Four-Edged Drill Geometry for Stable High-Feed Chip Removal
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Solution Overview
Problem
Conventional four-edged drills face challenges in maintaining stability and effective chip removal when drilling difficult-to-cut cast and light metal materials, particularly at high feed rates, due to uneven load distribution and chip congestion.
Innovation Solution
The drill design divides long main cutting edges into outer and inner partial cutting edges, with the inner partial cutting edges being higher to ensure self-centering and pre-drilling, and outer partial cutting edges and short main cutting edges for reaming, optimizing load distribution and chip removal through adjustable cutting wedge angles and point thinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If long main cutting edges extend as far as the middle of the drill tip, then the drill allows drilling into solid materials, but the chisel edge has no cutting effect and only exerts pressure and friction, impeding drilling into solid materials
Solution Approach 1:
The long main cutting edges are divided into two segments: an outer partial cutting edge extending from the cutting corner to a shoulder, and an inner partial cutting edge extending from the shoulder to the chisel edge. This segmentation allows the inner partial cutting edge to perform the cutting function while the outer partial cutting edge provides support and stability, resolving the contradiction between length and cutting effectiveness.
2Productivity
If the chip width of chips generated by main cutting edges increases, then more material is removed per pass, but chip congestion occurs, in particular while deep drilling
Solution Approach 1:
By dividing the long main cutting edges into inner and outer partial cutting edges, the chip width is effectively reduced. The inner partial cutting edge creates narrower chips that can be removed more efficiently through the chip grooves, preventing chip congestion during deep drilling while still maintaining high material removal rates.
3Productivity
If the load placed on long main cutting edges is greater than that on short main cutting edges, then cutting action is more effective, but the long main cutting edges can close at an earlier point
Solution Approach 1:
The inner partial cutting edge is designed with different properties than the outer partial cutting edge. The inner partial cutting edge is optimized for cutting action with higher load, while the outer partial cutting edge provides support and stability. This local differentiation allows the cutting edges to maintain effectiveness longer by distributing stress more evenly and preventing premature closure.
4Productivity
If high feed rates are used, then drilling productivity increases, but stability under load decreases and chip removal becomes more difficult
Solution Approach 1:
The segmented cutting edge design with inner and outer partial cutting edges allows for optimized chip control at high feed rates. The inner partial cutting edge creates narrower chips that are easier to evacuate, while the outer partial cutting edge maintains stability under load, enabling high productivity without sacrificing stability.
Data Source
AI summary
The invention relates to a four-edged drill having two long main cutting edges, arranged in a point-symmetric manner with regard to the axis of rotation, which each extend from an outer circumferential cutting corner to a chisel edge in the middle of the drill tip, and two short main cutting edges, arranged in a point-symmetric manner with regard to the axis of rotation, which each extend from an outer circumferential cutting corner in the direction of the middle of the drill tip. According to the invention, each long main cutting edge has an outer partial cutting edge, extending from the cutting corner as far as a shoulder, and an inner partial cutting edge, extending from the shoulder as far as the chisel edge, said inner partial cutting edge having a greater cutting height (Δx) than the outer partial cutting edge and the short main cutting edges.