颗粒阻尼及磁流变复合减振镗刀的研究

发布时间：2018-07-05 02:36

本文选题：颗粒阻尼 + 磁流变液　；参考：《中北大学》2017年硕士论文

【摘要】：切削加工领域中,刀具的切削振动严重影响着加工工件的表面质量,制约着加工效率的提高,尤其是对于精密孔、深孔的镗削加工,因其加工需要的镗刀长径比较大,镗刀的抑振效果必须要好,而普通镗刀往往满足不了工件孔加工质量的要求。因此,大长径比镗刀的颤振抑制技术已经成为重要的研究课题。本文针对大长径比镗刀的切削颤振现象,将颗粒阻尼减振技术和磁流变减振技术共同运用于大长径比镗刀中,设计出颗粒阻尼及磁流变复合减振镗刀,不仅可以通过颗粒之间、颗粒与镗杆腔壁之间的碰撞与摩擦来消耗振动能量,产生减振效果,而且还可以通过磁流变液的阻尼特性、实时调控性改变复合减振镗刀的固有频率从而避免共振的发生,达到抑振的目的。主要研究内容与结论如下:1.阐述了课题背景及研究意义,详细介绍了减振镗刀的发展,重点介绍了颗粒阻尼减振技术和磁流变减振技术的工作机理以及国内外研究现状,提出了本文的主要研究内容。2.研究了颗粒的物质特性,分别根据离散单元法与接触力学原理建立了阻尼颗粒的力学模型,提供了颗粒阻尼系统总接触力、总扭矩以及能量耗散的计算方法。3.建立了颗粒阻尼镗刀的动力学模型,并在不同的填充颗粒参数下对其进行了锤击与镗削实验,以检验颗粒阻尼技术在减振镗刀中的可行性,测试镗刀的性能,结果表明:填充颗粒直径越小,密度越大减振效果越好,当填充率为70%时,减振效果最佳;选取合理填充颗粒参数时,镗刀阻尼比最高达到4.38%,镗削后的工件表面粗糙度Ra值最低为1.392μm相比于实心镗刀降低了50.13%,颗粒阻尼镗刀切削性能良好。采用正交试验方法,确定了影响镗刀切削性能的主要和次要填充颗粒参数,找到了试验因素对镗刀切削性能的影响规律,最终得出了最优方案组合。4.阐述了磁流变液的流变机理,详细介绍了磁流变液工作模式的分类及原理。根据四种磁流变液阻尼的动力学模型,建立了一种修正的Bingham模型,该模型既充分体现了磁流变液的阻尼特性,又具备Bingham模型简单、实用性强的优点。建立了简化的磁流变液流动特性模型,据此计算出磁流变液的阻尼力。5.介绍了颗粒阻尼及磁流变复合减振镗刀的结构组成、装配方式以及工作原理。镗杆采用了三段式以对焊工艺进行连接,选定了镗杆材料,根据材料力学原理结合估算法确定出镗杆的尺寸;选定了磁流变减振系统的材料,考虑到结构尺寸限制,设定了磁流变减振系统的长度和镗杆轴肩的高度,依据理论,选取了磁流变减振系统三种主要结构参数各三组值作为下一步正交试验的因素水平,通过查询手册与国标确定出励磁线圈的电流密度和型号,并根据安培环路定理算出其匝数,构造L9(34)正交试验表,以ANSYS二维静态磁场分析得到的阻尼通道处的磁感应强度为评价指标,通过极差分析确定出磁流变减振系统的尺寸,最终设计出颗粒阻尼及磁流变复合减振镗刀。6.利用ANSYS对复合减振镗杆进行模态分析研究其前四阶固有频率与振型,结果表明:随着励磁线圈电流从0A增大到2A其各阶固有频率都得到提高,一阶固有频率从450.69Hz提高到了505.81Hz,各阶振型的相对位移降低,复合减振镗杆具有良好的动态性能可控性以及抑振性能;通过谐响应分析研究复合减振镗杆最前端外圆处一节点的一阶固有频率的响应,结果表明:随着励磁线圈电流从0A增大到2A,该节点处一阶固有频率的响应幅值明显减小,0A时响应幅值为3.436μm,而2A时仅为0.908μm,进一步证实了复合减振镗杆良好的动态性能可控性和抑振性能,颗粒阻尼及磁流变复合减振镗刀达到了设计目的。
[Abstract]:In the field of cutting, the cutting vibration of the cutting tool seriously affects the surface quality of the workpiece, and restricts the improvement of the machining efficiency. Especially for the precision hole, the boring machining of the deep hole, the boring tool must be better to suppress the vibration of the boring cutter because of the larger bore length of the boring tool, and the ordinary boring knife can not meet the machining quality of the workpiece. Therefore, the flutter suppression technology of the large length diameter ratio boring cutter has become an important research topic. In this paper, the particle damping technology and magnetorheological damping technology are applied to the large length diameter ratio boring tool to design the particle damping and magnetorheological compound damping boring cutter, which not only can be used in the large diameter ratio boring tool, but also the particle damping and magnetorheological damping boring cutter can be designed. The collision and friction between the particles and the wall of the boring bar are used to consume vibration energy and produce vibration damping effect. Moreover, the natural frequency of the compound damping boring cutter can be changed by the damping characteristic of the magnetorheological fluid, so as to avoid the occurrence of resonance and achieve the purpose of vibration suppression. The main contents and conclusions are as follows: 1. the main contents and conclusions are as follows: The development of the vibration boring cutter is introduced in detail, and the mechanism of the damping and damping technology and the working mechanism of the magnetorheological damping technology are introduced in detail. The main research contents of this paper,.2., are put forward, and the material properties of the particles are studied, and the discrete element method and the contact mechanics principle are established respectively. The mechanical model of the damping particles provides the calculation method of the total contact force, the total torque and the energy dissipation of the particle damping system.3.. The dynamic model of the particle damping boring cutter is set up, and the hammer and boring experiments are carried out under the different filling particle parameters to test the feasibility of the particle damping technology in the damping boring tool and the test boring. The performance of the cutter shows that the smaller the diameter of the filling particle is, the better the damping effect is, the better the damping effect is. When the filling rate is 70%, the damping effect is the best. The damping ratio of the boring cutter is up to 4.38% when selecting the reasonable filling particle parameters. The Ra value of the surface roughness after the boring is 1.392 mu m compared to the solid boring cutter, 50.13% and the particle damping boring. The cutting performance of the cutter is good. Using the orthogonal test method, the main and secondary filling particle parameters that affect the cutting performance of the boring cutter are determined. The influence of the test factors on the cutting performance of the boring cutter is found. Finally, the optimum scheme combination.4. is obtained to explain the rheological mechanism of the magnetorheological fluid, and the classification of the working mode of the magnetorheological fluid is introduced in detail. According to the dynamic model of four kinds of magnetorheological fluid damping, a modified Bingham model is established. The model not only fully embodies the damping characteristic of the magnetorheological fluid, but also has the advantages of simple Bingham model and strong practicability. The simplified model of the flow characteristics of the magnetorheological fluid is established, and the damping force.5. of the magnetorheological fluid is introduced. The structure composition, assembly mode and working principle of the particle damping and magnetorheological damping boring cutter are made. The boring bar adopts three sections to connect the welding process, selects the boring bar material, and determines the size of the boring bar according to the mechanics principle of material, and selects the material of the magnetic flux and vibration damping system, taking into account the limitation of the structure size, The length of the magnetorheological vibration damping system and the height of the shaft shoulder of the boring bar are set. According to the theory, the three values of the three main structural parameters of the magnetorheological vibration damping system are selected as the factor level of the next orthogonal test. The current density and model of the excitation coil are determined by the inquiry manual and the national standard, and the turns are calculated according to the ampere loop theorem. The L9 (34) orthogonal test table is constructed, and the magnetic induction intensity at the damping channel obtained by the ANSYS two-dimensional static magnetic field analysis is the evaluation index, and the size of the magnetorheological damping system is determined by the extreme difference analysis. Finally, the particle damping and the magnetorheological compound damping boring tool.6. are designed to study the modal analysis of the compound damping boring bar with the ANSYS. The first four order natural frequencies and modes of vibration show that the natural frequencies of each order increase with the excitation coil current from 0A to 2A, the first natural frequency is increased from 450.69Hz to 505.81Hz, the relative displacement of each order mode is reduced, and the composite damping boring bar has good dynamic performance controllability and vibration suppression performance; the harmonic response analysis is used. The response of the first order natural frequency of a node at the front end of the composite damping boring bar is studied. The results show that the response amplitude of the first natural frequency of the excitation coil decreases obviously with the excitation coil current increasing from 0A to 2A, and the response amplitude is 3.436 m at 0A, while 2A is only 0.908 mu m, which further confirms the good dynamics of the compound damping boring bar. Performance control and vibration suppression performance, particle damping and magnetorheological composite damping boring cutter achieve the purpose of design.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG53

【参考文献】