Oval Coolant Hole Drill for Stainless Steel Boring
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Solution Overview
Problem
Conventional coolant-hole equipped drills face challenges in efficiently supplying coolant to the outer circumferential side of the cutting edge during boring, particularly with difficult cutting materials like stainless steel, due to reduced strength and uneven coolant distribution, leading to inadequate cooling and increased risk of breakage.
Innovation Solution
The design features a coolant hole with constant intervals between wall surfaces and the chip discharging groove, ensuring even coolant distribution and increased cross-sectional area without compromising the drill's strength, along with a gradually increasing gap between hole wall surfaces towards the outer circumferential side to enhance coolant flow and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cross sectional area of the coolant hole is enlarged to increase coolant supply, then the coolant supply amount is improved, but the drill main body strength is reduced causing breakage
Solution Approach 1:
The coolant hole cross section is changed from a conventional circular shape to an oval shape with the long axis extending in the circumferential direction. This dimensional change allows the coolant hole area to be increased while maintaining sufficient wall thickness in the radial direction, thereby increasing coolant supply without compromising drill main body strength.
Solution Approach 2:
The coolant hole is designed with non-uniform dimensions in different directions: the long axis extends in the circumferential direction to maximize coolant flow area, while the short axis maintains adequate radial distance from the outer circumferential surface. This local quality differentiation allows optimized coolant supply while preserving structural integrity at critical locations.
2Productivity
If the coolant hole is positioned closer to the outer circumferential surface to improve coolant delivery, then coolant flow efficiency is improved, but the wall thickness is reduced compromising strength
Solution Approach 1:
By orienting the coolant hole's long axis in the circumferential direction rather than radially, the design achieves improved coolant delivery efficiency without sacrificing radial wall thickness. The oval cross section allows the hole to extend further in the circumferential dimension while maintaining adequate radial distance from the outer surface.
3Ease of manufacture
If conventional circular coolant holes are used, then manufacturing is simple, but coolant supply to outer circumferential side is insufficient
Solution Approach 1:
The coolant hole cross section is changed from circular to oval with the long axis in the circumferential direction. This shape modification can be achieved through standard drilling and shaping processes, maintaining manufacturing simplicity while significantly improving coolant supply capability to the outer circumferential region where heat generation is highest.
Data Source
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AI summary
A coolant-hole equipped drill includes a drill main body, a cutting edge portion which has a tip flank, a chip discharging groove provided with a front groove wall surface and a rear groove wall surface, a cutting edge formed at a ridge line portion where the front groove wall surface and the tip flank intersect with each other, a land portion formed between the chip discharging grooves adjacent to each other in the rotating direction, and a coolant hole drilled at the land portion and opened at the tip flank. The coolant hole includes a front hole wall surface, a rear hole wall surface, and an outer-circumference hole wall surface.