Visual navigation-based large-torque pre-tightening method and device in narrow space

Abstract

The invention relates to a small-space large-torque pre-tightening method and device based on visual navigation. The small-space large-torque pre-tightening device comprises a supporting seat and a cylindrical straight gear set with the axis perpendicular to the supporting seat. The cylindrical gear set comprises a driving gear meshed with the interior of the driven gear ring and an inner hexagonal wrench caliper integrated with the driven gear ring, and a photoelectric baffle shields a photoelectric switch to enable a motor to be powered off so as to guarantee that the wrench caliper does not exceed the stroke limit position of the wrench caliper. According to the large-torque pre-tightening device, traditional outer meshing design is replaced by gear and gear ring inner meshing design, so that the space occupied by the large-torque pre-tightening device is reduced, assembling and pre-tightening in a narrow space are achieved, and pre-tightening torques of a plurality of bolts tend to be consistent and accurate through driving and controlling of the motor; a mechanical arm is driven through visual navigation to convey the large-torque pre-tightening device to a position where manual assembly operation cannot be measured and reached, and collision interference with other equipment and parts in a vehicle is prevented.

Description

Technical Field

[0001] This invention belongs to the field of mechanical assembly in confined spaces, specifically relating to a method and device for high-torque pre-tightening in confined spaces based on visual navigation, and more particularly to a high-torque pre-tightening device based on visual navigation for assembling unmeasurable and unreachable bolts in confined spaces. Background Technology

[0002] In the field of mechanical equipment assembly, equipment is developing towards smaller size, lighter weight, and higher integration. Equipment manufacturing often involves installing multiple components within a small space, requiring not only ensuring the spatial position of the installed parts but also guaranteeing the rigidity and strength of the connections. This presents significant challenges to assembly. Assembly operations in difficult-to-measure and hard-to-reach locations are particularly critical to assembly quality, reliability, and safety, sometimes even posing dangers to operators.

[0003] Taking a certain special vehicle as an example, it is necessary to... Four hexagonal head support bolts with M20mm threads and a 24mm distance between opposite flats are pre-tightened within the space. The mounting space between the base plate and the upper component is 28mm, and a maximum pre-tightening torque of 200Nm is required. The lack of visibility within the mounting space limits the maximum torque that can be manually pre-tightened to 50Nm for the M20mm bolts, and within this confined space, the torque wrench caliper can only rotate a maximum of [missing value]. .

[0004] An existing high-torque bolt wrench for tightening and loosening bolts in confined spaces, used for tightening and loosening bolts between multi-stage blades of axial compressors, employs gear and belt drives. Its maximum preload torque is designed to be 50 Nm. While its small size and light weight make it suitable for bolt preload operations in confined spaces, its belt drive design at the output end suffers from drawbacks: low transmitted and output torque, slippage between the pulley and belt during high-torque preload operations leading to rapid belt wear, and inability to transmit torque effectively. Furthermore, its maximum output torque of 50 Nm is insufficient to meet the 200 Nm preload requirement of a certain special vehicle's M20mm support bolts. Moreover, this design remains at the theoretical design level, with no experimental verification yet.

[0005] Therefore, how to accurately engage the wrench and caliper into the hexagonal head of the bolt, and how to achieve high torque pre-tightening in a small space, have become the difficulties and common problems in assembly in confined spaces.

[0006] Therefore, the invention of a vision-guided high-torque pre-tightening method and device for confined spaces is of great significance and application value for assembly in confined spaces. Summary of the Invention

[0007] This invention provides a visual navigation-based method and device for high-torque pre-tightening in confined spaces. The technical problem to be solved is that current manual assembly operations are difficult to perform due to visual limitations, inaccessible spaces, inaccurate or substandard tightening torque, and the need to operate in confined and dangerous environments.

[0008] In order to solve the above technical problems, the present invention provides a high torque pre-tightening device for confined spaces based on visual navigation, characterized in that it includes: a support base (1) and a cylindrical spur gear set installed on the support base (1), wherein the axis of the cylindrical spur gear set is perpendicular to the support base; The cylindrical spur gear set includes a driven gear ring (9) and a driving gear (10) meshing with it. The driven gear ring (9) and the internal hex wrench caliper are an integral structure; The drive gear (10) is connected to the output shaft of the motor-matched reducer (3) and is axially positioned by the photoelectric baffle (6); The support base (1) has a cylindrical groove in the middle, which is in clearance fit with the outer diameter of the driven gear ring (9) to achieve radial positioning; The cylindrical groove is provided with several raceways in the circumferential direction and has built-in balls (11) to convert sliding friction into rolling friction; The cover plate (2) is fixed to the support base (1) and covers the gear set and the ball bearings; The photoelectric baffle (6) rotates with the drive gear (10) and is used to block the photoelectric switch (8) when the wrench caliper moves to the limit position, triggering the motor to cut off power; The photoelectric switch (8) is mounted on the cover plate (2); The high-torque pre-tightening device is connected to the robotic arm via a flange. An endoscope is installed on the robotic arm to achieve visual navigation. The device visually identifies the position and parts that need to be pre-tightened and moves the high-torque tightening device to the corresponding position, and then engages the hexagonal caliper of the wrench with the bolt that needs to be pre-tightened.

[0009] Furthermore, the cylindrical gear set has a module m=2, and the number of teeth of the driving gear is... Number of teeth on the driven gear ring The reduction ratio i = 3.05.

[0010] Two photoelectric switches are in Distributed on both sides of the drive gear 10 and the photoelectric baffle 6, the limit swing stroke of the hex wrench caliper is ±30°, and the photoelectric baffle (6) rotates ±90° to block the photoelectric switch (8) when the caliper approaches the limit position.

[0011] Furthermore, the number of raceways is 5 sets, the width is 6mm, and the built-in ball bearings (11) have a diameter of 6mm.

[0012] Furthermore, the distance between opposite sides of the hex wrench caliper is 24mm.

[0013] Furthermore, a protective cover (5) is installed on the support base (1) to cover the protruding parts of the photoelectric switch (8), the photoelectric baffle (6) and the drive gear (10).

[0014] A method for high-torque pre-tensioning in confined spaces based on vision navigation, characterized by the following steps: The location of bolts in a confined space is identified and located using an endoscope; The robotic arm is controlled to move to the pre-tightening station carrying the high-torque pre-tightening device. Guide the hex wrench caliper to accurately engage the hex head of the bolt; Start the motor, which drives the wrench caliper to rotate via gear transmission, thus pre-tightening the bolts; When the wrench caliper approaches its limit position, the photoelectric baffle (6) blocks the photoelectric switch (8), and the motor is de-energized; After pre-tightening is completed, the device is released from the bolts, and the robotic arm moves to the next station.

[0015] Furthermore, the endoscope has a guiding accuracy of no less than 0.1mm, enabling precise alignment of the wrench caliper with the hexagonal head of the bolt.

[0016] Furthermore, during the pre-tightening process, the instantaneous stall characteristic of the motor is utilized to enable the motor to output peak torque of 200Nm within 1-2 seconds.

[0017] Furthermore, the device employs a hollow structure and composite materials to achieve a lightweight design.

[0018] Beneficial effects: This invention achieves pre-tightening of the assembled hexagonal bolts by using an internal hex wrench caliper integrated with the driven gear ring 9 through the internal meshing of the driving gear 10 and the driven gear ring 9. The device achieves high torque pre-tightening through the high reduction ratio design of the reducer 3 and the aforementioned gear set, replacing the traditional external meshing design with an internal meshing design of the gear ring. This reduces the space occupied by the high torque pre-tightening device, enabling assembly pre-tightening in confined spaces. The drive and control of the motor 4 ensures that the pre-tightening torque of multiple bolts is nearly consistent and accurate. Visual navigation drives the robotic arm to deliver the high torque pre-tightening device to locations inaccessible to manual assembly operations, preventing collisions and interference with other equipment and components within the vehicle. Attached Figure Description

[0019] Figure 1 A schematic diagram of the overall structure of a vision-guided, high-torque pre-tensioning device in a confined space; Figure 2A schematic diagram showing the photoelectric baffle blocking the photoelectric switch as the wrench caliper of the high-torque preload device is moved to its limit position; Figure 3 Schematic diagram of the transmission mechanism for a high-torque preload device; The components include: 1. Support base; 2. Cover plate; 3. Reducer for motor; 4. Motor; 5. Protective cover; 6. Photoelectric baffle; 7. Pad block; 8. Photoelectric switch; 9. Driven gear ring; 10. Drive gear; 11. Ball bearing. Detailed Implementation

[0020] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below.

[0021] To address the need for high-torque pre-tightening of four M20mm threaded bolts with a 24mm flat-to-flat distance of hexagonal heads within a confined assembly space during the assembly of components for a certain special vehicle, where manual pre-tightening suffers from problems such as unmeasurability, unachievable limits, insufficient and inaccurate pre-tightening force, and inconsistent pre-tightening force on one side of the four support bolts, this invention provides a high-torque pre-tightening device for confined spaces based on visual navigation, combined with... Figures 1 to 3 As shown, the device for high-torque preload in confined spaces specifically includes: a support base 1, and a set of cylindrical spur gears with an axis perpendicular to the support base 1. The cylindrical gear set includes a driven gear ring 9 and a driving gear 10; the driving gear meshes with the driven gear ring. The driven gear ring 9 and the hex wrench caliper are an integral part. When the driven gear ring 11 rotates, it drives the hex wrench caliper to rotate to pre-tighten the bolts being assembled. The distance between opposite sides of the hex wrench caliper is 24mm.

[0022] The drive gear 10 is connected to the output shaft of the reducer 3 matched with the motor via a flat key and is circumferentially positioned. The axial clamping and positioning of the output shaft of the reducer 3 matched with the motor are achieved by the photoelectric baffle 6 and bolt connection. The photoelectric baffle 6 is connected to the drive gear 10 by bolts and rotates with the drive gear to block the photoelectric switch 8 when the hexagonal caliper of the wrench reaches the limit position of its stroke. By blocking the photoelectric switch, the motor is de-energized to ensure that the movement of the wrench caliper does not exceed its limit position of its stroke. The photoelectric switch 8 is bolted to the front of the pad 7, and the two photoelectric switches are arranged in a certain order. Distributed on both sides of the drive gear 10 and the photoelectric baffle 6, when the drive gear 10 drives the photoelectric baffle 6 to rotate to the position of blocking the photoelectric switch 8, the internal hex wrench caliper on the driven gear ring 9 moves to the travel limit position, and the motor is powered off for protection. The pad 7 is bolted to the cover plate 2 to support the photoelectric switch 8; The cover plate 2 is bolted to the support base 1, covering and protecting the driving gear 10, driven gear ring 9 and ball bearings 11 belonging to the transmission mechanism; The ball bearings 11 are evenly placed in the 5 sets of raceways of the support base 1, which converts the sliding friction between the support base 1 and the driven gear ring 9 into rolling friction, thereby reducing torque loss and wear on the driven gear ring 9 during transmission. The driving gear 10 meshes internally with the driven gear ring 9 and rotates to transmit torque to the driven gear ring 9; The reducer 3, which is matched with the motor, is bolted to the support base 1 and outputs torque through the drive gear 10 connected to the output shaft; The motor 4 is connected to the reducer 3 that is matched with the motor by bolts, and the output shaft of the motor 4 is connected to the input end of the reducer 3 that is matched with the motor. The protective cover 5 is bolted to the wrench support plate 1, covering and protecting the photoelectric switch 8, the photoelectric baffle 6, the protruding cylindrical boss of the drive gear 10, and the safety of the operator.

[0023] Specifically, the cylindrical gear set has a module m=2, and the number of teeth of the driving gear is... Number of teeth on the driven gear ring The reduction ratio i = 3.05; The support base has a cylindrical groove in the middle that is equal to the outer diameter of the driven gear ring. The driven gear ring is radially positioned by the clearance fit between its outer diameter and the inner diameter of the groove in the support base. The cylindrical groove of the support base and the driven gear ring is provided with 5 sets of 6mm wide raceways along the circumference, and contains 6mm diameter balls. The support base has threaded holes for installing a motor-matched reducer, and the motor-matched reducer is connected to the back of the support base by bolts; The motor has through holes for bolt connection, and is bolted to the matching reducer. The motor drives the drive gear, which meshes with the driven gear ring, thereby driving the internal hex wrench caliper, which is integrated with the driven gear, to rotate. The wrench caliper is integrated with the driven gear ring, and the distance between opposite sides of its internal hexagonal caliper is 24mm. Its maximum swing range during operation is... ; The cover plate is connected to the support base by bolts. The cover plate covers the gear set and rotating components such as balls. The cylindrical boss of the drive gear and the photoelectric baffle extend out of the cover plate through a 24mm diameter circular hole at the bottom of the cover plate. The cover plate has a 24mm diameter circular hole at its lower part. The position is achieved by connecting two pads with bolts for mounting the photoelectric switch; The pad block has two photoelectric switches bolted to its upper part, which are bolted to a cover plate. When the pad block is blocked by the photoelectric baffle, the wrench caliper moves to its travel limit position. The protective cover is connected to the support base by bolts and covers the photoelectric switch, photoelectric baffle, and the protruding part of the cylindrical boss of the drive gear.

[0024] In addition, a preferred solution is to adopt an internal meshing method of gear ring gear to reduce the center distance between the two gears, which reduces the diameter by 34mm compared to the external meshing design with the same reduction ratio, so as to achieve assembly preload in a narrow space. In addition, a preferred solution is to achieve speed reduction and torque increase by using a large reduction ratio, thereby achieving high torque despite the limited size of the motor. Furthermore, a preferred approach is to convert sliding friction into rolling friction using ball bearings, thereby reducing the friction between the outer diameter of the gear ring and the inner diameter of the cylindrical groove of the support seat.

[0025] In one embodiment, the high-torque tightening device is connected to the robotic arm via a flange. An endoscope is installed on the robotic arm to achieve visual navigation. The position and parts that need to be pre-tightened are identified visually, and the high-torque tightening device is moved to the corresponding position and the hexagonal caliper of the wrench is engaged with the bolt that needs to be pre-tightened. In one embodiment, the motor 4 drives the reducer 3 to transmit torque to the drive gear 10. The drive gear 10 drives the driven gear ring 9, which meshes with it, to rotate. This drives the hexagonal caliper of the wrench to tighten the bolts being assembled. The gear set has a reduction ratio of i=3.05. Combined with the reduction ratio provided by the reducer 3 connected in series with the motor, a large torque preload is achieved by reducing speed and increasing torque. In one embodiment, when the wrench's hex caliper rotates towards one side of the centerline of the high-torque preload device... When approaching the limit of its travel, since the reduction ratio i = 3.05, it can be inferred that the drive gear 10 and the photoelectric baffle 6 rotate in opposite directions. At this time, the photoelectric baffle 6 blocks the photoelectric switch 8 on one side, and the motor power-off protection wrench hexagonal caliper does not collide with the support base 1, jamming and damaging the drive gear 10, driven gear ring 9, motor-matched reducer 3 and motor 4.

[0026] This invention provides a vision-guided high-torque pre-tightening device for confined spaces. It utilizes an internal meshing drive between a driving gear 10 and a driven gear ring 9, which in turn drives an integrated hexagonal wrench caliper to pre-tighten the assembled hexagonal bolts. The device achieves high-torque pre-tightening through a high-reduction ratio design of the reducer 3 paired with the motor and the aforementioned gear set. The internal meshing design of the gear ring replaces the traditional external meshing design, reducing the space occupied by the high-torque pre-tightening device and enabling assembly pre-tightening in confined spaces. The drive and control of the motor 4 ensures that the pre-tightening torque of multiple bolts approaches uniformity and accuracy. Vision navigation drives a robotic arm to deliver the high-torque pre-tightening device to locations inaccessible to manual assembly operations, preventing collisions and interference with other equipment and components within the vehicle.

[0027] This invention utilizes the advantages of endoscopes—small size, high image resolution, high alignment accuracy, low image transmission latency, and the ability to capture and store images—to achieve visual navigation of a robotic arm and a high-torque preload device in confined spaces. The endoscope's vision-driven wrench caliper has an alignment accuracy of 0.1mm, which is sufficient to guide the robotic arm to the assembly position without collision and to accurately engage the high-torque preload device wrench caliper with the hexagonal head of the M20mm support bolt. This enables vision-driven guidance and adaptive adjustment of the robotic arm and the high-torque preload device, achieving intelligent assembly preload. A high-reduction-ratio motor paired with a planetary reducer is selected, and the high-torque preload device gear set also features a high-reduction-ratio design. Simultaneously, the motor's momentary stall ensures that the preload is achieved within 1-2 seconds. Achieving a peak torque output of 200 Nm within the space.

[0028] This invention designs a fully automated, unmanned pre-tightening method for confined spaces. The method is characterized by the following steps: endoscopic visual positioning in the confined space; a robotic arm equipped with a high-torque pre-tightening device accurately moves to the position of the bolt to be pre-tightened within the confined space; a wrench caliper accurately engages the hexagonal head of the M20mm support bolt and performs pre-tightening; and the high-torque pre-tightening device disengages from the pre-tightened bolt and moves with the robotic arm to the next pre-tightening position. The entire process is unmanned, automated, and intelligent.

[0029] The instantaneous stall method of the motor is to utilize the characteristics of the motor speed-torque curve. During the pre-tightening process of the high-torque pre-tightening device, as the M20mm support bolt is pre-tightened, the motor stalls instantaneously, causing the motor speed to drop to zero in a short time, and the output torque to reach its peak value. This enhances the maximum output torque of the high-torque pre-tightening device in the final stage of pre-tightening.

[0030] The internal meshing design of the gear ring reduces the overall size of the high-torque preload device. Compared with the external meshing design of the same reduction ratio, the internal meshing design reduces the length by 34mm, while the number of teeth on the driving gear is also reduced. The minimum number of teeth required to prevent undercutting has been achieved; a large reduction ratio design is adopted, which minimizes the number of teeth on the drive gear while increasing the number of teeth on the driven gear within the limits of size and the load-bearing capacity of the robotic arm, resulting in a gear reduction ratio of 3.05.

[0031] This invention employs a lightweight design, including an internal meshing gear ring design, replacing solid parts with hollow parts to achieve weight reduction; and using composite materials to process some parts, within the limits of structural strength and stiffness, to achieve significant weight reduction. The lightweight design reduces the weight of the high-torque preload device, allowing the robotic arm to operate without being under full load or near-full load for extended periods when carrying the device.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A vision-guided, high-torque pre-tensioning device for confined spaces, characterized in that, include: Support base (1) and cylindrical spur gear set mounted on support base (1), the axis of cylindrical spur gear set is perpendicular to support base; The cylindrical spur gear set includes a driven gear ring (9) and a driving gear (10) meshing with it. The driven gear ring (9) and the internal hex wrench caliper are an integral structure; The drive gear (10) is connected to the output shaft of the motor-matched reducer (3) and is axially positioned by the photoelectric baffle (6); The support base (1) has a cylindrical groove in the middle, which is in clearance fit with the outer diameter of the driven gear ring (9) to achieve radial positioning; The cylindrical groove is provided with several raceways in the circumferential direction and has built-in balls (11) to convert sliding friction into rolling friction; The cover plate (2) is fixed to the support base (1) and covers the gear set and the ball bearings; The photoelectric baffle (6) rotates with the drive gear (10) and is used to block the photoelectric switch (8) when the wrench caliper moves to the limit position, triggering the motor to cut off power; The photoelectric switch (8) is mounted on the cover plate (2); The high-torque pre-tightening device is connected to the robotic arm via a flange. An endoscope is installed on the robotic arm to achieve visual navigation. The device visually identifies the position and parts that need to be pre-tightened and moves the high-torque tightening device to the corresponding position, and then engages the hexagonal caliper of the wrench with the bolt that needs to be pre-tightened.

2. The apparatus according to claim 1, characterized in that, The cylindrical gear set has a module m=2 and a number of teeth on the driving gear. Number of teeth on the driven gear ring The reduction ratio i = 3.

05.

3. The apparatus according to claim 1, characterized in that, Two photoelectric switches are in Distributed on both sides of the drive gear 10 and the photoelectric baffle 6, the limit swing stroke of the hex wrench caliper is ±30°, and the photoelectric baffle (6) rotates ±90° to block the photoelectric switch (8) when the caliper approaches the limit position.

4. The apparatus according to claim 1, characterized in that, The number of raceways is 5 sets, the width is 6mm, and the built-in ball bearings (11) have a diameter of 6mm.

5. The apparatus according to claim 1, characterized in that, The distance between opposite sides of the hex wrench caliper is 24mm.

6. The apparatus according to claim 1, characterized in that, A protective cover (5) is installed on the support base (1) to cover the protruding parts of the photoelectric switch (8), photoelectric baffle (6) and drive gear (10).

7. A method for high-torque pre-tensioning in confined spaces based on vision navigation, characterized in that, Includes the following steps: The location of bolts in a confined space is identified and located using an endoscope; Control the robotic arm to move the high-torque pre-tensioning device as described in any one of claims 1-6 to the pre-tensioning station; Guide the hex wrench caliper to accurately engage the hex head of the bolt; Start the motor, which drives the wrench caliper to rotate via gear transmission, thus pre-tightening the bolts; When the wrench caliper approaches its limit position, the photoelectric baffle (6) blocks the photoelectric switch (8), and the motor is de-energized; After pre-tightening is completed, the device is released from the bolts, and the robotic arm moves to the next station.

8. The method according to claim 7, characterized in that, The endoscope has a guiding accuracy of no less than 0.1mm, enabling precise alignment of the wrench caliper with the hexagonal head of the bolt.

9. The method according to claim 7, characterized in that, During the pre-tightening process, the instantaneous stall characteristic of the motor is utilized to enable the motor to output peak torque of 200Nm within 1-2 seconds.

10. The apparatus according to any one of claims 1-6, characterized in that, The device employs a hollow structure and composite materials to achieve a lightweight design.

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