A frequency conversion speed regulation belt slip detection system based on PLC and proximity switch

Abstract

The utility model relates to the field of logistics belt conveying equipment detection technology, concretely to a kind of frequency control belt slip detection system based on PLC and proximity switch, including PLC, proximity switch, RC filter, frequency converter, driving motor, driving drum, driven drum, relay KQ3, relay SP2, proximity switch is installed in the outer side of driven drum, RC filter circuit is connected between proximity switch output end and PLC, frequency converter is electrically connected with PLC, frequency converter is electrically connected with driving motor, driving motor is drivingly connected with driving drum, driving drum rotates by belt driven driven drum, the parking terminal of relay KQ3 and relay SP2 are all electrically connected with frequency converter. System structure is simple, detection is accurate, anti-interference ability is strong, can effectively improve logistics belt running safety and reliability.

Description

Technical Field

[0001] This utility model relates to the field of testing technology for logistics belt conveyor equipment, specifically a variable frequency speed control belt slippage detection system based on PLC and proximity switch. Background Technology

[0002] In the field of modern logistics and transportation, belt conveyors are widely used in various stages of industrial production due to their high transportation efficiency and wide applicability. To adapt to different transportation needs, most belt systems use frequency converters to achieve speed regulation. However, during frequency conversion speed regulation, slippage can easily occur between the belt and the rollers due to insufficient friction. Slippage not only reduces transportation efficiency but can also lead to belt wear, equipment overheating and damage, and even safety hazards such as material accumulation and production interruption.

[0003] Traditional belt slippage detection methods have significant drawbacks: current-based methods are susceptible to load fluctuations and have low accuracy; speed-sensor-based methods require additional high-precision sensors, resulting in high costs and susceptibility to environmental factors such as dust and vibration, leading to short lifespans; solutions that rely on external detection equipment suffer from poor equipment compatibility and high maintenance difficulty, failing to meet the reliability and cost-effectiveness requirements of industrial environments. Therefore, there is an urgent need to design a slippage detection system that is simple in structure, low in cost, accurate in detection, and integrates core programming logic to address the pain points of existing technologies. Utility Model Content

[0004] The purpose of this invention is to provide a variable frequency speed control belt slippage detection system based on PLC and proximity switch, so as to solve the problems of low detection accuracy, high cost and difficult maintenance of existing detection technologies mentioned in the background art.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a variable frequency speed control belt slippage detection system based on PLC and proximity switch, comprising a PLC, proximity switch, RC filter, frequency converter, drive motor, driving roller, driven roller, relay KQ3, and relay SP2. The proximity switch is installed on the outside of the driven roller. The RC filter circuit is connected in series between the output terminal of the proximity switch and the PLC. The frequency converter is electrically connected to the PLC and the drive motor. The drive motor is driven by the driving roller. The driving roller drives the driven roller to rotate via a belt. Both relay KQ3 and relay SP2 are electrically connected to the stop terminal of the frequency converter.

[0006] Preferably, it also includes an alarm device, which is connected to the PLC.

[0007] Preferably, it also includes an alarm display, which is connected to the PLC.

[0008] Preferably, the PLC is an AB 1756-L71 PLC, which has a built-in high-speed counter, system timer, data register and timer.

[0009] Compared with the prior art, the beneficial effects of this utility model are: 1. High detection accuracy: The driven roller rotation signal is collected by a proximity switch. The sensing frequency of the proximity switch is matched with the speed of the driven roller to accurately calculate the rotation cycle. Based on the frequency-cycle matching relationship and the logic of three consecutive verifications, the slippage is accurately judged, and the detection accuracy reaches 100%, with no missed or false judgments. 2. High degree of automation: No manual intervention is required. From signal acquisition and cycle calculation to slippage judgment and shutdown alarm, the entire process is automated, reducing the intensity of manual operation. 3. Strong anti-interference capability: RC filter circuit suppresses electromagnetic interference, PLC stably captures pulses; dual output redundancy design ensures reliable shutdown command and adapts to complex industrial environments; 4. Low cost and easy maintenance: It adopts conventional proximity switches and AB 1756-L71 PLC, without the need for additional high-precision equipment, which facilitates later maintenance and parameter adjustment (such as extending the period range of the frequency band). 5. High safety: The combination of 10-second delay interlock shutdown and audible and visual alarms can promptly prevent equipment damage and production accidents caused by slippage, thus improving the reliability of system operation.

[0010] 6. Wide range of applications: This system is suitable for various variable frequency speed control logistics belts, especially in industrial production scenarios where belt operation stability is required (such as coking plants, mines, ports, etc.), and has good promotion and application value. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structural principle of the variable frequency speed control belt slippage detection system based on PLC and proximity switch of this utility model. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this utility model clear and complete, the embodiments of this utility model will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some, not all, embodiments of this utility model, and are merely used to explain the embodiments of this utility model. They are not intended to limit the embodiments of this utility model. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model. Example:

[0013] Please see Figure 1This utility model provides a technical solution: a variable frequency speed control belt slippage detection system based on PLC and proximity switch, including a PLC, proximity switch, RC filter, frequency converter, drive motor, driving roller, driven roller, relay KQ3, and relay SP2. The proximity switch is installed on the outside of the driven roller, 5mm away from the surface of the driven roller. The proximity switch generates a magnetic field to sense the metal driven roller, triggering a pulse signal once per revolution of rotation, accurately acquiring the rotation state of the driven roller. The RC filter is connected in series between the output of the proximity switch and the PLC, which can effectively filter out external electromagnetic interference, avoid pulse signal distortion, and ensure the stability of data acquisition. The frequency converter is electrically connected to the PLC and the drive motor. The drive motor is connected to the driving roller via a belt drive. As the drum rotates, a vector control frequency converter is selected, which can adjust the motor speed according to the PLC instructions to realize belt frequency conversion speed regulation. At the same time, the frequency converter transmits the real-time operating frequency to the PLC's data register F8:0 through a 4-20mA current signal, providing frequency reference data for the PLC's "slippage judgment programming statement" to ensure the accuracy of the judgment logic. To improve system safety, this embodiment is designed with relays KQ3 and SP2, both of which are electrically connected to the frequency converter's stop terminal, forming a dual-output redundant design for the stop command. This avoids the stop command failing due to a single relay failure. When the belt slips, the driven drum speed deviates from the driving drum speed. This deviation is transmitted to the PLC through the pulse signal change of the proximity switch, triggering the PLC to calculate the abnormal cycle. Finally, the PLC issues a stop command to achieve the stop.

[0014] The PLC used in this embodiment is an AB 1756-L71 PLC, used for data processing, logic judgment, and instruction output. It has built-in high-speed counting function, system timer S:39, data register F8:1, and timer T4:0. The proximity switch is a PNP type inductive proximity switch, which collects the pulse signal of the driven roller rotation. The pulse signal is transmitted to the PLC. The PLC has a pre-set program to realize signal acquisition, cycle calculation, slippage judgment, interlock control, and alarm functions. The PLC calculates the matching relationship between the rotation cycle and the frequency of the inverter to determine slippage, which can trigger a 10-second delay interlock shutdown and alarm. The inverter is used to control the speed of the drive motor and is also electrically connected to the PLC, transmitting the operating frequency data to the PLC's data register in real time.

[0015] The variable frequency speed control belt slippage detection system based on PLC and proximity switch in this embodiment also includes an alarm device. The alarm device is electrically connected to the PLC and can emit audible and visual signals to remind the operator to handle the situation in a timely manner.

[0016] The variable frequency speed control belt slippage detection system based on PLC and proximity switch in this embodiment also includes an alarm display. The alarm display is electrically connected to the PLC and can communicate bidirectionally with the PLC. The operator can view the periodic data stored in data register F8:1, the frequency converter data in data register F8:0, and the belt slippage status in real time through the alarm display. At the same time, the operator can send start and stop commands through the alarm display to control the operation of the system.

[0017] In this embodiment, the PLC is configured with belt running signal input port I:0.1 / 0, which can receive the drive motor running feedback signal to ensure that the motor does not misjudge slippage when it stops, and further improve the system status monitoring.

[0018] The working process of the variable frequency speed control belt slippage detection system based on PLC and proximity switch in this embodiment is as follows: S1. System startup; S2. The proximity switch collects the pulse signal of the driven roller, and after RC filtering, it is transmitted to the PLC high-speed counter port I:0.0 / 0; S3, the high-speed counter counts pulses and resets the cycle calculation when the system starts. When the high-speed counter reaches the preset value of 1, the PLC calls the system timer S:39 to record the current timestamp, calculates the time difference with the previous pulse, and stores it in the data register F8:1. S4. The PLC reads the real-time frequency of the inverter (F8:0), calls the preset "Frequency-Normal Cycle Range", and determines whether the actual cycle F8:1 and the normal cycle range exceed the limit for three consecutive cycles. If yes, proceed to step S5; otherwise, proceed to step S6. S5. Mark the slippage state, the PLC executes interlock control and alarm control, starts timer 4.0, and executes step S7; S6. Reset the slip count, clear the slip marker, and return to step S2; S7. Determine if the 10-second delay has elapsed; if the 10-second delay has elapsed, proceed to step S8; if the delay has not elapsed, proceed to step S9. S8. Output a stop command to control relay KQ3 or relay SP2 to close, so as to prevent the stop command from failing due to a single relay failure, trigger an audible and visual alarm, and execute step S10. S9. Continuously monitor for slippage for up to 10 seconds; S10. After troubleshooting, the slippage state is reset, the timer and alarm are reset, and the process returns to step S2.

[0019] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A variable frequency speed control belt slippage detection system based on PLC and proximity switches, characterized in that: The system includes a PLC, proximity switch, RC filter circuit, frequency converter, drive motor, driving roller, driven roller, relay KQ3, and relay SP2. The proximity switch is installed on the outside of the driven roller. The RC filter circuit is connected in series between the output terminal of the proximity switch and the PLC. The frequency converter is electrically connected to the PLC and the drive motor. The drive motor is connected to the driving roller via a drive belt. The driving roller drives the driven roller to rotate. Both relay KQ3 and relay SP2 are electrically connected to the stop terminal of the frequency converter.

2. The variable frequency speed control belt slippage detection system based on PLC and proximity switch according to claim 1, characterized in that: It also includes an alarm device, which is electrically connected to the PLC.

3. The variable frequency speed control belt slippage detection system based on PLC and proximity switch according to claim 1, characterized in that: It also includes an alarm display, which is electrically connected to the PLC.

4. The variable frequency speed control belt slippage detection system based on PLC and proximity switch according to claim 1, characterized in that: The PLC is an AB 1756-L71 PLC, which has a built-in high-speed counter, system timer, data register and timer.

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