JP7731932B2 - Wire rope diagnostic method, diagnostic system, and diagnostic program - Google Patents

Description

The present invention relates to a wire rope diagnostic method, diagnostic system, and diagnostic program, and more specifically to a wire rope diagnostic method, diagnostic system, and diagnostic program that diagnoses the need for wire rope replacement by taking into account fluctuations in the tension acting on the wire rope.

A device has been proposed for diagnosing wire ropes in cranes, elevators, etc. (see Patent Document 1). The invention described in Patent Document 1 divides the position of the main rope into predetermined main rope lengths and calculates the degree of deterioration for each length.

When diagnosing wire ropes, shortening the length of the section to be diagnosed allows for more focused diagnosis and improves diagnostic accuracy. However, shortening the length of the section to be diagnosed increases the number of wire rope segments, which creates problems such as a heavier computational load and a larger amount of data occupying memory space. Therefore, there is room for improvement in improving wire rope diagnostic accuracy while reducing computational load and suppressing the amount of data occupying memory space.

Japanese Patent Application Laid-Open No. 2006-27888

The object of the present invention is to provide a wire rope diagnostic method, diagnostic system, and diagnostic program that improves wire rope diagnostic accuracy while reducing the computational load and suppressing the amount of data occupying memory space.

The wire rope diagnosis method of the present invention, which solves the above-mentioned object, is a wire rope diagnosis method in which a number of wire sections divided at equal intervals are set, and a suspended body is moved by winding or unwinding a drum via at least one or more sheaves, and at least one of the number of times the sheaves are passed, the cumulative damage level, and the rope diameter are processed by a computing device as data for each of the number of wire sections that fluctuates due to the movement of the suspended body over a specified period, thereby identifying, as key diagnosis areas, wire sections among the number of wire sections that have a higher impact on the diagnosis of the wire rope than a standard, and setting, for the identified key diagnosis areas, a number of key diagnosis areas divided at equal intervals using section lengths shorter than the section length of the wire sections, thereby giving a higher priority to the diagnosis of the key diagnosis areas than the priority to the diagnosis of the remaining wire sections excluding the key diagnosis areas from the number of wire sections.
The wire rope diagnosis method of the present invention is a method for diagnosing a wire rope in which a large number of wire sections divided at equal intervals are set, and a suspended body is moved by winding or unwinding on a drum via at least one or more sheaves. In this method, at least one of the number of times the sheaves are passed, the cumulative damage level, and the rope diameter is processed by a computing device as data for each of the large number of wire sections that varies due to the movement of the suspended body during a predetermined period. By processing the data, the wire sections among the large number of wire sections that have a higher impact on the diagnosis of the wire rope than a standard are identified as key diagnosis areas, and the key diagnosis areas are identified as follows: A number of key diagnosis sections are set, divided at equal intervals using section lengths shorter than the section length of the wire section, and while the crane or elevator equipped with the hanging body is in operation, the computing device processes at least one of the number of times the sheave has passed, the cumulative damage level, and the rope diameter as data for each wire section of the key diagnosis section, which changes due to the movement of the hanging body after the key diagnosis section has been identified, thereby diagnosing only the key diagnosis sections and giving a higher priority to the diagnosis of the key diagnosis sections than to the remaining wire sections excluding the key diagnosis sections from the number of wire sections.

The wire rope diagnostic system of the present invention, which achieves the above-mentioned object, is a diagnostic system having a calculation device that diagnoses a wire rope in which a suspended body is moved by winding or unwinding a drum via at least one or more sheaves, and in which the calculation device performs data processing to identify, among the multiple wire sections, wire sections that have a higher impact on the diagnosis of the wire rope than a standard, as key diagnostic areas based on at least one of the number of times the sheave has been passed, the cumulative damage level, and the rope diameter, which are data for each of the multiple wire sections that fluctuate due to the movement of the suspended body over a specified period of time; and data processing to set, for the identified key diagnostic areas, multiple key diagnostic areas that are equally spaced using section lengths shorter than the section length of the wire sections, thereby increasing the importance of the diagnosis of the key diagnostic areas compared to the importance of the diagnosis of the remaining wire sections excluding the key diagnostic areas from the multiple wire sections.
The wire rope diagnostic system of the present invention has a calculation device for diagnosing a wire rope in which a large number of wire sections are set at equal intervals and which moves a suspended body by winding or unwinding it via at least one sheave, and the calculation device performs data processing to identify, among the large number of wire sections, wire sections that have a higher degree of influence on the diagnosis of the wire rope than a standard, as key diagnostic areas, based on at least one of the number of times the sheaves are passed, the cumulative damage level, and the rope diameter, which are data for each of the large number of wire sections that fluctuate due to the movement of the suspended body during a predetermined period, and to perform data processing to identify, among the large number of wire sections, wire sections that have a higher degree of influence on the diagnosis of the wire rope than a standard, as key diagnostic areas, based on at least one of the number of times the sheaves are passed, the cumulative damage level, and the rope diameter, and to perform data processing to identify, among the large number of wire sections, wire sections that have a higher degree of influence on the diagnosis of the wire rope than a standard, as key diagnostic areas. and performing data processing to set a number of key diagnosis sections divided at equal intervals using section lengths shorter than the section length of the wire section in each section, and during operation of the crane or elevator equipped with the hanging body, performing data processing to give a higher priority to the diagnosis of the key diagnosis sections than to the diagnosis of the remaining wire sections excluding the key diagnosis sections from among the number of wire sections, and to diagnose only the key diagnosis sections based on at least one of the number of passes of the sheave, the cumulative damage level, and the rope diameter as data for each of the number of wire sections that changes due to the movement of the hanging body after the key diagnosis sections have been identified.

The wire rope diagnostic program of the present invention, which achieves the above-mentioned object, is a wire rope diagnostic program that has a number of wire sections divided at equal intervals and that causes a calculation device to diagnose a wire rope that moves a suspended body by winding or unwinding a drum via at least one or more sheaves, and is characterized in that the calculation device executes the following steps: identify, among the many wire sections, wire sections that have a higher impact on the diagnosis of the wire rope than a standard, as key diagnostic areas, based on at least one of the number of times the sheave has been passed, the cumulative damage level, and the rope diameter, which are data for each of the many wire sections that fluctuate due to the movement of the suspended body over a specified period; and set, at the identified key diagnostic areas, a number of key diagnostic areas divided at equal intervals using section lengths shorter than the section length of the wire sections, thereby increasing the importance of the diagnosis of the key diagnostic areas compared to the importance of the diagnosis of the remaining wire sections excluding the key diagnostic areas from the many wire sections.
The wire rope diagnostic program of the present invention is a wire rope diagnostic program that causes a calculation device to diagnose a wire rope that has a large number of wire sections divided at equal intervals and that moves a suspended body by winding or unwinding it on a drum via at least one or more sheaves, and includes the steps of causing the calculation device to identify, among the large number of wire sections, wire sections that have a higher impact on the diagnosis of the wire rope than a standard, as key diagnostic areas, based on at least one of the number of times the sheaves are passed, the cumulative damage level, and the rope diameter , as data for each of the large number of wire sections that fluctuates due to the movement of the suspended body during a predetermined period. The method is characterized in that it executes the following steps: a procedure for setting a number of key diagnosis sections at the key diagnosis area, which are divided at equal intervals using section lengths shorter than the section length of the wire section; and a procedure for, during operation of the crane or elevator equipped with the hanging body, increasing the importance of diagnosing the key diagnosis area compared to the importance of diagnosing the remaining wire sections excluding the key diagnosis area from among the number of wire sections, by diagnosing only the key diagnosis area based on at least one of the number of passes of the sheave, the cumulative damage level, and the rope diameter, which are data for each of the number of wire sections that change due to the movement of the hanging body after the key diagnosis area has been identified.

According to the present invention, the diagnosis results of the identified key diagnostic areas have a significant impact on the diagnosis of the wire rope. Therefore, by focusing on diagnosing the key diagnostic areas, the accuracy of wire rope diagnosis can be improved in the same way as with a method that focuses on diagnosing the entire wire rope. Furthermore, because the key diagnostic areas are only a portion of the wire rope, the computational load can be reduced and the amount of data occupying memory space can be suppressed compared to a method that focuses on diagnosing the entire wire rope. In this way, the present invention is configured to enable high-precision wire rope diagnosis, while also reducing the computational load and suppressing the amount of data occupying memory space.

1 is a block diagram illustrating an embodiment of a wire rope diagnostic system. FIG. FIG. 1 is a flow diagram illustrating the steps of an embodiment of a wire rope diagnostic method and diagnostic program. 2 is an explanatory diagram showing an enlarged view of a part of the wire rope of FIG. 1 , comparing the wire section in the preliminary diagnosis process with the main diagnosis part in the main diagnosis process. FIG. FIG. 1 is a graph illustrating a frequency distribution of the number of sheave passes for a number of wire sections over a given period of time. FIG. 3 is a flow chart illustrating a diagnostic technique used in the preliminary diagnostic step and the main diagnostic step of FIG. 2. FIG. 2 is an explanatory diagram illustrating an example of time-series data. FIG. 10 is an explanatory diagram illustrating an example of passing section time series data. FIG. 10 is an explanatory diagram illustrating an example of cumulative damage level data.

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 Figure 1, the X direction is the extension direction of the girder of the crane 10, which is the direction in which the trolley moves laterally, the Y direction is the traveling direction of the crane 10, and the Z direction is the vertical direction. Arrows also indicate the flow of signals.

The diagnostic system 1 illustrated in Figure 1 is a system that diagnoses the replacement time for the wire rope 20 that moves the suspended body 11 by reeling it out and reeling it in on 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 and 3b, and a computing device 4. The computing device 4 can be any of a variety of well-known computers. The computing 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 computing device 4.

A variety of well-known cranes can be used as the crane 10. Examples of the crane 10 include gantry cranes (bridge cranes), transfer cranes (portal cranes), overhead cranes, and jib cranes (including tower cranes), and there are no particular limitations on the type.

The crane 10 in this embodiment is a known gantry crane, comprising multiple wire ropes 20, a hoisting body 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 hoisting body 11 to a predetermined position by traversing the trolley in the X direction along the girder and traveling in the Y direction using the traveling device, and performs container loading and unloading operations by raising and lowering the hoisting body 11 in the Z direction. The hoisting body 11 refers to something lifted by the wire rope 20, and in this embodiment, refers to a hoisting device and a container connected to the hoisting device, or a hoisting device not connected to a container. The drum 12, drive unit 13, and crane control device 14 are installed in a machine room (not shown). The drum 12 rotates using the rotational power of the drive unit 13 to wind and unwind the wire rope 20. The crane control device 14 can be implemented using 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 formed, for example, by twisting a strand of multiple wires around a core at a predetermined pitch. The rope diameter d (mm), cross-sectional area A (mm ² ), and total length of the wire rope 20 are not particularly limited. Multiple 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 the drawings, 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 hoisted using a variety of well-known methods, as long as the wire rope 20 passes through at least one sheave. For example, the wire rope 20 can be hoisted such 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 five sheaves 21 to 25. In this hoisting method, the wire rope 20 lifts the hoisting body 11 via a sheave 23 installed on the hoisting fixture of the hoisting body 11.

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

Each sheave can be selected as either a movable or fixed pulley, depending on how the wire rope 20 is fastened. 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 installed on the hoisting fixture of the hoisting body 11 and is a movable pulley that moves in the Z direction as the hoisting body 11 moves up and down, and 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 wire rope 20 is half the value of the tension measured by the load cell.

It is desirable that the tension acquisition device 2 acquire the tension acting on the wire rope 20 at a location where the position of the wire rope 20 does not change. Installing the tension acquisition device 2 at a location where the position of the wire rope 20 does not change simplifies installation of the tension acquisition device 2. It is more desirable that the tension acquisition device 2 be installed on the connector 15, but multiple tension acquisition devices 2 may be installed on each of the sheaves 22 to 25. Installing a tension acquisition device 2 on each sheave makes it possible to individually acquire the tension acting on each passing section 29, but increasing the number of installed tension acquisition devices 2 makes organizing the data more complicated. On the other hand, installing a tension acquisition device 2 on each connector 15 reduces the number of devices that acquire the tension acting on multiple wire ropes 20, which is advantageous for organizing the data.

The position acquisition devices 3a and 3b can set the sampling period to the first period t, and can use various known sensors or combinations of sensors as long as they can acquire the position (lt, ht) of the suspending body 11. The position (lt, ht) of the suspending body 11 is a relative coordinate system, indicating the X-direction component and Z-direction component of the movement distance from a base point. The base point is preferably a position within the range in which the suspending body 11 can move. The position acquisition device 3a acquires the X-direction position lt of the suspending 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 acquires the Z-direction position ht of the suspending body 11, and an example of this is a device that acquires the wound 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 suspending 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, such as an antenna for 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 set a base point with identified absolute position coordinates on the crane 10, and to use the X-direction component and Z-direction component of the movement distance of the suspending body 11 calculated from the absolute position coordinates of that base point and the absolute position coordinates of the suspending body 11 as the position (lt, ht) of the suspending body 11. Furthermore, 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, so it is preferable to correct the Z-direction position ht using the main hoist below sea level.

The computing device 4 is installed in the driver's cab (not shown) of the crane 10, or in a driver's cab installed in a remote location away from the crane 10, or in a control room where a management 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 operation instructed by the diagnostic program 30.

The input unit 8 of the calculation device 4 has input in advance into the auxiliary memory unit 7 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. The input unit 8 of the calculation device 4 has input in advance into the auxiliary memory unit 7 coefficient a based on 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.

After the diagnostic program 30 is launched, the input unit 8 performs initial settings, including the selection of initial values to be used in each data process, the selection of prediction results, and the criteria for impact. After the initial settings are complete, the diagnostic program 30 causes the computing device 4 to execute each data process in accordance with the initial settings.

Figure 2 shows an example of a diagnostic method and procedures executed by the diagnostic program 30. First, the diagnostic program 30 causes the calculation device 4 to execute a procedure for repeating a preliminary diagnosis process for a predetermined period of time, with multiple wire sections 26 set at equal intervals on the wire rope 20 (S110, S120). Next, the diagnostic program 30 causes the calculation device 4 to execute a procedure for identifying a key diagnosis area 27 (S130). Next, the diagnostic program 30 causes the calculation device 4 to execute a procedure for repeating the main diagnosis process until the wire rope 20 is replaced, with some of the multiple wire sections 26 set as the key diagnosis area 27 (S140, S150). Below, we will first describe the details of the wire sections 26 and the key diagnosis area 27, and then we will describe the details of each step (S110) to (S180).

Figure 3 shows a portion of the wire rope 20. The consecutive numbers (in the figure, "..." indicates an omitted number) on the upper and lower sides of the wire rope 20, as well as within an enlarged dotted circle of a portion of the wire rope 20, indicate section numbers M. The consecutive section numbers M on the upper side of the wire rope 20 indicate the section numbers M of the numerous wire sections 26 used in the preliminary diagnosis process (S110). The consecutive section numbers M on the lower side of the wire rope 20 indicate the section numbers M of the remaining wire sections 26 excluding the key diagnosis section 27 used in the main diagnosis process (S140). The consecutive section numbers M within the dotted circle indicate the section numbers M of the numerous key diagnosis sections 28 set in the key diagnosis section 27.

The wire sections 26 are sections obtained by dividing the wire rope 20 into equal intervals. The key diagnosis areas 27 are areas identified based on data obtained by the preliminary diagnosis process (S110). Specifically, the key diagnosis areas 27 are areas where multiple wire sections 26 are lined up in succession, including at least one wire section 26 among many wire sections 26 where the degree of damage is higher than the standard. The key diagnosis areas 28 are sections obtained by dividing the key diagnosis areas 27 into equal intervals with a section length Δs that is shorter than the section length (extension length) ΔS of the wire sections 26.

The multiple wire sections 26 may be set along the entire length of the wire rope 20, but it is advisable to exclude non-diagnostic sections that would sustain less damage than the damage sustained when the wire rope 20 passes through the sheaves 21-25. Examples of non-diagnostic sections include the end and terminal ends of the wire rope 20, including the fixed end. More specifically, examples of non-diagnostic sections include sections where the position of the wire rope 20 does not change when the suspending body 11 moves, and sections wound around the drum 12. Examples of non-diagnostic sections include sections between the connector 15 and the sheave 21 of the fixed pulley fixed to one end of the girder in the X direction. Furthermore, the section wound around the drum 12 is the section between the section wound around the drum 12 and the sheave 25 of the fixed pulley closest to the drum 12, when the wire rope 20 is most unwound from the drum 12, and the section between the drum 12 and the sheave 25 of the fixed pulley fixed to the other end of the girder in the X direction.

The total number of digits for the multiple wire sections 26 and multiple key diagnostic sections 28 in a single wire rope 20 varies depending on the section length ΔS of the wire section 26 and the section length Δs of the key diagnostic section 28. The total number of digits is approximately three to four digits when the total length of the wire rope 20 in the International System of Units (SI) is three digits, and approximately two to three digits when the total length is two digits.

In the preliminary diagnosis process (S110), a section number M (1≦M≦200) is assigned to each of the numerous wire sections 26, with the section number M increasing in value from either the one end or the other end of the wire rope 20 to the other. In the main diagnosis process (S140), some of the section numbers M used in the preliminary diagnosis process are omitted (101≦M≦110), and in place of the omitted section numbers M, section numbers M (201≦M≦217) are assigned to each of the numerous key diagnosis sections 28 of the key diagnosis area 27. The section numbers M assigned to the key diagnosis sections 28 are a continuation of the section numbers M assigned to the numerous wire sections 26, with the number increasing in value from either the one end or the other end of the wire rope 20 to the other. For the wire sections 26 and key diagnosis sections 28, the section start and end positions are identified along with the section number M. The start and end positions of section number M are determined based on section length ΔS, section length Δs, and section number M, with the start position of section number (M=1) being "0".

The greater the total number of wire sections 26 and key diagnosis sections 28 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 results are output, and the greater the extent to which memory space in the auxiliary memory unit 7 is monopolized. Therefore, it is preferable to set the total number of wire sections 26 and key diagnosis sections 28 per wire rope (maximum value of section number M) so that the total number of all wire sections 26 and key diagnosis sections 28 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, resulting in lower 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. Having the section length ΔS shorter than the minimum movement distance is advantageous for improving diagnostic accuracy. Note that the unit time should preferably be the sampling period of the tension acquisition device 2 and the position acquisition devices 3a and 3b.

Furthermore, when determining the section length ΔS, it is more desirable to consider not only the minimum travel distance but also the slack, expansion, or contraction of the wire rope 20 or the operation of the tilting device. The tilting device is a device that prevents excessive tension acting on the wire rope 20 and adjusts the angle of the suspending body 11, and any known tilting device can be used. If the wire rope 20 becomes slack or expands, the wire rope 20 will move, causing damage when it passes through the sheave. Similarly, if the tilting device operates, the wire rope 20 will move, causing damage when it passes through the sheave. The amount of movement of the wire rope 20 due to slack, expansion, or operation of the tilting device can be determined based on knowledge gained in advance from numerous experiments, test data, or accumulated computer simulation results. However, considering minute changes in the slack or expansion of the wire rope 20 will result in an infinitely small section length ΔS. Therefore, it is recommended to use the minimum travel distance of the wire rope 20 due to slack when the drive device 13 stops and the tension acting on the wire rope 20 is released. Furthermore, the expansion and contraction of the drum wire rope 20 can be calculated by taking into account the difference in expansion between the maximum and minimum tensions acting on the wire rope 20 and the difference in expansion between the highest and lowest temperatures at the installation location of the crane 10. In this way, by setting the section length ΔS in consideration of the slack and expansion of the wire rope 20, or the movement of the wire rope 20 due to operation of the tilting device, the diagnosis takes into account the slack and expansion of the wire rope 20, or damage to the wire rope 20 due to operation of the tilting device, which is advantageous for improving diagnostic accuracy.

The section length Δs of the key diagnostic section 28 need only be shorter than the section length ΔS, but it is desirable to set it taking into account accuracy based on the minimum sheave contact length of the wire rope 20. For example, if the total length of the wire rope 20 is 200 m, the sheave diameter D is 0.78 m, and the minimum sheave contact length of the wire rope 20 is 1/4 circumference, an example of the section length Δs taking into account the required accuracy is 0.6 m. For example, if the total length of the wire rope 20 is 200 m, diagnosing sections divided at equal intervals of 0.6 m along the entire length of the wire rope 20 would require a total of 334 sections, which would increase the computational load and occupy a larger amount of memory space in the auxiliary memory unit 7. On the other hand, if the section length ΔS of the wire section 26 is 1 m, the total length of the key diagnostic region 27 is 10 m (the key diagnostic region 27 is composed of ten consecutive wire sections 26), and the section length Δs of the key diagnostic region 28 is 0.6 m, the total number of sections will be 207, which is approximately 62% of the data volume compared to the aforementioned divisions. This concludes the explanation of the wire section 26 and the key diagnostic region 27. The content of each step (S110) to (S150) will be described in detail below.

In the preliminary diagnosis process (S110) illustrated in Figure 2, the calculation device 4 sets a number of wire sections 26 divided at equal intervals on the wire rope 20, and then performs data processing to diagnose each of the multiple wire sections 26 based on data for each of the multiple wire sections 26 that fluctuates due to the movement of the suspension body 11. The diagnosis method used in this process can be any of various known wire rope 20 diagnosis methods.

In the step (S120) of determining whether a predetermined period has elapsed, the computing device 4 performs data processing to compare the elapsed time during which the preliminary diagnosis process (S110) is repeated with the predetermined period and determine whether the elapsed time exceeds the predetermined period. The predetermined period can be set arbitrarily, but examples include the period for each working day of the crane 10, or the period from the start to the end of multiple scheduled loading and unloading operations.

In the step (S130) of identifying the key diagnosis areas 27, the calculation device 4 performs data processing to identify, among the numerous wire sections 26, those wire sections 26 that have a higher impact on the diagnosis of the wire rope 20 than a standard, as key diagnosis areas 27, based on data for each of the numerous wire sections 26 that fluctuates due to the movement of the suspending body 11 during a predetermined period. The data for each of the numerous wire sections 26 during the predetermined period can be the data and diagnosis results used in the preliminary diagnosis process (S110) that was repeatedly performed until the predetermined period has elapsed. The data for each of the numerous wire sections 26 during the predetermined period is the data at the end of the predetermined period.

The degree of influence indicates the degree to which the diagnosis result of the wire rope 20 is affected. When diagnosing the wire rope 20, it is determined that the wire rope 20 needs to be replaced if damage progresses to the point that there is a risk of breakage, so that even a single breakage does not occur. Therefore, in wire sections 26 with a low degree of influence, damage progresses slowly and is unlikely to break first even if the damage progresses further. On the other hand, in wire sections 26 with a high degree of influence, damage progresses quickly and is likely to break first if the damage progresses further. Therefore, the degree of influence can be determined according to the degree of damage progression. The degree of damage progression can be determined by the diagnosis in the preliminary diagnosis process (S110).

As indicators of the degree of impact, data and diagnostic results used in various known diagnostic methods used in the preliminary diagnosis process (S110) can be used. Specifically, as indicators of the degree of impact, the number of sheave passes for each of the multiple wire sections 26 during a specified period, the cumulative damage level, and the rope diameter can be used, which indicate the degree of damage progression. As indicators of the degree of impact, any one of the number of sheave passes, the cumulative damage level, and the rope diameter may be used, but two or all of these may also be used. The number of sheave passes indicates the total number of times the wire section 26 passes through the sheave. Because damage occurs to the wire section 26 each time it passes through one of the sheaves 21-25, the number of sheave passes is positively correlated with the degree of impact. The cumulative damage level, which will be described later, indicates the degree of damage accumulated in the wire section 26 and is calculated based on the number of sheave passes and the tension acting on the wire rope 20 during the pass. Because a higher cumulative damage level indicates more advanced damage progression, the cumulative damage level is positively correlated with the degree of impact. The rope diameter indicates the rope diameter for each wire section 26 and is negatively correlated with the cumulative damage level. Therefore, the rope diameter is negatively correlated with the impact level. It is desirable to use either the cumulative damage level or the rope diameter as an indicator of the impact level. Using the cumulative damage level or the rope diameter as an indicator of the impact level is advantageous for improving the accuracy of identifying the key diagnosis area 27. On the other hand, the cumulative damage level and rope diameter require a high calculation load, increase the effort required for measurement, or take a long time to measure. Therefore, using the number of sheave passes as an indicator of the impact level is advantageous for simplifying the preliminary diagnosis process (S110).

The standard for the degree of impact can be set arbitrarily and may be either an absolute evaluation or a relative evaluation. When using absolute evaluation, the standard is a fixed value set according to the length of a predetermined period based on knowledge gained in advance from data from numerous experiments and tests, or the accumulation of computer simulation results. When using relative evaluation, the standard is a variable value set based on the impact index for each of many wire sections 26. The standard for relative evaluation can be the mean, median, or intermediate value of the index multiplied by a positive coefficient greater than 1. The standard for relative evaluation can also be the maximum value of the index multiplied by a positive coefficient less than 1. Furthermore, in relative evaluation, multiple wire sections 26 with the highest index, including the maximum index, can be considered to be higher than the standard.

Figure 4 shows the frequency distribution of the number of sheave passes for each wire section 26. While a line graph is used in Figure 4, a histogram may also be used. na indicates the reference value for absolute evaluation set according to the length of a specified period. nb indicates the reference value for relative evaluation calculated by multiplying the maximum value of the index by a positive coefficient smaller than "1." nm indicates the maximum value of the index. Depending on the setting of the impact criteria, no key diagnostic area 27 may be identified for a single wire rope 20, or multiple key diagnostic areas 27 may be identified for a single wire rope 20. Furthermore, the number of wire sections 26 included in the key diagnostic area 27 may be excessive or insufficient. It is sufficient for the key diagnostic area 27 to include at least one wire section 26 with an impact level higher than the criteria, but it is preferable for it to be a section where multiple wire sections 26 are lined up in a row. Therefore, it is preferable for the impact criteria to be based on the extreme values of the index. For example, when the number of sheave passes or the cumulative damage level is used as the index, the impact standard is set based on the maximum value of the sheave pass or the cumulative damage level. When the rope diameter is used as the index, the impact standard is set based on the minimum value of the rope diameter. In this way, by basing the impact standard on the extreme values of the index, at least one key diagnostic area 27 can be identified for a single wire rope 20, increasing the likelihood that the number of wire sections 26 included in the identified key diagnostic area 27 will be an appropriate number. In Figure 4, the top ten wire sections 26 that include the maximum number of sheave passes are identified as key diagnostic areas 27.

In the main diagnosis process (S140) illustrated in Figure 2, the calculation device 4 sets a key diagnosis area 27 for the wire rope 20, and then performs data processing to diagnose the remaining wire sections 26 and key diagnosis areas 27, excluding the key diagnosis areas 27 from the numerous wire sections 26, based on data for each of the numerous wire sections 26 that fluctuates due to the movement of the suspending body 11. The diagnosis method in this diagnosis process can be any of the various well-known wire rope 20 diagnosis methods used in the preliminary diagnosis process. However, in this diagnosis process, the focus of diagnosis on the key diagnosis areas 27 is higher than the focus of diagnosis on the remaining wire sections 26.

The degree of importance of a diagnosis indicates the degree of computational load on the central processing unit 5 during the diagnosis and the degree to which the storage area of the auxiliary memory unit 7 is monopolized by data required for the diagnosis. When diagnosing a wire section 26 with a low degree of importance, the degree of computational load on the central processing unit 5 is low, and the degree to which the storage area of the auxiliary memory unit 7 is monopolized by data required for the diagnosis is also low. On the other hand, when diagnosing a key diagnosis area 27 with a high degree of importance, the degree of computational load on the central processing unit 5 is high, and the degree to which the storage area of the auxiliary memory unit 7 is monopolized by data required for the diagnosis is also high. Specifically, in this embodiment, the degree of importance of the diagnosis is increased by providing a large number of key diagnosis sections 28 in the key diagnosis area 27 with a section length Δs shorter than the section length ΔS of the wire section 26. Even when the same diagnostic method is used, shorter section lengths are more advantageous for improving diagnostic accuracy.

In this diagnosis process (S140), it is desirable to transfer the data for each of the numerous wire sections 26 obtained in the preliminary diagnosis process (S110) to the key diagnosis areas 27, and diagnose the wire rope 20 while also taking into account damage during the specified period since the preliminary diagnosis process. Specifically, in the example shown in Figure 3, the data for section numbers 101 to 110 obtained in the preliminary diagnosis process is transferred to section numbers 201 to 217 of the key diagnosis section 28 (for example, the data for section number 101 is transferred to section numbers 201 to 202). In this way, utilizing the data obtained in the preliminary diagnosis process (S110) in the diagnosis in this diagnosis process (S140) is advantageous in improving the accuracy of the diagnosis of the wire rope 20 in this diagnosis process.

In the step (S150) of determining whether the wire rope 20 has been replaced, the arithmetic unit 4 executes data processing to determine whether the wire rope 20 has been replaced. Replacement of the wire rope 20 is determined by repeating this diagnostic process (S140), determining that replacement of the wire rope 20 is necessary, and then actually replacing the wire rope 20 and inputting the replacement information into the diagnostic program 30.

As described above, the diagnosis results of the identified key diagnosis area 27 have a significant impact on the diagnosis of the wire rope 20. Therefore, according to this embodiment, by focusing on diagnosing the key diagnosis area 27, the accuracy of the diagnosis of the wire rope 20 can be improved, similar to a method that focuses on diagnosing the entire wire rope 20. Furthermore, because the key diagnosis area 27 is only a portion of the wire rope 20, the calculation load can be reduced and the amount of data occupying memory space can be suppressed compared to a method that focuses on diagnosing the entire wire rope 20. In this way, this embodiment is configured to be able to perform high-precision diagnosis of the wire rope 20, while also reducing the calculation load and suppressing the amount of data occupying memory space.

In this embodiment, the key diagnosis area 27 is identified as an area where multiple wire sections 26 are lined up in succession, which is advantageous in avoiding missing a diagnosis of an area that requires focused diagnosis. The number of multiple wire sections 26 included in the key diagnosis area 27 can be set arbitrarily, but it is preferable that the total length of the key diagnosis area 27 is between 10% and 30% of the total length of the wire rope 20, or between 5 and 20 times the section length ΔS of the wire section 26. If the total length of the key diagnosis area 27 is too short, there is a high possibility that a location that affects the diagnosis of the wire rope 20 will be missed in the focused diagnosis, and if the total length is too long, there is a high possibility that the calculation load and the amount of data occupying memory space will increase.

The above describes an embodiment of the present invention, but the wire rope diagnostic method, diagnostic system 1, and diagnostic program 30 of the present invention are not limited to a specific embodiment, and various modifications and variations are possible within the scope 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 also 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 suspended body of the present invention.

Methods for increasing the priority of the diagnosis of the key diagnosis area 27 are not limited to methods for setting multiple key diagnosis sections 28 in the key diagnosis area 27, each with a section length Δs shorter than the section length ΔS of the wire section 26. Another example of a method for increasing the priority is to diagnose only the identified key diagnosis area 27. Diagnosing only the key diagnosis area 27 cannot address situations in which the remaining wire section 26, excluding the key diagnosis area 27, has a greater influence when the loading status of the crane 10 differs between the preliminary diagnosis process (S110) and the main diagnosis process (S140). Therefore, in methods for diagnosing only the key diagnosis area 27, it is desirable to make the overall length of the key diagnosis area 27 longer than in the previously described embodiment. For example, it is advisable to make the section length Δs longer than in the previously described embodiment or to increase the number of key diagnosis sections 28. Another example of a method for increasing the level of importance is to diagnose only the identified key diagnosis area 27 through real-time processing while the crane 10 is operating, and then diagnose the remaining wire section 26 excluding the key diagnosis area 27 through batch processing while the crane 10 is at rest. Furthermore, the method for increasing the level of importance may be a combination of multiple of the example methods. Whichever of the example methods for increasing the level of importance is used, it is possible to reduce the computational load and suppress the amount of data occupying memory space.

The loading conditions in the preliminary diagnosis process (S110) may differ from those in the main diagnosis process (S140). In such cases, the influence of the remaining wire section 26 excluding the key diagnosis area 27 may become greater than the influence of the identified key diagnosis area 27 during the repeated process of the main diagnosis process (S140). Therefore, it is recommended to identify a new key diagnosis area 27 during the repeated process of the main diagnosis process (S140) using a method similar to that used in the preliminary diagnosis process (S110). As a result, if the influence of the remaining wire section 26 excluding the key diagnosis area 27 becomes greater than the influence of the identified key diagnosis area 27 during the repeated process of the main diagnosis process (S140), the wire section 26 with the increased influence can be identified as the new key diagnosis area 27 and can be diagnosed intensively. Note that when a new key diagnosis area 27 is identified, the previous key diagnosis area 27 is returned to the wire section 26. At this time, since many key diagnosis sections 28 are returned to one wire section 26, the diagnosis result of this diagnosis step (S140) for the wire section 26 at the time of return should be the average, median, or intermediate value of the diagnosis results for each of the many key diagnosis sections 28 at the time of return.

The preliminary diagnosis process (S110) can be carried out by utilizing periodic inspections of the wire rope 20. During periodic inspections of the wire rope 20, the rope diameter of each of a large number of wire sections 26 can be measured, and the measured rope diameter can be used as an indicator of the degree of influence to identify the areas 27 that require diagnosis. In this way, the diagnosis method for the wire rope 20 in the preliminary diagnosis process (S110) and the diagnosis method for the wire rope 20 in the periodic diagnosis process (S140) may be different.

The section number M in the main diagnosis process (S140) may be set so that the value increases from either one end or the other end of the wire rope 20 to the other, without leaving any missing numbers. In this case, the section number M used in the preliminary diagnosis process (S110) and the section number M in the main diagnosis process (S140) will be offset by the section number M assigned to the key diagnosis section 28, with the key diagnosis area 27 as the boundary. Therefore, when transferring the data obtained in the preliminary diagnosis process (S110) to the main diagnosis process (S140), it is advisable to take this offset into consideration.

The key diagnostic area 27 may be different for each wire rope 20. Furthermore, one key diagnostic area 27 may be set for each wire rope 20, but if one wire rope 20 passes through multiple sheaves 21-25, multiple key diagnostic areas 27 may be set for one wire rope 20. Setting multiple key diagnostic areas 27 is advantageous in avoiding missing diagnostics of areas that require priority diagnostics.

In the above-described embodiment, various known methods can be used to diagnose the wire rope 20. However, these known methods have room for improvement in order to accurately diagnose when to replace the wire rope 20, taking into account fluctuations in tension caused by the swing of the suspension body 11. Therefore, the method described in detail below is desirable as a method for diagnosing the wire rope 20 used in the preliminary diagnosis process (S110) and the main diagnosis process (S140).

Figure 5 shows an example of the diagnostic method and procedures executed by the diagnostic program 30. First, the tension Wt and position (lt, ht) are acquired for each first cycle t (S210, S220). Next, once the time-series data 31 is stored in the auxiliary memory unit 7 of the calculation device 4 (S230), the diagnostic program 30 causes the calculation device 4 to execute each procedure (S240-S270). Finally, once the diagnosis result indicating the time to replace the wire rope 20 is output to the output unit 9, the program returns to the start and executes each procedure again. These procedures are repeated while the crane 10 is moving the suspended body 11. Furthermore, the data accumulated through the repetitions is reset when the wire rope 20 is replaced and is accumulated again when the crane 10 begins moving the suspended body 11 after the wire rope 20 is replaced. The content of each step (S210) to (S280) is described in detail below. The passing section 29 shown in Figure 1 indicates the wire section 26 or key diagnostic section 28 that passes through one of the sheaves 21 to 25 while the suspending body 11 is moving, and at least a portion of the section is in contact with the sheave and is bent by the sheave.

In the step (S210) of acquiring the tension Wt, the tension Wt acting on the wire rope 20 is acquired by the tension acquisition device 2 for each first period t. In the step (220) of acquiring the position (lt, ht), the position (lt, ht) of the hanging body 11 is acquired by the position acquisition devices 3a and 3b 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 29 to pass the sheave (the time from when a wire section 26 starts passing the sheave to when that passage ends). The first period t is preferably based on the wire section 26, but can also be based on the key diagnosis section 28. The first period t is set based on 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. Furthermore, the first period t is preferably shorter than the period of the swing of the suspending body 11 when viewed as a simple pendulum. Because the period of the swing of the suspending body 11 varies depending on the distance between the suspending body 11 and the trolley, the first period t can be set shorter than the period of the swing of the suspending body 11 that is most dominant in the loading/unloading cycle, or shorter than the period of the swing of the suspending body 11 that is longest in the loading/unloading cycle. By making the first period t shorter than the period of the swing of the hanging body 11, the tension acquisition device 2 can more accurately acquire the tension acting on the wire rope 20 due to the swing of the hanging body 11. It is desirable to synchronize the sampling periods 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 also be set to a period shorter than the first period t.

In the step (S230) of storing the time series data 31 shown in FIG. 6, the time series data 31, which is a chronological arrangement of the tension Wt and position (lt, ht) 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 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.

The time series data 31 may have a data structure in which newly acquired tension Wt and position (lt, ht) are added to the data up to the previous cycle (t-1) and updated sequentially. Alternatively, the time series data 31 may have a data structure consisting of multiple 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 sequentially added and updated for each first cycle t, the amount of data increases over time. Therefore, to prevent the time series data 31 from becoming too large, grouping the time series data 31 for each second cycle T facilitates data management and is advantageous for deleting unnecessary data from the auxiliary memory unit 7 to prevent storage space from becoming full. The second cycle T is a preset, fixed cycle in which the first cycle t is repeated multiple times.

In step S240 of identifying the passing section 29 and the tensile stress δt [kgf/m ² ], the calculation device 4 identifies each passing section 29 based on the time-series data 31, and then performs data processing to identify the tensile stress δt acting on the passing section 29. The passing section 29 indicates the wire section 26 or key diagnosis section 28 with section number M that passes through one of the sheaves 21 to 25 while the suspension body 11 is moving, and the section number M is identified for each sheave number i. At least a portion of the passing section 29 is in contact with the sheave and is bent by the sheave. Specifically, in this step, the calculation device 4 identifies which wire section 26 or key diagnosis section 28 with section number M is the passing section 29 for each first period t based on the position (lt, ht) of the time-series data 31, and then 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 passage section time series data 32 to identify the tensile stress δt acting on the passage section 29 using the change in the section number M of the passage section 29 as a criterion for determination.

The method for identifying the passing section 29 from the position (lt, ht) of the time-series data 31 is not particularly limited, as long as it is possible to identify the passing section 29 for each sheave number i. An example of this method is shown below. First, a predetermined position of the contact area between the wire rope 20 and the sheave when the position (lt, ht) of the suspending body 11 is the base point is obtained in advance. The predetermined position can be selected arbitrarily within the range of the contact area, such as the midpoint of the contact area. The wire section 26 or key diagnostic section 28 with section number M, which exists within the range from the start position to the end position, becomes the passing section 29 when the suspending body 11 is located at the base point. Next, the predetermined position is set as the initial value, and the position (lt, ht) is substituted as a variable 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 wire section 26 or key diagnosis section 28 that exists within the range from the start position to the end position obtained is identified as the passing section 29, and its section number M is identified. Note that when the first period t is set based on the wire section 26, there may be more than one key diagnosis section 28 identified as the passing section 29.

The passing section time series data 32 illustrated in FIG. 7 is a data set in which the section number M of the passing section 29 for each sheave number i and the tension Wt for each first period t are arranged in chronological order for each first period t. Similar to the time series data 31, 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 consisting of multiple second-period data groups grouped for each second period T; or a data structure consisting of one second-period data grouped 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 consisting of multiple second-period data groups grouped for each second period T.

The second cycle T is a preset fixed cycle in which the first cycle t is repeated multiple times. The second cycle T is preferably a period in which, based on the wire section 26, the section number (M-1) identified as the passing section 29 switches to the next section number M at least once during that period. Note that, like the first cycle t, the second cycle T can also be based on the key diagnostic section 28. If the number of switches is one or more, the calculation device 4 can process data for at most two cycles of the second cycle T to output the diagnosis results for the wire rope 20, thereby reducing the amount of space required by the auxiliary memory unit 7. Furthermore, because the greater the number of switches, the greater the amount of data, so the number of switches is preferably five or less.

An example of a method for determining the tensile stress δt acting on the passing section 29 is to determine the tension acting on the passing section 29 (half the tension acquired by the tension acquisition device 2) and divide the determined tension by the cross-sectional area A of the wire rope 20 to determine the resulting value as the tensile stress δt. Examples of methods for determining the tension acting on the passing section 29 include calculating the average or median of the tension Wt for each first cycle t from the start to the end of the sheave's passage through the passing section 29, determining the tension Wt when a predetermined position in the passing section 29 (e.g., the center position of the passing section 29) passes the sheave, and determining the tension Wt when the section number M of the passing section 29 changes to the next number (M+1). While adopting the average or median of multiple tensions Wt increases the computational load on the computing device 4, it is advantageous for more accurately determining the tensile stress δt acting on the passing section 29. On the other hand, adopting a method for selecting one of multiple tensions Wt reduces the computational load on the computing device 4. Therefore, it is desirable that the method for identifying the tension acting on the passing section 29 be selectable by the diagnostic program 30 and changeable as appropriate depending on the situation.

In the step (S150) of calculating the degree of micro-damage Dj, the calculation device 4 performs data processing to calculate the degree of micro-damage Dj that has occurred in the passing section 29 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 previously determined numerical value into the following formula (1).

The previously determined numerical values are input via 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 differ for each sheave.

The above formula (1) is Niemann's empirical formula. Therefore, the number of times to failure Nj obtained from formula (1) indicates the number of times that a passing section 29 can pass through the sheave before breaking if a specified tensile stress δt continues to act on the passing section 29. The above formula (2) indicates that the microdamage level Dj is the reciprocal of the number of times to failure Nj. The damage level is a value calculated using the known cumulative fatigue damage law, using an S-N diagram and stress waveform to add up the effects of each stress (the value obtained by dividing the number of times a stress amplitude actually occurred by the number of repetitions of that stress amplitude until breaking). In other words, the microdamage level Dj indicates the degree of damage caused to a passing section 29 when the passing section 29, under the action of tensile stress δt, passes through the sheave once.

In the step (S160) of calculating the cumulative damage level Ds, the calculation device 4 performs data processing based on the calculated micro-damage level Dj to calculate the cumulative damage level Ds (ΣDj) obtained by sequentially accumulating the micro-damage levels Dj for each wire section 26 and key diagnosis section 28 from the start of use of the wire rope 20. Specifically, the calculation device 4 creates cumulative damage level data 33, as shown in Figure 8. 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.

The cumulative damage data 33 consists of a time-series micro-damage degree Dj for each section number M of the wire section 26 and the key diagnosis section 28, a cumulative damage degree Ds obtained by sequentially accumulating these micro-damage degrees Dj, and the number of sheave passes n. The cumulative damage data 33 is stored in the auxiliary memory unit 7 and is updated each time the calculation device 4 calculates a micro-damage degree Dj. It is reset (initialized) when the wire rope 20 is replaced. It is desirable that the cumulative damage data 33 be configured to identify the micro-damage degree Dj and the sheave number i in which the micro-damage degree Dj occurred. Identifying the sheave number i makes it possible to understand the history of the micro-damage degree Dj for each sheave number i. The number of passes n is the number of times the wire section 26 and key diagnosis section 28 with section number M were identified as the pass section 29, indicating the number of times the micro-damage degree Dj occurred. The number of passes n is not required, but may also be used in diagnosing the replacement timing, as described below. The time-series minute damage level Dj of the cumulative damage level data 33 may be deleted after calculating the cumulative damage level Ds, but if it is left intact it can be used to analyze damage to the wire rope 20.

In the replacement timing diagnosis step (S270), the calculation device 4 performs data processing to diagnose the replacement timing of the wire rope 20 based on the calculated micro-damage level Dj. Indicators for diagnosing the replacement timing of the wire rope 20 include the lifespan of the wire rope 20, the period until the end of that lifespan, and the number of times the wire rope can pass through the sheave before the end of that lifespan (hereinafter referred to as the predicted remaining number of times). The wire rope 20 is considered to have broken when any one of the multiple wire sections 26 and multiple key diagnosis sections 28 breaks. Therefore, the appropriate time to replace the wire rope 20 is before at least one of the multiple wire sections 26 and multiple key diagnosis sections 28 breaks. According to the known cumulative fatigue damage law, when any of the cumulative damage levels Ds for each section number M reaches "1," either the wire section 26 or the key diagnosis section 28 will break. Therefore, the cumulative damage level Ds corresponds to the lifespan of the wire rope 20. Furthermore, the transition of the cumulative damage level Ds for each section number M makes it possible to predict the predicted period until the cumulative damage level Ds reaches "1" (until the end of its life), and this predicted period corresponds to the period until the end of the life of the wire rope 20. Furthermore, the reciprocal of the cumulative damage level Ds can be regarded as the predicted number of times the wire section 26 or the key diagnosis section 28 can pass through the sheave before breaking, and therefore corresponds to the predicted remaining number of times. Therefore, it is possible to diagnose the replacement time for the wire rope 20 based on the cumulative damage level Ds for each section number M.

To determine when to replace the wire rope 20 based on its lifespan, the largest cumulative damage level Dsm is identified from the cumulative damage levels Ds for each section number M, and that maximum cumulative damage level Dsm is used as an index for determining when to replace the wire rope 20. When the maximum cumulative damage level Dsm reaches "1" (Dsm ≥ 1), the wire rope 20 may be diagnosed as reaching the end of its lifespan and therefore needing to be replaced. However, it is preferable to determine when to replace the wire rope 20 before the wire rope 20 breaks. Therefore, it is preferable to determine when to replace the wire rope 20 when the maximum cumulative damage level Dsm reaches a damage level threshold Da, which is set to a value less than "1" (Dsm ≥ Da). The damage level threshold Da can be set to any value less than "1" via the input unit 8 for the diagnostic program 30. For example, if the time to replace the wire rope 20 is determined when the wire rope 20 has reached 70% of its lifespan, the damage threshold Da is set to "0.7".

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

To diagnose when to replace the wire rope 20 based on the predicted remaining number of cycles, the reciprocal of the cumulative damage level Ds can be used as an indicator for diagnosing when to replace 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 better to calculate the cycle damage level Dcy per movement cycle of the suspension body 11 for each section number M based on the cumulative damage level Ds, identify the largest maximum cycle damage level Dcym from 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 indicator 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, loading the container onto the ship, and then moving the suspending device from the target location to the predetermined location and returning it (and the reverse cycle is also included). The damage level per cycle Dcy 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 time the wire rope 20 began to be used until the cumulative damage level Ds was calculated.

The wire rope 20 may be diagnosed as needing replacement when the minimum predicted cycle count Nsm reaches "0" (Nsm = 0), i.e., when there are no more predicted cycles remaining. However, it is preferable to determine the replacement time before the wire rope 20 breaks. Therefore, it is advisable to diagnose the wire rope 20 as needing replacement when the value obtained by multiplying the minimum predicted cycle count Nsm by a cycle coefficient k set to a value less than "1" reaches "0" (kNsm = 0). The cycle coefficient k can be set to any value less than "1" by the input unit 8 for the diagnostic program 30. For example, if the wire rope 20 is diagnosed as needing replacement when the minimum predicted cycle count Nsm reaches 70%, the cycle coefficient k is set to "0.7".

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

When the time for replacement of the diagnosed wire rope 20 approaches, the operator or manager of the crane 10 can 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 unit 9 of the computing device 4, or lighting a warning lamp or sounding a warning sound using a warning device.

As described above, the exemplary wire rope 20 diagnostic method accumulates the degree of minute damage Dj that occurs each time the passing section 29 passes through the sheave, and diagnoses when the wire rope 20 should be replaced. Therefore, even if the tensile stress δt acting on the wire rope 20 fluctuates slightly, it is possible to diagnose when the wire rope 20 should be replaced by taking into account the damage that corresponds to that fluctuation. This is advantageous for increasing the accuracy of diagnosing when the wire rope 20 should be replaced, ensuring safety by ensuring that the wire rope 20 is replaced before it breaks, and reducing costs by reducing the frequency of unnecessary wire rope 20 replacements.

Furthermore, according to the example diagnostic method for the wire rope 20, by setting the resolution to a first period t that is shorter than the period until the passing section 29 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 cumulative damage level Ds, which is the cumulative level of minute damage Dj each time the passing section 29 passes through the sheave, it is possible to perform a more accurate diagnosis than conventional methods that use the number of times the wire rope passes through the sheave in a specified period as a basis.

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

1 diagnostic system 2 tension acquisition devices 3a, 3b position acquisition device 4 calculation device 10 crane 11 hanging body 12 drum 20 wire ropes 21 to 25 sheave 26 wire section 27 key diagnosis part 28 key diagnosis section 29 passing section 30 diagnostic program t first cycle T second cycle M section number
Wt Tension (lt, ht) Position Dj Fine damage degree Ds Cumulative damage degree

Claims (9)

A diagnostic method for a wire rope in which a number of wire sections divided at equal intervals are set and a suspended body is moved by winding or unwinding a drum via at least one or more sheaves,
A wire rope diagnosis method characterized by using a computing device to process at least one of the number of times the sheave passes, the cumulative damage level, and the rope diameter as data for each of the multiple wire sections that fluctuates due to the movement of the hanging body over a specified period, thereby identifying, among the multiple wire sections, wire sections that have a higher impact on the diagnosis of the wire rope than a standard as key diagnosis areas, and setting, at the identified key diagnosis areas, multiple key diagnosis areas that are equally spaced using section lengths shorter than the section length of the wire section, thereby giving a higher priority to the diagnosis of the key diagnosis areas than to the remaining wire sections excluding the key diagnosis areas from among the multiple wire sections. A diagnostic method for a wire rope in which a number of wire sections divided at equal intervals are set and a suspended body is moved by winding or unwinding a drum via at least one or more sheaves,
a wire rope diagnosis method comprising: processing, by a computing device, at least one of the number of passes of the sheave, the cumulative damage level, and the rope diameter as data for each of the multiple wire sections that fluctuates due to movement of the hanging body during a predetermined period; identifying, among the multiple wire sections, wire sections that have a higher degree of influence on the diagnosis of the wire rope than a standard as key diagnosis areas; setting, in the key diagnosis areas, multiple key diagnosis areas that are equally spaced using section lengths that are shorter than the section lengths of the wire sections; and, during operation of a crane or elevator equipped with the hanging body, processing, by the computing device, at least one of the number of passes of the sheave, the cumulative damage level, and the rope diameter as data for each wire section of the key diagnosis areas that fluctuates due to movement of the hanging body after the key diagnosis areas have been identified, diagnosing only the key diagnosis areas and assigning a higher priority to the diagnosis of the key diagnosis areas than to the remaining wire sections excluding the key diagnosis areas from among the multiple wire sections. A wire rope diagnosis method as described in claim 1 or 2 , wherein the key diagnosis area is a section where multiple wire sections are lined up in succession, including wire sections among the multiple wire sections that have a higher impact on the diagnosis of the wire rope than a standard. The wire rope diagnosis method according to claim 3 , wherein the wire section having a degree of influence higher than the criterion is identified based on extreme values of the data. The wire rope diagnosis method according to claim 1 or 2 , wherein the data for the predetermined period of the wire section identified as the key diagnosis portion is also used in diagnosing the key diagnosis portion. A diagnostic system having a computing device for diagnosing a wire rope in which a number of wire sections divided at equal intervals are set and which moves a suspended body by winding or unwinding a drum via at least one or more sheaves,
The calculation device performs data processing to identify, among the multiple wire sections, wire sections that have a higher impact on the diagnosis of the wire rope than a standard as key diagnosis areas based on at least one of the number of times the sheave passes, the cumulative damage level, and the rope diameter as data for each of the multiple wire sections that fluctuates due to the movement of the hanging body during a specified period, and data processing to set, at the identified key diagnosis areas, multiple key diagnosis areas that are equally spaced using section lengths shorter than the section length of the wire section, thereby increasing the importance of diagnosis of the key diagnosis areas compared to the importance of diagnosis of the remaining wire sections excluding the key diagnosis areas from the multiple wire sections. A diagnostic system having a computing device for diagnosing a wire rope in which a number of wire sections divided at equal intervals are set and which moves a suspended body by winding or unwinding a drum via at least one or more sheaves,
The calculation device performs data processing to identify, among the multiple wire sections, wire sections that have a higher degree of influence on the diagnosis of the wire rope than a standard as key diagnosis areas based on at least one of the number of times the sheave has passed, the cumulative damage level, and the rope diameter as data for each of the multiple wire sections that fluctuates due to the movement of the hanging body during a predetermined period, and data processing to set, in the identified key diagnosis areas, multiple key diagnosis areas that are divided at equal intervals using section lengths that are shorter than the section lengths of the wire sections,
A wire rope diagnostic system characterized in that, during operation of a crane or elevator equipped with the hanging body, data processing is performed to give a higher priority to the diagnosis of the key diagnosis area than to the diagnosis of the remaining wire sections excluding the key diagnosis area from among the multiple wire sections, and to diagnose only the key diagnosis area based on at least one of the number of times the sheave has passed, the cumulative damage level, and the rope diameter, which are data for each of the multiple wire sections that change due to the movement of the hanging body after the key diagnosis area has been identified. A wire rope diagnostic program that causes a computing device to diagnose a wire rope that has a number of equally spaced wire sections set therein and moves a suspended body by winding or unwinding it through at least one or more sheaves,
A wire rope diagnostic program characterized by having the computing device execute the following steps: identify, among the multiple wire sections, wire sections that have a higher impact on the diagnosis of the wire rope than a standard based on at least one of the number of times the sheave has passed, the cumulative damage level, and the rope diameter, as data for each of the multiple wire sections that fluctuates due to the movement of the hanging body during a specified period; and set, at the identified multiple key diagnostic sections, multiple key diagnostic sections that are equally spaced using section lengths shorter than the section length of the wire section, thereby increasing the importance of the diagnosis of the key diagnostic sections compared to the importance of the diagnosis of the remaining wire sections excluding the key diagnostic sections from among the multiple wire sections. A wire rope diagnostic program that causes a computing device to diagnose a wire rope that has a number of equally spaced wire sections set therein and moves a suspended body by winding or unwinding it through at least one or more sheaves,
a procedure in which the computing device identifies, among the multiple wire sections, wire sections that have a higher degree of influence on the diagnosis of the wire rope than a standard as key diagnosis areas based on at least one of the number of times the sheave passes, the cumulative damage level, and the rope diameter as data for each of the multiple wire sections that fluctuates due to the movement of the hanging body during a predetermined period;
a step of setting a number of priority diagnosis sections at equal intervals in the identified priority diagnosis region using sections having lengths shorter than the section length of the wire section;
A wire rope diagnostic program characterized by executing, during operation of a crane or elevator equipped with the hanging body, a procedure for increasing the importance of diagnosing the key diagnosis area from among the multiple wire sections compared to the importance of diagnosing the remaining wire sections excluding the key diagnosis area, by diagnosing only the key diagnosis area based on at least one of the number of times the sheave has been passed, the cumulative damage level, and the rope diameter, which are data for each of the multiple wire sections that change due to the movement of the hanging body after the key diagnosis area has been identified.