Page 13 - Апрель

METALWORKING EQUIPMENT AND TOOLS

At the first stage, the experiment consisted in determining the natural frequencies and
vibration modes of the machine tool's operating system. To determine the natural frequencies
of the ES elements, the latter was excited by the blows of a dynamometric hammer, and then
the impulse action and the response to it were processed according to the method [7, 8].
The analysis of frequency characteristics showed the presence of natural frequencies of the
machine tool and work piece, which amounted to 217 Hz and 394 Hz, and the vibration modes
indicate that the work piece mainly vibrates at a frequency of 217 Hz, and at a frequency of 394
Hz - spindle assemblies with circles.
The second stage of experimental
research was devoted to assessing the
influence of disturbing influences from the
grinding process and from the elements of
the machine tool control on the oscillations
of the executive links [11, 12]. The shaft
was ground 8 x 42 x 48 with a total length
of L = 610 mm and a length of the spline
section l = 380 mm according to various
schemes: one-sided grinding - separately
by the upper and lower circles, and
double-sided - with the opposite direction
of rotation of both circles and the parallel
direction of rotation of the upper wheel at
unchanged (opposite) bottom during the
main removal. The circles were balanced
Fig. 1. Spline grinder mod. 3B451, upgraded for double-sided (the imbalance did not exceed 2 g • cm).
processing. The vibration signal from the
absolute vibration sensors fixed on the cylindrical part of the work piece, the sleeves of the
upper and lower circles, on the tailstock, was processed on the CF-355 analyzer during final
removal and during nursing. The sensitivity of the path was determined by the ratio of 5
mV signal from the sensor to 1 µm of real geometric deviation from the profile, that is, the
calibration factor is 0.2 µm / mV. The CF-355 analyzer makes it possible to obtain a spectrum
of a vibration signal with several parameters in numerical terms. These parameters were used
as the most informative:
root mean square –
Where N = 1024 is the number of sampling points;
Аmax - maximum value of the spectrum amplitude;
Sum of the first ten amplitude values

Stanochniy park 13