Grinding, spraying and rolling composite surface machining method facing gear tooth surface

Abstract

The invention provides a grinding, spraying and rolling composite surface machining method for a gear tooth surface, which comprises the following steps of: determining the overall maximum elastic deformation of a gear to obtain a modified theoretical involute gear tooth profile; by means of the micro-line-segment theory, a micro-line-segment type involute gear tooth profile is obtained; by means of non-linear smooth fitting, a final modified involute gear tooth profile is obtained, and an initial gear is obtained through machining; on the basis of the initial gear, a gear shot blasting impact model is built, and a shot blasting gear is obtained; and on the basis of the shot blasting gear, a gear finishing and grinding model under gear tumbling finishing machining is built, and a finished gear is obtained. Grinding, shot blasting and barreling finishing are combined, through process coupling design, the overall performance of the gear is improved, higher manufacturing precision is achieved, the failure risk is reduced, the service life of the gear is prolonged, and the gear has the practical application value.

Description

Technical Field

[0001] The invention belongs to the technical field of gear processing, in particular to a grinding, spraying and rolling composite surface processing method for gear tooth surfaces. Background Art

[0002] In the gear transmission system, gear performance directly affects the reliability of the entire transmission system. Especially under heavy load conditions, deformation is more significant, and it is easy to have eccentric load and stress concentration at the gear end face. Therefore, it is particularly important to consider the full tooth surface modification design to reduce the eccentric load on the tooth direction and improve the fatigue strength of the tooth root.

[0003] At present, in the conventional involute gear processing, most gears are mainly surface strengthened by heat treatment and then precision ground. However, the stress of the gear tooth root processed by such conventional methods has not been improved well, resulting in poor surface performance of the processed gear, thus affecting the service life and reliability of the gear. Therefore, in combination with the requirements of the modern heavy-duty gear industry and the current production level, it is urgent and necessary to seek a grinding, shot peening and rolling composite surface processing method for gear tooth surfaces, and to improve the gear tooth surface performance while improving the meshing efficiency and service life through process coupling design of gear tooth surface modification, shot peening and surface rolling finishing. Summary of the invention

[0004] In view of the defects in the above-mentioned prior art, the present invention proposes a grinding, shot peening and rolling composite surface processing method for gear tooth surfaces. The method includes determining the maximum elastic deformation of the entire gear to obtain the theoretical involute gear tooth profile after modification; obtaining the micro-segment-like involute gear tooth profile with the help of micro-segment theory; obtaining the final modified involute gear tooth profile with the help of nonlinear smooth fitting, and processing to obtain the initial gear; constructing a gear shot peening impact model based on the initial gear to obtain a shot peening gear; constructing a gear finishing grinding model under gear rolling finishing processing based on the shot peening gear to obtain a finished gear; and detecting the tooth surface performance of the finished gear. The present invention combines grinding, shot peening and rolling finishing processing, and through process coupling design, improves the overall performance of the gear, achieves higher manufacturing accuracy, reduces the risk of failure, and extends the operating life of the gear, and has important practical application value.

[0005] The present invention provides a method for grinding, spraying and rolling composite surface processing of gear tooth surface, which comprises the following steps:

[0006] S1. Determine the maximum elastic deformation of the entire gear and obtain the theoretical involute gear tooth profile after modification;

[0007] S2. Obtaining a micro-segment-like involute gear tooth profile by means of micro-segment theory: Based on the modified theoretical involute gear tooth profile, micro-segment tooth root transition modification is performed by means of micro-segment theory to obtain a micro-segment-like involute gear tooth profile; the step S2 specifically includes the following sub-steps:

[0008] S21. Establish the gear rack coordinate system Oxy, set the intersection of the rack tooth profile and the pitch line as the origin O, and use the micro-segment theory to obtain the rack tooth profile curve equation:

[0009]

[0010] Where x1 and y1 represent the horizontal and vertical coordinate values ​​of the coordinate point on the rack tooth profile respectively; ρ i ,α i They represent the curvature radius and pressure angle of the i-th point on the rack tooth profile respectively; O1p represents the rack tooth profile;

[0011] S22. Based on the rack tooth profile curve equation and with the help of the coordinate change relationship, the gear tooth profile curve equation is obtained:

[0012]

[0013] Among them, x2 and y2 represent the horizontal and vertical coordinate values ​​of the coordinate point on the gear tooth profile respectively; represents the radius of curvature of the i-th point on the gear tooth profile; r2 represents the radius of the gear base circle; θ2 represents the gear rotation angle;

[0014] S3, by means of nonlinear smooth fitting, the final modified involute gear tooth profile is obtained, and the initial gear is processed; specifically, the following sub-steps are included:

[0015] S31, based on the modified theoretical involute gear tooth profile obtained in step S1 and the micro-segment-like involute gear tooth profile obtained in step S2, a final modified involute gear tooth profile is obtained by means of nonlinear smooth fitting;

[0016] S32, obtaining an initial gear by grinding based on the final modified involute gear tooth profile;

[0017] S4, based on the initial gear, constructing a gear shot peening impact model to obtain a shot peening gear; specifically comprising the following sub-steps:

[0018] S41, obtaining the Johnson-Cook JC constitutive model of the typical material of the initial gear by means of a Hopkinson pressure bar experiment;

[0019] S42. Based on the Johnson-Cook JC constitutive model, a gear shot peening impact model is constructed:

[0020] S43, obtaining the elastic stress field of the elastic-plastic deformation zone on the initial gear tooth surface under the impact of the projectile:

[0021]

[0022] Among them, σ rr ,σ θθ , Respectively represent the radial stress, circumferential stress and latitudinal stress in the elastic-plastic deformation zone; σ y Represents the yield strength of typical materials; r c represents the yield surface radius; r0 represents the outer surface radius of a typical material; r represents the gear radius;

[0023] S44, obtaining the stress field of the spherical cavity on the tooth surface of the initial gear when the projectile impacts and loads:

[0024]

[0025] Among them, σ cr ,σ cθ , They represent the radial stress, circumferential stress and latitudinal stress of the spherical cavity when the projectile impacts the loading; θ represents the polar angle corresponding to the gear radius r; a represents the boundary value; r a Indicates the boundaries of the crater;

[0026] S45, obtaining the stress field of the spherical cavity on the tooth surface of the initial gear after unloading:

[0027] σ tr (r, θ) = σ cr (r, θ)-σ ur (r, θ) (18)

[0028]

[0029] Among them, σ tr and σ tθ Respectively represent the radial and circumferential stresses of the spherical cavity after unloading; σ ur and σ uθ denote elastic unloading radial and circumferential stresses, respectively;

[0030] S5. Based on the shot peening gear, a gear finishing grinding model under gear rolling finishing processing is constructed to obtain a finishing gear;

[0031] S51. Calculate the material removal volume of the shot-peened gear under the action of abrasive particles: Considering the high-speed collision and extrusion between the abrasive particles and the shot-peened gear during gear rolling and finishing, calculate the material removal volume V0 of the shot-peened gear under the micro-grinding action of a single abrasive particle:

[0032]

[0033] Where D is the diameter of the abrasive grain; L i It indicates the distance of the abrasive grains grinding the surface; d and h respectively indicate the width and depth of the grooves in the overlapping area produced by the downward movement of the abrasive grains;

[0034] S52, calculating the surface roughness limit value R of the smooth gear cr :

[0035]

[0036] Wherein, HB and P represent the Brinell hardness and pressure distribution of the shot peened gear surface, respectively.

[0037] Further, the step S1 specifically includes the following steps:

[0038] S11. Calculate the meshing stiffness c per unit tooth width under tooth surface deformation analysis γ1 ;

[0039] S12. Calculate the meshing stiffness c per unit tooth width under tooth root deformation analysis γ2 :

[0040]

[0041] Among them, ω x represents the load angle at the pitch circle; h,h i They represent tooth height and pitch circle height respectively; E, v represent elastic modulus and Poisson’s ratio respectively;

[0042] S13. Calculate the meshing stiffness c per unit tooth width of the gear teeth γ :

[0043]

[0044] S14. Calculate the maximum elastic deformation of the gear as a whole:

[0045]

[0046] Among them, B represents the tooth width; F represents the gear force;

[0047] S15. Determine the modification amount of the theoretical involute gear based on the maximum elastic deformation δ of the entire gear, and obtain the modified theoretical involute gear tooth profile.

[0048] Preferably, the step S11 specifically includes the following steps:

[0049] S111. Based on elastic body, make assumptions about the contact process in tooth surface deformation analysis;

[0050] S112. Calculate the bending deformation flexibility q for the equivalent tooth shape B , shear deformation flexibility q S and compression deformation compliance q h :

[0051]

[0052] Among them, ω x represents the load angle at the pitch circle; h,h i They represent tooth height and pitch circle height respectively; E, v represent elastic modulus and Poisson’s ratio respectively; s f Indicates tooth root thickness; h r Indicates the equivalent height at the tooth root; h x Indicates the distance from the meshing point to the tooth root; E1, E2 represent the elastic modulus of the driving gear and the passive gear respectively; v1, v2 represent the Poisson's ratio of the driving gear and the passive gear respectively; when the driving gear and the passive gear are made of the same material, E1=E1=E2, v=v1=v2;

[0053] Where s f is the tooth root thickness, ω x is the load angle at the pitch circle, h is the tooth height, h i is the pitch circle height, h r is the equivalent height at the tooth root, E is the elastic modulus, and v is the Poisson’s ratio;

[0054] S113, based on bending deformation flexibility q B , shear deformation flexibility q S and compression deformation compliance q h , calculate the meshing stiffness c per unit tooth width under tooth surface deformation analysis γ1 :

[0055]

[0056] Here, q represents the total flexibility.

[0057] Preferably, the rack tooth profile O1p in step S21 satisfies:

[0058]

[0059] in, represents the i-th micro-segment; represents the radius of the construction base circle of the i-1th micro-segment; θ represents the initial angle when constructing the tooth profile; θ i represents the increment of θ when constructing the i-th micro-segment of the tooth profile; α i-1 represents the pressure angle at the i-1th point on the tooth profile;

[0060] The coordinate change relationship in step S22 is:

[0061]

[0062] Wherein, L represents the micro-segment involute gear tooth profile.

[0063] Preferably, the α i ,θ i ,ρ i The calculation formula is:

[0064]

[0065] in, They represent the initial construction base circle radius of the micro-segment and the construction base circle radius of the i-th micro-segment respectively; ρ0 represents the initial curvature radius on the tooth profile.

[0066] Preferably, the assumptions in step S111 include a first assumption and a second assumption, wherein the first assumption is that the points on the gear contact line are independent of each other and are regarded as elastic bodies that do not affect each other and the interaction between materials is negligible; the second assumption is that the load on the gear is linearly distributed, and the influence of the greater flexibility at the tooth end face on the tooth profile analysis is ignored.

[0067] Preferably, the boundary r of the crater in step S44 is a It is expressed as:

[0068]

[0069] Where R represents the radius of the projectile;

[0070] The elastic unloading of radial and circumferential stresses σ in step S45 ur ,σ uθ Respectively expressed as:

[0071]

[0072] Where p represents the internal pressure; Represents the latitudinal stress in the spherical cavity after unloading.

[0073] Preferably, step S4 also includes step S46, calculating the residual stress S of the spherical cavity in the spherical coordinate system. sph :

[0074]

[0075] Among them, σ ctr ,σ ctθ , represent the radial, circumferential and latitudinal stresses on the yield boundary, respectively.

[0076] Preferably, the radial, circumferential and latitudinal stresses σ on the yield boundary are respectively represented in step S46. ctr ,σ ctθ , Respectively expressed as:

[0077]

[0078]

[0079] Among them, r rev Represents the radius of the yield boundary.

[0080] Preferably, the width and depth d and h of the groove in the overlapping area generated by the downward movement of the abrasive particles in step S51 are respectively expressed as:

[0081]

[0082] Compared with the prior art, the technical effects of the present invention are:

[0083] 1. The present invention designs a grinding, shot peening and rolling composite surface processing method for gear tooth surfaces, which combines grinding, shot peening and rolling finishing processing, and realizes the comprehensive strengthening of the tooth surface and tooth root through process coupling design. This composite strengthening processing significantly improves the overall performance of the gear, especially makes the gear have better fatigue resistance under heavy load conditions; at the same time, by establishing an accurate shot peening model during the shot peening process and analyzing the elastic stress field under different parameters, the problems of eccentric load and stress concentration in traditional processing are reduced, the compressive stress of the tooth surface is increased, and the stress distribution of the gear during use is more uniform, the failure risk is reduced, and the service life of the gear is extended.

[0084] 2. The present invention designs a grinding and spraying composite surface processing method for gear tooth surfaces. With the help of a finishing grinding model, the material removal volume under the action of abrasive particles is calculated and optimized, so that the roughness of the gear surface is greatly reduced, which not only improves the meshing efficiency but also prolongs the service life. By utilizing the micro-segment theory and nonlinear smooth fitting technology, the tooth profile is precisely modified to achieve higher manufacturing accuracy, meet the strict requirements of the modern heavy-load gear industry, and enable the gear to maintain efficient operation under high load, which has important practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Other features, objects and advantages of the present application will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings.

[0086] Figure 1 It is a flow chart of the grinding, spraying and rolling composite surface processing method for gear tooth surface of the present invention;

[0087] Figure 2 It is a schematic diagram of the gear rack coordinate system of the gear tooth profile micro-segment of the present invention;

[0088] Figure 3 is a schematic diagram of gear tooth profile modification of the present invention;

[0089] Figure 4 It is a schematic diagram of a spherical cavity model under shot peening impact in the shot peening process of the present invention;

[0090] Figure 5 It is a schematic diagram of the model of the surface finishing abrasive particles of the present invention acting on the surface in trace amounts. DETAILED DESCRIPTION

[0091] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0092] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0093] Figure 1 The present invention shows a method for grinding, spraying and rolling composite surface processing of gear tooth surface, which comprises the following steps:

[0094] S1. Determine the maximum elastic deformation of the gear as a whole and obtain the theoretical involute gear tooth profile after modification.

[0095] The elastic deformation is mainly caused by the bending shear contact deformation of the tooth surface and the bending shear deformation of the tooth root. The maximum elastic deformation caused by the bending shear contact deformation of the tooth surface and the bending shear deformation of the tooth root are calculated respectively to obtain the maximum elastic deformation of the entire gear.

[0096] S11. Calculate the meshing stiffness c per unit tooth width under tooth surface deformation analysis γ1 .

[0097] S111. Based on the elastic body, the contact process under the tooth surface deformation analysis is assumed. The assumptions include the first assumption and the second assumption. The first assumption is that the points on the gear contact line are independent of each other, and are regarded as elastic bodies that do not affect each other, and the interaction between materials is negligible; the second assumption is that the load on the gear is linearly distributed, and the influence of the large flexibility at the tooth end face on the tooth profile analysis is ignored.

[0098] Because the tooth surface is a complex curved surface and is difficult to solve directly, the total flexibility q of the equivalent tooth shape can be solved after approximate processing.

[0099] S112. Calculate the bending deformation flexibility q for the equivalent tooth shape B , shear deformation flexibility q S and compression deformation compliance q h :

[0100]

[0101] Among them, ω x represents the load angle at the pitch circle; h,h i They represent tooth height and pitch circle height respectively; E, v represent elastic modulus and Poisson’s ratio respectively; s f Indicates tooth root thickness; h r Indicates the equivalent height at the tooth root; h x It represents the distance from the meshing point to the tooth root; E1 and E2 represent the elastic modulus of the driving gear and the passive gear respectively; v1 and v2 represent the Poisson's ratio of the driving gear and the passive gear respectively.

[0102] S113, based on bending deformation flexibility q B , shear deformation flexibility q S and compression deformation compliance q h , calculate the meshing stiffness c per unit tooth width under tooth surface deformation analysis γ1 :

[0103]

[0104] Here, q represents the total flexibility.

[0105] When analyzing the elastic deformation of the tooth surface, it is assumed that the root of the tooth is fixed. In fact, the tooth root is also an elastic body, and the effect of the deformation of the gear root needs to be considered.

[0106] S12. Calculate the meshing stiffness c per unit tooth width under tooth root deformation analysis γ2 :

[0107]

[0108] S13. Calculate the meshing stiffness c per unit tooth width of the gear teeth γ :

[0109]

[0110] S14. Calculate the maximum elastic deformation of the gear as a whole:

[0111]

[0112] Among them, B represents the tooth width; F represents the gear force.

[0113] S15. Determine the modification amount of the theoretical involute gear based on the maximum elastic deformation δ of the entire gear, and obtain the modified theoretical involute gear tooth profile.

[0114] S2. With the help of micro-segment theory, a micro-segment-like involute gear tooth profile is obtained: Based on the modified theoretical involute gear tooth profile, micro-segment tooth root transition modification is performed with the help of micro-segment theory to obtain a micro-segment-like involute gear tooth profile.

[0115] S21, such as Figure 2 As shown, the gear rack coordinate system Oxy is established, the intersection of the rack tooth profile and the pitch line is set as the origin O, and with the help of micro-segment theory, the rack tooth profile curve equation is obtained:

[0116]

[0117] Where x1 and y1 represent the horizontal and vertical coordinate values ​​of the coordinate point on the rack tooth profile respectively; ρ i ,α i Respectively represent the curvature radius and pressure angle of the i-th point on the rack tooth profile; O1p represents the rack tooth profile and satisfies:

[0118]

[0119] in, represents the i-th micro-segment; represents the radius of the construction base circle of the i-1th micro-segment; θ represents the initial angle when constructing the tooth profile; θ i represents the increment of θ when constructing the i-th micro-segment of the tooth profile; α i-1 Represents the pressure angle at the i-1th point on the tooth profile.

[0120] a i ,θ i ,ρ i The calculation formula is:

[0121]

[0122] in, They represent the initial construction base circle radius of the micro-segment and the construction base circle radius of the i-th micro-segment respectively; ρ0 represents the initial curvature radius on the tooth profile.

[0123] S22. Based on the rack tooth profile curve equation and with the help of the coordinate change relationship, the gear tooth profile curve equation is obtained:

[0124]

[0125] Among them, x2 and y2 represent the horizontal and vertical coordinate values ​​of the coordinate point on the gear tooth profile respectively; represents the radius of curvature of the i-th point on the gear tooth profile; r2 represents the radius of the gear base circle; θ2 represents the gear rotation angle.

[0126] The coordinate change relationship is:

[0127]

[0128] Wherein, L represents the micro-segment involute gear tooth profile.

[0129] S3, such as Figure 3 As shown, with the help of nonlinear smooth fitting, the final modified involute gear tooth profile is obtained, and the initial gear is processed.

[0130] S31, based on the modified theoretical involute gear tooth profile obtained in step S1 and the micro-segment-like involute gear tooth profile obtained in step S2, the final modified involute gear tooth profile is obtained by means of nonlinear smooth fitting.

[0131] S32. Based on the final modified involute gear tooth profile, an initial gear is obtained by grinding.

[0132] S4. Based on the initial gear, a gear shot peening impact model is constructed to obtain a shot peening gear.

[0133] S41. With the help of Hopkinson pressure bar experiment, the Johnson-Cook constitutive model of the typical material of the initial gear is obtained.

[0134] S42. Based on the Johnson-Cook JC constitutive model, a gear shot peening impact model is constructed: During the initial gear shot peening process, the projectile hits the initial gear tooth surface at a certain speed, forming a crater on the initial gear tooth surface and generating elastic-plastic deformation around the crater.

[0135] S43, obtain the elastic stress field of the elastic-plastic deformation zone on the initial gear tooth surface under the impact of the projectile:

[0136]

[0137] Among them, σ rr ,σ θθ , Respectively represent the radial stress, circumferential stress and latitudinal stress in the elastic-plastic deformation zone; σ y Represents the yield strength of typical materials; r c represents the yield surface radius; r0 represents the outer surface radius of a typical material; r represents the gear radius.

[0138] S44, such as Figure 4As shown in the figure, a spherical cavity is generated after the projectile hits the tooth surface, and the stress field of the spherical cavity on the initial gear tooth surface during projectile impact loading is obtained. For the convenience of calculation, it is assumed that the value of the stress component in this area is equal to the value at the boundary r = a, specifically:

[0139]

[0140]

[0141] Among them, σ cr ,σ cθ , They represent the radial stress, circumferential stress and latitudinal stress of the spherical cavity when the projectile impacts the loading; θ represents the polar angle corresponding to the gear radius r; a represents the boundary value; r a represents the boundary of the crater and is expressed as:

[0142]

[0143] Where R represents the radius of the projectile.

[0144] S45. Assuming that the deformation of the material before the reverse yield is elastic deformation during the projectile impact unloading process, the entire spherical shell is in an elastic deformation state under the condition of internal pressure p, and the stress field of the spherical cavity on the initial gear tooth surface after unloading is obtained:

[0145] σ tr (r, θ) = σ cr (r, θ)-σ ur (r, θ) (18)

[0146]

[0147] Among them, σ tr and σ tθ Respectively represent the radial and circumferential stresses of the spherical cavity after unloading; σ ur and σ uθ denote elastic unloading radial and circumferential stresses respectively and are expressed as:

[0148]

[0149] Where p represents the internal pressure; Represents the latitudinal stress in the spherical cavity after unloading.

[0150] S46. During the impact of the projectile, there is a symmetric constraint on the z plane of the substrate, while in the actual shot peening process, the surface of the substrate is a free constraint. If the symmetric constraint of the shot peening surface in the spherical cavity model is removed, the stress after the projectile rebound calculated above will be released in the direction perpendicular to the shot peening surface. After the release, the residual stress inside the substrate is the residual stress of the single projectile impact. Calculate the residual stress S of the spherical cavity in the spherical coordinate systemsph :

[0151]

[0152] Among them, σ ctr ,σ ctθ , denote the radial, circumferential and latitudinal stresses on the yield boundary and are expressed as:

[0153]

[0154]

[0155] Among them, r rev Represents the radius of the yield boundary.

[0156] S5. Based on shot peening gears, a gear finishing grinding model is constructed under gear rolling finishing process, such as Figure 5 As shown, a smooth gear is obtained.

[0157] S51. Calculate the material removal volume of the shot-peened gear under the action of abrasive particles: Considering the high-speed collision and extrusion between the abrasive particles and the shot-peened gear during the gear rolling and finishing process, calculate the material removal volume V0 of the shot-peened gear under the micro-grinding action of a single abrasive particle:

[0158]

[0159] Where D is the diameter of the abrasive grain; L i represents the distance of the abrasive on the surface grinding; d and h represent the width and depth of the groove in the overlapping area produced by the downward movement of the abrasive and are respectively expressed as:

[0160]

[0161] Among them, HB and P represent the Brinell hardness and pressure distribution on the shot peened gear surface, respectively.

[0162] S52, calculate the surface roughness limit value R of the smooth gear cr :

[0163]

[0164] In a preferred embodiment of the present invention, the method of the present invention may further include a detection step, that is, it may also include S6, detecting the tooth surface performance of the smoothed gear. The tooth surface roughness, tooth surface residual stress and surface hardness are used as the tooth surface performance judgment. According to the performance results, the shot peening finishing parameters such as the relative speed between the gear and the abrasive, the abrasive material, etc. can be corrected to finally achieve high-performance gear processing.

[0165] The present invention designs a grinding, shot peening and rolling composite surface processing method for gear tooth surfaces, which combines grinding, shot peening and rolling finishing processing, and realizes comprehensive strengthening of tooth surfaces and tooth roots through process coupling design. This composite strengthening processing significantly improves the overall performance of the gear, especially makes the gear have better fatigue resistance under heavy load conditions; at the same time, by establishing an accurate shot peening model during the shot peening process and analyzing the elastic stress field under different parameters, the problems of eccentric load and stress concentration in traditional processing are reduced, the compressive stress on the tooth surface is increased, and the stress distribution of the gear during use is more uniform, the failure risk is reduced, and the service life of the gear is extended; by using the finishing grinding model, the material removal volume under the action of abrasive particles is calculated and optimized, so that the roughness of the gear surface is greatly reduced, which not only improves the meshing efficiency, but also extends the service life; by utilizing the micro-segment theory and nonlinear smooth fitting technology, the tooth profile is accurately modified, and higher manufacturing accuracy is achieved, which meets the strict requirements of the modern heavy-load gear industry, so that the gear can still maintain efficient operation under high load, and has important practical application value.

[0166] Finally, it should be noted that the above embodiments are only intended to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A grinding and spraying composite surface processing method for gear tooth surface, characterized in that: It includes the following steps: S1. Determine the maximum elastic deformation of the entire gear and obtain the theoretical involute gear tooth profile after modification; S2. Obtaining a micro-segment-like involute gear tooth profile by means of micro-segment theory: Based on the modified theoretical involute gear tooth profile, micro-segment tooth root transition modification is performed by means of micro-segment theory to obtain a micro-segment-like involute gear tooth profile; the step S2 specifically includes the following sub-steps: S21. Establish the gear rack coordinate system Oxy, set the intersection of the rack tooth profile and the pitch line as the origin O, and use the micro-segment theory to obtain the rack tooth profile curve equation: Where x1 and y1 represent the horizontal and vertical coordinate values ​​of the coordinate point on the rack tooth profile respectively; ρ i ,α i They represent the curvature radius and pressure angle of the i-th point on the rack tooth profile respectively; O1p represents the rack tooth profile; S22. Based on the rack tooth profile curve equation and with the help of the coordinate change relationship, the gear tooth profile curve equation is obtained: Among them, x2 and y2 represent the horizontal and vertical coordinate values ​​of the coordinate point on the gear tooth profile respectively; represents the radius of curvature of the i-th point on the gear tooth profile; r2 represents the radius of the gear base circle; θ2 represents the gear rotation angle; S3, by means of nonlinear smooth fitting, the final modified involute gear tooth profile is obtained, and the initial gear is processed; specifically, the following sub-steps are included: S31, based on the modified theoretical involute gear tooth profile obtained in step S1 and the micro-segment-like involute gear tooth profile obtained in step S2, a final modified involute gear tooth profile is obtained by means of nonlinear smooth fitting; S32, obtaining an initial gear by grinding based on the final modified involute gear tooth profile; S4, based on the initial gear, constructing a gear shot peening impact model to obtain a shot peening gear; specifically comprising the following sub-steps: S41, obtaining the Johnson-Cook JC constitutive model of the typical material of the initial gear by means of a Hopkinson pressure bar experiment; S42. Based on the Johnson-Cook JC constitutive model, a gear shot peening impact model is constructed: S43, obtaining the elastic stress field of the elastic-plastic deformation zone on the initial gear tooth surface under the impact of the projectile: Among them, σ rr ,σ θθ , Respectively represent the radial stress, circumferential stress and latitudinal stress in the elastic-plastic deformation zone; σ y Represents the yield strength of typical materials; r c represents the yield surface radius; r0 represents the outer surface radius of a typical material; r represents the gear radius; S44, obtaining the stress field of the spherical cavity on the tooth surface of the initial gear when the projectile impacts and loads: Among them, σ cr , σ cθ , They represent the radial stress, circumferential stress and latitudinal stress of the spherical cavity when the projectile impacts the loading; θ represents the polar angle corresponding to the gear radius r; a represents the boundary value; r a Indicates the boundaries of the crater; S45, obtaining the stress field of the spherical cavity on the tooth surface of the initial gear after unloading: s tr (r,θ)=σ cr (r,θ)-σ ur (r,θ) (18) Among them, σ tr and σ tθ Respectively represent the radial and circumferential stresses of the spherical cavity after unloading; σ ur and σ uθ denote elastic unloading radial and circumferential stresses, respectively; S5. Based on the shot peening gear, a gear finishing grinding model under gear rolling finishing processing is constructed to obtain a finishing gear; S51. Calculate the material removal volume of the shot-peened gear under the action of abrasive particles: Considering the high-speed collision and extrusion between the abrasive particles and the shot-peened gear during gear rolling and finishing, calculate the material removal volume V0 of the shot-peened gear under the micro-grinding action of a single abrasive particle: Where D is the diameter of the abrasive grain; L i It indicates the distance of the abrasive grains grinding the surface; d and h respectively indicate the width and depth of the grooves in the overlapping area produced by the downward movement of the abrasive grains; S52, calculating the surface roughness limit value R of the smooth gear cr : Wherein, HB and P represent the Brinell hardness and pressure distribution of the shot peened gear surface, respectively.

2. The grinding, spraying and rolling composite surface processing method for gear tooth surface according to claim 1 is characterized in that: The step S1 specifically includes the following steps: S11. Calculate the meshing stiffness c per unit tooth width under tooth surface deformation analysis γ1 ; S12. Calculate the meshing stiffness c per unit tooth width under tooth root deformation analysis γ2 : Among them, ω x represents the load angle at the pitch circle; h, h i They represent tooth height and pitch circle height respectively; E, v represent elastic modulus and Poisson’s ratio respectively; S13. Calculate the meshing stiffness c per unit tooth width of the gear teeth γ : S14. Calculate the maximum elastic deformation of the gear as a whole: Among them, B represents the tooth width; F represents the gear force; S15. Determine the modification amount of the theoretical involute gear based on the maximum elastic deformation δ of the entire gear, and obtain the modified theoretical involute gear tooth profile.

3. The grinding, spraying and rolling composite surface processing method for gear tooth surface according to claim 2 is characterized in that: The step S11 specifically includes the following steps: S111. Based on elastic body, make assumptions about the contact process in tooth surface deformation analysis; S112. Calculate the bending deformation flexibility q for the equivalent tooth shape B , shear deformation flexibility q S and compression deformation compliance q h : Among them, ω x represents the load angle at the pitch circle; h,h i They represent tooth height and pitch circle height respectively; E, v represent elastic modulus and Poisson’s ratio respectively; s f Indicates tooth root thickness; h r Indicates the equivalent height at the tooth root; h x Indicates the distance from the meshing point to the tooth root; E1, E2 represent the elastic modulus of the driving gear and the passive gear respectively; v1, v2 represent the Poisson's ratio of the driving gear and the passive gear respectively; when the driving gear and the passive gear are made of the same material, E1=E1=E2, v=v1=v2; Where s f is the tooth root thickness, ω x is the load angle at the pitch circle, h is the tooth height, h i is the pitch circle height, h r is the equivalent height at the tooth root, E is the elastic modulus, and v is the Poisson’s ratio; S113, based on bending deformation flexibility q B , shear deformation flexibility q S and compression deformation compliance q h , calculate the meshing stiffness c per unit tooth width under tooth surface deformation analysis γ1 : Here, q represents the total flexibility.

4. The grinding, spraying and rolling composite surface processing method for gear tooth surface according to claim 2 is characterized in that: The rack tooth profile O1p in step S21 satisfies: in, represents the i-th micro-segment; represents the radius of the construction base circle of the i-1th micro-segment; θ represents the initial angle when constructing the tooth profile; θ i represents the increment of θ when constructing the i-th micro-segment of the tooth profile; α i-1 represents the pressure angle at the i-1th point on the tooth profile; The coordinate change relationship in step S22 is: Wherein, L represents the micro-segment involute gear tooth profile.

5. The grinding, spraying and rolling composite surface processing method for gear tooth surface according to claim 4 is characterized in that: The α i ,θ i ,ρ i The calculation formula is: in, They represent the initial construction base circle radius of the micro-segment and the construction base circle radius of the i-th micro-segment respectively; ρ0 represents the initial curvature radius on the tooth profile.

6. The grinding, spraying and rolling composite surface processing method for gear tooth surface according to claim 3 is characterized in that: The assumptions in step S111 include a first assumption and a second assumption. The first assumption is that the points on the gear contact line are independent of each other and are regarded as elastic bodies that do not affect each other, and the interaction between materials is negligible. The second assumption is that the load on the gear is linearly distributed, and the influence of the greater flexibility at the tooth end face on the tooth profile analysis is ignored.

7. The grinding, spraying and rolling composite surface processing method for gear tooth surface according to claim 1 is characterized in that: The boundary r of the crater in step S44 a It is expressed as: Where R represents the radius of the projectile; The elastic unloading of radial and circumferential stresses σ in step S45 ur ,σ uθ Respectively expressed as: Where p represents the internal pressure; Represents the latitudinal stress in the spherical cavity after unloading.

8. The grinding, spraying and rolling composite surface processing method for gear tooth surface according to claim 1 is characterized in that: The step S4 also includes step S46, calculating the residual stress S of the spherical cavity in the spherical coordinate system. sph : Among them, σ ctr ,σ ctθ , represent the radial, circumferential and latitudinal stresses on the yield boundary, respectively.

9. The grinding, spraying and rolling composite surface processing method for gear tooth surface according to claim 8 is characterized in that: The step S46 represents the radial, circumferential and latitudinal stresses σ on the yield boundary respectively. ctr ,σ ctθ , Respectively expressed as: Among them, r rev Represents the radius of the yield boundary.

10. The grinding, spraying and rolling composite surface processing method for gear tooth surface according to claim 8, characterized in that: The width and depth d and h of the groove in the overlapping area generated by the downward movement of the abrasive particles in step S51 are respectively expressed as:

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