Escalator drive chain elongation measuring device and evaluation method

Abstract

The application discloses an escalator driving chain elongation measurement device and evaluation method, and belongs to the technical field of escalator detection. The application establishes a relatively constant force and a relatively stable posture linear measurement section in the non-engagement area of the driving chain through a contact type tension straightening mechanism to reduce the influence of curvature and fluctuation on the consistency of subsequent detection conditions; then, based on the calibrated detection reference, the length-related information in the complete measurement cycle of the driving chain is reconstructed and accumulated to obtain the actual total length, elongation and elongation rate of the driving chain; finally, in combination with the scrap threshold, inspection data, maintenance records and historical change information, the driving chain state is graded determined as normal, attention, early warning and over-standard, thereby providing a quantitative basis for on-site inspection, state recognition and maintenance decision, and effectively solving the problem that the prior art cannot accurately quantify the actual elongation rate, resulting in the lack of data support for evaluation and scrap decision.

Description

Technical Field

[0001] This invention belongs to the field of escalator testing technology, specifically relating to a device and evaluation method for measuring the elongation of an escalator drive chain. Background Technology

[0002] As a critical component for power transmission, the main drive chain of an escalator is extremely vulnerable to damage. If it breaks or detaches due to elongation, wear, or fatigue, the connection between the drive system and the steps will fail, causing the escalator to reverse (i.e., "slip backward"), which can easily lead to a major safety accident. Current standards and regulations have established a comprehensive regulatory system for drive chains, as outlined in GB / T 44843. The 2024 "Safety Assessment Standard for In-Service Escalators and Moving Walks" clearly states that the elongation of the drive chain should not exceed 3% of the design length or exceed the adjustment limits. (GB / T 37217) The 2018 "Technical Conditions for the Scrapping of Major Components of Escalators and Moving Walkways" lists "elongation exceeding 3% of the design length" as a scrapping condition. These regulations and standards together form a complete logic for maintenance inspection, safety assessment, and scrapping determination, and establish 3% elongation as the core safety threshold.

[0003] However, quantifying this key indicator faces significant challenges in engineering practice. The drive chain is located inside the truss, in a confined space, covered in oil stains, and subjected to high-speed movement or high temperatures. Current maintenance, inspection, and evaluation largely rely on technicians' listening, visual inspection, manual testing, or spot checks using calipers while the system is shut down. However, these methods have significant limitations: first, they are highly subjective and lack objective data; second, sampling measurements cannot reflect uneven wear and deformation along the entire chain length; third, downtime sampling inspections are inefficient and disrupt normal public transportation operations; and finally, the drive chain elongates under long-term alternating heavy loads, and the resulting sag curvature and corrosion-induced jamming affect the accurate measurement of its true length. Therefore, the measurement results lack precision and representativeness, making it difficult to truly implement standards and specifications. The hidden risks posed by drive chain elongation persist and continue to threaten public elevator safety.

[0004] Currently, the effective measurement of the elongation of the escalator drive chain has not been effectively solved in engineering practice. The tensioning devices that the industry generally relies on can only perform "passive compensation" and have limited adjustment stroke, making it impossible to accurately quantify the actual elongation rate, resulting in a lack of data support for evaluation and scrapping decisions.

[0005] Existing patent CN114057078B discloses a chain elongation detection device. Its basic idea is to arrange multiple detection sprockets on the chain, with multiple sensors detecting the rotation state of each sprocket. A signal processing device then detects the chain elongation based on the time difference of the rise time of the corresponding rotation pulse. This solution has the following main drawbacks: 1. This scheme primarily relies on the rotational response of the sprocket after meshing with the chain to determine elongation. It lacks a tensioning and straightening mechanism to transform the sag section of the chain into a stable, straight measurement section, and it doesn't establish a structural layout of "local straightening before measurement and maintaining constant tension during measurement." In other words, this scheme emphasizes the meshing and following of the sprocket and chain, rather than prioritizing the elimination or reduction of the impact of chain sag, vibration, and force fluctuations on measurement conditions. Therefore, in actual field testing of the escalator main drive chain, if the chain exhibits local sag, oscillation, or unstable force, its measurement status may still be affected by the chain's running posture and meshing contact state.

[0006] 2. The elongation detection results of this scheme mainly come from the deviation in the rotation time of the sprocket used for testing. Essentially, it is an indirect detection method based on the rotational response of the meshing sprocket, rather than reconstructing the actual length of the entire chain by establishing a calibrated linear measurement benchmark on the chain body under test. In other words, its focus is on judging the elongation state or elongation trend of the chain, rather than directly generating the actual total length, elongation amount, and elongation rate of the entire drive chain.

[0007] 3. This solution is more suitable for automatically detecting chain elongation rather than outputting information on the overall chain length distribution. For cases of uneven chain wear, relying solely on the rotational deviation of the detection sprocket makes it difficult to directly provide distributional results such as which fixed link group is abnormal, the specific location of the abnormal section within the entire chain, and how the cumulative length of the entire chain changes.

[0008] 4. This detection method relies on the meshing contact between the detection sprocket and the chain. The detection results are inevitably related to the meshing state, contact stability, tooth condition, and installation posture of the detection sprocket. In scenarios where the internal space of the escalator truss is limited, the chain is heavily contaminated with oil, and the convenience of maintenance and installation is high, additionally arranging and maintaining the stable meshing of multiple detection sprockets with the chain may bring complexity to the structural installation and contact state maintenance.

[0009] 5. This solution leans more towards a single threshold-based detection logic of "notifying after reaching the baseline elongation," and has not yet formed a multi-level status evaluation system for on-site management. For actual maintenance, simply knowing whether the baseline value has been exceeded is insufficient to support differentiated handling; it is also necessary to distinguish between different states such as normal, attention, warning, and exceeding the standard, and to determine the retesting cycle, key observations, or replacement recommendations based on elongation trends and local anomalies.

[0010] Existing patent CN115754328A discloses a method for real-time detection of chain elongation in escalators and moving walkways. This method requires the installation of detection terminals on the main drive chain, step chain, or handrail drive chain, along with an early warning platform. During escalator operation, the sprocket speed ω and chain travel time TL are detected, and then the chain elongation is calculated and an alarm is triggered. This solution has the following main drawbacks: 1. This measurement scheme primarily relies on patch identification during chain and sprocket operation, failing to address potential issues such as sagging, swaying, local bending, and changes in stress state that may occur in the drive chain on-site. In actual testing scenarios for escalator main drive chains, unstable chain posture and local stress states can easily lead to length conversion results affected by changes in operating conditions and posture, resulting in significant measurement errors.

[0011] 2. The length measurement results obtained by this method rely on intermediate variables such as chain rotation speed, chain radius, and chain running time. The actual length of the chain body is not directly reconstructed from the reference distance within a stable straight measurement segment. If there are deviations in chain rotation speed identification, patch triggering time, chain cycle identification, or chain radius value, the error will be included in the final length conversion.

[0012] 3. The zoning capability of this scheme depends on the deployment of multiple patches. The number of patches, patch positions, reflectivity, and contamination will all affect the area recognition effect. At the same time, its segmentation results are still mainly based on kinematic conversion relationships, rather than the cumulative segmentation of the entire chain after passing through a unified measurement benchmark.

[0013] 4. This identification system relies heavily on reflective patches, non-reflective layers, and additional light-shielding / cleaning structures. Given the oil, dust, and limited space inside the escalator truss, the installation, maintenance, cleaning, and long-term consistency of numerous patches may increase the engineering maintenance burden.

[0014] 5. The evaluation logic of this scheme is more biased towards "real-time detection - alarm when threshold is exceeded", and it does not adequately address the closed-loop relationship between pre-measurement tension conditions, cumulative results of the entire chain segments, local anomaly distribution, repeatability judgment and maintenance strategy. Summary of the Invention

[0015] The present invention aims to overcome the shortcomings of the prior art and provides a device and evaluation method for measuring the elongation of the escalator drive chain.

[0016] An escalator drive chain elongation measuring device includes a tensioning and straightening mechanism, a laser receiver A, a laser emitter A, a laser receiver B, a laser emitter B, and a control and display unit. The tensioning and straightening mechanism is located in the non-engaging area of ​​the drive chain. The tensioning and straightening mechanism includes a support assembly and a lifting power assembly. A tensioning wheel slide frame movable along the height direction of the support assembly is mounted on the support assembly. A first lower tensioning roller and a second lower tensioning roller are mounted at both ends of the tensioning wheel slide frame. A pressure roller vertical slider movable along the height direction of the support assembly is mounted on the support assembly above the tensioning wheel slide frame. A slider fixing bolt for limiting the position of the pressure roller vertical slider is mounted on the pressure roller vertical slider. A pressure force adjustment module is also mounted on the pressure roller vertical slider. The bottom of the pressure force adjustment module... The upper clamping roller is installed. The lifting power assembly is used to drive the tensioning roller sliding frame to move along the height direction of the support assembly. The control and display unit is electrically connected to the clamping force sensor of the clamping force adjustment module, the drive end of the lifting power assembly, laser receiver A, laser emitter A, laser receiver B, and laser emitter B. The working ends of laser receiver A and laser emitter A are arranged opposite each other and are on the same straight line as the center of the first lower tensioning roller. The working ends of laser receiver B and laser emitter B are arranged opposite each other and are on the same straight line as the center of the second lower tensioning roller. Laser receiver A and laser receiver B are located above the upper layer of the drive chain, and laser emitter A and laser emitter B are located below the lower layer of the drive chain.

[0017] Further, the support assembly includes a fixed base plate, a lower cover plate mounted on the fixed base plate, a main support frame mounted on the lower cover plate, an upper cover plate mounted on the top of the main support frame, the main support frame including symmetrically arranged left and right supports, a back support connected between the left and right supports, a lower support seat for the lead screw located between the left and right supports on the upper surface of the lower cover plate, and an upper support seat for the lead screw located between the left and right supports on the lower surface of the upper cover plate, a vertical adjusting lead screw is installed between the upper and lower support seats, vertical slide rails are installed on the front sides of the left and right supports, a lead screw nut that can slide along the length direction of the vertical adjusting lead screw is installed on the vertical adjusting lead screw, and a lead screw nut is connected to the lead screw nut, the lead screw... The female seat is connected to the tensioning wheel sliding frame. A tensioning wheel vertical slider is installed on the surface of the tensioning wheel sliding frame near the vertical slide rail. The tensioning wheel vertical slider is locked in the vertical slide rail and can slide along the vertical slide rail. The first lower tensioning roller and the second lower tensioning roller are installed at both ends of the surface of the tensioning wheel sliding frame away from the vertical slide rail. The pressure wheel vertical slider is locked on the vertical slide rail of the left bracket and is located above the tensioning wheel vertical slider. The pressure wheel vertical slider can slide along the vertical slide rail. Adjusting rods are provided on the upper pressure roller, the first lower tensioning roller, and the second lower tensioning roller. The lifting power assembly is installed on the upper cover plate. The output end of the lifting power assembly is connected to the vertical adjusting screw drive. The laser receiver A and the laser receiver B are installed on the tensioning wheel sliding frame.

[0018] Furthermore, the lifting power assembly includes a motor, a drive wheel is drivenly connected to the output shaft of the motor, and a driven wheel is also provided. The driven wheel is drivenly connected to the vertical adjustment screw, and the drive wheel and the driven wheel are drivenly connected by a belt.

[0019] Furthermore, the powertrain is also equipped with a belt tension adjustment device.

[0020] A method for measuring and evaluating the elongation of an escalator drive chain includes the following steps: Step 1, Measurement and Setup: A tensioning and straightening mechanism is set in the non-meshing area of ​​the drive chain to form a stable tensioned straight measurement section locally. Along the chain movement direction, two laser beam detection sections are set sequentially on the tensioned straight measurement section, denoted as detection section A and detection section B, respectively. Detection section A consists of laser emitter A and laser receiver A, and detection section B consists of laser emitter B and laser receiver B. The laser emitter and laser receiver are respectively arranged on both sides of the drive chain to form a detection beam that passes through the chain roller, the projection area of ​​the chain pin, and the edge feature area of ​​the chain plate. The laser receiver A and laser receiver B are mounted on the tensioning wheel sliding frame to keep the relative positions of the detection section A and the detection section B stable. Step 2, Calibration of the reference distance S1 between the two test sections: Step 2.1: Laser receiver A and laser receiver B are installed on the tension wheel sliding frame to ensure that the two beams are parallel to each other and pass perpendicularly through the direction of chain movement; Step 2.3: Measure the actual distance between the center lines of the two laser beams using a calibrated steel ruler, vernier caliper, depth gauge, or gauge block, and record it as S1; Step 2.4: Input S1 into the control and display unit as the system length calibration value; Step 2.5: Perform zero-point correction on the response delays of laser receiver A and laser receiver B; if the response delay of laser receiver A is δ... A The response delay of laser receiver B is δ B The corrected real time difference for the same link passing through sections A and B is: ; Step 3, Measurement of the actual elongation of the drive chain: Step 3.1, Establish a complete measurement cycle A unique identification link is selected on the entire drive chain as the measurement starting point. When the starting link passes through the detection section A for the first time, it is recorded as the measurement start time t0. When the same starting link passes through the detection section A for the second time after running one revolution with the drive chain, it is recorded as the measurement end time t1. To ensure data integrity, the acquisition does not stop immediately when the reference starting link passes through the detection section A for the second time, but continues until the reference starting link passes through the detection section B. Step 3.2, Collection of natural events of the chain segment: When the chain is running at a low speed during maintenance, the chain rollers, chain pins, and edge features of the chain plates pass through detection section A and detection section B in sequence, forming a continuous natural occlusion pulse. To reduce the errors caused by beam width, threshold drift, and edge jitter, the control and display unit uses the center time of each pulse as the corresponding event time. Let the pulse entry and exit times of the natural event of the i-th link at the detection section A be respectively... and ,but:

[0021] Similarly, at the detection section B:

[0022] Step 3.3, Local velocity: Let t be the time when the i-th natural link event passes through detection section A and detection section B, respectively. A,i and t B,i Then the local average velocity near the i-th natural event is:

[0023] in, v i The measured speed of the chain body within the tensioned straight measurement section is a localized speed. Step 3.4, Internal reconstruction of the actual pitch of a single segment: Reconstruct the actual pitch of a single segment between adjacent natural events, assuming that two adjacent natural events pass through the detection section. A The times are respectively t A,i and t A,i+1 Then the first i actual pitch p i Represented as:

[0024] In engineering practice, it is not necessary to explicitly output the pitch of each link. p i The discrete approximation is as follows:

[0025] Step 3.5, Construct a fixed-section array: Let n consecutive intervals be taken as a fixed measurement group, then the length of the j-th group is denoted as: ; Step 3.6, processing of tail groups Let the total number of links in the chain be N, and the size of the fixed measurement group be n, then:

[0026] Where q is the number of complete fixed measurement groups, r is the remainder, and 0 ≤ r < n; When r=0, the total length of the entire chain is:

[0027] When r≠0, the last segment of the chain with fewer than a fixed number of nodes is defined as the tail remainder, and its length is:

[0028] At this point, the total length of the entire drive train is: ; Step 3.7, Actual elongation and elongation rate of the entire drive chain: The standard pitch of the chain is p If 0, then the standard total length of the entire drive train is:

[0029] Therefore, the total elongation of the entire drive chain is:

[0030] The elongation of the drive chain is:

[0031] Step 4, Graded Evaluation: Step 4.1: Input the measured actual total length of the drive chain and the corresponding standard total length into the control and display unit, calculate the actual elongation ΔL of the drive chain, and on this basis, calculate the actual elongation rate ε of the drive chain, that is, the ratio of the elongation ΔL to the standard total length, and express it in percentage form. The elongation rate ε is used as the core criterion for graded evaluation to reflect the current overall degradation degree of the drive chain. Step 4.2: After obtaining the elongation rate ε, the control and display unit retrieves the preset graded threshold parameters A, B, and C; where C is the core scrapping threshold, used to correspond to the state where the drive chain reaches or exceeds the scrapping criterion; A and B are used as the attention threshold and warning threshold, respectively; at the same time, the control and display unit integrates a lightweight knowledge base composed of accident characteristics, maintenance records, historical measurement results, and trend analysis information to perform auxiliary correction and background interpretation on the single measurement result; During the grading and judgment process, the first step is to determine whether the elongation rate ε is greater than the threshold C. When ε>C, it indicates that the overall elongation of the drive chain has reached the limit level, and it is judged as an out-of-standard state. The corresponding output is a mandatory scrapping recommendation, and it is clearly required to stop the continued long-term use and replace the drive chain in time to avoid operational risks. When ε≤C, continue to determine whether ε is greater than the threshold B; if ε>B, it means that although the drive chain has not reached the scrapping condition, its degradation level is close to the failure boundary, and it is judged as a warning state. The corresponding output is the recent disposal strategy, including preparing spare parts in advance, formulating a replacement plan, strengthening retesting, and including it in short-cycle tracking management to prevent the chain from quickly crossing the scrapping threshold in subsequent service. When ε≤B, determine whether ε is greater than the threshold A. If ε>A, it indicates that the drive chain has accumulated a certain degree of elongation, but the overall situation is still within a controllable range. It is judged as a state of concern, and corresponding operation and maintenance suggestions are output, including shortening the inspection cycle, increasing the frequency of on-site observation, strengthening the verification of lubrication and tension status, and judging the degradation rate in combination with historical trends. When ε≤A, the drive chain is determined to be in a normal state, indicating that the current elongation level of the drive chain is within the allowable range, the overall service status is relatively stable, and maintenance, lubrication and re-inspection can continue to be carried out according to the regular cycle; Step 4.3: To avoid making rigid judgments based solely on a single measurement result, multiple measurement results, the length distribution of segmented fixed segments, repeatability bias, and historical evolution trends are incorporated into the graded evaluation. Based on elongation as the primary criterion, a comprehensive evaluation is conducted by combining local abnormal distributions and historical change trends.

[0032] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention establishes a stable straight measurement segment in the non-meshing zone through a tensioning and straightening mechanism, transforming the measured chain segment from a state of suspension, bending, and local fluctuation to a measurement state with relatively clear force conditions and relatively stable geometry. The actual chain length change and chain posture change are no longer highly coupled, and the temporal and length relationships between detection sections A and B can be established on a more stable geometric basis. Therefore, this helps reduce random fluctuation errors introduced by suspension curvature, jitter, and local oscillation, and improves the consistency between repeated measurements. This improved consistency essentially corresponds to an improvement in measurement accuracy.

[0033] 2. This invention establishes detection sections A and B on the tensioned straight section and calibrates the reference distance S1 between the two sections. This bases subsequent length calculations on a unified spatial reference, rather than relying on empirical judgment or rough geometric estimation. Since S1 is a pre-calibrated known quantity, the chain length information is reconstructed from the chain body using the temporal information of the fixed detection sections. Therefore, there is a more direct correspondence between the measurement results and the actual length change of the drive chain body. The main effect of this is not only improved repeatability, but more importantly, reduced systematic deviation of the measurement results from the true value, thus improving measurement accuracy.

[0034] 3. This invention improves the representativeness and completeness of the whole-chain measurement results. In existing engineering practices, local sampling measurements are difficult to reflect the uneven wear and deformation along the entire chain length. While the results can serve as a local reference, they cannot represent the true service condition of the entire drive chain. To address this, this invention employs a method of full-cycle measurement, segmented reconstruction, and whole-chain accumulation. Instead of simply extrapolating the whole chain length from local averages, it obtains the actual total length based on information from the entire cycle, while retaining the length distribution of a fixed number of segments. This allows the total chain elongation to be quantified, and local abnormal sections are less likely to be masked by averaging, improving both the representativeness of the total length results and the ability to identify local abnormal wear.

[0035] 4. This invention not only provides the actual total length, elongation, and elongation rate of the drive chain, but also further combines scrapping thresholds, maintenance records, historical measurement results, and trend analysis to construct a safety evaluation model. This achieves a closed-loop transformation from measurement results to status classification and then to maintenance recommendations. Measurement data no longer remains at a single numerical value but can be directly converted into classification conclusions such as normal, attention, warning, and exceeding limits, further supporting maintenance strategy adjustments, retesting arrangements, and replacement decisions. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic diagram of the tensioning and straightening mechanism of the present invention; Figure 2 This is a schematic diagram illustrating the principle of the tensioning and straightening mechanism of the present invention; Figure 3 This is a schematic diagram illustrating the adjustment of the upper pressing roller, the first lower tensioning roller, and the second lower tensioning roller of the present invention. Figure 4 This is a schematic diagram of the measurement of the elongation of the escalator drive chain according to the present invention; Figure 5 This is a flowchart of the present invention; Figure 6 This is a schematic diagram of the graded evaluation process of the present invention; The diagram is labeled as follows: 1-Lifting power assembly, 101-Motor, 102-Driving wheel, 103-Driven wheel, 104-Belt, 105-Belt tension adjustment device, 2-Tensioning wheel sliding frame, 3-First lower tensioning roller, 4-Second lower tensioning roller, 5-Pressure wheel vertical slider, 6-Slider fixing bolt, 7-Pressure force adjustment module, 8-Upper pressure roller, 9-Pressure force sensor, 10-Fixed base plate, 11-Lower cover plate, 12-Main support frame, 13-Upper cover plate, 14-Lower support seat for lead screw, 15-Vertical adjustment lead screw, 16-Vertical slide rail, 17-Lead screw nut seat, 18-Tensioning wheel vertical slider, 19-Adjusting rod, 20-Laser receiver A, 21-Laser emitter A, 22-Laser receiver B, 23-Laser emitter B, 24-Control and display unit, 25-Drive chain. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0039] It should be noted that the labels and letters in the following figures represent similar items, therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0040] Refer to the instruction manual. Figure 1-6 ; An escalator drive chain elongation measuring device includes a main support frame 12, a vertical slide rail 16, a fixed base plate 10, an upper cover plate 13, an upper support seat for the lead screw, a lower cover plate 11, a lower support seat for the lead screw 14, a lifting power assembly 1, a belt tension adjusting device 105, an upper pressing roller 8 and its adjusting rod 19, a pressing force adjusting module 7, a vertical slider 5 for the pressing roller, a slider fixing bolt 6, a first lower tensioning roller 3 and its adjusting rod 19, a second lower tensioning roller 4 and its adjusting rod 19, a vertical slider 18 for the tensioning roller, a tensioning roller sliding frame 2, a vertical adjusting lead screw 15, a lead screw nut, a lead screw seat 17, a laser receiver A20, a laser emitter A21, a laser receiver B22, a laser emitter B23, and a control and display unit 24.

[0041] The main support frame 12, fixed base plate 10, upper cover plate 13, lower cover plate 11, upper support seat of the lead screw and lower support seat of the lead screw together constitute the foundation for the installation and bearing of the mechanism; the vertical slide rail 16, vertical adjusting lead screw 15, lead screw nut, lead screw seat 17, tension wheel sliding frame 2 and lifting power assembly 1 together complete the vertical displacement adjustment; the upper pressing roller 8 and adjusting rod 19, the first lower tension roller 3 and its adjusting rod 19 and the second lower tension roller 4 and its adjusting rod 19 together complete the chain contact type tensioning and straightening; the laser receiver A20, laser emitter A21, laser receiver B22 and laser emitter B23 are arranged in the straight measurement area after tensioning and straightening, used to establish the detection section A and the detection section B, and to calibrate the reference distance S1 between the two detection sections.

[0042] In this invention, the function of the tensioning and straightening mechanism is not to permanently adjust the structural tension of the drive chain 25, but to apply a local, controllable and recoverable tension to the section of the drive chain 25 to be measured under low-speed measurement conditions, so that the chain, which was originally in a natural suspension state, forms a stable straight measurement section, thereby providing consistent force and geometric conditions for subsequent length measurement.

[0043] Since the main drive chain 25 of the escalator is usually suspended inside the truss, it is easily affected by factors such as its own weight, local wear, uneven elongation of the chain links, installation posture, and fluctuations in measurement speed during actual operation. This manifests as local bending, vertical shaking, lateral swaying, and unstable force on the chain. If length measurement is performed directly under these natural conditions, the measurement results will simultaneously incorporate geometric deviations caused by changes in the actual chain length and posture, making it difficult to establish a comparable measurement benchmark. Therefore, the tensioning and straightening mechanism in this invention serves a dual function: pre-measurement processing and stable maintenance during the measurement process. On the one hand, it locally straightens and geometrically shapes the suspended chain segment using contact rollers; on the other hand, it maintains the tension of the chain segment as constant as possible during the measurement process through closed-loop force adjustment, thereby reducing the impact of chain shaking, suspension recovery, and local force fluctuations on the consistency of subsequent measurement results.

[0044] In practical use, first, place the tensioning and straightening mechanism on one side of the suspended section of the escalator drive chain 25, i.e., the non-meshing area of ​​the drive chain, and complete the overall installation and positioning through the main support frame 12, so that the working area of ​​the mechanism corresponds spatially with the chain segment to be tested. Then, loosen the slider fixing bolt 6 on the vertical slider 5 of the pressure roller, move the upper pressure roller 8 above the chain, and then make fine adjustments to the upper pressure roller 8 up and down and back and forth through the adjusting rod 19, so that it contacts the upper surface of the chain. After completing the initial positioning, tighten the slider fixing bolt 6 again to lock the position of the upper pressure roller 8.

[0045] Then, adjust the first lower tension roller 3 and its adjusting rod 19, and the second lower tension roller 4 and its adjusting rod 19 respectively, so that the two tension rollers and the upper pressure roller 8 form a corresponding three-point contact relationship within the same measuring working plane. Here, "same measuring working plane" refers to the three rollers acting together on the chain segment corresponding to the subsequent straight measurement window, not merely simple geometric coplanarity. Through this arrangement, the upper pressure roller 8 applies pressure to the chain, while the two lower tension rollers provide support and tension, thus forming a local chain straightening structure.

[0046] After the initial adjustment of the rollers is completed, the lifting power assembly 1 is started. The lifting power assembly 1 drives the vertical adjusting screw 15 to rotate via belt drive. The tensioning wheel sliding frame 2, which is installed on the screw nut and screw seat 17, moves up and down along the vertical slide rail 16, thereby driving the lower tensioning roller assembly to make vertical displacement. As the tensioning wheel sliding frame 2 moves upward, the lower tensioning roller gradually forms force contact with the chain, so that the chain section to be measured, which was originally in a suspended state, is gradually straightened. That is, by using the method of "upper pressing roller 8 pressing and lower double tensioning roller supporting and lifting", the chain is locally subjected to controllable force shaping, thereby transforming the naturally suspended chain section into a stable straight measurement section.

[0047] After the chain segment under test is tensioned and straightened, the positions of laser receiver A20, laser emitter A21, laser receiver B22, and laser emitter B23 are adjusted so that the laser emitter and its corresponding laser receiver are located on both sides of the chain, forming detection sections A and B on the tensioned straight section. The reference distance S1 between the two detection sections is then measured. S1 serves as the reference parameter for subsequent local velocity calculations and reconstruction of the entire chain length. It should be calibrated under stable conditions after the chain is tensioned and straightened to ensure that subsequent measurement conditions are consistent with the calibration conditions.

[0048] After completing the above adjustments, the escalator is run at its lowest speed, and the measurement program is initiated. During the measurement process, the chain passes through detection section A and detection section B sequentially. The control and display unit 24 collects the corresponding timing signals and executes the subsequent length reconstruction algorithm. Simultaneously, the tension adjustment module 7 monitors the local tension of the chain or its corresponding force parameters in real time. When the monitored tension is higher or lower than the preset range, the control and display unit 24 drives the lifting power assembly 1 to rotate the vertical adjusting screw 15, causing the tension wheel sliding frame 2 to move slightly up or down along the vertical slide rail 16. This changes the support height and tensioning effect of the lower tension roller on the chain, restoring the local tension of the chain to the preset range. Therefore, the chain maintains a relatively constant tension throughout the measurement process, reducing fluctuations in measurement conditions caused by chain vibration, sag recovery, or changes in local force.

[0049] By combining initial mechanical positioning, local three-point contact straightening, vertical displacement adjustment, and closed-loop tension holding, a stable, repeatable, and calibrable straight-line measurement window is established in the suspended section of the drive chain 25. This window serves two purposes: firstly, it supports the stable establishment of the reference distance S1 between the detection sections A and B; secondly, it provides a unified geometric and force basis for the length measurement and elongation calculation of the entire drive chain 25, thereby solving the problem that the drive chain 25 is difficult to directly use as a precise measurement object in its natural suspended state.

[0050] A method for measuring and evaluating the elongation of an escalator drive chain includes the following steps: Step 1, Measurement and Setup: A tensioning and straightening mechanism is set in the non-meshing area of ​​the drive chain to form a stable tensioned straight measurement section locally. Along the chain movement direction, two laser beam detection sections are set sequentially on the tensioned straight measurement section, denoted as detection section A and detection section B, respectively. Detection section A consists of laser emitter A and laser receiver A, and detection section B consists of laser emitter B and laser receiver B. The laser emitter and laser receiver are respectively arranged on both sides of the drive chain to form a detection beam that passes through the chain roller, the projection area of ​​the chain pin, and the edge feature area of ​​the chain plate. Laser receivers A and B are mounted on the tensioning wheel slide frame, ensuring a stable relative position between detection sections A and B. The tensioning and straightening mechanism establishes a stable measurement posture without altering the relative reference distance between detection sections A and B. When the tensioning wheel slide frame moves up and down to tension, detection sections A and B move synchronously with the entire tensioning wheel slide frame, maintaining a constant center distance.

[0051] Step 2, Calibration of the reference distance S1 between the two test sections: Step 2.1: Laser receiver A and laser receiver B are installed on the tension wheel sliding frame to ensure that the two beams are parallel to each other and pass perpendicularly through the direction of chain movement; Step 2.3: Measure the actual distance between the center lines of the two laser beams using a calibrated steel ruler, vernier caliper, depth gauge, or gauge block, and record it as S1; Step 2.4: Input S1 into the control and display unit as the system length calibration value; Step 2.5: Perform zero-point correction on the response delays of laser receiver A and laser receiver B; if the response delay of laser receiver A is δ... A The response delay of laser receiver B is δ B The corrected real time difference for the same link passing through sections A and B is: ; Step 3, Measurement of the actual elongation of the drive chain: Step 3.1, Establish a complete measurement cycle A unique link is selected as the measurement starting point on the entire drive chain. The measurement start time t0 is recorded when this starting link first passes through detection section A. The measurement end time t1 is recorded when the same starting link passes through detection section A for the second time after completing one revolution of the drive chain. Since periodic closure only indicates that the entire drive chain has completely passed through one measurement window, and does not directly equal the total chain length, to ensure the integrity of the last segment of data, data acquisition does not stop immediately when the reference starting link passes through detection section A for the second time, but continues until the reference starting link passes through detection section B. Step 3.2, Collection of natural events of the chain segment: When the chain is running at a low speed during maintenance, the chain rollers, chain pins, and edge features of the chain plates pass through detection section A and detection section B in sequence, forming a continuous natural occlusion pulse. In order to reduce the errors caused by beam width, threshold drift, and edge jitter, the control and display unit uses the center time of each pulse as the corresponding event time to improve timing stability. Let the pulse entry and exit times of the natural event of the i-th link at the detection section A be respectively... and ,but:

[0052] Similarly, at the detection section B:

[0053] Step 3.3, Local velocity: Let t be the time when the i-th natural link event passes through detection section A and detection section B, respectively. A,i and t B,i Then the local average velocity near the i-th natural event is:

[0054] in, v i It is the local measured speed of the chain body within the tensioned straight measurement section, independent of the sprocket speed, chain disk radius or sprocket meshing geometry; Step 3.4, Internal reconstruction of the actual pitch of a single segment: Reconstruct the actual pitch of a single segment between adjacent natural events, assuming that two adjacent natural events pass through the detection section. A The times are respectively t A,i and t A,i+1 Then the first i actual pitch p i Represented as:

[0055] In engineering practice, it is not necessary to explicitly output the pitch of each link. p i The discrete approximation is as follows:

[0056] Step 3.5, Construct a fixed-section array: Let n consecutive intervals be taken as a fixed measurement group, then the length of the j-th group is denoted as: ; Note: In actual measurements, n can take integer values ​​from 5 to 8. The fixed-section array serves as the output unit; it is not required that all links in this array be simultaneously located between detection sections A and B. Detection sections A and B provide a calibration basis for local velocities, while the length of the fixed-section array is essentially the cumulative value of the integration results of several individual sections.

[0057] Step 3.6, processing of tail groups Let the total number of links in the chain be N, and the size of the fixed measurement group be n, then:

[0058] Where q is the number of complete fixed measurement groups, r is the remainder, and 0 ≤ r < n; When r=0, the total length of the entire chain is:

[0059] When r≠0, the last segment of the chain with fewer than a fixed number of nodes is defined as the tail remainder, and its length is:

[0060] At this point, the total length of the entire drive train is: ; The remaining groups should not be discarded, nor should they be forcibly merged into the previous complete group. Instead, they should be calculated and accumulated independently.

[0061] Step 3.7, Actual elongation and elongation rate of the entire drive chain: The standard pitch of the chain is p If 0, then the standard total length of the entire drive train is:

[0062] Therefore, the total elongation of the entire drive chain is:

[0063] The elongation of the drive chain is:

[0064] Step 4, Graded Evaluation: Step 4.1: Input the measured actual total length of the drive chain and the corresponding standard total length into the control and display unit, calculate the actual elongation ΔL of the drive chain, and on this basis, calculate the actual elongation rate ε of the drive chain, that is, the ratio of the elongation ΔL to the standard total length, and express it in percentage form. The elongation rate ε is used as the core criterion for graded evaluation to reflect the current overall degradation degree of the drive chain. Step 4.2: After obtaining the elongation rate ε, the control and display unit retrieves the preset grading threshold parameters A, B, and C. Among them, C is the core scrapping threshold, preferably set to 3%, used to correspond to the state where the drive chain reaches or exceeds the scrapping criterion. A and B are the attention threshold and warning threshold, respectively, and their values ​​can be preset or adjusted according to equipment type, location type, service conditions, maintenance strategy, and historical statistical data. At the same time, the control and display unit integrates a lightweight knowledge base composed of accident characteristics, maintenance records, historical measurement results, and trend analysis information to assist in the correction and background interpretation of single measurement results, thereby improving the engineering applicability and rationality of the grading conclusion. During the grading and judgment process, the first step is to determine whether the elongation rate ε is greater than the threshold C. When ε>C, it indicates that the overall elongation of the drive chain has reached the limit level, and it is judged as an out-of-standard state. The corresponding output is a mandatory scrapping recommendation, and it is clearly required to stop the continued long-term use and replace the drive chain in time to avoid operational risks. When ε≤C, continue to determine whether ε is greater than the threshold B; if ε>B, it means that although the drive chain has not reached the scrapping condition, its degradation level is close to the failure boundary, and it is judged as a warning state. The corresponding output is the recent disposal strategy, including preparing spare parts in advance, formulating a replacement plan, strengthening retesting, and including it in short-cycle tracking management to prevent the chain from quickly crossing the scrapping threshold in subsequent service. When ε≤B, determine whether ε is greater than the threshold A. If ε>A, it indicates that the drive chain has accumulated a certain degree of elongation, but the overall situation is still within a controllable range. It is judged as a state of concern, and corresponding operation and maintenance suggestions are output, including shortening the inspection cycle, increasing the frequency of on-site observation, strengthening the verification of lubrication and tension status, and judging the degradation rate in combination with historical trends. When ε≤A, the drive chain is determined to be in a normal state, indicating that the current elongation level of the drive chain is within the allowable range, the overall service status is relatively stable, and maintenance, lubrication and re-inspection can continue to be carried out according to the regular cycle; Step 4.3, to avoid making rigid judgments based solely on a single measurement result, incorporates multiple measurement results, the length distribution of segmented fixed sections, repeatability deviations, and historical evolution trends into the grading evaluation. In other words, the grading evaluation is not based solely on a single elongation threshold for mechanical judgment, but rather uses elongation as the primary criterion, combined with local anomaly distributions and historical trends for a comprehensive evaluation. This approach maintains the intuitiveness and feasibility of the grading results while enhancing the evaluation conclusions' adaptability to complex working conditions and uneven wear states.

[0065] This achieves a complete closed loop consisting of "actual length measurement - elongation calculation - elongation rate determination - threshold grading - strategy output". The quantitative detection results of the drive chain can be directly converted into four states: normal, attention, warning, and exceeding the standard. These states correspond to disposal strategies such as routine maintenance, enhanced monitoring, early replacement preparation, and mandatory scrapping, respectively. This provides a scientific, clear, and easy-to-implement decision-making basis for the safety management of the escalator main drive chain.

[0066] In its implementation, this invention establishes a relatively constant and stable straight measurement segment in the non-meshing area of ​​the drive chain using a contact-type tensioning and straightening mechanism, thereby reducing the impact of curvature and fluctuations on the consistency of subsequent testing conditions. Based on the calibrated testing benchmark, length-related information within the complete measurement cycle of the drive chain is reconstructed and accumulated to obtain the actual total length, elongation, and elongation rate of the drive chain. Finally, combining the scrap threshold, inspection data, maintenance records, and historical change information, the drive chain status is graded as normal, under observation, warning, or exceeding limits, providing a quantitative basis for on-site inspection, status identification, and maintenance decisions. This effectively solves the problems of insufficient representativeness of local sampling in existing methods, the lack of quantitative inspection methods that can directly support the 3% elongation threshold determination on-site, and the difficulty in further converting measurement results into status evaluation and disposal criteria.

[0067] The above description constitutes an embodiment of the present invention. The foregoing descriptions are preferred embodiments of the present invention. Unless there is a clear contradiction or a prerequisite for a particular preferred embodiment, the preferred embodiments can be arbitrarily combined and used. The embodiments and specific parameters described are merely for clearly illustrating the verification process of the invention and are not intended to limit the scope of patent protection of the present invention. The scope of patent protection of the present invention is still determined by its claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention should also be included within the scope of protection of the present invention.

Claims

1. A device for measuring the elongation of an escalator drive chain, characterized in that, The system includes a tensioning and straightening mechanism, a laser receiver A (20), a laser emitter A (21), a laser receiver B (22), a laser emitter B (23), and a control and display unit (24). The tensioning and straightening mechanism is located in the non-engaging area of ​​the drive chain (25). The tensioning and straightening mechanism includes a support assembly and a lifting power assembly (1). A tensioning wheel sliding frame (2) that can move along the height direction of the support assembly is installed on the support assembly. First lower tensioning rollers are installed at both ends of the tensioning wheel sliding frame (2). 3) The second lower tensioning roller (4) is mounted on the support assembly above the tensioning roller sliding frame (2), and a vertical slider (5) of the pressure roller is movable along the height direction of the support assembly. A slider fixing bolt (6) for limiting the vertical slider (5) of the pressure roller is mounted on the vertical slider (5). A pressure force adjustment module (7) is also mounted on the vertical slider (5). An upper pressure roller (8) is mounted at the bottom of the pressure force adjustment module (7). The lifting power assembly (1) is used to drive The tensioning wheel sliding frame (2) moves along the height direction of the support assembly. The control and display unit (24) is electrically connected to the clamping force sensor (9) of the clamping force adjustment module (7), the drive end of the lifting power assembly (1), laser receiver A (20), laser emitter A (21), laser receiver B (22), and laser emitter B (23) respectively. The working ends of laser receiver A (20) and laser emitter A (21) are arranged opposite to each other and the working ends of laser receiver A (20) and laser emitter A (23) are respectively connected to the drive end of the lifting power assembly (1). 21) The laser receiver B (22) and laser emitter B (23) are located on the same straight line as the center of the first lower tension roller (3). The working ends of the laser receiver B (22) and laser emitter B (23) are arranged opposite each other and the center of the laser receiver B (22) and laser emitter B (23) is located on the same straight line as the center of the second lower tension roller (4). The laser receiver A (20) and laser receiver B (22) are located above the upper layer of the drive chain (25), and the laser emitter A (21) and laser emitter B (23) are located below the lower layer of the drive chain (25).

2. The escalator drive chain elongation measuring device according to claim 1, characterized in that, The support assembly includes a fixed base plate (10), on which a lower cover plate (11) is mounted. A main support frame (12) is mounted on the lower cover plate (11), and an upper cover plate (13) is mounted on the top of the main support frame (12). The main support frame (12) includes a left support and a right support symmetrically arranged, and a back support is connected between the left support and the right support. A screw lower support seat (14) is provided on the upper surface of the lower cover plate (11) between the left support and the right support. A screw upper support seat is provided on the lower surface of the cover plate (13) between the left and right supports. A vertical adjusting screw (15) is installed between the screw upper support seat and the screw lower support seat (14). Vertical slide rails (16) are installed on the front side of the left and right supports. A screw nut that can slide along the length of the vertical adjusting screw (15) is installed on the vertical adjusting screw (15). A screw nut seat (17) is connected to the screw nut. The screw nut seat (17) is connected to the tension wheel sliding frame (2). The tensioning wheel sliding frame (2) has a tensioning wheel vertical slider (18) mounted on the surface near the vertical slide rail (16). The tensioning wheel vertical slider (18) is locked inside the vertical slide rail (16) and can slide along the vertical slide rail (16). The first lower tensioning roller (3) and the second lower tensioning roller (4) are mounted at both ends of the tensioning wheel sliding frame (2) on the surface away from the vertical slide rail (16). The pressure wheel vertical slider (5) is locked on the vertical slide rail (16) of the left bracket and is located on the tensioning wheel vertical slide rail. Above the slider (18), the vertical slider (5) of the pressure wheel can slide along the vertical slide rail (16). The upper pressure roller (8), the first lower tension roller (3), and the second lower tension roller (4) are all equipped with adjustment rods (19). The lifting power assembly (1) is installed on the upper cover plate (13). The output end of the lifting power assembly (1) is connected to the vertical adjustment screw (15). The laser receiver A (20) and the laser receiver B (22) are installed on the tension wheel sliding frame (2).

3. The escalator drive chain elongation measuring device according to claim 2, characterized in that, The lifting power assembly (1) includes a motor (101), on which a drive wheel (102) is driven and connected, and a driven wheel (103) is also provided. The driven wheel (103) is driven and connected to a vertical adjustment screw (15), and the drive wheel (102) and the driven wheel (103) are driven and connected by a belt (104).

4. The escalator drive chain elongation measuring device according to claim 3, characterized in that, The lifting power assembly (1) is also equipped with a belt tension adjustment device (105).

5. A method for measuring and evaluating the elongation of an escalator drive chain according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1, Measurement and Setup: A tensioning and straightening mechanism is set in the non-meshing area of ​​the drive chain to form a stable tensioned straight measurement section locally. Along the chain movement direction, two laser beam detection sections are set sequentially on the tensioned straight measurement section, denoted as detection section A and detection section B, respectively. Detection section A consists of laser emitter A and laser receiver A, and detection section B consists of laser emitter B and laser receiver B. The laser emitter and laser receiver are respectively arranged on both sides of the drive chain to form a detection beam that passes through the chain roller, the projection area of ​​the chain pin, and the edge feature area of ​​the chain plate. The laser receiver A and laser receiver B are mounted on the tensioning wheel sliding frame to keep the relative positions of the detection section A and the detection section B stable. Step 2, Calibration of the reference distance S1 between the two test sections: Step 2.1: Laser receiver A and laser receiver B are installed on the tension wheel sliding frame to ensure that the two beams are parallel to each other and pass perpendicularly through the direction of chain movement; Step 2.3: Measure the actual distance between the center lines of the two laser beams using a calibrated steel ruler, vernier caliper, depth gauge, or gauge block, and record it as S1; Step 2.4: Input S1 into the control and display unit as the system length calibration value; Step 2.5: Perform zero-point correction on the response delays of laser receiver A and laser receiver B; if the response delay of laser receiver A is δ... A The response delay of laser receiver B is δ B The corrected real time difference for the same link passing through sections A and B is: ; Step 3, Measurement of the actual elongation of the drive chain: Step 3.1, Establish a complete measurement cycle A unique identification link is selected on the entire drive chain as the measurement starting point. When the starting link passes through the detection section A for the first time, it is recorded as the measurement start time t0. When the same starting link passes through the detection section A for the second time after running one revolution with the drive chain, it is recorded as the measurement end time t1. To ensure data integrity, the acquisition does not stop immediately when the starting link passes through the detection section A for the second time, but continues until the starting link passes through the detection section B. Step 3.2, Collection of natural events of the chain segment: When the chain is running at a low speed during maintenance, the chain rollers, chain pins, and edge features of the chain plates pass through detection section A and detection section B in sequence, forming a continuous natural occlusion pulse. To reduce the errors caused by beam width, threshold drift, and edge jitter, the control and display unit uses the center time of each pulse as the corresponding event time. Let the pulse entry and exit times of the natural event of the i-th link at the detection section A be respectively... and ,but: ; Similarly, at the detection section B: ; Step 3.3, Local velocity: Let t be the time when the i-th natural link event passes through detection section A and detection section B, respectively. A,i and t B,i Then the local average velocity near the i-th natural event is: ; in, v i The measured speed of the chain body within the tensioned straight measurement section is a localized speed. Step 3.4, Internal reconstruction of the actual pitch of a single segment: Reconstruct the actual pitch of a single segment between adjacent natural events, assuming that two adjacent natural events pass through the detection section. A The times are respectively t A,i and t A,i+1 Then the first i actual pitch p i Represented as: ; In engineering practice, it is not necessary to explicitly output the pitch of each link. p i The discrete approximation is as follows: ; Step 3.5, Construct a fixed-section array: Let n consecutive intervals be taken as a fixed measurement group, then the length of the j-th group is denoted as: ； Step 3.6, processing of tail groups Let the total number of links in the chain be N, and the size of the fixed measurement group be n, then: ; Where q is the number of complete fixed measurement groups, r is the remainder, and 0 ≤ r < n; When r=0, the total length of the entire chain is: ; When r≠0, the last segment of the chain with fewer than a fixed number of nodes is defined as the tail remainder, and its length is: ; At this point, the total length of the entire drive train is: ； Step 3.7, Actual elongation and elongation rate of the entire drive chain: The standard pitch of the chain is p If 0, then the standard total length of the entire drive train is: ; Therefore, the total elongation of the entire drive chain is: ; The elongation of the drive chain is: ； Step 4, Graded Evaluation: Step 4.1: Input the measured actual total length of the drive chain and the corresponding standard total length into the control and display unit, calculate the actual elongation ΔL of the drive chain, and on this basis, calculate the actual elongation rate ε of the drive chain, that is, the ratio of the elongation ΔL to the standard total length, and express it in percentage form. The elongation rate ε is used as the core criterion for graded evaluation to reflect the current overall degradation degree of the drive chain. Step 4.2: After obtaining the elongation rate ε, the control and display unit retrieves the preset graded threshold parameters A, B, and C; where C is the core scrapping threshold, used to correspond to the state where the drive chain reaches or exceeds the scrapping criterion; A and B are used as the attention threshold and warning threshold, respectively; at the same time, the control and display unit integrates a lightweight knowledge base composed of accident characteristics, maintenance records, historical measurement results, and trend analysis information to perform auxiliary correction and background interpretation on the single measurement result; During the grading and judgment process, the first step is to determine whether the elongation rate ε is greater than the threshold C. When ε>C, it indicates that the overall elongation of the drive chain has reached the limit level, and it is judged as an out-of-standard state. The corresponding output is a mandatory scrapping recommendation, and it is clearly required to stop the continued long-term use and replace the drive chain in time to avoid operational risks. When ε≤C, continue to determine whether ε is greater than the threshold B; if ε>B, it means that although the drive chain has not reached the scrapping condition, its degradation level is close to the failure boundary, and it is judged as a warning state. The corresponding output is the recent disposal strategy, including preparing spare parts in advance, formulating a replacement plan, strengthening retesting, and including it in short-cycle tracking management to prevent the chain from quickly crossing the scrapping threshold in subsequent service. When ε≤B, determine whether ε is greater than the threshold A. If ε>A, it indicates that the drive chain has accumulated a certain degree of elongation, but the overall situation is still within a controllable range. It is judged as a state of concern, and corresponding operation and maintenance suggestions are output, including shortening the inspection cycle, increasing the frequency of on-site observation, strengthening the verification of lubrication and tension status, and judging the degradation rate in combination with historical trends. When ε≤A, the drive chain is determined to be in a normal state, indicating that the current elongation level of the drive chain is within the allowable range, the overall service status is relatively stable, and maintenance, lubrication and re-inspection can continue to be carried out according to the regular cycle; Step 4.3: To avoid making rigid judgments based solely on a single measurement result, multiple measurement results, the length distribution of segmented fixed segments, repeatability bias, and historical evolution trends are incorporated into the graded evaluation. Based on elongation as the primary criterion, a comprehensive evaluation is conducted by combining local abnormal distributions and historical change trends.

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