Cross ball bearing and harmonic reducer

Abstract

The invention discloses a cross ball bearing and a harmonic reducer, the cross ball bearing belongs to the technical field of harmonic reducers and accessories, the cross ball bearing comprises an outer ring and an inner ring, the outer ring is rotatably connected with the inner ring, V-shaped grooves are formed in the outer ring and the inner ring, a plurality of rollers are arranged between the two V-shaped grooves, a spiral air hole is integrally formed in the outer ring, and the spiral air hole is communicated with the inner ring. The spiral air hole is provided with a threaded oil groove, and the lubricating grease can move in the oil groove. According to the crossed ball bearing provided by the invention, lubricating grease in the V-shaped groove can be pressed out along the oil groove of the spiral air hole and can be released along with the pressure in the crossed ball bearing, and the oil groove is in a threaded shape and has a long stroke distance, so that when the lubricating grease reaches a certain position of the spiral air hole, the lubricating grease is prevented from leaking. The internal air pressure and the external air pressure of the crossed ball bearing tend to be balanced, so that lubricating grease is effectively intercepted, and the phenomenon of overflowing of the lubricating grease is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of harmonic reducers and accessories, and in particular, relates to a cross ball bearing and a harmonic reducer. Background Art

[0002] The harmonic reducer is the core component of the joint drive of the industrial robot. It can realize the high-precision, fast and smooth movement of the robot. When the robot's mechanical arm performs reciprocating arm flexion motion, a cross ball bearing is needed to provide radial load, thereby supporting the reciprocating arm flexion motion.

[0003] During the operation of the harmonic reducer, a large amount of heat is generated in the internal parts, and the pressure will also increase. As the pressure increases, the grease is easy to leak from the gap under the pressure difference. The existing cross ball bearing design will be equipped with an oil groove to receive the leaked grease. However, this design has the following problems:

[0004] ① Although an oil groove is provided in the gap between the outer ring and the inner ring, the depth of the oil groove is limited due to the overall size of the cross ball bearing, and the movable stroke of the grease is short, which easily leads to grease overflow.

[0005] ② Although the oil groove can intercept the leaked grease, it does not have the ability to push the grease back. During the reciprocating arm flexion of the robot's mechanical arm, only part of the grease close to the gap can return to the V-groove between the outer ring and the inner ring with the reciprocating arm flexion movement, and the remaining grease is difficult to return to the V-groove. This causes part of the grease to lose its function, resulting in a waste of grease and affecting the use of the harmonic reducer. Summary of the invention

[0006] In view of the deficiencies in the prior art, an object of the present invention is to provide a cross ball bearing and a harmonic reducer.

[0007] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0008] An outer ring and an inner ring, the outer ring is rotatably connected to the inner ring, a V-shaped groove is provided in each of the outer ring and the inner ring, a plurality of rollers are provided between the two V-shaped grooves, a spiral air vent is integrally formed in the axial side of the outer ring and communicated with the V-shaped groove, the spiral air vent has a threaded oil groove, and when the outer ring and the inner ring rotate relative to each other, the grease can move inside the oil groove.

[0009] It should be noted that one end of the threaded oil groove is close to the edge of the V-groove. When grease is squeezed out under pressure, it will cover the port of the oil groove. As the grease continues to be squeezed out, it will move upward along the thread shape of the oil groove, extending the movement of the grease with the thread shape of the oil groove. This can effectively prevent the grease from overflowing when the cross ball bearing releases internal pressure.

[0010] Preferably, a groove is provided in the V-shaped groove, the groove is arranged in the middle of the V-shaped groove, and the positions of the two grooves correspond to each other.

[0011] Preferably, a TC oil seal is sleeved on one side of the spiral vent hole, and the TC oil seal can cooperate with the spiral vent hole to form a seal.

[0012] Preferably, the cross-sectional shape of the oil groove is an arc, the diameter of the arc is at least 0.35 mm, and the depth of the arc is at least 0.1 mm.

[0013] Preferably, a plurality of connection holes are provided in the outer ring and the inner ring, and the plurality of connection holes are arranged at equal distances.

[0014] During the reciprocating motion of the industrial robot joints, the harmonic reducer will be subjected to axial force, and the axial force mainly acts in one direction, that is, the direction of the spiral vent hole. Therefore, oil leakage is more likely to occur in this direction, and rarely flows out from the gap on the outer ring away from the spiral vent hole.

[0015] See also Figure 5 The position of H at the outer edge of the outer ring is regarded as the highest point of the oil groove, while the position of L close to the inside of the outer ring 1 is regarded as the lowest point of the oil groove.

[0016] A harmonic reducer comprises a rigid wheel, a flexwheel and a wave generator, wherein the rigid wheel is meshedly connected to the flexwheel, the wave generator is tightly connected to the flexwheel, and the cross ball bearing is fixedly connected to the flexwheel.

[0017] Compared with the prior art, the advantages of the present invention include:

[0018] (1) The present invention provides a cross ball bearing and a harmonic reducer. By setting a spiral vent hole, when the air pressure inside the cross ball bearing reaches a certain pressure, the grease inside the V-groove will be pressed out along the oil groove of the spiral vent hole, and will be released along with the pressure inside the cross ball bearing. Since the specific shape of the oil groove is a thread shape and its travel distance is long, when the grease reaches a certain position of the spiral vent hole, the air pressure inside the cross ball bearing and the external air pressure will tend to be balanced, thereby effectively intercepting the grease and avoiding the occurrence of grease overflow;

[0019] (2) The present invention provides a cross ball bearing and a harmonic reducer. After the internal air pressure of the cross ball bearing tends to be balanced with the external air pressure, as the joints of the industrial robot reciprocate, the grease will slowly slide from the highest point of the oil groove of the spiral vent hole to the lowest point due to its own weight, until most of the grease is squeezed into the V-groove again, thereby avoiding the situation where part of the grease is difficult to return to its original position and loses its function, reducing the waste of grease, and at the same time, effectively lubricating the inside of the cross ball bearing to avoid affecting the use of the harmonic reducer;

[0020] (3) The present invention provides a cross ball bearing and harmonic reducer, which can increase the surface area of ​​the lubricating oil film by opening a groove in the middle of the V-groove, thereby improving the stability and stretchability of the lubricating oil film, and increasing the contact area of ​​the cross ball bearing, thereby enhancing the load-bearing capacity of the cross ball bearing. Under high-load operation, the cross ball bearing may produce deformation or plastic deformation, and the design of the groove helps to reduce such deformation, so that the cross ball bearing can better withstand heavy loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a front structural schematic diagram of a cross ball bearing in the present invention;

[0023] Figure 2 It is a schematic diagram of the back structure of a cross ball bearing in the present invention;

[0024] Figure 3 It is a structural cross-sectional view of the inner ring in the present invention;

[0025] Figure 4 It is a structural cross-sectional view between the outer ring and the inner ring in the present invention;

[0026] Figure 5 for Figure 3 A magnified view of the structure at center A;

[0027] Figure 6 for Figure 4 A magnified view of the structure at point B.

[0028] Reference numerals:

[0029] 1. Outer ring; 2. Inner ring; 3. Spiral vent hole; 4. V-shaped groove; 5. Groove; 6. TC oil seal; 7. Connection hole. DETAILED DESCRIPTION

[0030] In view of the deficiencies in the prior art, the inventor of this case has proposed the technical solution of the present invention after long-term research and extensive practice. The following will further explain the technical solution, its implementation process and principle, etc. in conjunction with the drawings in the embodiments of this application and specific implementation cases.

[0031] It should be noted that 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. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, the present invention covers any substitution, modification, equivalent method and scheme made on the spirit, principle and scope of the present invention defined by the claims. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the present application, "first", "second", "third" and similar words do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, "one" or "an" and other similar words do not indicate a quantity limitation, but indicate the existence of at least one. "Include" or "comprise" and other similar words mean that the elements or objects appearing before "include" or "comprises" include the elements or objects listed after "include" or "comprises" and their equivalents, and do not exclude other elements or objects. "Connect" or "connected" and other similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0033] In the description of the present application, the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application 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 a limitation on the present application. In addition, when positional terms such as both sides, outside, up and down are used, it should be understood that they are only used to facilitate understanding and description, considering that the structure may be facing other positions.

[0034] In the description of this application, unless otherwise clearly specified and limited, the technical or scientific terms used should have the usual meanings understood by persons with general skills in the field to which this application belongs. Terms such as "install", "connect", and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection, or an integrated connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] The embodiments of the present invention are intended to introduce and illustrate the structural composition of the cross ball bearing and harmonic reducer and the matching relationship between the various components. Unless otherwise specified, the dimensions, materials and manufacturing processes of the various components in the cross ball bearing in the embodiments of the present invention can be selected according to the specific circumstances and are not specifically limited or explained herein.

[0036] Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the following detailed description of the present invention. For those skilled in the art, the present invention can be fully understood without the description of these details.

[0037] Example 1

[0038] See also Figure 1 and Figure 2 A cross ball bearing comprises an outer ring 1 and an inner ring 2, the outer ring 1 is rotatably connected to the inner ring 2, a V-shaped groove 4 is provided in each of the outer ring 1 and the inner ring 2, a plurality of rollers are provided between the two V-shaped grooves 4, a spiral air vent 3 is integrally formed in the outer ring 1, and the spiral air vent 3 has a threaded oil groove so that grease can move inside the oil groove.

[0039] It should be noted that one end of the threaded oil groove is close to the edge of the V-groove 4. When grease is squeezed out under pressure, it will cover the port of the oil groove. As the grease continues to be squeezed out, it will move upward along the thread shape of the oil groove, thereby extending the movement of the grease with the thread shape of the oil groove. This can effectively prevent the grease from overflowing when the cross ball bearing releases internal pressure.

[0040] See also Figure 5 , the position of H at the outer edge of the outer ring 1 is regarded as the highest point of the oil groove, and the position of L close to the inside of the outer ring 1 is regarded as the lowest point of the oil groove;

[0041] It can be understood that after the internal pressure of the cross ball bearing is released and tends to be balanced compared with the external atmospheric pressure, the purpose of reducing the internal temperature and air pressure of the cross ball bearing will be achieved, and as the joints of the industrial robot reciprocate, the grease will slowly slide from the highest point of the oil groove of the spiral air vent 3 to the lowest point due to its own weight, until most of the grease is squeezed into the V-groove 4 again, thereby avoiding the situation where part of the grease is difficult to return to its original position and loses its effect, reducing the waste of grease, and at the same time enabling the cross ball bearing to be effectively lubricated to avoid affecting the use of the harmonic reducer.

[0042] See also Figure 4 A groove 5 is provided in the V-shaped groove 4, and the groove 5 is arranged in the middle of the V-shaped groove 4. The positions of the two grooves 5 correspond to each other. By providing the groove 5 in the middle of the V-shaped groove 4, the following functions and effects are mainly achieved:

[0043] Increase the stability of the lubricating oil film: It can increase the surface area of ​​the lubricating oil film, thereby improving the stability and stretchability of the lubricating oil film;

[0044] Enhanced load-bearing capacity: The contact area of ​​the cross ball bearing is increased, thereby enhancing the load-bearing capacity of the cross ball bearing. Under high-load operation, the cross ball bearing may deform or plastically deform, and the design of the groove 5 helps to reduce such deformation, so that the cross ball bearing can better withstand heavy loads;

[0045] Distribute the load: Groove 5 helps to distribute the load on the cross ball bearing, making the load distribution more even. This not only improves the load-bearing capacity of the cross ball bearing, but also extends its service life;

[0046] Grease storage: The groove 5 can store a certain amount of lubricating grease, thereby continuously providing lubrication during the operation of the cross ball bearing, which helps to reduce friction and wear caused by insufficient lubrication.

[0047] A TC oil seal 6 is sleeved on one side of the spiral air vent 3, and the TC oil seal 6 can cooperate with the spiral air vent 3 to form a seal. Normally, the TC oil seal 6 is installed on the rotating shaft part of the cross ball bearing and fits with the spiral air vent 3 to form a seal, thereby preventing the grease from overflowing.

[0048] It is understandable that the operating environment temperature requirement for harmonic reducers is -40~+55℃. Under the moisturizing condition of +55℃, the harmonic reducer operates normally at rated speed and rated load for about 2 hours, and its thermal equilibrium temperature does not exceed 100℃, and its temperature rise is 45℃. In the thermal vacuum transmission performance test of the harmonic reducer, the environmental conditions are selected from the high orbit space environmental conditions, and the vacuum degree is required to be ≤1.3×10^-3^Pa. That is to say, the temperature range generated by the conventional harmonic reducer bearings during operation is roughly between -40℃ and 100℃, and the air pressure range is under high vacuum conditions, and the vacuum degree does not exceed 1.3×10^-3^Pa. Taking the cross ball bearing size of the harmonic reducer used in conventional industrial robots as an example, at the rated speed and rated load, the internal temperature of the cross ball bearing can reach 80℃ after operating normally for about 2 hours, and the air pressure value at this time is in the range of 0.4~0.6MPa, and the grease will be pressed to Figure 4 When the air pressure inside the cross ball bearing moves in the P direction and tends to be balanced with the external air pressure, the air pressure value is close to 101.325 kPa, at which time the grease stops being squeezed out.

[0049] See also Figure 3 , Figure 4 and Figure 6 The cross-sectional shape of the oil groove is an arc, the diameter of the arc is at least 0.35 mm, and the depth of the arc is at least 0.1 mm. The arc-shaped design of the oil groove allows the oil groove to accommodate more grease and allows the grease to move along the threaded moving path of the oil groove, thereby preventing the grease from having enough space to move when the pressure inside the cross ball bearing is released, and preventing the overflow caused by insufficient grease moving path;

[0050] It should be noted that the size of the arc-shaped portion of the oil groove is affected by the actual size of the cross ball bearing and needs to be adjusted accordingly based on the size of the cross ball bearing used.

[0051] See also Figure 1 , Figure 2 and Figure 3 A plurality of connection holes 7 are provided in both the outer ring 1 and the inner ring 2, and the plurality of connection holes 7 are arranged at equal distances. The arrangement of the connection holes 7 reduces the material used in the production of the cross ball bearing and reduces the counterweight, which can reduce the overall weight of the cross ball bearing and facilitate the use of the cross ball bearing.

[0052] It should be noted that the main feature of the crossed ball bearing is that the rollers inside it are arranged in a cross manner. This arrangement allows the bearing to bear loads in two vertical directions at the same time, namely radial loads and axial loads, thereby supporting the robot's mechanical arm to perform reciprocating arm flexion movements.

[0053] The two V-shaped grooves 4 located inside the outer ring 1 and the inner ring 2 are combined to form a diamond-shaped groove body, and the shape of the roller will be adapted thereto to meet the radial load and axial load bearing capacity.

[0054] A harmonic reducer comprises a rigid wheel, a flexwheel and a wave generator, wherein the rigid wheel is meshedly connected to the flexwheel, the wave generator is tightly connected to the flexwheel, and the cross ball bearing is fixedly connected to the flexwheel.

[0055] When this technical solution is implemented as a whole, the following operations will be performed:

[0056] When the robot's mechanical arm performs reciprocating arm flexion movements, the movement of the mechanical arm joint area will be completed through the cross ball bearing of the harmonic reducer. When the air pressure inside the cross ball bearing reaches a certain pressure, the grease inside the V-groove 4 will be pressed out along the oil groove of the spiral air vent 3, and will be released along with the pressure inside the cross ball bearing. Since the specific shape of the oil groove is a threaded shape and its travel distance is long, when the grease reaches a certain position of the spiral air vent 3, the air pressure inside the cross ball bearing and the external air pressure will tend to be balanced. It should be noted that in the reciprocating motion of the industrial robot joint, the harmonic reducer The speed reducer will be affected by axial force, and the axial force mainly acts in one direction, that is, the direction of the spiral air hole 3. Therefore, oil leakage is more likely to occur in this direction, and it is rare for oil to flow out from the gap on the side of the outer ring 1 away from the spiral air hole 3. Therefore, the grease can be effectively intercepted through the spiral air hole 3. After the internal air pressure of the cross ball bearing tends to be balanced with the external air pressure, as the joints of the industrial robot reciprocate, the grease will slowly slide from the highest point of the oil groove of the spiral air hole 3 to the lowest point due to its own weight, until most of the grease is squeezed into the V-groove 4 again.

[0057] It should be understood that the above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. It cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, some simple deductions or substitutions can be made without departing from the concept of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A cross ball bearing, comprising an outer ring (1) and an inner ring (2), wherein the outer ring (1) and the inner ring (2) are rotatably connected, wherein both the outer ring (1) and the inner ring (2) are provided with a V-shaped groove (4), and a plurality of rollers are provided between two of the V-shaped grooves (4), wherein: The outer ring (1) is integrally formed with a spiral air vent (3) in communication with the V-shaped groove (4) in the axial side thereof. The spiral air vent (3) has a threaded oil groove so that the grease can move inside the oil groove when the outer ring (1) and the inner ring (2) rotate relative to each other.

2. A cross ball bearing according to claim 1, characterized in that: A groove (5) is provided at the bottom of the V-shaped groove (4), and the groove (5) is arranged in the middle of the V-shaped groove (4), and the positions of the two grooves (5) correspond to each other.

3. A cross ball bearing according to claim 1, characterized in that: A TC oil seal (6) is sleeved on one side of the spiral air vent (3), and the TC oil seal (6) can cooperate with the spiral air vent (3) to form a seal.

4. A cross ball bearing according to claim 1, characterized in that: The cross-sectional shape of the oil groove is an arc, the diameter of the arc is at least 0.35 mm, and the depth of the arc is at least 0.1 mm.

5. The cross ball bearing according to claim 1, characterized in that: A plurality of connection holes (7) are provided in both the outer ring (1) and the inner ring (2), and the plurality of connection holes (7) are arranged at equal distances.

6. A harmonic reducer, comprising the cross ball bearing according to any one of claims 1 to 5, characterized in that: The invention comprises a rigid wheel, a flexible wheel and a wave generator. The rigid wheel is meshedly connected with the flexible wheel, the wave generator is tightly connected with the flexible wheel, and the cross ball bearing is fixedly connected with the flexible wheel.

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