Miroslav Gašparík

Optimization of the Cutting Process of Wood-Based Agglomerated Materials by Abrasive Water-Jet

Abstract This paper deals with the cutting MDF, OSB, and plywood boards by abrasive water-jet (GMA Garnet Australian, grain size 80, MESH = 0.188 mm), with a kerf width depending on the material properties and technical parameters (material thickness, cutting direction, abrasive flow, and feed speed). The entry of water-jet cutting in the longitudinal direction produces changes in the material due to lateral leads spreading the width of the cut joints by an average of 0.20 mm for MDF boards, 0.3 mm for OSB boards, and 0.17 mm for plywood. On the exit side of the material, the water has the opposite effect. In relation to the thicknesses of the material, the width of the cut joints increases. The experiment has shown that the optimum value of the feed speed is explicitly 400 mm.min-1, at which the kerf width reaches the lowest dimensions both at entry and exit, and the abrasive flow of 450 g.min-1 has been shown as optimum. Kivonat A faalapú agglomerált anyagok folyadéksugaras vágásának optimalizálása. E tanulmány az MDF, OSB és rétegelt lemezek abrazív szemcsés folyadéksugaras vágásának problémájával foglalkozik (GMA Garnet Australian, 80-as szemcseméret, 0,188 mm szitaméret), az anyagtulajdonságoktól és műszaki paraméterektől (anyagvastagság, vágási irány, szemcsekoncentráció és előtolási sebesség) függő vágásrés mérettel. A folyadéksugár longitudinális irányú belépése változásokat okoz az anyagban, mivel ez oldalirányban jobban szétteríti a vágásrés szélességét, MDF esetében átlag 0,20 mm-rel, OSB-nél átlag 0,30 mm-rel, rétegelt lemeznél pedig átlag 0,17 mm-rel. Az anyag kilépési oldalán a víz ezzel ellentétes hatást fejt ki. A vágásrés szélessége az anyagvastagsággal növekszik. A kísérletek megmutatták, hogy kimondottan a 400 mm/min előtolás az optimális, melynél a vágásrés szélessége a legkisebb a bemeneti és a kimeneti oldalon egyaránt. Szemcsekoncentráció tekintetében 450 g/min bizonyult optimálisnak.

3D Molding of Veneers by Mechanical and Pneumatic Methods

This paper deals with the influence of selected methods (mechanical and pneumatic) as well as various factors (wood species, moisture content, veneer shape, punch diameter, laminating foil thickness, holding method, plasticizing) on 3D molding of veneers. 3D molding was evaluated on the basis of maximum deflection of birch and beech veneers. Cracks and warping edges were also evaluated in selected groups of mechanical molding. Mechanical methods tested veneers with various treatments (steaming, water and ammonia plasticizing and lamination). The pneumatic method was based on veneer shaping using air pressure. The results indicate that birch veneers are more suitable for 3D molding. The differences between the mechanical and pneumatic methods were not considerable. The most suitable method for mechanical 3D molding was the veneer lamination by polyethylene foils with thicknesses of 80 and 125 μm, inasmuch as these achieved better results than veneer plasticized by steam. The occurrence of cracks was more frequent in beech veneers, whereas, edge warping occurred at similar rates for both wood species and depends rather on holding method during 3D molding. Use of the ammonia solution is more suitable and there occurs no marked increase in moisture as happens when soaking in water.