Drill Thinning Geometry Reduces Cutting Resistance
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Solution Overview
Problem
Conventional drills used for manual hole drilling, such as hand drills and drill presses, face high drilling resistance issues due to their design, which leads to increased operator strain and inefficiency, and existing thinning methods either fail to reduce resistance effectively or result in drill tip chipping.
Innovation Solution
A drill design featuring two symmetrical cutting blades with a thinning cutting blade extending from the chisel edge to the peripheral side, forming a u-shaped thinning surface, and a main cutting blade extending from the thinning cutting blade, where the rake angles satisfy θ1 > θ2 > 0°, with an offset extension line that does not cross the drill tip center, reducing drilling resistance and improving sharpness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If thinning is performed on the drill tip to reduce drilling resistance, then drilling resistance decreases, but the drill tip becomes fragile and prone to chipping
Solution Approach 1:
The patent applies different surface qualities to different regions of the drill tip. The thinning portion has a smooth surface with reduced material, while the peripheral portion maintains the original structure for strength. This local differentiation allows the thinning area to reduce drilling resistance while the stronger peripheral areas prevent tip chipping.
Solution Approach 2:
The drill tip is segmented into distinct functional zones: a thinning portion with reduced material for cutting, and a peripheral portion with full material for structural support. This segmentation allows each zone to perform its specific function optimally without compromising the overall integrity of the drill tip.
2Force
If conventional thinning is performed from central part to heel part, then drilling resistance is reduced, but the resistance reduction effect is insufficient for manual drilling operations
Solution Approach 1:
Instead of performing thinning across the entire drill tip surface, the patent applies thinning only to the specific portion that contacts the workpiece during drilling. This partial action is sufficient to reduce drilling resistance for manual operations without over-thinning the structure.
3Force
If the chisel width is narrowed to reduce drilling resistance, then drilling resistance decreases, but the drilling force of the central part becomes weak requiring significant operator power
Solution Approach 1:
The patent creates a local quality difference between the thinning portion and peripheral portion. The thinning portion has narrowed effective width for reduced resistance, while the peripheral portion maintains full width for structural support and cutting capability, balancing resistance reduction with operational ease.
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3(a)~3(b)
AI summary
This invention relates to a drill with a tip part on which thinning is performed, comprising two cutting blades, thinning cutting blade and a thinning cutting blade, which are formed symmetrical about an axis of rotation, which enables a great reduction in cutting resistance and easy performance of a drilling operation by human power using a hand drill, a drilling machine, or the like. The cutting edge is configured from a thinned cutting edge (1) which extends in a shape including a curved line from a chisel edge to the outer peripheral side of the drill, and a main cutting edge (2) which extends from the end of the thinned cutting edge to the outer peripheral end of the drill when viewed from the tip side of the drill, and a thinned surface formed by the thinned cutting edge is formed into an approximately parabolic shape inclined in a drill axis direction when viewed from the front side of the drill, wherein a rake angle (θ1) formed by said thinning cutting blade and a rake angle (θ2) formed by said thinning cutting blade satisfy θ1>θ2>0°, except for a part just below the chisel.