Vibration categorization of flail mower using MEMS accelerometer

V sklopu zaključne naloge smo zasnovali merilni sistem, s katerim zaznavamo nivo vibracij. Meritve lahko izvajamo na različnih stroji, ter tako spremljamo spremembe tekom delovanja. Glede na nivo vibracij je možno detektirati napako, ter to napako odpraviti. V našem primeru smo meritve izvajali na mulčerjih, ter analizirali vibracije tedaj ko pride do loma kladiva. Pri takšnih strojih je glavni vir vibracij ekscentričnost vrtečega se rotorja. Ob lomu kladiva se ekscentričnost in s tem nivo vibracij povečata. Vibracije zaznavamo s spremembo amplitude pospeška. Velikost amplitude pospeška pri nihanju smo najprej določili teoretično, nato pa vrednosti primerjati z izmerjenimi rezultati. Analizo smo izvedli na dveh konstrukcijsko različnih mulčerjih, ter ugotavljali stopnjo ujemanja eksperimentalno in numerično pridobljenih rezultatov. Ugotovili smo, da je odstopanje med rezultati večje pri konstrukcijsko kompleksnejšem mulčerju. Za konec smo izvedeli uravnoteženje rotorja brez enega kladiva z odstranitvijo dodatnega na nasprotni strani. Ugotovili smo, da to ni najboljša rešitev, saj to ne vodi do zmanjšanja vibracij. Končno lahko ugotovimo, da lahko s takšnim sistemom uspešno spremljamo nivo vibracij ter zaznamo povečanje amplitude vibracij pri poškodbi stroja.In scope of diploma thesis we designed a measuring system to detect the level of vibration, specially for flail mower. Measurement is preformed for the purpose of monitoring of machine performance. In our case, we performed measurements on flail mowers and studied what happens if a hammer breaks while operating. In case of rotary machines the main source of vibration is the eccentricity of the rotor. When the hammer breaks, the eccentricity increases resulting in higher vibration levels. Vibration is detected by investigating peaks of acceleration. First, we theoretically determined the magnitude of the acceleration amplitude and then compared the values with a measured results. The validation of the model was performed with two different flail mower to examine the affects of the construction on the agreement between numerical and experimental results. We found that the calculated and measured results are not in full agreement which is mainly due to the simplified model of flail mower. Finally, we tried to balance the rotor with one hammer removed by removing the extra one on the opposite side. We found out that this is not the best solution as vibration was not reduced. The final conclusion was that such system can successfully monitor the vibration level and detect an increase of oscillating variables when malfunction in the system occours