鼓形体的铣削及参数选择

提出鼓形体铣削的优点及其加工方法,并进行了误差分析和参数选择,为中小企业铣削鼓形体提供了切实可行的理论依据。

r>R鼓形体的铣削方法

通常加工鼓形体主要有车削和铣削两种方法。本文主要介绍用铣削加工r>R的鼓形体,和车削相比的优点是:效率高、表面光洁度好且可节省靠模板。铣削是在立铣床和龙门铣上配合分发头来加工的。工件借助于定心轴或工艺夹头装卡在分度头上,铣削时刀具按一定的偏心量和回转半径回转,分度头带动工件进行分度。这两个运动的合成就可铣出鼓形体。图1所示,1为铣刀盘、2为工件、0—0为工件回转轴心,0′—0′为刀具回转轴心。

弯曲斜螺旋线的数学模型研究与应用

针对弯曲斜螺线这类非回转体零件做回转运动出现的问题进行研究,从空间几何的角度对斜螺线旋转的要素进行分析,由球体,环面螺旋线的数学模型延伸到螺旋线鼓形体,斜螺旋线椭球体,进一步得出任意起点斜螺线弯管的数学模型,最终提出了弯曲斜螺旋线做回转运动的数学方程。然后通过MATLAB对其数学模型进行仿真验证,得到弯曲斜螺旋线的通用数学模型。为后续弯曲斜螺旋线的加工提供理论依据。

Deformation inhomogeneity due to sample-anvil friction in cylindrical compression test

Finite element(FEM)analysis was used to systematically evaluate the inhomogeneity of deformation in cylindrical samples with various sample-anvil friction coefficients,m.It was found that the level of friction strongly influences the deformation homogeneity,which increases significantly with the friction coefficient although the overall geometry of the samples almost remains the same when m >0.4.The position,at which the effective strain along the maximum radial direction in a compressed sample is equal to the equivalent strain of the sample,does not vary greatly with respect to both equivalent strain of the sample and m.Hardness measurements of compressed cylindrical 5056B Al alloy samples revealed a change of effective strain distribution similar to that revealed by FEM analysis.There exists a quantitative relationship between the hardness and the effective strain if no recrystallization or recovery occurs during the compression process.

物理教学如何培养创造性思维

＂创新是一个民族进步的灵魂,是一个国家兴旺发达的不竭动力＂。创造性思维是一种探索未知事物的高级复杂的思维,是一种有自己的特点、具有创见性的思维,是扩散思维和集中思维的辩证统一,是抽象思维和灵感思维的对立统一。