Dual-Threaded Bushing Spacer Assembly for Adhesive Staking
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Solution Overview
Problem
Conventional spacer and bushing assemblies interfere with the thermal conduction path and prohibit adhesive staking, which is necessary for securing components on spacecraft, leading to potential loosening of fasteners and loss of precision alignment.
Innovation Solution
A dual-threaded bushing and spacer assembly with a counterbored countersink allows for adhesive staking between the bushing's top surface and the spacer's vertical counterbored surface, enabling compliance with NASA space flight fastener staking requirements without interfering with the precision-adjusted plane or thermal conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spacer and bushing assemblies are used to secure components, then fastening is achieved, but adhesive staking cannot be applied and thermal conduction is interfered with
Solution Approach 1:
The bushing is segmented into distinct functional zones: an external threading zone for mechanical fastening, and a recessed staking zone for adhesive application. The recess creates spatial separation between the fastener head and the staking surface, allowing both adhesive staking and mechanical threading to coexist without interference.
Solution Approach 2:
The invention transitions from a two-dimensional flat mounting surface to a three-dimensional recessed structure. By creating a countersunk recess in the bushing, the design adds vertical dimensionality that accommodates adhesive staking material while preserving the precision plane for thermal conduction.
2Strength
If conventional bushing designs are used, then mechanical fastening is achieved, but precision alignment and thermal conduction are compromised
Solution Approach 1:
Different regions of the bushing are assigned different functional qualities: the outer cylindrical surface maintains a precision-ground finish for thermal conduction and alignment, while the top surface incorporates a recessed area with different geometry for adhesive staking. This localized differentiation allows each region to optimize its specific function without compromising overall precision.
3Reliability
If adhesive staking is applied to conventional assemblies, then fastener security is improved, but thermal conduction path is blocked
Solution Approach 1:
The adhesive staking function is extracted from the primary thermal conduction path. By placing the staking recess on the top surface of the bushing rather than on the precision plane, the design separates the adhesive bonding function from the thermal conduction function, allowing both to perform optimally without interfering with each other.
Data Source
AI summary
A dual-threaded bushing and spacer assembly capable of accepting standard adhesive staking and thereby enabling compliance with NASA space flight fastener staking requirements. The assembly comprises a bushing having a head with top and bottom surfaces, inner threads, and outer threads, and a spacer having top and bottom surfaces and arranged to accept the bushing. This is achieved by providing a counterbored countersink in the spacer which provides a countersunk surface within the spacer. The countersunk surface provides a contact surface for the bushing head's bottom surface when the bushing is installed in the spacer. The spacer is further arranged such that the countersunk surface is such that, when the bushing is installed, the bushing's top surface is below the spacer's top surface. When so arranged, adhesive staking can be placed between the bushing's top surface and the spacer's vertical counterbored surface.