Control system and method for grabbing amount of gantry crane grab bucket

Abstract

The invention discloses a grab amount control system for a gantry crane grab bucket and a corresponding control method thereof. The system comprises a support mechanism position sensor, an opening and closing mechanism position sensor, a support mechanism speed encoder, an opening and closing mechanism speed encoder, a PLC controller and an operation panel, and the operation panel is provided with a display screen, a material selection knob, a deep digging adjustment knob, a deep digging start button and an automatic grab start button; the gantry crane grab bucket control method is implemented based on the gantry crane grab amount control system; the gantry crane grab bucket grab amount control system and the corresponding control method thereof can effectively improve the operation efficiency of loading and unloading goods with a relatively high specific gravity, and at the same time, also avoid damage to the gantry crane itself due to overload, and ensure the safety of man and machine; at the same time, the system is simple to operate, reduces the requirements on the operation level of the gantry crane driver, reduces the driver's labor intensity, and objectively reduces the risk of accidents.

Description

Technical Field

[0001] The invention relates to the field of dock loading and unloading operations, and in particular to a gantry crane grab bucket grab amount control system and a control method thereof. Background Art

[0002] At present, the rated lifting capacity of the gantry crane commonly used in dock unloading operations is 40t. The specific gravity of the cargo to be unloaded is of various types, basically between 1.9-2.8. However, it is not only costly to reserve grabs of different sizes to adapt to materials with different specific gravities, but also time-consuming and labor-intensive to replace grabs. Therefore, currently, light grabs with large bucket capacity and grabs with small bucket capacity are commonly used at loading and unloading sites, but grabs of different capacities show obvious differences in production efficiency in loading and unloading cargoes of different specific gravities.

[0003] Generally speaking, the loading and unloading efficiency of goods with a lower specific gravity is relatively high. This is because when loading and unloading goods with a lower specific gravity, a light grab with a large bucket capacity is usually selected; when grabbing goods, the weight of the full bucket is basically below 40t, and the technical requirements for the gantry crane driver are relatively low; the operating efficiency of drivers with relatively high operating levels and drivers with relatively low operating levels is not much different; when loading and unloading goods with a higher specific gravity, using a grab with a small bucket capacity will result in the weight not reaching 40t even if the grab is full of goods, wasting the operating capacity of the gantry crane; and when using a grab with a large bucket capacity, the total weight of the grab when fully loaded will exceed the maximum operating load of the gantry crane, causing overloading, causing the gantry crane driver to have to reopen the grab, causing some of the goods to leak out, and then re-close the bucket. This process of reopening and closing the bucket wastes time and reduces operating efficiency. However, a gantry crane driver with a high level of operating skills can manually control the grabbing amount of the grab bucket according to the degree of closure of the grab bucket during the grabbing process and the weight display in the driver's cab, so that the grabbing amount is basically maintained at 40t, avoiding the process of re-opening and closing the bucket and ensuring operating efficiency. It can be seen that the loading and unloading of goods with a higher proportion of gravity requires higher operating skills of the gantry crane driver, and the operating efficiency of drivers with relatively high operating skills is higher than that of drivers with relatively low operating skills. However, gantry crane drivers with high operating skills are a minority after all, and it is impossible for every driver to reach a very high level.

[0004] In summary, in order to improve the operating efficiency when loading and unloading goods with a higher specific gravity, it is necessary to start from the control of the grab bucket and develop a device that can be used in conjunction with the grab bucket operation and effectively improve the operating efficiency of loading and unloading goods with a higher specific gravity. Summary of the invention

[0005] The object of the present invention is to provide a gantry crane grab bucket grab amount control system for improving the operation efficiency of loading and unloading goods with a relatively high specific gravity.

[0006] Another object of the present invention is to implement a control method based on the above-mentioned gantry crane grab bucket grab amount control system.

[0007] To this end, the technical solution of the present invention is as follows:

[0008] A gantry crane grab bucket grab amount control system, comprising:

[0009] a) a support mechanism position sensor, which is installed on the rotating mechanism of the hoist of the support mechanism to collect the rotation position signal of the motor drive shaft of the hoist of the support mechanism;

[0010] b) an opening and closing mechanism position sensor, which is installed on the rotating mechanism of the hoist of the opening and closing mechanism to collect the rotation position signal of the motor drive shaft of the hoist of the opening and closing mechanism;

[0011] c) a supporting mechanism speed encoder, which is installed on the motor drive shaft of the hoist of the supporting mechanism to collect a speed signal of the motor drive shaft of the hoist of the supporting mechanism;

[0012] d) The speed encoder of the opening and closing mechanism is installed on the motor drive shaft of the hoist of the opening and closing mechanism to detect the speed signal of the motor drive shaft of the hoist of the opening and closing mechanism;

[0013] e) A PLC controller, which is arranged in a control box installed on the side of the linkage platform in the cab of the gantry crane; the PLC controller is electrically connected to the support mechanism position sensor and the opening and closing mechanism displacement sensor respectively, and the PLC controller is electrically connected to the support mechanism speed encoder and the opening and closing mechanism speed encoder respectively; the PLC controller is electrically connected to the hoist motor of the support mechanism through the frequency converter A respectively, the PLC controller is electrically connected to the hoist motor of the opening and closing mechanism through the frequency converter B, and the PLC controller is electrically connected to the overload system installed in the grab bucket itself; and

[0014] f) An operation panel is arranged on the upper surface of the control box; the operation panel is provided with a display screen electrically connected to the PLC controller, a material selection knob electrically connected to the PLC controller via a digital quantity input module, a deep digging adjustment knob connected to the PLC controller via an analog quantity input module, a deep digging start button electrically connected to the PLC controller, and an automatic grab start button electrically connected to the PLC controller; the deep digging adjustment knob adopts a stepless knob.

[0015] Furthermore, the supporting mechanism position sensor and the opening and closing mechanism position sensor may be selected to be Hall sensors, which are mounted on the motor rotor assembly.

[0016] Furthermore, an upper display frame and a lower display frame are provided on the display screen; the upper display frame is used to display the value corresponding to the current gear position of the material selection knob; and the lower display frame is used to display the value corresponding to the current position of the deep digging adjustment knob.

[0017] A gantry crane grab bucket control method based on the above gantry crane grab bucket grab amount control system, the steps are as follows:

[0018] 1. Determine the appropriate opening angle of the grab bucket corresponding to the material to be grabbed:

[0019] Step 1: Turn the material selection knob to the gear that matches the material, and start the deep digging start button; the deep digging start button sends a grab signal to the PLC controller, and the PLC controller controls the hoist motor drive shaft of the support mechanism to continue to rotate forward until the PLC controller collects the grab bucket weight value transmitted by the overload system as 0; at the same time, the material selection knob inputs a specified signal to the PLC controller, and the PLC controller controls the hoist motor drive shaft of the opening and closing mechanism to rotate forward for a specified number of turns according to the specified signal, and then releases the opening and closing wire rope to a specified length, so that the grab bucket opens to a specified opening angle;

[0020] Step 2: The grab grabs the material at the specified opening angle and lifts it away from the material surface. According to the grab weight value displayed in real time by the overload system, it is determined whether this grab has reached the maximum operating capacity of the gantry crane;

[0021] Step 3: If the grab weight value in step 2 does not reach or exceed the maximum operating capacity of the gantry crane, the number of rotations of the winch motor drive shaft of the opening and closing mechanism is adjusted by adjusting the deep digging adjustment knob to fine-tune the specified opening angle of the grab; the deep digging start button is started again, and the deep digging start button sends a grab signal to the PLC controller, and the PLC controller controls the winch motor drive shaft of the support mechanism to continue to rotate forward until the PLC controller collects the grab weight value transmitted by the overload system as 0; at the same time, the deep digging adjustment knob inputs a specified signal to the PLC controller, and the PLC controller controls the winch motor drive shaft of the opening and closing mechanism to rotate forward for a specified number of times according to the specified signal, and then releases the opening and closing wire rope to a specified length, so that the grab is opened to the new specified opening angle;

[0022] Repeat steps 2 and 3 until the specified opening angle of the grab bucket satisfies the material grabbing capacity and reaches the maximum operating capacity of the gantry crane; the corresponding value of the deep digging adjustment knob is the optimal adjustment value;

[0023] (II) Based on the opening angle determined in step (I), complete all material grabbing by automatic grabbing:

[0024] Keep the deep digging adjustment knob at the optimal adjustment value and start the automatic grab start button; the automatic grab start button inputs the automatic grab operation signal to the PLC controller;

[0025] The PLC controller controls the hoist motor drive shaft of the support mechanism to continuously rotate forward. At the same time, the deep digging adjustment knob inputs a specified signal to the PLC controller. The PLC controller controls the hoist motor drive shaft of the opening and closing mechanism to rotate forward for a specified number of turns, and then releases the opening and closing wire rope to a specified length. The grab opens to a specified opening angle during the descent process.

[0026] When the PLC controller obtains the weight value of the grab bucket detected by the overload system as 0, the PLC controller controls the motor drive shaft of the hoist of the opening and closing mechanism to rotate in the opposite direction for a specified number of turns, thereby lifting and tightening the opening and closing wire rope to a specified length, closing the grab bucket, and completing the material grabbing;

[0027] When the PLC controller collects the speed input from the speed encoder of the opening and closing mechanism as 0, the PLC controller controls the driving shaft of the hoisting motor of the supporting mechanism to rotate continuously in the opposite direction to lift and tighten the supporting wire rope. When the value difference transmitted by the displacement sensor of the opening and closing mechanism and the displacement sensor of the supporting mechanism is 0, it means that the rope difference between the two opening and closing wire ropes and the two supporting wire ropes is 0, and the grab bucket has left the material surface at this time, and the grabbing action is completed. At this time, the bucket can be controlled to transfer to the target position for unloading;

[0028] During the process of the above steps (a) and (b), the PLC controller calculates whether the rope difference between the supporting wire rope and the opening and closing wire rope exceeds the set threshold value based on the position signals input by the supporting mechanism position sensor and the opening and closing mechanism position sensor, so as to determine whether there is a loose wire rope state; when the PLC controller calculates that the rope difference exceeds the set threshold value, it controls the speed of the motor drive shaft of the supporting mechanism winch or the speed of the motor drive shaft of the opening and closing mechanism winch according to the current movement speeds of the supporting wire rope and the opening and closing mechanism speed encoder collected by the supporting mechanism speed encoder and the opening and closing mechanism speed encoder.

[0029] Compared with the existing technology, the gantry crane grab bucket grab volume control system and its corresponding control method can effectively improve the operating efficiency of loading and unloading goods with a higher specific gravity, while also avoiding damage to the gantry crane itself due to overload, ensuring the safety of people and machines; at the same time, the system is simple to operate, reduces the requirements for the operating level of the gantry crane driver, reduces the driver's labor intensity, and objectively reduces the risk of accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of the gantry crane grab bucket grab amount control system of the present invention;

[0031] Figure 2 It is a front view of the operating panel of the gantry crane grab bucket grab amount control system of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the following embodiments are by no means intended to limit the present invention in any way.

[0033] The grab amount control system of the gantry crane grab bucket of the present embodiment is suitable for the four-rope grab bucket; specifically, the four-rope grab bucket mainly includes four parts: an upper crossbeam, a pull rod, a lower crossbeam and a bucket part. It is used in conjunction with a bridge crane to realize grabbing various types of bulk cargo and to carry out operations such as loading, unloading and stacking. The crane lifting system is equipped with a front winch mechanism and a rear winch mechanism. The front winch mechanism is referred to as an opening and closing mechanism, and the rear winch mechanism is referred to as a supporting mechanism. Among them, the rear winch mechanism is composed of a winch motor and a set of wire rope drum systems, one end of the two supporting wire ropes is led out from the wire rope drum, and the other end is symmetrically fixed at both ends of the balance beam of the grab bucket to play a supporting role. The front winch mechanism is also composed of a winch motor and a set of wire rope drum systems, one end of the two opening and closing wire ropes is led out from the front wire rope drum, and the other end is respectively wound around a pulley located below the middle of the crossbeam and a lower pulley located on the upper side of the bucket petal to form a pulley group.

[0034] The operating principle of the four-rope grab is as follows: the front winch is used to synchronously lower the opening and closing wire ropes, so that the deadweight of the lower beam forces the main axis of the beam below the bucket to open to an appropriate angle, and the two winches are controlled to synchronously lower the supporting wire ropes to lower the grab to the position where the material is grabbed; the opening and closing mechanism is controlled to lift and tighten the opening and closing wire ropes to complete the material grab, so that the grab is closed and the closed hopper is filled with material, and then the supporting winch is controlled to synchronously tighten the supporting wire ropes until the four wire ropes are in a uniformly stressed state, and then the two winches are controlled to move simultaneously to raise the grab to a safe height, and then move it to the required unloading site to unload the material.

[0035] In the above process, based on the current problems that the amount of material grabbed by the grab bucket each time during the operation is different, and the grabbing efficiency is generally low for materials with high specific gravity, a gantry crane grab bucket grabbing amount control system was installed that can effectively improve the operating efficiency.

[0036] like Figure 1 As shown, the gantry crane grab bucket grab amount control system includes a support mechanism position sensor, an opening and closing mechanism position sensor, a support mechanism speed encoder, an opening and closing mechanism speed encoder, an operation panel and a PLC controller; wherein,

[0037] The support mechanism position sensor is installed on the rotating mechanism of the hoist of the support mechanism to collect the rotation position signal of the motor drive shaft of the hoist of the support mechanism, and then determine the number of positive or reverse rotations of the motor drive shaft to obtain the lowering length or tightening length of the support wire rope;

[0038] The opening and closing mechanism position sensor is installed on the rotating mechanism of the hoist of the opening and closing mechanism to collect the rotation position signal of the motor drive shaft of the hoist of the opening and closing mechanism to determine the number of positive or reverse rotations of the motor drive shaft, and then obtain the lowering length or tightening length of the opening and closing wire rope;

[0039] Specifically, the support mechanism position sensor and the opening and closing mechanism position sensor can choose to use a Hall sensor, which is installed on the motor rotor assembly and determines the position signal of the motor drive shaft rotation according to its own rotation Hall sector value to convert the number of positive or reverse rotations of the motor shaft;

[0040] The supporting mechanism speed encoder is installed on the motor drive shaft of the hoist of the supporting mechanism to collect the speed signal of the motor drive shaft of the hoist of the supporting mechanism;

[0041] The opening and closing mechanism speed encoder is installed on the motor drive shaft of the hoist of the opening and closing mechanism to detect the speed signal of the motor drive shaft of the hoist of the opening and closing mechanism;

[0042] A control box is installed on the side of the linkage platform in the gantry crane cab, a PLC controller is arranged in the control box, and an operation panel is arranged on the upper surface of the control box;

[0043] The PLC controller is electrically connected to the support mechanism position sensor to obtain the rotation position signal of the motor drive shaft of the hoist of the support mechanism, and then obtain the lowering length or tightening length of the support wire rope;

[0044] The PLC controller is electrically connected to the opening and closing mechanism displacement sensor to obtain the rotation position signal of the motor drive shaft of the hoist of the opening and closing mechanism, and then obtain the lowering length or tightening length of the opening and closing wire rope.

[0045] The PLC controller is electrically connected to the support mechanism speed encoder to obtain a speed signal of the motor drive shaft of the hoist of the support mechanism;

[0046] The PLC controller is electrically connected to the speed encoder of the opening and closing mechanism to obtain the speed signal of the motor drive shaft of the hoist of the opening and closing mechanism;

[0047] The PLC controller is electrically connected to the hoist motor of the supporting mechanism through the frequency converter A, so as to control the rotation speed of the driving shaft of the hoist motor of the supporting mechanism through the PLC controller, and then when the PLC controller detects that the supporting steel wire rope is too loose relative to the opening and closing steel wire rope due to the existence of the rope difference, the lowering speed or the lifting and tightening speed of the supporting steel wire rope is controlled to reduce the rope difference;

[0048] The PLC controller is electrically connected to the hoist motor of the opening and closing mechanism through the frequency converter B, so as to control the rotation speed of the driving shaft of the hoist motor of the opening and closing mechanism through the PLC controller, and then when the PLC controller detects that the opening and closing steel wire rope is too loose relative to the supporting steel wire rope due to the existence of rope difference, the lowering speed or the lifting and tightening speed of the opening and closing steel wire rope is controlled to reduce the rope difference;

[0049] The PLC controller is electrically connected to the overload system installed on the grab bucket itself to obtain the grab bucket weight value measured by the overload system;

[0050] like Figure 2 As shown, the operation panel is provided with a display screen, a material selection knob, a deep digging adjustment knob, a deep digging start button and an automatic grab start button; specifically,

[0051] The material selection knob is connected to the PLC controller through a digital input module; specifically, the material selection knob is provided with N gears at intervals in its circumferential direction, and the number of gears N is consistent with the number of material types with different specific gravities that the company has to deal with in its actual operations. Each gear corresponds to a type of material. When the material selection knob is rotated to a specified gear, the gear outputs a specified signal to the PLC controller, so that the PLC controller controls the forward rotation of the hoist motor drive shaft of the opening and closing mechanism for a specified number of turns, so as to lower the opening and closing wire rope to a specified length, so that the grab bucket is first opened to a specified opening angle according to the known material type;

[0052] The specified opening angle is the appropriate opening angle determined based on the conventional specific gravity of the material. However, in actual operation, the actual specific gravity of the material varies greatly due to different purities.

[0053] In this embodiment, since the main cargoes to be loaded and unloaded are Yangdi powder, PB powder, FOR powder and Brazil powder, the material selection knob is set with 4 gears, and based on operating experience and the different specific gravities of the four materials, four reference adjustment values ​​are set, as shown in Table 1 below.

[0054] Table 1:

[0055] Cargo proportion Reference adjustment value Yang Di Fan 1.9 5 PB powder 2.1 4.4 FOR Powder 2.27 3.5 Brazilian powder 2.56 2.3

[0056] The deep excavation adjustment knob adopts a stepless knob, which is connected to the PLC controller through an analog input module to output a specified signal to the PLC controller, so that the PLC controller controls the hoist motor drive shaft of the opening and closing mechanism to rotate forward or reverse for a specified number of circles, so as to lower the opening and closing wire rope to a specified length or lift and tighten the opening and closing wire rope to a specified length, complete the adjustment of the number of circles of the hoist motor drive shaft, and further adjust the opening angle of the grab bucket; specifically, when setting the stepless knob, the corresponding scale range of one rotation is 0~9, and the corresponding opening angle of the grab bucket (that is, the opening angle between the two bucket petals) is 0~180°. The stepless knob can realize any slight adjustment of the grab bucket opening angle, and adjust the grab bucket from the specified opening angle to the appropriate opening angle; wherein, when the corresponding scale value of the deep excavation adjustment knob is 0, its position is neutral;

[0057] It should be noted that the appropriate opening angle refers to the grabbing amount of 40t of material in the grab after the grab grabs the material at the current opening angle and closes, which is consistent with the maximum operating load of the gantry crane. In addition, for different batches of similar goods, their specific gravity values ​​will have large and unpredictable deviations due to purity issues. Therefore, on the basis of the theoretical adjustment value, the gantry crane driver needs to adjust the appropriate opening angle of the grab during the grabbing operation according to the actual specific gravity of the current goods.

[0058] The deep excavation start button is electrically connected to the PLC controller. When it is turned on, it outputs an electrical signal to the PLC controller, so that the PLC controller controls the motor drive shaft of the hoist of the supporting mechanism to rotate to lower the supporting wire rope according to the specified signal output by the material selection knob or the deep excavation adjustment knob, so that the grab bucket is lowered to the surface of the material to be grabbed. At the same time, the PLC controller controls the motor drive shaft of the hoist of the opening and closing mechanism to rotate to lower the opening and closing wire ropes until the grab bucket opens to the specified opening angle; when the PLC controller is specifically set, when the adjustment value of the deep excavation adjustment knob is 0, the specified opening angle is determined by the current gear position of the material selection knob, and when the adjustment value of the deep excavation adjustment knob is not 0, the specified opening angle is determined by the deep excavation adjustment knob; when it drops to the surface of the material to be grabbed, the deep excavation start button is automatically closed;

[0059] The automatic grab start button is connected to the PLC controller through a data transmission line, and is used to start and close the automatic grab action of the grab bucket; specifically, when the automatic grab start button is activated, the PLC controller executes the automatic grab action once, and the process is as follows: the PLC controller controls the winch motor drive shaft of the support mechanism to rotate to lower the supporting wire rope, so that the grab bucket gradually descends to the surface of the material to be grabbed. At the same time, the PLC controller controls the winch motor drive shaft of the opening and closing mechanism to rotate to lower the opening and closing wire ropes until the grab bucket opens to the specified opening angle corresponding to the current specified adjustment value of the deep digging adjustment knob; when the grab bucket descends After the material surface is reached, the PLC controller controls the motor drive shaft of the hoist of the opening and closing mechanism to rotate to lift and tighten the opening and closing wire rope until the grab is completely closed. At this time, the material grabbing is completed. The PLC controller controls the motor drive shaft of the hoist of the supporting mechanism to rotate to lift and tighten the supporting wire rope until the opening and closing wire rope and the two wire ropes return to the initial state of no rope difference. At this time, the grabbing action is completed, the grab has lifted the material to a safe height above the safety height, and the automatic grabbing start button is automatically turned off. When the automatic grabbing start button is turned off, the material grabbing action is completely completed by the driver in the gantry crane cab through manual operation.

[0060] The display screen is electrically connected to the PLC controller, and is provided with an upper display frame and a lower display frame; the upper display frame is used to display the reference adjustment value corresponding to the current gear position of the material selection knob for reference by the gantry crane driver; the lower display frame is used to display the actual adjustment value corresponding to the current position of the deep excavation adjustment knob.

[0061] The advantage of this automatic grabbing method is that during the operation of the gantry crane, each time the grab bucket drops to the material surface, the tightness of the four steel ropes can always be kept the same as the previous time, that is, each time the grab bucket grabs the goods, the initial state is the same, the subsequent control method is the same, and the grabbing amount is the same, which reduces the error of each grabbing amount and ensures the stability of the optimal operating efficiency.

[0062] Based on the above-mentioned gantry crane grab bucket grab quantity control system, the specific implementation steps of the control method for achieving quantitative and efficient grabbing operations for different materials are as follows:

[0063] (I) Use manual adjustment to determine the appropriate opening angle of the grab bucket corresponding to the material to be grabbed:

[0064] Step 1: The gantry crane driver turns the material selection knob to the gear that matches the material according to the type of material to be grabbed, and turns on the deep digging start button; at this time, the deep digging start button sends a grabbing signal to the PLC controller, and the PLC controller controls the hoist motor drive shaft of the supporting mechanism to continue to rotate forward to lower the supporting wire rope; when the PLC controller receives the grab bucket weight value transmitted by the overload system as 0, it means that the grab bucket has been lowered to the material surface, and the PLC controller controls the hoist motor drive shaft of the supporting mechanism to stop rotating; in this process, the material selection knob inputs a specified signal to the PLC controller, and the PLC controller controls the hoist motor drive shaft of the opening and closing mechanism to rotate forward for a specified number of turns according to the specified signal, and lowers the opening and closing wire rope to a specified length, so that the grab bucket is opened to the specified opening angle corresponding to the current gear of the material selection knob;

[0065] Step 2: The gantry crane driver manually controls the hoist motor drive shaft of the opening and closing mechanism to rotate in the opposite direction, and lifts and tightens the opening and closing wire ropes to the specified length, and the grab bucket returns to the closed state; then, the gantry crane driver manually controls the hoist motor drive shaft of the supporting mechanism to rotate in the opposite direction, and lifts and tightens the two opening and closing wire ropes until the grab bucket leaves the material surface; at this time, the gantry crane driver observes the grab bucket weight value displayed in real time by the overload system to determine whether the grabbing method reaches the maximum operating capacity of the gantry crane;

[0066] Step 3: If the grab weight value in step 2 does not reach or exceed the maximum operating capacity of the gantry crane, the gantry crane driver turns the deep digging adjustment knob to the left or right based on the reference adjustment value displayed on the display screen to fine-tune the number of rotations of the winch motor drive shaft of the opening and closing mechanism, thereby adjusting the specified lowering length of the opening and closing wire rope; turn on the deep digging start button again, the deep digging start button sends a grab signal to the PLC controller, and the PLC controller controls the winch motor drive shaft of the support mechanism to continue to rotate forward until the PLC controller collects the grab weight value transmitted by the overload system as 0; at the same time, the deep digging adjustment knob inputs a specified signal to the PLC controller, and the PLC controller controls the winch motor drive shaft of the opening and closing mechanism to rotate forward for a specified number of times according to the specified signal, so as to release the opening and closing wire rope to the specified length, so that the grab is lowered to the material surface again and the grab is opened to the specified opening angle according to the adjustment value of the deep digging adjustment knob;

[0067] Repeat steps 2 and 3 until the grab opening angle corresponding to the adjustment value of the deep digging adjustment knob reaches an appropriate opening angle, that is, the material grabbing amount of the grab at this opening angle reaches the maximum operating capacity of the gantry crane; the adjustment value corresponding to the deep digging adjustment knob is the optimal adjustment value for this material grabbing operation;

[0068] (ii) Keep the grab open to the appropriate opening angle each time, and use automatic grabbing to complete material grabbing:

[0069] Keep the deep digging adjustment knob at the optimal adjustment value and press the automatic grab start button; at this time, the PLC controller automatically controls the grab bucket to complete the four actions of lowering, opening, closing and rising; specifically,

[0070] The PLC controller controls the motor drive shaft of the hoist of the supporting mechanism to rotate continuously in the positive direction, so as to lower the supporting wire rope, and gradually lower the grab bucket to the surface of the material to be grabbed. At the same time, the PLC controller controls the motor drive shaft of the hoist of the opening and closing mechanism to rotate in the positive direction for a specified number of turns, so as to lower the opening and closing wire rope for a specified length, so that the grab bucket opens to a suitable opening angle during the descending process.

[0071] When the PLC controller obtains the weight value of the grab bucket detected by the overload system as 0, it means that the grab bucket has been lowered to the material surface; at this time, the PLC controller controls the motor drive shaft of the hoist of the opening and closing mechanism to rotate in the opposite direction for a specified number of circles, so as to lift and tighten the opening and closing wire rope to a specified length, and the grab bucket is completely closed, and the material grabbing is completed;

[0072] The PLC controller controls the winch motor drive shaft of the supporting mechanism to rotate in the reverse direction continuously to lift and tighten the supporting wire rope. When the value difference between the displacement sensor of the opening and closing mechanism and the displacement sensor of the supporting mechanism is 0, it means that the rope difference between the two opening and closing wire ropes and the two supporting wire ropes is 0, and the grab bucket has risen to a safe height at this time, and the grabbing action is completed;

[0073] Subsequently, the gantry crane driver manually operates the grab bucket to transport the grabbed materials to the designated destination.

[0074] During the process of the above steps (a) and (b), the PLC controller calculates whether the rope difference between the supporting wire rope and the opening and closing wire rope exceeds the set threshold value based on the position signals input by the supporting mechanism position sensor and the opening and closing mechanism position sensor, so as to determine whether there is a loose wire rope state; when the PLC controller calculates that the rope difference exceeds the set threshold value, it controls the speed of the motor drive shaft of the supporting mechanism winch or the speed of the motor drive shaft of the opening and closing mechanism winch according to the current movement speeds of the supporting wire rope and the opening and closing mechanism speed encoder collected by the supporting mechanism speed encoder and the opening and closing mechanism speed encoder.

[0075] The gantry crane grab bucket grab volume control system was first installed on the 15# gantry crane in the applicant's operating yard and tested for material grabbing operations. During the trial run, the operating efficiency of the 15# gantry crane with the gantry crane grab bucket grab volume control system was compared with the average operating efficiency of the 12#~16# gantry cranes without the gantry crane grab bucket grab volume control system. The specific test results are shown in Table 2 below.

[0076] Table 2:

[0077]

[0078] From the comparative data results in Table 2, it can be seen that when the six gantry cranes are operating the same type of cargo on the same ship, the operating efficiency of the 15# gantry crane is significantly higher than the average operating efficiency of the other five gantry cranes, and the efficiency improvement rate can reach up to 16.70%.

[0079] At the same time, during the trial operation, statistics were also collected on the individual operating efficiency of the six drivers (referred to as Driver A-Driver F) responsible for the 15# gantry crane during the operation after the installation of the gantry crane grab bucket grab volume control system, as well as the average operating efficiency of all drivers of the 12#-16# gantry cranes in the freight yard. The specific statistical results are shown in Tables 3 to 8 below.

[0080] Table 3: Driver A's operating efficiency statistics

[0081]

[0082] Table 4: Driver B's operating efficiency statistics

[0083]

[0084] Table 5: Driver C's operating efficiency statistics

[0085]

[0086] Table 6: Driver D's operating efficiency statistics

[0087]

[0088] Table 7: Driver E's operating efficiency statistics

[0089]

[0090] Table 8: Driver F's operating efficiency statistics

[0091]

[0092] From the statistics of single-person operation efficiency in Tables 3 to 8 above, it can be seen that the single-person operation efficiency of the six drivers of the 15# gantry crane has improved compared with the average operation efficiency of all drivers of the 12# to 16# gantry cranes, and the highest efficiency improvement has reached 15.96%.

[0093] In addition, the control system of the grab bucket of the gantry crane is analyzed from the economic perspective of the applicant's enterprise. From the perspective of saving grab buckets to achieve economic value, if the applicant carries out such transformation on ten gantry cranes that often carry out bulk cargo operations, and reduces the reserve of grab buckets, and calculates based on reducing one grab bucket, each grab bucket costs 200,000 yuan, 10 gantry cranes need about 12 grab buckets (10 common grab buckets and 2 spare grab buckets), which can save 2.4 million yuan in costs. From the perspective of improving operating efficiency and achieving economic value, if calculated based on increasing the operating volume by 6%, 10 gantry cranes can increase the operating volume by 300,000 tons. Calculated at 8 yuan per ton, the economic benefits that can be created in one year are 30×8=2.4 million yuan.

Claims

1. A gantry crane grab bucket control method based on a gantry crane grab bucket grab amount control system, characterized in that: The grab amount control system of the gantry crane grab bucket includes: a) a support mechanism position sensor, which is installed on the rotating mechanism of the hoist of the support mechanism to collect the rotation position signal of the motor drive shaft of the hoist of the support mechanism; b) an opening and closing mechanism position sensor, which is installed on the rotating mechanism of the hoist of the opening and closing mechanism to collect the rotation position signal of the motor drive shaft of the hoist of the opening and closing mechanism; c) a support mechanism speed encoder, which is installed on the motor drive shaft of the hoist of the support mechanism to collect the speed signal of the motor drive shaft of the hoist of the support mechanism; d) an opening and closing mechanism speed encoder is installed on the motor drive shaft of the hoist of the opening and closing mechanism to detect the speed signal of the motor drive shaft of the hoist of the opening and closing mechanism; e) a PLC controller, which is arranged in a control box on the side of the linkage table installed in the gantry crane cab; the PLC controller is respectively connected to the support mechanism The structure position sensor is electrically connected to the opening and closing mechanism displacement sensor, and the PLC controller is electrically connected to the supporting mechanism speed encoder and the opening and closing mechanism speed encoder respectively; the PLC controller is electrically connected to the hoist motor of the supporting mechanism through the frequency converter A, the PLC controller is electrically connected to the hoist motor of the opening and closing mechanism through the frequency converter B, and the PLC controller is electrically connected to the overload system installed in the grab bucket itself; and f) an operation panel is arranged on the upper surface of the control box; the operation panel is provided with a display screen electrically connected to the PLC controller, a material selection knob electrically connected to the PLC controller through the digital quantity input module, a deep digging adjustment knob connected to the PLC controller through the analog quantity input module, a deep digging start button electrically connected to the PLC controller, and an automatic grab start button electrically connected to the PLC controller; the deep digging adjustment knob adopts a stepless knob; The steps of the gantry crane grab control method are as follows:

1. Determine the appropriate opening angle of the grab bucket corresponding to the material to be grabbed: Step 1: Turn the material selection knob to the gear that matches the material, and start the deep digging start button; the deep digging start button sends a grab signal to the PLC controller, and the PLC controller controls the hoist motor drive shaft of the support mechanism to continue to rotate forward until the PLC controller collects the grab bucket weight value transmitted by the overload system as 0; at the same time, the material selection knob inputs a specified signal to the PLC controller, and the PLC controller controls the hoist motor drive shaft of the opening and closing mechanism to rotate forward for a specified number of turns according to the specified signal, and then releases the opening and closing wire rope to a specified length, so that the grab bucket opens to a specified opening angle; Step 2: The grab grabs the material at the specified opening angle and lifts it up away from the material surface. According to the grab weight value displayed in real time by the overload system, it is determined whether this grab has reached the maximum operating capacity of the gantry crane; Step 3: If the grab weight value in step 2 does not reach or exceed the maximum operating capacity of the gantry crane, the number of rotations of the winch motor drive shaft of the opening and closing mechanism is adjusted by adjusting the deep digging adjustment knob to fine-tune the specified opening angle of the grab; the deep digging start button is started again, and the deep digging start button sends a grab signal to the PLC controller, and the PLC controller controls the winch motor drive shaft of the support mechanism to continue to rotate forward until the PLC controller collects the grab weight value transmitted by the overload system as 0; at the same time, the deep digging adjustment knob inputs a specified signal to the PLC controller, and the PLC controller controls the winch motor drive shaft of the opening and closing mechanism to rotate forward for a specified number of times according to the specified signal, and then releases the opening and closing wire rope to a specified length, so that the grab is opened to the new specified opening angle; Repeat steps 2 and 3 until the specified opening angle of the grab bucket satisfies the material grabbing amount and reaches the maximum operating capacity of the gantry crane. The current specified opening angle of the grab bucket is the appropriate opening angle of the grab bucket. The corresponding value of the deep digging adjustment knob is the optimal adjustment value. (II) Based on the appropriate opening angle determined in step (I), complete all material grabbing by automatic grabbing: Keep the deep digging adjustment knob at the optimal adjustment value and start the automatic grab start button; the automatic grab start button inputs the automatic grab operation signal to the PLC controller; The PLC controller controls the hoist motor drive shaft of the support mechanism to continuously rotate forward. At the same time, the deep digging adjustment knob inputs a specified signal to the PLC controller. The PLC controller controls the hoist motor drive shaft of the opening and closing mechanism to rotate forward for a specified number of circles, and then releases the opening and closing wire rope to a specified length. The grab opens to a suitable opening angle during the descent process. When the PLC controller obtains the weight value of the grab bucket detected by the overload system as 0, the PLC controller controls the motor drive shaft of the hoist of the opening and closing mechanism to rotate in the opposite direction for a specified number of turns, thereby lifting and tightening the opening and closing wire rope to a specified length, closing the grab bucket, and completing the material grabbing; When the PLC controller collects the speed input from the speed encoder of the opening and closing mechanism as 0, the PLC controller controls the driving shaft of the hoisting motor of the supporting mechanism to continuously rotate in the opposite direction to lift and tighten the supporting wire rope. When the value difference transmitted by the displacement sensor of the opening and closing mechanism and the displacement sensor of the supporting mechanism is 0, it means that the rope difference between the two opening and closing wire ropes and the two supporting wire ropes is 0, and the grab bucket has left the material surface at this time, and the grabbing action is completed. At this time, the control bucket is transferred to the target position for unloading; During the above steps (a) and (b), the PLC controller calculates whether the rope difference between the supporting wire rope and the opening and closing wire rope exceeds the set threshold value based on the position signals input by the supporting mechanism position sensor and the opening and closing mechanism position sensor, so as to determine whether there is a loose wire rope state; when the PLC controller calculates that the rope difference exceeds the set threshold value, it controls the speed of the motor drive shaft of the supporting mechanism winch or the speed of the motor drive shaft of the opening and closing mechanism winch according to the current movement speeds of the supporting wire rope and the opening and closing mechanism speed encoder collected by the supporting mechanism speed encoder and the opening and closing mechanism speed encoder.

2. The method for controlling a gantry crane grab bucket based on a gantry crane grab bucket grab amount control system according to claim 1, characterized in that: The supporting mechanism position sensor and the opening and closing mechanism position sensor adopt Hall sensors, which are installed on the motor rotor assembly.

3. The method for controlling a gantry crane grab bucket based on a gantry crane grab bucket grab amount control system according to claim 1, characterized in that: The display screen is provided with an upper display frame and a lower display frame; the upper display frame is used to display the value corresponding to the current gear position of the material selection knob; the lower display frame is used to display the value corresponding to the current position of the deep digging adjustment knob.

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