Connecting Rod Laser Groove Cracking for Smoother Reassembly
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Solution Overview
Problem
The existing methods for cracking connecting rods in internal combustion engines often result in defective reassembly due to inadequate stress concentration factors, leading to rough mating surfaces and reduced longevity.
Innovation Solution
A two-pass laser method is employed to etch a groove in the connecting rod's inner surface, increasing the stress concentration factor by varying the depth of holes along the groove, thereby ensuring smoother cracking surfaces and improved reassembly quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single-pass laser method is used to etch a groove in the connecting rod, then the process is simpler and faster, but the stress concentration factor is insufficient resulting in rough mating surfaces and defective reassembly
Solution Approach 1:
The laser etching process is divided into two distinct passes: a first pass that creates an initial groove with moderate depth, and a second pass that deepens the groove to achieve the required stress concentration factor. This segmentation allows each pass to be optimized for its specific function, resulting in superior surface finish quality while maintaining process control
Solution Approach 2:
The first laser pass performs a preliminary etching action that creates a foundational groove structure. This preliminary groove serves as a base for the second pass, allowing the final deepening operation to achieve the target stress concentration factor more effectively and produce smoother mating surfaces
2Manufacturing precision
If a deeper groove is etched to increase the stress concentration factor, then the cracking quality improves, but the cracking load required increases
Solution Approach 1:
The laser etching process concentrates material removal locally at the groove bottom and along the groove walls, creating a highly localized stress concentration zone. This localized quality enhancement achieves precise cracking line formation with improved crack propagation control while managing the required cracking load through optimized groove geometry rather than uniform deepening throughout
3Manufacturing precision
If the laser removes more material to increase groove depth, then the stress concentration factor increases, but material waste increases
Solution Approach 1:
The two-pass laser method removes material in controlled increments rather than attempting to achieve the final depth in a single aggressive pass. The first pass removes a partial amount of material to create the initial groove, and the second pass removes additional material to reach the target depth. This partial action approach minimizes material waste by avoiding excessive removal and allows for better control of the final groove dimensions
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 two-pass laser method reduces the cracking load, minimizes chipping, and decreases surface roughness, resulting in higher quality cracked components with improved fitment during reassembly.
Implementation Method 1
etching, using a first pass of a laser, a groove in an inner surface of a larger bore of a connecting rod by removing material from the inner surface
Data Source
AI summary
A method for creating a cracking line in a connecting rod includes etching, using a first pass of a laser, a groove in an inner surface of a larger bore of a connecting rod by removing material from the inner surface. The groove may be discontinuous and include a plurality of holes that are spaced apart and have different depths. The method further includes removing more material from the groove using a second pass of the laser to increase the depths of the holes, thereby increasing the stress concentration factor of the groove.