Online identification method for broken shaft fault of rocker arm of drum coal mining machine

Abstract

The present invention relates to an online identification method for a broken shaft fault of a rocker arm of a drum coal mining machine, comprising obtaining the real-time three-phase current of the cutting motor of the coal mining machine and the real-time traction speed data of the coal mining machine, performing clock synchronization, and obtaining a sampling time count synchronized with the three-phase current and the traction speed; calculating the real-time three-phase current effective value and its change rate of the cutting motor and the change rate of the traction speed in real time and synchronously with a fixed time step; judging whether the cutting motor is in a current drop state at this time according to the three-phase current and the change rate of the three-phase current effective value; when it is judged that the cutting motor is in a current drop state, judging in combination with the change rate of the traction speed, if a non-broken shaft fault that can cause the current drop state is further excluded, it is judged that a broken shaft fault of the rocker arm has occurred. The present invention can utilize the existing real-time monitoring conditions of the cutting motor current and traction speed to efficiently and accurately identify the broken shaft fault without adding hardware devices.

Description

Technical Field

[0001] The invention relates to a coal mining machine rocker arm fault diagnosis method, in particular to a coal mining machine rocker arm gear box broken shaft fault identification method. Background Art

[0002] As the main mechanical equipment for safe and efficient production in modern mines, the reliability of coal mining machines directly affects the normal operation of the entire coal mining face, especially in automated working faces. The reliable and safe operation of equipment is a key indicator to ensure the reduction of staff and increase of efficiency in the working face.

[0003] The rocker arm is the main power transmission component of the coal mining machine when it is cutting coal. The power consumption of the cutting part accounts for 80%-90% of the power of the entire coal mining machine. According to statistics, in recent years, the rocker arm failure rate of the coal mining machine in a modernized 100 million ton mining area has accounted for an average of 34.2% of the coal mining machine failure rate, of which the rocker arm transmission system failure accounts for more than 80% of all rocker arm failures.

[0004] The main method for coal mining enterprises to diagnose coal mining machine transmission system failures is to regularly extract the gearbox lubricating oil and use iron spectrum analysis to determine the working status trend of the gearbox, which is a lagging diagnosis. Some mines conduct online fault monitoring of rocker arm gearboxes by adding oil quality detection or vibration detection sensor equipment, but the underground working conditions are harsh, and the additional sensor device is installed outside the machine body, which is difficult to protect and difficult to achieve long-term reliable operation. Summary of the invention

[0005] The purpose of the present invention is to provide an online identification method for a broken shaft fault of a rocker arm of a drum coal mining machine, which utilizes the existing real-time monitoring conditions of cutting motor current and traction speed to efficiently and accurately identify the broken shaft fault without adding hardware devices.

[0006] The main technical solutions of the present invention are:

[0007] An online identification method for a broken shaft fault of a rocker arm of a drum coal mining machine comprises the following steps:

[0008] S101: Acquire the real-time three-phase currents Icr, Ics, Ict of the shearer cutting motor and the real-time traction speed Vt of the shearer;

[0009] S102: Perform clock synchronization to obtain a sampling time count tn synchronized with the three-phase currents Icr, Ics, Ict and the traction speed Vt;

[0010] S103: Calculate the real-time three-phase current effective value Ic of the cutting motor and its change rate △Ic / △tn and the change rate of the traction speed △Vt / △tn in real time and synchronously with a fixed time step △tn;

[0011] S104: judging whether the cutting motor is in a current drop state at this time according to the three-phase currents Icr, Ics, Ict and the change rate △Ic / △tn of the three-phase current effective values;

[0012] S105: When it is determined that the cutting motor is in a current drop state, combined with the change rate of the traction speed △Vt / △tn, if non-broken shaft faults that can cause the current drop state are further excluded, it is determined that a rocker arm broken shaft fault has occurred.

[0013] Preferably, the power supply period of the cutting motor is used as the fixed time step Δtn.

[0014] In the step S101, the real-time three-phase currents Icr, Ics and Ict of the cutting motor are obtained by a three-phase current sensor arranged on the main circuit of the cutting motor, and the sampling rate is preferably not less than 500 Hz.

[0015] In the step S101, the real-time traction speed Vt of the coal mining machine is obtained by a speed detection sensor arranged at the rotating shaft of the traction motor, and the sampling rate is preferably greater than or equal to 100 Hz.

[0016] The three-phase current sensor may be a three-phase current transformer, and the speed detection sensor may be an encoder.

[0017] In step S102, the two sets of data, the three-phase currents Icr, Ics, Ict and the traction speed Vt, are synchronously sampled into the data acquisition module through the system clock signal, and the sampling zero point is obtained through the phase-locked loop in the data acquisition module, and the first sampling zero point after the start of acquisition is used as the counting reference zero position.

[0018] In step S104, the current drop state is determined by the following conditions: the effective value of the three-phase current is in a decreasing state, the current drop amplitude exceeds the drop threshold value in a plurality of consecutive analysis cycles, and the cutting motor itself has no fault.

[0019] The absolute value of the vector sum of the three-phase currents Icr, Ics, and Ict is less than 0.04 times the rated current of the cutting motor in a plurality of consecutive analysis cycles, indicating that the cutting motor itself has no fault.

[0020] The current drop condition in step S104 is that the following formula is satisfied simultaneously in multiple consecutive analysis cycles:

[0021] (1)|Icr+Ics+Ict|<0.04×Inom;

[0022] (2)

[0023] (3) △Ic / △tn<0;

[0024] Wherein, Inom is the rated current of the cutting motor, Id is the drop threshold, and n is a natural number.

[0025] The drop threshold value Id is preferably the no-load current Inlaod of the cutting motor.

[0026] In step S105, when the following formula is satisfied simultaneously in multiple consecutive analysis cycles, it is determined that a rocker arm broken shaft fault has occurred:

[0027] △Vt / △tn≥0; and Ic<Inload.

[0028] The beneficial effects of the present invention are:

[0029] The online identification method of the present invention is based on the judgment of the cutting motor current and traction speed signal of the coal mining machine. These two sensor signals are the basic monitoring signals of the coal mining machine. There is no need to add unnecessary hardware devices. Therefore, it is easy to implement and has a high recognition rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The flowchart is a method for online identification of broken shaft faults according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] like Figure 1 As shown, the present invention discloses an online identification method for a broken shaft fault of a rocker arm of a drum coal mining machine (which may be referred to as an online identification method for a broken shaft fault), comprising the following steps:

[0032] S101: Acquire the real-time three-phase currents Icr, Ics, Ict of the shearer cutting motor and the real-time traction speed Vt of the shearer;

[0033] S102: Perform clock synchronization to obtain a sampling time count tn synchronized with the three-phase currents Icr, Ics, Ict and the traction speed Vt;

[0034] S103: Calculate the real-time three-phase current effective value Ic of the cutting motor and its change rate △Ic / △tn and the change rate of the traction speed △Vt / △tn in real time and synchronously with a fixed time step △tn;

[0035] S104: judging whether the cutting motor is in a current drop state at this time according to the three-phase currents Icr, Ics, Ict and the change rate △Ic / △tn of the three-phase current effective values;

[0036] S105: When it is determined that the cutting motor is in a current drop state, further judgment is made based on the change rate of the traction speed △Vt / △tn. If non-broken shaft faults that can cause the current drop state are further excluded, it is determined that a rocker arm broken shaft fault has occurred.

[0037] Preferably, the power supply cycle of the cutting motor is used as the fixed time step Δtn. In this embodiment, the fixed time step Δtn is 20 ms.

[0038] In step S101, the real-time three-phase current Icr, Ics, and Ict of the cutting motor are obtained by a three-phase current sensor arranged on the main circuit of the cutting motor in the electric control box of the coal mining machine, and the sampling rate is preferably not less than 500 Hz. The three-phase current sensor can be a three-phase current transformer.

[0039] In step S101, the real-time traction speed Vt of the coal mining machine is obtained by a speed detection sensor arranged at the rotating shaft of the traction motor, and the sampling rate is greater than or equal to 100 Hz. The speed detection sensor can be an encoder.

[0040] In step S102, the three-phase currents Icr, Ics, Ict and the traction speed Vt are synchronously sampled into the data acquisition module through the system clock signal, and the sampling zero point is obtained through the phase-locked loop in the data acquisition module, and the first sampling zero point after the start of the acquisition is used as the counting reference zero position. The counting is performed every 20ms.

[0041] In step S104, the current drop state is determined by the following conditions: the three-phase current effective value is in a decreasing state, the current drop amplitude exceeds the drop threshold value in a plurality of consecutive analysis cycles, and the cutting motor itself has no fault. The three-phase current effective value is in a decreasing state and the current drop amplitude exceeds the drop threshold value in a plurality of consecutive analysis cycles is a manifestation of the current drop state, but the premise is that the cutting motor itself is still in a normal state at this time.

[0042] One analysis cycle is a fixed time step. In this embodiment, 50 consecutive analysis cycles are used, that is, 50×20 ms=1 s (the same below).

[0043] If the absolute value of the vector sum of the three-phase currents Icr, Ics, and Ict is greater than 0.04 times the rated current of the cutting motor in a plurality of consecutive analysis cycles, it can be determined that the cutting motor itself has a fault. If the cutting motor itself has a fault, there is no need to proceed to the next step of the judgment process.

[0044] In the online identification method of the present invention, the absolute value of the vector sum of the three-phase currents Icr, Ics, and Ict is less than 0.04 times the rated current of the cutting motor in a plurality of consecutive analysis cycles as judgment condition 1. When judgment condition 1 is met, it means that the cutting motor itself has no fault. The specific formula of judgment condition 1 is expressed as: |Icr+Ics+Ict|<0.04×Inom, where Inom is the rated current of the cutting motor.

[0045] The specific formula for the three-phase current effective value being in a decreasing state is expressed as: ΔIc / Δtn<0.

[0046] The specific formula for the current drop amplitude exceeding the drop threshold in multiple consecutive analysis cycles is expressed as: Wherein, Id is the drop threshold, and n is a natural number.

[0047] In summary, the judgment condition of the current drop state in step S104 (i.e., judgment condition 2) is that the following three formulas are satisfied simultaneously in multiple consecutive analysis cycles:

[0048] (1)|Icr+Ics+Ict|<0.04×Inom;

[0049] (2)

[0050] (3)△Ic / △tn<0.

[0051] In this embodiment, the drop threshold value Id is preferably the no-load current Inlaod of the cutting motor. Further, the no-load current Inlaod can be estimated as 0.3×Inom.

[0052] Since the causes of the current drop state include: rocker arm load mutation, traction speed reduction, rocker arm gearbox shaft breakage, and do not include the cutting motor fault state, in step S105, it is necessary to exclude non-shaft breakage faults that can cause the current drop state, that is, exclude rocker arm load mutation and traction speed reduction. The traction speed change rate △Vt / △tn is divided into four typical states: acceleration, uniform speed, deceleration and emergency stop. When △Vt / △tn≥0, the coal mining machine does not enter the deceleration and emergency stop state, that is, traction speed reduction is excluded, which is judgment condition 3.

[0053] The following formulas need to be satisfied to determine the sudden change of rocker arm load:

[0054] (1)|Icr+Ics+Ict|<0.04×Inom;

[0055] (2)

[0056] (3) △Ic / △tn<0;

[0057] (4) △Vt / △tn≥0;

[0058] (5)Ic≥Inload.

[0059] The first three formulas are judgment condition 2. Based on the above, when it is determined in step S104 that the cutting motor is in a current drop state, step S105 should be entered to further exclude traction speed reduction and rocker arm load mutation using judgment condition 3: △Vt / △tn≥0 and judgment condition 4: Ic<Inload, and then determine that a rocker arm shaft breakage fault has occurred. Judgment condition 4 indicates that the cutting motor is in an idling state.

[0060] Regarding judgment condition 4, in this embodiment, the no-load current Inlaod is estimated as 0.32×Inom, and may also be estimated as other multiples of the rated current, such as 0.32×Inom.

[0061] The present invention utilizes the phenomenon that when a broken shaft fault occurs in the cutting transmission system of the rocker arm of the drum coal mining machine, the current of the cutting motor will show regular mutations, and a joint analysis is performed based on the current mutation state and the traction state of the coal mining machine. Not only can it be more accurately determined whether a broken shaft fault has occurred at this time, with a high recognition rate, but also because the two sensor signals of current and traction speed are basic monitoring signals of the coal mining machine and can be obtained without adding any unnecessary devices, it is more convenient to implement and does not increase hardware costs.

Claims

1. An online identification method for a broken shaft fault of a rocker arm of a drum coal mining machine, characterized in that: The steps include: S101: Acquire the real-time three-phase currents Icr, Ics, Ict of the shearer cutting motor and the real-time traction speed Vt of the shearer; S102: Perform clock synchronization to obtain a sampling time count tn synchronized with the three-phase currents Icr, Ics, Ict and the traction speed Vt; S103: Calculate the real-time three-phase current effective value Ic of the cutting motor and its change rate △Ic / △tn and the change rate of the traction speed △Vt / △tn in real time and synchronously with a fixed time step △tn; S104: judging whether the cutting motor is in a current drop state at this time according to the three-phase currents Icr, Ics, Ict and the change rate △Ic / △tn of the three-phase current effective values; S105: When it is determined that the cutting motor is in a current drop state, combined with the change rate of the traction speed △Vt / △tn, if non-broken shaft faults that can cause the current drop state are further excluded, it is determined that a rocker arm broken shaft fault has occurred.

2. The online identification method for broken shaft fault of rocker arm of drum coal mining machine according to claim 1, characterized in that: The power supply period of the cutting motor is used as the fixed time step Δtn.

3. The online identification method for broken shaft fault of rocker arm of drum coal mining machine according to claim 2, characterized in that: In the step S101, the real-time three-phase currents Icr, Ics and Ict of the cutting motor are obtained by a three-phase current sensor arranged on the main circuit of the cutting motor, and the sampling rate is not less than 500 Hz.

4. The online identification method for broken shaft fault of rocker arm of drum coal mining machine according to claim 3, characterized in that: In the step S101, the real-time traction speed Vt of the coal mining machine is obtained by a speed detection sensor arranged at the rotating shaft of the traction motor, and the sampling rate is greater than or equal to 100 Hz.

5. The online identification method for broken shaft fault of rocker arm of drum coal mining machine according to claim 1, 2, 3 or 4, characterized in that: In step S102, the two sets of data, the three-phase currents Icr, Ics, Ict and the traction speed Vt, are synchronously sampled into the data acquisition module through the system clock signal, and the sampling zero point is obtained through the phase-locked loop in the data acquisition module, and the first sampling zero point after the start of acquisition is used as the counting reference zero position.

6. The online identification method for broken shaft fault of rocker arm of drum coal mining machine according to claim 1, 2, 3, 4 or 5, characterized in that: In step S104, the current drop state is determined by the following conditions: the effective value of the three-phase current is in a decreasing state, the current drop amplitude exceeds the drop threshold value in a plurality of consecutive analysis cycles, and the cutting motor itself has no fault.

7. The online identification method for broken shaft fault of rocker arm of drum coal mining machine according to claim 6, characterized in that: The absolute value of the vector sum of the three-phase currents Icr, Ics, and Ict is less than 0.04 times the rated current of the cutting motor in a plurality of consecutive analysis cycles, indicating that the cutting motor itself has no fault.

8. The online identification method for broken shaft fault of rocker arm of drum coal mining machine according to claim 7, characterized in that: The current drop condition in step S104 is that the following formula is satisfied at the same time within a plurality of consecutive analysis cycles: (1)|Icr+Ics+Ict|<0.04×Inom; (2) (3) △Ic / △tn<0; Wherein, Inom is the rated current of the cutting motor, Id is the drop threshold, and n is a natural number.

9. The online identification method for broken shaft fault of rocker arm of drum coal mining machine according to claim 8, characterized in that: The drop threshold value Id is the no-load current Inlaod of the cutting motor.

10. The online identification method for broken shaft fault of rocker arm of drum coal mining machine according to claim 8 or 9, characterized in that: In step S105, when the following formula is satisfied simultaneously in multiple consecutive analysis cycles, it is determined that a rocker arm broken shaft fault has occurred: △Vt / △tn≥0; and Ic<Inload.

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