CN207093681U - A kind of Cycloid Steel Ball Planetary Transmission mechanism and its joint of robot deceleration device - Google Patents
A kind of Cycloid Steel Ball Planetary Transmission mechanism and its joint of robot deceleration device Download PDFInfo
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Abstract
The utility model discloses a kind of Cycloid Steel Ball Planetary Transmission mechanism and its joint of robot deceleration device, belong to speed reduction gearing field.The utility model discloses a kind of Cycloid Steel Ball Planetary Transmission mechanism, including planetary plate, spider and steel ball group, gap d, d=Z are left between each steel ball in the steel ball group0The π of (h+ Δs)/2, there is the teeth groove that tooth form is correction of the flank shape hypocycloid, it is the epicycloidal teeth groove of correction of the flank shape to have tooth form on the end face of the planetary plate on the end face of the spider.Cross steel ball constant speed drive mechanism includes planetary plate, steel ball group, cross plate and end cap disk, and the straight-line groove of structure optimization is respectively provided with the end face of the planetary plate, cross plate and end cap disk.The utility model on the basis of small speed is possessed than performance, can effective hoisting machine person joint deceleration device actual bearer ability and service life, the electronic rotation type joint especially suitable for high speed transfer robot.
Description
Technical Field
The utility model relates to a reduction gearing technical field, more specifically say, relate to a cycloid steel ball planetary transmission mechanism and robot joint decelerator thereof.
Background
At present, industrial robot joint reduction gears are of a wide variety, including RV reducers, harmonic reducers, cycloid steel ball reducers and the like. Although the bearing capacity of the RV reducer and the harmonic reducer is strong, the speed ratio of the RV reducer and the harmonic reducer is usually larger than 30, and the RV reducer and the harmonic reducer are not suitable for the requirement of the high-speed transfer robot on the running speed. The cycloidal steel ball speed reducer is a two-tooth difference planetary speed reducer, and has the advantages of small speed ratio and zero backlash required by a high-speed carrying robot, but has the problems of poor lubrication of a meshing pair, easy undercut of tooth profile, poor bearing of a constant speed mechanism and the like, so that the speed reducer is low in power density, poor in load capacity and short in service life, and is less applied to an industrial robot. At present, an industrial robot joint speed reducing device which has the advantages of zero back clearance, small speed ratio and the like and is strong in bearing capacity, strength and service life is urgently needed.
Chinese patent No. 99202368.8, published 2000, 9.27, discloses a patent document entitled "dense ball cycloidal steel ball speed reducer", which includes an eccentric shaft and a balance block on an input shaft, an eccentric disc with hypocycloidal raceways mounted outside the eccentric shaft, an anti-rotation mechanism connected between one side of the eccentric disc and the inner side of an end cover, an output disc connected with an output shaft and with epicycloidal raceways on the side, and steel ball gears densely mounted between the eccentric disc and the two raceways of the output disc to form meshing transmission. In the reducer disclosed by the patent, steel balls among cycloid raceways are densely installed, the power density is theoretically improved, but the cycloid raceway center equation provided by the patent does not contain a steel ball gauge value and lubricating grease thickness parameters among the steel balls, namely the influence of the diameter error of the steel balls is not considered, and lubricating grease gaps among the steel balls are not reserved, so that the densely installed steel balls are not separated by the lubricating grease, and the steel balls are directly extruded and abraded. Therefore, the speed reducer disclosed by the patent is easy to have the problems of poor lubrication, accelerated abrasion and the like in an actual use state, and the bearing capacity and the service life are still poor.
Chinese patent No. 201410101989.5, published as 2014 25.6.25 discloses a patent document named "single-stage hard tooth surface cycloid steel ball planetary reducer", which comprises a casing, an input shaft, an eccentric sleeve, a steel ball group, an end cover disc, a cross disc, a planetary disc, a central disc, an output shaft, a pre-tightening nut, a support bearing and a bearing end cover. The speed reducer adopts a basic structure of K-H-V type single-stage small-tooth-difference planetary transmission, takes inner and outer cycloid grooves on the end faces of a central disc and a planetary disc as tooth profiles, takes steel balls as an intermediary body for meshing transmission, eliminates tooth gaps through four-point contact of the steel balls and the cycloid grooves, is matched with a non-tooth-gap cross steel ball constant-speed transmission mechanism, and has the advantages of simple structure, small volume, zero tooth gap, high transmission precision and high efficiency. In the speed reducer disclosed in the patent, each group of horizontal grooves and vertical grooves forming the cross steel ball constant-speed transmission mechanism are easy to cause uneven load distribution among the grooves due to the unevenness of the horizontal grooves and the vertical grooves, so that the running stability of the speed reducer is reduced, vibration is caused, and the service life is shortened.
SUMMERY OF THE UTILITY MODEL
1. Technical problem to be solved by the utility model
The utility model aims to overcome the defects of smaller speed ratio and poorer actual bearing capacity of the cycloidal steel ball speed reducer in the prior art, and provides a cycloidal steel ball planetary transmission mechanism which can effectively improve the actual bearing capacity and the service life of the cycloidal steel ball planetary transmission mechanism on the basis of keeping the performance of small speed ratio; the provided robot joint speed reducer is more suitable for industrial robot joints, and is particularly suitable for the use requirements of electric rotary joints of high-speed transfer robots.
2. Technical scheme
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the invention relates to a cycloid steel ball planetary transmission mechanism which comprises a planetary disc, a central disc and a steel ball group, wherein gaps d are reserved among steel balls in the steel ball group, and d = Z 0 (h + Delta)/2 pi, wherein Z 0 The number of steel balls in the steel ball group; h is the thickness of the lubricating grease among the steel balls; and delta is the gauge value of the steel ball.
As a further improvement of the invention, the tooth grooves on the end faces of the planetary disks adopt a parameter-containing combination Z 0 The modified epicycloid tooth profile of (h + delta)/2 pi has the following equation:
in the formula R 0 -the steel ball sets are distributed with a circle radius;
Z 0 -the number of steel balls of the steel ball set;
h is the thickness of the lubricating grease between the steel balls;
delta-gauge of steel ball;
k is the cycloidal coefficient of short amplitude;
r 0 -cycloidal generating circle radius;
θ 1 the epicycloid forms an angle.
As a further improvement of the invention, the tooth grooves on the end face of the central disc adopt a parameter-containing combination Z 0 The shape-modifying hypocycloid tooth profile of (h + delta)/2 pi has the following equation:
in the formula R 0 -the steel ball sets are distributed with a circle radius;
Z 0 -the number of steel balls of the steel ball set;
h is the thickness of the lubricating grease between the steel balls;
delta-gauge of steel ball;
k is the cycloidal coefficient of short amplitude;
r 0 -cycloid generating circle radius;
θ 2 the hypocycloids form an angle.
As a further improvement of the present invention, the parameters of the modified epicycloid tooth profile equation and the modified hypocycloid tooth profile equation are constrained by the non-undercut condition:
wherein r is the radius of the steel ball;
R 0 -the steel ball sets are distributed with a circle radius;
Z 0 -the number of steel balls of the steel ball set;
k is the coefficient of cycloid minor amplitude;
Z 1 -the number of teeth in the tooth socket on the end face of the planet carrier;
beta is the slot angle of the tooth slot.
The invention relates to a robot joint speed reducer, which comprises a cross steel ball constant-speed transmission mechanism and a cycloid steel ball planetary transmission mechanism according to any one of claims 1 to 4, wherein the cross steel ball constant-speed transmission mechanism mainly comprises a planetary disc, a cross disc, an end cover disc and a steel ball group.
As a further improvement of the invention, the straight-line grooves on the matched end surfaces of the planetary disc, the cross disc and the end cover disc are uniformly and equidistantly distributed on the distribution circle.
As a further improvement of the invention, the number n of the straight-line grooves is determined by a parameter formula:
wherein l is the length of the linear groove;
r is the radius of the steel ball;
R 1 -the radius of the distribution circle of the linear grooves.
As a further development of the invention, the length l of the straight-line groove is parametrically determined by:
l>2r+e；
wherein r is the radius of the steel ball;
e is the eccentricity of the input shaft.
3. Advantageous effects
Adopt the technical scheme provided by the utility model, compare with prior art, have following beneficial effect:
(1) The utility model discloses a cycloid steel ball planetary transmission mechanism, its enhancement mode cycloid steel ball transmission mechanism in, not closely arrange between each steel ball of steel ball group, but leave parameter combination Z between each steel ball 0 The tiny gap d determined by (h + delta)/2 pi is combined according to the parameters to obtain a modified hypocycloid tooth profile equation and a modified epicycloid tooth profile equation corresponding to the cycloid tooth groove; by combination of parameters Z 0 The micro gap determined by (h + delta)/2 pi can provide a space required by the error amount when the actual diameter of the steel ball is larger than the nominal diameter, and avoids excessive extrusion among the steel balls; and the required space of lubricating grease can be provided, the lubricating environment among the steel balls is ensured, and the actual service life of the speed reducer is effectively prolonged.
(2) The utility model discloses a cycloid steel ball planetary drive mechanism, among the cycloid steel ball drive mechanism, the parameter of repairing shape epicycloid profile of tooth equation and repairing shape hypocycloid profile of tooth equation receives not undercut condition restraint to the curvature radius of ensureing tooth's socket tooth root department is greater than the steel ball radius all the time, avoids the planet dishAnd the tooth grooves on the end surface of the central disc are subjected to undercut, so that the contact stress between the steel balls and the tooth grooves is reduced, and the abrasion between the steel balls and the tooth grooves is reduced. The maximum contact stress between the steel ball and the tooth socket is about 6 multiplied by 10 after calculation for the tooth socket which is not designed under the condition of no undercut 4 MPa; the maximum contact stress between the steel ball and the tooth socket is less than 3000MPa, and the contact stress between the steel ball and the tooth socket is reduced by 20 times compared with that between the steel ball and the tooth socket. Therefore, the reinforced robot joint speed reducing device with the technical scheme can effectively reduce the contact stress when the steel ball is meshed with the tooth socket, and the bearing capacity and the service life of the speed reducing device are enhanced.
(3) The utility model discloses a robot joint decelerator, among the enhancement mode cross steel ball constant speed drive mechanism, each straight line groove on the terminal surface of planet dish, cross dish and end cover dish is at its even equidistance distribution of the circle that distributes, and has the structure size restriction with length to the number of straight line groove to prevent that straight line groove from interfering and the steel ball card is dead. By the uniform and equidistant distribution of the linear grooves, the uniformity of load distribution among the linear grooves and the running stability of the speed reducer are improved, and the vibration is reduced; through the uniform and equidistant distribution of the straight-line grooves, the distribution circular space of the straight-line grooves is fully utilized, the number of the straight-line grooves is greatly increased, and the load on a single straight-line groove is reduced.
(4) The utility model discloses a robot joint decelerator, whole technical scheme all implement around promoting bearing capacity and life to do not change the poor tooth number ratio of two teeth of current cycloid steel ball reduction gear, consequently, this robot joint decelerator has remain the characteristic of little velocity ratio when promoting bearing capacity and life, is applicable to the running speed requirement of the electronic rotary-type joint of high-speed transfer robot.
Drawings
FIG. 1 is a schematic view of the present invention;
FIG. 2 isbase:Sub>A sectional view taken along line A-A in FIG. 1;
FIG. 3 is a sectional view taken along line B-B of FIG. 1;
FIG. 4 is a cross-sectional view taken along line C-C of FIG. 1;
FIG. 5 is a cross-sectional view taken along line D-D of FIG. 1;
FIG. 6 is a structural diagram of the zero-spacing dense installation of steel balls in a cycloid tooth groove;
FIG. 7 is a structural diagram of installation of a small gap reserved between steel balls in a cycloid tooth groove;
FIG. 8 is a view of the construction of the cycloidal gullet undercut;
FIG. 9 is a view of the construction of a cycloid gullet without undercut;
FIG. 10 is a graph of contact stress variation at cycloidal gullet undercut;
FIG. 11 is a graph of contact stress variation without undercut for a cycloidal tooth slot;
FIG. 12 is a structural diagram of non-uniform arrangement of straight grooves in a cross steel ball constant-speed transmission mechanism;
FIG. 13 is a structural diagram of uniform equidistant arrangement of straight-line grooves in a cross-shaped steel ball constant-speed transmission mechanism;
FIG. 14 is a structural diagram of the robot joint according to the present invention, when the housing is fixed and the flange is output;
fig. 15 is a structural diagram of the robot joint according to the present invention when the flange is fixed and the housing is output.
The reference numerals in the schematic drawings illustrate:
1-sealing device; 2, a baffle plate; 3, a flange; 4, pre-tightening the screw;
5, a shell; 6-crossed roller bearings; 7-central disc; 8-steel ball group;
9-planet disc; 10-steel ball group; 11-cross plate; 12-end cap disk;
13-end cap; 14-input shaft end cover; 15 — an input shaft; 16-balancing weight block;
17-cylindrical roller bearings; 18-motor.
Detailed Description
For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings and examples.
With reference to fig. 1, the robot joint reduction gear of the present embodiment includes a cross steel ball constant speed transmission mechanism and a cycloid steel ball planetary transmission mechanism, the cross steel ball constant speed transmission mechanism mainly includes a planetary disk 9, a steel ball group 10, a cross disk 11, and an end cover disk 12, and the cycloid steel ball planetary transmission mechanism mainly includes a central disk 7, a steel ball group 8, and a planetary disk 9.
As a specific embodiment, the speed reducer of this embodiment includes a sealing device 1, a baffle 2, a flange 3, a pre-tightening screw 4, a casing 5, a cross roller bearing 6, a center disk 7, a steel ball group 8, a planet disk 9, a steel ball group 10, a cross disk 11, an end cover disk 12, an end cover 13, an input shaft end cover 14, an input shaft 15, a balancing weight 16, and a cylindrical roller bearing 17. The input shaft 15 has an eccentric shaft section, on which a cylindrical roller bearing 17 is mounted. The inner ring of the cylindrical roller bearing 17 is fixed, the outer ring can move axially, the left side of the inner ring is positioned through a shaft shoulder, the right side of the inner ring is positioned by a balancing weight block 16, and the balancing weight block 16 is fixed on the input shaft 15 through a screw. The inner hole of the planetary plate 9 is connected with the outer ring of the cylindrical roller bearing 17 through matching, and the planetary plate 9 can axially move along with the outer ring of the cylindrical roller bearing 17. The straight line grooves on the end surfaces of the planetary plate 9, the cross plate 11 and the end cover plate 12 form an enhanced cross steel ball constant-speed transmission mechanism through a clamping steel ball group 10. The cross plate 11 floats, the end cover plate 12 is fixedly connected with the end cover 13 through a screw group, and the end cover 13 is fixedly connected with the machine shell 5 through a screw group. Tooth grooves on the end faces of the planetary plate 9 and the central plate 7 form an enhanced cycloid steel ball gear pair through a clamping steel ball group 8. The central disk 7 is fixed on one side end face of the flange 3 through a screw group, the flange 3 is connected with the machine shell 5 through a crossed roller bearing 6, and the flange 3 can rotate relative to the machine shell 5. The baffle 2 is fixed on the other side end face of the flange 3 through a screw group, and the baffle 2 is used for pressing the crossed roller bearing 6. The external thread on the pre-tightening screw 4 is connected with the internal thread at the left end of the machine shell 5, and the clearance between the steel ball group 10 and the straight line groove in the enhanced cross steel ball constant-speed transmission mechanism and the clearance between the steel ball group 8 and the tooth groove in the enhanced cycloid steel ball gear pair can be eliminated by screwing the pre-tightening screw 4. The input shaft 15 is a hollow shaft, a key groove is arranged in an inner hole of the hollow shaft and penetrates through the whole shaft, and the input shaft 15 is connected with the end cover 13 and the flange 3 through a bearing.
Referring to fig. 1, the speed reducer has two working modes, the first mode is that the shell 5 is fixed and the flange 3 outputs, and the second mode is that the flange 3 is fixed and the shell 5 outputs. The working principle of the first mode is as follows: power is input by the input shaft 15 and transmitted to the planet disks 9 through the cylindrical roller bearings 17 thereon. In this way, the housing 5 is fixed, and the end cover 13 and the end cover plate 12 fixed on the housing 5 are also fixed. Therefore, the reinforced cross steel ball constant speed transmission mechanism formed by the planetary plate 9, the cross plate 11, the steel ball group 10 and the end cover plate 12 can limit the self-rotation movement of the planetary plate 9, so that the planetary plate 9 only moves in translation along with the self-rotation of the input shaft 15.
The planetary plate 9, the steel ball 8 and the central plate 7 form an enhanced cycloid steel ball transmission mechanism, and the planetary plate 9 pushes the central plate 7 to rotate at a lower speed through the steel ball group 8. The flange 3 is fixedly connected to the central disc 7 through a screw group and can rotate at a low speed along with the central disc 7 to complete power output.
The working principle of the second mode is as follows: power is input by the input shaft 15 and transmitted to the planet disks 9 through the cylindrical roller bearings 17 thereon. In this way the flange 3 is fixed, so that the central disk 7 fixed to the flange 3 is also non-rotatable. Therefore, the planetary plate 9 is restrained by the central plate 7 to rotate at a low speed under the action of the enhanced cycloid steel ball gear pair. The low-speed rotation of the planetary disk 9 is transmitted to the end cover disk 12 at a constant speed through the enhanced cross steel ball constant-speed transmission mechanism. The shell 5 is fixedly connected with the end cover 13 and the end cover disc 12 through a screw group, and can rotate at a low speed along with the end cover disc 12 to complete power output.
Referring to fig. 2 and 3, in the end face structure of the cycloid steel ball transmission mechanism of the present embodiment, the steel ball groups 8 are uniformly and equidistantly arranged in the tooth grooves of the planetary plate 9 and the central plate 7.
Fig. 6 is a structural diagram of the zero-pitch dense installation of steel balls in the prior art. FIG. 7 is a structural diagram of the installation of the steel balls with a small gap reserved therebetween. Compared with the fig. 6 and 7, the steel balls in fig. 6 are closely arranged at zero spacing, although the volume of the reducer is reduced theoretically and the power density is improved, because no gap exists among the steel balls to contain the diameter error of the steel balls and lubricating grease, the steel balls which are densely arranged are not separated by the lubricating grease, and the steel balls are directly extruded and worn; even when the actual diameter of the steel balls is larger than the nominal diameter due to manufacturing errors, excessive pressing between the steel balls is caused. Therefore, in the prior art, the problems of poor lubrication, aggravation of abrasion and the like of the steel balls are easily caused in an actual use state in a steel ball zero-space intensive installation mode, and the bearing capacity and the service life of the speed reducer are still poor.
In contrast, in fig. 7, the steel balls are not closely arranged, but a parameter combination Z is left between the steel balls 0 Minute gap d = Z determined by (h + Δ)/2 π 0 (h + Delta)/2 pi, wherein Z 0 The number of steel balls in the steel ball group; h is the thickness of the lubricating grease among the steel balls; and delta is the gauge value of the steel ball. The parameter combination Z 0 The (h + delta)/2 pi comprises a steel ball gauge value delta, and is used for reserving a tiny gap to adapt to a steel ball diameter error corresponding to the steel ball gauge value; the thickness h of the lubricating grease among the steel balls is also included, and a tiny gap is reserved for containing the lubricating grease. By combination of parameters Z 0 The small clearance determined by the (h + delta)/2 pi can provide a required space for the error amount when the actual diameter of the steel ball is larger than the nominal diameter, and excessive extrusion among the steel balls is avoided; and the required space of lubricating grease can be provided, the lubricating environment among the steel balls is ensured, the speed reducing device has a good running environment, and the actual service life of the speed reducing device is effectively prolonged.
Furthermore, the parameter combination Z 0 The order of magnitude of the micro gap determined by (h + delta)/2 pi is small and is 10 -2 And the gap is mm-level, and no redundant space is provided for the steel ball to move after the diameter error of the lubricating grease and the steel ball is accommodated in the gap, so that each steel ball which is separated by the lubricating grease cannot deviate from a preset position in the assembling and running processes, and the poor meshing or the running blocking of the speed reducer can be avoided.
Further, a parameter combination Z is introduced between the steel balls in FIG. 7 0 After a small gap defined by (h + Δ)/2 π, the tooth gap must be modified. Specifically, in the prior art, the steel balls are densely installed at zero intervals, and the epicycloid tooth form equation corresponding to the cycloid tooth grooves is as follows:
in the embodiment, a parameter combination Z is reserved among the steel balls 0 Compared with the prior art, the small gap installation determined by (h + delta)/2 pi has the following shape modification epicycloid tooth form equation corresponding to the cycloid tooth grooves on the planet disk 9:
in the formula R 0 -the steel ball sets are distributed with a circle radius;
Z 0 -the number of steel balls of the steel ball set;
h is the thickness of the lubricating grease between the steel balls;
delta-gauge of steel ball;
k is the cycloidal coefficient of short amplitude;
r 0 -cycloidal generating circle radius;
θ 1 the epicycloid forms an angle.
Specifically, in the prior art, the steel balls are densely installed at zero intervals, and the hypocycloid tooth form equation corresponding to the cycloid tooth grooves is as follows:
the invention discloses a reserved parameter combination Z between steel balls 0 Compared with the prior art, the small gap installation determined by (h + delta)/2 pi has the following structural formula that the shape modification hypocycloid tooth profile corresponding to the cycloid tooth slot on the central disc 7 is as follows:
in the formula R 0 -the steel ball sets are distributed with a circle radius;
Z 0 -the number of steel balls of the steel ball set;
h is the thickness of the lubricating grease between the steel balls;
delta-gauge of steel ball;
k is the cycloidal coefficient of short amplitude;
r 0 -cycloid generating circle radius;
θ 2 the hypocycloids form an angle.
The parameters of the modified epicycloid tooth profile equation and the modified hypocycloid tooth profile equation are constrained by a non-undercut condition, so that the tooth grooves on the end surfaces of the planetary disk and the central disk are prevented from being undercut, the contact stress between the steel balls and the tooth grooves is reduced, the abrasion between the steel balls and the tooth grooves is reduced, the bearing capacity of the cycloid steel ball gear pair is enhanced, and the service life of the cycloid steel ball gear pair is prolonged.
The speed reducer of the published patent scheme (application number: 99202368.8) also adopts a short-amplitude cycloid as a center equation of a cycloid raceway and provides a short-amplitude coefficient relational expression required by the equation, but the short-amplitude coefficient relational expression is only determined by the condition of dense arrangement of steel balls and does not consider the curvature radius factor of the cycloid raceway. The curvature radius of the cycloid raceway designed according to the relation is usually smaller than the radius of the steel ball at the tooth root. Therefore, during the process of machining the cycloid raceway, the tooth root is cut off by the cutter to generate an undercut phenomenon. The root cutting phenomenon causes sharp corners at the tooth root of the cycloid raceway, and when the steel ball is in angular engagement with the tooth root, the contact stress is extremely high, and the abrasion is serious. Therefore, the speed reducer disclosed by the patent is easy to have the problems of overlarge stress, aggravated abrasion and the like, and has poor bearing capacity, strength and service life.
Referring to fig. 8, it is a structural diagram of the prior art that does not consider the condition of no undercut, resulting in undercut of the cycloidal tooth slot. Fig. 10 is a graph of contact stress variation in the prior art without consideration of the under-cut condition, resulting in under-cutting of the cycloidal tooth slot. Referring to fig. 9, there is shown a block diagram of the present invention which considers the non-undercut condition and the non-undercut of the cycloidal tooth slot. Referring to fig. 11, a graph of contact stress variation for a trochoidal tooth slot without undercutting is shown, taking into account the non-undercut condition according to the present invention.
Comparing fig. 8, 10 and 9, 11, the non-undercut condition is not considered in fig. 8, resulting in a smaller radius of curvature at the cycloidal gullet root than the steel ball radius. In the cycloidal gullet machining process, the root part of the gullet is cut off by the cutter to generate an undercut phenomenon, and the shaded area in fig. 8 is the part of the tooth root cut off by the cutter. The root cutting phenomenon causes the tooth root of the cycloid tooth socket to have a sharp angle, and when the steel ball runs to the position near the sharp angle of the tooth root, the contact stress between the steel ball and the cycloid tooth socket is extremely large, and the abrasion is serious. In fig. 10, the maximum contact stress between the steel ball and the trochoidal tooth grooves is about 6 × 10 when the trochoidal tooth grooves are undercut due to the non-undercut condition not being considered 4 MPa. Therefore, the problems of overlarge stress, aggravated abrasion and the like easily occur to the cycloid steel ball speed reducer in the prior art, and the bearing capacity, the strength and the service life are poor.
In contrast, in fig. 9, the non-undercut condition is considered, and the parameters of the cycloid tooth form equation are constrained by the non-undercut condition, so that the curvature radius of the tooth root of the cycloid tooth space is always larger than the radius of the steel ball, the cycloid tooth space is prevented from being undercut, the contact stress between the steel ball and the cycloid tooth space is reduced, and the abrasion between the steel ball and the cycloid tooth space is reduced. In fig. 11, considering the non-undercut condition, when the cycloid tooth grooves are not undercut, the maximum contact stress between the steel ball and the cycloid tooth grooves is less than 3000MPa, which is about 20 times lower than the data of fig. 10. Therefore, the robot joint speed reducer can effectively reduce the contact stress when the steel ball is meshed with the tooth socket through the condition of no undercut, and can enhance the bearing capacity and prolong the service life of the speed reducer. Specifically, the conditions for the non-undercut of the cycloid tooth profile in this embodiment are as follows:
wherein r is the radius of the steel ball;
R 0 -the steel ball sets are distributed with a circle radius;
Z 0 -the number of steel balls of the steel ball set;
k is the cycloidal coefficient of short amplitude;
Z 1 -the number of teeth in the tooth socket on the end face of the planet carrier;
beta is the slot angle of the tooth slot.
Referring to fig. 1, 4 and 5, in this embodiment, the planetary plate 9, the steel ball group 10, the cross plate 11 and the end cover plate 12 form an enhanced cross steel ball constant-speed transmission mechanism, wherein a group of linear grooves which are uniformly distributed along a distribution circle in the horizontal direction are processed on the right end surface of the planetary plate 9 and the left end surface of the cross plate 11, and the linear grooves on the two end surfaces are in one-to-one correspondence; a group of straight line grooves which are in the vertical direction and are uniformly distributed along a distribution circle are processed on the right end surface of the cross plate 11 and the left end surface of the end cover plate 12, and the straight line grooves on the two end surfaces are in one-to-one correspondence; meanwhile, the straight line grooves on the left and right end faces of the cross plate 11 are perpendicular to each other.
Fig. 12 is a structural diagram of non-uniform arrangement of linear grooves in a cross steel ball constant-speed transmission mechanism in the prior art. Fig. 13 is a structural diagram of the uniform equidistant arrangement of the straight grooves in the cross steel ball constant-speed transmission mechanism of the embodiment.
Comparing fig. 12 and 13, the linear grooves in fig. 12 are unevenly distributed on the distribution circle, which easily causes uneven load distribution among the linear grooves, reduces the running stability of the speed reducer, causes vibration, and shortens the service life. In addition, the cross steel ball constant-speed transmission mechanism can only arrange 1-2 groups of linear grooves due to limited space in the radial direction, the number of the loaded linear grooves is too small, and the load on a single linear groove is large. Therefore, the cross steel ball constant-speed transmission mechanism of the cycloidal steel ball speed reducer in the prior art is a weak link of the cycloidal steel ball speed reducer, and the weak link seriously influences the bearing capacity of the speed reducer.
In contrast, in fig. 13, the linear grooves are uniformly and equidistantly distributed on the distribution circle, and the number and the length of the linear grooves are limited by the structural size so as to prevent the interference of the linear grooves and the jamming of the steel balls. Specifically, the number n of the straight-line grooves is determined by the following parameter formula:
wherein l is the length of the linear groove;
r is the radius of the steel ball;
R 1 -the radius of the distribution circle of the linear grooves.
The length l of the straight-line slot is determined by the following parameter equation:
l>2r+e；
wherein r is the radius of the steel ball;
e-eccentricity of input shaft.
In fig. 13, the uniform distribution of the linear grooves improves the uniformity of load distribution among the linear grooves and the operation stability of the speed reducer, and reduces vibration; through the uniform and equidistant distribution of each linear groove, the distribution circular space of the linear grooves is fully utilized, the number of the linear grooves is greatly increased, and the load on a single linear groove is reduced. Therefore, the reinforced robot joint speed reducing device strengthens the weak link of the cross steel ball constant-speed transmission mechanism, and enhances the bearing capacity of the speed reducing device.
Referring to fig. 14 and 15, the present invention is applied to two applications of the robot joint reduction gear.
Referring to fig. 14, in this embodiment, the housing 5 and the motor 18 are both fixed to the fixed end of the robot joint. The power of the motor 18 is input by the input shaft 15 and is transmitted to the planetary plate 9 through the cylindrical roller bearing 17 on the input shaft. In this embodiment, the housing 5 is fixed, and the end cover 13 and the end cover disk 12 fixed to the housing 5 are also fixed against rotation. Therefore, the reinforced cross steel ball constant speed transmission mechanism formed by the planetary plate 9, the cross plate 11, the steel ball group 10 and the end cover plate 12 can limit the self-rotation movement of the planetary plate 9, so that the planetary plate 9 only moves in translation along with the self-rotation of the input shaft 15. The planetary plate 9, the steel ball 8 and the central plate 7 form an enhanced cycloid steel ball gear pair, and the planetary plate 9 pushes the central plate 7 to rotate at a lower speed through the steel ball group 8. The flange 3 is fixedly connected to the central disk 7 through a screw group and can rotate at a low speed along with the central disk 7. The flange 3 is fixedly connected with the rotating end of the robot joint, so that the robot joint is driven to rotate.
Referring to fig. 15, in this embodiment, the flange 3 and the motor 18 are both fixed at the fixed end of the robot joint. The power of the motor 18 is input by the input shaft 15 and is transmitted to the planetary disk 9 through the cylindrical roller bearing 17 thereon. In this embodiment, the flange 3 is fixed, so that the central disk 7 fixed to the flange 3 is also not rotatable. Therefore, the planetary plate 9 is restrained by the central plate 7 to rotate at a low speed under the action of the enhanced cycloid steel ball gear pair. The low-speed rotation of the planetary disk 9 is transmitted to the end cover disk 12 at a constant speed through the enhanced cross steel ball constant-speed transmission mechanism. The shell 5 is fixedly connected with the end cover 13 and the end cover disc 12 through screw groups and can rotate at a low speed along with the end cover disc 12. The shell 5 is fixedly connected with the rotating end of the robot joint, so that the robot joint is driven to rotate.
The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.
Claims (8)
1. A cycloidal steel ball planetary transmission mechanism is characterized in that: comprises a planetary plate (9), a central plate (7) and a steel ball group (8), wherein a gap d is reserved between steel balls in the steel ball group, and d = Z 0 (h + Delta)/2 pi, wherein Z 0 The number of steel balls in the steel ball group; h is the thickness of the lubricating grease among the steel balls; and delta is the gauge value of the steel ball.
2. The cycloid steel ball planetary transmission mechanism of claim 1, characterized in that: the tooth grooves on the end surface of the planetary plate (9) adopt a parameter-containing combination Z 0 The modified epicycloid tooth profile of (h + delta)/2 pi has the following equation:
in the formula R 0 -the steel ball groups are distributed with a circular radius;
Z 0 -the number of steel balls of the steel ball set;
h is the thickness of the lubricating grease between the steel balls;
delta-gauge of steel ball;
k is the coefficient of cycloid minor amplitude;
r 0 -cycloid generating circle radius;
θ 1 the epicycloid forms an angle.
3. The cycloidal steel ball planetary transmission according to claim 2, wherein: the tooth grooves on the end surface of the central disc (7) adopt a parameter-containing combination Z 0 The shape-modifying hypocycloid tooth profile of (h + delta)/2 pi has the following equation:
in the formula R 0 -the steel ball groups are distributed with a circular radius;
Z 0 -the number of steel balls of the steel ball set;
h is the thickness of the lubricating grease between the steel balls;
delta-gauge of steel ball;
k is the coefficient of cycloid minor amplitude;
r 0 -cycloid generating circle radius;
θ 2 the hypocycloid creates an angle.
4. The cycloidal steel ball planetary transmission according to claim 3, characterised in that: the parameters of the shape-modifying epicycloid tooth profile equation and the shape-modifying hypocycloid tooth profile equation are constrained by the condition of no undercut, and the condition of no undercut is as follows:
wherein r is the radius of the steel ball;
R 0 -the steel ball sets are distributed with a circle radius;
Z 0 -the number of steel balls of the steel ball set;
k is the coefficient of cycloid minor amplitude;
Z 1 -the number of teeth in the tooth socket on the end face of the planet carrier;
beta is the flute angle of the gullet.
5. A robot joint decelerator is characterized in that: the cycloidal steel ball planetary transmission mechanism comprises a cross steel ball constant-speed transmission mechanism and the cycloidal steel ball planetary transmission mechanism in any one of claims 1 to 4, wherein the cross steel ball constant-speed transmission mechanism mainly comprises a planetary disc (9), a cross disc (11), an end cover disc (12) and a steel ball group (10).
6. The robot joint decelerating device according to claim 5, wherein: the straight line grooves on the matched end surfaces of the planetary plate (9), the cross plate (11) and the end cover plate (12) are uniformly and equidistantly distributed on the distribution circle.
7. The apparatus according to claim 6, wherein: the number n of linear grooves is determined by the parameter formula:
wherein l is the length of the linear groove;
r is the radius of the steel ball;
R 1 -the radius of the distribution circle of the linear grooves.
8. The apparatus according to claim 7, wherein: the length l of the linear slot is determined by the parameter formula:
l>2r+e；
wherein r is the radius of the steel ball;
e-eccentricity of input shaft.
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| CN201721030745.8U CN207093681U (en) | 2017-08-17 | 2017-08-17 | A kind of Cycloid Steel Ball Planetary Transmission mechanism and its joint of robot deceleration device |
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| CN201721030745.8U CN207093681U (en) | 2017-08-17 | 2017-08-17 | A kind of Cycloid Steel Ball Planetary Transmission mechanism and its joint of robot deceleration device |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN107299970A (en) * | 2017-08-17 | 2017-10-27 | 安徽捷线传动科技有限公司 | A kind of cycloidal ball deceleration device and its application in joint of robot |
| CN107327543A (en) * | 2017-08-17 | 2017-11-07 | 安徽捷线传动科技有限公司 | A kind of Cycloid Steel Ball Planetary Transmission mechanism and its joint of robot deceleration device |
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| CN111237398A (en) * | 2020-03-15 | 2020-06-05 | 河南烛龙高科技术有限公司 | Single-stage close-packed combined tooth surface cycloid oscillating tooth transmission unit |
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| CN107299970A (en) * | 2017-08-17 | 2017-10-27 | 安徽捷线传动科技有限公司 | A kind of cycloidal ball deceleration device and its application in joint of robot |
| CN107327543A (en) * | 2017-08-17 | 2017-11-07 | 安徽捷线传动科技有限公司 | A kind of Cycloid Steel Ball Planetary Transmission mechanism and its joint of robot deceleration device |
| CN107327543B (en) * | 2017-08-17 | 2023-10-20 | 安徽一众精密轴业有限公司 | Cycloid steel ball planetary transmission mechanism and robot joint speed reducer thereof |
| CN107299970B (en) * | 2017-08-17 | 2024-03-15 | 安徽一众精密轴业有限公司 | Cycloidal steel ball speed reducer and application thereof in robot joint |
| CN109707802A (en) * | 2019-02-25 | 2019-05-03 | 燕山大学 | A kind of twin-stage integrated planar movable teeth reducer based on saddle coupling |
| CN109707802B (en) * | 2019-02-25 | 2020-12-22 | 燕山大学 | Two-stage integrated plane oscillating tooth speed reducer based on guide frame coupling |
| CN111173896A (en) * | 2020-01-06 | 2020-05-19 | 河南烛龙高科技术有限公司 | Single-stage undercut cycloid oscillating tooth transmission unit |
| CN111237397A (en) * | 2020-03-15 | 2020-06-05 | 河南烛龙高科技术有限公司 | Two-tooth differential close-packed combined tooth surface cycloid oscillating tooth transmission unit |
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