Comparison of wear performance of diamond tools in frame sawing with different trajectories

In this study, experiments were performed to explore the wear performance of diamond tools with different sawing trajectories in stone processing. The wear morphologies of the diamond segments were analyzed by an optical microscope and scanning electron microscopy. The wear behavior of the diamond segment was investigated comprehensively from the aspects of the wear morphology of matrix and diamond, the remaining height of segments and the height of protrusion of diamond particles. The results indicated that matrix tails are developed behind diamond particles in impacted frame saws guided by the specific eccentric hinge mechanisms. The sawblades can be lifted and cut stone at the maximum horizontal velocity, create many new cutting edges, so that the diamond particles with cutting ability in impacted frame saws are higher than that of the horizontal frame saw. In addition, the hinge mechanisms of impacted frame saws placed in the same direction are conducive to the uniformity of segment wear compared with the hinge mechanisms placed symmetrically. Impact wear is the main wear mechanism of the diamond particles in impacted frame saws, while impact load also accelerates the fracture of diamond particles. Accordingly, the difference of protrusion height between three kinds of frame saws is not particularly large.     

Investigation and improvement of wear nonuniformity of diamond tools in sawing granite

Sawing experiments were accomplished to discuss the wear characteristics at different parts of diamond tools in the process of sawing granite in this paper. Optical microscopy, scanning electron microscopy and 3D laser microscope were main detection means for the morphology of diamond tools. Synthetic investigation on the abrasion performance of segments was developed from aspects of the wear appearance of diamond particle and metal bond, the particle protrusion height and the residual height of segments. The results indicated that smaller residual height and larger proportion of macro-fractured and pull out crystal were exhibited at the front end of traditional diamond segment compared with the rear end. Morphology characteristics of diamond tools demonstrated different abrasion mechanism, flush erosion and cavitation was the main wear mechanism for the front end, while abrasive wear was the main wear mechanism for the rear end. Maximum undeformed chip thickness per diamond particle for the front end was larger than that of the rear end due to the existence of slot, the same was true for the load of single diamond particle. By reasonably matching of diamond particles and matrix bond, the abnormal failure efficiency of the diamond particles at the front of the segment was effectively reduced and the wear uniformity of the saw tooth surface was greatly improved. Suggestions on the design of diamond tools and test verification were put forward in the end.     

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.     

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。     

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.     

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.     

结合剂强度和不同镀层对金刚石工具出刃高度的影响

采用L9(34)正交试验研究未镀金刚石、表面镀Ti和镀Ni金刚石在不同强度结合剂下对金刚石工具出刃高度的影响,并使用SEM 3D重构法测量金刚石的出刃高度,对比分析不同状态下的金刚石出刃高度变化.结果表明:使用SEM 3D重构法能够方便、快速和准确地测量金刚石的出刃高度,高度值为221.26～321.68μm;金刚石表...     

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.     

Effects of diamond grain characteristics on sawblade wear

One-segmented diamond sawblades containing diamond with varying degrees of etch pits were manufactured to study the wear behaviour of diamond grains during the sawing of granite. The worn surfaces of the diamond segments were analysed by a scanning electron microscope (SEM), and the forces acting on the tool and the wear performance were measured. The results showed that a sawblade containing diamond with a small number of pits during sawing displays predominantly microfractured worn particles on the working segment surface, a lower sawing force, and a better wear performance. When a tool containing a greater number of extensive pits on the diamond grains is used, a higher proportion of macrofracture occurred and wear flats appeared on the worn diamonds. In addition, the sawing forces are relatively higher and the blade performance is poorer.     

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。     

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。     

金刚石线切割单晶碳化硅锯切力的实验研究

从锯切力的角度对金刚石线锯锯切单晶SiC材料的加工过程进行了研究。得出了线速度、进给速度、线锯张紧力对锯切力的影响规律。从单位长度线锯材料去除量、锯切比能的角度讨论了锯切工艺对锯切力的影响机理。在金刚石线锯锯切单晶SiC过程中,锯切力随着线速度的增大而减小,随着进给速度的增大而增大,线速度与进给速度对锯切力的综合影响表现为:单位长度线锯材料去除量的增加会增大锯切力。单位长度线锯材料去除量对于金刚石线锯锯切单晶SiC材料的锯切比能具有显著的影响。     

稀土对金属基金刚石节块力学性能的影响

金属基金刚石工具结合剂中添加少量稀土元素可以细化胎体晶粒,净化金刚石与胎体界面,从而改善结合剂与金刚石的界面结合状态。本研究通过在不同类别金刚石节块中添加或不添加稀土元素,观察其力学性能的变化,并进行比较分析,探讨稀土元素对不同类别金刚石节块力学性能的影响机制。实验结果表明稀土元素对不同类别金刚石节块抗弯强度的影响较为显著,同时,在铜基中加入稀土元素,可以加强金刚石与周围胎体的结合状况,提高胎体对金刚石的把持力。研究成果将有利于促进和推广稀土在金刚石工具制造领域中的应用。     

盾构滚刀材料表面镍基碳化钨涂层摩擦学性能研究

目的 盾构滚刀磨损是盾构施工中最常见的问题之一,为减缓刀具的剧烈磨损、延长刀具的使用寿命,采用等离子堆焊工艺在盾构滚刀表面制备镍基碳化钨涂层以强化滚刀性能,基于盾构滚刀服役的真实工况,研究滚刀涂层的摩擦学性能及其合理的评价方式.方法 对镍基碳化钨涂层在往复滑动、冲滑复合(冲击+滑动)两种相对运动模式下进行摩擦磨损试验研究.结果 制备镍基碳化钨涂层后可提高滚刀的耐磨性.往复滑动磨损后,镍基碳化钨涂层的磨痕宽度为0.42 mm,而H13钢的磨痕宽度达到0.78 mm,镍基碳化钨涂层的抗冲滑性能也明显优于H13钢.两种相对运动模式下镍基碳化钨涂层均主要承受磨粒磨损,但往复滑动模式下涂层存在局部剥落,而冲滑复合模式下则伴随一定的粘着磨损.结论在两种相对运动模式下,镍基碳化钨涂层表面的高硬度碳化钨颗粒都可阻止磨粒对较软镍基合金区域的切削与碰撞.相较往复滑动模式,冲滑复合模式下镍基碳化钨涂层要承受冲击和滑动的耦合作用,涂层的磨痕特征以及损伤形式都有明显的不同.采用冲滑复合运动模式的摩擦磨损试验能对盾构滚刀刀圈的摩擦学性能进行更全面、合理的研究及评价.     

Cu-Fe基金刚石锯片刀头真空液相烧结性能研究

采用真空液相烧结的方法,设计了Cu-n基刀头基体配方,以低熔点铜基预合金粉末为粘结相,并添加Ti、Cr等活性金属粉末改善基体与金刚石的结合力,通过组织观察及性能分析,讨论了粘结相．骨架相及活性金属含量对基体及刀头性能的影响。随Ti含量的增加,粘结相对骨架相的润湿能力增强,基体的硬度增加,基体对金刚石的结合力提高,刀头的耐磨性增加。随粘结相含量的增加,基体的合金化及致密性提高、硬度增加．刀头的耐磨性增加;硬质颗粒含量较少时对基体的增强作用是弥散强化,当硬质颗粒形成连续骨架时形成颗粒增强。     

Multi-wire sawing of sapphire crystals with reciprocating motion of electroplated diamond wires

This study examined the multi-wire sawing of C-plane sapphire ingots using diamond wires. Feeding new wire during the reciprocating motion of the wire was found to vary the cutting force, wafer shape, and roughness as a result of the break-in effect. The break-in and wire wear seemed to cause a gradual change in the cutting performance along the ingot position. The cutting force results indicated that an inappropriate supply of wire yielded an unbalanced force between the front and back sides of the ingot, which was caused by a difference in the cutting depth along the ingot. The results showed that controlling the wire consumption resulted in an average flatness of 16 μm, with a maximum value of 26 μm.     

Interfacial structures and mechanical properties of a high entropy alloy-diamond composite

A FeCoCrNiMo high-entropy alloy (HEA)/diamond composite prepared by spark plasma sintering (SPS) was investigated. Sintering the HEA/diamond composites at different temperatures leads to different interfacial structures, which have an impact on the mechanical properties. The multiple microstructures at HEA/diamond interface have different effects on the retention of the HEA matrix on diamond particles. It was found that the interstitial strengthening effect, amorphous carbon and nano-scale ordered carbon complex were beneficial to the mechanical properties. Due to the good interfacial bonding strength between the HEA matrix and un-failed diamond particles, the composite sintered at 950 °C exhibited an optimized combination of mechanical properties, with a hardness of 630 HV, transverse rupture strength of 1310 MPa, and optimal wear resistance. The failure of the diamond particles and the formation of brittle chromium carbides at sintering temperature at 1000 °C can deteriorate the properties of HEA/diamond composites.     

金刚石绳锯切割混凝土的锯切力实验研究

对烧结金刚石串珠绳锯在锯切混凝土过程中锯切力的变化进行了跟踪检测实验,研究了锯切力随锯切参数及锯切长度的变化规律.实验结果表明:锯切过程中,工件上所承受的锯切力(水平力Fh和垂直力Fv)随着线速度vs的提高而减低,随着进给速度vf的提高而增加.锯切力随着锯切中工件长度L的增加而增加.垂直力与水平力之间存在着良好的对应关...     

悬浮上砂金刚石线锯的锯切性能试验分析

采用不同上砂位置的悬浮上砂电镀金刚石线锯对单晶硅进行锯切试验,记录锯切时间,计算锯切效率,对比不同上砂位置锯丝的锯切性能。用扫描电镜对锯丝上砂及磨损情况进行观测,用表面粗糙度仪对硅片表面粗糙度进行测量。试验结果表明:不同上砂位置的锯丝的磨粒密度相差较大,上砂位置靠近上砂槽体中心的锯丝磨粒密度最大;磨粒密度较大的锯丝的锯切效率较高。磨粒密度为585 颗/mm的锯丝锯切效率为4.949 mm2/min,比磨粒密度为446 颗/mm的锯丝锯切效率(2.158 mm2/min)提高了138%;用磨粒密度不同的锯丝加工出的硅片表面质量差别不大;锯丝的磨损及损伤形式主要是磨粒的磨损、磨粒的脱落及锯丝镀层的磨损与损伤。