Monitoring system and method for endless part of conveyor belt

Abstract

Provided are a system and a method for monitoring an endless part of a conveyor belt, with which it is possible to more easily and accurately ascertain a precursor to the occurrence of a failure in the endless part. Passive IC tags (2) are installed at an endless front position and at an endless rear position across an endless section (6A) in the longitudinal direction of the belt. A transmission radio wave (R1) is transmitted from detectors (3) disposed at predetermined detection positions near a conveyor belt (6) toward each IC tag (2) while the conveyor belt (6) is moving. The length (Le) of the endless section (6A) in the longitudinal direction of the belt is calculated by an arithmetic device (4) on the basis of the travel speed (V) of the conveyor belt (6) and the reception time of a response radio wave (R2) received by the detector (3) from each IC tag (2) when each IC tag (2) passes through the detection position. The condition of the endless section (6A) is determined on the basis of the change over time of the calculated length (Le) in the longitudinal direction of the belt.

Description

System and method for monitoring an endless section of a conveyor belt

[0001] The present invention relates to a system and method for monitoring the endless portion of a conveyor belt, and more particularly to a system and method for monitoring the endless portion of a conveyor belt that can more easily and accurately detect signs of a malfunction in the endless portion of a conveyor belt.

[0002] Conveyor belts transport a variety of materials, including mineral resources such as iron ore and limestone. Conveyor belts have a section (endless section) where the traction layer is joined in the longitudinal direction. In the endless section, problems such as peeling of the joined traction layer can occur.

[0003] Various methods for managing conveyor belts by embedding RFID tags in the belt have been proposed (see, for example, Patent Document 1). Patent Document 1 proposes using a reader to read RFID tags embedded near the joints (endless portions) of the conveyor belt to discover and recognize joints that are relatively prone to peeling or breakage (paragraphs 0056 and 0070 of Patent Document 1). However, simply detecting the joints of the conveyor belt using a reader in this way does not accurately identify signs of potential problems at the joints. Therefore, there is room for improvement in a simpler and more accurate way of identifying signs of potential problems at the endless portions.

[0004] Japanese Patent Application Publication No. 2022-23840

[0005] An object of the present invention is to provide a monitoring system for the endless portion of a conveyor belt that can more easily and accurately detect signs of a malfunction occurring in the endless portion of the conveyor belt.

[0006] To achieve the above object, the present invention provides a monitoring system for the endless portion of a conveyor belt, which comprises a passive IC tag attached to the conveyor belt, a detector disposed at a predetermined detection position near the conveyor belt and wirelessly communicating with the IC tag without contacting the conveyor belt, and a computing device communicably connected to the detector, wherein the IC tags are respectively attached at a front position and a rear position of the endless portion of the conveyor belt across the belt longitudinal direction, and the system detects the presence or absence of the IC tags attached to the conveyor belt while the conveyor belt is running. The detector emits radio waves toward each of the IC tags, and the detector receives reply radio waves returned from each of the IC tags in response to the emitted radio waves each time the IC tag passes the detection position, and the calculation device calculates the belt longitudinal length of the endless section based on the reception time of the reply radio waves received by the detector from each of the IC tags when each of the IC tags passes the detection position and the running speed of the conveyor belt, and the state of the endless section is determined based on the change over time in the calculated belt longitudinal length of the endless section.

[0007] The method for monitoring the endless portion of a conveyor belt of the present invention comprises installing a passive IC tag on the conveyor belt, arranging a detector at a predetermined detection position near the conveyor belt, transmitting radio waves from the detector toward the IC tag without contacting the conveyor belt while the conveyor belt is running, receiving reply radio waves returned from the IC tag in response to the transmitted radio waves each time the IC tag passes the detection position by the detector, and inputting the reception results into a computing device. The method is characterized in that the IC tags are installed at a front position and a rear position of the endless tag that straddle the endless portion of the conveyor belt in the belt longitudinal direction, and the computing device calculates the belt longitudinal length of the endless portion based on the reception time of the reply radio waves from each IC tag received by the detector when each IC tag passes the detection position and the running speed of the conveyor belt, and the state of the endless portion is grasped based on the change over time in the calculated belt longitudinal length of the endless portion.

[0008] According to the present invention, a simple configuration can be achieved that includes a passive IC tag, a detector that wirelessly communicates with the IC tag, and a computing device communicatively connected to the detector. The computing device can accurately calculate the belt longitudinal length of the endless portion based on the reception time of the reply radio waves from each IC tag installed at a front position and a rear position across the endless portion in the belt longitudinal direction, the IC tags being received by the detector when the IC tags pass the detection position, and the running speed of the conveyor belt. Since an increase in the belt longitudinal length of the endless portion can be considered a sign of a malfunction in the endless portion, this is advantageous for more easily and accurately detecting signs of a malfunction in the endless portion based on the calculated change in the belt longitudinal length of the endless portion over time.

[0009] FIG. 1 is an explanatory diagram illustrating the overall configuration of an embodiment of a monitoring system for the endless portion of a conveyor belt. FIG. 2 is an explanatory diagram illustrating a side view of a conveyor belt to which the monitoring system of FIG. 1 is applied. FIG. 3 is a cross-sectional view taken along the line A-A in FIG. 2. FIG. 4 is a view taken along the line B-B in FIG. 3. FIG. 5 is an explanatory diagram illustrating a plan view of an IC tag. FIG. 6 is an explanatory diagram illustrating a cross-sectional view of the IC tag of FIG. 5. FIG. 7 is an explanatory diagram schematically illustrating the change over time in the longitudinal length of the endless portion of the belt. FIG. 8 is a graph diagram schematically illustrating the relationship between the position of the IC tag relative to the detector and the received signal strength of the reply radio wave.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A system and method for monitoring an endless portion of a conveyor belt according to the present invention will be described below based on an embodiment shown in the drawings.

[0011] 1 includes a passive IC tag 2, a detector 3 that wirelessly communicates with the IC tag 2, and a computing device 4 that is communicatively connected to the detector 3. In this embodiment, the computing device 4 is connectable to predetermined terminal devices 5a, 5b, and 5c via a communication network such as the Internet. The terminal devices 5a, 5b, and 5c are, for example, personal computers, smartphones, tablet computers, and the like.

[0012] This system 1 is applied to a conveyor belt 6 mounted on a conveyor device, as shown in Figures 2 and 3. The conveyor belt 6 to be monitored is composed of a traction layer 7 made of canvas or steel cord, and an upper cover rubber 8 and a lower cover rubber 9 that sandwich the traction layer 7 from above and below. An object C is placed on the surface of the upper cover rubber 8 and transported to its destination by the conveyor belt 6. The traction layer 7 provides tension for tensioning the conveyor belt 6. The conveyor belt 6 is configured with other necessary components added as needed. The L and W arrows in the figures indicate the belt longitudinal and width directions, respectively.

[0013] The conveyor belt 6 is stretched between a driving pulley 10a and a driven pulley 10b under a predetermined tension. Between the driving pulley 10a and the driven pulley 10b, the conveyor belt 6 is supported by support rollers 11 arranged at appropriate intervals in the belt longitudinal direction.

[0014] On the carrier side of the conveyor belt 6, the lower cover rubber 9 is supported by support rollers 11, and on the return side, the upper cover rubber 8 is supported by support rollers 11. On the carrier side of the conveyor belt 6, three support rollers 11 are arranged in the belt width direction, and these support rollers 11 support the conveyor belt 6 in a concave shape at a predetermined trough angle.

[0015] The drive pulley 10a is rotated by a drive motor. The take-up mechanism 12 moves the driven pulley 10b to change the gap between the drive pulley 10a and the driven pulley 10b in the belt longitudinal direction, thereby applying a predetermined tension to the conveyor belt 6 (core layer 7). With the conveyor belt 6 stretched at this predetermined tension, the drive pulley 10a is rotated to run the conveyor belt 6.

[0016] One or more conveyor belts 6 are formed into a ring shape by splicing together the longitudinal ends of their traction layers 7. Therefore, as shown in Fig. 4, the conveyor belt 6 has a longitudinally spliced ​​portion (endless portion 6A) of the traction layers 7 and an unspliced ​​portion (non-endless portion 6B) adjacent to each other. The longitudinal length Le of the endless portion 6A (hereinafter referred to as the endless length Le) is set appropriately based on the specifications of the conveyor belt 6, etc.

[0017] When one conveyor belt 6 is joined together to form a ring, there is one endless portion 6A, but when two or three conveyor belts 6 are joined together to form a ring, there are two or three endless portions 6A, respectively. When the total length of the conveyor belt 6 is very long (for example, several kilometers or more), many conveyor belts 6 are joined together to form a ring, so there are many endless portions 6A. In Figure 4, the upper side of the drawing is the forward direction of the belt (downstream side in the running direction), and the lower side of the drawing is the rear direction of the belt (upstream side in the running direction).

[0018] In this conveyor belt 6, the traction layer 7 is formed of a large number of steel cords 7a arranged in parallel in the belt width direction. In the endless portion 6A, the steel cords 7a extending from the non-endless portion 6B opposing the belt in the longitudinal direction are inserted between every other steel cord 7a in the width direction. If the traction layer 7 is formed of canvas, the endless portion 6A may have a known structure, such as canvas extending from the non-endless portion 6B opposing the belt in the longitudinal direction being joined in a step-like manner.

[0019] In the non-endless portion 6B, the traction layer 7 is continuous without any joints, but in the endless portion 6A, there are joints in the traction layer 7. Therefore, in the endless portion 6A, problems such as the spliced ​​traction layer 7 peeling off (steel cord 7a falling out) can occur, making the endless portion 6A more susceptible to problems than the non-endless portion 6B.

[0020] The IC tags 2 are installed at an endless front position and an endless rear position, respectively, straddling the endless portion 6A in the belt longitudinal direction. The endless front position is a position within a predetermined length X forward of the boundary between the front end of the endless portion 6A and the non-endless portion 6B, and is the area of ​​the non-endless portion 6B near the endless portion 6A. The endless rear position is a position within a predetermined length X rearward of the boundary between the rear end of the endless portion 6A and the non-endless portion 6B, and is the area of ​​the non-endless portion 6B near the endless portion 6A. The predetermined length X is, for example, 60 mm. Although the endless front position and the endless rear position are near the endless portion 6A, they are areas of the non-endless portion 6B, and therefore their behavior is more stable than that of the endless portion 6A.

[0021] In this embodiment, the IC tags 2 are installed at multiple locations (three locations) at intervals in the belt width direction. That is, three pairs of IC tags 2, 2 are installed in the non-endless portion 6B near the endless portion 6A across the endless portion 6A in the belt longitudinal direction, and are arranged in parallel at intervals in the belt width direction. It is sufficient that there is at least one pair of tags 2, 2, and it is also possible to have, for example, only a pair of tags 2, 2 installed in the center of the belt width direction.

[0022] In this embodiment, additional IC tags 2A are installed in positions spaced apart in the belt longitudinal direction ahead of each IC tag 2 installed in the forward position of the endless section 6A. That is, three pairs of IC tags 2, 2A are installed in the non-endless section 6B near the endless section 6A without spanning the endless section 6A in the belt longitudinal direction, and are arranged in parallel with a space in the belt width direction. The belt longitudinal spacing (arrangement pitch) La between pairs of IC tags 2, 2A can be determined arbitrarily, for example, approximately 300 mm to 500 mm, or approximately equal to the initial endless length Le. These additional IC tags 2A can be installed arbitrarily. The traction layer 7 and IC tags 2, 2A are embedded in the conveyor belt 6 (lower cover rubber 9), but in FIG. 4, the traction layer 7 and IC tags 2, 2A are visible through the lower cover rubber 9.

[0023] 5 and 6, the IC tag 2 has an IC chip 2b and an antenna portion 2c connected to the IC chip 2b. The IC chip 2b and the antenna portion 2c are disposed on a substrate 2d and covered with an insulating layer 2e. The above-mentioned additional IC tag 2A has the same specifications as the IC tag 2 and the method of installation on the conveyor belt 6, so a description thereof will be omitted below.

[0024] The IC tag 2 may be of a generally available specification, for example, an RFID tag (general-purpose product). The size of the IC tag 2 is, for example, 200 mm 2 Over 6000mm 2 Less than 300 mm, more preferably 2 2700mm or more 2 The thickness is, for example, 0.01 mm or more and 0.4 mm or less, more preferably 0.03 mm or more and 0.15 mm or less. The heat resistance temperature of the IC tag 2 is, for example, about 250°C.

[0025] The IC chip 2b pre-stores unique information that distinguishes the IC tag 2 from other IC tags 2. Although other information can be stored in the IC chip 2b, in this system 1, it is sufficient that only the unique information of the IC tag 2 is stored in the IC chip 2b. Therefore, no special information is stored in the IC chip 2b.

[0026] The IC tag 2 is not limited to being embedded in the lower cover rubber 9, but can also be installed at a different position on the conveyor belt 6. For example, it can be embedded in the upper cover rubber 8 or, in the case of a traction layer 7 made of multiple layers of canvas, in the traction layer 7. In order to protect the IC tag 2 from the transported goods C, it is preferable to embed it in the lower cover rubber 9 or traction layer 7 rather than in the upper cover rubber 8. The IC tag 2 can also be installed on the surface of the conveyor belt 6 without being embedded therein.

[0027] The IC tag 2 can be embedded in the conveyor belt 6 during its manufacture, or can be attached to the conveyor belt 6 after manufacture. For example, the IC tag 2 is placed in a desired position (on the surface of the lower cover rubber 9 or the upper cover rubber 8) on the conveyor belt 6 after manufacture, and then the IC tag 2 is covered with a rubber material and bonded to the conveyor belt 6 together with the rubber material. This bonding can be achieved using a known adhesive or vulcanization bonding. When vulcanization bonding is used, for example, a predetermined position on the conveyor belt 6 is subjected to a known surface treatment such as buffing, and then the IC tag 2 is placed in the predetermined position and covered with unvulcanized rubber material. The unvulcanized rubber material is then heated and pressurized to vulcanize it, and the IC tag 2 and the rubber material are vulcanization-bonded to the conveyor belt 6. By employing a method of retrofitting the IC tag 2 to the manufactured conveyor belt 6, this system 1 can be applied to existing conveyor belts 6 installed in conveyor devices.

[0028] The detector 3 is disposed at a predetermined detection position near the conveyor belt 6 and communicates wirelessly with the IC tag 2 without contacting the conveyor belt 6. More specifically, the detector 3 is disposed opposite a position where the IC tag 2 passes as the conveyor belt 6 travels. In this embodiment, the detector 3 is disposed close to the surface of the lower cover rubber 9 on the return side of the conveyor belt 6. The IC tags 2 are disposed at three positions spaced apart in the belt width direction on the conveyor belt 6, and correspondingly, the detectors 3 are disposed at three positions spaced apart in the belt width direction.

[0029] The detector 3 has a transmitter 3s and a receiver 3r. The transmitter 3s transmits an outgoing radio wave R1 toward the IC tag 2. The receiver 3r receives a reply radio wave R2 returned from the IC tag 2 (antenna section 2c) in response to the outgoing radio wave R1, and acquires the unique information of the IC tag 2 stored in the IC chip 2b that is transmitted together with the reply radio wave R2.

[0030] The detector 3 employs a commonly available specification that allows wireless communication with passive RFID tags, etc. In this way, the IC tag 2 and the detector 7 constitute an RFID (Radio Frequency Identification) system. The radio wave frequency used for wireless communication between the IC tag 2 and the detector 3 is mainly in the UHF band (a range of 860 MHz to 930 MHz, which varies depending on the country; in Japan, it is 915 MHz to 930 MHz), although the HF band (13.56 MHz) is sometimes used.

[0031] The detector 3 is not limited to being arranged on the return side of the conveyor device 10 as in this embodiment, but can also be arranged on the carrier side. The distance between the detector 3 and the IC tag 2 (antenna portion 2c) when they are closest to each other is set to, for example, within 1 m.

[0032] The arithmetic unit 4 is connected to the detector 3 by wire or wirelessly. A known computer or computer server is used as the arithmetic unit 4. The arithmetic unit 4 performs various arithmetic processes based on various input information.

[0033] The calculation device 4 receives various information such as the reception result of the reply radio wave R2 from the detector 3 and the running speed V of the conveyor belt 6. The running speed V is calculated based on, for example, the rotation speed of the drive pulley 10a. The calculation device 4 also receives a previously measured initial endless length Le. This initial endless length Le may be a measurement value obtained by attaching the conveyor belt 6 to the conveyor device, applying a predetermined tension to the conveyor belt 6, and running the conveyor belt 6 for a number of revolutions, and then measuring the initial endless length Le while the predetermined tension is being applied to the conveyor belt 6.

[0034] The above-mentioned predetermined length X is known for each IC tag 2, and is therefore input to the arithmetic unit 4 together with the unique information of that IC tag 2. In addition, the distance La between a pair of IC tags 2, 2A is known, and is therefore input to the arithmetic unit 4 together with the unique information of each IC tag 2, 2A. In other words, the placement positions of each IC tag 2, 2A on the conveyor belt 6 and the unique information of each IC tag 2, 2A are input to the arithmetic unit 4.

[0035] Next, a method for monitoring the endless section 6A using this system 1 will be described.

[0036] 2 and 3, in the conveyor device, while the conveyor belt 6 is running, transported objects C are thrown onto the surface of the upper cover rubber 8, for example, through a hopper or the like. While the conveyor belt 6 is running, an outgoing radio wave R1 is emitted from the transmitter 3s of the detector 3 toward each IC tag 2. Each time the IC tag 2 passes the detection position, it returns a reply radio wave R2 together with the unique information of that IC tag 2 in response to the outgoing radio wave R1. The receiver 3r of the detector 3 receives the reply radio wave R2 returned from each IC tag 2 and the unique information of that IC tag 2.

[0037] The calculation device 4 calculates the endless length Le based on the reception time t of the reply radio wave R2 from each IC tag 2 received by the detector 3 when each IC tag 2 passes the detection position and the traveling speed V of the conveyor belt 6. If the reception times t of the reply radio wave R2 from a pair of IC tags 2, 2 spaced a distance of endless length Le + 2 × (predetermined length X) are t1 and t2, respectively, the time required from when one IC tag 2 of the pair of IC tags 2, 2 passes the detection position until the other IC tag 2 passes the detection position is (t2 - t1). Therefore, the endless length Le at this time is calculated as (t2 - t1) = traveling speed V × (t2 - t1) - 2 × (predetermined length X). In this way, the calculation device 4 calculates the endless length Le each time the conveyor belt 6 makes one revolution, and the change over time in the endless length Le (data D1, D2) illustrated in FIG. 7 is grasped. In FIG. 7, the initial endless length Le is indicated by M, and in one data D1, the endless length Le hardly changes over time, while in the other data D2, the endless length Le increases over time.

[0038] If the endless length Le is increasing, it is considered that a defect such as peeling of the core layer 7 joined at the endless portion 6A (the steel cord 7a falling off) is beginning to occur, and this can be regarded as a sign of a defect occurring in the endless portion 6A. Based on these data D1 and D2, the calculation device 4 determines whether or not there is a sign of a defect occurring in the endless portion 6A.

[0039] In the case of data D1, it can be determined that there are no signs of malfunction in the endless portion 6A and that the endless portion 6A is sound, while in the case of data D2, it can be determined that there are signs of malfunction in the endless portion 6A. Therefore, an allowable change length for the initial endless length Le is set in advance and input into the calculation device 4. When the endless length Le, which is calculated successively, exceeds this allowable change length, the calculation device 4 activates a warning means such as an alarm or a warning display to notify an operator, manager, etc. that there are signs of malfunction in the endless portion 6A.

[0040] The horizontal axis of the graph in Fig. 7 may be the cumulative running time of the conveyor belt 6, rather than simply the elapsed time. During periods when the conveyor belt 6 is not running (periods when the conveyor belt 6 is not in operation), almost no change over time in the endless length Le is observed. Therefore, by using the change in the endless length Le with respect to the cumulative running time of the conveyor belt 6 as the change over time in the endless length Le, it is possible to more appropriately determine whether or not there is a sign of a malfunction in the endless portion 6A based on the actual usage situation of the conveyor belt 6.

[0041] The cumulative running time of the conveyor belt 6 is calculated by the calculation device 4 using the interval between the reception times t of reply radio waves R2 received by the detector 3 from at least one IC tag 2 (the time interval between the reception times t at which the receiver 3 periodically receives reply radio waves R2 from the same IC tag). Specifically, the total length of the conveyor belt 6 is known, and the running speed V of the conveyor belt 6 is approximately set, so the period T at which each IC tag 2 repeatedly passes the detection position is determined. If the conveyor belt 6 is running, the detector 3 receives reply radio waves R2 from one IC tag 2 approximately at this period T. Therefore, if the interval between the reception times t of the reply radio waves R2 is approximately this period T, it can be determined that the conveyor belt 6 is running. Therefore, if the interval between the reception times t is, for example, a predetermined multiple (e.g., two or three times) or more of the predetermined period T, it is determined that the conveyor belt 6 is not running. In other words, the cumulative running time is calculated by accumulating the period during which the interval between the reception times t is less than the predetermined multiple of the predetermined period T.

[0042] This system 1 can be simply configured to include a passive IC tag 2, a detector 3 that wirelessly communicates with the IC tag 2, and a computing device 4 communicatively connected to the detector 3. The endless length Le can be accurately calculated based on the reception time t (t1, t2) of a reply radio wave R2 from each of the IC tags 2, 2, which are installed across the endless section 6A in the belt longitudinal direction and are received by the detector 3 when the pair of IC tags 2, 2 pass the detection position, and the running speed V of the conveyor belt 6. This calculated change in the endless length Le over time is advantageous for more easily and accurately detecting signs of a malfunction in the endless section 6A. As a result, the malfunction of the endless section 6A can be quickly inspected and repaired, thereby avoiding or minimizing damage caused by the malfunction of the endless section 6A. Even if there are a large number of endless sections 6A, this system 1 can be easily applied to each of the endless sections 6A, so it is particularly useful when the total length of the conveyor belt 6 is, for example, 5 km or more, or 10 km or more.

[0043] As shown in Fig. 2, the conveyor belt 6 runs in a trough-shaped bent state, and therefore the elongation of the conveyor belt 6 and the tension acting on the trough layer 7 vary depending on the position in the belt width direction. Therefore, defects in the endless portion 6A originate from the weakest point. Therefore, as in this embodiment, placing IC tags 2 at the widthwise center (region corresponding to the flat portion in Fig. 2) and widthwise end portions (regions corresponding to the inclined portion in Fig. 2) of the conveyor belt 6 and grasping the condition of the endless portion 6A based on the change over time in the belt longitudinal length Le of the endless portion 6A is extremely effective in grasping signs of defects in the endless portion 6A with higher accuracy.

[0044] Terminal devices 5a, 5b, and 5c are set to be able to access calculation device 4 by, for example, inputting a password. By calculation device 4 transmitting data D1, D2, etc. on the change over time of endless length Le to terminal devices 5a, 5b, and 5c, relevant parties can grasp the state of endless section 6A in substantially real time via terminal devices 5a, 5b, and 5c, even if they are in a location remote from where conveyor belt 6 is used.

[0045] As the conveyor belt 6 moves, each IC tag 2 repeatedly passes the detection position where the detector 3 is located. When an IC tag 2 approaches the detection position where the detector 3 is located, the closer the IC tag 2 is to the detection position and the more wireless communication there is between the IC tag 2 and the detector 3 located at that detection position, the higher the received signal strength RSSI of the reply radio wave R2 received by the detector 3, as shown by the data DR in Fig. 8. In other words, when the received signal strength RSSI of the reply radio wave R2 is highest, it is considered that the IC tag 2 is located closest to the detection position.

[0046] Therefore, it is advisable to devise a further measure rather than simply adopting the time t at which the detector 3 receives the reply radio wave R2 from each IC tag 2 as the reception time t (t1, t2) when that IC tag 2 passes through the detector 3. That is, each time each IC tag 2 passes through the detection position, the time t at which the detector 3 receives the reply radio wave R2 with the highest received signal strength RSSI from that IC tag 2 is adopted as the reception time t of the reply radio wave R2 from that IC tag 2 when that IC tag 2 passes through the detector 3. Using the reception time t adopted in this way is advantageous for calculating the endless length Le with higher accuracy.

[0047] If the running speed V of the conveyor belt 6 is obtained based on the rotation speed of the drive pulley 10a, etc., some degree of error will occur due to the conditions under which the conveyor belt 6 is used. Therefore, further measures should be taken to accurately obtain this running speed V. More specifically, in addition to each IC tag 2, an additional IC tag 2A is attached to the conveyor belt 6 as described above. Then, a pair consisting of the additional IC tag 2A and an IC tag 2 that is attached at a distance La in the belt longitudinal direction without spanning the endless portion 6A in the belt longitudinal direction is used as the speed detection IC tag. While three pairs of the additional IC tag 2A and the IC tag 2 are shown in Figure 4, at least one pair is sufficient.

[0048] As the conveyor belt 6 travels, each of the additional IC tags 2A repeatedly passes the detection position where the detector 3 is located. An outgoing radio wave R1 is emitted from the transmitter 3s of the detector 3 toward each of the additional IC tags 2A. As each of the additional IC tags 2A passes the detection position, it returns a reply radio wave R2 together with the unique information of that additional IC tag 2A in response to the outgoing radio wave R1. The receiver 3r of the detector 3 receives the reply radio wave R2 returned from each of the additional IC tags 2A and the unique information of that additional IC tag 2A.

[0049] The calculation device 4 calculates the traveling speed V based on the reception time ta of the reply radio wave R2 from each additional IC tag 2A received by the detector 3 when the additional IC tag 2A passes the detection position, the reception time t1 of the reply radio wave R2 from the IC tag 2 that forms the pair, and the separation distance La. The separation distance La is previously determined and input to the calculation device 4. Since the separation distance La can be considered to be essentially constant over time, the time required from when the additional IC tag 2A passes the detection position until the IC tag 2 that forms the pair passes is (t1 - ta). Therefore, the traveling speed V at this time is calculated as follows: separation distance La / (t1 - ta). In this way, the calculation device 4 calculates the traveling speed V for each revolution of the conveyor belt 6 and uses it to calculate the endless length Le described above. Because this traveling speed V is a calculated value measured near the endless portion 6A, it is useful for more accurately calculating the endless length Le. The reception time ta may be the time adopted in the method described with reference to FIG.

[0050] The additional IC tag 2A may be installed at a position rearward of the IC tag 2 installed at a distance in the longitudinal direction of the belt from the IC tag 2 installed at a position rearward of the endless portion 6A. Alternatively, a set of two additional IC tags 2A, 2A installed at a distance in the longitudinal direction of the belt without spanning the endless portion 6A in the longitudinal direction of the belt can be used as a set of speed detection IC tags, separate from the IC tag 2.

[0051] That is, at least one additional IC tag 2A is provided in the non-endless portion 6B near the endless portion 6A, and a set of one additional IC tag 2A and one of the IC tags 2 provided at a distance in the belt longitudinal direction without straddling the additional IC tag 2A and the endless portion 6A in the belt longitudinal direction, or a set of two additional IC tags 2A, 2A provided at a distance in the belt longitudinal direction without straddling the endless portion 6A in the belt longitudinal direction, may be used as a set of speed detection IC tags. Then, the calculation device 4 calculates the traveling speed V based on the reception times t, t of the reply radio waves R2 received by the detector 3 from the set of speed detection IC tags when the set of speed detection IC tags passes the detection position, and the previously determined separation distance La between the set of speed detection IC tags in the belt longitudinal direction.

[0052] REFERENCE SIGNS LIST 1 Monitoring system 2, 2A IC tag 2b IC chip 2c Antenna section 2d Substrate 2e Insulating layer 3 Detector 3r Receiving section 3s Transmitting section 4 Calculating device 5a, 5b, 5c Terminal equipment 6 Conveyor belt 6A Endless section 6B Non-endless section 7 Traction layer 7a Steel cord 8 Upper cover rubber 9 Lower cover rubber 10a, 10b Pulley 11 Support roller 12 Take-up mechanism

Claims

1. A monitoring system for the endless portion of a conveyor belt, comprising: a passive IC tag attached to the conveyor belt; a detector disposed at a predetermined detection position near the conveyor belt and wirelessly communicating with the IC tag without contacting the conveyor belt; and a computing device communicably connected to the detector, wherein the IC tags are respectively attached at a front position and a rear position of the endless portion of the conveyor belt that straddle the endless portion of the conveyor belt in the belt longitudinal direction; while the conveyor belt is running, the detector emits radio waves toward each of the IC tags attached to the conveyor belt, and each time each of the IC tags passes the detection position, the detector receives reply radio waves returned from each of the IC tags in response to the emitted radio waves; A monitoring system for the endless section of a conveyor belt, in which the calculation device calculates the longitudinal length of the endless section based on the time of reception of the reply radio wave from each IC tag received by the detector as each IC tag passes the detection position and the running speed of the conveyor belt, and the condition of the endless section is determined based on the change over time in the calculated longitudinal length of the endless section.

2. A monitoring system for the endless section of a conveyor belt as described in claim 1, configured so that the time when the detector receives the reply radio wave with the highest received signal strength from each of the IC tags is adopted as the time when the reply radio wave is received from each of the IC tags when each of the IC tags passes through the detector.

3. A monitoring system for the endless section of a conveyor belt as described in claim 1 or 2, which has at least one additional IC tag installed in a non-endless section near the endless section, in addition to each of the IC tags, and which uses a set of one additional IC tag and one of the IC tags installed at a distance in the longitudinal direction of the belt without straddling the endless section in the longitudinal direction of the belt, or a set of two additional IC tags installed at a distance in the longitudinal direction of the belt without straddling the endless section in the longitudinal direction of the belt, as a set of speed detection IC tags, and wherein the calculation device calculates the running speed of the conveyor belt based on the time of reception of the reply radio waves from the set of speed detection IC tags received by the detector when the set of speed detection IC tags passes the detection position and the previously determined separation distance in the longitudinal direction of the belt of the set of speed detection IC tags.

4. A monitoring system for the endless portion of a conveyor belt as described in any one of claims 1 to 3, wherein the cumulative running time of the conveyor belt is calculated by the calculation device based on the total length of the conveyor belt, the running speed, and the interval between the reception times of the reply radio waves from at least one of the IC tags, and the change in the longitudinal length of the endless portion relative to the cumulative running time is calculated as the change in the longitudinal length of the endless portion over time.

5. A monitoring system for the endless portion of a conveyor belt as described in any one of claims 1 to 4, configured so that data on changes in the longitudinal length of the endless portion of the belt over time is transmitted via a communication network to a terminal device located away from the site where the belt conveyor is used.

6. A method for monitoring the endless portion of a conveyor belt, comprising: installing a passive IC tag on a conveyor belt; arranging a detector at a predetermined detection position near the conveyor belt; transmitting radio waves from the detector toward the IC tag without contacting the conveyor belt while the conveyor belt is running; receiving a reply radio wave from the IC tag in response to the transmitted radio wave each time the IC tag passes the detection position by the detector; and inputting the reception results into a computing device; wherein the IC tags are installed at an endless front position and an endless rear position spanning the endless portion of the conveyor belt in the belt longitudinal direction; calculating the belt longitudinal length of the endless portion by the computing device based on the reception time of the reply radio wave from each IC tag received by the detector when each IC tag passes the detection position and the running speed of the conveyor belt; and determining the condition of the endless portion based on the change over time in the calculated belt longitudinal length of the endless portion.

7. A method for monitoring the endless portion of a conveyor belt according to claim 6, wherein each of said IC tags is embedded in said conveyor belt when said conveyor belt is manufactured.

8. A method for monitoring an endless portion of a conveyor belt according to claim 6, wherein each of said IC tags is attached to said conveyor belt mounted on a conveyor device.

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