Modern methods of control geometry parameters of cutting tools often incorporate measuring operations performed using high-precision CCD cameras which work on the contrast-detection method. The key advantages of this method are the high speed of measurements, the simplicity of using general method on modern CNC measuring systems and a wide range of possibilities for controlling profile locations of surfaces. However, using this method largely depends on the resolution of the camera's ability and the size of the controlled area, which in turn imposes significant restrictions on the measurement of surface areas which are less than 10% of the frame area. This paper proposes a new way to measure the area of profile section of microtool surfaces, based on the identifying of a focused area throughout the entire frame area. This method makes it possible to recognize the nature of the focus distribution at different camera positions, which in turn makes it possible to measure the area of profile section of microtool surfaces when the size of the controlled area is less than 10% of the frame size to use the contrast autofocus method to incomparably increase.
Surface modifying complexes with nanolayer architecture are widely used in various fields of activity (optical systems, tribological pairs, cutting tools, etc.). In many cases, brittle fracture as a result of active cracking is the key or even the dominant mechanism for the destruction of such complexes. The report discusses the factors that can slow down the development of cracks in nanolayer systems and, thus, increase their resistance to brittle fracture. Both theoretical substantiation and practical examples of crack propagation inhibition are presented. The influence of the crystalline structure of the coating on the cracking pattern has been studied. The investigation has found the significant effect of the crystalline structure of the coating layers on the cracking pattern. It can be noticed that in addition to the nanolayer structure, the pattern of crack propagation can also be affected by the crystalline structure of the coating. With a decrease in the deformation energy, the intercrystalline interfaces have a greater influence on the crack growth direction, and the crack can stop, resting against a crystal boundary. Thus, during the further modeling, it is also important to take into account the influence of the crystalline structure of the nanolayers.
Fatigue microcracks, caused by mechanical or thermal impacts, are formed during periodic stretching and compression of the upper layers of nanostructured materials. Then, the microcracks grow further and merge, leading to the cleavage of the material fragment and its subsequent destruction. In this work, we have performed calculations and transfer showing that it is necessary to structure nanomaterials in such a way as to form residual compressive stresses, which can serve as a barrier to crack propagation, in them. Here we also show that shear stresses are largely responsible for initiating the microcrack formation in nanostructured materials.
This article proposes a method for finding the focal length for determining the coordinates of the cutting edge on the toroidal section of the end producing surface, formed on the basis of the functional relationships between the parameters of the focal length and the cutting tool design parameters. Recognition of focal zones is carried out using an algorithm for analyzing the minimum transitions of color intensity in the focal zone based on a statistical analysis of differences in the levels of shades of gray in the image, which makes it possible to determine not only the focal point, but also the focusing range when measuring the edge with the original curvature determined by the radius of the cutter and the radius of the arc of the toroidal section. Experimental results, obtained on a measuring machine with a CCD matrix camera of reflected light with 400x magnification and 8: 1 telecentric optics, show that, in comparison with the existing algorithms, the new method allows increasing the recognition accuracy of the focal zone up to quality over a wide focal range. The proposed method allows for the rational search for the focal length when measuring the cutting edge that greatly reduces the number of calculations.
Rationalizing energy consumption in the Electrical Discharge Machining (EDM) efficiently saves energy and improves machining quality. Since the conventional methods for estimating useful EDM energy are based on theoretical heat transfer studies or empirical assessments of processing conditions, the development of an industrially applicable method for assessing useful energy is an important problem. Here we show that the performance of the EDM process is directly related to acoustic emission (AE). The effectiveness of the proposed method has been evaluated in experiments. As part of the execution of the experiment, AlCuMg1 workpiece was machined using a copper electrode with different duty cycles with pulse widths varying from 10% to 80%. For comparative analysis, the root-mean-square vibroacoustic signal in the range of 1-10 kHz and the root-mean-square of the discharge current were used. It was found that the amplitude of the vibroacoustic (VA) signal monotonically increases with the increasing EDM performance. The properties of the VA signal allows using the VA monitoring to assess the performance of EDM, i.e., to determine the fraction of energy spent on removing the workpiece material. The advantage of the proposed method of monitoring is that the control of useful energy is carried out using accelerometers installed on the parts of the technological system on the workpiece side. The distance from accelerometers to the workpiece being processed can be quite large that is convenient for performing experiments. In particular, in the high frequencies range, the obtained results are protected from mechanical interference coming from drives, hydraulic units and wire rewinding mechanisms. Such VA signals are shown to be important indicators of EDM efficiency because they are observed only if the energy fluxes reach the workpiece surface. This provides a more reliable indication of raising concentrations of electroerosion products that prevents short circuits and breakage of wire electrodes.
The resistibility to corrosion of biocompatible metals is significantly reduced when plastic deformation of the surface layer is more than 0.5%. To increase the successful reliability of consolidation of bone tissues is proposed to use implants made of chemically pure titanium with a nanostructured biocompatible Ti-TiN coating to improve functional properties. An increase in functional properties is provided by improving coating deposition technology in an arc discharge plasma, which does not allow the formation of any impurities. The use of a high-current diffusion discharge in a vacuum chamber forms a controlled microstructure and the morphology of the implant surface, which increases adhesion during healing. The effectiveness of the proposed coating of implants is proved by the results of comparative tests on the study of the functional properties of samples without coating, with a coating applied by traditional technology and improved technology with a high-current diffusion discharge.
The continuously growing demand for high-precision complex-shaped parts combined with limited capabilities of conventional machining methods in their production have opened up high prospects for the use of Wire Electrical Discharge Machining (WEDM). The machining of ceramic composites with WEDM is an important area of highprecision machining. However, the high electrical resistance of such composites is a big problem, due to which WEDM of poorly conducting and semi-conducting materials cannot be monitored and controlled in the same way as that of electrically conductive materials. In particular, the adaptive control of the feed rate using monitoring of electrical parameters is no longer possible after the electrical conductivity of the workpiece material decreases to the level of semiconductors. This means that the development of monitoring and control principles and instruments for WEDM of semiconductor materials is critically important. In this work, after experimentally studying the physico-mechanical nature of EDM of semiconducting materials such as ceramic composites, recommendations for selecting the control criteria based on the vibroacoustic (VA) signal were developed. VA signals of the WEDM of semiconducting composite ceramics TiC+Al2O3 were measured to develop a more reliable method of preventing short circuits and wire electrode breakage than the conventional monitoring of voltage and amperage. We show that that the developed method is more efficient in detecting short circuits than conventional monitoring scheme and can thus be used as a foundation for the development of new adaptive control schemes of WEDM of semiconductor materials.
A new approach to obtaining three-dimensional cutting edges on a tapered cutting surface is proposed based on an image obtained on a measuring machine in the control section. The method is developed based on forming a spline and evaluating the shape using a unique algorithm, which is in turn based on an analytical mathematical model. The developed method allows estimating the main geometric parameters of the cutting edge and analyzing the shape of the helical groove of the drill. In the experiments, the drill was installed on a rotary table capable of adjusting the position around its axis. The validity of the new approach was corroborated by physical tests and analysis of the set of images obtained using an optical measuring system.
The paper discusses the development and application of nanostructured surface systems for a wide range of applications. By programming the parameters of the CAA-PVD (Controled Accelerated Arc-PVD) Deposition process, it becomes possible to effectively control the performance properties of surface modifying systems and products with such systems. Modification of the surface properties of products such as cutting tools, friction pairs and medical implants provides an optimal combination of properties such as surface hardness and plasticity, high adhesion to the substrate and low adhesion to the counterbody material. The strict determinism of the process parameters allows it to be included in the automatic control system of modern manufacturing with significant energy savings and a high level of environmental safety.
The article deals with the results of the study focused on the pattern of the distribution of heat flows in the cutting wedge of a carbide tool during the turning of steel. The influence of the wear-resistant TiN, (TiAlCr)N, and (AlTiCr)N coatings on the thermal state of the tool has been investigated. The results of the mathematical modeling have been compared with the data obtained by a method that relates the temperature in the cutting wedge of the tool to the changes in the microstructure and hardness of the material (the Wright and Trent methods). The experimental studies of tool life of the tools with the coatings under study and uncoated tools were carried out during the turning of AISI 5135 steel. It has been found that a tool with the (AlTiCr)N coating has the longest tool life which may be associated with a rational distribution of heat flows in the cutting zone and the cutting wedge of the tool. The use of self-organising wear-resistant coatings reduces the level of temperatures in the cutting zone by 8-20%.
The research aims to investigate the effect of depositing nitride and Si-containing amorphous hydrogenated carbon films on the characteristics of SiAlON-based ceramics experimentally. The effect of TiN/(Ti,Al)N, (Cr,Al,Si)N and (Cr,Al,Si)N/a-C:H:Si coatings on the microrelief and surface defects of ceramics was studied. The nanohardness, plasticity, and coefficient of friction of the ceramic material at room temperature and under heating conditions after applying the mentioned coatings were quantified. Laboratory durability tests of ceramic mills with different coatings during machining a heat-resistant nickel alloy were carried out. A qualitative assessment of the nickel adherence intensity on the work surfaces of ceramic tools during cutting was performed.
This paper discusses a new complex approach and an example of its practical application to solve the problem of improving the precision ceramics products and parts operational performance (ensuring high operational stability). The proposed approach consists of forming micro-texture in a ceramic product surface layer through vacuum-plasma deposition of conductive nanocomposite coatings based on a multicomponent thermally stable nitrides Ti-Al-Cr system as an auxiliary electrode in electrical discharge machining such as forming a specific microtexture in the surface layer, e.g., a combination of cavities, grooves, etc. This approach considerably improves the ceramic product surface layer characteristics, reduces contact surfaces' "ceramic product – counter face" adhesion and friction intensity, and ensures increased wear resistance and ceramic product operability.
The research presents the principles of development and practical implementation (including rational modes) of combined treatment technology for the surface of precision parts with a broad beam of ions and/or fast argon atoms. In a single technological cycle, two process stages are realized: polishing with a beam at an incidence of 80º to the surface of parts made of different material, which enables a precision level of the surface roughness and deposition of protective nanostructured films on the parts immersed in dense plasma produced by magnetron sputtering in a mixture of inert and reactive gases. The developed innovative technology has a wide range of technological applications, but a particularly promising area is the processing of optical parts and elements.
Today, industry is accelerating the use of laser technologies. Laser technologies are one of the areas of material machining with high-energy energy flows. This actualizes monitoring of the performance of laser technologies, because it creates the preconditions for similar research in other areas. In this article, we present the results of experiments that make it possible to determine relationships between the vibroacoustic signals accompanying the action of laser pulses on a workpiece, and the intensity and duration of individual pulses. Analysis of experimental data has lead to identification of the main mechanisms of the formation of wave processes in the workpiece exposed to laser pulses and became the foundation for assessing the role of sublimation processes. The results obtained in this work can be used to develop monitoring system of laser processing for use in automated control systems.
The helical groove, which has a complex shape in the radial section, strongly affects the performance of solid ceramic mills. The accuracy of shaping is strongly affected by the size of the grinding wheel and the kinematic parameters of its movement and rotation relative to the workpiece. Although it is possible to obtain the aforementioned properties using the existing methods, there does not exist a general approach the determination the acceptable ranges of the diameter of the grinding wheel and radius of curvature of its profiling section. In this paper we have analyzed the main features of the design of the profiling sections of grinding wheels, have formed a set of initial parameters that most efficiently implement the trajectory of the shaping movement, which in turn constitutes a new general method of shaping for the helical surfaces of ceramic cutters, have analyzed the character of rolling of a set of profiling sections on a helical surface, have derived new analytical relationships determining impacts of the grinding wheel design and parameters controlling the trajectory of the grinding wheel movement on the shape of the cutter profile in the axial section, and have demonstrated advantages of the developed general approach in designing a new ceramic mill. The new method of shaping allows to unambiguously realize movements of the grinding wheel on various machine layouts and to exclude the displacement of the shaping point by replacing rotation with displacement. Further development of this method will make it possible to replace five- coordinate machines with four-coordinate ones when manufacturing milling cutters with a helical surface that can significantly reduce the production costs.
Solid ceramic mills with a toroidal cutting surface are playing an important, steadily growing role in manufacturing products made of heat-resistant materials. However, properties of these mills have a drawback such as the low strength and, hence, their design requires the absence of zones with high concentration of stresses to reduce the probability of the brittle fracture. In this paper, a new approach to the formation of the cutting edge of solid ceramic end mills has been developed. Unlike the existing approaches, which are based on the shape of the helical groove on the periphery, the new approach is based on the shape of the cutting edge on the toroidal cutting surface determining the shape of the helical surface of the cutter on the radial section. The new method allows finding ranges, in which constant angle cutting edges in the toroidal region exist, and developing multiple new designs of solid end mills with varying combinations of geometric parameters. One of the most important advantages of this method is the ability to determine the ranges, where a smooth cutting edge in all areas of the cutting part of the cutter exists. The derived analytical dependencies can be used to develop new designs of tools of a special shape with a rational combination of geometric parameters of cutting edges with accounting for the radii of the torus surface and the radius of the cutter.
Nowadays additive manufacturing becomes more and more popular. It depends on the results of last
achievements in developing of the new constructions for modern machine tools. One of the most developed AM
technology is SLM or SLS. About twenty years ago the technology of rapid prototyping started to grow up from
building prototypes and developed to real functional item production. Especially this becomes more important in
producing medical implants in the full accordance with individual digital 3D-model from metallic powder as
Ti6Al4V or CoCr. The additive technology gives the possibility to reduce additional steps in implants production
process as work preparation process, forwarding a work piece from one shop to another one, post treatment etc.
This approach is very topical to production of tooth, knee and coxal implants. This idea is realized in the
commercial SLM machines as EOS M280, SLM Solutions 125HL (Germany), Phenix systems PXS/PXM Dental
(France) (fig. 1).
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