Transcript Document 7112585

MECH152-L23-1 (1.0) - 1
Metal Cutting
MECH152-L23-1 (1.0) - 2
Metal Cutting Operations
Turning
Drilling
Horizontal
Milling
Vertical
Milling
MECH152-L23-1 (1.0) - 3
Cutting Tools
http://www.youtube.com/watch?v=hRooPJAeK24&feature=PlayList&p=3AFB507B668AF162&index=4
http://www.youtube.com/watch?v=ivsigqntxno&feature=PlayList&p=3AFB507B668AF162&index=22
http://www.youtube.com/watch?v=mKxX50OMBd4&feature=PlayList&p=3AFB507B668AF162&index=33
Single
Point
Cutter
Multiple
Point
Cutter
MECH152-L23-1 (1.0) - 4
Cutting Force
Metal Removal Rate = vfd
Cutting Force Metal Removal Rate
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Cutting Mechanics
r cos 
tan  
1  r sin 
Orthogonal Cutting Model
ls sin 
r
ls cos(   )
Reducing the model to two dimensional model.
Chip thickness ratio, r = to / tc, always less than 1.
to = d, d being the depth of cut; tc is the chip thickness.
ls = length of the shear plane
MECH152-L23-1 (1.0) - 6
Cutting Mechanics
 
AC AD  DC

BD
BD
  tan(    )  cot 
MECH152-L23-1 (1.0) - 7
Cutting Mechanics
Forces on chip
Tool forces: Normal force, N; Frictional force, F = N;  = tan
Shear plane forces: Shear force, Fs; Normal force, Fn
Shear stress on shear plane:  = Fs /As; As= to w/sin
As= Shear plane area.
MECH152-L23-1 (1.0) - 8
Cutting Mechanics
F = Fc sin + Ft cos
F = Fc cos - Ft sin
Fs = Fc sin  - Ft co 
Fn = Fc sin  + Ft cos 
Fc = cutting force
Ft = thrust force
Fc 
St o w cos(    )
F cos(    )
 s
sin  cos(     ) cos(     )
St o w sin(    )
Fs sin(    )
Ft 

sin  cos(     ) cos(     )
MECH152-L23-1 (1.0) - 9
Power & Energy
Power, P = Fcv
Unit power, U
= Specific energy
= Power / Material Removal Rate = P / MRR
= Fcv / (vtow)
= Fc / (tow)
MECH152-L23-1 (1.0) - 10
Power & Energy
MECH152-L23-1 (1.0) - 11
Size Effect Correction
MECH152-L23-1 (1.0) - 12
Temperature
Rise in temperature at tool chip interface,
U  vto 
T  0.4


C  K 
or, in general
T  Kv m
0.333