Hat-type harmonic flexible gear with composite modified gear teeth

Abstract

The invention discloses a hat-type harmonic flexible gear with composite modified gear teeth. The gear teeth of a cylindrical gear of the hat-type harmonic flexible gear are subjected to radial modification and tooth modification at the same time. The pitch circle line of the gear teeth of the flexible gear after radial modification is not a straight line parallel to the rotation center of the flexible gear any more, but a section of arc with the distance from the circle center to the end face of the gear teeth being b and the radius being R; the two sides of the tooth direction of the flexible gear tooth after tooth direction modification are not straight lines any more, but are arcs with the distance from the circle center to the end face of the gear tooth being b0 and the radius being R0. The phenomenon that the two ends of the flexible gear teeth are in meshing interference with the rigid gear teeth in the axial direction and the tangential direction or cannot be meshed with the rigid gear teeth due to the influence of bending stress brought by deformation of a wave generator and gear meshing force bending moment is eliminated, and the number of tooth pairs where the hat type flexible gear teeth and the rigid gear teeth participate in meshing is increased. The meshing area of the meshing gear teeth is increased, the service life of the hat type harmonic flexible gear is prolonged, and therefore the defects in the prior art are overcome.

Description

Technical Field

[0001] The invention relates to a top-hat type harmonic flexible gear, in particular to a top-hat type harmonic flexible gear with composite modified gear teeth. Background Art

[0002] Harmonic gear drive is a gear transmission method that uses the elastic deformation of flexible gears to transmit motion or power.

[0003] Harmonic gear transmission usually consists of three basic components: a flexspline (flexible gear), a rigid wheel (rigid gear) and a wave generator. The transmission of its motion or power is achieved under the action of the wave generator, which forces the flexspline to continuously produce elastic deformation and interact with the rigid wheel to achieve the purpose of transmission.

[0004] The working principle of harmonic gear transmission is: when the cam wave generator with a flexible bearing is installed into the inner hole of the thin-walled flexible wheel, the thin-walled flexible wheel is forced to produce elastic deformation, and the gear teeth at both ends of its long axis are fully meshed with the gear teeth of the rigid wheel, while they are completely disengaged at the short axis. Some of the gear teeth in different sections of the circumference between the long axis and the short axis are meshed in, and some are meshed out; when the wave generator rotates continuously, the wave generator forces the deformation of the flexible wheel to be continuously converted, and the gear teeth of the flexible wheel successively turn from meshing to meshing out, from meshing out to disengaging, from disengaging to meshing in, and from meshing in to meshing, thereby realizing the rotation of the flexible wheel relative to the rigid wheel in the opposite direction of the wave generator.

[0005] In the harmonic gear transmission, the harmonic flexspline works under the state of repeated elastic deformation. It is not only subject to the bending stress caused by the deformation of the wave generator, but also the flexspline body is affected by the gear meshing force and bending moment.

[0006] At present, the flexible gears in harmonic gear transmission mainly include three structural forms: thin-walled straight cylinder type, cup type and top hat type. Since the increase in stress of the top hat type harmonic flexible gear when the load increases is much lower than that of the thin-walled straight cylinder type and cup type flexible gears, the top hat type harmonic flexible gear is more suitable for applications under large load conditions.

[0007] Although the top-hat type harmonic flexible gear is more suitable for applications under heavy load conditions, the gears in the current top-hat type harmonic flexible gear are still generally cylindrical gears, and the pitch line of the gear teeth is parallel to the rotation center axis of the flexible gear. This top-hat type harmonic flexible gear still has the following shortcomings: 1) During use, due to the bending stress caused by the deformation of the wave generator and the influence of the gear meshing force and bending moment, the flexible wheel teeth will simultaneously undergo nonlinear axial bending deformation and torsional deformation; 2) The nonlinear axial bending and torsional deformation of the flexspline teeth will cause the two ends of the teeth of the flexspline that originally participated in the meshing to interfere with or fail to mesh with the teeth of the rigid wheel in the axial and tangential directions; 3) The meshing interference or inability to mesh with the rigid wheel teeth at both ends of the flex spline teeth in the axial and tangential directions will lead to a decrease in the number of tooth pairs and meshing area of ​​the meshing teeth between the flex spline teeth and the rigid wheel teeth, making the tooth surface prone to wear, the transmission accuracy unable to be maintained for a long time, the transmission efficiency and transmission stability reduced, and ultimately causing the flex spline to quickly fatigue and fail, reducing its service life.

[0008] Therefore, the prior art still has deficiencies and needs to be further improved. Summary of the invention

[0009] The purpose of the present invention is to provide a top-hat type harmonic flexspline with composite modified gear teeth, so as to eliminate the meshing interference or inability to mesh with the rigid wheel teeth at both ends of the flexspline teeth in the axial direction and tangential direction caused by the bending stress caused by the deformation of the wave generator and the bending moment of the gear meshing force, increase the number of tooth pairs of the top-hat type flexspline teeth and the rigid wheel teeth involved in meshing, increase the meshing area of ​​the meshing gear teeth, and extend the service life of the top-hat type harmonic flexspline, thereby overcoming the shortcomings of the prior art.

[0010] The technical solution of the present invention is: a top-hat type harmonic flexspline with composite modified gear teeth, wherein radial modification and tooth direction modification are performed on the gear teeth of the cylindrical gear of the top-hat type harmonic flexspline at the same time; after radial modification, the pitch circle line of the flexspline gear teeth is no longer a straight line parallel to the rotation center of the flexspline, but an arc with a distance b from the center of the circle to the end face of the gear tooth and a radius R; after tooth direction modification, both sides of the tooth direction of the flexspline gear teeth are no longer straight lines, but are both arcs with a distance b0 from the center of the circle to the end face of the gear tooth and a radius R0.

[0011] In the aforementioned top-hat type harmonic flex spline with composite modified gear teeth, the radius of the pitch line arc of the radially modified flex spline gear teeth is R=(2.82-3.17)D0 2 / L, the distance from the center of the arc of the pitch circle of the flexspline tooth to the end face of the tooth after radial modification is b=(0.42~0.56)B×L / D0, where: D0 is the inner hole diameter of the flexspline, L is the length of the flexspline cylinder, and B is the width of the flexspline tooth.

[0012] In the aforementioned top-hat type harmonic flex spline with composite modified gear teeth, the radius of the modified arc of the gear teeth after the gear teeth are modified is R0 = (1.38-2.12) D0 2 / L, the distance from the center of the modified arc of the flexspline tooth to the end face of the tooth after tooth modification is b0=(0.42~0.56)B×L / D0, where: D0 is the inner hole diameter of the flexspline, L is the length of the flexspline cylinder, and B is the width of the flexspline tooth.

[0013] The beneficial effects of the present invention are as follows: compared with the prior art, the present invention simultaneously performs appropriate radial modification and tooth direction modification on the gear teeth of the cylindrical gear of the top-hat type harmonic flexible wheel in the prior art; after radial modification, the flexible wheel teeth present an arc shape with a high middle and low ends in the axial direction; after tooth direction modification, the flexible wheel teeth also present an arc shape with a high middle and low ends in the tangential direction; during use, when the flexible wheel teeth undergo nonlinear axial bending deformation and torsional deformation simultaneously due to the bending stress caused by the deformation of the wave generator and the bending moment of the gear meshing force, the cylindrical gear teeth undergo simultaneous After appropriate radial modification and tooth modification, the modified flexible wheel teeth present an arc shape with a high middle and low ends in the axial direction and the tangent direction, which can make the gear teeth that originally had meshing interference no longer have meshing interference, and at the same time make the gear teeth that originally had only partial tooth surface meshing become fully meshed. Therefore, during use, the present invention can eliminate the bending stress caused by the deformation of the wave generator and the influence of the gear meshing force and bending moment, increase the number of tooth pairs that participate in the meshing of the top-hat type flexible wheel teeth and the rigid wheel teeth, increase the meshing area of ​​the meshing gear teeth, and finally achieve the purpose of extending the service life of the top-hat type harmonic flexible wheel. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram (half-section view) of a top-hat type harmonic flexible wheel with composite modified gear teeth of the present invention; Figure 2 This is a schematic diagram of the radial modification structure of the top-hat type harmonic flexspline teeth in the present invention; Figure 3 It is a schematic diagram of the tooth profile modification structure of the top-hat type harmonic flexible wheel in the present invention.

[0015] The marks in the attached figure are: B-flexible wheel tooth width, D0-flexible wheel inner hole diameter, L-flexible wheel cylinder length, R-modified wheel tooth pitch line arc radius, b-modified wheel tooth pitch line arc center to the tooth end face distance, R0-modified wheel tooth tooth arc radius, b0-modified wheel tooth tooth arc center to the tooth end face distance. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0017] The embodiment of the present invention is a top-hat type harmonic flex spline with composite modified gear teeth, which simultaneously performs appropriate radial modification and tooth profile modification on the gear teeth of the cylindrical gear of the top-hat type harmonic flex spline in the prior art. After radial modification, the pitch line of the flex spline gear teeth is no longer a straight line parallel to the rotation center of the flex spline, but an arc with a distance b from the center of the circle to the end face of the gear teeth and a radius R; after tooth profile modification, the two sides of the gear profile of the flex spline gear teeth are no longer straight lines, but are both arcs with a distance b0 from the center of the circle to the end face of the gear teeth and a radius R0.

[0018] The radius of the arc of the pitch line of the flex spline tooth after radial training is R = (2.82 ~ 3.17) D0 2 / L, the distance from the center of the arc of the pitch circle of the flexspline tooth to the end face of the tooth after radial training is b=(0.42~0.56)B×L / D0; wherein: D0 is the inner hole diameter of the flexspline, L is the length of the flexspline cylinder, and B is the width of the flexspline tooth.

[0019] The radius of the arc of the tooth modification of the flex spline after the tooth modification is R0 = (1.38 ~ 2.12) D0 2 / L, the distance from the center of the modified arc of the flexspline tooth after the tooth direction is cultivated to the end face of the tooth b0=(0.42~0.56)B×L / D0; wherein: D0 is the inner hole diameter of the flexspline, L is the length of the flexspline cylinder, and B is the width of the flexspline tooth.

[0020] After adopting the above-mentioned radial training of the present invention, the flexible wheel teeth present an arc shape with a high middle and low ends in the axial direction; after the tooth direction modification, the flexible wheel teeth also present an arc shape with a high middle and low ends in the tangential direction. During use, when the flexible wheel teeth undergo nonlinear axial bending deformation and torsional deformation simultaneously due to the bending stress caused by the deformation of the wave generator and the bending moment of the gear meshing force, since the gear teeth of the cylindrical gear undergo appropriate radial training and tooth direction modification at the same time, the modified flexible wheel teeth present an arc shape with a high middle and low ends in both the axial direction and the tangential direction, which can make the gear teeth that originally had meshing interference no longer have meshing interference, and at the same time, make the gear teeth that originally only had partial tooth surface meshing become fully meshed. Therefore, during use, the present invention can eliminate the influence of the bending stress caused by the deformation of the wave generator and the bending moment of the gear meshing force, increase the number of tooth pairs that participate in meshing between the top-hat type flexible wheel teeth and the rigid wheel teeth, increase the meshing area of ​​the meshing gear teeth, and finally achieve the purpose of extending the service life of the top-hat type harmonic flexible wheel.

[0021] During the use of the hat-shaped harmonic flexwheel, due to the bending stress caused by the deformation of the wave generator and the influence of the gear meshing force and bending moment, the flexwheel teeth will simultaneously undergo nonlinear axial bending deformation and torsional deformation. The nonlinear axial bending deformation and torsional deformation of the flexwheel teeth will cause the two ends of some of the flexwheel teeth to mesh with the rigid wheel teeth in the axial direction and tangential direction or be unable to mesh, so that the number of tooth pairs of the flexwheel teeth and the rigid wheel teeth participating in the meshing and the meshing area of ​​the meshing teeth are reduced, and finally cause the flexwheel to quickly fatigue and fail, and the service life is reduced. This is the main problem to be solved by the present invention.

[0022] Since the structural parameters of the top-hat type harmonic flexspline (flexspline tooth width B, flexspline inner hole diameter D, and flexspline cylinder length L) change under the same load, the bending stress generated by the deformation of the wave generator and the gear meshing force bending moment will also change. Therefore, the structural parameters of the top-hat type harmonic flexspline are different, and the conditions and degrees of nonlinear axial bending deformation and torsional deformation of the flexspline teeth under the action of the bending stress generated by the deformation of the wave generator and the gear meshing force bending moment during use are also different.

[0023] The present invention simultaneously performs appropriate radial shaping and tooth profile shaping on the teeth of the cylindrical gear of the top-hat type harmonic flexspline, and the flexspline teeth after shaping present an arc shape with a high middle and low ends in both the axial direction and the tangent direction.

[0024] The above-mentioned shaping parameters fully consider the influence of the structural parameters of the top-hat type harmonic flexspline (flexspline tooth width B, flexspline inner hole diameter D, flexspline body length L) on the axial bending deformation and torsional deformation of the flexspline teeth. They are initially determined after computer simulation based on the establishment of a mathematical model, and the final result is relatively understood after further correction of the value range after several physical prototype tests: R = (2.82 ~ 3.17) D0 2 / L, b=(0.42~0.56)B×L / D0, R0=(1.38~2.12)D0 2 / L, b0=(0.42~0.56)B×L / D0, the number of tooth pairs of the flex spline teeth and the rigid wheel teeth participating in meshing is the largest, and the total meshing area of ​​the meshing teeth is also relatively the largest. When the upper and lower limits of the above value range are exceeded, the number of tooth pairs of the flex spline teeth and the rigid wheel teeth participating in meshing will decrease, and the meshing area of ​​some meshing teeth will also decrease.

Claims

1. A top-hat type harmonic flexible gear with composite modified gear teeth, characterized in that: The teeth of the cylindrical gear of the top-hat type harmonic flexspline are simultaneously modified radially and in tooth direction. After radial modification, the pitch line of the flexspline teeth is no longer a straight line parallel to the rotation center of the flexspline, but an arc with a distance b from the center of the circle to the end face of the tooth and a radius R. After in tooth direction modification, both sides of the flexspline teeth are no longer straight lines, but arcs with a distance b0 from the center of the circle to the end face of the tooth and a radius R0.

2. The top-hat type harmonic flexible gear with composite modified gear teeth according to claim 1, characterized in that: The radius of the arc of the pitch line of the flexspline tooth after radial modification is R = (2.82-3.17) D0 2 / L, the distance from the center of the arc of the pitch circle of the flexspline tooth to the end face of the tooth after radial modification is b=(0.42~0.56)B×L / D0, where: D0 is the inner hole diameter of the flexspline, L is the length of the flexspline cylinder, and B is the width of the flexspline tooth.

3. The top-hat type harmonic flexible gear with composite modified gear teeth according to claim 1, characterized in that: The radius of the arc of the tooth modification of the flex spline after the tooth modification is R0 = (1.38 ~ 2.12) D0 2 / L, the distance from the center of the modified arc of the flexspline tooth to the end face of the tooth after tooth modification is b0=(0.42~0.56)B×L / D0, where: D0 is the inner hole diameter of the flexspline, L is the length of the flexspline cylinder, and B is the width of the flexspline tooth.

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