Polycrystalline Diamond Bit Holder with Steel Insert for Road Milling
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Solution Overview
Problem
Existing road milling bits and bit holders, even those with polycrystalline diamond tips, are not sturdy enough to effectively degrade both macadam and concrete roadways, particularly in curved sections, due to the brittleness of the diamond tips and the harsh operating environment.
Innovation Solution
A unitary bit and bit holder combination featuring a polycrystalline diamond tip with a sturdy bit holder design, including an elongate hollow cylindrical shank with internal slots and a tungsten carbide ring for added strength, allowing the bit to withstand the forces required for degrading concrete surfaces, and a flat puck-shaped tip for enhanced durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If polycrystalline diamond tips are used to extend service life, then the useful life of the bit is lengthened, but the tip becomes too brittle to withstand forces when degrading concrete roadways or curved sections
Solution Approach 1:
The bit holder is divided into distinct material zones: a polycrystalline diamond tip for cutting, a tungsten carbide collar for structural support and impact resistance, and a steel body for overall strength. This segmentation allows each material to perform its optimal function while working together as a unified tool.
Solution Approach 2:
The invention employs a composite structure combining multiple materials with different properties: polycrystalline diamond (extreme hardness for cutting), tungsten carbide (high strength and toughness for withstanding impacts), and steel (ductility and overall structural integrity). This composite approach resolves the contradiction by combining the hardness needed for longevity with the toughness needed for concrete degradation.
2Reliability
If traditional steel bits with hardened tungsten carbide tips are used, then they can withstand harsh environments, but they wear quickly and require frequent replacement
Solution Approach 1:
The bit holder combines polycrystalline diamond tip (superior hardness and wear resistance), tungsten carbide collar (impact and shock resistance), and steel body (structural strength). This composite structure provides both the reliability needed for harsh environments and the extended service life achieved through superior wear resistance of the diamond tip.
Solution Approach 2:
The invention changes the material parameters from traditional steel and tungsten carbide to include polycrystalline diamond, which has significantly higher hardness and wear resistance. This parameter change in material properties directly extends service life while maintaining reliability through the multi-material construction.
3Ease of repair
If bits are made removable from bit holders for easy replacement, then ease of replacement is improved, but the connection becomes a potential failure point in harsh road degrading environments
Solution Approach 1:
The bit and bit holder are merged into a unitary structure where the diamond tip, tungsten carbide collar, and steel body form an integrated assembly. This merging eliminates separate connection interfaces that could fail, while the modular design still allows for replacement of the entire bit holder assembly when worn.
Solution Approach 2:
The bit holder is designed with a standardized mounting interface that allows for preliminary installation and secure attachment before use. The friction fit and geometric constraints are built in advance to ensure reliable connection, eliminating the need for additional fastening operations during installation.
Data Source
AI summary
A quick change type bit/bit holder includes several different structures for holding the item in a bit block without the necessity of a fastener. The bit portion of the bit/bit holder combination includes a ductile steel insert with a polycrystalline diamond coated tungsten carbide bit positioned therein. The ductility of the steel insert acts as a shock absorber to allow the bit to successfully remove concrete as well as asphalt in a road milling machine.