铣削刀具不同磨损期振动信号的分维特征

提出了应用铣削刀具磨损工作状态下的振动加速度信号的关联维数来描述刀具不同磨损状态下的特征,进而实现对状态的监测、识别。试验证明,刀具磨损在相同状态下,振动信号具有相近的关联维数,在不同状态下则有明显的关联维数。因此,关联维数不仅可以作为状态监测与识别的重要依据,而且可以作为其他特征提取方法的补充。     

缓释复方免疫增强剂有效药物释放量及安全性试验

将100只14日龄健康肉杂仔鸡随机分成A、B、C、D、E 5个试验组,每组20只鸡,A、B、C、D 4组为试验组,E组为对照组。A、B、C 3组试验鸡每只分别投服批号为0308、0312、0402的缓释复方免疫增强剂1粒,进行有效药物释放量测定试验,试验结果表明,药物投服后日均磨损量20d前为6.2~6.7 mg,30 d前为6.0~6.3 mg,日均药物有效释放量为2.40~2.52 mg,经方差分析,批间差异不显著(P0.05),均在有效剂量之间,药物的有效释放期均在30 d以上。D组试验鸡每只投服缓释复方免疫增强剂3粒,进行有效药物安全性试验,试验结果表明,仔鸡投服后食、饮欲正常,精神状态良好,与对照组鸡相比未发现任何不良反应,从而说明该缓释制剂在鸡体内是安全有效的。     

耕整播农机装备触土部件表面耐磨强化研究进展

耕整播农机装备是影响中国耕地耕种作业质量与效益的关键农机装备,随着农业机械化的快速发展,耕整播农机装备对其配套的旋耕刀、犁铧、深松铲、耙片、开沟器等触土部件耐磨性和使用寿命提出了更高的要求。该研究系统分析了触土部件主要的磨损失效形式及磨损机理,综述了提高触土部件耐磨性常用的表面熔覆、表面堆焊处理、表面热喷涂、激光表面强化处理、化学热处理、钎涂等表面处理工艺,从磨损机理、材料研发、结构设计和制造工艺4个方面对比分析了国内外技术差距,针对现阶段耕整播触土部件失效机理、材料、结构、工艺等短板环节的难点问题,展望农机触土部件未来研发方向,拟为表面耐磨强化的相关研究和工程应用提供理论依据与技术支撑。     

Assessment of wood particleboards milling by means of energy consumption tests

In this paper, an experimental procedure is proposed, in order to evaluate the machinability of different particleboards. A dedicated test stand has been built to measure the power consumption during the process for different typologies of particleboards. This methodology could constitute a quick particleboard grading system, in order to maximise the feeding rate during the working process, and, at the same time, minimise the tool wear and the loads on the shaft of the electrical spindle, with a considerable improvement in the overall production costs.     

Agricultural residues in panel production – Impact of silica particle content and morphology on tool wear

Abstract

Considering ongoing global deforestation and the increased demand for raw materials in all wood-processing sectors it is necessary to seek and employ alternative resources. Agricultural residues are potential sources of alternative lignocellulose-based raw materials. Research on substitute materials for wood panel production mainly focused on physical and mechanical properties of boards while much remains to be learned about machining. Therefore, studies were carried out to analyse the relationship between ash and silica content and their impact on tool wear. Ash and silica contents of agricultural residues were determined following ISO 3340. Particle morphology and elemental composition of selected materials were analysed using scanning electron microscopy and energy-dispersive X-ray analysis. Tool wear tests were carried out using particleboards made from wheat straw, canola straw and spruce. Analyses of various plant materials displayed no correlation between ash and silica content. Bio-mineralised silica structures in wheat and canola were different compared to coarse silica found in wood-based particleboard. Tool wear caused by these agricultural residues was just moderately increased compared to wood, despite the fact that their silica contents were many times higher. Furthermore, the impact of abrasive substances on wear behaviour was influenced by the density of the panels.     

整体硬质合金螺旋木工铣刀的合理选用

从刀具旋向特点、加工方式、切削参数以及刀具磨损等方面介绍整体硬质合金螺旋木工铣刀的应用和选择。     

强化木地板耐磨性能及国产化耐磨纸的研究

对强化木地板的耐磨性能和国产化耐磨纸进行了研究,重点考察耐磨纸的生产方式和热压工艺过程对产品耐磨转数和磨耗量的影响。结果表明Al2O3添加量和添加方式对产品的耐磨性能有很大影响,新研制的B型耐磨纸和进口耐磨纸有相似的磨损曲线,其耐磨转数与Al2O3添加量之间呈线性正相关,耐磨转数的增加主要表现在延长第二磨损区域,即提高初始磨损的IP值。热压工艺过程与产品的耐磨性能之间无明确关系。     

发动机汽缸磨损原因及创新维修实践总结

汽缸的状态直接决定了发动机的性能,在汽车使用过程中,汽缸会因为多种因素的影响而产生磨损问题,严重的磨损会直接影响汽车的动力性能及排放质量。通过介绍汽缸磨损的危害,分析了磨损问题产生的原因,并说明了汽缸磨损的检测方法与维修实例,总结了预防汽缸磨损的相关方案。     

Experimental study on landscape of CFRP cutting by abrasive water jet

To investigate the influence of operation parameters of abrasive water jet on surface roughness of carbon fiber reinforced plastic(CFRP),experimental studies were conducted.The three-dimensional landscape of cutting front was reconstructed according to the measured data byμscan laser confocal microscopy.Fourier spectral analysis was also adopted to study surface structure in detail.It is found that the morphology of cutting front is similar to that of other materials.In the smooth cutting zone,the fluctuation of amplitudes of surface profile is gentler,compared with that in the rough cutting zone.The lower part of the rough cutting zone was characterized by the periodical appearance of peaks and valleys.The roughness of surface increases with the increase of depth.While in the smooth cutting zone and part of rough cutting zone,roughness increases with the increase of traverse speed.For the thickness of samples,in the smooth cutting zone,the roughness increases with the increase of depth.The dominant harmonic component in the surface profile is concentrated in a narrow range from 0 to 10 Hz,and the relatively higher density of frequency from 10 to 50 Hz is shown in the rough cutting zone,which is caused by the interaction between perpendicular abrasive water jet and reflect jet.     

叉车轮胎的非正常磨损及预防

叉车的使用因素、行车机构技术状况、驾驶技术等影响叉车轮胎的非正常磨损，应通过加强轮胎维护、提高底盘维护质量、合理选择和搭配轮胎等加以预防。