复杂型线铣刀数字化设计及铣削力预测研究

发布时间：2018-04-19 09:30

本文选题：复杂型线铣刀 + 有限元仿真　；参考：《山东大学》2016年博士论文

【摘要】：汽轮机叶片及转子高速运行在高温度、高压力的环境下,零件不但承受静压力的影响,还承受热冲击、机械冲击等动态载荷,这一方面要求核心零部件材料有着良好的力学性能,同时需要零部件有良好的加工精度、配合精度。因此,整体式复杂型线刀具已广泛应用于核电机组核心部件的生产。根据刀具市场调查,目前国内应用在核心加工工艺的复杂型线刀具,尤其是硬质合金精加工刀具,基本依赖进口。除此之外以转子轮槽为代表的高温零部件加工,其复杂型线刀具的设计方法还是传统的试切法,这种方法存在制造周期长、制造成本高的缺陷,迫切需要借助一些新的数字化技术来指导优化其设计。本文依托国家“高档数控机床与基础制造装备”科技重大专项“汽轮机和燃气轮机叶片及转子轮槽加工系列化刀具应用示范(2013ZX04009-022)”,对整体式复杂型线铣刀的设计方法进行了系统的研究。本文分析了传统复杂型线铣刀的设计思路及其优缺点。基于圆锥铣刀实际应用中的失效状态,确立了分层-定制式的设计理念。在此基础上,提出微元法为基础的复杂型线铣刀数字化设计方法。基于微元法的复杂型线铣刀简化过程中,在铣削切屑结构计算模型的基础上定义了最大等切削厚度模型,将三维铣削过程离散为二维正交切削模型。并通过工艺参数转化模型,将复杂型线铣刀的铣削工艺转化为每个微元段的二维正交切削工艺参数。在此过程中,本文分析了复杂型线铣刀的几何结构及运动状态,基于常螺旋线理论推导建立了适用于复杂型线铣刀的圆锥螺旋线方程及复杂型线铣刀径向角度、法向角度换算模型。通过微元法,将复杂型线铣刀的刃口设计转化为简单二维正交切削刀具刃口结构的设计。在此基础上,本文分析了刀具失效形式,确立了刀具刃口几何结构设计过程的最主要参考指标：刀具抗破损能力。根据不同加工过程的加工要求,定义粗加工及半精加工铣刀刃口设计准则为最小刀尖应力和最低切削温度；精加工铣刀刃口设计准则为最小切削变形比和最小刀尖应力。引入权重系数λ将多指标约束问题转化为基于响应曲面方程的数学模型。引入安全系数K,将刀具材料的抗弯强度衍化为用于评定设计参数合理性的强度临界值。针对传统切法设计刀具成本高及设计周期长的缺陷,本文提出基于有限元仿真建立基础数据库的方法,以期降低设计成本、缩短设计周期。其中,在刃口设计过程中的响应曲面方程充分表达了数据量极大的有限元仿真结果。为保证有限元仿真对刀具设计结果的不利影响,本文对如何建立精确的有限元仿真模型进行了充分详细的研究。其中,分析了材料热物理属性、动态力学性能以及摩擦模型的精确建模方法,并把正交切削实验与有限元仿真结果的主切削力及吃刀抗力进行对比,验证有限元仿真的精度。在精确的有限元仿真模型的基础上,建立了有限元仿真结果(如刀尖应力S、刀尖温度T、切削变形比ξ、切削力Force X和Force Y)关于参数变量(如切削速度v、切削深度ap、前角γ、刃口半径r)的函数表达,进而实现有限元仿真结果的数据库管理及在刀具设计过程中的调用。为了对设计结果进行性能评价,本文基于复杂型线铣刀的几何特征及运动状态分析,建立了复杂型线铣刀的切削刃动态接触模型及整体铣削力预测模型。在建模过程中,定义了复杂型线铣刀工作过程中的四个时间节点：τn、τl、 τs及τe,用于判定复杂型线铣刀的切削刃线及微元切削刃的工作状态,在此基础上,建立了复杂型线铣刀的切削刃动态接触模型,同时提出了微元切削刃单位切削力的二步分解转化模型。考虑螺旋角β及名义型线倾角ω对单位切削力空间分解的影响,建立了微元切削刃单位切削力空间分解转化模型；考虑螺旋线导致的相位角对不同微元切削刃坐标系的影响,建立了微元切削刃单位切削力时间域分解转化模型。通过切削力沿切削刃线在同一方向的可叠加性,建立了整体铣削力集成模型,实现了工作坐标系下的铣削力预测。最后通过整体铣削实验,对整体力预测模型的精度进行验证,结果表明,整体铣削力预测模型可以精确的预测铣削力的频率和幅值,为后续的刀具性能评价奠定了基础。刀具设计的最终目的是投入生产并使用,因此需要进行刀具可制造性检验。本文针对刀具的三维建模及刃磨工艺进行了刀具可制造性检验研究。为实现复杂型线铣刀三维建模,首先基于空间几何的相关理论,建立了复杂型线铣刀刀尖几何、容屑槽、齿背的径向截形数学模型。并基于Pro/E实现了复杂型线铣刀的精确建模。在此基础上,利用NUMROTO完成了复杂型线铣刀的刃磨工艺制定,实现了复杂型线铣刀可制造性检验。为实现复杂型线铣刀数字化设计方法的广泛应用以及高效快捷的刀具设计,本文以上述复杂型线铣刀数字化设计及性能评价方法为依据,基于Visual C# 3.0开发了复杂型线铣刀数字化设计平台,基于Mysql workbench 6.0搭建了复杂型线铣刀数字化设计平台支撑数据库。并借助复杂型线铣刀数字化设计平台完成三把复杂型线铣刀的设计方案,应用于600 MW汽轮机转子轮槽加工过程中三个加工工艺过程。在实际生产中对设计的三把刀具进行应用,并与进口型号刀具进行寿命对比。结果显示,三把刀的刀具寿命均超过进口刀具。此结果充分证明了基于微元法的复杂型线铣刀数字化设计方法的可靠性及可推广性。
[Abstract]:Turbine blade and rotor speed in high temperature and high pressure environment, parts not only withstand the effects of static pressure, also bearing thermal shock, mechanical shock and dynamic load, the demand for the core components of materials have good mechanical properties, also need to have spare parts processing precision, good fitting accuracy. Therefore, overall type of complex line tool has been widely used in the production of core components of nuclear power units. According to the market survey tool, the complex line in the core domestic application processing tool, especially hard alloy finishing tool, the basic dependence on imports. In addition to the rotor slot as the representative of the high temperature parts processing, the complex line the tool design method and the traditional trial cutting method, this method has the defects of long manufacturing cycle, high manufacturing cost, the urgent need for the use of some new digital technology to guide. The design. Based on the major national high-end CNC machine tools and basic manufacturing equipment science and technology projects of steam turbine and gas turbine blades and rotor wheel groove machining tool series application demonstration (2013ZX04009-022) ", on the whole complex profile milling cutter design method was studied. This paper analyzes the design idea of the traditional complex line cutter and its advantages and disadvantages. The actual application state of failure cone cutter based on the establishment of a layered design philosophy - customized. On this basis, the digital design method of complex profile milling cutter is proposed based on infinitesimal method. The process of complex line element method based on the milling cutter is simplified, the chip structure calculation the model is defined on the model of the maximum cutting thickness, the 3D milling process for discrete 2D orthogonal cutting model. And through the process parameters of transformation model, the complex line Milling cutter into 2D orthogonal cutting process parameters of each micro segment. In this process, this paper analyzes the geometric structure and motion state of complex line cutter, conical spiral equation and complex line cutter radial angle often helix theory is developed based on the complex profile milling cutter, normal angle conversion model. By differential method, the complex profile milling cutter blade design into the design of simple 2D orthogonal cutting tool edge structure. On this basis, this paper analyzes the failure mode of this cutter, established the main reference index for the geometry design process of cutting edge: the ability of anti damage. According to the different machining tool the machining process requirements, the definition of rough machining and semi finishing milling cutter blade design criterion for the minimum tip stress and minimum cutting temperature; finishing cutter blade design criterion for the minimum cut The cutting deformation ratio and minimum stress. The weight coefficient is introduced to lambda multiple constraints problem into a mathematical model based on response surface equation. The introduction of safety coefficient K, the derived tool material bending strength was used to evaluate the rationality of the design parameters of critical strength. For the shortcomings of the traditional method of cutting tool design and high cost and design cycle the method proposed in this paper the basic database is established based on finite element simulation, in order to reduce the design cost and shorten the design cycle. The design of response surface equations in the process of the full expression of the great amount of data of the finite element simulation results on the cutting edge. In order to ensure the adverse effects of the finite element simulation of tool design, finite element this article on how to establish an accurate simulation model is studied in detail. The full analysis, thermal physical properties of material, dynamic mechanical properties and friction model precise construction The method and the orthogonal cutting experiment and finite element simulation results of the main cutting force and cutting force were compared to verify the finite element simulation precision. Based on finite element simulation model of precise, established the finite element simulation results (such as the stress of S, the temperature of T, the cutting deformation ratio zeta. Force X and Force Y cutting force) on the variables (such as cutting speed V cutting depth AP, the rake angle, edge radius R) function expression, database management and realize the finite element simulation results and call in tool design process. In order to evaluate the performance of the design results, the geometric analysis characteristic and motion of complex line cutter based on the cutting edge of the dynamic contact model and the whole complex profile milling cutter milling force prediction model is established. In the process of modeling, the definition of four time node complex profile milling cutter in the working process: n tau, Tau L, s and E, is used to determine the line cutting edge complex profile milling cutter and micro cutting edge work status, on this basis, a cutting edge of the dynamic contact model of complex line cutter, decomposition transformation model and put forward the micro cutting edge cutting of the two step. Considering the effects of spiral angle the name and type of line angle Omega unit cutting force space decomposition, a micro cutting edge cutting space decomposition model; considering the influence of phase spiral lead angle on the cutting edge of different element coordinate system, established a unit element cutting edge cutting force in time domain decomposition by cutting force along the cutting model. The edge line in the same direction of stacking, establish the overall integration model of milling force, the milling force work coordinates prediction. Finally through the whole milling experiments, to verify the accuracy of the overall force prediction model, The results show that the model can predict the frequency and amplitude of milling force prediction precision of the whole milling force, laid the foundation for the performance evaluation tool. The final purpose of subsequent tool design is put into production and use, so it is necessary for tool manufacturing test. The 3D modeling and edge grinding process for tool manufacturing research test tool can be carried out. In order to realize the 3D modeling of complex profile milling cutter, based on the theory of space geometry, a complex profile milling cutter tip geometry, groove, the tooth surface radial cross-section. The mathematical model of Pro/ and E to realize the accurate modeling of complex profile milling cutter based on. On this basis, the use of NUMROTO the complex line cutter edge set grinding process, the complex profile milling cutter manufacturing test. For wide application of complex profile milling cutter digital design method and efficient Tool design, the complex profile milling cutter digital design and performance evaluation method based on Visual C# 3 to develop the complex profile milling cutter design platform based on Mysql workbench 6 to build a complex profile milling cutter design platform. And with the support of database based on complex profile milling cutter design platform to complete the three complex line the cutter design, applied to the 600 MW steam turbine rotor slot in the process of the three process. In the actual production of three knives for the design of the application, and service life compared with the imported models tool. The results show that three knife tool life are more than the import tool. This proves the reliability digital design method of complex line element method of cutter and extension based on.

【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG714;TG501.3

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