钎焊金刚石薄壁钻的制备与磨损研究

发布时间：2018-05-17 06:02

本文选题：钎焊金刚石薄壁钻 + 磨损形式　；参考：《大连理工大学》2016年硕士论文

【摘要】：氮化硅工程陶瓷球阀以其优异的耐磨性、高硬度、抗腐蚀性等特点,广泛地应用于化工、冶金、核能、污水处理等工业领域。由于氮化硅工程陶瓷材料本身的高硬度和高脆性,对其进行孔加工十分困难。目前,氮化硅工程陶瓷孔加工的首选方式是利用钎焊金刚石薄壁钻对其进行机械钻削。本文通过对氮化硅工程陶瓷进行孔加工试验,开展了对钎焊金刚石薄壁钻的制备与磨损研究。首先,在分析氮化硅工程陶瓷加工性能的基础上,研究了钎焊金刚石薄壁钻制备时金刚石磨粒、钎料及基体的选用原则,确定了钎焊金刚石薄壁钻的制备方法,制定了制备的工艺流程。选用粒度为45/50的SMD金刚石磨粒、Ni基钎料和45钢作为制备钎焊金刚石薄壁钻的主体材料,钎焊方法为真空钎焊法。其次,采用SEM扫描电子显微镜与体视显微镜对孔加工后的钎焊金刚石薄壁钻钻头进行观察,归纳了钎焊金刚石薄壁钻的磨损形式,研究了其磨损机理和磨损过程。将钎焊金刚石薄壁钻的磨损分为金刚石磨粒磨损与粘结剂磨损。金刚石的磨粒磨损形式分为剥落磨损、点蚀磨损、破碎磨损、磨粒脱落和磨粒磨平；粘结剂磨损形式分为粘结剂的小面积轻微脱落和大面积连续脱落。在加工初始阶段,主要磨损形式为磨粒的破碎磨损、磨粒脱落及粘结剂的大面积脱落；在加工过渡阶段,主要磨损形式为金刚石磨粒的磨平磨损和粘结剂的小面积脱落；在加工的最后,大部分金刚石磨粒磨平,钻头失效。最后,以10mm的加工深度为指标,分别研究了机床转速、恒定钻压和钻头壁厚对钎焊金刚石薄壁钻磨损的影响。提高机床转速,金刚石磨粒的破碎磨损与磨平磨损比例增大,磨粒脱落比例几乎不变；提高恒定钻压,金刚石磨粒的破碎磨损、磨粒脱落比例增大,磨粒磨平比例几乎不变；增加钻头壁厚几乎不会影响磨损程度。试验发现,钎焊金刚石薄壁钻在对氮化硅工程陶瓷孔加工时,机床转速选择在710r/min,恒定钻压选择705N,钎焊金刚石薄壁钻的厚度选择在1.5mm,能够较好地控制磨损并得到较高的加工效率。
[Abstract]:Silicon nitride engineering ceramic ball valves are widely used in chemical, metallurgical, nuclear, sewage treatment and other industrial fields due to their excellent wear resistance, high hardness, corrosion resistance and so on. Due to the high hardness and brittleness of silicon nitride engineering ceramics, it is very difficult to process them. At present, the first choice of silicon nitride engineering ceramic hole machining is to use brazing diamond thin-wall drill to drill it. In this paper, the fabrication and wear of brazed diamond thin-walled drill were studied by hole processing test of silicon nitride engineering ceramics. Firstly, on the basis of analyzing the machining properties of silicon nitride engineering ceramics, the selection principle of diamond abrasive, brazing filler metal and matrix during the preparation of brazed diamond thin-walled drill is studied, and the preparation method of brazing diamond thin-walled drill is determined. The process of preparation was established. The SMD diamond grain size of 45 / 50 and 45% steel were selected as the main material for the brazing of diamond thin-walled drill. The brazing method was vacuum brazing. Secondly, SEM scanning electron microscope and stereoscopic microscope are used to observe the brazed diamond thin-walled drill bit after hole machining, and the wear patterns of brazed diamond thin-walled drill are summarized, and the wear mechanism and wear process are studied. The wear of brazed diamond thin-wall drill is divided into diamond abrasive wear and binder wear. The abrasive wear forms of diamond can be divided into spalling wear, pitting wear, crushing wear, abrasive shedding and abrasive grinding, while the wear forms of binder can be divided into small area and large area continuous shedding of binder. In the initial stage of processing, the main wear forms are the crushing wear of abrasive particles, the abrasive shedding and the large area exfoliation of binder, the main wear forms in the process transition stage are the abrasive wear of diamond particles and the small area shedding of binder. At the end of the process, most diamond grains are ground and the bit fails. Finally, the effects of machine speed, constant drilling pressure and bit wall thickness on the wear of brazed diamond thin-walled drill are studied based on the machining depth of 10mm. When the rotational speed of machine tool is increased, the ratio of crushing wear and grinding wear of diamond particles increases, and the ratio of abrasive particles falling off is almost unchanged, while the proportion of grinding particles is increased and the proportion of grinding particles flattening is almost unchanged when the constant drilling pressure is increased. Increasing the bit wall thickness will hardly affect the wear degree. It is found that the machine speed is 710r / min, the constant drilling pressure is 705N, the thickness of brazed diamond thin-walled drill is 1.5mm, and the wear can be controlled well and the processing efficiency is higher when brazing diamond thin-walled drill is machined to silicon nitride engineering ceramic hole, the machine speed is 710r / min, the constant drilling pressure is 705N, and the thickness of brazed diamond thin-wall drill is 1.5mm.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TG454

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