Mobile crane and boom lifting control method based on self-adaptive waist rope

Abstract

The invention relates to the technical field of mobile cranes, and discloses a mobile crane and a boom lifting control method based on a self-adaptive waist rope. The length of the waist rope can be automatically adjusted according to the deformation condition of the cantilever crane, the length of the waist rope is adjusted through the self-adaptive adjusting device according to the detection result, the deformation of the cantilever crane is always within the ideal range, and the problems that the structure of the cantilever crane is unstable due to the too loose waist rope and the cantilever crane is bent reversely due to the too tight waist rope, and then fatigue damage of the cantilever crane is caused are solved; and meanwhile, the tension of the waist rope is indirectly monitored in real time through a shearing force pin shaft sensor arranged on the fixed pulley block, and the length of the waist rope is correspondingly adjusted through a self-adaptive adjusting device, so that the risk of accidents caused by wrong connection of the specification of the waist rope due to misoperation or load on a lifting hook during arm lifting can be solved, the control structure is simple, and the control cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of mobile cranes, and in particular to a mobile crane and a boom raising and lowering control method based on an adaptive waist rope. Background Art

[0002] Mobile cranes usually use booms for hoisting operations. In order to pursue a larger operating range and operating amplitude, increasing the length of the boom is the only effective way. In order to pursue large lifting performance and save materials, the boom is usually made of high-strength materials, with small cross-sections, small pipe diameters, and light weight, but the problem that comes with it is low structural rigidity. During the boom raising process, when the boom is placed horizontally, it will produce downward deflection due to its own weight. As the boom of the variable-length system is raised, the boom head will be lifted off the ground, and the boom will produce axial loads due to the tension of the variable-length system. This axial load aggravates the downward deflection of the boom and produces secondary deformation. Although the calculated stress caused is not large, due to the low stiffness of the boom, it is easy to cause structural instability and cause the boom to fail, resulting in serious consequences of boom damage. Therefore, this phenomenon seriously restricts the increase in the length of the crane's boom.

[0003] At present, the traditional method is to add a fixed-length waist rope auxiliary device in the middle of the boom, so as to greatly reduce the deflection of the boom, which is particularly obvious for the long boom system. A phenomenon that often occurs in the fixed-length waist rope boom system is that when the boom angle changes, the distance between the pull plate connected to the waist rope near the middle of the boom and the boom connection point changes greatly, and the boom is very likely to bend backward, that is, the boom is reasonable but the boom is bent backward during the working condition. The so-called backbending means that the deflection of the boom is deformed upward under normal working conditions. If the boom is bent backward for a long time, it is easy to cause fatigue damage to the boom itself.

[0004] In addition, the traditional waist rope length is calculated by finite element method. In order to minimize the waist rope specifications, different length booms use the same waist rope as much as possible. This cannot guarantee that each length of boom is in an ideal state during lifting and operation. At the same time, since there is no detection of waist rope force, it is difficult to avoid accidents when the waist rope specifications are connected incorrectly or the hook is loaded when lifting the boom due to operating errors on site.

[0005] Therefore, how to automatically adjust the waist rope length according to the downward deflection of the boom to ensure that the boom does not lose stability during the raising process and does not bend back during the operation, while performing real-time detection of the waist rope force to avoid accidents caused by improper on-site operation has become a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a mobile crane and a boom raising and lowering control method based on an adaptive waist rope to solve the problems pointed out in the above background technology.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted is as follows:

[0008] A mobile crane comprises a boom, a front pull plate, a rear pull plate, a waist rope, a guide pulley block, a root angle sensor, a head angle sensor and a main machine. A root angle sensor is installed at one end of the boom close to the main machine, and a head angle sensor is installed at the other end. The crane also comprises an adaptive adjustment device. One end of the waist rope is connected to the adaptive adjustment device, and the other end is connected to the guide pulley block between the front pull plate and the rear pull plate. The pulley assembly is connected to the pulley bracket through a pulley shaft. Both ends of the pulley shaft are fastened by shaft end baffles and fixing bolts. The other end of the pulley bracket is connected to the boom through a shear force pin shaft sensor, and the shear force pin shaft sensor is axially fixed by a spring clip.

[0009] As a further improvement of the present invention, the adaptive adjustment device is a mechanism such as a winch mechanism or a cylinder mechanism that can adjust the length of the waist rope.

[0010] As a further improvement of the present invention, the adaptive adjustment device is a winch mechanism, a ratchet drum is installed in the middle of the winch mechanism, a pawl is fixed at the position of the arm corresponding to the ratchet drum, and the pawl is aligned with the ratchet on the ratchet drum and meshes well, the pawl is in a normally closed state to prevent the winch mechanism from causing the waist rope to loosen due to factors such as hydraulic leakage, and the pawl is opened only when the length of the waist rope is adjusted.

[0011] A boom raising and lowering control method based on an adaptive waist rope, the boom raising and lowering control method based on an adaptive waist rope is applied to any of the mobile cranes described above, comprising the following steps:

[0012] S1. Start the mobile crane;

[0013] S2. Operate the main machine of the mobile crane to raise or lower the boom;

[0014] S3, respectively compare whether the difference between the root angle sensor angle A and the head angle sensor angle B and the arm theoretical angle C is greater than the allowable angle deviation value α, if the difference between the root angle sensor angle A and the arm theoretical angle C or the difference between the head angle sensor angle B and the arm theoretical angle C is greater than the allowable angle deviation value α, go to step S4, if the difference between the root angle sensor angle A and the head angle sensor angle B and the arm theoretical angle C is not greater than the allowable angle deviation value α, go to step S5;

[0015] S4, start the adaptive adjustment device to perform the waist rope and wire rope retraction action;

[0016] S5, continue to perform the arm raising or lowering action;

[0017] S6, judging whether the arm theoretical angle C reaches the target angle, if the arm theoretical angle C does not reach the target angle, returning to step S2, if the arm theoretical angle C reaches the target angle, stopping the action, and the arm ends the lifting or lowering process;

[0018] S7, comparing the force F of the shear force pin sensor with the allowable force value f of the shear force pin sensor, if the force F of the shear force pin sensor is less than the allowable force value f of the shear force pin sensor, returning to step S3, if the force F of the shear force pin sensor is not less than the allowable force value f of the shear force pin sensor, entering step S8;

[0019] S8, start the adaptive adjustment device, release the waist rope and wire rope, and return to step S3.

[0020] As a further improvement of the present invention, the calculation formula of the arm theoretical angle C is as follows:

[0021] C=(A+B) / 2

[0022] Where A is the angle measured by the root angle sensor, B is the angle measured by the head angle sensor, and C is the theoretical angle of the boom.

[0023] As a further improvement of the present invention, when the difference between the root angle sensor angle A and the head angle sensor angle B and the arm theoretical angle C is not within the allowable angle deviation value range, or the shear force applied to the shear force pin sensor is not within the allowable force value range of the pin sensor, the length of the waist rope is adjusted by an adaptive adjustment device to control the deformation and stress of the arm so as not to exceed the allowable value.

[0024] As a further improvement of the present invention, the allowable angle deviation value α of the boom and the allowable force value f of the shear force pin sensor are determined by the structural performance parameters of the boom, the front pull plate and the rear pull plate.

[0025] The beneficial effects of the present invention are:

[0026] The boom raising and lowering control method based on adaptive waist rope and the crane using this method of the present invention can automatically adjust the waist rope length according to the deformation of the boom, avoiding the problems of boom structure instability and boom reverse bending during the boom raising and lowering process, and at the same time can solve the risk of accidents caused by improper operation due to multiple waist rope specifications and no waist rope force detection, and the control system has a simple structure and low control cost.

[0027] The boom raising and lowering control method based on adaptive waist rope and the crane using this method provided by the present invention utilize root angle sensor and head angle sensor to realize the detection of boom deflection degree, and the adaptive adjustment device adjusts the waist rope length according to the detection result, so that the boom deformation is always in the ideal range, avoiding the problem of boom structure instability caused by too loose waist rope and boom reverse bending caused by too tight waist rope, which further causes boom fatigue damage. At the same time, the waist rope tension is indirectly monitored in real time by arranging a shear force pin shaft sensor on the fixed pulley group, and the waist rope length is adjusted accordingly through the adaptive adjustment device, which can solve the risk of accidents caused by wrong waist rope specifications connected due to operating errors or the hook carrying load when raising and lowering the boom, and the control structure is simple and the control cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0029] Figure 1 It is a state diagram of the lifting and lowering arm of the mobile crane of the present invention;

[0030] Figure 2 is an operating state diagram of the mobile crane of the present invention;

[0031] Figure 3 It is a schematic diagram of the relationship between the theoretical center line of the boom, the actual center line, the angle measured by the root angle sensor, the angle measured by the head angle sensor and the theoretical angle of the boom;

[0032] Figure 4 It is a structural schematic diagram of the guide pulley block;

[0033] Figure 5 A schematic diagram of the structure of the guide pulley assembly from a second perspective;

[0034] Figure 6 It is a structural schematic diagram of the adaptive adjustment device;

[0035] Figure 7 It is a schematic diagram of the second viewing angle structure of the adaptive adjustment device;

[0036] Figure 8 The figure is a flow chart of the boom raising and lowering control method based on the adaptive waist rope of the present invention.

[0037] In the figure: 1. Boom; 2. Front pull plate; 3. Rear pull plate; 4. Waist rope; 5. Guide pulley group; 501. Pulley assembly; 502. Pulley bracket; 503. Pulley shaft; 504. Fixing bolt; 505. Shear force pin sensor; 506. Spring clip; 507. Shaft end baffle; 6. Adaptive adjustment device; 601. Ratchet reel; 602. Ratchet pawl; 7. Root angle sensor; 8. Head angle sensor; 9. Main machine. DETAILED DESCRIPTION

[0038] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0040] like Figure 1-7 As shown, a mobile crane comprises a boom 1, a front pull plate 2, a rear pull plate 3, a waist rope 4, a guide pulley block 5, a root angle sensor 7, a head angle sensor 8 and a main machine 9. The boom 1 is provided with a root angle sensor 7 at one end close to the main machine 9, and a head angle sensor 8 at the other end. The boom 1 also comprises an adaptive adjustment device 6. One end of the waist rope 4 is connected to the adaptive adjustment device 6, and the other end is connected to the guide pulley block 5 between the front pull plate 2 and the rear pull plate 3. The guide pulley block 5 comprises a pulley assembly The pulley assembly 501 comprises a pulley bracket 502, a pulley shaft 503, a fixing bolt 504, an axis end baffle 507, a shear force pin sensor 505 and a spring clip 506. The pulley assembly 501 is connected to the pulley bracket 502 through the pulley shaft 503. Both ends of the pulley shaft 503 are fastened by the axis end baffle 507 and the fixing bolt 504. The other end of the pulley bracket 502 is connected to the arm 1 through the shear force pin sensor 505. The shear force pin sensor 505 is axially fixed by the spring clip 506.

[0041] The self-adaptive adjustment device 6 is a mechanism such as a hoisting mechanism or a cylinder mechanism that can adjust the length of the waist rope 4.

[0042] The adaptive adjustment device 6 is a winch mechanism, and a ratchet drum 601 is installed in the middle of the winch mechanism. A pawl 602 is fixed at the position of the arm 1 corresponding to the ratchet drum 601, and the pawl 602 is aligned with the ratchet on the ratchet drum 601 and meshes well. The pawl 602 is in a normally closed state to prevent the winch mechanism from loosening the waist rope 4 due to factors such as hydraulic leakage. The pawl 602 is opened only when the length of the waist rope 4 is adjusted.

[0043] like Figure 8 As shown, a method for controlling the rise and fall of a boom 1 based on an adaptive waist rope 4 is applied to any of the mobile cranes described above, and comprises the following steps:

[0044] S1. Start the mobile crane;

[0045] S2, operating the main machine 9 of the mobile crane to raise or lower the boom 1;

[0046] S3, respectively compare whether the difference between the angle A of the root angle sensor 7 and the angle B of the head angle sensor 8 and the theoretical angle C of the boom 1 is greater than the allowable angle deviation value α, if the difference between the angle A of the root angle sensor 7 and the theoretical angle C of the boom 1 or the difference between the angle B of the head angle sensor 8 and the theoretical angle C of the boom 1 is greater than the allowable angle deviation value α, go to step S4, if the difference between the angle A of the root angle sensor 7 and the angle B of the head angle sensor 8 and the theoretical angle C of the boom 1 is not greater than the allowable angle deviation value α, go to step S5;

[0047] S4, start the adaptive adjustment device 6 to perform the waist rope 4 steel wire rope retraction action;

[0048] S5, continue to perform the arm raising or lowering action of arm stand 1;

[0049] S6, judging whether the theoretical angle C of the boom 1 reaches the target angle, if the theoretical angle C of the boom 1 does not reach the target angle, returning to step S2, if the theoretical angle C of the boom 1 reaches the target angle, stopping the action, and the boom 1 ends the lifting or lowering process;

[0050] S7, compare the force F of the shear force pin sensor 505 with the allowable force value f of the shear force pin sensor 505, if the force F of the shear force pin sensor 505 is less than the allowable force value f of the shear force pin sensor 505, return to step S3, if the force F of the shear force pin sensor 505 is not less than the allowable force value f of the shear force pin sensor 505, proceed to step S8;

[0051] S8, start the adaptive adjustment device 6, perform the waist rope 4 wire rope release action, and return to step S3. The calculation formula of the arm frame 1 theoretical angle C is as follows:

[0052] C=(A+B) / 2

[0053] Wherein, A is the angle measured by the root angle sensor 7, B is the angle measured by the head angle sensor 8, and C is the theoretical angle of the boom 1.

[0054] When the difference between the angle A of the root angle sensor 7 and the angle B of the head angle sensor 8 and the theoretical angle C of the boom 1 is not within the allowable angle deviation range, or the shear force applied to the shear force pin sensor 505 is not within the allowable force range of the pin sensor, the length of the waist rope 4 is adjusted by the adaptive adjustment device 6 to control the deformation and stress of the boom 1 not to exceed the allowable value.

[0055] The allowable angle deviation value α of the boom 1 and the allowable force value f of the shear force pin sensor 505 are determined by the structural performance parameters of the boom 1 , the front pull plate 2 and the rear pull plate 3 .

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, component splitting or combination, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A mobile crane, comprising a boom, a front pull plate, a rear pull plate, a waist rope, a guide pulley block, a root angle sensor, a head angle sensor and a mainframe, wherein a root angle sensor is installed at one end of the boom close to the mainframe, and a head angle sensor is installed at the other end, characterized in that: It also includes an adaptive adjustment device, one end of the waist rope is connected to the adaptive adjustment device, and the other end is connected to the guide pulley group between the front pull plate and the rear pull plate, the guide pulley group includes a pulley assembly, a pulley bracket, a pulley shaft, a fixing bolt, an axis end baffle, a shear force pin sensor and a spring clip, the pulley assembly is connected to the pulley bracket through the pulley shaft, the two ends of the pulley shaft are fastened by the axis end baffle and the fixing bolts, the other end of the pulley bracket is connected to the arm bracket through the shear force pin sensor, and the shear force pin sensor is axially fixed by the spring clip.

2. A mobile crane according to claim 1, characterized in that: The self-adaptive adjustment device is a winch mechanism or a cylinder mechanism.

3. A mobile crane according to claim 2, characterized in that: The adaptive adjustment device is a winch mechanism, a ratchet drum is installed in the middle of the winch mechanism, a pawl is fixed at the position on the arm corresponding to the ratchet drum, and the pawl is aligned with the ratchet on the ratchet drum and meshes well, the pawl is in a normally closed state to prevent the winch mechanism from loosening the waist rope due to factors such as hydraulic leakage, and the pawl is opened only when adjusting the length of the waist rope.

4. A boom raising and lowering control method based on an adaptive waist rope, the boom raising and lowering control method based on an adaptive waist rope is applied to a mobile crane as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Start the mobile crane; S2. Operate the main machine of the mobile crane to raise or lower the boom; S3, respectively compare whether the difference between the root angle sensor angle A and the head angle sensor angle B and the arm theoretical angle C is greater than the allowable angle deviation value α, if the difference between the root angle sensor angle A and the arm theoretical angle C or the difference between the head angle sensor angle B and the arm theoretical angle C is greater than the allowable angle deviation value α, go to step S4, if the difference between the root angle sensor angle A and the head angle sensor angle B and the arm theoretical angle C is not greater than the allowable angle deviation value α, go to step S5; S4, start the adaptive adjustment device to perform the waist rope and wire rope retraction action; S5, continue to perform the arm raising or lowering action; S6, judging whether the arm theoretical angle C reaches the target angle, if the arm theoretical angle C does not reach the target angle, returning to step S2, if the arm theoretical angle C reaches the target angle, stopping the action, and the arm ends the lifting or lowering process; S7, comparing the force F of the shear force pin sensor with the allowable force value f of the shear force pin sensor, if the force F of the shear force pin sensor is less than the allowable force value f of the shear force pin sensor, returning to step S3, if the force F of the shear force pin sensor is not less than the allowable force value f of the shear force pin sensor, entering step S8; S8, start the adaptive adjustment device, release the waist rope and wire rope, and return to step S3.

5. The boom raising and lowering control method based on adaptive waist rope according to claim 4 is characterized in that: The calculation formula of the arm theoretical angle C is as follows: C=(A+B) / 2 Where A is the angle measured by the root angle sensor, B is the angle measured by the head angle sensor, and C is the theoretical angle of the boom.

6. The boom raising and lowering control method based on adaptive waist rope according to claim 4 is characterized in that: When the difference between the root angle sensor angle A and the head angle sensor angle B and the arm theoretical angle C is not within the allowable angle deviation value range, or the shear force applied to the shear force pin sensor is not within the allowable force value range of the pin sensor, the length of the waist rope is adjusted by the adaptive adjustment device to control the deformation and stress of the arm so that it does not exceed the allowable value.

7. The boom raising and lowering control method based on adaptive waist rope according to claim 4 is characterized in that: The allowable angle deviation value α of the boom and the allowable force value f of the shear force pin sensor are determined by the structural performance parameters of the boom, the front pull plate and the rear pull plate.

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