046] 3. By replacing the V-shaped support block, the large-end hole positioning pin, and the detection mandrel (adapted to different small-end hole diameters), it can be compatible with the detection of various models of connecting rods, with wide adaptability; the detection mandrel is made of polyurethane elastic material, and the expansion pressure is controllable (0-1MPa), which will not damage the connecting rod or bushing, and there is no workpiece loss during the detection process. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a system principle block diagram of the present invention;

[0049] Figure 2 This is a system structure diagram of the present invention;

[0050] Figure 3 This is a structural diagram of the positioning mechanism of the present invention;

[0051] Figure 4 This is a flowchart of the algorithm for the pressure sensor of the present invention.

[0052] The attached figures are labeled as follows: 1. Base; 2. Positioning mechanism; 3. Detection mechanism; 4. Drive mechanism; 5. Bracket; 6. Control unit; 7. Data processing unit; 8. Detection spindle; 9. Miniature hydraulic pump; 10. Pressure sensor; 11. V-shaped support block; 12. Large-end hole positioning pin; 13. Pneumatic clamping assembly; 14. Connecting rod. Detailed Implementation

[0053] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0054] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in many different ways as defined and covered by the claims.

[0055] The following is in conjunction with the appendix Figures 1 to 4 As shown, this application will be described in further detail below.

[0056] A connecting rod small end bushing fit detection system includes a base 1, a positioning mechanism 2, a detection mechanism 3, a drive mechanism 4, a bracket 5, a control unit 6, and a data processing unit 7. The positioning mechanism 2 is mounted on the base 1 and is used to position and press the connecting rod 14. The drive mechanism 4 is mounted on the base 1 via the bracket 5, and the output end of the drive mechanism 4 is fixed to the detection mechanism 3. The detection mechanism 3 includes an elastically expandable detection mandrel 8 and a micro hydraulic pump 9. The micro hydraulic pump 9 is connected to the detection mandrel 8 via a hydraulic pipe, and the outer wall of the detection mandrel 8 is provided with multiple sets of pressure sensors 10. The control unit 6 is electrically connected to the positioning mechanism 2, the micro hydraulic pump 9, the drive mechanism 4, and the data processing unit 7. The data processing unit 7 receives data from the pressure sensors 10 and analyzes the bushing fit.

[0057] Furthermore, the positioning mechanism 2 includes a V-shaped support block 11, a large-end hole positioning pin 12, and a pneumatic clamping assembly 13, wherein the large-end hole positioning pin 12 is clearance-fitted with the large-end hole of the connecting rod 14.

[0058] Furthermore, eight pressure sensors 10 are evenly distributed around the outer circumference of the detection mandrel 8, arranged in two rows along the axial direction; the outer wall of the detection mandrel 8 is made of polyurethane elastic material.

[0059] Furthermore, the drive mechanism 4 is a drive electric cylinder or a hydraulic cylinder.

[0060] Furthermore, the data processing unit 7 includes a data acquisition card and host computer software, which can generate a heat map of the fit and calculate the percentage of the fit area and the standard deviation of the pressure.

[0061] The algorithm steps for the pressure sensor are as follows:

[0062] S1. Data acquisition triggering and synchronization;

[0063] S2. Data preprocessing (removing invalid values);

[0064] S3, Calculation of core indicators of fit;

[0065] S4. Result visualization and judgment.

[0066] 8. A connecting rod small end bushing fit detection system as described in claim 6, characterized in that: the triggering timing of S1 is as follows: after the PLC receives the "expansion amount meets the standard" signal from the displacement monitor, it sends a start command to the data acquisition card; according to the 1kHz sampling frequency set in the document (1000 times per second), the pressure values ​​of 16 sensors are collected synchronously for 10 seconds (the "detection time" parameter in the document).

[0067] Data storage: Real-time storage of raw pressure data from each sensor, denoted as... in

[0068] i represents the circumferential sensor number (1-8, corresponding to a 45° interval);

[0069] j represents the axial sensor number (1-2, corresponding to a 10mm spacing).

[0070] t represents the data collection time point (1-10000, a total of 1000×10=10000 data points);

[0071] In step S2, a moving average method is used to reduce fluctuations for 10,000 raw data points from each sensor. The calculation formula is as follows:

[0072] Where k represents the smoothed data points (3-9998). To avoid boundary value errors, the average value of each smoothed sensor data point is taken as the representative pressure value of that sensor, denoted as k. .

[0073] S3 includes the calculation of the bonding area ratio and the pressure standard deviation;

[0074] The steps for calculating the percentage of the bonding area are as follows:

[0075] Count the number of valid sensors, N is qualified: iterate through 16 sensors and count to meet the requirement.

[0076] Number of sensors with a strength ≥0.2MPa; Calculate the bonding area ratio:

[0077]

[0078] Where N_total = 16 (a fixed value, corresponding to 16 sensors). The number of sensors with pressure ≥ 0.2 MPa;

[0079] The steps for calculating the standard deviation of pressure are as follows:

[0080] Calculate the average pressure value represented by the 16 sensors:

[0081] , The average pressure value of a single sensor; i = 1-8 (circumference), j = 1-2 (axial direction);

[0082] Calculate the pressure standard deviation (reflecting the dispersion of pressure from each sensor):

[0083] The denominator is 15, which is the unbiased standard deviation calculation, in accordance with engineering data processing conventions. k: data point number. The average of the two data points is taken to reduce instantaneous fluctuations. σ≤0.1MPa indicates that the bonding uniformity is qualified.

[0084] In S6, the heatmap generation utilizes host computer software, mapping different colors according to a coordinate system of "8 sets of circumferential (X-axis) × 2 rows of axial (Y-axis)". The size (e.g., red = ≥ 0.5 MPa, green = 0.2-0.5 MPa, yellow = < 0.2 MPa) is used to generate a "circumferential-axial" fit heat map;

[0085] Final acceptance criteria: The bushing fit is considered acceptable if both of the following conditions are met:

[0086] The bonding area ratio η ≥ 90%;

[0087] Pressure standard deviation σ ≤ 0.1 MPa.

[0088] The beneficial effects of this invention are:

[0089] 1. The entire process from positioning and detection to result output is automated without human intervention. The detection time for a single piece is ≤30 seconds, which is 6-10 times more efficient than feeler gauge detection. It uses 16 sets of high-precision pressure sensors (accuracy ±0.01MPa) to cover the entire inner wall of the bushing. Combined with 1kHz high-frequency sampling, it can capture local small pressure differences and avoid missing "hidden poor fit".

[0090] 2. The bonding area ratio and pressure standard deviation are used to achieve quantitative evaluation of bonding, and the heat map intuitively presents the pressure distribution, avoiding the error of subjective judgment by humans;

[0091] 3. By replacing the V-shaped support block, the large-end hole positioning pin, and the detection mandrel (adapted to different small-end hole diameters), it can be compatible with the detection of various models of connecting rods, with wide adaptability; the detection mandrel is made of polyurethane elastic material, and the expansion pressure is controllable (0-1MPa), which will not damage the connecting rod or bushing, and there is no workpiece loss during the detection process.

[0092] Execution of detection steps

[0093] Workpiece positioning: Place the connecting rod to be tested on the V-shaped support block, and fit the connecting rod's large end hole into the large end hole positioning pin. After the photoelectric sensor detects the workpiece, it sends a "positioning signal" to the PLC. The PLC controls the pneumatic clamping component cylinder to extend, and the clamping head clamps the large end of the connecting rod. The clamping force is fed back through the pressure sensor (to ensure the pressure is ≥500N to prevent movement).

[0094] Mandrel insertion and expansion: The PLC controls the extension of the electric cylinder push rod, which drives the detection mandrel to insert into the small end bushing of the connecting rod at a speed of 1 mm / s. When the end of the mandrel is close to the bottom of the bushing (the stroke is detected by the displacement sensor at 80 mm), the speed is reduced to 0.5 mm / s until it is fully inserted. Then the micro hydraulic pump starts and pressurizes the oil chamber of the mandrel. The pressure rises from 0 to 1.5 MPa, and the mandrel expands radially. The displacement monitor detects the expansion amount in real time. When the expansion amount reaches 0.2 mm, an "expansion standard signal" is sent.

[0095] Data Acquisition: After receiving the "expansion meets the standard signal", the PLC sends a start command to the data acquisition card. The acquisition card synchronously acquires 16 sets of pressure sensor data at a frequency of 1kHz for 10 seconds, acquiring a total of 10,000 data points / sensors. The raw data is stored in real time to the host computer database. The data format is defined as: P(i,j,t), where i=1-8 (circumferential sensors, 45° interval), j=1-2 (axial numbering, 10mm interval), and t=1-10000 (time point).

[0096] Data preprocessing: The host computer software performs a moving average processing on 10,000 raw data points from each sensor. The calculation formula is: P_smooth(k) = [P(k-1) + P(k) + P(k+1)] / 3 (k = 3 - 9998, to avoid boundary value errors). The average value of the smoothed 9996 data points is then taken to obtain the representative pressure value of the sensor. .

[0097] Core indicator calculation:

[0098] The percentage of the bonding area η: Traversing 16 groups The number of sensors N that meet the requirement of P_avg(i,j)≥0.2MPa is considered qualified. If N is qualified = 15 (15 sensors meet the standard), then η = 15 / 16 × 100% = 93.75% (≥90%, meeting the requirement).

[0099] Pressure standard deviation σ: First calculate 16 groups The average value P_total_avg = (ΣP_avg(i,j)) / 16 (assuming P_total_avg = 0.4MPa); then calculate according to the unbiased standard deviation formula: σ = √[Σ(P_avg(k) - P_total_avg)² / (16-1)] (k = 1-16). If the calculated σ = 0.08MPa (≤ 0.1MPa, which meets the requirements).

[0100] Results visualization and judgment: The host computer software generates a heat map according to the coordinates of "8 groups of circles (X-axis) × 2 rows of axes (Y-axis)": Among the 15 qualified sensors, 8 have P_avg≥0.5MPa (displayed in red), 7 have 0.2-0.5MPa (displayed in green), and 1 has <0.2MPa (displayed in yellow); Since η=93.75%≥90% and σ=0.08MPa≤0.1MPa, the system judges "fitting degree qualified", and displays the results and heat map on the interface, while storing the test report.

[0101] System Reset: After the test is completed, the micro hydraulic pump is depressurized, and the test mandrel retracts to its original diameter; the PLC-controlled electric cylinder push rod retracts, and the test mandrel exits the bushing; the pneumatic clamping assembly cylinder retracts, releasing the connecting rod; the operator removes the connecting rod, and the system waits for the next test cycle.

[0102] Example 1:

[0103] 1. Applicable Scenarios

[0104] A certain auto parts manufacturer mass-produces connecting rods (model: L15-01) for 1.5L gasoline engines. The small end bore diameter is φ25mm, the large end bore diameter is φ50mm, the total length of the connecting rod is 120mm, and the width of the rod body is 18mm. The small end bushing needs to be tested to ensure that it fits evenly against the connecting rod bore wall, so as to avoid abnormal noise or premature wear of the bushing when the engine is idling.

[0105] 2. System configuration adjustments

[0106] Positioning mechanism adaptation: Replace the V-shaped support block 11 with a customized version with "90° included angle and 20mm support surface width" (to match the rod width); the large end hole positioning pin 12 adopts φ49.9mm (with a gap of 0.1mm between it and the φ50mm large end hole, which meets the clearance fit requirements); replace the pneumatic clamping assembly 13 with an arc-shaped rubber pressure head (to prevent damage to the connecting rod surface), and set the clamping force threshold to 550N (≥500N, to avoid workpiece movement).

[0107] Testing agency adaptation: The testing mandrel 8 is replaced with a polyurethane elastic mandrel with an initial diameter of φ24.8mm and an axial length of 40mm (compatible with a φ25mm small end hole), and the outer wall maintains the layout of "8 sets of pressure sensors 10 on the circumference (spaced at 45°) and 2 rows on the axis (spaced at 10mm)"; the micro hydraulic pump 9 retains the original model (maximum output pressure 2MPa).

[0108] Drive mechanism parameters: The drive electric cylinder is set with a push rod stroke of 150mm (covering the total length of the connecting rod), and the initial insertion speed is 1mm / s. When the displacement sensor detects that the stroke has reached 120mm (the mandrel is close to the bottom of the bushing), the speed is reduced to 0.5mm / s.

[0109] 3. Detect the execution process

[0110] Workpiece positioning: The operator places the connecting rod 14 on the V-shaped support block 11 and inserts the positioning pin 12 into the large end hole; after the photoelectric sensor sends the "positioning signal", the PLC controls the pneumatic clamping assembly 13 to extend, and the pressure feedback is 550N, completing the positioning.

[0111] Mandrel insertion and expansion: The drive cylinder push rod extends, and the detection mandrel 8 inserts into the bushing at 1 mm / s. After a stroke of 120 mm, the speed is reduced to 0.5 mm / s until it is fully inserted (total stroke 130 mm). The micro hydraulic pump 9 pressurizes to 1.5 MPa. When the displacement monitor detects that the mandrel has expanded by 0.2 mm, it sends an "expansion meets the standard signal".

[0112] Data Acquisition and Preprocessing: The data acquisition card acquires 16 sets of sensor data at a frequency of 1kHz for 10 seconds (a total of 10,000 data points / sensor); the host computer uses the moving average method (formula:

[0113] Smooth the data and take the average. .

[0114] Core indicator calculation: Adhesion area ratio η: 16 groups P avg Of the 15 groups, ≥0.2MPa (range 0.22-0.53MPa) and 1 group, 0.19MPa, η=16 / 15×100%=93.75% (≥90%).

[0115] Pressure standard deviation σ: 16 groups P avg

[0116] The average value is 0.38 MPa, and the unbiased standard deviation formula yields σ = 0.07 MPa (≤ 0.1 MPa).

[0117] Result judgment and reset: The thermal map shows that out of 15 sets of grid sensors, 6 sets are red (≥0.5MPa), 9 sets are green (0.2-0.5MPa), and 1 set is yellow (<0.2MPa); the system judges "fit is qualified" and generates a test report; then the hydraulic pump is depressurized, the mandrel retracts, the electric cylinder is reset, the clamping assembly is released, the operator removes the connecting rod, and the single-piece test time is 28 seconds.

[0118] Example 2:

[0119] 1. Applicable Scenarios

[0120] A heavy machinery factory produces a 6.0L diesel engine connecting rod (model: D60-03) with a small end bore diameter of φ40mm, a large end bore diameter of φ80mm, a total connecting rod length of 200mm, and a weight of 5kg. The bushing fit needs to be tested to cope with the impact load during high-load operation of the diesel engine and to prevent the bushing from falling off.

[0121] 2. System configuration adjustments

[0122] Positioning mechanism adaptation: V-shaped support block 11 is replaced with a heavy-duty version with "60° included angle and 30mm support surface width" (enhancing load-bearing stability); the large end hole positioning pin 12 adopts φ79.8mm (with a gap of 0.2mm between it and the φ80mm large end hole, adapting to the assembly error of heavy parts); the pneumatic clamping component 13 is upgraded to a dual-cylinder drive, the pressure head is made of hard alloy material, and the clamping force threshold is set to 800N (≥500N, to prevent the displacement of heavy workpieces).

[0123] Testing agency adaptation: The testing mandrel 8 is replaced with an enhanced polyurethane mandrel with an initial diameter of φ39.7mm and an axial length of 60mm (with added glass fiber to resist deformation), and the axial sensor spacing is adjusted to 15mm (to match the axial length of the bushing); the micro hydraulic pump 9 is replaced with a model with a maximum output pressure of 2.5MPa (to meet the expansion requirements of the large-diameter mandrel).

[0124] Drive mechanism parameters: Drive mechanism 4 is replaced with a hydraulic cylinder (for greater thrust), push rod stroke is 250mm, initial insertion speed is 0.8mm / s (for smooth advancement of the heavy-duty mandrel), and the speed decreases to 0.3mm / s at a stroke of 220mm. 3. Detection of the execution process.

[0125] Workpiece positioning: Using lifting tools, the connecting rod 14 is placed on the V-shaped support block 11, and the positioning pin 12 is inserted into the large end hole; after the photoelectric sensor is triggered, the double cylinders extend, and the pressure feedback is 850N (meeting the threshold). Mandrel insertion and expansion: The hydraulic cylinder push rod extends, and the detection mandrel 8 is inserted at 0.8mm / s, and after a stroke of 220mm, the speed is reduced to 0.3mm / s, and it is fully inserted when the total stroke is 230mm; the hydraulic pump pressurizes to 1.8MPa, and after the mandrel expands by 0.2mm, a "compliance signal" is sent.

[0126] Data Acquisition and Preprocessing: Data was acquired for 10 seconds at a frequency of 1kHz, and after moving average processing, 16 sets of P... avg All are ≥0.2MPa (range 0.25-0.6MPa).

[0127] Core indicator calculation:

[0128] The percentage of the bonding area η = 16 / 16 × 100% = 100% (≥ 90%).

[0129] Pressure standard deviation σ: The average value is 0.42 MPa, and the unbiased standard deviation is calculated to be σ = 0.05 MPa (≤ 0.1 MPa).

[0130] Result judgment and reset: If all heat maps are red (10 groups) and green (6 groups), the system judges them as "qualified"; the reset process is the same as in Example 1, and the single-item detection time is 29 seconds.

[0131] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A connecting rod small end bushing fit detection system, characterized in that: The device includes a base (1), a positioning mechanism (2), a detection mechanism (3), a drive mechanism (4), a bracket (5), a control unit (6), and a data processing unit (7). The positioning mechanism (2) is located on the base (1) and is used to position and press the connecting rod (14). The drive mechanism (4) is mounted on the base (1) through the bracket (5), and the output end of the drive mechanism (4) is fixed to the detection mechanism (3). The detection mechanism (3) includes an elastically expandable detection mandrel (8) and a micro hydraulic pump (9). The micro hydraulic pump (9) is connected to the detection mandrel (8) through a hydraulic pipe. The outer wall of the detection mandrel (8) is provided with multiple pressure sensors (10). The control unit (6) is electrically connected to the positioning mechanism (2), the micro hydraulic pump (9), the drive mechanism (4), and the data processing unit (7) respectively. The data processing unit (7) receives data from the pressure sensors (10) and analyzes the bushing fit.

2. The connecting rod small end bushing fit detection system as described in claim 1, characterized in that: The positioning mechanism (2) includes a V-shaped support block (11), a large-end hole positioning pin (12), and a pneumatic clamping assembly (13). The large-end hole positioning pin (12) is clearance-fitted with the large-end hole of the connecting rod (14).

3. The connecting rod small end bushing fit detection system as described in claim 2, characterized in that: The outer wall of the detection mandrel (8) is uniformly distributed with 8 groups of pressure sensors (10) and arranged in 2 rows along the axis; the outer wall of the detection mandrel (8) is made of polyurethane elastic material.

4. The connecting rod small end bushing fit detection system as described in claim 3, characterized in that: The drive mechanism (4) is a drive electric cylinder or a hydraulic cylinder.

5. The connecting rod small end bushing fit detection system as described in claim 4, characterized in that: The data processing unit (7) includes a data acquisition card and host computer software, which can generate a heat map of the fit and calculate the fit area ratio and pressure standard deviation.

6. The connecting rod small end bushing fit detection system as described in claim 1, characterized in that: The algorithm steps of the pressure sensor are as follows: S1. Data acquisition triggering and synchronization; S2, Data Preprocessing; S3, Calculation of core indicators of fit; S4. Result visualization and judgment.

7. The connecting rod small end bushing fit detection system as described in claim 6, characterized in that: The triggering timing of S1 is as follows: After the PLC receives the "expansion amount meets the standard" signal from the displacement monitor, it sends a start command to the data acquisition card; according to the 1kHz sampling frequency set in the document, it synchronously collects the pressure values ​​of 16 sensors and continues to collect for 10 seconds. Data storage: Real-time storage of raw pressure data from each sensor, denoted as... in i represents the number of the circumferential sensor; j represents the axial sensor serial number; t represents the data collection time point.

8. The connecting rod small end bushing fit detection system as described in claim 6, characterized in that: In step S2, a moving average method is used to reduce fluctuations for 10,000 raw data points from each sensor. The calculation formula is as follows: Where k represents the smoothed data points to avoid boundary value errors, the average value of each smoothed sensor data point is taken as the representative pressure value of that sensor, denoted as k. .

9. The connecting rod small end bushing fit detection system as described in claim 6, characterized in that: S3 includes the calculation of the bonding area ratio and the pressure standard deviation; The steps for calculating the percentage of the bonding area are as follows: Count the number of valid sensors, N is qualified: iterate through 16 sensors and count to meet the requirement. Number of sensors with a pressure ≥0.2MPa; Calculate the bonding area ratio: Where Ntotal = 16, The number of sensors with pressure ≥ 0.2 MPa; The steps for calculating the standard deviation of pressure are as follows: Calculate the average pressure value represented by the 16 sensors: , The average pressure value of a single sensor; i = 1-8, j = 1-2; Calculate the standard deviation of pressure: The denominator is 15, which is the unbiased standard deviation calculation, in accordance with engineering data processing conventions. k: data point number. The average of the two data points is taken to reduce instantaneous fluctuations. σ≤0.1MPa indicates that the bonding uniformity is qualified.

10. The connecting rod small end bushing fit detection system as described in claim 6, characterized in that: In S6, the heatmap generation utilizes host computer software, mapping coordinates using different colors according to 8 sets of circumferential coordinates × 2 rows of axial coordinates. The size is used to generate a circumferential-axial fit heat map; Final acceptance criteria: The bushing fit is considered acceptable if both of the following conditions are met: The bonding area ratio η ≥ 90%; Pressure standard deviation σ≤0.1MPa.

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