Spiral Step Twist Drill Bit for Chip Removal and Precision Drilling
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Solution Overview
Problem
Conventional step twist drill bits with parallel steps suffer from machining overlap, reduced cutting efficiency, and chip retention issues, leading to decreased drilling precision and increased power requirements.
Innovation Solution
A spiral step twist drill bit design featuring a spiral flute, varying pitch spiral cutting groove, and spiral chip removal groove that divides the cutting edge into segments and flank surfaces, enhancing chip discharge and reducing machining overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If parallel steps are used in conventional step twist drill bits, then positioning during layered drilling is easy, but machining overlap occurs and cutting efficiency is reduced
Solution Approach 1:
The patent applies spiral curvature to the step surfaces, transforming the conventional parallel stepped structure into a spiral form. The spiral step surface is defined by a spiral line generated by rotating a straight line around the drill axis, which eliminates machining overlap and improves chip discharge while maintaining positioning capability during layered drilling.
2Manufacturing precision
If parallel steps with perpendicular step surfaces are used, then drilling precision is maintained, but cutting chips are held at the step surfaces affecting subsequent processing
Solution Approach 1:
The step surfaces are designed with spiral curvature instead of being perpendicular to the drill axis. This spiral configuration allows cutting chips to be naturally guided away from the step surfaces during rotation, preventing chip accumulation and its harmful effects on subsequent drilling operations.
Solution Approach 2:
The invention introduces a spiral dimension to the step surfaces, transforming them from two-dimensional flat surfaces perpendicular to the axis into three-dimensional spiral surfaces. This dimensional change creates a self-cleaning effect where chips are naturally ejected along the spiral path rather than being trapped on flat surfaces.
3Device complexity
If conventional twist drill with symmetric cutting edges is used, then structural simplicity is maintained, but larger power is required and edges are prone to damage
Solution Approach 1:
The cutting edge is segmented into multiple sections along the spiral flute, with each section having its own cutting action. This segmentation distributes the cutting load across multiple smaller cutting zones rather than one large cutting edge, reducing the power required and decreasing stress on individual cutting points.
Solution Approach 2:
The spiral step structure creates periodic cutting actions as different sections of the segmented cutting edge engage with the workpiece in sequence during rotation. This periodic engagement reduces the instantaneous power requirement and prevents overload on any single cutting point.
Data Source
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Figure 3~4
AI summary
A spiral step twist drill bit, including a shank and a cutting portion. The cutting portion is provided with a spiral flute and a body clearance. A tip of the cutting portion is provided with a chisel edge and a cutting edge. A flank face is connected to the cutting edge, and is provided with a spiral cutting groove. A spiral direction of the spiral cutting groove is the same as that of the spiral flute. A slope of the spiral cutting groove is the same as that of the flank face. The spiral cutting groove is configured to divide the cutting edge into multiple segments to form multiple first edges and second edges.