Boring Tool Cutting Edge Geometry for Hard Material Drilling
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Solution Overview
Problem
Drilling tools face significant challenges when processing hard, abrasive materials like iron cast materials, particularly due to high loads on the main cutting edge and cutting corner, which lead to reduced tool life and increased wear.
Innovation Solution
The drilling tool features a main cutting edge that transitions into a circumferential cutting edge with a defined free angle, allowing for a pre-cutter action on a smaller diameter before switching to a guide chamber with a round cut to achieve the drilling diameter, thereby reducing loads and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the main cutting edge is extended through a curved path to reduce load per unit length, then the robustness of the main cutting edge is improved, but the complexity of the cutting edge geometry increases
Solution Approach 1:
The cutting edge is segmented into distinct functional zones: a main cutting edge zone for initial material removal, a transition zone with gradual curvature change, and a peripheral cutting edge zone. This segmentation allows each zone to be optimized independently while maintaining overall robustness without excessive geometric complexity.
Solution Approach 2:
The cutting edge employs a controlled curved path with specific radius parameters (R1, R2, R3) that provide smooth transitions between zones. The curvature is optimized to distribute loads evenly along the cutting edge while maintaining manufacturability through standard grinding processes.
2Object-generated harmful factors
If the peripheral cutting edge is designed with a clearance angle grind, then friction and cutting forces are reduced, but the manufacturing precision of the cutting edge geometry becomes more difficult to control
Solution Approach 1:
The peripheral cutting edge features a localized clearance angle grind (5°-15°) applied only to specific segments of the cutting edge, while other regions maintain different surface characteristics. This local treatment reduces friction and cutting forces in critical areas without compromising overall geometric precision through excessive grinding.
Solution Approach 2:
The clearance angle parameter is optimized to a specific range (5°-15°) that balances friction reduction with manufacturability. This parameter change allows the cutting edge to achieve lower cutting forces while remaining compatible with standard precision grinding capabilities.
3Reliability
If the guide chamfer is offset by a small angle from the first chamfer, then the support of the drilling tool is improved, but the auxiliary chip groove space is reduced
Solution Approach 1:
The guide chamfer is offset by a moderate angle (20°-40°) that provides sufficient support to the drilling tool during operation. This partial offset is optimized to achieve the minimum necessary support while preserving adequate space for the auxiliary chip groove, avoiding excessive offset that would compromise chip removal capability.
Solution Approach 2:
The offset angle between the guide chamfer and first chamfer is optimized to create an effective three-dimensional chip groove geometry. This angular arrangement in the radial dimension provides both structural support and adequate chip evacuation space without requiring increased axial or circumferential dimensions.
4Force
If the main cutting edge merges into the peripheral cutting edge along a transition zone, then the load distribution is improved, but the manufacturing complexity of the cutting edge increases
Solution Approach 1:
The transition zone between main and peripheral cutting edges employs a controlled curved path with specific radius parameters (R1, R2, R3) that provide smooth load distribution. The curvature is optimized to eliminate stress concentrations while maintaining compatibility with standard precision grinding processes, balancing load distribution improvement with manufacturing feasibility.
Data Source
Figure 1~3b
Figure 4~5
AI summary
Drilling tool comprising: - a drill longitudinal axis (L) about which the drilling tool (1) is rotatable in a direction of rotation (R) and along which drill longitudinal axis (L) a fluted length (LN) extends, - at least two main cutting edges (2) and at least two peripheral cutting edges (3), wherein one main cutting edge (2) transitions into a peripheral cutting edge (3) along a transition region (9), - at least two flutes (4), each flute (4) being spaced apart from a web (5), - a cutting back (6) formed on a cylindrical surface of a web (5), wherein along the fluted length (LN) at least partially - a first chamfer (7) with a clearance angle is formed on the peripheral cutting edge (3), which peripheral cutting edge (3) is formed on a first diameter (D1), which first diameter (D1) is smaller than the drill diameter (D), - on the cutting back (6) with respect to the direction of rotation (R) after the first chamfer (7) a Drill diameter (D) determining,A guide chamfer (8) offset at an angle of 20° to 40° from the first chamfer (7) is formed with a circular grinding, wherein an auxiliary clamping groove (10) is formed in front of the guide chamfer (8) with respect to the direction of rotation (R).