A high-precision transmission device

Abstract

The application discloses a high-precision transmission device, and belongs to a mechanical transmission device. The device comprises a split shell and three-stage transmission mechanisms integrated in the split shell and sequentially connected in transmission. In the three-stage transmission mechanisms, the sun gear of the first-stage involute planetary gear transmission mechanism is connected with an external input motor, and the planet gear and the cam shaft of the cycloid pin gear are connected through a spline. The second-stage cycloid pin gear transmission mechanism adopts a symmetrical layout of double cycloid gears and is driven by an eccentric cam shaft. The third-stage variable-thickness gear transmission mechanism comprises a variable-thickness pinion and a variable-thickness gear, the thickness of the gears changes nonlinearly along the axial direction, and the variable-thickness gear changes the axial meshing position through an adjusting gasket to control the side gap. The high-precision transmission device has the advantages of adjustable speed ratio, high stiffness, parallel shaft transmission, high precision, high efficiency, high rigidity, light weight and long service life, and can be applied to complex working conditions of robots.

Description

TECHNICAL FIELD

[0001] The present application belongs to mechanical transmission device, and particularly relates to a high-precision transmission device. BACKGROUND

[0002] The conventional features of a robot gear transmission device are high precision, high efficiency, high rigidity, light weight, and long service life, and the performance thereof directly determines the motion stability, load capacity, and working precision of the robot. The selection of different types of reducers needs to comprehensively consider the load, cost, and space constraints. The types of robot gear transmission include involute planetary transmission, cycloid pin wheel transmission, and variable-thickness gear transmission.

[0003] The core advantages of the involute planetary transmission are high load capacity, high efficiency, compact structure, and the like. However, the planetary transmission has the characteristics of low transmission precision and poor backlash control due to the special structure of the multi-stage gear pair with backlash. The cycloid transmission has the characteristics of high transmission efficiency, high transmission precision, compact structure, large load capacity, stable operation, low noise, and small vibration. However, the cycloid transmission is commonly used for concentric shaft transmission and cannot realize parallel shaft transmission and staggered shaft transmission. The involute variable-thickness gear transmission is a new type of cylindrical gear, and the displacement coefficient thereof changes linearly along the axial direction. The variable-thickness gear transmission has the advantages of high load capacity, high precision, stable transmission, and adjustable backlash. The characteristics of the variable-thickness gear transmission are that the tooth profile has different displacement coefficients along the tooth width direction, and the tooth tip has a certain taper. Due to the unique design of the variable-thickness gear transmission, the variable-thickness gear transmission has the advantages of small size, large coincidence, and high strength. The variable-thickness gear transmission can realize precise transmission through axial backlash adjustment. However, the variable-thickness gear transmission cannot realize high speed due to the sliding friction, and the temperature rise is large. In addition, the variable-thickness gear transmission has high machining difficulty and high tool requirement, and cannot realize flexible adjustment of the speed ratio. SUMMARY

[0004] The present application aims to overcome the limitations of the conventional gear transmission method, and provides a high-precision transmission device which has good overall performance and excellent overall transmission precision, and is suitable for complex working conditions of robots.

[0005] The application provides a high-precision transmission device, which comprises a split shell, a involute planetary gear transmission mechanism, a cycloid-pin gear transmission mechanism and a variable-thickness gear transmission mechanism which are integrated in the split shell and sequentially connected in transmission; the sun gear of the involute planetary gear transmission mechanism is connected with an input motor in interference fit, the planet gear is connected with a cam shaft of the cycloid-pin gear transmission mechanism through spline connection, and the speed ratio range is 40-200; the cycloid-pin gear transmission mechanism adopts a symmetrical layout design of two cycloid gears with a phase difference of 180 degrees, is driven by the cam shaft in eccentricity, and the tooth profile of the cycloid gear is engaged with the pin gear fixed on the pin gear shell; the low-speed rotation of the cycloid gear is transmitted to the variable-thickness pin gear of the variable-thickness gear transmission mechanism through the planet carrier; the variable-thickness gear transmission mechanism comprises a variable-thickness pin gear and a variable-thickness gear, the tooth thickness of the variable-thickness pin gear and the variable-thickness gear changes nonlinearly along the axial direction, the taper angle is 1-5 degrees, the variable-thickness gear is installed on the split shell through a deep groove ball bearing, an adjustable gasket is arranged axially between the variable-thickness gear and the deep groove ball bearing, and the side clearance is controlled by adjusting the thickness of the gasket to change the axial engagement position; and the variable-thickness gear is connected with an output flange as an output end.

[0006] According to the preferred scheme of the application, the split shell comprises an upper shell and a lower shell, the lower shell is provided with a transmission mechanism cavity for mounting the involute planetary gear transmission mechanism, the cycloid-pin gear transmission mechanism and the variable-thickness gear transmission mechanism, an input motor mounting cavity and an output flange mounting cavity; the transmission mechanism cavity is arranged at the top of the lower shell and is closed by the upper shell.

[0007] Further, the involute planetary gear transmission mechanism, the cycloid-pin gear transmission mechanism and the variable-thickness pin gear are coaxially mounted on one side of the transmission mechanism cavity from bottom to top, the variable-thickness gear is mounted on the other side of the transmission mechanism cavity and is engaged with the variable-thickness pin gear; the input motor mounting cavity is used for mounting the input motor and is located below the transmission mechanism cavity, the bottom of the transmission mechanism cavity is provided with an input opening, and the output shaft of the input motor is connected with the sun gear of the involute planetary gear transmission mechanism through the input opening; the output flange mounting cavity is located below the variable-thickness gear and is provided with the output flange.

[0008] According to the preferred scheme of the application, the deep groove ball bearing is a full ball bearing, supports the variable-thickness gear and is fixed with the lower shell; and the output flange is coaxially fixed with the deep groove ball bearing through a supporting bearing.

[0009] Compared with the prior art, the application integrates a plurality of transmission devices of three transmission modes of involute planetary transmission, cycloid pin wheel transmission and involute variable-thickness gear transmission, the involute planetary transmission is arranged at the first stage, the cycloid pin wheel transmission is arranged at the second stage, and the involute variable-thickness gear transmission is arranged at the third stage. Through reasonable structural arrangement, the optimization of the three transmission modes is fully utilized, the shortcomings are made up, and a new type of gear transmission device is formed. The high-precision transmission device further realizes compactness and high rigidity through split design of the shell and optimization of bearing layout (such as full ball bearing). The high-precision transmission device has the advantages of adjustable speed ratio, high rigidity, parallel shaft transmission, high precision, high efficiency, high rigidity, light weight and long service life, and can be applied to complex working conditions of robots.

[0010] The application adopts active gap adjustment design, the gear thickness of the variable-thickness gear transmission mechanism changes nonlinearly along the axial direction, and the taper angle is 1°-5°; a gasket with a specified thickness is installed between the variable-thickness large gear and the deep groove ball bearing, the axial position of the variable-thickness large gear can be changed by adjusting the thickness of the gasket, and then the actual meshing position of the variable-thickness gear pair is changed, so that the side gap of the transmission mechanism is adjusted, and the application of occasions requiring precise gap adjustment is met.

[0011] In view of the problem that the cycloid transmission mode cannot realize parallel shaft and staggered shaft transmission, the application realizes parallel shaft / staggered shaft output through the third-stage variable-thickness gear, breaks through the concentric shaft limitation, and solves the demand of robot transmission. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is a main sectional view of the high-precision transmission device provided in the embodiments of the application;

[0013] Figure 2 It is a structural diagram of the high-precision transmission device of the application;

[0014] Figure 3 It is a schematic diagram of the first-stage involute planetary gear transmission mechanism;

[0015] Figure 4 It is a schematic diagram of the second-stage cycloid pin wheel transmission mechanism;

[0016] Figure 5 It is a schematic diagram of the conical tooth profile of the variable-thickness large gear;

[0017] Figure 6 It is a local enlarged view of the output flange;

[0018] Figure 7 It is an overall appearance view of the high-precision transmission device; Figure 7 The direction of the black arrow is the top view direction of the transmission device of the application;

[0019] Figure 8A schematic diagram of a test system for the high-precision transmission device in the embodiment;

[0020] Figure 9 A hysteresis curve diagram;

[0021] Figure 10 A result of the repeat positioning accuracy of the speed reducer.

[0022] In the figure, the lower housing 1, the servo motor 2, the planetary gear transmission mechanism 3, the cycloid pin wheel transmission mechanism 4, the pin gear housing 5, the planet carrier 6, the inner hexagonal cylindrical head screw 7, the variable-thickness pinion 8, the upper housing 9, the variable-thickness gear wheel 10, the sealing cover 11, the screw 12, the deep groove ball bearing 13, the lip seal ring 14, the output flange 15, the output flange bearing end cover 16, the support bearing 17, the camshaft 18, the test platform 19, the stand 20, the high-precision transmission device 21, the inclination sensor 22, the tool loading rod 23, the pressure sensor 24, the tool loading disc 25, and the hydraulic jack 26. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0024] It should be noted that all directional indications, such as up, down, left, right, front, back, etc., in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0025] In addition, the description such as "first", "second" and the like in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0026] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation" and the like should be understood in a broad sense, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection, or physical connection, or wireless communication connection; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] The present application will be further described in detail below in combination with the drawings.

[0028] In view of the limitations of the traditional gear transmission mode, the present embodiment provides a high-precision transmission device, which mainly comprises a distributed shell and a three-stage transmission mechanism, wherein the distributed shell comprises an upper shell 9 and a lower shell 1; the three-stage transmission mechanism is respectively a first-stage involute planetary gear transmission mechanism 3, a second-stage cycloid pin gear transmission mechanism 4 and a third-stage variable-tooth-thickness gear transmission mechanism. A space for mounting the input motor is arranged in the distributed shell; in an embodiment of the present application, the high-precision transmission device is provided with a servo motor 2 as the input motor, and the servo motor 2 is connected to the input end of the three-stage transmission mechanism as the input motor; in another optional embodiment of the present application, the high-precision transmission device is not provided with an input motor, and it only serves as a transmission mechanism; in this case, the user can install a motor with the required input power or connect the device of the present application with an external input mechanism according to the needs.

[0029] As shown in Figure 1 , the present embodiment illustrates a high-precision transmission device, which mainly comprises a lower shell 1, a servo motor 2, a first-stage planetary gear transmission mechanism 3, a second-stage cycloid pin gear transmission mechanism 4, a variable-tooth-thickness pinion 8, an upper shell 9, a variable-tooth-thickness gear wheel 10, an output flange 15 and the like. The shell of the transmission device is designed in a split structure (including the lower shell 1 and the upper shell 9), and the first-stage, second-stage and third-stage transmission mechanisms (all of which are reducer mechanisms in the present embodiment) are in the same transmission mechanism cavity, so that the structure is compact.

[0030] As shown in Figure 1 , the upper shell 9 and the lower shell 1 are connected by bolts to form the split shell, and the lower shell 1 is provided with a transmission mechanism cavity for mounting the involute planetary gear transmission mechanism, the cycloid pin gear transmission mechanism and the variable-tooth-thickness gear transmission mechanism, an input motor mounting cavity and an output flange mounting cavity; wherein the transmission mechanism cavity is opened at the top of the lower shell 1, and the upper shell 9 serves as the top cover of the transmission mechanism cavity.

[0031] As shown in Figure 1 , the transmission mechanism cavity is provided with a transmission mechanism mounting cavity, an input motor mounting cavity and an output flange mounting cavity, and the transmission mechanism mounting cavity is provided with a first-stage transmission mechanism mounting cavity, a second-stage transmission mechanism mounting cavity and a third-stage transmission mechanism mounting cavity.As shown, the involute planetary gear mechanism, cycloidal pin wheel transmission mechanism and variable-thickness small wheel are coaxially installed on one side of the transmission mechanism cavity from bottom to top, the variable-thickness large wheel is installed on the other side of the transmission mechanism cavity and meshes with the variable-thickness small wheel; the input motor installation cavity is used for installing the servo motor 2, which is located below the transmission mechanism cavity, the bottom of the transmission mechanism cavity is provided with an input opening, and the output shaft of the servo motor 2 is connected with the sun gear of the involute planetary gear mechanism through the input opening; the output flange installation cavity is located below the variable-thickness large wheel, and the output flange 15 is arranged in the output flange installation cavity. The deep groove ball bearing 13 is located in the transmission mechanism cavity, which supports the variable-thickness large wheel 10 and is fixed with the lower shell 1; the output flange 15 is coaxially fixed with the deep groove ball bearing 13 through the support bearing 17 located on the lower shell 1, and the support bearing 17 and the deep groove ball bearing 13 are installed in parallel. The pin tooth shell of the second-stage cycloidal pin wheel transmission mechanism 4 is horizontally arranged on one side of the transmission mechanism cavity through the pin tooth shell mounting hole, and the deep groove ball bearing is horizontally arranged on the other side of the transmission mechanism cavity through the deep groove ball bearing mounting hole; the parallelism of the pin tooth shell mounting hole and the deep groove ball bearing mounting hole is ≤0.01mm.

[0032] The first-stage transmission mechanism of the application is an involute planetary gear mechanism 3, as shown in the figure, Figure 3 As shown, the involute planetary gear mechanism 3 mainly includes a sun gear and three circumferentially distributed planetary gears; the sun gear is connected with the servo motor 2 through interference fit, and the three planetary gears are circumferentially distributed and connected with the cam shaft 18 of the cycloidal pin wheel transmission mechanism 4 through key tooth side centering interference, and the gear ratio of the sun gear and the planetary gear can adjust the speed ratio of the first-stage transmission mechanism in the range of (40~200) to adapt to different robot working conditions. The sun gear and the planetary gear of the involute spur planetary transmission can ensure a small enough rotation gap of the system under the premise of ensuring good vibration noise in high-speed working condition by reasonably controlling the backlash (0.02mm~0.08mm).

[0033] The second-stage transmission mechanism of the application is a cycloidal pin wheel transmission mechanism 4, as shown in the figure, Figure 4As shown, it comprises components such as cycloid gear, pin gear shell 5, planet carrier 6, hexagonal cylindrical head screw 7, camshaft 18 and needle bearing. The cycloidal pin gear mechanism 4 is fixed on the lower shell 1 by the axially divided hexagonal cylindrical head screw, and the cycloidal pin gear mechanism adopts a symmetrical layout design of two cycloid gears with a phase difference of 180°, and is driven eccentrically by the camshaft 18 and the needle bearing to balance the radial force and improve the carrying capacity. The cycloid tooth profile is a short amplitude standard external cycloid curve, and the circumferential 4~10 teeth are simultaneously meshed through the composite modification of the tooth top and tooth root. The camshaft is fixed circumferentially by the tapered roller bearing and the planet carrier 6, and the number of camshafts is equal to the number of planet gears, both of which are 3. The pin gear shell 5 and the planet carrier 6 are connected by matched cross roller bearings or angular contact bearings to ensure good output rigidity of the cycloidal pin gear mechanism.

[0034] When working, the planet wheel of the first involute planetary transmission drives the camshaft 18 through the spline, the eccentric rotation of the camshaft pushes the double cycloid gears to swing in the plane through the needle bearing, and the cycloid gear tooth profile is meshed with the pin gear fixed on the pin gear shell 5; the design of the double cycloid gears with a phase difference of 180° can offset the radial force and reduce vibration; the low-speed rotation of the cycloid gear is transmitted to the variable-thickness pinion 8 of the third variable-thickness gear through the planet carrier 6.

[0035] The third transmission mechanism of the application is a variable-thickness gear transmission mechanism, which mainly includes a variable-thickness pinion 8 and a variable-thickness gear wheel 10 (as shown in Figure 5 The variable-thickness pinion 8 and the variable-thickness gear wheel 10 are both involute helical tooth variable-thickness gears, the thickness of the gear teeth (or the width of the gear groove) gradually increases or decreases along the axial direction, forming a taper or wedge structure, and the change is a nonlinear change with a taper angle of 1°~5°. The variable-thickness pinion 8 is connected with the planet carrier 6 through a screw, the variable-thickness gear wheel 10 is connected with the output flange 15 through a hexagonal tapered head screw, a gasket with a specified thickness is installed between the variable-thickness gear wheel 10 and the deep groove ball bearing 13, the thickness of the gasket is adjusted to change the axial position of the variable-thickness gear wheel, thereby changing the actual meshing position of the variable-thickness gear pair and adjusting the side clearance of the transmission mechanism. The variable-thickness gear wheel is fixed and supported by the deep groove ball bearing 13 and the lower shell 1, and the deep groove ball bearing 13 is a full ball bearing with high rigidity and carrying capacity. At the same time, a sealing cover 11 and a rotating shaft lip seal ring 14 are respectively installed on the variable-thickness gear wheel to ensure the sealing performance of the cavity.

[0036] As shown in Figure 1 , Figure 6 and Figure 7As shown, the output flange 15 is connected with an external load (for example, a robot arm) through the mounting hole provided thereon. In the embodiment of the present application, the mounting hole of the output flange 15 is provided on the side surface thereof, and the axis direction of the mounting hole is perpendicular to the rotation axis direction of the variable-thickness large gear 10 and the output flange 15. The rotation of the servo motor 2 is transmitted through the three-stage transmission mechanism, so that the output flange rotates around the axis thereof, and the connected external load swings with the rotation of the output flange. The top of the output flange 15 is connected with the variable-thickness large gear 10 through the screw 12, and the bottom is connected with the output flange bearing end cover 16 through the screw. The support bearing 17 and the deep groove ball bearing 13 ensure the support rigidity of the output flange, the end cover and the variable-thickness large gear, and the good rotation precision of the output flange. The mounting hole end surface of the output flange is provided with a mark hole, which is used for the initial zero positioning in the robot program setting. The mounting hole end surface of the output flange is designed with circumferentially distributed screw holes, which are connected with the external load through the screws.

[0037] In a specific embodiment of the present application, the upper shell 9 and the lower shell 1 are made of aluminum alloy, and the output flange 15 is made of spheroidal cast iron. The three are formed by sand casting, and the surface is subjected to anodic oxidation and paint spraying processes to improve the corrosion resistance and aesthetic appearance. The end surfaces of the upper shell and the lower shell are coated with oil and sealed with end surface rubber, and are fixed by the screws and the end surface sealing rubber. The parallelism of the center lines of the mounting hole of the needle gear shell 5 and the mounting hole of the deep groove ball bearing 13 on the lower shell 1 is ensured to be 0.01 mm, so as to ensure the good assembly precision and transmission precision of the system.

[0038] Test and repeatability verification of the transmission mechanism of the present application:

[0039] a Preparation work

[0040] 1) All measuring instruments should be within the valid period of verification and meet the accuracy requirements.

[0041] 2) The measured high-precision transmission device (also referred to as the measured gear box in the present application) and the sensor are installed according to the provisions, and the instrument should be self-calibrated before measurement.

[0042] b Test method

[0043] Figure 8 The schematic diagram of the test system of the high-precision transmission device in the embodiment; according to the scheme shown, Figure 8 the high-precision transmission device 21 shown in Figure 8 is a top view of the high-precision transmission device 21, that is, Figure 7The arrow direction is shown. The test platform 19 is provided with a bench 20 for fixing the high-precision transmission device 21 of the application. The hydraulic jack 26 is loaded and unloaded to the output flange 15 through the tool loading disc 25 and the tool loading rod 23. The bending moment in the loading process is measured through the pressure sensor 24. The inclination sensor 22 measures the inclination of the output flange and the distributed shell in the loading process, respectively. The bending moment and the inclination are recorded in the experiment process to generate the hysteresis curve.

[0044] After the static loading experiment test is completed, the jack is disassembled, the high-precision transmission device is started to move with load for dynamic test, and the repeated positioning accuracy of the output end is measured through the laser tracker.

[0045] c Data processing

[0046] According to the collected data, the hysteresis curve of the measured high-precision transmission device is drawn on the torque and rotation angle coordinate plane through the least square method as shown in the figure. Figure 9 The torsional stiffness and backlash of the transmission device are calculated. The absolute value of the rotation angle difference of the midpoint of the two groups of intersection points of the hysteresis curve at ±3% rated torque is the backlash. The difference between the inclinations at the torque "zero" of the hysteresis curve is the backlash.

[0047] From the hysteresis curve, the transmission device can keep the stroke and backlash within 1 arc. min. Figure 9

[0048] The repeated positioning accuracy of the gear transmission device is shown in the figure. The one-way repeated positioning accuracy is between 0.03 mm and 0.05 mm, and the two-way repeated positioning accuracy is between 0.05 mm and 0.07 mm. Figure 10

[0049] The experimental data show that the high-precision transmission device can ensure good overall performance and excellent overall transmission accuracy.

[0050] The above-described embodiments only express several embodiments of the application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent of the application. For ordinary skilled in the art, without departing from the concept of the application, a number of modifications and improvements can be made, which are within the protection scope of the application.​​

Claims

1. A high-precision transmission device, characterized in that, It includes a split housing and an involute planetary gear transmission mechanism, a cycloidal pinwheel transmission mechanism, and a variable tooth thickness gear transmission mechanism integrated within the split housing and sequentially connected in transmission. The sun gear of the involute planetary gear transmission mechanism is interference-fitted with the input motor, and its planet gears are splined to the camshaft of the cycloidal pinwheel transmission mechanism, with a speed ratio range of 40 to 200. The cycloidal pinwheel transmission mechanism adopts a symmetrical layout design of two cycloidal wheels with a phase difference of 180°. It is driven eccentrically by a camshaft, and the tooth profile of the cycloidal wheel meshes with the pin teeth fixed on the pin tooth housing. The rotation of the cycloidal wheel is transmitted to the variable tooth thickness small wheel through the planetary carrier. The variable tooth thickness gear transmission mechanism includes a variable tooth thickness pinion and a variable tooth thickness large gear. The tooth thickness of the pinion and large gear varies non-linearly along the axial direction, with a cone angle of 1° to 5°. The variable tooth thickness large gear is mounted on a split housing via a deep groove ball bearing. An adjustable shim is provided axially between the variable tooth thickness large gear and the deep groove ball bearing. The axial meshing position is changed by adjusting the thickness of the shim to control the backlash. The variable tooth thickness large gear is connected to the output flange.

2. The high-precision transmission device according to claim 1, characterized in that, The split housing includes an upper housing and a lower housing. The lower housing contains a transmission mechanism cavity, an input motor mounting cavity, and an output flange mounting cavity for mounting an involute planetary gear transmission mechanism, a cycloidal pinwheel transmission mechanism, and a variable tooth thickness gear transmission mechanism. The transmission mechanism cavity is located at the top of the lower housing and is closed by the upper housing.

3. The high-precision transmission device according to claim 2, characterized in that, The involute planetary gear transmission mechanism, the cycloidal pinwheel transmission mechanism, and the variable tooth thickness small gear are coaxially mounted on one side of the transmission mechanism cavity from bottom to top, while the variable tooth thickness large gear is mounted on the other side of the transmission mechanism cavity and meshes with the variable tooth thickness small gear. The input motor mounting cavity is used to mount the input motor, which is located below the transmission mechanism cavity. The bottom of the transmission mechanism cavity has an input end opening, and the output shaft of the input motor passes through the input end opening to connect with the sun gear of the involute planetary gear transmission mechanism. The output flange mounting cavity is located below the variable tooth thickness large gear, and an output flange is installed inside it.

4. The high-precision transmission device according to claim 1, characterized in that, The involute planetary gear transmission mechanism has three planetary gears, with the sun gear meshing with the three planetary gears for transmission. The backlash between the sun gear and the planetary gears is controlled between 0.02 mm and 0.08 mm.

5. The high-precision transmission device according to claim 1, characterized in that, The cycloidal pinwheel transmission mechanism is fixed to the lower housing by axially equally spaced hexagonal head screws. The cycloidal pinwheel transmission mechanism balances the radial force and improves the load-bearing capacity through the eccentric drive of the camshaft and needle roller bearing. The camshaft is circumferentially fixed to the planetary carrier through tapered roller bearings. The pin tooth housing is connected to the planetary carrier by paired crossed roller bearings or angular contact bearings to ensure good output rigidity of the cycloidal pinwheel transmission mechanism.

6. The high-precision transmission device according to claim 1, characterized in that, The cycloidal pinwheel transmission mechanism has a cycloidal tooth profile that is a short-amplitude standard epicycloidal curve. Through the composite shaping of the tooth tip and tooth root, the number of teeth meshing simultaneously in the circumferential direction is 4 to 10.

7. The high-precision transmission device according to claim 1, characterized in that, The variable tooth thickness small gear is fixed to the planetary carrier by screws, and the variable tooth thickness large gear is connected to the output flange by hexagonal head screws.

8. The high-precision transmission device according to claim 1, characterized in that, The deep groove ball bearing is a full complement ball bearing that supports the large gear with variable tooth thickness and is fixed to the lower housing; the output flange is fixed coaxially with the deep groove ball bearing through a support bearing.

9. The high-precision transmission device according to claim 8, characterized in that, The pin tooth housing of the cycloidal pinwheel transmission mechanism is horizontally set in the cavity of the transmission mechanism through the pin tooth housing mounting hole, and the deep groove ball bearing is horizontally set in the cavity of the transmission mechanism through the deep groove ball bearing mounting hole; the parallelism between the pin tooth housing mounting hole and the deep groove ball bearing mounting hole is ≤0.01mm.

10. The high-precision transmission device according to claim 1, characterized in that, The high-precision transmission device has a backlash of ≤1 arc minute and a bidirectional repeatability of 0.05mm~0.07mm.

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