Segmented Bore Drilling in Sintered Connecting Rods
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Solution Overview
Problem
The production of connecting rods with small connecting rod eyes is challenging due to inefficiencies in conventional heat-treating methods, leading to the industry's adoption of bores in the connecting rod shaft for lubricant passage, particularly in applications like compressors where bore diameters are less than 2 mm.
Innovation Solution
Introducing the bore into the green compact as first and second partial bores from the connecting rod foot and head, respectively, using shorter drills to improve precision and reduce thermal stress, with optional simultaneous drilling and the use of a clamping apparatus for better support and reduced material break-outs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a bore is introduced into the green compact using conventional single-sided drilling, then the bore can be produced, but the drill length increases causing bending and reduced precision
Solution Approach 1:
The bore production process is segmented into two separate drilling operations: first drilling from the connecting rod foot side to create a first partial bore, then drilling from the connecting rod head side to create a second partial bore that connects to the first. This segmentation allows the use of shorter drills for each operation, reducing drill bending and improving bore precision.
2Manufacturing precision
If a bore is introduced into the green compact using conventional single-sided drilling, then the bore can be produced, but the processing time increases causing excessive thermal stress on the green compact
Solution Approach 1:
The drilling process is segmented into two concurrent operations drilling from opposite sides simultaneously, which reduces the total processing time and thermal stress exposure while maintaining precision through shorter drill lengths.
Solution Approach 2:
Both partial bores are drilled simultaneously in one continuous operation rather than sequentially, maximizing productivity and reducing total processing time while the green compact remains in the pressing device for continuous support.
3Ease of manufacture
If a bore is introduced into the green compact, then lubricant passage is enabled, but thermal stress on the green compact increases during drilling
Solution Approach 1:
Segmenting the drilling into two shorter operations from opposite sides reduces the continuous thermal exposure time and allows better heat dissipation, lowering thermal stress on the green compact while still achieving the required lubricant passage.
Solution Approach 2:
Simultaneous drilling from both sides completes the lubricant passage faster, reducing total thermal stress exposure time while the green compact remains supported in the pressing device for optimal heat management.
4Manufacturing precision
If shorter drills are used for bore production, then precision improves and thermal stress reduces, but the bore must be produced as multiple partial bores
Solution Approach 1:
The bore is segmented into two partial bores drilled from opposite sides, which simplifies each individual drilling operation by using shorter drills that are less prone to bending, while the overall process complexity is managed through coordinated simultaneous execution.
Solution Approach 2:
The two drilling operations are merged into a single simultaneous process executed in one setup, which while requiring coordinated control, eliminates the need for repositioning and setup between operations, effectively managing the complexity.
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 method enhances precision and reduces thermal stress and processing time, allowing for more efficient production of bores with improved lubricant distribution and reduced scrap, particularly for small diameter bores commonly used in mass production.
Implementation Method 1
the powder is pressed into the corresponding mold to form a green compact
Implementation Method 2
the green compact is afterward sintered
Data Source
AI summary
A method produces a connecting rod from a sintered material, which rod has at least one bore having a center axis, and has a first connecting rod eye in a connecting rod head, and a second connecting rod eye in a connecting rod foot, wherein the connecting rod head is connected with the connecting rod foot with a connecting rod shaft, wherein the bore is configured in the connecting rod shaft, wherein furthermore, the connecting rod is produced from a metallic powder, in accordance with a sintering process, for which purpose the powder is pressed into the corresponding mold to form a green compact, the bore is introduced into the green compact, and the green compact is afterward sintered. The bore is introduced into the green compact as a first and second partial bore, proceeding from the connecting rod foot and from the connecting rod head.