Vpliv dielektričnih lastnosti lepila in lesa na selektivnost VF segrevanja : diplomsko delo (univerzitetni študij)

Kranjc, Matija (author), Šernek, Milan (mentor), Resnik, Jože (reviewer)

Raziskovali smo vpliv dielektričnih lastnosti lepila in lesa na selektivnost segrevanja preskušanca. Eksperimentalni del je potekal v 2 fazah. Najprej smo izmerili dielektrične lastnosti tekočega PVA lepila in furnirja bukve (Fagus sylvatica L.). Pri lepilu smo ugotavljali odvisnost dielektričnih lastnosti od temperature (22-80 °C) in frekvence (79,4 kHz-25,1 MHz), pri lesu pa samo odvisnost od frekvence na enakem območju kot pri lepilu. Meritve smo opravili z napravo Agilent 4285A Precision LCR Meter in pripadajočima sondama za merjenje dielektričnih lastnosti. V drugi fazi smo pripravili preskušance in jih v stiskalnici segrevali na posreden (klasično) in neposreden (VF) način. Med segrevanjem smo ugotavljali vpliv časa segrevanja na spreminjanje in porazdelitev temperature znotraj lepljenca. Ugotovili smo, da dielektrična vrednost in izgubni faktor lepila naraščata z naraščajočo temperaturo. Lepilo ima bistveno višje dielektrične lastnosti kot les, zato se je lepilni spoj v polju VF segreval hitreje kot les. Razlike v segrevanju so bile bolj očitne v začetni fazi segrevanja. V primerjavi hitrosti neposrednega in posrednega segrevanja nismo ugotovili bistvenih razlik.

• Language: Slovenian
• Keywords: les, tekoče PVA lepilo, dielektrične lastnosti, visoka frekvenca, segrevanje, selektivnost
• Work type: Undergraduate thesis
• Typology: 2.11 - Undergraduate Thesis
• Organization: BF - Biotechnical Faculty
• Place of publishing: Ljubljana
• Publisher: [M. Kranjc]
• Year: 2006
• Number of pages: XII, 55 f.
• PID: 20.500.12556/RUL-145
• UDC: 630*824.87
• COBISS.SI-ID: 1445001
• Publication date in RUL: 11.07.2014

Secondary language

• Language: English
• Title: The effect of dielectric properties of adhesive and wood on HF heating selectivity : graduation thesis (university studies)

Abstract

The effect of the dielectric properties of adhesive and wood on heating selectivity of test pieces was analysed. The experiment was carried out in 2 phases. First the influence of temperature (22-80 °C) and frequency (79.4 kHz-25.1 MHz) on the dielectric properties of liquid PVA adhesive, and the influence of frequency on the dielectric properties of beech wood (Fagus sylvatica L.) were measured. The measurements were performed with the Agilent 4285A Precision LCR Meter and the according test fixtures. In the second phase test pieces were made and heated indirectly and directly (HF). The test pieces were heated in a press, and the growth and distribution of temperature in the boards were monitored. It was determined that by increasing the temperature the dielectric properties of the adhesive increase. Adhesives have considerably higher dielectric properties than wood, and therefore, heat faster. The differences in heating were more obvious in early stages of heating. No differences in speed of indirect and direct heating were found.

• Keywords: wood, liquid PVA adhesive, dielectric properties, high frequency, heating, selectivity