JP7764261B2 - Maintenance management method and maintenance management system - Google Patents

Description

The present invention relates to a maintenance management method and a maintenance management system.

With the recent expansion of mail-order businesses, large logistics warehouses are required to move large quantities of cargo in a short period of time. For this reason, automatic guided vehicles (AGVs) that automatically transport cargo have been used in logistics-related facilities such as large logistics warehouses. For example, in large logistics warehouses with an area of over 10,000 ^m2 , hundreds of AGVs operate almost nonstop around the clock, except for scheduled maintenance periods. Each AGV can travel several thousand kilometers per month, and in some cases, more than 10,000 kilometers per year.

The surface of AGV casters is made from resin materials such as nylon or urethane. Casters are made in a variety of hardness and shapes. The amount of caster wear varies depending on the conditions of use of the AGV. The longer the travel distance, the greater the caster wear; the harder the caster material, the less wear there is relative to the travel distance. To reduce caster wear, select casters made from a hard material. However, if casters made from a hard material are selected, the vibration transmitted to the AGV will increase, and there is a risk of increased damage to the slab (floor) surface.

Furthermore, while using casters made of soft materials reduces vibrations transmitted to the AGV, they may also increase wear and the need for more frequent replacement. Therefore, when selecting casters, it is desirable to have test data in advance for various combinations that replicate the AGV's operating conditions. However, as mentioned above, an AGV in operation travels several thousand kilometers per month, and verifying these through replication tests of many combinations poses the challenge of requiring time and effort. For example, assuming a repeated back-and-forth running test using a 50 cm (25 cm in each direction) caster using a 30 cm long concrete specimen, 1 km would require 2,000 back-and-forth runs, and 100 km would require 200,000 back-and-forth runs. Assuming one back-and-forth takes 10 seconds, a 100 km run would take approximately 23 days. Taking into account measurements and equipment maintenance along the way, this would take approximately one month.

For example, Patent Document 1 describes a method for detecting wheel abnormalities based on measured values of wheel wear on railway vehicles. Patent Document 2 describes a method for predicting the state of wheel wear based on measured values of wheel wear on railway vehicles. Patent Document 3 describes a method for estimating the amount of caster wear on an automated guided vehicle based on detected values of the caster rotation speed and linear travel distance, and the initial diameter of the caster.

Japanese Patent Application Laid-Open No. 2021-043148 Japanese Patent Application Laid-Open No. 2020-183767 Japanese Patent Application Laid-Open No. 2007-022282

When performing regular maintenance on AGVs, casters that have worn beyond the standard are replaced. Therefore, when using AGVs, it is desirable to monitor the condition of casters, which are routinely replaced parts, predict when they will need to be replaced due to wear, and create a future maintenance plan that forecasts order quantities and inventory levels.

The methods described in Patent Documents 1 and 2 detect wheel abnormalities and wear based on the relationship between the rail and the wheels. When applied to AGVs, the application conditions must be changed, such as different floor conditions and different wheel types. The method described in Patent Document 3 estimates the current amount of wear on the AGV's casters, but does not grasp the amount of wear in the future.

The present invention aims to provide a maintenance management method and a maintenance management system that predicts the future wear of casters over long distances based on test results for casters travelling only a short distance.

One aspect of the present invention is a maintenance management method comprising the steps of: conducting a running test of a mobile body equipped with casters by varying test conditions including the applied load, the type of caster, and the type of floor surface; measuring the amount of wear on the casters and calculating a relationship between the amount of wear and the distance traveled based on the obtained measurements; calculating the future amount of wear on the casters equipped on the mobile body while it is in operation based on the relationship; and generating a maintenance plan for the mobile body based on the calculated future amount of wear.

According to the present invention, by obtaining measurements based on caster wear tests, it is possible to predict the amount of wear on the caster 10 over long travel distances based on short travel distances, significantly reducing measurement time and labor.

Furthermore, the relational equation of the present invention may be an approximation that linearly represents the relationship between the logarithm of the travel distance of the mobile body based on the test conditions and the logarithm of the wear amount of the caster, and the method may include a step of calculating parameters in the relational equation based on the measured values.

According to the present invention, the future wear of a caster can be easily calculated by regressing the relationship between the caster's travel distance and wear amount into a simple linear equation.

The present invention may also include a step of accumulating test results of the running tests based on different test conditions, a step of periodically measuring the operational wear of the casters attached to the moving body, and a step of adjusting the parameters based on the test results and the measured values of the operational wear.

According to the present invention, by measuring the amount of caster wear of an actually running vehicle at a specified timing, rather than just using the results of a running test, it is possible to adjust the parameters of the calculated relational equation and improve the accuracy of the predicted value.

The present invention may also include a step of conducting a running test of the caster for which information on the type is insufficient, and a step of estimating the type of the caster based on the test results.

According to the present invention, even when there is little information about a caster, it is possible to conduct a running test, obtain measurements, and compare the measurements with those of other casters, thereby estimating the type of caster based on similar data.

The present invention may also include a step of designing a new caster based on the test results and the amount of operational wear.

According to the present invention, the database of test results can be used to develop new caster products tailored to specific usage conditions, such as usage method and location.

One aspect of the present invention is a maintenance management system having a calculation unit that calculates a relationship between the amount of wear and the distance traveled based on measured values of the amount of wear of the casters obtained through running tests of a mobile body equipped with the casters, conducted under varying test conditions including the applied load, the type of caster, and the type of floor surface; calculates the future amount of wear of the casters equipped to the mobile body while it is in operation based on the relationship; and generates a maintenance plan for the mobile body based on the calculated future amount of wear.

According to the present invention, by obtaining measurements based on caster wear tests, it is possible to predict the amount of wear on the caster 10 over long travel distances based on short travel distances, significantly reducing measurement time and labor.

This invention makes it possible to estimate the future amount of wear on casters attached to a moving object.

1 is a diagram showing a configuration of a test device according to an embodiment of the present invention; FIG. 1 is a block diagram showing the configuration of a maintenance management system. FIG. 10 is a diagram showing the relationship between the travel distance of a caster and the amount of wear. FIG. 10 is a diagram showing the relationship between the travel distance of a caster and the amount of wear by an approximation formula. FIG. 10 is a diagram showing the relationship between the logarithm of the travel distance of a caster and the logarithm of the wear amount. 1 is a flowchart showing the flow of each step of a maintenance management method.

Embodiments of a maintenance management method and a maintenance management system according to the present invention will be described below with reference to the drawings. The maintenance management system supports the planning of periodic maintenance of casters on AGVs (mobile vehicles) based on the maintenance management method.

As shown in Figure 1, a running test is performed on the casters 10 used in AGVs using a testing device 100. The testing device 100 performs a running test that replicates the running of an AGV equipped with casters by changing test conditions, including, for example, the load, the type of caster 10, and the type of floor surface. During the running test, the running of the AGV is replicated, and the amount of wear on the casters 10 installed on the AGV is periodically measured.

The test device 100 includes, for example, a test stand 101 on which the caster 10 is placed, a running device 102 that causes the caster 10 to run back and forth on the test stand 101, a loading device 103 that applies a load to the caster 10, and a measuring device 104 connected to the running device 102. The test stand 101 has, for example, a plate-shaped test specimen made of the same material as the flooring on its surface. The running device 102 is, for example, a device that applies a reciprocating motion to the caster 10 based on rotational motion. For example, the running device 102 causes the caster 10 to reciprocate once with one rotation of the rotor 102R.

The rotor 102R is provided with a link device 102L having multiple link rods. The stroke of the link device 102L of the traveling device 102 is adjusted so that one round trip is, for example, 50 cm. The loading device 103 applies a load to the caster 10 from above, for example, using a weight. The configuration of the testing device 100 described above is one example, and any device configuration may be used as long as it is capable of measuring the amount of wear on the caster 10.

The measuring device 104, for example, detects the detection value of the encoder 102A that detects the number of rotations provided on the traveling device 102, calculates the travel distance of the caster 10 based on the detected value, and records the calculated value together with the time and number of reciprocations. When the travel distance of the caster 10 reaches a predetermined distance or a predetermined number of reciprocations, the outer diameter of the caster 10 is measured. The outer diameter of the caster 10 may be measured using a measuring tool such as a micrometer or calipers, or it may be calculated automatically based on the number of rotations and reciprocation distance after measuring the number of rotations of the caster 10.

The measurement device 104 is configured, for example, by an information processing device such as a personal computer, tablet terminal, or smartphone. The measurement device 104 may also be a server device connected to the network W described below.

The test device 100 allows for the collection of data indicating the degree of wear of the caster 10 under various conditions by changing test conditions, including the applied load, type of caster 10, and type of floor surface. The test data obtained from the running test is input into the maintenance management device 1 described below.

As shown in FIG. 2, the maintenance management device 1 is connected to the measuring device 104, for example, via a network W. The network W is composed of, for example, a public line, a LAN, a WAN, etc. The network W may also be composed of various types of lines, such as wired and wireless.

The maintenance management device 1 acquires test data from the measuring device 104, for example, via the network W. The maintenance management device 1 is configured, for example, as an information processing device such as a personal computer, tablet terminal, or smartphone. The maintenance management device 1 may also be a server device connected to the network W. The maintenance management device 1 may be configured to operate in conjunction with the measuring device 104 on the network W, or may be configured as an integral part of the measuring device 104.

The maintenance management device 1 includes, for example, an acquisition unit 2 that acquires measurement data from a measuring device 104. The acquisition unit 2 is, for example, a communications interface capable of sending and receiving data via a network W. The acquisition unit 2 stores the acquired data in a memory unit 4. The memory unit 4 is, for example, a non-temporary storage device configured using a hard disk drive (HDD), flash memory, etc. The measurement data stored in the memory unit 4 is read by a calculation unit 3 that performs various calculations.

The calculation unit 3 calculates the relationship between the amount of wear and the distance traveled by the mobile object based on, for example, the measured outer diameter of the caster 10. The calculation unit 3 calculates the future amount of wear of the caster 10 attached to the operating mobile object based on, for example, the relationship. The calculation unit 3 generates a maintenance plan for the AGV (mobile object) based on, for example, the calculated future amount of wear of the caster 10. The generated maintenance plan is displayed on the display unit 5. The display unit 5 is a display device configured, for example, by a liquid crystal display, an organic EL display, or the like. The calculation contents of the calculation unit 3 are explained below.

As shown in Figure 3, the wear amount (mm) of the caster 10 increases as the distance traveled (km) increases. The wear amount of the caster 10 also varies depending on the material of the caster 10. Under the same condition of distance traveled, the wear amount of the caster 10 will be smaller when the caster 10 is made of a hard material such as a hard resin than when it is made of a soft material such as a soft resin. At the predetermined standard value of wear amount that requires replacement of the caster 10, when the caster 10 is made of a hard material, the travel distance will be shorter than when the caster 10 is made of a soft material. As shown in the figure, the wear amount of the caster 10 increases in a curve relative to the distance traveled.

The amount of wear of the caster 10 actually measured by the test device 100 varies depending on the material of the caster 10. In the test, the amount of wear of two types of caster 10 (caster (1) and caster (2)) attached to the AGV was measured periodically. Caster (1) is made of, for example, a soft material. Caster (2) is made of, for example, a harder material than caster (1).

Figure 4 shows an example of a graph in which the relationship between the travel distance (km) and wear amount (mm) of the caster 10 is approximated by a function based on the measured values. As shown in the figure, the approximated curve obtained is a power curve.

As shown in Figure 5, when the travel distance of the caster 10 on the horizontal axis and the wear amount of the caster 10 on the vertical axis are graphed as logarithmic values, the relationship between the travel distance of the caster 10 and the wear amount can be expressed as a straight line. As shown in the figure, the relationship between the travel distance of the caster 10 and the wear amount can be expressed based on a simple equation that is linearly regressed, such as Y = AX + B. By calculating the coefficient A and constant B in the linear relationship equation, the future wear amount of the caster 10 can be predicted.

Parameters such as coefficient A and constant B in the relational equation change depending on differences in running conditions such as the material, shape, and load capacity of the caster 10, and the type of floor test specimen. Therefore, by accumulating data on a large number of combinations of running conditions and creating a database, it is possible to obtain wear trends from short-term test data, even for products for which accurate caster information is unavailable, such as overseas products.

In other words, according to the maintenance management method, a relational equation for a caster 10 may be calculated based on test data for a caster 10 for which type information is insufficient, and a type similar to the caster 10 may be estimated based on the calculation results. According to the maintenance management method, a caster 10 for which type information is insufficient may be attached to an AGV and operated, the amount of operational wear of the caster 10 that wears during operation may be measured periodically, a relational equation for the caster 10 may be calculated based on the amount of operational wear, and a type similar to the caster 10 may be estimated based on the calculation results. Furthermore, when developing a caster 10 as a product, trends can be predicted based on this database, significantly reducing the testing time required to measure the amount of wear on the caster 10. According to the maintenance management method, new casters can be designed based on the test results and the amount of operational wear.

Furthermore, finding the travel distance that corresponds to the reference value for wear amount as the test progresses is difficult to predict at the test planning stage. Therefore, by reflecting wear amount data obtained by actually running an AGV in the test database, it is possible to adjust the parameters in the relational equation and grasp wear amount trends more accurately. In other words, a maintenance management method can accumulate test results from travel tests under different test conditions, periodically measure the operating wear amount of the casters 10 attached to an operating AGV, and adjust the parameters included in the relational equation based on the test results and the measured operating wear amount.

The above-described caster 10 maintenance management method can be executed by the maintenance management device 1. In the maintenance management device 1, the acquisition unit 2 acquires measured values of caster wear obtained through periodic running tests of a mobile object equipped with casters, with test conditions including the applied load, caster type, and floor type being varied. The calculation unit 3 calculates a relationship between the wear amount and the running distance of the mobile object based on the measured values. The relationship is an approximation that expresses the relationship between the logarithm of the running distance of the mobile object based on the test conditions and the logarithm of the caster wear by linear regression. The calculation unit 3 calculates parameters in the relationship based on the measured values.

The calculation unit 3 calculates the future amount of wear on the casters attached to the moving body based on the relational expression. The calculation unit 3 may generate a maintenance plan for the casters 10 based on the calculated future amount of wear. The maintenance plan determines the time when the outer diameter of the casters 10 will fall below a reference value based on a relational expression calculated based on, for example, the type of attached caster 10, the type of floor surface in the movable area, and the applied load, and indicates the time to replace the casters 10 of the AGV. The calculation unit 3 generates a maintenance plan for each AGV based on the operating status of each AGV. The maintenance plan may be updated based on actual measurements of the casters 10. The maintenance plan is displayed on the display unit 5 of the maintenance management device 1. The manager replaces the casters 10 attached to the AGV based on the maintenance plan.

Next, we will explain how to maintain and manage the casters 10 attached to the AGV.

Figure 7 shows a flowchart of each step of the maintenance management method using the maintenance management system S. Using the testing device 100, a running test is conducted simulating an AGV equipped with casters 10, varying test conditions including the applied load, the type of caster 10, and the type of floor surface (Step S100). The maintenance management device 1 measures the wear amount of the caster 10 at a predetermined timing and obtains a measurement value correlating the wear amount with the travel distance of the caster 10 (Step S102). Based on the obtained measurement value, the maintenance management device 1 calculates a relationship between the wear amount of the caster 10 and the travel distance (Step S104). Based on the relationship, the maintenance management device 1 calculates the future wear amount of the casters equipped on the operating mobile object (Step S106). Based on the calculated future wear amount, the maintenance management device 1 generates a maintenance plan for the mobile object (Step S108).

As described above, the maintenance management method makes it possible to predict the amount of wear on a caster 10 over long travel distances based on short travel distances in caster wear tests, significantly shortening measurement time and reducing work effort. The maintenance management method uses a database of test results obtained from a wide variety of combinations of caster materials, shapes, load capacities, etc. to help understand wear trends in casters 10, for which information is scarce, such as on imported products. The maintenance management method makes it possible to reflect the test results database in the product development of new casters tailored to usage conditions such as usage method and location. When a caster 10 is installed on an actual AGV, the maintenance management method makes it possible to predict the amount of wear on the caster based on travel distance, and to generate a maintenance plan that predicts the replacement period.

The calculation unit 3 described above is realized by a processor such as a CPU (Central Processing Unit) or GPU (Graphics Processing Unit) executing a program (software). Some or all of these functional units may be realized by hardware such as an LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), or FPGA (Field-Programmable Gate Array), or by a combination of software and hardware. The program may be stored in a storage device such as an HDD (Hard Disk Drive) or flash memory included in the storage unit 4, or may be stored on a removable storage medium such as a DVD or CD-ROM and installed in the storage device by inserting the storage medium into a drive. Furthermore, a program is not necessarily required; predetermined operations may be performed by configuring a sequential circuit in the maintenance management device 1.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and can be modified as appropriate without departing from the spirit of the invention. For example, the maintenance management device 1 may be applied not only to AGVs, but also to drivable mobile bodies equipped with casters 10.

DESCRIPTION OF SYMBOLS 1 Maintenance management device 2 Acquisition unit 3 Calculation unit 4 Memory unit 5 Display unit 10 Caster 100 Test device 101 Test stand 102 Traveling device 102A Encoder 102L Link device 102R Rotor 103 Loading device 104 Measuring device S Maintenance management system W Network

Claims (6)

a step of conducting a running test of the caster while changing test conditions including the applied load, the type of caster, and the type of floor surface;
measuring the amount of wear of the caster and calculating a relational expression between the amount of wear and the running distance based on the obtained measurement value;
A step of calculating a future wear amount of the caster provided on the moving body in operation based on the relational expression;
and generating a maintenance plan for the mobile body based on the calculated amount of future wear. the relational expression is an approximation expression that expresses, by a straight line, the relationship between the logarithm of the travel distance of the movable body based on the test conditions and the logarithm of the wear amount of the caster,
calculating a parameter in the relational expression based on the measured value;
The maintenance management method according to claim 1. accumulating test results of the running tests under different test conditions;
a step of periodically measuring the operating wear amount of the caster provided on the moving body while it is in operation;
and adjusting the parameters based on the test results and the measured values of the operational wear.
The maintenance management method according to claim 2. conducting the running test of the caster for which the type information is lacking;
and estimating the type of the caster based on the test results.
The maintenance management method according to claim 3. and a step of designing a new caster based on the test results and the amount of operational wear.
The maintenance management method according to claim 3 or 4. a calculation unit that calculates a relational expression between the amount of wear and a running distance based on measured values of the amount of wear of the casters obtained by running tests of the casters, the test conditions of which include the applied load, the type of caster, and the type of floor surface, calculates future amounts of wear of the casters provided on an operating mobile body based on the relational expression, and generates a maintenance plan for the mobile body based on the calculated future amounts of wear;
Maintenance management system.