JP2024051417A - Wire rope diagnostic method, diagnostic system, and diagnostic program - Google Patents

Abstract

[Problem] To provide a wire rope diagnostic method, diagnostic system, and diagnostic program for diagnosing the time to replace a wire rope by taking into consideration the fluctuation in tension acting on the wire rope caused by the swing of a hanging body. [Solution] In a wire rope diagnostic method for diagnosing the time to replace a wire rope 20 passing through sheaves 21-25, a large number of wire sections 26 divided at equal intervals are set on the wire rope 20, and time series data 31 in which the position (lt, ht) of the hanging body for each first period t and the tension wt acting on the wire rope 20 are arranged in time series is processed by a calculation device 4 to calculate the minute damage degree Dj caused in the passing section 27, and the time to replace the wire rope 20 is diagnosed based on the accumulated damage degree Ds obtained by accumulating the calculated minute damage degrees Dj for each wire section 26. [Selected Figure] Figure 1

Description

The present invention relates to a method, system, and program for diagnosing a wire rope, and more specifically, to a method, system, and program for diagnosing the time to replace the wire rope by taking into account fluctuations in tension acting on the wire rope.

Devices have been proposed to diagnose wire ropes in cranes, elevators, etc. (see, for example, Patent Documents 1 and 2). The invention described in Patent Document 1 calculates the tension generated in the main rope from the acceleration obtained from the car speed and the load mass. The invention described in Patent Document 2 uses Nieman's empirical formula as a formula for estimating the lifespan of the wire rope, and finds the tensile stress acting on the wire rope from the load.

However, even if the load of the suspended object hoisted by the wire rope and the acceleration when the suspended object is moved are constant, if the suspended object sways, the tension acting on the wire rope will fluctuate due to the swaying. Therefore, there is room for improvement in accurately diagnosing the time to replace the wire rope by taking into account the fluctuations in tension caused by the swaying of the suspended object.

JP 2006-27888 A JP 2010-247996 A

The object of the present invention is to provide a wire rope diagnostic method, diagnostic system, and diagnostic program that diagnoses the time to replace the wire rope by taking into account the fluctuation in tension acting on the wire rope caused by the sway of the hanging body.

The wire rope diagnostic method of the present invention, which achieves the above object, is a method for diagnosing the replacement time of a wire rope that moves a suspended body by winding or unwinding a drum through at least one or more sheaves, in which the wire rope is set with a number of wire sections divided at equal intervals, and the position of the suspended body and the tension acting on the wire rope are arranged in a time series for each period shorter than the time required for the wire section to pass through the sheave, and the degree of micro-damage that has occurred in the wire section passing through the sheave is calculated by processing the data by a computing device, and the time to replace the wire rope is diagnosed based on the cumulative damage degree calculated by accumulating the calculated micro-damage degree for each wire section.

The wire rope diagnostic system of the present invention, which achieves the above object, is a wire rope diagnostic system that diagnoses the replacement time of a wire rope that moves a suspended body by winding or unwinding a drum through at least one or more sheaves, and the wire rope has a number of wire sections divided at equal intervals, and is equipped with a position acquisition device that acquires the position of the suspended body at each period shorter than the time required for the wire section to pass through the sheave, a tension acquisition device that acquires the tension acting on the wire rope at each short period, and a calculation device that stores time series data in which the position and the tension are arranged in chronological order at each short period, and the calculation device executes data processing to calculate the degree of micro-damage that has occurred in the wire section passing through the sheave based on the time series data, and data processing to diagnose the replacement time of the wire rope based on the calculated degree of micro-damage.

The wire rope diagnostic program of the present invention, which achieves the above object, causes a calculation device to diagnose the replacement time of a wire rope that moves a suspended body by winding or unwinding a drum through at least one or more sheaves, is characterized in that the wire rope has a number of wire sections divided at equal intervals, and the calculation device, which stores time series data in which the position of the suspended body and the tension acting on the wire rope for each period shorter than the time it takes for the wire section to pass through the sheave, executes the following steps: calculates the degree of micro-damage that has occurred in the wire section passing through the sheave based on the time series data; and diagnoses the time to replace the wire rope based on the calculated degree of micro-damage.

According to the present invention, the degree of micro-damage that occurs in the wire section passing through the sheave includes damage caused by the swinging of the hanging body that occurs while passing through the sheave. Therefore, by using the cumulative damage degree that is the accumulation of this micro-damage degree, it is possible to diagnose the time to replace the wire rope with high accuracy, taking into account the fluctuations in tension acting on the wire rope.

FIG. 1 is a block diagram illustrating an embodiment of a wire rope diagnostic system. FIG. 2 is a flow diagram illustrating the steps of an embodiment of a wire rope diagnostic method and program. FIG. 2 is an explanatory diagram illustrating an example of time-series data. FIG. 11 is an explanatory diagram illustrating an example of passing section time series data. FIG. 11 is an explanatory diagram illustrating an example of accumulated damage level data. FIG. 3 is a flow diagram illustrating steps that are executed instead of the step of identifying a passing section and a tensile stress and the step of calculating a degree of micro-damage in FIG. 2 . FIG. 1 is a graph illustrating a correlation between the number of times a wire rope passes through a sheave and the rate of reduction in rope diameter of the wire rope. 4 is a flow chart illustrating steps executed in place of the step of calculating the degree of micro-damage from the start of FIG. 3. FIG. 11 is an explanatory diagram illustrating time-series rope diameter data. FIG. 11 is an explanatory diagram illustrating wire section rope diameter data. FIG. 2 is an explanatory diagram illustrating the diagnostic results obtained in the examples.

The wire rope diagnostic method, diagnostic system, and diagnostic program of the present invention will be described below based on the embodiment shown in the figures. In FIG. 1, the X direction is the extension direction of the girder of the crane 10 and the direction in which the trolley travels laterally, the Y direction is the traveling direction in which the crane 10 travels, and the Z direction is the vertical direction. Also, the arrows indicate the flow of signals.

The diagnostic system 1 illustrated in FIG. 1 is a system that diagnoses the replacement time of the wire rope 20 that moves the suspending body 11 by paying out and reeling in the drum 12 via five sheaves 21-25 in a crane 10. The diagnostic system 1 includes a tension acquisition device 2, position acquisition devices 3a, 3b, and a calculation device 4. The calculation device 4 can be any of various known computers. The calculation device 4 includes a central processing unit (CPU) 5, a main memory unit (memory) 6, an auxiliary memory unit (e.g., HDD) 7, an input unit (keyboard, mouse) 8, and an output unit (display) 9. The diagnostic program 30 is installed in the auxiliary memory unit 7 of the calculation device 4.

A variety of known cranes can be used as the crane 10. Examples of the crane 10 include a gantry crane (bridge crane), a transfer crane (portal crane), an overhead crane, and a jib crane (including a tower crane), and the type is not particularly limited.

The crane 10 of this embodiment is a known gantry crane, and includes a plurality of wire ropes 20, a hoist 11, a drum 12, a drive unit 13, a crane control device 14, a girder (not shown), a trolley, a leg structure, and a traveling device. The crane 10 moves the hoist 11 to a predetermined position by the trolley moving in the X direction along the girder and the traveling device traveling in the Y direction, and performs container loading and unloading work by raising and lowering the hoist 11 in the Z direction. The hoist 11 refers to something that is lifted by the wire rope 20, and in this embodiment, refers to a hoist and a container connected to the hoist, or a hoist not connected to a container. The drum 12, the drive unit 13, and the crane control device 14 are installed in a machine room (not shown). The drum 12 rotates by the rotational power of the drive unit 13 to wind and unwind the wire rope 20. The crane control device 14 can use various known computers. The crane control device 14 controls the trolley to travel laterally in the X direction, controls the crane 10 to travel in the Y direction using the traveling device, and controls the lifting and lowering of the suspending body 11 in the Z direction.

Various known wire ropes can be used for the wire rope 20. The wire rope 20 is, for example, made by twisting a strand of multiple wires around a core at a specified pitch. The rope diameter d [mm], cross-sectional area A [mm], and total length of the wire rope 20 are not particularly limited. A single crane 10 is provided with multiple wire ropes 20, but the number of wire ropes 20 is not particularly limited. For example, four wire ropes 20 are provided on the crane 10, and in FIG. 1, each wire rope 20 is distinguished by a solid line, a dotted line, a dashed line, or a dashed double-dot line.

The wire rope 20 can be hung in a variety of known ways, and it is sufficient that the wire rope 20 passes through at least one sheave. For example, the wire rope 20 can be hung in such a way that one end is connected to the other end of another wire rope 20 via a connector 15, the other end is connected to the drum 12, and the middle position passes through each of the five sheaves 21 to 25. In this hanging method, the wire rope 20 lifts the suspending body 11 via a sheave 23 installed on the hoisting tool of the suspending body 11.

The wire rope 20 has a number of wire sections 26 divided at equal intervals. The number of digits of the total number of wire sections 26 in one wire rope 20 varies depending on the section length (extension length) ΔS of the wire sections 26. When the total length of the wire rope 20 is three digits using [m] as the unit of length in the International System of Units (SI), the number of digits is approximately three to four digits, and when the total length is two digits, the number of digits is approximately two to three digits. Each wire section 26 is assigned a section number M (= 1, 2, ..., 100, ...) whose numerical value increases from one end or the other end of the wire rope 20 to the other. The wire section 26 is specified by the section number M as well as the start and end positions of the section. The start position of section number M is the section length ΔS multiplied by the section number (M-1), with the start position of the section number (M=1) being "0", and the end position is the section length ΔS multiplied by the section number M.

The multiple wire sections 26 may be set over the entire length of the wire rope 20, but it is advisable to exclude non-diagnosed areas that will receive less damage than the damage that the wire rope 20 receives when passing through the sheaves 21 to 25. Examples of non-diagnosed areas include one end including the fixed end of the wire rope 20 and the end. More specifically, examples of non-diagnosed areas include areas where the position of the wire rope 20 does not change when the suspending body 11 moves, and areas wound around the drum 12. Examples of non-diagnosed areas include areas where the position of the wire rope 20 does not change when the suspending body 11 moves, and areas wound around the drum 12. Examples of non-displaced areas of the wire rope 20 include areas between the connector 15 and the sheave 21 of the fixed pulley fixed to one end of the girder in the X direction. In addition, the area wound around the drum 12 is the area between the area wound around the drum 12 and the sheave 25 of the fixed pulley that is closest to the drum 12 and fixed to the other end of the girder in the X direction when the wire rope 20 is most unwound from the drum 12.

The greater the total number of wire sections 26 per wire rope 20, the higher the accuracy of diagnosing when to replace the wire rope 20. On the other hand, the greater the total number, the greater the computational load on the computing device 4 until the diagnosis result is output, and the greater the degree to which the memory area of the auxiliary memory unit 7 is monopolized. Therefore, it is preferable to set the total number of wire sections 26 per wire rope (maximum value of section number M) so that the total number of all wire sections 26 in the multiple wire ropes 20 provided on one crane 10 is 5,000 or less.

The longer the section length ΔS of the wire sections 26, the fewer the total number of wire sections 26 per wire rope 20, and the lower the diagnostic accuracy. Therefore, it is desirable to set the section length ΔS shorter than the minimum movement distance of the wire rope 20 per unit time when the suspension body 11 is moved. Having the section length ΔS shorter than the minimum movement distance is advantageous for improving diagnostic accuracy. The unit time may be the sampling period of the tension acquisition device 2 and the position acquisition devices 3a and 3b.

In addition, it is more desirable to consider the section length ΔS in addition to the minimum movement distance, slack or expansion of the wire rope 20, or the operation of the tilting device for the purpose of avoiding overload of the tension acting on the wire rope 20 and changing the angle of the suspending body 11. If slack or expansion occurs in the wire rope 20, the wire rope 20 will move and will be damaged when it passes through the sheave. Similarly, if the tilting device is operated, the wire rope 20 will move and will be damaged when it passes through the sheave. The amount of movement of the wire rope 20 due to slack or expansion, or the operation of the tilting device can be grasped based on knowledge obtained in advance from a large number of experiments, test data, or the accumulation of computer simulation results. However, if minute changes in slack or expansion of the wire rope 20 are taken into consideration, the section length ΔS will become infinitely small. Therefore, it is preferable to adopt the minimum movement distance of the wire rope 20 due to slack when the drive device 13 stops and the tension acting on the wire rope 20 disappears. In addition, the extension and contraction of the drum wire rope 20 can be calculated by taking into account the difference in extension between the maximum and minimum tensions acting on the wire rope 20 and the difference in extension between the maximum and minimum temperatures at the installation site of the crane 10. In this way, by setting the section length ΔS in consideration of the slack and extension of the wire rope 20 or the movement of the wire rope 20 due to the operation of the tilting device, the diagnosis can be made taking into account the slack and extension of the wire rope 20 or damage to the wire rope 20 due to the operation of the tilting device, which is advantageous in improving the accuracy of the diagnosis.

Sheaves 21 to 25 (hereinafter, the reference numerals will be omitted when referring to sheaves 21 to 25) may be any of various known sheaves. The sheaves are arranged in order from one end of the wire rope 20 to the other end at intervals. The sheave diameter D [mm] and the sheave shape of each sheave are not particularly limited. The sheave diameter D and the sheave shape of each sheave are, for example, the same. However, sheave 21 is a sheave that contacts a location where the position of the wire rope 20 does not change, and the sheave diameter of this sheave 21 may be smaller than the other sheaves. Each sheave is assigned a sheave number i that increases in the order of arrangement. For example, the sheave number of sheave 21 is i=1, and the sheave numbers i (=2, ..., 5) are assigned to the sheaves 22 to 25 arranged in order from sheave 21 to the drum 12.

Each sheave is appropriately selected as either a movable pulley or a fixed pulley depending on how the wire rope 20 is hung. For example, in this embodiment, sheaves 21 and 25 are fixed pulleys installed on the girder of the crane 10. Sheaves 22 and 24 are movable pulleys installed on the trolley of the crane 10 and move in the X direction as the trolley moves laterally. Sheave 23 is a movable pulley installed on the hoisting fixture of the hoisting body 11 and moves in the Z direction as the hoisting body 11 rises and falls and moves in the X direction as the trolley moves laterally.

The tension acquisition device 2 can use various known sensors as long as it can set the sampling period to the first period t and can acquire the tension Wt [kgf] acting on the wire rope 20. An example of the tension acquisition device 2 is a load cell that measures the tension acting on the connector 15, and the tension Wt acting on each of the wire ropes 20 is half the tension measured by the load cell.

It is desirable for the tension acquisition device 2 to acquire the tension acting on the wire rope 20 at a location where the position of the wire rope 20 does not change. By installing the tension acquisition device 2 at a location where the position of the wire rope 20 does not change, the installation of the tension acquisition device 2 becomes easy. It is more desirable for the tension acquisition device 2 to be installed on the connector 15, but multiple tension acquisition devices 2 may be installed on each of the sheaves 22 to 25. By installing a tension acquisition device 2 on each sheave, it becomes possible to acquire the tension acting on each passing section 27 individually, but as the number of installed tension acquisition devices 2 increases, data organization becomes complicated. On the other hand, by installing a tension acquisition device 2 on each connector 15, the number of devices that acquire the tension acting on multiple wire ropes 20 is reduced, which is advantageous for data organization.

The position acquisition devices 3a and 3b can use various known sensors or a combination of several sensors as long as the sampling period can be set to the first period t and the position (lt, ht) of the hanging body 11 can be acquired. The position (lt, ht) of the hanging body 11 is a relative coordinate system, and indicates the X-direction component and the Z-direction component of the movement distance from the base point. The base point is preferably a position within the range in which the hanging body 11 can move. The position acquisition device 3a is a device that acquires the X-direction position lt of the hanging body 11, and an example of this is a device that measures the number of rotations of the trolley drive device. The position acquisition device 3b is a device that acquires the Z-direction position ht of the hanging body 11, and an example of this is a device that acquires the winding length of the wire rope 20 on the drum 12 or the number of rotations of the drum 12, or a device that measures the distance between the hanging body 11 and the trolley.

The position acquisition devices 3a and 3b may be devices that acquire the absolute position coordinates of the suspending body 11, and examples of such devices include antennas of a positioning satellite system installed directly on the suspending body 11. When acquiring the absolute position coordinates of the suspending body 11, it is preferable to provide a base point with a specified absolute position coordinate on the crane 10, and to set the X-direction component and Z-direction component of the movement distance of the suspending body 11 calculated from the absolute position coordinate of the base point and the absolute position coordinate of the suspending body 11 as the position (lt, ht) of the suspending body 11. In addition, in the case of a crane 10 that loads and unloads containers onto a ship docked at a quay, the position of the suspending body 11 may be lower than the ground, and therefore it is preferable to correct the Z-direction position ht with the main hoist below sea level lift.

The calculation device 4 is installed in an operator's cab (not shown) of the crane 10, or in an operator's cab installed in a remote location away from the crane 10, or in a control room in which a management system for managing containers is installed. When the diagnostic program 30 is started and executed by the input unit 8, the calculation device 4 executes each data processing instructed by the diagnostic program 30. Then, by executing each data processing, the calculation device 4 predicts the replacement time of the wire rope 20 and outputs it to the output unit 9.

The calculation device 4 has basic data including the structure and specification data of the crane 10, the wire rope hanging diagram, the total length of the wire rope 20, and the number of sheaves input in advance to the auxiliary memory unit 7 via the input unit 8. The calculation device 4 has coefficient a based on the sheave shape, coefficient b based on the twisting method of the wire rope 20, sheave diameter D, rope diameter d, and cross-sectional area A input in advance to the auxiliary memory unit 7 via the input unit 8.

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After the diagnostic program 30 is started, initial settings including selection of initial values to be used in each data processing and selection of a prediction result are performed by the input unit 8. After the initial settings are completed, when the time-series data 31 is stored in the auxiliary storage unit 7 of the arithmetic device 4, the diagnostic program 30 causes the arithmetic device 4 to execute each data processing according to the initial settings.

Figure 2 shows an example of the diagnostic method and the procedure executed by the diagnostic program 30. First, the tension Wt and the position (lt, ht) are acquired for each first period t (S110, S120). Next, when the time series data 31 is stored in the auxiliary memory unit 7 of the calculation device 4 (S130), the diagnostic program 30 causes the calculation device 4 to execute each procedure (S140 to S170). Finally, when the diagnosis result of the time to replace the wire rope 20 is output to the output unit 9, the process returns to the start and each procedure is executed again. These procedures are repeated while the hoisting body 11 is being moved by the crane 10. In addition, the data accumulated by the repetition is reset when the wire rope 20 is replaced, and is accumulated when the movement of the hoisting body 11 by the crane 10 is started after the wire rope 20 is replaced. The contents of each step (S110) to (S180) are described in detail below.

In the step (S110) of acquiring the tension Wt, the tension acquisition device 2 acquires the tension Wt acting on the wire rope 20 for each first period t. In the step (120) of acquiring the position (lt, ht), the position acquisition devices 3a and 3b acquire the position (lt, ht) of the hanging body 11 for each first period t.

The first period t is a preset fixed sampling period. The first period t is set to a period shorter than the time required for the passing section 27 to pass the sheave (the time from when a certain wire section 26 starts passing the sheave to when the passage ends). The first period t is set by a combination of the rated speed of the movement of the suspending body 11, the section length ΔS of the wire section 26, and the sheave diameter D. In addition, it is desirable that the first period t is shorter than the period of the swing of the suspending body 11 when the swing is regarded as a simple pendulum. Since the period of the swing of the suspending body 11 differs depending on the distance between the suspending body 11 and the trolley, the first period t can be shorter than the period of the swing of the suspending body 11 that is most dominant in the loading cycle, or shorter than the period of the swing of the suspending body 11 that is the longest in the loading cycle. By making the first period t shorter than the period of the swing of the suspending body 11, it becomes possible for the tension acquisition device 2 to more accurately acquire the tension acting on the wire rope 20 caused by the swing of the suspending body 11. It is desirable to synchronize the sampling period of the tension acquisition device 2 and the position acquisition devices 3a and 3b with the first period t, but the sampling period of the tension acquisition device 2 may be set to a period shorter than the first period t.

In the step (S130) of storing the time series data 31 illustrated in FIG. 3, the time series data 31 consisting of the tension Wt and position (lt, ht) arranged in time series for each first period t is stored in the auxiliary memory unit 7 of the calculation device 4. The time series data 31 may be sent directly from the tension acquisition device 2 and the position acquisition devices 3a and 3b to the calculation device 4 for each first period t, or may be sent to the calculation device 4 via the crane control device 14.

The time series data 31 may have a data structure in which the newly acquired tension Wt and position (lt, ht) are added to the data up to the previous cycle (t-1) and updated, or may have a data structure consisting of a plurality of second cycle data grouped for each second cycle T, which is a cycle longer than the first cycle t. The time series data 31 may also have a data structure consisting of one second cycle data grouped for each second cycle T, and updated for each second cycle T. When the time series data 31 is added and updated for each first cycle t, the amount of data increases over time. Therefore, in order to prevent the time series data 31 from increasing in size, the time series data 31 is grouped for each second cycle T, which makes data management easier and is advantageous in deleting unnecessary parts from the auxiliary storage unit 7 to avoid a shortage of storage space in the auxiliary storage unit 7. The second cycle T is a preset fixed cycle, and is a cycle in which the first cycle t is repeated multiple times.

In the step (S140) of identifying the passing section 27 and the tensile stress δt [kgf/mm ² ], the calculation device 4 identifies each passing section 27 based on the time series data 31, and then performs data processing to identify the tensile stress δt acting on the passing section 27. The passing section 27 indicates the wire section 26 with section number M passing through any one of the sheaves 21 to 25 when the suspending body 11 is moving, and the section number M is identified for each sheave number i. The passing section 27 is in a state in which at least a part of the section is in contact with the sheave and is bent by the sheave. In this step, specifically, the calculation device 4 identifies which wire section 26 with section number M is the passing section 27 for each first period t based on the position (lt, ht) of the time series data 31, and performs data processing to create the passing section time series data 32 illustrated in FIG. 4. Next, the calculation device 4 executes data processing based on the created pass section time series data 32 to identify the tensile stress δt acting on the pass section 27 using the change in section number M of the pass section 27 as a judgment criterion.

The method of identifying the passing section 27 from the position (lt, ht) of the time series data 31 is not particularly limited, and is not particularly limited as long as the passing section 27 for each sheave number i can be identified. An example of the method is shown below. First, a predetermined position of the contact part between the wire rope 20 and the sheave when the position (lt, ht) of the suspending body 11 is the base point is acquired in advance. The predetermined position can be arbitrarily selected from within the range of the contact part, and for example, the midpoint of the contact part is exemplified. The wire section 26 with section number M where this predetermined position exists in the range from the start position to the end position becomes the passing section 27 when the suspending body 11 exists at the base point. Next, the predetermined position is set as the initial value, and the position (lt, ht) which is a variable is substituted into a function determined by the way the wire rope 20 is hung at the position (lt, ht) of the suspending body 11. Next, the obtained position identifies the wire section 26 existing in the range from the start position to the end position as the passing section 27, and identifies its section number M.

The passing section time series data 32 illustrated in FIG. 4 is a data set in which the section number M of the passing section 27 for each sheave number i and the tension Wt for each first cycle t are arranged in a chronological order for each first cycle t. As with the time series data 31, the passing section time series data 32 may have a data structure in which new data is added sequentially to data up to the previous cycle (t-1) and updated, a data structure made up of multiple second cycle data compiled for each second cycle T, or a data structure made up of one second cycle data compiled for each second cycle T and updated for each second cycle T. In this embodiment, the second cycle T is a cycle in which the first cycle t is repeated three times, and the passing section time series data 32 has a data structure made up of multiple second cycle data compiled for each second cycle T.

The second cycle T is a preset fixed cycle in which the first cycle t is repeated multiple times. It is desirable that the second cycle T is a period during which the section number (M-1) of the passing section 27 switches to the next section number M at least once. If the number of switches is one or more, it is possible to output the diagnosis results of the wire rope 20 by processing data for at most two cycles of the second cycle T by the calculation device 4, and the area occupied by the auxiliary memory unit 7 can be reduced. Furthermore, since the amount of data increases as the number of switches increases, it is desirable that the number of switches be five or less.

As a method for identifying the tensile stress δt acting on the passing section 27, a method is exemplified in which the tension acting on the passing section 27 (in this embodiment, half the value of the tension acquired by the tension acquisition device 2) is identified, and the identified tension is divided by the cross-sectional area A of the wire rope 20 to identify the value obtained as the tensile stress δt. As a method for identifying the tension acting on the passing section 27, a method is exemplified in which the average value or median value of the tension Wt for each first period t from the start to the end of the passage of the sheave in the passing section 27 is calculated, a method is exemplified in which the tension Wt is identified when a predetermined position of the passing section 27 (for example, the center position of the passing section 27) passes through the sheave, and a method is exemplified in which the tension Wt is identified when the number M of the passing section 27 is switched to the next number (M+1). By adopting the average value or median value of multiple tensions Wt, the calculation load of the calculation device 4 increases, but it is advantageous for more accurately grasping the tensile stress δt acting on the passing section 27. On the other hand, by adopting a method for selecting one of multiple tensions Wt, the calculation load of the calculation device 4 is reduced. Therefore, the method for identifying the tension acting on the passing section 27 should be selectable by the diagnostic program 30 and should be changeable as appropriate depending on the situation.

In the step of calculating the degree of micro-damage Dj (S150), the calculation device 4 executes data processing to calculate the degree of micro-damage Dj that has occurred in the passing section 27 based on the identified tensile stress δt. Specifically, the calculation device 4 calculates the degree of micro-damage Dj using the following formula (2) from the value obtained by substituting the identified tensile stress δt and a numerical value known in advance into the following formula (1).

The previously determined numerical values are input by the input unit 8 and stored in the auxiliary memory unit 7 of the calculation device 4. The numerical values are a coefficient a due to the sheave shape, a coefficient b due to the twisting method of the wire rope 20, the sheave diameter D of each sheave, and the rope diameter d of the wire rope 20. However, if the sheave diameter and sheave shape differ for each sheave, the values of the sheave diameter D and the coefficient a due to the sheave shape substituted into formula (1) will be different for each sheave.

The above formula (1) is Niemann's experimental formula. Therefore, the number of breaks Nj obtained from formula (1) indicates the number of times that the passing section 27 can pass through the sheave before breaking when a specific tensile stress δt continues to act on the passing section 27. The above formula (2) indicates that the micro-damage degree Dj is the reciprocal of the number of breaks Nj. The damage degree indicates a value calculated by adding up the effects of each stress (the value obtained by dividing the number of times that the stress amplitude actually occurred by the number of repetitions until breaking by that stress amplitude) using the S-N diagram and the stress waveform in the known cumulative fatigue damage law. In other words, the micro-damage degree Dj indicates the degree of damage caused to the passing section 27 when the passing section 27 under the action of the tensile stress δt passes through the sheave once.

In the step of calculating the cumulative damage level Ds (S160), the calculation device 4 executes data processing based on the calculated micro-damage level Dj to calculate the cumulative damage level Ds (ΣDj) in which the micro-damage level Dj is sequentially accumulated for each wire section 26 from the start of use of the wire rope 20. Specifically, the calculation device 4 creates cumulative damage level data 33 as shown in FIG. 5. The start of use of the wire rope 20 refers to the time when the suspension body 11 is moved immediately after the wire rope 20 is replaced.

The accumulated damage data 33 is composed of the time series of micro-damage Dj for each section number M of the wire section 26, the accumulated damage Ds obtained by sequentially accumulating the micro-damage Dj, and the number of times the sheave passes n. The accumulated damage data 33 is stored in the auxiliary memory unit 7, and is updated each time the micro-damage Dj is calculated by the calculation device 4, and is reset (initialized) by replacing the wire rope 20. It is desirable that the accumulated damage data 33 is configured so that the sheave number i in which the micro-damage Dj occurred can be identified along with the micro-damage Dj. By making the sheave number i identifiable, it becomes possible to grasp the history of the micro-damage Dj for each sheave number i. The number of passes n is the number of times the wire section 26 with the section number M is identified as the passing section 27, and indicates the number of times the micro-damage Dj occurred. The number of passes n is not essential, but may be used in diagnosing the replacement timing described below. The time series of minute damage levels Dj in the cumulative damage level data 33 may be deleted after calculating the cumulative damage level Ds, but if they are left in place, they can be used to analyze damage to the wire rope 20.

In the step of diagnosing the replacement time (S170), the calculation device 4 executes data processing to diagnose the replacement time of the wire rope 20 based on the calculated micro-damage degree Dj. Indicators for diagnosing the replacement time of the wire rope 20 include the life of the wire rope 20, the period until the life is reached, and the number of times that the wire rope 20 can pass through the sheave before the life is reached (hereinafter, the predicted remaining number). The wire rope 20 is considered to have broken when any one of the multiple wire sections 26 breaks. Therefore, the appropriate time to replace the wire rope 20 is a time before at least one of the multiple wire sections 26 breaks. According to the known cumulative fatigue damage law, when any of the cumulative damage degrees Ds for each wire section 26 reaches "1", one of the wire sections 26 will break, so the cumulative damage degree Ds corresponds to the life of the wire rope 20. In addition, the predicted period until the cumulative damage level Ds reaches "1" (until the end of its life) can be predicted based on the progression of the cumulative damage level Ds for each wire section 26, and this predicted period corresponds to the period until the end of the life of the wire rope 20. In addition, the reciprocal of the cumulative damage level Ds can be regarded as the predicted number of times the wire section 26 can pass through the sheave before breaking, and therefore corresponds to the predicted remaining number of times. Therefore, it is possible to diagnose the time to replace the wire rope 20 based on the cumulative damage level Ds for each wire section 26.

To diagnose the time to replace the wire rope 20 based on the lifespan of the wire rope 20, the maximum cumulative damage Dsm, which is the largest among the cumulative damage Ds for each wire section 26, is identified, and the maximum cumulative damage Dsm is used as an index for diagnosing the time to replace the wire rope 20. The time when the maximum cumulative damage Dsm reaches "1" (Dsm ≧ 1) may be diagnosed as the time when the wire rope 20 has reached the end of its lifespan, but it is preferable that the time to replace the wire rope 20 be before the wire rope 20 breaks. Therefore, it is preferable to diagnose the time to replace the wire rope 20 when the maximum cumulative damage Dsm reaches a damage threshold Da set to a value smaller than "1" (Dsm ≧ Da). The damage threshold Da can be arbitrarily set by the input unit 8 to the diagnostic program 30 within a range of values smaller than "1". For example, when diagnosing the time to replace the wire rope 20 when the wire rope 20 reaches 70% of its lifespan, the damage threshold Da is set to "0.7".

To diagnose the replacement time of the wire rope 20 based on the period until the wire rope 20 reaches its lifespan, the maximum cumulative damage degree Dsm for each specified time in a specified period is identified, the correlation between the specified time and the maximum cumulative damage degree Dsm is grasped, and the predicted cumulative damage degree Df for the scheduled time is predicted based on the correlation thus grasped, and the predicted cumulative damage degree Df is used as an index for diagnosing the replacement time of the wire rope 20. Specifically, the maximum cumulative damage degree Dsm of the wire rope 20 is identified for each work date and time of the crane 10 in a specified work period, and the correlation between the work date and time and the maximum cumulative damage degree Dsm is grasped. Next, the predicted cumulative damage degree Df for the scheduled work date and time is predicted by using the correlation. Then, the predicted cumulative damage degree Df is used as an index for diagnosing the replacement time of the wire rope 20. It is preferable to diagnose the replacement time of the wire rope 20 until the scheduled work date and time when the predicted cumulative damage degree Df reaches "1" or the damage degree threshold value Da. The correlation between the work date and time and the maximum cumulative damage level Dsm can be expressed as a straight line that approximates the change in the maximum cumulative damage level Dsm for each work date and time in a certain work period. It can also be expressed as the average or median of the increase in the maximum cumulative damage level Dsm for each work date and time in a certain work period.

To diagnose when to replace the wire rope 20 based on the predicted remaining number of times, the inverse of the cumulative damage level Ds may be used as an index for diagnosing when to replace the wire rope 20, but the prediction accuracy is low because the tension Wt that actually acts on the wire rope 20 after the prediction is unpredictable. Therefore, it is better to calculate the cycle damage level Dcy per movement cycle of the suspension body 11 for each wire section 26 based on the cumulative damage level Ds, identify the maximum cycle damage level Dcym that is the largest among the cycle damage levels Dcy, and use the minimum predicted cycle number Nsm, which is the inverse of the maximum cycle damage level Dcym, as an index for diagnosing when to replace the wire rope 20.

The movement cycle of the suspending body 11 refers to a series of cycles in which the suspending body 11 is moved from a predetermined location to a target location, and then moved back to the predetermined location. When loading a container onto a ship, "one" cycle refers to moving the container from a predetermined location to the target location on the ship, and then moving the suspending device from the target location to the predetermined location and returning it after the container is loaded onto the ship (and the reverse cycle is also included). The damage level Dcy per cycle is calculated by dividing the cumulative damage level Ds by the number of movement cycles Ncy, which is the total number of movement cycles of the suspending body 11 from the start of use of the wire rope 20 to the time the cumulative damage level Ds is calculated.

The time to replace the wire rope 20 may be diagnosed when the minimum predicted cycle count Nsm reaches "0" (Nsm = 0), that is, when there are no more predicted cycles remaining. However, it is preferable to diagnose the time to replace the wire rope 20 before the wire rope 20 breaks. Therefore, it is preferable to diagnose the time to replace the wire rope 20 when the value obtained by multiplying the minimum predicted cycle count Nsm by a cycle coefficient k set to a value smaller than "1" reaches "0" (kNsm = 0). The cycle coefficient k can be arbitrarily set by the input unit 8 to the diagnostic program 30 within a range of values smaller than "1". For example, when diagnosing the time to replace the wire rope 20 when the minimum predicted cycle count Nsm reaches 70%, the cycle coefficient k is set to "0.7".

The minimum predicted cycle number Nsm is compared with the planned movement cycle number Na based on the container loading and unloading schedule, and if the minimum predicted cycle number Nsm is smaller than the planned movement cycle number Na, the time when the crane 10 is stopped before the loading and unloading schedule may be diagnosed as the time to replace the wire rope 20. The planned movement cycle number Na is set based on the container loading and unloading schedule, and the container loading and unloading schedule is available from a management system that manages the container loading and unloading. For example, the planned movement cycle numbers Nb, Nc, etc. for each work day are obtained from the management system, and the minimum predicted cycle number Nsm after the end of work on a certain work day is set to "50", the next planned movement cycle number Nb after that work day is set to "30", and the next next planned movement cycle number Nc after that work day is set to "100". In this way, by comparing the planned movement cycle with the minimum predicted cycle number Nsm, it is possible to diagnose the time to replace the wire rope 20 after the end of work of the next planned movement cycle number Nb. Instead of the minimum predicted cycle number Nsm, a value obtained by multiplying the minimum cycle number Nsm by the cycle coefficient k may be used.

When the time to replace the diagnosed wire rope 20 approaches, the operator or manager of the crane 10 may be instructed to replace the wire rope 20. Examples of methods for instructing to replace the wire rope 20 include changing the display on the output section 9 of the computing device 4, or turning on a warning lamp or sounding a warning sound using a warning device.

The procedure illustrated in Figure 6 is executed in place of steps (S140) and (S150) in Figure 2. In this procedure, the rope diameter d' in the passing section 27 is estimated (S210 to S240), the tensile stress δt' corresponding to the rope diameter d' is calculated (S250), and then the rope diameter d' and the tensile stress δt' are used to calculate the micro-damage degree Dj (S260). The contents of each step (S210) to (S260) are described in detail below.

In the step (S210) of identifying the passing section 27, the calculation device 4 executes data processing similar to the data processing for identifying the passing section 27 in step (S140) of FIG. 2. In the step (S220) of reading the number of passes n, the calculation device 4 executes data processing for reading the number of passes n indicated in the cumulative damage data 33 based on the section number M of the identified passing section 27.

In the step of calculating the reduction rate R (S230), the calculation device 4 performs data processing to calculate the reduction rate R of the passing section 27 using the number of passes n for each wire section 26 of the wire rope 20 to be diagnosed and the correlation shown in FIG. 7, which is known in advance. The reduction rate R indicates the percentage reduction from the nominal rope diameter d of the wire rope 20.

Figure 7 was created based on data obtained by measuring a specific wire section 26 of multiple wire ropes 20, such as wire ropes 20 that have been used in the same manner (e.g., solid lines in Figure 1) on the same crane 10 and replaced, or wire ropes 20 currently in use. Specifically, it was created based on the number of passes n obtained by a method similar to that of the embodiment, and the rope diameter d' determined by a known measurement method (measurement method using vernier calipers) at the timing of regular inspection. The black dots in the figure are plotted at the corresponding positions of the reduction rate R and the number of passes n, which are calculated from the nominal rope diameter d and rope diameter d' of each wire rope 20. A straight line approximating the plotted black dots shows the correlation between the number of passes n and the reduction rate R. This correlation may be obtained by computer simulation.

In the step (S240) of estimating the rope diameter d', the calculation device 4 multiplies the previously determined rope diameter d by the calculated reduction rate R to calculate the displaced rope diameter d', and executes data processing to calculate the cross-sectional area A' using the calculated rope diameter d'. In the step (S250) of calculating the tensile stress δt', the calculation device 4 executes data processing to identify the tension acting on the passing section 27, and to identify the value obtained by dividing the identified tension by the calculated cross-sectional area A' of the wire rope 20 as the tensile stress δt'.

In the step (S260) of calculating the minute damage degree Dj, the calculation device 4 executes data processing to calculate the minute damage degree Dj using the following formula (3) that uses the rope diameter d' and the tensile stress δt' instead of the rope diameter d and the tensile stress δt in the above formula (1). Numerical values known in advance are used for the values other than the rope diameter d' and the tensile stress δt'.

In this procedure, the displaced rope diameter d' is estimated using the correlation between the number of passes n and the reduction rate R, but the displaced rope diameter d' may be used instead of the reduction rate R. Also, the cumulative damage level Ds may be used instead of the number of passes n.

The procedure illustrated in FIG. 8 is executed when the rope diameters of multiple wire sections 26 are measured for each first period t by multiple measuring devices (not shown), and the measured rope diameter is used as the rope diameter d' of the passing section 27. In this procedure, the rope diameter is measured (S310), and the time series data 31 and rope diameter data 34 are stored in the auxiliary storage unit 7 (S320). Next, when the passing section 27 and the tensile stress δt' are identified by the calculation device 4, the rope diameter d' of the passing section 27 is identified (S330), and the micro-damage degree Dj is calculated. The contents of each step (S310) to (S330) are described in detail below.

In the step of measuring the rope diameter (S310), the rope diameter is measured at multiple locations for each first period t by multiple measuring devices. The multiple measuring devices are installed on the crane 10, arranged at intervals along the path of the wire rope 20. Various known measuring devices can be used as the measuring devices. An example of the measuring device is a device that is composed of an image acquisition unit (camera) and an image analysis unit (a function of the computing device 4) and measures the rope diameter by processing the acquired image data. Another example of the measuring device is a laser outer diameter measuring device. It is desirable to arrange the multiple measuring devices at least in the vicinity of each sheave so that the rope diameter d' of the passing section 27 can be identified in a subsequent step.

In the step (S320) of storing the time series data 31 and the rope diameter data 34 illustrated in FIG. 9, the time series data 31 and rope diameter data 34 in which the rope diameters measured at multiple locations are arranged in chronological order for each measuring device are stored in the auxiliary memory unit 7 of the calculation device 4. The rope diameter data 34 may be sent directly from the multiple measuring devices to the calculation device 4 for each first period t, or may be sent from the crane control device 14 to the calculation device 4. Unlike the time series data 31, the rope diameter data 34 requires a number of data (measured rope diameters) equal to or greater than the number of wire sections 26. Therefore, it is desirable for the rope diameter data 34 to have a data structure in which newly measured rope diameters are added sequentially to the data up to the previous period (t-1) and updated.

In the step of identifying the rope diameter d' (S330), the computing device 4 creates the section rope diameter data 35 illustrated in FIG. 10 based on the time series data 31 and the rope diameter data 34, and executes data processing to identify the rope diameter d' of the passing section 27 based on the created section rope diameter data 35. The method of creating the section rope diameter data 35 based on the time series data 31 and the rope diameter data 34 identifies the section number M of the wire section 26 where multiple locations exist in the range from the start position to the end position, using a similar method to the method of identifying the passing section 27, but using the location measured by the measuring device instead of the specified location.

In this procedure, rope diameters at multiple locations measured by multiple measuring devices installed on the crane 10 were used, but when measuring the rope diameter d' for each wire section 26 of the wire rope 20 during inspection of the crane 10, the rope diameter d' for each wire section 26 measured during inspection can also be used. However, since it requires a great deal of effort to measure the rope diameter d' for all wire sections 26 during inspection of the crane 10, it is preferable to use rope diameters at multiple locations measured by multiple measuring devices installed on the crane 10.

In this way, by using the rope diameter d' displaced by passing through the sheave and the tensile stress δt' corresponding to the rope diameter d' in the Niemann experimental formula shown in the above formula (3), it is possible to calculate the micro-damage degree Dj that varies according to the change in the rope diameter d' and the tensile stress δt'. In other words, by diagnosing the replacement time taking into account the change in the external shape of the wire rope 20 due to aging, the accuracy of the diagnosis can be further improved.

As described above, according to this embodiment, the degree of micro-damage Dj that occurs each time the passing section 27 passes through the sheave is accumulated to diagnose when to replace the wire rope 20. Therefore, even if the tensile stress δt acting on the wire rope 20 fluctuates minutely, it is possible to diagnose when to replace the wire rope 20 by taking into account the damage corresponding to the fluctuation. This is advantageous in improving the accuracy of diagnosing when to replace the wire rope 20, and it is possible to ensure safety by reliably replacing the wire rope 20 before it breaks, and to reduce costs by reducing the frequency of unnecessary replacement of the wire rope 20.

In addition, according to this embodiment, by setting the resolution to the first period t that is shorter than the period until the passing section 27 passes through the sheave, it is possible to accumulate damage to the wire rope 20 due to minute fluctuations in tensile stress acting on the wire rope 20. In this way, by diagnosing the time to replace the wire rope 20 based on the accumulated damage level Ds, which is the accumulated fine damage level Dj each time the passing section 27 passes through the sheave, it is possible to perform a diagnosis with higher accuracy than the conventional method that uses the number of times the wire rope passes through the sheave in a specified period as a criterion.

Although the embodiments of the present invention have been described above, the wire rope diagnostic method and diagnostic system 1 and diagnostic program 30 of the present invention are not limited to specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention.

The wire rope 20 to be diagnosed by the diagnostic system 1 is not limited to those used in various known cranes. The wire rope 20 to be diagnosed may be, for example, a wire rope used in various known elevators. When the wire rope to be diagnosed is an elevator wire rope, the elevator car corresponds to the hanging body of the present invention.

The diagnostic program 30 may be a collection of individual procedures in one package, or may be a collection of individual procedures in several packages. The computing device 4 may also be a collection of multiple electric circuits or programmable logic controllers (PLCs) that execute each procedure.

The number of breaks Nj obtained by the Niemann experimental formula shown in the above formula (1) or formula (3) may deviate from the actual value when the load of the suspending body 11 is low. Therefore, when the tension Wt acting on the wire rope 20 is smaller than the tension threshold Wa that is previously determined, it is preferable to use a value obtained by multiplying the number of breaks Nj obtained by the Niemann experimental formula shown in the above formula (1) or formula (3) by a correction coefficient c. The correction coefficient c is calculated using the following formula (4). Here, the variable f and the sheave bending stress ΔB [kgf/mm ² ] are values previously determined by the calculation device 4. The variable f is a value according to the specifications of the crane 10, such as the way in which the wire rope 20 is hung. The sheave bending stress ΔB is a value calculated by multiplying the Young's modulus E [kgf/mm 2 ] of the material of the outer layer wire constituting the wire rope 20 by a value obtained by dividing the outer layer wire diameter Φ [mm] of the wire rope 20 by the sheave diameter D [mm].

Correcting the number of breaks Nj using the correction coefficient c is advantageous in suppressing deviations in the number of breaks Nj that occur when the suspending body 11 is under a low load. The tension threshold Wa can be selected appropriately according to the specifications of the crane 10 and the loading and unloading conditions of the container, as long as it is possible to determine that a low load exists when the suspending device is not suspending a container or when the container is empty. The above formula (4) shows one example of calculating the correction coefficient c, and the method of calculating the correction coefficient c is not limited to the method using the above formula (4), as long as it is possible to correct deviations in the number of breaks Nj that occur when the suspending body 11 is under a low load.

Four wire ropes used in known gantry cranes were used as the wire ropes 20 to be diagnosed. Containers were loaded and unloaded for several days using a gantry crane that used the wire ropes 20 to be diagnosed.

The explanatory diagram shown in FIG. 11 shows the diagnosis results 40 of the diagnostic program 30 displayed on the output unit 9. The diagnosis results 40 are represented by a cumulative damage graph 41 and a replacement prediction graph 42. In FIG. 11, as in FIG. 1, the diagnosis results 40 of each wire rope 20 to be diagnosed are distinguished by a solid line, a dotted line, a dashed line, and a dashed double-dot line.

The cumulative damage graph 41 is created based on the cumulative damage Ds for each wire section 26 of each diagnosed wire rope 20. By checking the cumulative damage graph 41, it is possible to see at a glance which wire section 26 of each diagnosed wire rope 20 is damaged. In the cumulative damage graph 41, when the cursor is placed over an area showing an arbitrary wire section 26 by operating the input unit 8, a window pops up above the cumulative damage graph 41 in which the cumulative damage Ds of each diagnosed wire rope 20 in that wire section 26 and the number of passes through the sheaves 22 to 25 are displayed in numbers. This allows more detailed data to be confirmed.

The replacement prediction graph 42 is created based on the maximum cumulative damage degree Dsm for each work date and time of the crane 10. In the replacement prediction graph 42, the maximum cumulative damage degree Dsm, which is an actual measurement value, is displayed on the work date and time (left side of the graph) before the actual work date and time (Today) of the crane 10, and the predicted damage degree Df, which is a predicted value, is displayed on the work date and time after the actual work date and time of the crane 10 (right side of the graph). The predicted damage degree Df was obtained from the correlation indicated by a straight line that approximates the trend of the maximum cumulative damage degree Dsm for each work date and time. By checking the predicted damage degree Df on the replacement prediction graph 42, the work schedule of the crane 10 and the replacement time of the wire rope 20 to be diagnosed can be compared, and the replacement schedule of the wire rope 20 to be diagnosed can be set to a date that does not interfere with work. The planned replacement date was set three days before the work date and time when the predicted damage degree Df reaches the damage degree threshold Na. By checking the planned replacement date on the replacement prediction graph 42, the period until the planned replacement date can be grasped at a glance. In the replacement prediction graph 42, if there is a period prior to the actual work date and time during which the maximum cumulative damage level Dsm has not been calculated, this can be supplemented using the average or median of the increase in the maximum cumulative damage level Dsm for each work date and time during the entire period during which the maximum cumulative damage level Dsm was calculated or during a specified period.

In the diagnosis result 40, a wire rope hanging diagram display button 43, a calculation method setting button 44, and a replacement date setting button 45 are displayed. When the input unit 8 is operated to place a cursor over the wire rope hanging diagram display button 43 and click it, a wire rope hanging diagram in which each wire rope 20 and sheaves 21 to 25 can be visually distinguished on the cumulative damage degree graph 41 and the replacement prediction graph 42 can be displayed. An example of the wire rope hanging diagram is a diagram as shown in FIG. 1. When the input unit 8 is operated to place a cursor over the calculation method setting button 44 and click it, a window in which the completion method of the replacement prediction graph 42 and the prediction method of the predicted damage degree Df can be set is popped up. When the wire rope 20 to be diagnosed is replaced, the input unit 8 is operated to place a cursor over the replacement date setting button 45 and click it, a window in which the replacement date (start date of use) of the newly diagnosed wire rope 20 that has been replaced is popped up.

The above embodiment is merely an example, and the diagnosis result 40 of the diagnostic program 30 can be set as appropriate. For example, only the replacement prediction graph 42 may be displayed as the diagnosis result 40. Also, only the replacement date predicted based on the minimum predicted cycle count Nsm may be displayed as the diagnosis result.

REFERENCE SIGNS LIST 1 diagnostic system 2 tension acquisition devices 3a, 3b position acquisition device 4 calculation device 10 crane 11 hoisting body 12 drum 20 wire rope 21-25 sheave 26 wire section 27 passing section 30 diagnostic program t first period T second period M section number
Wt Tension (lt, ht) Position Dj Micro-damage degree Ds Accumulative damage degree

Claims (11)

A wire rope diagnostic method for diagnosing the replacement time of a wire rope that moves a suspended body by winding or unwinding a drum through at least one or more sheaves, comprising:
The wire rope has a number of wire sections that are equally spaced apart,
A wire rope diagnosis method characterized in that a degree of micro-damage caused in the wire section passing through the sheave is calculated by processing time series data in which the position of the suspension body and the tension acting on the wire rope are arranged in chronological order for each period shorter than the time required for the wire section to pass through the sheave using a computing device, and the time to replace the wire rope is diagnosed based on a cumulative damage degree obtained by accumulating the calculated micro-damage degrees for each wire section. The wire rope diagnosis method according to claim 1, wherein the time series data is organized into periods longer than the short periods, and the long periods are periods during which the passing wire section switches to the next wire section at least once. The wire rope diagnosis method according to claim 1, in which the largest maximum cumulative damage level is identified from the cumulative damage levels for each wire section, and the maximum cumulative damage level is used as an index for diagnosing the time to replace the wire rope. The wire rope diagnosis method according to claim 3, which identifies the maximum cumulative damage level for each specified time in a specified period, grasps the correlation between the specified time and the maximum cumulative damage level, predicts a predicted cumulative damage level at a scheduled time based on the grasped correlation, and uses the predicted cumulative damage level as an index for diagnosing the time to replace the wire rope. A wire rope diagnostic method according to claim 1, which calculates the cycle damage level per movement cycle of the suspension body based on the cumulative damage level for each wire section, identifies the largest maximum cycle damage level among the cycle damage levels for each wire section, and uses the minimum predicted number of cycles, which is the reciprocal of the maximum cycle damage level, as an index for diagnosing the time to replace the wire rope. The wire rope diagnosis method according to claim 1, in which the degree of micro-damage is calculated as the reciprocal of the number of breaks obtained by substituting, into Niemann's experimental formula, a coefficient according to the shape of the sheave, a coefficient according to the twisting method of the wire rope, the sheave diameter of the sheave, and the rope diameter of the wire rope, and the tensile stress acting on the wire section during the passage, which is identified based on the time-series data. A wire rope diagnosis method according to claim 6, in which the rope diameter of the wire section being passed is acquired, and the degree of micro-damage is calculated using the acquired rope diameter instead of the previously determined rope diameter in the Niemann's experimental formula, and using the acquired tensile stress corresponding to the rope diameter instead of the tensile stress. The wire rope diagnosis method according to claim 7, in which the correlation between the number of times each wire section passes through the sheave and the rate of reduction in the rope diameter of the wire rope is acquired in advance, and the calculation device calculates the rate of reduction of the wire section being passed using the number of times each wire section of the wire rope to be diagnosed passes through the sheave and the previously determined correlation, and estimates the rope diameter of the wire section being passed based on the calculated rate of reduction. The wire rope diagnosis method according to claim 7, in which the rope diameters of the wire rope are measured at multiple locations at each short period by multiple measuring devices, and one of the rope diameters measured at multiple locations is used as the rope diameter of the wire section being passed. A wire rope diagnostic system for diagnosing the replacement time of a wire rope that moves a suspended body by winding or unwinding a drum through at least one or more sheaves,
The wire rope has a number of wire sections that are equally spaced apart,
The system includes a position acquisition device that acquires the position of the suspending body at a period shorter than the time required for the wire section to pass through the sheave, a tension acquisition device that acquires the tension acting on the wire rope at the short period, and a calculation device that stores time series data in which the position and the tension are arranged in time series at the short period,
The wire rope diagnostic system is characterized in that the calculation device performs data processing to calculate the degree of micro-damage that has occurred in the wire section passing through the sheave based on the time series data, and data processing to diagnose the time to replace the wire rope based on the calculated degree of micro-damage. A wire rope diagnostic program for causing a computing device to diagnose the replacement time of a wire rope that moves a suspended body by winding or unwinding a drum through at least one or more sheaves,
The wire rope has a number of wire sections that are equally spaced apart,
A wire rope diagnostic program characterized by having a calculation device that stores time series data in which the position of the suspension body and the tension acting on the wire rope are arranged in chronological order for each period shorter than the time required for the wire section to pass through the sheave execute the following steps: calculating the degree of micro-damage that has occurred in the wire section passing through the sheave based on the time series data; and diagnosing the time to replace the wire rope based on the calculated degree of micro-damage.

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