Multi-Stepped Drill Bit Tip for Lower Axial Force in Metal Drilling
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Solution Overview
Problem
Existing drill bits and pilot drill bits face challenges when forming holes in metal workpieces, including high axial force requirements, drill bit damage, and uncontrolled holesaw movement, which can lead to workpiece damage and user jolting.
Innovation Solution
A drill bit with a multi-stepped tip featuring axial and radial reliefs, where the rearmost step has a greater axial relief, is designed to reduce axial force, prevent drill bit sticking, and improve cutting speed and life, and can be used alone or as a pilot drill bit with a holesaw to prevent uncontrolled contact and damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a single-step pilot tip is used to drill pilot holes, then the drill bit can penetrate the workpiece, but a large amount of axial force is required which causes the holesaw to slam into the workpiece, jolting the user and potentially damaging the teeth, pilot bit, and workpiece
Solution Approach 1:
The pilot tip is segmented into multiple steps (first step, second step, third step) with progressively larger diameters. Each step engages the workpiece at a different stage of penetration, distributing the cutting action and reducing the peak axial force required. This segmentation prevents the sudden slam that occurs with single-step tips while maintaining effective pilot hole formation.
Solution Approach 2:
The invention changes the geometric parameters of the pilot tip by creating multiple steps with different diameters and axial positions. The first step has a smaller diameter and engages first, the second step has an intermediate diameter, and the third step has the largest diameter. This parameter variation allows progressive engagement with the workpiece, controlling the cutting force profile and preventing excessive axial force application.
2Ease of operation
If axial force is applied to make the pilot bit penetrate through the workpiece, then the pilot hole is formed, but the holesaw may walk from the center, mar the workpiece, and break or bend the pilot drill bit
Solution Approach 1:
The multi-stepped configuration segments the cutting action into progressive stages. Each step engages the workpiece material in sequence, providing gradual guidance and centering of the holesaw. This prevents sudden lateral movements (walking) that occur when a single-step tip suddenly penetrates, thereby protecting the workpiece from marring and the drill bit from breaking or bending.
Solution Approach 2:
The multiple steps act as a cushioning mechanism before the full diameter of the holesaw engages the workpiece. The progressive engagement of steps with increasing diameter provides a controlled transition that cushions against sudden impacts and lateral forces, preventing damage to the workpiece and drill bit assembly.
3Productivity
If a multi-stepped tip with multiple steps is used, then axial force is reduced and cutting performance is improved, but the device complexity increases
Solution Approach 1:
The pilot tip is divided into multiple stepped sections (first step, second step, third step) with progressively larger diameters. Each step provides cutting action at a different stage of penetration, improving cutting performance and reducing axial force requirements. The segmented structure is manufactured as an integrated component, balancing complexity with manufacturing efficiency.
Data Source
AI summary
A drill bit includes a shank, an intermediate portion with a helical flute, and a multi-stepped tip portion extending along the axis. The tip portion includes a cutting tip with a pair of primary cutting edges extending radially outward from the axis, a plurality of steps each having an elongated portion and a tapered portion tapered outward from the elongated portion relative to the axis. The elongated portions progressively increase in diameter from the cutting tip to the intermediate portion. The elongated portion of each step has an axial relief tapered inward toward the axis. A frontmost elongated portion has a first axial relief at a first angle relative to the central axis and a rearmost elongated portion has a second axial relief at a second angle greater than the first angle. The drill bit may be used as a pilot bit together with a holesaw in a system.