PCD Tip with Alternating Stress Strata for Degradation Tools
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Solution Overview
Problem
Existing degradation tools, such as picks and percussion drills, face limitations due to the brittleness and reduced fracture resistance of synthetic diamond materials compared to cemented carbide, leading to a shorter working life.
Innovation Solution
A tip for degradation tools is developed, comprising a polycrystalline diamond (PCD) structure bonded to a cemented carbide substrate, with alternating strata of compressive and tensile residual stress states, directly intergrown for enhanced bonding, and varying thicknesses to oppose stress states, resulting in improved fracture resistance and extended tool life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If synthetic diamond material is used for the working tip, then abrasion resistance is improved, but fracture resistance deteriorates
Solution Approach 1:
The invention uses a composite structure combining polycrystalline diamond (PCD) material with cemented carbide substrate. The PCD layer provides superior abrasion resistance while the cemented carbide substrate provides fracture resistance and mechanical strength. This composite approach resolves the contradiction by combining materials with complementary properties rather than using pure synthetic diamond.
2Strength
If PCD material is used, then abrasion resistance is improved, but tool life deteriorates due to brittleness
Solution Approach 1:
The composite PCD-cemented carbide structure extends tool life by combining the abrasion-resistant PCD surface layer with the tougher cemented carbide substrate. The substrate prevents catastrophic failure when the PCD layer experiences stress, thereby extending the operational duration of the tool.
Solution Approach 2:
The invention applies different material properties to different regions: the PCD material is used specifically at the working surface where abrasion resistance is critical, while the cemented carbide substrate provides structural support and fracture resistance in the bulk material where toughness is more important.
3Ease of manufacture
If uniform PCD structure is used, then manufacturing is simplified, but stress distribution deteriorates under impact loads
Solution Approach 1:
The invention introduces deliberate local variations in the PCD structure, specifically creating layers with different diamond grain sizes and densities at specific locations (the working surface and transition zones). This non-uniform structure is strategically designed to manage stress distribution during impact loads, with finer grains near the surface for abrasion resistance and coarser grains deeper for stress management.
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 PCD structure with alternating stress states and varying thicknesses enhances the toughness and durability of the tool, leading to extended tool life and improved performance in degrading hard materials like asphalt and rock.
Implementation Method 1
the PCD structure comprising a plurality of strata arranged so that adjacent strata have alternating compressive and tensile residual stress states
Implementation Method 2
adjacent strata comprising different PCD grades and being directly bonded to each other by inter-growth of diamond grains
Data Source
AI summary
A tip for a degradation tool, the tip comprising a PCD structure joined to a cemented carbide substrate; the PCDstructure comprising a plurality of strata arranged so that adjacent strata have alternating compressive and tensile stress states, adjacent strata comprising different PCD grades and being directly bonded to each other by inter-growth of diamond grains; each stratum having a mean thickness of at most 500 microns; the PCD structure defining a working end including a rounded conical apex having a radius of curvature of 1.3 mm to 4 mm.