减小内花键齿轮渗碳淬火畸变的方法

汽车、拖拉机齿轮的内花键,一般都采用内花键大径定心,内花键经渗碳淬火后不便进行加工。因此,要使齿轮内花键达到技术要求,减小齿轮内花键畸变尤为重要。现将几种减小齿轮内花键畸变的方法介绍如下: 1.花键拉刀冷、热公差配合 生产实践证明,内花键渗碳淬火变形规律一般趋向收缩变小,根据内花键的变形规律,不能采用标准花键拉刀,应采用非标准热缩型花键拉刀。通过试验可以确     

轴承钢GCr15SiMn试片与渗碳钢G20Cr2Ni4A试片接触疲劳寿命分析

通过研究轴承钢GCr15SiMn试片与渗碳钢G20Cr2Ni4A试片的接触疲劳寿命水平得知,渗碳钢G20Cr2Ni4A试片的各项寿命指标均高于轴承钢GCr15SiMn试片,且渗碳钢G20Cr2Ni4A试片的接触疲劳寿命是轴承钢GCr15SiMn试片接触疲劳寿命的3.75倍。     

Cr-Ni钢制材料多参数热处理工艺研究及应用

对20Cr2Ni4A、12CrNi3等Cr-Ni钢制渗碳件的高温二次回火、二次淬火热处理工艺进行了研究,并对其显微组织、硬度、晶粒度和力学性能等指标进行了分析测试。结果表明,20Cr2Ni4A等齿轮钢渗碳后采用多参数热处理,表面获得细小的马氏体加粒状碳化物组织,细化了芯部组织,有效消除了表面渗碳层中的网状渗碳体,满足了齿轮表面高性能的设计要求,工件同时具备了良好的综合力学性能和冷加工性能。     

轮齿显微组织对齿轮弯曲疲劳寿命影响的分析

对 2 0 Cr Ni2 Mo A和 2 0 Cr Mn Mo A渗碳淬火齿轮进行了化学成分、力学性能和金相组织分析。通过对其显微组织的观察和测定 ,对比分析显微组织对渗碳淬火齿轮弯曲疲劳寿命的影响因素     

18Cr2Ni4WA重载齿轮的热处理工艺研究

通过对18Cr2Ni4WA材料的渗碳、淬火过程的研究,最终制定了采煤机摇臂内所用重载齿轮的热处理工艺。     

渗碳齿轮弯曲疲劳强度研究

根据GB/T 14230-1993中规定试验设备、方法、应力水平和试验点,通过试验方法研究20Cr2Ni4A材料渗碳淬火齿轮弯曲疲劳强度。分析了引入R-S-N曲线的原因,并根据试验获得的数据分析拟合出R-S-N曲线,估计出相应循环次数所对应的齿轮弯曲疲劳强度极限。     

20Cr2Ni4A替代18Cr2Ni4WA齿轮材料钢的加工试验

为了降低采煤机和掘进机齿轮材料成本及生产成本,试验用20Cr2Ni4A制造齿轮零件,采用合适的热处理工艺参数保证满足零件设计要求以替代18Cr2Ni4WA齿轮材料。     

井式炉的天然气渗碳实践

1.问题的提出 我厂零件的渗碳一般采用煤油进行气体渗碳。例如某零件材料为20Cr2Ni4A,要求渗碳层深1.1～1.5mm,表面硬度≥58HRC。其渗碳工艺曲线见图1。     

修复内花键热后变形的挤压刀

我国大部分农机齿轮的设计均采用矩形内花键大径定心,而齿轮矩形内花键大径热处理后总会产生某种程度的畸变,这是不可避免的。随着齿轮加工质量的不断提高,修复热后内花键孔径的变形工艺越来越被人们所重视。 通常渗碳淬火的齿轮内花键趋于收缩,对于该类齿轮,大径变形应优先采用冷挤压工艺来修正尺寸。我们针对各类内花键热后变形量的不同,设计出一组内花键挤压刀,采用分类选刀的加工方法,经反复试验,摸索到了冷挤压修复齿轮热后内花键的经验,收到了良好的效果,修复合格率达90％以上。     

镀铜层厚度与渗碳层厚度的关系

为了控制渗碳齿轮花键孔的精度,对于底径或侧定位的齿轮,其加工流程为:机械加工—内孔镀铜—渗碳、淬火—回火—退铜—推刀精整花键孔。在过去的生产中,由于我们对镀铜层厚度与渗碳层厚度的关系一直把握不准,经常发生渗碳淬火后花键镀铜部位硬度偏高,推刀推不动的现象,为此我们做了以下试验。 1、试棒制作 (1)试棒选渗碳常用钢20CrMnTi。 (2)考虑到内孔为圆形,花键类似正方形,故试棒作成φ20mm×95mm和16.5mm×16.5mm×95mm     

Study of the influence of the friction clutch operability on the performance of the switch motor

In this paper, the results of studying the efficiency of an SP-6 M switch motor have been presented. The friction clutch plays an important role during the transmission of torque from a motor to an actuator. To study a motor switch, a test rig was developed in order to determine the necessary force to move switchblades depending on the pressing force of the friction clutch. The tribological properties of the friction disk materials have been investigated using a specially designed test machine.     

Determination of the parameters of the dispersion curves of lamb waves with the use of the Hough transform of the spectrogram of an AE signal

A method for the recognition of dispersion curves on the spectrogram of acoustic-emission signals has been developed based on the Hough transform. The method was successfully tested in an experiment using a Hsu-Nielsen source. It has been determined that the suggested method can determine the distance from the source of a signal, even when the signal arrives only at one acoustic emission transducer. This enables one to perform AE testing only with one-sided access to any dimensional object or when there is a sufficiently large distance between transducers, when an AE signal reaches only one of them.     

曲轴连杆颈磨削运动模型的研究

在以曲轴连杆颈中心为原点的坐标系中，对切点跟踪法磨削曲轴连杆颈过程，进行运动分析，建立数学运动模型，提出对C轴和X轴的进给补偿数学模型，并讨论了曲轴弹性变形量的计算方法。     

A study of the possibility of improving the time resolution of the PHOS spectrometer

Experimental investigations have shown that a timing device based on a constant-fraction discriminator is capable of providing a time resolution of approximately 0.5 ns and a timing error of approximately ±0.25 ns in the energy range of 0.8?1.8 GeV. In the region of “low” energies (<0.6 GeV), the time resolution is decreased by the influence of detector noise, whose level is ~3–5 mV for most scintillation detectors under investigation.     

An algorithm for the estimation of the quality of the spot welds

Spot welds are widely used in industry, especially in automotive, so welds must be reliable. One of the approaches to estimate the quality of spot welds is to use ultrasonic testing. Spot welding is used in the automotive repair industry as well. However, a spot weld testing device, dedicated for the automotive repair industry, is not available. The objective of this work was to develop an algorithm for estimation of the quality of spot welds, to be used in a simple device in the automotive repair industry. The algorithm developed identifies the peaks in the acquired signal and separates the main peaks (ultrasonic signal reflected from the backwall of the weld) from intermediate peaks (which identify the defects in the weld or undersized weld). Then, according to the peak distribution and peak amplitude variations in the signal, the quality of the weld is determined and an automatic pass or fail indication given. The algorithm was verified using a finite element model of a good weld, an undersized weld and a weld with a pore.     

An extension of the concept of the group

A group is traditionally regarded as part of a mechanism which has zero mobility when its external pairs are connected to the other parts of the mechanisms. This has meant that actuators have not been able to exist in a group. Such a group has been called an Assur group. In this note the concept of a group is extended to groups with many degrees of mobility. Such groups must have as many actuator pairs as degrees of mobility.     

Contributions to the theory of the axes of curvature

New metric properties are demonstrated for the axis of curvature of a trajectory curve and the Disteli axis of a trajectory ruled surface under a general motion of a body in space. Especially we get a characterization for the vertex congruence. As an application we give a new method of construction for the Disteli axis by means of straight hyperbolic nets and the distribution parameters.     

Unravelling the structure of the lamellipodium

Summary Pushing at the cell front is the business of lamellipodia and understanding how lamellipodia function requires knowledge of their structural organization. Analysis of extracted, critical-point-dried cells by electron microscopy has led to a current dogma that the lamellipodium pushes as a branched array of actin filaments, with a branching angle of 70 degrees , defined by the Arp2/3 complex. Comparison of different preparative methods indicates that the critical-point-drying-replica technique introduces distortions into actin networks, such that crossing filaments may appear branched. After negative staining and from preliminary studies by cryo-electron tomography, no clear evidence could be found for actin filament branching in lamellipodia. From recent observations of a sub-class of actin speckles in lamellipodia that exhibit a dynamic behaviour similar to speckles in the lamella region behind, it has been proposed that the lamellipodium surfs on top of the lamella. Negative stain electron microscopy and cryo-electron microscopy of fixed cells, which reveal the entire complement of filaments in lamellipodia show, however, that there is no separate, second array of filaments beneath the lamellipodium network. From present data, we conclude that the lamellipodium is a distinct protrusive entity composed of a network of primarily unbranched actin filaments. Cryo-electron tomography of snap-frozen intact cells will be required to finally clarify the three-dimensional arrangement of actin filaments in lamellipodia in vivo.     

抗蛇行减振器参数对车辆稳定性的影响分析

介绍了抗蛇行减振器的简化模型——Maxwell模型。基于蛇形运动的稳定性理论,推导了带抗蛇行减振器的刚性转向架的线性临界速度解析表达式。利用表达式研究了不同等效锥度下抗蛇行减振器串联刚度和结构阻尼对临界速度的影响。研究结果表明:在相同锥度下,结构阻尼和串联刚度存在最佳匹配关系,小结构阻尼应配合小串联刚度,较大结构阻尼应配合较大串联刚度,大结构阻尼应配合大串联刚度;在满足结构阻尼和串联刚度匹配的大范围下,不同等效锥度应匹配不同的串联刚度和结构阻尼,小锥度应匹配较小的串联刚度和较大的结构阻尼,大锥度应匹配较大的串联刚度和较小的结构阻尼。     

压力对涡流管性能影响的实验研究

采用自行设计的涡流管，并以空气作为工作介质，通过实验研究了在保持膨胀比不变的情况下，不同进口压力对涡流管性能的影响。实验结果表明：对于常温涡流管，在较小的膨胀比下，进口压力的改变对涡流管的制冷性能没有显著的影响；随着膨胀比的增加，进口压力的改变对涡流管制冷性能的影响也变得越来越显著。膨胀比为3时，进口压力的增加基本不影响涡流管的制冷性能，而膨胀比为6时，随着进口压力的增加，涡流管的制冷性能显著提高。