ISSN 1068-798X, Russian Engineering Research, 2017, Vol. 37, No. 7, pp. 622–625. © Allerton Press, Inc., 2017.
Original Russian Text © A.A. Dyakonov, A.Kh. Nurkenov, I.V. Shmidt, A.S. Degtyareva, A.S. Ovsienko, A.D. Kazanskii, 2017, published in STIN, 2017, No. 2, pp. 18–21.
Static Rigidity of Numerically Controlled Lathes
A. A. Dyakonov*, A. Kh. Nurkenov**, I. V. Shmidt***, A. S. Degtyareva****,
A. S. Ovsienko*****, and A. D. Kazanskii******
South Ural State University, Chelyabinsk, Russia
Abstract—Methods of determining the static rigidity of the technological system in numerically controlled
machine tools are considered, with a view to assessing their applicability in production tests. Measurements
of the microdisplacements under the action of external forces yields numerical characteristics of the damping
decrement and the rigidity of the technological system
Keywords: numerically controlled lathes, rigidity of the technological system, damping decrement, static
Numerically controlled lathes are used in the pro-
duction of a wide range of components. They permit
flexible adjustment in accordance with the required
machining conditions. The basic characteristics of
such lathes are the limiting dimensions of the
machined workpieces; the power of the main spindle;
and the limiting machining precision. One of the main
problems in machining on numerically controlled
lathes is vibration of the technological system as a
result of periodic external perturbing forces or discon-
tinuous cutting processes. That results in instability of
the margin removed from the workpiece; premature
tool wear; increased surface roughness; and deviation
from the required shape of the machined surface (flat-
tening, undulation, taper, etc.).
The magnitude of vibration of lathe components as
a function the rigidity is known from research [1–3]. It
depends primarily on the rigidity of the basic compo-
nents (the spindle clamp, frame, and tool store). That
determines the static and dynamic rigidity of the
lathe’s technological system. Because of difficulty in
calculating the dynamic rigidity, attention turns first to
the static rigidity of the technological system for a
16K20F3R132 numerically controlled lathe.
EXISTING METHODS OF DETERMINING
THE STATIC RIGIDITY
The static rigidity of numerically controlled lathes
was determined and compared with the manufac-
turer’s stated rigidity in [4–7]. The ability of the lathe
to meet the claimed machining precision after opera-
tion for a specific period was investigated. The rigidity
was measured on the basis of static loading of the lathe
components by means of special attachments or jacks,
with simultaneous recording of the applied forces by
means of a dynamometer and measurement of the lin-
ear displacement of the lathe components relative to
the corresponding components of the cutting forces.
Another option is direction finding: indirect
assessment of the rigidity of the technological system
by measuring the limiting deviations from the longitu-
dinal guides under the action of the load on a steel
plate in the support . In that way, the position of the
center of rigidity may be determined by calculating the
maximum and minimum rigidity; that is useful for
subsequent analysis of the lathe design in terms of the
potential for increasing the vibrational stability.
Such experiments are very laborious. They require
the testing and design of additional attachments. That
calls for more setup time and increases the costs.
Those problems may be avoided by modeling on
the basis of ANSYS and SolidWorks software [9–11].
The specifics of the lathe’s technological system are
taken into account on the basis of mathematical simu-
lation, by means of appropriate software [12–14]. This
approach is limited by the capabilities of the software
and the qualifications of the researcher.
Thus, existing methods of determining the static
rigidity of the lathe’s technological system require