A robot end effector providing high tightening torque

Abstract

The present invention discloses a robot end effector that provides a large tightening torque, including a connecting mechanism connected to the end of the industrial robot, a visual positioning camera fixed to the connecting mechanism, a pre-tightening gun fixed to the connecting mechanism, a clutch mechanism arranged outside the connecting mechanism, a cylinder arranged on the upper side of the clutch mechanism, a contraction mechanism arranged on one side of the clutch mechanism, and a structure for providing a large tightening torque arranged on one side of the contraction mechanism. The robot arm simulates the action of a person tightening a bolt with a wrench, and transmits the force of the robot end to the bolt to be tightened through a longer torsion bar to complete the tightening operation of the bolt. At the same time, the contraction mechanism realizes different postures of the tightening mechanism at the end of the robot in working and preparation states, and is retracted into the robot in the preparation state, which effectively saves the space occupied in this state.

Description

Technical Field

[0001] The invention relates to the technical field of tightening robots, and in particular to a robot end effector providing large tightening torque. Background Art

[0002] A tightening robot is a robot used to automatically tighten bolts or nuts. It can be widely used in various fields such as automobiles, aviation, and mechanical manufacturing. With the improvement of the level of industrialization, a large number of robots are used for workshop operations. In addition to being able to work in complex environments, these robots can also achieve high-speed, high-precision and stable production efficiency. In the manufacturing process, tightening bolts and nuts often requires a lot of time and manpower, and its quality is difficult to guarantee. The emergence of tightening robot technology effectively solves this problem.

[0003] The bolt tightening systems currently used in the industrial field mainly include the following two methods:

[0004] 1. Use a torque tightening gun and a special fixture to tighten the bolts manually and semi-automatically;

[0005] 2. Set up a specific fixture and install it on the flange of the industrial robot arm so that it can tighten the specified bolts in a specific scenario;

[0006] Both of the above methods expose certain technical problems. For example, if manual methods are used, special staff will be required to perform tightening operations. In an environment where the demographic dividend is gradually fading, labor costs are constantly increasing. In addition, the tightening work is intensive, the movements are mechanical and repetitive, and the staff are very likely to feel fatigued or even disgusted after working for a long time. In severe cases, it may affect equipment and personal safety. Moreover, due to different operating habits, the tightening force of the bolts may fluctuate. This instability is particularly prominent in the field of product technology that requires high precision and high quality.

[0007] The tightening operation of such systems is basically completed by the tightening gun when the tightening gun is used in conjunction with the robot arm. When the bolt requires a large tightening torque, if the tightening gun is fixed to the robot arm flange, the robot arm flange motor will be subjected to a large counter torque, which may damage the motor shaft, causing deformation and cracking. In addition, the torque of the pre-tightening gun is limited and may not be able to output a large torque. Summary of the invention

[0008] The purpose of the present invention is to address the defects of the prior art and provide a robot end mechanism that can provide a large tightening torque. The mechanism can be connected to the flange of the robot arm and can effectively reduce the reaction torque applied to the flange by the tightening gun when tightening the bolts.

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0010] A robot end effector providing a large tightening torque, characterized in that it comprises a connecting mechanism connected to the end of an industrial robot, a clutch mechanism arranged outside the connecting mechanism, and a large tightening torque mechanism connected to the clutch mechanism;

[0011] The connection mechanism includes a connection base plate, a visual positioning camera, and a pre-tightening gun. The connection base plate is fixedly connected to the end flange of the industrial robot. A protruding stepped shaft is provided on the side of the connection base plate away from the end flange. The visual positioning camera is fixedly connected to the connection base plate through a camera support and is used to automatically locate the bolts to be tightened. The pre-tightening gun is fixedly connected to the connection base plate and is used to pre-tighten the bolts.

[0012] The clutch mechanism comprises a clutch frame, a pressure plate, a friction plate, and a clutch control device. The clutch frame is coaxially rotatably connected to the protruding stepped shaft through a clutch frame bearing and is axially fixed through a retaining ring. The pressure plate and the friction plate are sleeved on the clutch frame through a spline coaxial movable connection. The pressure plate, the friction plate, and the connecting base plate are stacked in sequence from the outside to the inside. The clutch control device is arranged on the clutch frame and can control the pressure plate to move axially along the clutch frame, thereby changing the contact or separation between the friction plate and the connecting base plate.

[0013] The large tightening torque mechanism includes a torsion rod, a ratchet, and a ratchet end cover. One end of the torsion rod is connected to the clutch frame, and the other end is provided with a groove. The ratchet end cover is arranged on the outside of the groove. One end of the ratchet is connected in the groove, and the other end is a long step shaft that passes through the ratchet end cover and protrudes out of the groove. A hexagonal groove is provided in the end face of the long step shaft for connecting and tightening bolts or nuts.

[0014] Furthermore, the clutch control device includes a cylinder and a clutch lever. The cylinder is fixedly connected to the clutch frame via a cylinder support. The clutch lever is arranged at the opening of the clutch frame. The lever fulcrum of the clutch lever and the clutch frame opening form a rotating pair through a pin, so that the clutch lever can rotate around the lever fulcrum. One end of the clutch lever is connected to the push rod of the cylinder, and the other end is connected to the groove of the pressure plate. When the cylinder is working, the push rod can push the clutch lever to rotate around the lever fulcrum, thereby driving the pressure plate to move axially along the clutch frame.

[0015] Furthermore, the large tightening torque mechanism also includes a pawl, a spring, an upper ratchet bearing, and a lower ratchet bearing. A small semicircular groove is provided on the side of the groove close to the main body of the mechanical arm. One side of the pawl is a cylindrical protrusion, which is rotatably connected in the small semicircular groove. The other side has three protruding bevel teeth, which engage with the outer teeth of the ratchet. One end of the spring is fixed in the groove, and the other end is fixed on the pawl. The pawl can limit the ratchet to rotate only counterclockwise but not clockwise. The ratchet is connected to the bottom of the groove through the ratchet upper bearing, and the ratchet end cover is connected to the ratchet through the ratchet lower bearing.

[0016] Furthermore, the middle portion of the torsion bar is an I-beam type crossbeam.

[0017] Furthermore, it also includes a contraction mechanism arranged between the clutch mechanism and the large tightening torque mechanism, the contraction mechanism includes a stepper motor and a shaft sleeve, the connecting part between the clutch frame and the torsion bar is a C-shaped groove, the stepper motor is fixedly connected to the clutch frame, the shaft sleeve is inserted into the C-shaped groove, the output shaft of the stepper motor is coaxially fixedly connected to the shaft sleeve, the torsion bar is fixedly connected to the shaft sleeve, and the stepper motor can drive the torsion bar to rotate around the shaft sleeve as the axis.

[0018] Furthermore, the retraction mechanism also includes an upper bearing of the torsion bar and a lower bearing of the torsion bar. The upper end of the C-shaped groove is connected to the shaft sleeve through the upper bearing of the torsion bar, and the lower end of the C-shaped groove is connected to the shaft sleeve through the lower bearing of the torsion bar, thereby ensuring the stability and smoothness of the rotation process of the torsion bar.

[0019] Furthermore, a gasket is provided between the upper bearing of the torsion bar and the torsion bar, so that the upper end surface of the torsion bar and the outer ring of the upper bearing of the torsion bar do not interfere with each other.

[0020] Furthermore, the shaft sleeve and the output shaft of the stepper motor are connected to each other via a flat key connecting the motor and the shaft sleeve.

[0021] Furthermore, the shaft sleeve and the torsion bar are connected to each other via a flat key connecting the shaft sleeve and the torsion bar.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: the robot arm simulates the action of tightening the bolts with a wrench, and transmits the force of the robot end to the bolts to be tightened through a longer torsion bar, thereby completing the tightening operation of the bolts. In this process, because the clutch mechanism is connected to the protruding stepped shaft of the connecting base plate through a bearing, and the bearing only transmits force but not torque, the flange at the end of the robot is subjected to the resistance generated during tightening, but not to the larger resistance torque caused by the resistance, which effectively solves the problem of insufficient torque of the pre-tightening gun and damage to the motor shaft of the flange at the end of the robot arm due to the large torque in special cases where a large torque is required; at the same time, the different postures of the tightening mechanism at the end of the robot in working and preparation are realized through the retraction mechanism, and the robot is retracted into the robot in the preparation state, which better saves the space occupied in this state. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0024] Figure 2 It is an axial cross-sectional view of the clutch mechanism in the embodiment of the present invention.

[0025] Figure 3 It is an axial cross-sectional view of the contraction mechanism in the embodiment of the present invention.

[0026] Figure 4 4 is a transverse cross-sectional view of a large tightening torque mechanism in an embodiment of the present invention.

[0027] Figure 5 It is a transverse cross-sectional view of the terminal structure when the robot is in working state.

[0028] Figure 6 This is a schematic diagram of the robot being in the ready state and the retraction mechanism retracting the torsion bar.

[0029] Figure 7 It is a schematic structural diagram of a clutch lever in an embodiment of the present invention.

[0030] Figure 8 It is an initial posture diagram and an ending posture diagram of an embodiment of the present invention during a tightening process.

[0031] In the figure: 1- robot base; 21- mechanical arm; 22- end flange; 31- connecting base plate; 311- protruding stepped shaft; 32- visual positioning camera; 33- camera support; 34- preload gun; 41- cylinder support; 42- cylinder; 43- clutch frame; 44- clutch frame outer bearing; 45- retaining ring; 46- clutch frame fixing bolt; 47- clutch frame inner bearing; 48- flange connecting bolt; 49- friction plate; 410- pressure plate; 411- clutch lever; 412- pin; 51- stepper Motor; 52-motor bolt; 53-torsion bar upper bearing; 54-gasket; 55-motor and shaft sleeve connecting flat key; 56-shaft sleeve; 57-end cover; 58-torsion bar lower bearing; 59-shaft sleeve and torsion bar connecting flat key; 510-C-type groove; 61-torsion bar; 62-pawl; 63-spring; 64-ratchet; 641-long step shaft; 642-hexagonal groove; 65-ratchet upper bearing; 66-ratchet lower bearing; 67-ratchet end cover; 68-end cover bolt; 69-groove. DETAILED DESCRIPTION

[0032] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0033] Figure 1-8 A specific embodiment of a robot end effector providing a large tightening torque is shown, including a connection mechanism with the end of an industrial robot, a visual positioning camera 32 fixed to the connection mechanism, a pre-tightening gun 34 fixed to the connection mechanism, a clutch mechanism arranged on the outside of the connection mechanism, a cylinder 42 arranged on the upper side of the clutch mechanism, a contraction structure arranged on one side of the clutch mechanism, and a mechanism for providing a large tightening torque arranged on one side of the contraction mechanism.

[0034] The connecting mechanism is fixed to the end flange 22 of the industrial robot by bolts, and can adjust the direction in the actual process following the movement of the robot arm. A visual positioning camera 32 can be loaded on one side of the connecting mechanism to realize the function of automatically positioning the bolts to be tightened. A pre-tightening gun 34 is provided on the lower side of the visual positioning to realize the bolt pre-tightening function. A clutch mechanism is provided on the outside of the connecting mechanism to realize the separation of the clutch frame and the connecting mechanism, avoiding the end being subjected to a large counter torque during the tightening process. A contraction mechanism is provided on one side of the clutch mechanism to realize the posture adjustment of the large tightening torque mechanism in different states, effectively saving the working space. The contraction mechanism is connected to the large tightening torque mechanism to realize the tightening of the bolts by a wrench-like tightening method.

[0035] The connection mechanism includes: a connection base plate 31 connected to the end flange 22 of the industrial robot by threads, a camera support 41 arranged on one side of the connection base plate 31 and threadedly connected thereto, and a pre-tightening gun 34 arranged on the lower side of the camera support 41 and fixed to the connection base plate 31. The connection base plate 31 is not a uniform thin plate, but an irregular piece with a protruding stepped shaft 311 on one side. The protruding stepped shaft 311 plays the role of supporting the entire clutch mechanism. In the actual tightening process, the specific position of the bolt to be tightened is first located by the visual camera 32, the robot arm 21 is adjusted to a suitable tightening posture, and then the pre-tightening gun 34 works to achieve pre-tightening, without the need for the industrial robot to control the large tightening torque mechanism to rotate the entire arc around the bolt to be tightened, thereby improving the efficiency of the tightening process.

[0036] The clutch mechanism includes: the outermost side of the clutch mechanism is a clutch frame 43, the upper side of the clutch frame 43 is an opening, and holes are provided on both sides of the opening to facilitate driving pins. There is a gap between the clutch frame 43 and the connecting substrate 31, and a friction plate 49 and a pressure plate 410 are installed in the gap. The clutch frame 43 is connected to the protruding stepped shaft 311 of the connecting substrate through the clutch frame outer bearing 44 and the clutch frame inner bearing 47, so that the clutch frame 43 can stably rotate around the protruding stepped shaft 311 of the connecting substrate. There are screw holes on the upper side of the clutch frame 43, the cylinder support 41 is connected to the clutch frame 43 through bolts, the cylinder 42 is connected to the cylinder support 41 through bolts, and a groove is provided on one side of the push rod of the cylinder 42. The clutch lever 411 is arranged at the opening of the clutch frame 43, and the lever fulcrum and the opening of the clutch frame 43 form a rotating pair through the pin 412, so that the clutch lever 411 can rotate around the lever fulcrum. The upper side of the clutch lever 411 penetrates the groove of the push rod of the cylinder 42, and the lower side extends into the groove of the pressure plate 410. The pressure plate 410 and the friction plate 49 are connected to the clutch frame 43 through splines and can move axially on the clutch frame 43. The outermost side of the clutch frame 43 is equipped with a retaining ring 45 and a clutch frame fixing bolt 46. The clutch frame fixing bolt 46 fixes the retaining ring 45 to the end face of the protruding stepped shaft 311 through a threaded connection. The retaining ring 45 supports the inner ring of the clutch frame outer bearing 44, and the shoulder of the protruding stepped shaft 311 supports the inner ring of the clutch frame inner bearing 47. The clutch frame 43 supports the outer rings of the clutch frame outer bearing 44 and the clutch frame inner bearing 47 to achieve axial positioning of the double bearings. When the clutch mechanism is in a disengaged state, such as Figure 2 As shown in (b), the push rod of the cylinder 42 is pushed outward, causing the clutch lever 411 to rotate clockwise around the lever fulcrum, driving the pressure plate 410 to move axially in the direction away from the flange 22. The friction plate 49 is not squeezed and is out of contact with the connecting substrate 31, thus realizing the function of separating the clutch frame 43 from the connecting substrate 31. When the clutch mechanism is in the engaged state, as shown in FIG. Figure 2As shown in (a), the push rod of the cylinder 42 retracts inward, causing the clutch lever 411 to rotate counterclockwise around the fulcrum, driving the pressure plate 410 to move axially in the direction close to the flange 22, and the pressure plate 410 is forced to squeeze the friction plate 49, causing the friction plate 49 to squeeze the connecting base plate 31 and generate friction force and friction torque. At this time, the clutch frame 43 and the connecting base plate 31 are completely pressed together through the friction torque, realizing the combination function of the two. In the combined state, the clutch frame outer bearing 44 and the clutch frame inner bearing 47 lose the rotation function and only bear the support function of the clutch frame 43 and the protruding stepped shaft 311. By controlling the telescopic state of the push rod of the cylinder 42, the separation and combination functions in the clutch mechanism are realized.

[0037] The retracting mechanism includes a stepper motor 51, a motor bolt 52, an upper bearing 53 of a torsion bar, a lower bearing 58 of a torsion bar, a shaft sleeve 56, a gasket 54, a flat key 55 for connecting the motor and the shaft sleeve, a flat key 59 for connecting the shaft sleeve and the torsion bar, and an end cover 57. The stepper motor 51 is fixed to the upper side of the clutch frame 43 and connected to the clutch frame 43 through the motor bolt 52. The connection part between the clutch frame 43 and the torsion bar 61 is a C-shaped groove 510, and there is a T-shaped hole in the middle for locating the upper bearing 53 of the torsion bar. The output shaft of the stepper motor 51 extends into the C-shaped groove 510. Since the length of the output shaft is limited, a shaft sleeve 56 is required to extend the output length range of the motor shaft. A keyway is left on the inner side of the shaft sleeve 56, and is connected to the output shaft of the stepper motor 51 through a flat key 55 connecting the motor and the shaft sleeve. A keyway is also left on the outer side, and is connected to the torsion bar 61 through a flat key 59 connecting the shaft sleeve and the torsion bar. The shaft sleeve 56 has a protruding shoulder near the lower end surface, which is convenient for positioning the inner ring of the lower bearing 58 of the torsion bar. A gasket 54 is provided between the upper bearing 53 of the torsion bar and the torsion bar 61, so that the end face of the torsion bar 61 does not interfere with the outer ring of the upper bearing 53 of the torsion bar. An end cover 57 is provided on the outside of the lower end surface of the C-shaped groove 510 of the clutch frame 43, and the end cover 57 is fixed to the clutch frame 43 by bolts. The flange part of the end cover 57 is used as the outer ring positioning of the lower bearing 58 of the torsion bar. When the stepper motor 51 is controlled to rotate, the torque of the output shaft of the stepper motor 51 is transmitted to the shaft sleeve 56 through the flat key 55 connecting the motor and the shaft sleeve, and then transmitted to the flat key 59 connecting the shaft sleeve and the torsion bar by the shaft sleeve 56, driving the torsion bar 61 to rotate around the shaft sleeve 56 at a specific angle. The upper bearing 53 of the torsion bar and the lower bearing 58 of the torsion bar ensure the stability and smoothness of the entire rotation process. By controlling the angular displacement of the stepper motor 51, the rotation function of the torsion bar 61 is realized, so that the robot arm can be retracted in the preparatory state and extended in the working state, saving the working space of the end mechanism of the robot arm.

[0038] The large tightening torque mechanism includes a torsion bar 61, a ratchet 64, a spring 63, a pawl 62, a ratchet end cover 67, an upper ratchet bearing 65, and a lower ratchet bearing 66. The middle part of the torsion bar 61 is an I-beam beam, which greatly reduces the weight of the beam itself while ensuring the strength requirement. The right side is a groove 69, and the bottom of the groove 69 is provided with a T-shaped hole to facilitate the positioning and installation of the outer ring of the ratchet upper bearing 65. The groove 69 has a small semicircular groove on the side close to the main body of the mechanical arm 21, which is convenient for installing the pawl 62 and forming a rotating pair with the pawl 62. One side of the pawl 62 is a cylindrical protrusion embedded in the small semicircular groove, and the other side has three protruding oblique teeth, which mesh with the outer teeth of the ratchet 64. One end of the spring 63 is fixed in the groove of the torsion bar 61, and the other end is fixed in the groove of the spring 63. The end is fixed to the lower part of the pawl 62. When the pawl 62 rotates clockwise, the outer teeth of the ratchet 64 bounce the oblique teeth of the pawl 62, move around the rotating pair on the circular protrusion side, and press the spring 63 downward. At this time, the pawl 62 does not change the movement state of the ratchet 64. When the pawl 62 rotates counterclockwise, the elastic force generated by the compression of the spring 63 engages the oblique teeth of the pawl 62 with the outer teeth of the ratchet 64. The ratchet 64 is constrained by the rotating pair and is forced to rotate together with the pawl 62. At this time, the ratchet 64, the pawl 62 and the torsion bar 61 are equivalent to being fixed together, and the tightening operation can be implemented. One side of the ratchet 64 has a solid protruding short step shaft with a smaller diameter, and the shoulder is convenient for positioning and installing the inner ring of the ratchet upper bearing 65. The other side has a long step shaft 641 with a larger diameter. The end face of the long step shaft 641 extends out of the groove 69, and the protruding end face of the long step shaft 641 has a hexagonal groove 642, which is convenient for tightening the hexagonal bolt or hexagonal nut. The shoulder of the long step shaft 641 is convenient for positioning and installing the inner ring of the ratchet lower bearing 66. The ratchet end cover 67 has through holes on both sides, which are fixedly connected to the outer end face of the groove 69 by bolts. The ratchet end cover 67 has a through hole in the middle, which is convenient for the extension of the long step shaft 641. The inner side has a flange slightly larger than the diameter of the middle through hole, which is convenient for positioning and installing the outer ring of the ratchet lower bearing 66.

[0039] When the robot is in standby or preparatory state, the pressure plate 410 and the friction plate 49 are separated by controlling the push rod of the cylinder 42 in the clutch mechanism. Under the influence of gravity, the clutch mechanism and the large tightening torque mechanism will droop downward to the ground. By controlling the angular displacement of the stepper motor 51 in the contraction mechanism, the entire large tightening torque mechanism will contract toward the inside of the robot and eventually become parallel to the four axes of the robotic arm 21, effectively reducing the environmental space occupied by the robot in the preparatory state.

[0040] When the robot is in working state, the pressure plate 410 moves toward the connecting substrate 22 through the control of the push rod of the cylinder 42 in the clutch mechanism, and the friction plate 49 is tightly pressed against the connecting substrate 22. When the flange 22 at the end of the robot arm is rotated, the connecting substrate 31 and the clutch frame 43 rotate around the center of the flange at the same time, and the visual positioning camera 32, the pre-tightening gun 34 and the clutch mechanism are rotated to the working position and standby. After the visual positioning camera 32 accurately locates the bolt position, the pre-tightening gun 34 is used to pre-tighten the bolt to be tightened, and then the angular displacement of the stepper motor 51 in the retraction mechanism is controlled to extend the large tightening torque mechanism to be parallel to the end face of the clutch frame 43. The size of the torsion bar 61 is a fixed value, and the coordinate transformation and movement of the robot end can be used to extend the hexagonal bolt to be tightened into the hexagonal groove outside the tightening mechanism. The clutch mechanism is re-controlled to be in a disengaged state. The robotic arm 21 takes the tightening bolt as the center of the circle and imitates the action of a person tightening the bolt with a wrench, driving the large tightening torque mechanism to make an arc motion counterclockwise from top to bottom. At this time, the pawl 62, the ratchet 64 and the torsion bar 61 are fixed together, and the ratchet 64 also rotates counterclockwise to tighten the bolt; when the end of the robotic arm 21 needs to return to the initial position for the second tightening operation, the robotic arm 21 drives the large tightening torque mechanism to make an arc motion clockwise from bottom to top. At this time, the pawl 62 is disengaged from the ratchet 64, realizing the function of the ratchet 64 not moving and the robotic arm returning to the initial position.

[0041] The specific working process and principle of the above embodiment are as follows:

[0042] like Figure 1 As shown, this embodiment is arranged on the robot base 1, including a connecting mechanism connecting the end flange 22 of the robot arm 21, a clutch mechanism for separating or combining the end mechanism and the robot arm flange, a telescopic mechanism for realizing that the large torque tightening mechanism is in different postures under different working conditions, and a large tightening torque mechanism for final tightening.

[0043] The robot is in the ready state at the initial moment, the large tightening torque mechanism is retracted inside the robot, and the clutch mechanism is in the separated state. At this time, the flange is only subject to the gravity and gravity torque brought by the end mechanism. Figure 6As shown, when the bolt to be tightened is in the working area, the robot starts to work. First, the visual positioning camera 32 fixed on the connection mechanism obtains the bolt position and sends the position information to the control system. The control system obtains the change coordinates through the spatial geometric relationship between the pre-tightening gun 34 and the visual positioning camera 32, and controls the pre-tightening gun 34 to reach the position of the bolt to be tightened. The pre-tightening gun 34 has a high rotation speed and can be used for pre-tightening of bolts, which greatly increases the work efficiency. After the pre-tightening gun 34 completes the pre-tightening, the cylinder 42 retracts inward, forcing the clutch lever 411 to rotate along its rotating pair. Because the end of the clutch lever 411 contacts the groove of the pressure plate 410, when the cylinder 42 retracts, the end of the clutch lever 411 drives the pressure plate 410 to move axially along the spline surface toward the end flange 22, and finally the pressure plate 410 squeezes the friction plate 49 to generate a friction torque. The friction plate 49 is forced to squeeze the connecting base plate 31 to generate a friction torque. At this time, the end flange 22 is controlled to rotate axially to a suitable position, and the friction plate 49 and the pressure plate 410 rotate at the same angle with the end flange 22. The pressure plate 410 and the friction plate 49 are connected to the clutch frame 43 through splines, so that the clutch frame 43 and the entire clutch mechanism rotate at the same angle. The clutch frame outer bearing 44 and the clutch inner bearing 47 only have a supporting function in this process.

[0044] The stepper motor 51 is fixed to the outer side of the clutch frame 43 by the motor bolt 52. When the clutch frame 43 rotates to the specified position, the stepper motor 51 is started, and the motor shaft torque is transmitted to the shaft sleeve 56 through the flat key 55 connecting the motor and the shaft sleeve, and then transmitted to the torsion bar 61 through the flat key 59 connecting the shaft sleeve and the torsion bar, driving it to rotate. By controlling the stepper motor 51 to rotate to a specific angle, the outer side of the torsion bar 61 is made parallel to the outer side of the clutch frame 43. Because the spatial geometric relationship between the visual positioning camera 32 and the ratchet 64 is fixed in this state, the joints of the robot arm 21 or the workpiece can be moved through the corresponding coordinate transformation, so that the hexagonal bolt to be tightened extends into the hexagonal groove 642 on the end face of the long step shaft 641 on the outer side of the ratchet 64, and is ready for final tightening.

[0045] After completing the previous step, the robot can be controlled to perform the final high-torque tightening operation. Figure 2 As shown in (b), first, the telescopic cylinder 42 is controlled to be in the extended state, and the clutch lever 411 rotates to drive the pressure plate 410 to move away from the end flange 22, and the friction plate 49 loses pressure and detaches from the connecting base plate 31, thereby losing the friction torque. The clutch frame 43 can rotate around the central axis under the action of the clutch frame outer bearing 44 and the clutch frame inner bearing 47. Then the posture of the robot arm 21 is controlled so that the end position is centered on the bolt to be tightened and rotates to a higher position, such as Figure 8As shown in (a), this position is the starting point of high torque tightening. During the clockwise upward rotation process, the pawl 62 also rotates clockwise along the outer contour of the ratchet 64, and the outer teeth of the ratchet 64 bounce the pawl 62 helical teeth, move around the rotating pair on the circular protrusion side, and press the spring 63 downward. At this time, the pawl 62 does not change the state of the ratchet 64.

[0046] After the large torque tightening mechanism reaches the starting position, the robot arm 21 is controlled to make an arc motion with the tightening bolt as the center. During the whole process, it is necessary to ensure that the hexagonal groove 642 in the end face of the long step shaft 641 of the large torque mechanism is always wrapped around the hexagonal bolt; during the arc motion, the end flange 22 of the robot arm 21 applies force to the connecting base plate 31, driving the clutch frame 43 and the torsion bar 61 to move counterclockwise, because the clutch frame 43 is connected to the connecting base plate 31 through the clutch frame outer bearing 44 and the clutch frame outer bearing 47, and The bearing only transmits force but not torque, so the end flange 22 on the robot arm 21 is only subject to the restraining reaction force fed back when tightening the bolt, but not to the restraining torque; when the torsion bar 61 drives the pawl 62 to rotate counterclockwise, the elastic force generated by the compression of the spring 63 pushes the helical teeth of the pawl 62 against the outer teeth of the ratchet 64, driving the ratchet 64 and the pawl 62 to rotate together. At this time, the ratchet 64, the pawl 62 and the torsion bar 61 are equivalent to being fixed together, thereby realizing the tightening operation. The ending posture of the robot arm 21 after completing a tightening operation is as follows Figure 8 (b). Because the torsion bar 61 is long, when the force output by the mechanical arm 21 is transmitted to the tightening bolt, a large torque will be generated, thereby achieving the function of large tightening torque and protecting the end flange 22. If the bolt does not meet the requirements at this time, the mechanical arm 21 is moved clockwise along the same arc to the initial state and the above process is repeated.

[0047] The above specific implementation methods are only for illustrating the technical concept and structural features of the present invention, and the purpose is to enable relevant persons familiar with this technology to implement it. However, the above content does not limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should fall within the protection scope of the present invention.

Claims

1. A robot end effector providing a large tightening torque, characterized in that: It includes a connection mechanism connected to the end of the industrial robot, a clutch mechanism arranged outside the connection mechanism, and a large tightening torque mechanism connected to the clutch mechanism; The connection mechanism comprises a connection base plate (31), a visual positioning camera (32), and a pre-tightening gun (34); the connection base plate (31) is fixedly connected to the end flange (22) of the industrial robot; a protruding stepped shaft (311) is provided on a side of the connection base plate (31) away from the end flange (22); the visual positioning camera (32) is fixedly connected to the connection base plate (31) via a camera support (33) and is used for automatically positioning bolts to be tightened; and the pre-tightening gun (34) is fixedly connected to the connection base plate (31) and is used for pre-tightening bolts; The clutch mechanism comprises a clutch frame (43), a pressure plate (410), a friction plate (49), and a clutch control device. The clutch frame (43) is coaxially rotatably connected to the protruding stepped shaft (311) via a clutch frame bearing and is axially fixed via a retaining ring (45). The pressure plate (410) and the friction plate (49) are sleeved on the clutch frame (43) via a spline coaxial movable connection. The pressure plate (410), the friction plate (49), and the connecting base plate (31) are stacked in sequence from the outside to the inside. The clutch control device is arranged on the clutch frame (43) and can control the pressure plate (410) to move axially along the clutch frame (43), thereby changing the contact or separation between the friction plate (49) and the connecting base plate (31). The clutch control device comprises a cylinder (42) and a clutch lever (411); the cylinder (42) is fixedly connected to the clutch frame (43) via a cylinder support (41); the clutch lever (411) is arranged at an opening of the clutch frame (43); a lever fulcrum of the clutch lever (411) and an opening of the clutch frame (43) form a rotation pair via a pin (412), so that the clutch lever can rotate around the lever fulcrum; one end of the clutch lever (411) is connected to a push rod of the cylinder (42), and the other end is connected to a groove of the pressure plate (410); when the cylinder (42) is working, the push rod can push the clutch lever (411) to rotate around the lever fulcrum, thereby driving the pressure plate (410) to move axially along the clutch frame (43); The large tightening torque mechanism comprises a torsion bar (61), a ratchet (64), and a ratchet end cover (67); one end of the torsion bar (61) is connected to the clutch frame (43), and the other end is provided with a groove (69); the ratchet end cover (67) is arranged outside the groove (69); one end of the ratchet (64) is connected to the groove (69), and the other end is a long step shaft (641) that passes through the ratchet end cover (67) and protrudes outside the groove (69); the end surface of the long step shaft (641) is provided with a hexagonal groove (642) for connecting and tightening a bolt or a nut; The large tightening torque mechanism further comprises a pawl (62), a spring (63), an upper ratchet bearing (65), and a lower ratchet bearing (66); a semicircular small groove is provided on one side of the groove (69) close to the main body of the mechanical arm (21); one side of the pawl (62) is a cylindrical protrusion, which is rotatably connected in the semicircular small groove; the other side of the pawl (62) has three protruding oblique teeth, which mesh with the outer teeth of the ratchet (64); one end of the spring (63) is fixed in the groove (69), and the other end is fixed on the pawl (62); the pawl (62) can limit the ratchet (64) to rotate only counterclockwise but not clockwise; the ratchet (64) is connected to the bottom of the groove (69) via the upper ratchet bearing (65); and the ratchet end cover (67) is connected to the ratchet via the lower ratchet bearing (66).

2. A robot end effector providing a large tightening torque according to claim 1, characterized in that: The middle portion of the torsion bar (61) is an I-beam crossbeam.

3. A robot end effector providing a large tightening torque according to claim 1, characterized in that: The invention also comprises a contraction mechanism arranged between the clutch mechanism and the large tightening torque mechanism, the contraction mechanism comprising a stepping motor (51) and a shaft sleeve (56), the connection portion between the clutch frame (43) and the torsion bar (61) being a C-shaped groove (510), the stepping motor (51) being fixedly connected to the clutch frame (43), the shaft sleeve (56) being inserted into the C-shaped groove (510), the output shaft of the stepping motor (51) being coaxially fixedly connected to the shaft sleeve (56), the torsion bar (61) being fixedly connected to the shaft sleeve (56), and the stepping motor (51) being capable of driving the torsion bar (61) to rotate about the shaft sleeve (56).

4. A robot end effector providing a large tightening torque according to claim 3, characterized in that: The retracting mechanism further comprises a torsion bar upper bearing (53) and a torsion bar lower bearing (58); the upper end of the C-shaped groove (510) is connected to the shaft sleeve (56) via the torsion bar upper bearing (53); and the lower end of the C-shaped groove (510) is connected to the shaft sleeve (56) via the torsion bar lower bearing (58), thereby ensuring the stability and smoothness of the rotation process of the torsion bar (61).

5. A robot end effector providing a large tightening torque according to claim 4, characterized in that: A gasket (54) is provided between the torsion bar upper bearing (53) and the torsion bar (61) so that the upper end surface of the torsion bar (61) and the outer ring of the torsion bar upper bearing (53) do not interfere with each other.

6. A robot end effector providing a large tightening torque according to claim 3, characterized in that: The shaft sleeve (56) and the output shaft of the stepper motor (51) are connected to each other via a motor-to-shaft sleeve connecting key (55).

7. A robot end effector providing a large tightening torque according to claim 3, characterized in that: The shaft sleeve (56) and the torsion bar (61) are connected to each other via a shaft sleeve and torsion bar connecting flat key (59).

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