Vision-guided automatic batch-changing screw tightening system and method thereof

Abstract

The invention relates to the technical field of screw tightening systems, and discloses a vision-guided automatic batch-changing screw tightening system and a method thereof.The vision-guided automatic batch-changing screw tightening system comprises a vision guiding subsystem, and the vision guiding subsystem is used for collecting a workpiece image; identifying the position and angle of the screw hole and the type of the screw head; the device further comprises a screwdriver bit library, a screwdriver bit quick-changing mechanism and a tightening executing mechanism. The vision-guided automatic batch-changing screw tightening system is used for improving the automation degree and efficiency of multi-specification screw mixed flow assembly and ensuring the positioning precision and tightening quality in the tightening process. According to the method, a multi-degree-of-freedom robot and a screwdriver bit replacement mechanism thereof are matched, so that full-flow automation from recognition of a screw hole to tightening is realized, and the screwdriver bit can be quickly, accurately and efficiently replaced according to needs, so that the problems of time and labor consumption, low production efficiency and the like in replacement of the screwdriver bit of the existing automatic tightening equipment are solved.

Description

Technical Field

[0001] This invention relates to the field of screw tightening system technology, specifically to a vision-guided automatic batch screw tightening system and method. Background Technology

[0002] In modern manufacturing industries such as automotive, electronics, aerospace, and home appliance assembly, screw tightening is one of the most widely used and fundamental connection processes. The quality, safety, and reliability of a product largely depend on the quality of screw tightening. Traditional screw tightening operations mainly rely on manual or semi-automatic screwdrivers, which is not only inefficient and labor-intensive, but also highly susceptible to quality problems such as missed tightening, stripped threads, insufficient torque, or over-tightening due to human factors.

[0003] With the development of industrial automation, robot-based automatic screw tightening systems have emerged, in which robots carry electric screwdrivers to complete the tightening action, greatly improving the consistency and efficiency of operations.

[0004] However, in actual production, a product often needs to be assembled with a variety of different types and specifications of screws, which requires the use of screwdrivers with different screwdriver bits.

[0005] Existing automated tightening equipment is typically equipped with only one type of screwdriver bit, which cannot accommodate mixed-line production of screws of various sizes. When it is necessary to change the screw type, the machine must be stopped and the screwdriver bit or the entire tool must be changed manually, which seriously affects the continuity of production and the degree of automation.

[0006] Existing equipment is not convenient for automatically, quickly, and accurately changing the matching screwdriver bits according to actual assembly needs, thus making it impossible to efficiently and reliably complete the mixed-flow automated assembly of screws of various specifications.

[0007] Furthermore, the replacement process relies on manual operation. When encountering screws of different specifications, operators need to stop production and manually change the screwdriver bits, resulting in low production efficiency and making it difficult to achieve full automation of the production process.

[0008] Therefore, we propose a visually guided automatic batch screw tightening system and method to address the problems mentioned above. Summary of the Invention

[0009] This invention provides a vision-guided automatic screw tightening system and method, which can solve the problem that existing screw tightening equipment is not convenient for automatically, quickly and accurately changing the matching screwdriver bits according to actual assembly needs.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A vision-guided automatic screw tightening system includes a vision guidance subsystem for acquiring workpiece images and identifying the position and angle of screw holes and the type of screw head; a screw bit library for storing various screw bits of different specifications; a screw bit quick-change mechanism; a tightening actuator including a multi-degree-of-freedom robot and a locking drive assembly; and a central control unit electrically connected to the vision guidance subsystem, the screw bit quick-change mechanism, and the tightening actuator.

[0011] Preferably, the vision guidance subsystem includes an industrial camera and an illumination source. The industrial camera and illumination source are installed at the end of the switching chamber away from the drive end of the multi-degree-of-freedom robot, and a mapping relationship between their coordinate system and the coordinate system of the tightening actuator is established through hand-eye calibration.

[0012] Preferably, the screwdriver bit magazine includes a switching chamber, inside which a rotary switching component and multiple sets of detachable bit holders are provided; the rotary switching component is located at one end of the switching chamber, and a working slot is opened at the other end.

[0013] Preferably, the rotary switching assembly includes a gear ring, with a sun gear located at the center inside the gear ring, and a rotary drive component for rotating the sun gear installed at the center of the outside of the switching chamber; a plurality of planetary gears are rotatably meshed between the sun gear and the gear ring, and the center of the working slot is on a virtual circumference determined by the centers of the plurality of planetary gears; a bit holder is installed at the center of one side of the planetary gears, the bit holder is used to store screwdriver bits, the screwdriver bits are magnetically fixed to the inside of the bit holder, a magnetic block is provided inside the bit holder for magnetically fixing the plug end of the screwdriver bit, and a plug groove is provided inside the bit holder, the plug groove and the plug end of the screwdriver bit are matched by a specific shape to prevent the plug groove and the screwdriver bit from rotating relative to each other.

[0014] Preferably, the bit holder is magnetically engaged with the planetary gear, and a frustum-shaped magnetic holder is fixedly provided near the center of the planetary gear, and a magnetic groove is provided at the bottom of the bit holder to engage with the frustum-shaped magnetic holder.

[0015] Preferably, the rotary drive component includes a stepper motor, which is installed outside the switching chamber. A drive shaft is provided in the middle of the sun gear. The rotating shaft of the stepper motor passes through the center of the switching chamber and is connected to the drive shaft of the internal sun gear. An absolute encoder is installed on the rotating shaft of the stepper motor. A U-shaped frame is fixedly installed outside the switching chamber. The stepper motor is fixedly connected to the U-shaped frame. The drive end of the multi-degree-of-freedom robot is fixedly connected to the outside of the U-shaped frame for moving the U-shaped frame to adjust its position.

[0016] Preferably, a sliding groove is provided on the inner wall of the switching chamber, a drive block is slidably connected inside the sliding groove, a lead screw is rotatably provided inside the sliding groove, a drive motor is fixedly installed at one end of the sliding groove, the drive motor drives the lead screw to rotate, the drive block is fixedly connected to the outside of the switching chamber, and the side of the drive block away from the sliding groove is connected to the locking drive assembly.

[0017] Preferably, the locking drive assembly includes a high-speed motor and a positioning cylinder. The high-speed motor is installed inside the drive block, and a drive gear is installed on the shaft of the high-speed motor. The positioning cylinder is fixedly connected to the outside of the drive block. One end of the positioning cylinder is open, and the other end has a positioning opening with a diameter larger than that of the screwdriver bit. A rotating sleeve is rotatably connected inside the positioning cylinder. Rotary rings are fixedly connected to both ends of the rotating sleeve. The rotating rings are rotatably connected to the inside of the positioning cylinder. A toothed ring is fixedly connected to the middle of the positioning cylinder. The positioning cylinder has a drive groove, and the drive gear and the toothed ring mesh with each other through the drive groove. Miniature electric push rods are fixedly installed on both sides inside the rotating sleeve. Arc-shaped toothed plates are installed on the telescopic ends of the miniature electric push rods. The bit holder is cylindrical. Racks are arranged in a circumferential array along the axial direction on the outside of the bit holder. Under the push of the miniature electric push rods, the tooth grooves on the inner sides of the arc-shaped toothed plates on both sides can engage with the racks on the outside of the bit holder. A guide block is fixedly provided on the outside of the arc-shaped toothed plates. The guide block can slide telescopically relative to the rotating sleeve.

[0018] Preferably, the central control unit is further configured to receive torque and angle information fed back by the locking drive assembly, and determine whether the tightening quality is qualified based on this information. A sliding retractable door is provided on one side of the switching room.

[0019] A method for a vision-guided automatic batch screw tightening system includes the following steps: S1. Visual inspection step: The visual guidance subsystem captures images of the workpiece, identifies the position and angle of the screw holes and the specific type of the screw head in the images, and sends these identification results to the central control unit. S2. Screwdriver bit selection steps: The central control unit matches the corresponding screwdriver bit from the screwdriver bit library according to the identified screw head type; then it controls the rotary drive to work, drives the sun gear to rotate, and through the planetary gear transmission, precisely rotates the bit holder with the target screwdriver bit to the tool change position at the working slot. S3. Screwdriver bit replacement steps: The central control unit controls the drive motor to run, which drives the drive block and locking drive assembly to move along the sliding groove through the lead screw, so that the open end of the positioning cylinder is aligned with the bit holder at the tool changing position; then, the micro electric push rod is controlled to extend, pushing the arc-shaped toothed plate to engage and lock with the rack outside the bit holder; then, the high-speed motor is controlled to drive the rotating sleeve and the locked bit holder to rotate at high speed through gear transmission, completing the screw tightening operation; S4. Tightening execution steps: Based on the coordinate information provided by the vision system, the multi-degree-of-freedom robot moves the entire screwdriver bit library and locking drive assembly to precisely align the screwdriver bits with the target screw hole. S5. Quality monitoring steps: During the tightening process, the central control unit monitors and records the actual torque and rotation angle data fed back by the locking drive component in real time. After tightening is completed, these data are compared with the preset standard parameters to automatically determine whether the tightening quality is qualified.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are: The present invention relates to a vision-guided automatic screw tightening system with bit changing mechanism. This system uses an industrial camera and lighting source to capture clear images of the workpiece within a switching chamber. The vision guidance subsystem accurately identifies the screw hole position, angle, and screw type, providing precise data support for subsequent operations. The rotating switching assembly and bit holder within the switching chamber enable rapid replacement of different sized screw bits through precise rotation and positioning. The entire process requires no manual intervention, improving production continuity.

[0021] Second, the locking drive assembly of this invention utilizes a miniature electric push rod, a high-speed motor, and an arc-shaped toothed plate to achieve precise locking and high-speed rotation of the screwdriver bit, ensuring the stability and reliability of the tightening process. The central control unit monitors torque and angle information in real time and automatically determines whether the tightening quality is up to standard, improving the accuracy and efficiency of the tightening operation.

[0022] III. The multi-degree-of-freedom robot of this invention moves the entire system to the target position. Each step of the operation is guided by a vision guidance system, ensuring high precision and efficiency in the assembly process. The overall principle is as follows: the system first acquires workpiece images and identifies screw hole information through the vision guidance subsystem. The central control unit selects a suitable screwdriver bit from the screwdriver bit library based on this information and precisely adjusts the target screwdriver bit to the working position via a rotary drive component. Next, the drive motor guides the locking drive component into place via a lead screw drive, and a miniature electric push rod locks the screwdriver bit. Then, the multi-degree-of-freedom robot precisely guides the screwdriver bit to the screw hole position. Finally, a high-speed motor drives the screwdriver bit to complete the tightening operation, and real-time monitoring ensures the tightening quality. The sliding telescopic door closes during non-operational periods to protect the internal precision mechanisms, extend the equipment's service life, and facilitates switching to open the interior for screwdriver bit replacement. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall external structure of the present invention; Figure 2 For the present invention Figure 1 A magnified structural diagram at point B; Figure 3This is a schematic diagram of the internal structure of the switching room of the present invention; Figure 4 For the present invention Figure 3 A magnified structural diagram at point A; Figure 5 This is a side sectional view of the screwdriver bit magazine of the present invention; Figure 6 This is a schematic diagram of the positioning cylinder and its internal structure according to the present invention; Figure 7 This is a schematic diagram of the external structure of the rotary switching component of the present invention; Figure 8 This is a cross-sectional view of the rotary switching component of the present invention; Figure 9 This is a schematic diagram of the unfolded structure of the tightening actuator of the present invention; Figure 10 This is a flowchart illustrating the execution method of the visually guided automatic batch screw tightening system of the present invention.

[0024] The components include: 1. Switching chamber; 2. Industrial camera; 3. Light source; 6. Working slot; 8. Gear ring; 9. Sun gear; 10. Planetary gear; 11. Bit holder; 12. Insertion slot; 15. Frustum-shaped magnetic holder; 17. Stepper motor; 18. Drive shaft; 19. Absolute encoder; 20. U-shaped frame; 22. Sliding groove; 23. Lead screw; 24. Drive motor; 25. Drive block; 27. Multi-DOF robot; 29. ​​High-speed motor; 30. Drive gear; 31. Positioning cylinder; 32. Positioning port; 33. Rotating sleeve; 34. Rotary ring; 35. Gear ring; 36. Drive slot; 37. Miniature electric actuator; 38. Arc-shaped toothed plate; 39. Guide block; 40. Screwdriver bit. Detailed Implementation

[0025] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0026] Example 1: Please see Figure 1-10 The present invention provides a technical solution: A vision-guided automatic screw tightening system includes a vision guidance subsystem for acquiring workpiece images and identifying the position, angle, and type of screw head of the screw hole; it also includes a screwdriver bit library, a screwdriver bit quick-change mechanism, and a tightening actuator. The screwdriver bit library stores various screwdriver bits of different specifications; the tightening actuator includes a multi-degree-of-freedom robot 27 and a locking drive assembly; and a central control unit electrically connected to the vision guidance subsystem, the screwdriver bit quick-change mechanism, and the tightening actuator.

[0027] Through the above technical solution, this system first acquires workpiece images through a vision guidance subsystem and automatically identifies the position, angle, and screw head type of the screw holes. The central control unit matches the corresponding screwdriver bit from the screwdriver bit library based on the identification results and controls the multi-degree-of-freedom robot 27 in the tightening actuator to move to the target position. Subsequently, the screwdriver bit quick-change mechanism automatically completes the screwdriver bit replacement, and finally, the locking drive component performs precise tightening, achieving full automation from identification, screwdriver bit selection, positioning to tightening.

[0028] The vision guidance subsystem includes an industrial camera 2 and an illumination source 3. The industrial camera 2 and the illumination source 3 are installed at the end of the switching chamber 1 away from the drive end of the multi-degree-of-freedom robot 27. The mapping relationship between its coordinate system and the coordinate system of the tightening actuator is established through hand-eye calibration. This vision guidance system achieves hand-eye calibration between the coordinate system of the industrial camera 2 and the coordinate system of the multi-degree-of-freedom robot 27 through the following steps: a) Control the multi-degree-of-freedom robot 27 to move the calibration plate to multiple different poses; b) Acquire images of the calibration plate in each pose using industrial camera 2; c) The central control unit calculates the transformation matrix between the industrial camera 2 coordinate system and the multi-degree-of-freedom robot 27 coordinate system based on the image and the parameters of each joint of the robot.

[0029] Through the above technical solution, the industrial camera 2, with the assistance of the illumination source 3, acquires clear working images. By establishing the mapping relationship between the camera coordinate system and the tightening actuator coordinate system through hand-eye calibration, the two-dimensional image coordinates identified by the vision system can be accurately converted into positioning data in the robot's three-dimensional space, thereby guiding the robot to move precisely to the screw hole position and effectively compensating for the workpiece's positional deviation.

[0030] The screwdriver bit magazine includes a switching chamber 1, inside which a rotary switching component and multiple sets of detachable bit holders 11 are installed; the rotary switching component is located at one end inside the switching chamber 1, and a working slot 6 is opened at the other end.

[0031] Through the above technical solution, the screwdriver bit storage switching chamber 1 is equipped with a rotary switching component and multiple detachable bit holders 11. When it is necessary to change the screwdriver bit, the rotary switching component drives the bit holder 11 to rotate, accurately transferring the target bit holder 11 to the working slot 6, preparing for the screwdriver bit quick change mechanism to grab it, and realizing the centralized storage and quick retrieval of multiple screwdriver bits.

[0032] The rotary switching assembly includes a gear ring 8, with a sun gear 9 located at the center of the gear ring 8. A rotary drive unit that drives the sun gear 9 to rotate is installed at the center of the outside of the switching chamber 1. Several planetary gears 10 are rotatably meshed between the sun gear 9 and the gear ring 8. The center of the working slot 6 is on a virtual circumference determined by the centers of the planetary gears 10. A bit holder 11 is installed at the center of one side of the planetary gears 10. The bit holder 11 is used to store screwdriver bits 40. The screwdriver bits 40 are magnetically fixed to the inside of the bit holder 11. The bit holder 11 is provided with a magnetic block inside for magnetically fixing the insertion end of the screwdriver bits 40. The bit holder 11 is provided with an insertion slot 12 inside. The insertion slot 12 and the insertion end of the screwdriver bits 40 are matched with a specific shape to prevent the insertion slot 12 and the screwdriver bits 40 from rotating relative to each other.

[0033] Through the above technical solution, the rotating drive component drives the sun gear 9 to rotate, and the sun gear 9 drives the surrounding planetary gears 10 to revolve within the gear ring 8. Since the center of the working slot 6 is located on the circumference of the planetary gears 10, by controlling the rotation angle of the sun gear 9, the planetary gears 10 and the bit holder 11 with the target screwdriver bit installed can be precisely rotated to the position aligned with the working slot 6. The screwdriver bit cooperates with the bit holder 11 through a specially shaped insertion slot 12 to prevent the bit holder 11 from rotating, and is attracted and fixed by a magnetic block to ensure stability during storage and transportation.

[0034] The bit holder 11 is magnetically engaged with the planetary gear 10. The planetary gear 10 is fixedly provided with a frustum-shaped magnetic holder 15 near the center. The bottom of the bit holder 11 is provided with a magnetic groove that engages with the frustum-shaped magnetic holder 15. The frustum-shaped magnetic holder 15 can be a quadrangular frustum or a hexagonal frustum structure.

[0035] Through the above technical solution, the bit holder 11 is attracted and connected to the frustum-shaped magnetic seat 15 on the planetary gear 10 through the magnetic groove at the bottom; the frustum-shaped structure realizes automatic centering and precise positioning, and uses magnetic force to provide a firm connection, which not only ensures the reliability of the bit holder 11 when rotating at high speed, but also facilitates quick manual disassembly and replacement, meeting the needs of screwdriver bit model replacement and maintenance.

[0036] Example 2: Please see Figure 1-10 Furthermore, in conjunction with Embodiment 1, the rotary drive component includes a stepper motor 17, which is installed outside the switching chamber 1. A drive shaft 18 is provided in the middle of the sun gear 9. The rotating shaft of the stepper motor 17 passes through the center of the switching chamber 1 and is connected to the drive shaft 18 of the internal sun gear 9. An absolute encoder 19 is installed on the rotating shaft of the stepper motor 17. A U-shaped frame 20 is fixedly installed outside the switching chamber 1. The stepper motor 17 is fixedly connected to the U-shaped frame 20. The drive end of the multi-degree-of-freedom robot 27 is fixedly connected to the outside of the U-shaped frame 20 for moving the U-shaped frame 20 to adjust its position.

[0037] Through the above technical solution, the stepper motor 17 serves as the power source, precisely driving the sun gear 9 to rotate via the drive shaft 18; the absolute encoder 19 provides real-time feedback on the rotation angle, ensuring that the system can accurately control the position of each planetary gear 10 and bit holder 11; the entire screwdriver bit library is mounted at the end of the multi-degree-of-freedom robot 27 via a U-shaped frame 20, enabling the robot to carry the entire screwdriver bit library and move in three-dimensional space, achieving flexible adjustment of the working position.

[0038] A sliding groove 22 is provided on the inner wall of the switching chamber 1. A drive block 25 is slidably connected inside the sliding groove 22. A lead screw 23 is rotatably installed inside the sliding groove 22. A drive motor 24 is fixedly installed at one end of the sliding groove 22. The drive motor 24 drives the lead screw 23 to rotate. The drive block 25 is fixedly connected to the outside of the switching chamber 1. The side of the drive block 25 away from the sliding groove 22 is connected to the locking drive assembly.

[0039] Through the above technical solution, the drive motor 24 drives the lead screw 23 to rotate, pushing the drive block 25 to move linearly along the sliding groove 22; through precise linear transmission, the locking drive assembly connected to the drive block 25 can accurately approach or move away from the bit holder 11 located at the working slot 6, completing the position docking during the bit changing process, and preparing for the subsequent screw bit gripping and tightening operation.

[0040] The locking drive assembly includes a high-speed motor 29 and a positioning cylinder 31. The high-speed motor 29 is installed inside the drive block 25, and a drive gear 30 is mounted on the shaft of the high-speed motor 29. The positioning cylinder 31 is fixedly connected to the outside of the drive block 25. One end of the positioning cylinder 31 is open, and the other end has a positioning opening 32 with a diameter larger than that of a screwdriver bit 40. A rotating sleeve 33 is rotatably connected inside the positioning cylinder 31. Rotating rings 34 are fixedly connected to both ends of the rotating sleeve 33 and are rotatably connected to the inside of the positioning cylinder 31. A toothed ring 35 is fixedly connected to the middle of the positioning cylinder 31. The positioning cylinder 31 has a drive opening. The drive gear 30 and the gear ring 35 pass through the drive groove 36 and mesh with each other; a miniature electric push rod 37 is fixedly installed on both sides inside the rotating sleeve 33, and an arc-shaped toothed plate 38 is installed on the telescopic end of the miniature electric push rod 37; the bit holder 11 is cylindrical, and racks are arranged in a circumferential array along the axial direction on the outside of the bit holder 11. Under the push of the miniature electric push rod 37, the tooth grooves on the inner side of the arc-shaped toothed plate 38 on both sides can engage with the racks on the outside of the bit holder 11. A guide block 39 is fixedly provided on the outer side of the arc-shaped toothed plate 38, and the guide block 39 can slide telescopically relative to the rotating sleeve 33.

[0041] With the above technical solution, after the positioning cylinder 31 is aligned with the bit holder 11, the miniature electric push rod 37 pushes the two arc-shaped toothed plates 38 on both sides to move inward, so that their tooth grooves are tightly engaged with the toothed rack outside the bit holder 11, and the bit holder 11 is firmly locked; the screwdriver bit is picked up, and then the locking drive assembly drives the bit holder 11 to move closer to the working slot 6, so that the screwdriver bit 40 of the bit holder 11 extends out of the working slot 6, realizing the position docking during the bit change process, and preparing for the subsequent tightening operation; Subsequently, the high-speed motor 29 drives the gear ring 35 through the drive gear 30, which in turn drives the rotating sleeve 33 and the locked bit holder 11 to rotate at high speed; the guide block 39 ensures that the arc-shaped toothed plate 38 can extend and retract smoothly, and the positioning port 32 at the front end of the positioning cylinder 31 provides guidance and support for the screwdriver bit 40, ensuring the stability of the tightening process.

[0042] The central control unit is also used to receive torque and angle information fed back from the locking drive assembly, and to determine whether the tightening quality is qualified based on the information. A sliding retractable door is installed on one side of the switching room 1.

[0043] Through the above technical solution, the locking drive component monitors torque and angle data in real time during the tightening process and feeds it back to the central control unit. The system compares these measured data with preset standards and automatically judges whether the tightening quality is qualified. The sliding telescopic door on the side of the switching chamber 1 is closed during non-operation periods to effectively prevent dust and foreign objects from entering, protect the internal precision mechanism, and extend the service life of the equipment. The interior of the switching chamber 1 can be opened by sliding the telescopic door to facilitate the replacement of the screwdriver bits 40 inside the switching chamber 1.

[0044] A vision-guided automatic batch screw tightening method includes the following steps: S1. Visual inspection step: The visual guidance subsystem captures images of the workpiece, identifies the position and angle of the screw holes and the specific type of the screw head in the images, and sends these identification results to the central control unit. S2. Screwdriver bit selection steps: The central control unit matches the corresponding screwdriver bit from the screwdriver bit library according to the identified screw head type; then controls the rotary drive to work, drives the sun gear 9 to rotate, and precisely rotates the bit holder 11 with the target screwdriver bit to the tool change position at the working slot 6 through the planetary gear transmission. S3. Screwdriver bit replacement steps: The central control unit controls the drive motor 24 to run, which drives the drive block 25 and the locking drive assembly to move along the sliding groove 22 through the lead screw 23, so that the open end of the positioning cylinder 31 is aligned with the bit holder 11 at the tool changing position; then the micro electric push rod 37 is controlled to extend, pushing the arc-shaped toothed plate 38 to mesh and lock with the rack outside the bit holder 11; then the high-speed motor 29 is controlled to drive the rotating sleeve 33 and the locked bit holder 11 to rotate at high speed through gear transmission, completing the screw tightening operation; S4. Tightening execution steps: Based on the coordinate information provided by the vision system, the multi-degree-of-freedom robot 27 drives the entire screwdriver bit library and locking drive assembly to move, accurately aligning the screwdriver bits with the target screw hole. S5. Quality monitoring steps: During the tightening process, the central control unit monitors and records the actual torque and rotation angle data fed back by the locking drive component in real time. After tightening is completed, these data are compared with the preset standard parameters to automatically determine whether the tightening quality is qualified.

[0045] The working principle of this vision-guided automatic screw tightening system is as follows: First, the vision guidance subsystem acquires an image of the workpiece and identifies the position, angle, and type of screw hole and screw head. Based on this, the central control unit matches the corresponding screw bit from the screw bit library and controls the rotary drive component to precisely rotate the target bit holder 11 to the working slot 6 via a planetary gear system. Then, the drive motor 24, through the lead screw 23, drives the locking drive assembly to move along the sliding groove 22, aligning the positioning cylinder 31 with the bit holder 11. The miniature electric push rod 37 drives the arc-shaped toothed plate 38 to engage and lock with the external rack of the bit holder 11. Finally, the drive motor 24 is reversed, causing the lead screw 23 to drive the drive block 25 and the locking drive assembly along the sliding groove 22. In reverse movement, the locking drive assembly moves the bit holder 11 towards the working slot 6, separating the bit holder 11 from the frustum-shaped magnetic base 15. The screwdriver bits 40 on the bit holder 11 extend out of the working slot 6. Further control is applied to the high-speed motor 29, which, through gear transmission, drives the rotating sleeve 33 and the locked bit holder 11 to rotate at high speed. The bit holder 11 drives the internal screwdriver bits 40 to rotate. Then, the multi-degree-of-freedom robot 27 moves the entire device to the target position. The high-speed motor 29, through gear set, drives the rotating sleeve 33 and screwdriver bits to rotate at high speed to complete the tightening. During this process, the central control unit monitors torque and angle data in real time and automatically judges the tightening quality. Simultaneously, the sliding telescopic door effectively protects the internal mechanisms. This system achieves full-process automation from identification, batch selection, positioning, batch changing to tightening and quality monitoring, effectively solving the problems of inconvenient batch changing, inaccurate positioning, and lack of quality monitoring in traditional equipment. It significantly improves the efficiency and reliability of multi-specification screw assembly.

[0046] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A vision-guided automatic batch screw tightening system, comprising a vision guidance subsystem, characterized in that: The vision guidance subsystem is used to acquire workpiece images and identify the position, angle, and type of screw head of screw holes; it also includes a screwdriver bit library, a screwdriver bit quick-change mechanism, and a tightening actuator. The screwdriver bit library is used to store various screwdriver bits of different specifications; the tightening actuator includes a multi-degree-of-freedom robot (27) and a locking drive assembly; it also includes a central control unit, which is electrically connected to the vision guidance subsystem, the screwdriver bit quick-change mechanism, and the tightening actuator, respectively.

2. The visually guided automatic batch screw tightening system according to claim 1, characterized in that: The visual guidance subsystem includes an industrial camera (2) and an illumination source (3). The industrial camera (2) and the illumination source (3) are installed in the switching room (1) away from the end connected to the multi-degree-of-freedom robot (27). The system achieves hand-eye calibration between the coordinate system of the industrial camera (2) and the coordinate system of the multi-degree-of-freedom robot (27) through the following steps: a) Control the multi-degree-of-freedom robot (27) to move the calibration plate to multiple different poses; b) Acquire images of the calibration plate in each pose using an industrial camera (2); c) Based on the image and the parameters of each joint of the robot, the central control unit calculates the transformation matrix between the coordinate system of the industrial camera (2) and the coordinate system of the multi-degree-of-freedom robot (27).

3. The visually guided automatic batch screw tightening system according to claim 1, characterized in that: The screwdriver bit magazine includes a switching chamber (1), inside which a rotary switching component and multiple sets of detachable bit holders (11) are provided; the rotary switching component is located at one end inside the switching chamber (1), and a working slot (6) is opened at the other end.

4. The visually guided automatic batch screw tightening system according to claim 3, characterized in that: The rotary switching assembly includes a gear ring (8), with a sun gear (9) located at the center inside the gear ring (8). A rotary drive unit that drives the sun gear (9) to rotate is installed at the center of the outside of the switching chamber (1). Several planetary gears (10) are rotatably meshed between the sun gear (9) and the gear ring (8). The center of the working slot (6) is on a virtual circumference determined by the centers of the several planetary gears (10). A bit holder (11) is installed at the center of one side of the planetary gears (10). The bit holder (11) is used to store screwdriver bits (40). The screwdriver bits (40) are magnetically fixed inside the bit holder (11). A magnetic block is provided inside the bit holder (11) to magnetically fix the plug end of the screwdriver bits (40). A plug groove (12) is provided inside the bit holder (11). The plug groove (12) and the plug end of the screwdriver bits (40) are matched by a specific shape to prevent the plug groove (12) and the screwdriver bits (40) from rotating relative to each other.

5. The visually guided automatic batch screw tightening system according to claim 4, characterized in that: The bit holder (11) is magnetically engaged with the planetary gear (10). The planetary gear (10) is fixedly provided with a frustum-shaped magnetic seat (15) near the center position. The bottom of the bit holder (11) is provided with a magnetic groove that engages with the frustum-shaped magnetic seat (15).

6. The visually guided automatic batch screw tightening system according to claim 4, characterized in that: The rotary drive includes a stepper motor (17), which is installed outside the switching chamber (1). A drive shaft (18) is provided in the middle of the sun gear (9). The rotating shaft of the stepper motor (17) passes through the center of the switching chamber (1) and is connected to the drive shaft (18) of the sun gear (9). An absolute encoder (19) is installed on the rotating shaft of the stepper motor (17). A U-shaped frame (20) is fixedly installed outside the switching chamber (1). The stepper motor (17) is fixedly connected to the U-shaped frame (20). The drive end of the multi-degree-of-freedom robot (27) is fixedly connected to the outside of the U-shaped frame (20) to drive the U-shaped frame (20) to move for position adjustment.

7. The visually guided automatic batch screw tightening system according to claim 3, characterized in that: The inner wall of the switching chamber (1) is provided with a sliding groove (22). A drive block (25) is slidably connected inside the sliding groove (22). A lead screw (23) is rotatably installed inside the sliding groove (22). A drive motor (24) is fixedly installed at one end of the sliding groove (22). The drive motor (24) drives the lead screw (23) to rotate. The drive block (25) is fixedly connected to the outside of the switching chamber (1). The side of the drive block (25) away from the sliding groove (22) is connected to the locking drive assembly.

8. The visually guided automatic batch screw tightening system according to claim 7, characterized in that: The locking drive assembly includes a high-speed motor (29) and a positioning cylinder (31). The high-speed motor (29) is installed inside the drive block (25). A drive gear (30) is installed on the shaft of the high-speed motor (29). The positioning cylinder (31) is fixedly connected to the outside of the drive block (25). One end of the positioning cylinder (31) is open, and the other end has a positioning port (32) with a diameter larger than that of a screwdriver bit (40) in the middle. A rotating sleeve (33) is rotatably connected inside the positioning cylinder (31). Rotary rings (34) are fixedly connected to both ends of the rotating sleeve (33). The rotating rings (34) are rotatably connected to the inside of the positioning cylinder (31). A toothed ring (35) is fixedly connected to the middle of the positioning cylinder (31). The positioning cylinder (31) has a toothed ring (35) in the middle. Drive slot (36), drive gear (30) and gear ring (35) pass through drive slot (36) and mesh with each other; micro electric push rods (37) are fixedly installed on both sides inside the rotating sleeve (33), and arc-shaped toothed plates (38) are installed on the telescopic end of the micro electric push rods (37); the bit holder (11) is cylindrical, and racks are distributed in a circumferential array along the axial direction on the outside of the bit holder (11). Under the push of the micro electric push rods (37), the tooth grooves on the inner side of the arc-shaped toothed plates (38) on both sides can engage with the racks on the outside of the bit holder (11). Guide blocks (39) are fixedly provided on the outer side of the arc-shaped toothed plates (38), and guide blocks (39) can slide telescopically relative to the rotating sleeve (33).

9. The visually guided automatic batch screw tightening system according to claim 3, characterized in that: The switching chamber (1) has a sliding telescopic door on one side. The central control unit is also used to receive the torque and angle information fed back by the locking drive assembly, and to determine whether the tightening quality is qualified based on the information.

10. A method for an automatic batch screw tightening system based on visual guidance according to any one of claims 1-9, characterized in that... Includes the following steps: S1. Visual inspection step: The visual guidance subsystem captures images of the workpiece, identifies the position and angle of the screw holes and the specific type of the screw head in the images, and sends these identification results to the central control unit. S2. Screwdriver bit selection steps: The central control unit matches the corresponding screwdriver bit from the screwdriver bit library according to the identified screw head type; then controls the rotary drive to work, drives the sun gear (9) to rotate, and precisely rotates the bit holder (11) with the target screwdriver bit to the tool change position at the working slot (6) through the planetary gear transmission. S3. Screwdriver bit replacement steps: The central control unit controls the drive motor (24) to run, and drives the drive block (25) and locking drive assembly to move along the sliding groove (22) through the lead screw (23), so that the open end of the positioning cylinder (31) is aligned with the bit holder (11) at the tool changing position; then, the micro electric push rod (37) is controlled to extend, pushing the arc-shaped toothed plate (38) to mesh and lock with the rack outside the bit holder (11); then the drive motor (24) is controlled to reverse, so that the lead screw (23) drives the drive block (25) and locking drive assembly to move along the sliding groove (22), so that the open end of the positioning cylinder (31) is aligned with the bit holder (11) at the tool changing position; then the micro electric push rod (37) is controlled to extend, pushing the arc-shaped toothed plate (38) to mesh and lock with the rack outside the bit holder (11); then the drive motor (24) is controlled to reverse, so that the lead screw (23) drives the drive block (25) and locking drive assembly to move along the sliding groove (22), so that the open end of the positioning cylinder (31) is aligned with the bit holder (11) at the tool changing position; then the micro electric push rod (24 ... micro electric push rod (25) to extend, pushing the micro electric push rod (24) to extend, pushing the micro electric push rod (25) to extend, pushing the micro electric push rod (24) to extend, pushing the micro electric push rod (25) to extend The drive block (25) and the locking drive assembly move in the opposite direction along the sliding groove (22). The locking drive assembly drives the bit holder (11) to move towards the working slot (6). The bit holder (11) separates from the frustum-shaped magnetic seat (15). The screwdriver bit (40) on the bit holder (11) extends out of the working slot (6) for easy operation. The high-speed motor (29) is further controlled to drive the rotating sleeve (33) and the locked bit holder (11) to rotate at high speed through gear transmission to complete the screw tightening operation. S4, Tightening execution steps: The multi-degree-of-freedom robot (27) moves the entire screwdriver bit library and locking drive assembly according to the coordinate information provided by the vision system, and accurately aligns the screwdriver bit with the target screw hole; S5. Quality monitoring steps: During the tightening process, the central control unit monitors and records the actual torque and rotation angle data fed back by the locking drive component in real time. After tightening is completed, these data are compared with the preset standard parameters to automatically determine whether the tightening quality is qualified.

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