Rotary Drill Bit Cutting Insert T-Land Geometry
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Solution Overview
Problem
Current roof drilling bits in underground mining are inefficient, leading to increased hazards and longer completion times due to unsupported roof conditions during the bolting process, and have a limited useful life, necessitating improved designs for faster penetration and longer durability.
Innovation Solution
A two-prong rotary drill bit with cutting inserts featuring a specific geometry, including a T-land surface and negative axial rake angle, made from wear-resistant materials like cemented tungsten carbide, designed to reduce stress and prevent edge breakage, combined with advanced manufacturing processes to optimize cutting edge preparation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional roof drilling bits are used, then the drilling process can be completed, but the penetration rate is low and the useful life is limited
Solution Approach 1:
The patent applies parameter changes by modifying the cutting insert geometry parameters, specifically introducing a T-land surface configuration with optimized dimensions (T-land width, height, and angles) and a negative axial rake angle. These geometric parameter changes enhance the cutting edge's ability to penetrate rock while maintaining structural integrity, thereby increasing penetration rate and reducing drilling time
Solution Approach 2:
The patent employs composite materials by using cemented tungsten carbide as the cutting insert material. This composite material combines tungsten carbide particles with a metallic binder, providing both high hardness for effective cutting and sufficient toughness to resist edge breakage. The composite structure enables the cutting insert to maintain sharpness and durability throughout the drilling process
2Duration of action of stationary object
If conventional cutting insert geometry is used, then the drill bit can operate, but edge breakage occurs frequently reducing useful life
Solution Approach 1:
The patent changes the geometric parameters of the cutting insert by introducing a T-land surface with specific dimensional parameters (width, height, and angular relationships). The negative axial rake angle and optimized T-land configuration distribute stresses more evenly across the cutting edge, preventing stress concentration that leads to edge breakage. This geometric optimization extends the useful life of the drill bit while maintaining reliability
Solution Approach 2:
The use of cemented tungsten carbide composite material provides both hardness for cutting effectiveness and toughness for resistance to edge breakage. The composite structure allows the cutting insert to withstand the high stresses encountered during roof drilling without catastrophic failure, thereby extending useful life and improving reliability
3Productivity
If drilling is performed on unsupported roof, then bore holes can be created, but safety hazards increase due to roof instability
Solution Approach 1:
The patent applies preliminary action by designing a cutting insert geometry that prepares and conditions the cutting edge before actual cutting occurs. The T-land surface configuration and negative axial rake angle create a cutting edge that is pre-stressed and pre-conditioned to resist breakage during the initial penetration into the unsupported roof. This preliminary geometric preparation allows safe and efficient drilling in hazardous conditions
Solution Approach 2:
The T-land surface configuration acts as a stress-distributing structure that cushions the cutting edge against sudden impacts and loads. The geometric design provides a buffer zone that absorbs and distributes stresses before they reach the critical cutting edge, preventing catastrophic failure during drilling of the unsupported roof
Data Source
AI summary
A two-prong rotary drill bit for engaging an earth strata material includes a drill bit body having an axis of rotation, the drill bit body having a head portion at an axial forward end and a shank portion at an axial rearward end, the head portion having two mounting arms offset from the axis of rotation of the drill bit body. The two-prong rotary drill bit also includes a cutting insert attached to each mounting arm at the axial forward end of the drill bit body. Each cutting insert includes a leading face facing in the direction of rotation, a top surface having a relief surface, a T-land surface extending between the leading face and the relief surface of the top surface and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.