Rodrigo Eduardo Catai

COMPORTAMENTO DOS TRABALHADORES DA CONSTRUÇÃO CIVIL – ESTUDO DE CASO

In this paper, we first discussed multiplicative metric mapping by giving some topological properties of the relevant multiplicative metric space. As an interesting result of our discussions, we observed that the set of positive real numbers

Performance of aerodynamic baffles in cylindrical grinding analyzed on the basis of air layer pressure and speed

\mathbb{R}_+

Analysis of diametrical wear of grinding wheel and roundness errors in the machining of steel VC 131

is a complete multiplicative metric space with respect to the multiplicative absolute value function. Furthermore, we introduced concept of multiplicative contraction mapping and proved some fixed point theorems of such mappings on complete multiplicative metric spacesIn this paper, we first discussed multiplicative metric mapping by giving some topological properties of the relevant multiplicative metric space. As an interesting result of our discussions, we observed that the set of positive real numbers R_+ is a complete multiplicative metric space with respect to the multiplicative absolute value function. Furthermore, we introduced concept of multiplicative contraction mapping and proved some fixed point theorems of such mappings on complete multiplicative metric spaces.

Global analysis of aerodynamics deflectors efficiency in the grinding process

Over the years, grinding has been considered one of the most important manufacturing processes. Grinding is a high precision process, and the loss of a single workpiece in this stage of the production is unacceptable, for the value added to the material is very high due to many processes it has already undergone prior to grinding. This study aims to contribute toward the development of an experimental methodology whereby the pressure and speed of the air layer produced by the high rotation of the grinding wheel is evaluated with and without baffles, i.e., in an optimized grinding operation and in a traditional one. Tests were also carried out with steel samples to check the difference in grinding wheel wear with and without the use of baffles. Keywords : grinding, aerodynamic baffle, optimized process

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

Due to the high industrial competitiveness, the rigorous laws of environmental protection, the necessary reduction of costs, the mechanical industry sees itself forced to worry more and more with the refinement of your processes and products. In this context, can be mentioned the need to eliminate the roundness errors that appear after the grinding process. This work has the objective of verifying if optimized nozzles for the application of cutting fluid in the grinding process can minimize the formation of the roundness errors and the diametrical wear of grinding wheel in the machining of the steel VC 131 with 60 HRc, when compared to the conventional nozzles. These nozzles were analyzed using two types of grinding wheels and two different cutting fluids. Was verified that the nozzle of 3mm of diameter, integral oil and the CBN grinding wheel, were the best options to obtain smaller roundness errors and the lowest diametrical wears of grinding wheels.

Analysis of the influence of infeed rate and cutting fluid on cylindrical grinding processes using a conventional wheel

The conventional grinding methods in some cases are not very efficient because the arising of thermal damages in the pieces is very common. Optimization methods of cutting fluid application in the grinding zone are essential to prevent thermal problems from interaction of the wheel grains with the workpiece surface. The optimization can happen through the correct selection of the cut parameters and development of devices that eliminate air layer effects generated around the grinding wheel. This article will collaborate with the development of an experimentation methodology which allows evaluating, comparatively, the performance of the deflectors in the cutting region to minimize the air layer effect of the high speed of the grinding wheel. The air layers make the cutting fluid jet to dissipate in the machine. An optimized nozzle was used in order to compare the results with the conventional method (without baffles or deflectors) of cutting fluid application. The results showed the high eficciency of the deflectors or baffles in the finish results.

Desenvolvimento de um torquímetro de precisão para o estudo do desempenho de implantes osseointegrados

Grinding, the final stage of the machining process, employs a significant amount of cutting fluids for lubrication, cooling and swarf removal. However, these cutting fluids are extremely aggressive to the environment. With technological progress, the world tendency is to produce more and more sophisticated pieces,having a high degree of geometrical and dimensional tolerance, good surface finish, hlow cost and, mainly, insignificant impact on the environment. Therefore, recycling cutting fluids is intrinsic and cost-cutting for the grinding process and This work aimed to assess several output parameters in external cylindrical grinding: tangential force, acoustic emission, surface roughness, roundness, tool wear, and residual stress. Also, analysis of microstructural features through Scanning Electron Microscopy (SEM) was carried out. Tests was developed for ABNT D6 steel, using a CBN grinding wheel with vitrified bond and two types of cutting fluids Analyzing cutting fluid performance, grinding wheel time and feed rate, the best grinding conditions were found, leading to a decrease in cutting fluid volume and grinding time without impairing the geometrical and dimensional parameters, surface finish and surface integrity of the parts.

Studies on the Cooling Minimum Quantity and Conventional Cooling at Hardened Steels in Grinding Process

New worldwide trends such as globalization have rendered grinding processes increasingly important for industry, making it essential to perform in-depth studies of variations in grinding process parameters in the pursuit of greater cost effectiveness. This paper presents a comparative analysis of three different infeed rates, using a conventional grinding wheel on quenched and tempered D2 steel workpieces. Higher infeed rates are known to be correlated with shorter grinding times, rendering the process more economically attractive. Two different coolant fluids, 5% emulsion and pure oil, were used. The tests were carried out using the smallest possible amount of coolant and an optimized 5 mm diameter nozzle. The parameters analyzed were tangential force, specific energy, acoustic emission, roundness error and surface roughness. The surfaces of the workpieces were also examined by scanning electron microscopy (SEM). The results revealed that increased infeed rates could reduce processing times without compromising the quality of the workpiece profile, thereby reducing the cost of the process. The best cutting fluid, albeit more harmful to human health and less environmentally friendly, was found to be pure oil.

Desgaste de ferramentas no torneamento com alta velocidade de corte da superliga "waspaloy"

This paper has as objective, to present the project, the construction and the results obtained in the study of the osseointegration with a torque gauge of high precision. The torque gage, especially developed for this research type, was used to improvement of odontological research on osseointegration of dental implant. The implants were done in seven rabbits that were available after 21 and 42 days. In some rabbits were made ultra-sonic stimulations at rabbits’ implants. The results showed that the torque to remove the implant of the rabbits is directly proportional at the time of osseointegration and that the ultra-sonic stimulations can also influence the torque in some cases.

ERGONOMICS AND THERMOGRAPHY INSIDE THE ASSEMBLY LINE

The purpose of this work is to explain the concept of cutting fluids reasonable usage through the fluid minimum quantity in grinding processes. On that purpose, the development of a new nozzle and an own and adequate methodology should be required in order to obtain good results and compare them to the conventional methods. The analysis of the grinding wheel/cutting fluid performance was accomplished from the following input parameters: flow rate variation by nozzle diameter changes (three diameters values: 3mm, 4mm and 5mm), besides the conventional round nozzle already within the machine. Integral oil and a synthetic emulsion were used as cutting fluids and a conventional grinding wheel was employed. The workpieces were made of steel VC 131, tempered and quenched with 60HRc. Thus, as the flow rate and the nozzle diameter changes, keeping steady fluid jet velocity (equal to cutting velocity), attempted to find the best machining conditions, with the purpose to obtain a decrease on the cutting fluid volume, taking into consideration the analysis of the process output variables such as cutting strength, cutting specific energy, grinding wheel wear and surface roughness. It was verified that the 3mm diameter optimized nozzle and the integral oil, in general, was the best combination among all proposed.