Replaceable Drill Connection Surface for Stress and Chip Control
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Solution Overview
Problem
Stress concentration at the ridgeline part of head replaceable type drills during cutting processes leads to fractures, as the direct connection between the flute and end surface concentrates stress, causing chipping and reduced durability.
Innovation Solution
The drill design incorporates a connection surface with varying lengths and shapes between the flute and end surface, featuring a first portion with a larger length along the rotation axis and a second portion closer to the outer periphery with a smaller length, along with a third portion for moderate length change, to distribute stress and prevent sharp changes, enhancing fracture resistance and chip discharge performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the flute directly connects to the end surface at an approximately vertical intersection, then the structure is simple and easy to manufacture, but stress concentration occurs at the ridgeline part leading to fracture
Solution Approach 1:
The connection surface is divided into multiple portions (first portion, second portion, third portion) with different lengths in the rotation axis direction. This segmentation allows stress to be distributed across multiple zones rather than concentrated at a single ridgeline, resolving the contradiction between structural simplicity and fracture resistance.
Solution Approach 2:
Different portions of the connection surface have different local characteristics - the first portion has a larger length providing stability, the second portion has a smaller length near the outer periphery reducing stress concentration, and the third portion provides moderate transition. This local differentiation maintains structural simplicity while preventing fracture.
2Device complexity
If the connection surface has uniform length throughout, then the structure is simple, but stress distribution is poor leading to chipping and reduced durability
Solution Approach 1:
The connection surface employs local quality by having different lengths at different locations - the first portion (near rotation axis) has larger length for stress distribution, the second portion (near outer periphery) has smaller length to prevent chipping, and the third portion provides moderate transition. This resolves the contradiction between uniformity and durability.
Solution Approach 2:
The third portion acts as an intermediary zone between the first portion (larger length) and second portion (smaller length), providing a moderate length transition that smoothly distributes stress across the connection surface, preventing both chipping and excessive complexity.
3Strength
If the second portion of the connection surface has larger length, then stress distribution is improved, but chip discharge performance deteriorates due to restricted chip flow
Solution Approach 1:
The second portion near the outer periphery has a smaller length specifically designed to maintain open chip flow paths and prevent chip clogging, while the first portion near the rotation axis has larger length for stress distribution. This local differentiation resolves the contradiction between stress distribution and chip discharge performance.
Solution Approach 2:
The connection surface lengths are differentiated in the rotation axis direction (vertical dimension) rather than uniformly reducing all dimensions. This allows the second portion to have smaller vertical length for chip discharge while the first portion maintains larger vertical length for stress distribution, resolving the contradiction through dimensional differentiation.
Data Source
AI summary
A drill may be extended from a first end to a second end and may include a cutting part. The cutting part may include a cutting edge, a flute, an end surface and a connection surface. The flute may be extended from the cutting edge toward the second end. The end surface may be located closer to the second end than the flute. The connection surface may be located between the flute and the end surface. The connection surface may include a first portion, and a second portion located closer to an outer periphery of the cutting part than the first portion. A length in the direction along the rotation axis on the second portion may be smaller than a length in the direction along the rotation axis on the first portion in a side view orthogonal to the rotation axis.