Authors: DUBRAVKO ROGALE, ŽELJKO KNEZIĆ, SINIŠA FAJT, SNJEŽANA FIRŠT ROGALE
Faculty: Sveučilište u Zagrebu Tekstilno-tehnološki fakultet and Sveučilište u Zagrebu Fakultet elektrotehnike i računarstva
web pages: www.ttf.unizg.hr; www.fer.unizg.hr
The capacitive micrometer measures the heights of the displaced edges of welded joints on parts of conventional and intelligent clothing using rotating ultrasonic sonotrodes. The device also records the values of displaced edges caused by an excessive amount of supplied ultrasonic energy, which increases the stiffness of the weld and reduces its breaking strength. Conventional micrometers cannot be used for these purposes because the excessive compressive force deforms the welds and introduces an error into measurements. The capacitive micrometer consists of a measuring capacitive rotating sonotrode with low compressive force, a high-frequency oscillator, a measuring bridge with compensation, a high-frequency amplifier, a demodulator and a DC amplifier. It is equipped with the table to displace the ultrasonic welds on abscissa and ordinate, as well as the microcamera and monitor to position the feelers of the capacitive probe. The design of the device enables measurements in a displacement range of 1 μm with low compressive forces and without deforming the test samples.