Wire rope diagnostic method, diagnostic system, and diagnostic program

Abstract

To provide a wire rope diagnostic method, a diagnostic system, and a diagnostic program for diagnosing the time to replace a wire rope in consideration of fluctuations in tension acting on the wire rope due to vibration of a hanging body.SOLUTION: In a wire rope diagnostic method for diagnosing when to replace a wire rope 20 that passes through sheaves 21 to 25, the wire rope 20 has many wire sections 26 divided at equal intervals. A minute damage degree Dj caused in a passing section 27 is calculated by an arithmetic device 4 that processes time-series data 31 in which the position of a hanging body (lt, ht) and a tension wt acting on the wire rope 20 are arranged in chronological order for each first cycle t, and the time to replace the wire rope 20 is diagnosed based on a cumulative damage degree Ds obtained by accumulating the calculated minute damage degree Dj for each wire section 26.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wire rope diagnostic method, diagnostic system, and diagnostic program, and more particularly to a wire rope diagnostic method, diagnostic system, and diagnostic program that diagnoses the time to replace the wire rope by taking into account fluctuations in tension acting on the wire rope. [Background technology]

[0002] Devices have been proposed for diagnosing wire ropes in cranes, elevators, etc. (For example, see 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 loaded 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.

[0003] However, even if the load of the suspended object lifted by the wire rope or the acceleration when the suspended object is moved is constant, if the suspended object sways, the tension acting on the wire rope will fluctuate due to the sway. Therefore, there is room for improvement in diagnosing the time to replace the wire rope with high accuracy, taking into account the fluctuation in tension caused by the sway of the suspended object. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-27888 A [Patent Document 2] JP 2010-247996 A Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a wire rope diagnostic method, diagnostic system, and diagnostic program that diagnose the time to replace the wire rope by taking into account fluctuations in tension acting on the wire rope due to the swaying of a hanging body. [Means for solving the problem]

[0006] The wire rope diagnostic method of the present invention for achieving the above object is a wire rope diagnostic method for diagnosing the replacement time of a wire rope that moves a suspended body by winding or unwinding it on a drum via at least one or more sheaves, the wire rope is provided with a number of wire sections divided at equal intervals, The swing of the hanging body is regarded as a simple pendulum, and the period of the swing is The time it takes for the wire section to pass through the sheave and The method is characterized in that 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 period, using a computing device, the degree of micro-damage that has occurred in the wire section passing through the sheave is calculated, and the time to replace the wire rope is diagnosed based on the cumulative damage degree obtained by accumulating the calculated micro-damage degrees for each wire section. The wire rope diagnosis method of the present invention is a wire rope diagnosis method for diagnosing the time to replace a wire rope that moves a suspended body by winding or unwinding a drum through at least one or more sheaves, wherein the wire rope has a number of wire sections divided at equal intervals, and a calculation device processes time series data in which the position of the suspended 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, thereby calculating the degree of micro damage caused in the wire section passing through the sheave, identifying the largest maximum cumulative damage degree among the cumulative damage degrees obtained by accumulating the calculated micro damage degrees for each wire section, identifying the maximum cumulative damage degree for each specified time in a specified period, grasping the correlation between the specified time and the maximum cumulative damage degree, predicting a predicted cumulative damage degree at a scheduled time based on the grasped correlation, and using the predicted cumulative damage degree as an index for diagnosing the time to replace the wire rope. The wire rope diagnosis method of the present invention is a wire rope diagnosis method for diagnosing the time to replace a wire rope that moves a suspended body by winding or unwinding a drum through at least one or more sheaves, wherein the wire rope has a number of wire sections divided at equal intervals, and a calculation device processes time series data in which the position of the suspended 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, thereby calculating the degree of micro-damage that has occurred in the wire section passing through the sheave, calculating the degree of cycle damage per movement of the suspended body based on the accumulated damage degree obtained by accumulating the calculated micro-damage degrees for each wire section, identifying the largest maximum cycle damage degree among the cycle damage degrees for each wire section, and using the minimum predicted cycle number, which is the reciprocal of the maximum cycle damage degree, as an index for diagnosing the time to replace the wire rope. The wire rope diagnosis method of the present invention is a wire rope diagnosis method for diagnosing the time to replace a wire rope that moves a suspended body by winding or unwinding a drum through at least one or more sheaves, wherein the wire rope has a number of wire sections divided at equal intervals, and 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 required for the wire section to pass through the sheave are processed by a computing device to calculate the degree of micro-damage caused in the wire section passing through the sheave, and the time to replace the wire rope is diagnosed based on the cumulative damage degree obtained by accumulating the calculated micro-damage degrees for each wire section, and the micro-damage degree is calculated as the reciprocal of the number of breaks obtained by substituting, into Niemann's empirical formula, a coefficient based on the shape of the sheave, a coefficient based on the twisting method of the wire rope, the sheave diameter of the sheave, and the rope diameter of the wire rope, which are known in advance, and the tensile stress acting on the wire section during passage identified based on the time series data.

[0007] The wire rope diagnostic system of the present invention for achieving the above object is a wire rope diagnostic system for diagnosing the replacement time of a wire rope that moves a suspended body by winding or unwinding it on a drum via at least one or more sheaves, the wire rope is provided with a number of wire sections divided at equal intervals, The swing of the hanging body is regarded as a simple pendulum, and the period of the swing is The time it takes for the wire section to pass through the sheave andThe system comprises a position acquisition device that acquires the position of the hanging body at a period shorter than the period of time, a tension acquisition device that acquires the tension acting on the wire rope at the short period of time, and a calculation device in which time series data consisting of the position and the tension arranged in chronological order at the short period of time is stored, and 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.

[0008] The wire rope diagnostic program of the present invention for achieving the above object is a wire rope diagnostic program that causes a calculation device to diagnose the replacement time of a wire rope that moves a suspended body by winding or unwinding it on a drum via at least one or more sheaves, the wire rope having a number of wire sections divided at equal intervals, The swing of the hanging body is regarded as a simple pendulum, and the period of the swing is The time it takes for the wire section to pass through the sheave and The method is characterized in that the calculation device, which 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 1000 s, executes the steps of: 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. Effect of the Invention

[0009] According to the present invention, the degree of micro-damage occurring in the wire section passing through the sheave includes damage caused by the swing of the hanging body occurring during the passage of the sheave. Therefore, by using the cumulative damage degree obtained by accumulating the micro-damage degrees, it becomes possible to diagnose the time to replace the wire rope with high accuracy, taking into account the fluctuation of the tension acting on the wire rope. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram illustrating an embodiment of a wire rope diagnostic system. [Diagram 2] FIG. 2 is a flow diagram illustrating the steps of an embodiment of a wire rope diagnostic method and program. [Diagram 3] FIG. 2 is an explanatory diagram illustrating an example of time-series data. [Figure 4] FIG. 11 is an explanatory diagram illustrating an example of passing section time series data. [Diagram 5] FIG. 11 is an explanatory diagram illustrating an example of accumulated damage level data. [Figure 6] 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. [Figure 7] 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 the rope diameter of the wire rope. [Figure 8] 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. [Figure 9] FIG. 11 is an explanatory diagram illustrating time-series rope diameter data. [Figure 10] FIG. 11 is an explanatory diagram illustrating wire section rope diameter data. [Figure 11] FIG. 2 is an explanatory diagram illustrating the diagnostic results obtained in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 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 drawings. 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 of the crane 10, and the Z direction is the vertical direction. Also, the arrows indicate the flow of signals.

[0012] The diagnostic system 1 illustrated in FIG. 1 is a system for diagnosing the replacement time of a wire rope 20 that moves a suspended body 11 by being let out and reeled in by a 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 storage unit (memory) 6, an auxiliary storage unit (e.g., HDD) 7, an input unit (keyboard, mouse) 8, and an output unit (display) 9. A diagnostic program 30 is installed in the auxiliary storage unit 7 of the calculation device 4.

[0013] Various 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.

[0014] The crane 10 of this embodiment is a known gantry crane, and includes a plurality of wire ropes 20, a hoisting body 11, a drum 12, a drive device 13, a crane control device 14, a girder (not shown), a trolley, a leg structure, and a traveling device. The crane 10 moves the hoisting body 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 hoisting body 11 in the Z direction. The hoisting body 11 refers to something that is lifted by the wire rope 20, and in this embodiment, refers to a hoisting tool and a container connected to the hoisting tool, or a hoisting tool not connected to a container. The drum 12, the drive device 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 device 13 to wind and unwind the wire rope 20. The crane control device 14 can use various known computers. The crane control device 14 executes control for moving the trolley laterally in the X direction, control for running the crane 10 in the Y direction using the traveling device, and control for raising and lowering the hoisting body 11 in the Z direction.

[0015] Various known wire ropes can be used for the wire rope 20. The wire rope 20 is formed, for example, by twisting a strand of a plurality of wires around a core at a predetermined pitch. The rope diameter d [mm], cross-sectional area A [mm], and total length of the wire rope 20 are not particularly limited. A plurality of wire ropes 20 are provided on one crane 10, 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.

[0016] Various known methods can be used for hanging the wire rope 20, and the wire rope 20 may pass through at least one sheave. For example, the wire rope 20 may 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 intermediate positions pass through each of the five sheaves 21 to 25. In this hanging method, the wire rope 20 hoists the hoisting body 11 via a sheave 23 installed on the hoisting tool of the hoisting body 11.

[0017] The wire rope 20 is provided with 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 a three-digit length 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 a two-digit length, 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 identified 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 section number (M=1) being "0", and the end position is the section length ΔS multiplied by the section number M.

[0018] Although the multiple wire sections 26 may be set over the entire length of the wire rope 20, it is preferable to exclude non-diagnosed portions 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 portions include one end including the fixed end of the wire rope 20 and the end. More specifically, examples of non-diagnosed portions include a portion where the position of the wire rope 20 does not change when the suspending body 11 moves, and a portion wound around the drum 12. The portion where the position of the wire rope 20 does not change is, for example, a portion 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 portion wound around the drum 12 is a portion between the portion 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.

[0019] 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.

[0020] 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 suspending body 11 is moved. Making the section length ΔS shorter than the minimum movement distance is advantageous for improving diagnostic accuracy. The unit time should be the sampling period of the tension acquisition device 2 and the position acquisition devices 3a and 3b.

[0021] In addition, it is more preferable to consider the section length ΔS in addition to the minimum movement distance, the slack or expansion of the wire rope 20, or the operation of the tilting device for avoiding overload of the tension acting on the wire rope 20 and changing the angle of the suspending body 11. When the wire rope 20 is slack or expanded, the wire rope 20 moves and is damaged when it passes through the sheave. Similarly, when the tilting device is operated, the wire rope 20 moves and is damaged when it passes through the sheave. The amount of movement of the wire rope 20 due to the 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, when considering minute changes in the slack or expansion of the wire rope 20, the section length ΔS becomes infinitely small. Therefore, it is preferable to adopt the minimum movement distance of the wire rope 20 due to the slack when the driving device 13 stops and the tension acting on the wire rope 20 is no longer present. Furthermore, the extension / contraction of the drum wire rope 20 may 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 location of the crane 10. In this way, by setting the section length ΔS in consideration of the slack or extension / contraction occurring in the wire rope 20 or the movement of the wire rope 20 due to the operation of the tilting device, the diagnosis takes into account the slack or extension / contraction occurring in 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.

[0022] The sheaves 21 to 25 (hereinafter, the reference numerals will be omitted when referring to the sheaves 21 to 25) may be 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, the sheave 21 is a sheave that contacts a portion of the wire rope 20 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 the sheave 21 is i=1, and the sheave numbers i (=2, . . . , 5) are assigned to the sheaves 22 to 25 arranged in order from the sheave 21 to the drum 12.

[0023] For each sheave, either a movable pulley or a fixed pulley is appropriately selected 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 tool 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.

[0024] 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.

[0025] It is desirable that the tension acquisition device 2 acquires 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 that the tension acquisition device 2 is 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.

[0026] 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 a 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.

[0027] The position acquisition devices 3a and 3b may be devices that acquire the absolute position coordinates of the suspending body 11, and an example of this is an antenna 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.

[0028] The computing 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 control system for managing containers is installed. When the diagnostic program 30 is started and executed by the input unit 8, the computing device 4 executes each data processing instructed by the diagnostic program 30. Then, by executing each data processing, the computing device 4 predicts the replacement time of the wire rope 20 and outputs the predicted data to the output unit 9.

[0029] In the calculation device 4, basic data including structure and specification data of the crane 10, a wire rope hanging diagram, the total length of the wire rope 20, and the number of sheaves are input in advance to the auxiliary storage unit 7 by the input unit 8. In the calculation device 4, a coefficient a according to the sheave shape, a coefficient b according to the twisting method of the wire rope 20, a sheave diameter D, a rope diameter d, and a cross-sectional area A are input in advance to the auxiliary storage unit 7 by the input unit 8.

[0030] Examination 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 unit 4, the diagnostic program 30 causes the arithmetic unit 4 to execute each data processing according to the initial settings.

[0031] FIG. 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 storage 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 replacement time of the wire rope 20 is output to the output unit 9, the process returns to the start and each procedure is executed again. The repetition of each procedure is 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.

[0032] In a step (S110) of acquiring the tension Wt, the tension Wt acting on the wire rope 20 is acquired for each first period t by the tension acquisition device 2. In a step (120) of acquiring the position (lt, ht), the position (lt, ht) of the hanging body 11 is acquired for each first period t by the position acquisition devices 3a and 3b.

[0033] 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 preferable 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.

[0034] 3, the time series data 31 in which the tension Wt and the position (lt, ht) for each first period t are arranged in time series is stored in the auxiliary storage 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, 3b to the calculation device 4 for each first period t, or may be sent via the crane control device 14 to the calculation device 4.

[0035] 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 suppress the increase in the time series data 31, 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 area in the auxiliary storage unit 7. The second cycle T is a preset fixed cycle, in which the first cycle t is repeated multiple times.

[0036] Passing section 27 and tensile stress δt [kgf / mm 2 In the step (S140) of identifying each passing section 27, 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 contacts 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 performs data processing to identify the tensile stress Δt acting on the passing section 27 based on the created passing section time series data 32, using the change in section number M of the passing section 27 as a judgment criterion.

[0037] 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 in which 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 an 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.

[0038] 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 period t are arranged in time series for each first period 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 sequentially added to data up to the previous period (t-1) and updated, a data structure made up of a plurality of second period data compiled for each second period T, or a data structure made up of one second period data compiled for each second period T and updated for each second period T. In this embodiment, the second period T is a period in which the first period t is repeated three times, and the passing section time series data 32 has a data structure made up of a plurality of second period data compiled for each second period T.

[0039] 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. Also, since the amount of data increases as the number of switches increases, it is desirable that the number of switches be five or less.

[0040] As a method for identifying the tensile stress δt acting on the passing section 27, a method for identifying the tension acting on the passing section 27 (in this embodiment, half the value of the tension acquired by the tension acquisition device 2) and dividing the identified tension by the cross-sectional area A of the wire rope 20 to identify the value obtained as the tensile stress δt is exemplified. As a method for identifying the tension acting on the passing section 27, a method for calculating 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, a method for identifying the tension Wt when a predetermined position of the passing section 27 (for example, the center position of the passing section 27) passes the sheave, and a method for identifying the tension Wt when the number M of the passing section 27 is switched to the next number (M+1) are exemplified. 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, it is preferable that the method of identifying the tension acting on the passing section 27 can be selected by the diagnostic program 30 and can be changed appropriately according to the situation.

[0041] In the step (S150) of calculating the degree of micro-damage Dj, the calculation device 4 executes data processing based on the identified tensile stress δt to calculate the degree of micro-damage Dj that has occurred in the passing section 27. 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).

[0042]

number

[0043] 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, a sheave diameter D of each sheave, and a rope diameter d of the wire rope 20. However, when the sheave diameter and the 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) shall be different for each sheave.

[0044] 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 passage section 27 can pass through the sheave before breaking when a specific tensile stress δt continues to act on the passage 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 influence 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 the stress amplitude) using the SN 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 passage section 27 when the passage section 27 in a state where the tensile stress δt is acting passes through the sheave once.

[0045] In the step (S160) of calculating the accumulated damage level Ds, the calculation device 4 executes data processing based on the calculated minor damage level Dj to calculate the accumulated damage level Ds (ΣDj) in which the minor damage levels Dj are sequentially accumulated for each wire section 26 from the start of use of the wire rope 20. Specifically, the calculation device 4 creates accumulated damage level data 33 as shown in Fig. 5. The start of use of the wire rope 20 refers to the time when the suspending body 11 is moved immediately after the wire rope 20 is replaced.

[0046] The accumulated damage data 33 is composed of the minute damage Dj in time series for each section number M of the wire section 26, the accumulated damage Ds obtained by sequentially accumulating the minute damage Dj, and the number of times the sheave passes n. The accumulated damage data 33 is stored in the auxiliary storage unit 7, and is updated each time the calculation device 4 calculates the minute damage Dj, and is reset (initialized) when the wire rope 20 is replaced. It is desirable that the accumulated damage data 33 is configured so that the sheave number i in which the minute damage Dj occurred can be identified along with the minute damage Dj. By making the sheave number i identifiable, it becomes possible to grasp the history of the minute damage Dj for each sheave number i. 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 minute damage Dj occurred. The number of times the sheave passes n is passed is not essential, but may also be used in diagnosing the timing of replacement, which will be described later. The time-series micro damage levels Dj of the cumulative damage level data 33 may be deleted after calculating the cumulative damage level Ds, but if left undeleted, they can be used to analyze damage to the wire rope 20.

[0047] In the step (S170) of diagnosing the replacement time, 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 the wire rope 20 can pass through the sheave before the life is reached (hereinafter, the predicted remaining number of times). 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 one 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. Furthermore, the predicted period until the accumulated damage level Ds reaches "1" (until the end of its life) can be predicted based on the transition of the accumulated 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. Furthermore, the reciprocal of the accumulated 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 accumulated damage level Ds for each wire section 26.

[0048] In order to diagnose the time to replace the wire rope 20 based on the life 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 specified, and the maximum cumulative damage Dsm is used as an index for diagnosing the time to replace the wire rope 20. When the maximum cumulative damage Dsm reaches "1" (Dsm ≧ 1), the time to replace the wire rope 20 may be diagnosed as the time when the life of the wire rope 20 has ended, but it is preferable that the time to replace the wire rope 20 is before the wire rope 20 breaks. Therefore, when the maximum cumulative damage Dsm reaches a damage threshold Da set to a value smaller than "1" (Dsm ≧ Da), it is preferable to diagnose the time to replace the wire rope 20. The damage threshold Da can be arbitrarily set to the diagnostic program 30 by the input unit 8 within a range of values ​​smaller than "1". For example, when the time to replace the wire rope 20 is diagnosed when the wire rope 20 reaches 70% of its lifespan, the damage level threshold Da is set to "0.7".

[0049] In order to diagnose the replacement time of the wire rope 20 based on the period until the life of the wire rope 20 is reached, the maximum cumulative damage Dsm for each predetermined time in a predetermined period is specified, the correlation between the predetermined time and the maximum cumulative damage Dsm is grasped, and the predicted cumulative damage Df at the scheduled time is predicted based on the correlation thus grasped, and the predicted cumulative damage Df is used as an index for diagnosing the replacement time of the wire rope 20. Specifically, the maximum cumulative damage Dsm of the wire rope 20 is specified for each work date and time of the crane 10 in a predetermined work period, and the correlation between the work date and time and the maximum cumulative damage Dsm is grasped. Next, the predicted cumulative damage Df at the scheduled work date and time is predicted by using the correlation. Then, the predicted cumulative damage 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 Df reaches "1" or the damage threshold Da. The correlation between the work date 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.

[0050] To diagnose the replacement time of the wire rope 20 based on the predicted remaining number of times, the reciprocal of the accumulated damage level Ds may be used as an index for diagnosing the replacement time of the wire rope 20, but the prediction accuracy is low because the tension Wt actually acting on the wire rope 20 after the prediction is unpredictable. Therefore, it is preferable to calculate the cycle damage level Dcy per movement cycle of the hanging body 11 for each wire section 26 based on the accumulated damage level Ds, identify the maximum cycle damage level Dcym, which is the largest among the cycle damage levels Dcy, and use the minimum predicted cycle number Nsm, which is the reciprocal of the maximum cycle damage level Dcym, as an index for diagnosing the replacement time of the wire rope 20.

[0051] 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 again. In the case of loading a container onto a ship, "one" cycle refers to moving a container from a predetermined location to a target location on the ship, and after loading the container onto the ship, moving the suspending device from the target location to the predetermined location and returning it (including the reverse cycle). 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 when the cumulative damage level Ds was calculated.

[0052] 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 remaining cycles. However, it is preferable that the time to replace the wire rope 20 is 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 for 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".

[0053] The minimum predicted cycle number Nsm may be compared with the planned movement cycle number Na based on the container loading and unloading schedule, and when 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 loading and unloading of the container. 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 a cycle coefficient k may be used.

[0054] When the time to replace the diagnosed wire rope 20 approaches, it is advisable to instruct the operator or manager of the crane 10 to replace the wire rope 20. Examples of methods for instructing to replace the wire rope 20 include changing the display of the output unit 9 of the computing device 4, or turning on a warning lamp or sounding a warning sound by a warning device.

[0055] The procedure illustrated in Fig. 6 is executed in place of step (S140) and step (S150) in Fig. 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 minute damage degree Dj is calculated using the rope diameter d' and the tensile stress δt' (S260). The contents of each step (S210) to (S260) are described in detail below.

[0056] In the step (S210) of identifying the passed section 27, the calculation device 4 executes data processing similar to the data processing for identifying the passed section 27 in the 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 accumulated damage degree data 33 based on the section number M of the identified passed section 27.

[0057] In the step (S230) of calculating the reduction rate R, the calculation device 4 executes 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 that is known in advance. The reduction rate R indicates the rate of reduction from the nominal rope diameter d of the wire rope 20.

[0058] FIG. 7 is created based on data obtained by measuring a predetermined wire section 26 of a plurality of wire ropes 20, such as a wire rope 20 that has been used in the same manner (for example, the solid line in FIG. 1) on the same crane 10 and replaced, or a wire rope 20 that is currently in use. Specifically, it is created based on the number of passes n obtained by the same method as in the embodiment, and the rope diameter d' grasped by a known measurement method (measurement method using a vernier caliper) 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 obtained from the nominal rope diameter d and rope diameter d' of each wire rope 20. A straight line approximating the group of 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.

[0059] In the step (S240) of estimating rope diameter d', the calculation device 4 executes data processing to calculate the displaced rope diameter d' by multiplying the previously determined rope diameter d by the calculated reduction rate R, and calculates the cross-sectional area A' using the calculated rope diameter d'. In the step (S250) of calculating tensile stress δt', the calculation device 4 executes data processing to identify the tension acting on the passing section 27, and to divide the identified tension by the calculated cross-sectional area A' of the wire rope 20 to determine the obtained value as the tensile stress δt'.

[0060] 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 parameters other than the rope diameter d' and the tensile stress δt'.

number

[0061] 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.

[0062] The procedure illustrated in Fig. 8 is executed when rope diameters of a plurality of wire sections 26 are measured for each first period t by a plurality of 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 the 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.

[0063] In the step (S310) of measuring the rope diameter, the rope diameter is measured at multiple locations for each first period t by multiple measuring devices. The multiple measuring devices are arranged at intervals along the path of the wire rope 20 and installed on the crane 10. 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 (one 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 specified in a subsequent step.

[0064] 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 a plurality of locations are arranged in chronological order for each measuring device are stored in the auxiliary storage unit 7 of the calculation device 4. The rope diameter data 34 may be sent directly from the plurality of 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 sequentially added to the data up to the previous period (t-1) and updated.

[0065] In the step (S330) of specifying the rope diameter d', the calculation device 4 executes data processing to create section rope diameter data 35 as exemplified in Fig. 10 based on the time series data 31 and rope diameter data 34, and to specify 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 rope diameter data 34 specifies the section number M of the wire section 26 where multiple points exist in the range from the start position to the end position, using a similar method to the method of specifying the passing section 27, except that the location measured by the measuring device is used instead of the predetermined location in the method of specifying the passing section 27.

[0066] In this procedure, rope diameters measured at multiple locations by multiple measuring devices installed on the crane 10 are 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 measuring the rope diameter d' of all wire sections 26 during inspection of the crane 10 requires a great deal of effort, it is desirable to use rope diameters measured at multiple locations by multiple measuring devices installed on the crane 10.

[0067] 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's 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 due to aging of the wire rope 20, the accuracy of the diagnosis can be further improved.

[0068] As described above, according to this embodiment, the degree of minute damage Dj that occurs each time the passing section 27 passes through the sheave is accumulated to diagnose the time 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 the time to replace the wire rope 20 by taking into account the damage corresponding to the fluctuation. This is advantageous in improving the accuracy of the diagnosis of the time 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.

[0069] Furthermore, according to this embodiment, by setting the resolution to the first period t 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 obtained by accumulating the minute damage levels 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 based on the number of times the wire rope passes through the sheave in a predetermined period.

[0070] Although an embodiment of the present invention has been described above, the wire rope diagnostic method, diagnostic system 1, and diagnostic program 30 of the present invention are not limited to the specific embodiment, and various modifications and variations are possible within the scope of the gist of the present invention.

[0071] 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 diagnosis target is the wire rope of an elevator, the elevator car corresponds to the hanging body of the present invention.

[0072] The diagnostic program 30 may be a collection of individual procedures as one package, or may be a collection of individual procedures as several packages. The computing device 4 may be a collection of multiple electric circuits or programmable logic controllers (PLCs) that execute the individual procedures.

[0073] The number of breakages Nj obtained by the Niemann's experimental formula shown in the above formula (1) or (3) may deviate from the actual value when the load of the suspension body 11 is low. Therefore, when the tension Wt acting on the wire rope 20 is smaller than the previously determined tension threshold Wa, it is advisable to use the value obtained by multiplying the number of breakages Nj obtained by the Niemann's experimental formula shown in the above formula (1) or (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 / mm2 ] is a numerical value that is known in advance by the calculation device 4. The variable f is a numerical value according to the specifications of the crane 10, such as how the wire rope 20 is laid. The sheave bending stress ΔB is a numerical value calculated by multiplying the Young's modulus E [kgf / mm2] of the material of the outer layer wires that make up the wire rope 20 by the value obtained by dividing the outer layer wire diameter Φ [mm] of the wire rope 20 by the sheave diameter D [mm].

[0074]

number

[0075] Correcting the number of breakages Nj using the correction coefficient c is advantageous in suppressing deviations in the number of breakages Nj that occur when the suspending body 11 is under a low load. The tension threshold Wa is sufficient if it can be determined that a low load exists when the suspending device is not suspending a container or when the container is empty, and can be appropriately selected depending on the specifications of the crane 10 and the loading and unloading status of the container. 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 breakages Nj that occur when the suspending body 11 is under a low load. EXAMPLES

[0076] Four wire ropes used in a known gantry crane were used as the wire rope 20 to be diagnosed. Containers were loaded and unloaded for several days using the gantry crane using the wire rope 20 to be diagnosed.

[0077] 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, similar to 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.

[0078] The cumulative damage graph 41 is created based on the cumulative damage Ds for each wire section 26 of each wire rope 20 to be diagnosed. By checking the cumulative damage graph 41, it is possible to know at a glance which wire section 26 of each wire rope 20 to be diagnosed 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 wire rope 20 to be diagnosed and the number of passes through the sheaves 22 to 25 in that wire section 26 are displayed in numbers. This allows more detailed data to be confirmed.

[0079] The replacement prediction graph 42 is created based on the maximum cumulative damage Dsm for each work date and time of the crane 10. In the replacement prediction graph 42, the maximum cumulative damage 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 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 Df was obtained from the correlation indicated by a straight line that approximates the transition of the maximum cumulative damage Dsm for each work date and time. By checking the predicted damage 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 date of the wire rope 20 to be diagnosed can be set to a date that does not interfere with the work. The planned replacement date was set three days before the work date and time when the predicted damage Df reaches the damage 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 increase in the maximum cumulative damage level Dsm for each work date and time during the entire period or a specified period during which the maximum cumulative damage level Dsm has been calculated.

[0080] The diagnosis result 40 displays a wire rope hanging diagram display button 43, a calculation method setting button 44, and a replacement date setting button 45. 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 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.

[0081] 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 planned date predicted based on the minimum predicted cycle number Nsm may be displayed as the diagnosis result. [Explanation of symbols]

[0082] 1 Diagnostic System 2 Tension acquisition device 3a, 3b Location acquisition device 4 Arithmetic unit 10. Crane 11 Hanging body 12 Drums 20 Wire Rope 21~25 Sheaves 26 Wire Section 27 Passing Section 30 Diagnostic Program t first period T second period M Section number Wt tension (lt, ht) position Dj fine damage Ds Cumulative damage

Claims

1. 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 the swing of the hanging body is regarded as a simple pendulum, and time series data in which the position of the hanging body and the tension acting on the wire rope are arranged in chronological order for each period shorter than both the period of the swing and the time required for the wire section to pass through the sheave are processed by a computing device, thereby calculating the degree of micro-damage that has occurred in the wire section passing through the sheave, and diagnosing the time to replace the wire rope based on the cumulative damage degree obtained by accumulating the calculated micro-damage degrees for each wire section.

2. 2. A wire rope diagnosis method as described in 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 based on the shape of the sheave, a coefficient based on the twisting method of the wire rope, the sheave diameter of the sheave, and the rope diameter of the wire rope, which are known in advance, and the tensile stress acting on the wire section during the passage, which is identified based on the time series data.

3. 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 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 are processed by a computing device to calculate the degree of micro-damage that occurred in the wire section passing through the sheave, the calculated degrees of micro-damage are accumulated for each wire section to identify the largest maximum cumulative damage degree, the maximum cumulative damage degree for each specified time in a specified period of time is identified, the correlation between the specified time and the maximum cumulative damage degree is grasped, a predicted cumulative damage degree at a scheduled time is predicted based on the grasped correlation, and the predicted cumulative damage degree is used as an index for diagnosing the time to replace the wire rope.

4. 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 in which the position of the suspension body and the tension acting on the wire rope for each period shorter than the time required for the wire section to pass through the sheave are processed by a computing device to calculate the degree of micro-damage caused to the wire section while it is passing through the sheave, the calculated micro-damage is accumulated for each wire section to calculate the degree of cycle damage per movement cycle of the suspension body based on the accumulated damage, the maximum cycle damage level, which is the largest among the cycle damage levels for each wire section, is identified, and the minimum predicted cycle number, which is the reciprocal of the maximum cycle damage level, is used as an index for diagnosing the time to replace the wire rope.

5. 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, The time series data in which the position of the suspension body and the tension acting on the wire rope are arranged in time series for each period shorter than the time required for the wire section to pass through the sheave are processed by a calculation device to calculate the degree of micro-damage that has occurred in the wire section passing through the sheave, and the time to replace the wire rope is diagnosed based on the cumulative damage degree obtained by accumulating the calculated micro-damage degrees for each wire section; A wire rope diagnosis method 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 based on the shape of the sheave, a coefficient based on the twisting method of the wire rope, the sheave diameter of the sheave, and the rope diameter of the wire rope, which are known in advance, and the tensile stress acting on the wire section during the passage, which is identified based on the time series data.

6. A wire rope diagnosis method as described in claim 2 or 5, in which the rope diameter of the wire section being passed through is obtained, and the degree of micro-damage is calculated using the obtained rope diameter instead of the rope diameter previously determined in Niemann's experimental formula, and using the tensile stress corresponding to the obtained rope diameter instead of the tensile stress.

7. The wire rope diagnosis method of claim 6, further comprising: acquiring in advance a correlation between the number of times each wire section has passed through the sheave and the rate of reduction in the rope diameter of the wire rope; and using the calculation device to calculate the rate of reduction of the wire section currently passing through using the number of times each wire section of the wire rope to be diagnosed has passed through the sheave and the correlation previously determined; and estimating the rope diameter of the wire section currently passing through based on the calculated rate of reduction.

8. A wire rope diagnosis method as described in claim 6, in which the rope diameters of the wire rope are measured at multiple points at each short period using multiple measuring devices, and one of the rope diameters measured at multiple points is used as the rope diameter of the wire section being passed through.

9. A wire rope diagnosis method as described in claim 2 or 5, in which, when the tension in the time series data is smaller than a previously determined tension threshold, the number of breaks is corrected using a correction coefficient.

10. 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 comprises: a position acquisition device which regards the swing of the hanging body as a simple pendulum and acquires the position of the hanging body at a period shorter than both the period of the swing and the time required for the wire section to pass through the sheave; a tension acquisition device which acquires the tension acting on the wire rope at each of the short periods; and a calculation device which stores time series data in which the position and the tension are arranged in time series at each of the short periods; 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.

11. 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 the arithmetic device, which stores time series data in which the position of the hanging body and the tension acting on the wire rope are arranged in chronological order for each period shorter than the period of the swing of the hanging body as a simple pendulum and the time required for the wire section to pass through the sheave, execute the following steps: calculate the degree of micro-damage that has occurred in the wire section passing through the sheave based on the time series data; and diagnose the time for replacing the wire rope based on the calculated degree of micro-damage.

Images