A rotary worktable based on planetary gear reducer

Abstract

In order to solve the problems of high cost, low transmission efficiency, large size, and transmission backlash in the existing technical solutions, the present invention proposes a rotary worktable based on a planetary gear reducer. The rotary worktable provided by the present invention has the following characteristics: when there is only a C-axis, the C-axis turntable motor is not installed on the C-axis turntable, which reduces the turntable volume and leaves a more flexible machine tool workspace; when a cradle (C-axis + A-axis) structure is added, because the C-axis turntable motor is not installed on the C-axis turntable, the A-axis load is reduced, thereby increasing the effective power of the A-axis; at the same time, the present invention also uses precision planetary gears for deceleration, which has higher transmission rigidity and stronger load inertia adaptability than the direct drive motor solution; and it has higher efficiency and higher power density than the worm gear pair solution.

Description

Technical Field

[0001] The invention relates to a rotary worktable, in particular to a rotary worktable based on a planetary gear reducer. Background Art

[0002] At present, there are three common design schemes for rotary worktables: direct-drive torque motor scheme, worm gear reduction scheme, and gear reduction scheme. The following describes the three schemes in detail:

[0003] 1] Direct drive motor solution

[0004] As a representative of direct-drive motors: Siemens direct-drive torque motors generally use high-precision circular gratings for full closed-loop feedback in position control, and imported table bearings are used for table support. Although the accuracy is guaranteed, the cost of purchased parts is very high. In addition, the motor directly faces the workbench and workpiece inertia, and its inertia is difficult to match. The electromechanical coupling system is prone to instability, and different load inertias require multiple sets of electrical parameter matching.

[0005] 2] Worm gear reduction scheme

[0006] The advantages of this solution are that, due to its relatively large reduction ratio, the load inertia has little impact on the motor. However, its transmission efficiency is low, typically only 60%, and it is prone to thermal deformation and is difficult to manufacture. Furthermore, because the worm's circumferential speed cannot exceed 5 m / sec, small-diameter worms lack drive stiffness, while large-diameter worms cannot achieve the required high output speeds. Furthermore, a single worm gear pair cannot eliminate transmission backlash, and to do so would require a complex dual-worm gear structure, which is both difficult and costly to manufacture.

[0007] 3] Involute gear reduction scheme

[0008] Hardened involute gears, which have undergone profile modification and precision grinding, offer advantages such as high precision, high transmission efficiency, insensitivity to center distance accuracy, and adaptability to high, medium, and low speeds. They are widely used in various transmission mechanisms. However, due to manufacturing errors and other factors, backlash-free transmission cannot be achieved with a single transmission element. Instead, a single gear meshing with two gears equipped with tangential tension springs for backlash elimination is typically employed. This results in limited backlash-eliminating torque and cannot support high torque loads.

[0009] Especially for the C-axis rotary table, the existing C-axis rotary table is too large because the motor and reducer parts are both arranged on the C-axis rotary table, which not only increases the unidirectional load of the rotary table, but also greatly compresses the working space of the machine tool and limits the working range.

[0010] In addition, in the cradle (C-axis + A-axis turntable) structure, the C-axis motor and reducer are both installed on the turntable, which increases the A-axis load and reduces the effective power of the A-axis. Summary of the Invention

[0011] In order to solve the problems of high cost, low transmission efficiency, large volume, transmission backlash and the like in the above technical solutions, the present invention proposes a rotary worktable based on a planetary gear reducer.

[0012] The specific technical solutions of the present invention are as follows:

[0013] The planetary gear reducer-based rotary table includes a C-axis mechanism;

[0014] The C-axis mechanism includes a C-axis turntable surface, a horizontal turntable, a C-axis motor and an L-shaped turntable base; the L-shaped turntable base includes a horizontal base and a vertical wall panel, and the vertical wall panel is arranged on one side of the horizontal base; the horizontal turntable is fixedly arranged on the horizontal base; the C-axis motor is fixedly arranged on the vertical wall panel, and the output end of the C-axis motor is connected to the first bevel gear; the horizontal turntable includes a second bevel gear, a first gear, a second gear, a C-axis planetary gear reducer and a turntable surface that are power-connected in sequence; the C-axis planetary gear reducer includes a sun gear, a planetary gear, a planetary carrier and a planetary shaft; the first bevel gear is vertically meshed with the second bevel gear, the first gear and the second gear are horizontally meshed and reduce speed, the second gear rotates coaxially with the sun gear of the C-axis planetary gear reducer, and the planetary carrier of the C-axis planetary gear reducer is fixedly connected to the C-axis turntable surface, that is, the C-axis motor arranged on the vertical wall panel transmits power to the horizontal turntable.

[0015] Furthermore, the planetary gear reducer-based rotary table further includes an A-axis mechanism;

[0016] The A-axis mechanism includes a vertical turntable, an A-axis motor and an A-axis turntable base; the vertical turntable is fixedly connected to the C-axis mechanism for providing a cradle action to the C-axis mechanism; an A-axis planetary gear reducer is arranged in the A-axis turntable base, and the A-axis planetary gear reducer includes an inner gear housing and a high-speed planetary gear reduction mechanism, N medium-speed planetary gear reduction mechanisms and a low-speed planetary gear reduction mechanism arranged in sequence along the axial direction of the inner gear housing, N≥0, and the high-speed, medium-speed and low-speed planetary gear reduction mechanisms all include a sun gear, a planetary gear, a planetary carrier and a planetary shaft; the high-speed sun gear of the high-speed planetary gear reduction mechanism is fixedly connected to the output shaft of the A-axis motor, the A-axis turntable surface is fixedly connected to the low-speed planetary carrier, and the A-axis motor transmits power to the A-axis turntable surface through the A-axis planetary gear reducer.

[0017] Furthermore, a speed measuring unit for measuring the output speed is provided on the low-speed planetary carrier of the A-axis mechanism. The speed measuring unit is used to transmit the real-time position of the low-speed planetary carrier back to the motor control unit, and the motor control unit adjusts the output of the motor according to the real-time position.

[0018] Furthermore, the rotation speed measurement unit includes a magnetic grating disk fixedly connected to the low-speed planetary carrier, a reading head for reading the position of the magnetic grating disk through contact, and a cable for transmitting information read by the reading head.

[0019] Furthermore, the planetary gear reducer adopts a planetary gear mechanism without backlash.

[0020] Furthermore, the high-speed sun gear of the high-speed planetary gear reduction mechanism is fixedly connected to the output shaft of the A-axis motor through a coupling sleeve, the high-speed sun gear is meshed with the high-speed planetary gear, the high-speed planetary gear is connected to the high-speed planetary carrier through a high-speed planetary shaft, and the high-speed planetary carrier is fixedly sleeved on the intermediate-speed sun gear of the adjacent next intermediate-speed planetary gear reduction mechanism; the intermediate-speed sun gear is a segmented structure, and the segmented structure includes a driving section and a transmission section, the driving section is sleeved with the planetary carrier of the previous reduction mechanism, and the transmission section is meshed with the planetary gear of the adjacent next reduction mechanism; the structure is repeated until it is meshed with the low-speed sun gear of the low-speed planetary gear reduction mechanism.

[0021] Furthermore, the A-axis motor is connected to the A-axis turntable base, and the sun gear of the high-speed planetary gear reduction mechanism is fixed to the coupling sleeve by the interference fit of the pin shaft; a sleeve is provided between the low-speed planetary carrier and the turntable surface for making the low-speed planetary carrier coaxial with the turntable surface, and the sleeve is interference fit with the low-speed planetary carrier.

[0022] Furthermore, the driving section and transmission section of the medium-speed sun gear are both gear structures, the tooth height of the driving section is smaller than the tooth height of the transmission section, the driving section gear is meshed with the planetary carrier of the previous stage reduction mechanism and is fixed by a key to achieve socket connection, the end face of the previous stage planetary carrier is in contact with the end face of the outer tooth of the transmission section on the current stage sun gear, and at the same time forms a micro gap with the end face of the current stage planetary gear.

[0023] Furthermore, N rows of balls and N rows of raceways are arranged between the low-speed planetary carrier and the inner gear housing, N is a natural number, and N≥1; the raceway cross-section includes at least one arc that does not coincide with the center of the cross-section; the raceway is composed of an outer ring inner raceway arranged on the inner gear housing and an inner ring outer raceway arranged on the planetary carrier.

[0024] Furthermore, the planet carriers and planetary wheels of the high-speed planetary gear reduction mechanism, the medium-speed planetary gear reduction mechanism or the low-speed planetary gear reduction mechanism are connected via planetary shafts, and contact ball bearings are provided between the planetary shafts and the planetary wheels.

[0025] The advantages of the present invention are:

[0026] 1. The present invention provides a rotary worktable for a planetary gear reducer. When there is only a C-axis, the C-axis turntable motor is not installed on the C-axis turntable, thereby reducing the turntable volume and leaving a more flexible machine tool workspace; when a cradle (C-axis + A-axis) structure is added, since the C-axis turntable motor is not installed on the C-axis turntable, the A-axis load is reduced, so that the effective power of the A-axis is improved; at the same time, the present invention also uses precision planetary gears for deceleration, which has higher transmission rigidity and stronger load inertia adaptability than the direct-drive motor solution; it has higher efficiency and greater power density than the worm gear pair solution.

[0027] 2. In the preferred embodiment of the rotary worktable provided by the present invention, a self-made output-end multi-point contact ball bearing method is adopted. This bearing type can not only bear radial loads, but also axial loads. Compared with the structure of the existing reducer, it greatly improves the reducer's carrying capacity for axial and bending loads; at the same time, the contact ball bearing structure adopts an axial hole, a ball filling hole and an anti-escape structure to form a filling structure, which avoids the problem of splicing gaps that are inevitably generated by the upper and lower splicing structures, thereby improving the manufacturing precision, effectively ensuring the raceway stiffness, and reducing the wear of the balls in the raceway caused by the splicing raceway gaps.

[0028] 3. In the preferred embodiment of the rotary worktable provided by the present invention, the reducer axially positions the planetary gears of the first-stage planetary gear reduction mechanism by adopting the connection structure (coupling sleeve) between the motor and the planetary reducer, the current-stage planetary carrier axially positions the planetary gear bearings, and the upper-stage planetary carrier axially positions the planetary gear through the transmission section of the lower-stage sun gear. At the same time, the planetary gears and the planetary carrier of the same stage are in direct contact to achieve mutual axial positioning. Compared with the existing reducer structure, the structure of the present invention not only shortens the overall axial size of the planetary gear reducer, but also reduces the features and quantity of parts, thereby reducing manufacturing costs.

[0029] 4. In the preferred embodiment of the rotary worktable provided by the present invention, a micro-gap is formed between the end face of the upper-stage planetary carrier and the end face of the current-stage planetary gear in the adjacent two-stage planetary gear reduction mechanism. This can provide space for grease while assuming the axial positioning function, thereby establishing an oil film between the contact surfaces, improving lubrication and reducing wear. At the same time, it also increases manufacturing tolerance and reduces manufacturing difficulty.

[0030] 5. In the preferred embodiment of the rotary table provided by the present invention, a planetary gear mechanism with no backlash is provided, so that the rotary table can achieve the effect of eliminating backlash, thereby allowing full closed-loop control feedback to be used without worrying about oscillation problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a front view of the C-axis mechanism of the present invention;

[0032] Figure 2 A left side view of the C-axis mechanism of the present invention;

[0033] Figure 3 The front view of the cradle (A axis + C axis) structure of the present invention;

[0034] Figure 4 A top view of the structure of the cradle (A axis + C axis) of the present invention;

[0035] The attached drawings are as follows:

[0036] 41-horizontal turntable, 42-C-axis motor, 43-L-type turntable base, 44-C-axis turntable surface, 431-horizontal base, 432-vertical wall panel, 45-first bevel gear, 46-second bevel gear, 47-first gear, 48-second gear, 49-C-axis planetary gear reducer (491-sun gear, 492-planetary gear, 493-planet carrier, 494-planetary shaft, 495-inner gear housing), 61-coupling sleeve; 62-connecting shaft; 63-connecting shaft.

[0037] 31-vertical turntable, 32-A-axis motor, 33-A-axis turntable base, 34-inner gear housing, 35-high-speed planetary gear reduction mechanism, 36-medium-speed planetary gear reduction mechanism, 37-low-speed planetary gear reduction mechanism. DETAILED DESCRIPTION

[0038] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0039] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0040] In the description of the present invention, it should be noted that the terms "upper, lower, inner, and outer" and other references to orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first, second, or third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] Unless otherwise specified or limited, the terms "mounted, connected, and connected" in this disclosure should be understood broadly. For example, they may refer to fixed, removable, or integral connections. They may also refer to mechanical, electrical, or direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure.

[0042] The present invention provides two major types of rotary worktables, namely: a simple C-axis rotary worktable and a cradle-structured rotary worktable composed of an A-axis + C-axis rotary worktable, which are described below through two embodiments.

[0043] Example 1

[0044] like Figure 1 、 Figure 2 As shown, the rotary table based on the planetary gear reducer includes a C-axis mechanism;

[0045] The C-axis mechanism includes a horizontal turntable 41, a C-axis motor 42 and an L-shaped turntable base 43; the L-shaped turntable base 43 includes a horizontal base 431 and a vertical wall plate 432, and the vertical wall plate 432 is arranged on one side of the horizontal base 431; the horizontal turntable 41 is fixedly arranged on the horizontal base 431; the C-axis motor 42 is fixedly arranged on the vertical wall plate 432, and the output end of the C-axis motor 42 is connected to the first bevel gear 45; the horizontal turntable 41 includes a second bevel gear 46, a first gear 47, a second gear 48, a C-axis planetary gear reducer, which are connected in sequence. 49 and the C-axis turntable surface 44; the C-axis planetary gear reducer includes a sun gear 491, a planetary gear 492, a planetary carrier 493, a planetary shaft 494 and an inner gear housing 495; the first bevel gear is vertically meshed with the second bevel gear 46, the first gear 47 and the second gear 48 are horizontally meshed and reduce speed, the second gear 48 rotates coaxially with the sun gear 491 of the C-axis planetary gear reducer 49, and the planetary carrier 493 of the C-axis planetary gear reducer 49 is fixedly connected to the C-axis turntable surface, that is, the C-axis motor 42 arranged on the vertical wall panel 432 transmits power to the horizontal turntable 41.

[0046] Taking into account the specific working conditions, since the output shaft of the C-axis motor 42 needs to be reversed for power transmission, the output length can be extended by cooperating with the coupling sleeve 61 and the connecting shaft 62, and then connected to the first bevel gear 45 through the connecting shaft 62.

[0047] During operation, the C-axis motor 42 is started, and the output shaft of the C-axis motor 42 rotates, driving the coupling sleeve 61 to rotate, thereby driving the connecting shaft 62 to rotate, and the first bevel gear 45 connected to the end of the connecting shaft 62 starts to rotate along with the connecting shaft 62, and the first bevel gear 45 transmits the power to the second bevel gear 46, completing the first 90° reversal of power transmission; after the second bevel gear 46 rotates, it drives its connecting shaft 63 to rotate, and the first gear 47 at the other end of the connecting shaft 63 rotates coaxially therewith, thereby driving the second gear 48 engaged with it in the horizontal direction to rotate. The diameter of the first gear 47 is smaller than the diameter of the second gear 48, thereby completing the first deceleration. The deceleration ratio can be achieved by adjusting the diameter ratio of the two.

[0048] Since the second gear 48 is coaxially connected to the C-axis planetary gear reducer 49, the second gear 48 transmits power to the C-axis planetary gear reducer 49. Specifically, the second gear 48 is coaxially connected to the sun gear 491 of the C-axis planetary gear reducer 49, driving the sun gear 491 to rotate. After the sun gear 491 rotates, it drives the planetary gear 492 engaged with it to connect. The planetary gear 492 then transmits power to the planetary carrier 493 through the planetary shaft 494. The planetary carrier 493 is fixedly connected to the C-axis turntable surface, thereby driving the C-axis turntable surface to rotate, completing power transmission.

[0049] The sun gear 491, planetary gears 492, planet carrier 493, and planetary shaft 494 of the C-axis planetary gear reducer 49 are housed within a cavity formed by the base housing, inner gear housing, and C-axis turntable of the C-axis planetary gear reducer 49. A multi-point contact bearing structure is formed between the inner gear housing and planet carrier 493 of the C-axis planetary gear reducer 49. Specifically, at least one set of raceways is positioned opposite the inner gear housing and planet carrier 493, with corresponding balls embedded within the raceways. The inner raceway outer raceway and the outer raceway inner raceway each consist of two non-concentric arcs. This means that regardless of the direction of force applied, the inner raceway walls contact the balls at at least four points, achieving multi-point support and increasing the bearing's tolerable torque. This structure can also be applied between the planetary gears 492 and planetary shaft 494 to further enhance stability.

[0050] Example 2

[0051] like Figure 3 、 Figure 4 As shown, the rotary table based on the planetary gear reducer includes an A-axis mechanism and a C-axis mechanism;

[0052] The C-axis mechanism is the same as that in Example 1. This embodiment adds a cradle, namely, an A-axis mechanism, to the C-axis mechanism.

[0053] The A-axis mechanism is located on the opposite side of the C-axis motor 42 .

[0054] The A-axis mechanism includes a vertical turntable 31, an A-axis motor 32, and an A-axis turntable base 33; the vertical turntable 31 is fixedly connected to the horizontal turntable 41 of the C-axis mechanism (and in this example, the horizontal turntable 41 of the C-axis mechanism is no longer fixedly connected to the horizontal base 431), and is used to provide a cradle action for the C-axis mechanism. When the A-axis motor 32 drives the vertical turntable 31 to perform the cradle action, the horizontal base 431 and the vertical wall panel 432 of the L-shaped turntable base 43 remain stationary, and the transmission chain from the C-axis motor 42 to the horizontal turntable 41 performs the cradle action relative to the L-shaped turntable base 43; an A-axis planetary gear reducer is provided in the A-axis turntable base 33. The A-axis planetary gear reducer includes an inner gear housing 34 and a high-speed planetary gear reduction mechanism 35, a medium-speed planetary gear reduction mechanism 36 and a low-speed planetary gear reduction mechanism 37 arranged in sequence along the axial direction of the inner gear housing 34. The high-speed, medium-speed and low-speed planetary gear reduction mechanisms all include a sun gear, planetary gears, a planetary carrier and a planetary shaft; the high-speed sun gear of the high-speed planetary gear reduction mechanism is fixedly connected to the output shaft of the A-axis motor 32, the back side of the A-axis turntable is fixedly connected to the low-speed planetary carrier, the A-axis motor 32 transmits power to the A-axis turntable through the A-axis planetary gear reducer, and the turntable on the other side of the A-axis is fixedly connected to the C-axis mechanism.

[0055] During movement, the A-axis mechanism controls the C-axis mechanism to achieve a swinging motion, that is, it rotates left and right with the output shaft center of the A-axis motor 32 as the center point. The specific movement process is: the output shaft of the A-axis motor 32 transmits power to the sun gear of the high-speed planetary gear reduction mechanism 35 through the coupling sleeve, the sun gear of the high-speed planetary gear reduction mechanism 35 rotates to drive the planetary gears of the high-speed planetary gear reduction mechanism 35 to rotate, the planetary gears of the high-speed planetary gear reduction mechanism 35 drive the planetary carrier to rotate through the planetary shaft, the planetary carrier of the high-speed planetary gear reduction mechanism 35 is meshed with the sun gear of the medium-speed planetary gear reduction mechanism 36, and the number of medium-speed planetary gear reduction mechanisms 36 can be adjusted according to the reduction ratio and actual application occasions, N ≥ 0, also That is to say, in extreme cases, only high-speed and low-speed planetary gear reduction mechanisms 37 can be set; the medium-speed sun gear is a segmented structure, which includes a driving section and a transmission section. The driving section is connected to the planetary carrier of the upper-stage reduction mechanism, and the transmission section is engaged with the planetary gear of the adjacent lower-stage reduction mechanism; the structure is repeated until it is engaged with the low-speed sun gear of the low-speed planetary gear reduction mechanism to realize power transmission, and the low-speed sun gear also transmits power to the planetary carrier through its planetary gears and planetary shafts, and the low-speed planetary carrier is directly fixedly connected to the C-axis mechanism to realize deceleration and control output.

[0056] The low-speed planetary carrier is also equipped with a speed measurement unit for measuring the output speed. This unit transmits the real-time position of the low-speed planetary carrier back to the motor control unit, which then adjusts the motor output based on the real-time position. Preferably, the speed measurement unit includes a magnetic grating fixedly connected to the low-speed planetary carrier, a readhead that reads the magnetic grating position by contact, and a cable for transmitting the information read by the readhead. Specifically, data obtained by the readhead is transmitted via the cable back to the CNC or drive for fully closed-loop control.

[0057] The following further describes the similar / identical parts between the A-axis mechanism and the C-axis mechanism.

[0058] Considering practical applications, the specific structure of the planetary reducer can be preferably a planetary gear mechanism with no backlash. This mechanism has been disclosed in 201810790333.7. This structure can reduce or completely eliminate the backlash of the planetary gear transmission device by eliminating the side clearance and bearing clearance in the gear meshing, greatly improving the precision of the planetary reduction mechanism. In addition, this structure does not add any other components, which greatly reduces the weight and volume of the rotary worktable.

[0059] It should be understood that the above-mentioned embodiments are merely illustrative and non-restrictive. Without departing from the basic principles of the present invention, various obvious or equivalent modifications or substitutions that can be made by those skilled in the art to the above-mentioned details will be included in the scope of the claims of the present invention.

Claims

1. A rotary table based on a planetary gear reducer, including a C-axis mechanism; Its characteristics are: Also includes A-axis mechanism; The C-axis mechanism includes a horizontal turntable, a C-axis motor and an L-shaped turntable base; The L-shaped turntable base includes a horizontal base and a vertical wall panel, and the vertical wall panel is arranged on one side of the horizontal base; The horizontal turntable is fixedly arranged on a horizontal base; The C-axis motor is fixedly mounted on the vertical wall plate, and the output end of the C-axis motor is connected to the first bevel gear; The horizontal turntable includes a second bevel gear, a first gear, a second gear, a C-axis planetary gear reducer and a C-axis turntable surface that are sequentially connected in power; the C-axis planetary gear reducer includes a sun gear, planetary gears, a planetary carrier and a planetary shaft; The first bevel gear is vertically meshed with the second bevel gear, the first gear and the second gear are horizontally meshed and reduce speed, the second gear rotates coaxially with the sun gear of the C-axis planetary gear reducer, and the planet carrier of the C-axis planetary gear reducer is fixedly connected to the C-axis turntable surface, that is, the C-axis motor set on the vertical wall panel transmits power to the horizontal turntable; The A-axis mechanism includes a vertical turntable, an A-axis motor and an A-axis turntable base; The vertical turntable is fixedly connected to the C-axis mechanism and is used to provide a cradle action to the C-axis mechanism; An A-axis planetary gear reducer is arranged in the A-axis turntable base, and the A-axis planetary gear reducer includes an inner gear housing and a high-speed planetary gear reduction mechanism, N medium-speed planetary gear reduction mechanisms and a low-speed planetary gear reduction mechanism arranged in sequence along the axial direction of the inner gear housing, N ≥ 0, and the high-speed, medium-speed and low-speed planetary gear reduction mechanisms all include a sun gear, planetary gears, a planet carrier and a planetary shaft; the high-speed sun gear of the high-speed planetary gear reduction mechanism is fixedly connected to the output shaft of the A-axis motor, the A-axis turntable surface is fixedly connected to the low-speed planet carrier, and the A-axis motor transmits power to the A-axis turntable surface through the A-axis planetary gear reducer; The medium-speed sun gear is a segmented structure, which includes a driving section and a transmission section. The driving section is socketed with the planetary carrier of the previous stage reduction mechanism, and the transmission section is meshed with the planetary gear of the adjacent next stage reduction mechanism; the structure is repeated until it is meshed with the low-speed sun gear of the low-speed planetary gear reduction mechanism; the driving section and the transmission section of the medium-speed sun gear are both gear structures, the tooth height of the driving section is smaller than the tooth height of the transmission section, the driving section gear is meshed with the planetary carrier of the previous stage reduction mechanism and is socketed by key fixation, the end face of the previous stage planetary carrier is in contact with the end face of the outer tooth of the transmission section on the current stage sun gear, and at the same time forms a micro gap with the end face of the current stage planetary gear.

2. The rotary worktable based on the planetary gear reducer according to claim 1, characterized in that: The low-speed planetary carrier is provided with a speed measuring unit for measuring the output speed. The speed measuring unit is used to transmit the real-time position of the low-speed planetary carrier back to the motor control unit, and the motor control unit adjusts the output of the motor according to the real-time position.

3. The rotary worktable based on the planetary gear reducer according to claim 2, characterized in that: The rotation speed measuring unit includes a magnetic grating disk fixedly connected to the low-speed planet carrier, a reading head for reading the position of the magnetic grating disk through contact, and a cable for transmitting information read by the reading head.

4. The rotary worktable based on the planetary gear reducer according to claim 3, characterized in that: The high-speed sun gear of the high-speed planetary gear reduction mechanism is fixedly connected to the output shaft of the A-axis motor through a coupling sleeve, the high-speed sun gear is meshed with the high-speed planetary gear, the high-speed planetary gear is connected to the high-speed planetary carrier through the high-speed planetary shaft, and the high-speed planetary carrier is fixedly sleeved on the medium-speed sun gear of the adjacent next medium-speed planetary gear reduction mechanism.

5. The rotary worktable based on the planetary gear reducer according to claim 4, characterized in that: The A-axis motor is connected to the A-axis turntable base, and the sun gear of the high-speed planetary gear reduction mechanism is fixed on the coupling sleeve by the interference fit of the pin shaft; a shaft sleeve is provided between the low-speed planetary carrier and the turntable surface to make the low-speed planetary carrier coaxial with the turntable surface, and the shaft sleeve is interference fit with the low-speed planetary carrier.

6. The rotary worktable based on the planetary gear reducer according to claim 5, characterized in that: N rows of balls and N rows of raceways are arranged between the low-speed planetary carrier and the inner gear housing, where N is a natural number and N≥1; the raceway cross section includes at least one arc that does not coincide with the center of the cross section; the raceway is composed of an outer ring inner raceway arranged on the inner gear housing and an inner ring outer raceway arranged on the planetary carrier.

7. The rotary worktable based on the planetary gear reducer according to claim 6, characterized in that: The planet carriers and planetary wheels of the high-speed planetary gear reduction mechanism, the medium-speed planetary gear reduction mechanism or the low-speed planetary gear reduction mechanism are connected via planetary shafts, and contact ball bearings are provided between the planetary shafts and the planetary wheels.

8. The rotary worktable based on a planetary gear reducer according to any one of claims 1 to 7, characterized in that: The planetary gear reducer adopts a planetary gear mechanism without backlash.

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