Single-Lip Deep Hole Drill Chip Forming Surface
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Solution Overview
Problem
Deep-hole gundrills face challenges in producing short chips when machining materials that produce long chips, leading to increased cutting forces, bore deviation, and reduced productivity, especially at high feed rates, and existing solutions like chip splitters and formers either increase costs or force requirements.
Innovation Solution
A deep-hole gundrill with a flat chip forming surface featuring two plateaus, where the first section is radially inside and higher than the rake surface, and the second section is radially outside and slightly raised, deflecting chips into a flute to break them into short pieces, reducing cutting forces and torque while being simple to produce and regrind.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rake angle of 0° is used, then the tool is simple to produce by grinding, but comparatively high cutting forces occur during machining
Solution Approach 1:
The chip forming surface is divided into two sections with different plateau heights relative to the rake surface. The first section has a plateau further above the rake surface than the second section, creating localized variations in chip deformation characteristics that reduce cutting forces while maintaining manufacturing simplicity
Solution Approach 2:
The invention changes the geometric parameters of the chip forming surface by introducing two plateaus at different heights above the rake surface. This modifies the chip flow and deformation characteristics, reducing cutting forces without requiring a change in the overall rake angle
2Reliability
If chip splitters are used, then chip size is minimized for reliable transport, but the bottom of the bore has an interrupted and/or curved shape which is often undesired
Solution Approach 1:
Instead of using an interrupted or curved chip splitter blade, the invention applies localized plateau structures on the chip forming surface. The first and second sections create different chip deformation zones that break chips into manageable sizes while preserving the continuity and straightness of the bore bottom shape
3Reliability
If chip formers are used, then chip formation is influenced, but feed forces and cutting forces rise which can negatively affect the bore deviation
Solution Approach 1:
The invention modifies the chip forming surface geometry by creating two plateaus at different heights above the rake surface. This parameter change influences chip formation and breaking into short pieces while maintaining relatively low feed and cutting forces, thus avoiding negative effects on bore deviation
4Productivity
If materials that produce long chips are machined at high feed rates, then productivity increases, but chip transport out of the bore becomes problematic
Solution Approach 1:
The chip forming surface is divided into two sections with different plateau heights, creating localized chip deformation zones. This allows chips to be broken into short pieces even at high feed rates, ensuring reliable chip transport while maintaining high productivity
Solution Approach 2:
The plateau structures on the chip forming surface preliminarily deform and break chips during the cutting process itself, before chips leave the bore. This preliminary chip breaking action ensures that even long-chip materials produce short chips suitable for reliable transport at high feed rates
Data Source
AI summary
The invention relates to a single-lip deep hole drill comprising a drill head, wherein the drill head has a drill diameter, a blade and a channel for chip removal, wherein the blade extends outwards from a rotational axis up to the perimeter of the drill head, wherein the blade has a cutting surface and wherein the channel is bordered by a chip forming surface, wherein the chip forming surface has two sections such that a first section of the chip forming surface extends in the radial direction from the rotational axis up to a first diameter, a second section of the chip forming surface connects to the first section in the radial direction, the first section is positioned above the cutting surface, and the second section is positioned nearer to the cutting surface than the first section.