students are usually confused while expressing forces in orthogonal cutting. Here's a step by step approach to explain the procedure.
Solution of Merchant CircleAsstt Prof Akhtar Husain Dept of
Mechanical Engineering Air University, Islamabad Email:
[email protected]
Merchant Model of Orthogonal Cutting Assume Chip in static
equilibrium Friction force F and Normal force to friction N from
tool to chip Shear force Fs and Normal force to shear Fn from
workpart to chip
Ref: 2007 John Wiley & Sons, Inc. M P Groover, Fundamentals
of Modern Manufacturing 3/e
Orthogonal Cutting ModelWorkpart Fs Machined Surface Chip
Cutter
R
Fn
F F
N
Cutting forces of equal resultant R from cutter and workpart
sides shown in a circle. Forces from Cutter are F, N ; Forces from
workpart are Fn , Fs. Rake Angle is and Shear Plane Angle is .
Forces from Workpart & CutterFs
R
Fn
F F
N
Only forces from cutter and workpart side are shown here (
Workpart and cutter are not shown for clarity.)
Forces from Cutter
R F F
N
Only forces from cutter side are shown here.
Forces from Cutter & Dynamometer
R F Ft F
Fc NIn order to determine values of forces from cutter side (F,
N ), we must express them in terms of known Forces Ft and Fc. Ft
and Fc can be determined by having load measuring cells on the tool
post.
Forces from cutter side in terms of Fc and Fc
F = Fc sin a + Ft cos a
R F Ft F
Fc N = Fc cos a - Ft sin a N
Forces from cutter side are expressed in terms of Fc and Ft
trigonometrically .
Forces from Workpart & CutterFs
R
Fn
F F
N
Once again see the forces from cutter and workpart side.
Forces from WorkpartFs
Fn R F
Only forces from workpart side are shown here.
Forces from Workpart & DynamometerFs Fc
Fn R Ft F
In order to determine values of forces from workpart side (Fs,
Fn ), we must express them in terms of known Forces Ft and Fc. Ft
and Fc can be determined by having load measuring cells with the
tool post. Note that their directions are reversed when they are
viewed from workpart side.
Forces from cutter side in terms of Fc and Fc
Fs = Fc cos f - Ft sin f Fs
Fc
Fn R Ft F
Fn = Fc sin f + Ft cos f
Forces from workpart side are expressed in terms of Fc and Ft
trigonometrically
