Most of the parts of furniture made of medium density fiberboards (MDF) require at least one hole to be assembled. The drilling technological parameters influence the quality of holes. Factors such ...as tip angle of the drill bit, feed rate, type and diameter of the drill bit, and spindle rotational speed could affect the drilling process. Therefore, the right choosing of drilling parameters is a mandatory condition to improve the drilling efficiency that is expressed through tool durability, cost, and quality of the drilling. Thus, in this work, we are proposed an approach that consists in combining two modelling techniques, which were successfully applied in various fields, namely artificial neural network (ANN) and response surface methodology (RSM), to analyze and optimize the drilling process of MDF boards. Four artificial neural network models with a reasonable accuracy were developed to predict the analyzed responses, namely delamination factor at inlet, delamination factor at outlet, thrust force, and drilling torque. These models were used to complete the experimental design that was requested by the RSM. The optimum values of the selected factors and their influence on the drilling process of the MDF boards were revealed. A part of optimum combinations among analyzed factors could be used both during the drilling of the MDF boards and prelaminated wood particleboards.
Plywood is a wood-based composite with many applications in construction, shipbuilding, and furniture production. One of the basic plywood processing and mandatory operations is drilling. Up to now, ...considerable and very diverse thematic research has been recently carried out on drilling, but little of that deals with modeling of the drilling process of plywood. Therefore, in this work, the artificial neural network modeling technique and response surface methodology were applied to model and optimize the drilling process of plywood. Two artificial neural network models were developed to predict the thrust force and the drilling torque based on drill tip angle, tooth bite, and drill type. The developed ANN models were used to complete the value of responses in the experimental design, which was requested by the response surface methodology. The trust force during the drilling of plywood is significantly influenced by the drill type (helical or flat). The most significant factor that affects the drilling torque during the drilling of plywood is the tooth bite. A helical drill assures a lower minimum thrust force and drilling torque than a flat drill. The proposed method could be used as an optimization tool during the design phase of the furniture manufacturing process.
The objective of this research was to establish comparatively some relevant features of Turkey oak and sessile oak wood, in order to better understand the drying behavior of these species. The ...analyzed samples were obtained from freshly harvested trees of the same age, originating from the Southern Sub-Carpathians. The microscopic analysis revealed that Turkey oak has larger earlywood pores than sessile oak. In heartwood, they are partly filled with tyloses for both species. The macroscopic analysis showed that Turkey oak wood has a much lower proportion of heartwood (only 50%) compared to sessile oak (90%). The comparative FTIR analysis of the two species showed similar qualitative chemical composition, but also some differences between sapwood and heartwood regarding the relative proportion of the main constituents, and very likely in the structure of lignin. High amounts of extractives were found in Turkey oak sapwood (5.34% in cold water, 7.77% in hot water, and 21.60% in NaOH 1%), close to the values obtained in sessile oak heartwood. The research also revealed that the Turkey oak sapwood and heartwood have statistically similar values of oven-dry density, shrinkage coefficient, fiber saturation point, while in sessile oak, the values are clearly higher in the heartwood.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Drilling is one of the oldest and most important methods of processing wood and wood-based materials. Knowing the optimum value of factors that affect the drilling process could lead both to ...high-quality furniture and low-energy consumption during the manufacturing process. In this work, the artificial neural network modeling technique and response surface methodology were employed to reveal the optimum value of selected factors, namely, drill tip angle, tooth bite, and drill type of the delamination factor at the inlet and outlet, thrust force, and drilling torque. The data set that was used in this work to develop and validate the ANN models was collected from the literature. The results showed that the developed ANN models could reasonably predict the analyzed responses. By using these models and the response surface methodology, the optimum values of analyzed factors were revealed. Moreover, the influences of selected factors on the drilling process of wood particleboards were analyzed.
The best-possible valorization of each cut log is a priority. The aim of this research was to evaluate the potential of a solution for increasing the conversion efficiency of tapered logs, by ...edge-cutting the narrowest sideboards at 45° and joining them by gluing, in order to obtain usable lumber boards. The modality of obtaining the glued elements was described and the values of the density and bending properties (MOE and MOR) of these elements compared to solid wood elements taken from the same logs and the same position within each log was determined. The envisaged outcome was to determine if the bonded products are suited to be used as cores within laminated products for construction.
In this work, the influence of the number of dowels and the option to place the dowels in the cross section of part on the bending moment capacity of heat-treated wood dowel joints was analysed. The ...joints, which were made of heat-treated ash, were tested by means of a universal testing machine.The ultimate failure load and the moment arms were used to figure out the bending moment capacity of the joints loaded in compression or in tension. The number of dowels affected the tensile strength of the L-shaped heat-treated wood joints. The modality to place the dowels in the cross section of rail, namely, in collinearity or in a triangular shape, did not significantly affect the strength of the heat-treated wood dowel joints.
One of the biggest challenges during phytosanitary treatment of wood packaging material is to ascertain that all the boards subjected to the treatment reach the final prescribed temperature (i.e. ...56 °C for 30 min during conventional heating and 60 °C for 1 min during dielectric heating) across the wood profile including core as per ISPM 15. This study represents a first attempt to find a tool that can be used to reveal the reliability of the phytosanitary treatment that is achieved by means of dielectric heating at radio frequencies (RF). The tool proposed in this work consists of an artificial neural network (ANN) based model that is solved by means of Monte Carlo method. The data set that was used in this work was collected from the literature. The results indicate that the developed ANN model can reasonably predict (R
2
= 0.72) the final temperature of boards during dielectric heating at radio frequencies. To predict the reliability of the RF phytosanitary treatment by means of the developed ANN model, three input variables are considered as random variables, namely, green moisture content, power density and initial temperature of wood. Once the model is solved for a large number of times and the performance function that separates the failure domain from the success domain is defined, the reliability of the phytosanitary treatment could be obtained. Since the reliability of the RF phytosanitary treatment is known at various time spans, the optimal treatment time is revealed.
The paper deals with an investigation of the influence of the method used to assembly a drying schedule for larch (
Larix
) timber on kiln performance and quality of drying. Ten drying schedules were ...analysed (six from literature and four from industry) using a simulation tool, which was experimentally validated for larch. First, the methods were compared using various criteria, namely drying rate, drying cost, energy consumption and quality of drying. Second, a multi-criteria analysis was performed using one-factor multilevel-categoric design. The results of this study showed that the kiln performance and the drying quality are influenced by the method applied to assembly the schedule. Currently, none of the analysed methods can completely fulfill the industrial requirements (short time, low cost and high quality). According to a cluster analysis, the results showed that the analysed methods can be grouped into three clusters based on their similarities regarding the kiln performance and quality of drying.
This paper introduces a numerical methodology based on a 3D turbulent flow computation developed to assess the aerodynamic performances of lumber drying kilns. The numerical results are validated ...against experimental data obtained by applying five different fan speeds and reversible air flow. The distributions of the energy loss coefficient and of the non-uniformity flow coefficient were plotted along the flow path in both normal and reverse directions and the regions with larger air loss values were identified. The numerical computation revealed that three quarters of the airfl ow delivered by the fans bypasses the wood stacks through different gaps, consequently leading to a low aerodynamic effi ciency (of 24-25 %) of the kiln.
PDF
