Grinding Tool Research Articles

Mechanism and Experiment Study of Non-Contact Ultrasonic Assisted Grinding

Ultrasonic-assisted grinding processing can effectively reduce the surface roughness and enhance the processing efficiency in the processing of hard and brittle materials. However, the most common ultrasonic assisted grinding is a type of contact ultrasonic grinding where the grinding tool directly contacts the workpiece, which means that it is necessary to accurately control the pre-pressure of the grinding tool on the workpiece. The control of pre-pressure will inevitably increase the complexity of the grinding device, and it is easy to wear the workpiece because of improper pre-pressure control. In this paper, a non-contact ultrasonic grinding method is proposed and the machining mechanism of non-contact ultrasonic grinding is revealed. The resonant frequency of the ultrasonic vibration system and vibration amplitude of the grinding tool working face were simulated and experimentally tested, respectively. Then, the experiment of non-contact ultrasonic grinding of a sapphire wafer was carried out. The result showed that non-contact ultrasonic grinding of the sapphire wafer could reduce the surface roughness by 48.6%. Compared with traditional contact grinding of sapphire wafer under certain pre-pressure conditions, the experimental results show that non-contact ultrasonic grinding has better effects in reducing surface roughness, improving processing efficiency, and improving the quality uniformity of the workpiece machining surface.

The Prospects of Abrasive Treatment of Tough-To-Machine Materials

Abstract In current conditions, great attention is paid to the quality of parts, which is in many ways determined by finishing operations of mechanical treatment, with surface grinding being the most widespread. Grinding process efficiency, abrasive tool wear intensity, machined surface quality and other features of grinding process depend on properties of the environment, where the cutting process takes place. Forced changing of conditions of this environment is one of the ways to control and optimize the grinding process, which can be reached due to finding new technological decisions. One of the most promising directions to solve this problem is the process of face grinding with discontinuous grinding tool and supply of cooling fluid or air in the cutting zone directly. Carried analysis of features of face grinding has shown that heat density can be decreased by the usage by grooved wheels with vortex air cooling or by supply of cooling-lubricant technological fluid. Obtained dependences of temperature field of part surface during grinding establish the influence of the length of working shoulders and grooves, vortex tubes number, outflow rate, temperature and flow rate of cold vortex flow of air. These data provide conscious control over the process of discontinuous face grinding by changing wheel grain size and grinding speed.

Impregnation of Micro- and Ultradispersed Diamond Powders with Copper-Based Alloys for Grinding Tool Manufacture

Impregnation of Micro- and Ultradispersed Diamond Powders with Copper-Based Alloys for Grinding Tool Manufacture

Quick-change Double-station Stainless Steel Pot Grinding Tool for Robot

Quick-change Double-station Stainless Steel Pot Grinding Tool for Robot

Reprint of: Gentelligent processes in biologically inspired manufacturing

Production systems have to meet quality requirements despite increasing product individuality, varying batch sizes and a scarcity of resources. The transfer of experience-based knowledge in a flexible and self-optimizing production and process planning offers the potential to meet these challenges. Biological systems solve conceptually similar challenges pertaining to the transfer of knowledge, flexibility of individual reactions and adaptation over time. Thus, in the context of digital transformation, mechanisms derived from biology are interpreted and applied to the knowledge domain of production technology. To be able to exploit the potential of bio-inspired production systems, genetic and intelligent properties of technical components and machines were identified and brought together under the concept of “Gentelligence”. Expanding upon this concept with the new idea of process-DNA and biologically inspired optimization algorithms facilitates a more flexible, learning and self-optimizing production, which is shown in three different applications. By using the new concept of gentelligent process planning it is possible to determine machine-specific process parameters in turning processes in order to ensure appropriate roughness within the requirements. Furthermore, the combination of the concept with a material removal simulation allows the determination of the resulting process force in tool grinding for subsequent unknown workpiece geometries. As a result of using the process-DNA, a workpiece-independent knowledge transfer and thus process adaptation for shape error compensation becomes possible. Gentelligent production scheduling enables a process-parallel, holistically optimized machine allocation, and as a result, a significantly reduced lead time.

Highly Accurate Digital Processing of Large Stroke Guideway with an Optical Material-Corning Code 7972

Currently, meter-long guideways rarely achieve an accuracy of dozens of nanometers due to processing difficulties such as the material and the edge effect. In this paper, we focus on this problem and propose a set of optimization processing methods to cope with it. In the grinding stage, a grinding tool is designed to improve the reciprocating processing and address the problem of warping; in the polishing stage, three different processes are compared, and the combination of magnetorheological finishing technology and the polyurethane disc technology process is purposed to reduce the polishing cycle and improve the surface figure accuracy. Moreover, through the combined process of magnetorheological finishing and smoothing, the edge effect and medium- and high-frequency error are essentially suppressed. The meter-long guideway is achieved with an accuracy of dozens of nanometers. Although the sizes of surface A/C and B/D are 1000 mm × 240 mm and 1000 mm × 160 mm, the surface figures are 20.33 nm, 22.78 nm, 39.23 nm and 26.58 nm RMS (Root Mean Square), respectively. The nanometer accuracy guideway is critical to an ultra-precision machine tool. Finally, the X-axis straightness of the profile measurement system formed by the guideway reaches 200 nm/600 mm.

A compensation algorithm of tool path for grinding wheel wear in solid cutting tool flank grinding

In finishing machining, the quality of workpiece is significantly influenced by the performance of solid cutting tool. Solid cutting tool flank is ground by CNC tool grinder in accordance with the tool path of grinding wheel. In actual grinding process, the grinding area of wheel will be gradually worn down, resulting in the decrease of geometric accuracy of flank and even wrong profile. In order to compensate the error, a compensation algorithm of tool path for solid cutting tool flank based on grinding wheel wear is proposed. Firstly, the coordinate systems are defined for the grinding process of flank, and the orientation and location calculation model of ideal wheel with the grinding process parameters is derived. Secondly, based on the profile description of wheel wear, flank errors are analyzed. Then, the compensation algorithm for anastomosis of cutting edge and relief angle is proposed. Finally, series of experiments of simulation and actual grinding are carried out. The comparison of the results shows that the algorithm can reduce the influence of wheel wear effectively, which can also improve the grinding quality stability and prolong the service life of grinding wheel.

Accuracy and topography analysis of hard machined surfaces

Research on efficient machining of hardened surfaces is invariably of interest because the number of wear resistant surfaces on the machined parts is increasing. These surfaces can be machined by both single-point (cutting) and abrasive (grinding) tools. However, in designating the finishing of the parts, the working characteristics of the products that the parts are intended for limit the finishing options. In this paper the results of a comparative experiment are introduced. In the experiments the allowances were removed from the hardened surfaces of the parts by turning, grinding or a combina-tion of them. The comparative analyses were carried out for the roughness and accuracy of the ma-chined surfaces and the procedures were assessed.

ОБЕСПЕЧЕНИЕ КАЧЕСТВЕННЫХ ПОКАЗАТЕЛЕЙ ДЕТАЛЕЙ, ОБРАБОТАННЫХ ИМПРЕГНИРОВАННЫМ АБРАЗИВНЫМ ИНСТРУМЕНТОМ

The work purpose: the accuracy investigation of parts machined with chromium diiodine grinding disks, and also roughness and structural state of surface layer material in parts after working with the impregnated tool; the investigation data are a part of the scientific work which has been started since 2012. 
 The investigation methods: the accuracy and quality of machining parts with the impregnated grinding tool were analyzed; there was carried out a generalization of the data obtained regarding quality parameter changes in the surface layer of parts during working having an influence upon their operation characteristics. 
 The investigation results and novelty: the impregnation method including additional mechanical oscillation at the moment of tool impregnation; the investigation results of accuracy and effectiveness of the mentioned method of working; the investigations of roughness parameters and distribution of residual stresses in the surface layer of parts. 
 Conclusions: at present in the Russian industry there are widely used methods and technologies of import substitution, industry needs low cost and efficient methods of working; thereupon there are urgent different investigations in the field of updating technology for metal grinding with the estimate of their effectiveness and qualitative characteristics of parts when using tools offered.

A CNN Prediction Method for Belt Grinding Tool Wear in a Polishing Process Utilizing 3-Axes Force and Vibration Data

This paper presents a tool wear monitoring methodology on the abrasive belt grinding process using vibration and force signatures on a convolutional neural network (CNN). A belt tool typically has a random orientation of abrasive grains and grit size variation for coarse or fine material removal. Degradation of the belt condition is a critical phenomenon that affects the workpiece quality during grinding. This work focuses on the identifation and the study of force and vibrational signals taken from sensors along an axis or combination of axes that carry important information of the contact conditions, i.e., belt wear. Three axes of the two sensors are aligned and labelled as X-axis (parallel to the direction of the tool during the abrasive process), Y-axis (perpendicular to the direction of the tool during the abrasive process) and Z-axis (parallel to the direction of the tool during the retract movement). The grinding process was performed using a customized abrasive belt grinder attached to a multi-axis robot on a mild-steel workpiece. The vibration and force signals along three axes (X, Y and Z) were acquired for four discrete sequential belt wear conditions: brand-new, 5-min cycle time, 15-min cycle time, and worn-out. The raw signals that correspond to the sensor measurement along the different axes were used to supervisedly train a 10-Layer CNN architecture to distinguish the belt wear states. Different possible combinations within the three axes of the sensors (X, Y, Z, XY, XZ, YZ and XYZ) were fed as inputs to the CNN model to sort the axis (or combination of axes) in the order of distinct representation of the belt wear state. The CNN classification results revealed that the combination of the XZ-axes and YZ-axes of the accelerometer sensor provides more accurate predictions than other combinations, indicating that the information from the Z-axis of the accelerometer is significant compared to the other two axes. In addition, the CNN accuracy of the XY-axes combination of dynamometer outperformed that of other combinations.

Prehistoric Grinding Tools as Metaphorical Traces of the Past

The predominant interpretation of reciprocating grinding tools is generally couched in terms of low archaeological value, anonymity, simplicity, functionality and daily life of women. It is argued that biased opinions and a low form-variability have conspired to deny grinding tools all but superficial attention. Saddle-shaped grinding tools appear in the archaeological record in middle Sweden at the time of the Mesolithic — Neolithic transition. It is argued that Neolithic grinding tools are products of intentional design. Deliberate depositions in various ritual contexts reinforce the idea of grinding tools as prehistoric metaphors, with functional and symbolic meanings interlinked.

Моделирование съема припуска в зоне контакта при внутреннем шлифовании хрупких неметаллических материалов

Introduction. Finishing operations, in particular, cylindrical grinding, essentially form the quality parameters of products, its performance characteristics and functional suitability. At the same time, the cost of grinding work increases significantly in comparison with grinding metals, reaching an average of 20 ... 28% of the total cost of manufacturing products. The selection of the optimal parameters of the technological system based on the process simulation can improve the reliability, productivity and economic efficiency. To describe the processing of brittle nonmetallic materials, empirical dependences are mainly used, and the existing analytical models do not take into account the stochastic nature of the grinding operation and the combination of microcutting and brittle chipping when removing particles of brittle nonmetallic material and wear of the surface of the grinding tool. Purpose of the work: simulation of stock removal in the contact zone during internal grinding of brittle non-metallic materials. The task is to study the features and patterns of change in the probability of material removal when the treated surface comes into contact with an abrasive tool. In the work, the theoretical and probabilistic models are obtained, allowing to reveal the patterns of material removal in the contact zone. The models make it possible to trace the regularities of the interaction of cutting and piercing grains on the surface of the workpiece and the process of removing the allowance in the contact zone due to a combination of the phenomena of microcutting and brittle chipping, considered as a random event. The research methods are mathematical and physical simulation using the basic provisions of the theory of probability, the laws of distribution of random variables, as well as the theory of cutting and the theory of a deformable solid. Results and discussion. Data are obtained that provide a clear illustration of the patterns of material removal along the contact zone at various levels. Analysis of the results obtained shows that the peripheral speed of the tool and the rotation speed of the workpiece, which are directly included in the equation for calculating the probability of material removal, significantly affect the rate of material removal. The cross feed also has a significant effect on stock removal. A qualitative picture of the change in the probability of material removal in the contact zone during grinding of holes in brittle nonmetallic materials is obtained. The obtained patterns of change in the probability of material removal when the machined surface is in contact with an abrasive tool and analytical dependences are valid for a wide range of grinding modes, tool characteristics and other technological factors.

Research on a novel fabricating method of diamond grinding tool with defined grain arrangement

Grain-arranged grinding tool refers to a kind of grinding tool in which the position of abrasive grains on grinding tool can be controlled artificially. In this paper, a new method for fabrication of grain-arranged grinding tool is proposed, which is to directly coat the mask material (UV ink) on the metal substrate, and then by combining laser ablation and grain electroplating technology, the grinding tool with orderly arrangement of abrasive grains can finally be obtained. For the proposed fabrication method, the fabrication process is introduced in detail, mainly including the relationship between laser ablation parameters and the ablated mask hole depth, and the relationship between mask hole aspect ratio and the morphology of the plated layer in the mask hole. It is found that for laser ablation of UV ink, the critical laser power to remove the UV ink is 1.79 W, and the critical ablation threshold is 0.269 J/cm2. When the used laser power is 5.4–21 W, the relationship between laser power and the ablated hole depth is basically linear. For mask hole electroplating process, it is found that the unevenness of the plated layer in the mask hole and the growth rate of the plating layer increase with the decrease of the mask hole aspect ratio. By using the proposed method, grain-arranged grinding tool with 6 mm diameter, 95 μm grain size, and 150 μm grain spacing has been successfully fabricated, and its processing performance has been preliminarily validated by machining experiments.

Study of the machining quality of CMC ceramic composite during high-speed grinding

Ceramic matrix composites (CMC) are now an increasingly popular choice of materials used to manufacture critical parts for a variety of engineering applications. Due to the complex heterogeneous structure of CMC and the high hardness of at least one of the components (fiber or matrix)-processing such materials becomes an extremely difficult task. In addition, the heterogeneous structure and brittleness of CMC leads to different material removal mechanisms during machining, resulting in unique surface defects that reduce the quality of the machined surface. This article deals with the issues of ensuring the quality of the machined surface of samples made of SiC/SiC ceramic composite with ceramic matrix, by selecting the characteristics of the grinding tool and cutting modes during high-speed grinding.

An Improved Cutting Force Model for Ultrasonically Assisted Grinding of Hard and Brittle Materials

Cutting force is one of the most important factors in the ultrasonically assisted grinding (UAG) of hard and brittle materials. Many theoretical and experimental studies show that UAG can effectively reduce cutting forces. The existing models for UAG mostly assume an ideal grinding wheel with abrasives in both the end and lateral faces to accomplish material removal, whereas the important role of the transition fillet surface is ignored. In this study, a theoretical cutting force model is presented to predict cutting forces with the consideration of the diamond abrasives in the end face, the lateral face, and the transition fillet surface of the grinding tool. This study analyzed and calculated the vibration amplitudes and the cutting forces in both the normal and tangential directions. It discusses the influences of the input parameters (rotation speed, feed rate, amplitude, depth and radius of transition fillet) on cutting forces. The study demonstrates that the fillet radius is an important factor affecting the grinding force. With an increase in fillet radius from 0.2 to 1.2 mm, the grinding force increases by 139.6% in the axial direction and decreases by 70% in the feed direction. The error of the proposed cutting force model is 10.3%, and the experimental results verify the correctness of the force model.

A case study on the observability of cutting fluid flow and the associated contact mechanics in scaled rough surfaces

In grinding processes, heat is generated by the contact of the grains with the workpiece. In order to reduce damages on the workpiece and the grinding tool, cutting fluids are necessary for most grinding processes. They have the tasks of cooling and lubricating the contact zone and to remove the chips from the contact area. Different types of cutting fluids perform differently regarding these tasks, which can be investigated on a laboratory scale. However, the results of those experiments are limited to certain workpieces and processes and information about the contact mechanics are not available. The experimental investigation of contact mechanics under cutting fluid influence is hardly possible. For this reason, this paper uses a measurement strategy that uses scaled topographies and has already been successfully applied to contact mechanics problems. With such a setup, it is intended that at an early stage in the development of cutting fluids, their characteristics in terms of contact mechanics can be determined very efficiently. To demonstrate this approach, two different cutting fluids were tested with the help of the associated test rig—a water miscible emulsion and a non-water miscible grinding oil. The two fluids showed fundamentally different characteristics regarding their hydrodynamic load bearing effect, their influence on the friction behavior of the contact and their fluid flow in the gap. The properties analyzed here correspond to the practical application of cutting fluids. The results underline the potential of the presented setup for an integration into the development process of cutting fluids.

Properties of grinding tool material for double-disc straight-groove grinding method based on friction and wear experiment

The double-disc straight-groove (DDSG) grinding method is a new precision machining approach employed for the rolling surface of bearing rollers. The friction coefficient and wear resistance of grinding disc materials affect the grinding performance due to the operation on the workpiece. However, relevant research on DDSG is rather limited currently. Therefore, we analyzed the friction principles of the DDSG method and conducted friction and wear experiments to facilitate appropriate material selection for grinding discs. The optimal friction conditions for grinding disc materials were determined to ensure steady rotation of cylindrical rollers. In addition, the friction coefficients, wear resistance, and clogging resistance of various materials such as PTFE, PMMA, cast iron, brass, and fixed abrasives were measured by friction and wear experiments under grinding conditions. The friction pairs of PMMA-AISI 52100 and PTFE-AISI 52100 exhibited sliding friction coefficients of 0.14 and 0.03, respectively, along with a high grinding efficiency and excellent wear resistance. The friction pairs of both bearing steel-fixed abrasive and bearing steel-brass were easily clogged, leading to dramatic changes in the sliding friction coefficients, and neither fixed abrasive nor brass was found to be a suitable material for grinding discs. Thus, PMMA and PTFE were selected as the materials for upper and lower grinding discs. Moreover, a verification platform was built to implement the DDSG grinding method where a continuous rotation of ground roller was observed. Overall, this study provides a basis for feasible material selection and an appropriate material combination for designing a grinding machine based on DDSG.

Reinvigorating Modern Breadmaking Based on Ancient Practices and Plant Ingredients, with Implementation of a Physicochemical Approach.

In this study, the potential use of ancient plant ingredients in emerging bakery products based on possible prehistoric and/or ancient practices of grinding and breadmaking was explored. Various ancient grains, nuts and seeds (einkorn wheat, barley, acorn, lentil, poppy seeds, linseed) were ground using prehistoric grinding tool replicas. Barley-based sourdough prepared by multiple back-slopping steps was added to dough made from einkorn alone or mixed with the above ingredients (20% level) or commercial flours alone (common wheat, spelt, barley). Sieving analysis showed that 40% of the einkorn flour particles were >400 μm, whereas commercial barley and common wheat flours were finer. Differential scanning calorimetry revealed that lentil flour exhibited higher melting peak temperature and lower apparent enthalpy of starch gelatinization. Among all bread formulations tested, barley dough exhibited the highest elastic modulus and complex viscosity, as determined by dynamic rheometry; einkorn breads fortified with linseed and barley had the softest and hardest crust, respectively, as indicated by texture analysis; and common wheat gave the highest loaf-specific volume. Barley sourdough inclusion into einkorn dough did not affect the extent of starch retrogradation in the baked product. Generally, incorporation of ancient plant ingredients into contemporary bread formulations seems to be feasible.

Analysis on the removal mechanism of disc grinding based on dynamic thermal–mechanical coupling

Disc grinding is a commonly-utilized removal technology to generate the machining surface with higher precision. The material removal is caused by the force interaction between abrasives, which releases much heat during grinding. The dynamic thermal–mechanical coupling can be a crucial factor to influence the surface performance of the workpiece. However, previous studies on disc grinding are not enough for investigating the influence of the removal mechanism on the surface’s quality with dynamic thermal–mechanical coupling effect, which is caused by the double-side enclosed construction of grinding tool. To fill this gap, a novel coupled theoretical model is established based on effective abrasives dynamic removal. The moving trajectory of the discrete dynamic abrasives is deduced firstly. Meanwhile, the dynamic mechanical interaction is calculated by effective abrasives movements and height differences. Afterwards, the dynamic thermal relaxation is calculated by a finite difference method according to the effective abrasives moving trajectory and dynamic mechanical interactions, which is further validated by the finite element method. On account of the distribution of dynamic thermal–mechanical coupling, the uneven machining is found in disc grinding process. Furthermore, disc grinding experiments are performed to validate the analyzed regulations by the measurements of machining surface profile. The obtained findings are anticipated to be meaningful for improving disc grinding mechanism and optimization in wafer machining enterprises.

Thermal and technological aspects of double face grinding of C45 carbon steel

In grinding, the contact zone temperature is a decisive factor influencing the achievable surface quality and the grinding tool wear. In contrast to other grinding processes, only few information regarding double face grinding with planetary kinematics when processing steel is known up to date. Since the successive substitution of industrial double-sided lapping processes by double-sided grinding, it has become necessary to the conducted research in order to provide deeper understanding of the process and factors that influence it. To determine the workpiece temperature during grinding of C45 components, silicon temperature sensors were integrated into the workpiece holders and technological investigations were carried out. The influences and interactions of the mean cutting speed, cooling lubricant flow rate and cutting ability of the grinding wheels on the resulting workpiece temperature were analysed. Subsequently, modelling enabled an empirical estimation of the resulting workpiece temperature for processes in the investigated test area. With regard to the design and optimization of processes for machining plane-parallel workpiece surfaces, this model is a helpful tool for avoiding thermally induced workpiece damage and reduction of tool wear. Furthermore, the method can be used to conduct further examinations on the grinding process and to reduce the amount of cooling lubricant used, to improve life cycle assessment.