Centralizing Bushing Assembly for Lead Screw Noise and Precision
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Solution Overview
Problem
Lead screw nut devices often experience noise and positional precision issues due to clearance between the threads, which existing technologies have not adequately addressed.
Innovation Solution
A centralizing bushing assembly with a bushing housing and a resilient biasing member, such as an O-ring, is used to radially bias a centralizing ring within the bushing housing, ensuring precise alignment and damping of noise by engaging the lead screw shaft and nut, thereby reducing vibration and improving linear movement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rigid bushing structure is used to maintain alignment, then manufacturing precision is improved, but adaptability to thermal variations and assembly tolerances deteriorates
Solution Approach 1:
The bushing material transitions from rigid to elastomeric, fundamentally changing the physical state and mechanical properties. This allows the bushing to deform elastically in response to thermal expansion, assembly tolerances, and operational loads, thereby maintaining alignment precision while adapting to varying conditions.
Solution Approach 2:
The elastomeric bushing acts as a flexible element that can deform to accommodate thermal variations and assembly tolerances. The flexible material absorbs dimensional changes without compromising the alignment between the lead screw and nut, resolving the contradiction between rigid precision and flexible adaptability.
2Measurement precision
If clearance is reduced to improve positional precision, then measurement precision is improved, but reliability deteriorates due to increased contact stress
Solution Approach 1:
Changing the material from rigid to elastomeric allows the bushing to deform and fill clearance gaps elastically, maintaining positional precision without creating excessive contact stress. The elastomeric property enables the bushing to conform to the lead screw threads while distributing loads evenly.
Solution Approach 2:
The elastomeric bushing material combines the benefits of flexibility and damping with sufficient structural integrity. This composite approach allows the bushing to eliminate clearance for precision while maintaining reliability through elastic deformation and load distribution.
3Manufacturing precision
If manufacturing tolerances are tightened to reduce clearance, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
Changing to elastomeric material allows for larger manufacturing tolerances in the bushing itself, as the material's elasticity compensates for dimensional variations. This reduces the overall manufacturing precision requirements for the assembly while maintaining the desired clearance elimination and alignment.
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
The solution effectively centralizes the lead screw shaft relative to the nut, reducing noise and vibration, and ensuring precise linear movement by compensating for manufacturing clearances and thermal variations, resulting in smoother operational precision and reduced noise.
Implementation Method 1
A resilient biasing member can be positioned against the outer shoulder of the bushing ring for radially biasing the inner diameter of the bushing ring radially inwardly in a centralizing manner about the axial axis
Implementation Method 2
The bushing ring can resiliently engage outer surfaces of the lead screw for centering the lead screw relative to the threaded nut for proper contact therebetween and damping noise
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A centralizing bushing assembly (15) includes a bushing housing (3) having axial ends and an opening (21) extending therethrough along an axial axis. The opening (21) can have a pocket (16) extending outwardly from the axial axis within the bushing housing (3) and have internal shoulders (5) axially facing each other. A bushing ring (1, 2) can be positioned within the pocket (16) of the bushing housing (3) between the internal shoulders (5). The bushing ring (1) can have a split for allowing collapsing of the bushing ring (1) radially inward and have an inner diameter for slidably engaging an axially movable shaft extending through the bushing housing (3) along the axial axis and also have an outer shoulder (28). A resilient biasing member (2) can be positioned against the outer shoulder (28) of the bushing ring (1) for radially biasing the inner diameter of the bushing ring (1) radially inwardly in a centralizing manner about the axial axis for engaging and centralizing the shaft slidably positioned therethrough.