Ball Socket Retention Structure for High Axial Load and Swing
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Solution Overview
Problem
Existing ball joint socket assemblies face challenges in supporting heavy negative axial loads without increasing manufacturing costs or restricting the swing of the ball stud, particularly when using plastic bearings that expand under load.
Innovation Solution
A ball socket assembly design featuring a monolithic metal housing with a cover plate that has a partial torus-shaped top surface and angled surface-to-surface contact with a polymeric exit bearing, which resists radial expansion and allows increased swing angle of the ball stud, while maintaining structural integrity without high-strength materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cross-sectional size of the metallic cover plate is increased to support heavy negative axial loads, then the strength to support large negative axial loads is improved, but the manufacturing cost increases and the swing of the ball stud is restricted
Solution Approach 1:
The cover plate incorporates a reinforcement rib that extends into the housing, creating a localized high-strength region only where the negative axial loads are applied. This allows the cover plate to support heavy loads without increasing the overall cross-sectional size or thickness, thereby avoiding increased manufacturing costs while maintaining adequate strength.
Solution Approach 2:
Instead of increasing the cover plate's strength by adding material in the planar dimensions (which would increase cost and restrict swing), the invention adds a vertical dimension element - the reinforcement rib that extends into the housing. This three-dimensional structural feature provides the necessary strength without increasing the cover plate's footprint or thickness.
2Strength
If the strength type of metal of the cover plate is increased to support heavy negative axial loads, then the strength to support large negative axial loads is improved, but the manufacturing cost increases
Solution Approach 1:
The reinforcement rib creates a localized high-strength structural feature that concentrates the load-bearing capacity exactly where needed - at the interface between the cover plate and the housing. This allows the use of standard-grade metal for the entire cover plate while achieving high local strength through the rib geometry, avoiding the need for expensive high-strength materials.
Solution Approach 2:
The cover plate structure effectively creates a composite system where the rib (extending into the housing) and the cover plate body work together as an integrated load-bearing structure. This composite geometry provides enhanced strength-to-cost ratio compared to using uniformly high-strength materials throughout the entire cover plate.
3Strength
If the thickness of the cover plate is increased to support heavy negative axial loads, then the strength to support large negative axial loads is improved, but the swing of the ball stud is restricted
Solution Approach 1:
The reinforcement rib extends in the vertical dimension (into the housing) rather than increasing the cover plate thickness in the horizontal dimension. This allows the cover plate to maintain its original thickness and not interfere with the ball stud swing, while still providing the necessary strength through the vertically-extending rib structure that engages with the housing.
Solution Approach 2:
The load-bearing function is segmented from the swing-clearance function. The reinforcement rib handles the load-bearing role by engaging with the housing, while the main cover plate body maintains its original thickness to allow adequate clearance for ball stud swing. This functional segmentation resolves the conflict between strength and operability.
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 design effectively supports heavy negative axial loads without increasing manufacturing costs and enhances the ball stud's swing angle and structural durability, reducing axial movement and improving resistance to deformation.
Implementation Method 1
The surface-to-surface contact area is angled towards the open second end of the housing from a radially outermost end of the surface-to-surface contact area to a radially innermost end of the surface-to-surface contact area for supporting the exit bearing against radial expansion in response to axial loads being applied on the exit bearing from the ball portion of the ball stud
Data Source
AI summary
The ball socket assembly includes a housing that is made of a monolithic piece which includes a lower wall. A ball portion of a ball stud is disposed in an inner bore of the housing. An exit bearing, which is made of a polymeric material, is disposed in the inner bore and is in slidable contact with at least one hemisphere of the ball portion. The exit bearing has an upper surface which faces towards an open end of the housing. A cover plate is in direct contact with the upper surface of the exit bearing along a surface-to-surface contact area. The surface-to-surface contact area is angled towards the open end from its radially outermost end to its radially innermost end for supporting the exit bearing against radial expansion in response to axial loads being applied on the exit bearing from the ball portion of the ball stud.