Large-size heavy workpiece lifting system and balance control method

Abstract

The invention discloses a large-size heavy workpiece lifting system which comprises an omni-directional moving platform, a bilateral linear expansion supporting table arranged on the omni-directional moving platform, a center driving shear fork mechanism driving the bilateral linear expansion supporting table to do lifting motion and a gravity center compensation sliding table used for balancing the gravity center position of the system. The invention further provides a balance control method. According to the system, the defects of an existing AGV in the aspects of high-position lifting and gravity center adjustment can be overcome, and efficient and accurate feeding and discharging operation is achieved.

Description

Technical Field

[0001] This invention belongs to the field of processing and manufacturing, and particularly relates to a lifting system for large-size heavy workpieces and a balance control method. Background Technology

[0002] A single part requires multiple stations and different processes to complete from machining. Utilizing Automated Guided Vehicles (AGVs) for the efficient, long-distance, and cross-production-line transfer of large, heavy workpieces is significant for improving the digital and intelligent transformation of the manufacturing industry. However, due to the large number of equipment and narrow passageways in the work area, as well as the large size and weight of the workpieces to be transferred, the application of AGVs faces problems such as non-decoupling of rolling steering and unstable high-position lifting. Omnidirectional AGVs can achieve three-degree-of-freedom planar motion along arbitrary trajectories, such as lateral movement and in-situ turning. Compared with traditional AGVs that rely on differential steering, they have high mobility and flexibility.

[0003] In smart manufacturing scenarios, various AGV lifting methods exist for high-level lifting of large, heavy workpieces, each with its own advantages and disadvantages. For example, while hydraulic or electric cylinder-driven lifting mechanisms can provide significant lifting force, the hydraulic system carries the risk of leakage, potentially damaging internal electronic components. Furthermore, hydraulic cylinder drives result in a heavier overall weight, making precise control difficult. Screw-nut or worm gear lifting mechanisms require high workpiece strength, have poor four-point synchronization, and generate significant noise during lifting. Forklift-type lifting mechanisms offer strong carrying capacity but lack flexibility in confined spaces and are susceptible to hydraulic system leakage. Disc-type lifting mechanisms have limitations on the shape and size of goods, limiting their applicability. Multi-degree-of-freedom robotic arm lifting mechanisms have limited load capacity and are primarily suitable for light-load scenarios. Scissor lifts, with multiple cross arms supporting each other, can withstand greater loads while maintaining high stability during lifting, reducing the risk of swaying and tipping. Their height is adjustable, allowing for flexible adjustments to the lifting height according to different needs, making them widely applicable not only to indoor environments but also to complex outdoor conditions. However, scissor lift mechanisms also have some shortcomings, such as the need to improve stability during high-level lifting, and the continuous accumulation of offset torque between the workpiece and the platform's center of gravity during the lifting process, which leads to a decrease in platform stability.

[0004] Patent document CN110790184B discloses a simple, compact, and low-cost AGV lifting system. It achieves lifting by driving a scissor-type lifting frame through the cooperation of a gear set and threaded connecting rods. The gear set includes a large bevel gear and two symmetrically arranged small bevel gears, enabling bidirectional drive and ensuring smooth and precise movement. Simultaneously, the scissor-type support frame employs a symmetrical, cross-design of equal-length connecting rods, combined with a slider and sliding guide rail, further improving lifting stability.

[0005] Patent document CN 105060204B discloses a high-safety lift. The lift is equipped with a safety bar, a first buckle, a swinging component, and a first elastic component. When the transmission chain breaks, the tension of the first elastic component drives the swinging component, causing the first buckle to engage with the slot on the safety bar, thereby quickly fixing the slide body and preventing it from falling suddenly, ensuring the safety of maintenance personnel.

[0006] All of the above technical solutions suffer from the problem of equipment instability caused by a shift in the center of gravity. Summary of the Invention

[0007] The purpose of this invention is to provide a lifting system for large-size heavy workpieces and a balance control method, which can solve the shortcomings of existing AGVs in high-level lifting and center of gravity adjustment.

[0008] To achieve the first objective of this invention, the following technical solution is provided: a large-size heavy workpiece lifting system, including an omnidirectional moving platform, a double-sided linear extension support platform disposed on the omnidirectional moving platform, a central drive scissor mechanism that drives the double-sided linear extension support platform to perform lifting and lowering movements, and a center-of-gravity compensation slide for balancing the position of the system's center of gravity. The central drive scissor lift mechanism includes a lower support plate and an upper support plate arranged on an omnidirectional moving platform, as well as two sets of folding rods arranged in parallel between the lower support plate and the upper support plate and a drive mechanism that drives the folding rods to move. Two folding rods with opposite folding directions are provided on the same side. The folding rod includes a first lower connecting rod and a second lower connecting rod hinged to the top surface of the lower support plate, and a first upper connecting rod and a second upper connecting rod hinged to the bottom surface of the upper support plate. The first lower connecting rod and the second lower connecting rod are arranged in parallel, and the first lower connecting rod and the second upper connecting rod are arranged symmetrically in vertical direction, and the second lower connecting rod and the first upper connecting rod are arranged symmetrically in vertical direction. The first lower link is hinged to the free end of the first upper link, and the second lower link is hinged to the free end of the second upper link; The driving mechanism includes a push-pull plate that spans two folding rods and a device plate that is horizontally arranged with the push-pull plate. The push-pull plate has a first connecting rod on both sides and the other end of the first connecting rod is rotatably sleeved on the rotating shaft at the folding point of the folding rod. The device plate has a second connecting rod on both sides and the second connecting rod is rotatably sleeved on the rotating shaft at the folding point of another folding rod on the same side. The device plate is equipped with a motor and a screw coaxially arranged at the output end of the motor, and the push-pull plate is provided with a screw hole for the screw to pass through.

[0009] This invention solves the problems of poor stability and center of gravity shift during high-level lifting in the prior art by using a double-sided linear extended support platform to adapt to different workpiece shapes, a centrally driven scissor lift mechanism to achieve smooth lifting, and a center of gravity compensation slide to adjust the center of gravity in real time.

[0010] Specifically, the omnidirectional moving platform includes a moving frame and decoupled active casters and driven casters mounted on the moving frame. The omnidirectional movement of the moving frame is achieved through the decoupled active casters, and the load pressure is distributed through the driven casters.

[0011] Specifically, the center-of-gravity compensation slide includes a support column set on the omnidirectional moving platform for supporting the lower support plate, and a mounting assembly set between the lower support plate and the omnidirectional moving platform. By being arranged below the central drive scissor mechanism, its center of gravity is controlled to be adjusted to be located below, so as to ensure the stability of the overall system.

[0012] Specifically, the mounting assembly includes a linear guide rail spanning the top of the mobile frame and a counterweight, with slides at both ends of the counterweight that slide in cooperation with the linear guide rail.

[0013] Specifically, the bilateral linear extension support platform includes a ball screw and a drive motor disposed on the top surface of the upper support plate along the folding direction of the folding rod, a first slider and a second slider sleeved on the ball screw, a first bearing plate disposed on the first slider and a second bearing plate disposed on the second slider; the relative movement between the first slider and the second slider enables the first bearing plate and the second bearing plate to complete the opening and closing action; there are two ball screws, which are arranged in parallel on the top surface of the upper support plate; The system can support a wider variety of items by using two load-bearing plates that can open and close.

[0014] Specifically, the equipment board is equipped with multiple motors, and the output ends of the multiple motors are arranged in parallel to ensure the stability of the lifting process.

[0015] Specifically, the upper support plate is equipped with a force sensor for collecting changes in the weight of goods on the bilateral linear extended support platform, thereby providing a real-time reference for force changes when adjusting the center of gravity during use.

[0016] To achieve the second objective of this invention, the following technical solution is provided: a balance control method for improving the operational stability of the large-size heavy workpiece lifting system, comprising the following steps: The workpiece is hoisted onto the double-sided linear extended support platform and then transferred to the destination area via the omnidirectional moving platform at the bottom; The double-sided linear extension support platform is raised to the target height at a constant speed by the centrally driven scissor mechanism. During the lifting process, the pressure distribution is monitored in real time by the force sensor on the upper support plate, and the position of the workpiece center of gravity is estimated based on the collected pressure data to determine whether there is a problem of center of gravity deviation. When a center of gravity deviation occurs, the position of the counterweight in the assembly can be adjusted to change the center of gravity of the final large-size heavy workpiece lifting system.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The design center drives a scissor lift mechanism that, without changing the effective support area of ​​the workpiece, works in conjunction with a center-of-gravity compensation slide to achieve more stable high-level lifting, thus avoiding tipping during operation and enabling efficient and precise loading and unloading operations. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the large-size heavy workpiece lifting system provided in this embodiment; Figure 2 This is a schematic diagram of the center-driven scissor lift mechanism provided in this embodiment; Figure 3 This is a schematic diagram of the bilateral linear extended support platform provided in this embodiment; Figure 4 A schematic diagram of the drive section of the bilateral linear extension support platform provided in this embodiment; Figure 5 This is a schematic diagram of the omnidirectional moving platform and the center-of-gravity compensation slide provided in this embodiment; In the diagram: 1. Double-sided linear extension support platform; 2. Center-driven scissor lift mechanism; 3. Center-of-gravity compensation slide; 4. Omnidirectional moving platform; 111. First bearing plate; 112. Second bearing plate; 121. First ball screw; 122. Second ball screw; 131. First stepper motor; 132. Second stepper motor; 141. First slider; 142. Second slider; 15. Upper support plate; 21. Upper connecting rod; 221. Third stepper motor; 222. Fourth stepper motor; 23. Push-pull plate; 24. Lower connecting rod; 25. Lower support plate; 31. Support column; 32. Linear guide rail; 33. Slide; 34. Counterweight. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] like Figure 1 As shown, this embodiment provides a large-size heavy workpiece lifting system, including an omnidirectional moving platform 4, a double-sided linear extension support platform 1 set on the omnidirectional moving platform 4, a central drive scissor mechanism 2 that drives the double-sided linear extension support platform 1 to perform lifting and lowering movements, and a center-of-gravity compensation slide 3 for balancing the position of the system's center of gravity.

[0021] like Figure 2 As shown, the center-driven scissor lift mechanism 2 includes a lower support plate 25 and an upper support plate 15 arranged on an omnidirectional moving platform, as well as two sets of folding rods arranged in parallel between the lower support plate 25 and the upper support plate 15 and a drive mechanism for moving the folding rods. Two folding rods with opposite folding directions are provided on the same side.

[0022] In addition, the upper support plate 15 is equipped with a force sensor array to monitor the pressure distribution in real time.

[0023] Each folding rod includes a lower connecting rod 24 hinged to the top surface of the lower support plate 25 and an upper connecting rod 21 hinged to the bottom surface of the upper support plate 15.

[0024] More specifically, the folding rods on the same side include a first lower link and a second lower link, as well as a first upper link and a second upper link.

[0025] The first lower link and the second lower link are arranged in parallel, and the first lower link and the second upper link are arranged symmetrically in the vertical direction, and the second lower link and the first upper link are arranged symmetrically in the vertical direction; the free ends of the first lower link and the first upper link are hinged, and the free ends of the second lower link and the second upper link are hinged.

[0026] The drive mechanism includes a push-pull plate 23 spanning the two folding rods and an equipment plate arranged horizontally with the push-pull plate 23. The push-pull plate 23 has a first connecting rod on both sides and the other end of the first connecting rod is rotatably sleeved on the rotating shaft at the folding point of the folding rod. The equipment plate has a second connecting rod on both sides and the second connecting rod is rotatably sleeved on the rotating shaft at the folding point of another folding rod on the same side. The equipment plate is provided with a third stepper motor 221 and a fourth stepper motor 222 arranged in parallel, as well as screws arranged coaxially at the output ends of each motor. The push-pull plate 23 is provided with screw holes for the screws to pass through, thereby ensuring the stable movement of the folding rods on both sides.

[0027] This makes it easy to stack without taking up too much space, and at the same time, it does not affect its center of gravity during the continuous lifting process.

[0028] like Figure 3 and Figure 4 As shown, the double-sided linear extension support platform 1 includes a first ball screw 121 and a second ball screw 122 arranged parallel to each other on the top surface of the upper support plate 15, a first slider 141 and a second slider 142 sleeved on each ball screw, a first bearing plate 111 provided on the first slider 141 and a second bearing plate 112 provided on the second slider 142. In addition, the transmission direction of the two ball screws is consistent with the folding direction of the lower folding rod.

[0029] The first ball screw 121 is coaxially connected to the output end of the first stepper motor 131, and the second ball screw 122 is coaxially connected to the output end of the second stepper motor 132.

[0030] In this embodiment, the first stepper motor 131 and the second stepper motor 132 are arranged separately to ensure the initial balance of the system's center of gravity.

[0031] The relative movement between the first slider 141 and the second slider 142 enables the first support plate 111 and the second support plate 112 to open and close, thereby satisfying workpieces of different shapes and volumes.

[0032] like Figure 5 As shown, its omnidirectional mobile platform 4 includes a mobile frame 41 and decoupled active casters 421 and driven casters 422 mounted on the mobile frame 41.

[0033] The center-of-gravity compensation slide 3 includes a support column 31 set on the omnidirectional moving platform for supporting the lower support plate 25, and a mounting assembly set between the lower support plate 25 and the omnidirectional moving platform 4.

[0034] The assembly components include a linear guide rail 32 spanning the top of the mobile frame 41 and a counterweight 34, with slides 33 at both ends of the counterweight 34 that slide in cooperation with the linear guide rail 32.

[0035] This embodiment also provides a balance control method for improving the operational stability of the large-size heavy workpiece lifting system provided in the above embodiments, including the following steps: Based on the shape, mass, density and other parameters of the large-sized heavy workpiece, the positions of the first bearing plate 111 and the second bearing plate 112 are adjusted by the first stepper motor 131 and the second stepper motor 132 to increase the effective support area of ​​the opening and closing plate. The workpiece is transferred to the double-sided linear extension support platform using a robotic arm or lifting platform. After being placed stably, the omnidirectional moving platform 4 efficiently transfers the workpiece to the designated plane position, and all casters of the moving platform 4 are locked. The third stepper motor 221 and the fourth stepper motor 222 work to shorten the distance between the workpiece and the push-pull plate 23, lifting the workpiece upward. The placement of the motors in the middle ensures that the effective support area of ​​the central drive scissor mechanism 2 and the upper support plate 15 does not change with the lifting height, improving the stability of lifting heavy workpieces. The pressure distribution of the first bearing plate 111 and the second bearing plate 112 is monitored in real time by a force sensor array arranged on the upper support surface, and the center of gravity position of the workpiece is estimated based on the pressure data to detect potential hazards such as tilting or uneven local stress. When the platform shows a tendency to tilt, the center of gravity adjustment closed-loop controller converts the required compensation torque into the displacement output of the slide table 33 to adjust the center of gravity of the lifting platform, achieving a safe and stable loading operation.

[0036] In summary, to address the issue of poor lifting stability for large, irregular, and heavy workpieces, this embodiment proposes a platform body design based on a center-driven scissor lift mechanism and a bilateral linear expansion mechanism. Combined with a center-of-gravity compensation slide based on linear servo control to adjust the center of gravity in real time, efficient and precise loading and unloading operations are achieved.

[0037] Furthermore, the terms "upper," "lower," "inner," "outer," "front," and "rear" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise specifically stated, the relative steps, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0038] Of course, the above description is only a specific embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention should be included in the scope of the claims of the present invention.

[0039] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A lifting system for large-size heavy-duty workpieces, characterized in that, It includes an omnidirectional moving platform, a double-sided linear extension support platform mounted on the omnidirectional moving platform, a central drive scissor mechanism that drives the double-sided linear extension support platform to perform lifting and lowering movements, and a center-of-gravity compensation slide for balancing the position of the system's center of gravity. The central drive scissor lift mechanism includes a lower support plate and an upper support plate arranged on an omnidirectional moving platform, as well as two sets of folding rods arranged in parallel between the lower support plate and the upper support plate and a drive mechanism that drives the folding rods to move. Two folding rods with opposite folding directions are provided on the same side. The folding rod includes a first lower connecting rod and a second lower connecting rod hinged to the top surface of the lower support plate, and a first upper connecting rod and a second upper connecting rod hinged to the bottom surface of the upper support plate. The first lower connecting rod and the second lower connecting rod are arranged in parallel, and the first lower connecting rod and the second upper connecting rod are arranged symmetrically in vertical direction, and the second lower connecting rod and the first upper connecting rod are arranged symmetrically in vertical direction. The first lower link is hinged to the free end of the first upper link, and the second lower link is hinged to the free end of the second upper link; The driving mechanism includes a push-pull plate that spans two folding rods and a device plate that is horizontally arranged with the push-pull plate. The push-pull plate has a first connecting rod on both sides and the other end of the first connecting rod is rotatably sleeved on the rotating shaft at the folding point of the folding rod. The device plate has a second connecting rod on both sides and the second connecting rod is rotatably sleeved on the rotating shaft at the folding point of another folding rod on the same side. The device plate is equipped with a motor and a screw coaxially arranged at the output end of the motor, and the push-pull plate is provided with a screw hole for the screw to pass through.

2. The large-size heavy workpiece lifting system according to claim 1, characterized in that, The omnidirectional mobile platform includes a mobile frame and decoupled active casters and driven casters mounted on the mobile frame.

3. The large-size heavy workpiece lifting system according to claim 1, characterized in that, The center-of-gravity compensation slide includes a support column disposed on the omnidirectional moving platform for supporting the lower support plate, and a mounting assembly disposed between the lower support plate and the omnidirectional moving platform.

4. The large-size heavy workpiece lifting system according to claim 3, characterized in that, The mounting assembly includes a linear guide rail spanning the top of the mobile frame and a counterweight block, with slides at both ends of the counterweight block that slide in cooperation with the linear guide rail.

5. The large-size heavy workpiece lifting system according to claim 1, characterized in that, The bilateral linear extension support platform includes a ball screw and a drive motor arranged on the top surface of the upper support plate along the folding direction of the folding rod, a first slider and a second slider sleeved on the ball screw, a first bearing plate arranged on the first slider and a second bearing plate arranged on the second slider. The relative movement between the first and second sliders enables the first and second support plates to open and close. There are two ball screws, which are arranged in parallel on the top surface of the upper support plate.

6. The large-size heavy workpiece lifting system according to claim 1, characterized in that, The device board is equipped with multiple motors, and the output ends of the multiple motors are arranged in parallel.

7. The large-size heavy workpiece lifting system according to claim 1, characterized in that, The upper support plate is equipped with a force sensor for collecting changes in the weight of goods on the bilateral linear extended support platform.

8. A balance control method, characterized in that, To improve the operational stability of the large-size heavy workpiece lifting system as described in any one of claims 1 to 7, the following steps are included: The workpiece is hoisted onto the double-sided linear extended support platform and then transferred to the destination area via the omnidirectional moving platform at the bottom; The double-sided linear extension support platform is raised to the target height at a constant speed by the centrally driven scissor mechanism. During the lifting process, the pressure distribution is monitored in real time by the force sensor on the upper support plate, and the position of the workpiece center of gravity is estimated based on the collected pressure data to determine whether there is a problem of center of gravity deviation. When a center of gravity deviation occurs, the position of the counterweight in the assembly can be adjusted to change the center of gravity of the final large-size heavy workpiece lifting system.

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