Research on Cutting Force of Ultrasonic Diamond Wire Saw

Based on impulse and vibration machining theories,a mathematical model of cutting force for the electroplated diamond ultrasonic wire saw was established using superposition principle.The differences between the cutting forces with and without ultrasonic effect were analyzed theoretically and experimentally.The results indicate that the cutting force of diamond wire increases along with the spindle speed decrease and the lateral pressure increase.The force in ultrasonic vibration cutting is about 20% to 30% less than that in conventional cutting.Also,the cutting trajectory of single diamond grit in sawing process is simulated,and the reason that the ultrasonic vibration can reduce the cutting force is explained further.

Preparation and Optimization of High-Purity Silicon Carbide Magnetic Abrasives for the Magnetic Induction-Wire Sawing Process

In this study,magnetic abrasives were obtained by crushing and sieving sintered iron-silicon carbide(Fe-SiC)composites.Fe and SiC powders with different mesh numbers were pre-compacted using different pressures and then sintered at various temperatures and with different holding times.The dispersion uniformity of the SiC powder was improved through surface modification using polyethylene glycol(PEG)300.The resulting magnetic abrasives were characterized in terms of phase composition,density,relative permeability,and microstructure;this was followed by a comprehensive analysis to reveal the optimal processing parameters.The ideal combination of process parameters for preparing SiC magnetic-abrasive grains for the magnetic induction-wire sawing process was obtained,which are preparation load of 60 kN,a SiC mesh number of 1,500,a sintering temperature of 1100℃,and a holding time of 4 h.

Force Modeling for Ultrasonic-assisted Wire Saw Cutting SiC Monocryatal Wafers

The advantages, such as a small cutting force, narrow kerf and little material waste make wire saw cut- ting suitable for machining precious materials like SiC, Si monocrystal and a variety of gem. As regards wire saw cutting fo wafer, however, in traditional wire saw cutting process, the cutting efficiency is low, the wear of wire saw is badly, the surface roughness of wafer is poor etc, which have a seriously impact on the cutting process stability and the use of wafers. Ultrasonic-assisted machining method is very suitable for processing a variety of non-conduc- tive hard and brittle materials, glass, ceramics, quartz, silicon, precious stones and diamonds, etc. In this paper, the force model of ultrusonic-assisted wire saw cutting of SiC monocrystal wafer, based on the kinematic and experi- mental analysis were established. The single factor and orthogonal experimental scheme for different processing pa- rameters such as wire saw speed, part rotation speed of and part feed rate, were carried out in traditional wire saw and ultrasonic-assisted wire saw cutting process. The multiple linear regression method is used to establish the static model among the cutting force, processing parameters and ultrasonic vibration parameters, and the model signifi- cance is verified. The results show, as regards ultrasonic-assisted wire saw cutting of SiC monicrystal wafer, both the tangential and normal cutting forces can reduce about 24. 5%-36% and 36. 6%-40%.

Research on Cutting Trajectory of Electroplated Diamond Wire Saw

The cutting process of electroplated diamond wire saw was researched on the basis of impulse and vibration machining theories. The different contact states in the cutting process were analyzed by using the finite element method. It shows that the cutting stress is uniformly distributed along the direction of the workpiece width in the steady state. A mathematical equation of sawing trajectory was established by using the superposition principle and the cutting experiment of wire saw to calculate the cutting trajectory. The comparison of the theoretical trajectory with the calculated one indicates that the error is less than 15%. The research results provide a theoretic basis for optimization of the saw's cutting process parameters.

Microstructure and mechanical properties of heat-affected zone of 680 MPa grade steel endured thermal cycle of double-wire SAW

Based on the measured thermal cycle of double-wire submerged arc welding （SAW）, the gleeble thermal test was performed. Meanwhile, the Charpy V-notch impact test at -50 ℃ and hardness test at room temperature were carried out after the thermal test. Thermally cycled microstructure and fracture surfaces were observed too. The results indicate that impact toughness of heat-affected zone （HAZ） at -50 ℃ is lower than that of parent metal with different wire spacing and welding speed. The microstracture of coarse-grains heat-affected zone （ CGHAZ ） is mainly made up of lath bainite with serious brittleness. The study also shows that a smaller energy input could be adopted to ensure the toughness of welded joints at the welding process in a common molten pool, while a higher energy input could be exerted to enhance welding efficieney at the welding process in two separate molten pools.

Experimental study of free abrasive wire sawing by using multi-strands wire

Grains in the slurry can be brought into cutting zone by steel wire with a certain speed to achieve the purpose of removing the workpiece material in the free abrasive wire sawing machining. Because its own of multi- strands characteristics, we use it to replace the steel wire to do slicing experiment. In this paper, multi-strands wire is made by seven metal wires and has many grooves on its surface. Compared with steel wire, it can carry more grains into cutting zone which is conducive to improving the slicing efficiency. We do some comparative slic- ing experimcnts by applying multi-strands wire （~b0.25 mm） and steel wire （~b0.25 mm） to cut optical glass （K9）. The results show that slicing efficiency and the surface roughness of the workpiece sliced by using multi-strands wire are better than that by using steel wire. but the kerf width of the former is wider than that of the latter in the same experimental conditions.

Twin-wire SAW welding of 70 kg class high strength steel

The twin-wire SAW welding process was investigated using Baosteel 70 kg class high strength steel, and the properties of the joints were studied using conventional single and double-faced grooves as well as an optimized groove. The results showed that by using an optimized double-faced groove, a small root face, and no back gouging, a small welding heat input was achieved and thus the joint strength and toughness were improved significantly. Also, removing back gouging reduced the labor required in the process. The weld reinforcement and deformation were observed to be rather small.

A Study on a Wire Tension Adaptive Control System of a Multi-wire Saw in Computer Simulation

Based on the analysis of the mechanism of wire tension control by using torque motors in the multi-wire saw machining process, some mathematical models of a tension control system are studied, and an adaptive algo- rithm is designed for controlling the wire tension. In this algorithm of tension control, the rotation speeds and waving angle of motors are measured and fed back to the controller, and the NLMS（ normalized least mean squares） algorithm is used to calculate the adaptive correction value and control the wire tension accurately. The computer simulation results in Matlab software validate the high accuracy for controlling the system of the wire tension with the NLMS algorithm in the multi-wire saw machining process.

Experimental Study on the Machining Technology of ZrO_2 Ceramics Using Diamond Wire Saw with Ultrasonic Vibration

The influence of different technological parameter on material remove rate and surface quality of ZrO2 ceramics is studied using the cutting machining method of electroplate diamond wire saw with ultrasonic vibration.Experimental results show that,compared with the same experiment condition without ultrasonic vibration,this cutting method has the advantages of high material remove rate,good surface quality,little brokenness and so on.

Sawing Performance Comparison of Brazed and Sintered Diamond Wires

Great attention has been paid on fabricating diamond wire by using the brazing diamond because of its strong chemical bonding strength and controllability of grits distribution. Although several serving performances of brazed diamond wire have been reported, seldom do these studies refer to its process characteristics. Sawing performances of a brazed diamond wire are investigated and compared with those of a sintered diamond wire on a wire saw machine. The surface topographies of beads selected from the two wires are micro observed before sawing. The sawing tests are carried out in constant feed rate feeding（CFF） and constant normal force feeding（CNFF）. In CFF test, sawing force, power, and the cut depths of positions on contact curve are measured. Then, coupled with the observations of beads topographies, sawing force and its ratio, relations of power against material removal rate, and contact curve linearity are compared and discussed. In CNFF test, the sawing rates of the two wires are investigated. The results indicate that the brazed wire performs with lower sawing force（less 16% of tangential force and 28% of normal force）, more energy efficiency（nearly one-fifth of sawing power is saved）, at a higher sawing rate （the rate is doubled） and with better contact curve linearity as compared with the sintered wire. This proposed research experimentally evaluates the sawing performances of brazed diamond wire from the aspect of process parameters, which can provide a basis for popularizing the brazed diamond wire.

Study on swarf when sawing granite with diamond wire

The diamond wire-sawing process was developed to cut granite in both quarries and block processing plants.In this paper,swarf was collected from different areas along the sawing arc when sawing three granites.The particle size distribution and the morphology of the swarf were investigated systematically,along with the swarf formation mechanism in sawing.Granite swarf formation was dominated by transgranular fractures based on the morphology of sawn granite chips and the analysis of sawn chip size.A long cutting arc increased the movement among the swarf,tool,and workpiece,thereby inducing a secondary fracture in the sawn chip.

线锯用金刚石微粉表面化学镀镍工艺及性能研究

金刚石微粉性能是提升金刚石线锯性能的关键因素。用化学镀方法在线锯用金刚石微粉表面镀镍,通过正交试验研究金刚石粒度、次亚磷酸钠浓度、镀液pH值和镀液温度对化学镀镀层沉积速率、镀层密度、镀层耐腐蚀性能、镀层致密度等性能的影响。结果表明:M1/2、M6/12、M20/30三种不同粒度金刚石微粉,在次亚磷酸钠浓度为25~35g/L、化学镀液pH值为3~11、化学镀温度为30℃~90℃时,针对镀层沉积速率、镀层密度和镀层耐腐蚀性的最佳工艺参数不同;不同粒度的金刚石微粉在相同工艺条件下化学镀镍,金刚石微粉粒度越大,镀层越均匀致密;金刚石微粉化学镀镍各工艺参数之间相互作用,共同影响镀层性能。对于不同粒度的金刚石微粉,各因素对镀层性能的影响权重不同,因此针对不同粒度、不同镀层性能需求的金刚石微粉应采取不同的镀覆工艺参数。

基于小样本数据驱动模型的硅片线切割质量预测

在单晶硅加工中,硅片多线切割质量检测耗时和检测成本高造成硅片质量检测难。因此,提出一种基于生成对抗网络(WGAN-GP)数据处理与自注意力残差网络(SeResNet)的硅片质量预测方法。分析多线切割的机制,确定影响硅片质量的工艺参数,建立数据样本,使用WGAN-GP对样本数据进行数据增强。在此基础上,建立基于SeResNet的硅片总体厚度偏差预测模型。以硅片的多线切割加工过程监控数据为模型验证数据,对构建的硅片总体厚度偏差预测模型进行验证。实验结果表明:该模型具有良好泛化性和高准确率,有效解决了小样本数据下的预测难题,实现了平均相对误差小于10%的硅片总体厚度偏差预测,所以基于数据驱动的硅片质量预测来代替硅片加工中的质量检测具有重要的现实意义。

晶硅太阳能电池制备过程中硅渣和金刚石线切割硅废料的回收利用研究进展

随着晶硅太阳能电池的快速发展,晶体硅片的需求大幅增加。晶体硅片在生产制备过程中,大量的硅以硅渣和金刚石线切割硅废料的形式流失。硅渣和金刚石线切割硅废料中硅的回收再循环利用对降低晶硅太阳能电池的成产成本、有效解决晶体硅片短缺以及环境污染等问题具有重要意义。本文通过对从硅渣和金刚石线切割硅废料中回收制备高纯硅的现有工艺和研究进展进行综述,对不同回收工艺的优势、缺陷以及改进措施进行分析,有助于研究人员选择合理的高纯硅回收策略,为晶硅太阳能电池产业的低成本、绿色可持续发展提供参考。

无润滑条件下工艺参数对Al6063金刚石线切表面粗糙度影响

金刚石线锯因具有超高的硬度和耐磨性,常用于切削各种硬质材料,因加工过程摩擦较为剧烈,通常加冷却润滑介质,但一些特殊需求下,铝合金需要线切时无法施加冷却液。基于单因素试验法,在无润滑条件下进行了Al6063材料的线锯试验,分析了加工表面不同区域粗糙度的分布规律以及配重、线速度与进给速度对加工表面粗糙度的影响规律。结果表明,加工面中间位置表面粗糙度最大;在试验范围内配重越大,对应的表面粗糙度值越小;金刚石线锯线速度越大,其表面粗糙度值越小;进给速度越小,所对应的表面粗糙度值越小。试验结果对提高加工表面质量有实际参考价值。

基坑盖板下逆作车站地下连续墙托换破除技术

附属结构与地铁车站连通常需要对地下连续墙进行破除,当地下连续墙上设有临时承重盖板时破除的施工难度更大,风险更高。以某地铁盖挖逆作车站的地下连续墙破除施工为依托,提出了利用局部破除体作为临时竖向支撑进行托换破除的施工方法。首先,采用数值计算分析了不同托换间距对盖板结构体系的受力影响,综合施工进度和作业空间考虑,确定预留1m宽的临时托换柱和不大于12m的破除间距为控制指标,能够满足各受力结构体系在临时托换施工下的承载性能要求;其次,对盖板下地下连续墙破除及切割块转运施工进行了详细分析,给出了分块尺寸、切割块吊装、预留柱节点等关键施工环节的控制指标与做法。实施结果表明:利用既有地下连续墙作为临时托换结构进行破除地下连续墙的施工方法,安全可靠,施工速度快,成本经济。

金刚石串珠绳锯切割煤层卸压增透效应研究

为探讨金刚石串珠绳锯割缝对缝槽周围煤层的卸压增透效应,首先建立基于缝槽顶板受力的两端固支梁力学模型,分析顶板梁的受力特征及缝槽顶板下沉接触底板(简称触底)特性,然后采用自行设计的物理相似模拟试验平台开展相似模拟试验,分析不同工艺参数绳锯割缝后缝槽上下方煤岩层应力、位移变化规律,基于FLAC^(3D)数值模拟和开发的煤层瓦斯渗透率计算程序,分析随割煤工作面推进缝槽周围煤岩体的应力和渗透率分布特征和周期演化规律。研究表明:绳锯割缝使缝槽周围应力重新分布,缝槽顶板随着割缝工作面的推进经过顶板悬露、顶板触底,连续缓沉3种演化形态;顶板未触底时,缝槽上下方形成“U”形卸压区,最大挠度在顶板中心位置,也是最先触底部位,顶板触底之后,缝槽中间位置出现应力恢复,减弱绳锯割缝的卸压增透效果;串珠绳锯的直径越大,顶板发生触底的极限跨度越大,缝槽触底越晚,卸压效果越好;相同割缝直径增加第2条割缝,两缝槽卸压区连成一起,卸压效果相互促进,减弱两缝作用下的应力恢复现象,增大了卸压范围;缝槽推进距离足够长时,由于顶板触底,缝槽两边的卸压增透效果更好,割缝卸压的影响范围从左到右划分为应力集中区、卸压区、应力恢复区、卸压区、应力集中区,对应的卸压区和应力恢复区都有较好的增透效果。

X60钢级Ф559 mm×32 mm直缝焊管预热多丝埋弧焊试验研究

为了提高直缝埋弧焊管多丝埋弧焊接速度,采用预热四丝埋弧焊接工艺进行了X60钢级Ф559 mm×32 mm规格钢管焊接对比试验,并与常规四丝埋弧焊工艺进行对比。对比试验发现,与常规四丝埋弧焊工艺相比,采用预热四丝埋弧焊工艺时,可提高焊接速度20%,降低焊接线能量10%,整体力学性能优。证明预热多丝埋弧焊工艺在保证焊缝质量、力学性能的前提下,可以显著提高直缝埋弧焊管的焊接速度,是一种优质、高效、节能的埋弧焊新工艺。

高速铁路隧道轨道板上拱切割落道施工技术

某隧道仰拱在地质构造应力及承压富水环境的综合作用下,CRTSⅠ型双块式无砟轨道道床板出现上拱变形和平面移位,最大上拱变形值达47.1 mm,最大横向移位达10 mm,超出常规扣件可精调的范围。本文提出了一种利用绳锯切割仰拱填充(即找平层),以实现道床板与下部隧道结构分离落道的施工方法,利用千斤顶、水平顶推装置、气垫等方式进行道床板平面位置或高程姿态调整。结果表明:该技术避免了因道床板及仰拱填充层大拆大换造成的行车中断,降低了拆除和重建成本,保证了无砟轨道结构整体性受力,经济、社会效益显著。研究成果可为类似道床板线性大尺度偏位处理提供借鉴。

多线摇摆往复式线锯切割蓝宝石法向力试验研究

多线摇摆往复式线锯切割加工是目前将蓝宝石晶棒切割成晶圆衬底的主要加工方法,加工过程中法向切割力是反映加工过程稳定性的重要指标。测量了多线摇摆往复式线锯切割蓝宝石晶棒过程中产生的法向力F_(n),跟踪了晶棒不同位置和不同切割深度下法向力的变化规律,以法向力变化幅值ΔF_(n)为指标,探究各种工艺参数对加工过程稳定性的影响。试验结果表明:法向力F_(n)与线锯的往复运动、工件的摇摆运动有明确的对应关系,晶棒前端的ΔF_(n)与中后端的有明显的不同。线速度V_(s)、最大摇摆角度θ_(max)、单片耗线量M_(d)、张紧力F_(w)、总切割时间T等工艺参数对ΔF_(n)有着不同的影响。ΔF_(n)的波动程度与线锯磨损有着密切的关系。