Low-inertia type robot

Abstract

The invention belongs to the technical field of six-degree-of-freedom vertical multi-joint industrial robots, and particularly relates to a low-inertia robot. Comprising a forearm shell, a forearm cover, a wrist shaft, a power output mechanism and a three-stage transmission mechanism, the wrist shaft is rotationally connected to the tail end of the forearm shell, the forearm cover is connected with the forearm shell, a transmission cavity is formed between the forearm cover and the forearm shell, and the power output shaft mechanism and the three-stage transmission mechanism are both arranged in the transmission cavity. The power output mechanism is connected with the wrist shaft through the three-stage transmission mechanism and provides power for rotation of the wrist shaft. Transmission parts are arranged in the forearm shell and the forearm cover and are sequentially arranged from the wrist shaft to the elbow joint shaft, distribution is more uniform, transmission inertia is smaller, controllability is good, and the wrist part is small in size and light in weight.

Description

Technical Field

[0001] The present invention belongs to the technical field of six-degree-of-freedom vertical multi-joint industrial robots, and particularly relates to a low-inertia robot. Background Art

[0002] Six-degree-of-freedom vertical multi-joint industrial robots are widely used in the industrial manufacturing field. In existing six-degree-of-freedom vertical multi-joint industrial robots, an RV reducer is usually placed on the wrist axis, and a reducer steel casting shell is provided outside the RV reducer. This structure increases the volume and weight of the wrist part and has a large transmission inertia. Therefore, there is an urgent need for a low-inertia robot. Summary of the Invention

[0003] Aiming at the above problems, the purpose of the present invention is to provide a low-inertia robot to solve the problems of the existing six-degree-of-freedom vertical multi-joint industrial robot, such as the increased volume and weight of the wrist part, large transmission inertia, and low precision.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] The present invention provides a low-inertia robot, including a forearm shell, a forearm cover, a wrist axis, a power output mechanism, and a three-stage transmission mechanism. The wrist axis is rotatably connected to the end of the forearm shell. The forearm cover is connected to the forearm shell, and a transmission cavity is formed between the forearm cover and the forearm shell. The power output shaft mechanism and the three-stage transmission mechanism are both arranged in the transmission cavity, and the power output mechanism is connected to the wrist axis through the three-stage transmission mechanism to provide power for the rotation of the wrist axis.

[0006] The power output mechanism includes a motor and an input shaft assembly. The motor is arranged at the front end of the forearm shell, and the motor shaft is connected to the input shaft assembly. The axis of the input shaft assembly is parallel to the axis of the wrist axis.

[0007] The input shaft assembly includes an input helical gear shaft, an input shaft, and an input helical gear. The input shaft is a hollow structure and is sleeved on the motor shaft. The input shaft is rotatably connected to the forearm shell. One end of the input helical gear shaft is inserted into the input shaft and connected to the motor shaft, and the other end of the input helical gear shaft is rotatably connected to the forearm cover. The input helical gear is fixedly arranged on the input helical gear shaft and is in transmission connection with the three-stage transmission mechanism.

[0008] The input shaft is connected to the forearm shell through a double-row angular contact ball bearing I. The inner ring of the double-row angular contact ball bearing I is axially limited by an eccentric snap ring for shaft use, and the outer ring of the double-row angular contact ball bearing I is axially limited by an eccentric snap ring for hole use. The eccentric snap ring for shaft use and the eccentric snap ring for hole use balance the axial force generated by the input helical gear during transmission.

[0009] The three-stage transmission mechanism includes a first-stage gear assembly, a second-stage gear assembly, and an output shaft assembly that are sequentially connected in transmission. The first-stage gear assembly is in transmission connection with the power output mechanism, and the output shaft assembly is connected to the wrist shaft.

[0010] The first-stage gear assembly includes a first-stage gear shaft, a first-stage large gear, and a first-stage small gear. One end of the first-stage gear shaft is connected to the small arm housing through a cylindrical roller bearing I, and the other end of the first-stage gear shaft is connected to the small arm cover through a double-row angular contact ball bearing II. The first-stage large gear and the first-stage small gear are coaxially installed on the first-stage gear shaft and rotate with the first-stage gear shaft. The first-stage large gear is in transmission connection with the power output mechanism, and the first-stage small gear is in transmission connection with the second-stage gear assembly.

[0011] The second-stage gear assembly includes a variable tooth thickness small gear shaft, a second-stage large gear, and a variable tooth thickness small gear. Both ends of the variable tooth thickness small gear shaft are respectively connected to the small arm housing and the small arm cover through cylindrical roller bearings II, and the outer rings of the cylindrical roller bearings II are axially limited by a ball pressing shaft thread gland. The second-stage large gear and the variable tooth thickness small gear are coaxially installed on the variable tooth thickness small gear shaft and rotate with the variable tooth thickness small gear shaft. The second-stage large gear meshes with the first-stage small gear, and the variable tooth thickness small gear is in transmission connection with the output shaft assembly.

[0012] The output shaft assembly includes an output shaft and a variable tooth thickness large gear. One end of the output shaft is connected to the wrist shaft, and the other end of the output shaft is connected to the small arm cover through a tapered roller bearing. The variable tooth thickness large gear is fixedly arranged on the output shaft and meshes with the variable tooth thickness small gear.

[0013] A stepped blind hole is provided along the axis at the other end of the variable tooth thickness small gear shaft, and a tooth clearance compensation mechanism is arranged in the stepped blind hole. The tooth clearance compensation mechanism is used to compensate the meshing clearance between the variable tooth thickness large gear and the variable tooth thickness small gear.

[0014] The tooth clearance compensation mechanism includes a steel ball, a spring, a ball pressing thread plug, and an inner hexagon plug screw. The steel ball, the spring, and the ball pressing thread plug are accommodated in the stepped blind hole of the variable tooth thickness small gear shaft from the inside to the outside. The inner hexagon plug screw is arranged outside the ball pressing thread plug and is in threaded connection with the ball pressing shaft thread gland.

[0015] The advantages and beneficial effects of the present invention are as follows: A low-inertia type robot provided by the present invention places the transmission components inside the small arm housing and the small arm cover, and arranges them sequentially from the wrist axis to the elbow axis. The distribution is more uniform, the moment of inertia is smaller, the controllability is good, and the volume of the wrist part is small and the weight is light. Compared with the RV reduction mechanism type, a reducer cast steel shell is saved, and the production cost is low. Description of the Drawings

[0016] Figure 1 Schematic diagram of the structure of a low-inertia robot according to the present invention;

[0017] Figure 2 is Figure 1 Partial enlarged view of part A of

[0018] Figure 3 is Figure 1 Partial enlarged view of part B of

[0019] In the figure: 1 - small arm housing, 2 - small arm cover, 3 - wrist shaft, 4 - output shaft assembly, 4A - output shaft, 4B - variable tooth thickness large gear, 5 - tapered roller bearing, 6 - variable tooth thickness gear meshing kinematic pair, 7 - second-stage gear assembly, 7A - variable tooth thickness pinion shaft, 7B - second-stage large gear, 7C - variable tooth thickness pinion, 8 - cylindrical roller bearing II, 9 - steel ball, 10 - spring, 11 - ball pressure thread plug, 12 - hexagon socket plug screw, 13 - ball pressure shaft thread gland, 14 - outer side seal end cover, 15 - inner side seal end cover, 16 - first-stage gear assembly, 16A - first-stage gear shaft, 16B - first-stage large gear, 16C - first-stage pinion, 17 - double-row angular contact ball bearing II, 18 - first-stage gear shaft end retaining ring, 19 - first-stage gear shaft external thread gland, 20 - cylindrical roller bearing I, 21 - input shaft assembly, 21A - input helical gear shaft, 21B - input shaft, 21C - input helical gear, 22 - needle bearing, 23 - double-row angular contact ball bearing I, 24 - shaft eccentric snap ring, 25 - hole eccentric snap ring, 26 - motor. Detailed implementation manner

[0020] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] As Figures 1 to 3 shown, the present invention provides a low-inertia robot, including a small arm housing 1, a small arm cover 2, a wrist shaft 3, a power output mechanism and a three-stage transmission mechanism. The wrist shaft 3 is rotatably connected to the end of the small arm housing 1, the small arm cover 2 is connected to the small arm housing 1, a transmission cavity is formed between the small arm cover 2 and the small arm housing 1, the power output shaft mechanism and the three-stage transmission mechanism are both arranged in the transmission cavity, and the power output mechanism is connected to the wrist shaft 3 through the three-stage transmission mechanism, and the power output mechanism provides power for the rotation of the wrist shaft 3.

[0022] As Figure 1 shown, in the embodiment of the present invention, the power output mechanism includes a motor 26 and an input shaft assembly 21. The motor 26 is arranged at the head end of the small arm housing 1, and the motor shaft is connected to the input shaft assembly 21. The axis of the input shaft assembly 21 is parallel to the axis of the wrist shaft 3.

[0023] As Figure 2As shown, in the embodiment of the present invention, the input shaft assembly 21 includes an input bevel gear shaft 21A, an input shaft 21B and an input bevel gear 21C, wherein the input shaft 21B is a hollow structure and is sleeved on the motor shaft, the input shaft 21B is rotatably connected to the arm housing 1, one end of the input bevel gear shaft 21A is inserted into the input shaft 21B and connected to the motor shaft, the other end of the input bevel gear shaft 21A is rotatably connected to the arm cover 2, and the input bevel gear 21C is fixed on the input bevel gear shaft 21A and is transmission-connected to the three-stage transmission mechanism.

[0024] Specifically, the input shaft 21B is connected to the arm housing 1 through a double-row angular contact ball bearing I23, the inner ring of the double-row angular contact ball bearing I23 is axially limited by an eccentric snap ring 24 for the shaft, and the outer ring of the double-row angular contact ball bearing I23 is axially limited by an eccentric snap ring 25 for the opening. The eccentric snap ring 24 for the shaft and the eccentric snap ring 25 for the opening balance the axial force generated by the input helical gear 21C during the transmission process. The other end of the input helical gear shaft 21A is rotatably connected to the arm cover 2 through a needle bearing 22.

[0025] In this embodiment, the eccentric retaining ring 24 for shaft and the eccentric retaining ring 25 for opening are commercially available products. The specific brand of the eccentric retaining ring 24 for shaft is Rotor Clip, and the model number is BSH-98P102. The bent C-type retaining ring for shaft is loaded on the bearing and has the feature of being able to fill the cumulative tolerance of the assembly. Once installed in the groove on the shaft, the bent retaining ring can apply axial force or pre-load axial load to the parts within a specified range. The specific brand of the eccentric retaining ring 25 for opening a hole is Rotor Clip, and the model number is VHO-206P90. The angled retaining ring for opening a hole looks similar to the C-type retaining ring HO for opening a hole, but the outer periphery of this retaining ring has a 15° bevel. In order to better fix and prevent the parts from moving, the groove for installing the retaining ring needs to have the same 15° bevel as the retaining ring. The eccentric retaining ring 24 for the shaft and the eccentric retaining ring 25 for the opening can effectively shield the axial force component of the helical gear pair meshing between the first-stage large gear 16B and the input helical gear 21C.

[0026] like Figure 1 As shown, in an embodiment of the present invention, the three-stage transmission mechanism is arranged sequentially from the wrist axis 3 to the elbow joint axis, and the three-stage transmission mechanism includes a first-stage gear assembly 16, a second-stage gear assembly 7 and an output shaft assembly 4 which are sequentially connected in transmission connection, wherein the first-stage gear assembly 16 is transmission connected to the power output mechanism, and the output shaft assembly 4 is connected to the wrist axis 3.

[0027] like Figure 1As shown, in the embodiment of the present invention, the first-stage gear assembly 16 includes a first-stage gear shaft 16A, a first-stage large gear 16B and a first-stage small gear 16C, wherein one end of the first-stage gear shaft 16A is connected to the small arm housing 1 through a cylindrical roller bearing Ⅰ20, and the other end of the first-stage gear shaft 16A is connected to the small arm cover 2 through a double-row angular contact ball bearing Ⅱ17, the first-stage large gear 16B and the first-stage small gear 16C are coaxially installed on the first-stage gear shaft 16A, and rotate with the first-stage gear shaft 16A; the first-stage large gear 16B is meshed with the input helical gear 21C in the power output mechanism to transmit power, and the first-stage small gear 16C is transmission-connected to the second-stage gear assembly 7.

[0028] Furthermore, the inner and outer rings of the double-row angular contact ball bearing II 17 are axially limited by a first-stage gear shaft end retaining ring 18 and a first-stage gear shaft external threaded gland 19 respectively.

[0029] like Figure 3 As shown, in the embodiment of the present invention, the second-stage gear assembly 7 includes a variable tooth thickness pinion shaft 7A, a second-stage large gear 7B and a variable tooth thickness pinion 7C, wherein the two ends of the variable tooth thickness pinion shaft 7A are respectively connected to the arm housing 1 and the arm cover 2 through cylindrical roller bearings II8, and the outer rings of the two cylindrical roller bearings II8 are axially limited by two ball-pressing shaft threaded glands 13, and the centers of the two ball-pressing shaft threaded glands 13 are respectively provided with an outer sealing end cover 14 and an inner sealing end cover 15. The second-stage large gear 7B and the variable tooth thickness pinion 7C are coaxially mounted on the variable tooth thickness pinion shaft 7A and rotate with the variable tooth thickness pinion shaft 7A; the second-stage large gear 7B is meshed with the first-stage pinion 16C, and the variable tooth thickness pinion 7C is drivingly connected to the output shaft assembly 4.

[0030] Specifically, the second-stage large gear 7B and the variable tooth thickness pinion shaft 7A are assembled by heat-fitting. Specifically, the heat-fitting process is: the variable tooth thickness pinion shaft 7A is cooled by liquid nitrogen, the second-stage large gear 7B is heated, and then the variable tooth thickness pinion shaft 7A is inserted into the center hole of the second-stage large gear 7B through a tool.

[0031] like Figure 3 As shown, in the embodiment of the present invention, the output shaft assembly 4 includes an output shaft 4A and a variable tooth thickness gear 4B, wherein one end of the output shaft 4A is connected to the wrist shaft 3, and the other end of the output shaft 4A is connected to the arm cover 2 through a pair of tapered roller bearings 5, and the variable tooth thickness gear 4B is fixed on the output shaft 4A and meshes with the variable tooth thickness pinion 7C to form a variable tooth thickness gear meshing motion pair 6.

[0032] In an embodiment of the present invention, a stepped blind hole is provided along the axis of the other end of the variable tooth thickness pinion shaft 7A, and a tooth clearance compensation mechanism is provided in the stepped blind hole. The tooth clearance compensation mechanism is used to compensate for the meshing clearance between the variable tooth thickness large gear 4B and the variable tooth thickness pinion 7C.

[0033] In an embodiment of the present invention, the tooth clearance compensation mechanism includes a steel ball 9, a spring 10, a ball pressing threaded plug 11 and an internal hexagonal plug screw 12. The steel ball 9, the spring 10 and the ball pressing threaded plug 11 are accommodated in a stepped blind hole of the variable tooth thickness pinion shaft 7A from the inside to the outside. The internal hexagonal plug screw 12 is arranged outside the ball pressing threaded plug 11 and is threadedly connected to the ball pressing shaft threaded cover 13. The internal hexagonal plug screw 12 is located inside the outer sealing end cover 14.

[0034] Further, the blind end of the stepped blind hole at the other end of the variable tooth thickness pinion shaft 7A is a conical surface. The steel ball 9 forms a ring contact with the conical surface. The upper end of the spring 10 abuts against the steel ball 9, and the lower end of the spring 10 abuts against the ball pressing threaded plug 11. The ball pressing threaded plug 11 is threadedly engaged with the ball pressing shaft threaded cover 13 with fine threads, and the ball pressing shaft threaded cover 13 is threadedly engaged with the small arm cover 2 with fine threads.

[0035] In this embodiment, both the small arm housing 1 and the small arm cover 2 are made of cast aluminum alloy. The small arm housing 1 and the small arm cover 2 are connected by screws and pins. The internal hexagonal plug screw 12 is used to lock the relationship between the ball pressing threaded plug 11 and the ball pressing shaft threaded cover 13. The outer sealing end cover 14 and the inner sealing end cover 15 are respectively used to block the small arm cover 2 and the small arm housing 1. Therefore, the clearance compensation principle of the second-stage gear assembly 7 is that the spring force of the spring 10 always compensates to keep the variable tooth thickness gear meshing pair 6 between the variable tooth thickness pinion 7C and the variable tooth thickness gear 4B in contact without clearance, so as to ensure the transmission stiffness of the three-stage transmission mechanism. Specifically, the transmission stiffness is: the servo motor brake is braked, the maximum torque is applied to the output end of the reducer in the forward direction, and then gradually weakened to the maximum torque in the reverse direction. Due to a series of factors such as the structural nonlinear stiffness, the gear nonlinear contact stiffness, and the bearing nonlinear stiffness of the output end, the output shaft angle will change. The output shaft load torque-output shaft torsion curve is drawn, and the curve characteristic is the stiffness characteristic of the reducer.

[0036] The present invention provides a low-inertia type robot, in which the transmission parts are placed inside the aluminum alloy small arm and the aluminum alloy small arm cover, and are arranged sequentially from the wrist axis to the elbow axis. From the perspective of the robot transmission and structural configuration, the present invention has a smaller inertia and a more uniform distribution. Compared with the RV reduction gear mechanism type, one reducer steel shell is saved, and it has more price advantages in mass production cost.

[0037] The above is only the embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A low-inertia type robot, characterized in that, It includes a small arm housing (1), a small arm cover (2), a wrist shaft (3), a power output mechanism and a three-stage transmission mechanism. The wrist shaft (3) is rotatably connected to the end of the small arm housing (1). The small arm cover (2) is connected to the small arm housing (1), and a transmission cavity is formed between the small arm cover (2) and the small arm housing (1). The power output shaft mechanism and the three-stage transmission mechanism are both arranged in the transmission cavity, and the power output mechanism is connected to the wrist shaft (3) through the three-stage transmission mechanism, and the power output mechanism provides power for the rotation of the wrist shaft (3).

2. The low-inertia type robot according to claim 1, wherein The power output mechanism includes a motor (26) and an input shaft assembly (21). The motor (26) is arranged at the head end of the small arm housing (1), and the motor shaft is connected to the input shaft assembly (21). The axis of the input shaft assembly (21) is parallel to the axis of the wrist shaft (3).

3. The low-inertia type robot according to claim 2, wherein The input shaft assembly (21) includes an input helical gear shaft (21A), an input shaft (21B) and an input helical gear (21C). The input shaft (21B) is of a hollow structure and is sleeved on the motor shaft. The input shaft (21B) is rotatably connected to the small arm housing (1). One end of the input helical gear shaft (21A) is inserted into the input shaft (21B) and connected to the motor shaft. The other end of the input helical gear shaft (21A) is rotatably connected to the small arm cover (2). The input helical gear (21C) is fixed on the input helical gear shaft (21A) and is in transmission connection with the three-stage transmission mechanism.

4. The low-inertia type robot according to claim 3, characterized in that, The input shaft (21B) is connected to the small arm housing (1) through a double-row angular contact ball bearing I (23). The inner ring of the double-row angular contact ball bearing I (23) is axially limited by a shaft eccentric snap ring (24), and the outer ring of the double-row angular contact ball bearing I (23) is axially limited by a hole eccentric snap ring (25). The shaft eccentric snap ring (24) and the hole eccentric snap ring (25) balance the axial force generated by the input helical gear (21C) during transmission.

5. The low-inertia type robot according to claim 1, characterized in that The three-stage transmission mechanism includes a first-stage gear assembly (16), a second-stage gear assembly (7) and an output shaft assembly (4) that are sequentially in transmission connection. The first-stage gear assembly (16) is in transmission connection with the power output mechanism, and the output shaft assembly (4) is connected to the wrist shaft (3).

6. The low inertia type robot according to claim 5, characterized in that, The first-stage gear assembly (16) includes a first-stage gear shaft (16A), a first-stage large gear (16B) and a first-stage small gear (16C). One end of the first-stage gear shaft (16A) is connected to the small arm housing (1) through a cylindrical roller bearing I (20), and the other end of the first-stage gear shaft (16A) is connected to the small arm cover (2) through a double-row angular contact ball bearing II (17). The first-stage large gear (16B) and the first-stage small gear (16C) are coaxially installed on the first-stage gear shaft (16A) and rotate with the first-stage gear shaft (16A). The first-stage large gear (16B) is in transmission connection with the power output mechanism, and the first-stage small gear (16C) is in transmission connection with the second-stage gear assembly (7).

7. The low-inertia type robot according to claim 6, characterized in that, The second-stage gear assembly (7) includes a variable tooth thickness pinion shaft (7A), a second-stage large gear (7B), and a variable tooth thickness pinion (7C). The two ends of the variable tooth thickness pinion shaft (7A) are respectively connected to the small arm housing (1) and the small arm cover (2) through cylindrical roller bearings II (8), and the outer rings of the cylindrical roller bearings II (8) are axially limited by a ball pressing shaft thread gland (13); the second-stage large gear (7B) and the variable tooth thickness pinion (7C) are coaxially installed on the variable tooth thickness pinion shaft (7A) and rotate with the variable tooth thickness pinion shaft (7A); the second-stage large gear (7B) meshes with the first-stage pinion (16C), and the variable tooth thickness pinion (7C) is in transmission connection with the output shaft assembly (4).

8. The low-inertia type robot according to claim 7, wherein The output shaft assembly (4) includes an output shaft (4A) and a variable tooth thickness large gear (4B). One end of the output shaft (4A) is connected to the wrist shaft (3), the other end of the output shaft (4A) is connected to the small arm cover (2) through a tapered roller bearing (5), the variable tooth thickness large gear (4B) is fixedly arranged on the output shaft (4A), and meshes with the variable tooth thickness pinion (7C).

9. The low-inertia type robot according to claim 8, characterized in that, A stepped blind hole is provided along the axis at the other end of the variable tooth thickness pinion shaft (7A), and a tooth clearance compensation mechanism is arranged in the stepped blind hole. The tooth clearance compensation mechanism is used to compensate the meshing clearance between the variable tooth thickness large gear (4B) and the variable tooth thickness pinion (7C).

10. The low-inertia type robot according to claim 9, characterized in that, The tooth clearance compensation mechanism includes a steel ball (9), a spring (10), a ball pressing thread plug (11), and an internal hexagon plug screw (12). The steel ball (9), the spring (10), and the ball pressing thread plug (11) are accommodated in the stepped blind hole of the variable tooth thickness pinion shaft (7A) from the inside to the outside. The internal hexagon plug screw (12) is arranged outside the ball pressing thread plug (11) and is threadedly connected to the ball pressing shaft thread gland (13).

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