Otpornost prema ivičnom izvlačenju vijka u konvencionalnoj iverici i OSB ploči - uticaj tipa iverja

Abstract

Ovo istraživanje je zasnovano na pretpostavci da promene u veličini i obliku iverja mogu imati uticaj na kvalitet ploče iverice uopšte. Pošto su konvencionalna ploča iverica i ploča iverica od orijentisanog "strend" iverja (OSB) izrađene od sasvim različtog iverja, predstavljaju interesantne predmete poređenja. U ovom radu ispitan je uticaj tipa iverja na ivično držanje vijaka u konvencionalnoj i OSB ploči iverici. Ispitivanja su rađena uz upotrebu vijaka prečnika 4,0, 4,5 i 5,0 mm. Dubina uvrtanja je iznosila 30 mm za sve testove, a vijčani otvori su imali prečnik u opsegu 80-90% u odnosu na prečnik korena vijka. Takođe, obavljena su i ispitivanja debljinskog profila gustine i zatezne čvrstoće upravno na površinu ploče, pošto oba ova svojstva predstavljaju pokazatelje kvaliteta srednjeg sloja ploče u kome je smešteno telo vijka. U cilju boljeg uvida u strukturu srednjeg sloja obavljen je vizuelni pregled površinskog preseka uzorka. U radu su utvrđene značajne razlike između otpornosti prema izvlačenju vijka kod konvencionalne i OSB ploče iverice, pri svim prečnicima vijaka. Pri tome, uzorci OSB-a pokazali su 56-73% veće srednje vrednosti sile izvlačenja u odnosu na konvencionalnu ploču. Sa druge strane, OSB ploča je pokazala veće rasipanje rezultata za sve prečnike vijka, što može dovesti do određenih problema prilikom projektovanja i izrade nameštaja.

This research was based on presumption that the changes in size and shape of wood particles are expected to have certain impact on the particleboard quality in general. Since the conventional particleboard (PB) and oriented strand board (OSB) were built of the quite diverse wood particles, they present interesting specimens in the comparison tests. In this work, the influence of the wood particles type on the edge screw holding performance of conventional particleboard and OSB was investigated. Those tests were obtained with the screw diameters of 4.0 mm, 4.5 mm and 5 mm. Depth of embedment was 30 mm for all tests and with the pilot-hole diameter kept in the range of 80-90% in respect of the screw root diameter. Additional tests of the thickness density profile and tensile strength perpendicular to the surface of the board were conducted. Since the middle layer structure of the particleboard embeds the screw body, both mentioned parameters are considered important in the aspect of the quality of the edge screw holding performance. In order to have further insight into the conformation of the middle layer the image survey was obtained on the split board section presenting the surface of the middle layer. Significant differences in the SWR performance of OSB and PB was recorded at all screw diameters. For the screw withdrawal tests parameters OSB samples showed 56-73% superior mean values then conventional PB. On the other hand, the OSB showed wider dispersions of measured withdrawal forces at all screw diameters, which might present some of the problems in certain engineering and project calculations.