Surface wear monitoring method and system for large shield machine cutting tools

Abstract

The present invention relates to the technical field of shield machine tool quality monitoring, and specifically to a surface wear monitoring method and system suitable for large shield machine tools. The blade width time series data of each rotation of the tool, the cutting gap time series data of each monitoring position, and the position coordinate time series data are obtained, wherein the cutting gap time series data reflects the thickness change of each position of the tool; since the tool will be affected by vibration during operation, the vibration displacement index is determined based on the cutting gap value and the blade width difference to reflect the influence of vibration on the longitudinal displacement of the tool; the cutting gap time series data is adjusted and corrected by using the synchronous changes and numerical characteristics of the blade center axis vibration displacement index and the vibration displacement index of each monitoring position, as well as the position offset; finally, the wear is monitored by using the numerical difference at the same moment in the corrected cutting gap time series data of different circles of the tool. The present invention takes vibration interference into consideration and improves the accuracy and effectiveness of the wear monitoring results.

Description

Technical Field

[0001] The present invention relates to the technical field of shield machine cutter quality monitoring, and in particular to a surface wear monitoring method and system suitable for large shield machine cutters. Background Art

[0002] During tunneling operations, the cutter, a key component that directly interacts with the rock and soil, has a significant impact on the machine's efficiency and tunneling quality. Under prolonged, high-intensity operation, cutters gradually lose their cutting capacity due to wear. This not only reduces tunneling efficiency but can also damage the cutter itself and other machine components. Therefore, real-time monitoring of cutter wear is essential.

[0003] When monitoring tool wear, existing technologies usually analyze the change in the distance between the tool blade and the sensor to determine whether the tool blade is worn or damaged. However, during the tunneling operation of a shield machine, the tool will vibrate when it directly acts on media such as rock and soil. This vibration will cause the tool to shake slightly and move. Therefore, if the impact of vibration on wear monitoring is ignored, the credibility of the final monitoring results will be greatly reduced. Summary of the Invention

[0004] In order to solve the technical problem that vibration occurs when the cutter directly acts on rock and soil and other media during the tunneling operation of a shield machine, and the vibration phenomenon causes slight shaking and displacement of the cutter, if the influence of vibration on wear monitoring is ignored, the credibility of the final monitoring result will be greatly reduced, the purpose of the present invention is to provide a surface wear monitoring method and system for large shield machine cutters. The technical solution adopted is as follows:

[0005] A surface wear monitoring method for large shield machine cutters, comprising:

[0006] Obtaining blade width time series data, cutting gap time series data, and position coordinate time series data at each monitoring position of the tool during each rotation, wherein the monitoring position includes the blade center axis position and the edge positions on both sides of the blade;

[0007] At each monitoring position, based on the changes in the cutting gap value and the differences in the blade width value at different times, the vibration displacement index at each monitoring position at each time is determined;

[0008] Based on the numerical characteristics of the vibration displacement index at the center axis of the blade at each moment, the synchronous changes and numerical characteristics of the vibration displacement index at all monitoring positions at each moment, and the offset of the position coordinates of the monitoring positions over time, the corrected cutting gap time series data at the center axis of the blade in each rotation of the tool is obtained;

[0009] The tool wear is monitored based on the difference between the corrected cutting gap values ​​at the blade center axis position under different rotations of the tool.

[0010] Furthermore, the method for obtaining the vibration displacement index includes:

[0011] In the cutting gap time series data at each monitoring position, the absolute value of the difference between the cutting gap values ​​at each two adjacent moments is used as the first vibration displacement factor at the previous moment in the time series between the two adjacent moments;

[0012] In the blade width time series data, the absolute value of the difference between the blade width values ​​at each two adjacent moments is used as the second vibration displacement factor at the previous moment in the time series between the two adjacent moments;

[0013] The product of the first vibration displacement factor at each monitoring position at each moment and the second vibration displacement factor corresponding to each moment is normalized to a value, which is used as the vibration displacement index at each monitoring position at each moment.

[0014] Furthermore, the method for obtaining the corrected cutting gap time series data includes:

[0015] Based on the vibration displacement index at the center axis of the blade at each moment, all moments are divided into normal vibration moments and abnormal vibration moments;

[0016] The cutting gap value at the center axis of the blade at each normal vibration moment is used as the corrected cutting gap value;

[0017] At the moment of abnormal vibration, analyzing the synchronous changes between the vibration displacement indicators at all monitoring positions to determine the first offset factor;

[0018] At the moment of abnormal vibration, the position coordinates of all monitoring positions are analyzed for their offset over time, and a second offset factor is determined;

[0019] The product of the first offset factor and the second offset factor corresponding to each abnormal vibration moment is negatively correlated and normalized to obtain the value as the vibration change unidirectional indicator of the tool at each abnormal vibration moment;

[0020] When the vibration change same-direction index corresponding to a certain abnormal vibration moment is greater than the preset change same-direction threshold, the cutting gap value at the blade center axis position at the normal vibration moment with the smallest time interval with the abnormal vibration moment is used as the corrected cutting gap value at the blade center axis position at the abnormal vibration moment;

[0021] When the vibration change same-direction index corresponding to a certain abnormal vibration moment is less than or equal to the preset change same-direction threshold, the cutting gap value at the blade center axis position at the abnormal vibration moment is used as the corrected cutting gap value;

[0022] The corrected cutting gap values ​​at the blade center axis position at all normal vibration moments and abnormal vibration moments during each rotation of the tool are arranged in time sequence, thereby obtaining the corrected cutting gap time sequence data.

[0023] Furthermore, based on the vibration displacement index at the blade center axis position at each moment, all moments are divided into normal vibration moments and abnormal vibration moments, including:

[0024] When the vibration displacement index at the blade center axis position at a certain moment is less than the preset displacement threshold, the moment is considered to be a normal vibration moment;

[0025] When the vibration displacement index at the blade center axis position at a certain moment is greater than or equal to a preset displacement threshold, the moment is considered to be an abnormal vibration moment.

[0026] Furthermore, the method for obtaining the first offset factor includes:

[0027] At each abnormal vibration moment, the difference between the vibration displacement index at the center axis of the blade and the vibration displacement index at the edge of each side of the blade is used as the axis deviation coefficient corresponding to the edge of each side of the blade;

[0028] The absolute value of the difference between the axis deviation coefficients corresponding to the edge positions on both sides of the blade is used as the first offset factor at each abnormal vibration moment.

[0029] Furthermore, the method for obtaining the second offset factor includes:

[0030] At each monitoring position, the position coordinates at each abnormal vibration moment are taken as the end point, and the position at the moment before each abnormal vibration moment is taken as the starting point, to obtain the offset vector at each monitoring position at each abnormal vibration moment;

[0031] At each abnormal vibration moment, the cosine similarity between the offset vector corresponding to the blade center axis position and the offset vector corresponding to the edge position on each side of the blade is used as the offset similarity value corresponding to the edge position on each side of the blade;

[0032] The absolute value of the difference between the corresponding offset similarity values ​​at the edge positions on both sides of the blade edge is used as the second offset factor at each abnormal vibration moment.

[0033] Furthermore, the tool wear monitoring based on the difference between the corrected cutting gap values ​​at the blade center axis position under different rotations of the tool includes:

[0034] In the time series data of the corrected cutting gap at the blade center axis position under two adjacent rotations of the tool, the absolute value of the difference between the corrected cutting gap values ​​at the same moment is used as the blade thickness change value at each moment;

[0035] Based on the fluctuation of the blade thickness change value at all times, the wear degree of the tool under two adjacent rotations is determined;

[0036] When the wear degree value is greater than or equal to the preset wear threshold, a wear warning is required; when the wear degree value is less than the preset wear threshold, a wear warning is not required.

[0037] Furthermore, the method for obtaining the wear degree value includes:

[0038] The standard deviation of the blade thickness variation at all moments is normalized and used as the discrete parameter;

[0039] When the discrete parameter is greater than or equal to a preset discrete threshold, the value after normalizing the maximum blade thickness change value at all moments is used as the wear degree value of the tool;

[0040] When the discrete parameter is less than a preset discrete threshold, the value obtained by normalizing the average of the blade thickness change values ​​at all moments is used as the wear degree value of the tool.

[0041] Furthermore, the value range of the preset discrete threshold is (0.6, 1).

[0042] A surface wear monitoring system for large shield machine cutting tools includes a processor and a memory. The memory stores at least one instruction, at least one program, a code set, or an instruction set. When the at least one instruction, at least one program, a code set, or an instruction set is loaded and executed by the processor, the at least one instruction, at least one program, a code set, or an instruction set implements the steps of a surface wear monitoring method for large shield machine cutting tools.

[0043] The present invention has the following beneficial effects:

[0044] First, the blade width time series data, cutting gap time series data, and position coordinate time series data of each monitoring position are obtained for each rotation of the tool. The cutting gap time series data specifically refers to the distance time series data between each monitoring position and the sensor, which can be used to reflect the change in tool thickness. Given that the shield machine tool is in a rotating state during operation and generates vibration when in contact with the rock and soil medium, a vibration displacement index is determined at each monitoring position based on the change in cutting gap value and the difference in blade width value to preliminarily reflect the impact of vibration on the longitudinal displacement of the tool. When the tool is not worn, when the tool is affected by vibration, the lateral displacement of the tool will cause the displacement of all monitoring positions to be isotropic. Therefore, based on the numerical characteristics of the vibration displacement index at the blade center axis position, the synchronous changes and numerical characteristics of the vibration displacement index at all monitoring positions, and the position offset of the monitoring positions, the cutting gap time series data at the blade center axis position of the tool for each rotation of the tool is adjusted and corrected to obtain the corrected cutting gap time series data. This correction process further reduces the impact of vibration interference on subsequent wear monitoring results and improves the accuracy and availability of the data. When a tool wears, the corrected cutting gap value at the same moment will change at different rotations. Therefore, the present invention monitors tool wear based on the difference in corrected cutting gap values ​​at different rotations. In summary, the present invention takes into account the interference of vibrations to the tool during shield machine operation on wear monitoring, which can effectively improve the accuracy of the final wear monitoring results. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 A flow chart of a method for monitoring surface wear of cutting tools of a large shield machine provided by one embodiment of the present invention;

[0047] Figure 2 A schematic diagram of three monitoring positions on a tool provided by one embodiment of the present invention;

[0048] Figure 3 A flowchart of a method for obtaining timing data of a corrected cutting gap provided by one embodiment of the present invention;

[0049] Figure 4 A flow chart of wear monitoring provided by one embodiment of the present invention;

[0050] Figure 5 A system block diagram of a surface wear monitoring system for large shield machine cutters provided by one embodiment of the present invention;

[0051] Figure 6 A schematic diagram of the system structure of a surface wear monitoring system for large shield machine cutting tools provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0052] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail a surface wear monitoring method and system for large shield machine cutters, including its specific implementation, structure, features, and effectiveness. In the following description, references to different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0053] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0054] The following describes in detail a specific solution of a surface wear monitoring method and system for cutting tools of a large shield machine provided by the present invention with reference to the accompanying drawings.

[0055] See also Figure 1 , which shows a method flow chart of a surface wear monitoring method for a large shield machine tool provided by one embodiment of the present invention, the method comprising the following steps:

[0056] Step S1: Obtaining blade width time series data, cutting gap time series data and position coordinate time series data at each monitoring position of the tool during each rotation. The monitoring positions include the blade center axis position and the edge positions on both sides of the blade.

[0057] During tunnel boring machine operation, the cutter comes into direct contact with the rock and soil, cutting through it. Therefore, the cutter must possess sufficient strength and wear resistance to ensure stable cutting performance during the long, high-intensity tunneling process. With the development of sensor technology, various high-precision sensors are widely used to monitor cutter wear. These sensors can capture tool operating data, thereby reflecting the wear condition of the tool surface.

[0058] Specifically, a lidar sensor can be embedded in each slot where the tool is installed on the shield machine cutterhead, and the monitoring range should ensure that it can cover the width of the tool. It can obtain the distance parameters between the tool and the lidar sensor during the rotation process, as well as the position coordinate data of each position when the tool passes through the sensor coverage range during the rotation process; the laser wavelength of the lidar sensor can be set to 1550nm, and the sampling time interval can be set to 1s. At this time, at each moment, the lidar sensor can obtain the position coordinate data of multiple positions on the width of the tool within the monitoring range and the distance parameters between the tool and the lidar sensor.

[0059] Since the tool is affected by vibrations when in contact with the rock and soil medium during operation, causing the tool to vibrate or shift slightly, in an embodiment of the present invention, it is necessary to correct the data changes caused by the vibration phenomenon. Therefore, the focus is mainly on the data changes at the center axis position of the blade and the data changes at the edge positions on both sides of the blade. Therefore, the center axis position of the blade and the edge positions on both sides of the blade are used as monitoring positions. Among them, the center axis position of the blade is the most prominent compared to the entire blade of the tool, so the distance between it and the laser radar sensor will be the closest. Therefore, among the distance parameters of multiple positions obtained by the laser radar sensor at each moment, the minimum value is used as the cutting gap value at the center axis position of the blade, and the position coordinates of the center axis position of the blade can be obtained at the same time; the edge positions on both sides of the blade should be the positions corresponding to the maximum distance parameters on each side of the minimum distance parameter. In this way, the cutting gap value and position coordinates at the edge positions on both sides of the blade can be obtained, and the Euclidean distance between the position coordinates of the edge positions on both sides of the blade is used as the blade width, so that the blade width timing data of the tool under each rotation, the cutting gap timing data at each monitoring position, and the position coordinate timing data can be obtained. Please refer to Figure 2 , which shows a schematic diagram of three monitoring positions on the tool.

[0060] It should be noted that the sampling time interval of the lidar sensor can be adjusted according to the specific implementation scenario, but it should be much shorter than the time it takes for the tool to rotate one circle, to ensure that sufficient length of time series data can be obtained with each rotation of the tool.

[0061] Step S2: At each monitoring position, based on the changes in the cutting gap value and the differences in the blade width values ​​at different moments, determine the vibration displacement index at each monitoring position at each moment.

[0062] Given that wear analysis primarily focuses on the blade's center axis, a significant change in the cutting gap at the blade's center axis indicates significant blade wear. However, during tool wear monitoring, the tool and cutterhead are both rotating, and the tool collides with the rock wall within the soil layer during excavation, generating vibration. This can lead to deviations in the data monitored by the laser radar sensor, affecting the accuracy of subsequent tool surface wear monitoring. Vibration can cause the tool to shift laterally and longitudinally, and longitudinal displacement can be characterized based on changes in the distance between the tool and the laser radar sensor and blade width at each monitoring location. Therefore, to obtain actual monitoring data on the tool surface during excavation, in an embodiment of the present invention, at each monitoring location, the vibration displacement index at each monitoring location is first determined based on the changes in the cutting gap and blade width at different times, to preliminarily reflect the impact of vibration on the tool's longitudinal displacement.

[0063] Preferably, in one embodiment of the present invention, the method for obtaining the vibration displacement index includes:

[0064] Vibration will cause the distance between the tool and the lidar sensor to change at different times, and this change can be reflected by the changes in the cutting gap value and the blade width value. Therefore, in the cutting gap time series data at each monitoring position, the absolute value of the difference between the cutting gap values ​​at each two adjacent moments is used as the first vibration displacement factor at the previous moment in the time series between the two adjacent moments. The larger the first vibration displacement factor, the more obvious the longitudinal displacement of the tool between the two moments.

[0065] Similarly, in the blade width time series data, the absolute value of the difference between the blade width values ​​at each two adjacent moments is used as the second vibration displacement factor at the previous moment in the time series between the two adjacent moments. Under normal circumstances, the blade width value of the tool itself should be uniform, so when the second vibration displacement factor is larger, it can be regarded as being affected by vibration, and a more obvious longitudinal displacement has occurred, resulting in changes in the blade width value at different moments.

[0066] It should be noted that, in the embodiment of the present invention, the first vibration displacement factor at the last moment in the time sequence is set to be the same as the first vibration displacement factor at the adjacent previous moment; the same applies to the second vibration displacement factor.

[0067] Based on the above analysis, it can be seen that both the first vibration displacement factor and the second vibration displacement factor are positively correlated with the longitudinal displacement of the tool due to vibration. Therefore, the product of the first vibration displacement factor at each monitoring position at each moment and the corresponding second vibration displacement factor at each moment is normalized and used as the vibration displacement index at each monitoring position at each moment. At this time, the larger the vibration displacement index, the more significant longitudinal displacement of the tool at that monitoring position at that moment. Normalization is a technical means well known to those skilled in the art. The normalization function can be linear normalization or standard normalization, etc. The specific normalization method is not limited here.

[0068] Step S3: Based on the numerical characteristics of the vibration displacement index at the center axis position of the blade at each moment, the synchronous changes and numerical characteristics of the vibration displacement index at all monitoring positions at each moment, and the offset of the position coordinates of the monitoring positions over time, the corrected cutting gap timing data at the center axis position of the blade under each rotation of the tool is obtained.

[0069] Based on the above steps, the vibration displacement indicators of the three monitoring positions at each moment in the embodiment of the present invention can be obtained to reflect the influence of vibration on the longitudinal displacement of the tool. Then in this step, the influence of vibration on the lateral displacement of the tool is further analyzed, that is, the left and right offsets that the tool may produce. The tool is offset as a whole when it produces left and right offsets. Therefore, the offset of the position coordinates of the monitoring position over time can be used as an indicator for analyzing the influence of lateral displacement, and the vibration displacement indicators at each monitoring position should also have synchronous changes. Therefore, in this embodiment of the present invention, the moments can be distinguished first based on the numerical characteristics of the vibration displacement indicators at the blade center axis position at each moment, and then the cutting gap timing data at the blade center axis position of the tool is corrected according to the synchronous changes and numerical characteristics of the vibration displacement indicators at all monitoring positions, as well as the offset of the monitoring positions over time, to obtain the corrected cutting gap timing data, thereby more accurately reflecting the wear state of the blade part of the tool and providing data support for subsequent wear monitoring.

[0070] Preferably, in one embodiment of the present invention, the method for obtaining the corrected cutting gap time series data includes:

[0071] See also Figure 3 , which shows a flow chart of a method for obtaining timing data of a corrected cutting gap in one embodiment of the present invention, the method comprising the following steps:

[0072] Step S301: Based on the vibration displacement index at the blade center axis position at each moment, all moments are divided into normal vibration moments and abnormal vibration moments.

[0073] Based on the analysis in step S2, it can be seen that when the vibration displacement index is larger, it means that the tool has undergone a more obvious longitudinal displacement under the influence of vibration. Therefore, when the vibration displacement index at the center axis position of the blade at a certain moment is less than the preset displacement threshold, this moment is considered to be a normal vibration moment, that is, the influence of vibration is small and can be regarded as within the normal range.

[0074] On the contrary, when the vibration displacement index at the center axis position of the blade at a certain moment is greater than or equal to the preset displacement threshold, this moment is considered to be an abnormal vibration moment, that is, it is greatly affected by the vibration, which will have a greater impact on the subsequent wear monitoring and needs to be corrected.

[0075] It should be noted that the preset displacement threshold is 0.45, and the specific value can be adjusted according to the implementation scenario and is not limited here.

[0076] Step S302: taking the cutting gap value at the blade center axis position at each normal vibration moment as the corrected cutting gap value.

[0077] Under normal vibration moments, the vibration of the tool is within the expected range and is not believed to have a significant impact on subsequent wear monitoring. Therefore, in an embodiment of the present invention, the cutting gap value at the center axis position of the blade under each normal vibration moment can be directly used as the corrected cutting gap value.

[0078] Step S303: at the moment of abnormal vibration, analyzing the synchronous changes between the vibration displacement indicators at all monitoring positions to determine a first offset factor.

[0079] When the tool deviates to the left or right, the tool will have an overall deviation. If the blade is relatively intact and the wear is weak, the line will be relatively neat. The vibration displacement index at the center axis monitoring position and the vibration displacement index at the edge position on each side of the blade should change synchronously, that is, the degree of vibration influence should be relatively consistent.

[0080] Therefore, at each moment of abnormal vibration, the difference between the vibration displacement index at the center axis position of the blade and the vibration displacement index at the edge position on each side of the blade is used as the axis deviation coefficient corresponding to the edge position on each side of the blade. The axis deviation coefficient reflects the consistency between the degree of vibration influence at the edge position on each side of the blade and the degree of vibration influence at the center axis position of the blade, and the smaller the value, the more consistent it is.

[0081] Finally, the absolute value of the difference in the axis deviation coefficients corresponding to the edge positions on both sides of the blade is used as the first offset factor at each abnormal vibration moment. The larger the first offset factor, the greater the difference in the degree of synchronous change in the degree of vibration influence between the edge positions on both sides of the blade and the center axis position of the blade. The greater the deviation and the smaller the degree of change in the same direction, the higher the possibility of wear on the blade of the tool at the abnormal vibration moment.

[0082] Step S304: at the moment of abnormal vibration, analyzing the offset of the position coordinates of all monitoring positions over time to determine a second offset factor.

[0083] First, at each monitoring position, the position coordinates at each abnormal vibration moment are taken as the end point, and the position at the moment before each abnormal vibration moment is taken as the starting point, and the offset vector at each monitoring position at each abnormal vibration moment is obtained. The offset vector reflects the moving direction and distance of each monitoring position of the tool at each abnormal vibration moment.

[0084] Then, at each abnormal vibration moment, the cosine similarity between the offset vector corresponding to the center axis position of the blade and the offset vector corresponding to the edge position on each side of the blade is used as the offset similarity value corresponding to the edge position on each side of the blade. The larger the offset similarity value, the higher the degree of consistency between the lateral displacement offset of the center axis of the blade and the lateral displacement offset at the edge position on each side of the blade.

[0085] Finally, the absolute value of the difference between the corresponding offset similarity values ​​at the edge positions on both sides of the blade edge is used as the second offset factor at each abnormal vibration moment. The larger the second offset factor, the greater the difference in the offset consistency between the edge positions on both sides of the blade and the blade center axis position under the influence of vibration. The smaller the degree of unidirectional change, the higher the possibility of wear on the blade part of the tool at the abnormal vibration moment.

[0086] Step S305: The first offset factor and the second offset factor corresponding to each abnormal vibration moment are integrated to determine the vibration change same direction index of the tool at each abnormal vibration moment.

[0087] Based on the above steps, the first offset factor and the second offset factor at the center axis position of the blade at each abnormal vibration moment can be obtained. They can be used as a measure of the same-direction change of the lateral displacement of the monitoring position of the tool under the influence of vibration. The first offset factor and the second offset factor are both negatively correlated with the degree of the same-direction change. Therefore, the product of the first offset factor and the second offset factor corresponding to each abnormal vibration moment is negatively correlated and normalized to achieve logical relationship correction, thereby obtaining the same-direction index of the vibration change of the tool at each abnormal vibration moment. At this time, the larger the same-direction index of the vibration change, the smaller the wear of the tool at the abnormal vibration moment, and the data offset generated by the tool is caused by vibration, not by tool damage or wear. The negative correlation mapping and normalization here can be performed using the formula exp(-x), where exp() represents an exponential function with the natural constant e as the base, and x represents the independent variable.

[0088] Step S306: Correcting the cutting gap value at the blade center axis position at the abnormal vibration moment based on the vibration change same direction index corresponding to the abnormal vibration moment, thereby obtaining corrected cutting gap time series data at the blade center axis position.

[0089] Based on the above analysis, it can be seen that when the vibration change same-direction index corresponding to a certain abnormal vibration moment is larger, it means that the data offset of the tool at the abnormal vibration moment is caused by vibration. Therefore, when the vibration change same-direction index corresponding to a certain abnormal vibration moment is greater than the preset change same-direction threshold, the cutting gap value at the center axis position of the blade at the normal vibration moment with the smallest time interval with the abnormal vibration moment will be used as the corrected cutting gap value at the center axis position of the blade at the abnormal vibration moment.

[0090] On the contrary, the smaller the vibration change same-direction index corresponding to a certain abnormal vibration moment is, the more likely it is that the data offset of the tool at the abnormal vibration moment is caused by real tool damage or wear. Therefore, when the vibration change same-direction index corresponding to a certain abnormal vibration moment is less than or equal to the preset change same-direction threshold, the cutting gap value at the blade center axis position at the abnormal vibration moment is used as the corrected cutting gap value to retain the data of real tool wear or tool damage.

[0091] Finally, the corrected cutting gap values ​​at the blade center axis position at all normal vibration moments and abnormal vibration moments during each rotation of the tool are arranged in time sequence to obtain corrected cutting gap time series data.

[0092] It should be noted that the preset change in the same direction threshold is 0.7, and the specific value can be adjusted according to the implementation scenario and is not limited here.

[0093] At this point, the cutting gap value at the monitoring position of the blade center axis under tool rotation can be corrected for vibration effects, and the corrected cutting gap timing data can be obtained that can truly represent the distance between the blade center axis position and the laser sensor at each moment.

[0094] Step S4: Based on the difference between the corrected cutting gap values ​​at the blade center axis position under different rotations of the tool, the tool wear is monitored.

[0095] Based on the above steps, the real data of the tool surface after correction can be obtained. During use, the tool will collide and grind media such as rock and soil, causing the cutting edge of the tool surface to gradually wear out or even become damaged. In an embodiment of the present invention, after obtaining the corrected cutting gap timing data of the tool under each rotation, given that in the corrected cutting gap timing data under different numbers of rotations, the corresponding points or positions on the tool at the same moment (specifically, the moments with the same sequence number in the timing, such as the first moment in the timing data of the first circle and the first moment in the timing data of the second circle are the same moment) should be the same, so by comparing the differences between the corrected cutting gap values ​​at the blade center axis position under different rotations of the tool, the wear state of the tool blade can be analyzed, thereby monitoring the wear of the tool.

[0096] Preferably, in one embodiment of the present invention, the tool wear is monitored based on the difference between the corrected cutting gap values ​​at the blade center axis position under different rotations of the tool, including:

[0097] See also Figure 4 , which shows a flow chart of wear monitoring in one embodiment of the present invention, specifically including the following steps:

[0098] Step S401: Analyze the difference between the corrected cutting gap values ​​when the blade center axis position is at the same moment in two adjacent rotations of the tool to obtain the blade thickness change value at each moment.

[0099] In the time series data of the corrected cutting gap at the center axis position of the blade under two adjacent rotations of the tool, the absolute value of the difference between the corrected cutting gap values ​​at the same moment is used as the blade thickness change value at each moment. The larger the blade thickness change value, the more serious the wear of the tool at the corresponding point or position at that moment under two adjacent rotations.

[0100] Step S402: Based on the fluctuation of the blade thickness change value at all times, determine the wear degree value of the tool in two adjacent rotations.

[0101] The standard deviation of the blade thickness change values ​​at all times is normalized and used as the discrete parameter. The larger the discrete parameter, the more obvious the discreteness of the blade thickness change values ​​at different times, that is, the greater the fluctuation of the blade thickness, which means that different degrees of wear have occurred in multiple places.

[0102] When the discrete parameter is greater than or equal to a preset discrete threshold, the maximum blade thickness change value at all times is normalized to the value obtained by normalizing it, and the tool wear value is used. When the discrete parameter is less than the preset discrete threshold, indicating that the blade thickness change value is relatively stable, the tool wear value is then normalized to the mean of the blade thickness change values ​​at all times. Normalization is a technique well known to those skilled in the art, and the normalization function can be linear normalization or standard normalization, etc. The specific normalization method is not limited here.

[0103] It should be noted that the preset discrete threshold is set to 0.65, and the specific value can be adjusted according to the implementation scenario and is not limited here.

[0104] Step S403: monitoring the wear of the tool based on the wear degree values ​​of the tool during two adjacent rotations.

[0105] Based on the above analysis, the wear degree value of the tool under two adjacent rotations can be obtained. Therefore, when the wear degree value is greater than or equal to the preset wear threshold, it is considered that the wear situation is relatively serious, and a wear warning is required to remind construction personnel to repair or replace the tool in time. When the wear degree value is less than the preset wear threshold, no wear warning is required.

[0106] It should be noted that the preset wear threshold in the embodiment of the present invention has a value range of (0.6, 1), which is set to 0.7 here. The specific value can be adjusted according to the implementation scenario and is not limited here.

[0107] In summary, first, the blade width time series data, cutting gap time series data of each monitoring position, and position coordinate time series data of the tool are obtained for each rotation of the tool. The cutting gap time series data specifically refers to the distance time series data between each monitoring position and the sensor, which can be used to reflect the thickness change of the tool. Given that the tool of the shield machine is in a rotating state during operation and generates vibration when in contact with the rock and soil medium, a vibration displacement index is determined at each monitoring position based on the change in the cutting gap value and the difference in the blade width value to preliminarily reflect the impact of vibration on the longitudinal displacement of the tool. When the tool is not worn, when the tool is affected by vibration, the lateral displacement of the tool will cause the displacement of all monitoring positions to be isotropic. Therefore, based on the numerical characteristics of the vibration displacement index at the blade center axis position, the synchronous changes and numerical characteristics of the vibration displacement index at all monitoring positions, and the position offset of the monitoring position, the cutting gap time series data at the blade center axis position of the tool for each rotation of the tool is adjusted and corrected to obtain the corrected cutting gap time series data. This correction process further reduces the impact of vibration interference on subsequent wear monitoring results and improves the accuracy and availability of the data. When a tool wears, the corrected cutting gap value at the same moment will change with different rotations. Therefore, the present invention monitors tool wear based on the differences in corrected cutting gap values ​​at different rotations. This embodiment of the present invention takes into account the interference of tool vibration during shield machine operation on wear monitoring, effectively improving the accuracy of the final wear monitoring results.

[0108] See also Figure 5 , which shows a system block diagram of a surface wear monitoring system for a large shield machine tool provided in one embodiment of the present invention, including a data acquisition module 501, used to implement step S1 in the above method embodiment; a vibration analysis module 502, used to implement step S2 in the above method embodiment; a data correction module 503, used to implement step S3 in the above method embodiment; and a wear monitoring module 504, used to implement step S4 in the above method embodiment.

[0109] It should be noted that the system provided in the above embodiment is merely exemplified by the division of the aforementioned functional modules. In actual applications, the aforementioned functions can be assigned to different functional modules as needed, i.e., the internal structure of the computer device can be divided into different functional modules to complete all or part of the functions described above. Furthermore, the surface wear monitoring system for large shield machine cutting tools and the surface wear monitoring method for large shield machine cutting tools provided in the above embodiment are based on the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0110] See also Figure 6 , which shows a system structure diagram of a surface wear monitoring system for large shield machine tools provided by an embodiment of the present invention, including a processor 600, a memory 601, a bus 602 and a communication interface 603, wherein the processor 600, the communication interface 603 and the memory 601 are connected via the bus 602; wherein the memory 601 may include a high-speed random access memory, the bus 602 may be an ISA bus, a PCI bus or an EISA bus, etc., and the processor 600 may be an integrated circuit chip with signal processing capabilities; the memory 601 stores at least one instruction, at least one program, a code set or an instruction set, and when the at least one instruction, at least one program, a code set or an instruction set is loaded and executed by the processor, the steps in a surface wear monitoring method for large shield machine tools are implemented.

[0111] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0112] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

Claims

1. A method for monitoring surface wear of cutting tools of large shield machines, characterized in that: The method comprises: Obtaining blade width time series data, cutting gap time series data, and position coordinate time series data at each monitoring position of the tool during each rotation, wherein the monitoring position includes the blade center axis position and the edge positions on both sides of the blade; At each monitoring position, based on the changes in the cutting gap value and the differences in the blade width value at different times, the vibration displacement index at each monitoring position at each time is determined; Based on the numerical characteristics of the vibration displacement index at the center axis of the blade at each moment, the synchronous changes and numerical characteristics of the vibration displacement index at all monitoring positions at each moment, and the offset of the position coordinates of the monitoring positions over time, the corrected cutting gap time series data at the center axis of the blade in each rotation of the tool is obtained; The tool wear is monitored based on the difference between the corrected cutting gap values ​​at the blade center axis position under different rotations of the tool; The method for obtaining the vibration displacement index includes: In the cutting gap time series data at each monitoring position, the absolute value of the difference between the cutting gap values ​​at each two adjacent moments is used as the first vibration displacement factor at the previous moment in the time series between the two adjacent moments; In the blade width time series data, the absolute value of the difference between the blade width values ​​at each two adjacent moments is used as the second vibration displacement factor at the previous moment in the time series between the two adjacent moments; The product of the first vibration displacement factor at each monitoring position at each moment and the second vibration displacement factor corresponding to each moment is normalized to a value, which is used as the vibration displacement index at each monitoring position at each moment.

2. A surface wear monitoring method for large shield machine cutting tools according to claim 1, characterized in that: The method for obtaining the modified cutting gap time series data includes: Based on the vibration displacement index at the center axis of the blade at each moment, all moments are divided into normal vibration moments and abnormal vibration moments; The cutting gap value at the center axis of the blade at each normal vibration moment is used as the corrected cutting gap value; At the moment of abnormal vibration, analyzing the synchronous changes between the vibration displacement indicators at all monitoring positions to determine the first offset factor; At the moment of abnormal vibration, the position coordinates of all monitoring positions are analyzed for their offset over time, and a second offset factor is determined; The product of the first offset factor and the second offset factor corresponding to each abnormal vibration moment is negatively correlated and normalized to obtain the value as the vibration change unidirectional indicator of the tool at each abnormal vibration moment; When the vibration change same-direction index corresponding to a certain abnormal vibration moment is greater than the preset change same-direction threshold, the cutting gap value at the blade center axis position at the normal vibration moment with the smallest time interval with the abnormal vibration moment is used as the corrected cutting gap value at the blade center axis position at the abnormal vibration moment; When the vibration change same-direction index corresponding to a certain abnormal vibration moment is less than or equal to the preset change same-direction threshold, the cutting gap value at the blade center axis position at the abnormal vibration moment is used as the corrected cutting gap value; The corrected cutting gap values ​​at the blade center axis position at all normal vibration moments and abnormal vibration moments during each rotation of the tool are arranged in time sequence, thereby obtaining the corrected cutting gap time sequence data.

3. A surface wear monitoring method for large shield machine cutting tools according to claim 2, characterized in that: Based on the vibration displacement index at the blade center axis position at each moment, all moments are divided into normal vibration moments and abnormal vibration moments, including: When the vibration displacement index at the blade center axis position at a certain moment is less than the preset displacement threshold, the moment is considered to be a normal vibration moment; When the vibration displacement index at the blade center axis position at a certain moment is greater than or equal to a preset displacement threshold, the moment is considered to be an abnormal vibration moment.

4. The surface wear monitoring method for large shield machine cutting tools according to claim 2, characterized in that: The method for obtaining the first offset factor includes: At each abnormal vibration moment, the difference between the vibration displacement index at the center axis of the blade and the vibration displacement index at the edge of each side of the blade is used as the axis deviation coefficient corresponding to the edge of each side of the blade; The absolute value of the difference between the axis deviation coefficients corresponding to the edge positions on both sides of the blade is used as the first offset factor at each abnormal vibration moment.

5. The surface wear monitoring method for large shield machine cutting tools according to claim 2 is characterized in that: The method for obtaining the second offset factor includes: At each monitoring position, the position coordinates at each abnormal vibration moment are taken as the end point, and the position at the moment before each abnormal vibration moment is taken as the starting point, to obtain the offset vector at each monitoring position at each abnormal vibration moment; At each abnormal vibration moment, the cosine similarity between the offset vector corresponding to the blade center axis position and the offset vector corresponding to the edge position on each side of the blade is used as the offset similarity value corresponding to the edge position on each side of the blade; The absolute value of the difference between the corresponding offset similarity values ​​at the edge positions on both sides of the blade edge is used as the second offset factor at each abnormal vibration moment.

6. The surface wear monitoring method for large shield machine cutting tools according to claim 1, characterized in that: The tool wear monitoring based on the difference between the corrected cutting gap values ​​at the blade center axis position under different rotations of the tool includes: In the time series data of the corrected cutting gap at the blade center axis position under two adjacent rotations of the tool, the absolute value of the difference between the corrected cutting gap values ​​at the same moment is used as the blade thickness change value at each moment; Based on the fluctuation of the blade thickness change value at all times, the wear degree of the tool under two adjacent rotations is determined; When the wear degree value is greater than or equal to the preset wear threshold, a wear warning is required; when the wear degree value is less than the preset wear threshold, a wear warning is not required.

7. The surface wear monitoring method for large shield machine cutting tools according to claim 6, characterized in that: The method for obtaining the wear degree value includes: The standard deviation of the blade thickness variation at all moments is normalized and used as the discrete parameter; When the discrete parameter is greater than or equal to a preset discrete threshold, the value after normalizing the maximum blade thickness change value at all moments is used as the wear degree value of the tool; When the discrete parameter is less than a preset discrete threshold, the value obtained by normalizing the average of the blade thickness change values ​​at all moments is used as the wear degree value of the tool.

8. The surface wear monitoring method for large shield machine cutting tools according to claim 7, characterized in that: The value range of the preset discrete threshold is (0.6, 1).

9. A surface wear monitoring system for large shield machine cutters, characterized in that: The invention comprises a processor and a memory, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and when the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor, the steps of a surface wear monitoring method for a large shield machine tool as described in any one of claims 1 to 8 are implemented.

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