Monitoring method and monitoring device

Abstract

The invention provides a monitoring method and a monitoring device, which can monitor bending and edge cracking of a belt without performing special processing on the belt. A monitoring method for monitoring a belt driven by a drive unit in a traveling direction includes: a surface shape measurement step (S1) for measuring a surface shape of the belt; and a determination step (S2-S9) for specifying the positions of both ends of the tape in the width direction at the measurement site on the basis of the data of the surface shape measured in the surface shape measurement step, and determining the presence or absence of tortuosity and crack on the basis of the specified positions of both ends of the tape in the width direction.

Description

Technical Field

[0001] The present disclosure relates to a monitoring method and a monitoring device. The present disclosure particularly relates to a monitoring method and a monitoring device for determining a belt driven in a traveling direction by a driving unit without meandering and edge cracking. Background Art

[0002] As a conveying device for conveying raw materials or the like, a belt conveyor having a conveyor belt (an example of a belt) wound around a pair of pulleys as a driving unit is known. The conveyor belt of the belt conveyor sometimes meanders due to long-term mechanical operation, and defects (hereinafter also referred to as "edge cracking") of the belt end caused by contact between the belt end and the gantry frame occur. In order not to break the conveyor belt due to this edge cracking, it is necessary to monitor the state of the conveyor belt.

[0003] As a method for monitoring the meandering or edge cracking of a conveyor belt, for example, Patent Document 1 discloses the following method: photographing the conveyor belt with a photographing device and monitoring the meandering of the conveyor belt based on the photographed image data. In addition, Patent Document 2 discloses the following method: detecting the defect of the ear part by measuring the unevenness of the surface of the conveyor belt by using a light cutting method using a line laser. However, in the methods of Patent Documents 1 and 2, although either the meandering or the edge cracking of the conveyor belt is monitored, both the meandering and the edge cracking cannot be monitored simultaneously.

[0004] Here, as a method for detecting both the meandering and the edge cracking of a conveyor belt, for example, Patent Document 3 discloses the following method: irradiating light on the conveyor belt and detecting an abnormality of the conveyor belt based on the amount of light received by a light receiving part.

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-115054

[0006] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2017-32346

[0007] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2020-132433

[0008] The method of Patent Document 3 can detect both the meandering and the edge cracking of the conveyor belt, but it is necessary to provide an ear seal part mixed with a light emitting agent at the ear part of the conveyor belt. Therefore, there are problems that the structure of the conveyor belt is complicated and the cost is high. Summary of the Invention

[0009] In view of this situation, an object of the present disclosure is to provide a monitoring method and a monitoring device capable of monitoring both the meandering and the edge cracking of a belt without performing special processing on the belt.

[0010] (1) A monitoring method according to an embodiment of the present disclosure monitors a belt driven in a traveling direction by a driving unit, and includes:

[0011] A surface shape measurement step of measuring the surface shape of the above-mentioned belt; and

[0012] A determination step of determining the positions of both end portions in the width direction of the above-mentioned belt at the measurement portion based on the data of the above-mentioned surface shape measured in the above-mentioned surface shape measurement step, and determining whether there are wrinkles and cracked edges on the above-mentioned belt based on the determined positions of both end portions in the width direction of the above-mentioned belt.

[0013] (2) As an embodiment of the present disclosure, based on (1),

[0014] In the above-mentioned surface shape measurement step, line laser is irradiated in the width direction of the above-mentioned belt in such a manner that at least both end portions in the width direction of the above-mentioned belt are included in the irradiation range, and the surface shape of the above-mentioned belt is measured.

[0015] (3) As an embodiment of the present disclosure, based on (1) or (2),

[0016] In the above-mentioned surface shape measurement step, the surface shape of the above-mentioned belt is measured during the operation of the above-mentioned belt, and the data of the measured surface shape are synthesized to generate data of the entire length portion of the above-mentioned belt.

[0017] (4) As an embodiment of the present disclosure, based on any one of (1) to (3),

[0018] In the above-mentioned determination step, the width of the above-mentioned belt is calculated based on the positions of both end portions in the width direction of the above-mentioned belt at the measurement portion, and the calculated width is compared with the width stored in advance, thereby determining whether there is a cracked edge on the above-mentioned belt.

[0019] (5) As an embodiment of the present disclosure, based on any one of (1) to (4),

[0020] In the above-mentioned determination step, when the calculated width is the same as the width stored in advance, the center position of the above-mentioned belt is calculated based on the positions of both end portions in the width direction of the above-mentioned belt at the measurement portion, and the calculated center position is compared with the center position stored in advance, thereby determining whether there is a wrinkle on the above-mentioned belt.

[0021] (6) As an embodiment of the present disclosure, based on any one of (1) to (5),

[0022] In the above determination process, when the calculated width is different from the pre-stored width, based on the parts before and after the measurement part in the traveling direction of the above belt, determine the part where the calculated width is the same as the pre-stored width, and infer the center position of the above belt at the measurement part according to the positions of both ends in the width direction of the above belt at this part, and compare the inferred center position with the pre-stored center position, thereby determining whether the above belt has twists and turns.

[0023] (7) A monitoring device according to an embodiment of the present disclosure monitors a belt driven by a driving unit in the traveling direction, and includes:

[0024] a measuring device that measures the surface shape of the above belt; and

[0025] an arithmetic device that determines the positions of both ends in the width direction of the above belt at the measurement part according to the data of the surface shape measured by the above measuring device, and determines whether the above belt has twists and turns and edge cracks based on the determined positions of both ends in the width direction of the above belt.

[0026] According to the present disclosure, a monitoring method and a monitoring device are provided, which can monitor both the twists and turns and edge cracks of the belt without performing special processing on the belt. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a diagram showing a structural example of a monitoring device according to an embodiment of the present disclosure.

[0028] Figure 2 is by Figure 1 a side view of a belt conveyor monitored by the monitoring device.

[0029] Figure 3 is by Figure 1 a top view of a belt conveyor monitored by the monitoring device.

[0030] Figure 4 is a diagram illustrating the surface shape data of the conveyor belt.

[0031] Figure 5 is a flowchart showing a processing example of a monitoring method according to an embodiment of the present disclosure.

[0032] Figure 6 is a diagram for explaining the calculation of the amount of twist.

[0033] Figure 7A is a diagram for explaining the calculation methods of the amount of twist and edge crack.

[0034] Figure 7B is a diagram for explaining the calculation methods of the amount of twist and edge crack.

[0035] Figure 7C This is a figure for explaining the calculation methods of the amount of waviness and edge crack.

[0036] Figure 7D This is a figure for explaining the calculation methods of the amount of waviness and edge crack.

[0037] Figure 7E This is a figure for explaining the calculation methods of the amount of waviness and edge crack. Detailed implementation manners

[0038] Hereinafter, a monitoring method and a monitoring device according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be appropriately omitted or simplified.

[0039] <Monitoring device>

[0040] Figure 1 FIG. shows a structural example of a monitoring device 10 according to an embodiment of the present disclosure. Figure 2 It is composed of Figure 1 A side view of the belt conveyor 1 monitored by the monitoring device 10. Figure 3 It is composed of Figure 1 A top view of the belt conveyor 1 monitored by the monitoring device 10. As Figure 2 shown, the monitoring device 10 measures the surface shape of the conveyor belt 30 wound around the pulley 20 and monitors the waviness and edge crack of the conveyor belt 30. Here, the pulley 20 is an example of a driving unit. In addition, the conveyor belt 30 is an example of a belt. In addition, waviness refers to a state in which the center in the width direction of the conveyor belt 30 deviates from the center position in the standard. In addition, an edge crack is a defect at the end of the conveyor belt 30.

[0041] The monitoring device 10 is a device for monitoring a belt driven in the traveling direction by a driving unit. The belt is not limited to the conveyor belt 30, but in this embodiment, it is assumed that the belt is the conveyor belt 30 driven by the pulley 20 for explanation. Here, the traveling direction is the direction in which the belt moves by the driving force from the driving unit. In this embodiment, the traveling direction is also referred to as the conveying direction. The conveying direction is the direction in which the conveyed object loaded on the surface 31 of the running conveyor belt 30 moves.

[0042] In addition, in the belt conveyor 1, it is preferable to manage the thickness of the conveyor belt 30 so that the conveyor belt 30 does not break. The thickness of the conveyor belt 30 can be calculated and managed based on the surface shape measured by the monitoring device 10. Here, the surface shape refers to a shape including the unevenness of the surface 31 of the conveyor belt 30. For example, a portion that is recessed compared to the surroundings on the surface 31 of the conveyor belt 30 may indicate that the thickness of the conveyor belt 30 is thinner than the surroundings. If the thickness of the conveyor belt 30 is 0, it can be known that a defect such as a hole has occurred in this portion.

[0043] As Figure 1 shown, the monitoring device 10 of this embodiment includes a laser sensor 11 and an arithmetic unit 12. The monitoring device 10 measures the surface shape of the conveyor belt 30 through the collaborative operation of the laser sensor 11 and the arithmetic unit 12, and monitors the bending and edge cracking of the conveyor belt 30. The laser sensor 11 and the arithmetic unit 12 can be connected through a network such as a LAN (Local Area Network), and can transmit and receive information (measurement data) obtained through measurement. In addition, the arithmetic unit 12 can obtain the conveyor belt operation information 13 via the network. The detailed content of the components of the monitoring device 10 will be described later.

[0044] As Figure 2 shown, the conveyor belt 30, which is the measurement object of the monitoring device 10, is wound around a pair of pulleys 20. When the pulleys 20 rotate, the conveyor belt 30 moves, so that the conveyed object placed on the surface 31 can move. Here, the surface 31 of the conveyor belt 30 is the surface (outer surface) on the side opposite to the surface (inner surface) of the conveyor belt 30 on the pulley 20 side.

[0045] <Laser Sensor>

[0046] The monitoring device 10 of this embodiment includes a plurality of laser sensors 11. As Figure 2 and Figure 3 shown, in order to be able to distinguish each of the plurality of laser sensors 11, they are sometimes denoted as the laser sensor 11a and the laser sensor 11b. In this embodiment, the laser sensor 11 is a laser cutting type device. The laser sensor 11 can measure the surface shape of the conveyor belt 30 in a non-contact state by irradiating line laser. That is, the laser sensor 11 measures the distance to the surface 31 of the conveyor belt 30 by irradiating line laser and receiving its reflected light by a light sensor. Then, the surface shape of the surface 31 of the conveyor belt 30 can be measured based on the distance information. Here, the line laser is a linear laser. Here, the laser sensor 11 is an example of a measuring device. The measuring device is not limited to the laser sensor 11, as long as it is a device that measures the surface shape of the conveyor belt 30. As another example, the measuring device can be composed of a camera or the like.

[0047] Preferably, the laser sensor 11 performs measurement during the rotation of the pulley 20 and the conveyor belt 30. As Figure 2 and Figure 3As shown, in this embodiment, in order to measure the entire width (the full length in the width direction) of the pulley 20, two laser sensors 11a and 11b are arranged in parallel in the width direction of the pulley 20 (which is, in other words, the width direction of the conveyor belt 30). The lasers (line lasers) from the laser sensors 11a and 11b extend in the width direction of the conveyor belt 30, and in order not to form an unmeasured area, the irradiation ranges of each other overlap by about several millimeters to several tens of millimeters. The end of the line laser on the side opposite to the overlapping end extends in the width direction on the pulley 20 to the outside of the end of the conveyor belt 30. Here, when it is possible to measure the entire width of the conveyor belt 30 with only one laser sensor 11, only one laser sensor 11 needs to be arranged.

[0048] In this embodiment, by irradiating the conveyor belt 30 with lasers using a plurality of laser sensors 11a and 11b respectively, the surface shape of the entire width of the conveyor belt 30 can be measured. In order to be able to measure the surface shape of the conveyor belt 30 at the portion where the conveyor belt 30 contacts the pulley 20, the laser sensor 11 can be arranged at a position where the laser can be irradiated onto the conveyor belt 30 from an obliquely upper direction of the pulley 20. At this time, in order to accurately measure the thickness direction of the conveyor belt 30, the laser sensor 11 is arranged such that the irradiation direction of the laser passes through the center 21 of the pulley 20. Here, the position of the laser sensor 11 is not limited to the obliquely upper side of the pulley 20. For example, in the case of observing from the side as Figure 2 shown, as long as the laser is irradiated between the 6 o'clock direction and the 12 o'clock direction (the left half side of the pulley 20 in the drawing) of the pulley 20 on the side closer to the laser sensor 11, the laser sensor 11 can be arranged at any position. By measuring the surface shape of the conveyor belt 30 at the portion where it contacts the pulley 20, the conveyor belt 30 does not swing up and down either, and the conveyor belt 30 in a stable posture can be measured. In this way, the laser sensor 11 can perform measurement to obtain information on the surface shape including the unevenness of the conveyor belt 30. Since the laser sensor 11 is non-contact type, the surface shape of the conveyor belt 30 can be measured during the operation of the conveyor belt 30.

[0049] <Operation device>

[0050] The arithmetic unit 12 calculates the surface shape of the conveyor belt 30 based on the measurement data of the surface of the conveyor belt 30 obtained by the laser sensor 11 and the conveyor belt operation information 13 acquired as needed (corresponding to the surface shape measurement process). Here, the conveyor belt operation information 13 includes information indicating the conveyor belt 30 during operation. In addition, the calculation performed by the arithmetic unit 12 includes a calculation of extracting only the information during the operation of the conveyor belt 30 from the information related to the surface shape obtained by the measurement. The arithmetic unit 12 synthesizes the data of the surface shape during the operation (during the driving process) of the conveyor belt 30 to generate the data of the entire length portion of the conveyor belt 30.

[0051] The arithmetic unit 12 determines the positions of both ends in the width direction of the conveyor belt 30 at the measurement site based on the obtained data of the surface shape of the conveyor belt 30. In addition, the arithmetic unit 12 determines whether there is any meandering or edge cracking of the conveyor belt 30 based on the determined positions of both ends in the width direction of the conveyor belt 30 (corresponding to the determination process).

[0052] The arithmetic unit 12 includes a processor that performs calculations and a storage unit that stores data used in the calculations (such as information on the surface shape). The arithmetic unit 12 can be, for example, a computer. The processor is, for example, a general-purpose processor or a dedicated processor customized for a specific process, but is not limited to them and can be any processor. The storage unit is one or more memories. The memory is, for example, a semiconductor memory, a magnetic memory, or an optical memory, etc., but is not limited to them and can be any memory.

[0053] <Monitoring method>

[0054] Hereinafter, with reference to Figures 4 to 7E , a monitoring method for the conveyor belt 30 including a specific determination method for meandering and edge cracking of the conveyor belt 30 based on the arithmetic unit 12 will be described. Figure 4 is a diagram illustrating the surface shape data of the conveyor belt 30. The surface shape represents the height direction as the radial direction starting from the center 21 of the cylindrical pulley 20, and is represented by the height difference in the height direction of the surface position of the conveyor belt 30. In Figure 4 , black portions such as near the center in the width direction indicate that the surface position is higher than the white portions.

[0055] Figure 5 is a flowchart showing an example of the processing of the monitoring method executed by the monitoring device 10 of the present embodiment.

[0056] The arithmetic unit 12 first performs the surface shape measurement of the conveyor belt 30 (step S1). In the surface shape measurement of this process, as described above, the arithmetic unit 12 measures the surface shape of the conveyor belt 30 during the operation of the conveyor belt 30, and synthesizes the measured surface shape data to generate data for the entire length portion of the conveyor belt 30.

[0057] The arithmetic unit 12 determines the positions of both ends in the width direction of the conveyor belt 30 based on the data of the entire length portion of the conveyor belt 30. The arithmetic unit 12 calculates the width of the conveyor belt 30 based on the determined positions of both ends 14 in the width direction (refer to Figure 6 ). Hereinafter, the calculated width of the conveyor belt 30 is also referred to as the "measured belt width". The arithmetic unit 12 reads the width, that is, the "standard belt width", previously stored in the storage unit. The standard belt width is the width of the conveyor belt 30 in the standard, and is the width of an appropriate conveyor belt 30 in a state without defects (chipped edges). The arithmetic unit 12 compares the measured belt width with the standard belt width to determine whether there is a chipped edge on the conveyor belt 30 (step S2).

[0058] When the measured belt width is the same as the standard belt width (yes in step S2), the arithmetic unit 12 determines that there is no chipped edge on the measured conveyor belt 30. When the measured belt width is different from the standard belt width (no in step S2), that is, when the width of the conveyor belt 30 is shorter than the standard due to defects, the arithmetic unit 12 determines that there is a chipped edge on the measured conveyor belt 30. Hereinafter, the case without a chipped edge is sometimes marked as "no chipped edge". In addition, the case with a chipped edge is sometimes marked as "chipped edge".

[0059] When the arithmetic unit 12 determines "no chipped edge" (yes in step S2), in order to detect the meandering of the conveyor belt 30, it performs the processing of steps S3 to S6 as follows. As Figure 6 shown, the arithmetic unit 12 calculates the center position in the width direction of the conveyor belt 30 based on the determined positions of both ends 14 in the width direction of the conveyor belt 30 (step S3). Hereinafter, the calculated center position in the width direction of the conveyor belt 30 is referred to as the calculated belt center 15.

[0060] Here, the center position in the width direction of the conveyor belt 30 in the standard, that is, the "standard belt center", coincides with the center position in the width direction of the pulley 20 (pulley center position). The pulley 20 is fixed to the gantry. Therefore, the pulley center position remains unchanged all the time. In addition, the position of the end portion (standard belt end) of the conveyor belt 30 in the standard corresponding to the standard belt center remains unchanged all the time. Therefore, by comparing the calculated belt center 15 with the standard belt center previously stored in the storage unit, it is possible to determine whether the conveyor belt 30 is meandering. The arithmetic unit 12 compares the calculated belt center 15 with the standard belt center to determine whether the conveyor belt 30 is meandering (step S4).

[0061] When the calculated center of the belt 15 is the same as the standard belt center (Yes in step S4), the arithmetic unit 12 determines that the measured conveyor belt 30 has no twist (step S5). When the calculated center of the belt 15 deviates from the standard belt center (No in step S4), the arithmetic unit 12 determines that the measured conveyor belt 30 has a twist. Hereinafter, the case of no twist may be marked as "no twist". In addition, the case of having a twist may be marked as "having a twist".

[0062] When the arithmetic unit 12 determines that there is a "twist" (No in step S4), it calculates the twist amount 16 of the conveyor belt 30 based on the offset amount of the center position (refer to Figure 6 )(step S6).

[0063] When the arithmetic unit 12 determines that there is a "split edge" (No in step S2), in order to calculate the split edge amount, it executes the processing of steps S7 to S9, and in order to detect the twist of the conveyor belt 30, it executes the processing of steps S3 to S6 as follows. Here, the processing of steps S8 to S9 and the processing of steps S3 to S6 can be executed in parallel.

[0064] Figure 7A Fig. shows a conveyor belt 30 having a split edge. Since there is a defect at the end of the measurement part, the arithmetic unit 12 cannot calculate the center of the belt based on the positions of both ends in the width direction of the conveyor belt 30. Therefore, the arithmetic unit 12 determines a part where the standard belt width is the same as the measured belt width based on the parts before and after the measurement part with the split edge in the traveling direction of the conveyor belt 30. Specifically, as Figure 7B shown, while moving at a constant measurement interval in the length direction (traveling positive direction and traveling negative direction) of the conveyor belt 30, a part where the standard belt width is the same as the measured belt width is determined. The measurement interval can be set to a value in the range of, for example, 0.1 mm to 0.5 mm. The arithmetic unit 12 determines the position closest to the measurement part with the split edge and where the standard belt width is the same as the measured belt width based on the accumulated surface shape data of the conveyor belt 30. In Figure 7B , the determined positions (determined positions) are represented by "i" and "j".

[0065] The arithmetic unit 12 infers both ends in the width direction of the conveyor belt 30 (belt ends) (step S7). As Figure 7C shown, the arithmetic unit 12 draws inference lines connecting the ends at the determined position "i" and the ends at the determined position "j" on both sides in the width direction and uses them as the inferred belt ends 114.

[0066] The arithmetic unit 12 detects the defect amount and the defect position (step S8), and calculates the split edge amount (step S9). As Figure 7EAs shown, the arithmetic unit 12 determines the defective part 17 as the area surrounded (clamped) by the inferred belt ends 114 and within the range where the thickness of the conveyor belt 30 is 0 in the surface shape data. The arithmetic unit 12 further determines the position and size of the defective part 17 and calculates the amount of edge cracking.

[0067] In addition, the arithmetic unit 12 calculates the center position in the width direction of the conveyor belt 30 (step S3). When it is determined that "there is edge cracking", as Figure 7D shown, the arithmetic unit 12 calculates the calculation belt center 115 based on the inferred belt ends 114 on both sides.

[0068] The arithmetic unit 12 compares the calculation belt center 115 with the standard belt center to determine whether the conveyor belt 30 is bent (step S4).

[0069] When the calculation belt center 115 is the same as the standard belt center (yes in step S4), the arithmetic unit 12 determines that the measured conveyor belt 30 is not bent (step S5). When the calculation belt center 115 deviates from the standard belt center (no in step S4), the arithmetic unit 12 determines that the measured conveyor belt 30 is bent.

[0070] When it is determined that "there is bending" (no in step S4), the arithmetic unit 12 calculates the amount of bending 116 of the conveyor belt 30 based on the offset amount of the center position (refer to Figure 7D )(step S6).

[0071] As described above, the monitoring method executed by the monitoring device 10 of the present embodiment includes a surface shape measurement process and a determination process. The surface shape measurement process corresponds to step S1 above, irradiates line laser in the width direction of the belt so that at least both end portions in the width direction of the belt are included in the irradiation range, and measures the surface shape of the belt. The determination process corresponds to steps S2 to S9 above, determines the positions of both end portions in the width direction of the belt at the measurement portion based on the data of the surface shape measured in the measurement process, and determines whether the belt is bent or has edge cracking based on the determined positions of both end portions in the width direction of the belt.

[0072] <Belt management method>

[0073] Using the above monitoring method, the conveyor belt 30 is managed (monitored) based on the calculated surface shape of the conveyor belt 30. When it is determined that there is bending or edge cracking, the monitoring device 10 can report the abnormality of the conveyor belt 30 to the operator or stop the conveyor belt 30. In addition, the monitoring device 10 can further determine whether the thickness of the conveyor belt 30 is sufficient based on the surface shape of the conveyor belt 30. In this way, abnormalities (such as bending and edge cracking) of the conveyor belt 30 can be detected and the abnormalities can be dealt with as early as possible.

[0074] As described above, the monitoring method and the monitoring device 10 of the present embodiment can monitor both the bending and the edge cracking of the belt without performing special processing on the belt through the above structure. In addition, problems such as breakage of the belt can be suppressed based on the determination of no bending and edge cracking of the belt.

[0075] The embodiments of the present disclosure have been described based on the respective drawings and examples, but it should be noted that those skilled in the art can easily make various deformations or corrections based on the present disclosure. Therefore, it should be noted that these deformations or corrections are included within the scope of the present disclosure. For example, the functions and the like included in each structural part or each step (process) can be reconfigured in a logically non - contradictory manner, multiple structural parts or steps can be combined into one, or can be divided. The embodiments of the present disclosure can also be implemented as a program executed by a processor included in a device or a storage medium recording the program. It should be understood that they are also included within the scope of the present disclosure.

[0076] In the above - described embodiment, although it is described that there are two laser sensors 11, there may be three or more. By increasing the laser sensors 11, it is possible to cope with a wider belt.

[0077] Description of Reference Numerals

[0078] 1... Belt conveyor; 10... Monitoring device; 11, 11a, 11b... Laser sensors; 12... Arithmetic device; 13... Conveyor belt operation information; 14... Both ends in the width direction; 15... Calculated belt center; 16... Amount of bending; 17... Defective part; 20... Pulley; 21... Center of the pulley; 30... Conveyor belt; 31... Surface of the conveyor belt; 114... Inferred belt end; 115... Calculated belt center; 116... Amount of bending.

Claims

1. A monitoring method for monitoring a belt driven by a driving unit in a traveling direction, wherein the monitoring method is characterized in that it includes: a surface shape measuring step of measuring the surface shape of the belt; and a determination step of determining the positions of both end portions in the width direction of the belt at the measurement portion based on the data of the surface shape measured in the surface shape measuring step, and determining whether the belt has a twist or a split edge based on the determined positions of both end portions in the width direction of the belt.

2. The monitoring method according to claim 1, wherein in the surface shape measuring step, a line laser is irradiated in the width direction of the belt in such a manner that at least both end portions in the width direction of the belt are included in the irradiation range, and the surface shape of the belt is measured.

3. The monitoring method according to claim 1 or 2, wherein in the surface shape measuring step, the surface shape of the belt is measured during the operation of the belt, and the data of the measured surface shape is synthesized to generate data of the entire length portion of the belt.

4. The monitoring method according to any one of claims 1 to 3, wherein in the determination step, the width of the belt is calculated based on the positions of both end portions in the width direction of the belt at the measurement portion, and the calculated width is compared with a pre-stored width, thereby determining whether the belt has a split edge.

5. The monitoring method according to any one of claims 1 to 4, wherein in the determination step, when the calculated width is the same as the pre-stored width, the center position of the belt is calculated based on the positions of both end portions in the width direction of the belt at the measurement portion, and the calculated center position is compared with a pre-stored center position, thereby determining whether the belt has a twist.

6. The monitoring method according to any one of claims 1 to 5, wherein in the determination step, when the calculated width is different from the pre-stored width, a portion where the calculated width is the same as the pre-stored width is determined based on the portions before and after the measurement portion in the traveling direction of the belt, the center position of the belt at the measurement portion is inferred based on the positions of both end portions in the width direction of the belt at the portion, and the inferred center position is compared with a pre-stored center position, thereby determining whether the belt has a twist.

7. A monitoring device for monitoring a belt driven by a driving unit in a traveling direction, wherein the monitoring device is characterized by comprising: a measuring device that measures the surface shape of the belt; and an arithmetic device that determines the positions of both end portions in the width direction of the belt at the measurement portion based on the data of the surface shape measured by the measuring device, and determines whether the belt has a twist or a split edge based on the determined positions of both end portions in the width direction of the belt.

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