Theoretical surface roughness of surfaces machined by single point cutting tools

In the article one possible method of theoretical surface roughness determination with help of a general mathematical model is introduced. The determination of surface roughness parameters (Ra, Rz, Rmax) was done for a given tool geometry. We also created relations between theoretical and measured values of the roughness of surfaces machined with this tool geometry.У статті представлений один з можливих методів теоретичного визначення шорсткості поверхні за допомогою математичного моделювання. Визначення параметрів шорсткості було зроблено для відомої геометрії інструмента. Також визначені зв'язки між теоретичною й вимірюваною величиною шорсткості обробленої поверхні даної геометрії інструмента

Research on coherences between the residual stresses and tool rake angle by hard turning

A broad base of researchers are concerned in studying chip removal by hard turning. The reason for that is the most of the accurate selection of the cutting conditions to be able to exploit the advantages of hard turning. Among the parameters influencing the material removal, the geometry and edge formation of the cutting tool play a decisive role too. The efficient chip removal from hardened surfaces of about 60 HRC hardness can be ensured by edge formation that can be called special. In this paper the effect of the tool rake angle on the chip removal process is investigated, within this more detailed is the effect on the residual stress formation. The main method of the investigation is the FEM simulation, with which investigations were done in a wide interval of rake angle values

The efficiency of combined machinings

This paper analyses the efficiency of the finish process applied in machining of hard surfaces, completed by grinding, hard turning and also by the combination of these two procedures, on the basis of time consumption

Material removal characteristics in rotational and tangential turning

Rotational and tangential turnings are two special variants of hard turning. They can eliminate a disadvantageous characteristic of ordinary hard turning, namely, the generation of periodical topography. This study reveals common and different features of both rotational method and the long-known tangential turning method. Common features make the complex chip removal mechanism of rotational turning easier to understand. The calculation of chip thickness and width becomes simpler. However, while the cutting technical parameters can be drawn on planar surfaces in a tangential method, these parameters obtain a 3D spatial form in rotational turning due to the helical edge. The extremely high productivity of rotational turning and the kinematical relations of the machining system are illustrated by several examples. Both methods are supplementary solutions because their extensive use requires expensive tools, which result in economic problems

Diamond grinding wheels production study with the use of the finite element method

AbstractResearch results on 3D modeling of the diamond grain and its bearing layer when sintering diamond grinding wheels are provided in this paper. The influence of the main characteristics of the wheel materials and the wheel production process, namely the quantity of metallic phase within diamond grain, coefficient of thermal expansion of the metallic phase, the modulus of elasticity of bond material and sintering temperature, on the internal stresses arising in grains is investigated. The results indicate that the stresses in the grains are higher in the areas around the metallic phase. Additionally, sintering temperature has the greatest impact on the stresses of the grain-metallic phase-bond system regardless of the type of the bond. Furthermore, by employing factorial design for the carried out finite element model, a mathematical model that reflects the impact of these factors on the deflected mode of the diamond grain-metallic phase-bond material system is obtained. The results of the analysis allow for the identification of optimal conditions for the efficient production of improved diamond grinding wheels. More specifically, the smallest stresses are observed when using the metal bond with modulus of elasticity 204GPa, the quantity of metallic phase in diamond grain of not higher than 7% and coefficient of thermal expansion of 1.32×10−51/K or lower. The results obtained from the proposed 3D model can lead to the increase in the diamond grains utilization and improve the overall efficiency of diamond grinding

The Use of the Kinetic Theory of Gases to Simulate the Physical Situations on the Surface of Autonomously Moving Parts During Multi-Energy Vibration Processing.

The multi-energy vibration processing, namely the combination of different energies or forces acting on a free abrasive medium for grinding of metal parts, is becoming more used in finishing processes, in recent years. However, the complexity that is involved in the aforementioned process requires a careful look in the particularities of the process itself in general and the movement of the abrasive media, in particular. In this paper, the nature of the collective movement of abrasive granules between the independently oscillating surfaces of the reservoir and the processed parts is described. This study presents the dissipation of the kinetic energy of the granules in a pseudo-gas from the working medium granules. The motion of the medium granules near the part surface, which is caused by pseudo-waves initiated by vibrations of the working surfaces of the vibration machine reservoir, is demonstrated. Furthermore, the nature of the motion of the granules near the oscillating part surface is described. The analysis that is presented here permits the determination of metal removal quantity from the surface of the workpiece as a result of multi-agent group action of the vibrating reservoir surface and the processed part. The optimal conditions for the finishing process can be determined based on the analysis presented

Чистовое точение закаленных деталей наружных цилиндрических поверхностей методом вращения

The accuracy of hard turning, the roughness parameters of the turned surfaces are equal to that of grinding or even better. However, the surface topography shows significant divergence. Retaining the extraordinary economic advantages of hard turning, a new version of this procedure has been developed – the rotation turning – which eliminates the deficiencies of the surface topography that cause operation disturbances.Точность обработки точением закаленных сталей и параметры шероховатости цилиндрических поверхностей равны шлифованию или даже превосходят его. Тем не менее, геометрическая форма обработанной поверхности показывает значительное расхождение. Сохраняя чрезвычайные экономические преимущества точения закаленных сталей, в новой версии был разработан метод вращения, который устраняет недостатки шероховатости поверхности, что являлось причиной нарушения операции

Применяемость водоструйной резки на различных циклах технологической обработки

Today the waterjet is unparalleled in many aspects of cutting and has changed the way of production in the case of many products. The abrasive waterjet (AWJ) may be used for flexible machine tools, capable of multiple operations including cutting, milling, turning and drilling in one setup, has been demonstrated in practice. In the following sections the alternative AWJ operations milling, turning will be discussed in more detail. Because of its excellent properties waterjet has a good chance to be applied as a cutting method.Сегодня гидроабразивная резка не имеет себе равных во многих аспектах резания и изменила технологию производства различных видов изделий. Гидроабразивная резка (AWJ) может быть использована в быстро переналаживаемых станках, рассчитанных на несколько видов обработки: фрезерование, точение и сверление за одну установку, что было продемонстрировано на практике. В последующих разделах альтернативных операции будут обсуждаться более подробно. Гидроабразивная резка имеет хорошие шансы для применения в качестве метода обработки из-за отличных характеристик