Bearing Pretensioning Device with Zero-Degree Thread Flank
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Solution Overview
Problem
Large bearing units, such as those in wind turbines, face challenges in reliably setting bearing preload without tilting the bearing ring relative to the bearing axis, especially due to the small width-to-diameter ratio of the bearing rings, which leads to tilting and axial run-out deviations, complicating assembly and potentially causing premature damage.
Innovation Solution
A bearing pretensioning device with a novel thread geometry where the load-transmitting thread flank has a flank angle of 0°, and the opposite thread flank has a flank angle of 0° to 30°, allowing for precise axial displacement without misalignment, combined with friction-reducing elements like lubricants or coatings, and rolling bodies to minimize torque and prevent tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional thread geometry with flank angles of 30° or 15° is used, then the bearing ring can be displaced axially to introduce preload, but the bearing ring tilts relative to the bearing axis due to misalignment
Solution Approach 1:
The patent changes the thread geometry parameters by reducing the flank angle of the load-transmitting thread flank to a maximum of 10° (preferably maximum 5°, in particular 0°). This parameter change reduces the radial component of the thread force, minimizing bearing ring tilt and axial run-out deviations during preload application.
Solution Approach 2:
The patent employs asymmetric thread flank angles where the load-transmitting flank has a maximum of 10° (preferably 0°) while the opposite flank has an angle of ≥0° (preferably 0°-30°). This asymmetric design optimizes force transmission while minimizing tilting effects during axial displacement.
2Strength
If the bearing ring width-to-diameter ratio is small (large diameter bearings), then the bearing can handle high loads, but the bearing ring is more prone to tilting during axial displacement
Solution Approach 1:
The patent changes the thread geometry parameters to compensate for the small width-to-diameter ratio effect. By reducing the load-transmitting thread flank angle to a maximum of 10° (preferably 0°), the radial force component is minimized, preventing tilting even in large diameter bearings with small width-to-diameter ratios.
Solution Approach 2:
The patent applies preliminary anti-action by designing the thread geometry to preemptively counteract the tilting tendency. The reduced flank angle prevents the radial force component that would cause tilting, addressing the problem before it occurs during assembly.
3Ease of manufacture
If conventional thread geometry is used, then assembly is simpler, but costly hydraulic presses are required to apply sufficient axial force without tilting
Solution Approach 1:
The patent changes the thread geometry parameters to reduce the radial force component by using a load-transmitting flank angle of maximum 10° (preferably 0°). This allows axial displacement to be achieved with simpler equipment without tilting, eliminating the need for costly hydraulic presses while maintaining assembly simplicity.
4Manufacturing precision
If thread tolerances are tight to prevent tilting, then axial run-out deviation is minimized, but manufacturing complexity and cost increase
Solution Approach 1:
The patent changes the thread geometry parameters (reducing the load-transmitting flank angle to maximum 10°) to inherently minimize tilting. This allows for more forgiving thread tolerances while still achieving minimal axial run-out deviations, reducing manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures reliable preload setting without tilting, reduces manufacturing complexities, and minimizes axial run-out deviations, enhancing the bearing's functionality and longevity by allowing for more forgiving thread tolerances and precise assembly without the need for costly hydraulic presses.
Implementation Method 1
The flank angle of the load-transmitting thread flank is a maximum of 10°, preferably a maximum of 5° and in particular 0°. The flank angle of the opposite thread flank is ≥0°, preferably in the range of 0°-30°
Implementation Method 2
rolling bodies to minimize torque and prevent tilting
Implementation Method 3
friction-reducing elements like lubricants or coatings
Data Source
Figure 1~3C
Figure 4A~5
Figure 6~7
AI summary
The bearing clamping device serves to pre-tension a large bearing unit (2) and has an inner part (28) with an external thread (30) and an outer part (26) with an internal thread (24). These two parts (26, 28) are designed to clamp against a bearing ring (12) of the bearing (8) of the large bearing unit (2). For this purpose, the two threads (24, 30) engage with each other when the two parts (26, 28) are rotated and each has a load-bearing thread flank (32a) and an opposing thread flank (32b), wherein a flank angle (a1) of the load-bearing thread flank (32a) is a maximum of 10°, preferably a maximum of 5°, and particularly 0°.