Bolt tightening device based on visual positioning

Abstract

A bolt tightening device based on visual positioning comprises a robot, a mounting support is arranged at the tail end of an arm of the robot, a visual camera used for collecting bolt mounting position image information is mounted on the mounting support through a connecting frame, the mounting support is a T-shaped support, and a lifting air cylinder is mounted on a transverse plate of the mounting support; a piston rod of the lifting air cylinder extends downwards to be fixedly connected with a sliding seat, the sliding seat is arranged on a guide rail arranged on a vertical plate of the installation support in a sliding fit mode, the sliding seat is in a U shape, a servo motor is installed on an upper plate of the sliding seat, a coupler is installed on a lower plate of the sliding seat, and an output shaft of the servo motor is connected with a tightening shaft through the coupler. A bolt sleeve is fixedly arranged at the lower end of the tightening shaft; a displacement sensor for monitoring the relative displacement of the mounting bracket and the sliding seat is arranged between the mounting bracket and the sliding seat; the robot, the visual camera, the lifting air cylinder, the displacement sensor and the servo motor are all electrically connected with the control module.

Description

Technical Field

[0001] This utility model relates to the field of bolt tightening devices, specifically to a bolt tightening device based on vision positioning. Background Technology

[0002] Bolt connections are a commonly used method for connecting components in industry. Currently, bolt tightening can be divided into three methods: manual, semi-automatic, and fully automatic. In the manual method, workers use hand wrenches to tighten bolts, which is not only physically demanding but also makes it difficult to control the tightening torque. In the semi-automatic method, workers use pneumatic or electric tightening guns to tighten bolts, which effectively reduces workload and allows for better control of the tightening torque. In the fully automatic method, a robot or specialized mechanism drives the tightening gun to perform the operation, eliminating the need for human intervention and significantly improving bolt tightening efficiency and quality.

[0003] Current fully automatic bolt tightening devices are mainly designed for bolt connections of specific specifications for specific components. To adapt to the customized production needs of multi-variety, small-batch products required by intelligent manufacturing environments and personalized consumption, CN116765803A discloses an intelligent bolt tightening control device. This device includes a robot, an industrial camera, and a servo motor. By using the servo motor to grip different bolt sleeves, it achieves automatic sleeve changing, automatic identification of tightening positions, and automatic execution of tightening operations, meeting the intelligent bolt tightening needs of various components.

[0004] However, the intelligent bolt tightening control device disclosed in CN116765803A has a servo motor and robot end effector connected only through a connecting plate. When driving a self-tapping bolt into a blind hole, the robot only applies downward pressure, which cannot guarantee that the servo clamping shaft provides sufficient downward pressure to the self-tapping bolt. This will cause the self-tapping bolt to bounce during the driving process, affecting the stability of the bolt self-tapping process. Furthermore, it lacks a detection device to detect whether the bolt sleeve carries the screw and to detect the bolt driving depth. The rigid connection between the servo motor and the bolt sleeve will transmit vibration to the entire device, affecting the operational stability of the device. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a bolt tightening device. The device includes a servo motor mounted on a mounting bracket, a lifting cylinder providing downward pressure to the mounting bracket to supply sufficient downward pressure to the servo motor, a displacement sensor for detecting whether the bolt sleeve carries a screw, a detection device for detecting the bolt penetration depth, and a coupling for absorbing vibration and impact.

[0006] The purpose of this utility model is achieved through the following approach:

[0007] A vision-based bolt tightening device includes a robot. The robot's arm has a mounting bracket at its end. A vision camera for acquiring bolt installation position image information is mounted on the mounting bracket via a connecting frame. The mounting bracket is a T-shaped bracket. A lifting cylinder is mounted on the horizontal plate of the mounting bracket. The piston rod of the lifting cylinder extends downward and is fixedly connected to a sliding seat. The sliding seat is slidably fitted onto a guide rail on the vertical plate of the mounting bracket. The sliding seat is U-shaped. A servo motor is mounted on the upper plate of the sliding seat, and a coupling is mounted on the lower plate of the sliding seat. The output shaft of the servo motor is connected to a tightening shaft via the coupling. A bolt sleeve is fixedly mounted at the lower end of the tightening shaft.

[0008] A displacement sensor is provided between the mounting bracket and the sliding seat to monitor the relative displacement of the mounting bracket and the sliding seat; the robot, vision camera, lifting cylinder, displacement sensor, and servo motor are all electrically connected to the control module.

[0009] Preferably, the sliding seat is provided with a return device electrically connected to the control module, including a proximity switch and a brake cylinder;

[0010] The servo motor has a radial extension on its output shaft. When the radial extension rotates to the detection area of ​​the proximity switch, the proximity switch sends a signal to the control module.

[0011] The proximity switch is used to control the brake cylinder. When the piston rod of the brake cylinder extends, it blocks the circumferential rotation of the radial extension and returns the bolt sleeve to its circumferential position.

[0012] Preferably, the proximity switch is mounted on the upper end face of the lower plate of the sliding seat, and the brake cylinder is mounted on the lower end face of the upper plate of the sliding seat. The piston rod of the brake cylinder extends downward and, when extended, is used to block the circumferential rotation of the radial extension.

[0013] Preferably, a piston rod bracket is installed on the lower plate of the sliding seat. The piston rod bracket is provided with a clearance for the radial extension to rotate through and a through hole for the brake cylinder piston rod to pass through. When the brake cylinder extends, the piston rod passes through the through hole to block the circumferential rotation of the radial extension.

[0014] Preferably, the displacement sensor is a pull-rope displacement sensor, the housing of which is fixed on the mounting bracket, and the pull-rope end of which is fixed on the sliding seat.

[0015] Preferably, the free end of the bolt sleeve is magnetic and has a positioning step that mates with the bolt pan head for picking up the bolt.

[0016] Preferably, the depth of the positioning step is the same as the thickness of the bolt head.

[0017] The beneficial effects of this utility model are as follows:

[0018] By working in collaboration with a vision camera and a robot, real-time images of components are acquired and fed back to the control module, enabling precise identification and dynamic positioning compensation of bolt hole positions. Combined with the robot's multi-degree-of-freedom motion characteristics, rapid positioning is achieved, significantly improving the device's adaptability to different production scenarios and meeting various production needs.

[0019] The mounting bracket is driven by a lifting cylinder to press down along the guide plate, providing a controllable axial clamping force to the servo motor. Compared to a single robot pressure application method, this structure effectively solves the bouncing problem caused by insufficient downward pressure during the self-tapping screw insertion process, ensuring stable engagement between the bolt thread and the workpiece hole.

[0020] The cable displacement sensor monitors the relative displacement of the mounting bracket and sliding seat in real time, accurately detects whether the bolt sleeve carries the screw, and collects the bolt penetration depth to avoid over-tightening or under-tightening; the servo motor is connected to the tightening shaft through a coupling, which can effectively absorb the vibration and impact generated by high-frequency tightening operations and avoid the impact of rigid transmission on the accuracy of the robot joints.

[0021] The repositioning device senses the circumferential position of the bolt sleeve through a proximity switch and controls the brake cylinder piston rod to block the radial extension, thereby achieving precise angle reset of the bolt sleeve and facilitating bolt pickup on the bolt drive device.

[0022] By changing the coupling, tightening the shaft, and bolt sleeve, it can adapt to different bolts and meet the intelligent bolt tightening needs of various components. Attached Figure Description

[0023] Figure 1 This is a structural diagram of one side of this utility model;

[0024] Figure 2 for Figure 1 Enlarged schematic diagram of the structure of region A in the middle;

[0025] Figure 3 This is a schematic diagram of the structure on the other side of this utility model;

[0026] Figure 4 for Figure 3 Enlarged schematic diagram of the structure of region B in the middle;

[0027] Figure 5 This is a schematic diagram of the bolt sleeve structure used in this application. Detailed Implementation

[0028] like Figures 1 to 5As shown, a vision-based bolt tightening device includes a robot 1, which is a six-joint serial robot. The robot 1 has a mounting bracket at the end of its arm. A vision camera 3 for acquiring bolt installation position images is mounted on the mounting bracket via a connecting frame. The mounting bracket is a T-shaped bracket. A lifting cylinder 8 is mounted on the horizontal plate 2 of the mounting bracket. The piston rod of the lifting cylinder 8 extends downward through the horizontal plate 2 and is fixedly connected to the upper plate 9 of a sliding seat 4. The side plate of the sliding seat 4 slides on a guide rail 13 on the vertical plate 12 of the mounting bracket. Under the action of the lifting cylinder 8, it slides along the axial direction of the lifting cylinder 8. When tightening the bolt, the piston rod of the lifting cylinder 8 gradually extends, providing a controllable axial clamping force to the servo motor. The sliding seat 4 is U-shaped, and the upper plate 9 of the sliding seat 4 is fixedly mounted... A servo motor 5 is provided, and a coupling 16 is installed on the lower plate 10 of the sliding seat 4. The coupling 16 has a mounting flange on its outer periphery. The coupling is installed in the mounting hole of the coupling 16 provided on the lower plate 10 of the sliding seat 4 by bolts. The output shaft 15 of the servo motor 5 is connected to the tightening shaft 17 through the coupling 16. The coupling connects the servo motor and the tightening shaft, which can effectively absorb the vibration and impact generated by high-frequency tightening operations, especially the severe vibration generated when self-tapping screws are driven into blind holes. A bolt sleeve 18 for picking up bolts is fixed at the lower end of the tightening shaft 17. The free end of the bolt sleeve 18 is magnetic and has a positioning step 27 that cooperates with the bolt pan head to facilitate picking up bolts. The depth of the positioning step 27 is the same as the thickness of the bolt pan head. If the depth of the positioning step 27 is too shallow or too deep, it will affect the tightening performance of the bolt.

[0029] A displacement sensor 6 is provided between the mounting bracket and the sliding seat 4 to monitor the relative displacement of the mounting bracket and the sliding seat 4. The displacement sensor 6 is a pull rope displacement sensor. The housing 24 of the pull rope displacement sensor is fixed on the upright plate 12 of the mounting bracket, and the end of the pull rope 25 of the pull rope displacement sensor is fixed on the side plate of the sliding seat 4. When tightening the bolt, the displacement sensor 6 monitors the relative displacement of the mounting bracket and the sliding seat to accurately detect whether the bolt sleeve carries the screw and collects the bolt penetration depth to avoid over-tightening or under-tightening.

[0030] The sliding seat 4 is equipped with a return device, including a proximity switch 19 and a brake cylinder 20. The proximity switch 19 is installed on the upper end face of the lower plate 10 of the sliding seat 4, and the brake cylinder 20 is installed on the lower end face of the upper plate 9 of the sliding seat 4. The output shaft 15 of the servo motor 5 is provided with a radial extension 21. The piston rod of the brake cylinder 20 extends downward and is used to block the circumferential rotation of the radial extension 21 when it extends. When the radial extension 21 rotates to the detection area of ​​the proximity switch 19, the proximity switch 19 sends a signal to the control module. The proximity switch 19 is used to control the brake cylinder 20. When the piston rod of the brake cylinder 20 extends, it blocks the circumferential rotation of the radial extension 21 and returns the bolt sleeve 18 to its circumferential position. The return device is used by the bolt tightening device to pick up the bolt on the bolt conveying mechanism.

[0031] A piston rod bracket 22 is installed on the lower plate 10 of the sliding seat 4. The piston rod bracket 22 is provided with a clearance for the radial extension 21 to rotate through and a through hole 23 for the piston rod of the brake cylinder 20 to pass through. When the bolt tightening device picks up the bolt, the piston rod of the brake cylinder 20 extends and passes through the through hole 23, blocking the circumferential rotation of the radial extension 21 at the clearance. The through hole 23 is used to reduce the torque of the piston rod of the brake cylinder 20 when blocking the radial extension 21.

[0032] The robot 1, vision camera 3, lifting cylinder 8, displacement sensor 6, servo motor 5, and homing device are all electrically connected to the control module.

[0033] The above description is only a preferred embodiment of this utility model and is not intended to limit this utility model. Any modifications made to this utility model by those skilled in the art without departing from the spirit of this utility model shall fall within the protection scope of this utility model.

Claims

1. A bolt tightening device based on vision positioning, comprising a robot (1), wherein the end of the arm of the robot (1) is provided with a mounting bracket, and a vision camera (3) for acquiring bolt installation position image information is mounted on the mounting bracket via a connecting frame, characterized in that: The mounting bracket is a T-shaped bracket. A lifting cylinder (8) is installed on the horizontal plate (2) of the mounting bracket. The piston rod of the lifting cylinder (8) extends downward and is fixedly connected to a sliding seat (4). The sliding seat (4) is slidably fitted on the guide rail (13) provided on the vertical plate (12) of the mounting bracket. The sliding seat (4) is U-shaped. A servo motor (5) is installed on the upper plate (9) of the sliding seat (4). A coupling (16) is installed on the lower plate (10) of the sliding seat (4). The output shaft (15) of the servo motor (5) is connected to a tightening shaft (17) through the coupling (16). A bolt sleeve (18) is fixed at the lower end of the tightening shaft (17). A displacement sensor (6) for monitoring the relative displacement of the mounting bracket and the sliding seat (4) is provided between the mounting bracket and the sliding seat (4); the robot (1), the vision camera (3), the lifting cylinder (8), the displacement sensor (6), and the servo motor (5) are all electrically connected to the control module.

2. The bolt tightening device based on vision positioning as described in claim 1, characterized in that: The sliding seat (4) is provided with a return device electrically connected to the control module, including a proximity switch (19) and a brake cylinder (20). The output shaft (15) of the servo motor (5) is provided with a radial extension (21). When the radial extension (21) rotates to the detection area of ​​the proximity switch (19), the proximity switch (19) sends a signal to the control module. The proximity switch (19) is used to control the brake cylinder (20). When the piston rod of the brake cylinder (20) extends, it blocks the circumferential rotation of the radial extension (21) and returns the bolt sleeve (18) to its circumferential position.

3. The bolt tightening device based on vision positioning as described in claim 2, characterized in that: The proximity switch (19) is installed on the upper end face of the lower plate (10) of the sliding seat (4), and the brake cylinder (20) is installed on the lower end face of the upper plate (9) of the sliding seat (4). The piston rod of the brake cylinder (20) extends downward and is used to block the circumferential rotation of the radial extension (21) when it extends.

4. The bolt tightening device based on vision positioning as described in claim 3, characterized in that: A piston rod bracket (22) is installed on the lower plate (10) of the sliding seat (4). The piston rod bracket (22) is provided with a clearance for the radial extension (21) to rotate through and a through hole (23) for the piston rod of the brake cylinder (20) to pass through. When the brake cylinder (20) extends, the piston rod passes through the through hole (23) to block the circumferential rotation of the radial extension (21).

5. The bolt tightening device based on vision positioning as described in claim 1, characterized in that: The displacement sensor (6) is a pull rope displacement sensor. The housing (24) of the pull rope displacement sensor is fixed on the mounting bracket, and the end of the pull rope (25) of the pull rope displacement sensor is fixed on the sliding seat (4).

6. The bolt tightening device based on vision positioning as described in claim 1, characterized in that: The free end of the bolt sleeve (18) is magnetic and has a positioning step (27) that mates with the bolt pan head for picking up bolts.

7. The bolt tightening device based on vision positioning as described in claim 6, characterized in that: The depth of the positioning step (27) is the same as the thickness of the bolt head.

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