IK Foundation

Tapping is a widely employed but complex manufacturing process in which a multi-toothed tool, known as a tap, cuts a mating thread when driven into a hole. In this paper, the experiments, statistical analysis and the on-line implementation of a new thread quality monitoring system are presented for a tapping process in high-speed conditions. A multivariate statistical process control chart, for each tap, is presented based on the principal components of the torque directly measured from spindle motor drive. The on-line implementation of the multivariate chart provides tap wear warnings and alarms before the process starts producing unacceptable screw threads. The system is cost-effective since the tapping process can be run automatically without any operator intervention, does not require intrusive sensors, does not result in false negatives (defects) and provides an acceptable number of false positives.

Friction stir welding (FSW) is an energy efficient and environmentally "friendly" (no fumes, noise, or sparks) welding process, during which the sheets are welded together in a solid-state joining process. FSW is mature for simple configurations but a significant lack of knowledge is found when dealing with different designs such as T-sections, corner welds and box sections. The present work explores the feasibility of producing corner fillet geometries using FSW. Although such a kind of geometry has traditionally been considered unfeasible for the process, it seems to have a great potential to be used for T-joint configurations, a recurrent design pattern in transport applications. A specific tool has been developed and a set of welds has been produced with it. The process has been analysed by both micro and macro observations and a dedicated numerical model tuned by comparison of the thermal histories experimentally measured by embedded thermocouples. According to the obtained results, the proposed model is able to represent a useful design tool for the process. Main problem pending to be solved is how to avoid the formation of a tunnel defect in the weld centre line due to a suck effect of the tool on the stirred material.

Nowadays many industrial sectors use forming processes in order to produce sheet metal components. The most widely used processes are stamping and deep drawing, which are based on big, costly dies and presses. These processes require large initial investment and specific dies for each part, which makes them inflexible and only profitable for large batches. A possible approach to small series production is based on the incremental sheet forming technique (ISF), which consists of a gradual plastic deformation of flat sheet metal by the action of a CNC controlled tool. Equipment such as a 3-axis milling machine can be used for ISF, such that the initial investment costs in ISF are around 5-10% of those required to set up a production line for conventional stamping. In its current stage of development, dedicated dies are often used as support tools in ISF. However, due to the fact that the forming forces are low in ISF, the dies can be made out of cheap materials like resin or wood. Although this is an additional advantage over stamping, the need to use additional tools still reduces the flexibility of the process. The present paper details the concept of a truly “dieless” incremental forming process. In the framework of the SCULPTOR EU project, the authors are working on an innovative concept of incremental sheet metal forming which is based on the replacement of the commonly used dies by a second forming tool which moves in a coordinated way with the first forming tool, thus creating a flexible die system, which does not depend on the specific geometry of the part to be formed. The present work summarizes the results obtained up to now in two fields: (i) the development of a prototype for the flexible die system to be included both in milling machines or combined with robots and (ii) process modelling to improve the understanding of the process.

<div class="htmlview paragraph">The system that will be presented consists of a Crawling Portable Robot (CPR) for drilling large air frame components as a part of the whole assembly process of fuselage or wing type sub-structures.</div> <div class="htmlview paragraph">Currently, the drilling of such components is massively fulfilled manually in a very labour intensive and “craft-based” manner. The operations are conducted in cramped, dangerous conditions and often involve unhealthy postures. The alternative to this situation consists in the use of large fixed-base multi-axis machines mounted upon a foundation on the shop floor.</div> <div class="htmlview paragraph">These machines are quite expensive, and also have a number of operational limitations. Because of their large working envelope, it is difficult for these machines to hold close tolerances over the entire range of all movement axes of the machine. Hence, there is a need to probe and calibrate the machine to the workpiece one or more times during work operations with the consequent negative impact in productivity. Moreover, the machines also require permanent floor space and require the structure that is to be processed to be brought to the machine with the non-productive transit time that is incurred in this process.</div> <div class="htmlview paragraph">The innovation presented seeks to improve upon the situation described above by providing a portable multi-axis drilling robot. The system consists in a robot that is stored in a wheeled station designed for that purpose. Whenever its services are needed, the storage carriage is brought to the component being assembled, and the robot is fixed to the aeronautic component by its own vacuum cups. After self-referencing with the aid of a vision system, the drilling work is done inside the robot working volume. Once this finished, the robot can move and relocate autonomously to the next working volume on the panel by means of a walking or crawling system. Once the work on the full component is finished, the robot is taken down from the panel and placed again in the storage station.</div>