Cams, harmonic reducers and industrial robots

Abstract

The utility model discloses a cam, a harmonic reducer and an industrial robot, and relates to the field of robot technology. By setting a strip hole in any one of the first area, the second area, the third area and the fourth area of ​​the cam, the strip hole extends along the circumference of the cam and is located on a side close to the outer wall of the cam. When the cam is embedded in the flexible bearing, the flexible wheel is sleeved on the flexible bearing and matched with the rigid wheel, the contact pressure generated between the flexible wheel and the rigid wheel will act on the cam. Since the cam is provided with a strip hole, the outer wall of the cam corresponding to the strip hole can produce a slight elastic deformation under the extrusion of the contact pressure, that is, the strip hole can be deformed so that the outer tooth part of the flexible wheel adjusts the meshing angle according to the change of the meshing position, thereby reducing the contact pressure on the flexible wheel, and then reducing the tooth root stress on the flexible wheel, so as to reduce the risk of plastic deformation or fracture of the flexible wheel and increase the service life of the flexible wheel.

Description

Technical Field

[0001] The utility model relates to the technical field of robots, in particular to a cam, a harmonic reducer and an industrial robot. Background Art

[0002] The harmonic reducer includes a wave generator, a flexspline and a rigid wheel. The flexspline is sleeved on the wave generator, and part of the external teeth of the flexspline mesh with part of the internal teeth of the rigid wheel. When the cam of the wave generator rotates, the flexspline is squeezed and deformed, so that the external teeth of the flexspline mesh with different internal teeth of the rigid wheel, thereby driving the flexspline or the rigid wheel to rotate. During the assembly stage, the wave generator needs to have an interference fit with the flexspline, and the external tooth segment of the flexspline is deformed outward in a trumpet shape. Since the flexspline will generate torque deformation after being subjected to torque load, it is easy for the flexspline to generate a large contact pressure with the rigid wheel in the area between the long axis and the short axis of the cam, thereby generating a large tooth root stress. The flexspline is prone to plastic deformation or fracture, resulting in a reduced service life of the flexspline. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model provides a cam that can reduce the tooth root stress of the flexible wheel and increase the service life of the flexible wheel.

[0004] The utility model also provides a harmonic reducer and an industrial robot having the cam.

[0005] According to the cam of the first aspect of the utility model, a plane rectangular coordinate system is established with the short axis of the cam as the X-axis, the long axis of the cam as the Y-axis, and the intersection of the X-axis and the Y-axis as the origin, and the part of the cam in the first quadrant of the plane rectangular coordinate system is defined as the first area, the part of the cam in the second quadrant of the plane rectangular coordinate system is defined as the second area, the part of the cam in the third quadrant of the plane rectangular coordinate system is defined as the third area, and the part of the cam in the fourth quadrant of the plane rectangular coordinate system is defined as the fourth area, and at least one of the first area, the second area, the third area and the fourth area is provided with a strip hole, and the strip hole extends along the circumference of the cam and is located on the side close to the outer side wall of the cam.

[0006] The cam according to the embodiment of the utility model has at least the following beneficial effects:

[0007] By setting a strip hole in any one of the first area, the second area, the third area and the fourth area of ​​the cam, the strip hole extends along the circumference of the cam and is located on a side close to the outer side wall of the cam. When the cam is embedded in the flexible bearing, the flexible wheel is sleeved on the flexible bearing and matched with the rigid wheel, the contact pressure generated between the flexible wheel and the rigid wheel will act on the cam. Since the cam is provided with the strip hole, the outer side wall of the cam corresponding to the strip hole can produce a slight elastic deformation under the extrusion of the contact pressure, thereby reducing the contact pressure on the flexible wheel, and then reducing the tooth root stress on the flexible wheel, so as to reduce the risk of plastic deformation or fracture of the flexible wheel and increase the service life of the flexible wheel.

[0008] According to some embodiments of the present invention, the first area, the second area, the third area and the fourth area are all provided with the strip-shaped holes, and the strip-shaped holes in adjacent areas are arranged at intervals.

[0009] According to some embodiments of the present invention, the sum of the central angles of the inner walls of all the strip-shaped holes along one side of the radial direction of the cam corresponding to the origin is γ, which satisfies 180°≤γ≤320°.

[0010] According to some embodiments of the utility model, along the radial direction of the cam, the minimum distance between the side of the strip hole close to the outer side wall of the cam and the outer side wall of the cam is L1, and the maximum distance between the side of the strip hole close to the outer side wall of the cam and the outer side wall of the cam is L2, satisfying: 2mm≤L1≤5mm, 2mm≤L2≤5mm.

[0011] According to some embodiments of the utility model, the cam is provided with a center hole, and along the radial direction of the cam, the maximum distance between the inner wall of the center hole and the outer wall of the cam is L3, and the minimum width of the strip hole is h, satisfying: 1mm≤h≤(L3-4mm), L3>5mm.

[0012] According to some embodiments of the utility model, one of the first area, the second area, the third area or the fourth area is provided with a strip hole, and on the projection plane perpendicular to the rotation axis of the cam, the line connecting the end of the strip hole closest to the long axis of the cam and the center of the cam is LA, and the angle between LA and the long axis is α, which satisfies: 10°≤α≤30°.

[0013] According to some embodiments of the present invention, a line connecting an end of the strip hole closest to the short axis and the center of the cam is LB, and an angle between LB and LA is β, which satisfies: 45°≤β≤80°.

[0014] According to some embodiments of the present invention, a line connecting an end of the strip hole closest to the short axis and the center of the cam is LB, and an angle between LB and the short axis is θ, which satisfies: 10°≤θ≤30°.

[0015] According to some embodiments of the present invention, the strip-shaped hole is a through hole, and the through hole passes through both axial ends of the cam.

[0016] The harmonic reducer according to the embodiment of the second aspect of the utility model comprises the cam described in the above embodiment.

[0017] The harmonic reducer according to the embodiment of the utility model has at least the following beneficial effects:

[0018] By adopting the cam of the first embodiment, a strip hole is set in any one of the first area, the second area, the third area and the fourth area of ​​the cam, and the strip hole extends along the circumference of the cam and is located on a side close to the outer wall of the cam. When the cam is embedded in the flexible bearing, the flexible wheel is sleeved on the flexible bearing and matched with the rigid wheel, the contact pressure generated between the flexible wheel and the rigid wheel will act on the cam. Since the cam is provided with a strip hole, the outer wall of the cam corresponding to the strip hole can produce a slight elastic deformation under the extrusion of the contact pressure, thereby reducing the contact pressure on the flexible wheel, and then reducing the tooth root stress on the flexible wheel, so as to reduce the risk of plastic deformation or fracture of the flexible wheel and increase the service life of the flexible wheel.

[0019] According to the third aspect of the present utility model, the harmonic reducer includes: a rigid wheel having an internal tooth portion;

[0020] A flexible wheel, provided with an outer tooth portion meshing with the inner tooth portion;

[0021] a wave generator mounted in the inner hole of the flexspline, the wave generator comprising a flexible bearing and the cam described in the first aspect, the flexible bearing being mounted on the outer side of the cam, the cam being configured to mesh the outer tooth portion with the inner tooth portion when rotating;

[0022] The strip-shaped hole can cause the outer side wall of the cam to deform elastically, so that the outer tooth portion can adjust the meshing angle in accordance with the change of the meshing position during the meshing process with the inner tooth portion.

[0023] The industrial robot according to the fourth embodiment of the utility model includes the harmonic reducer described in the above embodiment.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0026] Figure 1 This is a schematic diagram of the structure of a cam in one embodiment of the utility model;

[0027] Figure 2 It is a structural schematic diagram of a harmonic reducer of an embodiment of the utility model;

[0028] Figure 3 This is an exploded view of a harmonic reducer according to an embodiment of the utility model;

[0029] Figure 4 This is a cross-sectional view of a harmonic reducer according to an embodiment of the utility model;

[0030] Figure 5 It is a cross-sectional view of a harmonic reducer of another embodiment of the utility model;

[0031] Figure 6 The diagram is a comparative diagram of tooth root stress of a flexible spline according to an embodiment of the utility model and a flexible spline in related technology.

[0032] Reference numerals:

[0033] Harmonic reducer 1000;

[0034] Wave generator 100; cam 110; center hole 111; strip hole 112; first area 113; second area 114; third area 115; fourth area 116; flexible bearing 120;

[0035] Flexspline 200; cylinder 210; external tooth 220; mounting portion 230; first mounting hole 231;

[0036] The rigid wheel 300; the inner tooth portion 310; the second mounting hole 320;

[0037] Crossed roller bearing 400 ; inner ring 410 ; outer ring 420 ; raceway 430 . DETAILED DESCRIPTION

[0038] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0039] In the description of the present invention, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0040] In the description of the present utility model, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0041] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0042] The harmonic reducer includes a wave generator, a flexspline and a rigid wheel. The flexspline is sleeved on the wave generator, and part of the external teeth of the flexspline mesh with part of the internal teeth of the rigid wheel. When the cam of the wave generator rotates, the flexspline is squeezed and deformed, so that the external teeth of the flexspline mesh with different internal teeth of the rigid wheel, thereby driving the flexspline or the rigid wheel to rotate. During the assembly stage, the wave generator needs to have an interference fit with the flexspline, and the external tooth segment of the flexspline is deformed outward in a trumpet shape. Since the flexspline will generate torque deformation after being subjected to torque load, the area between the long axis and the short axis of the cam of the flexspline is prone to generate a large contact pressure with the rigid wheel, which in turn generates a large tooth root stress. The flexspline is prone to plastic deformation or fracture, resulting in a reduced service life of the flexspline.

[0043] In order to reduce the tooth root stress of the flexible wheel 200 and increase the service life of the flexible wheel 200, refer to Figure 1As shown, a cam 110 according to an embodiment of the present invention is used in a harmonic reducer 1000. The cam 110 rotates to cause the flexible wheel 200 of the harmonic reducer 1000 to produce elastic deformation, thereby achieving transmission of motion and power. In an embodiment of the utility model, a plane rectangular coordinate system is established with the short axis S2 of the cam 110 as the X-axis, the long axis S1 of the cam 110 as the Y-axis, and the intersection of the X-axis and the Y-axis as the origin O, and the portion of the cam 110 in the first quadrant of the plane rectangular coordinate system is defined as the first area 113, the portion of the cam 110 in the second quadrant of the plane rectangular coordinate system is defined as the second area 114, the portion of the cam 110 in the third quadrant of the plane rectangular coordinate system is defined as the third area 115, and the portion of the cam 110 in the fourth quadrant of the plane rectangular coordinate system is defined as the fourth area 116, and at least one of the first area 113, the second area 114, the third area 115 and the fourth area 116 is provided with a strip hole 112, and the strip hole 112 extends along the circumference of the cam 110 and is located on a side close to the outer wall of the cam 110.

[0044] It should be noted that the side of the strip hole 112 close to the outer wall of the cam 110 can be interpreted as: taking the center of the cam 110 as the dot, and drawing an auxiliary circle starting from half the distance between the inner wall of the center hole 111 of the cam 110 and the end point of the long axis of the cam 110. Taking the first area 113 provided with the strip hole 112 as an example, the auxiliary circle divides the first area 113 into a first part and a second part distributed along the radial direction of the cam 110, the first part is located on the side close to the outer wall of the cam 110, the second part is located on the side close to the center of the cam 110, and the strip hole 112 is set in the first part. When the second area 114, the third area 115 and the fourth area 116 are provided with the strip hole 112, the positional relationship of the strip hole 112 is similar, and in order to avoid repetition, it will not be repeated here.

[0045] By adopting the above scheme, when the cam 110 is embedded in the flexible bearing 120, and the flexible wheel 200 is sleeved on the flexible bearing 120 and cooperates with the rigid wheel 300, the contact pressure generated between the flexible wheel 200 and the rigid wheel 300 will act on the cam 110. Since the strip hole 112 is in the shape of a long strip, the outer wall of the cam 110 at the strip hole 112 can produce a slight elastic deformation under the extrusion of the contact pressure, thereby reducing the contact pressure on the flexible wheel 200, and further reducing the tooth root stress on the flexible wheel 200, so as to reduce the risk of plastic deformation or fracture of the flexible wheel 200 and increase the service life of the flexible wheel 200.

[0046] In order to further reduce the tooth root stress of the flexible wheel 200, refer to Figure 1As shown, in the embodiment of the utility model, the first area 113, the second area 114, the third area 115 and the fourth area 116 are all provided with strip holes 112, and a plurality of strip holes 112 are arranged around the rotation axis of the cam 110, and the strip holes 112 in adjacent areas are arranged at intervals. It should be noted that the strip holes 112 in adjacent areas are arranged at intervals, which can be explained as follows: the strip holes 112 in the first area 113 and the strip holes 112 in the second area 114 are arranged at intervals; the strip holes 112 in the second area 114 and the strip holes 112 in the third area 115 are arranged at intervals; the strip holes 112 in the third area 115 and the strip holes 112 in the fourth area 116 are arranged at intervals; the strip holes 112 in the fourth area 116 and the strip holes 112 in the first area 113 are arranged at intervals.

[0047] It is understandable that by providing the strip holes 112 in the first area 113, the second area 114, the third area 115 and the fourth area 116, the cam 110 can be elastically deformed on the multiple outer side walls corresponding to the multiple strip holes 112, thereby further reducing the tooth root stress on the flexible wheel 200. Among them, the adjacent strip holes 112 are arranged at intervals, which can improve the stability of the overall structure of the cam 110. As an alternative embodiment, the cam 110 can also be provided with strip holes 112 only in the first area 113 and the third area 115; or, the strip holes 112 are only provided in the second area 114 and the fourth area 116, and the appropriate setting method is selected according to the actual situation.

[0048] In order to improve the stability of the cam 110 during the rotation process, in the embodiment of the utility model, the first area 113, the second area 114, the third area 115 and the fourth area 116 are all provided with strip holes 112, and the strip holes 112 of the first area 113 and the strip holes 112 of the second area 114 are symmetrically arranged with the long axis S1 of the cam 110 as the symmetry axis, the strip holes 112 of the second area 114 and the strip holes 112 of the third area 115 are symmetrically arranged with the short axis S2 of the cam 110 as the symmetry axis, and the strip holes 112 of the third area 115 and the strip holes 112 of the fourth area 116 are symmetrically arranged with the long axis S1 of the cam 110 as the symmetry axis. By adopting this solution, the situation that the cam 110 is not stable due to uneven weight distribution can be reduced. By setting the adjacent strip holes 112 as a symmetrical design, the stability and reliability of the cam 110 during the rotation process can be improved, and the noise can be reduced, thereby improving the user experience.

[0049] In the embodiment of the utility model, when the first area 113, the second area 114, the third area 115 and the fourth area 116 are all provided with the strip holes 112, the sum of the central angles of the inner wall of one side of the cam 110 corresponding to the origin along the radial direction of all the strip holes 112 is γ, which satisfies 180°≤γ≤320°, for example, γ can be 180°, 200°, 230°, 250°, 280°, 320°. By limiting the sum of the central angles γ corresponding to all the strip holes 112 within the range of 180° to 320°, the elastic deformation amount of the cam 110 on the multiple outer side walls corresponding to the multiple strip holes 112 is further increased, and the tooth root stress of the flexible wheel 200 is further reduced.

[0050] Reference Figure 6 As shown, Figure 6 The abscissa in represents the number of teeth of the flexspline 200 , and the numbers 1, 5, 9, 13 in the abscissa represent the 1st tooth, the 5th tooth, the 9th tooth, and the 13th tooth on the flexspline 200 , respectively; the ordinate represents the maximum principal stress on the tooth root of the flexspline 200 . Figure 6 The dotted line in the figure represents the solution of this embodiment, and the solid line represents the solution in the related art. Figure 6 It can be seen from the comparison in that after the strip hole 112 is set in the cam 110, the maximum principal stress of the tooth root of the flexible wheel 200 is mostly lower than the solution without the strip hole 112, that is, the average principal stress of the flexible wheel 200 as a whole is reduced. Therefore, the solution of setting the strip hole 112 can reduce the tooth root stress of the flexible wheel 200, reduce the risk of plastic deformation or fracture of the flexible wheel 200, and increase the service life of the flexible wheel 200.

[0051] Reference Figure 1 As shown, in the embodiment of the utility model, the strip hole 112 is a through hole, which passes through the axial ends of the cam 110. Therefore, the elastic deformation of the outer wall of the cam 110 can be increased, and the contact pressure on the flexible wheel 200 can be further reduced, thereby reducing the tooth root stress on the flexible wheel 200. As an alternative embodiment, the strip hole 112 can also be a blind hole, which only passes through one end of the cam 110, and the other end of the blind hole is in a closed state. The appropriate setting form is selected according to the actual situation.

[0052] Reference Figure 1As shown, in the embodiment of the utility model, along the radial direction of the cam 110, the minimum distance between the side of the strip hole 112 close to the outer side wall of the cam 110 and the outer side wall of the cam 110 is L1, and the maximum distance between the side of the strip hole 112 close to the outer side wall of the cam 110 and the outer side wall of the cam 110 is L2, which satisfies: 2mm≤L1≤5mm, 2mm≤L2≤5mm. For example, the value of L1 can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 5mm, etc.; the value of L2 can be 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 5mm, etc. L1 and L2 reflect the distance between the strip hole 112 and the outer side wall of the cam 110.

[0053] When L1 is less than 2 mm and L2 is less than 2 mm, the distance between the strip hole 112 and the outer side wall of the cam 110 is too close, which may cause the cam 110 to be plastically deformed when subjected to a large pressure, and may even be broken in severe cases, causing the cam 110 to be scrapped and ineffective. In addition, the cam 110 is difficult to manufacture and process. When L1 is greater than 5 mm and L2 is greater than 5 mm, the distance between the strip hole 112 and the outer side wall of the cam 110 is too far, causing the outer side wall of the cam 110 to be difficult to elastically deform, and the contact pressure on the flexible wheel 200 cannot be effectively reduced, resulting in a large tooth root stress on the flexible wheel 200. Therefore, by limiting the size range of L1 and L2 to between 2 mm and 5 mm, that is, the distance between the strip hole 112 and the outer wall of the cam 110 is between 2 mm and 5 mm, the outer wall of the cam 110 has a certain strength, which can reduce the occurrence of plastic deformation and fracture, and can also produce a suitable elastic deformation, thereby reducing the root stress of the flexible wheel 200, reducing the risk of plastic deformation or fracture of the flexible wheel 200, and improving the service life of the flexible wheel 200.

[0054] Reference Figure 1As shown, in the embodiment of the utility model, the cam 110 is provided with a center hole 111, and the center hole 111 is used to be installed and matched with the output shaft of the motor, so as to drive the cam 110 to rotate. Along the radial direction of the cam 110, the maximum distance between the inner wall of the center hole 111 and the outer wall of the cam 110 is L3, and the minimum width of the strip hole 112 is h, which satisfies: 1mm≤h≤(L3-4mm), L3>5mm. For example, h can be 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, etc. L3-4mm reflects the distance between the inner wall of the strip hole 112 and the center hole 111. When h is less than 1mm, the production and manufacturing difficulty of the strip hole 112 is large, and the processing is difficult, and the outer wall of the cam 110 is difficult to produce suitable elastic deformation, resulting in the inability to reduce the tooth root stress on the flexible wheel 200. When h is greater than (L3-4mm), the distance between the strip hole 112 and the center hole 111 is too close, which may easily reduce the strength of the inner wall of the center hole 111, and may cause adverse effects such as deformation and rupture. Moreover, the larger width of the strip hole 112 may easily affect the overall strength of the cam 110, and may cause adverse conditions such as plastic deformation and fracture of the cam 110. Therefore, by reasonably designing the range of the thickness h of the strip hole 112, the overall cam 110 and the inner wall of the center hole 111 can have appropriate strength, and at the same time, the outer wall of the cam 110 can produce appropriate elastic deformation, thereby reducing the root stress of the flexible wheel 200, reducing the risk of plastic deformation or fracture of the flexible wheel 200, and increasing the service life of the flexible wheel 200.

[0055] Reference Figure 1 As shown, in the embodiment of the present invention, on the projection plane perpendicular to the axis of the rotating shaft of the cam 110, the line connecting the end of the strip hole 112 closest to the long axis S1 and the center of the cam 110 is LA, and the angle between LA and the long axis S1 is α, which satisfies: 10°≤α≤30°, for example, α can be 10°, 12°, 15°, 17°, 20°, 25°, 30°. It can be understood that when α is less than 10°, since the cam 110 is the main load-bearing area at the long axis S1, when the strip hole 112 extends to an area too close to the long axis S1, it is easy to cause the load-bearing capacity of the cam 110 to decrease, so that the overall performance of the harmonic reducer 1000 is reduced. When α is greater than 30°, the overall length of the strip hole 112 along the circumference of the cam 110 is shorter, and the outer wall of the cam 110 is difficult to produce effective elastic deformation under the contact pressure applied by the flexible wheel 200 and the rigid wheel 300, resulting in higher tooth root stress of the flexible wheel 200 and reducing the service life of the flexible wheel 200.

[0056] Therefore, by reasonably designing the range of the angle α between LA and the long axis S1, it is ensured that the strip hole 112 is not too close to the long axis S1, so as to ensure the load-bearing capacity of the cam 110. Moreover, the strip hole 112 has a suitable length, and can produce a suitable elastic deformation to reduce the contact pressure on the flexible wheel 200, thereby reducing the tooth root stress on the flexible wheel 200, reducing the risk of plastic deformation or fracture of the flexible wheel 200, and improving the service life of the flexible wheel 200.

[0057] It should be noted that, generally, the contact pressure applied by the flexible wheel 200 is greatest at the center of the outer wall of the first area 113, the second area 114, the third area 115 and the fourth area 116. Therefore, arranging the strip hole 112 near the center of the first area 113, the second area 114, the third area 115 and the fourth area 116 can effectively reduce the contact pressure on the flexible wheel 200.

[0058] Reference Figure 1 As shown, in the embodiment of the utility model, at most one strip hole 112 is provided in any one of the first area 113, the second area 114, the third area 115 and the fourth area 116, that is, at most one strip hole 112 is provided in each area. The line connecting the end of the strip hole 112 closest to the short axis S2 and the center of the cam 110 is LB, and the angle between LB and LA is β, which satisfies: 45°≤β≤80°, for example, the angle of β can be 45°, 50°, 60°, 70°, 80°, etc. It can be understood that the angle β between LB and LA reflects the length of the strip hole 112 in the circumferential direction of the cam 110, and the larger β is, the longer the length of the strip hole 112 is. When β is less than 45°, the length of the strip hole 112 is short, and it is difficult for the outer wall of the cam 110 to produce effective elastic deformation under the contact pressure applied by the flexible wheel 200 and the rigid wheel 300. When β is greater than 80°, the length of the strip hole 112 is long, which may easily reduce the overall strength of the cam 110, and the outer wall of the cam 110 may easily produce plastic deformation, thereby reducing reliability. Therefore, by reasonably designing the size of the angle β between LB and LA, the strip hole 112 can have a suitable length, which is conducive to the cam 110 to produce effective elastic deformation under the contact pressure applied by the flexible wheel 200 and the rigid wheel 300, while also ensuring the overall strength of the cam 110.

[0059] Reference Figure 1As shown, in the embodiment of the utility model, the angle between LB and the short axis S2 is θ, which satisfies: 10°≤θ≤30°, for example, θ can be 10°, 12°, 15°, 17°, 20°, 25°, 30°. When θ is less than 10°, the distance between adjacent strip holes 112 is relatively close, which easily leads to the risk of deformation, fracture, etc. of the cam 110 between adjacent strip holes 112, and the processing is difficult. When θ is greater than 30°, the overall length of the strip hole 112 along the circumference of the cam 110 is relatively short, and the outer side wall of the cam 110 is difficult to produce effective elastic deformation under the contact pressure applied by the flexible wheel 200 and the rigid wheel 300, resulting in a high tooth root stress of the flexible wheel 200, which reduces the service life of the flexible wheel 200. Therefore, by reasonably designing the range of the angle θ between LB and the short axis S2, it is ensured that the strip hole 112 will not be too close to another strip hole 112, so as to ensure the bearing capacity of the cam 110. The strip hole 112 has a suitable length and can generate suitable elastic deformation to reduce the contact pressure on the flexible wheel 200, thereby reducing the tooth root stress on the flexible wheel 200, reducing the risk of plastic deformation or fracture of the flexible wheel 200, and increasing the service life of the flexible wheel 200.

[0060] Reference Figure 1 As shown, in the embodiment of the utility model, the strip holes 112 are completely located in the corresponding areas, that is, the strip holes 112 do not cross the major axis S1 or the minor axis S2. For the convenience of explanation, the four strip holes 112 are respectively referred to as the first strip hole 112, the second strip hole 112, the third strip hole 112 and the fourth strip hole 112. Among them, the first strip hole 112 is completely located in the first area 113, the second strip hole 112 is completely located in the second area 114, the third strip hole 112 is completely located in the third area 115, and the fourth strip hole 112 is completely located in the fourth area 116. The above solution can avoid the problem of excessive reduction in the strength of the cam 110 due to the excessive proximity of adjacent strip holes 112, thereby improving the reliability and stability of the cam 110 during operation.

[0061] Reference Figure 1 As shown, in the embodiment of the present invention, along the radial direction of the cam 110, the two inner wall surfaces of the strip hole 112 opposite to each other are arc surfaces, and the center of the arc surface is located on the rotation axis of the cam 110. Therefore, when machining the strip hole 112, cutting can be performed within a preset radius with the center of the cam 110 as the center of the circle, which is fast and has high production efficiency.

[0062] A harmonic reducer 1000 of an embodiment of the utility model can be applied to industries such as robots and automation. The harmonic reducer 1000 includes the cam 110 of the above embodiment. The harmonic reducer 1000 of the embodiment of the utility model adopts the cam 110 of the above embodiment, and a strip hole 112 is set in any one of the first area 113, the second area 114, the third area 115 and the fourth area 116 of the cam 110. The strip hole 112 extends along the circumference of the cam 110 and is spaced from the outer side wall of the cam 110. When the cam 110 is embedded in the flexible bearing 120, and the flexible wheel 200 is sleeved on the flexible bearing 120 and cooperates with the rigid wheel 300, the contact pressure generated between the flexible wheel 200 and the rigid wheel 300 will act on the cam 110. Since the cam 110 is provided with a strip hole 112, the outer side wall of the cam 110 corresponding to the strip hole 112 can produce a slight elastic deformation under the extrusion of the contact pressure, that is, the strip hole 112 can be deformed to allow the outer tooth portion 220 of the flexible wheel 200 to adjust the meshing angle according to the change of the meshing position, thereby reducing the contact pressure on the flexible wheel 200, and further reducing the tooth root stress on the flexible wheel 200, so as to reduce the risk of plastic deformation or fracture of the flexible wheel 200 and increase the service life of the flexible wheel 200.

[0063] Since the harmonic reducer 1000 adopts all the technical solutions of the cam 110 of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be described in detail here.

[0064] Reference Figure 2 , Figure 3 and Figure 4 As shown, a harmonic reducer 1000 of another embodiment of the utility model includes a wave generator 100, a flexible wheel 200 and a rigid wheel 300. The wave generator 100 includes a cam 110 and a flexible bearing 120. The flexible bearing 120 is sleeved on the outer peripheral wall of the cam 110 and has an interference fit with the cam 110 to reduce the matching clearance between the flexible bearing 120 and the cam 110, improve the transmission accuracy, reduce friction and wear, reduce energy loss, and reduce deformation and vibration. The flexible bearing 120 is mainly made of high-carbon chromium bearing steel, so it can produce elastic deformation. When the cam 110 rotates, it can drive the outer ring 420 of the flexible bearing 120 to produce periodic deformation and withstand cyclic stress loads and alternating stress loads.

[0065] The inner hole of the flexible wheel 200 cooperates with the outer ring 420 of the wave generator 100, and the cam 110 is configured to mesh the outer tooth portion 220 of the flexible wheel 200 with the inner tooth portion 310 of the rigid wheel 300 when rotating. During the operation of the harmonic reducer 1000, the cam 110 rotates under the drive of the motor, driving the flexible bearing 120 and the flexible wheel 200 to deform repeatedly, so that the outer tooth portion 220 of the flexible wheel 200 and the different inner tooth portions 310 of the rigid wheel 300 mesh, thereby driving the flexible wheel 200 and the rigid wheel 300 to rotate relative to each other, realizing the transmission of motion and power.

[0066] When the cam 110 is provided with strip holes 112 in the first area 113, the second area 114, the third area 115 and the fourth area 116, the strip holes 112 extend along the circumference of the cam 110 and are located on a side close to the outer wall of the cam 110. Therefore, the strip holes 112 can cause the outer wall of the cam 110 to undergo elastic deformation, so that the outer tooth portion 220 can adjust the meshing angle in accordance with the change of the meshing position during the meshing process of the inner tooth portion 310, thereby reducing the contact pressure on the flexible wheel 200, and further reducing the tooth root stress on the flexible wheel 200, so as to reduce the risk of plastic deformation or fracture of the flexible wheel 200 and increase the service life of the flexible wheel 200.

[0067] Continue to refer to Figure 2 , Figure 3 and Figure 4 As shown, in the embodiment of the utility model, the harmonic reducer 1000 also includes a bearing, which can be a cross roller bearing 400, a deep groove ball bearing, a tapered roller bearing, etc., and the cross roller bearing 400 is taken as an example. The cross roller bearing 400 includes an inner ring 410, an outer ring 420, and a plurality of rolling elements. The outer ring 420 is sleeved on the inner ring 410, and a raceway 430 for mounting the rolling elements is formed between the inner ring 410 and the outer ring 420, so that the inner ring 410 and the outer ring 420 can rotate relative to each other, and the rolling elements play a role in reducing friction and improving the service life of the cross roller bearing 400. The inner ring 410 of the cross roller bearing 400 is connected to the rigid wheel 300, and the outer ring 420 is connected to the flexible wheel 200, so the cross roller bearing 400 plays a role in transmitting force and bearing load.

[0068] Reference Figure 3As shown, the flexible wheel 200 includes a barrel 210 and a mounting portion 230. The barrel 210 is in a cylindrical shape and has an outer tooth portion 220 on the outer wall of one end. The other end of the barrel 210 is connected to the mounting portion 230. The mounting portion 230 is extended in a direction away from the rotation axis of the cam 110, so the mounting portion 230 is annular. A plurality of first mounting holes 231 are provided on the mounting portion 230, and the plurality of first mounting holes 231 are arranged at intervals along the direction of the rotation axis of the cam 110. Fasteners such as screws are provided through the first mounting holes 231, so that the mounting portion 230 is fixedly connected to the outer ring 420. The scheme of providing a plurality of first mounting holes 231 can improve the stability of the connection between the mounting portion 230 and the outer ring 420. The rigid wheel 300 is provided with a plurality of second mounting holes 320 along its axial end surface, and the plurality of second mounting holes 320 are arranged at intervals along the direction of the rotation axis of the cam 110. By setting fasteners such as screws to pass through the second mounting holes 320, the rigid wheel 300 is fixedly connected to the outer ring 420. The scheme of setting multiple second mounting holes 320 can improve the stability of the connection between the mounting part 230 and the outer ring 420.

[0069] It is understandable that when the flexible wheel 200 rotates, it can drive the outer ring 420 of the cross roller bearing 400 to rotate so as to achieve power output. Therefore, the cross roller bearing 400 also has a positioning function, which can effectively reduce the deviation and dislocation of the flexible wheel 200.

[0070] Reference Figure 5 As shown, in another embodiment of the utility model, a harmonic reducer 1000, the form of the flexible wheel 200 can still include a barrel 210 and a mounting portion 230 connected to one end of the barrel 210, and the mounting portion 230 covers one end of the barrel 210. The appropriate form of the flexible wheel 200 is selected according to actual conditions.

[0071] An industrial robot in an embodiment of the utility model may be a welding robot, a handling robot, a spraying robot, a processing robot, an assembly robot, etc. The industrial robot adopts the harmonic reducer 1000 of the above embodiment, and a strip hole 112 is provided in any one of the first area 113, the second area 114, the third area 115 and the fourth area 116 of the cam 110, and the strip hole 112 extends along the circumference of the cam 110 and is spaced from the outer side wall of the cam 110. When the cam 110 is embedded in the flexible bearing 120, and the flexible wheel 200 is sleeved on the flexible bearing 120 and cooperates with the rigid wheel 300, the contact pressure generated between the flexible wheel 200 and the rigid wheel 300 will act on the cam 110. Since the cam 110 is provided with a strip hole 112, the outer side wall of the cam 110 corresponding to the strip hole 112 can produce a slight elastic deformation under the extrusion of the contact pressure, that is, the strip hole 112 can be deformed to allow the outer tooth portion 220 of the flexible wheel 200 to adjust the meshing angle according to the change of the meshing position, thereby reducing the contact pressure on the flexible wheel 200, and further reducing the tooth root stress on the flexible wheel 200, so as to reduce the risk of plastic deformation or fracture of the flexible wheel 200 and increase the service life of the flexible wheel 200.

[0072] Since the industrial robot adopts all the technical solutions of the harmonic reducer 1000 of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment, which will not be repeated here.

[0073] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A cam, characterized in that: A plane rectangular coordinate system is established with the short axis of the cam as the X-axis, the long axis of the cam as the Y-axis, and the intersection of the X-axis and the Y-axis as the origin, and the portion of the cam in the first quadrant of the plane rectangular coordinate system is defined as the first area, the portion of the cam in the second quadrant of the plane rectangular coordinate system is defined as the second area, the portion of the cam in the third quadrant of the plane rectangular coordinate system is defined as the third area, and the portion of the cam in the fourth quadrant of the plane rectangular coordinate system is defined as the fourth area, at least two of the first area, the second area, the third area and the fourth area are provided with strip holes, the strip holes in adjacent areas are arranged at intervals, and the strip holes extend along the circumference of the cam and are located on the side close to the outer side wall of the cam.

2. The cam according to claim 1, characterized in that: The first area, the second area, the third area and the fourth area are all provided with the strip-shaped holes, and the strip-shaped holes in adjacent areas are arranged at intervals.

3. The cam according to claim 2, characterized in that: The sum of the central angles of the inner walls of all the strip holes along one side of the radial direction of the cam corresponding to the origin is γ, which satisfies 180°≤γ≤320°.

4. The cam according to claim 1, characterized in that: Along the radial direction of the cam, the minimum distance between the side of the strip hole close to the outer side wall of the cam and the outer side wall of the cam is L1, and the maximum distance between the side of the strip hole close to the outer side wall of the cam and the outer side wall of the cam is L2, satisfying: 2mm≤L1≤5mm, 2mm≤L2≤5mm.

5. The cam according to claim 1 or 4, characterized in that: The cam is provided with a center hole. Along the radial direction of the cam, the maximum distance between the inner wall of the center hole and the outer wall of the cam is L3. The minimum width of the strip hole is h, satisfying: 1mm≤h≤(L3-4mm), L3>5mm.

6. The cam according to claim 1, characterized in that: One of the first area, the second area, the third area or the fourth area is provided with a strip hole, and on the projection plane perpendicular to the rotation axis of the cam, the line connecting the end of the strip hole closest to the long axis of the cam and the center of the cam is LA, and the angle between LA and the long axis is α, satisfying: 10°≤α≤30°.

7. The cam according to claim 6, characterized in that: A line connecting the end of the strip hole closest to the short axis and the center of the cam is LB, and an angle between LB and LA is β, which satisfies: 45°≤β≤80°.

8. The cam according to claim 1, characterized in that: A line connecting the end of the strip hole closest to the short axis and the center of the cam is LB, and an angle between LB and the short axis is θ, which satisfies: 10°≤θ≤30°.

9. The cam according to claim 1, characterized in that: The strip-shaped hole is a through hole, and the through hole passes through two axial ends of the cam.

10. Harmonic reducer, characterized in that: Comprising a cam as claimed in any one of claims 1 to 9.

11. Harmonic reducer, characterized in that: include: A rigid wheel having an internal tooth portion; A flexible wheel, provided with an outer tooth portion meshing with the inner tooth portion; a wave generator mounted in the inner hole of the flexspline, the wave generator comprising a flexible bearing and a cam according to any one of claims 1 to 9, the flexible bearing being mounted on the outer side of the cam, the cam being configured to mesh the outer tooth portion with the inner tooth portion when rotating; The strip-shaped hole can cause the outer side wall of the cam to deform elastically, so that the outer tooth portion can adjust the meshing angle in accordance with the change of the meshing position during the meshing process with the inner tooth portion.

12. An industrial robot, characterized in that: Comprising the harmonic reducer as claimed in claim 10 or 11.

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