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Lima M.,Center for Mechanical and Materials Technologies | Lima M.,University of Minho | Seabra E.,Center for Mechanical and Materials Technologies | Seabra E.,University of Minho | And 2 more authors.
Romanian Review Precision Mechanics, Optics and Mechatronics | Year: 2011

The Multiweave project involved the design of several complex mechanisms and in particular various conjugate cams with oscillating roller follower. In order to evaluate the quality of the manufactured cam profiles as well as the accuracy of the follower displacement, an experimental work has been designed and carried out. The whole set-up is presented with the experimental details and the results are analysed and discussed. This measurement system is based on a laser triangulation sensor Micro-Epsilon ILD 1302-50 to measure with no contact and high resolution. The obtained results were compared with the expected theoretical values and it could be concluded that, in general, the experimental results adjust very well to the theoretical ones. However there are some visible differences. From the analysis it was possible to conclude about the existence of some differences due to clearances in joints, geometric differences in the cinematic chain and manufacturing defects on the follower in terms of irregularities and surface roughness as well as some manufacturing imperfections of the cam surface. This study will be of great importance in the development of the new prototype machine to produce multidirectional woven fabrics, which is the main objective of the current Multiweave-2 project.


Vu M.H.,Center for Mechanical and Materials Technologies | Seabra E.,Center for Mechanical and Materials Technologies | Sepulveda J.,University of Minho | Lima M.,Center for Mechanical and Materials Technologies
Romanian Review Precision Mechanics, Optics and Mechatronics | Year: 2011

Devices for wrist rehabilitation must be able to make movements of the wrist quirky and complex. Powerball® is such a market existing device that can be used for wrist rehabilitation and also as a sports aid for strengthening the wrist. The operation of Powerball® is based on the gyroscope principle. While the gyroscope is spinning, the movement of the wrist will tilt the shell and a reaction moment will be produced. However, Powerball® in the existing market model must be manually started. Patients with fractured wrist will have difficulty to start it themselves. Speed is also not controlled and as a result, level of rehabilitation cannot be suitably adjusted. To maintain the rotation of the mass inside Powerball®, the torque must be at least equal to the minimum torque and patients in the early stages of rehabilitation will have difficulty to keep the Powerball® working. Besides, in some models of Powerball®, a small panel attached to the ball and allowing inspection of the number of revolutions of the mass and some other parameters during the training is available. However, during the operation of the ball, patients will find inconvenience to view and manipulate the panel. For improving the effectivity of the wrist rehabilitation processes, a new type of Powerball® has been developed. This will have adjustable speed given by an electric motor inside the ball, and consequently the manual start and the requirement of minimum torque will be eliminated. Also, a system composed by sensors, data acquisition board and human-machine interface was considered to allow the process of rehabilitation to be fully controlled. In the paper, the mechatronic design of a new type of Powerball®, named ControlledBioBall, carried out to overcome the present drawbacks, is be presented and discussed.


Borges P.C.,Federal Technological University of Paraná | Rocha L.A.,Center for Mechanical and Materials Technologies | Rocha L.A.,University of Minho
Kovove Materialy | Year: 2011

The results of the investigation on Solution Heat Treatment of Plasma Nitrided (SHTPN) precipitation-hardened steel 15-5 PH are presented. The layers have been obtained by the plasma nitriding process followed by solution heat treatment at different temperatures. The influence of the solution heat treatment after nitriding on the dissolution process of the nitrided layer has been considered. The nitrided layers were studied by scanning electron microscopy, X-ray microanalysis (EDX), and X-ray diffraction. Micro-hardness tests of the nitrided layers and solubilized nitrided layers have been carried out and interpreted by considering the processing conditions. It was found that high nitrogen austenitic cases could be obtained after SHTPN of martensitic precipitation-hardened steel (15-5PH). When Solution Heat Treatment (SHT) was performed at 1100°C, some precipitates were observed. The amount of precipitates significantly reduced when the temperature increased. The EDX microanalysis indicated that the precipitate might be chromium niobium nitride. When the precipitation on the austenite phase occurred in small amount, the corrosion resistance increased in SHTPN specimens and the pit nucleation potential also increased. The best corrosion result occurred for SHT at 1200°C.

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