多次切割中钼丝抖动影响因素分析

通过对快走丝线切割机实施多次切割工艺的分析可知,影响工件切割质量的主要因素是钼丝的运行抖动,对影响钼丝运行抖动的因素进行分析得到提高钼丝运行质量的措施。实践表明,通过对快走丝线切割机进行适当改造和采用合适的切割工艺,在快走丝线切割机上实施多次切割工艺得到的工件质量满足使用要求。     

光纤激光切割机特殊工艺设定对切割质量的影响

通过对激光切割机切割质量的大量试验研究,从激光切割加工特殊工艺要求来分析穿孔技术、引线设置和拐角设置等特殊工艺设定对切割质量和加工效率的影响。     

一种激光切割机横梁的优化设计方法

将某型号激光切割机的横梁进行简化,建立横梁结构参数化几何模型,并根据参数化模型建立有限元模型,根据模态分析结果从多个结构参数中选取设计变量,使用有限元分析软件对设计变量进行优化,得到结构参数最优解,此方法可代替传统方法对模型进行反复修改和计算,可提高设计效率。     

链轮的火焰精密切割

链轮采用机械加工,不仅浪费时间、材料,而且成本高。为此,东德中央焊接研究所研制一种新式的、F02/ZIS391型光电火焰切割机,可用于链轮、齿轮、齿条、传动齿轮以及任意结构形状部件的切割。切口表面质量符合要求。试验得出,切割质量与下列主要参数有关:导轨精度;行走机构和控制方法;行程控制;样板的尺寸精度;切割机、样板及毛坯的安装精度;切口位置及其切割方向的选择;工件的几何形状和尺寸;切割长度;材质及材料厚度;切割气体种类、纯度、压力;切割速度;割咀距工件表面距离等等。 F02/ZIS391光电火焰切割机具有工作效率高、节省材料、设备费用低等优点。该切割机装有固定部件、割炬定心装置,以达到精密切割的目的。F02/ZIS391新式光电火焰切割机主要     

DS-054数控激光切割机的可靠性及经济效果

DS-054数控激光切割机床是具有现代技术水平的切割机床,自在我厂使用以来,在客车的研制和生产中发挥了积极的作用,取得了较明显的技术经济效益。可靠性是激光切割机在使用中的重要指标,也是评定该机床设计和制造质量的主要指     

快走丝线切割加工铝及合金的工艺分析

由于铝的熔化热和汽化热低,当使用快走丝线切割机加工铝合金时,易产生熔化反应,加工表面粗糙,产生的电蚀物粘附在钼丝上,使导电块早期磨损,并在钼丝与工件间产生非正常火花放电,在导电块表面上切割出细沟槽,引起夹丝、断丝现象。通过改进切割工艺及试验,得到了提高加工稳定性及切割面质量的措施和方法。     

光纤激光切割技术

激光切割质量好,尺寸精度高,热影响小,在切割行业应用越来越广泛。通过对光纤激光切割机的介绍及其与二氧化碳激光切割机的对比,分析了光纤激光切割机在未来切割行业中的技术优势、结构优势、成本优势。光纤激光具有切割薄板速度快、能量集中、电光转化率高、柔性加工等众多优点。同时指出了目前光纤激光切割技术存在的安全问题及厚板切割局限性问题,提出了当前的一些解决方案及研究热点,并展望了光纤激光切割技术的发展前景。     

数控等离子切割机切割件的变形控制

针对数控等离子切割机切割件产生变形的原因,对切割件的变形进行了分析.根据数控等离子切割机的特点,在加工过程中正确选择切割的起点、切割方向、切割顺序、切割速度等工艺,可以有效提高切割件的加工质量,同时对单边工件、细长件、异型件以及特殊件的变形控制进行了详细地阐述.     

高功率激光切割机厚板侧边悬空切割功能设计

随着高功率激光发生器的出现,以及新技术在激光切割行业的应用,加之国产激光发生器的快速崛起,购买激光切割机的门槛也逐年降低,配套高功率激光发生器的激光切割机能够满足厚板下料需求。摆动式平面坡口切割装置可以实现在同一台设备上完成下料和坡口加工,加工好的工件可以直接进入焊接工序,节省大量的人力物力,提高用户生产效率。但是带角度斜切变相增加了切割厚度,导致厚板坡口加工板材厚度受限。针对部分场景需要对厚板侧边进行坡口加工,设计一种悬空切割工艺,满足坡口加工需求。     

三维激光切割转角“过烧”试验研究

三维激光在切割带有转角的工件时,由于能量的过多射入,在转角处会发生过烧现象。采用2 kW的Rofin光纤激光器、RX160L型史陶比尔机器人以及配套的辅助设备集成的三维激光切割机对45钢转角切割进行了研究,提出了在转角处减少工艺参数点、优化激光切割过程中机器人的运动姿态以及优化工艺参数的工艺手段减少过烧现象。研究结果表明在激光功率600 W,切割速度25 mm/s,辅助气体O2压力0.21 MPa时,经过工艺优化后进行转角切割可以有效避免过烧现象的发生,获得的切割断面平整,无挂渣。随着激光功率和辅助气体压力的增大,切缝宽度增大;随着切割速度增大,切缝宽度减小。随着激光功率增加,切割面粗糙度减小;随着切割速度和辅助气体压力增大,切割面粗糙度先减小后增大。     

基于改进遗传算法的数控机床加工铣削参数优化方法

对于数控机床加工铣削参数优化多采用常规的可信度近似模型,但该方法易受到材料失效应变系数的影响,导致优化后的加工效率较低,提出基于改进遗传算法的数控机床加工铣削参数优化方法。根据工件的本构模型,对切削刃进行采样抽取,确定最小铣削力波动位置;引入材料失效准则计算材料失效应变系数,基于此,以加工时间最短、加工成本最低和加工能耗消耗最小为目标建立铣削参数优化模型,并采用改进遗传算法求解模型,通过迭代适应度值,输出最佳铣削参数;最后,采用对比实验的形式对所提方法的优化性能进行测试。测试结果表明：应用所提方法对数控机床加工铣削参数进行优化后,能够有效缩短切削时间,提高加工效率。     

激光切割机精度保持性评估方法研究

针对激光切割机在加工FPCB板时,出现的误差逐渐增加导致拼接错位、工件精度下降、设备稳定性下降等问题,对激光切割机精度保持性进行历史数据分析、操作流程标准化及校准标准化研究.研究结果为进行设备优化提供参考.     

Estimation of heat conduction losses in laser cutting

Numerical models of laser cutting are essential for an improved understanding of the process. In order for the models to closely represent real physics the heat lost by conduction during cutting has to be incorporated into them. This paper outlines the details of a mathematical model that is used to estimate heat conduction losses in laser cutting by employing integral methods to solve the three-dimensional, heat-conduction equation. Simple, yet accurate, correlations are presented for the conduction heat loss rate, as well as for characteristic thicknesses of the heat affected zone (HAZ). These variables are functions only of Peclet number (Pe), which may be thought of as a dimensionless cutting speed. The correlations are then used to predict (i) the cutting speed in laser cutting, and (ii) the temperature field in the HAZ. The predictions show an excellent match with experimental results. Cutting speed is predicted using an energy balance at the cutting front. An implicit, nonlinear equation for Pe as a function of Stefan number (Ste) and dimensionless heat of combustion results. Ste gives the ratio of sensible heat to latent heat in the workpiece. Detailed analysis of beam absorptivity, coupled with the dimensionless cutting speed result suggests that the dimensional cutting speed, u_o, may be correlated as a unique function of the ratio of incoming laser power to workpiece thickness, Q_las/d. This is corroborated by measured cutting rates over a wide range of sample thicknesses and two beam power settings.     

面向绿色高表面质量制造的硬态车削工艺多目标参数优化

目的 为了进行硬态车削绿色制造与工艺性能协同优化研究,提出一种同时考虑碳排放量和表面粗糙度的多目标优化方法。方法 首先,通过分析硬态车削过程中切削参数、工件材料、刀具材料等因素对切削功率的影响建立碳排放目标函数,针对工件的表面粗糙度受到切削条件、工件材料、刀具材料等诸多因素的影响,利用正交试验和广义回归神经网络建立轴承硬态车削表面粗糙度目标函数。然后,考虑加工过程中机床特性和硬车实际工况等约束条件,建立以切削参数为优化变量,以碳排放量和表面粗糙度为优化目标的多目标优化模型,引入权重系数将其转化为单目标优化模型。最后,利用遗传算法对优化模型进行优化求解,深入分析切削参数对优化目标的影响。结果 在工厂实际轴承产品硬车试验中验证了优化模型的有效性,结果表明,切削速度为225 m/min、进给量为0.08 mm/r、背吃刀量为0.10 mm时,碳排放量和表面粗糙度的综合优化指标最低。相比优化前,虽然碳排放量上升了13.05%,但表面质量提升了34.44%。结论 研究结果对面向绿色制造的轴承硬车工艺参数优化提供理论方法有重要意义。     

基于灰色关联理论的空冷辅助车削钛合金端面的工艺参数优化

以TC4钛合金棒料为试验对象,以数控车床作为试验平台,对空冷辅助车削钛合金端面的切削速度、背吃刀量、进给量等主要工艺参数进行正交试验研究。采用灰色关联分析法,对工件表面粗糙度、刀具磨损量以及工件表面硬度等工艺目标进行综合评价,使多工艺目标转化为单一考察指标,得到了最佳的工艺优化组合方案,并提高了试验效率。研究结果证明:用灰色关联分析法优化后的工艺参数能够有效降低工件表面粗糙度,减少刀具磨损,使工件硬度更符合切削要求。     

Theoretical-experimental modeling of milling machines for the prediction of chatter vibration

Productivity of high speed milling operations can be seriously limited by chatter occurrence. Chatter vibrations can imprint a poor surface finish on the workpiece and can damage the cutting tool and the machine. Chatter occurrence is strongly affected by the dynamic response of the whole system, i.e. the milling machine, the tool holder, the tool, the workpiece and the workpiece clamping fixture. Tool changes must be taken into account in order to properly predict chatter occurrence. In this study, a model of the milling machine-tool is proposed: the machine frame and the spindle were modeled by an experimentally evaluated modal model, while the tool was modeled by a discrete modal approach, based on the continuous beam shape analytical eigenfunctions. A chatter identification technique, based on this analytical-experimental model, was implemented. Tool changes can be easily taken into account without requiring any experimental tests. A 4 axis numerically controlled (NC) milling machine was instrumented in order to identify and validate the proposed model. The milling machine model was excited by regenerative, time-varying cutting forces, leading to a set of Delay Differential Equations (DDEs) with periodic coefficients. The stability lobe charts were evaluated using the semi-discretization method that was extended to n>2 degrees of freedom (dof) models. The stability predictions obtained by the analytical model are compared to the results of several cutting tests accomplished on the instrumented NC milling machine.     

Direct laser assisted machining with a sapphire tool for bulk metallic glass

Bulk metallic glasses (BMGs) are amorphous metallic alloys with high strength and hardness. This paper discusses the machining process of Zr-BMG using a transparent sapphire tool with direct laser assistance. The laser beam passes through the tool and directly heats the workpiece material to improve its machinability. Micro textures were generated on the tool rake face to facilitate chip formation. Reduced cutting forces and improved surface finish were observed with direct laser assistance. The effects of machining speed and laser power on the material deformation mechanism were investigated. A finite element model was developed to investigate the cutting forces.     

基于PLC的切割机运动轨迹控制系统的设计

在实际应用中,很多切割机不能满足加工精度要求,精度高的切割机又十分紧缺,因此发展高精度的切割机很有必要。另一方面,很多切割机自动化水平不高,尤其是手动操作的切割机在操作时很不方便。故采用可编程终端、PLC、运动控制单元、伺服驱动系统等成熟的控制部件构建切割机运动轨迹控制系统。详细设计此系统的各个模块单元,介绍各个部件之间的数据通信和软件设计步骤,并以一个简单的例子说明了其操作过程。采用此运动系统能使加工工件的质量、机床的自动化程度、可操作性都得到大幅度的提高。     

基于高质量和低振动的铣削参数优化方法研究

针对数控铣床在切削过程中产生的振动对工件表面质量的影响,提出以低振动和高表面质量为优化目标,对切削参数进行优化。以VDF-850A铣床为研究对象对45号钢进行铣削正交试验,通过建立振动采集系统,采集振动信号提取振动特征值并测量工件表面粗糙度值,应用最小二乘法拟合数据建立了振动和粗糙度数学模型。利用层次分析法确定两目标函数权重,使用平方和加权法对两目标函数加权拟合成综合目标评价函数,运用粒子群算法优化切削参数。试验结果表明:应用粒子群算法优化后的切削参数进行加工可有效的降低振动和提高表面质量。     

Characterization of a hybrid laser-assisted mechanical micromachining (LAMM) process for a difficult-to-machine material

Mechanical micro-cutting is emerging as a viable alternative to lithography based micromachining techniques for applications in optics, semiconductors and micro-mold/dies. However, certain factors limit the types of workpiece materials that can be processed using mechanical micromachining methods. For difficult-to-machine materials such as mold and die steels or ceramics, limited cutting tool/machine stiffness and strength are major impediments to the efficient use of mechanical micromachining methods. In addition, at micron length scales of cutting, the effect of tool/machine deflection on the dimensional accuracy of the machined feature can be significant. This paper presents experimental characterization of a novel hybrid laser assisted mechanical micromachining (LAMM) process designed for 3D micro-grooving that involves highly localized thermal softening of the hard material by focusing a solid-state continuous wave laser beam in front of a miniature cutting tool. Micro-scale grooving experiments are conducted on H-13 mold steel (42 HRc) in order to understand the influence of laser variables and cutting parameters on the cutting forces, groove depth and surface finish. The results show that the laser variables significantly influence the process response. Specifically, the mean thrust force is found to decrease by 17% and the 3D average surface roughness increases by 36% when the laser power is increased from 0 to 10 W. The groove depths are found to be influenced by the machine (stage) deflection and tool thermal expansion, which affect the actual depth of cut, in the presence of laser heating. In particular, it is found that the accuracy of groove depth improves with laser heating. Explanations for the observed trends are given.