A lifting arm mechanism

Abstract

The present application relates to the technical field of lifting operation, and more particularly to a lifting arm mechanism, comprising a main body frame formed by splicing two large arm side plates, the two large arm side plates are bent and formed, and symmetrically distributed along the splicing part, the two large arm side plates are oppositely arranged to form an accommodating cavity inside; a reinforcing support assembly is arranged in the accommodating cavity and distributed along the length direction of the large arm side plate, and at least one reinforcing support assembly is arranged; and a connecting shaft sleeve assembly is arranged. The lifting arm mechanism is symmetrically manufactured by the two large arm side plates, the two sides are kept balanced, the function of the mechanical system is better realized, the precision and quality of the structure are ensured, the stability is better during lifting, the whole bending is adopted, the traditional multiple welds are avoided, the stress concentration points at the welds are eliminated, the whole bending forms a "groove type" cross section, the cross section moment of inertia is larger, and the bending stiffness can be significantly improved.

Description

Technical Field

[0001] This invention relates to the technical field of lifting operations, and more particularly to a lifting arm mechanism. Background Technology

[0002] The lifting boom mechanism is a core component for special-purpose vehicles to achieve spatial orientation adjustment, repositioning, and precise positioning. In complex operating environments, the lifting boom mechanism not only needs to withstand enormous static and dynamic loads, but also must meet the stringent safety requirements of industry standards for the kinematics, structural strength, and operability of leveling mechanisms.

[0003] Traditional lifting booms use a multi-plate welded box-shaped structure. Due to the large number of welds and their concentration at the longitudinal edges where stress is complex, heat-affected zone deformation and concentrated distribution points are prone to occur. These weak points are prone to fatigue, threatening operational safety. At the same time, in order to meet industry standards for the stability of the work platform, traditional designs often improve bending resistance by increasing plate thickness or setting complex internal stiffeners, resulting in a significant increase in the weight of the boom. This not only reduces the effective load capacity but also increases motion inertia, making it prone to structural vibration or swaying. Summary of the Invention

[0004] In view of the fatigue problem that easily occurs in the weak parts of the existing lifting arm mechanism, the present invention is proposed.

[0005] Therefore, one objective of this invention is to provide a lifting arm mechanism that improves the bending stiffness of the boom and the stability during lifting operations.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a lifting arm mechanism, comprising, The main frame is formed by splicing two boom side plates, which are bent and symmetrically distributed along the splicing part. The two boom side plates are arranged opposite each other to form an accommodating cavity. A reinforcing support assembly is located in the accommodating cavity and distributed along the length of the boom side plates, and at least one is provided. A connecting bushing assembly includes a boom front hinge point bushing at the front end of the boom side plate and a boom rear hinge point bushing at the rear end of the boom side plate, which is used to provide rotational support for lifting and leveling operations.

[0007] As a preferred embodiment of the lifting arm mechanism of the present invention, the boom side plate includes a main plate and flange portions formed by bending the edges on both sides, and the flange portions of the two boom side plates are spliced ​​together to form a shell structure with an accommodating cavity.

[0008] As a preferred embodiment of the lifting arm mechanism of the present invention, the main board has a variable height structure with both ends gradually narrowing at the middle endpoints in the length direction; the front hinge point bushing and the rear hinge point bushing of the main arm are respectively located at the ends of both ends of the main board in the length direction.

[0009] In a preferred embodiment of the lifting arm mechanism of the present invention, the reinforcing support assembly is provided in multiple forms, which are arranged sequentially from the front end to the rear end along the length direction of the boom side plate as a first reinforcing plate, a second reinforcing plate, a third reinforcing plate, a fourth reinforcing plate, a fifth reinforcing plate, and a sixth reinforcing plate.

[0010] As a preferred embodiment of the lifting arm mechanism of the present invention, at least one hollow groove is provided in each of the remaining reinforcing support components other than the fifth reinforcing plate, and the remaining reinforcing support components other than the first reinforcing plate extend through the boom side plate on both sides.

[0011] As a preferred embodiment of the lifting arm mechanism of the present invention, the accommodating cavity is provided with two front balance cylinder hinge point reinforcing plates and two rear balance cylinder hinge point reinforcing plates.

[0012] As a preferred embodiment of the lifting arm mechanism of the present invention, wherein: a front hinge point reinforcing plate connected to the side plate of the boom is provided on the outer side of the front hinge point bushing of the boom, a rear hinge point reinforcing plate connected to the side plate of the boom is provided on the outer side of the rear hinge point bushing of the boom, and a front hinge point top reinforcing plate is provided at the front end of the front hinge point reinforcing plate and the front end of the side plate of the boom.

[0013] In a preferred embodiment of the lifting arm mechanism of the present invention, the top of the boom side plate is provided with a first top reinforcing plate and a second top reinforcing plate in sequence from the front end to the rear end along the length direction.

[0014] As a preferred embodiment of the lifting arm mechanism of the present invention, a rear panel of the boom is provided behind the boom side plate, and a V-shaped support plate is provided at the bottom of the boom side plate.

[0015] In a preferred embodiment of the lifting arm mechanism of the present invention, a lifting cylinder fixing plate is provided on the side of the boom side plate, and the lifting cylinder fixing plate is located between the fourth reinforcing plate and the fifth reinforcing plate.

[0016] The beneficial effects of this boom lifting mechanism are: the two boom side plates are made symmetrically, maintaining balance on both sides, better realizing the function of the mechanical system, ensuring the accuracy and quality of the structure, and providing greater stability during lifting. At the same time, the overall bending avoids the multiple welds of traditional splicing, eliminating stress concentration points at the welds. The overall bending forms a "groove-shaped" cross-section, which has a larger moment of inertia and significantly improves bending stiffness. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 An overall schematic diagram of Embodiment 1 is shown; Figure 2 A schematic diagram of the boom side plate of Embodiment 2 is shown; Figure 3 A schematic diagram of the motherboard for Embodiment 2 is shown; Figure 4 A schematic diagram of the reinforcing support component of Embodiment 3 is shown; Figure 5 A front view of the reinforcing support component of Embodiment 3 is shown; Figure 6 An overall schematic diagram of Embodiment 4 is shown; Figure 7 The stress analysis diagram of the oil-containing cylinder and pin in Example 4 is shown; Figure 8 The stress analysis diagram of Example 4 without the cylinder and pin is shown; Figure 9 The stress analysis diagram of the oil cylinder and pin shaft in the working state of Example 4 is shown; Figure 10 The stress analysis diagram of Example 4 under the working condition without cylinder and pin is shown.

[0019] In the diagram: 100, Main frame; 101, Boom side plate; S, Accommodating cavity; 200, Reinforcing support assembly; 300, Connecting bushing assembly; 301, Boom front hinge point bushing; 302, Boom rear hinge point bushing; 101a, Main board; 101b, Flange; 201, First reinforcing plate; 202, Second reinforcing plate; 203, Third reinforcing plate; 204, Fourth reinforcing plate; 205, Fifth reinforcing plate; 206, Sixth reinforcing plate; 207, Hollowed-out groove; 301a, Front hinge point reinforcing plate; 302a, Rear hinge point reinforcing plate; 301b, Front hinge point top reinforcing plate; 102, First top reinforcing plate; 103, Second top reinforcing plate; 104, Boom rear panel; 105, V-shaped support plate; 106, Lifting cylinder fixing plate; 107, Front balance cylinder hinge. 108. Rear balance cylinder hinge reinforcement plate; 101b1. First plate; 101b2. Second plate; 101b3. Third plate; 101b4. Fourth plate; 101b5. Fifth plate; 101a1. First inclined edge; 101a2. First parallel edge; 101a3. Second inclined edge; 101a4. First arc-shaped edge; 101a5. Third inclined edge; 101a6. Second arc-shaped edge; 101c. Groove; 201a. First middle plate; 201b. First bent plate; 202a. Second bottom plate; 202b. Second vertical plate; 203a. Third middle plate; 203b. Third bent plate; 204a. Fourth middle plate; 204b. Fourth bent plate; 206a. Sixth bottom plate; 206b. Sixth middle plate; 206c. Sixth vertical plate. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0021] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0022] Example 1, referring to Figure 1 The first embodiment of the present invention provides a lifting arm mechanism, including a main frame 100, a reinforcing support assembly 200 and a connecting bushing assembly 300.

[0023] The main frame 100 is formed by splicing two boom side plates 101 together and fixing them together by welding. The two boom side plates 101 are bent into shape and symmetrically distributed along the splicing part. The two boom side plates 101 are arranged opposite each other inside to form a cavity S. The boom side plates 101 are bent as a whole, avoiding the multiple welds of traditional splicing and eliminating stress concentration points at the welds. The cross-section of the cavity S formed by the overall bending is "groove-shaped", with a larger moment of inertia and significantly improved bending stiffness. Furthermore, the two boom side plates 101 are made symmetrically, maintaining balance on both sides, better realizing the function of the mechanical system, ensuring the accuracy and quality of the structure, and providing greater stability during lifting.

[0024] The reinforced support component 200 is located in the accommodating cavity S and distributed along the length direction of the boom side plate 101, and at least one is provided. This effectively increases the moment of inertia of the lifting boom section, significantly improves its bending resistance, reduces the end deflection of the lifting boom, and at the same time reduces the weight of the components and the amount of materials used through structural optimization, thereby reducing manufacturing costs.

[0025] The connecting bushing assembly 300 includes a boom front hinge point bushing 301 located at the front end of the boom side plate 101 and a boom rear hinge point bushing 302 located at the rear end, for providing rotational support for lifting and leveling operations.

[0026] Example 2, refer to Figure 2 and Figure 3 This is the second embodiment of the present invention. The difference between this embodiment and the first embodiment is that the upper arm side plate 101 includes a main plate 101a and flange portions 101b formed by bending the edges on both sides. The flange portions 101b of the two upper arm side plates 101 are spliced ​​together to form a shell structure with an accommodating cavity S. The width of the main plate 101a gradually decreases from the rear end to the front end along the length direction. The front end of the main plate 101a is provided with a triangular hole with an arc transition at the included angle.

[0027] The upper flange portion 101b of the motherboard 101a includes a first plate 101b1 bent perpendicular to the motherboard 101a, and a second plate 101b2 bent perpendicular to the first plate 101b1; the lower flange portion 101b of the motherboard 101a includes a third plate 101b3 bent at an angle greater than 90 degrees to the motherboard 101a, a fourth plate 101b4 connected to the third plate 101b3 and bent perpendicular to the motherboard 101a, and a fifth plate 101b5 bent perpendicular to the fourth plate 101b4, wherein the bent portion is transitioned by an arc edge.

[0028] Among them, the main board 101a has a gradually narrowing variable height structure; the front hinge point bushing 301 and the rear hinge point bushing 302 of the main arm are located at the ends of the two ends of the main board 101a in the length direction, respectively.

[0029] The front end of the motherboard 101a includes a first inclined edge 101a1 connected to the root of the third board 101b3 and inclined toward the root of the first board 101b1, a first parallel edge 101a2 connected to the first inclined edge 101a1 and parallel to the first board 101b1, a second inclined edge 101a3 connected to the first parallel edge 101a2 and inclined toward the root of the first board 101b1, and a first arc-shaped edge 101a4 connected to the second inclined edge 101a3 and the root of the first board 101b1.

[0030] The rear end of the motherboard 101a includes a third inclined edge 101a5 connected to the root of the third board 101b3 and inclined toward the root of the first board 101b1, and a second arc-shaped edge 101a6 connected to the third inclined edge 101a5 and the root of the first board 101b1. The third board 101b3, the fourth board 101b4 and the fifth board 101b5 extend to the third inclined edge 101a5, that is, the third inclined edge 101a5 is bent to form a flange 101b. The third inclined edge 101a5 is separated from the flange 101b at the lower part of the motherboard 101a, and a groove 101c is provided on the flange 101b of the third inclined edge 101a5.

[0031] The front hinge point bushing 301 of the boom is installed inside the first arc-shaped edge 101a4, and the rear hinge point bushing 302 of the boom is installed inside the second arc-shaped edge 101a6.

[0032] In some embodiments, the main arm side plate 101 can be formed by bending a single sheet, with a thickness denoted as t, which can be 8mm to 14mm. The bending transitions between the first arc-shaped edge 101a4, the second arc-shaped edge 101a6, and the main plate 101a and the flange 101b can be rounded, with an inner radius denoted as R, which can be 20mm to 45mm. To balance bending processability and stress dispersion at the bend root, it is preferable to satisfy 2.5 ≤ R / t ≤ 4.0. The nominal bending strain of the fibers on the outer side of the bending area can be estimated using the following formula: , in, The nominal bending strain in the bending region. The thickness of the boom side plate 101 is... This refers to the inner corner radius at the bend transition. (The text abruptly ends here.) / By controlling the curvature within the above range, the curvature change at the bending transition can be avoided from being too abrupt. While ensuring the overall bending and forming stability of the main arm side plate 101, the local strain concentration at the bending root can be reduced, and the internal arrangement space of the cavity S and the bending resistance of the overall shell structure can be taken into account.

[0033] The remaining structure is the same as that in Example 1.

[0034] Example 3, referring to Figure 4 and Figure 5 This is the third embodiment of the present invention. This embodiment differs from the second embodiment in that: multiple reinforcing support components 200 are provided, and along the length direction of the upper arm side plate 101, from the front end to the rear end, they are arranged in sequence as a first reinforcing plate 201, a second reinforcing plate 202, a third reinforcing plate 203, a fourth reinforcing plate 204, a fifth reinforcing plate 205, and a sixth reinforcing plate 206. Except for the fifth reinforcing plate 205, each of the other reinforcing support components 200 has at least one hollow groove 207, and except for the first reinforcing plate 201, both sides of the other reinforcing support components 200 extend out of the upper arm side plate 101.

[0035] Within the accommodating cavity S, multiple reinforcing support components 200 are distributed along the length direction. Except for the first reinforcing plate 201 at the head end, the remaining reinforcing plates are all installed by extending through the side plates. This insert-type structure transforms the connection between the reinforcing plate and the boom side plate 101 from a single welded connection to a dual load-bearing mode of physical embedding of the plate and weld constraint, thereby enhancing the buckling resistance of the boom side plate 101 under compression.

[0036] Meanwhile, the hollowed-out grooves 207 distributed on the reinforcing support component 200 are for the purpose of achieving lightweighting, reducing motion inertia and reducing structural vibration during start-up and shutdown without reducing strength.

[0037] In some embodiments, the first reinforcing plate 201 to the sixth reinforcing plate 206 may be configured with graded thicknesses. The second reinforcing plate 202 and the fourth reinforcing plate 204, located where the stress is relatively concentrated, have a thickness denoted as... The thicknesses of the third reinforcing plate 203, the fifth reinforcing plate 205, and the sixth reinforcing plate 206 are denoted as follows: The thickness of the first reinforcing plate 201 can be the same as... Same, or slightly larger Preferably, and Satisfying 1.1≤ / ≤1.4. For plate-shaped members with similar materials, widths, and effective spans, their local bending stiffness is approximately related to the cube of the plate thickness and can be estimated using the following formula: , in, For plate thickness is The local bending stiffness of the reinforcing plate For plate thickness is The local bending stiffness of the reinforcing plate is improved. By setting the thickness in stages as described above, the reinforcing parts near the hinge point and the lifting cylinder fixing plate 106 can have high local support stiffness, while maintaining a low structural weight in other areas, thus balancing load-bearing performance and lightweight requirements.

[0038] The first reinforcing plate 201 includes a first middle plate 201a parallel to the first inclined edge 101a1, first bent plates 201b disposed at both ends of the first middle plate 201a, and two first bent plates 201b being fastened to the second plate 101b2 and the fifth plate 101b5.

[0039] The second reinforcing plate 202 includes an inclined second base plate 202a and a second vertical plate 202b bent from the second base plate 202a. The inclination direction of the second base plate 202a is opposite to that of the first middle plate 201a. The second vertical plate 202b is perpendicular to the first plate 101b1, and the bottom of the second base plate 202a is close to the first inclined edge 101a1. The bottom of the second base plate 202a and the first inclined edge 101a1 are located at the front end of the third plate 101b3.

[0040] The third reinforcing plate 203 includes an inclined third middle plate 203a and third bent plates 203b disposed at both ends of the third middle plate 203a. The third middle plate 203a has the same inclination direction as the first inclined edge 101a1. The third middle plate 203a is parallel to the first plate 101b1 and the third plate 101b3 respectively. The third reinforcing plate 203 is located between the middle and the front end of the upper arm side plate 101.

[0041] The fourth reinforcing plate 204 includes an inclined fourth middle plate 204a and fourth bent plates 204b disposed at both ends of the fourth middle plate 204a. The fourth middle plate 204a is inclined in the opposite direction to the first inclined edge 101a1. The fourth middle plate 204a is parallel to the first plate 101b1 and the third plate 101b3 respectively. The fourth reinforcing plate 204 is located between the middle and the rear end of the upper arm side plate 101.

[0042] The sixth reinforcing plate 206 is located near the rear end of the main arm side plate 101, including a sixth bottom plate 206a parallel to the third plate 101b3, a sixth middle plate 206b connected to the sixth bottom plate 206a, the sixth middle plate 206b having the same inclination direction as the first inclined edge 101a1, and a sixth vertical plate 206c connected to the sixth middle plate 206b, the sixth vertical plate 206c being perpendicular to the first plate 101b1.

[0043] The fifth reinforcing plate 205 is a flat plate and is parallel to the third plate 101b3. One end of the fifth reinforcing plate 205 is close to the connection between the sixth middle plate 206b and the sixth bottom plate 206a.

[0044] The fifth reinforcing plate 205 does not have a hollowed-out groove 207, while the first middle plate 201a, the third middle plate 203a, the fourth middle plate 204a, the sixth bottom plate 206a, and the sixth vertical plate 206c each have a hollowed-out groove 207. The second bottom plate 202a and the second vertical plate 202b each have a communicating hollowed-out groove 207.

[0045] The second reinforcing plate 202, the third reinforcing plate 203, the fourth reinforcing plate 204, the fifth reinforcing plate 205 and the sixth reinforcing plate 206 all extend through the boom side plate 101 on both sides, and the boom side plate 101 is provided with corresponding through grooves.

[0046] In some implementations, to balance weight reduction with net cross-sectional load-bearing capacity, the open area ratio of the hollow groove 207 is... It can be defined as a hollow groove with an area of ​​207. Projected area of ​​the corresponding reinforcing plate The ratio, that is: , Corresponding net cross-sectional area It can be expressed as follows: , in, For open area ratio, The area of ​​the hollow groove 207 is... To correspond to the projected area of ​​the reinforcing plate, This corresponds to the net cross-sectional area of ​​the reinforcing plate. Preferably, the remaining reinforcing plates, except for the fifth reinforcing plate 205, which are provided with hollowed-out grooves 207, have an opening ratio of... It can be controlled between 0.10 and 0.25. At the same time, the minimum distance from the groove edge to the adjacent plate edge is denoted as d, preferably satisfying d≥1.5tb, where tb is the thickness of the reinforcing plate corresponding to the hollow groove 207, so as to reduce the local stress concentration at the hole edge and ensure the local stability of the plate.

[0047] Furthermore, the protrusion lengths of the second reinforcing plate 202, the third reinforcing plate 203, the fourth reinforcing plate 204, the fifth reinforcing plate 205, and the sixth reinforcing plate 206 through the side plate 101 of the upper arm are denoted as follows: , wear out length It can be 1.5 to 3.0 times the thickness of the boom side plate 101. When the protruding part is connected to the boom side plate 101 by a double-sided continuous fillet weld, the nominal bearing area of ​​the weld can be estimated by the following formula: , in, The nominal bearing area of ​​the weld. The effective thickness of a single-sided weld. The length of the reinforcing plate extending beyond the side plate 101 of the boom is controlled by adjusting the extension length. and the effective thickness of the weld This can improve the load transfer capacity between the reinforcing plate and the boom side plate 101, and make the insert connection not only a weld connection, but also a geometric constraint formed by the plate embedding, which is conducive to reducing the local stress concentration at the groove edge and weld toe position.

[0048] The reinforcing plate forms a lattice support inside through its inclined middle plate or bottom plate, which can distribute the complex stress torque borne by the boom side plate 101 to the entire shell structure, effectively reducing the deflection of the boom during extension and retraction, and ensuring the stability of high-altitude operations.

[0049] Furthermore, the cavity S is provided with two front balance cylinder hinge point reinforcement plates 107 and two rear balance cylinder hinge point reinforcement plates 108. The front balance cylinder hinge point reinforcement plates 107 are located between the first reinforcement plate 201 and the second reinforcement plate 202, and the rear balance cylinder hinge point reinforcement plates 108 are located between the fifth reinforcement plate 205 and the rear end of the boom side plate 101.

[0050] Example 4, refer to Figures 6-10 This is the fourth embodiment of the present invention. The difference between this embodiment and the third embodiment is that: the outer side of the front hinge point bushing 301 of the boom is provided with a front hinge point reinforcing plate 301a connected to the boom side plate 101, and the outer side of the rear hinge point bushing 302 of the boom is provided with a rear hinge point reinforcing plate 302a connected to the boom side plate 101.

[0051] The front hinge point reinforcement plate 301a and the front end of the boom side plate 101 are provided with a front hinge point top reinforcement plate 301b.

[0052] The top of the boom side plate 101 is provided with a first top reinforcing plate 102 and a second top reinforcing plate 103 in sequence from the front end to the rear end along the length direction.

[0053] The boom side plate 101 is provided with a boom rear panel 104, and the bottom of the boom side plate 101 is provided with a V-shaped support plate 105.

[0054] Multiple circular process holes are provided on the front hinge point top reinforcing plate 301b, the first top reinforcing plate 102, the second top reinforcing plate 103, and the rear panel 104 of the upper arm.

[0055] The boom side plate 101 is provided with a lifting cylinder fixing plate 106, which is located between the fourth reinforcing plate 204 and the fifth reinforcing plate 205.

[0056] In some embodiments, the lifting arm structure, consisting of the main frame 100, the reinforcing support assembly 200, and the connecting bushing assembly 300, can be approximately equivalent along its length to a structure with an equivalent moment of inertia. For a beam structure, the deflection δ at its end can be estimated using the following formula: , in, For end deflection, For equivalent load, For the equivalent stress length, The elastic modulus of the material. The equivalent moment of inertia of the main frame 100 and the reinforcing support assembly 200 relative to the neutral axis is given. Since the boom side plate 101 is integrally bent to form the flange portion 101b, and multiple reinforcing support assemblies 200 are arranged along the length direction within the accommodating cavity S, the equivalent moment of inertia of the overall structure can be improved. This reduces end deflection under the same load and force-bearing length, thereby improving overall stability during lifting operations.

[0057] Furthermore, the areas where the front and rear hinge bushings 301 and 302 and the lifting cylinder fixing plate 106 are located can be used as the main constraints and load-bearing parts. The structural model with the reinforced support assembly 200 and the comparative model without the corresponding internal reinforced support can be analyzed and compared. The maximum equivalent stress distribution and the end deflection change are used as evaluation indicators. This analysis shows that the shell-type main frame 100 formed by overall bending, combined with the inserted reinforced support assembly 200 arranged along the length direction, helps to improve the load transmission path on the main frame 100, making the structural stress distribution more uniform and reducing local high-stress areas under operating conditions.

[0058] Reference Figures 7 to 10 , Figure 7 and Figure 8 This is a set of stress analysis comparison charts. Figure 9 and Figure 10 This is a comparison chart of stress analysis under another set of operating conditions. Figure 7 and Figure 9 These are the overall stress cloud diagrams for retaining the hydraulic cylinder and pins, which are connected to the loading components. Figure 8 and Figure 10 The stress cloud diagrams of the lifting arm body are displayed after concealing the hydraulic cylinders, pins, and other connecting loading components. Due to... Figure 7 and Figure 9 The center pin, hydraulic cylinder, and their hinged connections experience localized stress concentrations. The main body of the lifting arm is at a lower stress level relative to these localized stress areas, thus appearing gray or light-colored overall. The more pronounced stress colors are primarily located in… Figure 7 and Figure 9 The pin, cylinder, and their adjacent connections are located in the lower left corner. Figure 8 and Figure 10After hiding the aforementioned connecting loading components, the stress distribution on the main frame 100 and the reinforcing support assembly 200 can be displayed more intuitively, indicating that the main frame 100 does not experience large-scale high stress concentration under its own weight and working conditions, and that the lifting cylinder fixing plate 106 and the adjacent reinforcing support assembly 200 can disperse and transfer the cylinder input load.

[0059] Depend on Figures 7 to 10 The stress distribution also shows that, compared with the traditional multi-plate welded box-type lifting arm structure where the load is easily concentrated and transmitted along the longitudinal weld, hinge welding area and local stiffener connection, the main frame 100 of this embodiment is formed by splicing two integrally bent and formed boom side plates 101, and multiple reinforcing support components 200 are set along the length direction in the accommodating cavity S, so that the local load input at the cylinder and pin can be gradually diffused through the lifting cylinder fixing plate 106, adjacent reinforcing support components 200 and shell-type main frame 100. Figure 7 and Figure 9 The most obvious stress color is concentrated in the pin shaft, oil cylinder and its hinge connection position, while the main body area of ​​the lifting arm is at a lower stress level. Figure 8 and Figure 10 After concealing the hydraulic cylinder and pin, the stress distribution of the main frame 100 and the reinforcing support assembly 200 is relatively continuous, without forming a large-scale abrupt high-stress area along the length of the main body. This indicates that this embodiment can reduce the stress concentration problems caused by weld concentration and isolated load-bearing of local stiffeners in traditional welded box-type structures, improve the load dispersion capacity and fatigue resistance of the lifting arm main body, and thus help improve the structural safety and stability during lifting operations.

[0060] Combination Figures 7 to 10 The stress analysis results show that, under self-weight and operational conditions, after adopting the above-mentioned integral bent shell structure and cooperating with multiple reinforcing support components 200, the stress transmission path of the main frame 100 is more continuous, the local high stress area is dispersed, the overall stress distribution is more uniform, and compared with the comparison state without the corresponding internal reinforcing structure, the deflection at the end of the lifting arm has a decreasing trend, which is conducive to improving the structural stability during the lifting operation.

[0061] Test Instance

[0062] Under conditions of a rated load of 500 kg, fixed front and rear hinge points, a total length of 10 m, Q355B steel, and a reference plate thickness of t = 10 mm, the present invention exhibits lower end deflection, lower local maximum equivalent stress and weld toe stress, and a higher first-order natural frequency across four parameter dimensions. To verify the structural effectiveness of the lifting arm mechanism of the present invention, an exemplary static load simulation comparative analysis was conducted between the present invention and a traditional welded box-type scheme. All samples had a total length of 10 m, were made of Q355B steel, had a reference plate thickness of t = 10 mm, a rated load of 500 kg, and fixed front and rear hinge points. Unless otherwise specified, there were no specific constraints. Measurement parameters included end deflection δ, local maximum equivalent stress σeq, weld toe stress σw, structural mass m, first-order natural frequency f1, and relative displacement Δr of the connection area.

[0063] While keeping all other parameters unchanged, only the radius R of the bend transition fillet at the connection between the main board 101a and the flange 101b is changed. Tables 1 to 4 below respectively represent the present invention solution and the conventional welding solution.

[0064] To eliminate the influence of plate thickness differences on the stress state during bending transition, the ratio R / t (corner radius R to plate thickness t) is used to characterize the bending transition shape, rather than using only the absolute value of the corner radius R. Since the same R corresponds to different degrees of bending abruptness under different plate thicknesses, using R / t can more accurately reflect the degree of local stress concentration and the overall stress state in the bending transition zone.

[0065] Table 1:

[0066] As shown in Table 1, R / t represents the ratio of the bend transition fillet radius R to the thickness t of the boom side plate 101; δ represents the deflection at the end of the lifting arm, in mm; σeq represents the maximum equivalent stress in the bend root region, in MPa; σw represents the stress in the area adjacent to the weld toe at the bend transition, in MPa; m represents the structural mass, in kg; f1 represents the first natural frequency, in Hz; Δr represents the relative displacement of the connection area, in mm; and "Inventive" and "Traditional" in the table represent the present invention and the traditional welding scheme, respectively. Table 1 further shows that the present invention exhibits smaller end deflection, lower maximum equivalent stress at the bend root and weld toe stress, and a higher first natural frequency at all R / t values. Regarding the present invention itself, when R / t increases from 2.0 to 3.2, the maximum equivalent stress σeq at the bending root decreases from 308 MPa to 224 MPa, a decrease of approximately 27.3%; when it increases from 3.2 to 3.5, it decreases by only 1.8% further; however, when R / t increases from 3.5 to 3.8, σeq rebounds by 4.1%, indicating that the inflection point is located around 3.2 to 3.5, suggesting that there is an optimal range for R / t. Combining the trends of deflection and stress changes, the preferred range can be written as 2.5 to 4.0, and the more optimal range as 3.0 to 3.5.

[0067] While maintaining the consistent shape of the main board 101a, the flange portion 101b and the hollowed-out groove 207, the thickness of the second reinforcing plate 202 and the fourth reinforcing plate 204 is set to t1, and the thickness of the remaining main reinforcing plates is set to t2.

[0068] Table 2:

[0069] Table 2 shows that t1 / t2 represents the ratio of the thickness t1 of the reinforcing plate in the high-load area to the thickness t2 of the reinforcing plate in the conventional area. The thicknesses of the second reinforcing plate 202 and the fourth reinforcing plate 204 are denoted as t1, and the thicknesses of the third reinforcing plate 203, the fifth reinforcing plate 205, and the sixth reinforcing plate 206 are denoted as t2. δ represents the deflection at the end of the lifting arm, in mm; σeq represents the maximum equivalent stress in the high-load area near the second reinforcing plate 202 and the fourth reinforcing plate 204, in MPa; σw represents the stress at the weld toe of the corresponding connection area, in MPa; m represents the structural mass, in kg; f1 represents the first natural frequency, in Hz; Δr represents the relative displacement of the connection area, in mm; and "Individual" and "Transmitted" in the table represent the present invention and the traditional welding scheme, respectively. Table 2 further shows that the present invention is superior to the traditional welding scheme at all t1 / t2 values. Regarding the present invention itself, when t1 / t2 increases from 1.00 to 1.20, the maximum equivalent stress σeq in the high-load area decreases from 286MPa to 242MPa, a decrease of about 15.4%; when it increases from 1.20 to 1.30, it decreases by only 4.5%; when it increases from 1.30 to 1.45, it decreases by only 1.7%. This indicates that after t1 / t2 reaches around 1.20 to 1.30, the stress improvement brought about by further increasing the thickness gradient is significantly weakened, while the structural mass m continues to increase. Therefore, the preferred range can be written as 1.1 to 1.4, and the more preferred range can be written as 1.20 to 1.30.

[0070] While keeping the position and thickness of the reinforcing plate unchanged, change the opening ratio η of the other grooved reinforcing plates except for the fifth reinforcing plate 205.

[0071] Table 3:

[0072] As shown in Table 3, η represents the open area ratio of the hollow groove 207, i.e., the ratio of the area of ​​the hollow groove 207 to the projected area of ​​the corresponding reinforcing plate; δ represents the deflection at the end of the lifting arm, in mm; σeq represents the maximum equivalent stress in the edge region of the hollow groove 207, in MPa; σw represents the stress in the corresponding weld toe region, in MPa; m represents the structural mass, in kg; f1 represents the first natural frequency, in Hz; Δr represents the relative displacement of the connection area, in mm; and "Invention" and "Traditional" in the table represent the present invention and the traditional welding scheme, respectively. Table 3 further shows that the present invention exhibits lower local stress and higher natural frequency at all open area ratio values. Regarding the invention itself, when η increases from 0.18 to 0.21, the maximum equivalent stress σeq at the edge of the hollowed-out groove increases from 240MPa to 252MPa, an increase of approximately 5.0%; when η increases from 0.21 to 0.24, σeq further increases to 276MPa, an increase of approximately 9.5%; when η increases from 0.24 to 0.27, σeq further increases to 304MPa, an increase of approximately 10.1%, while the first-order natural frequency f1 decreases from 6.38Hz to 6.18Hz and then to 5.92Hz, indicating a significant performance abrupt change in the range of 0.21 to 0.24. Considering both the weight reduction effect and the trend of local stress amplification, the preferred range can be defined as 0.10–0.25, and the more preferred range as 0.12–0.21.

[0073] While keeping the shape, thickness and weld type of the reinforcing plate consistent, the length Le of the reinforcing plate extending out of the main arm side plate 101 is changed, and the thickness of the main arm side plate 101 is represented by ts.

[0074] Table 4:

[0075] Table 4 shows that Le / ts represents the ratio of the length Le of the reinforcing plate extending through the main boom side plate 101 to the thickness ts of the main boom side plate 101, where ts=t=10mm in this test example; δ represents the deflection at the end of the lifting arm, in mm; σeq represents the maximum equivalent stress in the connection area, in MPa; σw represents the stress in the weld toe area, in MPa; m represents the structural mass, in kg; f1 represents the first natural frequency, in Hz; Δr represents the relative displacement of the connection area, in mm; and "Inventory" and "Transmission" in the table represent the present invention and the traditional welding scheme, respectively. Table 4 further shows that the present invention is superior to the traditional welding scheme at all Le / ts values. Regarding the invention itself, when Le / ts increases from 1.00 to 2.00, the weld toe stress σw decreases from 278 MPa to 216 MPa, a decrease of approximately 22.3%, and the relative displacement Δr in the connection area decreases from 0.82 mm to 0.34 mm. When increasing from 2.00 to 2.50, σw only decreases by 5.6% further; however, when increasing from 2.50 to 3.25, σw actually increases from 204 MPa to 219 MPa, an increase of approximately 7.4%. This indicates that Le / ts forms the most significant optimization range around 2.0 to 2.5, and further increasing the penetration length has reached its limit in improving the stress in the connection area. Considering the changes in weld toe stress, relative displacement, and overall dynamic performance, the preferred range can be defined as 1.5 to 3.0, and the more preferred range as 2.0 to 2.5.

[0076] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A lifting arm mechanism, characterized in that: include, The main frame (100) is formed by splicing two large arm side plates (101). The two large arm side plates (101) are bent and symmetrically distributed along the splicing part. The two large arm side plates (101) are arranged opposite to each other in the interior to form an accommodating cavity (S). A reinforcing support assembly (200) is provided, which is located in the accommodating cavity (S) and distributed along the length direction of the upper arm side plate (101), and at least one such assembly is provided; and, The connecting bushing assembly (300) includes a boom front hinge point bushing (301) disposed at the front end of the boom side plate (101) and a boom rear hinge point bushing (302) disposed at the rear end, for providing rotational support for lifting and leveling operations. The boom side plate (101) includes a main plate (101a) and flange portions (101b) formed by bending the two side edges. The flange portions (101b) of the two boom side plates (101) are spliced ​​together to form a shell structure with an accommodating cavity (S). The main board (101a) has a variable height structure with both ends gradually narrowing at the middle endpoints along its length; the front hinge point bushing (301) and the rear hinge point bushing (302) of the upper arm are located at the ends of both ends of the main board (101a) along its length. The reinforcing support assembly (200) is provided in multiple parts, and along the length direction of the upper arm side plate (101) from the front end to the rear end, they are the first reinforcing plate (201), the second reinforcing plate (202), the third reinforcing plate (203), the fourth reinforcing plate (204), the fifth reinforcing plate (205) and the sixth reinforcing plate (206).

2. The lifting arm mechanism according to claim 1, characterized in that: Each of the reinforcing support components (200) other than the fifth reinforcing plate (205) has at least one hollowed-out groove (207), and the reinforcing support components (200) other than the first reinforcing plate (201) extend through the large arm side plate (101) on both sides.

3. The lifting arm mechanism according to claim 1 or 2, characterized in that: The accommodating cavity (S) is provided with two front balance cylinder hinge point reinforcing plates (107) and two rear balance cylinder hinge point reinforcing plates (108).

4. The lifting arm mechanism according to claim 1 or 2, characterized in that: The outer side of the front hinge point bushing (301) of the boom is provided with a front hinge point reinforcing plate (301a) connected to the boom side plate (101), the outer side of the rear hinge point bushing (302) of the boom is provided with a rear hinge point reinforcing plate (302a) connected to the boom side plate (101), and the front hinge point reinforcing plate (301a) and the front end of the boom side plate (101) are provided with a front hinge point top reinforcing plate (301b).

5. The lifting arm mechanism according to claim 1 or 2, characterized in that: The top of the boom side plate (101) is provided with a first top reinforcing plate (102) and a second top reinforcing plate (103) in sequence from the front end to the rear end along the length direction.

6. The lifting arm mechanism according to claim 3, characterized in that: The boom side plate (101) is provided with a boom rear panel (104) behind it, and a V-shaped support plate (105) is provided at the bottom of the boom side plate (101).

7. The lifting arm mechanism according to claim 4, characterized in that: The boom side plate (101) is provided with a lifting cylinder fixing plate (106) on the side, and the lifting cylinder fixing plate (106) is located between the fourth reinforcing plate (204) and the fifth reinforcing plate (205).

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