Cam, wave generator, harmonic reducer and cam design method

Abstract

The application provides a cam, a wave generator, a harmonic reducer and a cam design method, relates to the technical field of harmonic transmission, and the cam comprises a cam body, a surface texture is arranged on the peripheral side surface of the cam body, the surface texture comprises axially distributed microgrooves and circumferentially distributed microgrooves, the axially distributed microgrooves extend along the axial direction of the cam body, and the circumferentially distributed microgrooves extend along the circumferential direction of the cam body; the peripheral side surface of the cam body comprises a long axis region, a transition region and a short axis region, the long axis region is arranged at both ends in the long axis direction of the cam body, the short axis region is arranged at both ends in the short axis direction of the cam body, and the transition region is the part between the long axis region and the short axis region; the density of the surface texture in the long axis region is greater than the density of the surface texture in the short axis region, and the density of the surface texture in the short axis region is greater than the density of the surface texture in the transition region. In this way, the problem of how to enhance the connection reliability of the cam and the flexible bearing in the prior art is solved.

Description

Technical Field

[0001] This application relates to the field of harmonic drive technology, specifically to a cam, a wave generator, a harmonic reducer, and a cam design method. Background Technology

[0002] As a precision speed reduction device, the performance and reliability of harmonic reducers are increasingly crucial for high-end equipment such as humanoid robots and collaborative robots. The wave generator, as the core component of the harmonic reducer, employs a full-circumference interference fit design between the cam and the inner ring of the flexible bearing to achieve the purpose of cam-driven flexible bearing deformation and effective torque transmission. This ensures that the entire outer circumference of the cam is completely in contact with the inner ring of the flexible bearing. The applicant has discovered that this interference fit exhibits fretting wear under high-speed, heavy-load conditions. This means that the two tightly pressed metal surfaces experience wear due to small-amplitude reciprocating relative sliding, indicating a risk of relative sliding or even separation between the cam and the flexible bearing.

[0003] Therefore, how to enhance the connection reliability between the cam and the flexible bearing to reduce the possibility of the cam disengaging from the flexible bearing has become a direction explored by those skilled in the art. Summary of the Invention

[0004] In view of this, this application provides a cam, a wave generator, a harmonic reducer, and a cam design method to solve the problem of how to enhance the connection reliability of cams and flexible bearings in the prior art.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] A cam is used in a harmonic reducer. The cam includes a cam body, and the peripheral side of the cam body is provided with a surface texture. The surface texture includes axial microgrooves and circumferential microgrooves that are distributed in a cross pattern. The axial microgrooves extend along the axial direction of the cam body, and the circumferential microgrooves extend along the circumferential direction of the cam body.

[0007] The peripheral surface of the cam body includes a long axis region, a transition region, and a short axis region. The long axis region is distributed at both ends in the long axis direction of the cam body, the short axis region is distributed at both ends in the short axis direction of the cam body, and the transition region is the part between the long axis region and the short axis region.

[0008] The density of the surface texture in the long axis region is greater than the density of the surface texture in the short axis region, and the density of the surface texture in the short axis region is greater than the density of the surface texture in the transition region.

[0009] Optionally, the circumferential microgrooves are distributed at equal density along the axial direction of the cam body;

[0010] The axial microgrooves exhibit a gradient distribution density along the circumferential direction of the cam body.

[0011] Optionally, in the long axis region, the spacing between two adjacent axial microgrooves gradually decreases as they approach the long axis;

[0012] In the short axis region, the distance between two adjacent axial microgrooves gradually decreases as they approach the short axis;

[0013] In the transition region, the distance between two adjacent axial microgrooves gradually increases as they approach the center of the transition region.

[0014] Optionally, the cross-sections of both the axial microgroove and the circumferential microgroove are arc-shaped; and / or,

[0015] The width and depth of the axial microgroove are both in the micrometer range, and the width and depth of the circumferential microgroove are both in the micrometer range.

[0016] Optionally, the cross-sections of both the axial microgroove and the circumferential microgroove are semi-circular arc-shaped with a diameter of 10 micrometers to 50 micrometers.

[0017] Optionally, on a projection plane perpendicular to the axial direction of the cam body, the line connecting the axial micro-groove and the center of the cam body is the axial groove position line, and the angle between the major axis of the cam body and the adjacent axial groove position line, and the angle between two adjacent axial groove position lines are all interval angles.

[0018] In a Cartesian coordinate system with the center of the cam body as the origin, the minor axis of the cam body as the X-axis, and the major axis of the cam body as the Y-axis, all the axial groove position lines in the first quadrant are symmetrical about the Y-axis with all the axial groove position lines in the second quadrant, all the axial groove position lines in the third quadrant are symmetrical about the X-axis with all the axial groove position lines in the second quadrant, and all the axial groove position lines in the fourth quadrant are symmetrical about the X-axis with all the axial groove position lines in the first quadrant.

[0019] All the interval angles in the first quadrant conform to the interval angle function:

[0020] ,

[0021] Wherein, N is the number of all the axial groove position lines in the first quadrant;

[0022] x is the interval angle number, x∈[1,N], and the xth interval angle is the angle between the (x-1)th axial groove position line and the xth axial groove position line;

[0023] This represents the angle value corresponding to the x-th interval angle in the first quadrant;

[0024] The angle value represents the interval angle between the major axis of the cam body and the position line of the first axial groove.

[0025] Optionally, any of the axial microgrooves extends to the two end edges of the circumferential side surface of the cam body;

[0026] All of the circumferential microgrooves are distributed circumferentially.

[0027] A wave generator includes a flexible bearing and a cam as described above, the cam being fitted inside the flexible bearing.

[0028] A harmonic reducer includes the wave generator described above.

[0029] A cam design method applicable to designing cams for harmonic reducers, the method comprising:

[0030] An axially extending microgroove is constructed on the peripheral surface of the cam body, including:

[0031] Establish a Cartesian coordinate system with the center of the cam body as the origin, the minor axis of the cam body as the X-axis, and the major axis of the cam body as the Y-axis. Obtain the quarter cam profile located in the first quadrant and divide the quarter cam profile into a major axis region, a transition region, and a minor axis region in a clockwise direction.

[0032] In the first quadrant, N axial groove position lines are preset to connect the origin and the quarter cam profile. The angle between the major axis of the cam body and the adjacent axial groove position line, and the angle between two adjacent axial groove position lines are used as the interval angle. The angle between the minor axis of the cam body and the adjacent axial groove position line is used as the end angle.

[0033] Construct an interval angle function that is constrained over the quarter-cam profile;

[0034] Based on the absolute error between the interval angle function, the sum of the end angles and the total angle 90° corresponding to the first quadrant, an objective function is established. By solving the constraint equation of the objective function, the values ​​of parameters C and D can be obtained. Based on the values ​​of C and D, the interval angle function is further solved to obtain the positions of all the axial groove position lines in the first quadrant.

[0035] Based on all the axial groove position lines in the first quadrant, the axial groove position lines in the second quadrant are obtained with the Y-axis as the line of symmetry. Based on all the axial groove position lines in the first and second quadrants, the axial groove position lines in the fourth and third quadrants are obtained with the X-axis as the line of symmetry.

[0036] The position of the axial microgroove is obtained based on the position of all the axial groove position lines, and all the axial groove position lines correspond one-to-one with all the axial microgrooves.

[0037] Optionally, the interval angle function is constructed as follows:

[0038] ,

[0039] in ,

[0040] In equation (1), x is the interval angle number, x∈[1,N], the xth interval angle is the angle between the (x-1)th axial groove position line and the xth axial groove position line, representing the angle value corresponding to the xth interval angle in the first quadrant, C is the reference interval angle and represents the average interval angle value when the change of the axial groove position line density is not considered, D is the interval angle modulation amplitude and is used to control the change amplitude of the interval angle around C, t is the normalization parameter, representing the position parameter of the minimum axial groove position line density and determining the position of the maximum interval angle in the normalized coordinates;

[0041] according to and The mapping relationship between the two is established as follows: ,

[0042] Combining equations (1), (2), and (3), in order to make the lowest density point of the axial groove position line appear at the position of minimum contact pressure, the following steps are taken: Revised to , and will Set it to a constant value;

[0043] The objective function is: The included angle δ at the end is the angle between the Nth axial groove position line and the minor axis of the cam body;

[0044] The objective function is constrained to control the overall density of the axial groove position line in the short axis region to be between the overall density of the long axis region and the overall density of the transition region, while controlling the smoothness of the density change of the axial groove position line.

[0045] The first constraint equation is established as follows (5), The settings are based on engineering design requirements and actual machining precision.

[0046] There is a basic relationship between parameters C and D: (6), with equation (6) as the second constraint equation;

[0047] For N and The values ​​of C and D are obtained by assigning values ​​and solving the first constraint equation and the second constraint equation.

[0048] Optionally, assign N the value 40, and The value is assigned to 0.1, and the parameters can be obtained by solving the constraint equations of the objective function. , .

[0049] Optionally, the cam body may also include a circumferentially extending microgroove on its peripheral side surface, wherein multiple circumferential microgrooves are formed and are distributed at equal density along the axial direction of the cam body.

[0050] The cam provided in this application is applied to a harmonic reducer. The cam includes a cam body, and the circumferential surface of the cam body is provided with a surface texture. The surface texture includes axial microgrooves and circumferential microgrooves that are distributed in a cross pattern. The axial microgrooves extend along the axial direction of the cam body, and the circumferential microgrooves extend along the circumferential direction of the cam body. The circumferential surface of the cam body includes a long axis region, a transition region, and a short axis region. The long axis region is distributed at both ends in the long axis direction of the cam body, the short axis region is distributed at both ends in the short axis direction of the cam body, and the transition region is the part between the long axis region and the short axis region. The density of the surface texture in the long axis region is greater than the density of the surface texture in the short axis region, and the density of the surface texture in the short axis region is greater than the density of the surface texture in the transition region. This design, achieved by applying adhesive between the cam and the flexible bearing, aims to enhance the stability of their bond. This application constructs a surface texture on the circumferential surface of the cam, fundamentally altering the two-dimensional planar properties of the mating surface and transforming it into a complex three-dimensional interface. This significantly increases the effective bonding surface area, providing abundant micro-mechanical anchoring points for the adhesive. Furthermore, the applicant discovered that in the circumferential surfaces of elliptical and quasi-elliptical cams, the long axis region has the smallest radius of curvature, the highest contact pressure, and the highest risk of adhesive extrusion and slippage. Therefore, this region requires the best preservation of adhesive. The short axis region has a larger radius of curvature, lower contact pressure than the long axis region, and also a higher risk of slippage. The transition region between the long and short axis regions has the lowest contact pressure and a lower risk of slippage. Therefore, to match the contact pressure distribution of the cam, a double-peak high-pressure zone located on the long and short axes of the cam is designed... The surface texture density is high, while the surface texture density in the transition area between the long and short axes is low, resulting in an overall characteristic of being dense at both ends and sparse in the middle. This allows for the storage of more adhesive and the formation of a stronger anchoring effect in the long axis region, followed by the short axis region. This precisely targets the high-risk areas where the adhesive is most easily extruded, ensuring that the anchoring capacity of the surface texture matches the contact pressure distribution of the cam profile. This achieves a precise match between performance, structure, and operating conditions, promoting the rational distribution and effective storage of adhesive on the mating surfaces of the cam and the flexible bearing. It avoids the situation where simple planar mating can only achieve surface bonding of the adhesive, but instead transfers some stress from the inside of the adhesive layer to the micro-mechanical anchoring points. This changes the situation where planar bonding is easily sheared and damaged, effectively resisting the risk of debonding caused by fretting wear, improving the bonding strength and reliability of the adhesive, and preventing the cam and the flexible bearing from slipping or even falling off. This solves the problem of how to enhance the connection reliability of the cam and the flexible bearing in the existing technology. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0052] Figure 1 This is a schematic diagram of the surface texture on the circumferential side of a quarter-cam provided in an embodiment of this application.

[0053] Figure 2 This is a schematic diagram of the overall structure of the cam provided in an embodiment of this application.

[0054] Figure 3 This is a schematic diagram showing the distribution of the axial groove position lines in the first quadrant, as provided in an embodiment of this application.

[0055] Figure 4 The value of N provided in this embodiment is 40. An angle value curve of all interval angles in the first quadrant when the value is assigned to 0.1.

[0056] Figure 5 According to Figure 4 The obtained angular position curve of the axial microgroove.

[0057] exist Figures 1-2 middle:

[0058] 11. Long axis region; 12. Transition region; 13. Short axis region;

[0059] 100, axial microgroove; 200, circumferential microgroove. Detailed Implementation

[0060] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0061] In the prior art, the outer contour of cams, which are widely used, is typically designed as an ellipse or near-ellipse, with easily distinguishable major and minor axes. In this field, it is common practice to apply adhesive between the cam and the flexible bearing to enhance the stability of the connection. However, the applicant has found that the interference fit design of the entire circumference of the mating surface between the cam and the flexible bearing causes the adhesive to be easily extruded, making it difficult to adhere, weakening the reliability of the connection, and the adhesive is also prone to shear failure after bonding.

[0062] In light of the above situation, it is particularly important to enhance the adhesive bonding effect between the cam and the flexible bearing interference fit surface, improve the connection reliability between the two, and prevent the cam from separating from the flexible bearing.

[0063] like Figures 1-3 As shown in the embodiment of this application, a cam is provided for use in a harmonic reducer. The cam includes a cam body with a shaft hole. The peripheral surface of the cam body is provided with a surface texture, which includes axial microgrooves 100 and circumferential microgrooves 200 distributed in a cross pattern. The axial microgrooves 100 extend along the axial direction of the cam body, and the circumferential microgrooves 200 extend along the circumferential direction of the cam body. The surface texture presents a grid texture pattern formed by the interweaving of tiny grooves. The peripheral surface of the cam body includes a long axis region 11, a transition region 12, and a short axis region 13. The long axis region 11 is distributed at both ends in the long axis direction of the cam body, and the short axis region 13 is distributed at both ends in the short axis direction of the cam body. The transition region 12 is the part between the long axis region 11 and the short axis region 13. The density of the surface texture in the long axis region 11 is greater than the density of the surface texture in the short axis region 13, and the density of the surface texture in the short axis region 13 is greater than the density of the surface texture in the transition region 12.

[0064] This design, achieved by applying adhesive between the cam and the flexible bearing, aims to enhance the stability of their bond. This application constructs a surface texture on the circumferential surface of the cam, fundamentally altering the two-dimensional planar properties of the mating surface and transforming it into a complex three-dimensional interface. This significantly increases the effective bonding surface area, providing abundant micro-mechanical anchoring points for the adhesive. Furthermore, the applicant discovered that in the circumferential surfaces of elliptical and near-elliptical cams, the long axis region 11 has the smallest radius of curvature, the highest contact pressure, and the highest risk of adhesive extrusion, making it most prone to slippage. Therefore, this region requires the best preservation of adhesive. The short axis region 13 has a larger radius of curvature, with contact pressure slightly lower than the long axis region 11, and also a higher risk of slippage. The transition region 12, between the long axis region 11 and the short axis region 13, has the smallest contact pressure and a lower risk of slippage. Therefore, to match the contact pressure distribution of the cam, the double peaks located on the long and short axes of the cam are designed... The high-pressure zone has a high surface texture density, while the transition area 12 between the long and short axes has a low surface texture density, resulting in an overall characteristic of being dense at both ends and sparse in the middle. This allows for the storage of more adhesive and the formation of a stronger anchoring effect in the long axis region 11, followed by the short axis region 13. This precisely targets the high-risk areas where the adhesive is most easily extruded, ensuring that the anchoring capacity of the surface texture matches the contact pressure distribution of the cam profile. This achieves a precise match between performance, structure, and operating conditions, promoting the rational distribution and effective storage of adhesive on the mating surfaces of the cam and the flexible bearing. It avoids the situation where simple planar mating can only achieve surface bonding of the adhesive, but instead transfers some stress from the inside of the adhesive layer to the micro-mechanical anchoring points. This changes the situation where planar bonding is easily sheared and damaged, effectively resisting the risk of debonding caused by fretting wear, improving the bonding strength and reliability of the adhesive, and preventing the cam and the flexible bearing from sliding or even falling off. This solves the problem of how to enhance the connection reliability of the cam and the flexible bearing in the prior art.

[0065] In some preferred embodiments, the axial microgrooves 100 and circumferential microgrooves 200 are designed as straight lines, all circumferential microgrooves 200 are distributed in parallel, and the circumferential microgrooves 200 are distributed at equal density in the axial direction of the cam body; all axial microgrooves 100 are distributed in parallel, and the distribution density of the axial microgrooves 100 in the circumferential direction of the cam body varies in a gradient.

[0066] With this configuration, the circumferential microgrooves 200 are designed to have a uniform density distribution in the axial direction, while the axial microgrooves 100 are designed to have a gradient distribution density along the cam profile in the circumferential direction. This results in a gradient change in the surface texture, which matches the anchoring ability of the surface texture with the contact pressure distribution of the cam profile. This makes the surface texture easy to design and process, and the solution is highly feasible.

[0067] Furthermore, in some preferred embodiments, in the long axis region 11, the distance between two adjacent axial microgrooves 100 gradually decreases as they approach the long axis; in the short axis region 13, the distance between two adjacent axial microgrooves 100 gradually decreases as they approach the short axis; and in the transition region 12, the distance between two adjacent axial microgrooves 100 gradually increases as they approach the center of the transition region 12.

[0068] This configuration means that the distribution density of the surface texture follows a pattern where the spacing between the axial microgrooves 100 is smaller closer to the major and minor axes, and larger closer to the center of the transition region 12. This allows the density of the axial microgrooves 100 to change gradient with the contact pressure distribution of the cam profile, precisely corresponding to the high-risk locations where the adhesive is most likely to be extruded, achieving a match between performance and structure, and forming a gradient design that is precisely matched with the working conditions.

[0069] Of course, in some cases, it is also feasible to design the circumferential microgroove 200 as a curve and form a high-density distribution pattern locally, while designing the axial microgroove 100 as a uniform density distribution.

[0070] In some preferred embodiments, the cross-sections of both the axial microgroove 100 and the circumferential microgroove 200 are arc-shaped. This configuration, with both the axial microgroove 100 and the circumferential microgroove 200 featuring arc-shaped groove bottoms, avoids stress concentration that may be caused by sharp corners, thereby ensuring the fatigue strength of the cam under alternating loads and balancing structural details for both reinforcement and safety.

[0071] In some preferred embodiments, the width and depth of the axial microgroove 100 are both on the micrometer scale, as are the width and depth of the circumferential microgroove 200. This configuration confines the axial microgroove 100 and circumferential microgroove 200 to the micrometer scale, forming a micrometer-scale anchoring network. The cross-sectional area of ​​the axial microgroove 100 and circumferential microgroove 200 is much larger than the particle size of the filler in the adhesive, ensuring sufficient wetting of the adhesive. Simultaneously, the cross-sectional area of ​​the axial microgroove 100 and circumferential microgroove 200 is much smaller than the macroscopic dimensions of the part, avoiding the risk of them acting as crack initiation points. This surface texture at this size level ensures the formation of a large-scale micro-mechanical anchoring network with the adhesive, improving interfacial adhesion with almost no change to the macroscopic structure and stiffness of the cam.

[0072] In some preferred embodiments, the cross-sections of both the axial microgroove 100 and the circumferential microgroove 200 are semi-circular and have a diameter of 10 micrometers to 50 micrometers. For example, the diameters of the axial microgroove 100 and the circumferential microgroove 200 are set to 20 micrometers.

[0073] To further optimize the gradient distribution of the axial microgroove 100 and make it feasible, the position of the axial microgroove 100 can be designed to follow a certain functional distribution law, and its position can be reflected by angles. In some specific embodiments, on the projection plane perpendicular to the cam body axis, the line connecting the axial microgroove 100 and the center of the cam body is the axial groove position line, and the angle between the major axis of the cam body and the adjacent axial groove position line, and the angle between two adjacent axial groove position lines are all interval angles.

[0074] In a Cartesian coordinate system with the center of the cam body as the origin, the minor axis of the cam body as the X-axis, and the major axis of the cam body as the Y-axis, all axial groove position lines in the first quadrant are symmetrical about the Y-axis with all axial groove position lines in the second quadrant, all axial groove position lines in the third quadrant are symmetrical about the X-axis with all axial groove position lines in the second quadrant, and all axial groove position lines in the fourth quadrant are symmetrical about the X-axis with all axial groove position lines in the first quadrant.

[0075] All interval angles in the first quadrant conform to the interval angle function:

[0076] ,

[0077] Where N is the number of all axial groove position lines in the first quadrant; x is the interval angle number, x∈[1,N], and the xth interval angle is the angle between the (x-1)th axial groove position line and the xth axial groove position line; This represents the angle value corresponding to the x-th interval angle in the first quadrant; This indicates the angle value between the major axis of the cam body and the position line of the first axial groove. In other words, the interval angles are numbered in a clockwise direction.

[0078] All axial micro-grooves 100 appear as points on the outer contour of the cam in a Cartesian coordinate system. It should be noted that the axial groove position lines are virtual lines and do not exist in the solid structure of the cam.

[0079] For example, N is 40, which means that there are 160 axial microgrooves 100 on the circumferential side of the cam body.

[0080] In some preferred embodiments, any axial microgroove 100 extends to the two ends of the circumferential side surface of the cam body; any circumferential microgroove 200 is distributed around the circumference.

[0081] Of course, it is also possible for some axial microgrooves 100 not to extend to the two ends of the circumferential side surface, and for some circumferential microgrooves 200 not to be distributed around the entire circumference.

[0082] Based on the cam described above, this application also provides a wave generator, which includes a flexible bearing and the aforementioned cam, with the cam fitted inside the flexible bearing. Since this wave generator has the aforementioned cam, the beneficial effects of the cam on the wave generator are described above and will not be repeated here.

[0083] Based on the wave generator described above, this application also provides a harmonic reducer, which includes a flexible wheel, a rigid wheel, and the aforementioned wave generator. The flexible wheel is fitted inside the rigid wheel, and the flexible wheel and the rigid wheel mesh with each other. The wave generator is fitted inside the flexible wheel. Since this harmonic reducer has the aforementioned wave generator, the beneficial effects brought by the wave generator to the harmonic reducer are described above and will not be repeated here.

[0084] This application also provides a cam design method, applicable to designing cams for harmonic reducers, the method comprising:

[0085] An axially extending microgroove 100 is constructed on the circumferential surface of the cam body, including:

[0086] Establish a Cartesian coordinate system with the center of the cam body as the origin, the minor axis of the cam body as the X-axis and the major axis of the cam body as the Y-axis, and obtain the quarter cam profile located in the first quadrant. Divide the quarter cam profile into the major axis region 11, the transition region 12 and the minor axis region 13 in a clockwise direction.

[0087] In the first quadrant, N axial groove position lines are pre-defined, connecting the origin and the quarter-cam profile, such as... Figure 3 As shown, the angle between the major axis of the cam body and the adjacent axial groove position line, and the angle between two adjacent axial groove position lines are used as the interval angle, and the angle between the minor axis of the cam body and the adjacent axial groove position line is used as the end angle.

[0088] Considering that the cosine function has the property of being smooth and continuous, which can ensure that the distribution density of the axial microgroove 100 obtained according to this design changes smoothly, the cosine function is chosen as the basic model.

[0089] The interval angle function, constrained on a quarter-cam profile, is constructed as follows:

[0090] ,

[0091] in ,

[0092] In equation (1), x is the interval angle number, x∈[1,N], and the x-th interval angle is the angle between the (x-1)-th axial groove position line and the x-th axial groove position line. This represents the angle value corresponding to the x-th interval angle in the first quadrant. The angle value represents the interval angle between the major axis of the cam body and the position line of the first axial groove. C is the reference interval angle and represents the average interval angle value without considering the density change of the axial groove position line. C determines the overall density level of the axial micro-groove 100. D is the interval angle modulation amplitude and is used to control the variation of the interval angle around C. D determines the drastic degree of density change of the axial micro-groove 100. t is a normalization parameter. The position parameter represents the position where the linear density of the axial groove is the minimum and determines the position where the maximum spacing angle appears in the normalized coordinates; that is, the major axis of the cam body is set to 0° and the minor axis of the cam body is set to 90°.

[0093] according to and The mapping relationship between the two is established as follows: ,

[0094] Combining equations (1), (2), and (3), when hour, Reaching the maximum value will result in the lowest density point of the axial groove position line corresponding to the maximum value of the spacing angle. To ensure that this lowest density point appears at the center of transition region 12, i.e. At the corresponding position on the quarter cam profile, obtain Considering that in actual situations the minimum contact pressure position of the cam will appear at a position slightly higher than... The position, in order to make the lowest density point of the axial groove position line appear at the position of minimum contact pressure, will Revised to ,because The value of is determined by the geometric and mechanical properties of the cam and is not affected by N, therefore Set it to a constant value;

[0095] The objective function is established to minimize the absolute error between the sum of all interval angles and the included angles at the ends and the total angle of 90° corresponding to the first quadrant. The included angle δ is the angle between the Nth axial groove position line and the minor axis of the cam body. The constraint conditions for the objective function are set as follows: To control the overall density of the axial groove position line in the minor axis region 13 to be between the overall density of the major axis region 11 and the overall density of the transition region 12, thus achieving macroscopic control of the density gradient and simultaneously controlling the smoothness of the density change of the axial groove position line to achieve microscopic smoothness and avoid sudden density discontinuities, the first constraint equation is established: (5), The settings are determined based on engineering design requirements and actual machining precision. There is a basic relationship between parameters C and D: (6), with equation (6) as the second constraint equation;

[0096] For N and By assigning values, the values ​​of parameters C and D can be obtained by solving the first constraint equation and the second constraint equation of the objective function [that is, equation (4)] [that is, equation (5) and equation (6)]. Further solve the interval angle function to obtain the position of all axial groove position lines in the first quadrant.

[0097] Based on all the axial groove position lines in the first quadrant, the axial groove position lines in the second quadrant are obtained with the Y-axis as the line of symmetry. Based on all the axial groove position lines in the first and second quadrants, the axial groove position lines in the fourth and third quadrants are obtained with the X-axis as the line of symmetry.

[0098] The position of the axial micro-groove 100 is obtained based on the position of all axial groove position lines, and all axial groove position lines correspond one-to-one with all axial micro-groove 100.

[0099] This setup constructs the interval angle function of the axial microgroove 100 based on the cosine function and provides a solution process including the objective function, constraints, and parameter definitions to achieve the density gradient distribution of the axial microgroove 100, ensuring the high feasibility of the solution. The resulting cam with surface texture has a high surface texture density in the double-peak high-pressure zone between the long and short axes of the cam, while having a low surface texture density in the transition region 12 between the long and short axes, giving it an overall characteristic of being dense at both ends and sparse in the middle. After bonding with the flexible bearing, the anchoring ability of the surface texture matches the contact pressure distribution of the cam profile, achieving a precise match between performance, structure, and working conditions, and promoting the reasonable distribution and effective storage of adhesive on the mating surface of the cam and the flexible bearing.

[0100] In some alternative embodiments, N is assigned the value 40, and The value is assigned to 0.1, and the parameters can be obtained by solving the constraint equations of the objective function. , To provide a feasible preferred solution. For example... Figure 4 As shown, the angle values ​​of all interval angles in the first quadrant were obtained. Figure 5 As shown, the angular positions (i.e. the angles with the major axis) of all axial groove position lines in the first quadrant are obtained, thus obtaining the angular positions of the axial micro-grooves 100 that correspond one-to-one with the axial groove position lines.

[0101] In some optional embodiments, the cam design method further includes constructing multiple circumferentially extending circumferential microgrooves 200 on the circumferential surface of the cam body, with the microgrooves distributed at equal density along the axial direction of the cam body. This creates a cross-grid-like surface texture on the circumferential surface of the cam body, improving adhesive retention and anchoring capabilities.

[0102] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0103] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0104] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0105] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0106] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0107] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A cam, characterized in that The cam is applied to a harmonic reducer, and comprises a cam body, a surface texture is arranged on the circumferential surface of the cam body, the surface texture comprises intersectingly distributed axial microgrooves and circumferential microgrooves, the axial microgrooves extend along the axial direction of the cam body, and the circumferential microgrooves extend along the circumferential direction of the cam body. The circumferential surface of the cam body comprises a long-axis region, a transition region and a short-axis region, the long-axis region is arranged at both ends of the long-axis direction of the cam body, the short-axis region is arranged at both ends of the short-axis direction of the cam body, and the transition region is arranged between the long-axis region and the short-axis region. The density of the surface texture in the long-axis region is greater than the density of the surface texture in the short-axis region, and the density of the surface texture in the short-axis region is greater than the density of the surface texture in the transition region. In a projection plane perpendicular to the axial direction of the cam body, the line connecting the axial microgrooves and the center of the cam body is an axial groove position line, the included angle between the long axis of the cam body and the adjacent axial groove position line, and the included angle between two adjacent axial groove position lines are all interval angles. In a plane rectangular coordinate system with the center of the cam body as the origin, the short axis of the cam body as the X-axis and the long axis of the cam body as the Y-axis, all the axial groove position lines in the first quadrant are symmetric about the Y-axis with all the axial groove position lines in the second quadrant, all the axial groove position lines in the third quadrant are symmetric about the X-axis with all the axial groove position lines in the second quadrant, and all the axial groove position lines in the fourth quadrant are symmetric about the X-axis with all the axial groove position lines in the first quadrant. All the interval angles in the first quadrant satisfy an interval angle function: ， wherein N is the number of all the axial groove position lines in the first quadrant; x is the interval angle number, x∈[1, N], the xth interval angle is the included angle between the x-1th axial groove position line and the xth axial groove position line; represents the angle value corresponding to the x-th said interval angle in the first quadrant; an angle value representing the interval angle between the long axis of the cam body and the position line of the first axial groove.

2. The cam according to claim 1, wherein The circumferential microgrooves are equally distributed in the axial direction of the cam body. The distribution density of the axial microgrooves in the circumferential direction of the cam body changes in a gradient manner.

3. The cam of claim 2 wherein, In the long-axis region, the interval between two adjacent axial microgrooves gradually decreases with the degree of approaching the long axis. In the short-axis region, the interval between two adjacent axial microgrooves gradually decreases with the degree of approaching the short axis. In the transition region, the interval between two adjacent axial microgrooves gradually increases with the degree of approaching the center position of the transition region.

4. The cam of claim 1 wherein, The cross sections of the axial microgrooves and the circumferential microgrooves are arc-shaped; and / or, The width and depth of the axial microgrooves are both micrometers, and the width and depth of the circumferential microgrooves are both micrometers.

5. The cam of claim 1 wherein, The cross sections of the axial microgrooves and the circumferential microgrooves are semicircular arcs with a diameter of 10 micrometers to 50 micrometers.

6. The cam of claim 1 wherein, Any axial microgroove extends to the two end edges of the circumferential surface of the cam body. Any circumferential microgroove is circumferentially distributed.

7. A wave generator, characterized by The cam as claimed in any one of claims 1-6 is sleeved in a flexible bearing.

8. A harmonic reducer characterized by, The wave generator as claimed in claim 7.

9. A cam design method characterized by, A method for designing a cam for a harmonic reducer, the method comprising: An axially extending axial micro groove is formed on the peripheral side of the cam body, comprising: A plane rectangular coordinate system is established with the center of the cam body as the origin, the minor axis of the cam body as the X-axis and the major axis of the cam body as the Y-axis, and a quarter cam profile located in the first quadrant is obtained, and the quarter cam profile is divided into a major axis region, a transition region and a minor axis region in a clockwise direction; N axial groove position lines connecting the origin and the quarter cam profile are preset in the first quadrant, and the included angle between the major axis of the cam body and the adjacent axial groove position line and the included angle between two adjacent axial groove position lines are taken as the interval angle, and the included angle between the minor axis of the cam body and the adjacent axial groove position line is taken as the terminal included angle; An interval angle function defined on the quarter cam profile is constructed; A target function is established based on the absolute error value between the interval angle function, the sum of the terminal included angles and the total angle 90° corresponding to the first quadrant, and the values of parameters C and D can be obtained by solving the constraint equation of the target function, and the positions of all the axial groove position lines in the first quadrant are further solved according to the values of C and D; The axial groove position lines in the second quadrant are obtained according to all the axial groove position lines in the first quadrant with the Y-axis as the symmetry line, and the axial groove position lines in the third quadrant and the fourth quadrant are obtained according to all the axial groove position lines in the first quadrant and the second quadrant with the X-axis as the symmetry line; The positions of the axial micro grooves are obtained according to the positions of all the axial groove position lines, and all the axial groove position lines correspond to all the axial micro grooves one by one.

10. The cam design method of claim 9, wherein The interval angle function is constructed as: ， wherein , In formula (1), x is the interval angle number, x∈[1, N], the xth interval angle is the included angle between the x-1th axial groove position line and the xth axial groove position line, represents the angle value corresponding to the xth interval angle in the first quadrant, C is the reference interval angle and represents the average interval angle value when the density variation of the axial groove position line is not considered, D is the interval angle modulation amplitude and is used to control the variation amplitude of the interval angle around C, t is the normalization parameter and represents the position parameter at the minimum density of the axial groove position line and determines the position of the maximum interval angle in the normalized coordinates; According to and , the mapping relationship between the two is established as: , In conjunction with equation (1), equation (2) and equation (3), in order to make the density minimum point of the axial groove position line appear at the minimum contact pressure position, the following is set as a constant value: is modified to , and is set as a constant value; The objective function is: The end angle δ is the angle between the Nth axial slot position line and the minor axis of the cam body. The constraint condition of the target function is set: in order to control the overall density of the axial groove position line in the minor axis region to be between the overall density of the major axis region and the overall density of the transition region, and to control the smoothness of the density variation of the axial groove position line; The first constraint equation is established as (5), According to the engineering design requirements and actual machining precision There is a basic relationship between the parameters C, D: (6) as the second constraint equation; to N and are assigned values, the values of C and D are obtained by solving the first and second constraint equations.

11. The cam design method of claim 10, wherein, N is assigned a value of 40, and a value of 0.1, the parameters , .

12. The cam design method of claim 11, wherein, Further comprising forming a circumferential micro groove extending in the circumferential direction on the peripheral side of the cam body, and the circumferential micro groove is formed with multiple circumferential micro grooves and is distributed at equal density in the axial direction of the cam body.

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