The improvement in grinding of inlet engine valves by the adoption of the most effective cuting fluid type

In this paper is presented an experimental research in which the grinding of seating surfaces of inlet engine valves was improved by the adoption of the most effective cutting fluid type, matching the new requirements of cutting fluid application. Four different types of cutting fluids (straight oil and three different types of soluble oils) were analyzed. As qualitative and quantitative evaluation parameters of the performance of the cutting fluids, the roughness, the grinding wheel wear, the cutting force and the workpiece residual stress were determined. As a conclusion, the straight oil was the cutting fluid that presented the best results in all of the parameters analyzed. Copyright © 2000 Society of Automotive Engineers, Inc.

Influence of optimized lubrication-cooling and minimum quantity lubrication on the cutting forces, on the geometric quality of the surfaces and on the micro-structural integrity of hardened steel parts

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo da predição da circularidade e rugosidade de peças retificadas utilizando as redes neurais artificiais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influência da matriz polimérica e dos métodos de extração de corpos de prova em compósitos de fibra de carbono

Pós-graduação em Engenharia Mecânica - FEB

Otimização das condições de refrigeração / lubrificação no processo de retificação cilíndrica de mergulho

Pós-graduação em Engenharia Mecânica - FEG

Growth Control of Microbial in Miscible Cutting Fluids Using Ultraviolet Radiation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito das diferentes direções de aplicação de jato de fluido de corte no torneamento de um aço de difícil usinagem

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Experimental investigations of heat transfer coefficients of cutting fluids in metal cutting processes: analysis of workpiece phenomena in a given case study

This paper reports an experimental method to estimate the convective heat transfer of cutting fluids in a laminar flow regime applied on a thin steel plate. The heat source provided by the metal cutting was simulated by electrical heating of the plate. Three different cooling conditions were evaluated: a dry cooling system, a flooded cooling system and a minimum quantity of lubrication cooling system, as well as two different cutting fluids for the last two systems. The results showed considerable enhancement of convective heat transfer using the flooded system. For the dry and minimum quantity of lubrication systems, the heat conduction inside the body was much faster than the heat convection away from its surface. In addition, using the Biot number, the possible models were analyzed for conduction heat problems for each experimental condition tested.

Numerical simulation of drop impact and jet buckling problems using the eXtended Pom-Pom model

This work presents numerical simulations of two fluid flow problems involving moving free surfaces: the impacting drop and fluid jet buckling. The viscoelastic model used in these simulations is the eXtended Pom-Pom (XPP) model. To validate the code, numerical predictions of the drop impact problem for Newtonian and Oldroyd-B fluids are presented and compared with other methods. In particular, a benchmark on numerical simulations for a XPP drop impacting on a rigid plate is performed for a wide range of the relevant parameters. Finally, to provide an additional application of free surface flows of XPP fluids, the viscous jet buckling problem is simulated and discussed. (C) 2011 Elsevier B.V. All rights reserved.

Surface integrity analysis in the super duplex stainless steel ASTM-A890 after machining

The purpose of this paper was to study the main effects of the turning in the superficial integrity of the duplex stainless steel ASTM A890-6A. The tests were conducted on a turning centre with carbide tools and the main entrances variables were: tool material class, feed rate, cutting depth, cutting speed and cutting fluid utilisation. The answers were analysed: microstructural analysis by optical microscopy and x-ray diffraction, cutting forces measurements by a piezoelectric dynamometer, surface roughness, residual stress by x-ray diffraction technique and the microhardness measurements. The results do not show any changes in the microstructural of the material, even when the greater cutting parameters were used. The smaller feed rate (0.1 mm/v), smaller cutting speed (110 m/min) and the greater cutting depth (0.5 mm) provided the smaller values for the tensile residual stress, the smaller surface roughness and the greater microhardness.

Estudo comparativo do comportamento de diferentes ferramentas na fresagem de aços duplex

A maquinagem por arranque de apara é, na actualidade, um dos processos de fabrico mais utilizados e de maior relevo no panorama da indústria metalomecânica mundial. Para além da forte evolução que se tem registado ao longo das últimas décadas nos equipamentos ligados à maquinagem, também as ferramentas têm visto o seu desempenho fortemente melhorado, graças essencialmente ao desenvolvimento de revestimentos finos, mono e multicamada, que têm proporcionado o conjunto de propriedades mais indicado a cada situação. Por outro lado, os aços inoxidáveis duplex têm registado um forte incremento na sua aplicação, a qual requer, em muitos casos, o uso da maquinagem para a obtenção das formas necessárias. Tendo em consideração estes dois factores, o presente trabalho visa, essencialmente avaliar qual a ferramenta mais adequada para trabalhar este tipo de ligas, em função do tipo de maquinagem e condições de corte. Para tal, foram utilizadas diferentes ferramentas dotadas da mesma geometria, e seleccionados parâmetros que constituíssem um denominador comum entre os valores indicados pelos diferentes fabricantes. Foram consideradas apenas condições de maquinagem com utilização de fluido de corte e realizados percursos de corte previamente determinados na fresagem, utilizando fresas de topo em condições de maquinagem de alta velocidade. A análise comparativa recaiu sobre a qualidade da superfície gerada por maquinagem, avaliada através de perfilometria, e o desgaste registado por cada uma das ferramentas utilizadas.

Randzonenveränderung beim Bohren und ihre Auswirkung auf Folgebearbeitungsverfahren

In der Praxis kommt es bei der spanenden Bearbeitung immer wieder zu großen Standwegunterschieden identischer Werkzeuge bei vordergründig identischen Bearbeitungsrandbedingungen. Insbesondere bei Fertigungsschritten, die das Bohren als Vorbearbeitung erfordern, kommt es gelegentlich zu atypischen Verschleißerscheinungen, die auf das Entstehen einer Neuhärtezone an der Werkstückoberfläche beim Bohren zurückgeführt werden. Grundsätzlich sind Randzonenveränderungen eine Folge der mechanischen und thermischen Beanspruchung bei der Bearbeitung. Beim Eindringen des Schneidkeils kommt es zu Kornverzerrungen, welche die Werkstückhärte bis in eine Tiefe von 40 bis 80 µm erhöhen können. Überdies wird die Randzone des Werkstücks durch den Bearbeitungsvorgang und den Spantransport erhitzt und durch den Kühlschmierstoff bzw. die so genannte Selbstabschreckung im Anschluss sehr schnell abgekühlt. So kann es in Abhängigkeit der Randbedingungen zu Gefügeänderungen mit härtesteigernder (Sekundärabschreckung) oder härtemindernder (Anlasseffekte) Wirkung kommen. Nicht zuletzt beeinflussen beide Beanspruchungsarten auch das Ausmaß der Eigenspannungen in der Werkstückoberfläche. In dieser Arbeit werden die beim Kernlochbohren erzeugten Randzonenveränderungen sowie die Standzeit von Folgebearbeitungswerkzeugen, wie Gewindebohrern und Gewindeformern, und deren Abhängigkeit vom Verschleißzustand des Kernlochbohrers untersucht. Weiterhin werden mit Hilfe einer Energiebilanz die Anteile herausgefiltert, die primär die Eigenschaften der Bohrungsrandzone beeinflussen. Dies geschieht mit Hilfe einer mathematischen Modellierung des Bohrprozesses, in der die Einflüsse der Schneidkantengeometrie, der Schneidkantenverrundung, der Schneidkantenfase sowie des Freiflächenverschleißes berücksichtigt werden.

Influência na qualidade final de metais retificados através da variação da velocidade de mergulho

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influência da lubrirrefrigeração na qualidade superficial de metais retificados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fresamento com ar quente: uma proposta para minimizar a formação de trincas térmicas em ferramentas de metal duro

This work presents the results, analyses and conclusions about a study carried out with objective of minimizing the thermal cracks formation on cemented carbide inserts during face milling. The main focus of investigation was based on the observation that milling process is an interrupted machining process, which imposes cyclic thermal loads to the cutting tool, causing frequent stresses changes in its superficial and sub-superficial layers. These characteristics cause the formation of perpendicular cracks from cutting edge which aid the cutting tool wear, reducing its life. Several works on this subject emphasizing the thermal cyclic behavior imposed by the milling process as the main responsible for thermal cracks formation have been published. In these cases, the phenomenon appears as a consequence of the difference in temperature experienced by the cutting tool with each rotation of the cutter, usually defined as the difference between the temperatures in the cutting tool wedge at the end of the cutting and idle periods (T factor). Thus, a technique to minimize this cyclic behavior with objective of transforming the milling in an almost-continuous process in terms of temperature was proposed. In this case, a hot air stream was applied into the idle period, during the machining process. This procedure aimed to minimize the T factor. This technique was applied using three values of temperature from the hot air stream (100, 350 e 580 oC) with no cutting fluid (dry condition) and with cutting fluid mist (wet condition) using the hot air stream at 580oC. Besides, trials at room temperature were carried out. Afterwards the inserts were analyzed using a scanning electron microscope, where the quantity of thermal cracks generated in each condition, the wear and others damages was analyzed. In a general way, it was found that the heating of the idle period was positive for reducing the number of thermal cracks during face milling with cemented carbide inserts. Further, the cutting fluid mist application was effective in reducing the wear of the cutting tools.