No. 1, 1998 - Tribology in Industry

perature;4 VEarethecriteriaof similarityof thecuttinc
process determined by the formulas [2-]:
o-Il'nl.
a
r/-
r.f d-
G''(l sittylu "
r-P=J
01
Dt - isthe radius of the rouncting of rhe curting edge of
t!
the tool;a is the temperature conductivify coefficient of
themachined material; o=Bi, G=i'p'e arethe
criteria of similarity of the cutting process; a1 and b1 are
the thickness and *'iclth of the shear; y, f) and e are the
angle of cutting eclge,
Qt
^,-
The value ofrT for the first fourgroups of the machined
materialsisequal zero.Thisconfirmsthewell-knownfact
that abrasive and adhesive kinds of the tool wear in
cuttingofthesematerialsarenottypical.
z - Student's criterion and F - the Fisher's criterion
::it:i:.:Tl':
jiTl:1.::efficients are meaningful and
teste, dependence.
Representingtheobtaineddependenceintoformula(1)
after some transformations we have the following:
the angle of taper and the vertex Crrrr*-. Cn, !# o,I!L cr.(-)''
anglerespectively;irand.l.aretheheatconditioneffi-
"' SV. S4u'
\q )
ciencies of the treated and tool materials respectively; c.
x, ),, z ate the values depended on the properties of the
machined and tool materials.
The criterion ot'^
oI
,uk", into account the inuuence of
the abrasive and adhesive phenomena on the process of
the cutting tool wear. The B V and E criteria show the
influence of the ditfusive and oxidizing ones.
N{arirnum value of the technological productivity accor-
tling to formula (2) will be in the case .f
Durable experinrents were made and experimental derta
of other authors given in the papers [3, 4, 5, 6, 7, 8] were
used to determine the values of the coeffic ien'ts t'1,'x1, y 1,
zl inlhe obtained criterion equation (3).
The values of the coefficients c, .r; 1i z obtained after the
mathematical processing of the experimental results are
given in table 1'
I c-u. arzu la;i''',-r
v,nirtc=t-- -l (5)
i,-.", j.i") ,/) |
ft' lu"iJ | -${ttr'^-) 'EZt €tr 'I1-t1+21) u*o "J
Tablc l. Vnlttts o.[ t/u cot'JJit'itnt.s itt fonruiln (3)
Atier some transformations we obtain the formula (5).
rtv
tg1+ t6y . - ;' rnirt (6)
I tttt'
This conclition will be right in the case if the cutting speed
derivative, cleterminecl from the expression (fi), is equal
k=.1 for monocarbicre ru'gsren-cobart
',il.];,,|[T
harcr aloys;k=1.8 :[:'J:il[:illji;#'{:,1iXi::ffi'jfil
for bicarbide titaniurn-tungsten-cobalt alloys; k:1.5 for
high-speed steel;/ is the ratio of heat condr.rction efficiencies
of the trtol zrncl nrat:hinecl materilrls.
Groups of tne materials I c
After transformation of the obtained expression (7) we
get the lormula for gefting the cutting speed which cor-
22 TiiboloSSt itt irulustry, Volunre 20, No. 1, 1998.