环形电镀金刚石线锯对花岗石锯切机理的研究

论述用环形电镀金刚石线锯锯切花岗石时脆、塑性转变的临界条件,研究认为,提高锯丝的锯切速度,有利于花岗石由脆性向塑性转变。用自制的试验设备对花岗石进行锯切试验,试验结果表明,当花岗石的锯切深度小于其脆、塑性转变的临界深度时,花岗石可以实现塑性域锯切,锯切表面光滑,质量较好。     

金刚石圆锯片振动模态及频率可靠性分析

为提高金刚石圆锯片的锯切性能,降低其工作时的振动,防止锯片共振,通过锤击振动试验法,分析锯片固有频率的概率特性.依据结构固有频率与激振频率差的绝对值不超过规定值的关系准则,定义了锯片振动问题的可靠性模式和可靠度,提出避免锯片共振的频率可靠性分析方法.并通过对不同转速下的锯片可靠度的分析,得到了防止共振的工作转速,提高了金刚石圆锯片的使用寿命.     

Distribution of diamond grains in fixed abrasive wire sawing process

For over 20 years, wire sawing has been the primary method used for slicing ingots of silicon, sapphire, and silicon carbide into wafer substrates. Fixed diamond wire sawing has recently emerged as an alternative to slurry wire sawing as a means to shorten the time required for slicing and reduce the usage of slurry. The distribution of diamond grains on the wires strongly influences slicing performance in terms of material removal, surface topography, and subsurface damage. However, few studies have investigated this topic. This study established a model with which to simulate the distribution of diamond grains. Simulation results demonstrate that a higher density distribution reduces the rate of material removal because the loading is shared by the abrasives, thereby preventing the grains from penetrating deeply enough into the workpiece to facilitate the removal of material. Lower distribution density was shown to increase the loadings on the abrasives. These results demonstrate the importance of distribution density of diamond abrasives on the wire with regard to slicing performance.     

多参数金刚石圆锯片锯切性能试验机的研制

专门研制出一种多参数的试验机,用以检测石材加工所用的金刚石圆锯片的锋利度、耐磨性等锯切性能。简介了该试验机的系统组成,具体指出了用来衡量金刚石圆锯片的锯切性能的锯切功率、锯切阻力、锯片转速、给进速度和噪声等多种参数的检测和控制工作原理,给出了基于LabVIEW的锯切参量检测程序设计面板和噪声检测程序代码。该系统测控操作简便,具有很强的适应性,满足综合评价金刚石圆锯片锯切性能的基本要求。     

钎焊金刚石磨料片工艺的研究

用AgCuNi、AgCuCr和AgCuTi钎料,在自行研制的钎焊装置中,采用二次钎焊和两级加热工艺,实现了一次焊接20片金刚石磨料片。     

串珠绳锯切花岗石过程中锯切参数对锯切力和能耗的影响

在建立串珠绳锯切弧区内单颗磨粒平均切削深度与锯切参数间理论关系的基础上,采用单因素和正交法进行锯切参数对锯切力和锯切能耗影响的试验研究.结果表明,单颗磨粒平均切削深度与锯切长度无关,但随进给率的增大或线速度的减小而增大.进给率对锯切力和功率的影响比线速度和锯切长度都要明显.锯切过程中材料去除方式存在体积破碎,适当增大磨粒切削深度有利于提高体积破碎比例从而降低锯切比能;但增大磨粒切削深度直接缩小了介于工具一工件接触面问的动态容屑空间从而加剧岩屑摩阻效应,长弧区排屑困难对锯切力和能耗影响明显.正确选择锯切工艺参数尤其是进给率,对锯切力和能耗的控制及动态容屑空间的平衡至关重要.     

The optimal diamond wheels for grinding diamond tools

Grinding is the most suitable process for manufacturing good quality diamond tools. In this paper, diamond wheels have been studied. From the grinding of polycrystalline diamond (PCD) insets, the effects of certain factors such as the bonding material, the grit size and structure of a diamond wheel have been investigated. It is concluded that vitrified bond diamond wheels are the most suitable for grinding PCDs and the recommended grit size is mesh number 1000, which can get a good surface quality within an appropriate time. The wheel structure is another important factor. Rougher wheels (mesh #800, #1000) with the softer grade scale P yield a higher material removal rate (MRR) than scale Q. However, a finer wheel (mesh #1200) needs a tougher structure to promote its grinding ability and to have a higher MRR.     

新型硬质石材锯切加工冷却润滑液

介绍了国内外石材锯切冷却润滑液研究概况，分析了锯切加工对冷却润滑液的冷却、润滑、清洗、抗硬水和岩粉沉淀性能的要求，提出了石材锯切加工冷却润滑液的组成原则。     

高温焊接金刚石技术

分析金刚石焊接的工艺难点。阐述高温焊接金刚石可以采用的一些工艺技术 ,及与之有关的现代科学技术研究成果。     

DFT-based FEM analysis of nonlinear effects on indentation process in diamond crystal

We apply a new framework of a finite-element method (FEM) analysis with constitutive relations based on density functional theory (DFT), as an efficient method to characterize the nonlinear and anisotropic elastic deformation of single-crystal diamond. In our scheme, the stress-strain relations are obtained during FEM analysis on the fly based on the plane-wave-based DFT total-energy calculations and their numerical database is simultaneously constructed, which enables us to obtain high-precision stress without any empirical parameters even under finite strained conditions. To check its validity and accuracy, the shear deformation behavior of diamond crystal is analyzed under the strained condition. Then we examine the nonlinear effects on the indentation deformation of diamond single crystal, by comparing the results from the DFT-based constitutive relations with those from the linear elastic ones.     

环形电镀金刚石线锯锯切工艺参数的正交试验研究

这里对环形电镀金刚石线锯锯切工艺参数进行了正交试验研究。分析了金刚石粒度、进给压力和锯丝速度对锯切过程的影响。获得了基于提高锯切效率和锯丝寿命,降低锯切力的最佳锯切工艺参数。锯切花岗岩时,要保证较高的锯切效率和锯切比,在本试验范围内,最佳工艺参数为:采用金刚石粒度为200～230#的锯丝,进给压力为9N,锯丝速度为20m/s。     

金刚石线锯的研究现状与进展

金刚石线锯能够对硬脆材料进行精密、窄锯缝切割 ,已逐渐取代内圆锯 ,广泛应用于半导体和光电池切片加工 ,并在陶瓷、石英、木材等加工中显示出独特优势。对国内、外金刚石线锯研究现状进行总结 ,介绍该技术的最新进展     

Automatic 3D model reconstruction of the diamond object

This paper addresses the problems presented by automatic 3D modeling and measurement in evaluating the diamond-cutting grade of the round brilliant cut diamond. (In this paper, we refer to the round brilliant cut diamond, the most common diamond, unless otherwise specified.) Diamond features such as small size (most are less than 1 cm), lack of texture, highlights, and light transmission intensify these problems, and commonly used methods in computer vision such as laser triangulation, structured light, stereo matching, and shape from shading fail to generate the diamond’s 3D model. Based on the image features of the diamond and the polishing process of the rough diamond, this paper proposes a “shape from multi-view closed contours” (SFMCC) method. First, the diamond is placed on a turntable, and a single CCD camera with one telecentric lens captures silhouette images from multiple views as the turntable rotates. Next, accurate closed contours are extracted from the silhouette images sequence, and a 3D model of the diamond can be retrieved through the space-carving process of the bounding box with multi-view closed contours. To implement the SFMCC method, a complete system including hardware and software is designed and constructed. Many different experiments have been designed to test this method, and results have proven its high efficiency and accuracy.     

金刚石疲劳强度与刀具质量关系的试验研究

通过试验研究了金刚石疲劳强度与刀刃质量的关系,并对之进行了理论分析,最后对实际生产应用提出了建议和意见。     

Investigation of the diamond machinability of newly developed hard coatings

Presently, coatings of electroless nickel are used for diamond turning molds for injection molding of optical lenses. We have investigated the diamond machinability of substoichiometric hard nitride coatings (TiN_x, TiAlN_x, and CrN_x). These coatings have a superior hardness compared to electroless nickel suggesting an improved wear resistance of molds with optical surface quality. In the case of CrN_x and TiAlN_x, high tool wear occurred, even after small cutting distances, and the surfaces showed a roughness larger than R_a = 0.5 μm. A considerably higher surface quality was obtained on TiN_x coatings. The best results (R_a = 15 nm) were achieved with a nitrogen content of x = 0.03. As a first application, a mold for a diffractive optical element was machined using this newly developed substoichiometric titanium nitride deposit.     

Microscale patterning of single crystal diamond by thermochemical reaction between sidero-metal and diamond

Single crystal diamond is expected to be a new material for not only micromachining tools, but also innovative microelectromechanical systems (MEMS). In this paper, we propose a new method for micro-patterning of bulk diamond by exploiting the thermochemical reaction between diamond and sidero-metals. We demonstrate the micro-patterning of single crystal diamond by annealing at temperatures from 1073 K to 1173 K after either micro-patterning nickel on the diamond or placing the diamond on a silicon substrate with a micro-patterned nickel layer. The nickel patterning, and thus the diamond patterning, can be conducted in a mass producible manner using photolithography. Etching rates greater than 0.2 μm/min were successfully achieved. The etching mechanisms were also experimentally elucidated, with oxygen playing a crucial role in the etching processes.     

热切锯锯齿应力分析

针对热锯机锯片磨损较快，使用寿命过短等主要失效形式，为摸清失效机理，找出预防办法，进行了锯齿初始接触状态和稳定锯切状态下齿尖应力的理论分析和有限元研究，并且得到有意义的结果。     

Tribological behaviour of diamond coatings sliding against Al alloys

A low wear rate, combined with exceptional physical properties, makes diamond an ideal candidate for the machining of non-ferrous materials. It is particularly interesting for tooling aluminium and its alloys as it offers these soft materials clean cutting and lets the shavings slide on the tool surface.It results from studies dealing with the friction of diamond against aluminium, that the tribological behaviour of this pair is greatly influenced by the presence of oxides, more particularly Al₂O₃, on the counterface surface. It was therefore necessary to better understand the role of these oxides during the cutting process, the way they modify the nature of the contact, and their effects on transferred layer formation.The tribological behaviour of diamond coatings prepared by the combustion flame process, sliding against aluminium alloys under different environments (vacuum, oxygen and water vapour), at two applied normal loads is presented here; the modifications of both the coatings (formation of amorphous carbon) and the counterfaces (depth of the friction track), as well as the transferred layers (chemical composition, aspect) are specifically studied.The surface changes are revealed by scanning electron microscopy observations. Raman spectroscopy and energy dispersive spectroscopy analyses were realised to highlight the observed phenomena.     

Study on the thermal wear of diamond segmented tools in circular sawing of granites

An investigation is reported of an analysis on the thermally induced sawblade wear in circular sawing of granites with diamond segmented tools. The temperatures at the diamond–workpiece interface were measured in dry sawing using a foil thermocouple in order to examine the contribution of temperatures to the wear of the segments. Scanning electron microscope and energy dispersive spectrometers were employed to analyze the mechanisms for the bonding of Ti/Cr-coated diamonds to an iron-based matrix. Over 90% of the consumed energy was found to conduct into the diamond segments as heat in the sawing. Strong metallurgical bonding was observed at the diamond–matrix interface and subsequently the retention ability of the matrix to diamonds was increased. However, the retention effect of the coating was greatly offset by the disparity of diamond crystal strength, which could be improved by multistage shape selecting and magnetic separating. Coupled with the mechanisms for thermal wear, attempts were made to reduce thermally induced wear by using Ti/Cr-coated diamonds, reducing the disparity of diamond crystal strength, designing unique structured segments and selecting optimal machining parameters.