Miniature Drill with Segmented Chip Slots for PCB Precision
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Solution Overview
Problem
Existing miniature drills for printed circuit boards suffer from centroid deviation at the drill tip, leading to inaccurate hole positioning and reduced anti-break performance due to offsetting of cutting edges or changing helix angles, causing the drill tip to swing violently during high-speed rotation.
Innovation Solution
A miniature drill design featuring a drill body with a drill tip having two main cutting edges and two auxiliary cutting edges, where a long chip slot and a short chip slot with the same helix angle are connected by a communicating slot, ensuring symmetrical force distribution and reducing centroid deviation from the rotation axis, thereby enhancing position accuracy and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the two spiral slots are made to intersect by increasing or reducing the helix angles, then the chip slots can be made to intersect, but the centroid of the drill tip near the intersection portion becomes offset from the rotation axis, causing the drill tip to swing violently during high-speed rotation
Solution Approach 1:
The patent applies asymmetry by making the two spiral slots have different lengths (one long chip slot and one short chip slot) while maintaining the same helix angle. This asymmetric design allows the slots to be communicated without intersecting, thereby avoiding centroid offset while still achieving effective chip removal. The asymmetry in slot length resolves the contradiction by preventing the harmful intersection effect while maintaining manufacturing feasibility.
Solution Approach 2:
The patent introduces a new dimensional approach by adding a communicating slot that connects the long and short chip slots in a third spatial dimension. Instead of simply intersecting the two main slots in the plane, the communicating slot provides an additional pathway that allows chip evacuation without requiring the main slots to intersect, thus maintaining centroid alignment while achieving chip removal functionality.
2Productivity
If the two spiral slots are made to intersect, then chip removal is facilitated, but the drill tip swings violently due to centroid deviation, affecting position accuracy and anti-break performance
Solution Approach 1:
The patent segments the chip removal pathway into three distinct parts: a long chip slot, a short chip slot, and a communicating slot connecting them. This segmentation allows chips to be removed through multiple pathways without requiring the main cutting edges to intersect. The long and short slots handle different portions of chip evacuation, while the communicating slot provides additional relief, achieving effective chip removal without compromising drill tip stability or anti-break performance.
3Device complexity
If a single cutting edge is used, then the structure is simpler, but the wear resistance is lower and hole roughness is worse compared to multiple cutting edges
Solution Approach 1:
The patent merges two cutting edges into a single drill tip structure, with each cutting edge having its own chip slot (long and short slots). This combination allows both cutting edges to work simultaneously, sharing the cutting load and improving wear resistance. The merged structure also enables balanced force distribution during cutting, reducing radial forces and improving hole roughness, while the communicating slot ensures both edges remain effective by preventing chip clogging.
Data Source
AI summary
The present invention relates to the field of manufacture of miniature drills and discloses a miniature drill, which includes a drill body, a drill tip formed at one end of the drill body, and a plurality of spiral chip slots spiraling on a surface of the drill body; the chip slots include a long chip slot, a short chip slot, and a communicating chip slot, the long chip slot and the short chip slot are arranged at intervals and have the same helix angles, and the long chip slot is communicated with the short chip slot by the communicating slot. In the miniature drill provided by the present invention, the long chip slot and the short chip slot that have the same helix angle and do not intersect are communicated with each other by the communicating slot, which effectively avoids swing of the drill tip caused by deviation of the centroid from the rotation axis and affecting the position accuracy of the drilled holes; moreover, the communicating slot broadens the widths of the chip slots, increases the chip space, and thereby improves the heat dissipating property; furthermore, the communicating slot reduces the width of the body clearance and reduces heat generated by friction between the body clearance and walls of the drilled holes, which enhances the ability of resisting breaks caused by the thermal deformation of the miniature drill.