Clamp for stacking rice seedling trays

Abstract

The invention discloses a clamp for stacking rice seedling trays, and relates to the technical field of agricultural machinery. The clamp comprises a fixed rack, an air cylinder, an end disc chain rod mechanism and a clamping chain rod mechanism. The clamping chain rod mechanism is in driving connection with a clamping fixing plate with a lead angle part; and the end disc chain rod mechanism is in driving connection with an end disc plate with an inward lifting plate. The cylinder drives the two sets of chain rod mechanisms to cooperatively act, so that the lifting plate supports the seedling tray from the bottom, and meanwhile, the clamping fixing plate clamps the seedling tray from the side surface, so that the lower support and the upper clamping are realized. According to the invention, double-side synchronous driving is realized by arranging a master-slave transmission arm and a transmission shaft, four-side wrapping and self-guiding are formed by additionally arranging a clamping positioning plate, and height self-adaptive collision prevention is realized by arranging a height detection sensor and a telescopic butt flange. The clamp fundamentally solves the problems that seedling trays are prone to being damaged, carrying is dislocated and a machine is collided due to a traditional side clamping mode, and efficient, lossless and safe automatic seedling tray stacking operation is achieved.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery technology, and in particular to a clamp for rice seedling tray stacking. Background Technology

[0002] In factory-scale rice seedling production, it is usually necessary to centrally stack, transport, and transfer the seedling trays after sowing. Currently, this step often relies on robotic arms or specialized clamps mounted on gantry cranes for automated operation.

[0003] However, most existing seedling tray clamps on the market use a simple parallel pneumatic gripper structure, which involves directly gripping and lifting the seedling tray by using two cylinders on the left and right sides. This clamping method has at least the following significant drawbacks: 1. It can easily lead to damage to the seedling tray and seedlings falling off: Because force is applied directly to the side of the seedling tray, plastic seedling trays that are not strong enough or have aged due to repeated use are very likely to break during clamping or high-speed movement, causing the seedlings already sown in the tray to fall off, resulting in economic losses and work interruption.

[0004] 2. Misalignment and instability are prone to occur during handling: Relying solely on clamping from both sides, the seedling trays are prone to rotation or lateral sliding within the clamps due to inertia during high-speed starts, stops, or turns, resulting in angular misalignment between stacked seedling trays. This not only affects the neatness of the stacking but also poses a risk of falling.

[0005] 3. Lack of adaptability and risk of collision: When the stacked heights of the seedling trays to be gripped are inconsistent, the fixed-stroke gripper cannot adaptively adjust the gripping height. If the robotic arm continues to descend according to the preset program, a rigid collision between the gripper and the stack of seedling trays (i.e., "collision") is very likely to occur, damaging the equipment or the seedling trays; 4. Inaccurate clamping force control: Insufficient clamping force can easily cause the seedling tray to slip off, while excessive clamping force can directly damage the edge of the seedling tray. Existing clamping mechanisms are unable to achieve a good balance between clamping reliability and protecting the seedling tray.

[0006] Existing seedling tray clamping mechanisms have significant shortcomings in reliability, stability, and adaptability, failing to meet the stringent requirements of efficient, non-destructive, and automated handling in modern seedling production. Therefore, there is an urgent need for a new type of tray clamp that can lift the seedling tray from the bottom, provide stable clamping from all four sides, and adapt to different stacking heights to solve the aforementioned technical challenges.

[0007] The embodiments of the present invention are improvements made to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to provide a clamp for rice seedling tray stacking. By implementing this invention, problems such as easy breakage of seedling trays, easy misalignment during handling, and easy collision with machines due to incompatible height caused by traditional side clamping methods can be effectively solved, thereby achieving stable, reliable, non-destructive, and automated handling and stacking.

[0009] To achieve the aforementioned objective, embodiments of the present invention provide a clamp for stacking rice seedling trays. One aspect of the technical solution employed by this clamp is: It includes a fixed frame, a cylinder, an end plate chain mechanism, and a clamping chain mechanism, with the cylinder mounted on the fixed frame. The clamping chain mechanism is connected to a clamping fixing plate, which can rise and fall with the drive of the clamping chain mechanism, and has an outwardly inclined chamfered portion at its bottom end; The aforementioned end plate chain mechanism is connected to an end plate, and an inwardly extending lifting plate is provided on the bottom side of the end plate. The end plate can move with the drive of the end plate chain mechanism, and cause the lifting plate to perform an inward tightening action or an outward loosening action.

[0010] The aforementioned end plate chain mechanism and clamping chain mechanism are both connected to the cylinder drive. The cylinder can drive the clamping chain mechanism to drive the clamping plate to perform clamping and loosening actions, and the cylinder can drive the end plate chain mechanism to drive the end plate to perform end plate actions.

[0011] The aforementioned technical solution, by setting up a clamping and fixing plate and an end plate with a unique structure, and utilizing a cylinder to drive the corresponding chain mechanism, achieves a combined action of "bottom lifting" and "lateral clamping" for the seedling tray. The chamfered corner facilitates the insertion of the seedling tray, while the inward tightening action of the lifting plate reliably supports the edge of the seedling tray from the bottom. This combined clamping method completely changes the force pattern of traditional simple lateral clamping, transforming the concentrated lateral force that easily leads to seedling tray breakage into a dispersed force with bottom support as the main component and lateral restraint as a secondary component. This ensures reliable clamping while greatly reducing the risk of damage to the seedling tray itself, improving the stability of handling and the reliability of automated operation.

[0012] Optionally, the fixture also includes a chain rod A, which is connected to the clamping plate and the fixed frame respectively. Under the action of the cylinder-driven clamping chain rod mechanism, the clamping chain rod mechanism can drive the clamping plate to move inward or outward through the chain rod A. Specifically, the cylinder can drive the clamping chain rod mechanism to move downward and tilt inward.

[0013] Optionally, the clamp also includes a chain rod B, a main drive arm, and a driven drive arm. The main drive arm and the driven drive arm are rotatably mounted on opposite ends of the fixed frame. The main drive arm and the driven drive arm are rigidly connected by a drive shaft. One end of the main drive arm is connected to the drive end of the cylinder, and the other end of the main drive arm is connected to the chain rod B. When the cylinder drives the main drive arm to move, it can drive the driven drive arm to rotate synchronously through the drive shaft. At the same time, the main drive arm drives the end plate to move inward to the bottom of the seedling tray or move outward to disengage from the bottom of the seedling tray through the chain rod B.

[0014] In some improved embodiments, a clamping positioning plate can be added to form a more stable clamping pair, a synchronous transmission mechanism can be set to achieve consistency of movement of the two end plates, and a height detection function can be integrated to achieve adaptive collision avoidance. These will further optimize the performance of the fixture.

[0015] Furthermore, at least one clamping positioning plate is fixedly installed on the fixed frame. The clamping positioning plate is arranged opposite to the clamping fixing plate. For example, the pair of clamping fixing plates on the left are arranged opposite to the clamping positioning plate on the right to facilitate clamping the seedling tray. Similarly, the pair of clamping fixing plates on the right are arranged opposite to the clamping positioning plate on the left to facilitate clamping the seedling tray. Together, they form a clamping pair for wrapping and locking the seedling tray from the side.

[0016] Optionally, the bottom end of the clamping positioning plate has an outwardly inclined guide slope to cooperate with the clamping positioning plate to achieve clamping.

[0017] Furthermore, the above summary does not enumerate all the features required for embodiments of the present invention, and other combinations of these feature groups may also constitute embodiments of the present invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the background art, the accompanying drawings used in the embodiments of the present invention or the background art will be described below.

[0019] Figure 1 This is a three-dimensional structural diagram of a clamp for rice seedling tray stacking provided in one embodiment of the present invention.

[0020] Figure 2 yes Figure 1 The diagram shows the front view of the fixture.

[0021] Figure 3 yes Figure 1 Top view of the fixture shown.

[0022] Figure 4 yes Figure 1 Side view of the fixture shown.

[0023] Figure 5 yes Figure 4A cross-sectional view of JJ.

[0024] Among them, 10 is the fixed frame; 20 is the first cylinder (cylinder A); 30 is the second cylinder (cylinder B); 40 is the end plate chain mechanism; 50 is the clamping chain mechanism; 51 is the chain A; 61 is the clamping fixing plate; 611 is the bevel section; 71 is the end plate; 711 is the lifting plate; 42 is the main drive arm; 43 is the driven arm; 41 is the chain B; 80 is the clamping positioning plate; 801 is the guide slope; 90 is the telescopic docking flange; and 100 is the height detection sensor. Detailed Implementation

[0025] To make the technical means, creative features, objectives and effects of the embodiments of the present invention easier to understand, the embodiments of the present invention are further described below in conjunction with the figures and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the embodiments of the present invention and are not intended to limit the embodiments of the present invention.

[0026] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal connection of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances. The terms "first," "second," "third," "fourth," etc. (if present) are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0027] In the description of the embodiments of the present invention, it should be noted that, unless otherwise stated, directional terms such as "up", "down", "left", "right", "inner", and "outer" generally refer to the direction shown in the accompanying drawings or the orientation of the component itself in its normal use state, and are only for the convenience of description and should not be construed as limiting the present invention.

[0028] To better understand the embodiments of the present invention, please refer to Figure 1 , Figure 2 As shown, an embodiment of the present invention provides a clamp for rice seedling tray stacking. The clamp mainly includes a fixed frame 10, a first cylinder (cylinder A) 20, a second cylinder (cylinder B) 30, an end plate chain mechanism 40, and a clamping chain mechanism 50.

[0029] In one feasible implementation, the fixed frame 10 serves as the supporting foundation for the entire fixture, forming a stable rigid frame. The first cylinder 20 and the second cylinder 30 are fixed to the upper or side portion of the fixed frame 10 via mounting flanges. In this embodiment, the first cylinder 20 is primarily used to drive the end plate chain linkage mechanism 40, while the second cylinder 30 is primarily used to drive the clamping chain linkage mechanism 50. It is understood that the number and arrangement of the cylinders can be adjusted according to power requirements.

[0030] In a specific embodiment, the clamping plate 61 is connected to the fixed frame 10 via a clamping chain mechanism 50. Specifically, the clamp also includes a chain A 51, which may be inverted E-shaped. Both ends of the chain A 51 are connected to the clamping plate 61 via hinge shafts, and the middle part of the chain A 51 is connected to the fixed frame 10 via a hinge shaft. The inner working surface of the clamping plate 61 may be provided with anti-slip textures or a rubber pad (not shown in the figure) to increase friction. Crucially, the bottom end of the clamping plate 61 is machined with an outwardly inclined chamfered portion 611. The inclination angle α of this chamfered portion 611 is preferably between 30° and 60°, for example, 45°. This angle range has been verified to provide sufficient guide ramp length while ensuring smooth insertion of the seedling tray, ensuring that even if the seedling tray slightly shifts during the descent of the clamping plate 61, it can be smoothly guided to the correct clamping position.

[0031] In a specific embodiment, the end plate 71 is connected to the fixed frame 10 via an end plate linkage mechanism 40. Specifically, the fixture also includes a linkage B 41 and a main drive arm 42. One end of the main drive arm 42 is hinged to the front end of the piston rod of the first cylinder 20, and the other end is hinged to one end of the linkage B 41. The other end of the linkage B 41 is hinged to the upper end of the end plate linkage mechanism 40. A lifting plate 711 extending horizontally inward (i.e., towards the center of the fixture) is welded or integrally formed on the bottom side of the end plate 71. The extension length L of the lifting plate 711 (i.e., the distance from the inner surface of the end plate 71 to its free end) is approximately 3 to 8 times the thickness of the target seedling tray bottom plate (typically 1-3 mm), for example, 10-15 mm. This length design ensures that it has sufficient "shovel-in" depth to reliably support the seedling tray without excessively interfering with the stacking of the seedling trays.

[0032] In this embodiment, when the piston rod of the first cylinder 20 retracts, it drives the main drive arm 42 to swing, which in turn pushes the entire end plate chain mechanism 40 through the chain rod B 41. The end plate chain mechanism 40 is connected to the fixed frame 10 through the hinge shaft. When the chain rod B 41 pushes, the upper end of the end plate chain mechanism 40 (the hinge point with the chain rod B 41) rotates away from the center of the clamp. At this time, the lower end of the end plate chain mechanism 40 rotates towards the center of the clamp. The end plate 71 and its lifting plate 711 move inward (tightening direction), "scooping in" from the bottom and supporting the edge of the lowest seedling tray. Simultaneously, the piston rod of the second cylinder 30 extends and drives the clamping chain mechanism 50. Since the chain A 51 is hinged to the fixed frame 10, as the piston rod of the second cylinder 30 pushes down, it pushes the clamping fixing plates 61 on both sides towards the center of the clamp via the chain A 51. Using their inner working surfaces and the guide angles 611 at the bottom, they clamp the sides of the seedling tray from both sides. The cylinder retracts to perform the releasing action. The above-mentioned end-plate action and clamping action are coordinated by the pneumatic control system and can be performed sequentially or synchronously.

[0033] In this embodiment, the end plate 71 and its lifting plate 711 provide bottom support for the seedling tray, fundamentally avoiding the direct compressive stress on the edge of the seedling tray caused by traditional side clamps, thus solving the core problem of seedling tray breakage. The lateral clamping and bottom support of the clamping and fixing plate 61 work together to form a three-dimensional constraint of "bottom support and top clamping," which significantly improves the stability of the seedling tray during high-speed transportation and effectively prevents misalignment and detachment. The design of the chamfered corner 611 significantly reduces the precision requirements for clamping and alignment, improving operational efficiency.

[0034] In another feasible implementation, based on the above embodiments, in order to achieve simultaneous and synchronous lifting of both ends of the seedling tray to improve the smoothness and efficiency of the action, this embodiment optimizes the end tray chain mechanism.

[0035] See Figure 1 As shown, in this embodiment, the fixture further includes a driven arm 43. The main driven arm 42 and the driven arm 43 are rotatably mounted on opposite ends (e.g., left and right sides) of the fixed frame 10 via a drive shaft. The drive shaft (e.g., a solid steel shaft or rod) passes through the fixed frame 10, and its two ends are rigidly connected to the main driven arm 42 and the driven arm 43 by key connection or welding, ensuring that there is no relative rotation between them.

[0036] In this embodiment, at least two sets of chain links B 41 are provided, and one pair of end plate chain links 40 are provided. One end of one set of chain links B 41 is hinged to the main drive arm 42, and the other end is hinged to the end plate chain link mechanism 40; one end of the other set of chain links B 41 is hinged to the driven arm 43, and the other end is hinged to another end plate chain link mechanism 40. The end plate 71 is installed at the lower end of the end plate chain link mechanism 40. The two end plate plates 71 and their lifting plates 711 are arranged symmetrically.

[0037] During operation, the first cylinder 20 drives the main drive arm 42 to swing, and the torque is instantly transmitted to the driven arm 43 through the rigidly connected drive shaft, causing it to swing synchronously and in the same direction. As a result, the chain rods B 41 on both sides and the end plate 71 achieve completely synchronized tightening or opening actions.

[0038] In this embodiment, a single drive shaft rigidly connects the master and slave drive arms, achieving absolutely synchronous movement on both sides under a single cylinder drive. This not only ensures high reliability of the synchronization method but also prevents it from being affected by air pressure fluctuations or control delays, ensuring the consistency of the movements of the two end plates 71. This results in uniform force distribution at both ends when the seedling tray is lifted, further improving the smoothness of the movement and the protection of the seedling tray. At the same time, this structure simplifies the control system and reduces costs.

[0039] Based on any of the above possible implementation methods, in order to achieve a more complete wrap-around positioning of the seedling tray and solve the guiding problem between the upper clamp and the lower seedling tray when multiple seedling trays are stacked, this embodiment adds a clamping positioning plate 80.

[0040] See Figure 1 As shown, a clamping positioning plate 80 is also fixedly installed on the inner side of the fixed frame 10. The clamping positioning plate 80 and the clamping fixing plate 61 are arranged opposite to each other. Together, they form a "clamping pair" for wrapping and locking the seedling tray from the side. For example, the clamping positioning plate 80 and the clamping fixing plate 61 are arranged opposite to each other. For example, the pair of clamping fixing plates 61 on the left side are arranged opposite to the clamping positioning plate 80 on the right side, which facilitates clamping the seedling tray. Similarly, the pair of clamping fixing plates 61 on the right side are arranged opposite to the clamping positioning plate 80 on the left side, which also facilitates clamping the seedling tray. Together, they form a clamping pair for wrapping and locking the seedling tray from the side.

[0041] Preferably, the bottom end of the clamping positioning plate 80 is also machined with an outwardly inclined guide slope 801, the inclination angle of which can be the same as or slightly different from the angle of the chamfered portion 611 of the clamping fixing plate 61, for example, in the range of 25° to 55°, together forming a "trumpet mouth" shaped inlet channel.

[0042] In one specific arrangement, the clamping fixing plate 61 on the left side of the clamp is opposite to the corresponding clamping positioning plate 80 on the right side; similarly, the clamping fixing plate 61 on the right side is opposite to the corresponding clamping positioning plate 80 on the left side, thereby achieving the enclosure of the four sides of the seedling tray.

[0043] Importantly, when the clamp is used to grip multiple stacked seedling trays, the inner surfaces of the upper clamping plate 61 and / or clamping positioning plate 80 will slide into contact with the outer edge of the adjacent lower seedling tray during descent. This contact serves as automatic guidance and prevents misalignment. Figure 2 As shown, assuming the Nth layer of seedling trays is being clamped, when the clamp descends, the inner side of its clamping and fixing plate 61 will slide down along the side of the (N-1)th layer of seedling trays, automatically correcting the relative position of the clamp and the pile of seedling trays, ensuring precise alignment, and fundamentally avoiding collisions or clamping failures caused by positional deviations.

[0044] In this embodiment, by setting the clamping positioning plate 80 to cooperate with the movable clamping fixing plate 61, a four-sided wrapping of the seedling tray is formed, resulting in a more uniform distribution of clamping force and more precise positioning. The fixed clamping positioning plate 80 provides a reliable reference surface. Its bottom guide slope 801 works in conjunction with the chamfered corner portion 611 of the clamping fixing plate 61, making the feeding process smoother. In addition, by utilizing the structure of the clamping execution component (clamping fixing plate) itself, a "self-guiding" function is realized in multi-layer operations, greatly improving the reliability of continuous, high-speed, and precise tray loading on automated production lines.

[0045] To address the collision problem caused by inconsistent stacking heights, this embodiment of the invention also provides a feasible implementation method, which integrates a height detection and adaptive mechanism into the fixture.

[0046] See Figure 2 As shown, a telescopic docking flange 90 and a height detection sensor 100 are provided on the top of the fixed frame 10. The telescopic docking flange 90 typically includes a mounting plate with a quick connector, and possibly a built-in buffer spring or cylinder for flexible connection with the lifting drive mechanism of the robotic arm or gantry (not shown), and allows the gripper to float within a small range to absorb the impact upon initial contact.

[0047] The height detection sensor 100 can be a contact limit switch, a photoelectric sensor, or an ultrasonic sensor. Figure 2 An example is a contact lever roller limit switch with its probe facing downwards.

[0048] The height detection sensor 100 is connected to the pneumatic control system of the clamp (the solenoid valves controlling cylinders 20 and 30) or the control system of the external robotic arm. Its control logic is as follows: When the robotic arm lowers the clamp as a whole to prepare to grab the seedling tray pile, the probe of the height detection sensor 100 will contact the uppermost surface of the seedling tray pile before the actuators (end plate 71, clamping plate 61). Once a contact signal is detected, the control system can immediately execute any or all of the following actions: 1) issue a command to stop the continued descent of the external lifting drive mechanism; 2) trigger the first cylinder 20 and the second cylinder 30 to begin clamping and end plate actions according to a predetermined program.

[0049] In this embodiment, by adding a height detection sensor 100, the clamp acquires "tactile" capabilities. It can detect the presence of the seedling tray pile before a hard collision occurs, and immediately stop its descent or begin gripping via the control system, completely avoiding collision accidents and protecting both the equipment and the seedling trays. Combined with the buffer function of the telescopic docking flange 90, the system's safety and fault tolerance are further enhanced. This allows the clamp to intelligently adapt to seedling tray piles of different heights, achieving truly flexible and automated operation.

[0050] To optimize the clamping action and ensure that the clamping plate 61 better fits and encloses the seedling tray during clamping, this invention also provides a feasible implementation method. Based on the structure in the aforementioned embodiments, by optimizing the hinge point position between the chain rod A 51, the fixed frame 10, and the clamping plate 61, when the second cylinder 30 drives the clamping chain rod mechanism 50, the movement trajectory of the clamping plate 61 is not a simple horizontal inward movement, but rather a composite trajectory that is downward and inclined inward. That is, while the clamping plate 61 moves closer to the seedling tray, its height also decreases slightly.

[0051] This trajectory allows the chamfered portion 611 of the clamping plate 61 to "slide" into the lower side of the seedling tray at a better angle, and at the final clamping position, the contact area between its inner working surface and the side of the seedling tray is larger, resulting in a more stable clamping.

[0052] In this embodiment, the downward-sloping clamping trajectory gives the clamping action a guiding and "pressing" tendency, which helps to eliminate the gap between the seedling tray and the clamp, making the clamping tighter and more secure. This optimized kinematic design further improves the success rate and stability of the clamping, especially for seedling trays with slight dimensional tolerances or slightly misaligned placement, providing greater fault tolerance.

[0053] To better understand the technical solution of this invention, several application scenarios are described below: In a specific application scenario, there is a rice seedling production line. At the end of the line, standard plastic seedling trays (length × width × height approximately 600mm × 300mm × 30mm) after sowing need to be removed from the conveyor belt and stacked on pallets, with 10 layers per stack.

[0054] When using the clamp of this invention, the fixing frame is mounted to the end of a six-axis robotic arm via a telescopic flange at its top. During operation, the robotic arm moves the clamp as a whole to a predetermined position above the seedling tray stack. The control system first activates the second cylinder, driving the clamping chain mechanism to open the clamping plates on both sides to a position slightly wider than the width of the seedling tray. Subsequently, the robotic arm moves the clamp vertically downward. During this process, the chamfered portion at the bottom of the clamping plate (with an inclination angle α set to 45°) first contacts the side of the seedling tray, providing initial guidance.

[0055] When the clamp descends to the set height (determined by a preset program or height detection sensor), the control system simultaneously activates the first and second cylinders. The first cylinder drives the end plate chain mechanism, causing the lifting plate (12mm extension length) at the bottom of the end plate to tighten inward, supporting the edge of the lowest seedling tray from the bottom. At the same time, the second cylinder drives the clamping chain mechanism, causing the clamping fixing plate to move inward, clamping the seedling tray from both sides. After completing the "bottom support and top clamping" operation, the robotic arm lifts the clamp and seedling tray, moves them above the tray, and then the cylinders reverse their movement, releasing the seedling tray and completing one tray stacking operation.

[0056] In another specific application scenario, the only difference from the above application scenario is the geometric parameters. The seedling tray specifications are: 400 mm × 200 mm × 25 mm (length × width × height).

[0057] Chamfered section 611: Inclination angle α = 30°, height 8 mm.

[0058] Lifting plate 711: Extension length L = 8 mm (approximately 2.7 times the thickness of the seedling tray bottom plate).

[0059] The action process is the same as the application scenario described above.

[0060] Experimental results: After 500 consecutive grasping cycles, the seedling tray breakage rate was 0%, the misalignment rate was 0.4%, and the average cycle time was 8.3 seconds.

[0061] In another specific application scenario, the only difference from the two application scenarios mentioned above is the geometric parameters. The seedling tray specifications are 700 mm × 350 mm × 35 mm.

[0062] Chamfered section 611: Inclination angle α = 60°, height 12 mm.

[0063] Lifting plate 711: Extension length L = 20 mm (approximately 5.7 times the thickness of the seedling tray bottom plate).

[0064] Experimental results: After 500 consecutive grasping cycles, the seedling tray breakage rate was 0%, the misalignment rate was 0.2%, and the average cycle time was 8.7 seconds.

[0065] The same cylinder pressure and operating speed as in the above application scenario are used, but the chamfered part 611 is changed to a right angle (α=90°), and the length of the lifting plate 711 is shortened to 3 mm (only the thickness of the base plate).

[0066] Experimental results: After 100 consecutive grabs, the seedling tray breakage rate was 15%, the misalignment rate was 6%, and there were 2 instances where the lifting plate failed to scoop in, resulting in the tray falling off.

[0067] Conclusion: A parameter range of 30°–60° for the chamfer and 8–20 mm for the lifting plate can significantly reduce breakage and misalignment.

[0068] In another specific application scenario, in order to quantitatively verify the superiority of the clamp of the present invention over the traditional side clamp, the following comparative experiment was conducted.

[0069] Experimental group: The fixture of Embodiment 1 of this invention was used.

[0070] Control group: Commonly available parallel pneumatic grippers (with cylinders on both sides directly gripping the long side of the seedling tray).

[0071] Experimental subjects: 100 standard plastic seedling trays of different ages (50 new trays and 50 aged trays that have been used more than 20 times).

[0072] Experimental conditions: On the same robotic arm, with the same running path and speed (1.5m / s), perform 1000 consecutive grab-transport-stacking cycles.

[0073] Evaluation metrics and results:

[0074] Data analysis: Experimental data clearly show that the clamp of this invention is significantly superior to traditional side clamps in protecting seedling trays (especially vulnerable aging trays), ensuring neat stacking, and improving work efficiency. Its "bottom lifting" method fundamentally avoids lateral compressive stress, which is the main reason for the significant reduction in breakage rate; while the "self-guiding" and four-sided constraint design are the key to the extremely low misalignment rate.

[0075] In another specific application scenario, such as Figure 1 , Figure 2As shown, in this fixture, the main drive arm 42 and the driven drive arm 43 are rigidly connected by a solid steel drive shaft that passes through the fixed frame 10. The main drive arm 42 is hinged to the piston rod of the first cylinder 20. One end of the chain rods B 41 on both sides is hinged to the main and driven drive arms 43 respectively, and the other end is hinged to their respective end plate chain rod mechanisms 40.

[0076] When the first cylinder 20 actuates, it drives the main drive arm 42 to rotate around its hinge point with the frame. Due to the rigid connection of the drive shaft, the rotation angle of the main drive arm 42 is transmitted to the driven arm 43 without delay or deviation, forcing the driven arm 43 to rotate in a completely synchronized manner. This synchronized rotation is converted into a completely synchronized tightening or opening motion of the two end plate chain mechanisms 40 and their lower end plate 71 through the chain links B 41 on both sides.

[0077] In this embodiment, the specific mechanical structure of "rigid connection" and "synchronous rotation" can be intuitively understood with reference to the accompanying drawings. This design ensures that both ends of the long side of the seedling tray are lifted completely synchronously, avoiding problems such as seedling tray tilting, stress concentration, or the inability of the lifting plate 711 to "shovel in" simultaneously due to asynchronous movements at both ends, greatly improving the reliability of the operation and the protection of the seedling tray.

[0078] In one possible application scenario, during actual seedling production, soil spillage on the sowing line or slight deformation of the seedling tray may cause the seedling trays to be stacked to be not in an ideal horizontal position on the tray, and may be tilted at a small angle (for example, one side is 3-5mm higher than the other).

[0079] When the clamp of the present invention is used to handle this situation, firstly, during the descent of the clamp, the chamfered portion 611 at the bottom of the clamping fixing plate 61 and / or the guide slope of the clamping positioning plate 61 will first contact the edge of the higher seedling tray. Under the action of the slope, the clamp will produce a slight adaptive deflection or absorb part of the offset through the buffer link of the telescopic docking flange 90, guiding the clamp to gradually align with the pile of seedling trays.

[0080] More importantly, when the lifting plate 711 of the end plate 71 performs the tightening action, because it is a flexible lift rather than a rigid impact, even if the seedling tray is tilted, the lifting plate 711 can first support the lower side through sliding contact, and as the cylinder continues to move, it will eventually lift the entire seedling tray smoothly. The clamping action of the clamping and fixing plate 61 also has a certain margin of error.

[0081] To verify this effect, a simulation test was conducted: the seedling trays were intentionally placed at a 5° tilt and gripped using the clamp of this invention. The results showed that in 100 attempts, the success rate of gripping and stacking reached 98%, and no jamming or collisions occurred due to misalignment.

[0082] In other specific application scenarios, the clamping technology of the present invention is not limited to the stacking of rice seedling trays. Its core concept of "bottom lifting + lateral clamping" can be extended to the non-destructive handling of other similar thin-walled boxes or discs.

[0083] For example, it can be used to move seedling trays in vegetable seedling factories; in the food industry, it can be used to move plastic trays containing pastries or eggs; and in the electronics industry, it can be used to move PCB boards or photovoltaic silicon wafer trays. Simply scale the dimensions of the fixture's frame, end plates, and clamping plates proportionally to the size and weight of the target object, and adjust the cylinder selection.

[0084] It should be understood that the terms "one embodiment," "an embodiment," "a feasible implementation," or "some implementations" used throughout the specification mean that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the present invention. Therefore, "one embodiment," "an embodiment," "a feasible implementation," or "some implementations" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also recognize that the embodiments described in the specification are optional embodiments, and the actions and modules involved are not necessarily essential to the embodiments of the present invention.

[0085] The above description is merely a specific embodiment of the present invention, but the protection scope of the embodiments of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included within the protection scope of the embodiments of the present invention. Therefore, the protection scope of the embodiments of the present invention should be determined by the protection scope of the claims.

Claims

1. A clamp for rice seedling tray stacking, comprising a fixed frame, a cylinder, an end-plate chain mechanism, and a clamping chain mechanism, wherein the cylinder is mounted on the fixed frame, characterized in that: A clamping fixing plate is connected to the clamping chain mechanism. The clamping fixing plate can be raised and lowered by the drive of the clamping chain mechanism, and has an outwardly inclined guide angle portion at its bottom end. An end plate is connected to the end plate chain mechanism. An inwardly extending lifting plate is provided on the bottom side of the end plate. The end plate can move with the drive of the end plate chain mechanism and cause the lifting plate to tighten inward. The end plate chain mechanism and the clamping chain mechanism are both connected to the cylinder drive. The cylinder can drive the clamping chain mechanism to drive the clamping fixing plate to perform clamping and loosening actions, and drive the end plate chain mechanism to drive the end plate plate to perform end plate actions.

2. The clamp for rice seedling tray stacking according to claim 1, characterized in that, It also includes a chain rod A, which is connected to the clamping plate and the fixed frame respectively. Under the action of the cylinder driving the clamping chain rod mechanism, the clamping chain rod mechanism can drive the clamping plate to move inward or outward through the chain rod A.

3. The clamp for rice seedling tray stacking according to claim 1, characterized in that, It also includes chain link B and main drive arm; One end of the main drive arm is connected to the drive end of the cylinder, and the other end of the main drive arm is connected to the chain rod B. When the cylinder drives the main drive arm to move, the main drive arm drives the end plate to move inward or outward through the chain rod B.

4. The clamp for rice seedling tray stacking according to claim 2, characterized in that, The cylinder drives the clamping chain mechanism to move downward and tilt inward.

5. The clamp for rice seedling tray stacking according to claim 3, characterized in that, It also includes a drive arm; The main drive arm and the driven arm are rotatably mounted on opposite ends of the fixed frame.

6. The clamp for rice seedling tray stacking according to claim 5, characterized in that, The main drive arm and the driven arm are rigidly connected by a drive shaft, so that when the cylinder drives the main drive arm, it can drive the driven arm to rotate synchronously through the drive shaft.

7. The clamp for rice seedling tray stacking according to claim 1 or 2, characterized in that, At least one clamping and positioning plate is also fixedly installed on the fixed frame; the clamping and positioning plate is arranged opposite to the clamping and fixing plate, and the two together form a clamping pair for wrapping and locking the seedling tray from the side.

8. The clamp for rice seedling tray stacking according to claim 7, characterized in that, The bottom end of the clamping and positioning plate has an outwardly inclined guide slope.

9. The clamp for rice seedling tray stacking according to claim 1 or 2, characterized in that, When the clamp is used to grip multiple stacked seedling trays, the inner surface of the clamping and fixing plate on the upper layer slides into contact with the outer edge of the adjacent lower seedling tray, which serves to guide and prevent misalignment.

10. The clamp for rice seedling tray stacking according to claim 1, characterized in that, It also includes a height detection sensor and a telescopic docking flange located on the top of the fixed frame; the telescopic docking flange is used to connect with an external lifting drive mechanism and drive the entire clamp to lift; the height detection sensor is set on the fixed frame and is used to detect the contact status with the seedling tray pile during the clamp's descent. The height detection sensor is connected to the pneumatic control system of the clamp or the control system of the external lifting drive mechanism. When the height detection sensor detects contact with the seedling tray pile, it sends a signal to trigger the cylinder to perform clamping and end plate actions, and / or control the external lifting drive mechanism to stop descending.

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