Double-Margin Drill Geometry for Earlier Minor Margin Support
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing two-edge double margin drills with web thinning surfaces that extend to the outer peripheries of lands face challenges in maintaining an optimal interval between major and minor margins, leading to delayed minor margin entry and reduced drilling precision, especially during high-feed drilling due to web thinning and conical flank faces.
Innovation Solution
A two-edge double margin drill design featuring flat first and second flank faces with R web thinning surfaces that extend to the outer periphery of the lands, setting the interval between major and minor margins from 80° to 100°, and optimizing clearance angles to prevent interference and facilitate chip evacuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If web thinning is performed to reduce thrust force, then cutting performance is improved, but the distance from major margins to minor margins in the axial direction becomes long
Solution Approach 1:
The patent applies R web thinning with a specific curvature radius (R5-R10) to modify the web thinning surface geometry. This parameter change allows the web thinning surface to extend to the outer periphery of the land while controlling the axial distance, enabling the minor margin to enter the hole earlier and reduce the guiding period compared to conventional X web thinning.
Solution Approach 2:
The patent uses curved R web thinning surfaces with specific radius of curvature instead of planar surfaces. This curvature allows the web thinning to extend radially to the land outer periphery while maintaining controlled axial positioning, enabling better chip evacuation and earlier minor margin engagement.
2Manufacturing precision
If the interval between major margin and minor margin is set to 90° for optimal guiding, then guiding function is maximized, but web thinning causes the minor margin position to recede
Solution Approach 1:
The patent sets the interval angle θ between major and minor margins within 80°-100° (optimally 85°-95°) and uses R web thinning with radius R5-R10. These parameter changes ensure the minor margin is positioned to enter the hole earlier, reducing the guiding period while maintaining effective guiding function through the four-point support mechanism.
3Productivity
If web thinning surfaces extend to outer peripheries of lands, then chip evacuation is improved, but the position of minor margin ends recedes
Solution Approach 1:
The patent specifies R web thinning with radius R5-R10 and extends the web thinning surface to the outer periphery of the land. This parameter configuration allows chips to be smoothly guided to the helical flute without causing the minor margin end to recede, achieving both good chip evacuation and precise margin positioning.
4Ease of manufacture
If conventional web thinning is used, then manufacturing is simpler, but chip clogging occurs in narrow pockets
Solution Approach 1:
The patent uses R web thinning with specific curvature radius (R5-R10) that creates wider chip pockets at the outer periphery of the land. This curved geometry allows chips to be smoothly evacuated without clogging while remaining manufacturable through conventional web thinning processes.
Data Source
Figure 1~2
Figure 3~4
Figure 5~6A
AI summary
The present invention addresses the problem of making it possible to shorten as much as possible the distance from a major margin to a minor margin of a two-edge double margin drill in an axial direction and to keep the interval between the major margin and the minor margin within an ideal range. An interval (θ) between major margins (6) and respective minor margins (7), which are provided at outer peripheries of lands (5), are set at 80° to 100°, flank faces (8) both include a flat second flank face (8a) and a flat third flank face (8b), web thinning portions (4) including web thinning surfaces (4a) having convex arcs in a direction of drill rotation in front view of the drill are formed at a central portion of an end, and an outer end of each web thinning surface (4a) in a radial direction is disposed behind an end of the corresponding minor margin (7) in the direction of drill rotation and extends to the outer periphery of the corresponding land.