工程机械液压柱塞泵使用与维修新探

本文以直轴斜盘式柱塞泵为例，介绍关于工程机械液压柱塞泵使用与维修的几种新的方法。     

V型缸上箱体低压铸造

在研制开发豪华型250摩托车2V60M发动机过程中,解决了上箱体低压铸造过程中零件复杂、分型困难、浇道、 嵌件定位、型腔排气、模温控制、铸件缩补等技术难题,保证了铸件的优良品质。     

皮带助卷器液压回路原理设计及故障诊断

通过对冷轧后处理机组皮带助卷器的结构和运动特点的分析,进行了液压回路的设计;利用仿真软件对该液压回路进行动态仿真验证。在现场调试过程中,发现该液压回路不能保压。经排查,最后通过实验的方法找到问题原因。通过该问题的解决过程得知:在设计液压原理时,不但要选择合理的液压回路及阀件,还必须充分考虑油缸的内泄漏对系统的影响,并应提出油缸内泄漏的要求和减小内泄漏的措施。     

低速气缸与高速气缸

气动技术中气缸运动速度是一个重要技术参数，本文对气缸能达到的最低无爬行状态的速度和高速运动时的最高速度进行了分析。     

降低熟料出口温度的研究

对“降低熟料出口温度的研究”进行可行性论证,通过大量的计算数据和熟料冷却的原理证明,在传统的氧化铝熟料窑和单筒冷却机之间加一小型篦冷机,可以降低熟料出冷却机的温度。文章介绍了项目实施后的经济效益、存在的问题以及改进情况。     

Unsteady viscous flow over elliptic cylinders at various thickness with different reynolds numbers

Two-dimensional incompressible Navier-Stokes equations are solved using SIMPLER method in the intrinsic curvilinear coordinates system to study the unsteady viscous flow physics over two-dimensional ellipses Unsteady viscous flows over various thickness-to-chord ratios of 06, 08, 10, and 1 2 elliptic cylinders are simulated at different Reynolds numbers of 200, 400, and 1,000 This study is focused on the understanding the effects of Reynolds number and elliptic cylinder thickness on the drag and lift forces The present numerical solutions are compared with available experimental and numerical results and show a good agicement Through this study, it is observed that the Reynolds number and the cylinder thickness affect significantly the frequencies of the force oscillations as well as the mean values and the amplitudes of the drag and lift forces     

Plastic limit load of cylindrical shells with cutouts subject to pure bending moment

In this paper, the results of limit analyses of thin-walled cylindrical shells with a circular hole under the action of a pure bending moment are presented in dimensionless form for a wide range of geometric parameters. Analytical estimation of lower bound limit load is carried out using the feasible sequential quadratic programming (FSQP) technique. The finite element calculations of limit load consist of elastic–plastic and lower and upper bound predictions by elastic compensation methods. A testing device was made to perform experiments to obtain limit bending moment of cylinders with circular openings. The analytical and finite element calculations are compared with experimental results and their correlation is discussed. The finite element calculation results were found to be in good agreement with lower bound estimations by the nonlinear mathematical programming (FSQP) method and the formula proposed by Shu.     

U形涤纶面料的动态热湿传递性能

利用微气候圆筒仪对U形截面涤纶面料的动态热湿传递性能进行测试,并与常规的麻、羊毛和圆形涤纶面料进行了比较,结果表明新开发的U形涤纶面料具有良好的动态热湿舒适性能.     

双作用液压缸在冲压机中的新应用

通过对传统冲床与双作用液压缸冲床的机构及工作过程的分析,得到在近似相同的工作时间内,新型机床的功耗降低了25%.因此,通过改进传统冲压机床的操作控制系统,实现机-电-液-体化,提高工作效率,节约能源.     

利用复射线法分析腔体的散射场

利用基于几何光学和高斯波束法的复射线法分析了相对任意开口圆柱腔的后向散射场。该圆柱腔内部包含较复杂的中心锥，叶片等结构，计算了两种较复杂进气道模型的雷达截面，所得结果均与弹跳射线法结果进行了比较，二者吻合很好，该方法受计算机内存影响小，对电大腔体，复射线法精确高效。