CN109458441B

CN109458441B - Cam type wave generator

Info

Publication number: CN109458441B
Application number: CN201811382706.3A
Authority: CN
Inventors: 庄剑毅; 刘青; 汤秀清
Original assignee: Guangzhou Haozhi Electromechanical Co Ltd
Current assignee: Guangzhou Haozhi Electromechanical Co Ltd
Priority date: 2018-11-20
Filing date: 2018-11-20
Publication date: 2021-01-08
Anticipated expiration: 2038-11-20
Also published as: CN109458441A

Abstract

The invention disclosesA cam type wave generator comprises a cam and a flexible bearing sleeved on the cam, wherein the polar coordinate equation of the cam contour line of the cam is as follows: phi is more than or equal to 0 and less than or equal to beta-beta₁Interval ρ_Δ＝r+[ω₀ ^*m/(A‑4/π)][Acosψ+ψsinβsinψ‑4/π](ii) a In beta-beta₁Interval phi ≤ psi ≤ beta, rho_Δ＝r+[ω₀ ^*m/(A‑4/π)][Acosψ+ψsinβsinψ‑4/π]+0.5Δ₀{1+cos[π(ψ‑β)/β₁]}; beta is not less than psi not more than beta + beta₂Interval ρ_Δ＝r+[ω₀ ^*m/(A‑4/π)][Bsinψ+(π/2‑ψ)cosβcosψ‑4/π]+0.5Δ₀{1+cos[π(ψ‑β)/β₂]}; at beta + beta₂Phi is not less than 90 interval, rho_Δ＝r+[ω₀ ^*m/(A‑4/π)][Bsinψ+(π/2‑ψ)cosβcosψ‑4/π](ii) a The modified four-force action cam profile is adopted, the bearing capacity, the efficiency and the service life of the whole harmonic reducer are improved, and the deformation and stress conditions of the flexible bearing are improved by correcting the shape of the cam profile curve at the action of the force F; by optimizing the parameter value of the convex profile curve, the stress value and the meshing quality of the flexible gear are improved.

Description

Cam type wave generator

Technical Field

The invention relates to a wave generator, in particular to a cam-type wave generator.

Background

The harmonic reducer is a transmission device which uses the wave generator to make the flexible gear generate controllable elastic deformation wave, and realizes motion and power transmission by the interaction with the rigid gear. The wave generator is a component which makes the flexible gear generate continuous deformation wave, and the form and geometric parameters of the wave generator not only determine the shape of the original curve of the harmonic gear drive, but also have important influence on the meshing performance of the drive and the strength of the flexible gear.

The wave generators may be classified into various types of wave generators, such as a cam type, a roller type, and a disc type, according to the structure. The cam type wave generator can enable the meshing of the flexible gear and the rigid gear to reach an ideal state, and has stable operation, high precision and higher efficiency; and because the stress distribution state in the flexible gear is improved, the bearing capacity is high, and the flexible gear is suitable for transmission with higher requirement on transmission precision. At present, the harmonic reducer mainly adopts a cam type wave generator.

The cam type wave generator is composed of a cam designed and made according to the motion rule of flexible wheel deformation wave, and a flexible bearing capable of working in a deformation state is sleeved on the outer surface of the cam. The deformation shape and the deformation amount of the cam directly determine the deformation shape and the deformation amount of the flexible gear, and are very important for the working capacity of the whole harmonic reducer, so the design of the cam profile is the main content of the design of the cam type wave generator.

Currently, the most widely used are the cosine cam profile and the four force action cam profile. The four-force action cam profile can improve the stress value and the meshing quality of the flexible gear by changing the action angle (marked as beta) of the force F, and is better than a cosine cam in overall performance. However, the four-force action cam profile has the disadvantage that the wear of the compliant bearings increases at the point of action of the force F, and the overall life of the harmonic reducer is dependent on the life of the compliant bearings, and therefore this disadvantage is very detrimental to the efficiency and life of the overall machine.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a cam-type wave generator with high use efficiency and long service life.

The purpose of the invention is realized by adopting the following technical scheme:

a cam type wave generator comprises a cam and a flexible bearing sleeved on the cam, wherein the polar coordinate equation of the cam contour line of the cam is as follows: phi is more than or equal to 0 and less than or equal to beta-beta₁Interval ρ_Δ＝r+[ω₀ ^*m/(A-4/π)][Acosψ+ψsinβsinψ-4/π](ii) a In beta-beta₁Interval phi ≤ psi ≤ beta, rho_Δ＝r+[ω₀ ^*m/(A-4/π)][Acosψ+ψsinβsinψ-4/π]+0.5Δ₀{1+cos[π(ψ-β)/β₁]}; beta is not less than psi not more than beta + beta₂Interval ρ_Δ＝r+[ω₀ ^*m/(A-4/π)][Bsinψ+(π/2-ψ)cosβcosψ-4/π]+0.5Δ₀{1+cos[π(ψ-β)/β₂]}; at beta + beta₂Phi is not less than 90 interval, rho_Δ＝r+[ω₀ ^*m/(A-4/π)][Bsinψ+(π/2-ψ)cosβcosψ-4/π](ii) a Wherein, A is sin beta + (pi/2-beta) cos beta; b ═ cos β + β sin β; r is the flexspline radius; m is the flexible gear modulus; omega₀ ^*The maximum radial deformation coefficient; delta₀Defining a numerical value for the extreme value of the correction quantity according to the design requirement; beta is the force action angle; beta is a₁A correction range near the major axis; beta is a₂Is the correction range near the minor axis.

Further, ω is₀ ^*＝ω₀M, wherein ω₀Is the maximum radial deflection.

Further, when the structural length-diameter ratio k of the flexible gear is>0.4, number of teeth Z>130, ω₀ ^*1.0 to 1.3, beta is 25 to 35 degrees, delta₀Is (0.01 to 0.04) omega₀ ^*m，β₁Is 5-beta, beta₂Is 5-40 degrees.

Further, when the structural length-diameter ratio k of the flexible gear is>0.4, number of teeth Z>130, ω₀ ^*1.1 to 1.2, beta is 25 to 30 degrees, delta₀Is (0.02-0.03) omega₀ ^*m，β₁Is 20-beta, beta₂Is 20-40 degrees.

Further, when the structural length-diameter ratio k of the flexible gear is>0.4, when the number of teeth Z is less than or equal to 130, omega₀ ^*0.7 to 1.0, beta is 25 to 35 degrees, delta₀Is (0.01 to 0.04) omega₀ ^*m，β₁Is 5-beta, beta₂Is 5-40 degrees.

Further, when the structural length-diameter ratio k of the flexible gear is>0.4, when the number of teeth Z is less than or equal to 130, omega₀ ^*0.8 to 0.9, beta is 30 to 35 degrees, delta₀Is (0.02-0.03) omega₀ ^*m，β₁Is 20-beta, beta₂Is 20-40 degrees.

Further, when the structural length-diameter ratio k of the flexible gear is less than or equal to 0.4 and the tooth number Z is less than or equal to 0.4>130, ω₀ ^*1.0 to 1.3, beta is 15 to 25 degrees, delta₀Is (0.01-0.03) omega₀ ^*m，β₁Is 5-beta, beta₂Is 5-40 degrees.

Further, when the structural length-diameter ratio k of the flexible gear is less than or equal to 0.4 and the tooth number Z is less than or equal to 0.4>130, ω₀ ^*1.2 to 1.3, beta is 20 to 25 degrees, delta₀Is (0.01-0.02) omega₀ ^*m，β₁Is 10-beta, beta₂Is 20-40 degrees.

Further, when the structural length-diameter ratio k of the flexible gear is less than or equal to 0.4 and the tooth number Z is less than or equal to 130, omega₀ ^*Is 0.7 to 1.0, beta is 15 to 25 degrees, delta₀Is (0.01-0.03) omega₀ ^*m，β₁Is 5-beta, beta₂Is 5-40 degrees.

Further, when the structural length-diameter ratio k of the flexible gear is less than or equal to 0.4 and the tooth number Z is less than or equal to 130, omega₀ ^*Is 0.8 to 0.9, beta is 15 to 20 degrees, delta₀Is (0.01-0.02) omega₀ ^*m，β₁Is 10-beta, beta₂Is 20-40 degrees.

Compared with the prior art, the cam of the cam type wave generator adopts the modified four-force action cam profile to improve the bearing capacity, efficiency and service life of the whole harmonic reducer, and the deformation and stress conditions of the flexible bearing are improved by modifying the shape of the cam profile curve at the action of the force F; by optimizing the parameter value of the convex profile curve, the stress value and the meshing quality of the flexible gear are improved.

Drawings

FIG. 1 is a schematic view of a prior art lobed wave generator;

FIG. 2 is a simplified schematic diagram of a flexspline thin-walled ring;

FIG. 3 is a cam profile of the cam wave generator of FIG. 1 under four forces;

FIG. 4 is a front and rear comparative view of a cam profile modification of a cam of the cam wave generator of the present invention;

FIG. 5 is an enlarged view of FIG. 4 at cam wave generator A;

fig. 6 is a polar coordinate comparison before and after a first quadrant cam profile modification of the cam generator of fig. 4.

In the figure: 10. a cam; 20. a compliant bearing; 30. a flexible gear.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the prior art, as shown in fig. 1, a cam type wave generator is composed of a cam 10 designed and manufactured according to the motion law of a deformation wave of a flexible gear 30, and a flexible bearing 20 capable of working in a deformation state is sleeved outside the cam 10. The deformed shape and amount of deformation of the cam 10 directly determine the deformed shape and amount of deformation of the flexspline 30, and are important to the operation capability of the entire harmonic reducer.

In the prior art, the four force action cam profile is expressed as follows: the flexspline 30 can be viewed as a thin-walled ring (as shown in fig. 2), which is a ring with a thickness δ much smaller than the radius r, and the circle with the radius r is the neutral radius of the ring and is located in the middle of the thickness of the ring. When the thin-wall circular ring is deformed under stress, the length of the neutral circle is kept unchanged. As shown in fig. 3 (the thin-walled ring is simplified to a circle), the thin-walled ring is deformed by four forces F with an included angle β, the neutral circle is deformed accordingly, and the deformed neutral circle is a four-force-acting cam profile. During the deformation process, the intersection point of the neutral circle and the X axis deforms the most in the radial direction, and is called as the maximum radial deformation amount omega₀(ii) a Radial deformation omega and omega of other points (with an included angle phi with the X axis) on the neutral circle₀The relationship of (a) to (b) is as follows:

in the interval of psi is more than or equal to 0 and less than or equal to beta,

ω＝[ω₀/(A-4/π)][Acosψ+ψsinβsinψ-4/π] (1)

wherein, A is sin beta + (pi/2-beta) cos beta; b ═ cos β + β sin β; omega₀The maximum radial deflection; omega is radial deformation omega; beta is the angle of force.

In the interval that beta is less than or equal to psi is less than or equal to 90,

ω＝[ω₀/(A-4/π)][Bsinψ+(π/2-ψ)cosβcosψ-4/π] (2)

wherein, A is sin beta + (pi/2-beta) cos beta; b ═ cos β + β sin β; omega₀The maximum radial deflection; omega is radial deformation; beta is the angle of force.

The included angle between the neutral circle upper point P and the X axis before deformation is ═ POX, the point P 'reaching the cam profile after deformation can be considered to be constant in engineering application, namely the included angle ═ P' OX ═ POX.

At the same time, ω₀The ratio of the modulus m of the flexspline 30 to the maximum radial deformation coefficient ω₀ ^*Namely:

ω₀＝ω₀ ^*m (3)

thus, the polar equation for the four force action cam profile can be expressed as:

ρ＝r+[ω₀ ^*m/(A-4/π)][Acosψ+ψsinβsinψ-4/π] (4)

wherein, A is sin beta + (pi/2-beta) cos beta; m is the modulus of the flexspline 30; omega₀ ^*The maximum radial deformation coefficient; beta is the included angle of force; r is the radius of the flexspline 30.

ρ＝r+[ω₀ ^*m/(A-4/π)][Bsinψ+(π/2-ψ)cosβcosψ-4/π] (5)

wherein, B is cos beta + beta sin beta; m is the modulus of the flexspline 30; omega₀ ^*The maximum radial deformation coefficient; beta is the included angle of force; r is the radius of the flexspline 30.

In general, when designing the cam profile, r and m are known, by adjusting ω₀ ^*And β, the shape of the cam profile can be changed to ultimately adjust the compliance 30 deformation, stress level, and engagement quality.

In the present invention, based on the existing four-force action cam profile, the angle beta is used as a reference, and a certain range of [ -beta 1, beta 2 ] is set on two sides of the cam profile]The curve point (b) is subjected to local radial deformation correction, and if the correction amount is Δ, the corrected four-force action cam profile is: rho_Δ＝ρ+Δ。

By using cosine correction, Δ is designed as follows:

phi is more than or equal to 0 and less than or equal to beta-beta₁Interval, Δ ═ 0;

in beta-beta₁A range of phi < psi > beta < delta > 0.5 delta₀{1+cos[π(ψ-β)/β₁]} (6)

Beta is not less than psi not more than beta + beta₂Interval, Δ ═ 0.5 Δ₀{1+cos[π(ψ-β)/β₂]} (7)

At beta + beta₂The phi is not less than 90, and delta is 0;

wherein, Delta₀Defining a numerical value for the extreme value of the correction quantity according to the design requirement; beta is a₁To approximate the correction range of the major axis, β₂Is the correction range near the minor axis.

The polar equation for the modified four-force action cam profile may then be expressed as:

phi is more than or equal to 0 and less than or equal to beta-beta₁The interval of time is,

ρ_Δ＝r+[ω₀ ^*m/(A-4/π)][Acosψ+ψsinβsinψ-4/π]； (8)

In beta-beta₁The psi is not less than the beta,

ρ_Δ＝r+[ω₀ ^*m/(A-4/π)][Acosψ+ψsinβsinψ-4/π]+0.5Δ₀{1+cos[π(ψ-β)/β₁]}； (9)

wherein, A is sin beta + (pi/2-beta) cos beta; m is the modulus of the flexspline 30; omega₀ ^*The maximum radial deformation coefficient; beta is the included angle of force; r is the radius of the flexspline 30; delta₀Is a correction extreme value; beta is a₁A correction range near the long axis.

Beta is not less than psi not more than beta + beta₂The interval of time is,

ρ_Δ＝r+[ω₀ ^*m/(A-4/π)][Bsinψ+(π/2-ψ)cosβcosψ-4/π]+0.5Δ₀{1+cos[π(ψ-β)/β₂]}； (10)

wherein, B is cos beta + beta sin beta; m is the modulus of the flexspline 30; omega₀ ^*The maximum radial deformation coefficient; beta is the included angle of force; r is the radius of the flexspline 30; delta₀Is a correction extreme value; beta is a₂Is the correction range near the minor axis.

At beta + beta₂The psi is not less than 90,

ρ_Δ＝r+[ω₀ ^*m/(A-4/π)][Bsinψ+(π/2-ψ)cosβcosψ-4/π]； (11)

When designing the cam profile, r and m are known, and the shape of the cam profile is determined completely, andneeds to determine omega₀ ^*、β、Δ₀、β₁、β₂And the values of the 5 parameters are equal. The values of these parameters are related to the structural aspect ratio k (as shown in fig. 1, k ═ d/L) and the number of teeth Z of the flexspline 30, and the preferred ranges are shown in table 1.

TABLE 1

The optimum value ranges are shown in table 2.

TABLE 2

The effect of the modified four force action cam profile is illustrated below.

Taking a harmonic reducer of a certain specification as an example, it is known that k is 0.5 > 0.4, Z is 100, r is 40, and m is 0.8;

according to Table 2, ω₀ ^*、β、Δ₀、β₁、β₂The values of the 5 parameters are as follows:

ω₀ ^*＝0.9，β＝30°，Δ₀＝0.02·ω₀ ^*·m＝0.014，β₁＝20°，β₂＝30°。

according to the equations 4 and 5, the cam profile equation before repair is obtained as follows:

ρ＝40+[0.9*0.8/(1.407-4/π)][1.407*cosψ+ψsin30°*sinψ-4/π],ψ∈[0,30°]；

ρ＝40+[0.9*0.8/(1.407-4/π)][1.128*sinψ+(π/2-ψ)cos30°*cosψ-4/π],ψ∈[0,β]。

wherein, A is 30 degree (+ (pi/2-30 degree)) cos30 degree is 1.407,

B＝cos30°+30°sin30°＝1.128。

an unmodified cam profile and unmodified cam polar coordinates can be derived.

According to the following formula:

ρ_Δ＝40+[0.9*0.8/(1.407-4/π)][1.407*cosψ+ψsin30°sinψ-4/π]，ψ∈[0,10°]；

ρ_Δ＝40+[0.9*0.8/(1.407-4/π)][1.407*cosψ+ψsin30°sinψ-4/π]+0.5*0.014*{1+cos[π(ψ-30°)/20°]}，ψ∈[10°，30°]；

ρ_Δ＝r+[0.9*0.8/(1.407-4/π)][1.128*sinψ+(π/2-ψ)cos30°*cosψ-4/π]+0.5*0.014*{1+cos[π(ψ-30°)/30°]}，ψ∈[30°，60°]；

ρ_Δ＝40+[0.9*0.8/(1.407-4/π)][1.128*sinψ+(π/2-ψ)cos30°*cosψ-4/π]，ψ∈[60°，90°]；

wherein the content of the first and second substances,

A＝sin30°+(π/2-30°)cos30°＝1.407,

B＝cos30°+30°sin30°＝1.128。

the cam profile after the modification and the polar coordinates of the cam after the modification can be obtained.

In summary, the modified cam profile front-rear pair is shown in fig. 4 and 5, and the modified first quadrant cam front-rear polar coordinates (with the unmodified cam profile as the reference) are shown in fig. 6.

The invention improves the deformation and stress conditions of the flexible bearing 20 by correcting the convex profile curve shape of the action of the force F; meanwhile, the stress value and the meshing quality of the flexible gear 30 are improved by optimizing the parameter value of the convex profile curve; therefore, the bearing capacity and the service life of the whole harmonic reducer are greatly improved, and meanwhile, the transmission efficiency is also improved slightly.

Various other modifications and changes may be made by those skilled in the art based on the above-described technical solutions and concepts, and all such modifications and changes should fall within the scope of the claims of the present invention.

Claims

1. A cam-type wave generator comprises a cam and a flexible bearing sleeved on the cam, and is characterized in that: the polar coordinate equation of the cam profile line of the cam is as follows:

phi is more than or equal to 0 and less than or equal to beta-beta₁Interval ρ_Δ＝r+[ω₀ ^*m/(A-4/π)][Acosψ+ψsinβsinψ-4/π]；

In beta-beta₁Interval phi ≤ psi ≤ beta, rho_Δ＝r+[ω₀ ^*m/(A-4/π)][Acosψ+ψsinβsinψ-4/π]+0.5Δ₀{1+cos[π(ψ-β)/β₁]}；

Beta is not less than psi not more than beta + beta₂Interval ρ_Δ＝r+[ω₀ ^*m/(A-4/π)][Bsinψ+(π/2-ψ)cosβcosψ-4/π]+0.5Δ₀{1+cos[π(ψ-β)/β₂]}；

At beta + beta₂Phi is not less than 90 interval, rho_Δ＝r+[ω₀ ^*m/(A-4/π)][Bsinψ+(π/2-ψ)cosβcosψ-4/π]；

Wherein, A is sin beta + (pi/2-beta) cos beta; b ═ cos β + β sin β; r is the flexspline radius; m is the flexible gear modulus; omega₀ ^*The maximum radial deformation coefficient; delta₀Defining a numerical value for the extreme value of the correction quantity according to the design requirement; beta is the force action angle; beta is a₁A correction range near the major axis; beta is a₂A correction range near the minor axis; psi is the included angle between the upper point of the contour line and the X axis; rho_ΔThe corrected four force application cam profile.

2. The cam-type wave generator of claim 1, wherein: the omega₀ ^*＝ω₀M, wherein ω₀Is the maximum radial deflection.

3. The cam-type wave generator of claim 1, wherein: when the structural length-diameter ratio k of the flexible gear is>0.4, number of teeth Z>130, ω₀ ^*1.0 to 1.3, beta is 25 to 35 degrees, delta₀Is (0.01 to 0.04) omega₀ ^*m，β₁Is 5-beta, beta₂Is 5-40 degrees.

4. The cam-type wave generator of claim 3, wherein: when the structural length-diameter ratio k of the flexible gear is>0.4, number of teeth Z>130, ω₀ ^*1.1 to 1.2, beta is 25 to 30 degrees, delta₀Is (0.02-0.03) omega₀ ^*m，β₁Is 20-beta, beta₂Is 20-40 degrees.

5. The cam-type wave generator of claim 1, wherein: when the structural length-diameter ratio k of the flexible gear is>0.4, when the number of teeth Z is less than or equal to 130, omega₀ ^*0.7 to 1.0, beta is 25 to 35 degrees, delta₀Is (0.01 to 0.04) omega₀ ^*m，β₁Is 5-beta, beta₂Is 5-40 degrees.

6. The cam-type wave generator of claim 5, wherein: when the structural length-diameter ratio k of the flexible gear is>0.4, when the number of teeth Z is less than or equal to 130, omega₀ ^*0.8 to 0.9, beta is 30 to 35 degrees, delta₀Is (0.02-0.03) omega₀ ^*m，β₁Is 20-beta, beta₂Is 20-40 degrees.

7. The cam-type wave generator of claim 1, wherein: when the structural length-diameter ratio k of the flexible gear is less than or equal to 0.4, the number of teeth Z>130, ω₀ ^*1.0 to 1.3, beta is 15 to 25 degrees, delta₀Is (0.01-0.03) omega₀ ^*m，β₁Is 5-beta, beta₂Is 5-40 degrees.

8. The cam-type wave generator of claim 7, wherein: when the structural length-diameter ratio k of the flexible gear is less than or equal to 0.4, the number of teeth Z>130, ω₀ ^*1.2 to 1.3, beta is 20 to 25 degrees, delta₀Is (0.01-0.02) omega₀ ^*m，β₁Is 10-beta, beta₂Is 20-40 degrees.

9. The cam-type wave generator of claim 1, wherein: when the structural length-diameter ratio k of the flexible gear is less than or equal to 0.4 and the tooth number Z is less than or equal to 130, omega₀ ^*Is 0.7 to 1.0, beta is 15 to 25 degrees, delta₀Is (0.01-0.03) omega₀ ^*m，β₁Is 5-beta, beta₂Is 5-40 degrees.

10. The cam-type wave generator of claim 9, wherein: when the structural length-diameter ratio k of the flexible gear is less than or equal to 0.4 and the tooth number Z is less than or equal to 130, omega₀ ^*Is 0.8 to 0.9, beta is 15 to 20 degrees, delta₀Is (0.01-0.02) omega₀ ^*m，β₁Is 10-beta, beta₂Is 20-40 degrees.