Single Point Cutting Tool Geometry - me.iitb.ac.inramesh/courses/ME338/tool.pdf · Outline • Tool...
Transcript of Single Point Cutting Tool Geometry - me.iitb.ac.inramesh/courses/ME338/tool.pdf · Outline • Tool...
Single Point Cutting Tool Geometry 1
Prof. S. S. Pande
Mechanical Engineering Department
Indian Institute of Technology, Bombay
Outline
• Tool Geometry, Tool Angles
• Systems for Tool nomenclature - ISO System - ORS/NRS - American Standards System - ASA
• Tool Angle Conversion: ISO ASA
- Mathematical Basis
Basic Tool Shape
2β
Work
Tool
P
Wedge angle : 2β
Cutting Efficiency
2β
Tool
P
R R
Cutting Efficiency =
P = 2R sinβ
Orthogonal Cutting Geometry
Orthogonal Cutting
Velocity V
Orthogonal Cutting
Characteristics
• Cutting edge Perpendicular to cutting Velocity Vector
• Plain Strain (2D) phenomenon
• No Spread of material across
Oblique Cutting
Tool
Chip
λ
Work piece V
Oblique Cutting
Characteristics
• Cutting edge at an angle(λ) to normal to velocity vector in the cutting plane
• Inclination angle λ - modifies Tool angles - governs Direction of chip flow
Stabler’s Law for Chip flow
nc = k. λ nc = chip flow angle K = 0.8 – 1.0
Free and Restricted Cutting
Feed Motion
Tool
Chip Flow
Free Restricted
Single Point Tool Geometry
Tool Nomenclature Systems
Tool in Hand
• ISO System : ORS/ NRS - Orthogonal/ Normal Reference System
• American Standards Association (ASA) system
Tool in Machine
• Tool /Insert setting in fixture
Tool Angle Reference Systems ORS and ASA
λ
γx
γy
γo
Tool Reference Planes
Feed
πB
πo πc Cutting Orthogonal
Basic
axis v
Orthogonal (ORS) Reference Planes
Trace of πo
Trace of πc
πB πB
πc πo
Reference Planes - ORS View in πo
View in πc
πc πB
πo
Reference Planes – ASA system
Y
X X
V πx
πy
πB
ASA Reference Planes
X X
Y
πy
πx
Y
Tool Angles – ASA System
Y
X
V View in πx Plane
View in πy Plane
Ø = Plan Approach angle Øs = Side cutting Edge angle Øe = End cutting Edge angle
Ø = 90 - Øs
Tool Angles
Feed
Ø
Øs
Øe X X
Tool Designation
ASA System
γy , γx , αy , αx , Øe , Øs , r
γy : Back rake angle γx : Side rake angle αy : Front clearance angle αx : Side clearance angle Øe : End cutting Edge angle Øs : Side cutting Edge angle
r : Nose radius (mm)
Tool Angle Conversion
ORS ASA (γo, λ) (γx , γy )
Ø = Plan Approach angle
Tool Angle Conversion
ASA ORS (γx , γy ) (γo, λ)
Ø = Plan Approach angle
Does Orthogonal Plane πo represent True rake angle?
Orthogonal and Normal Reference Planes
λ
πo πc πn
Tool Angle Conversion
ORS NRS γo γn
Tool in Machine System
Static angles on Tool/Insert change due to
• Setting in tool Holders/ Fixtures
• Tool/ Work relative motion.
Inserts in Tool Holder
Inserts and Tool Angles
Tool Setup on Machine