Veneer drying usually consumes a significant amount of energy including heat and electricity. The soaring energy price as well as the substantial social-environmental concerns regarding energy use ...have urged veneer manufacturers to adapt and become more efficient in energy consumption. Different from the physics-based methods commonly seen in the literature, this research embraced a data-driven approach to analyze and predict unit gas and electricity consumption during industrial veneer drying. Both linear regression and random forest (RF) algorithms were deployed for prediction. Based on cross-validation evaluations, the RF model with all explanatory variables slightly outperformed two linear models regarding almost all accuracy metrics, although linear models had the advantage of providing an easy-to-interpret solution.
Veneer drying is the manufacturing process in the plywood industry that most affects energy consumption and panel properties such as bonding and bending. Therefore, the veneer drying temperature and ...moisture content should be accurately adjusted. Moreover, the determination of veneer thermal conductivity is as important as these two parameters and the thermal conductivity values should also be specifi ed when forming the drying programs. This study aimed to predict the optimum values of the veneer drying temperatures, moisture content and thermal conductivity, which gave the best mechanical properties, by artifi cial neural network (ANN) analysis. Poplar (Populus deltoidesI-77/51) and spruce (Picea orientalis L.) veneers and urea formaldehyde (UF) resin were used in the production of plywood. The thermal conductivity of veneer and the bonding, bending strength and elasticity modulus of the panels were tested by the relevant standards. The most accurate and reliable prediction models were obtained by analyzing the experimental data with ANN. The optimum veneer drying temperature, moisture content and thermal conductivity values that gave the best values for all three mechanical properties were 149 °C, 6.2 % and 0.02668 W/mK for poplar and 116 °C, 4.4 % and 0.02534 W/mK for spruce.
Sušenje furnira proizvodni je proces u industriji furnirskih ploča koji najviše utječe na potrošnju energije i svojstva ploče kao što su čvrstoća lijepljenja i savijanja. Stoga je potrebno točno prilagoditi temperaturu sušenja i sadržaj vode u furniru. Nadalje, određivanje toplinske vodljivosti furnira jednako je važno kao temperatura sušenja i sadržaj vode, pa je pri izradi programa sušenja potrebno specificirati i vrijednosti toplinske vodljivosti. Cilj ovog istraživanja bio je primjenom umjetne neuronske mreže (ANN) predvidjeti vrijednosti optimalne temperature sušenja, sadržaja vode i toplinske vodljivosti furnira koje će rezultirati najboljim mehaničkim svojstvima ploče. Za potrebe ispitivanja furnirske su ploče proizvedene od furnira topolovine (Populus deltoidesI-77/51) i furnira smrekovine (Picea orientalis L.) te su slijepljeni urea formaldehidnom smolom (UF). Prema odgovarajućim standardima ispitani su toplinska vodljivost i čvrstoća lijepljenja furnira te čvrstoća na savijanje i modul elastičnosti ploča. Najtočniji i najpouzdaniji modeli predviđanja dobiveni su analizom eksperimentalnih podataka uz pomoć umjetne neuronske mreže. Optimalne vrijednosti temperature sušenja, sadržaja vode i toplinske vodljivosti uz koje se postižu najbolja mehanička svojstva za furnirske ploče od topolovine iznosile su 149 °C, 6,2 % i 0,02668 W/mK, a za furnirske ploče od smrekovine 116 °C, 4,4 % i 0,02534 W/mK.
In this study, the effect of the veneer-drying process at elevated temperatures on selected properties and formaldehyde emission of plywood panels was determined. We assume that during the veneer ...drying at high temperatures, more formaldehyde is released from it, and therefore, a lower formaldehyde emission can be expected from the finished plywood. Prior to bonding, birch veneers were dried at 160 °C (control) and 185 °C in an industrial veneer steam dryer (SD) and at 180 °C, 240 °C and 280 °C in an industrial veneer gas dryer (GD). Two types of adhesives were used: urea-formaldehyde (UF) and phenol-formaldehyde (PF) resins. Bonding quality, bending strength and modulus of elasticity in bending, water absorption and thickness swelling of plywood samples were determined. The formaldehyde emission level of samples was also measured. It was concluded from the study that the effects of veneer-drying temperatures on the bonding strength and physical and mechanical properties of plywood panels were significant. Veneer-drying temperatures of 185 °C/SD, 180 °C/GD and 240 °C/GD negatively affected the bending strength and the modulus of elasticity along and across the fibres for both UF and PF plywood samples. Bonding strength mean values obtained from all test panels were above the required value (1.0 MPa) indicated in EN 314-2 standard. The lowest formaldehyde emissions for the UF and PF plywood samples were observed in the samples from veneer dried in a steam dryer at 185 °C/SD.
The aim of study was to determine the effect of veneer drying process on some technological properties of polystyrene composite plywood panels. For this reason, 2 mm-thick rotary cut veneers were ...obtained from beech (Fagus orientalis, Lipsky), Alder (Alnus glutinosa subsp. Barbata) and Scots pine (Pinus sylvestris L.) logs. The veneers obtained from three different wood species were divided into two groups to produce polystyrene composite plywood (PCP) and traditional plywood. While PCP was produced both air dried (at 20 °C) and oven dried (at 110 °C), the veneer sheets for production of traditional plywood were dried at 110 °C until reaching 7 % equilibrium moisture content. Two different types of polystyrene with high density (30 kg/m3) and low density (16 kg/m3) were used as bonding material for PCP panel production. The urea-formaldehyde adhesive was used as a bonding material for traditional plywood panels. Bonding shear strength, bending strength, modulus of elasticity and density of plywood and polystyrene composite plywood panels were investigated. It was found that the technological properties observed in the study of composite plywood panels manufactured with natural dried veneers gave similar results compared to those of composites produced with technical dried veneers.
Cilj ovog istraživanja bio je utvrditi utjecaj procesa sušenja furnira na tehnološka svojstva kompozitnih uslojenih drvnih ploča vezanih polistirenom. Ljušteni furniri debljine 2 mm pripremljeni su od trupaca drva bukve (Fagus orientalis, Lipsky), drva johe (Alnus glutinosa subsp. Barbata) i drva običnog bora (Pinus sylvestris L.). Furniri od tri različite vrste drva podijeljeni su u dvije skupine kako bi se proizvela kompozitna uslojena ploča vezana polistirenom (PCP) i tradicionalna uslojena ploča. Za proizvodnju PCP ploča rabljeni su furniri sušeni na zraku (na 20 °C) i u sušioniku (na 110 °C), a za proizvodnju tradicionalne uslojene ploče upotrijebljeni su furniri sušeni pri 110 °C sve do postizanja ravnotežnog sadržaja vode od 7 %. Kao vezivo za PCP ploče uporabljene su dvije vrste polistirena – polistiren velike gustoće (30 kg/m3) i polistiren male gustoće (16 kg/m3). Za proizvodnju tradicionalne uslojene ploče kao vezivo je služilo urea-formaldehidno ljepilo. Istraživani su smična čvrstoća lijepljenog spoja, čvrstoća na savijanje, modul elastičnosti te gustoća uslojene i kompozitne uslojene ploče vezane polistirenom. Utvrđeno je da kompozitne uslojene drvne ploče proizvedene od prirodno sušenih furnira imaju slična promatrana tehnološka svojstva kao i kompoziti proizvedeni od tehnički sušenih furnira.
The paper presents the application of linear programming to increase production efficiency in a furniture factory based on constructional veneer technology. Veneer production classifies as novel wood ...processing technology and it is mainly an automated process. Insufficient quantities of delivered thermal energy for veneer drying result in discontinuity in the production process. Inadequate veneer humidity causes production problems and exploitation of veneer-based products. The problem of using human resources in the newly created situation was also considered. Algorithms for solving problems are given in the paper. Keywords: linear programming; integer programming; wood; algorithm; veneer drying.
In this study the effects of steaming and drying condition on the mechanical properties and durability of laminated veneer lumber (LVL) and solid sawn lumber were investigated in a comparative way. ...Steamed beech and steamed and non-steamed spruce logs were used and two different veneer drying temperatures (20 and 110
°C) were selected for this aim. Aging test was applied according to EN 321 to determine the durability of LVL and solid wood samples. Steaming decreased considerably all investigated strength properties of LVL panels and the least affected was the compression strength. The compression strength and the static bending strength values of both beech and spruce LVL panels were higher than those of the solid wood groups obtained from the same logs. The impact strength values of LVL panels, unlike the static bending strength and the compression strength, were lower than those of the solid samples, which were not steamed and aged.
A reduced temperature drying schedule was investigated as a means of improving grade recovery of structural veneer cut from water stored southern pine logs. Fresh cut, one year old, and three year ...old logs were evaluated. In total, close to one thousand sheets of veneer were evaluated. Reducing the temperature in the last zone of the veneer dryer from 193 to 177°C substantially decreased incidence of grade-reducing splits. Moisture content average and distribution were not effected. Water sorption tests showed favorable results from the one year old material that was dried at the reduced temperature schedule. Relatively high thickness variation of veneer cut from water stored logs had no apparent affect on final moisture content average or distribution. Reducing the zone three temperature by 16°C increased the total veneer drying times by 13 and 19%, respectively, for the three year old and one year old material.
Cilj ovog istraživanja bio je utvrditi utjecaj procesa sušenja furnira na tehnološka svojstva kompozitnih uslojenih drvnih ploča vezanih polistirenom. Ljušteni furniri debljine 2 mm pripremljeni su ...od trupaca drva bukve (Fagus orientalis, Lipsky), drva johe (Alnus glutinosa subsp. Barbata) i drva običnog bora (Pinus sylvestris L.). Furniri od tri različite vrste drva podijeljeni su u dvije skupine kako bi se proizvela kompozitna uslojena ploča vezana polistirenom (PCP) i tradicionalna uslojena ploča. Za proizvodnju PCP ploča rabljeni su furniri sušeni na zraku (na 20 °C) i u sušioniku (na 110 °C), a za proizvodnju tradicionalne uslojene ploče upotrijebljeni su furniri sušeni pri 110 °C sve do postizanja ravnotežnog sadržaja vode od 7 %. Kao vezivo za PCP ploče uporabljene su dvije vrste polistirena – polistiren velike gustoće (30 kg/m3) i polistiren male gustoće (16 kg/m3). Za proizvodnju tradicionalne uslojene ploče kao vezivo je služilo urea-formaldehidno ljepilo. Istraživani su smična čvrstoća lijepljenog spoja, čvrstoća na savijanje, modul elastičnosti te gustoća uslojene i kompozitne uslojene ploče vezane polistirenom. Utvrđeno je da kompozitne uslojene drvne ploče proizvedene od prirodno sušenih furnira imaju slična promatrana tehnološka svojstva kao i kompoziti proizvedeni od tehnički sušenih furnira.
Sušenje furnira proizvodni je proces u industriji furnirskih ploča koji najviše utječe na potrošnju energije i svojstva ploče kao što su čvrstoća lijepljenja i savijanja. Stoga je potrebno točno ...prilagoditi temperaturu sušenja i sadržaj vode u furniru. Nadalje, određivanje toplinske vodljivosti furnira jednako je važno kao temperatura sušenja i sadržaj vode, pa je pri izradi programa sušenja potrebno specificirati i vrijednosti toplinske vodljivosti. Cilj ovog istraživanja bio je primjenom umjetne neuronske mreže (ANN) predvidjeti vrijednosti optimalne temperature sušenja, sadržaja vode i toplinske vodljivosti furnira koje će rezultirati najboljim mehaničkim svojstvima ploče. Za potrebe ispitivanja furnirske su ploče proizvedene od furnira topolovine (Populus deltoidesI-77/51) i furnira smrekovine (Picea orientalis L.) te su slijepljeni urea formaldehidnom smolom (UF). Prema odgovarajućim standardima ispitani su toplinska vodljivost i čvrstoća lijepljenja furnira te čvrstoća na savijanje i modul elastičnosti ploča. Najtočniji i najpouzdaniji modeli predviđanja dobiveni su analizom eksperimentalnih podataka uz pomoć umjetne neuronske mreže. Optimalne vrijednosti temperature sušenja, sadržaja vode i toplinske vodljivosti uz koje se postižu najbolja mehanička svojstva za furnirske ploče od topolovine iznosile su 149 °C, 6,2 % i 0,02668 W/mK, a za furnirske ploče od smrekovine 116 °C, 4,4 % i 0,02534 W/mK.
Radio-frequency drying of wood veneer: commercial use Wilson, J. (Oregon State University, Corvallis, OR)
The Journal of microwave power and electromagnetic energy,
(1989), Letnik:
24, Številka:
2
Journal Article
PDF
