Ledeburitic Gray Cast Iron Piston Ring for Flank Wear Resistance
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Solution Overview
Problem
Large-piston engine piston rings face significant wear on both the ring running surface and flanks, leading to reduced sealing effectiveness and increased maintenance costs due to frictional wear, with existing wear-resistant coatings and methods not adequately addressing the tribological properties required for long-term operation under high loads.
Innovation Solution
A piston ring design featuring a partially remelted ledeburitic gray cast iron structure on the flanks and a wear protection layer on the ring running surface, where the ledeburite structure is created by surface heating and self-quenching, combined with a thermally sprayed or PVD/DLC coating to enhance wear resistance and sealing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hardening or chrome plating is applied to the ring flanks, then wear resistance of the flanks is improved, but the overall tribological properties and sealing effectiveness are not sufficiently enhanced for long-term operation
Solution Approach 1:
The patent applies laser surface remelting to fundamentally change the microstructure of the ring flank surface, transforming it into a ledeburitic structure with superior hardness and wear resistance. This parameter change in the material structure provides enhanced protection that maintains sealing effectiveness over extended operation periods, addressing the insufficiency of conventional hardening and chrome plating methods.
2Strength
If conventional wear-resistant coatings are applied, then some wear protection is achieved, but the tribological properties required for long-term operation under high loads are not adequately addressed
Solution Approach 1:
The patent utilizes laser-induced phase transition to remelt the surface layer of the ring flank, creating a completely new ledeburitic microstructure. This phase transition process transforms the original material structure into a harder, more wear-resistant state that can withstand high loads during long-term operation, thereby adequately addressing the tribological properties requirement.
Solution Approach 2:
The patent creates a composite structure by forming a ledeburitic surface layer on the ring flank through laser remelting. This composite material structure combines the base material with a hardened surface layer, providing both the toughness of the underlying material and the superior wear resistance of the ledeburitic surface, thus achieving the required tribological properties under high loads.
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 provides improved wear resistance and sealing effectiveness by combining the toughness of gray cast iron with the hardness of ledeburite, reducing wear and corrosion, and ensuring prolonged operational reliability with minimal maintenance.
Implementation Method 1
the ledeburite structure is created by first heating the surface of the ring body at the appropriate points in order to partially melt it and then waiting until the material cools down again. Since the ring body is only melted on the surface, but is still cool and solid on the inside, 'self-quenching' takes place
Implementation Method 2
a ledeburitic structure (ledeburite structure) consisting of iron and iron carbide (Fe 3 C, cementite), so-called white cast iron. The ledeburitic structure has a higher hardness than gray cast iron and is therefore subject to less wear
Implementation Method 3
The wear protection layer is in the form of a thermally sprayed layer
Implementation Method 4
a wear protection layer (6), in particular a PVD layer, on the ring running surface (10)
Data Source
Figure 1~2
Figure 3A~3D
Figure 3E~3G
AI summary
The invention relates to a piston ring, having a ring body (14) of gray cast iron, which has a region of ledeburite microstructure (4) on at least one ring flank (8), which region of ledeburite microstructure extends to the ring running-surface edge and extends into the ring running surface (10), wherein an anti-wear layer (6) is applied to the ring running surface (10), which anti-wear layer also covers the region of ledeburite microstructure (4). The invention further relates to a method for producing such a piston ring.