Page 15 - May

METALWORKING EQUIPMENT AND TOOLS

There are times when even new machines have low vibration resistance. Thus, at one of
the enterprises, two identical modern imported CNC lathes, model TNL-100AL, were purchased.
One worked well, met all the requirements, while the other lost vibration resistance, especially
in boring and cross turning operations.
At another enterprise, two TNL-120AL2 CNC lathes of the same company are in operation
(Fig. 1). One of them worked without failures and complaints at maximum load for about 7 years,
let's call it the "old" machine. The other one was acquired later and worked for a little over a
year; we will conditionally call it a "new" machine. Recently, complaints have appeared about the
operation of both machines: when turning at maximum speeds (2500 - 3200 rpm), noise and
vibrations arose, vibration resistance significantly decreased. Such problems associated with
vibration during processing occur quite often, but these cases are notable in that it is possible
to compare two machines of the same design, which are operated under the same conditions,
with the same load, which, it would seem, should have similar performance indicators, however
they vary significantly.
A minimum amount of instrumentation is required to diagnose these machines (Fig. 2).
This is a laptop 1 for mobility and the ability to move between diagnosed machines, on which
the program for recording and processing the nkRecorder signal must be installed; ADC 2
(analog-to-digital converter), connected at the input via cables with amplifiers, and at the
output via a USB port with a computer; accelerometers 6 are connected to amplifiers 5, and a
torque hammer 3 is connected to amplifier 4.

a b

Fig. 2. a) a workstation for recording signals; b) the investigated machine TNL-120AL2: 1 - laptop, 2 - analog-to-digital
converter (ADC), 3 - dynamometric hammer, 4 - strengthening block of the torque hammer, 5 - sensor amplifier vibration
(accelerometer), 6 - accelerometers.

Stanochniy park 15