Zayas-Figueras Enrique E, Buj-Corral Irene
Department of Mechanical Engineering, Barcelona School of Industrial Engineering (ETSEIB), Universitat Politècnica de Catalunya (UPC), Av. Diagonal, 647, 08028 Barcelona, Spain.
Micromachines (Basel). 2023 Feb 2;14(2):377. doi: 10.3390/mi14020377.
In this work, the design, manufacture and measurement process of constant-breadth cams is presented. The motion law of the cam was designed by means of Bézier curves and the corresponding design desmodromic constraints. The cams were manufactured in two different materials employing two different processes: PLA cams with fused filament fabrication (FFF) and aluminium cams with computer numerical control (CNC) milling. The main aim of this work is to compare both types of cams regarding dimensional accuracy and surface finish, in order to evaluate if it would be possible to temporally replace a metallic cam with a plastic one during the repair of the first one. Dimensions were measured with micrometres and surface roughness with a contact roughness meter. The results show that, in diametral dimensions, similar dimensional error values were obtained for both the 3D-printed and the machined cams. However, in longitudinal dimensions, whose direction is perpendicular to the 3D-printed layers, the 3D-printed cams showed higher dimensional error than the machined ones. The average roughness in the 3D-printed cams was 20 times higher than in the milled cams. According to the results, it would be recommended to temporally replace metallic cams with plastic ones in applications of low-power transmission. Given that in the literature little information is available about the measurement of 3D-printed desmodromic cams, this work will contribute to the study and analysis of this kind of 3D printed mechanism.
在这项工作中，介绍了等宽凸轮的设计、制造和测量过程。凸轮的运动规律通过贝塞尔曲线和相应的设计气门驱动约束进行设计。凸轮采用两种不同的材料和两种不同的工艺制造：采用熔丝制造（FFF）的聚乳酸（PLA）凸轮和采用计算机数控（CNC）铣削的铝制凸轮。这项工作的主要目的是比较这两种凸轮在尺寸精度和表面光洁度方面的情况，以便评估在维修金属凸轮时用塑料凸轮临时替代是否可行。尺寸用千分尺测量，表面粗糙度用接触式粗糙度仪测量。结果表明，在直径尺寸方面，3D打印凸轮和加工凸轮获得了相似的尺寸误差值。然而，在纵向尺寸（其方向垂直于3D打印层）方面，3D打印凸轮的尺寸误差比加工凸轮更高。3D打印凸轮的平均粗糙度比铣削凸轮高20倍。根据结果，建议在低功率传动应用中用塑料凸轮临时替代金属凸轮。鉴于文献中关于3D打印气门驱动凸轮测量的信息很少，这项工作将有助于对这种3D打印机构的研究和分析。
