rotary table

Abstract

In order to solve the problems of cost, transmission efficiency, transmission backlash and the like in the prior art, the present application provides a rotary table using a precision planetary gear reducer. The rotary table provided by the present application adopts precision planetary gear reduction, and has higher transmission rigidity and stronger load inertia adaptability than the direct drive motor scheme; and has higher efficiency and greater power density than the worm pair scheme. In the preferred scheme of the rotary table provided by the present application, a self-made output end multi-point contact ball bearing mode is adopted, and the multi-point contact ball bearing structure has higher manufacturing precision, stronger bearing capacity, higher rigidity and higher transmission precision than the cylindrical needle bearing adopted by the existing planetary wheel bearing; meanwhile, the multi-point contact ball bearing structure can be preloaded to eliminate bearing play, thereby reducing the reverse backlash of the reducer.

Description

TECHNICAL FIELD

[0001] The present application relates to a rotary table, in particular to a high-precision numerical control rotary table. BACKGROUND

[0002] At present, the design schemes of common rotary tables are divided into three kinds, which are direct drive torque motor scheme, worm pair reduction scheme and gear reduction scheme, and the three schemes will be specifically explained as follows:

[0003] 1】Direct drive motor scheme

[0004] As a representative of the direct drive motor: the position control of the Siemens direct drive torque motor generally adopts high-precision circular grating for full closed loop feedback, and the table surface support adopts imported table surface bearing. Although the precision is guaranteed, the cost of the purchased parts is very high, and the inertia of the motor directly faces the table and the workpiece inertia, which is not easy to match, and the electromechanical coupling system is easy to be unstable, and different load inertia needs to be matched with multiple sets of electrical parameters.

[0005] 2】Worm pair reduction scheme

[0006] The advantages of this scheme are that the load inertia has less effect on the motor due to the large reduction ratio, but the transmission efficiency is low, generally only 60%, and thermal deformation is easy to occur, and the manufacturing difficulty is great. In addition, because the circular peripheral speed of the worm cannot exceed 5 m / sec, the driving stiffness of the small diameter worm is not enough, and the large diameter worm cannot meet the requirement of high output speed. In addition, the single worm pair structure cannot eliminate the transmission backlash, and in order to eliminate the transmission backlash, a complex double worm structure is required, which has high manufacturing difficulty and cost.

[0007] 3】Involute gear reduction scheme

[0008] The involute gear with hard tooth surface designed and precisely ground has the advantages of high precision, high transmission efficiency, not sensitive to center distance precision, and can adapt to high, medium and low speed requirements, etc. It is widely used in various transmission mechanisms. However, the single transmission element cannot achieve backlash-free transmission due to manufacturing errors, and a single gear and two gears with tangential spring backlash gears are generally used to mesh, which has limited backlash torque and cannot bear large torque load. SUMMARY

[0009] In order to solve the problems of cost, transmission efficiency, transmission backlash and the like in the above technical schemes, the present application proposes a rotary table using a precision planetary gear reducer.

[0010] The specific technical solution of the present application is as follows:

[0011] The rotary table comprises a motor, a rotary table base, a rotary table surface, and a planetary gear reducer arranged in the rotary table base, wherein the planetary gear reducer comprises an inner tooth shell and a high-speed stage planetary gear reducer, N medium-speed stage planetary gear reducers and a low-speed stage planetary gear reducer arranged in sequence along the inner tooth shell, N≥0, and the high-speed stage, medium-speed stage and low-speed stage planetary gear reducers each comprise a sun gear, a planetary gear, a planet carrier and a planet shaft; the rotary table surface is fixedly connected with the low-speed stage planet carrier, and the motor transmits power to the rotary table surface through the planetary gear reducer.

[0012] A rotation speed measuring unit is arranged on the low-speed stage planet carrier for measuring the output rotation speed, and the rotation speed measuring unit is used to return the real-time position of the low-speed stage planet carrier to the motor control unit, and the motor control unit adjusts the output of the motor according to the real-time position.

[0013] Further, the rotation speed measuring unit comprises a magnetic scale disc fixedly connected with the low-speed stage planet carrier, a reading head for contact reading of the position of the magnetic scale disc, and a cable for transmitting the information read by the reading head.

[0014] Further, the planetary gear reducer adopts a planetary gear mechanism without reverse backlash.

[0015] Further, the inner tooth shell and the rotary table base are an integral piece.

[0016] Further, the high-speed stage sun gear of the high-speed stage planetary gear reducer is fixedly connected with the output shaft of the motor, the high-speed stage sun gear is engaged with the high-speed stage planetary gear, the high-speed stage planetary gear is connected with the high-speed stage planet carrier through the high-speed stage planet shaft, and the high-speed stage planet carrier is fixedly sleeved on the medium-speed stage sun gear of the adjacent next-stage medium-speed stage planetary gear reducer; the medium-speed stage sun gear is of a segmented structure comprising a driving segment and a transmission segment, the driving segment is sleeved with the planet carrier of the previous-stage reducer, and the transmission segment is engaged with the planetary gear of the adjacent next-stage reducer; the structure is repeated until the low-speed stage sun gear of the low-speed stage planetary gear reducer is engaged.

[0017] Further, the output shaft of the motor is connected with the sun gear of the high-speed stage planetary gear reducer through a shaft sleeve, and the sun gear of the high-speed stage planetary gear reducer is fixed on the shaft sleeve through interference fit of a pin shaft.

[0018] Further, the driving segment and the transmission segment of the medium-speed stage sun gear are both gear structures, the tooth height of the driving segment is smaller than that of the transmission segment, the driving segment gear is engaged with the planet carrier of the previous-stage reducer and is fixedly sleeved through a key, the end face of the previous-stage planet carrier is in contact with the outer tooth end face of the transmission segment on the sun gear of the current stage, and at the same time, a micro gap is formed between the end face of the current-stage planet gear.

[0019] Further, the low-speed stage planet carrier and the inner gear shell are provided with N rows of balls and N rows of raceways, N is a natural number, and N≥1; the raceway cross section includes at least one circular arc which is not coincident with the cross section center; the raceway is composed of an outer ring inner raceway arranged on the inner gear shell and an inner ring outer raceway arranged on the planet carrier.

[0020] Further, the high-speed stage planet gear reduction mechanism, the medium-speed stage planet gear reduction mechanism or the low-speed stage planet gear reduction mechanism planet carrier and the planet wheel are connected through a planet shaft, and the planet shaft and the planet wheel are provided with a multi-point contact type ball bearing.

[0021] Further, the low-speed stage planet carrier and the inner gear shell are provided with N rows of balls and N rows of raceways, N is a natural number, and N≥2; when N is 2, the first bearing raceway includes four circular arcs which are not coincident with the cross section center, each occupying 1 / 4 of the cross section circumference; the second bearing raceway includes four circular arcs which are not coincident with the cross section center, each occupying 1 / 4 of the cross section circumference; the circular arcs of the first bearing raceway and the second raceway are the same; or when N is 2, the first bearing raceway includes two eccentric circular arcs, each occupying 1 / 2 of the cross section circumference; the second bearing raceway includes two eccentric circular arcs, each occupying 1 / 2 of the cross section circumference; the circular arcs of the first bearing raceway and the second raceway are mirror image arranged; or when N is 3, the first bearing raceway includes one circular arc which is not coincident with the cross section center, occupying 1 / 4 of the cross section circumference; the third bearing raceway includes one circular arc which is not coincident with the cross section center, occupying 1 / 4 of the cross section circumference; the second bearing raceway includes two eccentric circular arcs, occupying 1 / 2 of the cross section circumference; the circular arcs of the first bearing raceway and the third raceway are mirror image arranged.

[0022] Further, the low-speed stage planet carrier and the turntable surface are provided with a shaft sleeve for coaxial connection of the low-speed stage planet carrier and the turntable surface, and the shaft sleeve is in interference fit with the low-speed stage planet carrier.

[0023] Further, the turntable surface is provided with a T-shaped groove.

[0024] Further, the high-speed stage planet gear reduction mechanism planet wheel is axially positioned through the interference connected part of the input motor and the high-speed stage sun gear; the medium-speed stage planet gear reduction mechanism planet shaft and the planet shaft mounting hole on the planet carrier are in interference fit, the end surface of the upper stage planet carrier and the transmission segment outer tooth end surface on the current stage sun gear are in contact, and mutual axial positioning is provided; the medium-speed stage planet gear reduction mechanism planet wheel and the planet carrier are in contact to realize axial positioning.

[0025] Further, the axial positioning of the low-speed stage planet carrier is provided by N rows of balls and N rows of raceways.

[0026] The advantages of the present application are:

[0027] 1. The rotary table provided by the application adopts a precision planetary gear reduction, and has higher transmission rigidity and stronger load inertia adaptability than a direct drive motor scheme, and has higher efficiency and greater power density than a worm gear pair scheme.

[0028] 2. In the preferred scheme of the rotary table provided by the application, a self-made output end multi-point contact ball bearing mode is adopted, the manufacturing precision of the multi-point contact ball bearing structure is higher than that of the cylindrical needle bearing adopted by the existing planetary gear bearing, the bearing capacity, rigidity and transmission precision are stronger, and the multi-point contact ball bearing structure can be preloaded to eliminate bearing play, thereby reducing the reverse clearance of the reducer.

[0029] 3. In the preferred scheme of the rotary table provided by the application, the reducer is axially positioned on the planetary gear of the first-stage planetary gear reduction mechanism through the connecting structure (coupling sleeve) between the motor and the planetary reducer, the planetary gear bearing is axially positioned by the planetary carrier of the current stage, the planetary carrier of the previous stage is axially positioned through the transmission section of the planetary gear of the next stage, and the same-stage planetary gear and planetary carrier are directly contacted to realize mutual axial positioning. Compared with the existing reducer structure, the structure of the application not only shortens the overall axial size of the planetary gear reducer, but also reduces the number of parts and the manufacturing cost.

[0030] 4. In the preferred scheme of the rotary table provided by the application, the end face of the planetary carrier of the previous stage and the end face of the planetary gear of the current stage form a micro gap between the two adjacent stages of planetary gear reduction mechanisms, which can not only bear the axial positioning function, but also leave space for oil to establish an oil film between the contact surfaces, improve lubrication and reduce wear. At the same time, the manufacturing tolerance is increased, and the manufacturing difficulty is reduced.

[0031] 5. In the preferred scheme of the rotary table provided by the application, the selection of the planetary gear mechanism without reverse clearance makes the rotary table achieve the clearance elimination result, so that full closed-loop control feedback can be used without worrying about the shock problem.

[0032] 6. The application adopts a common inner tooth shell for all stages of planetary gear reduction mechanisms, and the planetary gears of all stages are designed with the same modulus, so that the width size of the planetary gears in all stages of planetary mechanisms can be thinned, further reducing the axial size of the reducer. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a structure sectional view of the application;

[0034] Figure 2 It is a structure left view of the application;

[0035] Figure 3 It is a schematic view of a planetary gear bearing without a shallow groove;

[0036] Figure 4 Fig. 1 is a schematic diagram of a planetary bearing with shallow grooves;

[0037] The drawings are described as follows:

[0038] 11-motor, 13-mid-speed stage planetary gear reducer, 14-low-speed stage planetary gear reducer, 15-high-speed stage planetary gear reducer, 16-magnetic grating disc, 17-reading head, 18-rotary table surface, 19-planet gear reducer inner gear shell, 20-rotary table base, 21-bush, 22-ball, 23-multipoint and multi-column contact ball, 26-motor output shaft, 27-coupling sleeve, 28-pin shaft; 141-high-speed stage sun gear, 151-output flange (low-speed stage carrier), 202-low-speed stage planet gear, 204-low-speed stage planet gear shaft, 207-low-speed stage planet gear inner hole. DETAILED DESCRIPTION

[0039] In order to make the above objectives, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below in combination with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the protection scope of the present application.

[0040] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.

[0041] Meanwhile, in the description of the present application, it should be noted that the orientation or position relationship indicated by the terms "up, down, inner and outer" is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the present application. In addition, the terms "first, second or third" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0042] In the present application, unless otherwise explicitly specified and limited, the terms "mounting, connection, connection" should be understood broadly, for example: it can be fixed connection, detachable connection or integral connection; it can also be mechanical connection, electrical connection or direct connection, it can also be indirectly connected through an intermediate medium, or the internal communication of two elements. 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.

[0043] AsFigure 1 as shown:

[0044] The rotary table comprises a motor 11, a rotary table base 20, a rotary table surface 18, a planetary gear reducer arranged in the rotary table base 20, the motor 11 is connected with the rotary table base 20, the rotary table surface 18 is fixedly connected with a low-speed stage planetary carrier, and the motor 11 transmits power to the rotary table surface 18 through the planetary gear reducer.

[0045] The planetary gear reducer comprises an inner tooth shell 19 and a high-speed stage planetary gear reducer mechanism 15, N medium-speed stage planetary gear reducer mechanisms 13 and a low-speed stage planetary gear reducer mechanism 14 arranged in the inner tooth shell 19 in sequence along the axial direction of the inner tooth shell 19,

[0046] In practice, the number of the medium-speed stage planetary gear reducer mechanisms 13 can be selected according to the reduction ratio and the bearing capacity,

[0047] In the embodiment, N = 1 is selected, that is, one high-speed stage, one medium-speed stage and one low-speed stage planetary gear reducer mechanism, and each stage of the planetary gear reducer mechanism comprises a sun gear, a planet gear, a planet carrier and a planet shaft.

[0048] In actual application, the specific structure of the planetary gear reducer can be preferably a planetary gear mechanism without reverse clearance, which is disclosed in 201810790333.7. The structure can reduce or completely eliminate the reverse clearance of the planetary gear transmission device by eliminating the side clearance in gear meshing and the bearing clearance, greatly improving the precision of the planetary gear reducer, and the structure does not increase any other parts, which greatly reduces the weight and volume of the rotary table.

[0049] In addition, a rotation speed measuring unit for measuring the output rotation speed is arranged on the low-speed stage planet carrier, the rotation speed measuring unit is used to return the real-time position of the low-speed stage planet carrier to the motor control unit, and the motor control unit adjusts the output of the motor 11 according to the real-time position. From the preferred point of view, the rotation speed measuring unit comprises a magnetic scale disc 16 fixedly connected with the low-speed stage planet carrier, a reading head 17 for contact reading the position of the magnetic scale disc 16, and a cable for transmitting the information read by the reading head 17. The data obtained by the reading head 17 can be transmitted back to the CNC or driver through the cable for full closed-loop control.

[0050] As another preferred scheme adopted in the embodiment, the connection between the inner tooth shell 19 of the planetary gear reducer and the rotary table base 20 can be fixed by screws, and the high-speed stage sun gear of the planetary gear reducer is fixedly connected with the output shaft of the motor 11 through a shaft sleeve 27. Of course, the inner tooth shell of the planetary gear reducer and the rotary table base 20 can also be made as an integral part. Although this method can also be used, it will increase the machining cost and assembly difficulty in practice.

[0051] Furthermore, the pin shaft blocks the lubricating oil inside the speed reducer to prevent it from leaking, and on the other hand, it is in interference connection with the high-speed stage sun gear of the planetary reducer, and it enlarges the inner hole of the high-speed stage sun gear of the planetary reducer, thereby assisting the interference connection of the high-speed stage sun gear of the planetary reducer and the shaft sleeve 27.

[0052] Similarly, the shaft sleeve and the low-speed stage planet carrier of the planetary reducer are in interference fit in the present embodiment, which on the one hand blocks the lubricating oil inside the speed reducer to prevent it from leaking to the rotary table, and on the other hand, it plays a role in assisting the coaxiality of the low-speed stage planet carrier of the planetary reducer and the rotary table surface.

[0053] The connection relationship of each component is further described as follows:

[0054] The high-speed stage sun gear of the high-speed stage planetary gear reduction mechanism is fixedly connected with the motor output shaft 26, the high-speed stage sun gear is engaged with the high-speed stage planet gear, the high-speed stage planet gear is connected with the high-speed stage planet carrier through the high-speed stage planet shaft, and the high-speed stage planet carrier is fixedly sleeved on the medium-speed stage sun gear of the adjacent next-stage medium-speed stage planetary gear reduction mechanism 13.

[0055] The medium-speed stage sun gear adopts a segmented structure, which includes a driving segment and a transmission segment, the driving segment is sleeved with the planet carrier of the previous-stage reduction mechanism, and the transmission segment is engaged with the planet gear of the adjacent next-stage reduction mechanism; the structure is repeated until the low-speed stage sun gear of the low-speed stage planetary gear reduction mechanism 14 is engaged.

[0056] The driving segment and the transmission segment of the medium-speed stage sun gear are both gear structures, the tooth height of the driving segment is smaller than that of the transmission segment, the driving segment gear is engaged with the planet carrier of the previous-stage reduction mechanism and is fixedly sleeved through a key, the end face of the previous-stage planet carrier is in contact with the outer tooth end face of the transmission segment on the current-stage sun gear, and at the same time, a micro-gap is formed between the end face of the current-stage planet gear.

[0057] Considering the multi-directional force and reasonable force unloading working conditions, N rows of balls and N rows of raceways can be provided between the low-speed stage planet carrier and the inner tooth shell, N is a natural number, and N≥1; in the present embodiment, a single row is selected for illustration, i.e. N=1. The raceway cross section includes at least one circular arc which does not coincide with the center of the cross section; the raceway is composed of an outer ring inner raceway provided on the inner tooth shell and an inner ring outer raceway provided on the planet carrier.

[0058] Of course, other structure forms of N≥2 can also be selected, for example: when N is 2, the first bearing raceway contains four circular arcs which do not coincide with the center of the cross section, each occupying 1 / 4 of the cross section circumference; the second bearing raceway contains four circular arcs which do not coincide with the center of the cross section, each occupying 1 / 4 of the cross section circumference; the circular arcs of the first bearing raceway and the second raceway are the same;

[0059] or when N is 2, the first bearing raceway comprises two eccentric circular arcs, each occupying 1 / 2 of the cross-sectional circumference; the second bearing raceway comprises two eccentric circular arcs, each occupying 1 / 2 of the cross-sectional circumference; the circular arc of the first bearing raceway and the circular arc of the second raceway are mirror images;

[0060] or when N is 3, the first bearing raceway comprises a circular arc that does not coincide with the cross-sectional center, occupying 1 / 4 of the cross-sectional circumference; the third bearing raceway comprises a circular arc that does not coincide with the cross-sectional center, occupying 1 / 4 of the cross-sectional circumference; the second bearing raceway comprises two eccentric circular arcs, occupying 1 / 2 of the cross-sectional circumference; the circular arc of the first bearing raceway and the circular arc of the third raceway are mirror images.

[0061] Similarly, considering the multi-directional force and reasonable unloading working conditions, the high-speed planetary gear reduction mechanism 15, the medium-speed planetary gear reduction mechanism 13 or the low-speed planetary gear reduction mechanism 14 planet carrier and the planet wheel are connected through the planet shaft, and a plurality of multi-point contact type ball bearings 23 are arranged between the planet shaft and the planet wheel.

[0062] Taking the three-point contact ball bearing arranged in the low-speed planetary gear reduction mechanism 14 as an example, as shown in Figure 1 and Figure 3 The low-speed planetary shaft 204 is provided with S first inner ring outer raceways 2041 on the outer surface in the low-speed planetary wheel bearing mounting hole 207, S≥2, and a plurality of first steel balls 400 are arranged between each first inner ring outer raceway 2041 and the hole wall of the low-speed planetary wheel bearing mounting hole 207 in the circumferential direction; the first steel balls 400 installed in each adjacent two first inner ring outer raceways 2041 are arranged in a staggered manner in the circumferential direction, thereby forming a planet wheel bearing of an N-stage planetary gear reduction mechanism; the low-speed planetary wheel bearing mounting hole 207 is provided with an inwardly protruding arc-shaped channel 2042 near one side of the planet carrier, which is used for axially positioning the first steel balls 400.

[0063] In order to position the first steel ball 400 more reliably, as shown in Figure 1 and Figure 4 In the embodiment, S shallow grooves 2071 are also formed on the inner wall of the low-speed planetary wheel bearing mounting hole 207, and the S shallow grooves 2071 correspond to the S first inner ring outer raceways 2041 one by one; the first inner ring outer raceway 2041 is composed of two eccentric circular arcs, which are respectively referred to as the fifth circular arc and the sixth circular arc; the first steel ball 400 is in point contact with the two circular arcs respectively, and is in contact with the shallow groove 2071, thereby forming a more reliable three-point contact ball bearing structure.

[0064] A T-shaped groove is arranged on the turntable surface.

[0065] Based on the above structure, since there is no any hard connection between the planetary gear reduction mechanisms of each level, that is, the fixed connection mechanism such as bolt is adopted, and the related mechanism is increased, which greatly increases the volume and weight of the rotary table, therefore, the axial positioning needs to rely on the mutual matching relationship between the components. Among them, the planetary gear of the high-speed planetary gear reduction mechanism is axially positioned by the part of the interference connection between the input motor and the high-speed sun gear; the planetary shaft of the medium-speed planetary gear reduction mechanism 13 is in interference fit with the planetary shaft mounting hole on the planet carrier, the end face of the upper planet carrier contacts the outer tooth end face of the transmission section on the current sun gear, and mutual axial positioning is provided; the planetary gear and the planet carrier of the medium-speed planetary gear reduction mechanism 13 contact each other to realize axial positioning. The axial positioning of the low-speed planet carrier is provided by N rows of balls and N rows of ball tracks.

Claims

1. A rotary table comprising a motor, a rotary table base and a rotary table surface, characterized in that: a planetary gear reducer is arranged in the rotary table base, the planetary gear reducer adopts a planetary gear mechanism without reverse clearance, comprising an inner tooth shell and a high-speed stage planetary gear reduction mechanism, N medium-speed stage planetary gear reduction mechanisms and a low-speed stage planetary gear reduction mechanism arranged along the inner tooth shell in sequence in the axial direction, N≥0, the high-speed stage, medium-speed stage and low-speed stage planetary gear reduction mechanisms each comprise a sun gear, a planet gear, a planet carrier and a planet shaft; the rotary table surface is fixedly connected with the low-speed stage planet carrier, the motor transmits power to the rotary table surface through the planetary gear reducer; the sun gear of the medium-speed stage planetary gear reduction mechanism is of a segmented structure, the segmented structure comprises a driving segment and a transmission segment, the driving segment is sleeved with the planet carrier of the upper-stage reduction mechanism, and the transmission segment is engaged with the planet gear of the adjacent lower-stage reduction mechanism; the structure is repeated until the low-speed stage sun gear of the low-speed stage planetary gear reduction mechanism is engaged; a rotation speed measuring unit for measuring the output rotation speed is arranged on the low-speed stage planet carrier, the rotation speed measuring unit is used to return the real-time position of the low-speed stage planet carrier to a motor control unit, and the motor control unit adjusts the output of the motor according to the real-time position; the output shaft of the motor is connected with the sun gear of the high-speed stage planetary gear reduction mechanism through a shaft sleeve, and the sun gear of the high-speed stage planetary gear reduction mechanism is fixed on the shaft sleeve through interference fit of a pin shaft; the planet gears of the high-speed stage planetary gear reduction mechanism are axially positioned through the structure that the input motor is connected with the high-speed stage sun gear in interference; the planet shafts on the planet carriers of the medium-speed stage planetary gear reduction mechanisms are interference-fitted with planet shaft mounting holes on the planet carriers, the end face of the planet carrier of the upper-stage reduction mechanism is in contact with or forms a micro gap with the toothed end face of the transmission segment on the sun gear of the current stage, and mutual axial positioning is provided; the planet gears of the medium-speed stage and low-speed stage planetary gear reduction mechanisms are in contact with the planet carriers of the upper-stage reduction mechanisms, to achieve axial positioning of one side of the planet gears; the low-speed stage planet gears are in contact with the low-speed stage planet carriers, to achieve axial positioning of one side of the low-speed stage planet gears. 2.The rotary table according to claim 1, characterized in that: the rotation speed measuring unit comprises a magnetic scale disc fixedly connected with the low-speed stage planet carrier, a reading head for contact reading of the position of the magnetic scale disc, and a cable for transmitting the information read by the reading head. 3.The rotary table according to claim 2, characterized in that: the high-speed stage sun gear of the high-speed stage planetary gear reduction mechanism is fixedly connected with the output shaft of the motor, the high-speed stage sun gear is engaged with the high-speed stage planet gear, the high-speed stage planet gear is connected with the high-speed stage planet carrier through a high-speed stage planet shaft, and the high-speed stage planet carrier is fixedly sleeved on the medium-speed stage sun gear of the adjacent lower-stage medium-speed stage planetary gear reduction mechanism. 4.The rotary table according to claim 3, characterized in that: ​ ​ ​ The driving section and the transmission section of the medium-speed stage sun gear are gear structures, the tooth height of the driving section is less than that of the transmission section, the driving section gear is engaged with the planet carrier of the previous stage reduction mechanism and is fixed by a key to achieve sleeve connection, the end surface of the previous stage planet carrier is in contact with the transmission section outer tooth end surface of the current stage sun gear, and simultaneously forms a micro gap with the end surface of the current stage planet gear.

5. The rotary table according to any one of claims 1 to 4, wherein: N rows of balls and N rows of ball tracks are arranged between the low-speed stage planet carrier and the inner tooth shell, N is a natural number, and N≥1; The ball track cross section includes at least one circular arc that does not coincide with the cross-sectional center; The ball track is composed of an outer ring inner track arranged on the inner tooth shell and an inner ring outer track arranged on the planet carrier.

6. The rotary table according to claim 5, wherein: The high-speed stage planet gear reduction mechanism, the medium-speed stage planet gear reduction mechanism, or the low-speed stage planet gear reduction mechanism planet carrier and the planet gear are connected through a planet shaft, and a multi-point contact ball bearing is arranged between the planet shaft and the planet gear.

7. The rotary table according to claim 5, wherein: N rows of balls and N rows of ball tracks are arranged between the low-speed stage planet carrier and the inner tooth shell, N is a natural number, and N≥2; When N is 2, the first bearing ball track includes four circular arcs that do not coincide with the cross-sectional center, each occupying 1 / 4 of the cross-sectional circumference; the second bearing ball track includes four circular arcs that do not coincide with the cross-sectional center, each occupying 1 / 4 of the cross-sectional circumference; the circular arcs of the first bearing ball track and the second ball track are the same; Or when N is 2, the first bearing ball track includes two eccentric circular arcs, each occupying 1 / 2 of the cross-sectional circumference; the second bearing ball track includes two eccentric circular arcs, each occupying 1 / 2 of the cross-sectional circumference; the circular arcs of the first bearing ball track and the second ball track are mirror images; Or when N is 3, the first bearing ball track includes one circular arc that does not coincide with the cross-sectional center, occupying 1 / 4 of the cross-sectional circumference; the third bearing ball track includes one circular arc that does not coincide with the cross-sectional center, occupying 1 / 4 of the cross-sectional circumference; the second bearing ball track includes two eccentric circular arcs, occupying 1 / 2 of the cross-sectional circumference; the circular arcs of the first bearing ball track and the third ball track are mirror images.

8. The rotary table according to claim 7, wherein: An axle sleeve for coaxially connecting the low-speed stage planet carrier and the rotary table surface is arranged between the low-speed stage planet carrier and the rotary table surface, and the axle sleeve is in interference fit with the low-speed stage planet carrier.

9. The rotary table according to claim 5, wherein: The axial positioning of the low-speed stage planet carrier is provided by N rows of balls and N rows of ball tracks.

Images