مقاله انگلیسی رایگان در مورد یک معماری رباتیک موبایلی واحدی در تونل های باریک – الزویر 2019

Advanced composite structural components in aeronautics are characterized by very high production costs because of their dimensions, complex shapes and expensive forming equipment. For these components, such as horizontal stabilizers and wings, a defect occurrence is often critical because large part of inner surfaces, made of long and tapered narrow tunnels, are not reachable for repair operations. In these cases, the part is rejected with a relevant economic loss and high production costs. For this reason, aircraft constructors plan huge investments for defects avoidance during the forming processes of CFRP and to develop effective, robust and reliable repair tools and methods. Mobile robotics can play an important role, with specific systems capable of moving into narrow channels of wings structures (i.e. multi spar boxes) and repair it in accordance to technical standards. This paper describes an innovative mobile robot architecture for bonded repair scarfing operations on CFRP components. Targeting and responding to the demanding machining requirements, the functional-oriented design approach clearly highlights the advantages of a modular robotic solution. The mobile robotic architecture can be also applied in other fields with similar challenging manufacturing operations for further inspection, detection and machining operations.

Introduction

Working in narrow space is a typical issue for the repair process of aeronautical structural components. Carbon Fiber Reinforced Plastic (CFRP) components, as wings and horizontal stabilizers, are often realized in the form of multi spar boxes assemblies. A typical example is the Boeing 787 Dreamliner horizontal stabilizer (tailplane) which has a multi-spar boxes structure and its cross-section is composed by a plurality of longitudinal tapered narrow tunnels. During the manufacturing process of these components some defects may occur. In order to reduce the high cost of discards, the necessity for an efficient and robust repair process arises. In literature, different technological processes and techniques for CFRP aircraft structures repair are available [1]. This paper deals with the application of such techniques in narrow spaces, as the multi spar boxes structures. Currently, the CFRP repair techniques are typically performed manually [2] and sometimes the damage is not accessible by the operator. In large CFRP multi-spar boxes structural components, indeed, human operators are able to repair internal damages only if localized in proximity of the wing tip or root. In all the other cases there are no fix strategies currently available and the components, often very expensive, must be discarded [3]. Thus, the position of the damage is crucial, as it causes a large number of discards in aeronautics manufacturing, with consequent increase of the production costs. Due to the lack of solutions of applying fixing techniques in narrow multi spar boxes, in this paper a strategy for the automation of such a process is described. Mobile robotics is identified as the key enabling technology that makes it possible. As a further advantage, some studies, remarked the importance of automated machining of CFRP and the advantages in terms of accuracy, quality and reliability compared with a manual operation [4]. Nevertheless, there are no available solutions for the repair of internal defects. The proposed approaches, indeed, consider either new specific devices to be manually fixed in proximity of the damage [5,6], or the use of conventional robots, too big for this purpose [7]. In [8] a robotic inspection cell is presented, composed of three industrial manipulators performing both, photogrammetry acquisitions and ultrasound-based NDT inspection. The robots can move along linear guides and the inspection of large components is enabled; however, there is no possibility for internal defects detection.