木材切削力的研究

本文用拉丁方正交表安排试验，进行切削力的研究。分析切向力Ｆｘ和法向力Ｆｙ与切削厚度、刀具角度、刀具材料及刀具磨损等因素之间的关系。     

Lateral cutting force during machining of wood due to momentary disturbances in the wood structure and degree of wear of the cutting tool

The paper presents a study of the effect of momentary disturbances due to variations in wood structure on the lateral cutting force. Density, shape and fibre-direction of the disturbances, and the degree of wear of the cutting tool are taken into consideration. The paper shows that high density gradients result in high lateral forces. The highest momentary lateral force noted has a value of approximately 40 N. The geometrical shape of the cutting tool in terms of degree of wear has a big impact on the lateral force. The work indicates a potential to increase the cutting performance by a more accurate supervision of the condition of the cutting tools.     

Parallel and normal cutting forces in peripheral milling of wood

In this paper, the parallel and normal cutting forces on the tip of the tool are examined when altering a number of parameters in peripheral milling. The parameters studied are rake angle, chip thickness and upward/downward milling. The evaluation of the forces has been performed during cutting of the chip and the variation in the forces has been recorded. In this way, important information can be obtained in order to arrive at cutting data and tool geometries that will reduce surface defects such as torn and raised grain. In the past, very few investigations have been carried out on peripheral milling, probably because of the difficulties of measurement. Nowadays, however, new measuring techniques and equipment make it possible to measure cutting forces even in standard milling machines. In this work, a sensor was placed under the workpiece to measure the forces in three directions at frequencies up to 7000 Hz. To obtain detailed data, a plastic material was used so that the cutting (revolution) speed could be kept at a minimum, thereby maximizing the number of readouts per incision. The results show how the normal force (the force component perpendicular to the workpiece) varies during the cut and how it is dependent on the examined parameters. This force changes from negative to positive during the cut. When altering the machining parameters, the normal force changes in both direction and magnitude. The other force component, the parallel force, also shows a dependence on the parameters. The objective of this research is to find parameters that minimize the normal forces in order to avoid damage to the wood.     

Parallel and normal cutting forces in peripheral milling of wood

In this paper, the parallel and normal cutting forces on the tip of the tool are examined when altering a number of parameters in peripheral milling. The parameters studied are rake angle, chip thickness and upward/downward milling. The evaluation of the forces has been performed during cutting of the chip and the variation in the forces has been recorded. In this way, important information can be obtained in order to arrive at cutting data and tool geometries that will reduce surface defects such as torn and raised grain. In the past, very few investigations have been carried out on peripheral milling, probably because of the difficulties of measurement. Nowadays, however, new measuring techniques and equipment make it possible to measure cutting forces even in standard milling machines. In this work, a sensor was placed under the workpiece to measure the forces in three directions at frequencies up to 7000 Hz. To obtain detailed data, a plastic material was used so that the cutting (revolution) speed could be kept at a minimum, thereby maximizing the number of readouts per incision. The results show how the normal force (the force component perpendicular to the workpiece) varies during the cut and how it is dependent on the examined parameters. This force changes from negative to positive during the cut. When altering the machining parameters, the normal force changes in both direction and magnitude. The other force component, the parallel force, also shows a dependence on the parameters. The objective of this research is to find parameters that minimize the normal forces in order to avoid damage to the wood.

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Parallele und Normal-Schnittkräfte beim maschinellen Holzbearbeiten

Zusammenfassung  Parallele und Normal-Schnittkräfte, die auf die Werkzeugspitze einwirken, wurden untersucht, wobei eine Reihe von Parametern bei der maschinellen Holzbearbeitung variiert wurden. Dies betrifft Neigungswinkel, Spandicke, Aufwärts- und Abwärts-Schneiden. Das Abschätzen der Kräfte geschah während des Schneidens, wobei die Veränderung der Kräfte aufgezeichnet wurde. So können wichtige Informationen zu Schnittdaten und Werkzeuggeometrie gewonnen werden, um Oberflächendefekte wie Ausreißen oder Aufstellen von Fasern zu verringern. Bisher liegen wegen der Schwierigkeit beim Messen nur wenige Untersuchungen zu diesem Thema vor. Heute ist es mit neuen Meßtechniken möglich, die Schnittkräfte auch an Standardmaschinen zu messen. Ein Sensor wurde unter dem Werkstück angebracht, um die Kräfte in drei Richtungen bei Frequenzen bis zu 7000 Hz zu messen. Um detaillierte Werte zu erhalten, wurde ein Plastikmaterial verwendet, so daß die Schnittgeschwindigkeit minimiert und dadurch die Datenpunkte pro Einschnitt maximiert werden konnte. Die Ergebnisse zeigen, wie die Normalkraft während des Schneidens variiert, und wie sie von den untersuchten Parametern abhängt. Diese Kraft ändert sich von negativen zu positiven Werten während des Schneidens. Bei Änderung der Parameter ändert die Normalkraft sowohl die Richtung als auch die Größe. Die andere, parallele, Kraftkomponente zeigt ebenfalls eine Abhängigkeit von den Parametern. Ziel der Arbeit ist es, Parameter zu finden, die die Normalkräfte minimieren und so Schäden am Holz zu vermeiden.

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竹材物理性质对切削力影响的研究

经切削实验研究了竹材不同切面、密度与含水率对切削力的影响。结果表明:竹黄部位微管束分布较疏,所需主切削力较小,竹青部位微管束分布密集,主切削力较大;端面切削主切削力最大,纵向切削次之,横向切削最小;竹材密度对切削力有明显影响,且呈正相关关系;随着含水率的增加,竹材韧性增大,所需主切削力增加。当含水率超过33.6%之后,随含水率的进一步增加,竹材软化作用明显,主切削力缓慢下降。     

西南桦木材化学成分及其变异的研究

按照我国木材化学成分分析标准,对人工林西南桦木材化学成分进行了测定,结果表明含量分别为:纤维素47.31%,多戊糖23.99%,木质素24.57%,热水抽提物4.41%,1%NaOH抽提物15.15%,笨醇抽提物1.80%,pH值4.61;以上7个指标在树干不同高度的差异均未达到显著性水平;热水、1%NaOH抽提物含量和pH值在不同树龄间的差异达到了1%显著性水平;苯醇抽提物含量达到5%显著性水平.主要化学成分含量的差异不显著.比较分析认为,就木材化学成分而言,西南桦是比较理想的板材和造纸原料.     

含水率对木质材料切削力影响的研究

采用硬质合金锯齿刀具分别对三种实木(杉木、樟子松、水曲柳)和两种人造板(中密度纤维板、刨花板)进行闭式切削实验,研究不同含水率对木质材料切削力的影响。实验结果表明:含水率对木质材料切削力的影响显著。随着含水率的增加,杉木的主切削力和法向力都呈减小趋势,而樟子松和水曲柳的主切削力皆为先增大后减小,当接近纤维饱和点含水率时主切削力达到最大。对人造板,在5%～18%含水率范围内,随着含水率的增加,主切削力和法向力都不断增大。     

木材磨削切削力研究进展

概述了近年来磨削技术及理论研究的最新进展,其中包括磨削机理、磨削力建模和磨削力研究方法,还介绍了几种典型的木材磨削力实验研究的方法,以及个别材种的最佳磨削加工条件.     

Minor cutting edge angles of sawing teeth: effect on cutting forces in wood

European Journal of Wood and Wood Products - Optimising the cutting tool geometries can reduce waste while increasing timber yield. The industry is moving towards thin-kerf bandsawing of timber,...     

The influence of the specific cutting force and cross-sectional geometry of a chip on the cutting force in the process of circular rip-sawing

in the process of circular rip-sawing of wood tissue. The specific cutting force represents a complex interaction between the geometry of the blade, the physical and mechanical properties of the tissue and the direction of cutting, i.e. the rotating angle of the tool. The analyses carried out confirm the appropriateness of the definition of the specific cutting force as the parameter independent of the cross-sectional geometry of the chip, i.e. independent of the technological parameters. The results of the analysis of the relation between the tangential component of the cutting force and the feed velocity, which at invariable values of the entrance and exit rotating angle of the tool directly determines the mean thickness of the chip, confirm the hypothesis on an exponential relation between the said variables. In the case of invariable geometric parameters of the tool, the specific cutting force is constant, while the relation between the cutting force and the technological parameters is merely a consequence of the influence of the parameter of cross-sectional area of the chip f _hm . For this research wood of two tree species was used, namely celtis wood (Celtis zenkeri Engel.) and manilkara wood (Manilkara fouilloyana Aubrev et Pellegr.).     

The influence of the specific cutting force and cross-sectional geometry of a chip on the cutting force in the process of circular rip-sawing

f_s in the process of circular rip-sawing of wood tissue. The specific cutting force represents a complex interaction between the geometry of the blade, the physical and mechanical properties of the tissue and the direction of cutting, i.e. the rotating angle of the tool. The analyses carried out confirm the appropriateness of the definition of the specific cutting force as the parameter independent of the cross-sectional geometry of the chip, i.e. independent of the technological parameters. The results of the analysis of the relation between the tangential component of the cutting force and the feed velocity, which at invariable values of the entrance and exit rotating angle of the tool directly determines the mean thickness of the chip, confirm the hypothesis on an exponential relation between the said variables. In the case of invariable geometric parameters of the tool, the specific cutting force is constant, while the relation between the cutting force and the technological parameters is merely a consequence of the influence of the parameter of cross-sectional area of the chip f _hm . For this research wood of two tree species was used, namely celtis wood (Celtis zenkeri Engel.) and manilkara wood (Manilkara fouilloyana Aubrev et Pellegr.).

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f_s im Verfahren des L?ngss?gens von Holz. Die spezifische Schnittkraft stellt eine komplexe Interaktion zwischen der Geometrie der Schneide, den physikalischen und mechanischen Eigenschaften des Holzes und der Richtung des Schneidens, bzw. des Drehwinkels des Werkzeugs dar. Die durchgeführten Analysen best?tigen die Zweckm?ssigkeit der Definition der spezifischen Schnittkraft als den Parameter, der von der Querschnittsgeometrie des Spanes, bzw. den technologischen Parametern unabh?ngig ist. Die Resultate der Analyse des Zusammenhangs zwischen der tangentialen Komponente der Schnittkraft und der Vorschubgeschwindigkeit, der bei konstanten Werten des Eintritts- und Austrittsdrehwinkels des Werkzeugs unmittelbar die mittlere Spandicke bestimmt, best?tigen die Hypothese über die exponentielle Abh?ngigkeit der genannten Variablen. Im Falle der unver?nderlichen geometrischen Parameter des Werkzeugs ist die spezifische Schnittkraft konstant, die Abh?ngigkeit zwischen der Schnittkraft und den technologischen Parametern ist aber nur die Folge der Einflusses des Parameters der Querschnittsgeometrie des Spanes f _{h m} . In der Untersuchung wurde das Holz von zwei Baumsorten angewandt und zwar Celtis (Celtis zenkeri Engel) und Manilkara (Manilkara fouilloyana Aubrev et Pellegr.).

     

木材过渡切削过程中的声发射特性研究

本文研究了木材过渡切削过程中的声发射特性.木材切削过程中的声发射与切削条件密切相关.木材切削过程中,切屑厚度对声发射活动有显著影响.切屑厚度越大,声发射活动越剧烈;切屑越薄,声发射活动越微弱.切削方向与纤维方向之间的夹角也会影响切削过程中的声发射活动.     

Clearance wear and normal force of TiN-coated P30 in cutting hardboards and wood-chip cementboards

This paper presents the clearance wear and normal force characteristics of TiN coated P30 when cutting hardboards and wood-chip cement boards. Hardboards and wood-chip cement boards of low density (about 0.8 g/cm³) and high density (about 1.2 g/cm³) were cut by using TiN coated P30. Cutting tests were performed at a cutting speed of 1000 m/min and a feed rate of 0.1 mm/rev to investigate the effect of the work materials on the clearance wear and normal force characteristics of the TiN coated P30. The experimental results showed that the TiN coated P30, compared to uncoated P30, is more advantageous in reducing the progression of wear on the clearance face, and in retaining lower normal force in cutting both hardboards and wood-chip cement boards. The amount of clearance wear suffered by the TiN coated P30 for the wood-chip cement board was larger compared to that for the hardboard. Though the TiN coated P30 suffers higher wear for the low density wood-chip cement board than the low density hardboard, its normal force, however, is always lower for the low density wood-chip cement board. It was observed that the clearance wear of the TiN coated P30 occurs due to delamination of TiN film and the wear of the substrate occurs after the coating film was disappeared from the substrate.     

木工刀具材料及其发展趋势

简述了木工刀具材料应具备的性能,介绍了常用木工刀具材料的历史发展过程、分类及性能特点,并对未来发展趋势提出了预测。     

木工刀具硬质合金化及其应用

本文对国内木工刀具硬质合金化基本情况，硬质合金化所使用的刀具材料及性能，木工硬质合金刀具的应用进行阐述，主要供使用这类刀具的人员参考。     

Studies of the main cutting force at and near a cutting edge

The present work is a study of how various parameters affect the cutting forces at, and near a cutting edge when cutting wood at full speed and with all cutting edges of the tool. Statistical methods from experimental results are used to develop a model.     

仿生切削机切削力与切片形态的试验分析

利用电测应变法对一种仿生切削刀具不同切削角度下的切削力和切片形状进行试验研究.试验时,在下切刀的切面上粘贴箔金属应变片,通过静态标定和动态切削信号的采集与分析,测得其切削力大小,并对切削力试验和切片形态进行了分析.     

Modelling the collapse of wood cells during the cutting process

Sharpness affects the performance of a wood cutting tool, particularly the surface finish and cutting forces on the wood. Because the mechanisms involved with cutting wood are not well understood, the amount of cutter sharpness required to produce a high quality cutting edge is not defined. An optimum economic sharpness for a cutter is when any increase in benefit from making the cutter sharper is less than the increase in cost of sharpening.This paper details a hybrid cellular/macroscopic finite element analysis of wood during the cutting process. Different radii were applied to the cutting edge to simulate different sharpnesses. It was found that the interaction between cutter and wood changed as the cutter was sharpened. A changeover point between two cutting mechanisms occurred when the radius of the cutting edge was less than the radius of curvature of the wood fibres in bending. Below this radius, the cutter acted a point load, above this radius, the cutter distributed its force around the radius.The cutting forces for Pinus radiata in the LR direction were experimentally measured. The empirical results confirmed the validity of the model.

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Modellbildung über den Zellkollaps während des Schneidevorgangs

Zusammenfassung Die Schärfe des Schneidwerkzeugs beeinflusst dessen Leistung, besonders im Bezug auf die Qualität der Oberfläche und den Auswirkungen der Schneidkräfte auf das Holz. Da die Mechanismen, die beim Schnitt des Holzes wirken, nicht sonderlich gut erforscht sind, ist der Schärfegrat, der benötigt wird, um ein Messer hoher Qualität herzustellen, nicht definiert.Das ökonomische Schärfemaximum ist erreicht, wenn der zusätzliche Nutzen einer weiteren Schärfung geringer ist als die daraus entstehenden Kosten.Dieser Artikel beschreibt eine FE-Analyse aufgrund zellulärer und makroskopischer Eigenschaften des Holzes während des Schneidprozesses. Verschiedene Radien wurden für das Schneide verwendet, um unterschiedliche Schärfegrade zu simulieren. Es wurde herausgefunden, dass sich der Effekt des Schneidwerkzeuges auf das Holz mit zunehmender Schärfe änderte. Ein Wendepunkt zwischen zwei Schneidemechanismen trat auf, wenn der Radius der Schneide kleiner war als der Krümmungsradius der gebogenen Holzfasern war. Unterhalb dieses Radius übte die schneide punktuellen Druck aus, darüber verteilte sich die Kraft über den gesamten Radius.Die Schneidkräfte bei Pinus radiata in LR Richtung wurden experimentell gemessen. Die empirischen Resultate bestätigten die Richtigkeit des Modells.

     

拉削外回转表面时的切削层参数及切削力分析

以加工曲轴为例，依据拉削原理，通过加工过程中切削层参数的分析计算，指出：拉削外回转表面时的切削力可按照单位切削力计算原理来计算。