【作者】 张衡；

【导师】 张建中；

【作者基本信息】 沈阳航空航天大学 ， 机械制造及其自动化， 2012， 硕士

【摘要】 铣削是被广泛采用的一种金属切削加工方法。铣削是断续切削,并且很容易受到外界和自激振动的影响。普通铣削过程中由于系统刚度等因素的影响变得不稳定,刀具与工件时刻做微小的位移,影响加工精度和表面质量。本文研究利用工作台的逻辑进给产生振动切削的机理,强化切削过程。本文主要是对淬硬45号钢进行振动铣削研究。这种材料硬度达到HRC40以上的时,切削加工性较差,其特点是硬度、强度高,脆性大,(导热性差,)在切削加工过程中,切削力大,切削温度高,刀具耐用度低,容易使工艺系统产生振动,从而使加工工件的加工精度低,表面质量差。通过在相对切削刀具施加某种有规律的、可控的振动,从而达到减小切削力、切削热,提高加工质量和效率。本文研究利用数控系统控制工作台的产生逻辑进给,实现脉冲力作用的数控加工方法,即利用数控加工设备的数字控制系统,通过编程指令使工件按照所需的逻辑进给,实现脉冲力作用的振动切削机理。在理论上建立了铣削的数学模型,构建了微分方程,并进行求解,在理论上研究了刀具与工件的动态关系。论文对工艺系统刚度进行了研究和测定,对刚度规律及对加工过程影响进行了分析。通过实验研究了切削参数、逻辑进给和工作台回退速度对切削力、表面粗糙度的关系;同时也研究了振动频率对切削力和表面粗糙度的影响,探讨了其相关的规律;还对切削温度进行了粗略的研究。试验表明,当振动频率满足零位振动切削条件时,切削力、切削温度明显降低,表面粗糙度精度有较明显的提高,可以用普通切削刀具铣削淬硬材料。更多还原

【Abstract】 In the metal cutting, milling is wildly used in the processing methods. Milling is in intermittent in the cutting process, which is affected by the external vibration and inherent vibration easily. The process of normal milling will be unstable because of stiffess of process. The machining accuracy and surface quality will be affected by the small displacement of tool and workpiece. This paper studies the mechanism of vibration cutting under the logic feed of workbench, which can strengthen the cutting process.In this paper, vibration milling of hardened 45 steel is studied. Machinability is poor when the hardness of this material exceeds HRC40, and this moment its characteristic is high hardness and intensity, prodigious brittleness, poor thermal conductivity prodigious cutting force, high cutting temperature, lower tool life, caused easily vibration so that the machining accuracy of workpiece is low and the surface quality is poor. By exerting certain regular and controlled vibration on relative cutting tool, cutting force and heat would be decreased and processing quality and efficiency would be improved. In this paper, the CNC machining methods of realizing the effect of pulse force is studied by the use of logic feed, which is engendered by using the CNC workbench. By programming instructions, that is to say, workpiece can realize the pulse of the force under vibration cutting mechanism according to required logic feed by the using the digital control system of numerical control processing equipment. The mathematical model of the milling established, and the differential equation is established and solved theoretically. the dynamic relationship between the tool and the workpiece is studied theoretically.the stiffness of the process system is measured. The law of stiffness and the affect of pocess is analysised .the relation of cutting perameter and logic feed and the speed of workbench with cutting force and surface roughness are studied. And the influence of vibration cutting frequency for cutting force and surface roughness are discussed in this paper. The dynamic displacement between tool and workpiece is analyzed though Matlab.Tests show that when the vibration frequency to meet the zero-vibration cutting conditions, cutting forces and cutting temperature significantly reduced, the surface roughness accuracy has improved significantly, hardened materials can be machined by the ordinary cutting tool.更多还原