t=0.2mm
tcmax=0.4mm
tcmin=0.25mm
tanϕmax=rmaxcosα1−rmaxsinα=0.20.25cos9∘1−0.20.25sin9∘
orϕmax=42.09∘
tanϕmin=tmincosα1−rminsinα=0.20.4cos9∘1−0.20.4sin9∘
orϕmin=28.18∘
Ratio=ϕmaxϕmin=42.0928.18=1.494