基于流体动力润滑理论的深孔加工直线度误差分析研究

发布时间：2018-03-21 15:58

  本文选题：深孔加工　切入点：直线度误差　出处：《中北大学》2015年博士论文　论文类型：学位论文

【摘要】：随着市场经济对制造业发展的多样性要求，机械零部件产品正以高效率、低成本的形式展现在人们面前；作为制造业的重要组成部分，深孔加工正面临着小批量、多品种、异型孔、新型材料、高难度及越来越高精度要求的挑战。深孔加工由于其特有的加工难点和使用要求，如何获得在尺寸精度、圆度、直线度、圆柱度和粗糙度等方面都很高精度的深孔，长期以来一直是人们最为关注的热点问题。在深孔加工过程中，深孔轴线容易发生偏斜，当偏斜发展到一定程度后，深孔加工的直线度就开始急剧恶化，人们采用了提高机床、工装、刀具精度和刚度等多种方法改善深孔加工直线度误差，但是到目前为止尚未得到很好的解决。故此，本文基于流体动力润滑理论，从深孔加工切削液流体动力特性、切削液对BTA旋转钻杆的动态干扰、切削液流体的入口压力特性及深孔加工直线度误差的测量等方面，研究深孔加工直线度。主要研究内容如下： （1）针对深孔加工过程中旋转钻杆受到切削液流体力的特点，依据流体Reynolds方程及钻杆弯曲变形、倾角方程，建立了深孔加工直线度误差方程，揭示了切削液流体入口压力、钻杆转动、涡动、挤压、钻杆结构参数与深孔直线度之间的关系。指出在切削稳定状态下，减小切削液入口压力，增加钻杆转速、减小钻杆涡动速度或者减小钻杆挤压速度等均可改善深孔直线度误差。 （2）深孔加工过程中，负压结构的工作参数对切削液入口压力有很大的影响，，包括喷射系数、排屑口的横截面积比、排出压力、负压级数等。喷射系数和排屑口的横截面积比呈非线性正比关系，负压排出压力随入射压力的增大而增大，增加负压级数对降低切削液入口压力、改善排屑效果及提高深孔加工直线度精度有很好的作用。通过模拟切削液的运动形态，研究切削液在流动中能量的损失，发现曲面喷嘴的负压效果优于锥面喷嘴，多级负压结构优于单级负压结构。 （3）设计了新型多级负压结构，其通过增设分流腔和增加喷射级数来降低切削液入口压力，可有效减小深孔直线度误差；阐述了SFD利用油膜阻尼力减小深孔钻杆的涡动与挤压运动，来提高深孔加工直线度。得出了多级负压结构、共同作用下的深孔直线度误差，试验验证了钻杆在较低切削液流体入口压力、较小涡动和挤压作用下加工的深孔有更好地直线度，为控制深孔加工直线度误差提出新的思路及方案。 （4）基于光电原理，提出了一种利用输出电压的变化规律来准确测量深孔直线度的方法。分析了光电探测器发生平移运动和旋转运动时造成的实际孔中心位置的变化规律。基于最小二乘原理，推导了深孔直线度与输出电压的关系，为深孔直线度光电测量提供了理论基础。利用光电测量原理，设计了一种具有自定位功能、实时显示深孔直线度误差的光电测量装置，可实现深孔直线度的无损自动检测。
[Abstract]:With the diversity of market economy to the development of manufacturing industry, machinery products and parts with high efficiency, low cost in the form of the show in front of people; as an important part of the manufacturing industry, deep processing is facing many varieties, small batch, special-shaped hole, new materials, high difficulty and high accuracy requirements of more and more challenges. The deep hole processing requirements for processing and using the unique difficulties, how to obtain the precision in size, roundness, straightness, roundness and roughness on high precision deep hole, a long time has been a hot issue of concern to most people. In the process of deep hole processing, deep hole axis prone to deviation, when the deviation to a certain extent, the deep processing of straightness began to rapidly deteriorate, people used to improve machine tools, tooling, cutting precision and rigidity of a variety of methods to improve the deep processing of straightness error, but to So far hasn't been solved well. Therefore, this paper based on the theory of hydrodynamic lubrication, the dynamic characteristics of deep hole machining cutting fluid, dynamic interference of cutting fluid on BTA rotary drill, measurement etc. the entrance pressure characteristics and deep processing of straightness error of cutting fluid, research on deep processing of straightness. The main research contents the following:
(1) according to the characteristics of rotary drill deep hole machining process by cutting fluid flow force, based on fluid Reynolds equation and the bending deformation of the drill rod, angle equation, an equation of the deep hole processing of straightness error reveals the cutting fluid entrance pressure, drill pipe rotation, eddy, extrusion, the relationship between the drill pipe structure parameters and deep hole straightness the cutting. Pointed out that in the steady state, reducing cutting fluid entrance pressure, increasing the rotation speed of the drill pipe, drill pipe to reduce eddy velocity or decreasing extrusion speed can improve the drill hole straightness error.
(2)娣卞瓟鍔犲伐杩囩▼涓

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