BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI - Universitatea ...

(2)
Bul. Inst. Polit. Iaşi, t. LVI (LX), f. 2, 2010 77
Fig.1 – Forces model in symmetrical face milling.
b) For symmetrical milling with even zs the Eq. (2) results.
F
F
Z
X
= 2
= 2
z / 2
s
∑
1
z / 2
s
∑
1
2π
Fz
cos( zi
) = 2Fz
z
2π
Fx
cos( zi
) = 2Fx
z
F = F ⋅ z .
Y
y
s
z / 2
s
∑
1
z / 2
s
∑
1
2π
cos( zi
) ,
z
2π
cos( zi
) ,
z
From Eqs. (1) and (2) result that in symmetrical face milling the forces FZ,
FX and FY depend on the components Fz, Fx and Fy developed on a single-tooth
level, the number of teeth that simultaneously cut (zs) and the cutting tooth
position beside the XYZ coordinates system of the tool. The axial component FY
doesn’t depend on the relative position of the cutting tooth.
2.2. Theoretical Models of Cutting Force Components in
Unsymmetrical Face Milling
In this case, the values of cutting force components FZ, FX, FY are influenced
by the relative position of the tool and the material being cut, resulting different
equations for cut-up (conventional) milling and cut-down (climb) milling.
Fig. 2 shows the geometrical models of unsymmetrical cut-up milling and its
three possible variants:
a) Unsymmetrical face milling with t' = D/2, Ψ = 90°, and z = z / 4 ;
s
1