Indexable Drill Inner Blade Geometry for Radial Force Balance
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Solution Overview
Problem
Indexable drilling tools face challenges in achieving radial force balance between inner and outer blades, leading to cutting vibrations, poor machining surface quality, and reduced dimensional accuracy due to asynchronous wear and differences in cutting edge structures and angles.
Innovation Solution
The design features a cutter body with symmetric shank and peripheral surfaces, central and circumferential grooves, and inner and outer blades with specific cutting edge configurations and dimensions that ensure radial force balance, allowing the inner blade to achieve balance independently of its cutting edge shape and angle, thus simplifying mounting dimensions and maintaining stability despite asynchronous wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner blade and outer blade have different structures or identical structure with different mounting dimensions to meet different cutting conditions, then wear resistance and impact resistance can be improved, but radial force balance is compromised leading to cutting vibration
Solution Approach 1:
The patent applies asymmetry by designing the inner blade and outer blade with different geometric parameters (different mounting angles, different rake angles, different cutting edge shapes) to optimize their respective cutting conditions. The inner blade has a first mounting angle and first rake angle, while the outer blade has a second mounting angle and second rake angle, allowing each blade to be asymmetrically optimized for its specific cutting requirements while maintaining overall radial force balance through careful parameter selection.
2Reliability
If the inner blade and outer blade are mounted independently on the cutter body, then wear resistance and impact resistance can be improved, but it becomes difficult to balance radial cutting force
Solution Approach 1:
The patent employs parameter changes by systematically adjusting multiple geometric parameters of the inner and outer blades including mounting angles, rake angles, cutting edge shapes, and blade thicknesses. By changing these parameters within specific ranges and relationships, the patent achieves radial force balance while maintaining the independent mounting structure that provides wear and impact resistance.
3Productivity
If the inner blade and outer blade have different cutting edge shapes, cutting angles, mounting angles and rake angle, then cutting performance can be optimized, but it becomes very difficult to realize radial force balance in actual machining
Solution Approach 1:
The patent applies local quality by optimizing specific geometric parameters at different locations and for different blades. The inner blade has specific mounting angles and rake angles optimized for central area cutting, while the outer blade has different parameters optimized for peripheral cutting. Each blade's geometry is locally optimized for its specific cutting zone while the overall system maintains radial force balance through coordinated parameter selection.
Data Source
AI summary
An indexable drilling tool, includes a cutter body, an outer blade and an inner blade. The inner blade is surrounded by a first upper surface, a first lower surface and a first side surface. The first upper surface intersects with the first side surface to form multiple identical inner cutting edges. When drilling, a cutting area of the inner cutting edge as a main cutting edge is located between a central inner point and a central outer point on the inner cutting edge. In a feed direction, an inner convex cutting portion with a maximum cutting depth is arranged between the central inner point and the central outer point. Distances between the central inner point and the inner convex cutting portion and between the central outer point and the inner convex cutting portion in an axial direction are H1 and H2 respectively, which meets the following requirement: 0.9H2≤H1≤1.1H2.