提高导轨磨加工精度的有效方法

目前机床导轨一般都要求进行淬火处理,因此导轨的精加工就无法用刮削的方法,而只能靠磨削和研磨。我国机床厂的导轨磨精度一般不很高,对于精度要求(全长直线度)较高的大中型导轨的加工就是一个难题,我厂从实践中摸索出一种新的导轨磨削方法,效果显著,全长直线度可提高60%。 我厂加工的导轨长 2200 mm,淬火硬度RC 68,直线度 0.012 mm/全长, 0.005 mm/m,导轨间平行度0.01 mm。以往加工直线度只能达到 0.025～0.032 mm/全长, 0.006mm/m,平行度 0.008 mm(床身两侧向导轨),需再经手工研磨才能达到设计要求,效率极低。现采用这种新方法,工效一般…     

运用新思想设计高精度数控导轨磨床

为消除导轨磨床的热变形，采用新思想设计出大型高精度数控导轨磨床——自准直导轨磨床。自准直导轨磨床的基本原理是通过降低床身和基础的纵向弯曲刚度，使床身和基础的重力变形自动补偿由于环境温度变化和磨擦热引起的热变形。有限元分析和10余年的实际应用表明：采用该思想设计的机床精度高、费用低，而且不需要恒温车间；用该思想设计的自准直导轨磨床，被加工件的线性误差小于0．003mm／m，而且加工精度长时间保持稳定。     

工厂小经验

用变形加工法实现床身中凸量 严各康 目前,外商对我国出口车床导轨要求采用周边磨削。为此我厂研制了用成型砂轮进行周边磨削导轨磨。它既能保证车床导轨一次成形,又能达到ISO精度标准要求(0.005～0.022 mm)。但是设计的导轨磨是用我厂生产的卧轴平面磨床为基础的,按照国家标准要求,其床身中间应凹 1000:0.01 mm。这正好与车床导轨中间凸的要求矛盾。再加上导轨磨床身导轨刚性变形和热变形的影响,使这个矛盾更为突出。为此我们对导轨磨床进行了分析。 1.导轨磨床身导轨受自重及立柱等部件压力的影响产生图中所示的变形( Y=5 gL4+/384 EJ)…     

陶瓷结合剂CBN砂轮磨削机床导轨工艺试验

一、概述我厂端面磨削导轨磨床,原来使用普通磨料杯形砂轮精磨5m以上的大型磨床铸铁床身导轨,由于砂轮切削性能差,虽由经验丰富的师傅精心操作,导轨在水平面内任意250mm长度上的直线度误差还是只能达到“GB4685-84外圆磨床精度标准”合格的边缘,在床身重新安装或环境温度变化时,容易超差而返修,导轨表面粗糙度也不能稳定达到要求,因此砂轮成了贯彻磨床导轨精度国家标准的关键。为了解决上述问题,我厂提请郑州磨料磨具磨削研究所研制磨削大型铸铁床身导轨用陶     

床身导轨中凸加工方法

重庆读者刘进来信说，要求介绍床身导轨中凸的加工方法。GB4020—83《卧式车床精度》标准规定了车床床身导轨在纵向垂直平面内的直线度，并要求向上凸，即中凸要求。为达到这一要求，可采用如下3种加工方法。一、数控导轨磨床法应用数控导轨磨床时，磨床导轨处于水平直线位置，     

薄壁细长件内孔直线度加工工艺分析

通过对薄壁细长件内孔原加工工艺的分析,找出产生弯曲变形的原因,提出在渗碳前采用枪钻、渗碳淬火后采用电火花磨床取代内圆磨床加工内孔的新工艺方案,保证了内孔直线度误差在0.001mm内的要求,通过试加工3批工件,大大提高了产品的合格率,证明该方法切实可行。     

自准直仪测M1432B磨床导轨直线度

M1432B外圆磨床的床身导轨长2700mm,在机床大修过程中,床身导轨要进行修磨和刮研,在加工过程中,必须对导轨进行直线度误差测量和分析计算。现介绍利用DZ—Ⅱ1″单向测微自准直仪对M1432B外圆磨床床身导轨垂直平面内直线度进行测量计算的方法。     

焊接结构机床件应力与精度控制技术研究

调研测试了国内外焊接机床结构件的残余应力,试制了某立式加工中心用焊接床身、立柱和滑鞍并跟踪测试其焊接后与组合时效处理后的应力与变形.结果 表明:焊接机床结构件普遍存在较大的残余应力、大多在100 MPa以上;所试制焊接床身、立柱、床身和滑鞍的焊接后初始残余应力最大分别达到154.9 MPa、274.4 MPa和300.6 MPa,接近或超过材料屈服强度,容易引起较大的变形.此外,立柱导轨、床身和滑鞍最大变形量也分别达到1.22 mm、2.24 mm、2.88 mm;经过"焊接后-热时效-半精加工-振动时效-精加工"的组合时效处理后,床身、滑鞍和立柱的应力与变形均显著降低,最大残余应力分别降低至18.1 MPa、39.8 MPa和41.9 MPa,均低于10％Rm,最大直线度分别为19.17 μm、23.57μm和36.69 μm;时隔约6个月之后,导轨面的变形量控制在1μm/1000 mm～3μm/1000 mm,具有良好的精度保持性,焊接结构件可以用于精度要求高的数控金切机床和齿轮箱等的加工场所.     

光刨代磨加工特长导轨

床身是磨床的基础,也是关键的零件之一,床身导轨不仅是机床各项几何精度的测定基准,而且它的精度直接影响磨床的加工精度。一般的床身加工工艺路线最后一道都是要上导轨磨床磨削平V导轨面,但对于导轨大于8m的工件,由于设备的局限对于床身的加工只能依靠括工手工刮削的方法来加工解决。我们通过试验现已经成功的在3×16m的龙门刨床上用光刨代磨的方法达到了导轨磨床磨削的要求。以加工床身长10.72m、的专用外     

机床床身导轨热变形及其模型的建立

机床床身导轨热变形后会破坏机床安装调试的精度,引起部件移动的直线度和角度变化而降低机床的加工精度;通过几种运用不同的方法建立导轨热变形的数学模型,能够为数控机床的编程带来方便,保证和提高工件的加工质量。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.