Solid Step Drill Chip Breaking Recess Design
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Solution Overview
Problem
Solid step drills face challenges in achieving high precision and efficient chip formation and evacuation, especially when dealing with long-chipping materials, due to unpredictable chip conditions and potential for chip jamming, which affects hole quality and precision.
Innovation Solution
A solid step drill design featuring concentric cylindrical sections with primary and secondary cutting edges, where a chip breaking recess is formed adjacent to the secondary cutting edge to control chip direction and breakage before it enters the chip flute, optimizing chip formation and evacuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a solid step drill is used to ensure high precision hole making, then manufacturing precision is improved, but chip evacuation becomes problematic due to long chip formation and potential jamming
Solution Approach 1:
The chip flute is segmented into multiple sections with different geometries. The first section has a narrower width suitable for initial chip formation, while the second section has a wider width to accommodate and evacuate long chips effectively. This segmentation allows the drill to maintain precision while solving chip evacuation problems.
Solution Approach 2:
Different sections of the chip flute are given different local qualities - the first section has specific geometric characteristics for precise chip formation near the cutting edge, while the second section has modified geometry (wider width, different angle) optimized for chip evacuation. This local differentiation resolves the contradiction between precision and chip management.
2Manufacturing precision
If the chip flute is countersunk in both first and second sections to ensure proper chip formation, then chip surface area is improved, but the complexity of the drill structure increases
Solution Approach 1:
The chip flute is designed as a continuous, integrated structure that spans both the first and second sections of the drill. This merging of the chip flute across different diametric sections simplifies the overall structure compared to having separate chip evacuation systems for each section, while still providing the necessary geometric variations for proper chip formation and evacuation.
3Productivity
If secondary cutting edges are formed at the step to enable multi-diameter hole making, then productivity is improved, but unpredictable chip conditions arise affecting hole quality
Solution Approach 1:
The chip flute geometry is designed in advance to anticipate and accommodate the different chip conditions that will arise at each cutting edge. The first section handles chips from the primary cutting edge, while the second section is pre-configured with wider geometry to handle chips from the secondary cutting edge at the step, ensuring consistent hole quality across multiple diameters.
Data Source
AI summary
A solid step drill, including a front tip and a rear end between which a center axis extends and around which the drill is rotatable in a predetermined direction. At least two cylindrical sections are concentric with the center axis, a first section extending rearward from the front tip and having a first diameter, and a second section extending behind the first section and having a second diameter that is greater than the first diameter, the first section transforming into the second section via a step. The tip includes two primary cutting edges, which individually co-operate with a respective chip flute that is delimited by a concave surface and countersunk in the first section and in the second section, the respective chip flute intersecting the step while forming a secondary cutting edge. Adjacent to the secondary cutting edge, a chip breaking recess is formed between a cutting edge line of the cutting edge and the concave surface.