Cutting energy and surface roughness in medium density fiberboard rip sawing

Medium density fiberboard (MDF) is a?wood based panel which main feature is the distribution of wood fibers, uniform and dense in the full panel thickness, allowing for very precise machining on the edges and in the faces of the board. However, and due to its manufacturing process, a?density profile is produced with external layers being heavier than the core of the panel. These differences generate a?variable surface quality across the panel when machined. The tool characteristics and the cutting process kinematics also determine the resulting surface roughness of the processed material. With regard to the cutting energy, there are important variations when machining conditions are modified, or when some tool characteristics are changed. The aim of this paper is to determine the cutting energy required to rip sawing MDF and to study its relationship with the resulting surface roughness across the panel profile when the density of the material changes. The findings lead to the conclusion that there is a?close relationship between cutting energy and surface roughness, being particularly sensitive to changes in specific gravity within the profile of the panel, and in particular to changes in cutting condition expressed as mean chip thickness.     

The interactions between wax and UF resin in medium density fibreboard

Through the use of fluorescently labelled paraffin wax and UF resin, fluorescence microscopy has been used to simultaneously visualise wax and resin components on medium density fibreboard (MDF) fibre. To simulate differing application methods, the wax and resin were applied to fibre either separately or as a mixture. Visualisation on unpressed fibre and in panels suggests the application order can lead to differing wax-resin behaviours and how each interact with fibre. Both qualitative and quantitative analyses of wax and resin distribution on fibre established that the main differences in behaviours were due to wax and occur on pressing. Applying wax first to fibre led to wax droplet agglomeration in panels whereas applying wax after resin or as a mixture appeared to allow wax to be retained as relatively smaller droplets within the resin matrix. This also manifested itself in differences in wax overlap with resin in panels, where a relatively low overlap was observed when applying wax first, despite a substantially higher overlap in unpressed fibre. Application of wax after resin or as a mixture resulted in the wax generally staying with the resin. The observed differences in wax distribution were also correlated with panel cold water soak properties.     

模糊PID控制在中密度纤维板施胶中的应用研究

PID控制针对单输入单输出的定值线性系统能达到较理想的控制效果,但针对中密度纤维板施胶控制系统,不能很好解决施胶控制中多输入多输出、非线性、时滞等诸多问题.通过比较常规模糊控制器和传统的PID控制器在控制方面的优缺点,结合PID控制中存在的问题与不足,提出将模糊控制技术与PID控制算法相结合构成复合型控制器.经仿真试验,控制效果明显改善.     

浅析中密度纤维板施胶控制研究现状

文中分析了国内外当前中密度纤维板施胶技术的研究现状；介绍了SCR直流调速控制施胶系统、MCS-1型微机控制系统与失重流量计施胶控制系统的特点、原理、优缺点；并就施胶控制系统设计提出了几点看法。     

Effectiveness of two chemical preservatives against widespread moulds of high density fibreboard

In this work the effectiveness of potassium sorbate and condensed tannins against mycelial growth and sporulation of some widespread moulds of High-Density Fibreboards (HDF) for crate production was tested. Laboratory inoculation tests were performed on 130 treated and untreated samples of HDF using the European Standard EN 15457. Potassium sorbate was more effective than condensed tannins and significantly reduced (P<0.05) both mycelial growth and mitospore (conidia) production of mould fungi compared to controls.     

Effect of species and grinding disc distance on the surface roughness parameters of medium density fiberboard

Surface quality of medium density fiberboard (MDF), as a very important criterion for further finishing and utilization, was evaluated using a wide range of measuring parameters (instruments, filters, filtering cut-off length, measuring length, measuring resolution, roughness parameters). However, these various approaches make any data comparison rather difficult. Furthermore, filtering the measured data with a simple Gaussian filter has proved unreliable for wood surfaces. A new, more robust approach by using a Robust Gaussian Regression filter together with a previously tested set of measuring and evaluating parameters was used in this paper in order to quantify the surface roughness of MDF manufactured from different species (beech, poplar, birch, Scots pine, mixture 50 % Scots pine and 50 % beech) and using three different grinding disc distances (0.06, 0.15 and 0.6 mm). If manufacturing parameters are kept constant, the processing roughness of MDF is similar, but variable species anatomy and fuzziness effects will give differentiation in total roughness. The results indicated that fibers made of a mixture of wood chips from Scots pine and beech led to the smoothest MDF surface, followed closely by poplar, birch, and Scots pine. The roughest surface was measured for the panels made of beech fibers. Investigating the influence of the grinding disc distance, the roughest MDF surface was obtained when a grinding gap of 0.6 mm was used. However, surface roughness was found to be quite similar applying a grinding disc distance of 0.06 mm slightly lower for 0.15 mm. This finding indicates that a too fine grinding gap does not improve the MDF surface roughness.     

Influence of different climatic conditions on the roughness of uncoated medium density fiberboards (MDF)

The surface roughness is primarily a function of the raw material properties, but other factors like type and amount of resin, press cycle, sanding and moisture content of the boards may also affect the roughness and other surface properties. In this study the effect of the equilibrium moisture content on medium density fiberboards (MDF) surfaces was evaluated using different raw materials in the surface layers as well as different binders. The statistical analysis confirmed that the relationship between equilibrium moisture content and average roughness is a complex function of interactions between many variables.     

Influence of climatic conditions and surface roughness on the wettability of medium density fiberboards (MDF)

Wettability of wood surface is measured by the contact angle between the liquid and the surface of the wood. In this study, the wettability of MDF surfaces was measured using different mixtures of distilled water and isopropanol. The results reveal that TF-bonded MDF made from fresh and recycled fibers showed better wettability than the corresponding MUF-bonded MDF. Moreover, the entire results indicate that roughness is one of the most important influencing factors on the wettability of MDF surfaces.     

Influence of climatic conditions and surface roughness on the wettability of medium density fiberboards (MDF)

Wettability of wood surface is measured by the contact angle between the liquid and the surface of the wood. In this study, the wettability of MDF surfaces was measured using different mixtures of distilled water and isopropanol. The results reveal that TF-bonded MDF made from fresh and recycled fibers showed better wettability than the corresponding MUF-bonded MDF. Moreover, the entire results indicate that roughness is one of the most important influencing factors on the wettability of MDF surfaces.     

木材表面粗糙度测量技术

本文从国内外木材表面粗糙度研究内容、研究方向、测量方法和手段等方面综述了木材表面粗糙度研究现状与最新成果,并对木材表面粗糙度研究的未来发展方向提出了一些建议。     

奥地利的板材加工技术

去年上半年新建的奥地利潘汉斯（Panhans）机械制造有限公司,前身是安东——潘汉斯工具与机械厂。该公司致力于研发经济地板材锯切,包括纤维板、塑料板和石膏纸箱等板材。它具有30多年的板材锯切的经验。     

Surface roughness properties of polyester woven fabrics after abrasion

Effect of abrasion on surface roughness properties of textured polyester woven fabrics has been investigated. The effects of weft density, weft yarn filament number, fiber fineness, and weave pattern on surface roughness after abrasion were studied. Surface roughness values of control fabric (not abraded) and abraded fabrics after four different abrasion cycles were discussed according to different constructional parameters. Surface roughness values of fabrics changed according to abrasion cycles and the changes were related to yarn float lengths, yarn densities, yarn fiber fineness, and initial fabric surface roughness. A general overview of the results showed that abrasion eliminated the effect of texture especially at the fabric samples with initially high surface roughness. The surface roughness of fabrics with initially high surface roughness decreased at a greater extent than the ones with low surface roughness after abrasion. Fabrics with high surface roughness were affected more by abrasion and the effect of abrasion on rough surfaces depended on different manners regarding the compactness of woven structures.     

Surface roughness properties of wool woven fabrics after abrasion

Effects of abrasion on surface roughness properties together with appearance of woven wool fabrics have been investigated. The effects of weft yarn count, weft yarn density, and weave pattern on fabric surface roughness after abrasion were researched. Surface roughness values of control fabric (not abraded) and abraded fabrics after four different abrasion cycles were discussed according to different fabric constructional parameters. It was observed that the greatest decreases in surface roughness values after abrasion were observed in loose fabric structures which had the highest initial fabric surface roughness values (coarse yarn, low yarn density, and low yarn intersection). The results showed that change of roughness properties of wool fabric surfaces after abrasion depends on the initial surface roughness values and on the amount of contact area of fabrics based on the fabric constructional parameters.     

On-line control of feed-speed in circular sawing

An adaptive control optimization system was developed to produce a desired surface finish roughness by automatic control of the work-piece feed-rate in circular sawing. The system developed in this study consists of the interconnection of an adaptive controller with a numerically controlled circular saw. The AE signals and cutting forces were measured to monitor the machining process continuously in this system. The signals were provided to the adaptive controller to evaluate the surface finish roughness and adjust the workpiece feed-rate automatically in the machining process. Sensing of AE signals and of cutting forces was compared to determine which technique is more convenient. Experiments were carried out with a carbide-tipped circular saw. Cross cutting was done with counter-cutting during the experiments. The cutting parameters controlled were workpiece feed-rates and cutting speeds. Japanese beech (Fagus crenata Blume) and Yezo spruce (Picea jezoensis Carr.) were used as the workpiece. Experimental results indicated that adaptive control optimization took place in the system developed for circular sawing. The desired surface finish roughness was produced by automatic control of the workpiece feed-rate using the sensing technique of AE signals as well as that of cutting force. However, the system using AE signals is more convenient than taht using cutting force.     

Study washboarding phenomenon in frame sawing machines

The paper concerns washboarding phenomenon where for every kind of sawing a very regular pattern is characterised by a sinusoidal – like variation in board thickness. That pattern is an effect of the saw blade lateral vibrations. It is palpable that these vibrations are detrimental to the cutting process, and lead to poor surface quality and dimensional accuracy, and raw material waste. For band saws in the contemporary literature models explaining a washboarding phenomenon are supported on self-excited (self-induced) vibration theories. However, these explanations cannot be simply broadened into the washboarding phenomenon in frame sawing machines. In this work based on theoretical and experimental investigation the washboard pattern formation is clarified by the authors with the use of a theoretical model, in which the rugged surface is an effect of vibrations generated by lateral cyclic loading and lagged wave formation. The authors hope that their obtained results contribute significantly to further understanding of this important but complicated phenomenon.     

Study washboarding phenomenon in frame sawing machines

The paper concerns washboarding phenomenon where for every kind of sawing a very regular pattern is characterised by a sinusoidal – like variation in board thickness. That pattern is an effect of the saw blade lateral vibrations. It is palpable that these vibrations are detrimental to the cutting process, and lead to poor surface quality and dimensional accuracy, and raw material waste. For band saws in the contemporary literature models explaining a washboarding phenomenon are supported on self-excited (self-induced) vibration theories. However, these explanations cannot be simply broadened into the washboarding phenomenon in frame sawing machines. In this work based on theoretical and experimental investigation the washboard pattern formation is clarified by the authors with the use of a theoretical model, in which the rugged surface is an effect of vibrations generated by lateral cyclic loading and lagged wave formation. The authors hope that their obtained results contribute significantly to further understanding of this important but complicated phenomenon.     

圆锯锯切中在线控制进给速度

在圆锯锯切时，开发一种最佳适应性控制系统来自动控制工件的进给速度以产生所要求的工件表面粗糙度。本研究中开发的系统包括与数控圆锯机相连接的适应性控制器。本系统在加工过程中由监测器连续测定声发射讯号和切削力。在加工过程中适应性控制器提供的讯号用于评估表面粗糙度并自动调节工件进给速度。