Bearing and sealing device

Abstract

The embodiment of the present application provides a bearing and a sealing device, the sealing device comprises a framework, a sealing part, the sealing part is annular in whole, the sealing part comprises an elastic part and a plastic part, the elastic part is fixed to the framework, the plastic part forms contact sealing with a bearing inner ring after the sealing device is arranged between the bearing inner ring and a bearing outer ring, the elastic part and the plastic part are relatively fixed, at least part of the plastic part is arranged between the bearing inner ring and the elastic part in a radial direction, and the friction coefficient of the material of the plastic part is smaller than the friction coefficient of the material of the elastic part. The sealing device provided by the embodiment of the present application can improve the sealing effect of the sealing device and prolong the service life of the sealing device.

Description

Technical Field

[0001] This invention relates to the field of bearing sealing technology, and more particularly to a bearing and a sealing device. Background Technology

[0002] Articulated robots, also known as articulated arm robots or articulated robotic arms, are one of the most common forms of industrial robots in today's industrial fields, suitable for automated mechanical operations in many industries. The bearings of the articulated arm play a decisive role in the robot's load-bearing capacity, dynamic performance, and precision.

[0003] Articulated arm bearings consist of an inner ring, an outer ring, and a seal ring located between the inner and outer rings. The seal ring is used to prevent grease leakage. Because the articulated arm of a robot repeatedly performs grasping and retracting rocker arm movements, the rotation direction of the bearing needs to be frequently switched, which can easily lead to the risk of lubricating grease leakage.

[0004] Therefore, the sealing performance of articulated arm bearings needs to be improved. Summary of the Invention

[0005] The technical problem solved by the embodiments of the present invention is to improve the sealing performance of bearings.

[0006] To address the above problems, embodiments of the present invention provide a bearing suitable for placement between the inner ring and outer ring of the bearing, wherein the sealing device includes:

[0007] skeleton;

[0008] The sealing part has an overall annular structure and includes an elastic part and a plastic part. The elastic part is fixed to the skeleton. When the sealing device is placed between the inner ring and the outer ring of the bearing, the plastic part forms a contact seal with the inner ring of the bearing. The elastic part and the plastic part are relatively fixed, and at least part of the plastic part is disposed between the inner ring of the bearing and the elastic part in the radial direction. The coefficient of friction of the material of the plastic part is less than the coefficient of friction of the material of the elastic part.

[0009] Optionally, the plastic part is an overall ring structure, including a fixed outer ring end and a free inner ring end that are fixedly connected. The fixed outer ring end is fixed to the axial outer end face of the skeleton. When the sealing device is placed between the inner ring and the outer ring of the bearing, the free inner ring end can be bent along the axial direction of the sealing device and is disposed in the radial direction between the inner ring of the bearing and the elastic part. The elastic part is fixed relative to the free inner ring end.

[0010] Optionally, the free end of the inner ring is provided with an annular groove, and when the free end of the inner ring is located between the inner ring and the outer ring of the bearing, the opening of the annular groove faces the inner ring of the bearing.

[0011] Optionally, the sealing device further includes:

[0012] A stop ring is fixed to the skeleton, and the stop ring and the skeleton are respectively disposed at both ends of the plastic part along the axial direction.

[0013] Optionally, the plastic part further includes a thrust surface, which is located at the axial inner end of the plastic part when the plastic part forms a contact seal with the inner ring of the bearing.

[0014] Optionally, the thrust surfaces are evenly distributed circumferentially along the plastic portion, and the slope direction of adjacent thrust surfaces is symmetrical about the boundary line of adjacent thrust surfaces.

[0015] Optionally, the material of the plastic part is polytetrafluoroethylene.

[0016] Optionally, the plastic portion further includes:

[0017] The dustproof lip is fixed to the axial outer end face of the annular fixed end. When the free end of the inner ring is located between the inner ring and the outer ring of the bearing, the dustproof lip extends axially away from the free end of the inner ring and radially closer to the inner ring of the bearing.

[0018] Optionally, the sealing device further includes:

[0019] The spring has an overall ring structure and is fitted onto the outer ring surface of the elastic part, and is disposed on the cross section where the elastic part, the plastic part, and the inner ring of the bearing coexist.

[0020] To address the aforementioned problems, embodiments of the present invention also provide a bearing, including an inner bearing ring, an outer bearing ring, and the aforementioned sealing device, wherein the sealing device is disposed between the inner bearing ring and the outer bearing ring.

[0021] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages:

[0022] The sealing device provided in this embodiment of the invention, when placed between the inner ring and outer ring of a bearing, forms a contact seal with the inner ring of the bearing, and the elastic part and the plastic part are relatively fixed. The plastic part is located radially between the inner ring and the elastic part. During bearing operation, relative rotation occurs between the plastic part and the inner ring. Because the coefficient of friction of the plastic part material is less than that of the elastic part material, the friction between the plastic part and the inner ring is less than that between the elastic part and the inner ring. The surface of the plastic part in contact with the inner ring is less prone to wrinkling. Therefore, even if the bearing suddenly changes its rotation direction and the grease fails to change direction in time, the grease will not move axially due to the pumping effect of the wrinkles. This improves grease leakage between the inner ring and the plastic part when the inner ring suddenly changes its rotation direction, enhancing the sealing effect of the sealing device. Furthermore, the reduced friction between the plastic part and the inner ring extends the service life of the sealing device.

[0023] In an optional configuration, the plastic part is an overall annular structure, including a fixed outer ring end and a free inner ring end. The fixed outer ring end is fixed to the axial outer end face of the frame. When the sealing device is placed between the inner and outer rings of the bearing, the free inner ring end can bend axially along the sealing device and is positioned radially between the inner ring and the elastic part. The elastic part is fixed relative to the free inner ring end. By fixing the plastic part to the frame, the rigidity is improved, axial movement of the plastic part is prevented, and the end face of the plastic part is ensured to be parallel to the axial end faces of other bearing components (inner and outer rings). Since the free inner ring end can bend axially along the sealing device after installation and is positioned radially between the inner ring and the elastic part, the contact area between the plastic part and the inner ring is increased, providing space for subsequently creating an annular groove at the free inner ring end. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 and Figure 2 This is a schematic diagram showing the interaction between the sealing device and the inner ring of the bearing under different rotational directions;

[0026] Figure 3This is a schematic diagram of the sealing device provided in an embodiment of the present invention;

[0027] Figure 4 This is another structural schematic diagram of the sealing device provided in an embodiment of the present invention;

[0028] Figure 5 yes Figure 4 Installation status diagram;

[0029] Figure 6 This is another structural schematic diagram of the sealing device provided in the embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of the bearing structure provided in an embodiment of the present invention.

[0031] Wherein: 1-Sealing lip; 2-Bearing inner ring; 5-Sealing part; 10-Elastic part; 20-Plastic part; 210-Outer ring fixed end; 220-Inner ring free end; 200-Annular groove; 230-Dustproof lip; 30-Skeleton; 40-Bearing outer ring; 50-Bearing inner ring; 60-Thrust surface; 70-Stop ring; 80-Spring. Detailed Implementation

[0032] As can be seen from the background technology, the sealing performance of articulated arm bearings needs to be improved.

[0033] The following is combined Figures 1-2 Analyze the reasons for poor bearing sealing performance.

[0034] Figure 1 and Figure 2 This is a schematic diagram showing the interaction between the sealing device and the inner ring of the bearing under different rotation directions.

[0035] A sealing device generally includes a skeleton, a rubber component bonded to the skeleton, and a rubber sealing lip 1 that contacts the inner ring 2 of the bearing. The sealing device is positioned between the inner ring 2 and the outer ring of the bearing, and the sealing lip 1 forms a contact seal with the inner ring 2. Taking a bearing mounted on a robotic arm as an example, because the robotic arm needs to perform grasping and retraction actions, the bearing requires low-speed bidirectional slow rotation, typically less than 30 rpm, with frequent changes in rotation direction. Figure 1 As shown, hollow arrow A represents the bearing rotation direction, and solid arrow B above sealing lip 1 represents the radial force (the force that makes sealing lip 1 press tightly against the bearing inner ring 2). When the bearing rotates, the grease rotates with the inner ring. Due to the friction between sealing lip 1 and bearing inner ring 2, sealing lip 1 is stretched and deformed on bearing inner ring 2, forming wrinkles (such as...). Figure 1 As shown by the wavy line in the middle, this fold can pump the grease on the sealing lip 1 back to the inside of the bearing (i.e., Figure 1(Left side of the diagram). The dense arrows below the inner ring 2 of the bearing represent the C-pressure distribution diagram, which is determined by the shape of the folds in the diagram. (See the diagram on the left.) Figure 2 As shown, when the rotation direction suddenly changes, the rotation direction of the inner ring 2 of the bearing immediately changes (in the direction of the hollow arrow A). Correspondingly, the wavy direction of the pleats on the sealing lip 1, which contacts the inner ring 2 of the bearing, changes. However, due to the low rotation speed, the direction of grease movement cannot change in a short time. When encountering pleats with changing direction (…), Figure 2 As shown by the wavy line, under the pumping action of the folds, the grease will move towards the outside of the bearing (i.e., Figure 2 The movement (right side of the middle) makes it easy for grease to leak.

[0036] To improve the sealing performance of articulated arm bearings, this invention provides a sealing device. During bearing operation, relative rotation occurs between the plastic part and the inner ring of the bearing. Because the coefficient of friction of the material of the plastic part is less than that of the material of the elastic part, the frictional force between the plastic part and the inner ring of the bearing is less than that between the elastic part and the inner ring of the bearing. The surface of the plastic part in contact with the inner ring of the bearing is less prone to wrinkling. Therefore, even if the bearing suddenly changes its rotation direction, and the grease fails to change with the rotation direction in time, the grease will not move axially due to the pumping effect of the wrinkles. This improves the grease leakage between the inner ring of the bearing and the plastic part when the inner ring of the bearing suddenly changes its rotation direction, thus improving the sealing effect of the sealing device. Furthermore, the reduced frictional force between the plastic part and the inner ring of the bearing can extend the service life of the sealing device.

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that, unless otherwise specified, axial, radial, and circumferential refer to the axial, radial, and circumferential directions of the sealing device, respectively; the outer end of the axial direction refers to... Figures 3-7 The right side of the middle, the inner end of the axial direction refers to Figures 3-7 The left side; radially outer side refers to the side that is radially away from the central axis of the sealing device. Figures 3-7 The upper side of the seal), the radial inner side refers to the side that is radially closer to the central axis of the sealing device (the upper side of the seal). Figures 3-7 (the lower side of the middle).

[0039] This invention provides a sealing device suitable for placement between the inner ring and outer ring of a bearing, the sealing device comprising:

[0040] skeleton;

[0041] The sealing part has an overall annular structure and includes an elastic part and a plastic part. The elastic part is fixed to the skeleton. When the sealing device is placed between the inner ring and the outer ring of the bearing, the plastic part forms a contact seal with the inner ring of the bearing. The elastic part and the plastic part are relatively fixed, and at least part of the plastic part is disposed between the inner ring of the bearing and the elastic part in the radial direction. The coefficient of friction of the material of the plastic part is less than the coefficient of friction of the material of the elastic part.

[0042] It should be noted that the relative fixation of the elastic part and the plastic part refers to their relative stillness during the operation of the sealing device. Therefore, before the sealing device is installed between the inner and outer rings of the bearing, the elastic part and the plastic part can be directly fixed together or not in contact, as long as it ensures that they are relatively fixed after the sealing device is installed between the inner and outer rings of the bearing. For example, in one embodiment, the elastic part and the plastic part can be directly glued together, with the plastic part positioned between the inner ring and the elastic part in the radial direction; in another embodiment, the elastic part and the plastic part can be two separate components, with the elastic part abutting against the plastic part by external force (e.g., spring force) after the plastic part is installed on the inner ring of the bearing, thus achieving relative fixation between the elastic part and the plastic part. Of course, in another embodiment, both the elastic part and the plastic part can be fixed to the frame to achieve relative fixation between them.

[0043] For details, please refer to Figure 3 , Figure 3 This is a partial schematic diagram of a sealing device provided in an embodiment of the present invention. Those skilled in the art will understand that... Figure 3 The diagram only shows a portion of the cross-sectional view of the sealing device.

[0044] like Figure 3 As shown, in one specific embodiment, the plastic part 20 is generally annular in structure, including a fixed outer ring end 210 and a free inner ring end 220. The fixed outer ring end 210 is fixed to the axial outer end face of the skeleton 30. When the sealing device is placed between the inner ring and the outer ring of the bearing, the free inner ring end 220 can be bent axially along the sealing device (see reference). Figure 5The plastic part 20 is radially positioned between the inner ring of the bearing and the elastic part 10, with the elastic part 10 fixed relative to the free end 220 of the inner ring. By fixing the plastic part 20 to the frame 30, the rigidity is improved, preventing axial movement of the plastic part 20 and ensuring that the end face of the plastic part 20 is parallel to the end faces of other bearing components (inner ring and outer ring 40). Since the free end 220 of the inner ring can bend axially along the sealing device after installation and is radially positioned between the inner ring of the bearing and the elastic part 10, the contact area between the plastic part 20 and the inner ring of the bearing is increased, providing space for subsequently creating an annular groove 200 in the free end 220 of the inner ring.

[0045] To improve the contact force between the free end 220 of the inner ring and the inner ring of the bearing, the sealing device may further include a spring 80 with an integral annular structure, fitted onto the outer ring surface of the elastic part 10, and disposed on the cross-section where the elastic part 10, the plastic part 20, and the inner ring of the bearing coexist. Figure 7 For example, the spring 80 is disposed on the cross section where the elastic part 10, the free end of the inner ring 220 and the inner ring of the bearing 50 coexist.

[0046] Combination Figure 4 and Figure 5 During installation, the plastic part 20 is first bent using an installation tool. Figure 5 As shown, the installation tool is then removed, allowing the free end 220 of the inner ring of the plastic part 20 to engage with the bearing inner ring 50 (shown in the diagram). Figure 7 (Middle) In close contact, while the elastic part 10, which is equipped with a loading spring 80, abuts against the plastic part 20 to increase the contact force between the plastic part 20 and the inner ring of the bearing.

[0047] The coefficient of friction of the material of the plastic part 20 is lower than that of the material of the elastic part 10. Specifically, the material of the plastic part 20 can be polytetrafluoroethylene (PTFE). PTFE has an extremely low coefficient of friction, which can greatly reduce the frictional torque of the sealing device, reduce the wear of the plastic part 20, and extend the service life of the sealing device. Of course, in other embodiments, the plastic part can also be made of other materials with low coefficients of friction to reduce the possibility of deformation of the plastic part at the contact with the inner ring of the bearing due to friction, thereby improving the sealing performance of the sealing device.

[0048] The sealing device provided in this embodiment of the invention, when placed between the inner ring and outer ring of a bearing, forms a contact seal with the inner ring of the bearing, and the elastic part and the plastic part are relatively fixed. The plastic part is located radially between the inner ring and the elastic part. During bearing operation, relative rotation occurs between the plastic part and the inner ring. Because the coefficient of friction of the plastic part material is less than that of the elastic part material, the friction between the plastic part and the inner ring is less than that between the elastic part and the inner ring. The surface of the plastic part in contact with the inner ring is less prone to wrinkling. Therefore, even if the bearing suddenly changes its rotation direction and the grease fails to change direction in time, the grease will not move axially due to the pumping effect of the wrinkles. This improves grease leakage between the inner ring and the plastic part when the inner ring suddenly changes its rotation direction, enhancing the sealing effect of the sealing device. Furthermore, the reduced friction between the plastic part and the inner ring extends the service life of the sealing device.

[0049] Continue to refer to Figure 3 In one specific embodiment, the free end 220 of the inner ring has an annular groove 200. When the free end 220 of the inner ring is located between the inner ring and the outer ring 40 of the bearing, the opening of the annular groove 200 faces the inner ring of the bearing. Once a small amount of grease flows outward axially, the grease will be retained in the annular groove 200, preventing it from continuing to flow outward axially, thus further improving the sealing effect of the sealing device.

[0050] The shape of the annular groove 200 is not limited, and the number of annular grooves 200 can be one or at least two.

[0051] Please refer to Figure 4 and Figure 5 To enhance the fixing effect of the plastic part 20, in one specific embodiment, the sealing device may further include a stop ring 70 fixed to the skeleton 30, wherein the stop ring 70 and the skeleton 30 are respectively disposed at both axial ends of the plastic part 20. When the sealing device is installed on the inner ring of the bearing, during the axial bending of the free end 220 of the inner ring of the plastic part, the fixed end 210 of the outer ring of the plastic part is confined within the axial area enclosed by the skeleton 30 and the stop ring 70, which can prevent the fixed end 210 of the outer ring from detaching from the skeleton 30 due to the tendency of the outer ring to move axially away from the skeleton 30.

[0052] Specifically, the stop ring 70 may include a fixedly connected axial portion and a radial portion. The radial portion of the stop ring 70 is press-fitted with the frame 30. The plastic portion 20 is located between the axial portion and the frame 30, and the axial portion of the stop ring 70 is press-fitted with the plastic portion 20. Alternatively, the plastic portion 20 may be directly adhered between the frame 30 and the stop ring 70. Of course, in other embodiments, to reduce costs, the sealing device may not include a stop ring, and the outer ring fixed end face of the plastic portion may be directly adhered to the outer end face of the radial portion of the frame.

[0053] Please refer to Figure 5 In one specific embodiment, the plastic part 20 further includes a thrust surface 60, which is located at the axial inner end of the plastic part 20 when the plastic part 20 forms a contact seal with the inner ring of the bearing.

[0054] It is easy to understand that the thrust surface is a slope, meaning that the thrust surface is not perpendicular to the axis, but rather forms an angle (not a right angle) with the axis. Figure 5 For example, oil is located in Figure 5 On the left side, when grease accumulates at the free end 220 of the inner ring of the plastic part 20, the thrust surface, which is an inclined surface, can block the grease. The thrust surface 60 helps to prevent the grease from flowing further towards the axial outer end.

[0055] Further reference Figure 5 In applications where the bearing requires slow bidirectional rotation, the thrust surfaces 60 are evenly distributed circumferentially along the plastic portion 20, and the slope directions of adjacent thrust surfaces 60 are symmetrical about the boundary line between adjacent thrust surfaces 60. Therefore, regardless of whether the bearing rotates in the forward or reverse direction, the thrust surfaces 60 serve to push the grease back to the axial inner end, preventing the grease from flowing further towards the axial outer end.

[0056] Please refer to Figure 6 In one specific embodiment, the plastic portion 20 may further include:

[0057] A dustproof lip 230 is fixed to the axial outer end face of the annular fixed end. When the free end 220 of the inner ring is located between the inner ring and the outer ring 40 of the bearing, the dustproof lip 230 extends axially away from the free end 220 of the inner ring and radially closer to the inner ring of the bearing. Because the dustproof lip 230 is located at the axial outer end, it can block dust and a small amount of splashed water, further improving the sealing effect of the sealing device.

[0058] Please refer to Figure 7 To address the aforementioned problems, this invention also provides a bearing, including an inner bearing ring 50, an outer bearing ring 40, and the aforementioned sealing device, wherein the sealing device is disposed between the inner bearing ring and the outer bearing ring 50.

[0059] During bearing operation, relative rotation occurs between the plastic part and the inner ring of the bearing. Because the coefficient of friction of the material of the plastic part is less than that of the material of the elastic part, the frictional force between the plastic part and the inner ring of the bearing is less than that between the elastic part and the inner ring of the bearing. The surface of the plastic part that contacts the inner ring of the bearing is less prone to wrinkling. Therefore, even if the bearing suddenly changes its rotation direction and the grease fails to change with the rotation direction in time, the grease will not move axially due to the pumping effect of the wrinkles. This can improve the grease leakage between the inner ring of the bearing and the plastic part when the inner ring of the bearing suddenly changes its rotation direction, improve the sealing effect of the bearing, and further, the reduced frictional force between the plastic part and the inner ring of the bearing can extend the service life of the bearing.

[0060] While the embodiments of the present invention have been disclosed above, the present invention is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A sealing device, characterized in that, Suitable for placement between the inner ring and outer ring of a bearing, the sealing device includes: skeleton; The sealing part has an overall annular structure and includes an elastic part and a plastic part. The elastic part is fixed to the skeleton. When the sealing device is placed between the inner ring and the outer ring of the bearing, the plastic part forms a contact seal with the inner ring of the bearing. The elastic part and the plastic part are relatively fixed, and at least part of the plastic part is disposed between the inner ring of the bearing and the elastic part in the radial direction. The friction coefficient of the material of the plastic part is less than that of the material of the elastic part. The plastic part also includes a thrust surface. When the plastic part forms a contact seal with the inner ring of the bearing, the thrust surface is located at the axial inner end of the plastic part. The thrust surfaces are evenly distributed along the circumference of the plastic part, and the slope direction of adjacent thrust surfaces is symmetrical about the boundary line of adjacent thrust surfaces.

2. The sealing device as claimed in claim 1, characterized in that, The plastic part has an overall ring structure, including a fixed outer ring end and a free inner ring end that are fixedly connected. The fixed outer ring end is fixed to the axial outer end face of the skeleton. When the sealing device is placed between the inner ring and the outer ring of the bearing, the free inner ring end can be bent along the axial direction of the sealing device and is placed between the inner ring and the elastic part in the radial direction. The elastic part is fixed relative to the free inner ring end.

3. The sealing device as described in claim 2, characterized in that, The free end of the inner ring is provided with an annular groove. When the free end of the inner ring is located between the inner ring and the outer ring of the bearing, the opening of the annular groove faces the inner ring of the bearing.

4. The sealing device as described in claim 2, characterized in that, Also includes: A stop ring is fixed to the skeleton, and the stop ring and the skeleton are respectively disposed at both ends of the plastic part along the axial direction.

5. The sealing device according to any one of claims 1-4, characterized in that, The material of the plastic part is polytetrafluoroethylene.

6. The sealing device according to any one of claims 2-4, characterized in that, The plastic part further includes: The dustproof lip is fixed to the axial outer end face of the fixed end of the outer ring. When the free end of the inner ring is located between the inner ring and the outer ring of the bearing, the dustproof lip extends in a direction that is axially away from the free end of the inner ring and radially close to the inner ring of the bearing.

7. The sealing device according to any one of claims 1-4, characterized in that, Also includes: The spring has an overall ring structure and is fitted onto the outer ring surface of the elastic part, and is disposed on the cross section where the elastic part, the plastic part, and the inner ring of the bearing coexist.

8. A bearing, characterized in that, It includes an inner bearing ring, an outer bearing ring, and a sealing device as described in any one of claims 1-7, wherein the sealing device is disposed between the inner bearing ring and the outer bearing ring.

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