Liftable device for dry-wet alternate seedling of flue-cured tobacco

Abstract

The utility model belongs to but is not limited to the agricultural machinery technical field, especially relates to a kind of liftable device for flue-cured tobacco dry-wet alternate seedling, mainly by seedling facility unit module, lifting device module and track network system constitute.The seedling facility unit module adopts aluminium alloy perforated backing plate with quick detachable locking mechanism and integrated tooth group locking and double "X" type support of chrome plated light axle direction, and synchronous lifting (precision ±0.5mm) is realized by Φ40mm rigid synchronous shaft linkage.The lifting device module is driven worm wheel elevator by servo motor, and power is transmitted through cross torque distributor and four-bar linkage mechanism.The track network system integrates hydraulic support leg (synchronous precision ±0.2mm) and interference fit track, supports AGV automatic movement operation.The device monitors substrate water and fertilizer state by EC sensor, automatically controls seedling tray and nutrient solution contact-disengagement cycle, realizes accurate dry-wet alternate seedling, effectively improves seedling efficiency and automation level.

Description

Technical Field

[0001] This utility model belongs to, but is not limited to, the field of agricultural machinery technology, and particularly relates to a lifting device for alternating dry and wet seedling raising of flue-cured tobacco. Background Technology

[0002] The development of tobacco seedling roots directly affects the survival rate and recovery time after transplanting. A well-developed root system is a key foundation for high-quality tobacco production. Seedlings with well-developed root systems have a shorter recovery period after transplanting, a higher survival rate, and a lower rate of replanting in the field, significantly reducing labor and production costs. In the field, tobacco plants exhibit strong growth, high uniformity, and enhanced resistance to adverse conditions, resulting in good growth and development and ensuring both yield and quality of cured tobacco leaves.

[0003] To optimize root development, it is generally believed that alternating wet and dry seedling raising is a key measure to promote root development and improve the stress resistance of tobacco seedlings. Research on alternating wet and dry seedling raising methods has led to the development of the relatively mature and practical tidal seedling raising method, while some production areas use ground cover seedling raising (Hubei Province) as an alternative to seedling beds. Currently, floating seedling raising remains the main method in tobacco agricultural production. During the seedling stage (generally after 5 leaves), water and fertilizer are controlled to harden the seedlings, allowing them to adapt to the tobacco field environment in advance and enhancing their drought resistance and low-temperature tolerance in the field.

[0004] The above methods, through different approaches, achieve alternating wet and dry conditions to promote root development.

[0005] (1) Tidal Seedling Raising: The tidal seedling tray is designed with an integrated inlet and outlet design and intelligent irrigation timing control to achieve high-frequency switching of root "immersion-aeration". The essence of the technology lies in ensuring leaf dryness through bottom irrigation, strengthening root respiration through the ebb tide mechanism, and improving resource efficiency through closed circulation. Tidal seedling raising achieves dry and wet cycle through "bottom irrigation + timed drainage": Nutrient solution is injected into the seedling pool from the bottom inlet. The bottom of the seedling pool is designed with a grooved raised plate, on which seedling trays (floating seedling trays) are placed. After the nutrient solution enters the seedling pool, the seedling trays absorb water and nutrients. After the set time is reached, the outlet opens, and the nutrient solution is drained back to the storage tank by gravity for recycling. After drainage, the substrate of the seedling tray enters the air, providing oxygen to the roots and preventing root rot caused by lack of air. It achieves water and fertilizer supply guarantee during the wet period and oxygen exchange during the dry period, forming a dynamic balance of irrigation and aeration, which significantly improves root vitality and nutrient utilization.

[0006] The seedling pools for tidal seedling raising are raised above the ground. Seedbeds are built first in the seed shed. The frame structure of the seedling pools is designed on the seedbeds according to the technical standards for tobacco production. The main functions of the seedbeds are to bear weight and facilitate overall movement for easy operation.

[0007] (2) Floating seedling raising: After sowing in seedling trays, the seedling trays are placed in seedling pools. The seedling pools are built on the surface of the seedling shed. The appropriate depth and width are dug according to the technical standards for tobacco production.

[0008] (3) Ground seedling raising: No seedling ponds are dug in the seedling shed. Seedling trays are laid directly on the ground, and the ground is covered with a material that has good water absorption and water retention.

[0009] The above methods all employ different approaches to achieve the effect of alternating wet and dry seedling cultivation. From a practical production perspective, tidal seedling cultivation and ground cover seedling cultivation (moist seedling cultivation) result in the best root development. However, ground cover seedling cultivation (moist seedling cultivation) is limited by current production methods, resulting in higher labor costs and its application only in small areas, making large-scale promotion difficult. Currently, floating seedling cultivation is the main method in tobacco production, while tidal seedling cultivation, as a new type of seedling cultivation, is receiving increasing attention. Combining floating and tidal seedling cultivation, floating seedling cultivation is limited by the conditions of the seedling bed facilities. In the early stages, the seedling trays are constantly immersed in nutrient solution, and water and fertilizer are controlled only in the later stages of seedling development and before transplanting. This involves directly draining water and fertilizer from the seedling bed and cutting off water and fertilizer in the seedling bed for hardening off, resulting in poor hardening-off effects, especially in dry or cold weather. This leads to low survival rates and a long recovery period after transplanting.

[0010] Tidal seedling raising, as a novel seedling raising method, creates favorable conditions for tobacco seedling root development through frequent alternation of wet and dry conditions. By designing an intelligent water and fertilizer supply mode at the inlet, the seedling trays are soaked in the nutrient solution, and after the seedling substrate absorbs water and fertilizer, the drain valve is opened, allowing the nutrient solution to flow back into the water and fertilizer tank for recycling. However, due to cost constraints, the water outlet module of tidal seedling raising is not fully intelligent, and manual operation presents the following problems: personnel need to be assigned to observe the substrate's water and fertilizer absorption; after the substrate's water and fertilizer needs are met, each drain valve needs to be opened manually. Furthermore, to ensure seamless arrangement between seedling trays and meet the requirements for the installation and arrangement of return water and fertilizer pipes, the drain valves are often installed at the bottom of the seedling trays, making operation quite difficult. This step is labor-intensive and time-consuming, thus posing a challenge to large-scale production and promotion.

[0011] Meanwhile, current seedling cultivation facilities are mainly based on floating seedling cultivation, with seedling ponds arranged on the ground. Under current production conditions, it is difficult to achieve frequent alternating wet and dry seedling cultivation, resulting in a need to improve the quality of the produced tobacco seedlings. The main limiting factor is the drainage process, but due to the cost of facility construction, it is difficult to abandon the current seedling cultivation facilities in the short term until a mature and suitable alternative is available. Therefore, developing a device that can be used for both tidal seedling cultivation, reducing the labor costs of drainage in tidal seedling cultivation and increasing its application value, and floating seedling cultivation, solving the problem of the lack of drainage conditions in floating seedling cultivation and the inability to achieve true wet and dry alternation, is of great production significance.

[0012] Based on the above analysis, the urgent technical problems that need to be solved by the existing technology are as follows: the current seedling facilities are mainly based on floating seedling cultivation, with seedling ponds arranged on the ground. Under the current production conditions, it is difficult to achieve frequent alternating dry and wet seedling cultivation, resulting in the need to improve the quality of the tobacco seedlings produced. The main limiting factor is the drainage process. However, due to the cost of facility construction, it is difficult to abandon the current seedling facilities in the short term before a mature alternative facility is available. Utility Model Content

[0013] To address the problems of existing technologies, this utility model provides a lifting device for alternating wet and dry seedling raising of flue-cured tobacco. After sowing, the seedling trays are placed on the device, and water and fertilizer sensors are inserted into the trays. When the water and fertilizer content in the substrate reaches a predetermined upper limit, the sensors issue a prompt, activating the lifting device to lift the trays away from the nutrient solution. After leaving the nutrient solution, when the water and fertilizer content reaches a predetermined lower limit, the sensors issue a prompt, activating the lifting device again, and the trays return to the nutrient solution. Using this device, firstly, the nutrient solution level in the trays is ensured to be uniform. Simultaneously, sensor monitoring ensures a reasonable supply of water and fertilizer during seedling raising, reducing variability caused by manual experience-based operations, and guaranteeing uniform emergence and growth. This provides a fundamental guarantee for the uniform growth and development of tobacco seedlings after transplanting to the field, the uniformity of field management, and the uniformity of tobacco leaf ripening and yellowing.

[0014] This utility model is implemented as follows: a lifting device for alternating wet and dry tobacco seedling raising, comprising: a seedling facility unit module, a central drive module, and a track network system;

[0015] The utility model seedling facility unit module includes a seedling unit frame, a seedling tray plate, and a rigid synchronous shaft linkage system, which is used to support the seedling tray and realize lifting and lowering.

[0016] The utility model's central drive module includes a mobile base, a lifting mechanism, and a control system, which drive the seedling facility unit modules to rise and fall.

[0017] The utility model track network system consists of a main track, branch tracks, and AGV transport units, supporting the movement of the device within the seed shed;

[0018] The utility model device monitors the substrate moisture content through a water and fertilizer sensor, triggering a lifting mechanism to detach the seedling tray from or immerse it in nutrient solution, thus achieving alternating wet and dry seedling cultivation.

[0019] Furthermore, the utility model seedling facility unit module includes: seedling tray plate: made of 5052 aluminum alloy perforated plate, with 5mm diameter drainage holes evenly distributed on the plate surface, effective drainage area ≥35%, specifications 2000×1000×2.5mm, ultimate load ≥600kg, surface with diamond anti-slip texture (depth 0.3~0.5mm, spacing 10mm), and four corners integrated with M8 quick-release pin locking mechanism;

[0020] Seedling unit support frame: It consists of a horizontal 304 stainless steel square tube welded frame (2000×1000×500mm) and a vertical "X"-shaped cross support frame; the utility model "X"-shaped support frame is a double cross arm structure (wall thickness 2.5mm, included angle 30°~45°), and synchronous lifting is achieved through a four-bar linkage mechanism. The bottom is equipped with a sliding groove-tooth block self-locking mechanism (resistance to displacement force ≥8kN);

[0021] Rigid synchronous shaft linkage system: Two sets of seedling racks are connected by a Φ40mm / 42CrMo synchronous shaft and forced to synchronize by a cross torque distributor (error ≤ ±0.5mm). The linkage lifting stroke is 100mm.

[0022] Furthermore, the utility model cross torque distributor adopts an SWP type split fork head structure and is linked to the seedling frame through a Φ40mm / 42CrMo rigid synchronous shaft;

[0023] The utility model four-bar linkage consists of a frame, crank, connecting rod and rocker arm. The crank is connected to the output end of the cross torque distributor via a key, which converts the rotational motion into lifting displacement.

[0024] Furthermore, the utility model's center drive module includes: a mobile base: a 304 stainless steel frame (rated load capacity 1 ton), equipped with omnidirectional wheels, hydraulic outriggers (leveling accuracy ±2°), and ball joints (compensating for ±3° deflection angle); a lifting mechanism: adopting an SWL5 type worm gear lift (load 500kg / stroke 100mm), with a 750W waterproof servo motor (IP67) connected to the drive end, and lifting is achieved through a telescopic arm guide system; a telescopic arm guide system: consisting of 6 Φ20mm chrome-plated optical shafts (hardness HRC). 58-62) Circumferentially symmetrically distributed, with the bottom fixed to the base and the top floating with a 0.2-0.4mm expansion gap reserved; the optical axis and the plasma nitriding groove (hardness ≥ HV800) form a 20° tilt sliding pair to decompose the radial load; control system: based on the XC7Z020 chip, it coordinates the magnetostrictive displacement sensor (accuracy ±0.01mm), servo driver and water and fertilizer sensor through the EtherCAT bus; when the tilt angle > 0.3° or the synchronization error > 0.5mm, differential compensation and self-locking are triggered.

[0025] Furthermore, the utility model water and fertilizer sensor is a four-electrode EC sensor (accuracy ±0.3mS / cm, IP68 waterproof), with a threshold setting to control the raising and lowering: when the EC value is lower than the lower limit, the seedling tray is lowered to the bottom of the substrate and 50±1mm from the liquid surface; when the EC value is higher than the upper limit, the seedling tray is raised to the bottom and 200±2mm above the liquid surface.

[0026] Furthermore, the utility model track network system includes: main track and branch tracks: 6063-T5 aluminum alloy profile (section 80mm×40mm, load capacity ≥200kg / m), the branch tracks achieve 90° lateral switching through Φ300mm slewing bearing (rated load ≥2.5 tons); composite safety components: buffer baffle (buffer stroke 50mm, kinetic energy absorption rate ≥85%) and laser emergency stop sensor (detection distance 0.1-3m) are installed at the end of the track; AGV transport unit: integrated alloy steel base frame, drive chassis (750W servo motor), hydraulic support feet (10kN / set, response time 1.8 seconds) and screw lifting mechanism (stroke 100mm); the utility model hydraulic support feet work in coordination with the drive wheel set, locking the load when stopped and retracting when moving; the wheel flange of the utility model drive wheel set forms an interference fit with the track (tolerance ±0.2mm), and the positioning accuracy reaches the centimeter level.

[0027] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this utility model are as follows:

[0028] This invention provides a lifting device suitable for both ordinary seedbeds and tidal seedling beds. After sowing, the seedling trays are placed on the device, and water and fertilizer sensors are inserted into the trays. When the water and fertilizer content in the substrate reaches a predetermined upper limit, the sensors issue a prompt, activating the lifting device to lift the trays away from the water and fertilizer solution. After the trays are removed from the nutrient solution, when the water and fertilizer content reaches a predetermined lower limit, the sensors issue a prompt, activating the lifting device again, and the trays return to the nutrient solution. Using this device, firstly, it ensures a uniform nutrient solution level in the seedling trays. Secondly, through sensor monitoring, it ensures a reasonable supply of water and fertilizer during the seedling stage, reducing the variability caused by manual experience-based operations, and ensuring uniform emergence and growth. This provides a fundamental guarantee for the uniform growth and development of tobacco seedlings after transplanting to the field, the uniformity of field management, and the uniformity of tobacco leaf ripening and yellowing.

[0029] This utility model mainly consists of three parts: a seedling facility unit module, a central drive module, and a track network system. The seedling facility unit module comprises a seedling unit frame, a seedling tray support, and a rigid synchronous shaft linkage. The unit module uses seedling ponds as units, constructing a seedling tray placement and support lifting device to complete the seedling tray lifting function. The seedling unit frame is connected to the central drive mechanism via a cross torque distributor to realize the lifting process of the seedling trays. The central drive module includes a moving base, a lifting module, and a control system. The moving base is equipped with universal wheels and hydraulic outriggers, achieving ±2° leveling accuracy. The lifting module uses an SWL5 type worm gear lift (500kg load / 100mm stroke), coupled with a 750W waterproof servo motor and a chrome-plated optical shaft guide system. The control system integrates an XC7Z020 chip, supports EtherCAT bus control, and achieves a mechanical limit accuracy of ±1mm. The track network system consists of a main track and branch tracks, which are hinged via a turntable to achieve AGV lateral movement. Buffer plates and laser emergency stop sensors are installed at the ends of the tracks. The AGV integrates a worm gear lift, and hydraulic outriggers ensure operational stability. The system supports EtherCAT bus synchronous control, with a single lifting time of ≤8 seconds, and features automatic failover to a backup AGV.

[0030] By installing this device in the seedbed, the production technology requirements for robust seedling cultivation can be met, and production goals can be achieved simply by adding the device without altering the existing facilities. Furthermore, this device can also be used for seedling cultivation of other crops, improving the utilization rate of the seed shed during idle periods and achieving the goal of improving quality and efficiency. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall structure of the seedling rack lifting device provided in this embodiment of the utility model;

[0032] Figure 2 This is a schematic diagram of the seedling unit support structure provided in this embodiment of the utility model;

[0033] Figure 3 This is a schematic diagram of the seedling tray structure provided in this embodiment of the utility model;

[0034] Figure 4 This is a schematic diagram of the rigid synchronous shaft linkage system provided in this embodiment of the utility model;

[0035] Figure 5 This is a schematic diagram of the lifting device module structure provided in this embodiment of the utility model;

[0036] Figure 6 This is a schematic diagram of the track network system structure provided in an embodiment of the present invention;

[0037] Figure 7This is a diagram showing the survey results of agronomic traits of tobacco seedlings under two seedling raising methods provided in this embodiment of the utility model;

[0038] Figure 8 This is a graph showing the difference in dry matter accumulation of tobacco seedlings between two seedling raising methods provided in this embodiment of the utility model.

[0039] Figure 9 These are diagrams illustrating the developmental changes of tobacco seedlings under two different seedling raising methods provided in this embodiment of the invention.

[0040] Figure 10 This is a graph showing the seedling stage index measurement results for two seedling raising methods provided in this embodiment of the utility model;

[0041] Figure 11 These are comparison images of transplanted tobacco seedlings provided in this embodiment of the utility model;

[0042] In the diagram: 1. Seedling tray support frame; 2. Pin shaft; 3. Double "X" crossarm; 4. M16 bolt; 5. Flange; 6. Gear locking mechanism; 7. Track groove; 8. End of bottom support; 9. Hardened gear block; 10. Seedling tray; 11. Perforated plate drainage hole; 12. Edge drainage groove; 13. Folded edge; 14. Seedling tray; 15. Water and fertilizer sensor; 16. First "X" type support frame; 17. Second "X" type support frame; 18. Synchronous shaft and four-bar linkage 19. Hinge joint; 20. Four-bar linkage; 21. Rigid synchronous shaft A section; 22. Rigid synchronous shaft B section; 23. First seedling tray frame; 24. Second seedling tray frame; 25. SWL5 type worm gear lift; 26. Cross torque distributor; 27. Telescopic arm top flange structure; 28. Telescopic arm guide; 29. ​​Servo motor; 30. Base frame structure; 31. Hydraulic support leg; 32. AVG guide rail; 33. Wheel; 34. Ground track. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model.

[0044] like Figure 1 As shown, this utility model discloses a lifting device for alternating wet and dry seedling cultivation of flue-cured tobacco, particularly suitable for lifting seedling trays during seedling cultivation in seed sheds. It achieves a seedling cultivation method of alternating wet and dry conditions by regulating the contact and separation between the seedling trays and the nutrient solution through the control of the moisture and nutrient content of the seedling substrate. This device mainly consists of three parts: a seedling facility unit module, a lifting device module, and a track network system.

[0045] In some embodiments, such as Figure 2 , Figure 3 and Figure 4 As shown in the figure, the seedling-raising facility unit module mainly consists of a horizontal seedling tray support frame 1, a vertical "X"-shaped telescopic frame 3, a seedling-raising pallet 10 and a seedling-raising pallet 10. The horizontal seedling tray support frame is connected to the seedling-raising pallet through a pin shaft 2. The vertical "X"-shaped telescopic frame is rigidly welded to the bottom of the seedling tray support frame, and the seedling tray 14 is placed on the seedling-raising pallet supported by the seedling tray support frame. Two groups of seedling-raising unit modules are connected by a rigid synchronous shaft. The two ends of the synchronous shaft are connected by a vertical "X"-shaped bracket cross hinge cross torque and then linked synchronously.

[0046] The driving force of the lifting machine 24 is transmitted to the rigid synchronous shaft through the four-bar linkage 19, lifting the seedling tray racks 22 and 23 synchronously out of the liquid surface. The bottom bracket end 8 of the vertical "X" support frame moves in the track chute 7 and reaches the tooth group locking mechanism 6. The quenched tooth block 9 locks the bracket, and the seedling tray rack is stationary. The middle part of the synchronous shaft is hinged to the four-bar linkage through the hinge connection 18 to achieve the synchronous lifting of the two seedling-raising units. After the water and fertilizer sensor 15 triggers the descending command, the seedling tray descends into the nutrient solution, and the bottom of the substrate is 50±1 mm from the liquid surface; when it is higher than the upper limit, it is lifted, and the bottom of the seedling tray is 200±2 mm above the liquid surface.

[0047] The seedling tray pallet is made of 5052 aluminum alloy perforated plate. The plate surface is evenly distributed with drainage holes with a diameter of 5 mm in a staggered array, and the effective drainage area is ≥35%. The specifications of the pallet are 2000×1000×2.5 mm (the ultimate load ≥600 kg), and the bearing surface is treated with diamond-shaped convex anti-slip patterns (depth 0.3 - 0.5 mm, spacing 10 mm). The perforated area ratio is ≤50%, and a drainage groove with a depth of 10 mm and a width of 15 mm is designed at the edge. 90° vertical flanges with a height of 15 mm are set at the four corners for reinforcement. Quick-release plug locking mechanisms (M8 standard interface) are integrated at the four corners of the pallet. Rotating 90° realizes locking or releasing, and is compatible with different seedling pond support frames.

[0048] The seedling-raising unit support frame is divided into a horizontal support frame and a vertical support frame:

[0049] The horizontal support frame is a welded skeleton made of 304 stainless steel square tubes, with dimensions of 2000×1000×500 mm, a load capacity of 500 kg, and a "field" - shaped structure to support the seedling tray.

[0050] The vertical support frame adopts a double "X" cross-arm design (cold-rolled 304 stainless steel, wall thickness 2.5 mm, yield strength ≥205 MPa):

[0051] The two arms cross at an angle of 30° - 45°, and are hinged by a Φ18 mm / 42CrMoA alloy steel pin shaft (allowing ±5° dynamic deflection), and a spherical hinge joint is added to compensate for the ±2° installation error.

[0052] The bottom support end is equipped with an adjustable tooth locking mechanism 6: trapezoidal tooth blocks (pressure angle 30°, tooth pitch 10mm) mesh with the slide groove, with a meshing depth of 4.5±0.2mm, single tooth shear strength ≥1200MPa (quenched HRC45-50), and displacement resistance ≥8kN.

[0053] The horizontal force is decomposed by the Φ20mm chrome-plated optical axis guide system 28 (HRC58-62); the chute is a double-track inclined chute (cold-rolled 304 stainless steel base + plasma nitriding treatment, hardness ≥HV800), with a width of 22±0.1mm and an inclination angle of 20°.

[0054] The rigid synchronous shaft linkage system links two sets of seedling racks via a Φ40mm / 42CrMo rigid synchronous shaft (shaft length 500mm):

[0055] One end of the synchronous shaft is connected to the movable hinge point of the "X"-shaped bracket of the seedling rack, and the other end is connected to the lifting device via a cross torque distributor to achieve a 100mm stroke lifting (synchronization error ≤ ±0.5mm).

[0056] The cross torque distributor adopts an SWP type split fork head structure (standardized commercial part), eliminating the traditional four-end journal and needle roller bearing. It uses a Φ40mm rigid synchronous shaft to rigidly link two sets of seedling frames, converting variable angle transmission into pure torque distribution.

[0057] Lifting Drive: A servo motor with an integrated harmonic reducer drives a four-bar linkage (including crank, rocker, connecting rod, and frame), moving according to Grachoff's theorem regarding rod length conditions. The crank is connected to the vertical output port of a cross-shaped torque distributor via a key, pushing the connecting rod to convert rotation into displacement, which in turn drives the rocker to swing and transmit lifting torque.

[0058] In some embodiments, such as Figure 5 As shown, the lifting device module consists of an SWL5 type worm gear lift 24, a servo motor 29, a telescopic arm 27, a telescopic arm guide 28, a cross torque distributor 25, and a four-bar linkage 19.

[0059] The water and fertilizer sensor 31 senses changes in moisture and EC value by being inserted into the seedling tray 14. When the target value (high value) in the substrate is reached, the sensor sends a signal to the control system (XC7Z020) chip via the EtherCAT bus. The chip then issues a command to start the servo motor, which outputs power to the worm gear lift. The lift's telescopic arm, guided by the telescopic arm, outputs a vertical upward force. The top of the telescopic arm transmits the power to the crank end of the four-bar linkage via a cross torque distributor. The end of the four-bar linkage is hinged to the center of the synchronous shaft, which then transmits the power to the seedling tray frame, thus realizing the operation of lifting the seedling frame.

[0060] In some embodiments, such as Figure 6As shown, the track network system includes a track structure 34 and an AGV transport unit 32. The AGV transport unit consists of a base frame structure 30, hydraulic support legs 31, and a drive system. The AGV is the core unit for the lifting device's transport, including the balanced movement of the lifting device on the base 30 and the precise movement of the base and lifting device along the track within the seedling shed. This enables the automatic lowering of the seedling rack to the next set of racks after the lifting operation is completed, saving labor and manpower.

[0061] The base frame structure is a cuboid welded from alloy steel, integrating a drive chassis, guide rail 32, and hydraulic support legs 31.

[0062] Base frame structure 30: a welded cuboid of alloy steel, integrating a drive chassis, guide rail 32, and hydraulic support legs 31. The guide rail is a hardened alloy steel concave track with a gauge tolerance of ±0.2mm, and is interference-fitted with the wheel 33.

[0063] Hydraulic support leg 31: 4 sets of 10kN support feet, EtherCAT bus control (delay ≤1ms), load locking within 1.8 seconds, synchronization accuracy ±0.2mm.

[0064] Drive system: 750W servo motor drives the wheel mechanism, the wheel flange groove is interference fit with the ground track 34 (tolerance ±0.2mm), and the load capacity is ≥2.5 tons.

[0065] The top track 32 of the base is made of 6063-T5 aluminum alloy profile (80mm×40mm cross-section), with a straight load-bearing capacity of ≥200kg / m, and a composite safety component (density ≥1.2g / cm³) at the end. 3 (Buffer baffle + SICK ML100-8 laser emergency stop sensor).

[0066] Ground track 34: The 90° switching turntable is hinged by a Φ300mm slewing bearing and driven by a 750W servo motor (20-bit encoder), with a response time of <50ms.

[0067] The control system master and slave stations both adopt EtherCAT (CoE mode) and support CiA402 line specifications to achieve real-time communication and multi-axis collaborative control.

[0068] A lifting device for alternating wet and dry tobacco seedling cultivation mainly consists of three parts: a seedling facility unit module, a central drive module, and a track network system. The seedling facility unit module comprises a seedling unit frame, a seedling tray support, and a rigid synchronous shaft linkage. The unit module uses seedling beds as units, constructing a structure to hold seedling trays and support the lifting device to achieve the tray lifting function. The seedling unit frame is connected to the central drive mechanism via a cross torque distributor to realize the lifting process of the seedling trays. The central drive module includes a moving base, a lifting module, and a control system. The moving base is equipped with universal wheels and hydraulic outriggers, achieving ±2° leveling accuracy. The lifting module uses an SWL5 type worm gear lift (500kg load / 100mm stroke), coupled with a 750W waterproof servo motor and a chrome-plated optical shaft guide system. The control system integrates an XC7Z020 chip, supports EtherCAT bus control, and achieves a mechanical limit accuracy of ±1mm. The track network system consists of a main track and branch tracks, which are hinged via a turntable to achieve lateral movement of the AGV. The track end is equipped with a buffer baffle and a laser emergency stop sensor. The AGV integrates a worm gear lift, and hydraulic outriggers ensure operational stability. The system supports EtherCAT bus synchronous control, with a single lifting time of ≤8 seconds, and features automatic fault switching to a backup AGV.

[0069] By installing this device in the seedbed, the production technology requirements for robust seedling cultivation can be met, and production goals can be achieved simply by adding the device without altering the existing facilities. Furthermore, this device can also be used for seedling cultivation of other crops, improving the utilization rate of the seed shed during idle periods and achieving the goal of improving quality and efficiency.

[0070] Example 1: The seedling facility unit module consists of a seedling tray, a seedling unit support, and a rigid synchronous shaft linkage system.

[0071] The seedling tray is made of 5052 aluminum alloy perforated plate with 5mm diameter drainage holes evenly distributed on the surface in an alternating array, with an effective drainage area of ​​≥35%. The tray size is 2000×1000×2.5mm (ultimate load ≥600kg), and the load-bearing surface is treated with anti-slip texture.

[0072] The perforated area accounts for ≤50%, and the edge of the board is designed with drainage grooves (10mm deep × 15mm wide). The pallet is reinforced with a 15mm high 90° vertical flange around its perimeter. The anti-slip texture is 0.3~0.5mm deep, with a diamond-shaped raised pattern (10mm spacing).

[0073] The tray features a quick-release pin locking mechanism at each of its four corners, which can be locked or released by rotating 90°. The M8 standard interface is compatible with different seedling pond support frames.

[0074] The seedling-raising unit support is composed of a horizontal support frame and a vertical support frame. The horizontal support frame is made of a welded skeleton of 304 stainless steel square tubes, with dimensions of length × width × height

[0075] = 2000×1000×500 mm, which is adapted to the seedling pond (needs to match a 500 kg load). The overall frame is in a "field" shape structure and is mainly used to assist in supporting the seedling trays. The vertical support frame is designed with an "X"-shaped cross structure support

[0076] The "X"-shaped support is a double "X" cross arm with a wall thickness of 2.5 mm (cold-rolled 304 stainless steel, yield strength ≥ 205 MPa). The two arms are cross-fixed at an angle of 30° - 45° to form a stable triangular mechanical transmission path, and the synchronous lifting (stroke 100 mm) is achieved through the four-bar linkage mechanism 19, which is driven by a servo motor 29 with an integrated harmonic reducer. The intersection point is articulated by a high-strength pin shaft (Φ18 mm / 42CrMoA alloy steel pin shaft), allowing a dynamic deflection compensation of ±5°. A spherical hinge joint is added to compensate for an installation error of ±2°. An adjustable tooth group locking mechanism 6 is provided at the end of the bottom support, and self-locking is achieved through the engagement of the chute 7 and the tooth block 9 (anti-displacement force ≥ 8 kN), and the horizontal force is decomposed through a chrome-plated optical axis guiding system 28 (Φ20 mm / HRC58 - 62).

[0077] The main structure of the chute adopts a double-track inclined slideway structure, and a cold-rolled 304 stainless steel matrix and surface plasma nitriding treatment (hardness ≥ HV800) are selected. The width is 22 ± 0.1 mm (adapted to a Φ20 mm chrome-plated optical axis), and a 20° inclination angle is designed (the optimal angle for anti-horizontal displacement). The tooth block engagement system consists of trapezoidal teeth (pressure angle 30°) with a tooth pitch of 10 mm. The engagement depth is 4.5 ± 0.2 mm (anti-unhooking design), and the shear strength of a single tooth is ≥ 1200 MPa (quenched HRC45 - 50).

[0078] The rigid synchronous shaft linkage system 20, 21 is composed of a synchronous shaft made of 42CrMo alloy material with a diameter of 40 mm. The shaft length is equal to the spacing of the seedling racks (500 mm). One end of the rigid synchronous shaft 20 is connected to the movable end (articulation point) of the "X"-shaped support of the seedling rack, and the other end is connected to the lifting device 24 through a cross torque distributor 25

[0079] The rigid synchronous shaft linkage drives 2 groups of seedling racks through a Φ40 mm rigid synchronous shaft (42CrMo). The synchronous shaft spacing is 500 mm, the lifting stroke is 100 mm, and the synchronous error ≤ ±0.5 mm. A working process of "rigid synchronous shaft → cross torque distributor → movable hinge point of the 'X'-shaped support of seedling racks A / B" is formed

[0080] The connection between the horizontal support frame, the vertical X-shaped support frame, and the cross torque distributor is as follows: Horizontal support frame A and the seedling trays on its tray, and horizontal support frame B and the seedling trays on its tray, are connected via the cross torque distributor and a rigid synchronous shaft. Under the action of the lifting mechanism, the two sets of seedling trays rise and reach a static support state after leaving the liquid surface. The lifting system then moves to the next set of seedling tray frames for operation. After the EC sensor triggers the descent function, the seedling tray frames descend into the nutrient solution to a static support state.

[0081] The cross torque distributor adopts an SWP-type split fork head structure, which is a simplified design optimized from the traditional cross shaft: it retains two shaft interfaces and eliminates the traditional four-end journal and needle roller bearing structure. It links two sets of seedling racks through a Φ40mm / 42CrMo rigid synchronous shaft (500mm spacing), focusing on torque distribution to achieve forced rigid synchronization (error ≤ ±0.5mm), transforming variable angle transmission into pure torque distribution and mechanical synchronization. The cross torque distributor is installed at the top movable hinge point of the "X"-shaped bracket, with one end connected to the output end of the telescopic arm, and the other end linked to the adjacent seedling rack through the Φ40mm rigid synchronous shaft.

[0082] The cross torque distributor adopts a standardized SWP-type split fork head structure (a mature commercial component with a complete model system and supply chain). It achieves a synchronization accuracy of ≤±0.5mm by rigidly linking two seedling racks spaced 500mm apart via a Φ40mm / 42CrMo rigid synchronous shaft. This design is compatible with the mechanical path of an "X"-shaped support and, combined with a four-bar linkage, completes a 100mm stroke lifting motion. Users can directly select and purchase the SWP fork head assembly based on parameters such as torque capacity and rotation diameter.

[0083] The four-bar linkage is a basic mechanical transmission device composed of four rigid hinged components: a crank, a rocker arm, a connecting rod, and a frame. Its motion principle is based on Grahoff's theorem, which states that the sum of the lengths of the shortest and longest links must be less than or equal to the sum of the lengths of the remaining two links. This allows for crank-rocker, double-crank, or double-rocker motions. Four-bar linkages are highly standardized in industry. Due to their mature design and reliable structure, several professional manufacturers (such as SMC and Festo) offer modular four-bar linkage components that can be directly integrated into customized systems.

[0084] The four-bar linkage consists of four rigid links—a frame, a crank, a connecting rod, and a rocker arm—connected by four revolute joints (hinge points) to form a closed planar quadrilateral mechanism. The frame is fixed to the base. The crank serves as the power input, connecting to the telescopic arm's output and the vertical output of the cross-shaped torque distributor via a key, driving the crank to rotate. The crank pushes the connecting rod in a planar compound motion, converting rotation into a specific trajectory displacement. The connecting rod drives the rocker arm to oscillate back and forth around the frame's hinge points, with its end hinged to the center of a synchronous shaft via a spherical bearing, transmitting lifting torque.

[0085] Example 2: The lifting device module consists of a base, a lifting device, a control system, and a water and fertilizer sensor.

[0086] The base is made of 304 stainless steel frame (rated load capacity 1 ton), with elastic pads installed (allowing ±5mm displacement), and the levelness after leveling is ≤0.5°. The center load-bearing (Φ120mm) rigid connection drive unit is equipped with ball joints to compensate for ±3° deflection angle.

[0087] The lifting module uses an SWL5 type worm gear lift with a rated load of 500kg and a stroke of 100mm. It is equipped with a waterproof servo motor and the lifting device moves precisely guided by a telescopic arm.

[0088] The waterproof servo motor is a 750W IP67 waterproof motor controlled by an EtherCAT bus. This forms the operational flow of "servo motor → worm gear lift → telescopic boom → cross torque distributor".

[0089] The telescopic arm guide is a core component in the lifting device that ensures motion accuracy. Its core structure consists of six chrome-plated optical shafts (hardness HRC58-62) with a diameter of 20mm, requiring a straightness of ≤0.02mm / m to form a high-precision linear guide system. The chrome plating thickness of the optical shafts is ≥0.05mm, and the hardness of the plasma-nitrided grooves is ≥HV800.

[0090] The six chrome-plated optical shafts are crucial components of the anti-deviation mechanism in the lifting device. These shafts are vertically distributed equidistantly around the central axis of the lifting mechanism (not arranged on one side), forming a symmetrical guiding frame to resist overturning moments caused by eccentric loads. The bottom end is fixed to the 304 stainless steel base frame via an interference fit and flange locking, forming an immovable fulcrum. The upper end penetrates the plasma-nitrided groove within the telescopic arm, decomposing horizontal forces (radial load → axial thrust + normal constraint force) through a 20-degree inclined contact surface. The top of the optical shafts features a free-floating structure with a 0.2–0.4 mm axial clearance to absorb the linear expansion caused by the temperature rise during lifting operation.

[0091] The plasma-nitrided slide groove within the telescopic arm serves as the core guiding component. It forms a sliding pair with six chrome-plated optical shafts (Φ20mm), directly constraining the radial degree of freedom of the lifting shaft. Its interface utilizes a floating self-lubricating bushing (containing graphite-copper-based material, with a friction coefficient ≤0.1)). The optical shaft system, through its absolutely fixed bottom and dynamically released top structure, constrains the radial degree of freedom of the lifting shaft while avoiding the over-positioning risk of multi-axis parallel mechanisms. Its circumferential layout further enhances its resistance to eccentric loads.

[0092] The ion nitriding chute is designed with a stepped bottom structure and is made of high-strength alloy steel (38CrMoAl) with a hardness ≥ HV800. The surface undergoes plasma nitriding treatment to form a hardened layer with a thickness ≥ 0.2 mm, a microhardness ≥ HV800, and a smoothness Ra ≤ 0.4 μm, significantly improving wear resistance and anti-galling ability. The 20° inclined contact of the channel decomposes the radial load of the optical axis into axial thrust (80%–85%) and normal velocity force (15%–20%), suppressing lifting and offset. The above mechanism can be directly selected from mature products and compatible solutions.

[0093] The control system, based on the XC7Z020 chip and coordinated via EtherCAT bus, consists of components such as an MTS magnetostrictive sensor, servo driver, harmonic reducer, and EC sensor. The servo motor controls the worm gear jack via EtherCAT.

[0094] The MTS magnetostrictive sensor is a non-contact displacement measurement device that achieves measurement accuracy of ±0.01mm through the interaction of the magnetic field between a permanent magnet and a waveguide. The sensor is mounted on the base of the lifting module, and the waveguide (length ≥150mm) is parallel to the chrome-plated optical axis guide system. The permanent magnet is fixed to the movable end of the cross torque distributor to provide real-time feedback on the lifting displacement of the "X"-shaped bracket. The data is transmitted to the control system (XC7ZZ020 chip) via EtherCAT bus. When the detected tilt angle is >0.3° (IMU monitoring value) or the synchronization error is >0.5mm, the servo motor differential speed compensation and system self-locking are triggered.

[0095] The servo driver is the core control unit of the seedling facility lifting system, and the control system that enables the precise movement of the "X"-shaped support. The commands issued by the control system chip (XC7Z020) adjust the output torque through a three-loop system (position loop, speed loop, and torque loop), analyze EtherCAT bus commands in real time, control a 750W servo motor to drive the worm gear lift, and rely on an MTS magnetostrictive sensor to monitor the height difference between the two sets of seedling supports for synchronous adjustment. The servo driver features a 7-inch touchscreen.

[0096] The 7-inch touchscreen allows users to set the target height and simultaneously set parameters such as the error threshold (0.5mm), lifting speed, and limit stroke. Upon startup, commands are transmitted via EtherCAT to the servo driver, which controls the worm gear lift to raise and lower the "X"-shaped support. The magnetostrictive actuator provides real-time position feedback; when the synchronization deviation exceeds 0.5mm, differential compensation is activated to converge the height difference between the two seedling supports to within ±0.5mm. Real-time status is also displayed visually.

[0097] The water and fertilizer sensor uses a ±0.3mS / cm four-electrode sensor (IP68 waterproof connector) and is installed on the bottom side of the tray.

[0098] "When EC / pH is below the set lower limit, it triggers a descent, and the seedling tray descends into the nutrient solution, with the bottom of the substrate 50±1mm from the liquid surface; when it is above the upper limit, it rises, with the bottom of the seedling tray 200±2mm above the liquid surface."

[0099] Example 3: The track network system consists of a main track, branch tracks, AGV transport units, and a control system. The main track is made of 6063-T5 aluminum alloy profile with a cross-section of 80mm × 40mm, and the load-bearing capacity of the straight section is ≥200kg / m. Composite safety components are installed at the ends of the tracks.

[0100] The composite safety component has a density ≥1.2 g / cm³. 3 It consists of a buffer baffle (buffer stroke 50mm, kinetic energy absorption rate ≥85%) and a SICK ML100-8 laser emergency stop sensor (detection distance 0.1-3m).

[0101] The branch track achieves 90° lateral switching through a Φ300mm slewing bearing hinge, and forms a vertical intersection structure with the main track through a turntable.

[0102] The turntable is driven by a 750W servo motor (20 bits (1,048,576 CPR)) with a response time of <50ms, ensuring fast and accurate direction switching. The slewing bearing has a rated load of ≥2.5 tons.

[0103] The AVG transport unit is composed of an integrated base, vehicle body, and lifting mechanism. The base and vehicle body form the basic load-bearing platform, and a high-strength frame is used to support the drive chassis, lifting mechanism, and other components to ensure overall structural stability.

[0104] The base is the core load-bearing structure of the AGV transport unit, mainly comprising a basic frame, integrated drive chassis, support leg system, and lifting actuator. The base frame is a rectangular parallelepiped welded from alloy steel, providing overall support and integrating components such as the drive chassis and lifting mechanism to ensure load-bearing stability. An internal guide rail design guides the AGV to move precisely on the track (similar to the parallel, level guide rails on a machine tool base).

[0105] The guide rails are two parallel, equal-height metal solid track structures on the top surface of the base. The track body is precision-machined from hardened alloy steel, with a concave cross-section that forms an embedded fit with the rim of the AGV's traveling wheels. A continuous guide surface is provided on the inner side of the track to constrain the lateral freedom of the wheels, ensuring the AGV moves accurately along straight lines or curves. The track gauge tolerance is within ±0.2mm, and it forms an interference fit with the traveling wheel assembly.

[0106] The AGV transport unit is installed on the top guide rail of the base to achieve precise displacement within the plane of the base. The movement of this layer relies on independent sensor guidance.

[0107] The support foot system consists of four sets of 10kN hydraulic support feet, which, through trigger control, complete load locking within 1.8 seconds (similar to the suspension fixing mechanism of a vehicle chassis). They are directly installed at the four corners below the base frame, embedded within the hydraulic support structure, and arranged parallel to the drive chassis to ensure even load distribution to the track network.

[0108] The hydraulic support feet communicate with the master station in real time via EtherCAT bus (CoE mode), with a trigger command transmission delay of ≤1ms. The system automatically sends a locking or releasing signal based on the load status. Upon receiving the signal, the support feet are driven by hydraulic cylinders to extend and retract, completing load locking within 1.8ms. The lifting process is synchronized with the AGV wheel jack, using worm gear coordination to prevent track deviation or structural deformation. The locking mechanism employs a double-screw system for enhanced stability, with a load-bearing capacity of 10Kn / set, meeting the ≥2.5-ton rated load requirement. The support foot movement coordinates with the AGV's walking wheel set, maintaining overall balance through differential speed control, with response accuracy controlled within ±0.2mm tolerance.

[0109] The integrated drive chassis, including a 750W servo motor and wheel mechanism, is directly fixed to the frame, enabling autonomous navigation and power transmission. The chassis structure integrates transmission components to ensure driving stability.

[0110] The wheel mechanism consists of an active drive wheel assembly mounted at the bottom of the base, directly connected to a 750W servo motor. This drives the entire device to move along the main track of the seedling shed, with a load capacity of ≥2.5 tons and a positioning accuracy of centimeters. The drive wheel assembly and hydraulic support feet are arranged parallel to each other at the four corners of the base, embedded together at the bottom of the frame. During movement, the drive wheel assembly provides power, and the support feet retract. When stationary, the support feet touch the ground to lock the load, and the drive wheel assembly is unloaded and ready to go. Mature finished products for AGV steering wheels / differential wheels are available, suitable for scenarios with a load capacity of ≥2.5 tons. The integrated steering wheel module (including servo motor, gearbox, and wheel body) provided by the manufacturer can be directly purchased and adapted.

[0111] The wheels are installed on the outer side of the base bottom, with two wheels on each side. The wheel surface adopts a grooved rim structure to form an interference fit with the ground track, with the tolerance controlled within ±0.2mm to ensure anti-derailment stability.

[0112] The lifting actuator achieves a 100mm stroke lifting based on a screw and nut mechanism. The drive unit links multiple fiber rods via a synchronous belt to maintain synchronicity in the lifting process.

[0113] The control system consists of a master station and slave stations. Both the master station and slave stations use EtherCAT (CoE mode), and the EtherCAT slave station supports the CiA402 standard (CoE mode).

[0114] The overall operation process is as follows: the main track of the seedling shed moves -- the base with the AGV moves as a whole and arrives at the work area -- the hydraulic support feet lock the base -- the AVG transport unit makes fine adjustments on the base guide rail -- the seedling rack is lifted -- the support feet are released -- the base with the AGV continues to move to the next set of seedling tray racks.

[0115] The device can be directly installed in a standard seedling greenhouse without modifying the existing seedling pond structure, and its space utilization and operational compatibility meet the design requirements.

[0116] I. Evidence related to the technical effects obtained by the embodiments of this utility model.

[0117] The experiment verified the conventional seedling raising method (CK) and the production verification of seedling raising using a dry-wet alternation facility (T1). The key indicators of tobacco seedling growth and development were investigated and analyzed for both methods.

[0118] 1. Experimental Design

[0119] (1) Two treatments were set up in the experiment: T1, sowing at the same time as conventional seedling raising, and using a lifting device to realize the dry and wet alternating seedling raising method; CK, conventional floating seedling raising experiment, that is, the seedling tray is always placed in the seedling pond.

[0120] (2) Survey Content and Methods

[0121] The two treatments were first sampled at the large cross stage (when the seedlings were about to be closed), and then sampled every 3 days until the seedlings were established.

[0122] The survey indicators include: stem height, stem circumference, leaf SPAD value, underground dry (fresh) weight, above-ground dry (fresh) weight, and whole plant dry (fresh) weight.

[0123] 2. Results Analysis

[0124] 2.1 Changes during the seedling stage

[0125] (1) Difference in stem height between the two treatments

[0126] From the first sampling on April 14th to the second sampling on April 16th, the stem height of the two seedling methods was not significantly different. After April 18th, the stem height of the tobacco seedlings increased rapidly, but the stem height of CK was significantly faster than that of T1. By the seedling stage on April 30th, the height of CK tobacco seedlings reached about 15cm. Excessive seedling height is not only not conducive to seedling establishment, but also different transplanting methods, such as well cellar transplanting, not only have requirements for the age of tobacco seedlings, but also require appropriate stem height. Too high or too low is not suitable. The stem height of T1 is more widely applicable in different production areas.

[0127] (2) Difference in stem circumference

[0128] The stem circumference of T1 was generally larger than that of CK. From the early seedling stage to the seedling stage, the stem circumference of T1 was consistently larger than that of CK, approximately 1.1 times that of CK. Stem circumference is a key indicator of robust seedlings, and a thick stem circumference is an important sign of high-quality tobacco seedlings. Production has also proven that tobacco seedlings with thick stems have strong resistance to adverse conditions after transplanting, a short recovery period, and a high survival rate.

[0129] (3) Difference in SPAD values ​​of leaves

[0130] The difference in SPAD values ​​of leaves between T1 and CK during the seedling stage was not significant, indicating that the alternating wet and dry seedling method did not result in insufficient nutrient supply due to the intermittent separation of the seedling tray from the nutrient solution.

[0131] (4) Difference between fresh weight and dry weight underground

[0132] Root development is a key indicator for evaluating the quality of tobacco seedlings; seedlings with well-developed roots have a high survival rate after transplanting. Before April 16th, the T1 seedlings did not show a significant advantage in the early root elongation stage. However, after April 18th, T1 roots developed rapidly, with a significantly higher fresh weight than the control (CK). By the time the seedlings matured, the CK root weight had decreased significantly, directly affecting the quality of transplanted tobacco seedlings. T1 roots, while slightly decreasing in weight at seedling stage, rapidly increased in weight by the time they matured.

[0133] (5) Difference between fresh weight and dry weight on the ground

[0134] The amount of aboveground dry matter accumulation in tobacco seedlings is affected not only by the height of the tobacco plant but also by the leaf pruning. T1 and CK underwent leaf pruning and hardening-off on April 22 and April 28, respectively. On April 22, about 1 / 4 of the leaves were pruned, and on April 28, about 2 / 3 of the leaves were pruned.

[0135] The highest above-ground weight of T1 tobacco seedlings occurred between April 23rd and April 27th, roughly at the end of the root elongation stage, which aligns with the typical development pattern of the tobacco seedling stem. The above-ground weight decreased later, possibly due to the leaf pruning level on April 28th. The sustained increase in above-ground weight in CK was due to two factors: CK used a fully automatic leaf pruning machine, resulting in more uniform pruning, while T1 used manual pruning, ensuring a more consistent pruning standard.

[0136] (6) Fresh weight of whole plant, dry weight of whole plant (g)

[0137] Affected by changes in the weight of the above-ground parts, the highest values ​​of the fresh and dry weight of the whole plant in T1 were concentrated between April 23 and April 26, after which the weight showed a decreasing trend. The above-ground parts of CK showed a continuous upward trend overall.

[0138] From the perspective of overall seedling development, T1 has advantages over floating seedling cultivation in terms of root system and stem development (stem circumference and stem height). Although the overall weight of floating seedlings is higher than that of T1, the stem height of floating seedlings is significantly higher than that of T1, while the stem circumference is smaller. By the seedling stage, CK reaches a height of about 15cm, which poses a greater challenge for transplanting. T1, on the other hand, has a stem height of about 10cm, which is more in line with the height requirements for transplanting in well-cellar areas.

[0139] 2.2 Results of the survey on the quality of tobacco seedling transplanting

[0140] 2. Comparison of key quality indicators of seedlings transplanted from floating seedling raising and tidal seedling raising

[0141] Transplanting was carried out on May 2nd, and samples were taken beforehand to investigate key indicators of tobacco seedling quality.

[0142] (1) Stem height (cm)

[0143] The stem height of tobacco seedlings differed significantly between the two seedling raising methods. The stem height of the control (CK) seedlings was significantly higher than that of the seedlings raised in the control (T1) seedlings, and the difference between the two was statistically significant.

[0144] (2) Stem circumference (cm)

[0145] The stem circumference of T1 transplanted seedlings was significantly larger than that of CK, and the difference between the two was statistically significant, with T1 stems being thicker.

[0146] (3) SPAD value

[0147] The SPAD values ​​of the leaves from the two seedling raising methods are not much different, both ranging from 20 to 30, with the leaf color being slightly lighter.

[0148] (4) Dry matter accumulation

[0149] The root weights of the two seedling raising methods did not differ significantly. The aboveground part weight (CK) was greater than that of T1, with a significant difference. For both fresh and dry weights of the whole plant, T1 was lower than CK, and the difference was significant.

[0150] (5) Root-to-shoot ratio

[0151] The root-to-shoot ratio of tobacco seedlings is a key indicator of robust seedling growth; a higher ratio indicates better root development, a shorter recovery period after transplanting, and a higher survival rate. The root-to-shoot ratios of the two seedling raising methods differed significantly, with T1 showing a significantly higher ratio than CK, and the difference was statistically significant.

[0152] In summary, T1, while meeting the water and fertilizer needs of tobacco seedlings, overcomes the problems of weak root development, poor resistance to field environmental stresses (such as low temperature and drought), long seedling establishment period, and low survival rate caused by floating seedlings being placed in nutrient solution for extended periods. This is achieved through an alternating wet and dry water supply system at the bottom of the seedling tray. The alternating wet and dry seedling method promotes root and stem development by controlling water and fertilizer application. The experimental results show that T1 has a significant effect on improving the quality of tobacco seedlings and is an important pathway for the steady development of high-quality tobacco raw material production.

[0153] In the description of this utility model, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In addition, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0154] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the technical scope disclosed in this utility model, and within the spirit and principles of this utility model, should be included within the protection scope of this utility model.

Claims

1. A lifting device for alternating wet and dry seedling cultivation of flue-cured tobacco, characterized in that, include: A seedling facility unit module, which includes a seedling unit frame, a seedling tray, and a rigid synchronous shaft linkage system; A central drive module is installed on a mobile base and connected to the seedling facility unit module through a rigid synchronous shaft linkage system. The track network system, which consists of a main track, branch tracks and an automatic guided transport unit, is used to support and guide the movement of the central drive module within the seedling shed. A water and fertilizer sensor is electrically connected to the control system in the central drive module. The control system is used to drive the seedling facility unit module to rise and fall according to the signal output by the water and fertilizer sensor.

2. The apparatus according to claim 1, characterized in that, The seedling tray is made of 5052 aluminum alloy perforated plate with drainage holes of 5 mm in diameter evenly distributed on the surface. The drainage area is not less than 35%. The tray size is 2000 mm × 1000 mm × 2.5 mm. The ultimate load is not less than 600 kg. The surface is provided with diamond-shaped anti-slip texture with a depth of 0.3 mm to 0.5 mm and a spacing of 10 mm. The four corners are provided with locking mechanisms with quick-release pins.

3. The apparatus according to claim 1, characterized in that, The seedling unit frame includes a horizontal 304 stainless steel square tube welded skeleton and a vertical X-shaped cross support frame. The X-shaped cross support frame is a double cross arm structure with a wall thickness of 2.5 mm and an included angle of 30 to 45 degrees. The bottom is equipped with a sliding groove-tooth block self-locking mechanism. The two X-shaped support frames are connected by a synchronous shaft with a diameter of 40 mm and made of 42CrMo steel and a cross torque distributor. The lifting stroke is 100 mm.

4. The apparatus according to claim 1, characterized in that, The central drive module adopts a worm gear lift, with the worm input end connected to a 750-watt waterproof servo motor; the lift is guided by a telescopic arm guide system, which consists of six 20-mm diameter chrome-plated optical shafts arranged symmetrically around the circumference, with the lower end fixed to the movable base and the upper end reserved with an expansion gap of 0.2 mm to 0.4 mm.

5. The apparatus according to claim 1, characterized in that, The water and fertilizer sensor is a four-electrode conductivity sensor. When the conductivity value is lower than the preset lower limit, the control system lowers the seedling tray to the bottom of the substrate, which is 49 to 51 mm from the liquid surface. When the conductivity value is higher than the preset upper limit, the control system raises the seedling tray to the bottom of the substrate, which is 198 to 202 mm from the liquid surface.

6. The apparatus according to claim 1, characterized in that, The track network system is made of 6063-T5 aluminum alloy profiles. The branch tracks are connected to the main tracks through 300 mm diameter slewing bearings to achieve 90-degree lateral conversion. Buffer baffles and laser emergency stop sensors are set at the ends of the tracks. The automatic guided transport unit includes an alloy steel base frame, a drive chassis, hydraulic support feet and a screw lifting mechanism. The drive wheels are positioned with an interference fit with the tracks.

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