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Publikacije (8)

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Atif Hodžić, Nedim Hurem, Miran Merhar

The machinability of wood is an insufficiently researched problem that is mainly related to the machinability of metals. The machinability of a material is a technological property that expresses the ability to remove the maximum amount of crisps from the machined surface in the shortest possible time with satisfactory machining quality and the lowest possible cutting forces and tool wear. The quality and efficiency of the production process when milling solid wood is influenced by the following factors: type of wood, density and moisture content of the wood, temperatures and dimensions of the workpiece as well as the hardness and strength of the wood. The parameters of the milling mode, such as the main and auxiliary motion, the cutting force and power and the power of the drive unit, have a direct effect on the milling process and are related to the milling tool, i.e. the type and quality of the material from which it is made, the number of cutting edges, the geometry of the cutting edge and the sharpness of the tool. In this work, the influence of significant input parameters on the machinability of solid wood in flat peripheral milling is analysed as a function of the cutting force as an output parameter by planning an experiment. The experimental results are mathematically modelled with the aim of obtaining a mathematical model of the process of large-scale milling of solid wood, i.e. its parameters as a function of the cutting force. The results of the experimental part and the results of the models are analysed and compared in order to draw appropriate conclusions and

Aldin Bjelić, Miran Merhar, Atif Hodžić

Considering that two-layer parquet is composed of two lamellas—most commonly 10 mm birch plywood and 4 mm solid oak—bonded together with adhesive, and that profiling is required to create a joint that serves a mechanical function, the process becomes complex and imposes significant demands on the cutting tool. This paper presents an experimental analysis of how the type of cutting tool affects the surface quality, profile stability, and edge wear of the tool after a certain machining length. Two different technological solutions were analyzed: a tool with replaceable tungsten carbide (TC) inserts and a tool with an integrated polycrystalline diamond (PCD) cutting edge. A particular focus of the analysis is the wear of the TC tool in the area of the oak and plywood joint profile, where selective wear of the TC edge occurs, potentially causing profile deformation and a weaker joint. The obtained results show that using PCD tools in two-layer parquet profiling achieves better surface finish, longer tool life, more consistent geometry of the cutting edge, and thus a more stable parquet profile.

Miran Merhar, Aldin Bjelić, Atif Hodžić

For efficient production planning, it is necessary to know the power consumption of a particular woodworking operation in advance. In the past, many power measurement tests have been carried out based on a large number of different combinations of technological parameters. However, in this paper, the effects of technological parameters and wood properties on the power magnitude of peripheral milling are analysed using experimental design methods, where the effects of the different factors can be tested with a much smaller number of combinations. Therefore, a central composite experimental design was used to plan the experiments. Three different tree species with different densities were milled with three different numbers of cutting knives and three depths of cut at constant feeding speed and rotational velocity. For each milling combination, the power was measured continuously and then the average power was calculated. Based on the measurements, a suitable model was determined that allowed the magnitude of the cutting power to be determined for each combination of technological parameters and wood species tested. The model proved to be suitable, as the deviations between the measured and modelled power values are minimal.

Husein Rošić, Aldin Bjelić, Atif Hodžić, Miran Merhar

It is known from theory and practice that the workability of wood depends on structural parameters that are closely related to the physical, mechanical and chemical properties of the type of wood itself, and disturbance parameters that refer to the technological and geometric parameters determined by the specific processing regime. That machinability, in addition to the mechanical output sizes, is often expressed by the quality, that is, the roughness of the processed surface. By defining a mathematical model in the process of planing solid wood in which the input sizes are processing parameters: wood density (ρ), feed rate (m/min) and number of cutting spirals (z), and the spilled sizes are praamters of roughness of the treated surface (Ra and Rz), and by applying optimization methods, optimal solutions for the process of planing solid wood on planer machines will be determined, so that the obtained Yoptim model will aim to improve the workability of solid wood, specifically its roughness of the processed surface.

Atif Hodžić, Aldin Bijelić, D. Hodžić

We consider the machinability of the material as a technological feature that expresses the ability of the material to remove the maximum number of shavings from its machined surface in the minimum time with satisfactory processing quality, with as little cutting force as possible and as little tool wear as possible. The aim of the experimental research in this work is to examine the significance of the influential kinematic parameters of the roughness of the machined surface, i.e. of wood density (ρ), feeding speed (s’) and the number of spiral cutting knices (z) in the process of planning massive wood on the roughness of the newly created processing surface, which will vary in 14 trials, of which 6 are repetitions in the central point of the compositional plan, where the roughness parameter Ra is obtained as an output value, and the analysis of experimental data from the point of view of possible achievement of a better quality of the processed surface. The obtained mathematical model is essentially applicable and can be used to optimize the machinability parameters in the planning process of solid wood, and the experimental results can be used in further research into other parameters of the machinability of solid wood in the planning process.

R. Hasanagić, Leila Fathi, Atif Hodžić, M. Bahmani

In Europe, wood is a crucial construction material that has experienced a surge in use for building applications in recent years. To enhance its dimensional stability and durability, thermal modification is a widely accepted commercial technology. Thermal modification is a popular technique that alters the properties of wood, improving its resistance to decay and increasing its dimensional stability. The process involves heating wood to high temperatures under controlled conditions, leading to chemical reactions that result in various physical and mechanical changes. This paper will discuss the effects of thermal modification on the physical properties of wood, such as density, moisture content, and color, as well as its impact on the mechanical properties, including strength, stiffness, and hardness. Additionally, the review will examine the factors that influence the degree of modification, such as temperature, duration, and wood species. Finally, the paper will conclude with an overview of the current state of research in this field and identify potential avenues for future investigation.

<p style="text-align: justify;">The paper analyzes the behavior of the plastic container during the buckling, ie during the load effect on the containers. The analysis was experimentally performed on several different types of containers. The container material is polypropylene. Experimental determination of pressure force and corresponding deformation was performed in the<br />laboratory at the Faculty of Technical Engineering Bihać. The analysis includes experimental testing on assembled containers and on container side. Places where deformation occurs on the container sides are shown.</p>

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