Grinding Force Model Research Articles

Dynamic force modeling and mechanics analysis of precision grinding with microstructured wheels

The application of structured surfaces on advanced tools is an effective method for enhancing the machining performance. The modeling of dynamic grinding force is of great significance for improving tool surface structure design and improving grinding accuracy. In this paper, a novel dynamic force modeling and mechanics analysis of precision grinding with microstructured wheels was put forward. A grinding wheel topography model was established by considering the non-simplified position-posture-shape-size multiple random grains morphological characteristics. On this basis, the material removal pattern of the microstructured multiple random abrasive grains was identified based on grinding kinematics and undeformed chip thickness. The grain diameter, average bearing width, flat surface area, friction coefficient and total number of active abrasive grains in the grinding area were considered. Their effects on the amplitude and frequency of grinding force were discussed in detail, and the precision grinding experiment was carried out. The results show that the dynamic force model proposed could accurately evaluate the influence of microstructure tools on forces with an error rate of 6.7% or less. Compared with the original grinding wheel, the addition of microstructure reduces the grinding force by 49.6%− 94.3%. By controlling the force components, the force frequency is more concentrated, and the disorder of the grinding force signal is suppressed. Furthermore, the carbon emission model was calculated, and it can be seen that microstructured wheels can obviously reduce carbon emission, which is a novel processing technology to realize low-carbon manufacturing.

Ultrasonic assisted grinding force model considering anisotropy of SiCf/SiC composites

The modeling of ultrasonic assisted grinding (UAG) force for ceramic matrix composites (CMCs) is extremely complex due to the heterogeneous and anisotropic characteristics, further limiting the in-depth comprehension of the UAG mechanism of CMCs. In this paper, the grinding force prediction model of SiCf/SiC composites in UAG was proposed, which has taken into account the anisotropic and heterogeneous characteristics of SiCf/SiC composites and the interaction state of grain and material. According to the results, the multi-scale elastic mechanical model and equivalent fracture toughness proposed in this study can be well applied in the ultrasonic assisted grinding force modeling of ceramic matrix composites. And the normal and tangential grinding forces are predicted with an average error of 9.29%, 6.16%, respectively. In addition, the grinding force exhibits a significant correlation with fiber orientation. It is attributed to the fact that the fiber orientation influences the crack propagation path; meanwhile, the complex and diverse crack propagation paths make the degree of fluctuation of grinding force and the energy required for material removal varied along different fiber orientations, which consequently affects the grinding force magnitude along different fiber orientations.

An iterative blending integrating grinding force model considering grain size and dislocation density evolution

An iterative blending integrating grinding force model considering grain size and dislocation density evolution

Monitoring of ductile–brittle transition mechanisms in sapphire ultra-precision grinding used small grit size grinding wheel through force and acoustic emission signals

Progressive ultra-precision grinding experiments used small grit size grinding wheels were performed to investigate the ductile–brittle transition process of sapphire, force and AE signals were employed to monitor the material removal behavior. Precision dressing and measurement of circular arc grinding wheels were performed to meet the minimum grinding depth for ultra-precision grinding. A grinding force model was proposed to interpret the grinding forces in different materials removal modes. A continuous complete ductile–brittle transition process was observed and monitored, the progressive grinding was divided into three stages: ductile dominant, ductile–brittle transition and brittle eruption. The grinding force, surface profile, micro morphology and brittle fracture percentage were discussed. Brittle fracture will not entirely occur, but rather brittle fracture and ductile grooves were coexisted on the surface in the brittle eruption stage, which was attributed to the grinding characteristics of small grit wheels. In addition, raw AE signals and multiple transformation forms were utilized to monitor the material removal behavior and their respective roles were analyzed. The Fourier transform, discrete wavelet, continuous wavelet and wavelet coefficients in different stages can all establish a mapping relationship with material removal modes.

Study on Grinding Force of Two-Dimensional Ultrasonic Vibration Grinding 2.5D-C/SiC Composite Material

The grinding force is an important index during the grinding process, which affects the surface quality and other aspects after machining. However, the research on the grinding force of ceramic matrix composites assisted by two-dimensional ultrasonic vibration-assisted grinding is very weak. In this paper, the impact of the relationship between the critical cutting depth and the maximum undeformed chip thickness on the removal mode of ceramic matrix composites was analyzed. On this basis, the grinding force model of two-dimensional ultrasonic vibration-assisted grinding were developed for ductile removal and brittle removal, respectively. Finally, the correctness of the model was verified, and the impact of grinding parameters on the grinding force was analyzed. The experimental results show that compared with the conventional grinding force, the two-dimensional ultrasonic vibration assisted grinding force decreases obviously. When the feed rate and grinding depth increase, the grinding force increases. When the grinding velocity and ultrasonic amplitude increase, the grinding force decreases. Compared with the experimental value, the average relative error of normal grinding force is 8.49%, and the average relative error of tangential grinding force is 13.59%. The experimental and theoretical values of the grinding force have a good fitting relationship.

Mechanical Behavior of Material Removal and Predictive Force Model for CFRP Grinding Using Nano Reinforced Biological Lubricant

Mechanical Behavior of Material Removal and Predictive Force Model for CFRP Grinding Using Nano Reinforced Biological Lubricant

Grinding force model for gear profile grinding based on material removal mechanism

Grinding force model for gear profile grinding based on material removal mechanism

Analysis of grinding mechanics and improved grinding force model based on randomized grain geometric characteristics

Too high grinding force will lead to a large increase in specific grinding energy, resulting in high temperature in grinding zone, especially for the aerospace difficult cutting metal materials, seriously affecting the surface quality and accuracy. At present, the theoretical models of grinding force are mostly based on the assumption of uniform or simplified morphological characteristics of grains, which is inconsistent with the actual grains. Especially for non-engineering grinding wheel, most geometric characteristics of grains are ignored, resulting in the calculation accuracy that cannot guide practical production. Based on this, an improved grinding force model based on random grain geometric characteristics is proposed in this paper. Firstly, the surface topography model of CBN grinding wheel is established, and the effective grain determination mechanism in grinding zone is revealed. Based on the known grinding force model and mechanical behavior of interaction between grains and workpiece in different stages, the concept of grain effective action area is proposed. The variation mechanism of effective action area under the influence of grain geometric and spatial characteristics is deeply analyzed, and the calculation method under random combination of five influencing parameters is obtained. The numerical simulation is carried out to reveal the dynamic variation process of grinding force in grinding zone. In order to verify the theoretical model, the experiments of dry grinding Ti-6Al-4 V are designed. The experimental results show that under different machining parameters, the results of numerical calculation and experimental measurement are in good agreement, and the minimum error value is only 2.1 %, which indicates that the calculation accuracy of grinding force model meets the requirements and is feasible. This study will provide a theoretical basis for optimizing the wheel structure, effectively controlling the grinding force range, adjusting the grinding zone temperature and improving the workpiece machining quality in the industrial grinding process.

Study on the CBN Wheel Wear Mechanism of Longitudinal-Torsional Ultrasonic-Assisted Grinding Applied to TC4 Titanium Alloy.

In this study, the CBN (cubic boron nitride) wheel wear model of TC4 titanium alloy in longitudinal-torsional ultrasonic-assisted grinding (LTUAG) was established to explore the grinding wheel wear pattern of TC4 titanium alloy in LTUAG and to improve the grinding efficiency of TC4 titanium alloy and the grinding wheel life. The establishment of the model is based on the grinding force model, the abrasive surface temperature model, the abrasive wear model, and the adhesion wear model of TC4 titanium alloy in LTUAG. The accuracy of the built model is verified by the wheel wear test of TC4 titanium alloy in LTUAG. Research has shown that the grinding force and grinding temperature in LTUAG increase with the increase of the grinding depth and workpiece feed rate and decrease with the increase of the longitudinal ultrasonic amplitude. It also shows that the grinding force gradually decreases with the increase of the grinding wheel speed, while the grinding temperature gradually increases with the increase of the grinding wheel speed. In addition, the use of LTUAG can significantly reduce the wear rate of the grinding wheel by 25.2%. It can also effectively reduce the grinding force and grinding temperature.

Dynamic grinding force model for face gear based on the wheel-gear contact geometry

The non-uniform grinding conditions due to the wheel-gear contact geometry lead to the changeable of grinding force in face gear grinding. As a result, the classical grinding force models for other gears are not applicable to the grinding process of face gear. In this work, a dynamic grinding force model for face gear was developed based on the wheel-face gear contact geometry. In this process, surface of a virtual pinion engaged with the face gear was divided into many micro-elements to calculate the undeformed chip thickness and number of effective abrasive grains. Considering the mechanical properties of the tool and workpiece materials, equations for the total normal and tangential force components were derived by using the grinding force model of single abrasive grain. For verifying the model, the measurement coordinate system was established to convert the spatial components of experimental grinding force into the normal grinding force and tangential grinding force. Experimental results show reasonable consistency with simulation results that validate the proposed model. Besides, main reason for the changeable of grinding forces from top to root of tooth surface can be summarized by the change of material removal rate caused by the interference grinding width of adjacent grinding trajectories. Characteristics of surface morphologies and surface roughness prove this reason as well. This work provides a method to obtain a uniform grinding force during the process of grinding face gear and can be utilized to optimize the grinding process for higher tooth surface integrity.

A grinding force model in two-dimensional ultrasonic-assisted grinding of silicon carbide

Ultrasonic-assisted grinding (UAG) is a suitable machining solution for hard and brittle materials, effectively reducing cutting forces and improving the machined surface quality. With the development of UAG system, multi-dimensional vibration devices have emerged and been applied in the machining of advanced materials. In this study, a discrete numerical model is proposed for two-dimensional ultrasonic-assisted grinding (2D-UAG) of silicon carbide (SiC) to describe the dynamic cutting behaviors and a grinding force model considering the material removal mechanism is further established. In the model development, the three-dimensional surface topography of grinding wheel is simulated and adopted to determine the cutting state of individual grit. Meanwhile, a workpiece profile update procedure and a novel approach to realize the decomposition and synthesis of grinding forces are proposed. Experimental validation demonstrates that the prediction error of this proposed model is limited within 11.14% with an average value of 8.16% under conventional machining parameters. Furthermore, the tool amplitude and workpiece amplitude affect the grinding force in a similar manner. As the ultrasonic amplitude increases from 1 µm to 9 µm, the grinding force declines first and then goes up and the inflection point appears around 5 µm. The inherent characteristics of grinding forces in 2D-UAG of hard and brittle materials can be explained by obtaining the variation trends of the average cutting depth of individual grit and the number of active grains. The modeling methodology presented in this study provides a reference for studying the 2D-UAG process of brittle materials. • This model provides a reference for studying the grinding process in grit scale. • Applying two-dimensional vibration facilitates further reduction of grinding forces. • The effects of tool amplitude and workpiece amplitude are similar. • Setting the ultrasonic amplitudes to 5 µm is beneficial to reduce the grinding force.

Modelling and experiment for grinding forces of gear form grinding considering complete tooth depth engagement

Grinding is an essential gear finishing method. Grinding force analysis and prediction are critical to understand grinding mechanisms. By using a geometry model for gear form grinding and surface grinding mechanisms, a theoretical model was established to calculate the gear form grinding force. By considering the complete tooth depth engagement between tooth grooves and wheel profiles during form grinding, three segments of the involute, transition arc and tooth bottom line, which were included in complete tooth groove profiles, were analysed using the model. Contact relations among the normal grinding depth, wheel equivalent radius, wheel linear velocity and wheel profile were obtained. In addition, grinding experiments were outperformed on the basis of the single tooth, and the unknown coefficients of the form grinding force calculation model were acquired. The effects of the grinding depth, feed speed and grinding speed on grinding force were analysed using the grinding force model. The comparison of the predicted values of the form grinding force model with the experimental results, indicated that the relative errors of tangential and normal grinding forces are within ±10% and ±12%, respectively. The results confirmed the accuracy of gear form grinding force calculation model. These findings play a key role in parameter optimisation during gear form grinding.

An analytical force and energy model for ductile-brittle transition in ultra-precision grinding of brittle materials

The critical grinding depth of ductile-brittle transition is an important processing parameter to guarantee brittle materials machining in ductile mode. Nevertheless, it is a difficult task to predict the critical grinding depth considering multiple grain interactions due to the random grain distribution on the wheel. In our paper, a novel grinding force and energy model is established to predict the critical grinding depth with considering the random interactions between multiple grains, and experimental validations are carried out on single crystal silicon. In this process, the grain-workpiece interactions are explored by the actual grain protrusion heights and random grain distribution. The surface generation mechanisms of the ductile-brittle transition are comprehensively investigated by applying the numerical and experimental methods. It shows that the plastic ploughing and brittle fracture are the dominant material removal modes when grinding brittle materials. Moreover, validation experiment results indicate that the proposed model could accurately predict the realistic critical grinding depth with an average deviation of less than 9.2%. Finally, based on the proposed model, the influence of grinding conditions on the critical grinding depth are investigated in detail. The critical grinding depth increases with increasing grinding speed, while decreases with increasing feed speed. Hence, this research not only provides a new method for predicting the critical grinding depth, but also enhances the understanding of the ductile-brittle transition mechanism in brittle materials machining.

Establishment of dynamic grinding force model for ultrasonic-assisted single abrasive high-speed grinding

In the grinding process, the magnitude of the grinding force has a serious impact on the surface quality of the workpiece and the tool life. In order to explore the influence of different grinding parameters on the grinding force in the ultrasonic-assisted grinding process, this paper carried out an ultrasonic-assisted single-grain high-speed grinding experiment. First, the forms of abrasive wear were analyzed, and the reasons for the formation of different abrasive wears were discussed. The results showed that the grinding force of a single abrasive increases with the increase of abrasive wear volume. In addition, based on the condition that the abrasive particles are constantly worn over time during the machining process, a new type of dynamic grinding force model for ultrasonic-assisted high-speed grinding of single abrasive particles was established based on the relationship of abrasive wear volume changes with time. The model was verified experimentally by ultrasonic-assisted single-grain grinding of QT500-7 ductile cast iron, and the change law of single-grain grinding force with time under different parameters was explored. It was found that under the same parameters, the axial force of a single abrasive particle is always greater than the tangential force, and the grinding force increases with the increase of workpiece linear speed. The maximum error between the experimental value and the simulated value of the grinding tangential force is about 34 %, and the maximum error of the normal force is about 23 %, but the variation trend of the two with time is basically the same.

Analytical Grinding Force Model by Discretizing Stochastic Grains

Analytical Grinding Force Model by Discretizing Stochastic Grains

Experimental Analyses of the Effects of Cooling Lubricants to Expand an FEM‐Based Physical Grinding Force Model

AbstractAn FEM‐based physical force model is an important step to obtain a full understanding of the grinding process itself. Such a physical force model is already under development and is based on Abaqus‐FEM. In order to examine basic material behavior and material parameters for such a physical force model and to validate it, scratch tests have been carried out with single grains. However, the current physical force model is only designed for grinding processes that do not require cooling lubricants. Therefore, the aim of this work is to extend this physical force model in such a way that grinding processes with cooling lubricants can also be considered. In order to include the cooling lubricants in the FEM model, it is essential to carry out scratch tests with cooling lubricants in addition to the scratch tests in a dry environment. The aim is to identify basic mechanisms in connection with cooling lubricants, which are needed to expand the FEM model and to create a data basis for subsequent validation.

Force modeling for 2D freeform grinding with infinitesimal method

A universal method of grinding force modeling in arbitrary 2D freeform grinding is proposed, which is based on the infinitesimal approach. The main idea of this method is to discretize the freeform surface into a group of surfaces with very small widths along the profile of the surface cross section, which can be considered as flat surfaces inclined at different angles. The form grinding process can be considered as a series of inclined flat surface grinding, where the normal grinding force of each flat inclined surface is divided into portions along specific directions. The process of inclined flat surface grinding at certain angle is equivalently converted to flat surface grinding in terms of the same abrasive wheel peripheral velocity and workpiece velocity but different cutting depth and contacting curvature in inclined view plane. A mathematical model of grinding force in flat surface grinding (FSG) is established, where the sliding stage, plowing stage and chip formation stage are considered respectively with 9 coefficients which are determined with linear regression from the grinding experiments. The forces in form grinding are then obtained by summing the individual inclined surfaces grinding forces, which are verified via rail form grinding (RFG). The algorithm was validated by means of the grinding experiments with average relative percentage errors of 6.08% and 7.01% respectively on tangential grinding force and normal grinding force in FSG and average relative percentage errors of 8.47% and 10.37% respectively on longitudinal grinding force and vertical grinding force in RFG.

Study on passive compliance control in robotic belt grinding of nickel-based superalloy blade

To overcome the effect of fluctuation of normal grinding force on belt precision grinding of nickel-based superalloy blade with the robot, a novel passive compliance control method is proposed in this work. A passive compliance grinding device was designed to reduce the fluctuation of robotic normal grinding force, and the mechanical modeling and analysis of this device were performed. In consideration of the effect of elastic deformation of contact wheel, inherent accuracy error of robot, non-uniform allowance distribution and weak rigidity of blade, the control model of the robotic normal grinding force was established to maintain its stability. The experimental results revealed that the presented control method was beneficial to stabilize the normal grinding force in robotic grinding of nickel-based superalloy blade, and control accuracy of normal grinding force with this proposed method increased by 64.81% than that without the control method. This control method significantly improved the surface profile accuracy of nickel-based superalloy turbine blade to 0.10309 mm. Furthermore, the mathematical model of residual height based on the proposed control method was obtained to explain the relationship between residual height and machined surface roughness of concave surface and convex surface.

A novel material removal rate model based on single grain force for robotic belt grinding

Modelling of grinding force and material removal rate (MRR) has been widely investigated for wheel grinding which often has a preset cutting depth, but is rather lacking for sand belt grinding. For robotic belt grinding where the normal force often remains constant, the cutting depth of individual grain varies as the abrasive grains wear with grinding time increasing. It is, therefore, a challenge to accurately predict the tangential force and resulted MRR, and subsequently control the finish profile. This paper develops grinding force model and material removal rate model based on single grain force for robotic belt grinding. It divides the whole grinding process into three stages: initial stage, steady stage and accelerated stage, based on the degree of grain wear, analyses the grinding force of rubbing, ploughing and cutting effects and MRR at each stage. By studying the distribution of grains and penetration depth of each grain, the grinding force and MRR are calculated. Experimental work on stainless steel 304 shows that the maximum errors of the tangential force prediction is 10.9% and that of MRR is 14.4%. The proposed models not only reveal the grinding mechanism but also predict the grinding force and MRR.

Analytical modeling of grinding force and experimental study on ultrasonic-assisted forming grinding gear

This study aimed to propose an ultrasonic-assisted forming grinding (UAFG) gear processing method that would enhance the processing efficiency of traditional forming grinding (TFG) gears and reduce the surface damage of gears caused by excessive grinding force. The actual cutting arc length of the grain was deduced by analyzing the separation time of the adjacent grain of the forming wheel. This was combined with the actual cutting depth of the grain to establish the grinding force in the UAFG method. The established theoretical model could predict the grinding force. The results indicated that the grinding force of TFG was larger than that of UAFG under the same condition. In this process, the effect of each processing parameter on the grinding force was in the following sequence: ultrasonic amplitude, grinding wheel speed, grinding depth, and feed speed. The influence of the grinding force on the surface quality was examined based on the grinding force model. The results showed that UAFG helped remove the gear tooth surface material and improve grinding surface quality. The study provided a new research method to improve the machining efficiency and surface quality of the forming grinding gear.