【作者】 李远；

【导师】 徐西鹏；

【作者基本信息】 华侨大学 ， 机械制造及其自动化， 2004， 博士

【摘要】 在花岗石板材的生产过程中，切割加工是一道关键工序，不仅关系到本工序的加工成本和效率，还关系到后续加工工序的效率和质量。使用金刚石工具的锯切加工是石材切割的最主要方式，也是消耗人造金刚石最多的工业领域。相对于早期的加工技术，金刚石圆锯片切割无论在降低加工成本还是提高加工效率方面都有了革命性的变化。但是，这种革命性的含义似乎更多地体现在大理石的加工上。对于花岗石特别是硬质花岗石，所能达到的极限锯切的深度远远低于大理石锯切。 本文在深入剖析花岗石锯切加工技术现状以及存在问题的基础上，全面探讨了大切深条件下花岗石的锯切机理，设计制造了新型超短齿结构的金刚石锯片，实现了花岗石的超大切深锯切。论文的主要研究工作概括如下： 1、制备了常规结构的铁基金属结合剂金刚石锯片，建立了大切深锯切实验及测试平台，对大切深锯切过程中的锯切功率和锯切力以及锯片磨损过程中金刚石节块表面磨粒的磨损状态和出刃高度等进行跟踪测量。 2、探讨了大切深锯切花岗石过程机理，建立了锯切载荷模型，统计分析了磨粒磨损状态及其出刃高度对锯切载荷的影响情况。 3、利用有限单元法对锯切过程中锯片承受的应力分布状况进行分析，通过模态和屈曲分析，了解锯片厚度、转速、夹紧比和直径对锯切动态特性的影响。 4、基于上述分析，研制了一种新型结构超短齿金刚石圆锯片，并进行锯切实验以揭示其锯切性能以及锯切参数的变化对其性能的影响。 通过实验研究和理论分析，本论文取得的主要成果和结论有： 1、经断口分析、锯切实验及锯切后节块表面磨粒状态观测表明，选用合适的铁基金属结合剂配方和表面金属化的高品级金刚石磨料制备的锯片节块完全能满足大切深锯切的要求，并实现了120mm锯切深度的大切深锯切实验。 2、锯切过程中锯片承受的总锯切力和单颗金刚石磨粒承受的平均载荷都随着锯切深度a_p或进给速度v_f的增大而增大；锯切深度a_p对总锯切载荷的影响程度比进给速度v_f大。而对于单颗磨粒平均承受的载荷，v_f对其的影响要比a_p大。固定a_p和v_f锯切花岗石时，在不引起锯片振动增加的情况下，锯切载荷随着锯片圆周线速度v_s的增大而减小。 3、锯切能量主要消耗在锯片与锯屑的摩擦以及与花岗石的划擦上。锯切切向力F_t与单颗金刚石耕犁的两侧面面积A_g、锯切法向力F_n与锯切弧区内法向接触应力σ_n，都有着较好的对应关系，在此基础上推导建立的锯切力模型与实验数据吻合较好。花岗石超大切深锯切机理与技术研究 4、首次将金刚石磨损状态细分成12种状态，通过金刚石节块工作表面状态对锯切力影响程度的量化分析表明，磨粒的平均出刃高度与锯切力呈负相关关系，出刃高度越大，锯切力越小。节块工作表面上完整、微破碎和磨平面较小的金刚石磨粒所占的比例越多，锯片也就越锋利，锯切力越小;而宏观破碎、磨平面较大和脱落的磨粒所占的比例越多，则锯片越钝，锯切力也越大。 5、锯切弧区内锯切载荷可以认为基本上是按三角形规律分布的。有限元分析发现，锯切弧区内由于不同位置的金刚石的切削厚度的不同以及冷却水槽的存在，金刚石节块表面前后端承受的载荷存在梯度，而且随着节块长度的增大而增大。通过有限单元法对锯片进行动力学分析发现，锯片的固有频率和临界载荷都随着锯片厚度、转速和夹紧比的增大而增大，随着锯片直径的增大而减小。 6、新型短齿结构锯片可以减小锯切弧区内金刚石节块前后端的应力梯度，还有利于将冷却液导入锯切弧区，提高锯片在锯切弧区内的容屑和排屑能力，降低锯片与锯屑在锯切弧区内的摩擦作用，减少磨耗，从而降低大切深锯切花岗石时锯片承受的载荷。 7、采用超薄锯片进行花岗石锯切可以大量地节约原材料和能源的消耗，但是随着锯片厚度的减小，锯片的固有频率和临界载荷急剧减小。通过在距离锯片临界转速一定范围内增大锯片转速和在现场工艺条件允许的情况下增大夹紧比等方法提高锯片的刚度，以及采用不等距断续槽降低激振频率的手段，都有望改善锯片的振动特性。但是圆周线速度越高，功耗也增大，冷却液进入锯切弧区的难度也增加。因此，需要提出更加有效的冷却和润滑技术。更多还原

【Abstract】 Cutting is a key process during the production of granite slabs. It influences not only on the cost effectiveness of the current procedure, but also on the efficiency and quality of the subsequent procedure in production. At present, sawing granite with diamond tools is the most popular method, which consumes most of synthetic industrial diamond. Relative to early technique for granite machining, cutting with diamond circular saw-blade revolutionizes the whole sector both in reducing the cost and in improving the efficiency. However, the revolutionary meanings seem to embody in the processing of the marbles. The maximum cutting depth for granites, especially for hard granites, is much less than that for marbles.Based on the thorough analysis on the state of arts of granite sawing and the existing problem, the mechanism for sawing of granites under the conditions of large depth of cut is discussed in this thesis, and a new type of diamond saw-blade with short segments is developed to realize deep sawing of granites. The main work of this thesis can be summarized as follows:1. Make diamond saw-blade of normal structure with iron-base metal matrix; set up the platform for the experiment and test of the deep sawing of granites; during the sawing of the granite, monitor the sawing power and forces, observe and count the worn pattern of the grits in the surface of the diamond segments, and measure the protrusion height of the grits.2. Discuss the mechanism of the deep sawing of granites; build model of sawing loads; make statistic analysis of the worn pattern of the grits and the influence of protrusion height on the sawing loads.3. Analyze the stress distribution of the saw-blade during the sawing by Finite Element Method (FEM); study the influence of the thickness, rotary speed, clamping ratio and diameter of the saw-blade on its dynamic performance by modal and buckling analysis.4. Based on the analyses mentioned above, develop a new type of diamond circular saw-blade with short segments, and find out its sawing performance and the effect of processing parameters on its performance by sawing experiment.Through experimental study and theoretical analysis, the following achievements and conclusions can be obtained:1. From the fracture analysis, sawing experiment and observation of the grit state in the segments surface after sawing, it indicated that the segments which were made up of appropriate iron-base metal matrix and high grade coated diamond, can meet with the need of deep sawing, and carry out the experiment of deep sawing at 120mm depth of cut.2. During the sawing process, the total sawing forces acting on the saw-blade and average loads acting on each diamond grit increase with the depth of cut (ap) or the feed speed (vf). ap contributes more to the total forces than Vf, whereas Vf contributes more to the average loads than ap. When keeping ap and Vf constant, the sawing forces decrease with the peripherallinear speed vs in case of not increasing the vibration of the blade.3. The sawing energy is mostly consumed by the friction between the saw-blade and the swarf and by the scratch of the grits with the granite. The tangential force component has good corresponding relation with the bilateral surface area plowed by a diamond grit, and such relation also exists between the normal force component and the normal contact stress at the sawing arc zone. The force models that derived from these relations are quite identical to the experiment results.4. The worn pattern of the diamond grits have been subdivided into twelve states for the first time. Quantified analysis of the effect of the working state of the diamond segment surface on the sawing forces indicates that the average protrusion height of the grits is negatively correlated with the sawing forces. The larger the protrusion height is, the smaller the sawing forces are. The bigger the proportion of the whole, micro-fractured and flatten with little face grits are, the sharper the saw-blade is, and the smaller the sawing forces更多还原