磨削加工方式的合理组合

根据磨削加工中所用砂光机砂削机构与木材工件作用方式和最终加工效果的不同,磨削加工可分为定厚磨削与定量磨削两种方式。如果根据被加工对象和加工要求的不同,磨削加工可分为基材尺寸精确校准、基材表面修整和装饰板表面修整三种形式。其中基材的尺寸精确校准加工需使...     

木纤维增强氧化镁复合材料锥形铣削性能研究

木质纤维增强氧化镁复合材料(WRMC)作为一种新型建筑装饰装修材料,其以优异的物理力学性能被应用于建筑装饰领域。本文研究了在对WRMC的锥形铣削过程中,铣削参数(锥度角、铣削深度和铣削速度)对切削力和加工后工件表面粗糙度的影响。结果表明:切削力与铣削深度呈正相关,与锥度角、铣削速度呈负相关。表面粗糙度随着铣削深度的增加而增大,随着锥度角和铣削速度的增加而减小。综合分析得到对WRMC的优化切削参数组合:锥度角为75°,铣削速度为45 m/s,铣削深度为0.5 mm,切削力和工件表面粗糙度分别为50.24 N和2.11μm。     

基于三维表面形貌测定法的水切割木竹材工艺参数优化

为优化木竹材超高压水射流切割加工工艺参数,以红橡木和竹地板为对象,采用正交试验法,研究磨料流速、切割压力、进给速度、靶距对水射流加工试件表面粗糙度的影响,探索优化工艺参数。利用扫描探针式三维表面形貌测定法测量试件切割面的表面粗糙度值,分析三维表面形貌图。结果表明:红橡木磨料射流的试验影响因素排序为CADB;竹地板磨料射流的试验影响因素排序为BCAD。红橡木和竹地板优化工艺参数为:进给速度为250 mm/s,磨料流速为35 kg/h,靶距3 mm,切割压力为310 MPa。在此加工工艺条件下切割材料表面粗糙度相对较小,加工所得材料品质较好。     

木工刨床刀轴和刀片的改进

１加工现状分析 目前，国内木工刨床的刀轴多是圆柱形的，刀具是直线刀片，切削部分由高速旋转的刀轴和直线刀片组成，其结构如图１所示。 直线状的刀片、刀刃，在加工时同时进入和离开切削，其切削过程是断续的，负载时大时小，概括起来有以下缺点。１．１对产品加工质量的影响 断续切削使加工木材表面产生波纹，影响表面粗糙度和形状精度。主要是平面度精度低，表面较粗糙，加工质量差。１．２对设备的影响 断续切削使负载大小变化频繁，有冲击力，使被加工工件和设备产生振动，既损坏设备，又对其寿命有影响。１．３对刀具的影响 断续切…     

激光加工技术

激光加工技术目前，激光加工技术已经有了迅猛的发展，并且显示出巨大的优越性。其主要特点是：①可以加工包括高硬、高脆材料在内的任何材料，加工迅速，变形极小，具有表面硬化作用，可改善工件的抗磨性和抗压性。②属非接触性加工，可对易于受力变形的工件或材料进行比...     

纳秒脉冲激光烧蚀胡桃楸木的微观形貌分析

以胡桃楸为研究对象,对木材表面进行横纹、顺纹和逆纹3个不同方向的铣削加工,再用纳秒脉冲激光进行烧蚀。借助扫描电镜观察木材微观形貌,分析对比不同加工表面毛刺的物理性状,总结适合胡桃楸的表面加工方法。结果表明:激光烧蚀后的表面较之传统铣削加工的表面更为光滑,而激光烧蚀前对木材进行顺纹铣削能进一步提高胡桃楸表面平整度。     

刀具前角对木塑复合材料加工表面质量的影响

木塑复合材料(WPC)是一种可重复使用的新型环保材料，在其二次加工过程中，表面易出现凹坑、凸起和波纹，致使表面质量差。本文通过分析WPC加工过程中切削力、切削温度和表面粗糙度，研究了刀具前角和每齿进给量对WPC已加工表面质量的影响。结果表明，随着刀具前角的增大，切向切削力Fx和径向切削力Fy、切削温度逐渐减小，表面粗糙度值逐渐降低，提高了已加工工件表面质量。切向切削力Fx和径向切削力Fy随着每齿进给量的增大而增大，切削温度和表面粗糙度值随着每齿进给量的增大而降低。在高切削力和低切削温度情况下，已加工工件表面质量更优，但同时也出现了能耗高的问题，通过对切削参数的调整来改善以上的问题，对WPC的二次加工提供理论依据指导。     

数控超高压水切割机床的工件夹紧装置研究设计

基于提高超高压水射流切割机床加工木材和木质复合材料质量需要,依据动力学实验原理,以杉木为试件,采用动压力测试方法分别对杉木工件在自由状态下切割受力情况和对不同规格的杉木工件在自由状态与夹紧状态下的切割表面粗糙度进行了对比试验研究,并以此设计了与SQ-WJG40型高压水射流切割机床相配套的四气缸联动气压夹紧装置.     

窿缘桉木材刨削和砂光后的微观破坏形式

以窿缘桉木材为研究对象,对其刨削和砂光处理后的加工缺陷和无缺陷表面采用扫描电子显微镜观察,结果表明:窿缘桉木材刨削加工缺陷处的微观破坏形式为纤维和木射线的撕裂和切断,其中纤维破坏是最主要的破坏形式。而在正常刨削处,主要表现为表层木材组织的大量压溃。砂光后的木材表面,在缺陷处和无缺陷处,其微观表现形式均为组织压溃。     

木材加工中冲孔代替钻孔的试验和研究

一、导言 在工业性木材加工中,钻孔是除了铣削、锯切和砂光之外最重要的加工工艺.虽然有相当多的科研项目进行提高钻孔工效的研究,但这方面仍旧有较大的开发空间.现在,工业性木材加工(如:家具、窗户、门的生产)所用行进加工式和固定加工式机器的最高进给速度已达150 m/min,因此其工件流通量很大.钻孔工序可能对行进加工式机器产生不利影响,常限制其工件流通量和生产率,因钻孔时工件必须停住,以便可以用较低的进给速度进行钻孔.应当指出,通过改善传统的钻孔装置并不能明显地提高机器的生产率,因为在钻头每转进给量相同情况下提高钻轴转速虽然可较明显地缩短工艺时间,但传统机器钻头轴向加速度太小,影响其生产率.另外,高转速使刀具磨损增大.     

基于三维显微系统的木材切削表面粗糙度分析

以榆木、杨木和松木为试验材料,采用不同的测试模式、木材切面、放大倍数和切削加工方式对切削表面粗糙度进行测定评价,比较分析上述因素的影响。结果表明:测定模式对于粗糙度值有一定影响;同一树种、同一切面时,磨削表面粗糙度明显低于锯切和旋切,表面粗糙度值为锯切>旋切>磨削;榆木磨削加工中,显微构造明显部位的三切面粗糙度值为径切面>弦切面>横切面;放大倍数与木材显微构造有关,对表面粗糙度值有影响。基于试验结果提出,木材切削表面粗糙度测定评价宜采用先选定被测试件的评价部位,再确定满足精度等级的测试模式的两步法进行。     

砂带磨削效率的实验研究

以杨木、水曲柳和中密度纤维板为试材,使用磨削效率测试系统和表面粗糙度测量仪进行磨削实验,分析比较了三种试材磨削效率和表面粗糙度的变化规律,以及相关因素对磨削效率和表面粗糙度的影响。结果表明,在其他条件不变的情况下,杨木的磨削效率高于水曲柳的磨削效率,中密度纤维板的磨削效率最低;横向磨削的磨削效率高于纵向磨削的磨削效率;杨木的表面粗糙度数值Ra高于水曲柳的Ra,中密度纤维板的Ra最高;横向磨削的表面粗糙度数值Ra高于纵向磨削的Ra。     

A comparison of selected acoustic signal analysis techniques to evaluate wood surface roughness produced during routing

This study examines the applicability of several signal analyzing methods applied to audio signals to establish relationships between audio signals generated during machining and the surface roughness produced. One-third octave passband filters were also used to condition audio signals acquired during routing of Japanese beech (Fagus crenata Blume) at different machining conditions. The one-third octave analysis was essential for gaining satisfactory results. Three different analyzing strategies were investigated: the RMS averaging method and the count rate method combined with static and dynamic thresholds. The count rate method at constant threshold could not be applied to the sound intensity signal due to its substantial range in magnitude during machining at different states, although the dynamic threshold strategy can be applied to both the sound intensity and the sound pressure signals, and adjusts flexibly to the variable signal generated. Linear regression of data obtained during each of the analyzing strategies shows that the RMS averaging method is most suitable for analyzing audio signals, as shown by its highest correlation coefficient with surface roughness produced. The results suggest that measurement of sound intensity is a promising method for monitoring surface roughness and determining optimum feed rates.     

木材机械加工表面粗糙度的激光在线检测系统

介绍了一种采用计算机控制激光位移传感器在线检测木材机械加工表面粗糙度的新方法。该系统由计算机、模数转换板(A/D板)、激光传感器测量系统(激光头及激光控制器)等组成,试验研究是在木材加工CNC(Computer Numerical Control)装置上进行的。文中给出了硬件结构、软件程序设计流程图及木材表面粗糙度在线检测的实验数据。     

基于圆柱面投影的树干表面重建算法

[目的]树干在林业生产与科研中具有重要的地位,树干表面重建对森林可视化与树干参数提取具有重要意义,本研究以重建树干的精确表面模型为目的。[方法]提出了一种基于圆柱面投影的树干表面重建算法,算法以连续的多个树干分段为重建单元,以重建单元的质心与直径构建圆柱面,通过将树干点云投影至圆柱面,再将圆柱面点云延伸展开得到平面点集,由平面点集Delaunay三角网的连接关系构建重建单元的不规则三角网表面,连接相邻重建单元的树干表面以获取树干整体的表面模型。[结果]在树皮粗糙程度各异的3种树干点云上的实验表明:重建的树干表面能清晰地展示外业时标注的信息,能有效地反映树干表面的褶皱凸凹特征,具有更好的可视化效果;通过从重建表面上定量提取直径的精确性评价表明:与围尺实测直径相比,从本文提出的基于圆柱面投影重建的树干表面上提取树干直径的RMSE为0.14 cm,比基于切平面投影重建方法更精确。[结论]本文提出的算法是一种简单高效的树干表面重建算法,无需计算法向量、重建的树干表面上三角形数量较少,且能有效地还原树干表面的凸凹特征,适用于树干表面的精确重建、精确可视化与树干参数提取。     

基于单片机的木材表面粗糙度激光在线检测系统

介绍一种用单片机控制激光位移传感器进行在线检测木材机械加工表面粗糙度的新方法.该系统由单片机、模数转换器和激光传感器测量系统(激光头及激光控制器)等组成,试验在木材加工CNC装置上进行.文中给出了硬件结构及软件程序设计流程图.     

Effect of Cutting Speed on Surface Quality by Bandsawing

Introducti0nSincetI1ebandsa\`canbequickl}'andaccLIratel}'setal1dtllereisvirtuaII};noupper-sizeIilnitinIogdiameter,tI1emachinecanberegardedasthemosleffectiveaII-r0undmachine.Lumbermillsshowgro\"inginterestintI1ebal1dsawingconceptduetotl1el1ighthroLIghputan…     

Characteristics of sugar maple wood surfaces machined with the fixed-oblique knife pressure-bar cutting system

Oblique cutting differs from orthogonal cutting by an inclination given to the knife edge, which induces several changes on tool geometry, cutting forces, as well as on the quality of machined surfaces. In this work, a pressure bar was used during oblique cutting to reduce the occurrence of torn grain. The effects of cutting depth, rake angle, and oblique angle on cutting forces and surface quality were studied. Surface topography, cell damage and wetting properties were used to assess surface quality. All force components were increased by increasing cutting depth and decreasing rake and oblique angles. The lateral force, however, increased as the oblique angle increased. The surface roughness increased with increasing the lateral cutting force. Higher cutting depths and oblique angles tended to provide higher surface roughness, while higher rake angles tended to reduce surface roughness. The pressure bar was not always able to completely prevent the occurrence of defects when cutting against the grain. The occurrence of machining defects increased at higher cutting depths and oblique angles. As the rake angle decreased, the type of machining defect tended to change from torn grain to slight fuzzy grain. Moreover, the best wetting properties were obtained at lower rake angles, as they induced higher surface roughness. A 25° rake angle, a 30° oblique angle, and thinner cutting depths should be preferred to reduce dependence on ulterior sanding.     

Toward a process monitoring of CNC wood router. Sensor selection and surface roughness prediction

The measurement of wood surface roughness is performed once the machining process is completed. It requires considerable time since the measurement is performed at slow speed. The objective of this study was to develop a method to evaluate the surface roughness of paper birch wood while routing. For this purpose, a number of transducers were mounted on the router spindle and also in the proximity of the workpiece and cutting zone. Signals were acquired during a wide range of cutting conditions and analyzed. Statistical regression and artificial neural networks were employed to establish relationships between the signals and the actual cutting depth and surface roughness. The sensor selection and the feasibility of the sensor placement were determined. The models were subjected to a validation procedure to confirm their performance. The placement of the microphone at constant distance from the cutting zone was determined to be the most useful one. A model able to predict the surface roughness of routed paper birch wood regardless of the depth of cut was produced. The performance of the model was valid independently of the length of the workpiece.