Needle bearing, speed reducer and industrial robot

Abstract

The invention discloses a needle bearing, a speed reducer and an industrial robot, the needle bearing comprises a retainer and a plurality of rolling bodies, the plurality of rolling bodies are arranged in the retainer and are uniformly arranged around the axis of the needle bearing, the diameter of the inscribed circle of each rolling body is D2, the diameter of the circumscribed circle of each rolling body is D3, and the diameter of the inscribed circle of each rolling body is D2; the reference constant # imgabs0 # # imgabs1 # represents that the calculation result of pi * (D3 + D2) / (D3-D2) is rounded down, and x is smaller than 0.35. The reference constant x is determined according to the excircle diameters and the incircle diameters of the rolling bodies of the needle bearing, and when x is smaller than 0.35, the number of the rolling bodies contained in the needle bearing is optimal, so that the maximum contact stress of the needle bearing is reduced, the abrasion of the needle bearing is reduced, and the service life of the needle bearing is prolonged.

Description

[0001] This application is a divisional application with the application date of "2023.10.27", application number "202311417305.8", and application name "Design method of needle roller bearings, needle roller bearings, reducers and industrial robots". Technical Field

[0002] The present invention relates to the technical field of motors, and in particular to a needle roller bearing, a reducer and an industrial robot. Background Art

[0003] In the related art, the bearings of the crankshaft of the cycloid transmission are mainly needle roller bearings. However, when needle roller bearings are used in cycloid transmissions, the contact stress is large, which leads to increased noise, increased vibration, accelerated wear and finally failure of the needle roller bearings after long-term use. Therefore, the reasonable design of the needle roller bearing structure is the key to prolonging the service life of the cycloid transmission. Summary of the invention

[0004] The embodiments of the present invention provide a needle roller bearing, a reducer and an industrial robot to solve at least one of the above-mentioned technical problems.

[0005] A needle roller bearing according to an embodiment of the present invention comprises a cage and a plurality of rolling elements, wherein the plurality of rolling elements are arranged in the cage and are evenly arranged around the axis of the needle roller bearing, wherein the inscribed circle diameter of the rolling element is D2, the circumscribed circle diameter of the rolling element is D3, and the reference constant in, It means that the calculation result of π×(D3+D2) / (D3-D2) is rounded down to satisfy: x<0.35.

[0006] A needle roller bearing according to an embodiment of the present invention has at least the following beneficial effects: a reference constant x is determined by the circumscribed circle diameter and the inscribed circle diameter of the rolling element of the needle roller bearing; when x < 0.35, the number of rolling elements accommodated by the needle roller bearing is optimal, which is beneficial to reducing the maximum contact stress of the needle roller bearing, thereby reducing the wear of the needle roller bearing and extending the service life of the needle roller bearing.

[0007] According to some embodiments of the present invention, the needle roller bearing includes a retaining frame and a plurality of rolling elements. The retaining frame is provided with pockets for accommodating the rolling elements. The pockets are evenly arranged around the axis of the needle roller bearing. The number of the pockets is equal to the number of the rolling elements. The plurality of rolling elements are installed in corresponding pockets.

[0008] According to some embodiments of the present invention, the distribution circle diameter of the rolling body is equal to half of the sum of the inscribed circle diameter of the rolling body and the circumscribed circle diameter of the rolling body.

[0009] According to some embodiments of the present invention, the difference between the inner diameter of the needle roller bearing and the diameter of the inscribed circle of the rolling body is in the range of [0, 3 mm].

[0010] According to some embodiments of the present invention, the difference between the outer diameter of the needle roller bearing and the diameter of the outer circumscribed circle of the rolling bearing is in the range of [0, 3 mm].

[0011] According to some embodiments of the present invention, along the circumferential direction of the needle roller bearing, the distance between the rolling element and the hole wall of the pocket is in the range of (0, 1 mm].

[0012] According to some embodiments of the present invention, the distance between the rolling element and the hole wall of the pocket is C0, and along the circumferential direction of the needle roller bearing, the minimum distance between every two rolling elements is C1, and the minimum distance between every two pockets is C2, satisfying: C1=2×C0+C2.

[0013] A reducer according to an embodiment of the present invention includes the needle roller bearing according to any one of the above embodiments.

[0014] An industrial robot according to an embodiment of the present invention includes the reducer according to the above embodiment.

[0015] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0017] Figure 1 is a flow chart of a design method for a needle roller bearing according to an embodiment of the present invention;

[0018] Figure 2 is a schematic structural diagram of a needle roller bearing according to an embodiment of the present invention;

[0019] Figure 3 is a schematic cross-sectional structure diagram of a needle roller bearing according to an embodiment of the present invention;

[0020] Figure 4 is a schematic diagram of the relationship between the number of rolling elements and the maximum contact stress of the rolling elements in an embodiment of the present invention;

[0021] Figure 5 and Figure 6 It is a flowchart of the design method of the needle roller bearing according to the embodiment of the present invention.

[0022] Figure Number:

[0023] Needle roller bearing 10 ; cage 12 ; rolling element 14 ; pocket 16 . DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below, examples of which 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.

[0025] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be directly connected or indirectly connected through an intermediate medium. It can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0028] The disclosure herein provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described herein. Of course, they are merely examples, and the purpose is not to limit the present invention. In addition, the present invention may repeat reference numerals and / or reference letters in different examples, and such repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present invention provides various specific examples of processes and materials, but those of ordinary skill in the art may appreciate the application of other processes and / or the use of other materials.

[0029] See also Figures 1 to 3 The embodiment of the present invention provides a design method of a needle roller bearing 10, wherein the needle roller bearing 10 includes a cage 12 and a plurality of rolling elements 14, wherein the plurality of rolling elements 14 are evenly arranged in the cage 12 around the axis of the needle roller bearing 10. The design method includes:

[0030] Step S101: Obtaining a theoretical maximum number and a reference constant of the rolling body 14 according to the diameter of the circumscribed circle of the rolling body 14 and the diameter of the inscribed circle of the rolling body 14;

[0031] Step S103: Determine the actual maximum number of rolling elements 14 according to the reference constant and the theoretical maximum number.

[0032] The design method of the needle roller bearing 10 is to determine the actual maximum number of rolling elements 14 under the diameter according to the circumscribed circle diameter and the inscribed circle diameter of the needle roller bearing 10. Increasing the number of rolling elements 14 is conducive to reducing the maximum contact stress of the needle roller bearing 10, thereby reducing the wear of the needle roller bearing 10 and increasing the life of the needle roller bearing 10.

[0033] Specifically, the needle bearing 10 can be used in a reducer. Optionally, the reducer can be a RV (Rotary Vector) reducer. The RV reducer is a core component of an industrial robot and has the advantages of high precision, high rigidity, and long life. The RV reducer is composed of a planetary gear transmission assembly and a cycloid gear transmission assembly.

[0034] The motion transmission path of the RV reducer starts from the input shaft, and the motion and force are transmitted to the planetary gear through the meshing of the input shaft and the planetary gear. The planetary gear is connected to the crankshaft, and the crankshaft and the planetary gear make the same motion. The cycloid gear has a through hole, and the cycloid gear is sleeved on the flange of the crankshaft through the through hole. The crankshaft will drive the cycloid gear to make eccentric motion and mesh with the pin teeth, and finally transmit the load and motion to the output shaft.

[0035] The needle bearing 10 is arranged between the cycloid gear and the crankshaft, and is an important load-bearing component in the RV reducer. At present, the needle bearing 10 is developed without a ring, and a retaining frame 12 is used to limit the rolling element 14 in the needle bearing 10, so that the size of the needle bearing 10 can be increased. However, after the size of the needle bearing 10 changes, if the number of rolling elements 14 is not designed reasonably, the maximum contact stress of the rolling element 14 during operation will increase, which will cause the needle bearing 10 to have problems such as increased noise, increased vibration, and accelerated wear after long-term use, and finally cause the needle bearing 10 to fail.

[0036] Based on the above problems, an embodiment of the present invention provides a design method for a needle roller bearing 10, which first calculates the theoretical maximum number of rolling elements 14 according to the diameter of the circumscribed circle and the inscribed circle of the rolling element 14 of the needle roller bearing 10, and then determines the actual maximum number of rolling elements 14 according to the calculation result. The number of rolling elements 14 obtained in this way is the maximum number under the size of this needle roller bearing 10.

[0037] like Figure 2 As shown, the needle roller bearing 10 includes a retainer 12 and a plurality of rolling elements 14. The rolling elements 14 are arranged in the retainer 12. The retainer 12 is used to limit the position of the rolling elements 14 along the axial direction of the needle roller bearing 10. The plurality of rolling elements 14 are evenly arranged around the axis of the needle roller bearing 10. The diameter of the distribution circle of the rolling elements 14 is recorded as D1, the diameter of the inscribed circle of the rolling elements 14 is recorded as D2, and the diameter of the circumscribed circle of the rolling elements 14 is recorded as D3. Among them, the circumscribed circle of the rolling elements 14 is a circle where the axis of the needle roller bearing 10 and the surface of the rolling elements 14 are tangent on the side close to the outer diameter of the needle roller bearing 10. The inscribed circle of the rolling elements 14 is a circle where the axis of the needle roller bearing 10 and the surface of the rolling elements 14 are tangent on the side close to the inner diameter of the needle roller bearing 10.

[0038] The theoretical maximum number of rolling elements 14 is recorded as N1max, the actual maximum number of rolling elements 14 is recorded as N2max, and the reference constant is recorded as x.

[0039] Reference constants in, It means that the calculation result of π×(D3+D2) / (D3-D2) is rounded down, and x is the decimal part of the calculation result of π×(D3+D2) / (D3-D2).

[0040] In the needle roller bearing 10, increasing the number of rolling elements 14 is beneficial to reducing the maximum contact stress of the rolling elements 14, thereby reducing the wear of the needle roller bearing 10 and increasing the life of the needle roller bearing 10. Figure 4 FIG. 2 shows the relationship between the number N of rolling elements 14 and the maximum contact stress Qmax.

[0041] See also Figure 5 In some embodiments, step S103 includes:

[0042] Step S1031 : when the reference constant is less than a preset value, determining the theoretical maximum number of the rolling elements 14 as the actual maximum number of the rolling elements 14 .

[0043] In this way, the actual maximum number of rolling elements 14 can be determined directly.

[0044] Specifically, when designing the needle roller bearing 10, first determine the circumscribed circle diameter of the rolling element 14 and the inscribed circle diameter of the rolling element 14, then calculate and obtain the theoretical maximum value and reference constant of the rolling element 14 based on the circumscribed circle diameter and the inscribed circle diameter of the rolling element 14 of the needle roller bearing 10, and determine the actual maximum number of rolling elements 14 based on the size relationship between the reference constant and the preset value.

[0045] The preset value is calculated based on the relationship between the number of rolling elements 14 and the maximum contact stress of the rolling elements 14 when they are working, and the actual maximum number of rolling elements 14 can be determined based on the relationship between the reference constant x and the preset value.

[0046] The preset value is calculated based on the number of rolling elements 14 and the maximum contact stress of the rolling elements 14 when they are working.

[0047] In one embodiment, the preset value is 0.35. When the reference constant x is less than 0.35, determine That is, the theoretical maximum number of rolling elements 14 calculated at this time can be used as the actual maximum number of rolling elements 14 .

[0048] See also Figure 6 In some embodiments, step S103 includes:

[0049] Step S1033: when the reference constant is greater than or equal to the preset value, increase the diameter of the inscribed circle of the rolling element 14 and redetermine the theoretical maximum number of the rolling elements 14 and the reference constant until the reference constant is less than the preset value;

[0050] Step S1035 : when the reference constant is less than the preset value, determining the theoretical maximum number of rolling elements 14 as the actual maximum number of rolling elements 14 , and determining the current inscribed circle diameter of the rolling element 14 as the actual inscribed circle diameter of the rolling element 14 of the needle roller bearing 10 .

[0051] In this way, according to the calculated theoretical maximum number of rolling elements 14 and the reference constant, the diameter of the inscribed circle of the rolling element 14 is adjusted, so as to obtain the actual maximum number of the rolling elements 14 .

[0052] Specifically, if the reference constant calculated based on the current circumscribed circle diameter of the rolling body 14 and the inscribed circle diameter of the rolling body 14 is greater than the preset value, the inscribed circle diameter of the rolling body 14 can be increased, and the theoretical maximum number of rolling bodies 14 and the reference constant can be recalculated until the reference constant is less than the preset value, and the corresponding theoretical maximum number of rolling bodies 14 is determined to be the actual maximum number of rolling bodies 14, and at the same time, the corresponding inscribed circle diameter of the rolling body 14 is determined to be the actual inscribed circle diameter of the rolling body 14 of the needle roller bearing 10.

[0053] In one embodiment, the preset value is 0.35, when x≥0.35,

[0054]

[0055] Among them, Δ=0.1×n, (n∈Z+), n takes the values ​​of 1, 2, 3, 4, 5, etc.

[0056] Until the reference constant x is less than 0.35, it is determined that the theoretical maximum number N1max of the rolling elements 14 at this time is equal to the actual maximum number N2max of the rolling elements 14, and the diameter of the inscribed circle of the rolling element 14 is D2+Δ.

[0057] In other implementations, the preset value can be determined according to actual needs.

[0058] In summary, the theoretical maximum number of rolling elements 14 is calculated based on the diameter of the inscribed circle of the rolling element 14 and the circumscribed circle of the rolling element 14 of the needle roller bearing 10, and the actual maximum number of rolling elements 14 is determined based on the calculation result. The number of rolling elements 14 obtained in this way is the maximum number under the size of the needle roller bearing 10, so that the needle roller bearing 10 can obtain the most rolling elements 14, reduce the maximum contact stress of the rolling element 14, and optimize the life of the needle roller bearing 10.

[0059] A needle roller bearing 10 according to an embodiment of the present invention is designed and processed by the design method of the needle roller bearing 10 according to any of the above embodiments.

[0060] Specifically, according to the above-mentioned design method of needle roller bearings 10, the actual maximum number of needle roller bearings 10 can be determined, and the diameters of the circumscribed circle and the inscribed circle of the rolling element 14 of the needle roller bearing 10 can be determined at the same time, thereby determining the size parameters of the needle roller bearing 10, and processing can be performed to obtain needle roller bearings 10 of corresponding sizes.

[0061] In some embodiments, the needle roller bearing 10 includes a retaining frame 12 and a plurality of rolling elements 14 . The retaining frame 12 is provided with pockets 16 for accommodating the rolling elements 14 . The pockets 16 are evenly arranged around the axis of the needle roller bearing 10 . The number of the pockets 16 corresponds to the number of the rolling elements 14 . The plurality of rolling elements 14 are installed in the pockets 16 .

[0062] In this way, the retainer 12 can limit the position of the rolling element 14 and prevent the rolling element 14 from falling out.

[0063] Specifically, Figure 2 As shown, the needle roller bearing 10 includes a cage 12 and a plurality of rolling elements 14. The cage 12 is provided with pockets 16. The pockets 16 are evenly arranged around the axis of the needle roller bearing 10. The plurality of rolling elements 14 are installed in the pockets 16. The number of pockets 16 and rolling elements 14 corresponds to each other and can be determined according to the design method of the needle roller bearing 10 described above.

[0064] The retainer 12 can limit the position of the rolling element 14 in the axial direction of the needle roller bearing 10, so that the inner and outer rings of the needle roller bearing 10 can be eliminated, the size of the needle roller bearing 10 can be increased, the structure of the needle roller bearing 10 can be simpler, and the processing difficulty can be reduced.

[0065] In one embodiment, the rolling body 14 is cylindrical. In other embodiments, the rolling body 14 may be spherical or conical. The shape of the pocket 16 corresponds to the shape of the rolling body 14.

[0066] Optionally, the material of the cage 12 can be resin, nylon or steel. The cage 12 made of resin or nylon has good sliding and self-lubricating properties, and can make the overall weight of the needle roller bearing 10 light. The steel cage 12 has the advantages of high strength, good toughness, and easy processing. When applying, it can be selected according to the use scenario and actual needs of the needle roller bearing 10.

[0067] In some embodiments, the diameter of the distribution circle of the rolling body 14 is equal to half of the sum of the inscribed circle of the rolling body 14 and the circumscribed circle of the rolling body 14 .

[0068] In this way, it can be ensured that the rolling body 14 is subjected to uniform force on each surface when rolling, thereby reducing the wear on the rolling surface of the rolling body 14 when subjected to force.

[0069] Specifically, Figure 2 As shown, the center of the rolling body 14 is located on the distribution circle of the rolling body 14, and the diameter of the distribution circle of the rolling body 14 is D1. The diameter D1 of the distribution circle of the rolling body 14 is equal to half of the sum of the diameter D2 of the inscribed circle of the rolling body 14 and the diameter D3 of the circumscribed circle of the rolling body 14, that is, D1 = 1 / 2 (D2 + D3). In this way, it can be ensured that the rolling body 14 is subjected to uniform force on all surfaces when rolling, and the wear on the rolling surface of the rolling body 14 when subjected to force is reduced. In the actual production and processing process, a certain error can be allowed. The specific error range needs to be set according to the application scenario of the needle roller bearing 10, and is not specifically limited here.

[0070] In some embodiments, the difference between the outer diameter of the needle roller bearing 10 and the circumscribed circle diameter of the rolling element 14 is in the range of [0, 3 mm].

[0071] In this way, the rolling element 14 can be prevented from falling out of the cage 12 , while ensuring that the needle roller bearing 10 has a high rotation accuracy.

[0072] Specifically, Figure 2 As shown, the difference between the outer diameter D4 of the needle roller bearing 10 and the circumscribed circle diameter D3 of the rolling element 14 is in the range of [0, 3mm]. For example, the difference between the outer diameter D4 of the needle roller bearing 10 and the circumscribed circle diameter D3 of the rolling element 14 can be 0, 0.5mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.3mm, 2.7mm or 3mm. If the difference between the outer diameter D4 of the needle roller bearing 10 and the circumscribed circle diameter D3 of the rolling element 14 is greater than 3mm, the limiting function of the rolling element 14 in the axial direction of the needle roller bearing 10 may fail, and even the rolling element 14 may be separated from the retaining frame 12 during operation. Limiting the difference between the outer diameter D4 of the needle roller bearing 10 and the circumscribed circle diameter D3 of the rolling element 14 to the range of [0, 3mm] can prevent the rotation of the needle roller bearing 10 from being affected after the rolling element 14 is installed in the retaining frame 12.

[0073] In some embodiments, the difference between the inner diameter of the needle roller bearing 10 and the inscribed circle diameter of the rolling element 14 is in the range of [0, 3 mm].

[0074] In this way, the rolling element 14 can be prevented from falling out of the cage 12 , while ensuring that the needle roller bearing 10 has a high rotation accuracy.

[0075] Specifically, Figure 2 As shown, the difference between the inner diameter D5 of the needle roller bearing 10 and the inscribed circle diameter D2 of the rolling element 14 is in the range of [0, 3mm]. For example, the difference between the inner diameter D5 of the needle roller bearing 10 and the inscribed circle diameter D2 of the rolling element 14 can be 0, 0.5mm, 1mm, 1.2mm, 1.5mm, 1.8mm, 2mm, 2.3mm, 2.7mm or 3mm. If the difference between the inner diameter D5 of the needle roller bearing 10 and the inscribed circle diameter D2 of the rolling element 14 is greater than 3mm, the limit function of the rolling element 14 in the axial direction of the needle roller bearing 10 may fail, and even the rolling element 14 may be separated from the retaining frame 12 during operation. Limiting the difference between the inner diameter D5 of the needle roller bearing 10 and the inscribed circle diameter D2 of the rolling element 14 to a range of [0, 3mm] can prevent the rotation of the needle roller bearing 10 from being affected after the rolling element 14 is installed in the retaining frame 12.

[0076] In some embodiments, along the circumferential direction of the needle roller bearing 10 , the distance between the rolling element 14 and the wall of the pocket 16 is in the range of (0, 1 mm).

[0077] In this way, the rolling of the rolling body 14 in the pocket 16 is not affected, and at the same time, it is prevented that the gap between the rolling body 14 and the wall of the pocket 16 is too large, so that the rolling body 14 shakes in the pocket 16.

[0078] Specifically, Figure 3 As shown, along the circumferential direction of the needle roller bearing 10, the distance between the rolling element 14 and the hole wall of the pocket 16 is C0, and the value range of C0 is (0, 1mm]. For example, along the circumferential direction of the needle roller bearing 10, the distance C0 between the rolling element 14 and the hole wall of the pocket 16 can be 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm or 1mm. If the distance between the rolling element 14 and the hole wall of the pocket 16 is zero, the friction between the rolling element 14 and the hole wall of the pocket 16 is large when rolling, which will cause the needle roller bearing 10 to wear during operation. The damage is serious and it is not convenient for processing and assembly. If the distance between the rolling element 14 and the hole wall of the pocket 16 is greater than 1mm, the rolling element 14 will shake in the pocket 16 during operation, thereby affecting the rotation of the needle roller bearing 10. In some working conditions, for example, when the needle roller bearing 10 rotates at a high speed, the distance between the rolling element 14 and the hole wall of the pocket 16 is too large and noise will be generated. Therefore, the distance between the rolling element 14 and the hole wall of the pocket 16 is within (0, 1mm], which does not affect the rolling of the rolling element 14 in the pocket 16, and at the same time avoids the gap between the rolling element 14 and the hole wall of the pocket 16 being too large, so that the rolling element 14 shakes in the pocket 16.

[0079] In some embodiments, the distance between the rolling element 14 and the hole wall of the pocket 16 is C0, along the circumferential direction of the needle roller bearing 10, the minimum distance between two adjacent rolling elements 14 is C1, and the minimum distance between the hole walls of two adjacent pockets 16 is C2, 2×C0+C2=C1.

[0080] In this way, it can be ensured that the hole wall of the pocket 16 has a certain structural strength, and at the same time the structure of the pocket 16 and the rolling body 14 is compact.

[0081] Specifically, Figure 3 As shown, along the circumferential direction of the needle roller bearing 10, the minimum distance between two adjacent rolling elements 14 is C1, the minimum distance between the walls of two adjacent pockets 16 is C2, and the distance between the rolling element 14 and the wall of the pocket 16 is C0, that is, 2×C0+C2=C1. In this way, the wall of the pocket 16 can be guaranteed to have a certain structural strength, and the structure of the pocket 16 and the rolling element 14 is compact.

[0082] It should be noted that the above dimensional requirements may have a certain degree of error during the actual processing. The specific error requirements can be set according to the specific purpose and processing equipment of the needle roller bearing 10, and are not specifically limited here.

[0083] A speed reducer according to an embodiment of the present invention includes the needle roller bearing 10 according to any one of the above embodiments.

[0084] An industrial robot according to an embodiment of the present invention includes the reducer according to the above embodiment.

[0085] In the above-mentioned speed reducer and industrial robot, the actual maximum number of rolling elements 14 under the diameter is determined according to the circumscribed circle diameter and the inscribed circle diameter of the needle roller bearing 10. Increasing the number of rolling elements 14 is conducive to reducing the maximum contact stress of the needle roller bearing 10, thereby reducing the wear of the needle roller bearing 10 and increasing the life of the needle roller bearing 10.

[0086] It should be noted that the above explanations of the implementation and beneficial effects of the needle roller bearing 10 are also applicable to the reducer and industrial robot used in the implementation of the present invention, and will not be elaborated here in detail to avoid redundancy.

[0087] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0088] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A needle roller bearing, comprising a cage and a plurality of rolling elements, wherein the plurality of rolling elements are arranged in the cage and are evenly arranged around the axis of the needle roller bearing, characterized in that: The diameter of the inscribed circle of the rolling body is D2, the diameter of the circumscribed circle of the rolling body is D3, and the reference constant is in, It means that the calculation result of π×(D3+D2) / (D3-D2) is rounded down to satisfy: x<0.

35.

2. The needle roller bearing according to claim 1, characterized in that: The needle roller bearing includes a retaining frame and a plurality of rolling elements. The retaining frame is provided with pockets for accommodating the rolling elements. The pockets are evenly arranged around the axis of the needle roller bearing. The number of the pockets is equal to the number of the rolling elements. The plurality of rolling elements are installed in corresponding pockets.

3. The needle roller bearing according to claim 1 or 2, characterized in that: The distribution circle diameter of the rolling body is equal to half of the sum of the inscribed circle diameter of the rolling body and the circumscribed circle diameter of the rolling body.

4. The needle roller bearing according to claim 1 or 2, characterized in that: The difference between the inner diameter of the needle roller bearing and the diameter of the inscribed circle of the rolling body is in the range of [0, 3 mm].

5. The needle roller bearing according to claim 1 or 2, characterized in that: The difference between the outer diameter of the needle roller bearing and the diameter of the outer inscribed circle of the rolling bearing is in the range of [0, 3 mm].

6. The needle roller bearing according to claim 1 or 2, characterized in that: Along the circumferential direction of the needle roller bearing, the distance between the rolling element and the hole wall of the pocket hole ranges from (0 to 1 mm).

7. The needle roller bearing according to claim 1 or 2, characterized in that: The distance between the rolling element and the wall of the pocket is C0. Along the circumferential direction of the needle roller bearing, the minimum distance between every two rolling elements is C1, and the minimum distance between every two pockets is C2, satisfying: C1=2×C0+C2.

8. A reducer, characterized in that: The invention comprises the needle roller bearing according to any one of claims 1 to 7.

9. An industrial robot, characterized in that: Including the reducer as described in claim 8.

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