In designing a conical end mill with a helical front surface, the geometry of the grinding wheel has an influence on the shape of the back profile, as this study shows. For the first time, the influence of the generix of a conical circle's angle of inclination on various interference schemes has been studied. Through the combination of laser ablation and grinding, the underpoints of the helical surface were given their final shapes, indicating the standard sizes that would affect the execution's ability to be manufactured. This work will result in the engineering of a system for automated manufacturing of conical mills, as well as the development of control programs for CNC grinding and laser ablation machines. It will also enable the development of design support for cutting tool production. The work reveals analytical dependences of the value of the clearance angle, controlled at the point of the flank surface during the transition from the radius of the cutting edge to the profile section of the helical flute in the radial section, which is set from the coordinate of a parametrically defined point along the OX axis in the radial section. It has been established that the value of the radius of curvature of the cutting edge and the point of formation of the transition of the radius to the profile can significantly change the kinematic geometry of the cutter (up to nine degrees when the radius of the cutting-edge changes by 30 μmm).
A key functional role is served by the helical surfaces of carbide end mills that can be manufactured during diamond grinding wheel. Localized changes in the form of the helical surface can be caused by abrasion, high pressure, and grinding wheel wear. Therefore, it is extremely important to measure the physical samples of products with a helical surface according to the criterion of profile accuracy, rake angle and core diameter. A specialized inspection machine in reflected light can be used to obtain images across the helical groove. Manually extracting a number of defects from photos takes time. Using defect recognition algorithms, effective and quick quality control of a ground helical surface can be established. As a result, effective surface quality control can be achieved in the machine tool industry. In this study, an innovative approach to determine a defect's shape and location as well as an algorithm for removing it are presented. Both of these approaches are integrated into the technological process used to manufacture products with helical surfaces. With the goal to recognized create suggestions for image analysis using different image levels, the suggested approach provides logically smoothing histograms and limiting contrast as an image pre-processing, based on an analysis of images with useful and faulty parts. Achieved successful extraction of areas of adhesive, diffusion, abrasion and chips from the image through post-processing. The article presents a new approach to recognizing adhesive and diffusion defects on the helical surface of a mill after grinding. When developing this approach, it was revealed that areas with alternating profile changes are most susceptible to the formation of defects under conditions of increased heating of the working area, and specialized inductors for searching for defects in localized areas according to the criterion of pixel brightness intensity were proposed.
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.
The surface grinding of the critical parts is the most important operation, which largely determines the product surface properties and its quality. In the context of automated production, efficient monitoring of this operation is a critically important task. In this work, we propose a new approach to monitoring of grinding: to simulate the processes of generating vibro-acoustic signals during grinding, to divide the working grains of the grinding wheel into sharp grains and low cutting ability ones. This division allows qualitatively predicting changes in the nature of vibro-acoustic signals accompanying grinding in different operational conditions, such as dry grinding and grinding with coolants, and the wear of the grinding wheel. The conclusions obtained based on the phenomenological modeling are confirmed by experimental studies showing that the vibration signal parameters adequately reflect the current state of the technological process and the wear of the grinding wheel. In this work, a new indicator for monitoring the grinding operation of products with high requirements to the quality of the machined surface was identified and evaluated. The proposed approach is shown to yield a more informative diagnostic indicator for finishing process compared to measurements of cutting forces, which are insufficiently efficient in the case of finishing operations with minimum allowance. The indicator was found to be efficient in the case of grinding of surfaces with roughness smaller than 0.4 μmm. The relevance of this indicator has been evaluated and proven in rigid grinding wheel-part-reference system, the use of which minimizes the probability of error.
In this paper, a new method for determining the curvature of the drill's rake surface is developed. The new method is based on the identified functional relationships between the focus area in the image and the shape of drill’s rake surface. The revealed relationships allow for the determination of the curvature of the front surface of the drill, which can be used to determine the geometric parameters of the chip flute. The method is based on the analysis of images obtained in the process of measurement by a camera in reflected light. To implement the developed method, the drill was fixed in a collet chuck on a NC measuring machine, the camera is pointed at the front surface area, and a series of images with different focal lengths was taken. After processing the images obtained in reflected light, the shape of the rake surface of the drill in the radial section was determined. The accuracy of the proposed method is proved by comparison with the data obtained from the measuring machine
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.
In this work, a new mathematical model for determining the mechanism of plunging the cutting edge of end mills with a stable passage of the cutting into the workpiece material has been developed. The new mathematical model describes the chip width as a function of the feed rate, the number of teeth and the cutter diameter. The present work shows that the theoretical value of the width of the cut layer can be used as a key parameter controlling the cutting force and as a key factor determining the plunging mechanism. A comparison of model results with experimental data has shown that modeled and experimental heights of microroughness in the stable cutting sections are in agreement within 0.05 μm that indicates the high accuracy of the developed mathematical model.
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 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.
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.
Toroidal end mills have great industrial applications and have good prospects for increasing the volume of products produced with them. It complicates the process of measuring the cutting edges by changing the position of the cutting edges along the axis, which does not allow the geometry control at the same focal length. The method proposed in the article is an effective tool for carrying out automated measurements of the shapes of cutting edges. Application of the method is relevant for edge control in automated mode. To assess the accuracy of the proposed method, it was tested on a high precision measuring machine Walter Helicheck Plus. The new method allows for repeatability of measurements down to 1.5 μm, which meets the accuracy requirements for non-profiling areas of end mills. Suggested method is universal and can significantly reduce the laboriousness of measuring multi-flute cutters. The most important advantage of this method is the ability to determine the ranges in which there is a smooth cutting edge in all areas of the cutter's cutting edge.
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.
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.
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