The effect of dynamic behavior on surface roughness of ball screw under the grinding force (original) (raw)
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Shock and Vibration
This article presents a new model of the flat surface grinding process vibration conditions. The study establishes a particular analysis and comparison between the influence of the normal and tangential components of grinding forces on the vibration conditions of the process. The bifurcation diagrams are used to examine the process vibration conditions for the depth of cut and the cutting speed as the bifurcation parameters. The workpiece is considered to be rigid and the grinding wheel is modeled as a nonlinear two-degrees-of-freedom mass-spring-damper oscillator. To verify the model, experiments are carried out to analyze in the frequency domain the normal and tangential dynamic grinding forces. The results of the process model simulation show that the vibration condition is more affected by the normal component than the tangential component of the grinding forces. The results of the tested experimental conditions indicate that the cutting speed of 30 m/s can permit grinding at th...
The International Journal of Advanced Manufacturing Technology, 2018
In grinding, regenerative-vibration and forced-vibration due to grinding wheel eccentric rotation are main excited-vibration sources that interact with grinding material removal mechanism. In the paper, instantaneous undeformed chip thickness in down-grinding cutting phase may consist of two components, i.e. linear kinetic thickness and nonlinear dynamic thickness. Considering abrasive grit-workpiece interaction in the grinding contact zone, the grinding vibration system is presented by a new set of differential equations of two degrees of freedom (DOF) with a close-loop feedback control system models. Conventional grinding control parameters, including wheel spindle speed, work-speed in feed direction and radial cutting depth, are often regarded as linear constants in many existing simplified models. When considering time delay, they can be transferred to nonlinear variables, so the capability of prediction and the accuracy of solution of the grit-workpiece dynamics performance are improved. Based on quantitative comparison of force and vibration magnitudes, the influence of the eccentric rotation of abrasive wheel and the negative rake angle of working grit cutting edges on grinding performance are demonstrated in the paper.
Numerical and Experimental Approach for Roll Grinding Process
This paper presents a study of a vibration problem in a roll grinding machine. The rolling contact between a metal roll and the grindstone may cause the pattern formation on the roll surface during the grinding operation. A self-excited vibration excitation or so-called regenerative chatter excitation is present in the process. The chatter vibrations are described by a mathematic model including time delay effects. The numerical results of frequency responses are illustrated and they are consistent with the on-site measurements in a workshop of a roll factory.
Physical Modeling of Grinding Forces
Springer eBooks, 2023
In order to address the increasing demands on precision in manufacturing, the prediction of various processes by model-based methods is increasingly becoming a key technology. With respect to this, the grinding process still reveals a lot of potential in terms of reliable predictions. In order to exploit this potential and to improve the understanding of the process itself, a physical force model is developed. Here, process-typical influencing factors, as well as commonly used cooling lubricants, are considered. In addition to the simulative effort for the actual model, basic experimental investigations have to be carried out. In single scratch tests, it has been found that process and deformation mechanisms such as rubbing, ploughing, and cutting of the material and also the pileup of this material on both sides of the cutting grain are significantly involved in the development of forces. It also turned out that the resulting forces are greater when cooling lubricants are used and that the topographic characteristics of a scratch are also affected by them. For a realistic mapping of these effects within the force model, the deformation model, according to Johnson and Cook, and a discretization, according to Arbitrary Lagrangian-Eulerian, proved most suitable. For integrating the cooling lubricants, the Reynolds equation using a subroutine proves to be a suitable instrument. The challenge to complete the force model is combining the scratch and the Reynolds equation simulation.
Mathematical modeling of the cylindrical grinding process
Journal of Machinery Manufacture and Reliability, 2017
This paper proposes a dynamic model of cylindrical grinding with a tool owning specified distribution of abrasive grains. Cutting forces have been calculated, the surface geometry formed after a grinding wheel pass has been determined, the influence of the process dynamics on cutting forces and machined surface geometry has been taken into account, and the effects of cutting condit on vibrations being generated in the process of grinding have been investigated.
An Experimental Study on the Dynamic Behavior of Grinding Wheels in High Efficiency Deep Grinding
Procedia CIRP, 2012
The design and material of the grinding wheel hub determine its static and dynamic behaviors which, in turn, play significant roles in grinding performance. This can be of special interest in high efficiency deep grinding (HEDG) process, in which the wheel is subjected to extremely high centrifugal and grinding forces. On the other hand, controlling the dynamic behavior of the grinding wheel through an in-process monitoring and a post-process measurement seems an appropriate approach to optimize the grinding process. This paper addresses the effects of the Carbon fiber-reinforced polymer (CFRP) hub body on the grinding process efficiency through comparing the results of the experiments carried out by two CBN vitrified bonded wheels with different hub materials, CFRP and steel. The experiments were conducted using a new in-process measurement system. It was proved that the dynamic behavior of grinding wheels can affect the chip removal mechanism, and in turn, influences the finished surface roughness. Furthermore, using the CFRP as the hub material leads to a reduction in the wheel radial expansion during the operation and grinding forces. High amplitudes and frequencies have been measured when using the steel grinding wheel, while they can be damped by employing CFRP hub material.
Semi-analytical Force Model for Grinding Operations
Procedia CIRP, 2014
Grinding process is generally used to improve the tolerance integrity and surface quality of a workpiece. However, in case of some hard-to-machine materials grinding can also be a cost effective alternative even for roughing operations. It is crucial to know process forces since they are necessary to identify the conditions for surface burn which is one of the most important issues in grinding applications. In this paper, a new semi-analytical force model for grinding process is developed by modeling abrasive grits and their interaction with the workpiece individually. Grits are examined to determine their geometrical properties and distribution on the grinding wheel. Semi-analytical equations for total normal and tangential force components as well as average force per grit are established by using the micro milling analogy. Fundamental parameters such as shear stress and friction coefficient between the grits and the work material are identified. The model can then be used in prediction of the forces for different cases involving the same material and the abrasive grain however with different conditions. The model predictions are verified by several experiments and also using Johnson-Cook material model.
An analytical force and surface roughness model for cylindrical grinding of brittle materials
International Journal of Abrasive Technology, 2017
In this paper, an analytical approach is proposed for the modelling of ground surface and grinding forces in cylindrical grinding of ceramic materials. The model incorporates the near-actual distribution of cutting grains over the grinding wheel surface and a kinematic approach for the engagement of the grains with the workpiece surface per grinding parameters and conditions. To interpret the stochastic engagement of arbitrary grains with the workpiece, and to distinguish the dominant material removal mechanism, fracture mechanics of single-grain indentation is applied. The approach based on the fracture mechanics accounts for grain size and geometry and material properties. The results of a previously performed research on single-grain scratch tests are taken for interpreting force and workpiece surface characteristics. Without losing generality, the model was applied to a cylindrical plunge grinding of an alumina ceramic. The experiments show qualitative agreement of model predictions with the experimental force and ground workpiece topography.