Step Drill Reaming Geometry for Ribbon Chip Breaking
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Solution Overview
Problem
Conventional step drills produce long ribbon chips during machining of metallic materials, which can wrap around the drill and cause damage due to their length.
Innovation Solution
A step drill with a chip-breaking geometry featuring a concavely curved surface on the reaming step, designed to break the chips before they reach a critical length, comprising multiple curved sections with varying radii and a depression in the flute surface to align and deflect the chips effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional step drill geometry is used, then the drill can maintain simple structure and manufacturing, but long ribbon chips are formed that wrap around the drill and cause damage
Solution Approach 1:
The patent applies a concavely curved surface on the reaming step of the step drill. This curved geometry causes the ribbon chips to curl as they are transported along the flute, preventing them from reaching the critical length that would cause wrapping around the drill. The curvature transforms the linear chip path into a curved trajectory, effectively breaking the chips without adding complex structures.
Solution Approach 2:
The reaming step is divided into different surface sections: a conically curved section for initial chip guidance, a cylindrically curved section for chip curling, and a flat section for chip breaking. This segmentation of the reaming step into functional zones allows each section to perform a specific chip control function, effectively preventing chip wrapping while maintaining overall structural simplicity.
2Object-affected harmful factors
If chip-breaking geometry with concavely curved surface is added, then ribbon chips are broken and wrapping is prevented, but the drill geometry becomes more complex
Solution Approach 1:
The reaming step serves multiple functions: it provides the final dimensional finish of the hole and simultaneously acts as the chip-breaking geometry. By combining these functions in a single structural element, the patent avoids adding separate chip-breaking components that would increase drill complexity. The multi-functional design achieves chip control without proportionally increasing structural complexity.
Solution Approach 2:
The chip-breaking geometry is localized specifically to the reaming step region where chips have already been transported a certain distance and are at a manageable size. The concave curvature is applied only where needed for chip control, while other parts of the drill maintain simple geometry. This localized application minimizes the overall complexity increase while achieving the desired chip-breaking effect.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents the formation of long ribbon chips by curling and breaking them on the concavely curved surface, ensuring they do not wrap around the drill and causing damage, while maintaining the drill's outer dimensions and cutting behavior.
Implementation Method 1
As the step drill rotates, for example, the ribbon chips curl on the concavely curved surface and are thereby broken
Data Source
AI summary
The invention relates to a step drill having a shaft section extending along a longitudinal axis of the step drill and a cutting section with a cutting tip, and having a chip-breaking geometry which comprises a concavely curved surface and is configured such that ribbon chips are broken on the concavely curved surface during rotation of the step drill, whereby the chip-breaking geometry is disposed on a reaming step of the step drill.