Bearing Shell Sliding Surface Profiling via Adjustable Cutting Cartridge
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Solution Overview
Problem
Conventional machining of bearing shells results in uniform but unavoidable groove profiling, leading to increased wear and bending/tilting of shafts under load, especially in high-load applications like internal combustion engines, due to imprecisions at connection sites and uneven load distribution.
Innovation Solution
A drilling spindle with adjustable cutting cartridges, driven by a rotary drive and featuring a piezo element for precise axial adjustment, allows for targeted profiling of the sliding surface, creating convex curves at edge regions to enhance lubrication and reduce wear, while forming exposed regions to prevent inward protrusions and minimize bending/tilting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional drilling out with fixed cutting cartridges is used, then the machining process is simple and uniform grooves are formed, but the sliding surface geometry is flat and cannot compensate for shaft bending or tilting under load
Solution Approach 1:
The cutting cartridge is made adjustable in the axial direction through a piezo element actuator, transforming it from a fixed to a dynamic component. This allows the cutting depth and sliding surface geometry to be varied during machining to create convex curves that compensate for shaft bending and tilting under load
Solution Approach 2:
The piezo element changes the axial position parameter of the cutting cartridge dynamically during the machining process. This parameter change enables the creation of non-uniform sliding surface profiles with convex curves at edge regions, improving lubrication and compensating for operational deformations
2Reliability
If uniform groove profiling is formed on the sliding surface, then the machining process is straightforward, but wear resistance decreases and oil losses increase due to poor lubricating film build-up
Solution Approach 1:
The sliding surface is given different geometries at different locations: convex curves are created at the edge regions while the central region maintains a different profile. This local differentiation improves lubricating film build-up at critical edge areas, enhancing wear resistance and reducing oil losses without requiring complete redesign of the entire sliding surface
3Reliability
If exposed regions are not formed, then the bearing shell maintains uniform wall thickness, but imprecisions at connection sites cause shaft bending and tilting that increase wear
Solution Approach 1:
Exposed regions are pre-formed at the ends of the bearing shell during the drilling out process. These regions compensate in advance for the effects of connection site imprecisions, reducing shaft bending and tilting under load before the bearing enters service, thereby improving running properties and reducing wear
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 solution improves wear resistance and running properties by optimizing the sliding surface geometry, reducing oil losses and compensating for minimal shaft bending or tilting, thereby enhancing operational performance with a single machining step.
Implementation Method 1
The cutting cartridge (21) is braced against a piezo element (24). By means of a corresponding actuation of the piezo element (24), this element expands and thus changes the position of the cutting cartridge (21)
Data Source
AI summary
The invention relates to a tool for machining sliding surfaces of a bearing shell (30), comprising a rotary drive for driving a drilling spindle (20) that can be rotated about a rotational axis and at least one first cutting cartridge that is mounted on the drilling spindle (20) in order to cut the bearing shell (30) to a certain wall thickness by rotating the drilling spindle (20). The tool is characterized in that the first cutting cartridge can be adjusted by an adjustment means in a direction of adjustment that has a component in the radial direction of the drilling spindle, while the drilling spindle (20) is rotated by the rotary drive. The invention further relates to a bearing shell (30) comprising a deliberately structured sliding surface (31) and to a method for producing a bearing shell (30) comprising a deliberately structured sliding surface (31).