CN108818303B - End effector for polishing and grinding force control of robot - Google Patents

Abstract

The invention discloses a robot polishing force control end effector, which comprises a rotating part, a linear motion part and a polishing head part. The actuator uses an air motor as the power source, which effectively reduces the total mass of the actuator. Avoiding the use of couplings reduces the complexity of the mechanism and makes the structure more compact. The rotary motion of the air motor is transmitted to the ball spline through the main shaft, and the ball spline transmits the rotary motion to the grinding head part. Since the ball spline has the function of transmitting torque without "tight" connection, the two degrees of freedom of the grinding head are mechanically decoupled at the ball spline. Compared with the invention that the actuator and the macro robot system are connected at the top of the actuator, the invention effectively reduces the overturning moment of the polishing surface and improves the polishing quality. The invention can realize the control of important polishing parameters such as polishing tool force and polishing speed, and the actuator has simple structure, small mass, high force control precision and fast response speed.

Description

A force-controlled end effector for robot polishing

technical field

The invention relates to the technical field of automation equipment and robots, in particular to a robot polishing force-controlled end effector.

Background technique

With the rapid development of industrial robots, their applications in various industrial fields are becoming more and more extensive. In some contact operations, industrial robots are required to have the ability to perceive and control contact force to meet the requirements of precision operations, such as grinding, polishing and assembly operations. During the grinding and polishing operation, the processing tool wears with use, resulting in surface position error, which changes the contact force and affects the processing effect. Therefore, realizing the constant force contact between the tool and the workpiece has important practical significance for the application of industrial robots in contact operations.

Grinding, as a typical example of contact work, requires smooth control of the grinding system. The contradiction between the high requirements for the flexibility of the robot to be able to generate arbitrary forces when operating in a specific contact environment and the high requirements for the rigidity of the position servo and the rigidity of the mechanical structure when the robot operates in free space. The ability of a robot to obey its contact environment is called compliance. Compliance is divided into active compliance and passive compliance. With some auxiliary compliant mechanisms, the robot can naturally obey the external force when in contact with the environment, which is called passive compliance; the robot system uses force feedback information to actively control the force by using a certain control strategy, which is called active compliance. The passive and compliant method is: passive compliant robot deburring, usually knowing the 3D model of the workpiece, fixing the workpiece on the fixture, and polishing the tool at the end of the robot to follow the contour of the workpiece. The purpose of material removal is achieved through the high-speed rotation of the tool head. Generally, there is no force control, which means that most of the current grinding cases are achieved through direct programming. This method cannot achieve automatic deceleration and track change when encountering a large amount of cutting. At present, there are mainly two ways to achieve passive compliance: first, the robot clamps the workpiece, and adjusts the grinding force through the tension of the abrasive belt; second, the robot clamps the tool, and the tool compliance adopts a mechanical spring to achieve passive compliance. Active compliance can be divided into two ways from a large perspective. One is realized by the robot controller, which represents a force/bit hybrid control method. Because this method needs to realize force and position control at the same time, there is force/position coupling, so the implementation is more complicated; second, the active force control based on the end tool. Generally speaking, using algorithms to realize impedance control and force/position hybrid control by robot controllers has a slow response speed and poor algorithm stability, making it difficult to realize industrial production.

The technical background of force control in contact polishing and grinding has been explained above. It is not difficult to find that under the current technical background, the development of robot polishing force-controlled end effector is a reasonable way to realize the active and smooth polishing of robot polishing system. Therefore, the prior art needs to be further improved and perfected.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a force-controlled end effector for robot polishing.

The object of the present invention is achieved through the following technical solutions:

A polishing force control end effector for a robot, the end effector mainly includes a grinding head for grinding a workpiece, a rotating part for driving the grinding head to rotate, and a linear motion part for driving the grinding head to feed. The rotating part is connected with the mechanical arm, and its output end passes through the linear moving part and is connected with the grinding head in transmission.

Specifically, the rotating part includes an air motor, a motor bracket, an L-shaped connector, a main shaft, a key, and a bearing assembly. One side of the L-shaped connector is fixedly connected with the grinding mechanical arm, and the air motor is fixedly installed on the other side of the L-shaped connector through the motor bracket. One end of the main shaft is connected to the output end of the air motor through the key, and the other end is connected to the grinding head. The bearing assembly is installed on the L-shaped connector, and its inner ring is in interference fit with the main shaft.

Specifically, the linear motion part mainly includes a tension-torsion compound force sensor, an upper annular connector, a motor mounting sleeve, a linear motor stator, a linear motor mover, a lower annular connector, a bearing inner ring retaining ring, an angular contact ball bearing, and a retaining ring. The tension-torsion composite force sensor is arranged under the air motor, and is fixedly connected to the L-shaped connector through bolts. The tension-torsion compound force sensor is fixedly connected with the linear motor stator through the upper ring connector and the motor mounting sleeve. The linear motor mover is arranged in the linear motor stator, and its lower end is fixedly connected with the lower annular connecting piece. The upper end of the retaining ring of the inner ring of the bearing is fixed to the lower annular connecting piece through bolts, and the lower end thereof is fixedly connected to the elastic retaining ring. The angular contact ball bearing is arranged outside the retaining ring of the inner ring of the bearing, between the top of the retaining ring of the inner ring of the bearing and the elastic retaining ring.

Specifically, the grinding head mainly includes a retaining ring, a bearing outer ring retaining ring, a ball spline, an abrasive mounting disc, and abrasives. The upper end of the retaining ring of the outer ring of the bearing is connected to the retaining ring through bolts, and its inner wall abuts against the angular contact ball bearing. The ball spline is arranged in the retaining ring of the bearing outer ring, and its bottom is fixedly connected with the retaining ring of the bearing outer ring and the abrasive mounting plate through bolts, and its inner wall is connected with the main shaft, so that the main shaft drives the ball spline to rotate and the ball spline can slide axially on the main shaft. The abrasive is mounted on an abrasive mounting disc.

As a preferred solution of the present invention, in order to improve the load-bearing capacity of the angular contact ball bearings, the angular contact ball bearings in the present invention are set as a pair and installed face to face, so that the angular contact ball bearings can bear the axial load of the main shaft in both directions, thereby improving the service life of the actuator.

As a preferred solution of the present invention, in order to make the bearing assembly easier to locate and install during assembly and use, the upper surface of the L-shaped connector in the present invention is provided with a profile, and the bearing assembly is positioned on the profile of the L-shaped connector through the profile.

As a preferred solution of the present invention, in order to make it easier for the linear motor to meet the assembly requirements and assembly accuracy, the lower annular connector of the present invention is provided with a circular truncated surface for ensuring the installation alignment of the linear motor, and the linear motor mover is installed on the circular truncated surface of the lower circular connector.

As a preferred solution of the present invention, in order to ensure that the grinding head will not fall due to the action of gravity in the non-working state, the bearing outer retaining ring of the present invention is provided with a stepped torus for positioning the angular contact ball bearing. The outer wall of the stepped torus is arranged on the inner wall of the bearing outer retaining ring, and its inner wall is in contact with the angular contact ball bearing. This design allows the angular contact ball bearing to support the grinding head through the bearing outer retaining ring so that it will not fall.

As a preferred solution of the present invention, in order to ensure that the retaining ring of the bearing inner ring does not move upward under the axial force, the upper part of the retaining ring of the bearing inner ring in the present invention is provided with a shoulder for positioning the retaining ring of the bearing inner ring.

The working process and principle of the present invention are: in the present invention, the cutting speed is provided by the air motor of the polishing actuator, avoiding the use of a motor, and greatly reducing the mass of the responding part of the actuator. The polishing actuator can realize the force control of the polishing tool, avoid adjusting the parameters in the polishing operation through the robot controller, and improve the responsiveness of the polishing system. At the same time, the force is also used as a signal to realize the position control of the robot and the feed speed control during the polishing operation. The polishing force and rotary cutting speed can be changed according to the workpieces of different materials and the cutting volume of workpieces.

Compared with the prior art, the present invention also has the following advantages:

(1) The power of the robot polishing force control end effector provided by the present invention is powered by an air motor, which greatly reduces the total mass of the actuator and can be fully loaded until it stops.

(2) The power of the robot polishing force control end effector provided by the present invention adopts an air motor, which is suitable for application in robot polishing operations, without electric sparks, and will not cause explosions of polishing dust.

(3) The pneumatic motor of the robot polishing force control end effector provided by the present invention is connected to the main shaft through a key, and the main shaft and the air motor are connected in one piece, avoiding the use of couplings, thereby reducing the complexity of the mechanism and making the structure more compact.

(4) The robot polishing force control end effector provided by the present invention adopts a bearing assembly, which simplifies the design of the shaft section of the main shaft and reduces the uncertainty introduced by the positioning of the inner and outer rings of the bearing.

(5) The force control end effector of the robot polishing provided by the present invention adopts a linear motor to realize the axial force control in the polishing operation, and has superior force control performance.

(6) The grinding fulcrum of the robot polishing force control end effector provided by the present invention is lower than other existing products, which can ensure that the eccentric torque of the polished surface is small, and ensure the polishing quality of the workpiece surface.

(7) The robot polishing force control end effector provided by the present invention can decouple the rotary motion and the linear motion of the mechanism, and control these two motions separately, so as to realize force control and grinding and cutting speed control. This kind of decoupling realized on the mechanical structure is more suitable for the polishing and grinding contact operation with complex tasks than the decoupling realized on the algorithm.

(8) The robot polishing force control end effector provided by the present invention adopts a force sensor to realize real-time adjustment of the polishing force within the scope of the polishing actuator to ensure the polishing quality.

Description of drawings

Fig. 1 is a schematic structural view of a robot polishing force-controlled end effector provided by the present invention.

Explanation of the symbols in the above drawings: 1-tension and torsion compound force sensor, 2-air motor, 3-motor bracket, 4-L-shaped connecting plate/L-shaped connecting piece, 5-bearing assembly, 6-main shaft, 7-key, 8-linear motor mover, 9-linear motor stator, 10-motor mounting sleeve, 11-bearing inner ring retaining ring, 12-lower annular connector, 13-upper annular connector, 14-angular contact ball bearing, 15-bearing outer ring retaining ring, 16-ball flower Key, 17-retaining ring, 18-abrasive mounting disc, 19-abrasive, 20-retaining ring.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear and definite, the present invention will be further described below with reference to the accompanying drawings and examples.

Example 1:

As shown in FIG. 1 , this embodiment discloses a force-controlled end effector for robot polishing. The end effector mainly includes a grinding head for grinding workpieces, a rotating part for driving the grinding head to rotate, and a linear motion part for driving the grinding head to feed. The rotating part is connected with the mechanical arm, and its output end passes through the linear moving part and is connected with the grinding head in transmission.

Specifically, the rotating part includes an air motor 2 , a motor bracket 3 , an L-shaped connector 4 , a main shaft 6 , a key 7 , and a bearing assembly 5 . One side of the L-shaped connecting piece 4 is fixedly connected with the grinding mechanical arm, and the air motor 2 is fixedly installed on the other side of the L-shaped connecting piece 4 through the motor bracket 3 . One end of the main shaft 6 is connected to the output end of the air motor 2 through the key 7, and the other end is connected to the grinding head. The bearing assembly 5 is installed on the L-shaped connector 4 , and its inner ring is in interference fit with the main shaft 6 .

Specifically, the linear motion part mainly includes a tension-torsion composite force sensor 1, an upper annular connector 13, a motor mounting sleeve 10, a linear motor stator, a linear motor mover 8, a lower annular connector 12, a bearing inner ring retaining ring 11, an angular contact ball bearing 14, and a retaining ring 20. The tension-torsion composite force sensor 1 is arranged under the air motor 2 and is fixedly connected to the L-shaped connector 4 by bolts. The tension-twist compound force sensor 1 is fixedly connected to the linear motor stator 9 through the upper ring connector 13 and the motor mounting sleeve 10 . The linear motor mover 8 is arranged in the linear motor stator 9 , and its lower end is fixedly connected with the lower annular connecting piece 12 . The upper end of the retaining ring 11 of the inner ring of the bearing is fixed to the lower annular connector 12 by bolts, and the lower end thereof is fixedly connected to the elastic retaining ring 20 . The angular contact ball bearing 14 is arranged outside the retaining ring 11 of the inner ring of the bearing, and is located between the top end of the retaining ring 11 of the inner ring of the bearing and the elastic retaining ring 20 .

Specifically, the grinding head mainly includes a retaining ring 17 , a bearing outer ring retaining ring 15 , a ball spline 16 , an abrasive mounting disc 18 , and an abrasive 19 . The upper end of the retaining ring 15 of the bearing outer ring is connected to the retaining ring 17 through bolts, and its inner wall abuts against the angular contact ball bearing 14 . The ball spline 16 is arranged in the bearing outer ring retaining ring 15, and its bottom is fixedly connected with the bearing outer ring retaining ring 15 and the abrasive mounting plate 18 through bolts, and its inner wall is connected with the main shaft 6, so that the main shaft 6 drives the ball spline 16 to rotate and the ball spline 16 can slide axially on the main shaft 6. The abrasive 19 is installed on the abrasive mounting disc 18 .

As a preferred solution of the present invention, in order to improve the load-bearing capacity of the angular contact ball bearing 14, the angular contact ball bearing 14 of the present invention is arranged as a pair and installed in a face-to-face manner, so that the angular contact ball bearing 14 can bear the axial and bidirectional load of the main shaft 6, thereby improving the service life of the actuator.

As a preferred solution of the present invention, in order to make the bearing assembly 5 easier to locate and install during assembly and use, the upper surface of the L-shaped connector 4 in the present invention is provided with a profile, and the bearing assembly 5 is positioned on the profile of the L-shaped connector 4 through the profile.

As a preferred solution of the present invention, in order to make it easier for the linear motor to meet assembly requirements and assembly accuracy, the lower annular connector 12 of the present invention is provided with a circular truncated surface for ensuring the neutrality of the linear motor installation, and the linear motor mover 8 is installed on the circular truncated surface of the lower circular connector 12.

As a preferred solution of the present invention, in order to ensure that the grinding head will not fall due to the action of gravity in a non-working state, the bearing outer retaining ring 15 of the present invention is provided with a stepped torus for positioning the angular contact ball bearing 14.

As a preferred solution of the present invention, in order to ensure that the retaining ring 11 of the bearing inner ring does not move upward under the axial force, the upper part of the retaining ring 11 of the bearing inner ring in the present invention is provided with a shoulder for positioning the retaining ring 11 of the bearing inner ring.

The working process and principle of the present invention are: in the present invention, the cutting speed is provided by the air motor 2 of the polishing actuator, avoiding the use of a motor, and greatly reducing the quality of the response part of the actuator. The polishing actuator can realize the force control of the polishing tool, avoid adjusting the parameters in the polishing operation through the robot controller, and improve the responsiveness of the polishing system. At the same time, the force is also used as a signal to realize the position control of the robot and the feed speed control during the polishing operation. The polishing force and rotary cutting speed can be changed according to the workpieces of different materials and the cutting volume of workpieces.

Example 2:

According to the polishing process, a novel robot end polishing actuator is invented. In the present invention, the cutting speed is provided by the air motor 2 of the polishing actuator, avoiding the use of a motor, and greatly reducing the mass of the responding part of the actuator. The polishing actuator can realize the force control of the polishing tool, avoid adjusting the parameters in the polishing operation through the robot controller, and improve the responsiveness of the polishing system. At the same time, the force is also used as a signal to realize the position control of the robot and the feed speed control during the polishing operation. The polishing force and rotary cutting speed can be changed according to the workpieces of different materials and the cutting volume of workpieces.

The fixed part of the front end of the air motor 2 is clamped by the motor bracket 3 with screws, and the motor bracket 3 and the L-shaped connector 4 are connected together by bolts. The main shaft 6 and the air motor 2 are connected through a key 7 . The bearing assembly 5 is positioned on the L-shaped connector 4 through the profile, and connected by screws, and the inner ring of the bearing assembly 5 and the main shaft 6 adopt interference fit. The main shaft 6 and the bearing assembly 5 are matched to the shaft section of the main shaft 6 between the main shaft 6 and the ball spline 16 and there is no matching relationship with other parts. This is the structural description of the polishing cutting rotating part.

The tension-torsion composite force sensor 1 and the L-shaped connector 4 are connected by 6 evenly distributed bolts, and the inner ring of the tension-torsion composite force sensor 1 and the L-shaped connector 4 adopt transition fit to ensure the coaxiality of the tension-torsion composite force sensor 1 installation. The upper annular connecting piece 13 is connected to the tension-torsion composite force sensor 1 through 6 uniformly distributed screws. The flange of the upper annular connector 13 is flange-connected with the motor mounting sleeve 10, and the motor outer ring 9 and the motor mounting sleeve 10 are connected by 4 countersunk screws. The mover 8 of the linear motor is connected to the lower annular connecting piece 12 through two screws, and the lower annular connecting piece 12 is provided with a circular platform to ensure the centering of the linear motor installation. What this part describes is the structure of the linear motion of the actuator that realizes the polishing force control.

The ball spline 16 used in conjunction with the main shaft 6 is connected with the bearing outer ring retaining ring 15 and the abrasive mounting plate 18 by bolts. There is a stepped torus inside the bearing outer ring retaining ring 15 which can be used for positioning the outer ring of the bearing. The flange of the bearing outer ring retaining ring 15 and the retaining ring 17 are connected by bolts. The retaining ring 11 of the bearing inner ring and the lower annular connecting piece 12 are connected by evenly distributed bolts. A shaft shoulder for positioning the inner ring of the bearing is provided on the retaining ring 11 of the inner ring of the bearing to ensure that the bearing cannot move upwards under the axial force. A circlip 20 mounting groove is designed on the lower part of the bearing inner ring retaining ring 11 for installing the circlip 20, which ensures that the grinding head part will not fall due to gravity in a non-working state. There are 4 screw holes on the abrasive material mounting disc 18 for installing abrasive materials 19. The structure described in this part is the structure of the grinding head part.

The grinding system has three important parameters, namely grinding force, cutting speed, and feed speed, among which the feed speed is provided by the robot. Abrasive force is provided by the linear motion described in this patent, and rotational cutting speed is provided by the rotary motion described in this patent. In terms of function realization, the polishing force control end effector is divided into three parts: the rotating part, the linear motion part, and the grinding head part.

The rotating part is mainly composed of an air motor 2 and a main shaft 6 . Based on the improvement of the quality of the current air motor 2, more and more electromechanical systems no longer use the transmission system. This not only increases the compactness and stability of the system, but also reduces the mass of the system. The linear motion part is mainly composed of a linear motor, a motor sleeve and a ring connector, and a pull-torque composite sensor is installed between the linear motion part and the rotating part. Below the rotating part is the grinding head part, which is mainly composed of abrasive material 19, abrasive mounting plate 18, inner and outer retaining rings of the bearing and bearings. The motion of the rotating part and the linear part will be transmitted to the grinding head, so there is a coupling problem in the grinding head part. The decoupling part adopts the ball spline 16 to connect the rotating part and the grinding head, the linear motion part and the grinding head respectively.

In this design, the air motor 2 is used as the power, which greatly reduces the total mass of the actuator. The air motor 2 is connected to the main shaft 6 through the key 7, and the main shaft 6 and the air motor 2 are connected in one piece, which avoids the use of a coupling and reduces the complexity of the mechanism, making the structure more compact. The bearing assembly 5 is used in this design, which simplifies the design of the 6-axis section of the main shaft and reduces the uncertainty introduced by the positioning of the inner and outer rings of the bearing. The force detection sensor of the polishing system is a two-dimensional tension-torsion composite sensor. The sensor is installed on the lower surface of the L-shaped connector and can directly measure the normal force of the polishing operation. Compared with the six-dimensional force sensor, the two-dimensional tension-torsion composite force sensor 1 greatly reduces the design cost. In order to smoothly connect the linear motor stator 9 and the inner ring of the tension-torsion composite force sensor 1 , a transitional part—an upper annular connecting piece 13 is designed here. Among the many ways to achieve linear motion, this design chooses the linear motor, because the linear motor has superior force control performance and fast response bandwidth, which are exactly what the polishing operation and polishing research needs. The rotary motion of the air motor 2 is transmitted to the ball spline 16 through the main shaft 6, and the ball spline 16 transmits the rotary motion to the grinding head part, which realizes the cutting rotary motion of polishing. The inner ring of the linear motor transmits the linear motion to the grinding head through the inner ring of the bearing, which realizes the control of the normal polishing force. Since the ball spline 16 has the function of transmitting torque without "tight" connection, the grinding head can slide freely along the shaft, which makes the two degrees of freedom of the grinding head mechanically decoupled at the ball spline 16. In this design, a pair of angular contact ball bearings 14 are installed face to face, and the grinding head can bear bidirectional axial force. The inner and outer rings of the bearing have bearing inner and outer retaining rings, retaining rings 17 and spring collars for axial positioning respectively. Abrasives 19 for polishing the end effector can be ordered uniformly, and a series of abrasive mounting discs 18 can be designed in this design to install abrasives 19 of different types and materials according to requirements. In addition, in the current general design, the connection between the actuator and the macro robot system is at the top of the actuator, which greatly increases the overturning moment of the polishing surface and affects the quality of polishing. In comparison, in this design, the connection point of polishing is lower, which is more conducive to ensuring the quality of the polishing surface.

Example 3:

The polishing force control end effector can be installed on the end joint of the robot through the L-shaped connecting plate 4, and the actuator and the robot together constitute a macro-micro robot polishing system. The robot provides the feed movement during the polishing process, and the actuator provides the polishing speed and polishing tool force.

Turn on the switch of the air pump to provide the air source to the air motor 2, and the shaft of the air motor 2 rotates. The main shaft 6 and the air motor 2 are connected by the key 7, the speed and torque of the air motor 2 are transmitted to the main shaft 6, the main shaft 6 and the ball spline 16 are used together, the main shaft 6 transmits the motion and torque to the grinding head connected with the ball spline 16, and the rotation of the abrasive 19 provides the cutting speed of polishing.

The lower surface of the L-shaped connecting plate 4 is equipped with a tension-torsion compound sensor 1 through bolts, which can detect the polishing force during the polishing process in real time. The pull-twist composite sensor 1 is connected to the linear motor stator 9 through the upper ring connector 13 and the motor mounting sleeve 10 . The linear motor mover 8 is partially connected to the polishing head, the position control mode of the mover can realize pose compensation, and the torque mode of the mover can realize the force adjustment of the polishing tool.

In this case, the polishing head can realize the adjustment of the cutting rotation speed by adjusting the air volume of the air motor 2, and can realize the position compensation of the polishing and the constant force of the adjustment tool by adjusting the linear motor.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods, and are all included within the protection scope of the present invention.

Claims (6)

1. A robot polishing force-controlled end effector, characterized in that the end effector includes a grinding head for grinding workpieces, a rotating part that drives the grinding head to rotate, and a linear motion part that drives the grinding head to feed; the rotating part is connected to the mechanical arm, and its output end is connected to the grinding head after passing through the linear motion part; The rotating part includes an air motor, a motor bracket, an L-shaped connector, a main shaft, a key, and a bearing assembly; one side of the L-shaped connector is fixedly connected to the grinding mechanical arm, and the air motor is fixedly mounted on the other side of the L-shaped connector through the motor bracket; one end of the main shaft is connected to the output end of the air motor through the key, and the other end is connected to the grinding head; the bearing assembly is installed on the L-shaped connector, and its inner ring is in interference fit with the main shaft; The linear motion part includes a tension-torsion compound force sensor, an upper annular connector, a motor mounting sleeve, a linear motor stator, a linear motor mover, a lower annular connector, a bearing inner ring retaining ring, an angular contact ball bearing, and a circlip; the tension-torsion compound force sensor is arranged below the air motor, and is fixedly connected to the L-shaped connector through bolts; the tension-torsion compound force sensor is fixedly connected to the linear motor stator through the upper annular connector and the motor mounting sleeve; the linear motor mover is arranged in the linear motor stator, and its lower end is fixedly connected to the lower annular connector; The upper end of the retaining ring of the bearing inner ring is fixed to the lower annular connector by bolts, and its lower end is fixedly connected to the circlip; the angular contact ball bearing is arranged outside the retaining ring of the inner ring of the bearing, between the top of the retaining ring of the bearing inner ring and the retaining ring; The grinding head includes a retaining ring, a bearing outer retaining ring, a ball spline, an abrasive mounting plate, and abrasives; the upper end of the bearing outer retaining ring is connected to the retaining ring by bolts, and its inner wall is in contact with the angular contact ball bearing; the ball spline is arranged in the bearing outer retaining ring, and its bottom is fixedly connected to the bearing outer retaining ring and the abrasive mounting plate through bolts, and its inner wall is connected to the main shaft to realize the spindle driving the ball spline to rotate and the ball spline can slide axially on the main shaft; on the installation disk. 2 . The robot polishing force control end effector according to claim 1 , wherein the angular contact ball bearings are set as a pair and installed in a face-to-face manner. 3 . 3. The robot polishing force control end effector according to claim 1, characterized in that, the upper surface of the L-shaped connector is provided with a profile, and the bearing assembly is positioned on the profile of the L-shaped connector through the profile. 4. The robot polishing force control end effector according to claim 1, characterized in that, the lower annular connector is provided with a circular truncated surface for ensuring the neutrality of the linear motor installation, and the linear motor mover is installed on the lower circular connector The circular truncated surface. 5. The robot polishing force control end effector according to claim 1, characterized in that, the outer ring of the bearing is provided with a stepped torus for positioning the angular contact ball bearing, the outer wall of the stepped torus is arranged on the inner wall of the outer ring of the bearing, and its inner wall is in contact with the angular contact ball bearing. 6 . The robot polishing force control end effector according to claim 1 , characterized in that, the upper part of the retaining ring of the inner ring of the bearing is provided with a shoulder for positioning the retaining ring of the inner ring of the bearing. 7 .