useful formula
========
∀a∈R^+ :∀b ∈R: a sin x +b cos x =(√(a^2 +b^2 ))sin (x+arctan (b/a))
∫(dx/(a sin x +b cos x))=
=(1/(√(a^2 +b^2 )))∫(dx/(sin (x+arctan (b/a))))=
[t=x+arctan (b/a) → dx=dt]
(1/(√(a^2 +b^2 )))∫(dt/(sin t))=−(1/(√(a^2 +b^2 )))ln ((1/(sin t))+(1/(tan t))) =
=−(1/(√(a^2 +b^2 )))ln ∣(((√(a^2 +b^2 ))−b sin x +a cos x)/(a sin x +b cos x))∣ +C
given diameter 25mm
half of the drill point angle =60
cutting velocity=44000mm/minute
length=60mm
feedrate=0.25mm/revolution
determine the time needed to drill a through hole
1) calculate ∫_0 ^(2π) (dt/(cost +x sint)) wih x from R.
2) calculate ∫_0 ^(2π) ((sint)/((cost +xsint)^2 ))dt
3) find[the value of ∫_0 ^(2π) (dt/(cos(2t)+2sin(2t)))