锯切花岗石中金刚石节块形貌变化过程跟踪

评价锯切过程中金刚石节块表面状态与锯切力的依赖关系是十分重要也是十分困难的。本文以大切深锯切为研究对象,采用新的磨粒磨损状态划分方法将传统的六种金刚石磨损状态细分为十二种,通过视频采集系统跟踪观察金刚石锯片节块表面形貌变化。通过分析磨粒的不同磨损状态随锯切面积的变化规律,并结合锯切力的变化过程,讨论分析了不同磨损状态变化与锯切过程的内在联系。结果表明,单颗金刚石的磨损变化具有跳动性。十二种磨损状态的变化能够较好的反映锯切力的变化,在达到某一锯切面积时大多数磨损状态和锯切力的变化都有一个明显的转折。     

金刚石压齿锯片在先进陶瓷加工中的应用评价

针对先进陶瓷材料的切割加工中存在着切割效率低、工具磨损快等问题,本文通过用金刚石压齿锯片加工氧化铝陶瓷的实验,研究锯片的磨损失效机制,探讨高效低成本的先进陶瓷切割技术.实验中用金刚石压齿锯片在不同加工条件下对氧化铝陶瓷材料和玉石进行切割加工,测量切割法向力和切向力,并跟踪锯片刃口形貌的变化及其磨损过程.实验结果表明,由于材料性质的差异,氧化铝陶瓷的切割力和力比均要明显大于玉石.锯片的磨损是由于该类型锯片的刃口上金刚石磨料浓度太低,而且结合剂的把持力不足导致金刚石大量脱落而失效的,并造成金属基体与工件间的摩擦加剧,切割比能也相应增加.     

Characteristics of diamond sawblade wear in sawing

The characteristics of the surfaces of worn diamond segments in circular saws for the sawing of granite have been investigated. A scanning electron microscope and a toolmaker's microscope were used to examine the worn surfaces, and radial sawblade wear and grinding ratio during sawing were measured. Experimental results indicate that the diamonds on the working surface for a heavy trimming operation can be classified as whole (without significant wear), micro-fractured, and macro-fractured crystals; also pull-out craters occur. The transition from a free-cutting action to a less efficient cutting occurs when the proportions of whole crystal, fractured particle, and grit pull-out are about one-third. When the proportion of particle fracture (particularly macro-fractured particles) and/or grit pull-out exceeds one-third, the cutting ability of a sawblade becomes less efficient and, in an extreme case, leads to sawblade failure. Conversely, a sawblade containing a higher proportion of whole crystals and a lower proportion of macro-fractured particles cuts more efficiently.     

金刚石框架锯锯切研究（Ⅴ）—金刚石结块磨损特征

在对金刚石框架锯锯切加工动力学，锯切破碎机理模型和金刚石框架锯锯切加工石材时的切削力研究的基础上，通过金刚石锯条锯切石材的实验，测量并分析了金刚石结块磨损特征及其分类，金刚石结块磨损机理，金刚石结块磨损与加工时间，进给速度，石材种类，金刚石结块性能和锯条张紧力等因素的关系，提出了加工参数和金刚石结块的优选原则，研究结果为系统开发和改进金刚石工具提供了一个良好的基础，基于 这些结果，可改进结合剂，金刚石质量，金刚石浓度，金刚石粒度，结块尺寸和结块间隔。     

Comparison of wear characteristics of diamond segments under different sawing modes in sawing hard stone

In this study, the wear characteristics of two kinds of diamond segments with different composition of matrix were compared and investigated under two sawing modes through an experiment. Diamond particles were studied through scanning electron microscopy and three dimensional imaging system. Then, the remaining height of diamond segments was measured by digital vernier caliper. The wear characteristics of diamond segments were analyzed from wear morphology, protrusion height of diamond particles and the remaining height of diamond segments. The motion of two sawing modes and their effects on trajectories were analyzed which presented that the rocking reciprocating sawing mode can reduce sawing length and sawing time compared with horizontal reciprocating sawing mode used daily in industry. The results of experiment demonstrated that the main wear mechanism attributed to diamond segments wear is the fracture and falling of diamond particles caused by heavy loads especially in rocking reciprocating sawing mode. The average protrusion height of diamond particles is related with loads and the bonding strength of matrix. However, diamond segments wear can be effectively reduced in rocking reciprocating sawing mode while cobalt-based segments were adopted because a higher bonding strength to diamond particles can be provided compared with iron-based segments. The matrix of segments can be abrased slower while sawing length and sawing time were reduced.     

Computer simulation of stone frame sawing process using diamond blades

Based on the results of scratching tests with single point tools and single segments in a previous study, the contact area between stone and blade, the number of effective cutting edges and the cutting forces per diamond grit, per segment and blade in the frame sawing process are simulated by computer. The number of diamond grits per unit area, the distribution of diamond grits per segment and the effective depth of cut of diamond grits are calculated by a new method. The Monte Carlo method is applied to generate the position of diamond grits randomly. The results show that in cutting stroke, only half of the diamond grits on the segment surface cut stone with the depth of cut increasing and a limited moving distance. The interactions of the grooves created by different segments remove the stone and generate the saw kerf. The simulation results of cutting forces are consistent in tendency with the data tested in a frame sawing machine. Cutting feed and the cutting performance of the segments are the major factors which determine the cutting forces and segment wear. The optimized constant contact area between blade and stone depends on the segment spaces, the segment number and the segment size, the ratio of the length of block and the effective cutting length of blade etc.     

金刚石框架锯锯切研究(Ⅵ)--在实验机上模拟框架锯锯切过程

测定金刚石框架锯锯切切削力，金刚石结块磨损和锯条变形等是十分重要也是非常困难的。在前面对锯切运动，锯切机理，锯切切削力和金刚石结块磨损研究的基础上，介绍了一种在实验室里用小型框架锯切实验机模拟框架锯锯切过程的实验方法，比较了用单锯条三节块和单锯条单结块锯切石材的实验结果，优选了结块分布间距，与金刚石框架锯锯切加工实验结果的比较表明，在实验机上用单锯条三节块锯切石材时，测量得到的处于中间的金刚石结块的切削性能，可以较好地反映实际加工中金刚石结块的切削状态，利用这一结果，可快速地通过简单的实验，评价金刚石锯条在实际加工中的切削力和金刚石结块磨损特性，其误差在20%以内。     

聚晶金刚石复合片的磨损规律

通过观察切削花岗岩过程中聚晶金刚石复合片(PDC)刀具的磨损过程和磨损形貌,研究PDC刀具的磨损规律。研究结果表明:切削花岗岩时,受切削力及其冲击的作用,PDC刀具产生近乎平行岩石表面的磨损形式,磨损机理为机械作用引起聚晶金刚石层微观裂纹产生并扩展而导致的金刚石颗粒的微观破碎。     

Characterization of N-doped polycrystalline diamond films deposited on microgrinding tools

Chemical vapor deposited diamond films have many industrial applications but are assuming increasing importance in the area of microengineering, most notably in the development of diamond coated microgrinding tools. For these applications the control of structure and morphology is of critical importance. The crystallite size, orientation, surface roughness, and the degree of sp ³ character have a profound effect on the tribological properties of the films deposited. In this article, we present experimental results on the effects of nitrogen doping on the surface morphology, crystallite size, and wear of microgrinding tools. The sp ³ character optimizes at 200 ppm nitrogen, and above this value the surface becomes much smoother and crystal sizes decrease considerably. Fracture-induced wear of the diamond grain is the most important mechanism of material removal from a microgrinding tool during the grinding process. Fracture occurs as a consequence of tensile stresses induced into diamond grains by grinding forces to which they are subjected. The relationship between the wear of diamond coated grinding tools, component grinding forces, and induced stresses in the model diamond grains is described in detail. A significant correlation was found between the maximum value of tensile stress induced in the diamond grain and the appropriate wheel-wear parameter (grinding ratio). It was concluded that the magnitude of tensile stresses induced in the diamond grain by grinding forces at the rake face is the best indicator of tool wear during the grinding process.     

Wear and cutting performance of diamond composite material-a comparison with tungsten carbide

A series of wear and rock cutting tests were undertaken to assess the wear and cutting performance of a thermally stable diamond composite (TSDC). The wear tests were conducted on a newly designed wear testing rig in which a rotating aluminium oxide grinding wheel is turned (also known as machined) by the testing tool element.The rock cutting tests were performed on a linear rock-cutting planer. The thrust and cutting forces acting on the tool were measured during these tests. A tungsten carbide element was also studied for comparative purposes. The wear coefficients of both materials were used to evaluate wear performance while cutting performance was assessed by tool wear and the rates of increase in forces with cutting distance.     

电镀金刚石圆柱铣刀在数控石材加工中磨损实验研究

本文采用正交实验方法,对电镀金刚石涂层刀具在数控石材加工中进行试验,研究加工参数和金刚石颗粒性能对电镀金刚石刀具磨损量的影响,并利用体式显微镜对磨损后的刀具表面形貌进行了分析.试验结果表明:影响金刚石铣刀磨损量的主要因素是金刚石粒度,加工参数中影响较大的是径向切深,其次是主轴转速,进给速度影响较小.刀具底面的磨损比侧面严重,刀具底面的磨损形式主要是犁沟,金刚石主要以脱落为主;侧面的磨损形式主要是磨平,金刚石颗粒以破碎为主.     

金刚石圆锯节块在花岗岩锯切过程中的磨损形态及影响因素

通过单个金铡石节块磨损量和磨损表面形貌的观察和测量，分析了在不同冷却液和加工条件下的金刚石磨损形式。结果表明，金刚石的磨损形态可分为良好及微破碎、端部破碎、磨平、局部脱落、脱落凹抗和出刃。锯切节块成份和工件材料种类决定了金刚石的磨损形态和冷却液作用效果。     

金刚石薄锯片高速锯切花岗石过程中的锯切力特性

本文对金刚石薄锯片高速锯切花岗石过程中的锯切力特性进行试验研究,在较宽的参数范围下,通过测量水平力、垂直力和主轴功率来计算切向力和法向力.对锯切力、力比、单颗金刚石承受的平均载荷进行了分析.结果显示,提高锯片的线速度使锯切力、力比和单颗金刚石磨粒承受平均载荷减小;在高速锯切时,锯切力随着锯切深度和进给速度的增加而增加,而进给速度对锯切力的明显影响要小于锯切深度,应选择小切深大进给的工艺参数组合;锯切力比随锯切深度的增加而增加,随进给速度的增加而减小;单颗金刚石磨粒承受平均载荷随着单颗粒金刚石最大未变形切削厚度的增大而线性增大.     

Analyzing the performance of diamond-coated micro end mills

A method is presented to improve the tool life and cutting performance of 300 μm diameter tungsten carbide (WC) micro end mills by applying thin (<300 nm) fine-grained diamond (FGD) and nanocrystalline diamond (NCD) coatings using the hot-filament chemical vapor deposition (HF-CVD) process. The performance of the diamond-coated tools has been evaluated by comparing their performance in dry slot milling of 6061-T6 aluminum against uncoated WC micro end mills. Tool wear, coating integrity, and chip morphology were characterized using SEM and white light interferometry. The initial test results show a dramatic improvement in the tool integrity (i.e., corners not breaking off), a lower wear rate, no observable adhesion of aluminum to the diamond-coated tool, and a significant reduction in the cutting forces (>50%). Reduction of the cutting forces is attributed to the low friction and adhesion of the diamond coating. However, approximately 80% of the tools coated with the larger FGD coatings failed during testing due to delamination. Additional machining benefits were attained for the NCD films, which was obtained by using a higher nucleation density seeding process for diamond growth. This process allowed for thinner, smaller grained diamond coatings to be deposited on the micro end mills, and enabled continued operation of the tool even after the integrity of the diamond coating had been compromised. As opposed to the FGD-coated end mills, only 40% of the NCD-tools experienced delamination issues.     

PCD刀具加工强化复合地板中磨损行为的断裂力学研究

本文首先利用断裂力学的理论，分析了聚晶金刚石刀具切削过程中的沿晶和解理两种磨损特征及其形成过程。通过采用SYNDITE聚晶金刚石刀具对Al2O3颗粒表层强化复合地板的切削加工实验，验证了理论分析的正确性。研究表明聚晶金刚石刀具铣削Al2O3表层强化复合地板的过程中，刀具的磨损特征主要由沿晶磨损和解理磨损组成。并且，理论和实验结果表明刀具的磨损特征受到金刚石晶粒尺寸的影响。粗粒度聚晶金刚石易产生解理磨损形貌，细粒度的聚晶金刚石易产生沿晶磨损形貌。同时，研究表明微观裂纹特征对聚晶金刚石刀具的磨损起着重要的作用。     

A novel laser-assisted truing and dressing technique for vitrified CBN wheels

The preparation of vitrified CBN or diamond wheels by truing and dressing has a large influence on the grinding performance. A worn diamond dresser cannot produce sufficient protrusion of cutting grain edges. To reduce the wear of diamond dressers and hence guarantee a desired wheel surface, a novel truing and dressing method, namely, laser-assisted truing and dressing, is proposed and tested to achieve good dressing quality and efficiency. A systematical experimental feasibility study on this newly proposed laser-assisted truing and dressing technique is conducted by investigating truing efficiency, truing accuracy, dresser wear, dressed wheel profiles, and specific forces in comparison with those of the conventional single diamond methods. Experimental results show that the new laser-assisted truing and dressing technique offers a number of advantages over the conventional single-tip diamond dressing and truing method. In addition, the underlying mechanism of the laser truing and dressing process is investigated through the careful analysis of the properties of chips and the microscopic structural characteristics of wheels.     

金刚石框架锯锯切研究(Ⅷ) --计算机模拟框架锯锯切过程

计算机模拟了在框架锯锯切过程中石材和锯片的接触面积和有效切削刃数、单个金刚石颗粒、金刚石结块和整个金刚石锯条的切削力。结果表明：在结块表面上出刃的金刚石颗粒中，只有半数金刚石颗粒在一个固定的切削区间内切削石材。金刚石在不同位置切削产生的断裂沟槽交错，形成了锯切沟槽的底部，切削力的试验结果与实际切削试验结果在数量级和变化趋势上是一致的。切削进给量和金刚石结块的切削性能是影响切削力和结块磨损的主要因素。石材和锯条结块间的最佳接触面积取决于结块间距、结块数目、结块尺寸，以及石材的长度与锯条有效切削长度之比等因素。     

金刚石框架锯锯切研究(VII)━计算机模拟框架锯锯切过程基础

基于框架锯锯切加工运动学分析、单颗粒和单结块切削力试验结果 ,讨论了采用计算机模拟框架锯锯切过程中所需的运动学、金刚石结块磨损和金刚石颗粒切削力模型 ,以及模拟过程图。采用简化方法计算了金刚石结块表面的理论金刚石颗粒数 ;结合对金刚石结块磨损的研究结果 ,用MontoCarlo方法生成了结块表面的金刚石颗粒的出刃高度、分布位置和磨损形态 ,生成了数字化的金刚石锯条 ,为计算机模拟框架锯锯切加工过程 ,提供了基础数据。     

The effect of operational parameters on diamond tools of frame sawing system: Wear characteristics and optimization in stone processing

A series of sawing experiments was carried out to investigate the effect of operational parameters on the wear characteristics of diamond segment. And the wear mechanism of diamond segment was studied through micro-morphology. The analysis presented that the wear mechanisms of segment metal matrix are mainly attributed to abrasive wear and erosion wear, the wear mechanism of diamond particles mainly includes cleavage fracture caused by the impact load and abrasion caused by scratching. The effect of sawing parameters on the wear rate of segment matrix is consistent with that of diamond particles. The wear resistance of segment matrix increases with the increase of the proportion of diamond particles with micro-fractured and complete crystalline shape, and decreases with the increase of the proportion of diamond particles with macro-fractured and pulled-out. Furthermore, the predicted model was established to evaluate the segment wear per unit by using Design Expert software, and the optimum sawing parameters obtained as a result of the optimization was investigated to provide some guidance for the processing of the enterprise.     

硬脆材料的电镀金刚石线锯超声切割锯切力研究

基于冲量理论和振动加工理论,采用叠加原理建立了电镀金刚石线锯超声切割锯切力数学模型.从理论上分析了电镀金刚石线锯施加超声振动后锯切力与普通锯切力的区别,并进行了超声振动与普通锯切力对比试验研究.结果表明:锯切力的大小随线锯往复频率的提高而降低,随侧向压力的增加而增大.通过比较发现,超声振动锯切力比普通锯切力减小20%～30%.同时,对超声振动锯切过程中单颗金刚石磨粒切削运动轨迹进行了仿真分析,进一步解释了施加超声振动后锯切力减小的原因.