Hierarchical control method and device for steel wire rope of crane holding bucket

Abstract

The invention relates to the field of holding bucket safety control, provides a crane holding bucket steel wire rope layered control method and device, and aims to improve the use safety of a crane holding bucket. Based on real-time monitoring data, through a multi-stage control scheme, when overload does not reach a national standard risk value, a flexible control scheme is mainly used, and through a buffer speed reduction means, the safety of the crane holding bucket is improved. The working continuity of the holding bucket is ensured, and the production efficiency is improved; and meanwhile, for the wire breakage risk after overload or long-term abrasion of the steel wire, risk prevention is achieved through wire breakage early warning, the person and machine injury risk caused by falling of the holding bucket due to rope breakage is reduced, and the equipment failure rate is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of safety control of a grab bucket, and particularly relates to a method and device for layered control of a steel wire rope of a grab bucket. BACKGROUND

[0002] A grab bucket of a travelling crane is generally composed of a steel wire rope, a pulley block and a mechanical opening and closing mechanism, and the opening and closing of the grab bucket is realized by upward pulling or downward loosening of the closed steel wire rope, so as to grab materials, and the grab bucket is lifted by lifting the steel wire rope after the materials are grabbed.

[0003] The grab bucket of the travelling crane has a simple structure, and cannot detect whether the whole is overloaded, the opening and closing size, the force of the steel wire rope and the like, and all rely on the self-consciousness and operation standardization of the operator of the grab bucket in the use process. Therefore, in the actual use process, the grab bucket of the travelling crane often becomes the equipment with the highest failure rate in the production unit of the travelling crane, mainly reflected in that the lifting steel wire rope is broken due to overall overload, resulting in falling of the grab bucket, damage of the guide rope device, deformation of the pulley block and the like, and also in that the workers do not realize that the closed steel wire rope of the grab bucket is partially broken or broken due to corrosion of the steel wire rope, difficulty in manual inspection and the like, resulting in breakage of the steel wire rope during the closing of the grab bucket, which greatly reduces the safety and use continuity of the grab bucket of the travelling crane. SUMMARY

[0004] In order to improve the safety of the use of the grab bucket of the travelling crane, the present application provides a method and device for layered control of a steel wire rope of a grab bucket.

[0005] The technical solution adopted by the present application to solve the above problems is as follows:

[0006] The method for layered control of the steel wire rope of the grab bucket comprises the following steps:

[0007] Step 1: presetting control evaluation parameters in a control unit, including a grab bucket type and a corresponding rated load G_rated, an angle-force arm mapping relationship, a broken wire critical value and a broken wire threshold value, the broken wire critical value being less than the broken wire threshold value;

[0008] Step 2: collecting real-time monitoring parameters, including a lifting steel wire rope tension Ft, a closed steel wire rope tension Fc and a jaw plate angle θ;

[0009] Step 3: determining a real-time force arm coefficient η(θ) according to the angle-force arm mapping relationship by querying the jaw plate angle θ; and calculating a calibrated load G(t) according to the formula G(t) = Ft / η(θ);

[0010] Step 4: layered control: if the calibrated load G(t) is greater than A times the rated load G_rated, then overload buffer control is performed;

[0011] If the calibration load G(t) is less than A times the rated load G_rated, it is determined whether the closed steel wire rope tension change ΔFc in Δt time reaches the wire breaking threshold value, if yes, the wire breaking early warning control is performed; if no, the device is in normal operation;

[0012] If the wire breaking early warning control is performed, and ΔFc continues to increase and exceeds the wire breaking threshold value, the emergency stop and fault locking are executed.

[0013] Further, A is 1.1.

[0014] Further, the overload buffer control is specifically: slowing down the closing speed of the closed steel wire rope and issuing an overload reminder; if the calibration load G(t) falls back to the safe range within the preset time, the speed of the grab bucket is restored; otherwise, the device is stopped.

[0015] Further, the overload reminder is an audible and visual alarm and / or information notification.

[0016] Further, Δt is 10-50 ms.

[0017] Further, the wire breaking threshold value and the wire breaking threshold value are set according to the percentage of the rated tension of the closed steel wire rope.

[0018] Further, the wire breaking early warning control is specifically: performing an audible and visual alarm, if the duration of the audible and visual alarm exceeds the preset sustainable duration, the grab bucket is controlled to perform the unloading action: opening B time; if after unloading, ΔFc falls below the wire breaking threshold value, the normal operation of the grab bucket is restored.

[0019] Further, it also includes optimizing the angle-force arm mapping relationship, the wire breaking threshold value and the wire breaking threshold value according to the grab bucket operation situation.

[0020] The device for controlling the steel wire rope of the grab bucket of the traveling crane is used to realize the method for controlling the steel wire rope of the grab bucket of the traveling crane, comprising: a hoisting steel wire rope, a closed steel wire rope, a grab bucket jaw plate, an actuator and a control unit, further comprising: a hoisting steel wire rope tension sensor for detecting the tension of the hoisting steel wire rope, a closed steel wire rope tension sensor for detecting the tension of the closed steel wire rope, and a jaw plate angle encoder for detecting the opening and closing angle of the grab bucket jaw plate; the hoisting steel wire rope tension sensor, the closed steel wire rope tension sensor, the jaw plate angle encoder and the actuator are connected with the control unit.

[0021] Further, the hoisting steel wire rope tension sensor is arranged in the groove of the hoisting steel wire rope terminal, the closed steel wire rope tension sensor is arranged in the groove of the closed steel wire rope terminal, and the jaw plate angle encoder is arranged at the center of the grab bucket jaw plate shaft.

[0022] The present application has the beneficial effects compared with the prior art: based on real-time monitoring data, through the multi-level control scheme, when the overload does not reach the national standard risk value, mainly using the flexible control scheme, through the means of buffer speed reduction, ensuring the continuity of the grab bucket work, improving the production efficiency; at the same time, for the risk of wire breakage after overload or long-term wear of steel wire, through the wire breakage early warning, the risk prevention is realized, the risk of injury and machine caused by the falling of the grab bucket due to the rope breakage is reduced, and the equipment failure rate is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The figure is a flow chart of the hierarchical control method for the hoist grab steel wire rope.

[0024] Figure 2 The figure is a structural schematic diagram of the hierarchical control device for the hoist grab steel wire rope.

[0025] The figure is a structural schematic diagram of the hierarchical control device for the hoist grab steel wire rope. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0027] As shown in the figure, the hierarchical control method for the hoist grab steel wire rope comprises: Figure 1

[0028] Step 1: presetting control evaluation parameters in the control unit, including the grab bucket type and the corresponding rated load G_rated, the angle-force arm mapping relationship, the wire breakage critical value and the wire breakage threshold value, the wire breakage critical value being less than the wire breakage threshold value.

[0029] In this embodiment, the wire breakage critical value and the wire breakage threshold value are both set according to the percentage of the closed steel wire rated tension Fc_rated, and the control evaluation parameter table is shown in Table 1:

[0030] Table 1 Control evaluation parameter table

[0031]

[0032] The design principle of the angle-force arm mapping relationship is to cover the full opening (10°) to the full closing (90°) interval, and at least provide 4 discrete points; the control unit automatically linearly interpolates the intermediate angle coefficient. The wire breakage threshold value is lower than 20% of the safety limit value of GB / T 5972-2016, so as to reserve greater safety redundancy.

[0033] ​Step 2: Collect real-time monitoring parameters, including lifting wire rope tension Ft, closing wire rope tension Fc and jaw angle θ.

[0034] Step 3: Query the angle-force arm mapping relationship according to the jaw angle θ to determine the real-time force arm coefficient η(θ); calculate the calibration load G(t) according to the formula G(t) = Ft / η(θ).

[0035] Step 4: Hierarchical control:

[0036] If the calibration load G(t) > A times the rated load G_rated, overload buffering control is performed; in this embodiment, A is 1.1, and the overload buffering control specifically includes: slowing down the closing speed of the closing wire rope and issuing an overload warning, the closing speed can be slowed down by a pre-set overload speed reduction ratio to improve safety and stability; the overload warning uses audible and visual alarms and / or sends an alarm message; if the calibration load G(t) falls back to the safe range within the pre-set time, the bucket running speed is restored; otherwise, the equipment is shut down.

[0037] If the calibration load G(t) ≤ A times the rated load G_rated, it is determined whether the closing wire rope tension change ΔFc reaches a critical value within Δt time, if yes, wire breakage early warning control is performed; if not, the equipment operates normally.

[0038] ΔFc = |Fc(t) - Fc(t-Δt)|, where t is the current time and Δt is the sampling interval, generally 10-50 ms. The wire breakage early warning control specifically refers to: audible and visual alarms, if the duration of the audible and visual alarms exceeds the pre-set sustainable time, the bucket performs the unloading action: opening B time; if after unloading, ΔFc falls below the critical value, the bucket resumes normal operation. The pre-set sustainable time is generally set to 3-5 seconds or a few ΔFc detection periods to avoid false alarms; B time is set to 5-10 seconds.

[0039] If ΔFc continues to increase and exceeds the wire breakage threshold after the wire breakage early warning control is performed, emergency shutdown and fault locking are performed.

[0040] The application controls layer by layer based on multi-layer response logic through real-time data monitoring. The first layer: if it is determined to be overloaded, the closing speed of the grab bucket is reduced to realize closing buffer, ensure sufficient time for reasonable unloading, and prevent forced closing from affecting or damaging the equipment. The second layer: if the rated load is exceeded but the overload risk warning is not reached, it is determined whether the closing steel wire rope has a broken wire risk. If it does, an alarm unloading is performed to ensure that the risk is discovered in advance and prevented. If the second layer risk warning and remedial measures are still deteriorating after execution, the third layer response is entered. The third layer response: if the third layer response is entered, it is determined that the closing steel wire rope has a broken risk, and the machine is stopped and automatically repaired. The three-layer reasonable response can be corrected layer by layer, effectively avoiding the one-size-fits-all phenomenon of existing overload shutdown, solving the industry pain point of traditional grab bucket overload shutdown, and improving the operation efficiency.

[0041] Further, in order to improve the accuracy of control, the application also sets an optimization process to optimize the angle-force arm mapping relationship, the broken wire critical value and the broken wire threshold value according to the grab bucket operation condition:

[0042] The time sequence data of the grab bucket operation is collected and stored, including: the time sequence of the jaw opening angle θ; the real-time data of the lifting rope tension Ft and the closing rope tension Fc; the finally calculated dynamic load G(t); the material type finally selected by the operator; whether an alarm or control event (such as overload warning, broken wire alarm, etc.) is triggered.

[0043] Optimization of angle-force arm mapping relationship (θ→η): the system periodically (such as every 100 hours of work) or when manually triggered by the operator, analyzes the historical data of a specific material type to obtain angle-force arm coefficients η(θ) that are more suitable for the actual working conditions of the machine, to supplement or replace the initial parameter table (Table 1). The optimization goal is to make the calculated value of the dynamic calibration load G(t) closer to the actual load G_actual under this working condition. For example, for a "5t grain grab bucket", the initial mapping is 45°→1.25, but after adaptive learning, it is found that the actual coefficient of this device at 45° is 1.28, and the system will automatically update this value, thereby improving the calculation accuracy of the dynamic load G(t).

[0044] In order to obtain the reference data (i.e. G_actual) required for optimization, the system can use one or more of the following methods:

[0045] 1. Static calibration mode: During equipment maintenance or idle period, the operator can initiate the calibration procedure. The system guides the operator to place the grab bucket on a known weight standard weight or static scale, hold it still at multiple preset angles (θ) and record the lifting rope tension Ft at that moment. At this moment, the actual load G_actual is known and accurate, according to the formula η(θ) = Ft / G_actual, the actual force arm coefficient at this angle can be directly calculated, which is used to correct or replace the preset mapping value.

[0046] 2. Dynamic data filtering and fitting: In normal operation, the system automatically filters those operation cycle data that do not trigger any alarm (i.e. stable load, no risk of wire breakage) and smooth operation. In these "golden data" segments, it can be reasonably assumed that the calculated G(t) is relatively accurate and reliable. The system collects a large number of corresponding Ft and G(t) (regarded as approximate G_actual) at different angles θ, and through linear regression or curve fitting algorithm, it reversely deduces the η(θ) relationship curve that is more in line with the long-term average working condition of the machine.

[0047] 3. Auxiliary verification based on closed rope tension Fc (optional advanced logic): For some specific types of grab buckets and materials, under the ideal model, the closed rope tension Fc also has a theoretical relationship with the material load and angle. The system can jointly analyze the stable data of Ft, Fc, θ, and through more complex mechanical models (such as establishing a system of equations containing friction and material characteristics), it can further improve the accuracy of η(θ).

[0048] Optimization of wire breakage critical value and threshold: The system records each "wire breakage warning" event and its subsequent development. If the system repeatedly warns that the wire has not been seriously broken after inspection (i.e. false alarm), the adaptive learning module will appropriately increase the wire breakage critical value and / or the wire breakage threshold under this working condition to reduce false alarms and improve operation continuity; on the contrary, if a wire breakage accident occurs but the system does not give an early warning (i.e. missed alarm), the module will analyze the tension sudden change data before the accident and accordingly reduce the wire breakage critical value and / or the wire breakage threshold, making it more sensitive to similar minor changes in the future.

[0049] Through the optimization process, the system can automatically calibrate the angle-force arm relationship and warning threshold based on actual use data, making overload and wire breakage judgments more and more accurate over time, effectively solving the control failure problem caused by equipment manufacturing errors, long-term wear and tear, and changes in material characteristics. Even the same type of grab bucket, when handling different fermented grains in different workshops, its mechanical properties and personnel's operation of the equipment also differ. Through the optimization process, it can tailor the control parameters to each device to realize the upgrade from generalization to individualization and solve the lack of adaptability in complex real working conditions.

[0050] Correspondingly, as shown in Figure 2 The present application also provides a hoist rope layering control device for implementing the hoist rope layering control method, which comprises a lifting rope, a closing rope, a grab jaw plate, an actuator, a control unit, a lifting rope tension sensor 1 for detecting the tension of the lifting rope, a closing rope tension sensor 2 for detecting the tension of the closing rope, and a jaw plate angle encoder 3 for detecting the opening and closing angle of the grab jaw plate. The lifting rope tension sensor 1, the closing rope tension sensor 2, the jaw plate angle encoder 3, and the actuator are all connected to the control unit 4. The lifting rope tension sensor / closing rope tension sensor is fixed in the groove of the lifting rope end connector / closing rope end connector or the wire rope fixing pin by a buckle structure. This embodiment adopts fixed installation, which can effectively resist vibration interference during wire rope movement. The jaw plate angle encoder is installed at the center of the grab jaw plate shaft by high-strength magnetic attraction or embedded structure, and is not in contact with the outside world, so that it can achieve a protection level of IP67 and be suitable for various complex working conditions.

[0051] Further, an operation control panel 5 is also included, which is provided with a grab selection unit for allowing the operator to select the current grab type, and the control unit calls the corresponding control evaluation parameters according to the selected grab.

[0052] Taking the white spirit brewing scene as an example for verification:

[0053] Implementation of the experimental group:

[0054] (1) In the white spirit brewing workshop (high temperature, high humidity, and much water vapor), a working hoist is selected, the lifting rope tension sensor and the closing rope tension sensor are installed in the rope end connector groove of the wire rope, the jaw plate angle encoder is self-fixed and installed by magnetic attraction and embedded in the center of the grab jaw plate shaft, and the shaft ends are sealed.

[0055] (2) According to the material characteristics, the grab is selected as a "5t grain grab", and the system automatically loads the corresponding preset control evaluation parameters in the display screen.

[0056] (3) Overload control verification: 5.5t highland barley material is loaded on the static weighing scale in the workshop, placed under the hoist grab, and the hoist grab operator performs highland barley grabbing. When 5.5t is grabbed, the system overloads and the yellow light flashes, the running speed of the grab closing motor is reduced by 30%, 0.07m / s (original speed 0.1m / s), and all 10 tests are accurate.

[0057] (4) Perform the wire breaking control verification: after the above actions are continued, unload to the non-overload state, the yellow light flashes and stops, the worker operates the grab in the non-closed state, and the grab is suspended and stationary above the ground. A technician artificially releases the tension of the closed steel wire rope by 5% (according to the test data of the tension sensor on the closed rope). At this time, the sound and light alarm starts, and after 10 seconds, the unloading actuator of the grab starts to act (that is, the grab is opened), and the material is released. Artificially continuously release the closed rope tension to 10%, and all the actuators of the grab are powered off and emergency stopped.

[0058] (5) Continue the above experiments and production, and find that no overload false alarm shutdown occurs, the overload response time reaches the 200 ms level, the simulation of the mathematical tool has an accuracy of 100%, and the precise prediction of wire breaking can be basically achieved.

[0059] The implementation situation of the control group 1 is as follows:

[0060] (1) In the control test group, the lifting rope tension sensor and the closed rope tension sensor are directly bound and installed near the rope end joint groove of the steel wire rope, the jaw plate angle encoder is embedded in the jaw plate of the grab through magnetic adsorption self-fixing installation, and the shaft is sealed at both ends.

[0061] (2) The second step operation is the same as that of the above experimental group.

[0062] (3) Perform the overload control verification. 5.5t of sorghum material is loaded on the workshop static weighing scale, and is placed below the grab of the crab. The sorghum is grabbed by the grab operator of the crab. When 5.5t of sorghum is grabbed for the first time, the system overload warning yellow light does not flash, and the running speed of the grab closing motor is not reduced by 30%, 0.07m / s (original speed 0.1m / s). A total of 10 control experiments are performed, of which 4 times alarm in time, 3 times alarm when the material is increased to about 5.53t, and 3 times alarm when the material is increased to about 5.53t.

[0063] (4) Perform the wire breaking control verification: after the above actions are continued, unload to the non-overload state, the yellow light flashes and stops, the worker operates the grab in the non-closed state, and the grab is suspended and stationary above the ground. A technician artificially releases the tension of the closed steel wire rope by 5% (according to the test data of the tension sensor on the closed rope). At this time, the sound and light alarm starts, and after 10 seconds, the unloading actuator of the grab starts to act (that is, the grab is opened), and the material is released. Artificially continuously release the closed rope tension to 10%, and all the actuators of the grab are powered off and emergency stopped.

[0064] (5) Finally, the system accuracy decreased significantly due to the tension sensor being tied to the wire rope, which could also achieve alarm prediction, but the accuracy rate decreased by about 40%.

[0065] Implementation of control group 2:

[0066] In the white wine brewing workshop, a working crane was selected, and the lifting rope tension sensor and the closing rope tension sensor were installed in the rope end joint groove position of the steel wire rope. The jaw plate angle encoder was fixed and installed on the outside of the grab jaw plate shaft by magnetic adsorption. All other conditions remained unchanged.

[0067] All subsequent operations were consistent, but due to the angle encoder being exposed to the outside, it was affected by high temperature, humidity, and water vapor, resulting in 3 cases of not transmitting signals in time, misreading angles, and other situations. The accuracy rate decreased by more than 30%.

[0068] Implementation of control group 3:

[0069] After long-term simulation and test operation, the system adaptive learning module found that when the grab bucket grabs "wine lees", the actual closing force required in the angle range of 60° to 75° is about 8% higher than the preset parameter table. The module automatically generated an optimized force arm coefficient for "wine lees" (correcting the coefficient at 75° from 2.20 to 2.38). Thereafter, the accuracy of calculating dynamic load G(t) under this working condition was significantly improved, effectively avoiding the false overload alarm caused by calculation deviation, and improving the operation efficiency.

Claims

1. A method for layered control of wire rope in a crane bucket, characterized in that, include: Step 1: Preset control evaluation parameters in the control unit, including bucket type and its corresponding rated load G_rated, angle-lever mapping relationship, wire breakage critical value and wire breakage threshold, where the wire breakage critical value is less than the wire breakage threshold; Step 2: Collect real-time monitoring parameters, including lifting wire rope tension Ft, closing wire rope tension Fc, and jaw plate angle θ; Step 3: Determine the real-time lever arm coefficient η(θ) by querying the angle-lever mapping relationship based on the jaw plate angle θ; calculate the calibration load G(t) according to the formula G(t) = Ft / η(θ); Step 4: Layered control: If the calibration load G(t) > A times the rated load G_rated, then overload buffer control is performed; If the calibration load G(t) ≤ A times the rated load G_rated, then determine whether the change in tension ΔFc of the closed wire rope within the time interval Δt reaches the critical value for wire breakage. If yes, then wire breakage early warning control is performed; otherwise, the equipment operates normally. If ΔFc continues to increase and exceeds the wire breakage threshold after wire breakage warning control is implemented, an emergency shutdown and fault lockout will be executed.

2. The method for layered control of the wire rope in the overhead crane bucket according to claim 1, characterized in that, A is set to 1.

1.

3. The method for layered control of the wire rope in the crane bucket according to claim 1, characterized in that, The overload buffer control is as follows: reduce the closing speed of the closing wire rope and issue an overload warning; if the calibration load G(t) falls back to the safe range within the preset time, the bucket running speed is restored; otherwise, the control equipment is stopped.

4. The method for layered control of the wire rope in the crane bucket according to claim 3, characterized in that, Overload alerts include audible and visual alarms and / or information notifications.

5. The method for layered control of the wire rope in the overhead crane bucket according to claim 1, characterized in that, Δt is taken as 10-50ms.

6. The method for layered control of the wire rope in the crane bucket according to claim 1, characterized in that, The critical value and threshold for wire breakage are set according to the percentage of the rated tension of the closed wire rope.

7. The method for layered control of the wire rope in the crane bucket according to claim 1, characterized in that, The wire breakage early warning control is as follows: an audible and visual alarm is triggered. If the duration of the audible and visual alarm exceeds the preset duration, the bucket is controlled to perform an unloading action: opening for time B. If, after unloading, ΔFc falls back below the wire breakage threshold, the bucket returns to normal operation.

8. The method for layered control of the wire rope in the crane bucket according to claim 1, characterized in that, It also includes optimizing the angle-lever mapping relationship, wire breakage critical value, and wire breakage threshold based on the bucket operation situation.

9. A crane bucket wire rope layering control device, used to implement the crane bucket wire rope layering control method according to any one of claims 1-8, comprising: The lifting wire rope, closing wire rope, jaw plate of the bucket, actuator, and control unit are characterized in that they further include: a lifting wire rope tension sensor for detecting the tension of the lifting wire rope, a closing wire rope tension sensor for detecting the tension of the closing wire rope, and a jaw plate angle encoder for detecting the opening and closing angle of the jaw plate of the bucket; the lifting wire rope tension sensor, the closing wire rope tension sensor, the jaw plate angle encoder, and the actuator are all connected to the control unit.

10. The crane bucket wire rope layering control device according to claim 9, characterized in that, The lifting wire rope tension sensor is installed in the groove of the lifting wire rope end joint, the closing wire rope tension sensor is installed in the groove of the closing wire rope end joint, and the jaw plate angle encoder is installed at the center of the jaw plate hinge shaft of the bucket.

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