How does the cutting force changes with rake

# How does the cutting force changes with rake - eliminate...

This preview shows pages 1–9. Sign up to view the full content.

How does the cutting force changes with rake angle? Applications: Machining Grinding Friction Wear Prof. Christopher Brown WPI

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Machining forces and Friction α sin cos c t F F F + = sin cos t c F F N - = φ sin cos t c s F F F - = cos sin t c n F F F + = Rake face Frictional force and normal force Shear plane forces F t F n F c F s N F = = τ μ tan tan tan t c c t F F F F - + = Tool workpiece friction coefficient µ 90-(τ-α+φ)
Fc=Fs cos φ + Fn cos (90- φ) Use Trig identity Fc=Fs cos φ + Fn sin (φ) 1. Write Fc in terms of Fs and Fn

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Eliminate Fn From the geometry of Merchant’s circle Fn=Fs/tan(90- (τ-α+φ)) =Fs tan(τ-α+φ) Fc=Fs cos φ + Fs tan(τ-α+φ)sin (φ) Fc=Fs (cos φ + tan(τ-α+φ)sin (φ))
Fs=S w doc/sin φ (shear stress * area) Fc=Sw doc/sin φ (cos φ + tan(τ-α+φ)sin (φ)) Fc=S w doc (cot φ + tan(τ-α+φ)) Write Fs in terms of shear stress and cutting geometry

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
φ = 45-τ/2+α/2 (Merchant) Fc=S w doc (cot (45-τ/2+α/2) + tan(τ-α+ 45- τ/2+α/2)) Fc=S w doc (cot (45-τ/2+α/2) + tan(45+τ/2-α/2) Use Merchant’s equation to

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: eliminate the shear angle Normalize and simplify Fc/Swdoc = (cot (45-/2+/2) + tan(45+/2-/2) Use trig identity Fc/Swdoc = 2tan(45+/2-/2) Fc=Fs cos + Fn cos (90- ) 1. Fc=Fs cos + Fn sin () 2. Fn=Fs/tan(90- (-+))=Fs tan(-+) Fc=Fs cos + Fs tan(-+)sin () 3. Fc=Fs (cos + tan(-+)sin ()) 4. Fs=S w doc/sin (shear stress * area) Fc=Sw doc/sin (cos + tan(-+)sin ()) 5. Fc=S w doc (cot + tan(-+)) 6. = 45-/2+/2 (Merchant) Fc=S w doc (cot (45-/2+/2) + tan(-+ 45-/2+/2)) 7. Fc=S w doc (cot (45-/2+/2) + tan(45+/2-/2) Fc/Swdoc = (cot (45-/2+/2) + tan(45+/2-/2) 8. Fc/Swdoc = 2tan(45+/2-/2) Normalized cutting force versus rake angle 2 4 6 8 10 12 14 16 18 20-60-40-20 20 40 60 rake angle degrees normalized cutting force =0.8 =0.6 =0.4...
View Full Document

## This note was uploaded on 04/29/2008 for the course ME 1800 taught by Professor Brown during the Winter '08 term at WPI.

### Page1 / 9

How does the cutting force changes with rake - eliminate...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online