A lead screw assembly and a multi-joint robot

Abstract

This invention provides a lead screw assembly and a multi-joint robot. The lead screw assembly includes: a lead screw, a first transmission wheel, a second transmission wheel, a first friction plate, a second friction plate, a first sleeve, a second sleeve, and a spring device. The first sleeve is threadedly connected to the lead screw, and the second sleeve is keyed to the lead screw. The spring device can release spring force to engage the first and second friction plates. The first and second friction plates, the first and second transmission wheels, the first and second sleeves, and the lead screw are connected as a single unit, allowing the first and second sleeves and the lead screw to rotate synchronously to limit the axial movement of the lead screw. This invention avoids the lead screw impacting the second robotic arm due to downward movement under gravity when the robot stops, while also reducing the structural complexity of the robot and lowering costs. Furthermore, this invention significantly reduces braking torque, improves braking effect, and greatly reduces power consumption.

Description

Technical Field

[0001] This invention relates to the field of industrial robot technology, specifically to a lead screw assembly and a multi-joint robot. Background Technology

[0002] In existing technologies, when a robot stops, the ball screw shaft of a SCARA robot will rotate and move downwards under the influence of gravity due to the load, causing impact damage to the robot. Therefore, existing SCARA (horizontal multi-joint) industrial robots are usually equipped with brakes on the third joint and / or the fourth joint.

[0003] In some cases, a solution using a third or fourth motor with built-in brakes is employed. However, if the brakes malfunction, the entire motor needs to be replaced, increasing maintenance costs.

[0004] In some cases, external brakes are used. External brakes complicate the robot's structure and increase costs to some extent.

[0005] Because existing horizontal multi-joint robots require brakes to prevent the ball screw from damaging the robot due to gravity, but this leads to technical problems such as structural complexity and increased cost, this invention researches and designs a ball screw assembly and a multi-joint robot. Summary of the Invention

[0006] Therefore, the technical problem to be solved by the present invention is to overcome the shortcomings of the prior art in horizontal multi-joint robots, which require brakes to prevent the ball screw from damaging the robot due to gravity. However, setting brakes leads to structural complexity and increased cost. Therefore, the present invention provides a ball screw assembly and a multi-joint robot.

[0007] To address the above problems, the present invention provides a lead screw assembly, comprising:

[0008] The device comprises a lead screw, a first drive wheel, a second drive wheel, a first friction plate, a second friction plate, a first sleeve, a second sleeve, and a spring device. The first drive wheel can simultaneously drive the first sleeve and the first friction plate to rotate, and the second drive wheel can simultaneously drive the second sleeve and the second friction plate to rotate. The first friction plate and the second friction plate are arranged opposite to each other. The lead screw passes through the first sleeve and the second sleeve. The first sleeve is threadedly connected to the lead screw, and the second sleeve is keyedly connected to the lead screw.

[0009] The elastic device can release elastic force to make the first friction plate and the second friction plate come into contact. The first friction plate, the second friction plate, the first transmission wheel, the second transmission wheel, the first sleeve, the second sleeve and the lead screw are connected as a whole, so that the first sleeve, the second sleeve and the lead screw can rotate synchronously to limit the axial movement of the lead screw.

[0010] In some embodiments, the first sleeve is the inner ring of a lead screw nut, and the lead screw assembly further includes an outer ring of a lead screw nut. The outer ring of the lead screw nut is sleeved on the outer circumference of the inner ring of the lead screw nut. The inner ring of the lead screw nut rotates relative to the outer ring of the lead screw nut. The outer ring of the lead screw nut also limits the axial movement of the inner ring of the lead screw nut. The inner ring of the lead screw nut and the outer ring of the lead screw nut together form a lead screw nut.

[0011] In some embodiments, the inner circumferential wall of the lead screw nut inner ring is provided with an internal thread, and the outer circumferential wall of the lead screw is provided with an external thread. The internal thread and the external thread are matched and connected, so that the lead screw nut inner ring and the lead screw form a matching helical pair. When the lead screw nut inner ring is driven to rotate alone, it drives the lead screw to move axially relative to the lead screw nut inner ring while also rotating.

[0012] In some embodiments, the second sleeve is the inner ring of a spline nut, and the lead screw assembly also includes an outer ring of a spline nut. The outer ring of the spline nut is sleeved on the outer circumference of the inner ring of the spline nut. The inner ring of the spline nut rotates relative to the outer ring of the spline nut. The outer ring of the spline nut also limits the axial movement of the inner ring of the spline nut. The inner ring of the spline nut and the outer ring of the spline nut together form a spline nut.

[0013] In some embodiments, a spline groove is provided on the inner peripheral wall of the inner ring of the spline nut, and a spline is provided on the outer peripheral wall of the lead screw. The spline and the spline groove are matched and connected, forming a rotating pair between the inner ring of the spline nut and the lead screw. When the inner ring of the spline nut is driven to rotate independently, it drives the lead screw to rotate together with the inner ring of the spline nut. The lead screw can move axially relative to the inner ring of the spline nut. In some embodiments, the elastic device includes a magnetic structure and an elastic structure. One end of the elastic structure is connected to the first friction plate or the second friction plate to provide an elastic thrust so that the first friction plate and the second friction plate are in contact. The magnetic structure is disposed on the side of the second friction plate away from the first friction plate to provide a magnetic attraction force to the second friction plate, or disposed on the side of the first friction plate away from the second friction plate to provide a magnetic attraction force to the first friction plate, so as to overcome the elastic force of the elastic structure and separate the second friction plate from the first friction plate.

[0014] In some embodiments, the magnetic structure is an electromagnetic structure. When braking is required, the magnetic structure is de-energized, and the elastic structure pushes the second friction plate to adhere to the first friction plate, causing the first and second friction plates to rotate as a whole, thereby driving the lead screw, the first sleeve structure, and the second sleeve structure to rotate as a whole. When braking is not required, the magnetic structure is energized, and the magnetic attraction generated by the magnetic structure overcomes the elastic force of the elastic structure, separating the first and second friction plates. The rotation of the first transmission wheel and the rotation of the second transmission wheel are controlled to control the axial movement and / or rotation of the lead screw.

[0015] In some embodiments, one end of the first transmission wheel is connected to the first sleeve and the other end is connected to the first friction plate. One end of the second transmission wheel is connected to the second sleeve and the other end is spaced apart from the second friction plate. The second friction plate is sleeved on the lead screw and can be in no contact with the lead screw. The second friction plate and the second transmission wheel rotate together. The second transmission wheel drives the second sleeve to rotate by rotating, thereby driving the lead screw to rotate.

[0016] In some embodiments, when the lead screw assembly further includes a splined nut outer ring:

[0017] The elastic structure is disposed in the space between the second transmission wheel and the second friction plate, with one end of the elastic structure connected to the second transmission wheel and the other end connected to the second friction plate; the magnetic structure is disposed between the second transmission wheel and the outer ring of the spline nut, the magnetic structure provides magnetic attraction to the second friction plate, and the elastic structure provides elastic thrust to the second friction plate.

[0018] In some embodiments, when the second sleeve is the inner ring of a spline nut: the electromagnetic structure is installed on the side of the outer ring of the spline nut facing the second transmission wheel, the electromagnetic structure is fixed and does not rotate, and the inner ring of the spline nut, the second transmission wheel, the second friction plate, and the elastic structure do not contact the electromagnetic structure.

[0019] In some embodiments, the electromagnetic structure includes an electromagnet and an electrode plate. The electromagnet is mounted on the side of the second transmission wheel facing the outer ring of the spline nut, so that the electromagnet rotates integrally with the second transmission wheel. The electrode plate is disposed on the side of the outer ring of the spline nut facing the second transmission wheel. An electrode is also disposed on the side of the electromagnet facing the electrode plate. An annular electrode region is disposed on the side of the electrode plate facing the electromagnet. The annular electrode region is opposite to the moving position of the electrode, so that the electrode is always in contact with the electrode region during rotation.

[0020] In some embodiments, a groove is provided on the side of the electromagnet facing the electrode plate, a portion of the electrode structure is located in the groove, the portion of the electrode structure extends out of the groove and one end of the electrode contacts the electrode region, and an elastic thrust structure is provided between the other end of the electrode and the bottom of the groove, the elastic thrust structure applying an elastic thrust to the electrode.

[0021] The present invention also provides a multi-joint robot comprising the lead screw assembly described in the preceding claim.

[0022] In some embodiments, when the lead screw assembly further includes a lead screw nut outer ring and a spline nut outer ring: the multi-joint robot further includes a first robotic arm and a second robotic arm, one end of the first robotic arm forms a first rotation axis, i.e., axis J1, and the first robotic arm can rotate around axis J1. The other end of the first robotic arm is rotatably connected to one end of the second robotic arm to form a second rotation axis, i.e., axis J2, and the second robotic arm can rotate around axis J2. The other end of the second robotic arm is provided with the lead screw, the first transmission wheel, the second transmission wheel, the first friction plate and the second friction plate, the first sleeve and the second sleeve; the lead screw nut outer ring is fixedly connected to the second robotic arm, and the spline nut outer ring is fixedly connected to the second robotic arm.

[0023] In some embodiments, the second robotic arm is further equipped with a third motor and a fourth motor. The third motor can drive the first transmission wheel to rotate, and the fourth motor can drive the second transmission wheel to rotate. The first transmission wheel is a lead screw nut pulley, and the second transmission wheel is a spline nut pulley. By simultaneously driving the first transmission wheel and the second transmission wheel to rotate, the lead screw can be driven to perform axial movement and / or rotation.

[0024] The lead screw assembly and multi-joint robot provided by this invention have the following beneficial effects:

[0025] This invention, by setting up a first friction plate, a second friction plate, and a spring device, allows the first transmission wheel to simultaneously drive the first sleeve and the first friction plate to rotate, and the second transmission wheel to simultaneously drive the second sleeve and the second friction plate to rotate. When braking is required, the spring device is controlled to bring the first and second friction plates into contact, enabling the first and second friction plates, the first and second transmission wheels, and the second transmission wheel to rotate as a whole. This, in turn, connects the first and second sleeves and the lead screw into a single unit, allowing them to rotate synchronously. Because the second sleeve and the lead screw are connected by a key, and the first sleeve and the lead screw are connected by a thread, and can rotate synchronously, the rotating pair between the first sleeve and the lead screw is constrained, and the two are relatively fixed. This effectively restricts the axial movement of the lead screw, allowing it only to rotate (or tend to rotate), and preventing it from moving up and down in the axial direction. The invention effectively avoids the situation where the lead screw, due to gravity, moves downwards and collidees with the second robotic arm when the robot stops. Furthermore, the invention, through the use of two friction plates and an elastic device, effectively replaces the existing braking structures located at the third and fourth motors, as well as the external brake structure, thus significantly reducing the robot's structural complexity and cost. Moreover, the invention effectively controls the synchronous rotation of the lead screw, multiple friction plates, multiple transmission wheels, and multiple sleeves. By achieving synchronous rotation, effective braking can be achieved by overcoming the frictional resistance between the two friction plates and the first and second sleeves, respectively. This allows for effective braking even under heavy loads with low power consumption, effectively avoiding excessive braking torque caused by the force required to overcome rotation. The braking torque of the invention is greatly reduced, the braking effect is significantly improved, and power consumption is greatly reduced. Attached Figure Description

[0026] Figure 1 This is a front structural view of the multi-joint robot (SCARA robot) of the present invention;

[0027] Figure 2 yes Figure 1 AA section view (schematic diagram of the lead screw assembly);

[0028] Figure 3 This is a preferred structural diagram of the braking portion of the lead screw assembly of the present invention;

[0029] Figure 4 This is a structural diagram of an alternative embodiment of the braking portion of the lead screw assembly of the present invention;

[0030] Figure 5 yes Figure 4 A magnified view of part B in the diagram.

[0031] The reference numerals in the attached figures are as follows:

[0032] 1. Base; 2. First motor; 3. First reducer; 4. First robotic arm; 5. Second reducer; 6. Second motor; 7. Second robotic arm; 8. Third motor; 9. Fourth motor; 10. Lead screw; 11. Lead screw nut; 111. Inner ring of lead screw nut; 112. Outer ring of lead screw nut; 12. Spline nut; 121. Inner ring of spline nut; 122. Outer ring of spline nut; 13. First transmission wheel; 14. Second transmission wheel; 15. First friction plate; 16. Second friction plate; 17. Elastic device; 171. Magnetic structure; 172. Elastic structure; 1711. Electrode; 1712. Elastic thrust structure; 18. Electrode plate; 181. Electrode area. Detailed Implementation

[0033] In the description of this invention, it should be noted that the terms "inner" and "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "contact," and "communication" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] like Figure 1-5 As shown, Part One: Working Principle of the SCARA Robot of the Present Invention

[0036] like Figure 1-2 As shown, the SCARA robot is characterized by a base 1, a first motor 2, a first reducer 3, a first robotic arm 4, a second reducer 5, a second motor 6, a second robotic arm 7, a third motor 8, a fourth motor 9, a lead screw 10, a lead screw nut 11, and a spline nut 12.

[0037] like Figure 1-2 As shown, the first motor 2 is fixed on the base 1; the motor output shaft is connected to the first reducer 3; the input end of the second reducer 5 is connected to the output shaft of the second motor 6, and the output end is connected to the first robotic arm 4; one end of the first robotic arm 4 is connected to the output end of the first reducer 3. Under the deceleration action of the first reducer 3, the first motor 2 drives the first robotic arm 4 and the components mounted on it to rotate around the J1 axis.

[0038] like Figure 1-2As shown, the second motor 6 is mounted on the second robotic arm 7. The input end of the second reducer 5 is connected to the output shaft of the second motor 6, and the output end is connected to the first robotic arm 4. Under the deceleration action of the second reducer 5, the second motor 6 drives the second robotic arm 7 and the components mounted on it to rotate around the J2 axis.

[0039] like Figure 1-2 As shown, the third motor 8 is mounted on the second robotic arm 7. The third motor 8 drives the inner ring 111 of the lead screw nut. The inner ring 111 of the lead screw nut is assembled with the lead screw 10 and controls the lead screw 10 to reciprocate linearly along the J3 axis. (The reciprocating motion of the lead screw is achieved by rotating the inner ring 111 of the lead screw nut to fix the inner ring 121 of the spline nut, along the J3 axis, and rotation).

[0040] like Figure 1-2 As shown, the fourth motor 9 is mounted on the second robotic arm 7. The fourth motor 9 drives the inner ring 121 of the spline nut to rotate. The inner ring 121 of the spline nut is assembled with the lead screw 10. With the cooperation of the lead screw nut 11 (the inner ring 111 of the lead screw nut rotates synchronously with the lead screw), the lead screw 10 can be controlled to rotate around the J4 axis.

[0041] The lead screw assembly of the multi-joint robot (preferably a horizontal multi-joint robot, i.e., a SCARA industrial robot) of the present invention includes:

[0042] The device comprises a lead screw 10, a first transmission wheel 13, a second transmission wheel 14, a first friction plate 15, a second friction plate 16, a first sleeve, a second sleeve, and a spring device 17. The first transmission wheel 13 can simultaneously drive the first sleeve and the first friction plate 15 to rotate, and the second transmission wheel 14 can simultaneously drive the second sleeve and the second friction plate 16 to rotate. The first friction plate 15 and the second friction plate 16 are arranged opposite to each other. The lead screw 10 passes through both the first sleeve and the second sleeve (indicating a state). The first sleeve is threadedly connected to the lead screw 10, and the second sleeve is keyed to the lead screw 10.

[0043] The elastic device 17 can release elastic force to make the first friction plate 15 and the second friction plate 16 connect. The first friction plate 15, the second friction plate 16, the first transmission wheel 13, the second transmission wheel 14, the first sleeve, the second sleeve and the lead screw are connected as a whole, so that the first sleeve, the second sleeve and the lead screw 10 can rotate synchronously to limit the axial movement of the lead screw 10.

[0044] This invention, by setting up a first friction plate, a second friction plate, and a spring device, allows the first transmission wheel to simultaneously drive the first sleeve and the first friction plate to rotate, and the second transmission wheel to simultaneously drive the second sleeve and the second friction plate to rotate. When braking is required, the spring device is controlled to bring the first and second friction plates into contact, enabling the first and second friction plates, the first and second transmission wheels, and the second transmission wheel to rotate as a whole. This, in turn, connects the first and second sleeves and the lead screw into a single unit, allowing them to rotate synchronously. Because the second sleeve and the lead screw are connected by a key, and the first sleeve and the lead screw are connected by a thread, and can rotate synchronously, the rotating pair between the first sleeve and the lead screw is constrained, and the two are relatively fixed. This effectively restricts the axial movement of the lead screw, allowing it only to rotate (or tend to rotate), and preventing it from moving up and down in the axial direction. The invention effectively avoids the situation where the lead screw, due to gravity, moves downwards and collidees with the second robotic arm when the robot stops. Furthermore, the invention, through the use of two friction plates and an elastic device, effectively replaces the existing braking structures located at the third and fourth motors, as well as the external brake structure, thus significantly reducing the robot's structural complexity and cost. Moreover, the invention effectively controls the synchronous rotation of the lead screw, multiple friction plates, multiple transmission wheels, and multiple sleeves. By achieving synchronous rotation, effective braking can be achieved by overcoming the frictional resistance between the two friction plates and the first and second sleeves, respectively. This allows for effective braking even under heavy loads with low power consumption, effectively avoiding excessive braking torque caused by the force required to overcome rotation. The braking torque of the invention is greatly reduced, the braking effect is significantly improved, and power consumption is greatly reduced.

[0045] The braking mechanism of this invention refers to the fact that both the third and fourth motors are stopped, the two transmission wheels do not rotate, and the first friction plate, the second friction plate, the first and second sleeves, and the lead screw are all relatively stationary. The aforementioned components can rotate as a whole or have a tendency to rotate as a whole under the drive of a load, thereby limiting the axial displacement of the lead screw.

[0046] For example, when a load is applied to the lower end of the lead screw, the load tends to cause the lead screw to move downwards. This causes axial displacement of the lead screw and the inner ring of the lead screw nut. Since they are a helical pair, the lead screw causes the inner ring of the lead screw nut to rotate clockwise or counterclockwise. Furthermore, the inner ring of the lead screw nut causes the inner ring of the spline nut to rotate clockwise or counterclockwise, and so on. This results in synchronous rotation (trend) between the lead screw and the inner ring of the lead screw nut, constraining the rotational pair between them and preventing axial displacement of the lead screw. This effectively limits the axial displacement of the lead screw.

[0047] The invention proposes a SCARA robot, which includes: a first brake pad (i.e., a first friction pad), a second brake pad (i.e., a second friction pad), an elastic device, a ball screw, a spline nut, a screw nut, a spline nut pulley, and a screw nut pulley.

[0048] The first friction plate is fixed on the lead screw nut pulley, and the second friction plate is installed on the spline nut pulley. There is an elastic device on the second brake plate. When braking is required, the first and second friction plates come into contact under the action of the elastic device to achieve braking. When braking is not required, the first and second friction plates separate under the action of the elastic device.

[0049] When the first friction plate comes into contact with the second friction plate, the spline nut pulley and the lead screw nut pulley will move synchronously, causing the lead screw to only rotate and not move up and down, resulting in a collision.

[0050] The following technical problems are solved: Compared with the existing J3-axis and J4-axis braking structures, this method avoids the situation where the lead screw moves downward due to gravity and hits the second robotic arm when the machine stops, while also reducing the use of brakes and lowering the cost of SCARA robots.

[0051] Beneficial effects: (1) It achieves the purpose of setting brakes in the third and fourth joints, preventing the lead screw from moving downwards due to gravity when the machine is stopped, thus preventing a collision. It also reduces the use of brakes and lowers the complexity of the robot; (2) The braking torque is small (using the form of built-in or external brakes in the motor, the braking torque increases with the increase of load, and the brake volume also increases).

[0052] Part Two: Working Principles of the SCARA Robot's J3 and J4 Axes

[0053] In general, the J3 and J4 axes of a SCARA robot are driven by the third motor 8 and the fourth motor 9, respectively, to drive the inner ring 111 of the lead screw nut and the inner ring 121 of the spline nut, so that the lead screw 10 moves up and down and rotates.

[0054] like Figure 1-2 As shown, the lead screw nut 11 consists of an inner ring 111 and an outer ring 112, with only one revolute joint between them. The outer ring 112 is fixed to the lead screw nut mounting plate, and then together they are fixed to the second robotic arm 7. The lead screw 10 and the inner ring 111 are connected by a helical joint. The inner ring 111 is fixed to the lead screw nut pulley (first transmission wheel 13), and the third motor 8 drives the pulley to control the motion of the inner ring 111.

[0055] like Figure 1-2As shown, the spline nut 12 consists of an inner spline nut ring 121 and an outer spline nut ring 122, with only one revolute joint between them. The outer spline nut ring 122 is fixed to the second robotic arm 7. The lead screw 10 and the inner spline nut ring 121 are splined, allowing axial movement but not rotational movement. The inner spline nut ring 121 is fixed to the spline nut pulley (second transmission wheel 14), and the fourth motor 9 drives the spline nut pulley to achieve motion control of the inner spline nut ring 121.

[0056] J3 axis movement: The rotational movement of the lead screw 10 is restricted (because the lead screw 10 and the inner ring 121 of the spline nut are splined, the rotation of the lead screw 10 is restricted, that is, the rotational movement of the inner ring 121 of the spline nut and the spline nut pulley (second transmission wheel 14) is restricted). Rotating the inner ring 111 of the lead screw nut will cause the inner ring 111 of the lead screw 10 to rotate and move axially at the same time (because the lead screw 10 and the inner ring 111 of the lead screw nut are helically coupled). However, since the axial movement of the inner ring 111 of the lead screw nut is restricted (reason: the outer ring 112 of the lead screw nut is fixed to the second robotic arm 7, and there is only a rotating pair between it and the inner ring 111 of the lead screw nut), the axial movement of the inner ring 111 of the lead screw nut on the lead screw 10 is transformed into the axial movement of the lead screw 10 on the inner ring 111 of the lead screw nut.

[0057] J4 axis movement: When the lead screw 10 and the inner ring 111 of the lead screw nut rotate synchronously (i.e., the inner ring 121 of the spline nut + the spline nut pulley (second transmission wheel 14) drives the lead screw 10, and as the inner ring of the lead screw nut + the lead screw nut pulley rotate synchronously), the relative position between the lead screw 10 and the inner ring 111 of the lead screw nut will not change. The lead screw 10 and the inner ring 111 of the lead screw nut, relative to the outer ring of the lead screw nut, only have rotational motion. Therefore, the lead screw 10 only has rotational motion relative to the second robotic arm 7, i.e., the J4 axis.

[0058] By properly controlling the movement of the J3 and J4 axes together, the lead screw can be made to rotate and move up and down simultaneously.

[0059] Part Three: This Invention – SCARA Robot Braking Structure

[0060] For the J3 and J4 axes of the SCARA robot, braking devices need to be installed to ensure that when the robot is stopped, the lead screw 10 will rotate downwards under gravity, causing the J3 and J4 axes to exceed the soft limit or the lead screw to be impacted.

[0061] In general SCARA robots, braking of the J3 and J4 axes employs two methods. One method involves installing a braking device on the motor shaft, sometimes internally and sometimes externally. The other method involves incorporating braking devices in the transmission links between the third motor 8 and the lead screw nut 11, and between the fourth motor 9 and the spline nut 12. Some SCARA robots only have brakes on the third joint. Both methods utilize motor braking to achieve collision avoidance.

[0062] This invention proposes a SCARA robot braking system, which differs from the aforementioned ones.

[0063] Preferred embodiments of the present invention:

[0064] like Figure 1-2 As shown, the present invention proposes a SCARA robot braking system, characterized by: a first brake pad (first friction pad 15), a second brake pad (second friction pad 16), an elastic device 17, a ball screw (screw 10), a spline nut 12, a screw nut 11, a spline nut pulley (second transmission wheel 14), and a screw nut pulley (first transmission wheel 13).

[0065] The first friction plate 15 is fixed on the first transmission wheel 13, the second friction plate 16 is mounted on the second transmission wheel 14, and an elastic device 17 is present on the second friction plate.

[0066] During braking, under the action of the elastic device 17, the first friction plate 15 and the second friction plate 16 come into contact. The frictional force of the two brake plates causes the first brake plate + lead screw nut pulley + lead screw nut inner ring 111 and the second brake plate + spline nut pulley + spline nut inner ring 121 to move synchronously. According to the characteristics of the ball screw, when the lead screw nut inner ring 111 and the spline nut inner ring 121 rotate synchronously, the lead screw 10 only rotates and cannot move up and down, avoiding the possibility of the lead screw colliding with the machine. This replaces the existing external brake solution (i.e., setting the brake at the motor), achieving a simpler structure, reduced cost, and prevention of lead screw impact.

[0067] When braking is not required, the first friction plate 15 and the second friction plate 16 separate under the action of the elastic device 17.

[0068] The mounting or fixing positions of the first friction plate 15 and the second friction plate 16 on the first transmission wheel 13 and the second transmission wheel 14 can be interchanged, and the elastic device can also be changed accordingly.

[0069] In some embodiments, the first sleeve is the inner ring 111 of the lead screw nut, and the lead screw assembly also includes an outer ring 112 of the lead screw nut. The outer ring 112 of the lead screw nut is sleeved on the outer periphery of the inner ring 111 of the lead screw nut (the outer ring of the lead screw nut is fixed to the second robotic arm 7). The inner ring 111 of the lead screw nut rotates relative to the outer ring 112 of the lead screw nut. The outer ring 112 of the lead screw nut also limits the axial movement of the inner ring 111 of the lead screw nut. The inner ring 111 of the lead screw nut and the outer ring 112 of the lead screw nut constitute the lead screw nut 11. This is the preferred structural form of the first sleeve of the present invention and the corresponding related structures. That is, the lead screw nut is effectively composed of an inner ring and an outer ring of the lead screw nut. The outer ring of the lead screw nut is used to fix the second mechanical arm to support the inner ring of the lead screw nut. The inner ring of the lead screw nut can rotate relative to the outer ring of the lead screw nut, that is, the inner ring of the lead screw nut is driven to rotate by the first transmission wheel. The connection structure between the inner ring of the lead screw nut and the lead screw is a helical pair, that is, a threaded connection. And because the outer ring of the lead screw nut axially limits the inner ring of the lead screw nut, when the inner ring of the lead screw nut rotates, the lead screw is driven to both rotate and move axially (the inner ring of the lead screw nut is axially fixed) through the helical pair, thereby realizing the effective driving of the axial movement and rotation of the lead screw.

[0070] In some embodiments, the inner circumferential wall of the lead screw nut inner ring 111 is provided with an internal thread, and the outer circumferential wall of the lead screw 10, at a position opposite to the lead screw nut inner ring 111, is provided with an external thread. The internal thread and the external thread are matched and engaged, so that the lead screw 10 and the lead screw nut inner ring 111 form a fitting helical pair. When the lead screw nut inner ring 111 is driven to rotate alone, it drives the lead screw 10 to move axially relative to the lead screw nut inner ring 111 while also rotating. This is the preferred structural form of the threaded connection between the lead screw nut inner ring and the lead screw of the present invention. That is, the inner wall of the lead screw nut inner ring is provided with an internal thread, and the corresponding position on the lead screw is provided with an external thread, so that the internal and external threads are matched and engaged. Thus, the rotation of the lead screw nut inner ring can drive the lead screw to rotate while also moving up and down axially.

[0071] In some embodiments, the second sleeve is a spline nut inner ring 121, and the lead screw assembly further includes a spline nut outer ring 122. The spline nut outer ring 122 is sleeved on the outer periphery of the spline nut inner ring 121. The spline nut inner ring 121 rotates relative to the spline nut outer ring 122. The spline nut outer ring 122 also limits the axial movement of the spline nut inner ring 121. The spline nut inner ring 121 and the spline nut outer ring 122 constitute a spline nut 12. This is a preferred structural form of the second sleeve of the present invention and corresponding related structures. Specifically, the spline nut is effectively formed by the structure of the inner ring and the outer ring of the spline nut. The outer ring of the spline nut is used to fix with the second robotic arm to support the inner ring of the spline nut. The inner ring of the spline nut can rotate relative to the outer ring of the spline nut, that is, the inner ring of the spline nut is driven to rotate by the second transmission wheel. The connection structure between the inner ring of the spline nut and the lead screw is a revolute joint, that is, a spline connection. Furthermore, since the outer ring of the spline nut axially limits the inner ring of the spline nut, when the inner ring of the outer ring of the spline nut rotates, the lead screw is driven to rotate only through the revolute joint (the inner ring of the spline nut is axially fixed), thereby achieving effective driving of the rotation of the lead screw.

[0072] In some embodiments, a spline groove is provided on the inner peripheral wall of the spline nut inner ring 121, and a spline is provided on the outer peripheral wall of the lead screw 10 at a position opposite to the spline nut inner ring 121. The spline and the spline groove are matched and connected, so that the spline nut inner ring 121 and the lead screw 10 form a rotating pair. When the spline nut inner ring 121 is driven to rotate alone, it drives the lead screw 10 to rotate together with the spline nut inner ring 121. The lead screw 10 can move axially relative to the spline nut inner ring 121. This is the preferred structural form of the spline connection between the spline nut inner ring and the lead screw of the present invention. That is, the inner wall of the spline nut inner ring is provided with a spline groove, and a spline is provided at a corresponding position on the lead screw, so that the spline and the spline groove are matched and connected. Thus, the rotation of the spline nut inner ring can drive the lead screw to only rotate, and the lead screw can move up and down axially relative to the spline nut inner ring.

[0073] In some embodiments, the elastic device 17 includes a magnetic structure 171 and an elastic structure 172. One end of the elastic structure 172 is connected to the first friction piece 15 or the second friction piece 16 to provide an elastic thrust that causes the first friction piece 15 and the second friction piece 16 to adhere to each other. The magnetic structure 171 is disposed on the side of the second friction piece 16 away from the first friction piece 15 to provide a magnetic attraction force to the second friction piece 16, or disposed on the side of the first friction piece 15 away from the second friction piece 16 to provide a magnetic attraction force to the first friction piece 15, thereby overcoming the elastic force of the elastic structure 172 to separate the second friction piece 16 from the first friction piece 15.

[0074] This is a preferred structural form of the elastic device of the present invention, namely, the elastic device includes a magnetic structure and an elastic structure. The elastic structure is used to provide elastic thrust acting on the first or second friction plate, so as to provide elastic thrust when braking is required to make the first and second friction plates fit together, thereby achieving the effect of synchronous rotation of the lead screw and the first and second sleeves, and effectively limiting the axial movement of the lead screw, i.e., axial braking; the magnetic structure can provide magnetic attraction to the first or second friction plate, so as to provide magnetic attraction when braking is not required, to effectively overcome the effect of elastic thrust and separate the first and second friction plates, so that they can operate independently, and effectively drive the lead screw to complete the required axial movement and / or rotation.

[0075] In some embodiments, the magnetic structure 171 is an electromagnetic structure. When braking is required, the magnetic structure 171 is de-energized, and the elastic structure 172 pushes the second friction plate 16 to adhere to the first friction plate 15, causing the first friction plate 15 and the second friction plate 16 to rotate as a whole, thereby driving the lead screw, the first sleeve structure, and the second sleeve structure to rotate as a whole. When braking is not required, the magnetic structure 171 is energized, and the magnetic attraction force generated by the magnetic structure 171 overcomes the elastic force of the elastic structure 172 to separate the first friction plate 15 and the second friction plate 16. The rotation of the first transmission wheel 13 and the second transmission wheel 14 are controlled to control the axial movement and / or rotation of the lead screw 10.

[0076] The magnetic structure of this invention is preferably an electromagnetic structure, which can be de-energized when braking is required. The elastic thrust of the elastic structure causes the first and second friction plates to come into contact, so that the first and second sleeves and the lead screw can rotate as a whole, effectively limiting the axial movement of the lead screw and forming axial braking. When the robot is working normally, the electromagnetic structure is energized to provide magnetic attraction to overcome the elastic thrust, effectively separating the first and second friction plates, so that the lead screw is controlled by the first and second sleeves respectively, thereby achieving the effect of axial movement and / or rotation to meet actual needs.

[0077] In some embodiments, one end of the first transmission wheel 13 is connected to the first sleeve and the other end is connected to the first friction plate 15. One end of the second transmission wheel 14 is connected to the second sleeve and the other end is spaced apart from the second friction plate 16. The second friction plate 16 is sleeved on the outer periphery of the lead screw 10 and rotates integrally with the second transmission wheel 14 (there is a gap between the second friction plate and the lead screw, and the two do not contact each other). The second transmission wheel 14 drives the second sleeve to rotate by rotating, and then drives the lead screw 10. At the same time, the rotation of the second transmission wheel drives the second friction plate 16 to rotate.

[0078] This describes the preferred positional and connection relationships between the first and second transmission wheels, the first and second sleeves, and the first and second friction plates of this invention. One end of the first transmission wheel is connected to the first sleeve, and the other end is connected to the first friction plate, enabling the first transmission wheel to simultaneously drive the first sleeve and the first friction plate to rotate. The second transmission wheel, connected to the second sleeve, drives the second sleeve to rotate. Preferably, the second friction plate is spaced apart from the second transmission wheel, and an elastic structure can be provided between them. This invention also preferably includes a guide post structure on the lower end face of the second friction plate, with the guide post fixedly connected to the second friction plate. A guide hole is provided on the second transmission wheel, and the guide post passes through the guide hole, allowing the second friction plate to be pushed by the elastic structure to move axially relative to the second transmission wheel, and simultaneously rotated by the second transmission wheel. This achieves the effect of the second friction plate and the second transmission wheel rotating as a unit.

[0079] In some embodiments, when the lead screw assembly further includes a spline nut outer ring 122:

[0080] The elastic structure 172 is disposed in the space between the second transmission wheel 14 and the second friction plate 16. One end of the elastic structure 172 is connected to the second transmission wheel 14, and the other end is connected to the second friction plate 16. The magnetic structure 171 is disposed between the second transmission wheel 14 and the outer ring 122 of the spline nut. The magnetic structure 171 provides magnetic attraction to the second friction plate 16, and the elastic structure 172 provides elastic thrust to the second friction plate 16. Preferably, the elastic structure of the present invention is disposed between the second transmission wheel and the second friction plate, enabling the second transmission wheel and the second friction plate to be connected through the elastic structure, achieving integrated rotation of the two. Furthermore, the elastic structure provides elastic thrust to push the second friction plate into contact with the first friction plate, thereby achieving synchronous rotation of the first transmission wheel, the second transmission wheel, the lead screw, the first sleeve, and the second sleeve, effectively forming a braking effect on the axial movement of the lead screw.

[0081] like Figure 3In a preferred embodiment, in some implementations, when the second sleeve is the inner ring 121 of the spline nut: the electromagnetic structure is installed on the side of the outer ring 122 of the spline nut facing the second transmission wheel 14, the electromagnetic structure is fixed and does not rotate, and the inner ring 121 of the spline nut, the second transmission wheel 14, the second friction plate 16, and the elastic structure 172 do not contact the electromagnetic structure. This is a preferred structural form of the horizontal lead screw assembly of the present invention, wherein the electromagnetic structure is disposed on the side of the outer ring of the spline nut facing the second transmission wheel. Since the outer ring of the spline nut is a fixed structure, the electromagnetic structure is also fixed. Therefore, the electromagnetic structure can provide a continuous electromagnetic attraction force on the second friction plate to control the second friction plate from sticking to the first friction plate, thereby realizing the normal operation of the horizontal lead screw assembly. When braking is required, the electromagnetic structure is de-energized, and the elastic thrust provided by the elastic structure connects the first and second friction plates together to achieve braking of the axial movement of the lead screw. The electromagnetic structure is not connected to the inner ring 121 of the spline nut, the second transmission wheel 14, the second friction plate 16, or the elastic structure 172. Since the above components all rotate during operation, the fixing effect of the electromagnetic structure can be effectively guaranteed.

[0082] Preferred embodiments of the present invention:

[0083] like Figure 2 As shown, the second friction plate 16 is mounted on the second transmission wheel 14, and the elastic device consists of a magnetic structure 171 (preferably an electromagnetic structure) and an elastic structure 172 (preferably a spring). The second friction plate 16 is subjected to an upward (towards the first friction plate 15) elastic force from the elastic structure 172. The second friction plate is made of a magnetic material such as iron.

[0084] When the J3 axis needs to be braked, the magnetic structure 171 is de-energized and loses its magnetism. The elastic structure 172 pushes the second friction plate 16 to press against the first friction plate 15. The frictional force of the two friction plates causes the first friction plate 15 + the first transmission wheel 13 + the inner ring of the lead screw nut 111 and the second friction plate 16 + the second transmission wheel 14 + the inner ring of the spline nut 121 to move synchronously. According to the characteristics of the ball screw, when the inner ring of the lead screw nut 111 and the inner ring of the spline nut 121 rotate synchronously, the lead screw 10 only rotates and cannot move up and down, so as to avoid the lead screw from colliding with the machine.

[0085] When the J3 shaft does not require braking, the magnetic structure 171 is energized, generating magnetism and creating an attractive force on the second friction plate 16. The combined force of the magnetic force and the elastic force of the spring causes the second friction plate 16 to separate from the first friction plate 15. The movements of the inner ring 111 of the lead screw nut and the inner ring 121 of the spline nut do not interfere with each other.

[0086] The magnetic structure 171 is mounted on the outer ring 122 of the spline nut, and the inner ring 121 of the spline nut, the spline nut pulley (second transmission wheel 14), the second friction plate 16, and the elastic structure 172 are not in contact with the magnetic structure 171.

[0087] like Figure 4 and 5 In alternative embodiments, in some implementations, the electromagnetic structure includes an electromagnet and an electrode plate 18. The electromagnet is mounted on the side of the second transmission wheel 14 facing the outer ring 122 of the spline nut, so that the electromagnet rotates integrally with the second transmission wheel 14. The electrode plate 18 is disposed on the side of the outer ring 122 of the spline nut facing the second transmission wheel 14. An electrode 1711 is also disposed on the side of the electromagnet facing the electrode plate 18. An annular electrode region 181 is disposed on the side of the electrode plate 18 facing the electromagnet. The annular electrode region 181 and the electrode 1711 are positioned opposite each other, so that the electrode 1711 is always in contact with the electrode region 181 during rotation.

[0088] This is a preferred structure of an alternative embodiment of the horizontal lead screw assembly of the present invention. The electromagnet of the electromagnetic structure is disposed on the side of the second transmission wheel facing the outer ring of the spline nut, and the electrode plate is disposed on the side of the outer ring of the spline nut facing the second transmission wheel. The electrode area on the electrode plate is set as an annular area, which can ensure that the electrode disposed on the electromagnet is always in contact with the electrode area on the electrode plate, thus ensuring that the electromagnet is always energized and effectively avoiding the pulling or tangling of the cable.

[0089] In some embodiments, a groove is provided on the side of the electromagnet facing the electrode plate 18, a portion of the structure of the electrode 1711 is located in the groove, a portion of the structure of the electrode 1711 extends out of the groove and one end of the electrode 1711 contacts the electrode region 181, and an elastic thrust structure 1712 is provided between the other end of the electrode 1711 and the bottom of the groove, the elastic thrust structure 1712 applying an elastic thrust to the electrode 1711.

[0090] In an alternative embodiment of the present invention, by providing a groove on the electromagnet, an electrode can be effectively positioned therein, which provides effective positioning and limiting effect on the electrode. Furthermore, the elastic thrust structure provides elastic thrust to the electrode, so that the electrode is always pushed to fit against the electrode area, ensuring that the electromagnet is always energized.

[0091] In some cases, when the electromagnet is mounted on the splined nut pulley (second transmission wheel 14), the power cord of the electromagnet and the electromagnet rotate with the second transmission wheel 14, causing the cable to be pulled or tangled. To address this, the following solution is proposed:

[0092] The electromagnet has several electrodes 1711 and an elastic thrust structure 1712. Under the action of the thrust system, the electrodes 1711 and the electrode region 181 are in close contact.

[0093] An electrode plate 18 is provided, which is fixed to the outer ring 122 of the spline nut or the second robotic arm 7. The electrode plate 18 can rotate relative to the electromagnet and the second transmission wheel 14. Several annular electrode areas 181 are provided on the electrode plate 18. The electrode areas 181 on the electrode plate 18 correspond to the electrodes 1711 on the electromagnet. The electrodes 1711 can slide on the electrode areas 181 as the electromagnet rotates, and the electromagnet is always energized.

[0094] The present invention also provides a horizontal multi-joint robot, which includes the aforementioned lead screw assembly.

[0095] In some embodiments, the horizontal multi-joint robot further includes a first robotic arm 4 and a second robotic arm 7. One end of the first robotic arm 4 forms a first rotation axis, namely the J1 axis, and the first robotic arm 4 can rotate around the J1 axis. The other end of the first robotic arm 4 is rotatably connected to one end of the second robotic arm 7 to form a second rotation axis, namely the J2 axis, and the second robotic arm 7 can rotate around the J2 axis. The other end of the second robotic arm 7 is provided with the lead screw 10, the first transmission wheel 13, the second transmission wheel 14, the first friction plate 15, the second friction plate 16, the first sleeve, and the second sleeve. The outer ring 112 of the lead screw nut is fixedly connected to the second robotic arm 7, and the outer ring 122 of the spline nut is fixedly connected to the second robotic arm 7.

[0096] This is a further preferred structural form of the horizontal lead screw assembly of the present invention. A rotatable J1 axis is formed at one end of the first robotic arm, which rotates around the J1 axis. The other end of the first robotic arm is rotatably connected to one end of the second robotic arm to form the J2 axis, allowing the second robotic arm to rotate around the J2 axis. Since both the J1 and J2 axes are rotatable, the robot can rotate in multiple different positions, improving its freedom and flexibility. The present invention also incorporates a lead screw, sleeve, friction plate, and transmission wheel at the other end of the second robotic arm, which effectively controls the rotation of the lead screw, i.e., rotation around the J4 axis and axial movement along the J3 axis, further improving the robot's freedom. The spline and the outer ring of the lead screw nut are fixed to the second robotic arm, supporting the inner ring of the spline and the lead screw nut, thereby driving the lead screw to rotate around the J4 axis and / or move axially along the J3 axis.

[0097] In some embodiments, the second robotic arm 7 is further equipped with a third motor 8 and a fourth motor 9. The third motor 8 can drive the first transmission wheel 13 to rotate, and the fourth motor 9 can drive the second transmission wheel 14 to rotate. The first transmission wheel 13 is a lead screw nut pulley, and the second transmission wheel 14 is a spline nut pulley. By simultaneously driving the first transmission wheel 13 and the second transmission wheel 14 to rotate, the lead screw 10 is driven to perform axial movement and / or rotation. This is a further preferred structural form of the horizontal lead screw assembly of the present invention, in which the third motor and the fourth motor are both mounted on the second robotic arm and are used to drive the first and second transmission wheels to rotate, respectively, thereby effectively driving the lead screw to perform axial movement and rotation through the lead screw and the inner ring of the spline nut, achieving the purpose of precise control.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A lead screw assembly, characterized by: The screw rod assembly comprises a screw rod (10), a first transmission wheel (13), a second transmission wheel (14), a first friction plate (15), a second friction plate (16), a first sleeve, a second sleeve and an elastic device (17), the first transmission wheel (13) can drive the first sleeve and the first friction plate (15) to rotate simultaneously, the second transmission wheel (14) can drive the second sleeve and the second friction plate (16) to rotate simultaneously, the first friction plate (15) and the second friction plate (16) are oppositely arranged, the screw rod (10) is arranged in the first sleeve and the second sleeve, the first sleeve is threadedly connected with the screw rod (10), and the second sleeve is keyed connected with the screw rod (10). The elastic device (17) can release elastic force to make the first friction plate (15) contact the second friction plate (16), the first friction plate (15), the second friction plate (16), the first transmission wheel (13), the second transmission wheel (14), the first sleeve, the second sleeve and the screw rod are connected as a whole, so that the first sleeve, the second sleeve and the screw rod (10) can rotate synchronously to limit the axial movement of the screw rod (10). The screw rod assembly further comprises a spline nut outer ring (122), the elastic device (17) comprises a magnetic structure (171) and an elastic structure (172), the magnetic structure (171) is an electromagnetic structure, the electromagnetic structure comprises an electromagnet and an electrode plate (18), the electromagnet is arranged on one side of the second transmission wheel (14) facing the spline nut outer ring (122), so that the electromagnet rotates integrally with the second transmission wheel (14), the electrode plate (18) is arranged on one side of the spline nut outer ring (122) facing the second transmission wheel (14), one side of the electromagnet facing the electrode plate (18) is further provided with an electrode (1711), and one side of the electrode plate (18) facing the electromagnet is provided with an annular electrode area (181), the annular electrode area (181) is opposite to the movement position of the electrode (1711), so that the electrode (1711) is always in contact with the electrode area (181) during rotation.

2. The screw rod assembly according to claim 1, wherein: the first sleeve is a screw nut inner ring (111), the screw rod assembly further comprises a screw nut outer ring (112), the screw nut outer ring (112) is arranged on the outer periphery of the screw nut inner ring (111), the screw nut inner ring (111) rotates relative to the screw nut outer ring (112), the screw nut outer ring (112) further limits the axial movement of the screw nut inner ring (111), and the screw nut inner ring (111) and the screw nut outer ring (112) constitute a screw nut (11).

3. The screw rod assembly according to claim 2, wherein: ​ The inner peripheral wall of the screw nut inner ring (111) is provided with an internal thread, the outer peripheral wall of the screw rod (10) is provided with an external thread, the internal thread matches the external thread, so that the screw nut inner ring (111) and the screw rod (10) form a matched screw pair, when the screw nut inner ring (111) is driven to rotate, it drives the screw rod (10) to move axially relative to the screw nut inner ring (111) while rotating.

4. The screw rod assembly according to claim 2 or 3, characterized in that: The second sleeve is a spline nut inner ring (121), the spline nut outer ring (122) is sleeved on the outer periphery of the spline nut inner ring (121), the spline nut inner ring (121) rotates relative to the spline nut outer ring (122), the spline nut outer ring (122) also limits the axial movement of the spline nut inner ring (121), and the spline nut inner ring (121) and the spline nut outer ring (122) form a spline nut (12).

5. The screw rod assembly according to claim 4, characterized in that: The inner peripheral wall of the spline nut inner ring (121) is provided with a spline groove, the outer peripheral wall of the screw rod (10) is provided with a spline, the spline matches the spline groove, so that the spline nut inner ring (121) and the screw rod (10) form a matched rotation pair, when the spline nut inner ring (121) is driven to rotate, it drives the screw rod (10) to rotate integrally with the spline nut inner ring (121), and the screw rod (10) can move axially relative to the spline nut inner ring (121).

6. The screw rod assembly according to any one of claims 1-5, characterized in that: One end of the elastic structure (172) is connected with the first friction plate (15) or the second friction plate (16) to provide an elastic pushing force so that the first friction plate (15) and the second friction plate (16) are attached, the magnetic structure (171) is arranged on the side of the second friction plate (16) away from the first friction plate (15) to be able to provide a magnetic attraction force to the second friction plate (16), or is arranged on the side of the first friction plate (15) away from the second friction plate (16) to be able to provide a magnetic attraction force to the first friction plate (15), so as to overcome the elastic force of the elastic structure (172) to separate the second friction plate (16) from the first friction plate (15).

7. The screw rod assembly according to claim 6, characterized in that: When braking is needed, the magnetic structure (171) is controlled to be powered off, the second friction plate (16) is pushed to adhere to the first friction plate (15) by the elastic structure (172), so that the first friction plate (15) and the second friction plate (16) rotate integrally, and then drive the lead screw, the first sleeve structure and the second sleeve structure to rotate integrally; when braking is not needed, the magnetic structure (171) is controlled to be powered on, the magnetic attraction generated by the magnetic structure (171) overcomes the elastic force of the elastic structure (172) to separate the first friction plate (15) and the second friction plate (16), and the rotation of the first transmission wheel (13) and the rotation of the second transmission wheel (14) are controlled to control the axial movement and / or rotation of the lead screw (10).

8. The lead screw assembly according to claim 7, wherein: One end of the first transmission wheel (13) is connected with the first sleeve, and the other end is connected with the first friction plate (15); one end of the second transmission wheel (14) is connected with the second sleeve, and the other end is spaced apart from the second friction plate (16); the second friction plate (16) is sleeved on the outer periphery of the lead screw (10) and can not contact the lead screw (10); the second friction plate (16) can be driven by the second transmission wheel (14) to rotate integrally; the second transmission wheel (14) drives the second sleeve to rotate, and then drives the lead screw (10) to rotate.

9. The lead screw assembly according to claim 8, wherein: When the lead screw assembly further comprises a spline nut outer ring (122): The elastic structure (172) is arranged in the space between the second transmission wheel (14) and the second friction plate (16); one end of the elastic structure (172) is connected with the second transmission wheel (14), and the other end is connected with the second friction plate (16); the magnetic structure (171) is arranged between the second transmission wheel (14) and the spline nut outer ring (122); the magnetic structure (171) provides magnetic attraction to the second friction plate (16); and the elastic structure (172) provides elastic thrust to the second friction plate (16).

10. The lead screw assembly according to claim 9, wherein: When the second sleeve is a spline nut inner ring (121), the electromagnetic structure is mounted on the side of the spline nut outer ring (122) facing the second transmission wheel (14); the electromagnetic structure is fixed and does not rotate; and the spline nut inner ring (121), the second transmission wheel (14), the second friction plate (16) and the elastic structure (172) do not contact the electromagnetic structure.

11. The lead screw assembly according to claim 1, wherein: The electromagnet is further provided with a groove on the side facing the electrode plate (18), part of the electrode (1711) is located in the groove, part of the electrode (1711) extends out of the groove and one end of the electrode (1711) is in contact with the electrode area (181), the other end of the electrode (1711) is connected with the groove bottom by the elastic thrust structure (1712), and the elastic thrust structure (1712) applies elastic thrust to the electrode (1711).

12. A multi-joint robot characterized by comprising: The screw rod assembly according to any one of claims 1-11.

13. The multi-joint robot according to claim 12, characterized in that: When the screw rod assembly further comprises a screw rod nut outer ring (112) and a spline nut outer ring (122): The multi-joint robot further comprises a first mechanical arm (4) and a second mechanical arm (7), one end of the first mechanical arm (4) is formed into a first rotating shaft, i.e. a J1 shaft, the first mechanical arm (4) can rotate around the J1 shaft, the other end of the first mechanical arm (4) is rotationally connected with one end of the second mechanical arm (7) to form a second rotating shaft, i.e. a J2 shaft, the second mechanical arm (7) can rotate around the J2 shaft, the other end of the second mechanical arm (7) is provided with the screw rod (10), the first transmission wheel (13), the second transmission wheel (14), the first friction plate (15), the second friction plate (16), the first sleeve and the second sleeve; the screw rod nut outer ring (112) is fixedly connected with the second mechanical arm (7), and the spline nut outer ring (122) is fixedly connected with the second mechanical arm (7).

14. The multi-joint robot according to claim 13, characterized in that: The second mechanical arm (7) is further provided with a third motor (8) and a fourth motor (9), the third motor (8) can drive the first transmission wheel (13) to rotate, and the fourth motor (9) can drive the second transmission wheel (14) to rotate; the first transmission wheel (13) is a screw rod nut pulley, the second transmission wheel (14) is a spline nut pulley, and the screw rod (10) is driven to move axially and / or rotate by simultaneously driving the first transmission wheel (13) and the second transmission wheel (14) to rotate.

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