浅谈组合机床夹具精度(上)

根据作者多年的实践经验,对无导向固定夹具、有导向夹具、活导向夹具、移动夹具、回转夹具等各类组合机床夹具的应检验精度项目及其影响因素和具体如何取值等问题进行了全面深入的分析论述。图4幅,表1个。     

关于等距度与同轴度两种检测方法的再商榷

本文论述了钻镗组合机床精度标准中关于主轴回转轴线和夹具导向孔(或样件孔)轴线相对位置精度的检验方法问题,主张将同轴度检验方法纳入标准,摈弃等距度检验方法。     

凹面齿圆柱蜗杆付蜗轮滚刀齿形的设计计算

鉴于目前加工凹面齿圈柱蜗杆的刀具只限于蜗轮飞刀的设计计算方法。本文提出蜗轮滚刀的设计计算方法,从滚刀参数的选择,滚刀齿形的检验,加工Ⅰ和Ⅱ型凹面齿圆柱蜗杆付蜗轮滚刀齿形的设计计算方法等方面论述,并建立了数学模型;最后举例验算了计算方法的正确性。可供设计蜗轮滚刀者参考。     

浅谈组合机床夹具精度(下)

因为组合机床大部分是孔加工机床,所以有导向夹具占了较大的比例。有导向夹具的定位方法与无导向夹具完全相同,不再赘述。因为它带有导套,导套代替了样件,检查机床精度的检验棒不是插在样件孔中,而是插在导套孔中(若导套与模板体配合松动时取下     

51CrV4钢链板断裂分析

经等温淬火的发动机齿形链,材料为51CrV4钢,在装配过程中发现有断裂现象。对断裂的齿形链进行了化学成分分析、显微组织检验和硬度测试,以揭示其断裂产生的原因。结果表明,齿形链属于脆性断裂,主要是由于链板在网带炉内等温淬火时发生了增碳,使脆性增大,导致在链板台阶处由于应力集中而断裂。     

在普通电火花机床上加工斜齿型腔

我们曾加工了一种斜齿轮模具,该模具的加工关键在于斜齿型腔的加工。斜齿型腔由于齿部有螺旋升角,电火花加工斜齿形腔,电极提升就必须按照斜齿的螺旋转提升。在此情况下我们在D6140型电火花机床上,设计制造了一套螺旋提升夹具。     

整体式汽车转向节夹具结构设计

基于汽车转向节结构复杂、加工精度要求高、定位困难、生产批量大等特点,对整体式汽车转向节加工工艺问题进行了研究针对加工过程中某一工序设计了一套翻转式铣面钻孔夹具,并运用三维图形软件Pro/E对所设计夹具结构进行建模和虚拟装配检验夹具空间布置和零件尺寸干涉性问题并修改同时对夹具的夹紧力和定位误差进行分析计算以确保该夹具可以满足汽车转向节大批量、高效、高精度的加工要求,提高了该转向节的生产效率和加工精度.     

直齿圆柱齿轮冷精锻模具齿形设计

对两步成形直齿圆柱齿轮冷精锻工艺模具齿形设计方法进行了研究，分别采用修正模数法和变位法对终锻模具和预锻模具的齿形进行了设计。提出的模具齿形设计方法可靠、易行，不仅可用于冷精锻齿轮模具的齿形设计，对齿轮的热温成形模具齿形设计也同样适用。     

渐开线花键导轴挤压模设计

采用挤压加工方法对渐开线齿形部分进行加工,不仅能显著地提高生产效率,而且还能提高齿形的强度和齿形精度。介绍渐开线花键齿形的挤压工艺过程,对模具的总体结构设计特点、渐开线齿形花键凹模的设计以及制造要点进行作了阐述。     

关于组合机床多轴箱主轴回转轴线与夹具导向孔轴线相对位置精度检验方法的探讨

本文论述了钻镗类组合机床精度标准中关于主轴回转轴线与夹具导向孔轴线相对位置精度的检验方法问题,对采用等距度检验方法和重合度检验方法作了分析对比,结论是:按等距度来评价主轴回转轴线与导向孔相对位置精度欠佳;但按重合度的数据来评价却是较优的。因此,作为行业控制产品质量的标准,这两种检验方法并存是不适宜的。     

The influence of serrated flow on necking in tensile specimens

Three-dimensional finite element simulations are used to investigate the role of serrated flow on the strain at the onset of necking in a cylindrical uniaxial tension specimen. The material is idealized using a modified form of the McCormick constitutive equation, which has an additional material parameter that allows the rate of transient aging to be varied without affecting its steady-state response. Stability calculations and direct simulations show that, if the transient response is sufficiently slow, serrated flow can be suppressed, even though the material has negative steady-state strain rate sensitivity. This result is then used to determine the effect of suppressing serrated flow on the strain to localization. We find that negative steady-state sensitivity significantly reduces the strain required to initiate necking failure in a tensile specimen. However, the strain to failure is largely unaffected by the transient response of the material, and suppressing the serrated flow in particular has a negligible effect on the localization strain. We conclude that, while both serrated flow and reduced ductility are observed in materials with negative rate sensitivity, the reduction in ductility is not a direct consequence of serrated flow.     

基于3D打印的CMM辅助测量技术

针对现阶段复杂零件在CMM上测量的不足,提出了采用基于3D打印的CMM辅助测量技术。为了能使产品在CMM探针精度最高的A0B0度方向测量,经常需要借助治具辅助。文中首先使用光学扫描技术获取产品表面数据,然后在Geomagic Studio软件进行数据处理,并将网格面导入到Rapidform软件对该产品的治具进行建模和设计,再将设计模型导入到3D打印机中得到治具模型,最后将测量的产品放置在治具中测量。通过试验证明,该方法可以很好地提升复杂零件在CMM下的测量效率。     

气缸体砂型铸造组芯夹具的优化设计

对气缸体组芯夹具的各种设计结构进行对比分析.对夹具结构、夹具本体、轴箱芯定位机构、水套砂芯组芯小车及夹具支架的设计优化进行了讨论.对夹具的设计理念提出了建议：既要实用、可靠、经济,又要美观.     

基于B样条的自由曲面超声自动检测轨迹生成

针对复杂曲面内部缺陷的超声检测,文章提出了一种基于B样条的自动检测轨迹生成算法, 该方法可以实现自由曲面工件的连续扫查检测,具有较高的检测效率.     

Efficient Simulation of Welding Distortion in Large Structures and Its Reduction by Jig Constraints

Two large construction machinery structures were welded separately with and without jig constraints. The welding distortion of the entire structure was measured by a 3D coordinate measuring system and simulated by elastic FEM using the inherent deformation method. To obtain an accurate inherent deformation, a thermal elastoplastic FE analysis of simple one-side fillet joints with and without jig constraints was performed. Efficient simulation of welding distortion in large structures was accomplished by applying inherent deformation in a localized region, and the effect of jig constraint on the reduction of welding distortion was clarified. The computation of inherent deformation, the weld zone definition and the conversion of inherent deformation into inherent strain were automated. Measured and computed welding distortions in large structures had a good correspondence with respect to both tendency and magnitude. Further investigation of jig configuration was performed for enhanced reduction of welding distortion. Alternative controlling techniques for common welded structures were also addressed.     

深孔加工的新方法——钻铣法

传统的深孔加工方法,如接柄麻花钻,机械夹固硬质合金钻头,单刃深孔钻,BTA深孔钻长期以来已在不同的范围内广泛地应用,但是这些方法至今未能解决钻孔时的零切削速度区问题。钻铣法在钻头上加装铣刀,切削时铣刀自转并连同钻头一起公转或钻头不转工件旋转,成功地解决了深孔钻削时的零切削区问题,为较大孔径的深孔加工提供了一种可供选择的新型加工方法。     

GRAIN SIZE AND ACTIVATION ENERGY OF SERRATED YIELDING

The apparent activation energy of serrated yielding was measured by two different methodsfor a commercial brass H68.The results showed that the apparent activation energy of serrat-ed yielding measured by a method involving(m+β)values increases with the grain size.Incontrast,those measured by another method without involving(m+β)values are all the samefor specimens with different grain sizes.Combining with the observation of themicrostructures,the above phenomena have been explained.The method to measure the trueactivation energy of serrated yielding has also been proposed.     

液压泵上体三孔加工车床夹具设计

为车床上加工液压泵上体3个阶梯孔设计夹具,此夹具是一种安装在花盘上的直线移动式车床专用夹具。分析夹具的结构特点、工作原理,计算其定位误差和夹紧力,进行加工精度分析,该夹具能保证三孔中心尺寸精度、三孔轴线与底面垂直精度以及与四小孔位置精度。     

下芯夹具在缸体组合芯上的优化设计

简述了缸体砂型铸造流水线下芯夹具应用现状,以及使用中存在的不足之处.经过多次试验、设计,运用动态仿生学对下芯夹具的结构做出局部调整,即平移机构代替杠杆机构.阐述了采用多层式下芯夹具的齿条带动齿轮平移运动机构以及夹紧机构同步性等的优化设计.在实际生产中,取得了良好的效果.在一定尺寸的铸件成型中,具有通用性.     

连杆零件的双圆柱定位钻模

介绍一种加工连杆零件孔的双圆柱钻模的工作原理与实施方式,并对钻模进行了可行性分析。该钻模具有结构简单、制造工艺性好、布置灵活、调整方便、生产效率高和实用性强等特点。依据双圆柱的定位原理,可设计出铣削和磨削连杆零件端面的夹具,能有效地避免零件加工中刀具与夹紧元件之间的干涉问题。