A new flexible spline and wave generator assembly for harmonic gear transmission

Abstract

A new type of flexible spline and wave generator assembly for harmonic gear transmission, the assembly can overcome the following technical and quality problems existing in the existing flexible spline and wave generator assembly due to the use of special-shaped ferrule flexible bearings: (1) The outer ring of the flexible bearing slips relative to the flexible wheel, causing the speeds of the two to be incompletely synchronized; (2) The outer ring of the flexible bearing made of bearing steel breaks and fails under the repeated action of alternating bending stress; (3) The precision after processing When the higher flexible bearing is installed on the cam with interference, the groove shape will be distorted, the geometrical and shape accuracy will be greatly reduced, and the compressive stress formed on the working surface will become tensile stress during processing; (4) the ball of the flexible bearing is the same The raceway of the outer ring is a single-point contact, which causes the flexspline teeth to undergo predetermined radial deformation, and at the same time, there is additional warping along the tooth width direction and additional twisting deformation along the circumferential direction, all of which make the assembly have higher transmission accuracy , operational reliability and longer service life.

Description

technical field [0001] The invention relates to a novel flexspline and wave generator assembly for a harmonic gear drive, in particular to a flexspline and wave generator assembly including a flexible bearing with a special-shaped ring and a flexible bearing with a special-shaped ring. Background technique [0002] Harmonic gear transmission is an assembly that relies on the elastic deformation of the intermediate flexible member to achieve movement or power transmission. Because the deformation process of the intermediate flexible member is basically a symmetrical harmonic, it is named, and it is more common than general gear transmission. , it has outstanding advantages such as large transmission ratio, transmission in confined space, small size, light weight, strong carrying capacity, high transmission precision, stable transmission and low noise. It is widely used in aerospace, radar systems, optical machinery, industrial robots, weapon systems, etc. It is more and more ...

AI Technical Summary

Problems solved by technology

[0005] The cam and the inner circle surface of the flexible bearing inner ring have an interference fit, because the cam surface has a wave profile (for example, the double wave transmission is an ellipse, unless otherwise specified below, the double wave transmission and the elliptical profile are taken as examples by default. ), so after installation, the inner ring of the bearing whose cross-section is high-precision circular is forced to become elliptical, which leads to the following problems: (1) The state of compressive stress on the raceway surface of the inner ring changes from the original state of compressive stress after processing to Tensile stress state; (2) The wall thickness difference between the channel and the inner circular surface and the depth difference with the channel rib increase exponentially; (3) The precise arc shape of the bearing channel section is destroyed, and the grooves at different positions The cross-sectional shape of the track is no longer the same, including the groove width and groove depth. The ideal contact state between the ball and the original ideal circular arc channel no longer exists, and the contact state between the ball and the channel is no longer the same; (4) along the inner ring The amount of interference between each part of the circular surface and the cam is not the same. For example, the interference is the largest at both ends of the major axis of the ellipse, and clearance fit may occur at both ends of the minor axis of the ellipse, which also affects the trajectory of the ball. the accuracy of

[0006] While the inner ring of the flexible bearing and the installation of the cam are forced to become elliptical, the center distribution shape of each ball and the outer ring are also forced to change from ideal circular to elliptical. After the outer circular surface of the elliptical outer ring is assembled with the flexible spline The flexspline is also forced to become elliptical. Since the wall of the flexspline is very thin, in order to prevent unintended additional deformation caused by installation, the gap between the flexspline and the outer surface of the outer ring of the flexible bearing (when they are all circular) It is often designed as a small gap or transition fit, which leads to the following problems: (1) Since the fit between the outer ring and the flexspline cannot be too tight, there is a problem of deformation inconsistency between the outer figure and the flexspline when using different steel types, After working for a period of time, there will be relative rotation between the outer ring and the flexible spline, which will cause fretting wear and corrosion of the mating surface, and reduce the transmission accuracy of the harmonic reducer; (2) The outer ring of the bearing is generally made of bearing steel , the hardness of the outer ring is sufficient but the toughness is insufficient. Under the repeated action of bending stress during work, the outer ring is prone to fracture and failure

[0008] In addition, the outer ring and inner ring of the flexible bearing are very thin and narrow, and are easily deformed during machining and heat treatment, resulting in increased processing costs and difficulty in obtaining high processing accuracy

[0009] The above-mentioned problems in the flexspline and wave generator assembly and the components in the assembly will eventually lead to a decrease in the accuracy, efficiency, and operating life of the harmonic gear transmission. Therefore, it is urgent to develop a new type of flexspline and wave generator assembly , to overcome many principle technical and quality limitations of current components, and substantially improve the accuracy and operational reliability of harmonic gear transmissions

Images