Detection and verification method for longitudinal tearing cracks of mineral conveying belt

Abstract

The invention relates to a method for detecting and checking longitudinal tearing cracks of a mineral conveying belt, which comprises the following steps of: taking a'conveying mileage-ultrasonic highest amplitude 'envelope line of a mineral conveying belt system under the conditions of stability and good running state as a standard envelope line; acquiring graphic data information of a joint signal in the standard envelope line; the standard envelope line and the real-time detection envelope line of the current conveying belt are displayed on the same screen, so that the real-time detection envelope line of the conveying belt is compared with the standard envelope line in real time, and when the real-time detection envelope line of the conveying belt is abnormal, the real-time detection envelope line of the conveying belt is detected according to the obtained graphic data information of the joint signal. The joint signal in the real-time detection envelope line is determined and eliminated, so that the corresponding position of the abnormal real-time detection envelope line on the conveying belt is determined, the influence of the position of the joint of the conveying belt on longitudinal tear crack detection is eliminated, and the detection precision of the position of the longitudinal tear crack is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of ultrasonic detection, and in particular to a detection and verification method for a longitudinal tear seam of a mineral conveyor belt. Background Art

[0002] Conveyor belts are the lifeline of the mining industry, used to transport and carry various minerals. Minerals are stacked on the conveyor belt during transportation, which will cause great wear on the upper surface of the conveyor belt and even cause longitudinal tears. If the longitudinal tears are not discovered in time and the operation continues, the longitudinal tears will gradually tear open and eventually cause the conveyor belt to tear. The strong elastic force during tearing will overturn the entire conveyor belt and the equipment on the machine, causing serious production safety accidents. At present, the domestic main method is to take pictures and identify the upper surface of the conveyor belt through high-speed smart cameras. Since the longitudinal tears themselves are relatively hidden and difficult to be identified, and the longitudinal tears only occur on the upper surface of the conveying section of the conveyor belt, when the conveyor belt is in the process of transporting minerals, the minerals are very likely to cover the entire longitudinal tear on the outer surface of the conveyor belt, resulting in the high-speed smart camera being unable to detect the longitudinal tear in time, which has a great impact on the inspection results of the conveyor belt. In response to the above problem, the applicant's prior Chinese patent CN118090924A discloses a method for detecting longitudinal tear seams of conveyor belts, wherein an ultrasonic detector is arranged on the lower surface of the conveying section of the conveyor belt. The transmission range of the ultrasonic wave emitted by the ultrasonic detector covers the width direction of the conveying section of the conveyor belt. In at least one conveying length cycle of the conveyor belt, echoes are continuously acquired and recorded for positioning, thereby effectively detecting the longitudinal tear seams of the conveyor belt during the transportation operation of the conveyor belt, and drawing an envelope curve of "transportation mileage-ultrasonic maximum amplitude" for the recorded ultrasonic reception conditions, and judging whether there is a longitudinal tear seam on the upper surface of the conveyor belt according to the shape of the envelope curve image.

[0003] In the process of longitudinal tear seam detection, in addition to the fact that mineral stacking will affect the detection accuracy of longitudinal tear seams, the positioning accuracy of the conveyor belt joints will also affect the detection accuracy of longitudinal tear seams. In the actual detection process, since the conveyor belts used in mines can be more than 20km long, a joint will be set every 200m on the conveyor belts. The joints will cause false alarms in the identification of longitudinal tear seams. Multiple false alarms seriously affect the detection accuracy of longitudinal tear seams. Therefore, it is necessary to accurately locate the joints of the conveyor belts during the longitudinal tear seam detection process to reduce the workload of downtime inspections caused by false alarms in longitudinal tear seam detection. Therefore, the applicant's prior Chinese patent CN118090904A discloses a joint positioning method for detecting longitudinal tear seams of mineral conveyor belts, in which a first probe wheel simultaneously emits a highly penetrating low-frequency ultrasonic wave and a 0° low-frequency ultrasonic wave. The highly penetrating low-frequency ultrasonic wave passes through the conveyor belt and is received by the second probe wheel, and the 0° low-frequency ultrasonic wave is received by the first probe wheel after passing through the thickness direction of the conveyor belt. At the same time, the encoder continuously encodes and records the conveying mileage. According to the difference in the waveform envelope diagram of "conveying mileage-ultrasonic wave maximum amplitude", it is determined whether the first probe wheel and the second probe wheel are at the joint of the conveyor belt at this time.

[0004] However, in the subsequent actual detection process, it was found that the signal of the joint position and the signal of the longitudinal tear position were very close, which could easily lead to misjudgment of the longitudinal tear seam signal on the existing detection instruments. Therefore, before judging the longitudinal tear seam signal, it is necessary to further verify the relevant detection signals to eliminate the influence of the joint position signal on the longitudinal tear position signal. Summary of the invention

[0005] The problem to be solved by the present invention is to provide a method for detecting and verifying the longitudinal tear seam of a mineral conveyor belt, which can eliminate the influence of the conveyor belt joint position on the longitudinal tear seam detection and further improve the detection accuracy of the longitudinal tear seam position. The adopted technical solution is as follows: A method for detecting and verifying a longitudinal tear seam of a mineral conveyor belt comprises the following steps: (1) An ultrasonic detector is arranged on the lower surface of the conveying section of the conveyor belt, the ultrasonic detector includes at least one transmitting probe wheel and at least one receiving probe wheel, each probe wheel is in contact with the lower surface of the conveying section of the conveyor belt, and the transmission range of the ultrasonic wave emitted by the transmitting probe wheel covers the width direction of the conveying section of the conveyor belt; (2) Start the conveyor belt and keep pressure between the lower surface of the conveyor section of the conveyor belt and the wheel surface of each probe wheel during the transportation operation; (3) The transmitting probe wheel transmits ultrasonic waves, and the receiving probe wheel continuously obtains echoes in the conveyor belt and records the location; (4) Draw the envelope curve of "transmission mileage-ultrasonic maximum amplitude" based on the recorded ultrasonic reception conditions; It is characterized in that it also includes the following steps: (5) Select the envelope of a normal operation of the conveyor belt as the standard envelope, and decompose and identify the graphic features of the standard envelope; (6) Based on the graphic features of the standard envelope, the joint signal in the standard envelope is marked, and the graphic data information of the joint signal is acquired, counted, and analyzed; (7) The standard envelope and the real-time detection envelope of the current conveyor belt are displayed on the same screen, and the real-time detection envelope of the conveyor belt is compared with the standard envelope in real time; when an abnormality occurs in the real-time detection envelope of the conveyor belt, the joint signal in the real-time detection envelope is determined and eliminated according to the graphic data information of the joint signal obtained in step (6), so as to determine the position on the conveyor belt corresponding to the abnormality of the real-time detection envelope.

[0006] In the above step (5), the normal operation of the conveyor belt means that the mineral conveyor belt system is in a stable and good operating state, and the entire conveyor belt runs one circle without load, and a more accurate "transmission mileage-ultrasonic maximum amplitude" envelope is drawn as a standard envelope to accurately locate the joint of the conveyor belt. Therefore, the graphic features of the standard envelope also include the relevant graphic features of the joint signal, which can more directly reflect the joint of the conveyor belt on the standard envelope.

[0007] Under the aforementioned operating conditions, the standard envelope can fully and accurately reflect the various characteristics of the conveyor belt during normal operation, including the conveyor belt's joint signal, as well as more sensitive identification of abnormal phenomena such as possible abnormal jump signals, thereby providing a deeper understanding of the system operation status of the conveyor belt and providing more powerful data support for subsequent real-time detection.

[0008] As a preferred embodiment of the present invention, in step (6), the graphic data information of the joint signal in the standard envelope is marked, counted and analyzed, and the graphic data information at least includes the serial number, position and length of the joint signal. The serial number, position and length of the joint signal are not only the key data information for determining the joint signal in the real-time detection process using the standard envelope, but also can reflect the structural characteristics of the conveyor belt system, and provide a strong basis for timely discovery and handling of fault problems in subsequent detection work.

[0009] As a further preferred embodiment of the present invention, the serial number of the joint signal refers to assigning a unique serial number to each joint signal; the position of the joint signal refers to recording the position of the joint signal on the conveyor belt; the length of the joint signal refers to the actual length of the joint part on the conveyor belt. The serial number information of the joint signal can facilitate subsequent query and analysis; the position information of the joint signal is usually expressed in meters from the starting point.

[0010] As a preferred embodiment of the present invention, in step (1), a transmitting probe wheel and a receiving probe wheel are arranged in parallel on the lower surface of the conveying section of the conveyor belt and are located in the width direction of the conveyor belt; wherein a probe having both transmitting and receiving functions is installed in the transmitting probe wheel, and a probe having only receiving function is installed in the receiving probe wheel; in step (3), the transmitting probe wheel emits a low-frequency ultrasonic wave with strong penetrating power toward the receiving probe wheel, and the low-frequency ultrasonic wave propagates along the width direction of the conveyor belt and is received by the receiving probe wheel; at the same time, the transmitting probe wheel emits a low-frequency ultrasonic wave of 0° toward the conveyor belt, and the low-frequency ultrasonic wave propagates in the thickness direction of the conveyor belt and is reflected at the interface and received by the transmitting probe wheel itself.

[0011] Since the materials and welding processes used in the joint and non-joint parts of the conveyor belt are different, the joint and non-joint parts of the conveyor belt have different acoustic characteristics. Under the same ultrasonic detection sensitivity, the attenuation of the ultrasonic wave passing through the joint is greater than that of the non-joint part. When the ultrasonic wave passes through the non-joint part, the joint part, and the longitudinal tear seam, different reception conditions will occur and different reception waveforms will be displayed. Therefore, in step (3), the transmitting probe wheel simultaneously transmits a low-frequency ultrasonic wave with strong penetrating power and a low-frequency ultrasonic wave with a temperature of 0°. The low-frequency ultrasonic wave with strong penetrating power passes through the conveyor belt and is received by the receiving probe wheel. The low-frequency ultrasonic wave with a temperature of 0° passes through the thickness direction of the conveyor belt and is received by the transmitting probe wheel. According to the different waveform envelope diagrams, it is judged whether the transmitting probe wheel and the receiving probe wheel are at the joint of the conveyor belt at this time.

[0012] Since the joint position is relatively fixed, the calibration and positioning of the transmission belt over a long distance is achieved through the distance between the relative positions of the joints. As a further preferred embodiment of the present invention, during the detection and verification process, an encoder is used to self-calibrate and correct the real-time conveying mileage of the conveyor belt, record the positions of the transmitting probe wheel and the receiving probe wheel each time they pass through a joint, and the number of encoder pulses when they pass through two adjacent joints, divide the joint spacing by the number of pulses to obtain the distance represented by each encoder pulse; then collect and measure the number of encoder pulses, and when the number of pulses missing reaches a specified proportion, when the transmitting probe wheel and the receiving probe wheel pass through the next joint, the position information of the recorded conveying mileage is automatically rounded to one multiple of the joint spacing.

[0013] In general, the distance between two adjacent joints of the conveyor belt (i.e., the joint spacing) is certain (usually 200m). The number of encoder pulses is fixed in principle for the transmission mileage of the transmitting probe wheel and the receiving probe wheel within a joint spacing. Therefore, the distance represented by each encoder pulse can be obtained through the joint spacing and the number of pulses. On this basis, the number of encoder pulses is collected and measured. When the conveyor belt is uneven or the encoder wheel vibrates and hangs in the air, resulting in idling, the number of encoder pulses is missing. When the number of missing pulses reaches a specified ratio, when the transmitting probe wheel and the receiving probe wheel pass the next joint, the position information of the recorded transmission mileage is automatically rounded to one multiple of the joint spacing, and a self-calibration and correction is automatically completed.

[0014] Compared with the prior art, the present invention has the following advantages: The method for detecting and verifying the longitudinal tear seam of a mineral conveyor belt of the present invention uses the "transport mileage-ultrasonic maximum amplitude" envelope of the mineral conveyor belt system when the system is in a stable and good operating state as the standard envelope, and obtains the graphic data information of the joint signal in the standard envelope; the standard envelope and the real-time detection envelope of the current conveyor belt are displayed on the same screen, so that the real-time detection envelope of the conveyor belt is compared with the standard envelope in real time. When an abnormality occurs in the real-time detection envelope of the conveyor belt, the joint signal in the real-time detection envelope is determined and eliminated according to the graphic data information of the joint signal obtained, so as to determine the position on the conveyor belt corresponding to the abnormality of the real-time detection envelope, eliminate the influence of the conveyor belt joint position on the longitudinal tear seam detection, and further improve the detection accuracy of the longitudinal tear seam position. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of a process of a preferred embodiment of the present invention; Figure 2 It is a structural demonstration diagram of a preferred embodiment of the present invention; Figure 3 This is a demonstration diagram of the encoder performing self-calibration and correction; Among them, the markings are: 1-transmitting probe wheel, 2-receiving probe wheel, and A and B are two adjacent joints on the conveyor belt. DETAILED DESCRIPTION

[0016] The following is a further description of the preferred embodiments of the present invention in conjunction with the accompanying drawings.

[0017] like Figure 1 As shown, a method for detecting and verifying the longitudinal tear seam of a mineral conveyor belt comprises the following steps: (1) An ultrasonic detector is arranged on the lower surface of the conveying section of the conveyor belt, and the ultrasonic detector includes at least one transmitting probe wheel 1 and at least one receiving probe wheel 2. The transmitting probe wheel 1 and the receiving probe wheel 2 are arranged in parallel on the lower surface of the conveying section of the conveyor belt and are located in the width direction of the conveyor belt. Each probe wheel is in contact with the lower surface of the conveying section of the conveyor belt, and the transmission range of the ultrasonic wave emitted by the transmitting probe wheel 1 covers the width direction of the conveying section of the conveyor belt; wherein, the transmitting probe wheel 1 is installed with a probe having both transmitting and receiving functions, and the receiving probe wheel 2 is installed with a probe having only receiving function; (2) Start the conveyor belt and keep pressure between the lower surface of the conveyor section of the conveyor belt and the wheel surface of each probe wheel during the transportation operation; (3) If Figure 2 As shown, the transmitting probe wheel 1 transmits a low-frequency ultrasonic wave with strong penetrating power toward the receiving probe wheel 2. The low-frequency ultrasonic wave propagates along the width direction of the conveyor belt and is received and located and recorded by the receiving probe wheel 2. At the same time, the transmitting probe wheel 1 transmits a low-frequency ultrasonic wave of 0° toward the conveyor belt. The low-frequency ultrasonic wave propagates along the thickness direction of the conveyor belt and is reflected at the interface and received and located and recorded by the transmitting probe wheel 1 itself. (4) Draw the envelope curve of "transmission mileage-ultrasonic maximum amplitude" based on the recorded ultrasonic reception conditions; (5) Select the envelope of a normal operation of the conveyor belt as the standard envelope, and decompose and identify the graphic features of the standard envelope; (6) Based on the graphic features of the standard envelope, the joint signals in the standard envelope are marked, and the graphic data information of the joint signals is obtained, counted, and analyzed; the graphic data information at least includes the serial number, position, and length of the joint signal, wherein the serial number of the joint signal refers to assigning a unique serial number to each joint signal, the position of the joint signal refers to recording the position of the joint signal on the conveyor belt, and the length of the joint signal refers to the actual length of the joint part on the conveyor belt; (7) The standard envelope and the real-time detection envelope of the current conveyor belt are displayed on the same screen, and the real-time detection envelope of the conveyor belt is compared with the standard envelope in real time; when an abnormality occurs in the real-time detection envelope of the conveyor belt, the joint signal in the real-time detection envelope is determined and eliminated according to the graphic data information of the joint signal obtained in step (6), so as to determine the position on the conveyor belt corresponding to the abnormality of the real-time detection envelope.

[0018] When the mineral conveyor belt system is in a stable and good operating state, the conveyor belt operates normally, and the entire conveyor belt runs one circle without load, a more accurate "conveying mileage-ultrasonic maximum amplitude" envelope is drawn as the standard envelope to accurately locate the joint of the conveyor belt. Therefore, the graphic features of the standard envelope also include the relevant graphic features of the joint signal, which can more directly reflect the joint of the conveyor belt on the standard envelope. Under this operating condition, the standard envelope can comprehensively and accurately reflect the various characteristics of the normal operation of the conveyor belt, including the joint signal of the conveyor belt, and more sensitively identify abnormal phenomena such as abnormal jump signals that may exist, so as to have a deeper understanding of the system operation status of the conveyor belt, and provide more powerful data support for the subsequent real-time detection process. The serial number, position and length of the joint signal are not only the key data information for determining the joint signal in the real-time detection process using the standard envelope, but also can reflect the structural characteristics of the conveyor belt system, and provide a strong basis for timely discovery and handling of fault problems in subsequent detection work.

[0019] Since the materials and welding processes used in the joints and non-joints of the conveyor belt are different, the joints and non-joints of the conveyor belt have different acoustic characteristics. Under the same ultrasonic detection sensitivity, the attenuation of ultrasonic waves passing through the joints is greater than that of non-joints. When ultrasonic waves pass through non-joints, joints, and longitudinal tear seams, different reception conditions will occur and different reception waveforms will appear. Therefore, if Figure 2 As shown, the transmitting probe wheel 1 simultaneously transmits a highly penetrating low-frequency ultrasonic wave and a 0° low-frequency ultrasonic wave. The highly penetrating low-frequency ultrasonic wave passes through the conveyor belt and is received by the receiving probe wheel 2. The 0° low-frequency ultrasonic wave passes through the thickness direction of the conveyor belt and is received by the transmitting probe wheel 1 itself. Based on the difference in the waveform envelope diagram, it is determined whether the transmitting probe wheel 1 and the receiving probe wheel 2 are at the joint of the conveyor belt at this time.

[0020] Since the joint position is relatively fixed, the distance between the joints is used to realize the calibration and positioning of the transmission belt over a long distance. Therefore, during the inspection and verification process, an encoder is required to self-calibrate and correct the real-time transmission mileage of the conveyor belt, record the position of the transmitting probe wheel 1 and the receiving probe wheel 2 when they pass each joint position and the position of the two adjacent joint positions (such as Figure 3As shown, the transmitting probe wheel 1 and the receiving probe wheel 2 measure the number of pulses of the encoder when they arrive at the joint A at the joint B and pass through a joint spacing (the distance of the conveying mileage). The joint spacing is divided by the number of pulses to obtain the distance represented by each pulse of the encoder. Then the number of encoder pulses is collected and measured. When the number of pulses is missing reaches a specified ratio, when the transmitting probe wheel 1 and the receiving probe wheel 2 pass the next joint, the position information of the conveying mileage is automatically rounded to one multiple of the joint spacing. The distance represented by each pulse of the encoder is obtained through the joint spacing and the number of pulses. On this basis, the number of encoder pulses is collected and measured. When the conveying belt is uneven or the encoder wheel vibrates and hangs in the air, causing idling, the number of encoder pulses is missing. When the number of pulses is missing reaches a specified ratio, when the transmitting probe wheel 1 and the receiving probe wheel 2 pass the next joint, the position information of the conveying mileage is automatically rounded to one multiple of the joint spacing, and a self-calibration and correction is automatically completed.

[0021] The method for detecting and verifying the longitudinal tear seam of a mineral conveyor belt of the present invention uses the "transport mileage-ultrasonic maximum amplitude" envelope of the mineral conveyor belt system when the system is in a stable and good operating state as the standard envelope, and obtains the graphic data information of the joint signal in the standard envelope; the standard envelope and the real-time detection envelope of the current conveyor belt are displayed on the same screen, so that the real-time detection envelope of the conveyor belt is compared with the standard envelope in real time. When an abnormality occurs in the real-time detection envelope of the conveyor belt, the joint signal in the real-time detection envelope is determined and eliminated according to the graphic data information of the joint signal obtained, so as to determine the position on the conveyor belt corresponding to the abnormality of the real-time detection envelope, eliminate the influence of the conveyor belt joint position on the longitudinal tear seam detection, and further improve the detection accuracy of the longitudinal tear seam position.

[0022] In addition, it should be noted that the names of the various parts of the specific embodiments described in this specification may be different, and any equivalent or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. The technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for detecting and verifying the longitudinal tear seam of a mineral conveyor belt, comprising the following steps: (1) An ultrasonic detector is arranged on the lower surface of the conveying section of the conveyor belt, the ultrasonic detector includes at least one transmitting probe wheel and at least one receiving probe wheel, each probe wheel is in contact with the lower surface of the conveying section of the conveyor belt, and the transmission range of the ultrasonic wave emitted by the transmitting probe wheel covers the width direction of the conveying section of the conveyor belt; (2) Start the conveyor belt and keep pressure between the lower surface of the conveyor section of the conveyor belt and the wheel surface of each probe wheel during the transportation operation; (3) The transmitting probe wheel transmits ultrasonic waves, and the receiving probe wheel continuously obtains echoes in the conveyor belt and records the location; (4) Draw the envelope curve of "transmission mileage-ultrasonic maximum amplitude" based on the recorded ultrasonic reception conditions; It is characterized in that it also includes the following steps: (5) Select the envelope of a normal operation of the conveyor belt as the standard envelope, and decompose and identify the graphic features of the standard envelope; (6) Based on the graphic features of the standard envelope, the joint signal in the standard envelope is marked, and the graphic data information of the joint signal is acquired, counted, and analyzed; (7) The standard envelope and the real-time detection envelope of the current conveyor belt are displayed on the same screen, and the real-time detection envelope of the conveyor belt is compared with the standard envelope in real time; when an abnormality occurs in the real-time detection envelope of the conveyor belt, the joint signal in the real-time detection envelope is determined and eliminated according to the graphic data information of the joint signal obtained in step (6), so as to determine the position on the conveyor belt corresponding to the abnormality of the real-time detection envelope.

2. The method for detecting and verifying the longitudinal tear seam of a mineral conveyor belt according to claim 1, characterized in that: In the step (6), the graphic data information of the joint signal in the standard envelope is marked, counted and analyzed, and the graphic data information at least includes the serial number, position and length of the joint signal.

3. The method for detecting and verifying the longitudinal tear seam of a mineral conveyor belt according to claim 2, characterized in that: The serial number of the joint signal refers to assigning a unique serial number to each joint signal; the position of the joint signal refers to recording the position of the joint signal on the conveyor belt; the length of the joint signal refers to the actual length of the joint part on the conveyor belt.

4. The method for detecting and verifying the longitudinal tear seam of a mineral conveyor belt according to any one of claims 1 to 3, characterized in that: In the step (1), a transmitting probe wheel and a receiving probe wheel are arranged in parallel on the lower surface of the conveying section of the conveyor belt and are located in the width direction of the conveyor belt; wherein a probe having both transmitting and receiving functions is installed in the transmitting probe wheel, and a probe having only receiving function is installed in the receiving probe wheel; in the step (3), the transmitting probe wheel emits a low-frequency ultrasonic wave with strong penetrating power toward the receiving probe wheel, and the low-frequency ultrasonic wave is received by the receiving probe wheel after propagating along the width direction of the conveyor belt; at the same time, the transmitting probe wheel emits a low-frequency ultrasonic wave of 0° toward the conveyor belt, and the low-frequency ultrasonic wave is reflected at the interface after propagating along the thickness direction of the conveyor belt and is received by the transmitting probe wheel itself.

5. The method for detecting and verifying the longitudinal tear seam of a mineral conveyor belt according to claim 4, characterized in that: During the detection and verification process, the encoder is used to self-calibrate and correct the real-time conveying mileage of the conveyor belt, record the position of the transmitting probe wheel and the receiving probe wheel when they pass each joint and the number of encoder pulses when they pass two adjacent joints, and divide the joint spacing by the number of pulses to obtain the distance represented by each encoder pulse; then the number of encoder pulses is collected and measured. When the number of pulses missing reaches the specified proportion, the transmitting probe wheel and the receiving probe wheel pass the next joint, and the recorded conveying mileage position information is automatically rounded to one multiple of the joint spacing.

Images