EM - Escola de Minas

Agora exibindo 1 - 3 de 3

Suppressing notch wear by changing the tool path in the side milling of a Ti‑6Al‑4 V alloy.
(2022) Inácio, Ricardo Henrique; Silva, Rodrigo Henriques Lopes da; Pereira, Igor Cézar; Hassui, Amauri
Despite many advantages ofered by titanium alloys compared to other conventional materials in the industry, several manufacturing challenges arise, and they are associated with titanium’s mechanical, thermal, and chemical properties. As a result of these characteristics, titanium alloys are low-machinability materials. Machining path strategies have proven their infuence over surface fnishing, machining forces, and tool life to reduce machinability-related problems. Most studies have shown the impact of the path strategies on frontal or end milling processes, and few are related to side (tangential) milling. Finally, based on the self-propelled rotary tool (SPRT) technique, which alters the cutting tool portion during machining, this work evaluates surface fnishing behavior, machining forces, and tool life using two diferent tool path strategies (sinusoidal and linear) on the side milling of Ti-6Al-4 V alloy. The results show that the association between an adequate tool path strategy (sinusoidal) and the cutting parameters improves surface fnishing (more than 130%), decreases cutting forces (about 20%), changes tool wear mechanisms, and increases tool life signifcantly (4–5 times) without productivity loss. Wear mechanisms that promote notch wear were suppressed, and uniform fank wear predominated. Consequently, the sinusoidal path has brought benefts to the cutting process. It is a technology that can have great interest and is easily applicable in the industry.
Tool life monitoring in end milling of AISI H13 hot work die steel using a low‑cost vibration sensor connected to a wireless system.
(2022) Vianello, Pedro Ivo Alves; Abrão, Alexandre Mendes; Maia, Antônio Augusto Torres; Pereira, Igor Cezar
Machining of complex components with high added value requires the development and implementation of technologies for monitoring the processes outputs and to ensure the performance and reliability of the manufactured part. Cutting tool wear is one of the most relevant variables in machining due to its efect on both the machining cost and quality of the manufactured component. Although tool wear has been extensively investigated for more than a century, the advent of Industry 4.0 has required more accurate and reliable monitoring systems. This work investigates the feasibility of using a low-cost vibration sensor, based on a micro-electromechanical system (MEMS), connected to a wireless data transmission system attached to a rotary tool (milling cutter) for tool wear monitoring when milling annealed AISI H13 hot work die with coated tungsten carbide inserts. A microcontroller with an integrated internet connection connected to a local server through the Wi-Fi network was employed. In order to validate the proposed system, tests were performed comparing its behavior with a conventional piezoelectric sensor in terms of sensitivity to changes in the cutting conditions and tool wear evolution. The results indicated that the proposed system responds satisfactorily to changes in the cutting conditions, with approximately a four-fold increase in the acceleration amplitude when either cutting speed or axial depth of cut were doubled. Although neither the MEMS nor the piezoelectric accelerometer was capable to detect tool wear evolution (considering a tool life criterion VBB=0.3 mm), the RMS value of the signal generated by the vibration sensor based on MEMS is approximately four times higher than that provided by the piezoelectric accelerometer, thus indicating a better representation of the vibration phenomenon resulting from fxing the MEMS on the tool (in contrast to the piezoelectric accelerometer attached to the workpiece).
Analysis of the coefficient of friction at the workpiece-tool interface in milling of high strength compacted graphite cast irons.
(2019) Silva, Leonardo Rosa Ribeiro da; Ruzzi, Rodrigo; Teles, Vinicius C.; Sales, Wisley Falco; Guesser, Wilson L.; Machado, Alisson R.
The coefficient of friction at the workpiece-tool interface is one of the main influencing parameters in machining. It can be tribologically investigated using conventional and open tribometers, however, there is no consensus as to which type of test has the best correlation with the real machining process. This work aims at investigating the use of three different methods to measure the coefficient of friction in the machining of three types of high strength compacted graphite cast irons, with variations in the size of the free graphite phase and the presence or absence of molybdenum carbides in the matrix. The coefficient of friction of the process was measured using two progressive load conventional tribological tests, the progressive load single sliding test with load ranging from 0.5 to 40 N and the progressive load reciprocate sliding test in both dry and starved lubrication regimen, with load ranging from 48 to 83 N. The coefficient of friction was also measured in a conventional machining center used as an open tribometer, where ramp milling tests were performed in workpieces fixed on a piezoelectric dynamometer, with a cutting depth varying from 100 μm to 0, to simulate a regressive load. The following machining parameters were varied: cutting speed, feed rate, tool geometry, tool coating and the use of minimum quantity of lubrication in contrast to dry machining. As the main results, the predominance of lubrication, even in small quantities, was observed as the most influential parameter in the coefficient of friction. An inverse relationship was also observed between the hardness of the materials and the coefficient of friction independent of the lubrication condition used. The results of the coefficient of friction obtained in progressive load re- ciprocate sliding and open tribometer tests showed the best correlation with those found in the literature for this kind of materials.

EM - Escola de Minas

Notícias

Navegar

Filtros

Configurações

Ordenar por

Resultados por página

Resultados da Pesquisa