Papers by Keyword: Grinding Wheel

Abstract: The possibility and efficiency of the use of high-density polyethylene as a binding substance in grinding wheels for cutting-off, as well as for finish cylindrical grinding, is researched. It is determined that: - breaking mechanical strength of such circles ensures their safe operation at maximum operating speeds of 30–35 m/sec; - the use of high-density polyethylene as a binding substance in cutting wheels is not advisable, due to intensive wear and low cutting power of these tools; - wheels for finish cylindrical grinding on the basis of high-density polyethylene and hollow spherocorundum as abrasive grains in a number of key indicators (cutting power, roughness of machined surfaces) are highly competitive with grinding wheels on a bakelite bond or are comparable to them, and significantly exceed the latter in terms of wear resistance.

Abstract: In this work, the experimental research was carried out on the processing of the cutting surface of a grinding wheel with a ceramic bond via continuous laser radiation with a wavelength of 10.6 μm. The influence of laser radiation power, processing speed on the depth and width of the obtained cut was investigated. A full factorial experiment was carried out with varying factors at two levels. In the form of a regression equation, a mathematical model of the effect of radiation power and processing speed on the output parameters of the process is obtained. Using Fisher's criterion, it is shown that the resulting equation adequately describes the process under the study. The analysis of the regression equation makes it possible to assess the relative influence of each factor and the effects of the interaction of factors on the depth and width of the cut on the surfaces of the grinding wheel.

Abstract: Nowadays, surface grinding is one of the most common of metal finishing methods. The efficiency of this process is affected by the so-called process parameters such as dressing feed rate (S), rough dressing depth (a_r), rough dressing times (n_r), fine dressing depth (a_f), fine dressing times (n_f), and non-feeding dressing (n_non). etc. In this paper, the optimization of dressing parameters in surface grinding SKD11 tool steel is studied. The aim of the study is to find the most appropriate value set of dressing parameters to maximize the material removal rate (MRR). In order to solve the problem, the Taguchi method is used. Based on an orthogonal array L₁₆(4⁴x2²), sixteen experiments have been conducted. By analyzing the experimental results, an optimal solution of such optimization problem has been solved, presenting the most appropriate dressing parameters as follows: a_r = 0.015 mm, n_r = 2 times, a_f = 0.005 mm, n_f = 0 times, n_non = 0 times, S = 1.6 m/min. The discovered technology mode has been applied to the real machining process and the outcome shows out a much better result in comparison with default setting modes, that the difference between the model values and the real values of the roughness average is controlled within 3.87% of the ranges.

Abstract: The composition of each grinding wheel depends on the specific application, and nowadays, there are many types of grinding wheels on the market. Bakelite bonded grinding wheels are fast becoming the standard choice for grinding and finishing processes in automotive, aerospace and other special fields of industry. Increasing requirements on higher quality and lifetime push manufacture to continuous research and development in this field. From that reason, it is necessary to characterize the structure and properties of already produced commercial grinding tools. In this contribution, two in chemical composition identical bakelite bonded grinding wheels with different properties were studied. Processing parameter like compression force is the main factor resulting in either hard grinding wheel for machining soft materials or soft grinding wheel for machining hard materials. The main components of both grinding wheels are abrasive particles of brown alumina (Al₂O₃) and two bonding agents based on synthetic rubber and bakelite. In addition, grinding wheels contain additives, e.g. vulcanization accelerators, fillers etc. to improve functional properties of grinding wheel. Fractures and metallographic samples morphology was studied by scanning electron microscopy. Porosity of grinding wheels was estimated using image analysis. Hardness of binder and abrasive brown alumina particles was measured by Rockwell hardness test.

Abstract: The high-speed grinding wheel can be defined as a self-sharpening composite structural tool composed from abrasive grains held in a specific binder. The main properties of grinding wheels depend on the type of abrasive elements, grit size, grade, binder and the resulting structure, which is influenced by several crucial technological processing steps. Preparation of an initial mixture of abrasive particles together with permanent binder’s mixture and temporary binder followed by pressing and high-temperature sintering is the essential technological step in the manufacturing of high-quality grinding wheels. High demands placed on functionality and quality together with constantly increasing effort to improve existing properties of grinding tools require detailed characterization of all input raw materials. For further research and development is crucial know, how each technological step can influence the final quality of the product. This contribution is focused on the characterization of four alumina abrasives with different grit size and two in chemical composition different binder mixtures which were used for the production of two different high-speed grinding wheels. Initial abrasive grains, binders and metallographic samples of high-speed grinding wheels were evaluated by means of scanning electron microscopy. The porosity of grinding wheels with different binding agents was also determined ustilizing digital image analysis technique.

Abstract: Geometrical characteristics of a discrete grinding wheel, which influence on a mechanical strength of the segments, formed during a high-frequency discretization of the cutting surface by highly concentrated energy flow, were defined. The analytical dependences, which establish interrelation of actual stresses in dangerous sections of a discrete grinding instrument with geometrical and mechanical characteristics of a segment, were determined. On a base of these analytical dependences a designing of a discrete grinding wheel with highly frequency discretization of a cutting surface is executed. The scientific recommendations for choice of dimensional characteristics of discrete cutting surface were proposed. Observance of these recommendations allows getting the abrasive segments with a high mechanical strength.

Abstract: The objective of this paper is to clarify the effect of grinding surface characteristics in the grinding of a titanium alloy with a coolant supply from the inner side of the grinding wheel. In this paper, we selected a white aluminum oxide (WA) vitrified bonded grinding wheel and a green silicon carbide (GC) vitrified bonded grinding wheel, and compared their grinding characteristics. As a result, in the case of the GC vitrified bonded grinding wheel, the surface roughness decreased by about 54% and the compressive residual stress increased by about 128%.

Abstract: Worm gear set is composed by the worm and worm wheel. It is an important transmission device for crossed axes transmission with high gear ratio. Worm gears can be produced in several ways, depending on the size of the transmission, the number of threads, the type of the worm and the purpose of application, etc. The contact is highly related to the precision of tooth profile. The best way to control the characteristic of contact is done by the modified worm profile. This paper deals with the manufacture of ZI-Worm whose theoretical tooth surface is generated by a screw motion of a straight line. In order to manufacture the worm with modified high precision tooth profile, the most important consideration is how to develop the profile of the grinding wheel in the worm grinding process. It is the essential requirement for the development of grinding machine for the worm. This article therefore deals with the problems of how to generate the profile of the grinding wheel. By the development of the grinding machine, we can complete the worm surface and tools for the production.

Abstract: The complex dynamics of grinding repeatedly cause critical or unstable process conditions. For a better understanding and prediction of such occurrences, the dominant excitation phenomena need to be identified and their interrelation with the system dynamics have to be analyzed.Based on measurements of the excited frequencies in several operation modes of the grinding machine, the grinding wheel rotation is identified as a major excitation source. Further analysis of the grinding wheel surface displays three main components that define the excitation frequencies of the system; these are the eccentricity, waviness and roughness (also named wheel topography). Moreover, the wheel topography and thus the excitation frequencies can change over time due to excessive wear.Following the experimental results, a grinding wheel topography and wear model are developed and included in an integrated simulation of tool grinding. The analysis of the calculated cutting forces in the frequency domain confirm the excitation due to the grinding wheel topography.Firstly, this work has extracted the grinding wheel as a prominent excitation mechanism and reproduced it with the developed grinding model. Secondly, we have evidence that a complete description of the complex grinding process is only possible when considering the interdependence between system dynamics, wheel kinematics and the grinding process.

Abstract: A new self-lubrication concept based on the techniques including of dry grinding and solid lubricating was proposed for green grinding process. And a kind of self-lubrication grinding wheel was designed with solid powder lubricant and centrifugal impeller inside. The self-lubricating was achieved by the blow out of the solid powder lubricant from the inner cavity of the wheel by the centrifugal force to the grinding surface. The experiments were conducted to study the friction and wear properties of the new cylindrical wheel samples manufactured by the proposed concept. The results showed that the flow channel diameters of 1 to 1.5 mm are the best for the blowing out of the solid lubricant to realize the continuous lubricating. After grinding, the surface coating is even, and the sizes of the abrasive particles are relatively uniform with no peeling into blocks. Although there is a certain wear loss of the grinding surface, the wear rate of the particles on the sample wheels is less than that of the traditional grinding wheel. The computational simulation of the self-lubrication wheel is conducted with the RSM method with FLUENT software to analyze the flow field in the wheel cavity of solid lubricant inside, which is meaningful for the study of the motion of the solid lubricant and useful for optimum design of the wheel design to realize the best self-lubricating performance.