Ball Stud Blind-Hole Joint for Wear-Resistant Chassis Pivots

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Solution Overview

Problem

Existing ball joints in vehicle chassis components face challenges in achieving high wear resistance and corrosion resistance, particularly when produced using plastic encapsulation methods, as traditional joining methods like welding cannot be combined with nitrocarburizing, and through-holes in the joint ball hinder pivot movement in plastic overmoulding.

Innovation Solution

A ball pivot design featuring a blind hole in the joint ball that receives the joint shaft, allowing for a frictional connection and nitrocarburizing for enhanced wear and corrosion resistance, suitable for plastic encapsulation, with the joint shaft optionally coated for additional surface treatment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a through hole is formed in the joint ball to press the joint shaft, then the joint strength is improved, but the pivot movement is hindered in plastic overmoulding

Engineering Contradiction:
Improvejoint strengthVSAvoidpivot movement
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The hole in the joint ball is segmented into a blind hole rather than a complete through hole, allowing the joint shaft to be pressed in while maintaining the spherical outer surface for proper pivot movement in plastic overmoulded ball joints

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The hole is extracted only partially through the joint ball (blind hole) rather than completely, removing just enough material to accommodate the joint shaft while preserving the necessary spherical geometry for pivot movement

Inventive Principle:
Principle #2Taking out (Extraction)

2Strength

If welding is used to join the joint ball and joint shaft, then the connection strength is improved, but nitrocarburizing cannot be applied to the joint ball

Engineering Contradiction:
Improveconnection strengthVSAvoidwear resistance and corrosion resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The welding process is replaced with a mechanical pressing connection through a blind hole, eliminating the thermal process that would interfere with nitrocarburizing while still achieving sufficient connection strength

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The joint ball is nitrocarburized before the joint shaft is pressed into the blind hole, allowing the surface treatment to be applied to the entire spherical surface including areas that will later be covered by the joint shaft

Inventive Principle:
Principle #10Preliminary action

3Strength

If the joint ball is nitrocarburized for wear resistance, then the surface hardness is improved, but the joining process becomes more restricted

Engineering Contradiction:
Improvesurface hardnessVSAvoidjoining process flexibility
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The nitrocarburizing process is performed before the joining operation of pressing the joint shaft into the blind hole, allowing the full spherical surface to receive the surface treatment without restriction from the subsequent joining process

Inventive Principle:
Principle #10Preliminary action

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 ball pivot achieves high wear and corrosion resistance while enabling smooth pivot movement and compatibility with plastic encapsulation, enhancing the durability and mobility of the ball joint in vehicle chassis components.

Implementation Method 1

Nitrocarburizing is a thermo-chemical process for enriching the surface layer of the joint ball with nitrogen and carbon, creating a nitrided layer that increases the wear resistance and corrosion resistance of the steel joint ball

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

A blind hole is formed in the joint ball, which receives the joint shaft in sections

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3513084B1Ball stud
Publication Date: 2021.07.21 ZF FRIEDRICHSHAFEN AG
  • EP3513084B1 patent drawingFigure 1
  • EP3513084B1 patent drawingFigure 2

AI summary

The invention relates to a ball pin (1) for a ball-and-socket joint (2), in particular for use on the chassis of a vehicle, comprising a joint shaft (3) and a joint ball (4) connected to the joint shaft (3). The invention is characterized in that a blind hole (5) is formed in the joint ball (4), which receives some sections of the joint shaft (3).