Elastic Deformation for Sliding Bearing Shell Boring
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Solution Overview
Problem
Existing methods for machining the sliding surfaces of bearing shells result in defects such as scratches and welded chips due to the axial offset of cutting cartridges, leading to poor surface quality, especially when processing lead-free materials.
Innovation Solution
The method involves elastically deforming the bearing shell during drilling to form exposed areas with a reduced wall thickness, allowing for simultaneous machining of the sliding surface and exposed areas using a single cutting tool, which reduces defects and simplifies the process by avoiding previously finished surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two cutting cartridges are used with axial offset to machine exposure areas and sliding surface simultaneously, then machining efficiency is improved, but surface quality deteriorates due to chip scratches and welded chips
Solution Approach 1:
The bearing shell machining process is divided into two separate operations: first machining the exposure areas, then machining the sliding surface. This segmentation eliminates the problem of chips from the second cut damaging the first cut surface, while still maintaining efficient machining through the use of a drill spindle with multiple cutting cartridges working in sequence rather than requiring multiple separate tools
Solution Approach 2:
The patent introduces an intermediary element - the elastically deformable bearing shell material itself - which allows the cutting cartridges to be positioned with axial offset. The elastic deformation enables the material to accommodate the offset positioning and machining sequence without compromising the final surface quality, as the material returns to its proper form after machining
2Ease of manufacture
If cutting cartridges are positioned with axial offset to create different cutting circle diameters, then the ability to form exposure areas and sliding surface in one stroke is improved, but chip contamination of finished surfaces occurs
Solution Approach 1:
The exposure areas are machined first as a preliminary action before machining the sliding surface. This sequencing ensures that when the second cutting cartridge machines the sliding surface, any chips generated cannot contaminate the already-finished exposure areas, since the exposure areas are positioned axially ahead in the machining stroke
Solution Approach 2:
The patent uses the axial dimension (depth) to separate the machining operations, positioning cutting cartridges at different axial locations to create different cutting circle diameters. This dimensional approach allows one surface to be finished before the next cutting operation begins, preventing chip contamination while maintaining process efficiency
3Device complexity
If a single cutting tool is used to machine both sliding surface and exposure areas, then device complexity is reduced, but manufacturing precision deteriorates due to inability to create reduced wall thickness in exposure areas
Solution Approach 1:
The patent employs a drill spindle with multiple cutting cartridges that can be positioned at different axial locations and angles. This dynamic configuration allows a single multi-tool spindle to perform functions that would otherwise require multiple separate tools, maintaining device simplicity while achieving precise control over wall thickness in different areas through the elastic deformation capability of the bearing shell material
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
This approach improves the quality of the sliding surfaces by reducing defects and simplifying the machining process, achieving a smooth transition between the sliding surface and exposed areas, thereby mitigating linear contact and enhancing reproducibility and accuracy.
Implementation Method 1
the boring is carried out on an elastically deformed bearing shell
Data Source
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AI summary
The invention relates to a method and device for producing a bearing shell having a first and a second exposed region, wherein in said regions the bearing shell has a reduced wall thickness, wherein the two exposed regions are machined on the inner face of the bearing shell at both end sections of the bearing shell and a sliding surface region is machined between the two exposed regions on the inner face of the bearing shell, and the sliding surface region and the exposed regions are machined by boring the bearing shell, characterised in that the boring is effected on an elastically deformed bearing shell and, immediately before boring, the end sections of the bearing shell at which the exposed regions are to be formed, are offset radially inwardly with respect to a circular contour.