木工铣刀的选用

依据木材铣削要素、材料性质、铣刀切削方向,稳定性和安全性几方面介绍了木工铣刀主要技术参数,角度参数、结构形式、回转方向、切削用量、运转稳定性和加工的安全性选用的原则和方法.     

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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木工铣床在木材加工中的安全性分析

为了保证木工铣床在木材加工中的安全性,而需要采取的工艺措施和安全操作注意事项。     

木材隔热材料刨削加工的研究

房屋结构隔热的经济意义越来越受重视。因为将来的能源价格将越来越贵。在产生能量的同时也造成二氧化碳含量的增高。考虑到这两方面的原因，一个节能的方法是使用木材的隔热材料。一个由BMBF资助的项目——包括了研究传统刨削加工产生可作为隔热材料的木屑的优化。考虑到它作为隔热材料的性能。另外还有切屑与加工表面质量的关系等。     

Peripheral milling properties of compressed wood manufactured from planted China-fir

Softwood exhibits different physical and mechanical properties in early wood and late wood, which often becomes the cause of some cutting defects during processing. These problems, however, can be partially solved by conversion into compressed wood. It can be expected that density and strength of the compressed wood increase with the increase in compression, thus affecting cutting resistance. The study on the machinability of compressed wood in order to justify its application is needed. In the test, green China-fir wood (Cunninghamia lanceolata) grown in plantations was compressed in radial direction using various compression sets, followed by peripheral milling parallel to the grain. The results showed that the horizontal cutting force increased with an increase in compression and depth of cut, but decreased with rake angle increase. The vertical cutting forces increased with an increase in cutting depth. No apparent relationship between vertical cutting force and compression was found. No significant difference existed in horizontal cutting forces beween up cutting and down cutting.     

Examination of tools of different materials edge geometry for MDF milling

Most of the investigations directed to find the relation between tool wear and the wood-based panel characteristics concern particleboard cutting. The goal of this paper was to characterize the optimal edge geometry, in case of wear, when milling the medium-density fibreboard, for blades produced from different materials.     

Assessment of surface properties and solvent-borne coating performance of red oak wood produced by peripheral planing

Coating performance on wood could be affected for different aspects including the manner in which the surface is prepared. Peripheral planing is one of the most used machining processes in woodworking. Improving this process would allow to enhance coating performance. As a result, the effects of wavelength and rake angle on surface properties and coating performance were evaluated in an attempt to improve peripheral planing of red oak wood. Surface quality was assessed through roughness, scanning electron micrographs, and wettability analyses. The performance of a solvent-borne coating was measured by adhesion strength before and after accelerated aging. Surface roughness and energy components increased as rake angle increased. As wavelength increased, cell damage and surface roughness increased. Surfaces prepared with a rake angle of 25° had more cell-wall fibrillation, which was assumed to be responsible for increased surface energy and improved coating adhesion after weathering. Samples machined with this rake angle combined with a short wavelength resulted in the lowest loss of adhesion after aging and presented an acceptable level of surface roughness.     

切削刃位置精度对铣削表面粗糙度影响的机理再探

文章分析有效切削刃判定值与装刀数量、铣削波纹深度之间的关系，深入探讨切削丸位置精度影响铣削表面粗糙度的机理。指出：铣削波纹深度不变时，有效切削丸判定值与装刀数量的平方成正比关系；在刀轴转数和切削圆直径不变时，提高进给速度后，只要相应增加装刀数量，铣削表面粗糙度就不会降低，而切削刃位置精度可以降低；装刀数量不变时，有效切削刃判定值与铣削波纹深度成正比关系；刀轴转数、切削圆直径及进给速度都不变时，切削刃位置精度不随装刀数量的增减而变化。     

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,...     

Effects of cutting parameters on surface quality of paper birch wood machined across the grain with two planing techniques

Helical planing and face milling were applied across the grain to surface paper birch wood prior to coating application. Three feed speeds and three cutting depths were evaluated for face milling while three cutting depths were studied for helical planing. The roughness and wetting properties of wood as well as pull-off strength of a solvent-borne coating after aging were evaluated. For helical planing, no significant effects of the cutting depth on roughness and wetting properties were found. For face milling, the cutting depth had no significant effect on the surface roughness while it had a significant impact on the wetting properties. The feed speed affected significantly both parameters. Furthermore, none of these parameters had a significant effect on the pull-off strength. However, helical planing produced smoother surfaces with equivalent wetting properties and higher pull-off strength than face milling. Scanning electron microscopy showed more exposed cell lumina and sound cells for helical planed surfaces, which enhanced their wetting and adhesion properties.     

Vitamin status of diamond cutters

Workers engaged in industrial treatment of diamonds manifested deficient supply of ascorbic acid, thiamine, riboflavin, pyridoxine and niacin in spring and autumn. This was ascertained on the basis of studying actual nutrition and specific indicators of the content of vitamins or their catabolites in the urine and blood and determination of metabolic functions of some vitamin-dependent enzymes.     

切纸机发展现状及市场需求

随着印前和印刷工艺及设备的迅速发展,人们将注意力开始转向印后方面,并逐渐形成了新的发展热点.在数字化、网络化发展异常迅猛的今天,在印后加工设备中,切纸机械的发展格外引人注目.     

废弃纺织品纤维与木浆配抄纸的性能

为探讨废弃纺织品作为原料在现代造纸工业中的应用,按照原料和颜色深浅把废弃纺织品分为4类:合成纤维(浅色)、纤维素纤维(浅色)、纤维素纤维(深色)、纯棉纤维(浅色),将原料经粉碎工序加工成散纤维,分别与木浆配抄成手抄纸,分析了配抄纸的各项物理性能。结果表明,手抄纸具有优异的透气性能,透气度为91.70~100.00μm/(Pa·s),是木浆(对比样)手抄纸的9.6~10.44倍;力学性能低于木浆手抄纸,是木浆手抄纸的27.8%~55.6%;废弃纺织纤维与木浆配抄纸的白度与纺织品纤维原来的颜色相关。