文献翻译-分析模型导轨磨损的演算对机床加工精度的影响

附录一 外文文献翻译ANALYTICAL MODEL OF CALCULUS FOR INFLUENCE THETRANSLATION GUIDE WEAR OVER THE MACHINING ACCURACY ON THE MACHINE TOOLAf.dr.eng. Ivona PETRE, University Valahia from TargovisteLecturer dr. eng. Carmen POPA, University Valahia from TargovisteLecturer dr. eng. Dumitru DUMITRU, University Valahia from TargovisteEng. Ciprian MANESCU, University Valahia from TargovisteAbstract: The wear of machine tools guides influences favorably to vibrations. As a result of guides wear, the initial trajectory of cutting tools motion will be modified, the generating dimensional accuracy discrepancies and deviations of geometrical shape of the work pieces. As it has already been known, the wear of mobile and rigid guides is determined by many parameters (pressure, velocity, friction length, lubrication, material). The choice of one or another analytic model and/or the experimental model of the wear is depending by the working conditions, assuming that the coupling material is known.The present works goal is to establish an analytic model of calculus showing the influence of the translation guides wear over the machining accuracy on machine-tools.Keywords: accuracy, machine-tools, surface.1.IntroductionAs it has already been known the accuracy of machining each piece depends on a multitude of factors connected to the technological system (the machine tool, the clamping device, the cutting tool etc) 1, 2, 3.In the present work, the authors goal is to establish the size and influence only of the wear of the bed the slide guide over the machining accuracy on machine-tools with use on lather. The size of the guide and (longitudinal) slide wear are important to be known because the change of the slide trajectory due to the wear that occurs in time conditions the dimensional deviations and the quality of the machined parts surface.In order to establish the wear size of the system bed-slide, three distinct situations are being analyzed:1 the bed guide only is being worn2 the slide guide only is being worn3 both guides (bed-slide) are being worn2. Analytic models establishing the error produced by the bed-slides wear.In order to establish the quantitative influence of the wear process over the machining accuracy on a lathe, the following assumptions are made 2:-the curve of the worn profile of the rigid guide U(x) is considered known at a certain moment assessed by the number of the stress cycles;- the wear on the current stress cycles is neglected compared to the wear produced by all the previous cycles;- the mobile guide wear U1(l) is so produced that the profile of this guide follows continuously the rigid guide profile; based on this assumption it is admitted that the contact is always of the type according to the appropriate distribution of the normal and tangential stress;- the mobile guide is set on the rigid one during the displacement so that normal line to the contact surface of the two profiles is unique;- the wear is a continuous process and is characterized by the thickness of the worn layer, considered as a continuous function onto the guide length and in time.Based on these assumptions the wear of the bed and slide guide is established for the 3situation shown in the first part of the work.Case 1: the bed guide is being only (fig.1)Fig.1. Settlement scheme of the mobile slide on a bed-guideTaking a point A (xo, Uxo) situated at the middle of the mobile slide. The wear of the bed guide in the considered point is Uxo and the function of the bed guide wear Ux. The deviation of the point A is considered 1 = AC .In order to establish, the coordinates of the point C the normal at the bed guide profile in the point A is considered a straight line with the slope m that can be determined based on the wear function Ux.（1）nmxy（2）XM/1where： UadUXX1Being the conditions to limit, the co-ordinates of the point C will be y c = 0 andx c = U x U x + x .The deviation in this case considered:（3） admXXAcAcy2221 )(1)()(Case 2: the slide guide only is being worn according to a linear variation law (fig.2). Considering the point B(0,b) situated at the half of the slide with the length l. After a certain period of functioning, as a result of the slide wear, the point B will be displaced in the point B. In this situation the deviation of the point will be: 2 = BBIn order to make the calculation of this deviation 2 cases can be distinguished:a) the point A is not worn U A = 0 ; b) the point A is worn by a size that can be established (measured) U A 0Fig. 2. Assessment scheme of the mobile slide geometry changesStaring from the equation of the straight line that goes through the points AO and following the some argument as in case 1, the deviation of the point B will be:-when 2/cos202baUA-when /)( AUThe size of the angle depends on the size of the accuracy deviation imposed to the slide:1CMAtgThe angle can be known if the wear of the point C, Us and adm are measured(known).The allowable size of the angle adm is a size that can be established from the accuracy conditions imposed by the machine tool on which the slide is installed where: （5）lAiltgprawhere: Ai the initial deviation that can be accepted as being the maximum allowable deviation prescribed within the accuracy parameters of the machine-tool;App the accuracy deviation allowable of the parts machined on the machine tool;Ara the allowable relative deviation of accuracy;l slide lengthCase 3: booth the mobile slide U1 (l) and the bed U(x) are worn as in figure 3.Fig. 3. Assessment scheme of the changes caused by wearThe straight line at the bed guide in a point is a line having m slope that can be established based on the wear function U (x). Following the some argument as in cases 1 and 2 for a common point M on the bed and slide guide the changes of the co-ordinates of this point will be:（6）211 )()()(MM xxUBAy （7）211 )()(sinMyxThe deviation from the abscissa implies the axial position change of different tronsons of the machined parts.The total deviation a is considered to be the size that characterizes the loss of accuracyas a result of the wear process of the mobile and fixed guide:（8）admxy23. Explanation of the wear functionAs concerns the types explanation of the process that has produced them there is no unanimous agreement. Actually, the different way some or other assumptions with reference to the evaluation of the complex phenomena a friction-wear-lubrication is accepted, has influenced the classification of the various types of wear noticed in the industrial practice regarding the aspect and the deterioration degree of the surfaces.Depending on the way and size of the wear process measurement of a friction couple slide bed guide type the most accessible to any engineer is to establish the worn layer thickness namely the linear wear 4.In order to find a more correct relation ship of the wear size a linear dependence between the wear time t and the wear size U is considered, the wear velocity being constant in time:（9）tUudvStarting from the assumption unanimous recognized namely at the no continuous lubrication film can be formed at the normal lathers, the wear is assessed to be adhesive and or abrasive type and the removal of a wear particle is a cumulative process of contact fatigue through elastic, plastic or elastoplastic deformations 2, 3, 4.Under this circumstances the dimensionless linear intensity (Iu) considered as on indication of the wear process, depending on the material characteristics (elasticity modulus E, rupture stress for one cycle o, the fatigue parameter Whler to type), also depending on the microgeometry characteristics and on loading characteristics (contact pressure p, friction coefficient ) 2, 4 the form of the wear in a point M situated on the couple bed slide will be:- for the bed guide:（10）12012 1)()(MrvrpMubofuXM dxPxIHNdLIU- for the slide guide: （11）00111 )()(l rvMrpubofuMxlPIdIwhere: No the number of the total strokes within the worning period; l1, l2 lengths characteristic for the wear area of the bed guide;(x), prp(x), prv(x) the use coefficient, the load coefficient and velocity coefficient that are considered to have different variation laws (uniform, linear, normal);Hb the total length of the bed guide;Iu01, Iu02 the wear intensity of the bed guide material, respective of the slide.4. The quantitative influence of the wear process over the machining processDeviations from the axial positionDeviations from the radial positionDeviations from the total positionFig. 4. Deviations from the position of the bed-slideBased in the three cases that have been analyzed (when the bed guide only is worn,when the slide guide only is worn or both) the deviations, that characterize the accuracy loss as a result of the wear process of the friction couple elements, can be established knowing the wear size.Thus, taking into consideration the most disadvantageous case (but the most possible one) when both the bed guide and the slide guide are worn figure 4 shows the deviation of the radius (deviations from the co-ordinate of the considered point) of axial positioning (deviations from abscises of the analyzed conditions expressed by the variation laws of the use coefficient, loading coefficient and velocity coefficient that characterize the couple wear tribologically standpoint 2.5. ConclusionsAs can be noticed in figure4, the deviations of axial position (x) show discontinuities in the passing points from one working area to another one, function of the worn guide curve slide. This discontinuity results from the condition that the profiles of the worn mobile guide and of the fixed one are always continuously followed and they have a common contact point.The radius deviations (y) are always continuous functions, so as the profiles of the machined parts in the radial direction will be “smooth” but with circular shapes of various radius.Given the facts presented, we can conclude that by having the possibility to know the wear size beginning with the projecting status, a better choice of the material couples can be made for bed-slide, a correct evaluation of the overall dimensions of slide and of the guide can be made and an estimation closer to the ones as concerns the size of the exploitation factors (pressure, velocity, lubrication etc.).We cant ignore the accuracy over the machined part shape, slide that as it dread been known can be influenced in a smaller or bigger way by the shape of the bed and slide guide wear.References1 Militaru, C., Fiabilitatea si precizia n tehnologia constructiilor de masini, 1987, Ed.Tehnica Bucuresti;2 Sandu, Gh., Moraru, V. , Minciu, C., Ghidajele masinilor unelte, 1967, Ed. Tehnica Bucuresti;3 Pavelescu, D., Aspecte ale modului in care este corelata evolutia procesului de frecare cu a celui de uzare. Constructia de masini 32, nr.10, 1980, p.495-499;4 Pavelescu, D., Conceptii noi, calcul si aplicatii in frecarea si uzarea solidului deformabil, 1970 Ed. Academiei romane.分析模型导轨磨损的演算对机床加工精度的影响Af.dr.eng. Ivona PETRE, University Valahia from Targoviste,Lecturer dr. eng. Carmen POPA, University Valahia from Targoviste,Lecturer dr. eng. Dumitru DUMITRU, University Valahia from Targoviste,Eng. Ciprian MANESCU, University Valahia from Targoviste,摘要：机床导轨的磨损有利影响到振动。作为指导的结果磨损，刀具运动的初始轨迹将被修改，尺寸精度产生差异的工件的几何形状和偏差。因为它已经成为连接称为移动和刚性导轨的磨损取决于许多参数（压力，速度，长度摩擦，润滑，材料） 。一种或另一种分析模型和/或磨损的实验模型的选择取决于所的工作条件，假设被称为耦合材料。目前的工作的目标是建立一个分析模型的演算显示导轨的影响磨损在工具机的加工精度。关键词：精度 机床 表面。1.简介因为它已经被称为加工每个工件的精度取决于多种连接技术的系统（该机床，夹紧装置，刀具等）的因子1，2，3。在目前的工作，笔者的目标是建立规模和影响力的床身在对车床使用的机床的加工精度，导轨的磨损。导轨的大小和（纵向）滑动磨损是重要的被称为因为滑动轨迹，由于磨损，时间条件下发生的尺寸偏差和加工零件的表面质量的变化。以建立系统的床身滑动磨损大小，三种不同的情况正在分析：1.床身导轨正在磨损2.导轨只被磨损3.导轨（床身滑动）正在磨损2建立床身滑动产生的误差分析模型磨损为了建立在加工的磨损过程的定量影响车床的精度，以下假设2：被认为是在一定的刚性指南 U（X）的磨损轮廓曲线时刻评估应力循环的数量; 比以前所有的周期产生的磨损，被忽视的电流应力周期的磨损 ;移动导轨磨损 U1（L ）是这样产生的，该导轨的性能如下；不断刚性指南轮廓; 基于这个假设，它是承认接触的类型始终是按照正常和切向应力的适当分配;移动导轨位移在两个剖面的接触面，使正常的线是独一无二的刚性;磨损是一个连续的过程和特点是由连续拖到指导长度的功能和时间的考虑，磨损层的厚度。这些假设的基础上建立的床身和导轨的磨损 3 在工作的第一部分显示的情况。案例 1：床身导轨（图）图 1 解决方案床身导轨伤的移动导轨以一个（XO，UXO）点，坐落在中间移动导轨。在考虑点的床身导轨的磨损是 U XO 和床身导轨磨损 UX 的功能。该点的偏差， A 被认为是 AC 1=。为了建立，在床身导轨的轮廓 A 被认为是一个直线的斜率 m，可以根据磨损功能 UX 正常的 C 点的坐标。（1）nmxy（2）XMU/1这里： adUXX1作为限制的条件下，C 点的坐标，将 YC= 0 和 XC = UxUx+ X在这种情况下偏差考虑：（3）admXXAcAc Uyx 2221 )(1)()(案例二：导轨只被磨损根据线性变化规律（图 2） 。考虑到 B 点（0，B ） ，坐落在幻灯片的长度 l 的一半。后一定时期的运作，作为一个滑动磨损的结果，将在 B 点在 B 点流离失所。在这种情况下，点差将是：2= BB 为了使这种偏差的计算可分为 2 例：a）点没有磨损 UA= 0;b）在 A 点磨损一个可以成立（测量）UA 的大小0图 2 移动导轨几何变化评估计划盯着从直线的方程，通过点的 AO和以下一些参数，如例 1，B 点的偏差将是：-当 2/cos202baUA-当 /)( AU角 的大小取决于强加给导轨的准确性偏差的大小：（4）1CMtg角 可以知道，如果 C 点的磨损，我们和 的 adm 测量（已知） 。允许的角度 adm 的大小是一个可以从机床上安装在导轨中所规定的精度条件下建立大小：（5）lAiltgpra其中：Ai- 可以作为最大允许接受的初始偏差偏离规定范围内的机床精度参数; APP-精度偏差允许在机床上加工零件;ARA-相对偏差在允许的精度;L - 导轨长度案例 3：展位移动导轨 U1（L）和床身 U（X）的磨损，如图 3图 3 由磨损造成的变化评估计划在床身导轨在一个点的直线是一条线，有 m 的斜坡，可以建立基于磨损函数u（x） 。继一些参数的变化引导上常见的 M 点的床身和导轨在例 1 和 2 这一点的坐标将是：（6）211 )()()(MMM xUxUBAy （7）211 )()(sinyx从横坐标的偏差意味着加工零件的不同 tronsons 轴向位置的变化。总偏差 a被认为是特点为移动和固定导轨的磨损过程的结果的精度损失的大小：（8）admxya23.磨损功能的说明由于担心类型的解释，他们已经产生的过程是没有达成一致意见。事实上，一些不同的方式或其他复杂的现象，摩擦磨损润滑接受评估参考假设，影响了在工业方面的做法注意到磨损的各类分类和恶化程度表面。根据摩擦的一队滑床导轨类型的磨损过程测量方式和规模，最方便到纽约工程师是建立磨损层厚度，即线性磨损4。为了找到一个更正确的关系，磨损大小之间的磨损时间 t 和磨损大小 林耳依赖被认为是，磨损速度常数时间：（9