How do expander bearings composed of freely tiltable tiles form a self-sustaining fluid dynamic film to achieve efficient operation? ​

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In modern industrial equipment, expanders are the core devices for energy conversion and transmission, and their stable operation is inseparable from the support of high-performance bearings. Among the many types of bearings, bearings composed of a series of tiles supported on a support ring and freely tiltable have become key components for the efficient operation of expanders due to their ability to form a self-sustaining fluid dynamic film. It is worth exploring how this unique bearing structure works and why it can play an important role under complex working conditions. ​
The basic structure of expander bearings consists of tiles and support rings. Tiles are the core load-bearing units of bearings, and the number is usually multiple and evenly distributed on the inner side of the support ring. The support ring, as a supporting structure, provides a stable installation base for tiles and ensures the relative position of each tile is accurate. The design of the tiles is unique, and its surface is precisely machined to maintain a specific gap with the rotating shaft. Each tile can tilt freely around its own fulcrum. This seemingly simple degree of freedom design actually contains exquisite mechanical principles.​
When the rotating shaft of the expander starts to run, the gap between the shaft and the tile is filled with lubricating medium, usually lubricating oil. As the shaft rotates, the lubricating oil is brought into the wedge-shaped gap between the shaft and the tile. Since the tile can tilt freely, under the action of the lubricating oil, the tile will automatically adjust the tilt angle according to the position and movement state of the shaft. When the shaft rotates, the lubricating oil is squeezed in the wedge-shaped gap and the pressure gradually increases. As the shaft speed increases, the pressure of the lubricating oil further increases, and a layer of fluid dynamic film with a certain load-bearing capacity is formed between the shaft and the tile. ​
This self-sustaining fluid dynamic film has multiple important functions. First, it completely separates the shaft from the tile, avoiding direct contact between solids, thereby greatly reducing friction resistance. Compared with traditional sliding bearings, this design reduces the energy loss caused by friction and improves the mechanical efficiency of the expander. Secondly, the fluid dynamic film has good buffering and vibration reduction performance. During the operation of the expander, the shaft will inevitably be affected by various disturbances and unbalanced forces, causing the shaft to vibrate and deflect. The tiles can quickly adjust their positions by freely tilting, so that the thickness and pressure distribution of the fluid dynamic film change, generating a force opposite to the disturbance direction, effectively suppressing the vibration of the shaft, and ensuring the stable operation of the shaft. ​
In practical applications, this type of bearing shows strong adaptability under different working conditions. In a high-speed expander, the shaft speed is usually high, and traditional bearings may not be able to work stably due to friction heating and increased vibration. The bearing composed of freely tiltable tiles can automatically adjust the state of the fluid dynamic film as the shaft speed increases. The lubricating oil forms a more stable pressure distribution under high-speed flow, and the free tilting characteristics of the tiles ensure that the fluid dynamic film always maintains a suitable thickness and shape, providing reliable support for the shaft, so that the expander can still maintain efficient and stable performance when running at high speed. ​
For expander working conditions with large loads, this bearing also performs well. When the shaft is subjected to a large radial load, the tile on the side of the force will tilt further under the load, reducing the thickness of the fluid dynamic film on that side and increasing the pressure, thereby providing sufficient bearing capacity to support the weight of the shaft and external loads. Other tiles will also automatically adjust their tilt angles according to the force conditions to share the load and avoid damage to a single tile due to excessive pressure. This load-adaptive characteristic enables the bearing to maintain good working conditions under heavy load conditions, extending the service life of the bearing and the expander. ​
In terms of the choice of lubrication method, the structural characteristics of the bearing also provide a flexible solution. For different operating conditions and requirements, the bearing box can be completely filled with lubricating oil to ensure that the bearing can be fully lubricated under various conditions. For high-speed application scenarios, it is more appropriate to guide the lubricating oil to the thrust surface and then let the oil drain freely from the bearing box. This lubrication method can promptly remove the heat generated by friction during high-speed operation, avoid the performance degradation of the lubricating oil due to high temperature, and ensure the stability of the fluid dynamic film. ​
From the perspective of manufacturing technology, in order to achieve free tilting of tiles and precise matching clearance, extremely high requirements are placed on processing accuracy. The surface of the tile needs to be finely ground and polished to ensure that the surface roughness reaches an extremely low level, reduce the flow resistance of the lubricating oil, and improve the formation efficiency of the fluid dynamic film. The manufacturing of the support ring also needs to ensure good dimensional accuracy and form and position tolerance to ensure that each tile can be evenly stressed and work stably after installation. In addition, the assembly process of the bearing is also critical, and the matching clearance between the tile, the support ring, and the shaft needs to be strictly controlled. Through precise measurement and adjustment, it is ensured that the bearing can normally exert its performance advantages after installation.