Plain bearing and use thereof

Abstract

The application provides a sliding bearing (10) of a supporting shaft system in the field of low speed and heavy load. The sliding bearing (10) comprises an inner ring (11), an outer ring (12) and a bearing bushing (13) arranged between the inner ring and the outer ring. The bearing bushing (13) is mainly interwoven and wound by a fiber composite material, and the interwoven and wound direction is an acute angle with the circumferential direction of the bushing. The radially outer part of the bearing bushing (13) forms a supporting backing (13a), and the radially inner part forms a wear-resistant layer (13b). The sliding bearing (10) with the above structure and material has all-round performance advantages and cost advantages for adapting to the harsh technical requirements in the field of low speed and heavy load, and has great practical significance and wide application prospect.

Description

Technical Field

[0001] This invention relates to a sliding bearing, and more particularly to a sliding bearing suitable for low-speed, heavy-load operating conditions. Background Technology

[0002] Low-speed, heavy-load applications have always posed a severe challenge to bearing applications. Take continuous casting rolls in steel mills as an example... Figure 2 As shown, the fixed-position roller bearings on the left (first from left) and the floating-position roller bearings on the right (first to third from right) provide rotational support for the shaft system of the continuous casting roll. In the illustrated shaft system, the floating-position bearings not only need sufficient load-bearing capacity but also need to accommodate axial float caused by system temperature rise and dynamic shaft deflection caused by radial load compression. Specifically, thermal expansion caused by temperature rise leads to lateral displacement of the bearing's inner ring following the mandrel 1 of the continuous casting roll; simultaneously, the heavy load forces the mandrel 1 of the continuous casting roll to warp (as shown in the figure), resulting in misalignment of the bearing's inner and outer rings. These concurrent operating conditions pose a significant challenge to existing roller bearings. Although specially designed roller bearings can adapt to these operating requirements to varying degrees, they generally face problems such as excessive cost or inconvenient maintenance.

[0003] by Figure 3 The toroidal bearing shown is a typical example of a rolling bearing used to support the floating end of a continuous casting roll. While it can accommodate both axial floating and misalignment of the inner and outer rings, the annular raceways of its inner and outer rings and the annular surfaces of the rollers result in high manufacturing costs. More seriously, disassembling this bearing from the continuous casting roll is extremely inconvenient. Improper use of the bearing puller (such as clamping it onto the inner ring) can easily damage the bearing, making subsequent maintenance impossible. There is a real need for a cost-effective and easy-to-maintain shaft system solution. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a sliding bearing for shaft systems in low-speed, heavy-load applications. The sliding bearing comprises an inner ring, an outer ring, and a load-bearing bushing disposed between the inner and outer rings. The load-bearing bushing is primarily composed of interwoven fiber composite material, with the interwoven winding direction forming an acute angle with the circumferential direction of the bushing. The bushing forms a supporting backing on its radially outer portion and a wear-resistant layer on its radially inner portion.

[0005] The sliding bearings using the above structure and materials have comprehensive performance and cost advantages in adapting to the harsh technical conditions of low-speed heavy-load fields, and have great practical significance and broad application prospects. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of the three-dimensional shape of a continuous casting roll;

[0007] Figure 2 for Figure 1 A schematic cross-sectional view of the continuous casting roll shown in the figure;

[0008] Figure 3 for Figure 2 A schematic diagram of the cross-section of the annular roller bearing used in the floating end;

[0009] Figure 4 This is a cross-sectional schematic diagram of the sliding bearing described in this invention;

[0010] Figure 5 This is a schematic diagram of the structure of a load-bearing bushing formed by interwoven and wound fiber materials; and

[0011] Figure 6 This is a magnified view of the composite material in the wear-resistant layer of the bearing bushing. The dark part is PTFE fiber, the light part is polymer fiber, and the rest is epoxy resin filler. Detailed Implementation

[0012] Figure 4 This is a cross-sectional schematic diagram of the sliding bearing described in this invention. The sliding bearing 10 consists of an inner ring 11, an outer ring 12, and a load-bearing bushing 13 disposed between the inner and outer rings, and is integrally mounted in a bearing housing 20. The load-bearing bushing 13 is mainly composed of interwoven fiber composite material, with the interwoven winding direction forming an acute angle with the circumferential direction, and is ultimately impregnated into an epoxy resin matrix for fixation. Typically, the fiber composite material is based on polytetrafluoroethylene (PTFE), and the mechanical properties of the formed load-bearing bushing are improved by adding fillers such as glass fiber, carbon, graphite, molybdenum disulfide, and bronze, or polymer fiber. Generally, in addition to the excellent chemical and high-temperature properties of PTFE, fillers can improve mechanical strength, stability, and wear resistance.

[0013] The aforementioned materials and forming process not only give the load-bearing bushing a significantly higher load-bearing capacity than the rolling elements of a rolling bearing, but also allow its flexibility to withstand [various loads]. The above-mentioned misalignment capability is sufficient to meet the requirements of many low-speed, heavy-load applications, including continuous casting production lines. Incidentally, the material and thickness of the bearing bushing also significantly affect its ability to deform (i.e., adapt to bearing misalignment), and therefore, the material and / or thickness of the bearing bushing can be adjusted according to actual needs. For example, increasing its thickness can improve its ability to adapt to misalignment. In addition, the cylindrical hollow structure of the bearing bushing allows the inner and outer rings of the bearing to move relative to each other in the axial direction, similar to the case of a cylindrical roller bearing, which is sufficient to accommodate the need for maximum axial displacement adjustment.

[0014] Figure 5 This is a schematic diagram of a bearing bushing formed by interwoven fiber composite materials. The outer radial material of the bearing bushing 13 forms a supporting backing 13a, while the inner radial material forms a low-friction wear-resistant layer 13b. Typically, the backing 13a can be primarily made of high-strength glass fiber to ensure sufficient rigidity and strength; the wear-resistant layer 13b can be primarily made of a mixture of polytetrafluoroethylene and polymer fibers to ensure both low friction and tough wear resistance. The bearing bushing 13 forms a tight fit with the inner surface of the outer ring 12 on its backing 13a side, thus maintaining relative stationary position with the outer ring 12 and ensuring that the sliding friction of the bearing 10 during operation actually occurs between the wear-resistant layer 13b and the outer surface of the inner ring 11. To further improve the wear resistance of the inner ring and reduce its coefficient of friction, a preferred embodiment is to harden its outer surface and reduce its roughness R. a The roughness is limited to between 0.2 and 0.4 μm. The hardening treatment can be nitriding or hard chrome plating, and polishing is used as a process to control the roughness. Obviously, a hard and smooth surface is more conducive to reducing friction and improving lifespan.

[0015] While sliding bearings have existed as bearings in a broad sense for a long time, this invention marks the first time a sliding bearing with the aforementioned structure has been used as a floating end bearing in a shaft system for low-speed, heavy-load applications. This application overcomes the long-held industry prejudice that floating end bearings in shaft systems can only be performed by rolling bearings, opening a new path for sliding bearings to replace traditional rolling bearings in shaft systems. Specifically, in a low-speed, heavy-load shaft system, the fixed end bearing anchors the entire shaft system axially, while the sliding bearing described in this invention can replace traditional rolling bearings, providing radial support to the shaft system as a floating end bearing.

[0016] The shaft systems used in the low-speed, heavy-load applications are primarily for various mill rolls, including continuous casting rolls in steel mills and paper mill dryer rolls in the paper industry. The bearing arrangements used in these rolls include a fixed-end bearing positioned at a fixed end support and at least one floating-end bearing positioned at a floating end support. The sliding bearing described in this invention is particularly suitable for use as a floating-end bearing in the aforementioned bearing arrangements, or for replacing floating-end rolling bearings in conventional bearing arrangements.

[0017] It is not difficult to see that the sliding bearing of the present invention is quite similar in form to the rolling bearing, the only difference being that a bearing bushing replaces the series of rolling elements arranged circumferentially in the rolling bearing. This similarity gives the sliding bearing of the present invention a natural advantage in replacing rolling bearings (especially cylindrical roller bearings and annular roller bearings). Taking advantage of this, the sliding bearing described in the present invention can be manufactured with the same boundary dimensions as rolling bearings in a specific field and / or standard, thereby ensuring its full linter changeability with specific rolling bearings. For example, annular bearings C4024 and C4032 are common bearing models for the floating ends of shaft systems of continuous casting rolls under the ISO 15 (4th edition 2017-07) standard series, with boundary dimensions (inner diameter × outer diameter × width) of 120 × 180 × 60 and 160 × 240 × 80 mm, respectively. For this type of annular roller bearing, as long as a sliding bearing with sufficiently consistent boundary dimensions is produced, the rolling bearing at the floating end can be easily replaced without changing the existing shaft system, thus having significant commercial value and broad application prospects.

[0018] The aforementioned replacement comprehensively enhances the technical performance of the shaft system and significantly reduces the user's operating costs. As mentioned earlier, this replacement improves the radial load-bearing capacity of the shaft system and enables the floating end bearing to achieve both axial floating and misalignment operation. Furthermore, the fiber material and epoxy composite matrix of the load-bearing bushing provide it with exceptional corrosion resistance, making it particularly suitable for heavily polluted environments such as metallurgy, mining, machinery, and chemical industries. Therefore, compared to rolling bearings composed entirely of metal rolling elements, this invention offers advantages such as longer lifespan and maintenance-free operation. On the other hand, since the load-bearing bushing functionally replaces the rolling elements between the inner and outer rings of the bearing, the number of rolling components in the bearing is greatly reduced, thus significantly improving the bearing's operational reliability. More importantly, the load-bearing bushing used in the sliding bearing requires no lubrication, allowing the shaft system to operate safely with a default lubrication system. This not only significantly reduces operating costs but also avoids environmental pollution caused by lubricating oil emissions.

[0019] One of the few drawbacks of fiber-wound bushings is their limited resistance to intrusive particles, thus requiring protection of the wear-resistant layer from intrusive dust and impurities. To address this, in cases where the overall seal of the bearing housing is insufficient, additional seals (not shown) can be added on both sides between the inner and outer rings of the bearing (load-bearing bushing). A retaining ring can be further installed on the axially outer side of the seal to prevent it from dislodging from the bearing during operation (not shown).

[0020] As can be seen from the above description, the sliding bearing described in this invention possesses comprehensive technical performance adaptable to low-speed, heavy-load operating conditions, such as high load-bearing capacity, axial floating capability, and misalignment capability. Simultaneously, its unique performance in other aspects, such as ease of disassembly and assembly, impact resistance, corrosion resistance, maintenance-free operation, lubrication-free operation, and low cost, provides comprehensive technical advantages that rolling bearings do not possess. These comprehensive performance advantages make it suitable not only as a floating end bearing in the shaft system of continuous casting rolls but also as a floating end bearing in any other low-speed, heavy-load shaft system, such as dryer rollers in paper mills, wind turbine bearings, and large gearboxes, which will not be elaborated upon here.

[0021] Those skilled in the art should understand that the sliding bearing and its applications are not limited to the specific embodiments described above. Any modifications and improvements to this invention, as long as they comply with the limitations of the appended claims, are within the scope of protection of this invention.

Claims

1. A sliding bearing (10), comprising an inner ring (11), an outer ring (12), and a load-bearing bushing (13) disposed between the inner and outer rings, characterized in that: The sliding bearing (10) is configured to have boundary dimensions that are fully consistent with the rolling bearing it replaces, in order to ensure full interchangeability with the replaced rolling bearing; and the sliding bearing (10) is used as a floating end bearing of the shaft system, wherein the floating means that thermal expansion caused by temperature rise causes the inner ring (11) to move axially along the spindle (1) of the shaft system.

2. The sliding bearing (10) as described in claim 1, characterized in that, The bearing bushing (13) is mainly made of interwoven fiber composite material, and the direction of interwoven winding is at an acute angle to the circumferential direction.

3. The sliding bearing (10) as described in claim 2, characterized in that, The radially outer portion of the bearing bushing (13) forms a supporting backing (13a), and the radially inner portion forms a wear-resistant layer (13b).

4. The sliding bearing (10) as described in claim 3, characterized in that, The backing (13a) is mainly made of high-strength glass fiber, and the wear-resistant layer (13b) is mainly made of PTFE-added polymer fiber.

5. The sliding bearing (10) as described in claim 3, characterized in that, The bearing bushing (13) forms a tight fit with the outer ring (12) on its backing (13a) side, thereby keeping it relatively stationary with the outer ring (12) and ensuring that the sliding friction of the bearing (10) actually occurs between the wear-resistant layer (13b) and the inner ring (11) during operation.

6. The sliding bearing (10) as described in claim 5, characterized in that, The outer surface of the inner ring (11) is hardened, and the roughness R is [not specified]. a It is controlled within the range of 0.2 – 0.4 μm.

7. The sliding bearing (10) as described in claim 6, characterized in that, The hardening treatment refers to nitriding or hard chrome plating, with polishing used as a process to control roughness.

8. The sliding bearing (10) as described in any one of claims 1-7, characterized in that, The sliding bearing (10) has seals on both sides of its inner and outer rings (11, 12) in the axial direction.

9. The sliding bearing (10) as described in claim 8, characterized in that, The inner and outer rings (11, 12) and the bearing bushing (13) of the sliding bearing (10) are all hollow cylindrical in shape.

10. A shaft system for low-speed, heavy-load applications, wherein the bearing configuration of the shaft system comprises a fixed-end bearing disposed at a fixed-end support position and at least one floating-end bearing disposed at an axially floating-end support position, characterized in that: The floating end bearing is a sliding bearing (10) as described in any one of claims 1 to 9.

11. A roll employing a sliding bearing (10) as described in any one of claims 1 to 9 as its axial floating end support bearing.

12. The roll as described in claim 11, characterized in that: The rolls are continuous casting rolls from steel mills and / or dryer rolls from paper mills.

13. A bearing configuration for a roll comprising at least one sliding bearing (10) as described in any one of claims 1 to 9.

14. A method for replacing a bearing configuration in a rolling mill roll, the bearing configuration comprising a fixed-end bearing disposed on a fixed-end support position and at least one floating-end rolling bearing disposed on an axially floating-end support position, characterized in that: The axial floating end rolling bearing in the bearing configuration is replaced by a sliding bearing (10) as described in any one of claims 1 to 9.

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