控制薄板件加工变形的工艺方法

探讨了减小薄板件切削加工变形的工艺方法,通过分析变形产生的原因,结合生产经验,提出了合理可行的工艺措施,能够控制零件的变形,保证其平面度和尺寸精度.     

真空吸盘在薄壁板类零件加工中的应用

<正>1引言薄壁、薄板型零件普遍刚性差、强度低、精度高,在加工过程中容易产生变形,零件的加工质量难以保证。尤其是薄板类零件,在铣平面时,传统的加工方法是用虎钳夹紧零件的侧面。夹紧力大,零件易变形;夹紧力小,零件容易飞出威胁操作者的人身安全。如果用压板压住零件铣平面,需要倒一次压板,零件平面度难以保证,对小型薄板零件更是无法实现。安全有效的装夹零件便成了零件加工中的关键问题。真空吸盘作为铣床夹具所发挥的独     

谈谈薄板零件的磨削方法

随着我国工业的不断发展,要求磨削的薄板零件也日益增多,如果它的平直度要求较高的话,用普通的磨削方法就很难保证。为了达到要求并提高生产效率,我们对薄板件的磨削方法进行了一些摸索,初步得出用普通砂轮在一般卧轴矩台平面磨床上磨削的简单操作方法,现介绍如下。     

薄型板件平面的磨削加工

介绍了薄型板件在平面砂带磨床上磨削的方法，这种磨削方法具有工件受热受力变形小、磨削表面质量好、生产成本低、效率高等特点，对提高产品质量、降低成本有实用价值。     

超薄板的精密磨削

超薄板精密磨削平面中,由于零件的刚性差及毛坯基准面的不平,使零件的平面度很难控制。一般均通过在磁台上多次翻身吸磨来解决零件的等厚,但如何使工件在平面磨的普通磁台上吸牢,加工后退磁不产生翘曲,就需要采用特殊的工艺手段。我厂在加工压缩机阀片(材料35钢)时,平面度要求0.005,光浩度8,     

薄片零件两端平面磨削的几种加工方法

常见的垫圈、摩擦片、样板、薄板等这样的薄片零件 ,它的刚性差、散热困难 ,热处理后弯曲 ,装夹时引起夹紧变形 ,磨削时易翘曲与变形 ,难于保证零件两端平面的平行度精度。然而 ,通常采用磁力吸盘在平面磨床上磨削加工 ,磨削完成后 ,去掉磁性吸引力 ,薄片工件恢复原状。如图 1所示。如采用如下几种磨削加工方法 ,可保证薄片工件在自由状态下进行定位与夹紧 ,取得良好效果 ,满足薄片零件两端平面的厚度尺寸和平行度精度要求。1　垫弹性垫片方式的磨削　　在平面磨床上磨削上述薄片工件两端平面时 ,采用弹性夹紧机构 ,使薄片工件在自由状态下…     

平面磨削颤振试验研究

首先，通过平面磨削过程动力学模型，对平面磨削颤振的发生和发展进行分析。然后，设计平面磨削颤振的试验方案，获得磨削颤振和磨削表面波纹度的试验结果，进而研究不同的磨削条件对磨削颤振和磨削表面波纹度的影响，得到与理论分析一致的结果。最后，给出磨削颤振和磨削表面波纹度之间的相互关系，研究表明，在平面磨削过程中，磨削深度是影响磨削颤振和磨削表面波纹度的主导因素；在较大的磨削深度条件下，磨削颤振的幅值和磨削表面的波纹度幅值随着工件速度的增加有显著增大的趋势。     

薄壁套圈磨加工控制与保证工艺探讨

在轴承套圈的磨削加工中 ,如何保证薄壁套圈不发生变形是工艺研究的一个重要课题。本次我们以 6 0 / 5 2 .4产品内套磨削加工做为试验对象 ,验证其磨削工艺应如何安排 ,才能提高加工精度 ,满足技术要求。一、试验方法本次试验分三组进行 ,通过改变内径和内沟的磨削工艺路线 ,然后对加工后零件的内沟圆度Ｖｄｉｐ和内径圆度Ｖｄｐ分别进行检测、对比和分析 ,最终确定最佳的工艺路线。具体试验步骤如下 :(1)第一组试验工艺路线磨内沟———取 2 0件合格品———磨内径 (磨削速度 2 5Ｓ/件 )(2 )第二组试验工艺路线磨内沟———取 2 0件合格品…     

多斜孔薄板关键加工工艺研究

为达到跨声速风洞试验段壁板的技术指标,对多斜孔薄板的关键加工工艺进行了研究。在分析多斜孔薄板加工主要控制项和加工难点的基础上,重点研究了斜孔加工工艺、薄板平面度加工工艺和薄板防腐蚀工艺。在跨声速风洞壁板加工中应用所研究的多斜孔薄板加工工艺,确认可以满足技术指标。     

磨削工件受热变形及其误差的计算

本文把平面磨削的工件划分为薄板和厚板,根据热弹性理论分别推导了热变形误差计算公式,得到了两者的热变形误差计算公式。分析表明薄板和厚板在磨削过程中将产生相同的形状误差．但厚板还将产生尺寸误差。实例计算表明,对较精密零件的磨削,必须考虑热变形。     

硬质合金工件精磨表面粗糙度及平面度的试验研究

通过对硬质合金工件的磨削试验,分析了不同砂轮对工件表面粗糙度的影响,优选出可获得最佳表面质量的砂轮。通过将Matlab应用于磨削表面平面度检测的数学建模,提高了工件平面度的检测精度。     

非导电工程陶瓷电火花磨削技术

开发出双电极同步伺服跟踪电火花磨削新技术,该技术突破了传统的机械磨削和电解电火花机械复合磨削方法,利用导电磨轮与紧贴非导电工程陶瓷工件表面作自动伺服进给运动的薄片辅助电极间的放电实现电火花磨削。对非导电的Al2O3工程陶瓷进行加工试验,给出加工参数如脉冲宽度、脉冲间隔、峰值电压、峰值电流、磨轮转速以及铜片电极厚度等对材料去除率和表面粗糙度的影响规律关系。试验结果表明,该种新型加工技术具有效率高、表面质量好、成本低和对环境无污染等优点。     

Basic investigation of noncontact transportation system for large TFT-LCD glass sheet used in CCD inspection section

Recently, thin film transistor liquid crystal displays (TFT-LCDs) have been successfully applied to desktop personal computer (PC) monitors and televisions. Higher resolution and larger mother glass sheets have been required for television displays in particular to reduce costs and improve production efficiencies. To handle the increasing resolution and mother glass size, high-speed inspection processes for detecting defects in TFT arrays using charge coupled device (CCD) cameras are becoming very important. Therefore, a noncontact transportation technique for the high-speed inspection section is necessary, to avoid damage to the glass sheet during the inspection process. In addition, high-speed CCD cameras with high resolution, large magnification and shallow focus depth are usually used in the inspection process. Accordingly, it was reported that fluctuations of less than 20 μm in the floating gap of the LCD glass sheet were required. We have used a 240 mm square LCD glass sheet as the first step of this study and an air-pad system using porous metal was investigated to support the glass sheet. The influence on the flatness of design parameters such as the nonuniformity of the permeability of the porous air pads and the appropriate combination of supply and exhaust pressures were investigated numerically for a glass sheet that was quiescently supported by the proposed air-pad system. Moreover, the numerical results are compared with experimental results to verify the validity of the numerical predictions. We found that the flatness of the glass sheet of less than 15 μm could be achieved experimentally with a floating gap of around 30 μm by using the proposed air-pad system.     

An airy function to rapidly predict stresses in wound metal strip having asymmetric thickness profile

With increased demand for thin gage flat metals, control of strip flatness or shape in cold rolling processes has become very important. To improve the flatness quality of cold rolled metal strip and sheet, this work provides a rapid method to predict the transient strains (or stresses) occurring during the rewinding of flat-rolled steels having problematic asymmetric strip thickness profile (or wedge). Flatness control systems, used to monitor and correct the distribution of stress across the width of rolled sheet, are unable to distinguish between stresses induced during rolling, and those caused when rewinding strip containing asymmetric thickness profile. The winding stresses, unless large enough to plastically deform the strip, vanish upon unwinding during subsequent operations such as stamping. Therefore, to help avoid strip flatness defects in thin strip containing wedge, a method is developed to separate the winding stress contribution from the overall stresses that are measured indirectly by flatness control systems. A fourth-order polynomial Airy function is developed to rapidly predict the in-plane stresses based on mandrel wrap number and spatial location on the strip. The Airy function is obtained by applying two-dimensional finite element analysis to study the transient in-plane stresses during rewinding at various numbers of mandrel wraps for a strip containing wedge profile. Three-dimensional finite element analysis is first employed, however, to show justification to a simplified two-dimensional problem described by the plane-stress Airy function. The two-dimensional finite element analysis provides insight as to how the in-plane stresses evolve, and allows determination of coefficients for the Airy function based upon model geometry and displacement boundary conditions. This approach differs from other methods that employ Fourier series to solve the biharmonic equations for an assumed two-dimensional problem. Finally, filtering of the winding stresses from flatness control system input signals is also discussed based on data taken from a rolling mill different to that used for model development.     

Wear analysis of electrolytically dressed wheels for finishing substrate materials

Finishing of silicon wafers is a billion dollar global business. The present process chain consists of several processes, which lead to long production times and increase the cost of the finished materials. In the recent years, several processes have been experimented as an alternate process for finishing substrate wafers with stringent specifications. However, there are no successful alternate processes, which have been adopted by the wafer processing industries. The electrolytic in-process dressing (ELID) grinding is one of the processes that has already been experimented on silicon wafers for producing mirror surface finish. However, the flatness achieved from the ELID grinding is not reported. The main influence on the flatness of the wafers during ELID grinding may be due to the wear of the grinding wheels. The wear mechanism of electrolytically dressed wheels has not been fully understood and reported. The main objective of this study is to report the wear behaviors of the wheels during thinning and fine finishing of substrate wafers. The experimental results provide the conditions for utilization of the non-linear behavior of the electrolytically dressed grinding wheels for thinning and fine finishing processes.     

Planar nanogrinding of a fine grained WC-Co composite for an optical surface finish

Nanogrinding of a fine-grained WC-Co composite was developed to achieve an optical quality surface without further polishing. Direct planar grinding was conducted with a CNC grinding machine using a metal-bond diamond wheel of grit size of 15 μm, under the nanogrinding conditions selected. The ground planar surfaces were examined using laser and optical interferometry, atomic force microscopy, and scanning electron microscopy to measure flatness, surface roughness, and surface integrity as a function of grinding conditions. Damage-free, planar mirror surfaces with a flatness (peak-to-valley, PV) at the submicron scale and surface roughness <5 nm R_a were obtained.     

金刚石微粉烧结棒与杯形砂轮修整碟形金刚石砂轮的对比试验研究

以反映砂轮平面度的端面跳动变化率和径向跳动变化率作为修整效率的评价依据,以插齿刀的齿形精度和齿面精度作为修整效果的评价依据,从试验和实际加工出的插齿刀齿形两方面对金刚石微粉烧结棒和杯形砂轮修整碟形金刚石砂轮进行了对比试验研究。结果表明,杯形砂轮的修整效率高于金刚石微粉烧结棒的修整效率;杯形砂轮修整的碟形金刚石砂轮具有较高的磨削能力。     

一种新型平面研磨机的研制与实验

根据研磨最佳运动学条件,结合现有研磨机,研制了新型行星轮式恒速率变向平面研磨机.研磨机具有被研磨表面各点研磨轨迹相同、速度相同,研磨运动方向恒速率变向的运动特性.利用研磨实验机进行了大量研磨实验,取得了很好的研磨效果,研磨表面Ra可至纳米级.     

Development of a hybrid particle swarm optimization algorithm for multi-pass roller grinding process optimization

In the field of metal rolling, the quality of steel roller’s surface is significant for the final rolling products, e.g., metal sheets or foils. The surface roughness of steel rollers must fall into a stringent range to guarantee the proper rolling force between the sheet and the roller. To achieve the surface roughness requirement, multiple grinding passes have to be implemented. The current process parameter design for multi-pass roller grinding mainly relies on the knowledge of the experienced engineers. This always requires time tedious “trial and error” and is insufficient to work out cases: (1) multi-pass with complex interaction for one pass with its neighboring passes; (2) large number of process parameters setup; (3) multiple process objectives and constrains. In this paper, a process planning method for multi-objective optimization is proposed with a hybrid particle swarm optimization while incorporating the response surface model of the surface roughness evolution. The hybrid particle swarm optimization regards the entire grinding process parameters (from rough grinding, semi-finish grinding, finish grinding to spark-out grinding) as a whole, and realizes the parameter optimization by considering multiple objectives and constrains. The establishment of the response surface model of surface roughness evolution is capable to incorporate the inter-correlation of neighboring passes into the multi-pass parameter optimization. Finally, the experimental verification was implemented to verify the effectiveness of the proposed method. The error between predicted roughness and experimental roughness is less than 16.53%, and the grinding efficiency is improved by 17.00% compared with the empirical optimal process parameters.