新型金刚石锯片研究

本文研制开发了一种既锋利又耐磨的新型金刚石锯片,其主要成分为Fe-Ni-Cu,探讨了刀具各成分对产品的使用效率和产品性能的影响,提出通过改变配方中的金属粉比例及金刚石的粒度、强度来调节刀头的锋利性和耐用度。试验结果表明:该锯片的寿命平均提高23%,效率提高32%;在制造成本上,刀头粉料成本下降为原成本的42%,提高了锯片在市场上的竞争力。     

硬脆材料切割过程中基于线锯速度的切割力自适应控制

光学玻璃、工程陶瓷以及硅基材料等硬脆材料因其良好的物理性质和化学性质而广泛应用于光学工程及集成电路等高尖端技术领域,但低塑性、高脆性的物理特性会导致其切片在切割过程中易出现效率低和表面质量较差等问题。为提高切片表面质量,建立了金刚石线锯切割过程中线锯速度与切割力的模型,设计最小方差自校正控制器对切割力进行在线实时控制。实验结果表明：所设计的最小方差自校正器能够降低线锯切割系统中切片所受的切割力波动,使切割力趋于稳定;与定参数切割条件下所得的切片进行比较,采用最小方差自校正控制策略切割完成的工件表面形貌较为平整,表面粗糙度值降低约30%.     

某建筑上部高耸构筑物拆除施工工艺

既有建筑高耸构筑物部分的拆除不同于一般破碎拆除,为避免对下部结构的破坏,需采用保护性静力拆除,同时受周边环境及空间的影响,拆除施工及废物清运过程中须用到大型且相对灵活的机械和车辆。既有建筑物一般周边环境相对复杂,受相邻建筑物影响,场地空间局限性较大,对各种机械及车辆的约束较多,采用常规机械及拆除方式难以实施。本文以某建筑上高耸构筑物部分拆除工程为例,介绍复杂工况下的高耸构筑物保护性拆除关键施工工艺。     

超声切割SiC单晶时金刚石线锯磨损特性的研究

超声线锯切割SiC单晶时,金刚石线锯的成本仅次于SiC单晶材料本身的成本。建立了超声辅助切割SiC单晶时线锯受力模型,对线锯受力和失效形式进行了理论分析,并进行了相关试验,研究了工件进给速度对线锯偏角、切割方式对线锯磨损、切削液对线锯磨损以及磨粒破坏形式对线锯切割性能的影响规律。结果表明:工件进给速率及超声振幅增大,线锯易被拉断,但过小,切割效率会降低,要想通过增大工件进给速率提高效率,必须提高线锯强度,增大导轮直径,降低线速;超声辅助切割时线锯磨损可降低约40%;与自来水相比,使用Ecocool Resist EP微乳化液后线锯表面堵塞较严重;金刚石磨粒的微小破碎、有利于切割。     

填料对生活垃圾降解及渗滤液水质水量的影响

为了考察在生活垃圾中添加具有吸附性和干燥性的填料对垃圾降解速率、渗滤液产生量、渗滤液水质的影响,在实验室建立了五个圆柱形垃圾厌氧填埋反应器,用于模拟垃圾填埋场的运行情况,以不添加填料反应器作对比,其余四个反应器中分别混合加入锯末、活性炭、沸石、报纸作为填料。实验中对五个反应器中的垃圾层高度、渗滤液产生量、产生渗滤液的COD和NH3-N及重金属离子浓度进行了检测。实验结果表明:在垃圾中添加具有吸附和干燥性的填料具有减少渗滤液产量、加速垃圾降解和减少溶入渗滤液中污染物质的作用,整体来看,锯末在发挥这些作用方面要好于其他三种填料。     

自动切割机桥形工作台的误差分析

以自动切割机桥形工作台为研究对象,针对其高精度要求,通过对其结构的具体分析,系统并详尽地对三轴桥形工作台的各种误差源进行了分析计算;通过高斯公式计算出各驱动轴定位精度误差;介绍了桥形工作台定位精度的测量方法,对理论结果与实测结果进行了分析比较,验证了误差分析结果的正确性,为高精度桥形工作台的设计提供参考。     

圆锯片噪声产生机理及降噪技木

分析了圆锯片噪声产生的机理,同时指出共振噪声是圆锯片噪声的重要组成部分。根据增加圆锯片阻尼、改变圆锯片的共振频率及改变激振力频率可减小振动实现降噪的原理,本文主要分析了多层基体结构、开热胀槽及不等齿距等结构圆锯片的降噪技术。     

数控木工曲线带锯机的研制

介绍了研制开发的MJKS365型数控木工曲线带锯机的工作原理.采用锯机连同带锯条一起以带锯条工作边锯齿齿尖连线为中心作回转摆动的方法,实现带锯条始终沿着锯切曲线的切线方向进行锯切.并依此设计了结构形式和数控系统.     

Free-form curves cutting using flexible circular saw

A flexible circular saw, which can be used in a novel machining process for high-speed carbon fiber-reinforced plastic (CFRP) plate cutting, was developed. In this process, the saw is deflected like a bowl-like shape. A cross-section of the saw body then forms a circular arc. A curved line can therefore be cut without interference by the bowl-like deflection. In addition, the radius of the cross-section of the saw body can be controlled by adjusting the deflection. This process therefore allows curves to be cut with a varied radius using a single saw. This process can carry out high-speed curved-line cutting with a feed rate of 3 m/min on a CFRP plate. However, it is difficult to cut free-form curves using a flexible circular saw. Therefore, in this research, a new technique that can cut free-form curves using a flexible circular saw was proposed. Then, a cutting test applying the technique was carried out.     

Experimental investigation on diamond wire sawing of Si3N4 ceramics considering the evolution of wire cutting performance

When diamond wire saw is used in machining silicon nitride ceramics (Si₃N₄ ceramics), the ultra-hardness of Si₃N₄ causes the saw wire to wear out, which leads to the saw wire cutting performance constantly changing during its life cycle, and thus the machined quality of Si₃N₄ ceramics is affected. Surface roughness and topography are important indicators of the quality of the machined surface. In this paper, the diamond wire saw cutting experiment of Si₃N₄ ceramics was carried out, the effect of the evolution of saw wire cutting performance on the surface roughness and topography of Si₃N₄ ceramics as-sawn slices was investigated based on the analysis of the changes of saw wire wear topography, breaking force, bow angle and kerf loss during the sawing process. The results show that the surface roughness along the saw wire motion direction and the workpiece feed direction tends to decrease and then increase with the evolution of the cutting performance of the saw wire, which accords well with the trend of the as-sawn slices surface morphology. The results of the study can provide experimental reference for the development of high precision diamond wire saw cutting technology for Si₃N₄ ceramics.