The Increase of the Dynamic and Static Stiffness of a Grinding Machine

2006 ◽  
Author(s):  
Marc Simnofske ◽  
Ju¨rgen Hesselbach
Keyword(s):  
Dynamic Stiffness ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Static Stiffness ◽  
Process Stability ◽  
Chatter Vibrations ◽  
Theoretical Investigations ◽  
The Stability ◽  
Grinding Machine ◽  
Chatter Marks

The dynamic stiffness of a grinding machine influences the process stability enormously. Among other things the stability of the grinding process is affected by influences like the specification of the grinding wheel, the condition of the workpiece and machine parameters. Unfavorable combinations of these lead to chatter vibrations of the machine and chatter marks on the workpiece. This paper presents the results of experimental and theoretical investigations of the vibration behavior of a grinding machine and the design of active modules. These modules will be implemented in the structure of the machine to minimize the vibrations and additionally increase its static stiffness of the machine.

Active Vibration Reduction to Optimize the Grinding Process

2009 ◽  
Author(s):  
Alexander L. Boldering ◽  
Marc Simnofske ◽  
Annika Raatz ◽  
Ju¨rgen Hesselbach
Keyword(s):  
Dynamic Stiffness ◽  
Production Quality ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Active Vibration ◽  
Efficient Machine ◽  
High Production ◽  
Basic Approaches ◽  
The Stability ◽  
Grinding Machine

High production quality and processing velocity characterizes an efficient machine tool. Higher velocities lead to increasing process forces, hence the stiffness of the machine must be high. Especially in grinding, the dynamic stiffness of a machine influences the process stability enormously. The stability of the grinding process is affected by the specification of the grinding wheel, machine parameters and the condition of the workpiece. Chattering is simply a consequence of vibration within a grinding system. At present, parts of the machine tools (structures, drives, measuring systems, etc.) are constantly being improved. However, a better performance can only be achieved by applying innovative basic approaches. In this paper, a grinding machine with integrated active modules is presented. The aim of the modules, which consist of piezo actuators and force transducers, is to increase the static and dynamic stiffness of the structure and minimize vibrations.

scholarly journals A dynamic model of cylindrical plunge grinding process for chatter phenomena investigation

2018 ◽  
Vol 148 ◽  
pp. 09004
Author(s):  
Paweł Lajmert ◽  
Małgorzata Sikora ◽  
Dariusz Ostrowski
Keyword(s):  
Degrees Of Freedom ◽  
Stability Limit ◽  
Element Model ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Plunge Grinding ◽  
Chatter Vibrations ◽  
Grinding Conditions ◽  
The Stability ◽  
Improved Model

In the paper, chatter vibrations in the cylindrical plunge grinding process are investigated. An improved model of the grinding process was developed which is able to simulate self-excited vibrations due to a regenerative effect on the workpiece and the grinding wheel surface. The model includes a finite-element model of the workpiece, two degrees of freedom model of the grinding wheel headstock and a model of wheel-workpiece geometrical interferences. The model allows to studying the influence of different factors, i.e. workpiece and machine parameters as well as grinding conditions on the stability limit and a chatter vibration growth rate. At the end, simulation results are shown and compared with exemplified real grinding results.

Nonlinear Stability and Bifurcation of Multi-D.O.F. Chatter System in Grinding Process

2006 ◽  
Vol 304-305 ◽  
pp. 141-145 ◽  
Author(s):  
Qing Kai Han ◽  
Tao Yu ◽  
Zhi Wei Zhang ◽  
Bang Chun Wen
Keyword(s):  
Dynamic Properties ◽  
Grinding Wheel ◽  
Dimensional System ◽  
Grinding Process ◽  
Center Manifold Theorem ◽  
Stability And Bifurcation ◽  
The Stability ◽  
Grinding Machine ◽  
Low Dimensional ◽  
Theoretical Analyses

The nonlinear chatter in grinding machine system is discussed analytically in the paper. In higher speed grinding process, the self-excited chatter vibration is mostly induced by the change of grinding speed and grinding wheel shape. Here the grinding machine tool is viewed as a nonlinear multi-D.O.F. autonomous system, in which hysteretic factors of contact surfaces are also introduced. Firstly, the DOFs of the above system are reduced efficiently without changing its dynamic properties by utilizing the center manifold theorem and averaging method. Then, a low dimensional system and corresponding averaging equations are obtained. The stability and bifurcation of chatter system are discussed on the base of deduced averaging equations. It is proved that chatter occurs as a Hopf bifurcation emerging from the steady state at the origin of system. The theoretical analyses on the multi-DOF chattering system will lead to further understanding of the nonlinear mechanisms of higher speed grinding processes.

Stability Analysis of a Transverse Cylindrical Grinding Process

2012 ◽  
Vol 479-481 ◽  
pp. 1190-1193
Author(s):  
Yao Yan ◽  
Jian Xu
Keyword(s):  
Stability Analysis ◽  
Grinding Wheel ◽  
Force Model ◽  
Grinding Process ◽  
Key Factors ◽  
Mass System ◽  
Cylindrical Grinding ◽  
Chatter Vibrations ◽  
The Stability ◽  
Euler Bernoulli Beam

The stability of a transverse cylindrical grinding process is investigated in this paper. The workpiece is considered as a rotating damped hinged-hinged Euler-Bernoulli beam and the grinding wheel a rotating damped spring mass system moving along the workpiece. Called regenerative force, the contact force between the workpiece and the wheel is a functional equation related to both the current and previous relative positions between the workpiece and the wheel since the regeneration exists on the surfaces of both the workpiece and the wheel. The two distinct time delays presented in the regenerative force model are inversely proportional to the rotation speeds of the workpiece and the wheel respectively. For grinding stability analysis, the regenerative effects are considered as the key factors in inducing chatter vibrations in the grinding process. The grinding stability is numerically analyzed since two distinct delays being involved in the model makes the analytical analysis extremely difficult. Finally, the grinding stability analysis is verified by numerical simulation.

Calculation of Effective Ground Depth of Cut by Means of Grinding Process Model

2011 ◽  
Vol 496 ◽  
pp. 7-12 ◽  
Author(s):  
Takazo Yamada ◽  
Michael N. Morgan ◽  
Hwa Soo Lee ◽  
Kohichi Miura
Keyword(s):  
Process Model ◽  
Ground Surface ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Wheel Wear ◽  
Elastic Deformations ◽  
Proposed Model ◽  
Effective Depth ◽  
Grinding Machine

In order to obtain the effective depth of cut on the ground surface, a new grinding process model taking into account thermal expansions of the grinding wheel and the workpiece, elastic deformations of the grinding machine, the grinding wheel and the workpiece and the wheel wear was proposed. Using proposed model, the effective depth of cut was calculated using measured results of the applied depth of cut and the normal grinding force.

scholarly journals Grinding of AISI 4340 steel with interrupted cutting by aluminum oxide grinding wheel

2015 ◽  
Vol 68 (2) ◽  
pp. 229-238
Author(s):  
Hamilton Jose de Mello ◽  
Diego Rafael de Mello ◽  
Eduardo Carlos Bianchi ◽  
Paulo Roberto de Aguiar ◽  
Doriana M. D'Addona
Keyword(s):  
Aluminum Oxide ◽  
Rotation Speed ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Wheel Wear ◽  
Machined Surface ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Grinding Machine ◽  
Aisi 4340

AbstractThere has been a great advance in the grinding process by the development of dressing, lubri-refrigeration and other methods. Nevertheless, all of these advances were gained only for continuous cutting; in other words, the ground workpiece profile remains unchanged. Hence, it becomes necessary to study grinding process using intermittent cutting (grooved workpiece – discontinuous cutting), as little or no knowledge and studies have been developed for this purpose, since there is nothing found in formal literature, except for grooved grinding wheels. During the grinding process, heat generated in the cutting zone is extremely high. Therefore, plenty of cutting fluids are essential to cool not only the workpiece but also the grinding wheel, improving the grinding process. In this paper, grinding trials were performed using a conventional aluminum oxide grinding wheel, testing samples made of AISI 4340 steel quenched and tempered with 2, 6, and 12 grooves. The cylindrical plunge grinding was performed by rotating the workpiece on the grinding wheel. This plunge movement was made at three different speeds. From the obtained results, it can be observed that roughness tended to increase for testing sample with the same number of grooves, as rotation speed increased. Roundness error also tended to increase as the speed rotation process got higher for testing the sample with the same number of grooves. Grinding wheel wear enhanced as rotation speed and number of grooves increased. Power consumed by the grinding machine was inversely proportional to the number of grooves. Subsuperficial microhardness had no significant change. Micrographs reveal an optimal machining operation as there was no significant damage on the machined surface.

Nonlinearity Analysis and Wavelet Package Transform of Measured Chatter Vibrations in Grinding Process

2007 ◽  
Vol 359-360 ◽  
pp. 494-498 ◽  
Author(s):  
Qing Kai Han ◽  
Bang Chun Wen
Keyword(s):  
Fractal Dimensions ◽  
Numerical Control ◽  
Grinding Process ◽  
Frequency Spectra ◽  
Frequency Bands ◽  
Special Alloy ◽  
Chatter Vibrations ◽  
Scaled Energy ◽  
Grinding Machine ◽  
Nc Grinding

In grinding process, chatter vibrations known as self-excited vibrations, become increasingly problematic and must be avoided. Firstly, experimental measurements of chatter vibrations in a numerical control (NC) grinding machine tool are introduced for the case of a special alloy workpiece being carried on. Then, frequency spectra of chatter vibrations are analyzed. The wavelet package transform technique is used to describe original chatter signals in the term of scaled energy of frequency bands. At last, fractal dimensions of the reconstructed signals in consecutive frequency bands of chatter vibrations are calculated. These results are helpful for understanding of the nonlinearity of chatter vibrations.

Study on the Grinding Process of Ceramic Zirconia Oxide Rod

2014 ◽  
Vol 575 ◽  
pp. 121-127
Author(s):  
Shinn Liang Chang ◽  
Dai Jia Juan ◽  
Bean Yin Lee ◽  
You Jhih Lin
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Rotation Speed ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Hard Machining ◽  
Grinding Machine ◽  
Diamond Grain ◽  
Zirconia Oxide

Grinding technology is used in this study to overcome the hard machining of ceramic with hard and brittle characteristics. The grinding machine with diamond grain size 25 and 5 , spindles speed 1720 rpm and 3450 rpm are applied. Combining the unintentional roll clamp and the grinding machine, ceramic rods can be ground to the desired size.In the research, surface profilometer is applied to measure the rod surface roughness of processing results under different conditions. The results show that the grinding wheel with finer particle, the roughness of the ground ceramic rod will be better. While the rotation speed of grinding wheel is increased, the surface roughness will have the same trend.

Suppression of Regenerative Chatter in a Plunge-Grinding Process by Spindle Speed

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Yao Yan ◽  
Jian Xu
Keyword(s):  
Control Strategy ◽  
Spindle Speed ◽  
Effective Control ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Regenerative Chatter ◽  
Plunge Grinding ◽  
Dynamical Interaction ◽  
Chatter Vibrations ◽  
Free Region

This paper utilizes an effective control strategy to suppress the regenerative chatter in a plunge-grinding process. To begin with, the dynamical interaction between the workpiece and the grinding wheel is considered as a major factor influencing the grinding stability. Mathematically, the grinding stability is studied through numerical eigenvalue analysis. Consequently, critical chatter boundaries are obtained to distinguish the chatter-free and the chatter regions. As known, the grinding is unstable and the chatter happens in the chatter region. To observe the chatter vibrations, an analytical method and numerical simulations are employed. As a result, chatter vibrations both with and without losing contact between the workpiece and the wheel are obtained. Meanwhile, the coexistence of the chatter and the stable grinding is also found in the chatter-free region. Finally, a control strategy involving spindle speed variation (SSV) is introduced to suppress the chatter. Then, its effectiveness is analytically investigated in terms of the method of multiple scales (MMS).

Grinding Process Instability

1969 ◽  
Vol 91 (3) ◽  
pp. 597-606 ◽  
Author(s):  
B. Bartalucci ◽  
G. G. Lisini
Keyword(s):  
Closed Loop ◽  
Experimental Tests ◽  
Grinding Wheel ◽  
Closed Loop System ◽  
Regenerative Effect ◽  
Machine Tool Structure ◽  
Chatter Vibrations ◽  
Grinding Machine ◽  
Theoretical Results ◽  
Good Agreement

The paper describes a theoretical investigation on chatter vibrations of cylindrical plunge grinding. The system grinding machine-grinding wheel-workpiece is represented as a closed loop system with two feedback paths, one due to the machine tool structure, the other to the regenerative effect of the grinding wheel. Theoretical results are in good agreement with the experimental tests.

Sign in / Sign up

Export Citation Format

Share Document