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] The present invention relates to the field of bolt tightening devices, and particularly to a bolt tightening device based on visual positioning. Background Art

[0002] Bolt connection is a very common component connection method in industry. Currently, bolt tightening can be divided into three methods: manual, semi-automatic, and full-automatic. In the manual method, workers hold a wrench to perform the tightening operation, which not only has a large working intensity but also is difficult to control the tightening torque. In the semi-automatic method, workers hold a pneumatic or electric tightening gun to perform the tightening operation, which can effectively reduce the workload and better control the tightening torque. In the full-automatic method, a robot or a special mechanism drives the tightening gun to perform the operation without manual intervention, which can significantly improve the bolt tightening efficiency and quality.

[0003] The current full-automatic bolt tightening devices are mainly aimed at the bolt connections of specific specifications of specific components. To meet the customized production needs of multi-variety and small-batch products required in the intelligent manufacturing environment and personalized consumption, CN116765803A discloses an intelligent bolt tightening control device, which includes a robot, an industrial camera, a servo motor, etc. By using the servo motor to hold different bolt sleeves, it can realize automatic sleeve replacement, automatic identification of the tightening position, and automatic execution of the tightening operation to meet the intelligent bolt tightening needs of various components; However, for the intelligent bolt tightening control device disclosed in CN116765803A, the servo motor and the end of the robot are only connected through a connecting plate. When tapping a self-tapping bolt into a blind hole, only the robot applies a downward pressure, which cannot ensure that the servo pressing shaft provides sufficient downward pressure on the self-tapping bolt, resulting in the self-tapping bolt bouncing during the tapping process, affecting the stability of the bolt tapping process. Moreover, there is a lack of detection devices for detecting whether the bolt sleeve carries a screw and detecting the depth of the bolt tapping. The rigid connection between the servo motor and the bolt sleeve will transmit vibrations to the entire device, affecting the operation stability of the device. Summary of the Invention

[0004] The object of the present invention is to provide a bolt tightening device in view of the corresponding deficiencies of the prior art. The servo motor of this device is installed on an installation bracket, and a lifting cylinder provides a downward pressure on the installation bracket to provide sufficient downward pressure for the servo motor. A displacement sensor is provided as a detection device for detecting whether the bolt sleeve carries a screw and detecting the depth of the bolt tapping, and a coupling is provided to absorb vibrations and impacts.

[0005] The object of the present invention is achieved by the following solutions: A bolt tightening device based on vision positioning comprises a robot, a mounting bracket is provided at the end of the arm of the robot, a visual camera for collecting image information of the bolt installation position is installed on the mounting bracket through a connecting bracket, the mounting bracket is a T-shaped bracket, a lifting cylinder is installed 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 on a guide rail provided on the vertical plate of the mounting bracket, the sliding seat is U-shaped, a servo motor is installed on the upper plate of the sliding seat, and a coupling is installed on the lower plate of the sliding seat, the output shaft of the servo motor is connected to the tightening shaft through the coupling, and a bolt sleeve is fixedly provided 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 provided between the mounting bracket and the sliding seat; the robot, visual camera, lifting cylinder, displacement sensor, and servo motor are all electrically connected to the control module.

[0006] Preferably, the sliding seat is provided with a homing device electrically connected to the control module, including a proximity switch and a brake cylinder; The output shaft of the servo motor is provided with a radial extension portion, and when the radial extension portion rotates to the detection area of the proximity switch, the proximity switch sends a signal to the control module; The proximity switch is used to control the brake cylinder. When the piston rod of the brake cylinder is extended, the circumferential rotation of the radial extension portion is blocked, and the bolt sleeve is returned to its circumferential position.

[0007] Preferably, the proximity switch is mounted on the upper end surface of the sliding seat lower plate, the brake cylinder is mounted on the lower end surface of the sliding seat upper plate, and the piston rod of the brake cylinder extends downward to block the circumferential rotation of the radially extending portion when extended.

[0008] Preferably, a piston rod bracket is installed on the lower plate of the sliding seat, and the piston rod bracket is provided with a hole for the radial extension part to rotate through and a through hole for the brake cylinder piston rod to pass through. When the brake cylinder is extended, the piston rod passes through the through hole to block the circumferential rotation of the radial extension part.

[0009] Preferably, the displacement sensor is a pull-wire displacement sensor, the housing of the pull-wire displacement sensor is fixed on the mounting bracket, and the end of the pull-wire displacement sensor is fixed on the sliding seat.

[0010] Preferably, the free end of the bolt sleeve is magnetic and is provided with a positioning step that cooperates with the bolt pan head for picking up the bolt.

[0011] Preferably, the depth of the positioning step is the same as the thickness of the bolt pan head.

[0012] The beneficial effects of the present invention are as follows: By collaborating with a vision camera and a robot, the system can collect component images in real time and feedback them to the control module, achieving precise identification and dynamic positioning compensation of bolt holes. Combining with the multi-degree-of-freedom motion characteristics of the robot, it can quickly locate, significantly improving the adaptability of the device to different production scenarios and meeting various production requirements.

[0013] The lifting cylinder is used to drive the mounting bracket to press down along the guide plate, providing a controllable axial pressing force for the servo motor. Compared with the single-robot pressing method, this structure effectively solves the problem of bouncing caused by insufficient downward pressure during the tapping of self-tapping bolts, ensuring the stable meshing of the bolt thread and the workpiece hole position.

[0014] The rope displacement sensor monitors the relative displacement between the mounting bracket and the sliding seat in real time, accurately detecting whether the bolt sleeve is carrying a screw and collecting the bolt penetration depth to avoid over-tightening or under-tightening; connecting the servo motor and the tightening shaft through a coupling can effectively absorb the vibration impact generated by high-frequency tightening operations, avoiding the influence of rigid transmission on the accuracy of the robot joints.

[0015] The homing device senses the circumferential position of the bolt sleeve through a proximity switch, controlling the piston rod of the brake cylinder to block the radially extending part, realizing the precise angular reset of the bolt sleeve, which is convenient for picking up bolts on the bolt transmission device.

[0016] By replacing the coupling, the tightening shaft and the bolt sleeve, it can adapt to different bolts and meet the intelligent bolt tightening needs of various components. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of one side of the present invention; Figure 2 is Figure 1 an enlarged schematic diagram of the structure of area A in Figure 3 It is a schematic structural diagram of the other side of the present invention; Figure 4 is Figure 3 an enlarged schematic diagram of the structure of area B in Figure 5 It is a schematic structural diagram of the bolt sleeve in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] As Figures 1 to 5As shown, a bolt tightening device based on vision positioning includes a robot 1, which is a six-joint serial robot. The end of the arm of the robot 1 is provided with a mounting bracket, and a visual camera 3 for collecting image information of the bolt installation position is installed on the mounting bracket through a connecting frame. The mounting bracket is a T-shaped bracket, and the horizontal plate 2 of the mounting bracket is provided with a lifting cylinder 8. 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 the sliding seat 4. The side plates of the sliding seat 4 are slidably fitted on the guide rails 13 provided 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 to provide a controllable axial pressing force for the servo motor. The sliding seat 4 is U-shaped, and the upper plate 9 of the sliding seat 4 is fixedly installed There is a servo motor 5, and a coupling 16 is installed on the lower plate 10 of the sliding seat 4. The outer periphery of the coupling 16 is provided with a mounting flange, and the coupling is installed in the coupling 16 mounting hole 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 servo motor and the tightening shaft are connected by the coupling, which can effectively absorb the vibration impact generated by high-frequency tightening operations, especially the violent vibration generated when the self-tapping bolts are struck into blind holes. The lower end of the tightening shaft 17 is fixed with a bolt sleeve 18 for picking up bolts. The free end of the bolt sleeve 18 is magnetic and is provided with 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.

[0019] 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 displacement sensor 6 is a pull-wire displacement sensor. The housing 24 of the pull-wire displacement sensor is fixed to the vertical plate 12 of the mounting bracket, and the end of the pull-wire 25 of the pull-wire displacement sensor is fixed to the side plate of the sliding seat 4. When tightening the bolt, the displacement sensor 6 accurately detects whether the bolt sleeve carries the screw by monitoring the relative displacement of the mounting bracket and the sliding seat, and collects the penetration depth of the bolt to avoid over-tightening or under-tightening. A return device is provided on the sliding seat 4, including a proximity switch 19 and a brake cylinder 20; the proximity switch 19 is installed on the upper end surface of the lower plate 10 of the sliding seat 4, the brake cylinder 20 is installed on the lower end surface of the upper plate 9 of the sliding seat 4, a radially extending portion 21 is provided on the output shaft 15 of the servo motor 5, the piston rod of the brake cylinder 20 extends downward, and is used to block the circumferential rotation of the radially extending portion 21 when it extends out; when the radially extending portion 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 out, it blocks the circumferential rotation of the radially extending portion 21, and circumferentially returns the bolt sleeve 18. The return device is used for the bolt tightening device to pick up bolts on the bolt conveying mechanism.

[0020] 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 radially extending portion 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 bolts, the piston rod of the brake cylinder 20 extends out and passes through the through hole 23, and blocks the circumferential rotation of the radially extending portion 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 radially extending portion 21.

[0021] The robot 1, the vision camera 3, the lifting cylinder 8, the displacement sensor 6, the servo motor 5, and the return device are all electrically connected to the control module.

[0022] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Without departing from the spirit of the present invention, any modifications made by those skilled in the art fall within the protection scope of the present invention.

Claims

1. A bolt tightening device based on visual positioning, comprising a robot (1), wherein an installation bracket is provided at the end of the arm of the robot (1), and a vision camera (3) for collecting image information of the bolt installation position is installed on the installation bracket through a connecting frame, and is characterized in that: The mounting bracket is a T-shaped bracket. A lifting cylinder (8) is mounted on the cross 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 engaged with a 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 mounted on the upper plate (9) of the sliding seat (4). A coupling (16) is mounted 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 fixedly provided at the lower end of the tightening shaft (17). A displacement sensor (6) for monitoring the relative displacement between 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 visual positioning according to claim 1, wherein: A homing device electrically connected to the control module is provided on the sliding seat (4), including a proximity switch (19) and a brake cylinder (20). A radially extending portion (21) is provided on the output shaft (15) of the servo motor (5). When the radially extending portion (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 radially extending portion (21) to circumferentially home the bolt sleeve (18).

3. The bolt tightening device based on visual positioning according to claim 2, wherein: The proximity switch (19) is mounted on the upper end face of the lower plate (10) of the sliding seat (4). The brake cylinder (20) is mounted 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 radially extending portion (21) when it extends.

4. The bolt tightening device based on visual positioning according to claim 3, wherein: A piston rod bracket (22) is mounted on the lower plate (10) of the sliding seat (4). The piston rod bracket (22) is provided with a clearance for the radially extending portion (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 radially extending portion (21).

5. The bolt tightening device based on visual positioning according to claim 1, characterized in that: The displacement sensor (6) is a cable displacement sensor. The housing (24) of the cable displacement sensor is fixedly provided on the mounting bracket. The end of the cable (25) of the cable displacement sensor is fixedly provided on the sliding seat (4).

6. The bolt tightening device based on visual positioning according to claim 1, characterized in that: The free end of the bolt sleeve (18) has magnetism and is provided with a positioning step (27) for cooperating with the bolt head to pick up the bolt.

7. The bolt tightening device based on visual positioning according to claim 6, wherein: The depth of the positioning step (27) is the same as the thickness of the bolt head.

Images