CN112902821B - Method for measuring lay length on line and evaluating health state of steel wire rope according to lay length - Google Patents

Method for measuring lay length on line and evaluating health state of steel wire rope according to lay length Download PDF

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CN112902821B
CN112902821B CN202110022383.2A CN202110022383A CN112902821B CN 112902821 B CN112902821 B CN 112902821B CN 202110022383 A CN202110022383 A CN 202110022383A CN 112902821 B CN112902821 B CN 112902821B
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steel wire
wire rope
lay length
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length
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CN112902821A (en
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刘志亮
周建国
左明健
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University of Electronic Science and Technology of China
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/14—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring distance or clearance between spaced objects or spaced apertures
    • G01B7/15—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring distance or clearance between spaced objects or spaced apertures being regularly spaced
    • D—TEXTILES; PAPER
    • D07—ROPES; CABLES OTHER THAN ELECTRIC
    • D07B—ROPES OR CABLES IN GENERAL
    • D07B7/00—Details of, or auxiliary devices incorporated in, rope- or cable-making machines; Auxiliary apparatus associated with such machines
    • D07B7/02—Machine details; Auxiliary devices
    • D07B7/022—Measuring or adjusting the lay or torque in the rope
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
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    • G06F17/14—Fourier, Walsh or analogous domain transformations, e.g. Laplace, Hilbert, Karhunen-Loeve, transforms
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    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/04—Ageing analysis or optimisation against ageing

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Abstract

The invention discloses a method for measuring the lay length on line and evaluating the health state of a steel wire rope according to the lay length, which comprises the steps of firstly installing a rotary encoder and initializing, then collecting magnetic leakage signals of the steel wire rope for multiple times, obtaining the lay length function of the steel wire rope in a self-checking mode and an evaluation mode through the magnetic leakage signals, completing the on-line measurement of the lay length of the steel wire rope, finally calculating the characteristic value of the change of the lay length function, and evaluating the current health state of the steel wire rope according to the characteristic value, thereby monitoring the change condition of the lay length of the steel wire rope on line and improving the use safety level of the steel wire rope.

Description

Method for measuring lay length on line and evaluating health state of steel wire rope according to lay length
Technical Field
The invention belongs to the technical field of wire rope lay length measurement, and particularly relates to a method for measuring the lay length on line and evaluating the health state of a wire rope according to the lay length.
Background
The lay length is an important process parameter for manufacturing the steel wire rope and is also an important process index and detection index of the steel wire rope. When the steel wire rope is manufactured, the take-up speed is unstable, the early twist and the lay length are not uniform, and the twist and twist reduction phenomenon, lantern shape, kink, strand loosening, abrasion, corrosion, deformation and other damages are caused by the rotation of a suspended heavy object in the using process, so that the lay length of different parts of the steel wire rope can be changed. The uneven lay length of the steel wire rope and the deviation of the designed lay length can cause the uneven distribution of the stress load of the steel wire rope, and the different bearing tension of each strand in the rope can degrade the performance of the steel wire rope, greatly shorten the residual service life of the steel wire rope and cause the early scrapping of the steel wire rope.
At present, a unified standard for detecting the lay length of the steel wire rope is lacked in China. However, in the national standard of GBT 5972-. In which it is explicitly stated: the twist makes the lay length of the steel wire rope uneven, which causes excessive abrasion, and the strength of the steel wire rope is greatly reduced due to serious distortion. Provision is made for: the rejection criteria "kinked wire rope should be rejected immediately". These criteria define the necessity of detecting the lay length of the steel cord. However, the lay length is used as an important structural parameter of the steel wire rope, the change influence of the lay length is more than reflected in the deformation and damage of the steel wire rope, and the change influence influences the load distribution in the rope during bearing, so that the service life consumption of the steel wire rope is accelerated. However, the current steel wire rope nondestructive testing device mainly aims at the surface local damage and the metal cross section loss of the steel wire rope, and cannot simultaneously carry out lay length detection.
At present, the lay length of the steel wire rope is measured by manually using a vernier caliper, or the surface texture of the steel wire rope is rubbed by white paper, and the lay length measurement is realized by measuring the rubbed texture. The other means is to photograph the surface of the steel wire rope by using a camera and measure the lay length by using a machine vision-based algorithm.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for measuring the lay length on line and evaluating the health state of a steel wire rope according to the lay length, wherein the lay length of the steel wire rope is measured on line and automatically, and the health state of the steel wire rope is judged according to the lay length.
In order to achieve the above object, the present invention provides a method for measuring lay length on line and estimating the health status of a steel wire rope, comprising the steps of:
(1) installing a rotary encoder and initializing;
fixing the mounting position of the rotary encoder and setting the iso-spatial sampling rate f of the rotary encodersUnit sample points per meter (in/m);
(2) collecting a magnetic leakage signal of a steel wire rope self-inspection mode;
the steel wire rope is firstly operated for a whole round trip period, and M paths of Hall sensors are used for sampling at equal space sampling rate fsRepeatedly collecting leakage magnetic field signals of the self-checking mode of the space around the steel wire rope twice, and recording the leakage magnetic field signals
Figure GDA0003046152860000021
In the formula, the forward detection signal is represented as
Figure GDA0003046152860000022
The reverse detection signal is recorded as
Figure GDA0003046152860000023
Wherein M is 1,2, …, M represents the number of channels, N is 1,2, …, and N represents the length of the collected signal;
(3) estimating an effective lay length function according to a magnetic leakage signal of the steel wire rope self-inspection mode;
(3.1) pair
Figure GDA0003046152860000024
Removing trend;
using a multi-dimensional variational modal decomposition algorithm pair
Figure GDA0003046152860000025
Carrying out mode decomposition, wherein the dimension of the decomposition is the number of signal channels M, the number of the decomposed mode components is more than 4, removing the first term component after the decomposition is finished, summing other term components to obtain each path of trend-removed leakage magnetic signals, and recording the trend-removed leakage magnetic signals as the leakage magnetic signals
Figure GDA0003046152860000026
(3.2) obtaining an optimal selection strand wave signal;
computing
Figure GDA0003046152860000027
Each path of characteristic value of (1) comprises a root mean square value RMS, a Kutrosis and a peak factor C;
substituting the above characteristic values into a spike intensity characterization function f (RMS, C, Kutrosis) ═ a1×RMS+a2×C-a3X Kutrosis and solved, wherein, a1、a2、a3Obtaining the characteristic function value of the strand wave intensity of each XD (m, n) for a given coefficient, and then taking the signal of the channel where the maximum value of the characteristic function value of the strand wave intensity is as the optimal strand wave signal which is recorded as the optimal strand wave signal
Figure GDA0003046152860000028
(3.3) windowing the optimal selection strand wave signal;
to pair
Figure GDA0003046152860000029
Gaussian window function with sliding window
Figure GDA00030461528600000210
The window length being at least ten wave lengths, i.e.
Figure GDA0003046152860000031
In the formula, winL represents the window length, H represents the lay length of the steel wire rope, and B represents the number of strands of the steel wire rope;
(3.4), Fourier transform;
after being respectively windowed
Figure GDA0003046152860000032
Performing Fourier transform to obtain a time-frequency diagram of short-time Fourier transform, and recording the time-frequency diagram as
Figure GDA0003046152860000033
The size F × N, F is 1,2, …, F is the frequency dimension;
(3.5) calculating a redistributor;
using initial redistributors to divide the time-frequency diagrams
Figure GDA0003046152860000034
The first difference of the unwinding phase angle of each frequency vector, i.e.
Figure GDA0003046152860000035
Calculation of where unwarp [. cndot]Indicating uncoiling and indicating a phase angle;
iterative computation redistributor
Figure GDA0003046152860000036
J is 1,2.. J, and J is the number of compression times, and the redistributor is finally obtained after iteration is finished
Figure GDA0003046152860000037
(3.6) use of the redistributor pairs
Figure GDA0003046152860000038
Carrying out redistribution;
will be provided with
Figure GDA0003046152860000039
Is carried into the redistributor
Figure GDA00030461528600000310
To redistribute, i.e.
Figure GDA00030461528600000311
Thereby obtaining a high-resolution time-frequency diagram
Figure GDA00030461528600000312
(3.7) searching an instantaneous strand frequency function by using a greedy algorithm;
setting the length of a forward window and a backward window of a greedy algorithm for forward and backward windowing, and then setting a high-resolution time-frequency graph
Figure GDA00030461528600000313
Using a greedy algorithm of windowing from front to back, finding a continuously-changing instantaneous strand wave frequency function with the maximum amplitude value, and recording the function as
Figure GDA00030461528600000314
Solving instantaneous frequency function
Figure GDA00030461528600000315
First order difference of
Figure GDA00030461528600000316
If it is
Figure GDA00030461528600000317
g is a given frequency hopping threshold, thenAbandon the curve and do so in
Figure GDA00030461528600000318
Zero all data for this curve; then the window length in the forward and backward directions is doubled, and the greedy algorithm with the window length in the forward and backward directions is used again to search the instantaneous frequency function again
Figure GDA00030461528600000319
And analogizing until finding the curve meeting the condition;
(3.8) obtaining a lay length function of the steel wire rope in the forward detection process as
Figure GDA00030461528600000320
The unit meter per twist (m/twist), the number of strands B per twist (strand/twist), and the instantaneous strand wave frequency
Figure GDA00030461528600000321
Unit strand per meter (strand/m);
(3.9) similarly, according to the method in the steps (3.1) - (3.8), according to the leakage magnetic signal of the steel wire rope self-checking mode
Figure GDA0003046152860000041
Estimating the lay length function in reverse detection of steel wire ropes
Figure GDA0003046152860000042
(3.10) obtaining an effective lay length function H of a steel wire rope self-checking mode0(n)
Function of lay length
Figure GDA0003046152860000043
Is turned over left and right to obtain
Figure GDA0003046152860000044
n＝N,N-1,...1；
Will be provided with
Figure GDA0003046152860000045
And
Figure GDA0003046152860000046
making a difference, and then taking an absolute value to obtain
Figure GDA0003046152860000047
If epsilonH(n)＞d1In the formula, d1If the error threshold is given, the rotary encoder is not normally operated, the installation position of the rotary encoder is replaced, and the step (2) is returned; otherwise, the lay length function of the condition will be satisfied
Figure GDA0003046152860000048
Effective lay length function H recorded as steel wire rope self-checking mode0(n)；
(4) Acquiring a magnetic flux leakage signal of the steel wire rope in an evaluation mode;
after the steel wire rope works and uses for a period of time, acquiring a magnetic flux leakage signal in the steel wire rope evaluation mode according to the method in the step (2), and recording the magnetic flux leakage signal as a magnetic flux leakage signal
Figure GDA0003046152860000049
And
Figure GDA00030461528600000410
i is 1,2, …, I represents the number of detections during the use of the steel wire rope;
(5) calculating a lay length function of the steel wire rope in the evaluation mode;
according to the method in the step (3), magnetic flux leakage signals under the steel wire rope evaluation mode
Figure GDA00030461528600000411
And
Figure GDA00030461528600000412
estimating a lay length function H of the steel wire rope in an evaluation modei(n)；
(6) Calculating a characteristic value of the change of the lay length function;
(6.1) calculating a lay length function H in a self-checking mode0The characteristics of (n)Eigenvalues, including mean values
Figure GDA00030461528600000413
Variance (variance)
Figure GDA00030461528600000414
Kurtosis K0；
(6.2) calculating a lay length function H in an evaluation modeiCharacteristic values of (n), including mean values
Figure GDA00030461528600000415
Variance (variance)
Figure GDA00030461528600000416
Kurtosis Ki；
(6.3) for the steel wire rope lay length function H in the evaluation modei(n) plus a sliding window having a window length of at least an odd number of 2 beam lengths, i.e.
Figure GDA00030461528600000417
Obtaining a windowed lay length sequence
Figure GDA00030461528600000418
(6.4) respectively calculating the characteristic values of the health state of the windowed twist pitch sequence, wherein the characteristic values comprise a mean value, a standard deviation, a skewness and a kurtosis; thereby obtaining a windowed mean sequence
Figure GDA0003046152860000051
Windowed standard deviation sequence
Figure GDA0003046152860000052
Windowing skewness sequence
Figure GDA0003046152860000053
Windowed kurtosis sequence
Figure GDA0003046152860000054
(7) Evaluating the health state of the steel wire rope;
(7.1) if window mean sequence variation range
Figure GDA0003046152860000055
And the maximum value of the absolute value of the windowed skewness sequence
Figure GDA0003046152860000056
In the formula, epsilon0And ε1If the positive threshold value is given, the problem of twisting and untwisting of the steel wire rope is judged to be absent;
if windowed mean sequence
Figure GDA0003046152860000057
In which there are successive y elements
Figure GDA0003046152860000058
Or there are y consecutive elements in the windowed skewness sequence
Figure GDA0003046152860000059
In the formula, y is more than or equal to 3 multiplied by span, the twisting problem exists in the part of the steel wire rope;
if windowed mean sequence
Figure GDA00030461528600000510
In which there are successive y elements
Figure GDA00030461528600000511
Or there are y consecutive elements in the windowed skewness sequence
Figure GDA00030461528600000512
The part of the steel wire rope has the problem of untwisting;
(7.2) for initial detection lay length function H0(n) and in-use lay length function Hi(n) bringing them into the pitch ripple function
Figure GDA00030461528600000513
Solving if the pitch ripple function
Figure GDA00030461528600000514
In the formula, h is a given coefficient, the uneven load distribution degree exceeds the requirement when the steel wire rope is loaded, and the lay length distribution range exceeds the allowable range;
(7.3), four windowed eigenvalue sequences: mean value
Figure GDA00030461528600000515
Standard deviation of
Figure GDA00030461528600000516
Deflection degree
Figure GDA00030461528600000517
And kurtosis
Figure GDA00030461528600000518
If a certain characteristic value sequence has mutation, the pitch mutation function consisting of first-order difference of each characteristic value sequence
Figure GDA00030461528600000519
In the formula, epsilon2If the threshold value is given, judging that the lay length of the steel wire rope is locally abnormal and the performance degradation trend exists;
(7.4) measuring data H for different periods of time0(n) and Hi(n) average value, calculating the average elongation of the steel wire rope lay length
Figure GDA00030461528600000520
In the formula, LiThe length L of the steel wire rope is measured by a rotary encoder during the ith measurement0When the self-checking mode is adopted, the length of the steel wire rope is measured by a rotary encoder; if the elongation delta > epsilon3In the formula, epsilon3If the elongation rate is the threshold value of the elongation rate of the steel wire rope, the elongation rate of the steel wire rope is considered to exceed the requirement;
the invention aims to realize the following steps:
the invention relates to a method for measuring the lay length on line and evaluating the health state of a steel wire rope according to the lay length, which comprises the steps of firstly installing a rotary encoder and initializing, then collecting magnetic leakage signals of the steel wire rope for multiple times, obtaining the lay length function of the steel wire rope in a self-checking mode and an evaluation mode through the magnetic leakage signals, completing the on-line measurement of the lay length of the steel wire rope, finally calculating the characteristic value of the change of the lay length function, and evaluating the current health state of the steel wire rope according to the characteristic value, thereby monitoring the change condition of the lay length of the steel wire rope on line and improving the use safety level of the steel wire rope.
Meanwhile, the method for measuring the lay length on line and evaluating the health state of the steel wire rope further has the following beneficial effects:
(1) the invention can measure the lay length of the steel wire rope with high precision and no damage only by the self characteristic of the magnetic leakage signal, realizes the online measurement of the lay length of the steel wire rope, does not change the hardware structure of the traditional steel wire rope local defect detector, does not increase the cost, does not change the device and has the characteristic of low cost;
(2) the invention is not influenced by vibration noise between the steel wire rope and the detector and the defect noise of the steel wire rope, accurately measures the lay length of the steel wire rope, resists the strong interference of the defect noise and the vibration noise, and has good accuracy and stability;
(3) the method can automatically eliminate the unstable working data of the rotary encoder, can detect the abnormal and worsening trend of the lay length of each part of the steel wire rope, and simultaneously realizes the analysis and prejudgment of the local and global health states of the steel wire rope.
Drawings
FIG. 1 is a flow chart of a method of the present invention for measuring lay length on-line and assessing the health of a steel cord accordingly;
FIG. 2 is a schematic diagram of a steel wire rope magnetic flux leakage signal measuring device;
FIG. 3 is a schematic view of a rotary encoder installation;
FIG. 4 is a schematic diagram of a leakage flux signal of a steel wire rope;
fig. 5 is a schematic illustration of the lay length and strand spacing of a steel cord.
Detailed Description
The following description of the embodiments of the present invention is provided in order to better understand the present invention for those skilled in the art with reference to the accompanying drawings. It is to be expressly noted that in the following description, a detailed description of known functions and designs will be omitted when it may obscure the subject matter of the present invention.
Examples
Fig. 1 is a flow chart of a method for on-line measuring lay length and estimating the health of a steel wire rope according to the invention.
In this embodiment, as shown in fig. 2, the measuring device for estimating a wire breakage of a steel wire rope according to the present invention includes a magnetic loop composed of a permanent magnet, a magnetic yoke, and a steel wire rope, and M ═ 20 hall sensors located in the middle of a detecting instrument are annularly arranged around the axis of the steel wire rope at equal angles. As shown in fig. 1, the method for online measuring the lay length by the leakage magnetic signal and accordingly evaluating the health state of the steel wire rope comprises the following steps:
s1, installing a rotary encoder and initializing;
fixing the mounting position of the rotary encoder and setting the iso-spatial sampling rate f of the rotary encodersUnit sample points per meter (in/m);
in this embodiment, the installation position of the rotary encoder directly affects the accuracy of the isometric sampling pulse, as shown in fig. 3, under the condition that the conditions allow, the rotary encoder is preferentially installed on the steel wire rope head sheave, the main guide wheel or the fixed pulley, such as the installation positions 1 and 2 of the rotary encoder, so as to ensure the accuracy of the isometric sampling; if the conditions do not allow, the cable is installed on the steel cable, as in position 3. Attention must be paid to pure rolling between a friction wheel for driving the rotary encoder and a steel wire rope, and relative sliding is avoided, so that the accuracy of displacement information is guaranteed, and accurate equal-space sampling pulses are output.
S2, collecting a magnetic flux leakage signal of the steel wire rope self-checking mode;
the steel wire rope is firstly operated for a whole round trip period, and 20 paths of Hall sensors are used for sampling at an equal space sampling rate fsRepeatedly collecting leakage magnetic field signals of the self-checking mode of the space around the steel wire rope twice, and recording the leakage magnetic field signals
Figure GDA0003046152860000071
In the formula, the forward detection signal is represented as
Figure GDA0003046152860000072
The reverse detection signal is recorded as
Figure GDA0003046152860000073
Wherein M is 1,2, …, M represents the number of channels, N is 1,2, …, and N represents the length of the collected signal;
s3, estimating an effective lay length function according to the magnetic leakage signal of the steel wire rope self-checking mode;
s3.1, pair
Figure GDA0003046152860000074
Removing trend;
as shown in fig. 4, the data is the magnetic flux leakage signal data of a certain wire rope portion, wherein the ordinate is the output voltage of the hall sensor, and the abscissa is the detection distance. In the figure, one of 20 leakage magnetic signals has obvious nonlinear trend terms. Therefore, the magnetic leakage signal needs to be subjected to detrending processing, and the specific process is as follows:
using a multi-dimensional variational modal decomposition algorithm pair
Figure GDA0003046152860000075
Carrying out mode decomposition, wherein the dimension of the decomposition is the number of signal channels M, the number of the decomposed mode components is more than 4, removing the first term component after the decomposition is finished, summing other term components to obtain each path of trend-removed leakage magnetic signals, and recording the trend-removed leakage magnetic signals as the leakage magnetic signals
Figure GDA0003046152860000076
S3.2, obtaining an optimal selection strand wave signal;
computing
Figure GDA0003046152860000081
Each path of characteristic value of (1) comprises a root mean square value RMS, a Kutrosis and a peak factor C;
substituting the above characteristic values into a spike intensity characterization function f (RMS, C, Kutrosis) ═ a1×RMS+a2×C-a3XKutrosis and findsSolution of formula (I), wherein a1、a2、a3Obtaining the characteristic function value of the strand wave intensity of each XD (m, n) for a given coefficient, and then taking the signal of the channel where the maximum value of the characteristic function value of the strand wave intensity is as the optimal strand wave signal which is recorded as the optimal strand wave signal
Figure GDA0003046152860000082
S3.3, windowing the optimal selection strand wave signal;
to pair
Figure GDA0003046152860000083
Gaussian window function with sliding window
Figure GDA0003046152860000084
The window length being at least ten wave lengths, i.e.
Figure GDA0003046152860000085
In the formula, winL represents the window length, H represents the lay length of the steel wire rope, and B represents the number of strands of the steel wire rope;
s3.4, Fourier transform;
after being respectively windowed
Figure GDA0003046152860000086
Performing Fourier transform to obtain a time-frequency diagram of short-time Fourier transform, and recording the time-frequency diagram as
Figure GDA0003046152860000087
The size F × N, F is 1,2, …, F is the frequency dimension;
s3.5, calculating a redistributor;
using initial redistributors to divide the time-frequency diagrams
Figure GDA0003046152860000088
The first difference of the unwinding phase angle of each frequency vector, i.e.
Figure GDA0003046152860000089
Calculation of where unwarp [. cndot]Indicating unwindingThe angle represents the phase angle;
iterative computation redistributor
Figure GDA00030461528600000810
J is the number of compression, generally, J is 7, and the redistributor is finally obtained after the iteration is completed
Figure GDA00030461528600000811
S3.6, using heavy distributor pairs
Figure GDA00030461528600000812
Carrying out redistribution;
will be provided with
Figure GDA00030461528600000813
Is carried into the redistributor
Figure GDA00030461528600000814
To redistribute, i.e.
Figure GDA00030461528600000815
Thereby obtaining a high-resolution time-frequency diagram
Figure GDA00030461528600000816
S3.7, searching an instantaneous strand wave frequency function by using a greedy algorithm;
setting the length of a forward window and a backward window of a greedy algorithm for forward and backward windowing, and then setting a high-resolution time-frequency graph
Figure GDA0003046152860000091
Using a greedy algorithm of windowing from front to back, finding a continuously-changing instantaneous strand wave frequency function with the maximum amplitude value, and recording the function as
Figure GDA0003046152860000092
K is 1,2, …, M is the total number of instantaneous strand wave frequency functions; solving instantaneous frequency function
Figure GDA0003046152860000093
First order difference of
Figure GDA0003046152860000094
If it is
Figure GDA0003046152860000095
g is given frequency jump threshold, the curve is discarded and
Figure GDA0003046152860000096
zero all data for this curve; then the window length in the forward and backward directions is doubled, and the greedy algorithm with the window length in the forward and backward directions is used again to search the instantaneous frequency function again
Figure GDA0003046152860000097
And analogizing until finding the curve meeting the condition;
s3.8, obtaining a lay length function of the steel wire rope during forward detection as
Figure GDA0003046152860000098
The unit meter per twist (m/twist), the number of strands B per twist (strand/twist), and the instantaneous strand wave frequency
Figure GDA0003046152860000099
Unit strand per meter (strand/m);
in this embodiment, the strand pitch is the reciprocal of the instantaneous strand wave frequency, and the lay length is the product of the number of strands of the steel cord and the strand pitch, as shown in fig. 5, the number of strands of the steel cord is 6, and the lay length is 6 times the strand gap.
S3.9, and similarly, according to the method of the steps S3.1 to S3.8, according to the magnetic leakage signal of the steel wire rope self-checking mode
Figure GDA00030461528600000910
Estimating the lay length function in reverse detection of steel wire ropes
Figure GDA00030461528600000911
S3.10, obtaining an effective lay length function H of a steel wire rope self-checking mode0(n)；
Function of lay length
Figure GDA00030461528600000912
Is turned over left and right to obtain
Figure GDA00030461528600000913
n＝N,N-1,...1；
Will be provided with
Figure GDA00030461528600000914
And
Figure GDA00030461528600000915
making a difference, and then taking an absolute value to obtain
Figure GDA00030461528600000916
If epsilonH(n)＞d1In the formula, d1If the error threshold is set, indicating that the rotary encoder is not working properly, the mounting position of the rotary encoder is changed, and the process returns to step S2; otherwise, the lay length function of the condition will be satisfied
Figure GDA00030461528600000917
Effective lay length function H recorded as steel wire rope self-checking mode0(n)；
In the step, the same steel wire rope is repeatedly measured twice in a reciprocating way, the relative error of repeated measurement is judged, the accuracy and the stability of the measurement result are ensured, and the influence of improper operation or abnormal work of a rotary encoder is eliminated; in this step, it should be noted that the starting point and the ending point of the two measurements need to be the same.
S4, acquiring a steel wire rope magnetic flux leakage signal in an evaluation mode;
after the steel wire rope works and uses for a period of time, acquiring a magnetic flux leakage signal under the steel wire rope evaluation mode according to the method in the step S2, and recording the magnetic flux leakage signal as
Figure GDA00030461528600000918
And
Figure GDA00030461528600000919
i is 1,2, …, I represents the number of detections during the use of the steel wire rope;
in this embodiment, after the steel wire rope works for a period of time, two modes of off-line detection and on-line detection can be adopted, wherein the off-line detection comprises: setting fixed time periods according to related production safety requirements, running the steel wire rope to and fro in the whole process every fixed time period, and acquiring and recording whole-process data, such as a shutdown acquisition signal every week for fixed time; online detection: in the using process of the steel wire rope, whether the steel wire rope has the condition of the sudden change of the lay length or the uneven load distribution is judged according to the collected signals, if the health state of the steel wire rope is deteriorated, the detection times are increased, the detection time interval is reduced, or the magnetic flux leakage signals of the steel wire rope are continuously collected, and the lay length characteristics and the load distribution of the steel wire rope are detected on line and analyzed synchronously.
S5, calculating a lay length function of the steel wire rope in the evaluation mode;
according to the method of step S3, the leakage flux signal is evaluated according to the steel wire rope under the mode
Figure GDA0003046152860000101
And
Figure GDA0003046152860000102
estimating a lay length function H of the steel wire rope in an evaluation modei(n)；
S6, calculating a characteristic value of the change of the lay length function;
s6.1, calculating a lay length function H in a self-checking mode0Characteristic values of (n), including mean values
Figure GDA0003046152860000103
Variance (variance)
Figure GDA0003046152860000104
Kurtosis K0；
S6.2, calculating the lay length in the evaluation modeFunction HiCharacteristic values of (n), including mean values
Figure GDA0003046152860000105
Variance (variance)
Figure GDA0003046152860000106
Kurtosis Ki；
S6.3, evaluating the function H of the lay length of the steel wire rope in the modei(n) plus a sliding window having a window length of at least an odd number of 2 beam lengths, i.e.
Figure GDA0003046152860000107
Obtaining a windowed lay length sequence
Figure GDA0003046152860000108
S6.4, respectively calculating the characteristic values of the health state of the windowed twist pitch sequence, wherein the characteristic values comprise a mean value, a standard deviation, a skewness and a kurtosis; thereby obtaining a windowed mean sequence
Figure GDA0003046152860000109
Windowed standard deviation sequence
Figure GDA00030461528600001010
Windowing skewness sequence
Figure GDA00030461528600001011
Windowed kurtosis sequence
Figure GDA00030461528600001012
S7, evaluating the health state of the steel wire rope;
s7.1, if window mean sequence change interval range
Figure GDA00030461528600001013
And the maximum value of the absolute value of the windowed skewness sequence
Figure GDA00030461528600001014
In the formula, epsilon0And ε1If the positive threshold value is given, the problem of twisting and untwisting of the steel wire rope is judged to be absent;
if windowed mean sequence
Figure GDA0003046152860000111
In which there are successive y elements
Figure GDA0003046152860000112
Or there are y consecutive elements in the windowed skewness sequence
Figure GDA0003046152860000113
In the formula, y is more than or equal to 3 multiplied by span, the twisting problem exists in the part of the steel wire rope;
if windowed mean sequence
Figure GDA0003046152860000114
In which there are successive y elements
Figure GDA0003046152860000115
Or there are y consecutive elements in the windowed skewness sequence
Figure GDA0003046152860000116
The part of the steel wire rope has the problem of untwisting;
however, the higher the twisting and detwisting degree is, the more the steel wire rope lay length deviates from the normal designed lay length, the more uneven the distribution of the stress load of the steel wire rope is, and the accelerated consumption of the residual service life of the steel wire rope is;
s7.2, for initial detection of lay length function H0(n) and healthy State lay Length function Hi(n) bringing them into the pitch ripple function
Figure GDA0003046152860000117
Solving if the pitch ripple function
Figure GDA0003046152860000118
In the formula, h is a given coefficient, the distribution range of the lay length of the steel wire rope is considered to exceed the allowable rangeAllowable range, the uneven degree of load distribution exceeds the requirement when bearing;
the higher the fluctuation degree of the lay length of the steel wire rope, the more uneven the stress of each part of the steel wire rope during bearing, and the earlier scrapping of the steel wire rope can be caused;
s7.3, four windowing characteristic value sequences: mean value
Figure GDA0003046152860000119
Standard deviation of
Figure GDA00030461528600001110
Deflection degree
Figure GDA00030461528600001111
And kurtosis
Figure GDA00030461528600001112
If a certain characteristic value sequence has mutation, the pitch mutation function consisting of first-order difference of each characteristic value sequence
Figure GDA00030461528600001113
In the formula, epsilon2If the threshold value is given, judging that the lay length of the steel wire rope is locally abnormal and the performance degradation trend exists;
the local sudden change of the lay length of the steel wire rope means that the steel wire rope has local damage such as lantern shape, kink, strand looseness, corrosion, deformation and the like, and the specific damage type and the severity are judged according to the steel wire rope;
s7.4, detecting data H for different time periods0(n) and Hi(n) average value, calculating the average elongation of the steel wire rope lay length
Figure GDA00030461528600001114
In the formula, LiThe length L of the steel wire rope is measured by a rotary encoder during the ith detection0Detecting the length of the steel wire rope by a rotary encoder in a self-checking mode; if the elongation delta > epsilon3In the formula, epsilon3If the elongation rate is the threshold value of the elongation rate of the steel wire rope, the elongation rate of the steel wire rope is considered to exceed the requirement;
when the rotary encoder can output equal space pulse and detection distance information, the rotary encoder is preferentially used for measuring the length of the steel wire rope to calculate the average elongation rate of the lay length, and the average elongation rate of the lay length of the steel wire rope is checked with the average elongation rate of the lay length calculated by the mean value of the lay length function; and when the encoder is not selected to detect the distance information, calculating the average elongation of the lay length of the steel wire rope by using the mean value of the lay length function.
Although illustrative embodiments of the present invention have been described above to facilitate the understanding of the present invention by those skilled in the art, it should be understood that the present invention is not limited to the scope of the embodiments, and various changes may be made apparent to those skilled in the art as long as they are within the spirit and scope of the present invention as defined and defined by the appended claims, and all matters of the invention which utilize the inventive concepts are protected.

Claims (2)

1. A method for measuring the lay length on line and evaluating the health state of a steel wire rope according to the lay length on line is characterized by comprising the following steps:
(1) installing a rotary encoder and initializing;
fixing the mounting position of the rotary encoder and setting the iso-spatial sampling rate f of the rotary encodersUnit sampling point per meter (pieces/m);
(2) collecting a magnetic leakage signal of a steel wire rope self-inspection mode;
the steel wire rope is firstly operated for a whole round trip period, and M paths of Hall sensors are used for sampling at equal space sampling rate fsRepeatedly collecting leakage magnetic field signals of the self-checking mode of the space around the steel wire rope twice, and recording the leakage magnetic field signals
Figure FDA0003279731900000011
Figure FDA0003279731900000012
In the formula, the forward detection signal is represented as
Figure FDA0003279731900000013
Reverse direction detection signalNumber is marked as
Figure FDA0003279731900000014
Wherein M is 1,2, …, M represents the number of channels, N is 1,2, …, and N represents the length of the collected signal;
(3) estimating an effective lay length function according to a magnetic leakage signal of the steel wire rope self-inspection mode;
(3.1) pair
Figure FDA0003279731900000015
Removing trend;
using a multi-dimensional variational modal decomposition algorithm pair
Figure FDA0003279731900000016
Carrying out mode decomposition, wherein the dimension of the decomposition is the number of signal channels M, the number of the decomposed mode components is more than 4, removing the first term component after the decomposition is finished, summing other term components to obtain each path of trend-removed leakage magnetic signals, and recording the trend-removed leakage magnetic signals as the leakage magnetic signals
Figure FDA0003279731900000017
(3.2) obtaining an optimal selection strand wave signal;
computing
Figure FDA0003279731900000018
Each path of characteristic value of (1) comprises a root mean square value RMS, a Kutrosis and a peak factor C;
substituting the above characteristic values into a spike intensity characterization function f (RMS, C, Kutrosis) ═ a1×RMS+a2×C-a3X Kutrosis and solved, wherein, a1、a2、a3Obtaining the characteristic function value of the strand wave intensity of each XD (m, n) for a given coefficient, and then taking the signal of the channel where the maximum value of the characteristic function value of the strand wave intensity is as the optimal strand wave signal which is recorded as the optimal strand wave signal
Figure FDA0003279731900000019
(3.3) windowing the optimal selection strand wave signal;
to pair
Figure FDA00032797319000000110
Gaussian window function with sliding window
Figure FDA00032797319000000111
The window length being at least ten wave lengths, i.e.
Figure FDA00032797319000000112
In the formula, winL represents the window length, H represents the designed lay length of the steel wire rope, and B represents the number of strands of the steel wire rope;
(3.4), Fourier transform;
after being respectively windowed
Figure FDA0003279731900000021
Performing Fourier transform to obtain a time-frequency diagram of short-time Fourier transform, and recording the time-frequency diagram as
Figure FDA0003279731900000022
The size F × N, k is 1,2, …, F is the frequency dimension;
(3.5) calculating a redistributor;
using initial redistributors to divide the time-frequency diagrams
Figure FDA0003279731900000023
The first difference of the unwinding phase angle of each frequency vector, i.e.
Figure FDA0003279731900000024
Calculation of where unwarp [. cndot]Indicating uncoiling and indicating a phase angle;
iterative computation redistributor
Figure FDA0003279731900000025
J is 1,2.. J, J is the number of compression times, and is finally obtained after iteration is finishedHeavy distributor
Figure FDA0003279731900000026
(3.6) use of the redistributor pairs
Figure FDA0003279731900000027
Performing redistribution
Will be provided with
Figure FDA0003279731900000028
Is carried into the redistributor
Figure FDA0003279731900000029
To redistribute, i.e.
Figure FDA00032797319000000210
Thereby obtaining a high-resolution time-frequency diagram
Figure FDA00032797319000000211
(3.7) searching an instantaneous strand frequency function by using a greedy algorithm;
setting the length of a forward window and a backward window of a greedy algorithm for forward and backward windowing, and then setting a high-resolution time-frequency graph
Figure FDA00032797319000000212
Using a greedy algorithm of windowing from front to back, finding a continuously-changing instantaneous strand wave frequency function with the maximum amplitude value, and recording the function as
Figure FDA00032797319000000213
Solving instantaneous frequency function
Figure FDA00032797319000000214
First order difference of
Figure FDA00032797319000000215
If it is
Figure FDA00032797319000000216
g is given frequency jump threshold, then abandon
Figure FDA00032797319000000217
And is arranged at
Figure FDA00032797319000000218
To go up
Figure FDA00032797319000000219
All data of (1) are zeroed; then the window length in the forward and backward directions is doubled, and the greedy algorithm with the window length in the forward and backward directions is used again to search the instantaneous strand wave frequency function again
Figure FDA00032797319000000220
And analogizing until finding the instantaneous strand wave frequency function meeting the condition;
(3.8) obtaining a lay length function of the steel wire rope in the forward detection process as
Figure FDA00032797319000000221
The unit meter per twist (m/twist), the number of strands B per twist (strand/twist), and the instantaneous strand wave frequency
Figure FDA00032797319000000222
Unit strand per meter (strand/m);
(3.9) similarly, according to the method in the steps (3.1) - (3.8), according to the leakage magnetic signal of the steel wire rope self-checking mode
Figure FDA00032797319000000223
Estimating the lay length function in reverse detection of steel wire ropes
Figure FDA00032797319000000224
(3.10) obtaining effectiveness of self-checking mode of steel wire ropeLay length function H0(n)；
Function of lay length
Figure FDA0003279731900000031
Is turned over left and right to obtain
Figure FDA0003279731900000032
Will be provided with
Figure FDA0003279731900000033
And
Figure FDA0003279731900000034
making a difference, and then taking an absolute value to obtain
Figure FDA0003279731900000035
If epsilonH(n)＞d1In the formula, d1If the error threshold is given, the rotary encoder is not normally operated, the installation position of the rotary encoder is replaced, and the step (2) is returned; otherwise, the lay length function of the condition will be satisfied
Figure FDA0003279731900000036
Effective lay length function H recorded as steel wire rope self-checking mode0(n)；
(4) Acquiring a magnetic flux leakage signal of the steel wire rope in an evaluation mode;
after the steel wire rope works and uses for a period of time, acquiring a magnetic flux leakage signal in the steel wire rope evaluation mode according to the method in the step (2), and recording the magnetic flux leakage signal as a magnetic flux leakage signal
Figure FDA0003279731900000037
And
Figure FDA0003279731900000038
i represents the number of detections during the use of the steel wire rope;
(5) calculating a lay length function of the steel wire rope in the evaluation mode;
according to the method in the step (3), magnetic flux leakage signals under the steel wire rope evaluation mode
Figure FDA0003279731900000039
And
Figure FDA00032797319000000310
estimating a lay length function H of the steel wire rope in an evaluation modei(n)；
(6) Calculating a characteristic value of the change of the lay length function;
(6.1) calculating a lay length function H in a self-checking mode0Characteristic values of (n), including mean values
Figure FDA00032797319000000311
Variance (variance)
Figure FDA00032797319000000312
Kurtosis K0；
(6.2) calculating a lay length function H in an evaluation modeiCharacteristic values of (n), including mean values
Figure FDA00032797319000000313
Variance (variance)
Figure FDA00032797319000000314
Kurtosis Ki；
(6.3) for the steel wire rope lay length function H in the evaluation modei(n) plus a sliding window having a window length of at least an odd number of 2 beam lengths, i.e.
Figure FDA00032797319000000315
Obtaining a windowed lay length sequence
Figure FDA00032797319000000316
(6.4) calculating the sequence of the windowed lay lengths respectivelyHealth state characteristic values including mean, standard deviation, skewness and kurtosis; thereby obtaining a windowed mean sequence
Figure FDA00032797319000000317
Windowed standard deviation sequence
Figure FDA00032797319000000318
Windowing skewness sequence
Figure FDA00032797319000000319
Windowed kurtosis sequence
Figure FDA0003279731900000041
(7) Evaluating the health state of the steel wire rope;
(7.1) if window mean sequence variation range
Figure FDA0003279731900000042
And the maximum value of the absolute value of the windowed skewness sequence
Figure FDA0003279731900000043
In the formula, epsilon0And ε1If the positive threshold value is given, the problem of twisting and untwisting of the steel wire rope is judged to be absent;
if windowed mean sequence
Figure FDA0003279731900000044
In which there are successive y elements
Figure FDA0003279731900000045
Or there are y consecutive elements in the windowed skewness sequence
Figure FDA0003279731900000046
In the formula, if y is more than or equal to 3 multiplied by span, the twisting problem of the steel wire rope is judged;
if windowed mean sequence
Figure FDA0003279731900000047
In which there are successive y elements
Figure FDA0003279731900000048
Or there are y consecutive elements in the windowed skewness sequence
Figure FDA0003279731900000049
Judging that the steel wire rope has the untwisting problem;
(7.2) for initial detection lay length function H0(n) and in-use lay length function Hi(n) bringing them into the pitch ripple function
Figure FDA00032797319000000410
Solving if the pitch ripple function
Figure FDA00032797319000000411
In the formula, h is a given coefficient, the uneven load distribution degree exceeds the requirement when the steel wire rope is loaded, and the lay length distribution range exceeds the allowable range;
(7.3), four windowed eigenvalue sequences: mean value
Figure FDA00032797319000000412
Standard deviation of
Figure FDA00032797319000000413
Deflection degree
Figure FDA00032797319000000414
And kurtosis
Figure FDA00032797319000000415
If a certain characteristic value sequence has mutation, the pitch mutation function consisting of first-order difference of each characteristic value sequence
Figure FDA00032797319000000416
In the formula, epsilon2If the threshold value is given, judging that the lay length of the steel wire rope is locally abnormal and the performance degradation trend exists;
(7.4) detecting data H for different time periods0(n) and Hi(n) average value, calculating the average elongation of the steel wire rope lay length
Figure FDA00032797319000000417
In the formula, LiThe length L of the steel wire rope is measured by a rotary encoder during the ith measurement0The length of the steel wire rope is measured by a rotary encoder in a self-checking mode; if the elongation delta > epsilon3In the formula, epsilon3And if the elongation rate is the threshold value of the elongation rate of the steel wire rope, the elongation rate of the steel wire rope is considered to exceed the requirement.
2. A method of on-line measuring lay length and assessing the health of a steel cord as claimed in claim 1, wherein the rotary encoder mounting position priorities are in the order: the steel wire rope comprises a winding drum of the steel wire rope, a head sheave, a main guide wheel and the steel wire rope.
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