Polycrystalline diamond mini-cubes for sawing applications

Diamond grits are indispensable for sawing granite or concrete.Each year about 1 000 tons of diamond grits are consumed for such purposes.In all cases,mono crystalline diamond is used.However, polycrystalline grits(polygrits) are generally better performed than mono grits as abrasives.For example,poly grits of cubic boron nitride(e.g.Borazon(?) CBN-550 of Diamond Innovations) can cut faster and they last longer than mono grits(e.g.Borazon(?) CBN-500). Polygrits of alumina(e.g.Cubitron(?) of 3M) also out perform by far glassy grits(e.g.white alumina).For diamond superabrasives,micron polygrits formed by shock waves may polish as fast as mono grits of the same size,but without causing as much scratches due to the presence of smaller sintered grains.The improved performance of poly grits is attributed to their ability to micro chipping that renews the sharp cutting corners from time to time.By contrast,mono grits tend to round off at low cutting force or macro fracture at high cutting force,so they may lose the cutting ability rapidly. For sawing granite with mesh sizes 40/50 or coarser,poly grits of diamond have not been available until recently.In this research,we have made polygrits in mini cube with sizes of 18/20,20/25,and 30/40.Turbo grinders and wire saws were made by brazing both mono grits and polygrits on steel substrates.Cutting performance on granite demonstrated that grinding speed was faster with turbo grinder,and the surface finish was smoother with wire saw for poly grits than mono ones. Polygrits and mono grits of diamond were mixed for comparison(upper left).Polygrits of mini cubes were brazed on the pearl of a wire saw(upper right).Mono diamond grits were brazed on a turbo grinder(bottom diagrams ).

Historical developments and future prospects of saw diamond

More than 1 000 tons of saw diamond grits were consumed worldwide in 2007.Even with such a mature industry,there are still major improvements possible in developing new grits.The DiaCanTM technology with patterned diamond seeding can boost the production yield of coarse mesh diamonds（e.g. 30/40）.Moreover,the DiaMind crystals formed contain a visible core.This diamond-in-diamond architecture allows self-sharpening during sawing application.Furthermore,a revolutionary polycrystalline diamond superabrasive with cubical shape was fabricated to further increase the sawing efficiency and tool longevity.Such DiaCubeTM polygrits were made tools by brazing them on pearls of wire saws and on the surface of turbo grinders. The pros and cons of major designs of high-pressure equipment for diamond synthesis were discussed with the recommendation to combine the merits of belt apparatus and cubic press.This tooling synergism may increase diamond yield at reduced cost for massive production of saw grits. In 1997 Sung Chien-Min filed a series US patents that described the art of making patterned diamond tools with diamond grits forming an array in three dimensions.He also made the debut of the world’ s first brazing tools with patterned diamond distribution at the stone exhibition in Verona in 1998（also in Nuremberg in 1999）.The patterned diamond saws were introduced by Korean companies in 2005 with the demonstration of increased cutting speeds and prolonged tool lives.

固结磨粒金刚石线锯的研究进展

总结固结磨粒金刚石线锯的制备方法,主要有钎焊法、树脂结合剂粘结法和电镀法;分析金刚石表面金属化的原理和模型,比较金刚石表面金属化方法的优缺点;探讨复合电镀的共沉积机理,主要有吸附理论、力学理论和电化学理论;展望固结磨粒金刚石线锯制备的发展方向。

悬砂法工艺参数对精密切割用线锯制备质量影响的研究

为实现KDP、CZT等光学元件用软脆功能晶体坯料的精密切割,研究了悬砂法制备电镀金刚石微粉磨料线锯工艺方法,通过扫描电镜形貌观测,试验分析了不同电流密度、电镀时间和金刚石悬浮量条件下制备的线锯样件质量,探讨了工艺参数对线锯电镀质量的影响及缺陷产生的原因。试验结果表明,悬砂法制备金刚石微粉磨料线锯能够克服埋砂法存在的微粉磨粒分散性差、易导致连续运动的丝线挂砂困难等问题,在合理的工艺参数条件下能够获得磨料分布均匀的电镀金刚石微粉磨料丝线。

钢砂的锯切过程试验研究

对国内外钢砂锯切花岗岩试验的结果说明:钢砂在锯切过程中承受小能量多次冲击接触应力。商用铸造钢砂内存在一些宏观、微观裂纹,其失效的过程为破碎—犁削—破碎;非铸造钢砂失效过程为犁削—破碎模型。

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—工件接触面间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。

金刚石粒度对金刚石锯片性能的影响

根据锯切过程中锯片的金刚石粒度与切屑厚度之关系论述金刚石粒度对锯片性能的影响,主要包括锯切率、使用寿命、功率消耗。在关于金刚石粒度的表示方式中,指出单纯以目数表示金刚石粒度的局限性和以每克拉颗粒数(PPC)表示金刚石粒度的重要性。

金刚石锯片中金刚石粒度与切割瓷砖崩边效果的关系

金刚石锯片根据其不同切割需求采用不同粒度的金刚石。具体研究在使用相同胎体,不同粒度金刚石制成相同规格锯片,在相同切割条件下,湿切不同瓷砖的切割效果。由于使用不同粒度的金刚石锯片切割瓷砖后,瓷砖切割边缘的崩边情况明显不同,随着金刚石的粒度变细,崩边情况明显变好,但其切割速度也会明显降低,同时锯片的价格也会有所提高。因此,使用者可根据笔者的结论选用合适粒度的金刚石锯片。

单颗金刚石磨粒切削面积的推导

引进运动学中的点速度合成定理 ,求解单颗金刚石磨粒切削面积 .通过详细的理论推导 ,推出单颗金刚石磨粒锯切速度方程、锯切运动方程和切削面积的计算公式 .结果表明 ,金刚石磨粒锯切面积与前一颗金刚石磨粒所夹的圆心角成正比 ,并与进给速度、锯切深度成正比 ,也与金刚石圆锯片的转速成反比 .

单颗金刚石磨粒锯切运动学分析

引进运动学中的点的速度合成定理求解单颗金刚石磨粒锯切面积和锯切厚度 ,通过详细的理论推导推出了单颗金刚石磨粒锯切速度方程、锯切运动方程和锯切面积和锯切厚度的计算公式。结果表明 ,单颗金刚石磨粒锯切面积与前一颗金刚石磨粒所夹的圆心角成正比 ,与进给速度成正比 ,与锯切深度成正比 ,与金刚石圆锯片的转速成反比 ,且依余弦规律减小。

感应钎焊金刚石线锯抗拉性能的研究

为了研究钎料、磨粒、钎焊温度对金刚石线锯抗拉性能的影响,利用高频感应加热设备在氩气中进行了钎焊金刚石线锯的制备,在万能试验机上进行了拉伸试验,分析了线锯抗拉性能的影响因素。结果表明:高温钎焊后,线锯的抗拉强度下降明显。

表面磨粒群螺旋排布电镀锯丝制造的实验研究

为了获得高性能的电镀金刚石锯丝,实验研究了悬砂法制备表面磨粒群螺旋排布锯丝的电镀工艺,分析了预镀阴极电流、上砂阴极电流密度与上砂时间对锯丝复合镀层外观质量与锯丝表面磨粒分布情况的影响规律,并采用试制锯丝进行了锯切实验。研究结果表明,镀底层的阴极电流密度为5.0A/dm2时,镀层与钢丝基体表面有着良好的结合强度;上砂阶段采用阴极电流密度为5.0A/dm2,其电镀时间为7-8min,可得到良好的镀层和磨粒分布效果。钢丝基体预镀前在表面绕绝缘线,合理地选择工艺参数可以获得磨粒群在钢丝基体表面螺旋排布的基本结构,试制的新型锯丝在锯切中具有良好的容屑与排屑效果。

解读De Beers锯片金刚石磨粒标示图系

在已知应用条件下正确选用锯片金刚石磨粒乃是获得最佳效益的先决条件。为此 ,De Beers工业金刚石部根据广泛的试验室实验和确证的现场数据 ,制定出其锯片金刚石产品的标示图系 ,以便金刚石工具制造厂家能够选择最合适的锯片金刚石磨粒。不同的合成方法可合成出同样强度的金刚石 ,但其颗粒结构不同。金刚石的颗粒结构可用其粒度、形状、表面特征和内含夹杂物来表征。在同样工作条件下 ,不同合成方法生产出来的金刚石磨粒的磨损状况是不相同的。因而其磨损机理标示图也不相同。在 De Beers锯片金刚石磨粒标示图系中列出了颗粒强度、颗粒结晶度和磨损机理标示图。应用 De Beers锯片金刚石磨粒标示图系的关键在于对磨损机理标示图的透彻分析。

碳化硅切割刃料圆形度控制技术研究

碳化硅切割刃料的圆形度对晶硅片线切割有着重要影响。对高压辊磨法制备碳化硅微粉过程中影响圆形度的因素进行理论分析和实验研究,分别研究了亚微粉(Ф≤2μm)含量、碳化硅纯度、1#分级机转速和磨辊磨损四个因素对圆形度的影响。探讨了降低微粉圆形度,并稳定圆形度指标的方法,能够获得具有较多棱角颗粒的低圆形度微粉,对提高碳化硅微粉的工业价值和经济价值,提高晶硅片切割效率,具有重要意义。