中文摘要：

间隙特征的成型是免组装机构直接成型的关键问题,为了提高间隙特征的可成型性,采用倾斜摆放方式减少间隙内部支撑。建立悬垂结构尺寸误差的数学模型并进行试验验证;采用激光选区熔化（SLM）成型了间隙尺寸为0.2mm、一系列倾斜角度的间隙特征,研究成型厚度、倾斜角度和能量输入等工艺参数对间隙大小的影响;成型了免组装的折叠算盘。结果表明,在倾斜角度大于40°时,通过增大倾斜角度、减小成型厚度或者能量输入,间隙尺寸增大,实验结果与该数学模型相符合。当激光功率150 W、扫描速度为800mm/s时,层厚为25μm和35μm的间隙大小分别为140μm和120μm。采用以上的工艺参数成型的折叠算盘可以实现预设计的动作,为机构的直接制造提供了一个可行的方法。

英文摘要：

The manufacturing of clearance features is the crucial issue for direct manufacturing non-assembly mechanisms.To improve the processibility of clearance feature,tilted display is adopted to reduce the support within the clearance.A dimension error model for overhanging structure is established and a verification experiment is conducted,firstly.Then clearance feature of 0.2 mm with a series of tilt angles is manufactured by selective laser melting（SLM）to investigate the effects of process parameters,such as layer thickness,tilt angle and energy input on clearance size.Finally,a collapsible abacus is manufactured.Results show that the clearance size increases with increasing tilt angle,decreasing layer thickness or energy input when the tilt angle is lager than 40°.It shows that the theoretical dimension error fits the experimental results well.With laser power of 150 W,scan speed of800 mm/s and layer thickness of 25μm and 35μm,the clearance sizes are 140μm and 120μm,respectively.A collapsible abacus manufactured under the above process parameters can achieve designed performances well.It provides a feasible method for direct manufacturing of mechanisms.