20-08-2016, 11:59 AM
The assembly of machine tool spindles results in a degree of variability in the effective stiffness of the bearings. This may result in a poor machining performance if the bearing stiffnesses are below their specified design values. Alternatively, the life of the bearings may be reduced if the bearings stiffnesses are above the design values because of excessive preload. This paper describes a method of checking the spindle assembly by making vibration measurements. From these measurements it is possible to determine which bearings (if any) are not at their design stiffness. This then allows appropriate adjustments to be made to ensure the assembled spindle is close to the design specifications.
A typical vibration measurement system includes a device to sense the vibration (accelerometer), and an instrument to measure the level of vibration. Today a number of industries are making vibration measuring instruments that look like sound level meters. This equipment also has settings for measuring frequency, a frequency-weighting network, and a display such as a meter, printer or recorder.
The accelerometer produces an electrical signal. The size of this signal is proportional to the acceleration applied to it. The frequency-weighting network mimics the human sensitivity to vibration of different frequencies. The use of weighting networks gives a single number as a measure of vibration exposure and is expressed as the frequency-weighted vibration exposure in metres per second squared (m/s2), units of acceleration.
A typical vibration measurement system includes a device to sense the vibration (accelerometer), and an instrument to measure the level of vibration. Today a number of industries are making vibration measuring instruments that look like sound level meters. This equipment also has settings for measuring frequency, a frequency-weighting network, and a display such as a meter, printer or recorder.
The accelerometer produces an electrical signal. The size of this signal is proportional to the acceleration applied to it. The frequency-weighting network mimics the human sensitivity to vibration of different frequencies. The use of weighting networks gives a single number as a measure of vibration exposure and is expressed as the frequency-weighted vibration exposure in metres per second squared (m/s2), units of acceleration.
