Applied Mechanics and Materials Vol. 657

Abstract: This paper studies the cutting force at drilling of the stainless steel X15CrNiSi20-12. The structure of the cutting force 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 force. The paper also contains graphs for the variation of the cutting force with parameters of the cutting technology. The graphs are drawn based on the analytic relationship of the cutting force, obtained in the paper, 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 another steels classes.

Abstract: The researches in the cutting domain have as purpose the cutting process economic optimization. This paper studies the cutting tool wear at drilling of the stainless steel X15CrNiSi20-12. The experimental data and their subsequent processing represent the original contribution of the authors to the estimation of polytropic exponents and to the assessment in terms of structure of the calculus relation of the cutting tool wear. The obtained relationship of the cutting tool wear on the tool putting surface at drilling of the steel X15CrNiSi20-12 permits the determination of the wear on the putting surface, in the case of a couple: stainless steel X15CrNiSi20-12 - Rp5 high-speed spiral drill, depending on the work parameters and the cutting conditions. Putting the condition of wear limitation, from the obtained relation, the cutting speeds are exactly given. The paper also contains graphs for the variation of the tool wear with parameters of the cutting technology. 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: This paper presents the design and manufacturing aspects of these tools. Constructive and geometric peculiarities are exposed for the gear hobbing cutter with large modules. The design of the gear hobbing cutter with modified profile in the parametrized variant permits a rapid adaptation to any conditions. Depending on the particular constructive geometric of the gear hobbing cutter profile it was created the virtual prototype (solid model). This is analyzed and, in the final stage, it is manufactured [1,2,3,4,] . Manufacturing techniques of the tool include the obtaining of the profiled knifes for clearance (achieved by increased 50:1 templates on the machine for profiled tools) and the special control templates (obtained on templates milling machine F. Studer) [. This paper presents the method of obtaining of the gear hobbing cutter profile by adjusting the corresponding shape of the abrasive disc to optimize the grinding conditions [. It is recomended the method which use the changing of the rack reference imposed by technical and functional conditions [7,8,.

Abstract: Magnesium alloys exhibit a very good ratio of mechanical properties versus specific weight, thus making it an important choice for parts used in automotive, aeronautic and medical industry. The distribution of residual stress in the superficial layer of the material is regarded as one of the factors defining the surface quality of a machined part. It is therefore important to know this distribution as it is closely related to fatigue and corrosion resistance, especially for the parts working in aggressive environments (i.e. biomedical devices). The present paper focuses on the determination of the residual stresses induced in a magnesium alloy part processed by milling, and their effects on surface quality.

Abstract: The study presents the contribution in engineering of surfaces particularly in surface morphology of Austenitic Stainless Steels. The objective of the investigation was to determine the surface morphology of austenitic stainless steel after turning with coated carbide tool point. The investigation included geometrical parameters of SI for different cutting parameters in dry turning process of austenitic stainless steel. The study has been performed within a production facility during the production of electric motor parts and deep-well pumps.

Abstract: The compressor rotors usually are helical surfaces with constant pitch and are composed crossing profiles. Frequently, for repair operations occurs the reconstruction necessity for one or both of the worms, drive and driven, from the helical compressors gear. The helical composed surface of rotor flank is generated usually with side mill. The knowledge of worm shape can not be made from geometrical conditions. In these conditions it is necessary to determine the flank form by actual measuring the crossing profiles of these parts. So, the theoretical helical surface of the worm is being substituted by an assembly of helical lines which together with crossing profiles forms points cloud resulted from measuring leads to a polyhedral expression of the flank rotor. Numerically, this surface type is expressed by a coordinate array which shows its discrete image. The profiling of cutting tool bounded by a revolution surface reciprocally enveloping with the substitutive surface of the helical one represents a special problem. In this paper is proposed an algorithm for polyhedral expression of the helical surface previously determined by reverse engineering methods and an algorithm for the determination of the specific enveloping condition at contact with a discrete surface.It is presented an example for a compressor rotor measured on a 3D measuring machine, the algorithm for the transformation of the gathered points cloud in a surface with polyhedral expression. Given these conditions there were determined the enveloping condition and the axial section of the side mill.

Abstract: The problem of machinability evaluation by constant force feed drilling was addressed in this paper. One of the objectives of the research presented in this paper was the decrease of the influence exerted by the presence of chips in drill channels and achieving equipment able to correspond to such a requirement. The use of value analysis method allowed identifying a solution of device able to ensure simpler conditions for materialization of test corresponding to machinability evaluation by drilling under constant force feed. One analyzed various machining schemas for achieving a drilling process. Equipment for drilling under constant force feed was designed. Essentially, a vertical feed motion up down could be achieved by the device for clamping the test piece, while the drilling tool achieves the rotation motion. The feed motion is generated under the action of some weights. One also developed a preliminary experimental research for verifying the conditions of equipment operation.

Abstract: The paper presents the results of research on the effect produced by modern cooling methods on the chip shapes and surface roughness when finish turning of ASTM A53 and AISI 1010 low carbon steels. Dry cutting, cooling by compressed air and the Minimum–Quantity–Cooling–Lubrication (MQCL) method were compared. The MQCL method is more effective for machining low carbon steel and ensures a usable chip shape and lesser surface roughness. Depending on the cutting conditions, the efficiency of the MQCL method is 10 to 30 % higher compared to dry machining. Examples of experimental investigations about reducing the use of cooling lubricant substances in turning process can be found in the open literature [1, 2].

Abstract: The paper presents the results of research on the effect produced by various cooling methods on the chip thickness ratio, shear angle and shearing force. Dry cutting, cooling by compressed air and the MinimumQuantityCoolingLubrication (MQCL) method when finish turning of carbon steel with different speeds of cutting and feed rates were compared. The investigations were performed in accordance with the Parameter Space Investigation method. The advantage of the MQCL is confirmed by lower values of the chip thickening ratio, shearing force and higher values of the shear angle. Depending on the cutting conditions, the efficiency of the MQCL method is 6 to 30% higher compared to dry machining.