Applied Mechanics and Materials Vols. 809-810

Abstract: This article studies the cutting moment at drilling of the stainless steel X5CrNiMo17-12-2. The structure of the cutting moment relation was modified with respect to the relation available in the technical literature for common steels. The tool speed was included in the calculus relation. The experimental data and their subsequent processing represent the original contributions of the authors to the estimation of polytropic exponents and to the assessment in terms of structure of the calculus relation of the cutting moment. The paper also contains graphs with the cutting moment variation depending on the parameters of the cutting technology. The graphs are drawn based on the analytic relationship of the cutting moment, obtained in the article, using the mathematical software Maple. The results presented in this study can be taken into consideration in the educational studies and in the theoretical technical research. Also, they can be readily implemented in the manufacturing activity. Our further studies aim these problems for other classes of steels and cutting machining processes.

Abstract: In the specialized literature the cost of the machining process has been analyzed using a number of approaches and varying degrees of simplification to determine the optimum tool life and the tool speed. The accuracy of prediction is dependent on the degree of sophistication of the model. The purpose of this paper is the optimization of the cutting tool life and the cutting speed at the drilling of the stainless steels in terms of the minimum machining cost. A more comprehensive nonlinear programming model to minimize the total cost at the drilling of a stainless steel is developed in this paper. The optimum tool life and the associated tool speed are obtained by solving this model. The results can be taken into consideration in the educational studies and in the theoretical technical research. They can be implemented in the manufacturing activity.

Abstract: The research in the last decade regarding their cutting machinability have highlighted the insufficiency of the data for establishing of the optimum cutting processing conditions and the optimum cutting regime. The purpose of this article is the optimization of the tool life and the cutting speed at the drilling of the stainless steels in terms of the maximum productivity. A nonlinear programming mathematical model to maximize the productivity at the drilling of a stainless steel is developed in this paper. The optimum cutting tool life and the associated cutting tool speed are obtained by solving the proposed mathematical model. The use of this productivity model allows greater accuracy in the prediction of the productivity for the drilling of a certain stainless steel and getting the optimum tool life and the optimum cutting speed for the maximum productivity. The obtained results can be used in production activity, in order to increase the productivity of the stainless steels machining. Finally the paper suggests new research directions for the specialists interested in this field.

Abstract: Since the beginning of industrial era it was clear that the goal of perfect machine is far away. Things become more complicated as the tool machinery branch developed in quite a fast way so things as using full production capacity of a machine or working with adaptive control become normal and frequent. Reaching a good precision in manufacturing was realized by strengthening the structure , with related weight growth and use of more material both generating supplementary costs. Probably the best idea was to create a structure not so rigid , that means lighter ,a structure predictable in the way it works that means predictable deformation and their direction. The big advantage of the idea is that knowing the deformation we can take corrective actions so that the final precision at the edge of the cutting tool becomes very high. The corrective action consists in a very fine and very fast movement that composed with the structure deformations makes a great precision. The solution it self-generated a new challenge consisting in the need for almost instant movement , the source of which was not conventional. The authors are proposing a “magnetostrictive” engine as a new way of generating precise correction movements.

Abstract: Formation of the ground surface is the result of the interaction of the cutting elements of the diamond tool with the material being processed, so the nature of the working surface geometry of the grinding wheel (WSW) has principal value on processed surface quality. One of the main parameters that characterize the geometry of the WSW is the law of the grain distribution vertex in height. However, statistical models do not reflect the real picture of the tool interaction with the material being processed in the modelling process of grinding tool on the elastic ligament used for final operations. In the process of contact with the material being processed each diamond grain is moved with an adjacent block ligament, changing the position of the cutting vertex relative to both the midrange cords level and the other grains vertexes. As a result the nature of the grain vertexes distribution changes and the conditions of interaction with the material being processed change too. Studies have shown that the density distribution in height of diamond grains elastic grinding tool vertexes in a static state can be described by different distribution laws. For practical use in the calculation of the processed surface roughness and processing capacity is sufficient to approximate the distribution in height only the most protruding grains. In the area of contact with the processed material the distribution density of the grains elastic tool in height significantly differs from the static characteristics and is defined by the elasticity degree of the grinding tool ligament and machinability index of the workpiece material. The obtained results can serve as initial data for the calculation of the processed surface roughness.

Abstract: Hard milling is considered to be a precise and efficient machining method for the die and mold manufacturing industry. The main criterion for evaluating the cutting processes of the parts designed for these applications is the quality of the machined surfaces. For this reason, the analysis of the factors that influence the surface roughness obtained in this processes is important for helping the process become more productive and competitive. The present paper presents some results and an empirical model for surface roughness when high speeds face milling of AISI W1 tool steel. The influence of cutting parameters and material hardness is investigated by using Taguchi design of experiments. The results obtained show that high speed face milling of hardened tool steel AISI W1 can be carried out in economical conditions(on plant milling machines) and can lead to satisfactory surface quality (Ra =0.2-0.36 μm).

Abstract: Frequently, on the drawings of mechanical parts, only indications concerning the surface roughness parameter Ra and, relatively rarely, the surface roughness parameter Rz are included. However, the study of the machined surface roughness highlights the necessity to use yet other surface roughness parameters, in order to have a clearer image on the state of the machined surface. Some other surface roughness parameters possible to be used and presenting importance, without the parameters Ra and Rz, were highlighted. One took into consideration the possibility of measuring parameters Rsk and Rmr by means of the available surface roughness testers. Experimental researches of turning by applying the method of full factorial experiment were developed. As input factors in turning process, the cutting speed, the feed rate and the tool nose radius were used. The experimental results were mathematically processed, being determined empirical mathematical models that highlight the influence of certain input factors of turning process on the values of some surface roughness parameters characterized by a more restricted use

Abstract: The ball nose end milling process, which use a ball nose cutter, is very complex and, generates a pronounced area variation of the cross section in the uncut chip. In this sense, the current paper looks into and assesses some aspects regarding the geometric simulation of the chip generating mechanism in 5 axes ball nose end milling. The influence of tool inclination, however, was not considered in the machining strategy, starting with the tool path program in CAM software, which allows the management of various ways of tool path generation, but cannot decide which one is the best. The present study advances, with minimal approximation, a geometrical method to establish the volume of the uncut chip and area variation of the cross section, obtained in 3D-CAD by four surfaces intersection [1]. Both rotations in 5 axes are considered for the tool and degree range is 0 to 30 for rotary axis A and 0 to-30 for rotary axis B (A+B-in fourth geometrical quadrant).

Abstract: In the paper, the problem of designing of mechatronic discrete systems for vibration control has been investigated and generalized. As the design method, the synthesis has been used. Main focus of the paper is given to formalization of the mechatronic structures that contains elements with negative values on different stages of the synthesis process. The study is done based on different distributions methods of dynamical characteristics, dimensionless transformation and retransformation algorithm, simultaneously with verification of possible configurations of connections of piezostack actuators with external electric networks. As the result, various classifications of mechatronic discrete systems and general design constrains have been presented and discussed.

Abstract: In this paper are presented and analyzed a series of problems that are appearing during the CFRP machining. Due to their properties, the composite materials began to replace traditional materials (ferrous and non-ferrous) in a lot of industries leading out the development of new methods of machining or adaptation of the classic. Unlike traditional material, drilling in CFRP is more difficult due to inhomogeneity of the material, its high hardness but also due to lack of knowledge relating to how these materials behave. This paper investigates different types of tool wears as corner wear, welding, crater wear that are appearing in drilling operation due to the highly abrasive nature of the carbon fibers. Also, here is presented an evaluation that refers to the machined hole quality and describe defects as delamination, pull outs, fibers projections, pyrolysis and shape errors. The main goal of this paper is to verify the current status of technique in CFRP drilling in order to develop and produce a new drill geometry in a cooperation between the Technical University of Cluj-Napoca and the cutting tool company Gühring KG.