机床热态特性的回归分析方法

一、引言机床热态特性是表征机床性能的一个重要方面。Birmingham大学教授J.Peklenik的研究分析表明,在精密加工机床中因热变形影响而造成的工作精度误差占总误差的40％～70％。对机床进行热变形成试验正越来越得到人们的重视。机床热稳定后的最高     

机床热态特性的回归分析方法

<正> 一、引言机床热态特性是表征机床性能的一个重要方面。Birmingham 大学教授 J.Peklenik的研究分析表明,在精密加工机床中因热变形影响而造成的工作精度误差占总误差的40％～70％。对机床进行热变形成试验正越来越得到人们的重视。机床热稳定后的最高温度与温升已成为控制机床质量的通用技术条件,机床热平衡时间作为描述机床热态特性的指标之一。机床热变形试验中,机床真     

第四讲 机床热变形(上)

一、机床热变形及其研究概况 生产过程自动化和精密加工的迅速发展,对金属切削机床的加工精度和精度稳定性提出了越来越高的要求,而加工精度主要取决于机床的两个性能:即机床的静态-动态力学特性和热学特性。据英国伯明翰(Birminghan)大学J.Peklenik教授的调查,在精密加工中,由于热变形引起的制造误差约占总制造误差的40～70%[1]。热变形不仅严重地降低了机床的加工精度,而且影响了机床的生产效率。这是因为,为了避免热变形所进行的机床予热或调整,常常要花费很多时间。有时,由于机床局部(如主轴轴承、液压系统)的急剧温升,甚至使机床无法…     

BFPC填充结构机床立柱设计及其性能分析

为探索提高机床静、动、热态性能和轻量化从而满足机械制造向着高效率、高精度和高自动化程度方向发展需求的新途径,以某立式加工中心的立柱为研究原型,以满足刚度要求和轻量化为约束条件,设计了玄武岩纤维树脂混凝土(BFPC)填充结构机床立柱。利用ANSYS软件对两种结构立柱的静、动、热态性能进行仿真分析,对其轻量化及所需铸铁量进行计算。并将其结果进行对比分析,结果表明,BFPC填充结构机床立柱可在保证轻量化的同时提高机床静、动及热态性能,并有利于实现机床制造的节能减排和绿色环保。     

《机床动力学》(一)

为了适应机床向高精度,高自动化及高柔性发展,除了要求机床重量轻,成本低、使用方便和具有良好的工艺可能性外,对其动态性能的要求也越来越高。因为它直接影响机床的加工质量和切削效率。机床的动态性能主要是指它抵抗振动的能力。对机床进行动力分析和动态设计,使机床具有良好的动态性能,也即把机床的振动量控制在满足加工质量的允许范围之内,使机床在额定功率范围内不发生切削自激振动,这是机床动力学的主要任务。     

新型高阻尼机床主轴的研制及其综合性能试验

本文提出了一种新型的高阻尼机床主轴结构,并对其动态性能、静刚度和热态性能进行了深入研究。试验结果表明:这种在原机床主轴的支承部位增设阻尼圈的高阻尼主轴结构可以在静刚度和热态性能下降很小的情况下,显著地改善主轴系统的动态性能。     

机床主轴热管冷却系统的原理和设计

前言随着机床向高精度及数控方向的发展,对减小加工误差提出了越来越高的要求.影响机床加工误差的因素很多,如主轴系统、进给系统的热变形,刀具的压具的精度及磨损等等.其中最主要的因素是主轴系统的热变形.特别是近年来,为了实现高效率加工,要求提高机床的开动率,重切削及高速切削,从而使机床主轴系统的发热更为严重,导致加工精度恶化.因此,在精密加工中,特别是在数控机床上,防止机床主轴系统热变形已成为当前最重要的研究课题.     

热误差补偿功能在机床领域的应用

随着机床零部件的精度越来越高以及数控系统控制的高速发展,使得几何误差对机床整体的精度影响越来越小。而现代加工机床的加工特点,长时间的处于高速切削和快速进给的状态下连续运转,由于机床运动部件产生摩擦热、切削热以及外部热源等会引起系统的热变形,造成机床床身和主轴丝杠等主要部件的快速升温,且受热不均匀,产生由于温度的变化导致的精度误差,在精密及超精密加工中,热误差的影响非常严重,占机床总误差的40%~70%。通过热误差补偿功能,在不改变机床结构的前提下,能大大提高机床的加工精度和稳定性。     

立式加工中心热态有限元分析与实验研究

通过分析主轴运转条件下的发热和散热条件,在考虑结合面热阻的情况下,建立了机床热态有限元分析模型;并利用该模型对机床的发热及其导致的变形进行了仿真分析,设计相关实验验证对该模型进行了验证.实验结果表明该仿真模型可靠性较高,可为机床热态性能优化提供了参考.     

电主轴助力高精高速高效加工——我国高性能机床主轴技术现状分析

高性能机床主轴概述 机床主轴是机床的核心部件,其功能是带动刀具（砂轮）或工件旋转,实现高速精密加工。随着现代工业对机床加工精度和加工效率要求的不断提高,机床对主轴性能的要求也越来越高,传统的高速主轴概念已难以充分描述机床主轴的技术内涵。高性能机床主轴是指在满足加工精度和加工效率的前提下,速度、精度、刚度、功率、转矩匹配特性好,可靠性高,性能价格比高的机床主轴。     

高速立式加工中心主轴箱热态分析

高速立式加工中心在加工过程中产生的热效应对机床加工精度的影响日益凸显.XH714B高速立式加工中心在高速加工过程中会出现主轴轴线热偏转现象,机床行业俗称为“闷头”,影响了机械加工表面的完整性,降低了粗糙度.主轴箱作为加工中心的重要热源,为了解决立式加工中心出现“闷头”现象的主要原因,对主轴箱的热态分析就显得尤为重要,采用有限元方法建立了XH714B高速立式加工中心主轴箱热态特性分析模型,分析计算了主轴箱在额定转速下的稳态热特性.与传统观点“滚动轴承为主轴主要热源”不同,提出主轴电动机的热损耗是导致机床主轴轴线在y-z平面内发生偏转的主要原因.     

数控机床热误差补偿高次多阶ADL模型应用分析

综合运用模糊聚类和灰色关联度理论对机床温度监测传感器进行了优选。同时针对现行常用的多元回归模型,采用自回归分布滞后模型（ADL模型）对数控机床热误差进行了建模。在获得较高精度基础上,对ADL模型进行扩展,提出了高次多阶ADL建模技术,并对其建模方法及精度进行了分析比对,实例证明,提出的高次多阶ADL模型在数控机床热误差补偿技术中具有较高的建模精度。     

Actualities and Development of Heavy-Duty CNC Machine Tool Thermal Error Monitoring Technology

Thermal error monitoring technology is the key technological support to solve the thermal error problem of heavy-duty CNC(computer numerical control) machine tools. Currently, there are many review literatures introducing the thermal error research of CNC machine tools,but those mainly focus on the thermal issues in small and medium-sized CNC machine tools and seldom introduce thermal error monitoring technologies. This paper gives an overview of the research on the thermal error of CNC machine tools and emphasizes the study of thermal error of the heavy-duty CNC machine tool in three areas. These areas are the causes of thermal error of heavy-duty CNC machine tool and the issues with the temperature monitoring technology and thermal deformation monitoring technology. A new optical measurement technology called the ‘‘fiber Bragg grating(FBG) distributed sensing technology' for heavy-duty CNC machine tools is introduced in detail. This technology forms an intelligent sensing and monitoring system for heavy-duty CNC machine tools.This paper fills in the blank of this kind of review articlesto guide the development of this industry field and opens up new areas of research on the heavy-duty CNC machine tool thermal error.     

Thermal Error Modeling Method with the Jamming of Temperature-Sensitive Points’ Volatility on CNC Machine Tools

Aiming at the deficiency of the robustness of thermal error compensation models of CNC machine tools, the mechanism of improving the models’ robustness is studied by regarding the Leaderway-V450 machining center as the object. Through the analysis of actual spindle air cutting experimental data on Leaderway-V450 machine, it is found that the temperature-sensitive points used for modeling is volatility, and this volatility directly leads to large changes on the collinear degree among modeling independent variables. Thus, the forecasting accuracy of multivariate regression model is severely affected, and the forecasting robustness becomes poor too. To overcome this effect, a modeling method of establishing thermal error models by using single temperature variable under the jamming of temperature-sensitive points’ volatility is put forward. According to the actual data of thermal error measured in different seasons, it is proved that the single temperature variable model can reduce the loss of forecasting accuracy resulted from the volatility of temperature-sensitive points, especially for the prediction of cross quarter data, the improvement of forecasting accuracy is about 5 μm or more. The purpose that improving the robustness of the thermal error models is realized, which can provide a reference for selecting the modeling independent variable in the application of thermal error compensation of CNC machine tools.     

Improvement of temperature accuracy in oil cooler systems with gas bypass

In keeping with the development of machine tools with higher speed, more axes, and a greater degree of sophistication, thermal deformation is becoming an important factor in the precision of machine tools. It has been found that thermal error accounts for about 70% of the total error in machine tools. As such, oil coolers which absorb heat from heat generating parts with cold oil are being used to reduce the error caused by thermal deformation. The gas bypass type oil coolers used in ultra-precision (temperature accuracy within ±0.1°C) machine tools are simple in structure and precise in terms of their temperature control performance; however, they have a limitation as regards temperature control due to the instability of their performance under light load conditions. In this study, an oil cooler system equipped with dual electronic valves was developed to solve the problems of the single electronic valve system and achieve more precise temperature control. To verify the performance of the developed system, its performance under the operating conditions of rated load, DIN 8602 standard, and ISO/DIS 230-3 operational mode was compared and analyzed. The proposed oil cooler system is applicable to semiconductor equipment, ultra-precision injection molds, and ultra-precision machine tools, and improves the quality of the products.     

A method for thermal characterization and modeling of large gantry-type machine tools

In this paper, a method specially designed for the assessment of repeatability and accuracy of large machine tools is proposed, along with results for a large gantry-type milling machine, recorded in a medium-term period. For this purpose, temperatures were recorded and a metrological frame was used along with inductive sensors in the tool tip, performing repetitive measurements. As initial results, origin, weight and influence of every heat source on this kind of machines were found. Afterwards, high precision measurements of thermal deformations were obtained. Mechanism of errors was found, discerning between main thermal error in the vertical Z-axis and secondary error in longitudinal X-axis towards out of the plane of the gantry bridge. Finally, a finite element model was developed which showed main thermal behavior identified experimentally. This will permit to make simulations of the thermal response of the machine and to choose machining strategies for future parts. Proposed methodology was therefore proved satisfactory for thermal characterization of this kind of big machine tools. This knowledge will make possible to improve thermal design of machines and to develop error compensation procedures. This method can also be applied on workshop conditions for recalibration purposes.     

机床主轴热设计研究综述

机床的热态性能已成为影响高速机床工作性能的最重要的因素之一。主轴是机床的关键功能部件,其热态特性在很大程度上决定了机床的切削速度和加工精度,是影响机床精度提升的最重要因素。因此,在主轴的设计阶段减少机床热误差的影响,对于提高机床的热态特性十分重要。在过去的近一个世纪时间中,国内外众多学者针对主轴热设计方法开展了研究探索,基于热设计的过程可以分成三部分内容:热态特性分析方法,热设计与优化方法和热态特性试验方法。先通过主轴热态特性(如温度场分布、热变形、热平衡时间等)建模与分析获取必要的参数,然后以此为基础开展主轴结构设计优化、材料设计优化和冷却系统设计等热设计措施,获得较佳的主轴热态特性,最后通过热态特性试验来校验分析和设计优化的结果,整个过程循环直至达到满意结果为止。本文以此为脉络展开,分别探讨了三部分内容的国内外典型研究现状、主要研究内容和所存在的优缺点,并对未来的研究趋势进行了展望。     

热变形对精密机床精度的影响研究及控制措施

文中分析了精密机床热变形的热源和热变形对机床精度的影响,从四个方面提出了减少机床热变形的措施。     

Multi-procedure design optimization and analysis of mesoscale machine tools

Conventional machine tools are being miniaturized because of the technical and economic advantages that this approach produces. Apart from these issues, the response time for marketing mesoscale machine tools is growing shorter. Thus, further development in this area will require a systematic design scheme to reduce subjectivity at the early design stage. This paper covers the structural optimization of a miniaturized milling machine using an integrated design strategy based on individual modeling and simulations of key parameters, such as volumetric error and machine working space, as well as static, thermal, and dynamic stiffness. This integrated approach was developed using analytical methods and then validated experimentally. Individual computations based on the mathematical model were carried out to produce a penalty function for the miniaturized milling machine that was then used to determine the optimal structure. This paper also discusses the sensitivity of weighting factors to determine which weighting factor is the most effective in an optimal solution. This study contributes to the development of more reliable mesoscale machine tools.     

重型数控机床热误差建模及预测方法的研究

重型数控机床的热误差已经成为影响其加工精度的一个关键问题。针对一台典型的重型落地铣镗床,以机床热误差测量试验为依据,分析该类机床温度场的特点;据此提出一种旨在完成高效温度测点优化的改进系统聚类方法,该方法使用一种兼顾欧氏距离和相关系数的系统聚类准则,可以有效地降低优化后温度测点之间的共线性。基于优化后的温度测点,利用多元线性回归分析,构建了机床的热误差预测模型。现场试验数据表明,该方法可以将热误差预测的均方根误差降低到10μm以下,相较于其他方法有着更高的热误差预测精度,有望在其他重型数控机床的热误差建模和预测研究中得到更大的推广应用。