Bearing Pin Upset Method for Tappet Retention
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Solution Overview
Problem
Current high hardness upset methods for axles in tappets are not robust enough to maintain rotational freedom and balance around the circumference of the pin, leading to periodic loss of alignment and increased load requirements.
Innovation Solution
A method using a peen tool with a concave distal end surface to displace material at the terminal ends of the axle, forming bulbous ends that securely lock the axle within the tappet body, ensuring consistent diameter and reduced axial deformation, thereby enhancing retention force and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high hardness upset methods are used to lock the axle, then retention force is improved, but rotational freedom and alignment are lost
Solution Approach 1:
The peen tool applies localized deformation only at the terminal ends of the axle, creating bulbous enlargements that provide retention force without affecting the intermediate portion. This localized approach allows the bearing to rotate freely along the axle while the ends remain locked in position.
Solution Approach 2:
The upset method applies partial action by deforming only the terminal ends of the axle rather than the entire length. This partial deformation is sufficient to achieve the locking function while preserving rotational freedom in the bearing contact area.
2Ease of manufacture
If conventional upset methods are used, then manufacturing simplicity is maintained, but manufacturing precision and alignment are degraded
Solution Approach 1:
The peen tool creates bulbous, rounded enlargements at the axle ends through oscillating contact. This curved deformation pattern ensures uniform material displacement and consistent diameter formation, improving alignment precision while maintaining the simplicity of a single-tool process.
3Strength
If material displacement is increased to improve retention, then retention force is improved, but axial deformation and tilting increase
Solution Approach 1:
The peen tool oscillates around the radius of the axle terminal ends during the upset process. This vibratory motion distributes material displacement more uniformly, creating symmetric bulbous enlargements that provide retention force without causing excessive axial deformation or tilting.
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 method provides improved retention force and alignment of the bearing within the tappet body, reducing cycle time and load requirements compared to prior art methods, while maintaining consistent axle diameter and preventing tilting of the bearing.
Implementation Method 1
An area of the axle is displaced based on the contacting. The displacing can further comprise displacing material of the axle at the first terminal end resulting in a first deformation having a first bulbous end.
Implementation Method 2
A method of upsetting an axle with a peen tool according to one example of the present disclosure includes contacting a distal end surface of the peen tool with a first terminal end of the axle.
Data Source
AI summary
A method of upsetting an axle with a peen tool according to one example of the present disclosure includes contacting a distal end surface of the peen tool with a first terminal end of the axle. The distal end surface of the peen tool has a relief portion formed on the distal end surface that includes a concave profile. An area of the axle is displaced based on the contacting.