CN116652570B - A robot end effector providing high tightening torque - Google Patents

Abstract

The invention discloses a robot end effector for providing large tightening torque, which comprises a connecting mechanism connected with the tail end of an industrial robot, a visual positioning camera fixed on the connecting mechanism, a pre-tightening gun fixed on the connecting mechanism, a clutch mechanism arranged on the outer side of 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 large tightening torque arranged on one side of the contraction mechanism. The mechanical arm simulates the action of screwing the bolt by a spanner, and transmits the force of the tail end of the robot to the bolt to be screwed through the longer torsion bar, so that the screwing operation of the bolt is completed. Meanwhile, different postures of the tail end screwing mechanism of the robot under working and preparation are realized through the contraction mechanism, the tail end screwing mechanism of the robot is retracted into the robot under the preparation state, and the occupied space under the state is better saved.

Description

Robot end effector providing large tightening torque

Technical Field

The invention relates to the technical field of screwing robots, in particular to a robot end effector which provides large screwing torque.

Background

The tightening robot is a robot for automatically tightening bolts or nuts. It can be widely used in various fields of automobile, aviation, mechanical manufacturing, etc. With the increase of the industrialization level, a large number of robots are used to perform shop operations. The robots can work in complex environments and can realize high-speed, high-precision and stable production efficiency. In the manufacturing process, the tightening of the bolts and nuts often requires a lot of time and labor, and the quality of the bolts and nuts is difficult to ensure. The screwing robot technology effectively solves the problem.

The bolt tightening system currently used in the industry mainly comprises the following two modes:

1. the torque tightening gun and the special clamp are utilized to manually carry out semiautomatic operation to tighten the bolt;

2. Setting a specific clamp and installing the specific clamp on a flange of an industrial mechanical arm, so that the specific clamp can realize the tightening operation of a specified bolt in a specific scene;

The two modes all expose certain technical problems, for example, if a manual mode is adopted, special staff is required to be arranged for tightening operation, under the environment that the population is in a red interest gradually fading, the personnel cost is continuously increased, the tightening working strength is high, the action machinery is repeated, the staff is extremely easy to generate fatigue and even aversion emotion after working for a long time, the equipment and personal safety can be influenced when serious, and the tightening force of the bolts can be fluctuated due to different operation habits, so that the instability is particularly prominent in the technical field of products requiring high precision and high quality.

And the tightening gun is matched with the mechanical arm, so that the tightening operation of the system is basically completed by the tightening gun. When the bolt needs great tightening torque, if the tightening gun is fixed with the mechanical arm flange, the mechanical arm flange motor can receive very big counter moment, probably can lead to the fact the damage to the motor shaft, produces deformation and fracture, and the moment of torsion of pretension rifle is limited, probably can not export great moment.

Disclosure of Invention

The invention aims at overcoming the defects of the prior art, and provides a robot tail end mechanism capable of providing large tightening torque, which can be connected with a mechanical arm flange and can effectively reduce the counter moment applied to the flange when a bolt is tightened by a tightening gun.

In order to solve the technical problems, the invention provides the following technical scheme:

The robot end effector for providing large tightening torque is characterized by comprising a connecting mechanism connected with the tail end of an industrial robot, a clutch mechanism arranged outside the connecting mechanism and a large tightening torque mechanism connected with the clutch mechanism;

The connecting mechanism comprises a connecting substrate, a visual positioning camera and a pretension gun, wherein the connecting substrate is fixedly connected to an end flange of the industrial robot, a protruding stepped shaft is arranged on one side, far away from the end flange, of the connecting substrate, the visual positioning camera is fixedly connected to the connecting substrate through a camera support and used for automatically positioning a bolt to be screwed, and the pretension gun is fixedly connected to the connecting substrate and used for pre-screwing the bolt;

the clutch mechanism comprises a clutch frame, a pressure plate, a friction plate and a clutch control device, wherein the clutch frame is coaxially and rotatably connected to the protruding stepped shaft through a clutch frame bearing and is axially fixed through a retainer ring, the pressure plate and the friction plate are arranged on the clutch frame through a spline coaxial movable connecting sleeve, the pressure plate, the friction plate and a connecting substrate are sequentially stacked from outside to inside, and the clutch control device is arranged on the clutch frame and can control the pressure plate to axially move along the clutch frame so as to change the contact or separation of the friction plate and the connecting substrate;

The large tightening torque mechanism comprises a torsion bar, a ratchet wheel and a ratchet wheel end cover, wherein one end of the torsion bar is connected with the clutch frame, the other end of the torsion bar is provided with a groove, the ratchet wheel end cover is covered outside the groove, one end of the ratchet wheel is connected in the groove, the other end of the ratchet wheel is a long stepped shaft which is arranged on the ratchet wheel end cover in a penetrating mode and protrudes out of the groove, and a hexagonal groove is formed in the end face of the long stepped shaft and used for connecting and tightening a bolt or a nut.

Further, the clutch control device comprises an air cylinder and a clutch lever, the air cylinder is fixedly connected to the clutch frame through an air cylinder support, the clutch lever is arranged at an opening of the clutch frame, a lever pivot of the clutch lever and the opening of the clutch frame form a rotating pair through a pin, the clutch lever can rotate around the lever pivot, one end of the clutch lever is connected with a push rod of the air cylinder, the other end of the clutch lever is connected in a groove of the pressure plate, and when the air cylinder works, the push rod can push the clutch lever to rotate around the lever pivot, so that the pressure plate is driven to axially move along the clutch frame.

Further, the large tightening torque mechanism further comprises a pawl, a spring, a ratchet upper bearing and a ratchet lower bearing, a semicircular small groove is formed in one side, close to the mechanical arm main body, of the groove, a cylindrical protrusion is arranged on one side of the pawl, the ratchet is rotationally connected in the semicircular small groove, three protruding helical teeth are arranged on the other side of the pawl, the helical teeth are meshed with outer teeth of the ratchet, one end of the spring is fixed in the groove, the other end of the spring is fixed on the pawl, the pawl can limit the ratchet to rotate only anticlockwise and not clockwise, the ratchet is connected to the bottom of the groove through the ratchet upper bearing, and the ratchet end cover is connected with the ratchet through the ratchet lower bearing.

Further, the middle part of the torsion bar is a beam of I-steel type.

Further, the clutch mechanism further comprises a contraction mechanism arranged between the clutch mechanism and the large tightening torque mechanism, the contraction mechanism comprises a stepping motor and a shaft sleeve, the connecting part of the clutch frame and the torsion bar is a C-shaped groove, the stepping motor is fixedly connected to the clutch frame, the shaft sleeve is arranged on the C-shaped groove in a penetrating mode, an output shaft of the stepping motor is coaxially and fixedly connected with the shaft sleeve, the torsion bar is fixedly connected to the shaft sleeve, and the stepping motor can drive the torsion bar to rotate by taking the shaft sleeve as a shaft.

Further, the shrinkage mechanism further comprises a torsion bar upper bearing and a torsion bar lower bearing, the upper end of the C-shaped groove is connected with the shaft sleeve through the torsion bar upper bearing, and the lower end of the C-shaped groove is connected with the shaft sleeve through the torsion bar lower bearing, so that the stability and smoothness of the torsion bar in the rotating process are ensured.

Further, a gasket is arranged between the torsion bar upper bearing and the torsion bar, so that the upper end face of the torsion bar is not interfered with the outer ring of the torsion bar upper bearing.

Further, the shaft sleeve and the output shaft of the stepping motor are connected with each other through a flat key connected with the shaft sleeve through the motor.

Further, the shaft sleeve and the torsion bar are connected with each other through a flat key connected with the torsion bar through the shaft sleeve.

Compared with the prior art, the manipulator has the beneficial effects that the manipulator simulates the action of screwing the bolt by a spanner, and transmits the force of the tail end of the robot to the bolt to be screwed through the longer torsion bar, so that the screwing operation of the bolt is completed. In the process, the clutch mechanism is connected with the protruding stepped shaft of the connecting substrate through the bearing, the bearing only transmits force and does not transmit moment, the flange at the tail end of the robot is subjected to resistance generated during screwing, and larger resistance moment caused by no resistance force is effectively solved, the problems that the torque of the pretightening gun is insufficient and the motor shaft of the flange at the tail end of the mechanical arm is damaged due to the fact that the motor shaft of the flange at the tail end of the mechanical arm is subjected to the maximum torque under the special condition of needing the maximum torque are solved, meanwhile, different postures of the screwing mechanism at the tail end of the robot under working and preparation are realized through the contraction mechanism, and the robot is retracted in the preparation state, so that the occupied space in the state is well saved.

Drawings

Fig. 1 is a schematic overall structure of an embodiment of the present invention.

Fig. 2 is an axial cross-sectional view of a clutch mechanism in an embodiment of the invention.

Fig. 3 is an axial cross-sectional view of a retraction mechanism in an embodiment of the present invention.

Fig. 4 is a transverse cross-sectional view of a high tightening torque mechanism in an embodiment of the invention.

Fig. 5 is a transverse cross-sectional view of the end structure when the robot is in operation.

Fig. 6 is a schematic view of the retraction mechanism retracting the torsion bar with the robot in a ready state.

Fig. 7 is a schematic view of a clutch lever according to an embodiment of the present invention.

Fig. 8 is an initial posture diagram and an end posture diagram of the embodiment of the present invention in one tightening process.

The robot comprises a 1-robot base, a 21-mechanical arm, a 22-end flange, a 31-connecting base plate, a 311-protruding stepped shaft, a 32-visual positioning camera, a 33-camera support, a 34-pretensioning gun, a 41-cylinder support, a 42-cylinder, a 43-clutch bracket, a 44-clutch bracket outer bearing, a 45-retainer, a 46-clutch bracket fixing bolt, a 47-clutch bracket inner bearing, a 48-flange connecting bolt, a 49-friction plate, a 410-pressure plate, a 411-clutch lever, a 412-pin, a 51-stepping motor, a 52-motor bolt, a 53-torsion bar upper bearing, a 54-gasket, a 55-motor and shaft sleeve connecting flat key, a 56-shaft sleeve, a 57-end cover, a 58-torsion bar lower bearing, a 59-shaft sleeve connecting flat key, a 510-C-shaped groove, a 61-torsion bar, a 62-pawl, a 63-spring, a 64-ratchet, a 641-long stepped shaft, a 642-hexagonal groove, a 65-ratchet upper bearing, a 66-ratchet lower bearing, a 67-ratchet end cover, a 68-end cover and a 69-groove.

Detailed Description

In order to enhance the understanding of the present invention, the present invention will be further described in detail with reference to the drawings, which are provided for the purpose of illustrating the present invention only and are not to be construed as limiting the scope of the present invention.

Fig. 1-8 illustrate an embodiment of a robot end effector that provides a high tightening torque, including a connection mechanism to an end of an industrial robot, a visual positioning camera 32 secured to the connection mechanism, a pretensioner gun 34 secured to the connection mechanism, a clutch mechanism disposed outside the connection mechanism, an air cylinder 42 disposed above the clutch mechanism, a retraction mechanism disposed on one side of the clutch mechanism, and a high tightening torque mechanism disposed on one side of the retraction mechanism.

The connecting mechanism is fixed with the end flange 22 of the industrial robot through bolts, and can follow the movement of the mechanical arm to adjust the direction in the actual process. The visual positioning camera 32 can be loaded on one side of the connecting mechanism, the function of automatically positioning a bolt to be screwed is achieved, the pretension gun 34 is arranged on the lower side of the visual positioning, the bolt pretension function is achieved, the clutch mechanism is arranged on the outer side of the connecting mechanism, separation of the clutch frame and the connecting mechanism is achieved, the situation that the tail end is subjected to larger counter moment in the screwing process is avoided, the contraction mechanism is arranged on one side of the clutch mechanism, the gesture adjustment of the large screwing torque mechanism in different states is achieved, the working space is effectively saved, the contraction mechanism is connected with the large screwing torque mechanism, and the screwing of the bolt is achieved through a spanner-like screwing mode.

The connecting mechanism comprises a connecting substrate 31 which is connected with the tail end flange 22 of the industrial robot through threads, a camera support 41 which is arranged on one side of the connecting substrate 31 and is connected with the connecting substrate through threads, a pretensioner gun 34 which is arranged on the lower side of the camera support 41 and is fixed on the connecting substrate 31, the connecting substrate 31 is not a uniform thin plate, but an irregular piece with a protruding stepped shaft 311 on one side, and the protruding stepped shaft 311 plays a role of supporting the whole clutch mechanism. In the actual tightening process, the specific position of the bolt to be tightened is firstly positioned through the visual camera 32, the mechanical arm 21 is adjusted to a proper tightening gesture, then the pre-tightening gun 34 works, pre-tightening is realized, the industrial robot is not required to control the large tightening torque mechanism to rotate the whole arc around the bolt to be tightened, and the efficiency of the tightening process is improved.

The clutch mechanism comprises a clutch frame 43 at the outermost side, an opening is arranged at the upper side of the clutch frame 43, and holes are arranged at two sides of the opening, so that pins can be conveniently driven in. The clutch frame 43 and the connection substrate 31 are provided with a gap, a friction plate 49 and a pressure plate 410 are arranged in the gap, the clutch frame 43 and the protruding stepped shaft 311 of the connection substrate are connected through a clutch frame outer bearing 44 and a clutch frame inner bearing 47, so that the clutch frame 43 can stably rotate around the protruding stepped shaft 311 of the connection substrate, a screw hole is formed in the upper side of the clutch frame 43, the cylinder support 41 is connected with the clutch frame 43 through a bolt, the cylinder 42 is connected with the cylinder support 41 through a bolt, a groove is formed in one side of a push rod of the cylinder 42, the clutch lever 411 is arranged at an opening of the clutch frame 43, a rotating pair is formed between a lever fulcrum and an opening of the clutch frame 43 through a pin 412, and the function that the clutch lever 411 can rotate around the lever fulcrum is realized. The upper side of the clutch lever 411 penetrates through a groove of a push rod of the air cylinder 42, the lower side of the clutch lever extends into the groove of the pressure plate 410, the pressure plate 410 and the friction plate 49 are connected with the clutch frame 43 through splines and can axially move on the clutch frame 43, a retainer ring 45 and a clutch frame fixing bolt 46 are arranged on the outermost side of the clutch frame 43, the retainer ring 45 is fixed on the end face of the protruding stepped shaft 311 through threaded connection, the retainer ring 45 abuts against the inner ring of the clutch frame outer bearing 44, the shaft shoulder of the protruding stepped shaft 311 abuts against the inner ring of the clutch frame inner bearing 47, the clutch frame 43 abuts against the clutch frame outer bearing 44 and the bearing outer ring of the clutch frame inner bearing 47, and axial positioning of the double bearings is achieved. When the clutch mechanism is in a separation state, as shown in fig. 2 (b), the push rod of the air cylinder 42 is pushed outwards, so that the clutch lever 411 rotates clockwise around the lever fulcrum to drive the pressure plate 410 to axially move in a direction away from the flange 22, the friction plate 49 is separated from the connecting substrate 31 due to being not extruded, the separation function of the clutch frame 43 and the connecting substrate 31 is realized, when the clutch mechanism is in a combination state, as shown in fig. 2 (a), the push rod of the air cylinder 42 is retracted inwards, so that the clutch lever 411 rotates anticlockwise around the fulcrum to drive the pressure plate 410 to axially move in a direction close to the flange 22, the pressure plate 410 is forced to extrude the friction plate 49 to extrude the connecting substrate 31 and generate friction force and friction moment, and at the moment, the clutch frame 43 and the connecting substrate 31 are completely pressed together through the friction moment, so that the combination function of the clutch frame 43 and the connecting substrate 31 is realized. In the coupled state, the clutch outer bearing 44 and the clutch inner bearing 47 lose the rotation function, and only support the clutch 43 and the protruding stepped shaft 311. By controlling the telescopic state of the push rod of the air cylinder 42, the separation and combination functions of the clutch mechanism are realized.

The retraction mechanism includes a stepper motor 51, motor bolts 52, torsion bar upper bearings 53, torsion bar lower bearings 58, shaft sleeve 56, shims 54, motor to shaft sleeve connection flat key 55, shaft sleeve to torsion bar connection flat key 59, and end cap 57. The stepper motor 51 is fixed on the upper side of the clutch frame 43, and is connected with the clutch frame 43 through a motor bolt 52, the connection part of the clutch frame 43 and the torsion bar 61 is a C-shaped groove 510, and a T-shaped hole for conveniently positioning the upper bearing 53 of the torsion bar is arranged in the middle. The output shaft of the stepping motor 51 extends into the C-shaped groove 510, and because the output shaft has a limited length, the shaft sleeve 56 is required to extend the output length range of the motor shaft, a key slot is reserved on the inner side of the shaft sleeve 56, the output shaft of the stepping motor 51 is connected with the shaft sleeve connecting flat key 55 through the motor, a key slot is reserved on the outer side of the stepping motor, the stepping motor is connected with the torsion bar 61 through the shaft sleeve connecting flat key 59, a protruding shaft shoulder is arranged on the part, close to the lower end face, of the shaft sleeve 56 so as to facilitate the positioning of the inner ring of the torsion bar lower bearing 58, a gasket 54 is arranged between the torsion bar upper bearing 53 and the torsion bar 61, the end face of the torsion bar 61 is not interfered with the outer ring of the torsion bar upper bearing 53, an end cover 57 is arranged outside the lower end face of the C-shaped groove 510 of the clutch frame 43, the end cover 57 is fixed with the clutch frame 43 through bolts, and the flange part of the end cover 57 is positioned as the outer ring of the torsion bar lower bearing 58. When the stepping motor 51 is controlled to rotate, the torque of the output shaft of the stepping motor 51 is transmitted to the shaft sleeve 56 through the motor and shaft sleeve connecting flat key 55, and then the shaft sleeve 56 is transmitted to the shaft sleeve and torsion bar connecting flat key 59 to drive the torsion bar 61 to rotate around the shaft sleeve 56 by a specific angle, and the stability and smoothness of the whole rotation process are ensured by the torsion bar upper bearing 53 and the torsion bar lower bearing 58. By controlling the angular displacement of the stepping motor 51, the rotation function of the torsion bar 61 is realized, so that the arm can be retracted in the standby state and extended in the working state, thereby saving the working space of the arm end mechanism.

The large tightening torque mechanism includes a torsion bar 61, a ratchet 64, a spring 63, a pawl 62, a ratchet end cap 67, and ratchet upper and lower bearings 65, 66. The middle part of the torsion bar 61 is a beam of I-shaped steel, the weight of the beam is greatly reduced under the requirement of ensuring the strength, the right side is a groove 69, a T-shaped hole is arranged at the bottom of the groove 69, the positioning and the installation of the outer ring of the upper bearing 65 of the ratchet wheel are facilitated, a semicircular small groove is arranged on one side of the groove 69 close to the main body of the mechanical arm 21, the installation of the pawl 62 is facilitated, a rotating pair is formed by the pawl 62, one side of the pawl 62 is a cylindrical protrusion and is embedded in the semicircular small groove, three protruding bevel teeth are arranged on the other side, the bevel teeth are meshed with the external teeth of the ratchet wheel 64, one end of the spring 63 is fixed in the groove of the torsion bar 61, the other end is fixed at the lower part of the pawl 62, when the pawl 62 rotates clockwise, the outer teeth of the ratchet wheel 64 spring up the helical teeth of the pawl 62, move around the rotary pair on the circular protrusion side, and press down the spring 63, at this time, the pawl 62 does not change the moving state of the ratchet wheel 64, when the pawl 62 rotates counterclockwise, the helical teeth of the pawl 62 are meshed with the outer teeth of the ratchet wheel 64 by the elastic force generated by the compression of the spring 63, the ratchet wheel 64 is forced to rotate together with the pawl 62 due to the constraint of the rotary pair, at this time, the ratchet wheel 64, the pawl 62 and the torsion bar 61 are equivalent to being fixedly connected together, and the screwing operation can be performed. One side of the ratchet wheel 64 is provided with a solid protruding short stepped shaft with a smaller diameter, a shaft shoulder is convenient for positioning and mounting the inner ring of the ratchet wheel upper bearing 65, the other side is provided with a long stepped shaft 641 with a larger diameter, the end face of the long stepped shaft 641 extends out of the groove 69, a hexagonal groove 642 is formed in the extending end face of the long stepped shaft 641, a hexagonal bolt or a hexagonal nut is convenient to screw down, and the shaft shoulder of the long stepped shaft 641 is convenient for positioning and mounting the inner ring of the ratchet wheel lower bearing 66. Through holes are formed in two sides of the ratchet end cover 67 and fixedly connected with the outer end face of the groove 69 through bolts, a through hole is formed in the middle of the ratchet end cover 67, the long stepped shaft 641 is conveniently stretched out, and a flange slightly larger than the diameter of the middle through hole is arranged on the inner side, so that the outer ring of the ratchet lower bearing 66 is conveniently positioned and installed.

When the robot is in a standby or standby state, the separation between the pressure plate 410 and the friction plate 49 is realized through the control of the push rod of the air cylinder 42 in the clutch mechanism, the clutch mechanism and the large tightening torque mechanism can downwards vertically face the ground under the influence of gravity, and the whole large tightening torque mechanism can shrink inwards of the robot through the control of the angular displacement of the stepping motor 51 in the shrink mechanism and is finally parallel to the four shafts of the mechanical arm 21, so that the environment space occupied by the robot in the standby state is effectively reduced.

When the robot is in operation, the pressure plate 410 moves toward the connection substrate 22 by the control of the push rod of the air cylinder 42 in the clutch mechanism, and the friction plate 49 is pressed tightly against the connection substrate 22. When the flange 22 at the end of the arm is rotated, the connection base plate 31 and the clutch frame 43 are simultaneously rotated around the center of the flange, and the vision positioning camera 32, the pretensioner gun 34, and the clutch mechanism are rotated to the working position to be on standby. After the visual positioning camera 32 accurately positions the bolt, the bolt to be screwed is pre-tightened by the pre-tightening gun 34, and then the angular displacement of the stepping motor 51 in the contraction mechanism is controlled, so that the large screwing torque mechanism extends out to be parallel to the end face of the clutch frame 43. The torsion bar 61 is a fixed size, and the hexagonal bolt to be screwed can be inserted into the hexagonal groove on the outer side of the screwing mechanism by changing coordinates and moving the robot tip. The clutch mechanism is controlled again to be in a separation state, the mechanical arm 21 takes the tightening bolt as the center of a circle, a person is simulated to use a spanner to tighten the bolt, the large tightening torque mechanism is driven to do circular arc movement from top to bottom anticlockwise, the pawl 62, the ratchet wheel 64 and the torsion bar 61 are fixedly connected together, the ratchet wheel 64 rotates anticlockwise along with the ratchet wheel, the bolt is tightened, when the tail end of the mechanical arm 21 needs to be returned to the initial position again to carry out second tightening operation, the mechanical arm 21 drives the large tightening torque mechanism to do circular arc movement from bottom to top clockwise, the pawl 62 is separated from the ratchet wheel 64, and the function that the ratchet wheel 64 is not moved and the mechanical arm returns to the initial position is realized.

The specific working process and principle of the embodiment are as follows:

As shown in fig. 1, the embodiment is arranged on a robot base 1, and comprises a connecting mechanism for connecting a tail end flange 22 of a mechanical arm 21, a clutch mechanism for realizing separation or combination of the tail end mechanism and the mechanical arm flange, a telescopic mechanism for realizing different postures of a high-torque tightening mechanism in different working states, and a high-tightening torque mechanism for final tightening.

The robot is in a preparation state at the initial moment, the large tightening torque mechanism is contracted in the robot, the clutch mechanism is in a separation state, at the moment, the flange is only subjected to gravity and gravity moment brought by the tail end mechanism, and as shown in fig. 6, after the bolt to be tightened is in a working area, the robot starts to work. Firstly, the position of the bolt is obtained by the visual positioning camera 32 fixed on the connecting mechanism, and the position information is sent to the control system, and the control system obtains a change coordinate through the space geometric relation between the pretensioning gun 34 and the visual positioning camera 32 and controls the pretensioning gun 34 to reach the position of the bolt to be screwed. The pre-tightening gun 34 rotates faster and can be used for pre-tightening bolts, so that the working efficiency is greatly improved, after the pre-tightening gun 34 is completely pre-tightened, the air cylinder 42 retracts inwards to force the clutch lever 411 to rotate along the rotating pair of the pre-tightening gun, and as the tail end of the clutch lever 411 contacts with the groove of the pressure plate 410, when the air cylinder 42 retracts, the tail end of the clutch lever 411 drives the pressure plate 410 to axially move along the spline surface towards the tail end flange 22, and finally the pressure plate 410 presses the friction plate 49 to generate friction torque, the friction plate 49 is forced to press the connecting substrate 31 to generate friction torque, at the moment, the tail end flange 22 is controlled to axially rotate to a proper position, the friction plate 49 and the pressure plate 410 rotate together with the tail end flange 22 by the same angle, and 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 whole clutch mechanism rotate together by the same angle. The clutch outer bearing 44 and the clutch inner bearing 47 have only a supporting effect in this process.

The stepping motor 51 is fixed with the outside of the clutch frame 43 through a motor bolt 52, after the clutch frame 43 rotates to a designated position, the stepping motor 51 is started, the motor shaft moment is transmitted to the shaft sleeve 56 through the motor and shaft sleeve connecting flat key 55, and then the motor shaft moment is transmitted to the torsion bar 61 through the shaft sleeve and torsion bar connecting flat key 59 to drive the motor shaft moment to rotate. The outside of the torsion bar 61 is made parallel to the outside of the clutch frame 43 by controlling the stepping motor 51 to rotate a certain angle. Because the spatial geometry of the visual positioning camera 32 and the ratchet wheel 64 in this state is fixed, each joint of the mechanical arm 21 can be moved or the workpiece can be moved by corresponding coordinate transformation, so that the hexagonal bolt to be screwed extends into the hexagonal recess 642 of the end face of the long stepped shaft 641 outside the ratchet wheel 64, and preparation for final screwing is made.

After the last step of working procedure is finished, the robot can be controlled to carry out final high-torque screwing operation. As shown in fig. 2 (b), first, the telescopic cylinder 42 is controlled to be in an extended state, the clutch lever 411 rotates to drive the pressure plate 410 to move away from the end flange 22, the friction plate 49 is released from compression, and the friction torque is lost. The clutch frame 43 is rotatable about the central axis by a clutch frame outer bearing 44 and a clutch frame inner bearing 47. The attitude of the robot arm 21 is then controlled so that the tip position is rotated at a higher position centering on the bolt to be screwed, as shown in fig. 8 (a), which is a high torque screwing start point. During the clockwise upward rotation, the pawl 62 also rotates clockwise along the outer contour of the ratchet wheel 64, the outer teeth of the ratchet wheel 64 spring up the pawl 62 helical teeth, move around the pair of rotation on the circular projection side, and press down the spring 63, at which time the pawl 62 does not change the state of the ratchet wheel 64.

After the large torque tightening mechanism reaches the starting point posture, the mechanical arm 21 is controlled to do circular arc movement by taking the tightening bolt as the center of a circle, the hexagonal groove 642 in the end face of the long stepped shaft 641 of the large torque mechanism is required to be guaranteed to be always wrapped on the hexagonal bolt in the whole process, in the circular arc movement process, the end flange 22 of the mechanical arm 21 applies force to the connecting base plate 31 to drive the clutch frame 43 and the torsion bar 61 to do anticlockwise movement, the clutch frame 43 and the connecting base plate 31 are connected through the clutch frame outer bearing 44 and the clutch frame outer bearing 47, the bearings only transmit force and do not transmit torque, so that the end flange 22 on the mechanical arm 21 is only subjected to constraint reaction force fed back when the tightening bolt, but not constrained torque, when the torsion bar 61 drives the pawl 62 to anticlockwise rotate, the pawl 62 is propped against the outer tooth of the ratchet wheel 64 by elasticity generated by compression, the ratchet wheel 64 and the ratchet wheel 64 are driven to jointly rotate, and the ratchet wheel 64, the pawl 62 and the torsion bar 61 are correspondingly fixedly connected together, and the end posture of the mechanical arm 21 for completing the tightening operation is as shown in fig. 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 moment is generated, so that the function of large tightening torque is realized, and the end flange 22 is protected. If the bolts do not meet the requirement at this time, the mechanical arm 21 is moved clockwise to the initial state along the same circular arc, and the above process is repeated.

The foregoing detailed description will set forth only for the purposes of illustrating the general principles and features of the invention, and is not meant to limit the scope of the invention in any way, but rather should be construed in view of the appended claims.

Claims (7)

1. The robot end effector for providing large tightening torque is characterized by comprising a connecting mechanism connected with the tail end of an industrial robot, a clutch mechanism arranged outside the connecting mechanism and a large tightening torque mechanism connected with the clutch mechanism;

The connecting mechanism comprises a connecting substrate (31), a visual positioning camera (32) and a pre-tightening gun (34), wherein the connecting substrate (31) is fixedly connected to an end flange (22) of the industrial robot, a protruding stepped shaft (311) is arranged on one side, far away from the end flange (22), of the connecting substrate (31), the visual positioning camera (32) is fixedly connected to the connecting substrate (31) through a camera support (33) and is used for automatically positioning a bolt to be screwed, and the pre-tightening gun (34) is fixedly connected to the connecting substrate (31) and is used for pre-tightening the bolt;

The clutch mechanism comprises a clutch frame (43), a pressure plate (410), friction plates (49) and a clutch control device, wherein the clutch frame (43) is coaxially connected to the protruding stepped shaft (311) through a clutch frame bearing in a rotating way and is axially fixed through a check ring (45), the pressure plate (410) and the friction plates (49) are arranged on the clutch frame (43) through spline coaxial movable connecting sleeves, the pressure plate (410), the friction plates (49) and the connecting substrate (31) are sequentially stacked from outside to inside, and the clutch control device is arranged on the clutch frame (43) and can control the pressure plate (410) to axially move along the clutch frame (43), so that contact or separation between the friction plates (49) and the connecting substrate (31) is changed;

the clutch control device comprises an air cylinder (42) and a clutch lever (411), wherein the air cylinder (42) is fixedly connected to the clutch frame (43) through an air 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 the opening of the clutch frame (43) form a rotating pair through a pin (412), the clutch lever can rotate around the lever fulcrum, one end of the clutch lever (411) is connected with a push rod of the air cylinder (42), the other end of the clutch lever is connected in a groove of the pressure plate (410), and when the air cylinder (42) works, the push rod can push the clutch lever (411) to rotate around the lever fulcrum, so that the pressure plate (410) is driven to axially move along the clutch frame (43);

The large tightening torque mechanism comprises a torsion bar (61), a ratchet wheel (64) and a ratchet wheel end cover (67), one end of the torsion bar (61) is connected with the clutch frame (43), the other end of the torsion bar is provided with a groove (69), the ratchet wheel end cover (67) is covered outside the groove (69), one end of the ratchet wheel (64) is connected in the groove (69), the other end of the ratchet wheel is a long stepped shaft (641) which is arranged on the ratchet wheel end cover (67) in a penetrating way and protrudes out of the groove (69), and a hexagonal groove (642) is formed in the end face of the long stepped shaft (641) and used for connecting and tightening a bolt or a nut;

The large tightening torque mechanism further comprises a pawl (62), a spring (63), a ratchet upper bearing (65) and a ratchet lower bearing (66), a semicircular small groove is formed in one side, close to the main body of the mechanical arm (21), of the groove (69), one side of the pawl (62) is provided with a cylindrical protrusion, the pawl is rotationally connected in the semicircular small groove, three protruding bevel teeth are formed in the other side of the pawl, the bevel teeth are meshed with the outer teeth of the ratchet (64), one end of the spring (63) is fixed in the groove (69), the other end of the spring is fixed to the pawl (62), the pawl (62) can limit the ratchet (64) to rotate anticlockwise only and cannot rotate clockwise, the ratchet (64) is connected to the bottom of the groove (69) through the ratchet upper bearing (65), and the ratchet end cover (67) is connected with the ratchet through the ratchet lower bearing (66).

2. The robot end effector of claim 1, wherein the torsion bar (61) has a beam of I-steel type at a middle portion thereof.

3. The robot end effector for providing large tightening torque according to claim 1, further comprising a contraction mechanism arranged between the clutch mechanism and the large tightening torque mechanism, wherein the contraction mechanism comprises a stepping motor (51) and a shaft sleeve (56), the connection part of the clutch frame (43) and the torsion bar (61) is a C-shaped groove (510), the stepping motor (51) is fixedly connected to the clutch frame (43), the shaft sleeve (56) is arranged on the C-shaped groove (510) in a penetrating manner, an output shaft of the stepping motor (51) is fixedly connected with the shaft sleeve (56) in a coaxial manner, the torsion bar (61) is fixedly connected to the shaft sleeve (56), and the stepping motor (51) can drive the torsion bar (61) to rotate by taking the shaft sleeve (56) as a shaft.

4. The robot end effector according to claim 3, wherein the contraction mechanism further comprises a torsion bar upper bearing (53) and a torsion bar lower bearing (58), wherein the upper end of the C-shaped groove (510) is connected with the shaft sleeve (56) through the torsion bar upper bearing (53), and the lower end of the C-shaped groove (510) is connected with the shaft sleeve (56) through the torsion bar lower bearing (58), so that the stability and smoothness of the rotation process of the torsion bar (61) are ensured.

5. The robot end effector for providing a large tightening torque according to claim 4, wherein a spacer (54) is provided between the torsion bar upper bearing (53) and the torsion bar (61) so that an upper end surface of the torsion bar (61) does not interfere with an outer ring of the torsion bar upper bearing (53).

6. A robot end effector for providing high tightening torque according to claim 3, wherein the shaft sleeve (56) and the output shaft of the stepper motor (51) are connected to each other by a motor-to-shaft sleeve connection flat key (55).

7. A robotic end effector as claimed in claim 3, wherein the shaft sleeve (56) and torsion bar (61) are interconnected by a shaft sleeve and torsion bar connecting flat key (59).