Flexible tightening device and method for tightening a screw without a head

Abstract

The present application belongs to the field of automatic assembly technology, and discloses a flexible tightening device and a tightening method of a non-flower type screw. The device comprises a rotary driving mechanism, a rotary main shaft assembly, a torque adjusting mechanism, a floating clamping mechanism and a displacement monitoring mechanism. The rotary main shaft assembly has a lifting shaft and a rotary disc which can be axially floated and circumferentially linked. The torque adjusting mechanism limits the maximum transmission torque. The floating clamping mechanism realizes the swing and plane floating self-adaption of the to-be-tightened part through a universal joint assembly and a plane floating platform. The displacement monitoring mechanism is used for detecting the axial displacement of the lifting shaft. The tightening method judges the tooth recognition state through height change feedback, and completes tooth recognition and tightening by using segmented control speed. The present application can realize the flexible tightening of the non-flower type screw, effectively avoid the product from being stuck and damaged, and improve the assembly reliability.

Description

Technical Field

[0001] This invention relates to the field of automated assembly technology, and in particular to a flexible tightening device and a tightening method for non-spangled screws. Background Technology

[0002] In modern factory automated production lines, tightening is a common step in the assembly process. For screws with standard patterns, there are already mature solutions in the existing technology, which can usually achieve automatic tightening using tools such as screwdriver bits and sockets.

[0003] However, in some assembly requirements, the screws to be tightened have a smooth, unadorned surface, making it difficult for conventional bits or sockets to effectively hold and transmit torque. Furthermore, ensuring the consistent positioning of the products being tightened is challenging, and conventional tightening methods can easily lead to jamming during the tightening process. Additionally, some products are quite delicate, requiring controlled tightening torque to prevent damage.

[0004] To address the aforementioned issues, existing tightening devices struggle to simultaneously meet the requirements for reliable clamping, adaptive positional deviation, torque limiting, and lightweight, flexible tightening of splice-less screws. Therefore, it is necessary to provide a device and method capable of achieving lightweight, flexible tightening of splice-less screws. Summary of the Invention

[0005] The purpose of this invention is to provide a flexible tightening device and a tightening method for non-split screws, so as to solve the problems of non-split screws being difficult to reliably clamp in automatic assembly, having poor adaptability to position deviation, being unable to limit torque, and being prone to damaging products, thereby achieving lightweight and flexible tightening.

[0006] To achieve this objective, the present invention adopts the following technical solution: A flexible tightening device, comprising: Lifting support; A rotary drive mechanism is mounted on the lifting bracket; A rotating spindle assembly is mounted on the lifting bracket and is connected to the output end of the rotating drive mechanism. The rotating spindle assembly includes a rotating shaft, a lifting shaft, and a rotating disk. The rotating shaft is rotatably mounted on the lifting bracket about its own axis. The lifting shaft passes through the rotating shaft and is linked to the rotating shaft in the circumferential direction via a drive guide key, and can slide relative to the rotating shaft in the axial direction. The rotating disk is fixed to the lifting shaft. A torque adjustment mechanism is installed on the lifting bracket and located between the rotary drive mechanism and the rotary spindle assembly, and is used to adjust the maximum torque transmitted from the rotary drive mechanism to the rotary shaft. A floating clamping mechanism includes a universal joint assembly, a planar floating platform, and a clamping assembly; the upper end of the universal joint assembly is connected to the lower end of the lifting shaft, and the lower end of the universal joint assembly is connected to the planar floating platform, enabling the planar floating platform to swing relative to the lifting shaft; the clamping assembly is fixed to the planar floating platform so that the clamping assembly can swing with the planar floating platform and float in a plane parallel to the surface of the planar floating platform. A displacement monitoring mechanism is installed on the lifting bracket and cooperates with the rotating disk to detect the axial displacement of the lifting shaft.

[0007] Preferably, the rotary drive mechanism includes a servo motor, a reducer, and a drive wheel; the servo motor drives the drive wheel through the reducer, and the drive wheel is connected to the rotary shaft via the torque adjustment mechanism.

[0008] Preferably, the rotating spindle assembly further includes a driven wheel, which is fixed to the rotating shaft; The torque adjustment mechanism includes a circular belt, an adjusting idler pulley, and an adjusting screw; the circular belt is wound around the driving pulley and the driven pulley, and the adjusting idler pulley is in contact with the circular belt; the adjusting screw is used to adjust the position of the adjusting idler pulley to change the tension of the circular belt, thereby limiting the maximum torque transmitted by the rotary drive mechanism to the rotary shaft.

[0009] Preferably, the torque adjustment mechanism further includes a fixed bracket, an adjusting nut, and a baffle; the fixed bracket is provided with a sliding groove, the adjusting nut is slidably disposed in the sliding groove, and the adjusting idler wheel is fixed on the adjusting nut; the adjusting nut is provided with a threaded hole, and the adjusting screw is rotatably disposed on the fixed bracket and threadedly engaged with the threaded hole; the baffle is fixed on the fixed bracket to limit the vertical displacement of the adjusting screw.

[0010] Preferably, the rotary spindle assembly further includes a bearing housing, at least two rotary bearings, two bearing pressure plates, at least one intermediate spacer sleeve, two mounting spacers, and a lock nut. The bearing housing is mounted on the lifting bracket; At least two of the rotating bearings are spaced apart in the bearing housing along the axial direction, and a middle spacer sleeve is provided between two adjacent rotating bearings. Two bearing pressure plates are respectively provided at the upper and lower ends of the bearing housing along the axial direction and are used to axially restrict the rotating bearings. The rotating shaft passes through at least two of the rotating bearings and is rotatably mounted in the bearing housing. One end of the rotating shaft is provided with a boss, and the other end is provided with an external thread. The driven wheel is sleeved on the end of the rotating shaft with the boss, and the driven wheel abuts against the inner ring of the adjacent rotating bearing through a mounting spacer. The end of the rotating shaft with the external thread is threadedly connected to the locking nut, and the locking nut abuts against the inner ring of the adjacent rotating bearing through another mounting spacer, so as to axially press the driven wheel, the mounting spacer, the inner rings of each rotating bearing, and the intermediate spacer onto the rotating shaft.

[0011] Preferably, the circumference of the rotating shaft is provided with two guide holes extending axially; the two drive guide keys are respectively fixed on both sides of the lifting shaft and slidably engaged in the corresponding guide holes, so that the lifting shaft can slide axially relative to the rotating shaft and move circumferentially.

[0012] Preferably, the displacement monitoring mechanism includes a sensor bracket, a linear bearing assembly, and a detection assembly; The sensor bracket is fixed to the lifting bracket; The linear bearing assembly includes a linear bearing housing, a linear bearing, and a linear bearing cover plate. The linear bearing housing is fixed to the sensor bracket, the linear bearing is disposed inside the linear bearing housing, and the linear bearing cover plate is fixed to the linear bearing housing and is used to axially limit the linear bearing. The detection assembly includes a displacement sensor and a displacement transmission component. The displacement sensor is fixed to the sensor bracket. The displacement transmission component is slidably disposed on the linear bearing, with its upper end cooperating with the displacement sensor and its lower end contacting the rotating disk. When the rotating disk floats up, the displacement transmission component slides upward along the linear bearing and presses against the displacement sensor to monitor the floating height of the rotating disk.

[0013] Preferably, the displacement transmission component includes a sensor contact block, a lifting guide column, a roller mounting block, and a roller; The lifting guide column passes through the linear bearing, with its upper end fixed to the sensor contact block and its lower end fixed to the roller mounting block; The roller is mounted on the roller mounting block, and the roller's rollers are capable of rotating around their own axis; The sensor contact block cooperates with the displacement sensor, and the roller contacts the rotating disk.

[0014] Preferably, the lifting shaft is in the lower position when no external force is applied; And / or, the rotation direction of the roller is tangent to the rotation circumference of the rotating disk, the roller follows the rotation of the rotating disk, and floats or falls synchronously with the rotating disk.

[0015] Preferably, the universal joint assembly includes an upper universal joint holder, a universal joint sleeve, a lower universal joint holder, two sets of universal joint connecting pins, and a self-returning spring, with each set of universal joint connecting pins consisting of two pins. The upper universal joint bracket is fixedly connected to the lower end of the lifting shaft; The universal joint sleeve is connected to the upper universal joint seat through a set of universal joint connecting pins, and to the lower universal joint seat through another set of universal joint connecting pins; The axis of one set of universal joint connecting pins is set perpendicular to the axis of another set of universal joint connecting pins, so that the lower universal joint holder can swing conically relative to the upper universal joint holder. The self-resetting spring is disposed between the upper universal joint holder and the lower universal joint holder, so that the upper universal joint holder and the lower universal joint holder are parallel to each other and in the center position when no external force is applied.

[0016] Preferably, the planar floating platform is fixedly connected to the lower universal joint bracket; the planar floating platform has an upper surface and a lower surface, and the upper surface and the lower surface can float relative to each other in a plane parallel to the planar floating platform.

[0017] Preferably, the clamping assembly includes a three-jaw cylinder, three jaws, and a central support column; The three-jaw cylinder is a self-resetting cylinder; it clamps when air is supplied and opens when air is not supplied by an internal spring. All three grippers and the central support column are fixed to the three-jaw cylinder; The central support column is used to be flush with the upper end surface of the part to be tightened to position the part to be tightened axially, and the three jaws are used to clamp the part to be tightened circumferentially.

[0018] Preferably, the rotating spindle assembly further includes a high-speed rotating air connector and an air outlet connector; the lifting shaft has an axially extending air passage hole inside, an air inlet hole at the top of the lifting shaft, and an air outlet hole on the lower circumferential side. A sealing ring is provided between the rotating disk and the lifting shaft; The rotating disk is provided with a threaded hole, and the high-speed rotating air connector is fixed to the rotating disk by the thread; the air inlet end of the high-speed rotating air connector is used to connect to an external air pipe, and the external air pipe does not rotate with the rotating disk when it rotates. The air outlet connector is connected to the air outlet; The high-speed rotary air connector, the air passage hole, the air outlet connector, and the three-jaw cylinder are connected in sequence via air passages.

[0019] Preferably, the flexible tightening device further includes a gravity compensation spring, which is placed between the rotating shaft and the rotating disk to offset part of the weight of the lifting shaft and the components mounted on the lifting shaft, thereby reducing the pressure on the product being tightened during tightening.

[0020] A method for tightening a non-spangled screw, employing the flexible tightening device described above, includes the following steps: Step S1: The clamping assembly clamps the part to be tightened and presses it onto the product being tightened, causing the lifting shaft and rotating disk to float up. The displacement monitoring mechanism detects the first height value at this time. Step S2: The rotary drive mechanism reverses to drive the part to be tightened, which is held by the clamping assembly, to reverse the tooth recognition process. During the reverse tooth recognition process, the part to be tightened swings and floats adaptively under the action of the universal joint assembly and the planar floating platform until the lifting shaft falls back. The displacement monitoring mechanism detects the second height value. When the difference between the first height value and the second height value falls into the first preset range, the reverse tooth recognition is considered successful. Step S3: After successful reverse tooth recognition, the rotary drive mechanism rotates forward at the first speed to drive the part to be tightened to recognize the tooth in the forward direction for 1-2 turns; the displacement monitoring mechanism detects the third height value at this time, and when the difference between the second height value and the third height value falls within the second preset range, the state is considered normal; Step S4: After confirming that the status is normal, the rotary drive mechanism rotates clockwise several times at a second speed to complete the tightening. The second speed is greater than the first speed.

[0021] Preferably, the height change detected by the displacement monitoring mechanism and the number of rotations of the rotary drive mechanism are monitored in real time throughout the tightening process, and the process is stopped if any abnormality occurs.

[0022] The beneficial effects of this invention are: The present invention provides a flexible tightening device, which includes a lifting bracket, a rotary drive mechanism, a rotary spindle assembly, a torque adjustment mechanism, a floating clamping mechanism, and a displacement monitoring mechanism. A rotary drive mechanism is mounted on a lifting bracket; a rotary spindle assembly is mounted on the lifting bracket and is connected to the output end of the rotary drive mechanism; the rotary spindle assembly includes a rotary shaft, a lifting shaft, and a rotary disk, with the rotary shaft rotatably mounted on the lifting bracket around its own axis; the lifting shaft passes through the rotary shaft and is linked to the rotary shaft circumferentially via a drive guide key, and can slide relative to it axially; the rotary disk is fixed to the lifting shaft; a torque adjustment mechanism is mounted on the lifting bracket and located between the rotary drive mechanism and the rotary spindle assembly, used to adjust the maximum torque transmitted from the rotary drive mechanism to the rotary shaft; a floating clamping mechanism includes a universal joint assembly, a planar floating platform, and a clamping assembly; the upper end of the universal joint assembly is connected to the lower end of the lifting shaft, and the lower end of the universal joint assembly is connected to the planar floating platform, allowing the planar floating platform to swing relative to the lifting shaft; the clamping assembly is fixed to the planar floating platform so that the clamping assembly can swing with the planar floating platform and float in a plane parallel to the surface of the planar floating platform; a displacement monitoring mechanism is mounted on the lifting bracket and cooperates with the rotary disk, used to detect the axial displacement of the lifting shaft. This flexible tightening device drives a rotating shaft via a rotary drive mechanism and a torque adjustment mechanism. It utilizes a circular belt friction transmission to limit the maximum torque transmitted to the rotating shaft, effectively controlling the tightening torque and preventing damage to precision products. Axial floating and circumferential linkage are achieved through a drive guide key between the lifting shaft and the rotating shaft. Combined with a displacement monitoring mechanism that monitors the floating height of the rotating disk in real time, the axial displacement of the lifting shaft can be accurately obtained. Through a universal joint assembly and a planar floating platform, the clamping assembly can adaptively swing and float with the workpiece to be tightened. This ensures reliable clamping and automatic alignment even with plain screws or products exhibiting angular, misaligned, or positional deviations, preventing jamming during tightening. Simultaneously, the clamping assembly can stably clamp smooth, plain screws. The overall structure is compact and lightweight, making it suitable for flexible tightening of plain screws in precision assembly scenarios.

[0023] This invention also provides a method for tightening a non-spangled screw, employing the flexible tightening device described above. The method for tightening a non-spangled screw includes the following steps: Step S1: The clamping assembly clamps the part to be tightened and presses it onto the product being tightened, causing the lifting shaft and rotating disk to float up. The displacement monitoring mechanism detects the first height value at this time; Step S2: The rotation drive mechanism reverses, driving the part to be tightened held by the clamping assembly to reverse the tooth alignment; During the reverse tooth alignment process, the part to be tightened swings and floats adaptively under the action of the universal joint assembly and the planar floating platform until the lifting shaft falls back down. Step S3: After successful reverse tooth recognition, the rotary drive mechanism rotates forward at the first speed to drive the part to be tightened to recognize the tooth in the forward direction for 1-2 turns. The displacement monitoring mechanism detects the third height value at this time. When the difference between the second height value and the third height value falls within the second preset range, the state is considered normal. Step S4: After confirming that the state is normal, the rotary drive mechanism rotates forward at the second speed for several turns to complete the tightening. The second speed is greater than the first speed. This method for tightening threadless screws employs a segmented control strategy: first, reverse thread recognition; then, forward thread recognition at low speed; and finally, rapid tightening. A displacement monitoring mechanism detects changes in the lifting shaft's floating height to determine if the thread recognition status is normal, effectively preventing misalignment, stripping, and jamming. During reverse thread recognition and tightening, the part to be tightened automatically swings and floats under the action of the universal joint assembly and the planar floating platform, achieving adaptive alignment of positional deviations and ensuring reliable thread engagement. Through dual judgment of height difference, the rapid tightening stage is only entered after both reverse and forward thread recognition have reached the expected state. This improves the tightening success rate and assembly consistency of threadless screws while protecting the product from damage, making it suitable for precision and lightweight tightening requirements in automated production lines. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the flexible tightening device in an embodiment of the present invention; Figure 2 This is a cross-sectional structural diagram of a portion of the flexible tightening device in an embodiment of the present invention; Figure 3 This is a cross-sectional schematic diagram of a portion of the torque adjustment mechanism in an embodiment of the present invention; Figure 4 This is a cross-sectional schematic diagram of a portion of the displacement monitoring mechanism in an embodiment of the present invention.

[0025] In the picture: 10. Lifting support; 20. Rotary drive mechanism; 201. Servo motor; 202. Reducer; 203. Drive wheel; 30. Rotary spindle assembly; 301. Rotary shaft; 302. Lifting shaft; 3021. Air passage; 303. Rotary disk; 304. Driven wheel; 305. Bearing housing; 306. Rotary bearing; 307. Bearing pressure plate; 308. Intermediate spacer sleeve; 309. Mounting spacer sleeve; 310. Locking nut; 311. High-speed rotary air connector; 312. Air outlet connector; 313. Sealing ring; 40. Torque adjustment mechanism; 401. Round belt; 402. Adjusting idler pulley; 403. Adjusting screw; 404. Fixed bracket; 405. Adjusting nut; 406. Baffle; 50. Floating clamping mechanism; 501. Planar floating platform; 502. Upper universal joint holder; 503. Universal joint sleeve; 504. Lower universal joint holder; 505. Universal joint connecting pin; 506. Self-returning spring; 507. Three-jaw cylinder; 508. Gripper; 509. Central support column; 60. Displacement monitoring mechanism; 601. Sensor bracket; 602. Linear bearing housing; 603. Linear bearing; 604. Linear bearing cover plate; 605. Displacement sensor; 606. Sensor contact block; 607. Lifting guide column; 608. Roller mounting block; 609. Roller; 70. Gravity-compensating spring; 100. Components to be tightened. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0027] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, 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. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0030] like Figures 1 to 4 As shown, this invention discloses a flexible tightening device, which includes a lifting bracket 10, a rotary drive mechanism 20, a rotary spindle assembly 30, a torque adjustment mechanism 40, a floating clamping mechanism 50, and a displacement monitoring mechanism 60. The rotary drive mechanism 20 is mounted on the lifting bracket 10; the rotary spindle assembly 30 is disposed on the lifting bracket 10 and is drively connected to the output end of the rotary drive mechanism 20; the rotary spindle assembly 30 includes a rotary shaft 301, a lifting shaft 302, and a rotating disk 303. The rotary shaft 301 is rotatably mounted on the lifting bracket 10 around its own axis; the lifting shaft 302 passes through the rotary shaft 301 and is linked to the rotary shaft 301 in the circumferential direction via a drive guide key, and can slide relative to the rotary shaft 301 in the axial direction; the rotating disk 303 is fixed to the lifting shaft 302; the torque adjustment mechanism 40 is mounted on the lifting bracket 10 and located between the rotary drive mechanism 20 and the rotary spindle assembly 30, and is used for adjusting... The maximum torque is transmitted to the rotating shaft 301 by the rotary drive mechanism 20; the floating clamping mechanism 50 includes a universal joint assembly, a planar floating platform 501, and a clamping assembly; the upper end of the universal joint assembly is connected to the lower end of the lifting shaft 302, and the lower end of the universal joint assembly is connected to the planar floating platform 501, so that the planar floating platform 501 can swing relative to the lifting shaft 302; the clamping assembly is fixed to the planar floating platform 501 so that the clamping assembly can swing with the planar floating platform 501 and float in a plane parallel to the surface of the planar floating platform 501; the displacement monitoring mechanism 60 is set on the lifting bracket 10 and cooperates with the rotating disk 303 to detect the axial displacement of the lifting shaft 302.

[0031] It is understood that in this embodiment, the part to be tightened 100 refers to a threaded part, such as a smooth, unscrewed screw, which is clamped by the clamping assembly and subjected to a tightening operation; the product to be tightened refers to the workpiece to which the part to be tightened 100 is to be screwed or tightened. The lifting bracket 10 is used to install the flexible tightening device on an automated production line or external equipment for use in conjunction with the production line; of course, the flexible tightening device can also be used as an independent device, and after being positioned manually or with auxiliary tooling, the part to be tightened is flexibly tightened. In this embodiment, the rotary drive mechanism 20 provides rotational power to the entire device, and the power is transmitted to the rotary shaft 301 through the torque adjustment mechanism 40, and the maximum transmitted torque is limited by the torque adjustment mechanism 40. When the rotary shaft 301 rotates, the lifting shaft 302 is driven to rotate synchronously through the drive guide key. The lifting shaft 302 can slide axially relative to the rotary shaft 301 to achieve floating. The rotating disk 303 is fixed to the lifting shaft 302 and rotates synchronously and floats axially with the lifting shaft 302. In the floating clamping mechanism 50, the universal joint assembly allows the planar floating platform 501 to swing relative to the lifting shaft 302. The planar floating platform 501 further provides a degree of freedom of floating in the planar direction. The clamping assembly is used to clamp the part 100 to be tightened. Thus, when there is an angular deviation or misalignment between the part 100 to be tightened and the product being tightened, the part 100 to be tightened can adaptively align itself. The displacement monitoring mechanism 60 cooperates with the rotating disk 303 to obtain the axial displacement of the lifting shaft 302 by detecting the floating height of the rotating disk 303, providing status feedback for the tightening process.

[0032] In some embodiments, such as Figure 1 As shown, the rotary drive mechanism 20 includes a servo motor 201, a reducer 202, and a drive wheel 203. The servo motor 201 drives the drive wheel 203 through the reducer 202, and the drive wheel 203 is connected to the rotary shaft 301 via a torque adjustment mechanism 40. It can be understood that the servo motor 201 enables precise speed and direction control, the reducer 202 reduces speed and increases torque, and the drive wheel 203 outputs power to the torque adjustment mechanism 40, which then transmits it to the rotary shaft 301.

[0033] In some specific embodiments, such as Figure 1 , Figure 2 and Figure 3As shown, the rotary spindle assembly 30 also includes a driven pulley 304, which is fixed to the rotary shaft 301. The torque adjustment mechanism 40 includes a circular belt 401, an adjusting idler pulley 402, and an adjusting screw 403. The circular belt 401 is wound around the driving pulley 203 and the driven pulley 304, and the adjusting idler pulley 402 is in contact with the circular belt 401. The adjusting screw 403 is used to adjust the position of the adjusting idler pulley 402 to change the tension of the circular belt 401, thereby limiting the maximum torque transmitted from the rotary drive mechanism 20 to the rotary shaft 301. It is understood that the circular belt 401 transmits power through friction. When the load torque exceeds the friction limit between the circular belt 401 and the pulley, the circular belt 401 slips, thus limiting the maximum transmitted torque. Changing the position of the adjusting idler pulley 402 can change the tension of the circular belt 401, thereby adjusting the friction limit and making the maximum transmitted torque adjustable to meet process requirements. In other embodiments, a transmission structure with torque limiting function, such as a synchronous belt, V-belt, or friction clutch, can be used to replace the round belt 401 and the adjusting idler pulley 402, as long as the torque limiting of the friction transmission can be achieved.

[0034] In some embodiments, such as Figure 3 As shown, the torque adjustment mechanism 40 also includes a fixed bracket 404, an adjusting nut 405, and a baffle 406. The fixed bracket 404 has a groove, in which the adjusting nut 405 is slidably disposed, and the adjusting idler wheel 402 is fixed to the adjusting nut 405. The adjusting nut 405 has a threaded hole, in which the adjusting screw 403 is rotatably disposed and threadedly engaged with the threaded hole. The baffle 406 is fixed to the fixed bracket 404 and is used to limit the vertical displacement of the adjusting screw 403. It can be understood that when the adjusting screw 403 is rotated, the adjusting nut 405 slides in the groove, thereby driving the adjusting idler wheel 402 to move, thus adjusting the tension of the round belt 401. The baffle 406 prevents the adjusting screw 403 from shifting vertically under force, ensuring stable and reliable adjustment.

[0035] In some specific embodiments, such as Figure 2As shown, the rotary spindle assembly 30 also includes a bearing housing 305, at least two rotary bearings 306, two bearing pressure plates 307, at least one intermediate spacer sleeve 308, two mounting spacers 309, and a locking nut 310; the bearing housing 305 is mounted on the lifting bracket 10; at least two rotary bearings 306 are spaced apart along the axial direction of the bearing housing 305, and an intermediate spacer sleeve 308 is provided between two adjacent rotary bearings 306; the two bearing pressure plates 307 are respectively provided at the upper and lower ends of the bearing housing 305 along the axial direction and are used to axially restrict the rotary bearings 306, specifically restricting the outer ring of the rotary bearings 306. A rotating shaft 301 passes through the inner rings of at least two rotating bearings 306 and is rotatably mounted in a bearing housing 305. One end of the rotating shaft 301 is provided with a boss, and the other end is provided with an external thread. A driven wheel 304 is sleeved on the end of the rotating shaft 301 with the boss, and the driven wheel 304 abuts against the inner ring of the adjacent rotating bearing 306 through a mounting spacer 309. The end of the rotating shaft 301 with the external thread is threadedly connected to a locking nut 310, and the locking nut 310 abuts against the inner ring of the adjacent rotating bearing 306 through another mounting spacer 309, so as to axially press the driven wheel 304, the mounting spacer 309, the inner rings of each rotating bearing 306 and the intermediate spacer 308 onto the rotating shaft 301. Understandably, by cooperating with the locking nut 310 and the mounting spacer 309 and intermediate spacer 308, the driven wheel 304 on the rotating shaft 301 and the inner rings of each rotating bearing 306 are axially pressed together, achieving reliable fixation of the rotating shaft 301 with the driven wheel 304 and the inner rings of the rotating bearings 306, ensuring smooth rotation of the rotating shaft 301 and its ability to withstand axial force. Two bearing pressure plates 307 confine the outer rings of the bearings within the bearing housing 305, preventing axial movement of the rotating bearings 306. An intermediate spacer 308 is provided between two adjacent rotating bearings 306 to adjust the bearing spacing and allow for pre-tightening. Optionally, the rotating bearings 306 can be deep groove ball bearings, angular contact ball bearings, etc., and the specific quantity and type can be selected according to the load-bearing requirements.

[0036] In some embodiments, the circumference of the rotating shaft 301 is provided with two axially extending guide holes; two drive guide keys are respectively fixed to both sides of the lifting shaft 302 and slidably fitted into the corresponding guide holes, so that the lifting shaft 302 can slide axially relative to the rotating shaft 301 and move in a circumferential manner. It is understood that the guide holes can be oblong holes or long slots, and the drive guide keys can slide axially within the guide holes but are circumferentially limited, thereby transmitting torque and allowing axial floating. In other embodiments, spline fits, keyways, or other structures can also be used to achieve the same circumferential linkage and axial sliding functions.

[0037] In some embodiments, such as Figure 1 and Figure 4As shown, the displacement monitoring mechanism 60 includes a sensor bracket 601, a linear bearing 603 assembly, and a detection component. The sensor bracket 601 is fixed to the lifting bracket 10. The linear bearing 603 assembly includes a linear bearing seat 602, a linear bearing 603, and a linear bearing cover plate 604. The linear bearing seat 602 is fixed to the sensor bracket 601, the linear bearing 603 is disposed within the linear bearing seat 602, and the linear bearing cover plate 604 is fixed to the linear bearing seat 602 and is used to axially limit the linear bearing 603. The detection component includes a displacement sensor 605 and a displacement transmission component. The displacement sensor 605 is fixed to the sensor bracket 601; the displacement transmission component slides through the linear bearing 603, with its upper end engaging with the displacement sensor 605 and its lower end contacting the rotating disk 303. When the rotating disk 303 floats, the displacement transmission component slides upward along the linear bearing 603 and presses against the displacement sensor 605 to monitor the floating height of the rotating disk 303. Understandably, when the rotating disk 303 floats axially with the lifting shaft 302, it drives the displacement transmission component to move up and down. The displacement transmission component transmits the displacement to the displacement sensor 605, which converts the displacement change into an electrical signal output, thereby monitoring the axial position of the lifting shaft 302 in real time. The linear bearing 603 assembly can reduce the frictional resistance when the displacement transmission component slides, improving the detection accuracy. The displacement sensor 605 can be a contact displacement sensor 605, LVDT, grating ruler, etc., as long as it can detect the displacement of the displacement transmission component.

[0038] In some specific embodiments, such as Figure 2 As shown, the displacement transmission component includes a sensor contact block 606, a lifting guide post 607, a roller mounting block 608, and a roller 609. The lifting guide post 607 passes through a linear bearing 603, with its upper end fixed to the sensor contact block 606 and its lower end fixed to the roller mounting block 608. The roller 609 is mounted on the roller mounting block 608, and its rollers can rotate around their own axis. The sensor contact block 606 cooperates with the displacement sensor 605, and the roller 609 contacts the rotating disk 303. It can be understood that when the rotating disk 303 rotates, the roller 609 rolls along the surface of the rotating disk 303, reducing friction and wear. The rotation direction of the roller 609 is tangent to the circumference of the rotating disk 303. As the rotating disk 303 floats up and down with the lifting shaft 302, the roller 609 drives the roller mounting block 608, the lifting guide column 607, and the sensor contact block 606 to move up and down, thereby pressing against the displacement sensor 605. The sensor contact block 606 ensures reliable and stable contact with the displacement sensor 605. Two lifting guide columns 607 can be provided for greater structural stability. In other embodiments, the displacement transmission component can also be a push rod, slider, or lever structure, as long as it can float up and down with the rotating disk 303 and transmit displacement to the displacement sensor 605.

[0039] In some embodiments, when no external force is applied, the lifting shaft 302 is in the lower position; and / or, the rotation direction of the roller 609 is tangent to the rotation circumference of the rotating disk 303, and the roller 609 rotates with the rotating disk 303, and floats or falls synchronously with the rotating disk 303. It can be understood that in the free state, due to gravity, the lifting shaft 302 and its components fall to the lower position, and the roller 609 remains in contact with the rotating disk 303. When the rotating disk 303 rotates, the roller 609 rotates with the rotating disk 303; when the rotating disk 303 floats or falls, the roller 609 moves synchronously. This structure ensures that the displacement monitoring mechanism 60 always remains in contact with the rotating disk 303, and can reflect the axial displacement of the lifting shaft 302 in real time. The above two states can exist individually or simultaneously, both of which are within the scope of this embodiment.

[0040] In some embodiments, such as Figure 2 As shown, the universal joint assembly includes an upper universal joint holder 502, a universal joint sleeve 503, a lower universal joint holder 504, two sets of universal joint connecting pins 505, and a self-resetting spring 506. Each set of universal joint connecting pins 505 consists of two pins. The upper universal joint holder 502 is fixedly connected to the lower end of the lifting shaft 302. The universal joint sleeve 503 is connected to the upper universal joint holder 502 via one set of universal joint connecting pins 505, and also to the upper universal joint holder 502 via another set of universal joint connecting pins 506. 05 is connected to the lower universal joint seat 504; the axis of one set of universal joint connecting pins 505 is set perpendicular to the axis of another set of universal joint connecting pins 505, so that the lower universal joint seat 504 can swing conically relative to the upper universal joint seat 502; the self-resetting spring 506 is set between the upper universal joint seat 502 and the lower universal joint seat 504, so that the upper universal joint seat 502 and the lower universal joint seat 504 are parallel to each other and in the center position when no external force is applied.

[0041] Understandable Figure 2 The universal joint connecting pins 505 shown only represent one set that secures the lower universal joint holder 504. The axis of the other set is perpendicular to the plane of the drawing, i.e., perpendicular to the axis of the set of universal joint connecting pins 505 already shown. The two sets of universal joint connecting pins 505 with perpendicular axes constitute a universal joint structure, allowing the lower universal joint holder 504 to conically swing relative to the upper universal joint holder 502 in any direction, providing angle self-adaptation capability for the part to be tightened 100. The self-returning spring 506 automatically returns the upper and lower universal joint holders 504 to a parallel and centered state when no force is applied, ensuring that the part to be tightened 100 is aligned in its initial position. In other embodiments, the number and layout of the universal joint connecting pins 505 can be adjusted according to the load-bearing and swing angle requirements, for example, ball joints or cross universal joints can be used.

[0042] In some specific embodiments, the planar floating platform 501 is fixedly connected to the lower universal joint holder 504; the planar floating platform 501 has an upper surface and a lower surface, and the upper and lower surfaces can float relative to each other in a plane parallel to the planar floating platform 501. It is understood that the planar floating platform 501 can move relative to each other in a planar direction, providing the clamping assembly with in-plane floating degrees of freedom to absorb horizontal positional deviations between the part to be tightened 100 and the product being tightened. The planar floating platform 501 can be an XY floating platform, a sliding guide rail type floating platform, a ball bearing type floating platform, or an elastic floating platform, etc., as long as it can achieve planar relative floating between the upper and lower surfaces.

[0043] In some embodiments, such as Figure 2 As shown, the clamping assembly includes a three-jaw cylinder 507, three jaws 508, and a central support column 509. The three-jaw cylinder 507 is a self-resetting cylinder; it clamps when air is supplied and opens when air is de-supplied by a built-in spring. The three jaws 508 and the central support column 509 are all fixed to the three-jaw cylinder 507. The central support column 509 is used to flatten the upper surface of the part to be tightened 100 to axially position the part to be tightened 100, and the three jaws 508 are used to clamp the part to be tightened 100 circumferentially. It can be understood that after the three-jaw cylinder 507 is supplied with air, the three jaws 508 synchronously retract radially to clamp the outer circumferential surface of the part to be tightened 100, achieving reliable clamping of the smooth, non-grooved screw. The central support column 509 provides axial support and positioning to the upper surface of the part to be tightened 100, preventing the part to be tightened 100 from tilting during tightening. The three-jaw cylinder 507 adopts a self-resetting design, automatically opening when air is cut off to ensure safety. In other embodiments, the number of grippers 508 may be two, four, etc., and the cylinder may be replaced by an electric gripper, a pneumatic finger, or a hydraulic gripping mechanism.

[0044] In some embodiments, such as Figure 2As shown, the rotating spindle assembly 30 also includes a high-speed rotating air connector 311 and an air outlet connector 312; the lifting shaft 302 has an axially extending air passage hole 3021 inside, an air inlet hole at the top of the lifting shaft 302, and an air outlet hole on the lower circumference; a sealing ring 313 is provided between the rotating disk 303 and the lifting shaft 302; a threaded hole is provided on the rotating disk 303, and the high-speed rotating air connector 311 is fixed to the rotating disk 303 by the thread; the air inlet end of the high-speed rotating air connector 311 is used to connect to an external air pipe, and the external air pipe does not rotate with the rotating disk 303; the air outlet connector 312 is connected to the air outlet hole; the high-speed rotating air connector 311, the air passage hole 3021, the air outlet connector 312, and the three-jaw cylinder 507 are connected in sequence by air passage. It is understood that compressed gas enters the air passage 3021 inside the lifting shaft 302 from the external air pipe via the high-speed rotary air connector 311, and then supplies the three-jaw cylinder 507 from the outlet port via the outlet connector 312, realizing air supply to the three-jaw cylinder 507 in the rotating state, while the external air pipe does not rotate, avoiding air pipe entanglement. The sealing ring 313 is used to ensure the airtightness between the rotating disk 303 and the lifting shaft 302. The high-speed rotary air connector 311 can be a commercially available rotary air connector or rotary connector. It should be noted that this air passage structure is used to supply air to the three-jaw cylinder 507. In other embodiments, the air passage can also be arranged outside the rotating shaft 301, and the air passage can be realized through a rotating sleeve or a rotating air distribution block.

[0045] In some embodiments, such as Figure 2 As shown, the flexible tightening device of the present invention also includes a gravity compensation spring 70, which is placed between the rotating shaft 301 and the rotating disk 303 to offset part of the weight of the lifting shaft 302 and the components mounted on the lifting shaft 302, thereby reducing the pressure on the product being tightened during tightening. It is understood that the lifting shaft 302 and its components will generate downward pressure under their own weight. The gravity compensation spring 70 provides upward support based on its elastic properties, offsetting part of the gravity and reducing the normal pressure acting on the product being tightened, thus meeting the requirements of lightweight, low-torque precision tightening. The stiffness and pre-compression of the gravity compensation spring 70 can be selected according to the weight of the lifting mechanism and process requirements.

[0046] The tightening method for non-spangled screws will be explained below in conjunction with the aforementioned flexible tightening device.

[0047] The present invention also discloses a method for tightening a non-spangled screw, employing a flexible tightening device as described in any of the above embodiments, comprising the following steps: Step S1: The clamping assembly clamps the part to be tightened 100 and presses the part to be tightened 100 onto the product being tightened, causing the lifting shaft 302 and the rotating disk 303 to float up, and the displacement monitoring mechanism 60 detects the first height value at this time. Step S2: The rotary drive mechanism 20 reverses to drive the part to be tightened 100 held by the clamping assembly to reverse the tooth recognition; during the reverse tooth recognition process, the part to be tightened 100 swings and floats adaptively under the action of the universal joint assembly and the planar floating platform 501 until the lifting shaft 302 falls back. The displacement monitoring mechanism 60 detects the second height value. When the difference between the first height value and the second height value falls into the first preset range, the reverse tooth recognition is considered successful. Step S3: After successful reverse tooth recognition, the rotary drive mechanism 20 rotates forward at the first speed, driving the part to be tightened 100 to recognize the tooth in the forward direction for 1-2 turns; the displacement monitoring mechanism 60 detects the third height value at this time. When the difference between the second height value and the third height value falls within the second preset range, the state is considered normal. Step S4: After confirming that the status is normal, the rotary drive mechanism 20 rotates several revolutions at the second speed to complete the tightening. The second speed is greater than the first speed.

[0048] It is understandable that in step S1, the clamping component first clamps the part to be tightened 100, so that the part to be tightened 100 is pressed on the product being tightened, the lifting shaft 302 is lifted, the rotating disk 303 floats up, and the displacement monitoring mechanism 60 records the current height as the first height value.

[0049] In step S2, the rotary drive mechanism 20 reverses, and the part to be tightened 100 rotates in the opposite direction to perform thread recognition. At this time, under the action of the universal joint assembly and the planar floating platform 501, the part to be tightened 100 can automatically compensate for angular and positional deviations. When the threads are aligned and begin to engage, the lifting shaft 302 moves downward due to the thread engagement, that is, the lifting shaft 302 falls back, and the displacement monitoring mechanism 60 detects the second height value. The difference between the first height value and the second height value represents the change in thread engagement depth. When it falls into the first preset range, it is determined that the reverse thread recognition is successful.

[0050] In step S3, the first rotation speed is lowered and rotated forward for 1-2 revolutions to confirm the thread engagement and to check the third height value. If the difference between the second and third height values ​​falls within the second preset range, the condition is considered normal.

[0051] After confirming everything is normal in step S4, increase the rotation speed to quickly complete the remaining tightening. This method effectively avoids misalignment and jamming, and protects the product, through height change feedback and segmented speed control. The first rotation speed can be low-speed forward rotation, and the second rotation speed can be high-speed forward rotation; the relationship between the two speeds can be set according to specific working conditions.

[0052] In some embodiments, the height change detected by the displacement monitoring mechanism 60 and the number of rotations of the rotary drive mechanism 20 are monitored in real time throughout the tightening process, and the process stops when an abnormality occurs. It is understood that by monitoring the height change and the number of rotations in real time, the normality of the tightening process can be determined. Specific abnormalities may include, but are not limited to: mismatch between the height change and the number of rotations, the height change exceeding a preset range, the number of rotations exceeding a preset range, an abnormal rate of height change, or the total height change exceeding the tolerance zone. When any of the above abnormalities occur, the rotary drive mechanism 20 should be stopped immediately to prevent damage to the part to be tightened 100 or the product being tightened. For example, if the number of rotations of the rotary drive mechanism 20 reaches a predetermined value but the height change does not reach the corresponding range, it indicates possible stripping or jamming, and the process should be stopped; if the height change exceeds the preset range, it indicates possible incorrect thread turning, and the process should be stopped; if the number of rotations exceeds the preset range, it indicates possible incomplete tightening or slippage, and the process should be stopped. Those skilled in the art can set specific judgment thresholds and abnormality types according to actual process requirements.

[0053] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A flexible tightening device, characterized in that, include: Lifting support (10); A rotary drive mechanism (20) is installed on the lifting bracket (10). A rotating spindle assembly (30) is mounted on the lifting bracket (10) and is connected to the output end of the rotating drive mechanism (20). The rotating spindle assembly (30) includes a rotating shaft (301), a lifting shaft (302), and a rotating disk (303). The rotating shaft (301) is rotatably mounted on the lifting bracket (10) around its own axis. The lifting shaft (302) passes through the rotating shaft (301) and is linked to the rotating shaft (301) in the circumferential direction via a drive guide key, and can slide relative to the rotating shaft (301) in the axial direction. The rotating disk (303) is fixed to the lifting shaft (302). A torque adjustment mechanism (40) is installed on the lifting bracket (10) and located between the rotary drive mechanism (20) and the rotary spindle assembly (30), for adjusting the maximum torque transmitted from the rotary drive mechanism (20) to the rotary shaft (301); The floating clamping mechanism (50) includes a universal joint assembly, a planar floating platform (501), and a clamping assembly; the upper end of the universal joint assembly is connected to the lower end of the lifting shaft (302), and the lower end of the universal joint assembly is connected to the planar floating platform (501), so that the planar floating platform (501) can swing relative to the lifting shaft (302); the clamping assembly is fixed to the planar floating platform (501) so that the clamping assembly can swing with the planar floating platform (501) and float in a plane parallel to the surface of the planar floating platform (501); The displacement monitoring mechanism (60) is installed on the lifting bracket (10) and cooperates with the rotating disk (303) to detect the axial displacement of the lifting shaft (302).

2. The flexible tightening device according to claim 1, characterized in that, The rotary drive mechanism (20) includes a servo motor (201), a reducer (202), and a drive wheel (203); the servo motor (201) drives the drive wheel (203) through the reducer (202), and the drive wheel (203) is connected to the rotating shaft (301) through the torque adjustment mechanism (40).

3. The flexible tightening device according to claim 2, characterized in that, The rotating spindle assembly (30) also includes a driven wheel (304) which is fixed to the rotating shaft (301). The torque adjustment mechanism (40) includes a circular belt (401), an adjusting idler pulley (402), and an adjusting screw (403); the circular belt (401) is wound around the driving pulley (203) and the driven pulley (304), and the adjusting idler pulley (402) is in contact with the circular belt (401); the adjusting screw (403) is used to adjust the position of the adjusting idler pulley (402) to change the tension of the circular belt (401), thereby limiting the maximum torque transmitted by the rotary drive mechanism (20) to the rotary shaft (301).

4. The flexible tightening device according to claim 3, characterized in that, The torque adjustment mechanism (40) further includes a fixed bracket (404), an adjusting nut (405), and a baffle (406); the fixed bracket (404) is provided with a sliding groove, the adjusting nut (405) is slidably disposed in the sliding groove, and the adjusting idler wheel (402) is fixed on the adjusting nut (405); the adjusting nut (405) is provided with a threaded hole, and the adjusting screw (403) is rotatably disposed on the fixed bracket (404) and threadedly engaged with the threaded hole; the baffle (406) is fixed on the fixed bracket (404) and is used to limit the vertical displacement of the adjusting screw (403).

5. The flexible tightening device according to claim 3, characterized in that, The rotary spindle assembly (30) also includes a bearing housing (305), at least two rotary bearings (306), two bearing pressure plates (307), at least one intermediate spacer sleeve (308), two mounting spacers (309), and a lock nut (310). The bearing housing (305) is mounted on the lifting bracket (10); At least two of the rotating bearings (306) are spaced apart in the bearing housing (305) along the axial direction. A spacer sleeve (308) is provided between two adjacent rotating bearings (306). Two bearing pressure plates (307) are respectively provided at the upper and lower ends of the bearing housing (305) in the axial direction and are used to axially restrict the rotating bearings (306). The rotating shaft (301) passes through at least two of the rotating bearings (306) and is rotatably mounted in the bearing housing (305). One end of the rotating shaft (301) is provided with a boss, and the other end is provided with an external thread. The driven wheel (304) is sleeved on the end of the rotating shaft (301) with the boss, and the driven wheel (304) abuts against the inner ring of the adjacent rotating bearing (306) through a mounting spacer (309). The end of the rotating shaft (301) with the external thread is threadedly connected to the locking nut (310), and the locking nut (310) abuts against the inner ring of the adjacent rotating bearing (306) through another mounting spacer (309) to axially press the driven wheel (304), the mounting spacer (309), the inner rings of each rotating bearing (306), and the intermediate spacer (308) onto the rotating shaft (301).

6. The flexible tightening device according to claim 1, characterized in that, The rotating shaft (301) has two guide holes extending axially on its periphery; the two drive guide keys are respectively fixed on both sides of the lifting shaft (302) and are respectively slidably engaged in the corresponding guide holes, so that the lifting shaft (302) can slide axially relative to the rotating shaft (301) and move circumferentially.

7. The flexible tightening device according to claim 1, characterized in that, The displacement monitoring mechanism (60) includes a sensor bracket (601), a linear bearing (603) assembly, and a detection assembly; The sensor bracket (601) is fixed to the lifting bracket (10). The linear bearing (603) assembly includes a linear bearing housing (602), a linear bearing (603), and a linear bearing cover plate (604). The linear bearing housing (602) is fixed to the sensor bracket (601), the linear bearing (603) is disposed inside the linear bearing housing (602), and the linear bearing cover plate (604) is fixed to the linear bearing housing (602) and is used to axially limit the linear bearing (603). The detection assembly includes a displacement sensor (605) and a displacement transmission component. The displacement sensor (605) is fixed to the sensor bracket (601). The displacement transmission component is slidably disposed on the linear bearing (603), with its upper end cooperating with the displacement sensor (605) and its lower end contacting the rotating disk (303). When the rotating disk (303) floats up, the displacement transmission component slides upward along the linear bearing (603) and presses against the displacement sensor (605) to monitor the floating height value of the rotating disk (303).

8. The flexible tightening device according to claim 7, characterized in that, The displacement transmission component includes a sensor contact block (606), a lifting guide column (607), a roller mounting block (608), and a roller (609). The lifting guide column (607) passes through the linear bearing (603), its upper end is fixed to the sensor contact block (606), and its lower end is fixed to the roller mounting block (608); The roller (609) is mounted on the roller mounting block (608), and the roller of the roller (609) can rotate about its own axis; The sensor contact block (606) cooperates with the displacement sensor (605), and the roller (609) contacts the rotating disk (303).

9. The flexible tightening device according to claim 8, characterized in that, When no external force is applied, the lifting shaft (302) is in the lower position; And / or, the rotation direction of the roller (609) is tangent to the rotation circumference of the rotating disk (303), the roller (609) rotates with the rotating disk (303), and floats or falls synchronously with the rotating disk (303).

10. The flexible tightening device according to claim 1, characterized in that, The universal joint assembly includes an upper universal joint holder (502), a universal joint sleeve (503), a lower universal joint holder (504), two sets of universal joint connecting pins (505) and a self-returning spring (506), with each set of universal joint connecting pins (505) consisting of two pins; The upper universal joint bracket (502) is fixedly connected to the lower end of the lifting shaft (302); The universal joint sleeve (503) is connected to the upper universal joint seat (502) through a set of universal joint connecting pins (505), and is connected to the lower universal joint seat (504) through another set of universal joint connecting pins (505); The axis of one set of universal joint connecting pins (505) is set perpendicular to the axis of another set of universal joint connecting pins (505), so that the lower universal joint holder (504) can swing conically relative to the upper universal joint holder (502). The self-resetting spring (506) is disposed between the upper universal joint holder (502) and the lower universal joint holder (504), so that the upper universal joint holder (502) and the lower universal joint holder (504) are parallel to each other and in the center position when no external force is applied.

11. The flexible tightening device according to claim 10, characterized in that, The planar floating platform (501) is fixedly connected to the lower universal joint bracket (504); the planar floating platform (501) has an upper surface and a lower surface, and the upper surface and the lower surface can float relative to each other in a plane parallel to the planar floating platform (501).

12. The flexible tightening device according to claim 1, characterized in that, The clamping assembly includes a three-jaw cylinder (507), three jaws (508), and a central support column (509). The three-jaw cylinder (507) is a self-resetting cylinder that clamps when air is supplied and opens when air is not supplied by a built-in spring. The three grippers (508) and the central support column (509) are all fixed to the three-jaw cylinder (507); The central support column (509) is used to be flush with the upper end face of the part to be tightened (100) to axially position the part to be tightened (100), and the three jaws (508) are used to clamp the part to be tightened (100) in the circumferential direction.

13. The flexible tightening device according to claim 12, characterized in that, The rotating spindle assembly (30) also includes a high-speed rotating air connector (311) and an air outlet connector (312); the lifting shaft (302) is provided with an axially extending air passage hole (3021) inside, the top of the lifting shaft (302) is provided with an air inlet hole, and the lower circumferential side is provided with an air outlet hole; A sealing ring (313) is provided between the rotating disk (303) and the lifting shaft (302). The rotating disk (303) is provided with a threaded hole, and the high-speed rotating air connector (311) is fixed to the rotating disk (303) by the thread; the air inlet end of the high-speed rotating air connector (311) is used to connect to an external air pipe, and the external air pipe does not rotate with the rotating disk (303) when it rotates; The air outlet connector (312) is connected to the air outlet; The high-speed rotary air connector (311), the air passage hole (3021), the air outlet connector (312), and the three-jaw cylinder (507) are connected in sequence via air passages.

14. The flexible tightening device according to claim 1, characterized in that, The flexible tightening device also includes a gravity compensation spring (70), which is placed between the rotating shaft (301) and the rotating disk (303) to offset part of the weight of the lifting shaft (302) and the components installed on the lifting shaft (302) to reduce the pressure on the product being tightened during tightening.

15. A method for tightening a non-spangled screw, characterized in that, Using the flexible tightening device as described in any one of claims 1 to 14, the tightening method for the non-spangled screw includes the following steps: Step S1: The clamping assembly clamps the part to be tightened (100) and presses the part to be tightened (100) onto the product being tightened, causing the lifting shaft (302) and the rotating disk (303) to float up, and the displacement monitoring mechanism (60) detects the first height value at this time; Step S2: The rotary drive mechanism (20) reverses, driving the part to be tightened (100) held by the clamping assembly to reverse the tooth recognition; during the reverse tooth recognition process, the part to be tightened (100) swings and floats adaptively under the action of the universal joint assembly and the planar floating platform (501) until the lifting shaft (302) falls back, the displacement monitoring mechanism (60) detects the second height value, and when the difference between the first height value and the second height value falls into the first preset range, the reverse tooth recognition is considered successful; Step S3: After the reverse tooth recognition is successful, the rotary drive mechanism (20) rotates forward at the first speed to drive the part to be tightened (100) to recognize the tooth in the forward direction for 1-2 turns; the displacement monitoring mechanism (60) detects the third height value at this time. When the difference between the second height value and the third height value falls into the second preset range, the state is considered normal. Step S4: After confirming that the status is normal, the rotary drive mechanism (20) rotates forward several times at the second speed to complete the tightening. The second speed is greater than the first speed.

16. The tightening method for the non-spangled screw according to claim 15, characterized in that, Throughout the tightening process, the height change detected by the displacement monitoring mechanism (60) and the number of rotations of the rotation drive mechanism (20) are monitored in real time, and the process is stopped when an abnormality occurs.

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