Segmented Step Drill Cutting Edges for Lower-Force Drilling
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Solution Overview
Problem
Traditional step drills experience issues with large cutting forces, insufficient sharpness, difficult chip breaking, high cutting heat, and low processing efficiency due to their design.
Innovation Solution
The step drill features multiple flutes forming cutting edges with a multi-segment structure, where each cutting edge is composed of two or more segments with different lengths and angles, allowing for a compound cutting effect that decomposes the cutting force and disperses heat, reducing the cutting force required and improving cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional step drill with single-segment cutting edges is used, then the structure is simple, but the cutting force is large and processing efficiency is low
Solution Approach 1:
The cutting edge is divided into multiple segments (first cutting edge segment and second cutting edge segment) with different entering/auxiliary angles. This segmentation allows the cutting force to be distributed across multiple cutting zones, reducing the peak cutting force and improving chip evacuation, thereby resolving the contradiction between processing efficiency and structural complexity.
Solution Approach 2:
Different segments of the cutting edge are designed with different local properties (different entering/auxiliary angles) to optimize cutting performance at various positions. The first segment has one set of angles for initial cutting, while the second segment has different angles for finishing, allowing each local region to perform its specific function optimally.
2Manufacturing precision
If traditional step drill with symmetric cutting edges is used, then the manufacturing is simple, but the cutting sharpness is insufficient
Solution Approach 1:
The cutting edge is designed with asymmetric segments where the first and second cutting edge segments have different entering/auxiliary angles. This asymmetry creates sharper cutting action by optimizing the angle of attack at different positions, improving cutting sharpness while the overall structure remains manufacturable through standard drilling processes.
3Ease of operation
If traditional step drill with single cutting edge is used, then the structure is simple, but chip breaking is difficult
Solution Approach 1:
The segmented cutting edge creates multiple cutting zones that naturally break chips into smaller pieces as they pass through different segments. The variation in entering/auxiliary angles between segments disrupts continuous chip formation, making chip breaking easier and improving chip evacuation from the cutting zone.
4Temperature
If traditional step drill with conventional cutting edges is used, then the design is simple, but cutting heat is high
Solution Approach 1:
The segmented cutting edge with different angles distributes the cutting action across multiple zones, reducing the concentration of heat generation in a single location. This segmentation allows for better heat dissipation and reduced peak temperatures, addressing the cutting heat issue while maintaining a relatively simple overall structure.
Data Source
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Figure 5~6
AI summary
The present invention relates to a step drill (1), characterized in that the step drill has a hole processing portion (2, 3) and at least two flutes (5, 5) extending on the hole processing portion, the hole processing portion comprising step sections (Tn), each step section and the at least two flutes forming at least two cutting edges (An, An') distributed in a circumferential direction of the step section, wherein, the at least two cutting edges on at least one of the step sections at least comprise a first cutting edge (An) and a second cutting edge (An'), wherein the first cutting edge and the second cutting edge are respectively constructed in at least two-segment style, and therefore respectively include at least two cutting edge segments, wherein the first cutting edge and the second cutting edge are at least partially different from each other in the structure of their cutting edge segments, or one cutting edge of the first cutting edge and the second cutting edge is formed in one-segment style, while the other cutting edge is formed in at least two-segment style, and thus includes at least two cutting edge segments. The present invention further relates to a method for drilling a workpiece by using a step drill.