Towards in-process x-ray CT for dimensional metrology
Towards in-process x-ray CT for dimensional metrology
复制标题
DOI：
10.1088/0957-0233/27/3/035401
复制
发表时间：
2016-03-01
影响因子：
2.4
通讯作者：
Williams, Mark A.
中科院分区：
文献类型：
--
作者：
Warnett, Jason M.;Titarenko, Valeriy;Williams, Mark A.
x射线计算机断层扫描（CT）作为一种计量工具提供了巨大的潜力，因为可以捕获丰富的内部和外部数据，其中大部分是传统的光学和触觉坐标测量机（CMM）无法获得的。典型的基于实验室的CT可能需要30分钟以上的时间来生成一个物体的3D模型，这使得它不适合批量生产检测应用。最近，用于机场行李检查的新一代实时断层扫描（RTT） x射线CT已经开发出来，利用新型电子开关x射线源代替旋转龙门。这使得袋子可以在几秒钟内被扫描，并几乎实时地产生3D体积图像，用于定性评估，以识别潜在的威胁。这种系统能够以500毫米秒（-1）的速度扫描直径达600毫米的物体。目前这种系统的体素大小约为1毫米，比实验室CT大得多，但扫描时间明显更快，这是一个有吸引力的探索前景。本文将研究这种系统对增材制造零件的实时计量检测的潜力。Rapiscan RTT110 （RTT机场行李扫描仪）的测量精度通过与计量学确认的三坐标测量机和传统实验室ct的测量结果进行比较来评估。发现它产生的平均绝对误差为0.18 mm，可能已经在生产线上有一些应用。虽然这比实验室CT的误差更大，但建议进行一些调整可以提高分辨率，使该技术适用于更广泛的在线质量检测应用，包括铸造和增材制造零件。
X-ray computed tomography (CT) offers significant potential as a metrological tool, given the wealth of internal and external data that can be captured, much of which is inaccessible to conventional optical and tactile coordinate measurement machines (CMM). Typical lab-based CT can take upwards of 30 min to produce a 3D model of an object, making it unsuitable for volume production inspection applications. Recently a new generation of real time tomography (RTT) x-ray CT has been developed for airport baggage inspections, utilising novel electronically switched x-ray sources instead of a rotating gantry. This enables bags to be scanned in a few seconds and 3D volume images produced in almost real time for qualitative assessment to identify potential threats. Such systems are able to scan objects as large as 600 mm in diameter at 500 mm s(-1). The current voxel size of such a system is approximately 1 mm-much larger than lab-based CT, but with significantly faster scan times is an attractive prospect to explore. This paper will examine the potential of such systems for real time metrological inspection of additively manufactured parts. The measurement accuracy of the Rapiscan RTT110, an RTT airport baggage scanner, is evaluated by comparison to measurements from a metrologically confirmed CMM and those achieved by conventional lab-CT. It was found to produce an average absolute error of 0.18 mm that may already have some applications in the manufacturing line. While this is expectedly a greater error than lab-based CT, a number of adjustments are suggested that could improve resolution, making the technology viable for a broader range of in-line quality inspection applications, including cast and additively manufactured parts.