Belt conveyor reverse detection method

Abstract

The present application relates to the technical field of belt conveyor detection equipment, and particularly relates to a belt conveyor reverse detection method, which comprises a driven roller, the end of the driven roller is provided with an inductive sheet coaxially rotating with the driven roller, the outer side of the driven roller is provided with a digital signal induction switch matched with the inductive sheet, and the digital signal induction switch is connected with a PLC; the inductive sheet comprises an inductive sheet one and an inductive sheet two, the inductive sheet one and the inductive sheet two are respectively in arc-shaped structures, and the inductive sheet one and the inductive sheet two are intermittently arranged. The present application collects four connected pulse times through the digital signal induction switch through the PLC, compares the pulse times in size to judge whether the belt conveyor is reversed, can quickly and accurately detect the belt conveyor in the case that the backstop and the brake are invalid, and timely alarms and reminds the equipment supervisor.

Description

Technical Field

[0001] This invention relates to the field of belt conveyor testing equipment technology, and in particular to a method for detecting belt conveyor reversal. Background Technology

[0002] When conveyor belts are transporting materials, their backstops and brakes are prone to failure when the belt rises to a large height or angle. After these devices fail, the belt may reverse after a heavy-load shutdown, causing material to spill from the rear of the belt. Belt reversal is usually detected by on-site monitoring personnel based on the material position and spillage. Only when the backstop or brake fails severely, resulting in obvious reversal, can it be reported to maintenance personnel through equipment management channels, making the inspection method rather slow. Summary of the Invention

[0003] To solve the above-mentioned technical problems, this invention proposes a belt conveyor reversal detection method, which can effectively detect the belt conveyor operation when the brake and backstop fail, even when the belt conveyor has a large climbing height or angle.

[0004] One aspect of this invention provides a method for detecting belt conveyor reversal, including a belt conveyor reversal detection device comprising a driven roller, an induction plate coaxially rotating with the driven roller at its end, and a digital signal induction switch adapted to the induction plate disposed on the outer side of the driven roller, the digital signal induction switch being connected to a PLC; the induction plate includes induction plate one and induction plate two, both induction plate one and induction plate two being arc-shaped structures, and induction plate one and induction plate two being intermittently arranged, and the method is implemented according to the following steps:

[0005] The arc length of sensor 1 is L1, the arc length of sensor 2 is L2, the radius of sensor 1 and sensor 2 is R, the radius of driven roller is Rc, the sensing time of sensor 1 is T1, the sensing time of sensor 2 is T3, and the intermittent time intervals of sensor 1 and sensor 2 are T2 and T4, respectively.

[0006] When the belt conveyor is running normally, the time it takes for the driven drum to complete one revolution is T.

[0007] T = T1 + T2 + T3 + T4;

[0008] Self-test of the reversing detection device:

[0009] After the belt conveyor is powered on and running for a period of time, the PLC extracts the time of four consecutive pulses, sets the maximum value to T4, and then the pulses before T4 are T3, T2, and T1, and the pulses after T4 are T1, T2, and T3. If T1 < T2 < T3 < T4, then it is considered normal.

[0010] Reverse detection:

[0011] After the belt conveyor is powered off, the PLC extracts the time of four consecutive pulses and sets the maximum value to T4. The pulses before T4 are Tc, Tb, and Ta, and the pulses after T4 are Ta, Tb, and Tc. If Ta < Tb < Tc < T4, the belt conveyor is determined to be rotating in the forward direction. If Tc < Tb < Ta < T4, the belt conveyor is determined to be rotating in the reverse direction.

[0012] Compared with existing technologies, the advantages of this detection method are as follows:

[0013] The PLC collects the duration of four consecutive pulses through a digital signal sensor switch, compares the magnitudes of the pulse durations to determine whether the belt conveyor is reversing, and can quickly and accurately detect the belt conveyor in the event of failure of the backstop and brake, and promptly alert the equipment supervisor.

[0014] Furthermore, the preferred embodiment adopted in this invention is:

[0015] If the hardware delay time of the digital input is Ty, the PLC delay time is Tr, and the PLC scan cycle is Ts, then the minimum allowable sensing time of the PLC is Tz = Ts + Ty + Tr.

[0016] To ensure pulse recognition accuracy, T1, T2, T3, and T4 should satisfy the following relationships: T1≥2Tz, T2-T1≥2Tz, T3-T2≥2Tz, T4-T3≥2Tz; therefore, T≥20*Tz, and the optimal value of T is 20Tz.

[0017] The rated operating speed of the belt conveyor is V. If the radius of the driven roller is set to Rc≥10V*Tz / π and R≥Rc, then the arc lengths of the two induction plates are L1≥2V*Tz and L2≥4V*Tz. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, are not intended to limit the scope of the invention. In the drawings:

[0019] Figure 1 This is a schematic diagram of the structure of the present invention;

[0020] Figure 2 A schematic diagram of the pulse signal generated by the time of four consecutive pulses for one revolution of the driven drum;

[0021] In the diagram: driven roller 1; induction plate support rod 2; induction plate one 3; induction plate two 4; digital signal induction switch 5; connecting shaft 6. Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. Here, the illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention.

[0023] A belt conveyor reversal detection device mainly includes a driven roller. A connecting shaft is fixedly connected to the center of one end of the driven roller's central shaft, and the connecting shaft can rotate coaxially with the central shaft of the driven roller. A sensor support rod is fixedly installed on the connecting shaft. A sensor first is fixedly installed at one end of the sensor support rod, and a sensor second is installed at the other end. A digital signal sensing switch (in this embodiment, the digital signal sensing switch is a proximity switch) adapted to the two sensors is installed on the outside of the driven roller. The digital signal sensing switch is connected to a PLC, and the PLC collects pulse time through the digital signal sensing switch and the sensors. The PLC is also connected to a human-machine interface and an audible and visual alarm.

[0024] In this embodiment, the center of the sensor support rod is fixedly connected to the connecting shaft, and the two ends of the sensor support rod form a certain angle.

[0025] In this embodiment, sensor sheet one and sensor sheet two are arc-shaped structures with equal radii, and sensor sheet one and sensor sheet two are intermittently arranged during installation.

[0026] When performing belt conveyor reversal detection, this device shall be used as follows:

[0027] First, set the arc length of sensor 1 to L1 and the arc length of sensor 2 to L2, with L1 < L2. The radii of sensor 1 and sensor 2 are both R, the radius of the driven roller is Rc, the sensing time of sensor 1 is T1, the sensing time of sensor 2 is T3, and the intermittent time intervals of sensor 1 and sensor 2 are T2 and T4, respectively.

[0028] When the belt conveyor is running normally, the time it takes for the driven roller to complete one revolution is T. Therefore, T = T1 + T2 + T3 + T4. The pulse signal generated by the PLC is as follows: Figure 2 As shown.

[0029] If the digital input hardware delay time is Ty, the PLC delay time is Tr, and the PLC scan cycle is Ts, then the minimum allowable sensing time of the PLC is Tz = Ts + Ty + Tr.

[0030] To ensure pulse recognition accuracy, T1, T2, T3, and T4 should satisfy the following relationships: T1≥2Tz, T2-T1≥2Tz, T3-T2≥2Tz, T4-T3≥2Tz; therefore, T≥20*Tz, and the optimal value of T is 20Tz.

[0031] The rated operating speed of the belt conveyor is V. If the radius of the driven roller is set to Rc≥10V*Tz / π and R≥Rc, then the arc lengths of the two induction plates are L1≥2V*Tz and L2≥4V*Tz.

[0032] In this embodiment, during the self-test of the belt conveyor reversal detection device:

[0033] After the belt conveyor has been powered on and running normally for more than 10 seconds, the PLC extracts the time of 4 consecutive pulses through the digital signal induction switch. The maximum value of these pulses is set to T4. The pulses before T4 are T3, T2, and T1, and the pulses after T4 are T1, T2, and T3. If T1 < T2 < T3 < T4, then the detection device is considered to be normal.

[0034] When performing a belt conveyor reversal test:

[0035] After the belt conveyor is powered off, the PLC extracts the time of four consecutive pulses and sets the maximum value to T4. The pulses before T4 are Tc, Tb, and Ta, and the pulses after T4 are Ta, Tb, and Tc. If Ta < Tb < Tc < T4, the belt conveyor is determined to be rotating in the forward direction. If Tc < Tb < Ta < T4, the belt conveyor is determined to be rotating in the reverse direction.

[0036] Once the belt conveyor is detected to be reversing, the PLC will display an alarm message indicating that manual reset is required via the human-machine interface, and trigger the on-site audible and visual alarm to continuously alert the on-site equipment supervisors for emergency handling until the latest pulse duration exceeds 30 seconds.

[0037] This detection method uses a PLC to extract digital signal pulse signals from the induction switch and sensor to obtain four consecutive pulse durations. By analyzing the sequence of the lengths of these four consecutive pulse durations, it can quickly and effectively analyze whether the conveyor belt reverses when the backstop and brake fail, providing timely alarm reminders to equipment supervisors. Moreover, this device has a simple structure, few components, is easy to maintain and replace, and has a relatively low cost.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A belt-reversal detection method, characterized by, The belt conveyor reverse detection device comprises a driven roller, an inductive sheet coaxially rotating with the driven roller is arranged at the end of the driven roller, a digital signal inductive switch matched with the inductive sheet is arranged at the outer side of the driven roller, and the digital signal inductive switch is connected with a PLC. The arc length of the inductive sheet one is L1, the arc length of the inductive sheet two is L2, the radius of the inductive sheet one and the inductive sheet two is R, the radius of the driven roller is Rc, the inductive time through the inductive sheet one is T1, the inductive time through the inductive sheet two is T3, and the interval time of the inductive sheet one and the inductive sheet two is T2 and T4 respectively. When the belt conveyor is normally operated, the time length of one circle of the driven roller is T, and T=T1+T2+T3+T4. Self-check of the reverse detection device: After the belt conveyor is operated for a period of time, the PLC extracts four connected pulse times, sets the maximum value as T4, and T3, T2 and T1 are before T4, T1, T2 and T3 are after T4, if T1 Reverse detection: After the belt conveyor is powered off, the PLC extracts four connected pulse times, sets the maximum value as T4, and Tc, Tb and Ta are before T4, Ta, Tb and Tc are after T4, if Ta 2. The belt conveyor reverse detection method according to claim 1, wherein: The digital quantity input hardware delay time is Ty, the PLC delay time is Tr, and the PLC scanning period is Ts, and the minimum inductive time allowed by the PLC is Tz=Ts+Ty+Tr. In order to ensure the pulse recognition degree, T1, T2, T3 and T4 should satisfy the following relationship: T1≥2Tz, T2-T1≥2Tz, T3-T2≥2Tz, and T4-T3≥2Tz, thus T≥20*Tz, and the best value of T is 20Tz. The rated operating speed of the belt conveyor is V, the radius Rc of the driven roller is set to be greater than or equal to 10V*Tz / π, R is greater than or equal to Rc, the arc length L1 of the two inductive sheets is greater than or equal to 2V*Tz, and the arc length L2 of the two inductive sheets is greater than or equal to 4V*Tz. ​

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