RPM-Synchronous Grinding: Control Concepts to Improve Surface Qualities for a Highly Efficient Non-Circular Grinding Approach

2017 ◽  
Author(s):  
Matthias Steffan ◽  
Franz Haas ◽  
Thomas Spenger
Keyword(s):  
Grain Size ◽  
Fixed Ratio ◽  
Basic Research ◽  
Force Sensor ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Wheel Wear ◽  
Process Step ◽  
Fine Grain ◽  
Grinding Machine

The RPM-Synchronous Grinding process offers new possibilities to generate defined macro- and micro-geometries on workpieces. With present technology, various macroscopic non-circular geometries must be grinded subsequently in an oscillating process where the X-axis is coupled with the rotary workpiece-spindle axis. Such workpieces can be machined in an ordinary plunge grinding process by implementing the approach of RPM-Synchronous Non-Circular Grinding. Therefore, the workpiece and the grinding wheel rotational rates are in a fixed ratio. A non-circular grinding wheel is used to transfer its geometry onto the workpiece. The authors use a unique machine tool for basic research and control concept development for RPM-Synchronous Grinding (RSG). The machine was especially designed for this RSG technology. Highest revolution rates on the workpiece spindle are mandatory for its success. The grinding approach is performed in a two-step process. For roughing, a highly porous vitrified bonded grinding wheel with medium grain size is used. It ensures high specific material removal rates for producing the non-circular geometry on the workpiece efficiently. A control algorithm adapts this process step, which uses acquired data from a piezoelectric three-component force sensor fixed at the tailstock-side of the grinding machine. For finishing, a grinding wheel with fine grain size is suited. This process step is tuned by a digital process adaption strategy. Roughing and finishing are performed consecutively among the same clamping of the workpiece with two locally separated grinding spindles. With the presented control and adaption concepts for RPM-Synchronous Grinding, a significant increase in surface quality on the workpiece is attained. The minimization of grinding wheel wear results concurrently. Especially the automotive industry shows big interest in RPM-Synchronous Non-Circular Grinding. This emerging trend in finishing machining opens up various fields of application.

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.

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.

Analysis of the Tribological Conditions in Grinding of Polycrystalline Diamond Based on Single Grain Friction Tests Using the Pin-Disk Principle

2018 ◽  
Vol 767 ◽  
pp. 259-267 ◽  
Author(s):  
Frederik Vits ◽  
Daniel Trauth ◽  
Patrick Mattfeld ◽  
Rudolf Vits ◽  
Fritz Klocke
Keyword(s):  
Contact Zone ◽  
Material Removal ◽  
Polycrystalline Diamond ◽  
Grinding Wheel ◽  
Grinding Process ◽  
State Variables ◽  
Wheel Wear ◽  
Grinding Wheel Wear ◽  
Single Grain ◽  
Zone Temperature

Cutting tools made of polycrystalline diamond (PCD) are used for machining of aluminum alloys, fiber-reinforced plastic composites and wood. Compared to cemented carbide tools with geometrically defined cutting edges, PCD tools offer significant advantages with respect to tool life. High demands regarding the cutting edge roughness and the quality of the rake and the flank face usually require a grinding process with diamond grinding wheels. The PCD grinding process, however, is characterized by low material removal rates and high grinding wheel wear. The material removal rate and the grinding wheel wear, in turn, highly depend on the process state variables process force and process temperature. However, the relationship between these process state variables and the process input variables is largely unknown. This work provides a contribution to the closure of this knowledge gap by means of an adapted friction law. A single grain friction test stand using the pin-disk principle was developed, which enables a measurement of the friction force and the contact zone temperature for normal forces and relative speeds that are common in PCD grinding. During the experiments, the specification of the PCD disc, the cross-sectional area of the friction sample made of monocrystalline diamond as well as the process parameters normal force and relative speed were varied. In addition, the tests were carried out without lubrication as well as with a minimum lubrication. A high correlation between the contact force and the coefficient of friction was determined. This relationship was mathematically formulated in a friction law. In addition, a direct influence of the contact force and the relative velocity on the contact zone temperature was identified. The knowledge gained leads to an improved understanding of the PCD grinding process and thus enables a more efficient grinding process design.

Evaluation of the Working Surface of the Grinding Wheel Using Speckle Image Analysis

2015 ◽  
Author(s):  
Arunachalam Narayanaperumal ◽  
Vijayaraghavan Lakshmanan
Keyword(s):  
Surface Quality ◽  
Surface Condition ◽  
Grinding Wheel ◽  
Optical Parameters ◽  
Wheel Surface ◽  
Wheel Wear ◽  
Speckle Image ◽  
Periodic Monitoring ◽  
Grinding Machine

The surface quality of the ground components mainly depends on the surface condition of the grinding wheel. The surface condition of the grinding wheel changes with grinding time due to wheel wear and loading. The excessive wear and loading increases the cutting force and the temperature. This in turn affects the quality of the produced component. Hence periodic monitoring of the grinding wheel surface is essential to avoid the production of the defective components. In this paper, an attempt is made to study the changes in the grinding wheel surface condition using the laser scattered images. The simple speckle imaging arrangement is fabricated and fitted into the grinding machine to capture the images of the grinding wheel after each 100 passes. The fresh wheel expected to scatter more light due to higher roughness and porosity. On the other hand, the completely glazed and worn-out wheel scatters the light less due to smoother surface. Thus, speckle image intensity distribution captures the changes in the grinding wheel surface condition. The optical parameters evaluated from the speckle images clearly indicating the changes in the grinding wheel condition. This method can be utilized to evaluate the grinding wheel condition to improve the surface quality of the component produced.

Adaptive Grinding Process—Prevention of Thermal Damage Using OPC-UA Technique and In Situ Metrology

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Matthias Steffan ◽  
Franz Haas ◽  
Alexander Pierer ◽  
Gentzen Jens
Keyword(s):  
Thermal Damage ◽  
Control Variable ◽  
Safety Margin ◽  
Value Added ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Production Chain ◽  
Process Step ◽  
Edge Zone ◽  
Control Concept

The production process grinding deals with finishing of hardened workpieces and is one of the last stages of the value-added production chain. Up to this process step, considerable costs and energy have been spent on the workpieces. In order to avoid production rejects, significant safety reserves are calculated according to the present state of the art. The authors introduce two approaches to minimize the safety margin, thus optimizing the process’ economic efficiency. Both control concepts use the feed rate override of the machining operation as regulating variable to eliminate thermal damage of the edge zone. The first control concept is developed to avoid thermal damage in cylindrical plunge grinding by controlling the cutting forces. Therefore, the industrial standard Open Platform Communications Unified Architecture (OPC-UA) is used for the communication between a proportional–integral–derivative (PID) controller and the SINUMERIK grinding machine tool control system. For noncircular workpieces, grinding conditions change over the circumference. Therefore, thermal damage cannot be ruled out at any time during the grinding process. The authors introduce a second novel control approach, which uses a micromagnetic measure that correlates with thermal damage as the main control variable. Hence, the cutting ability of the grinding wheel and thermal damage to the workpiece edge zone is quantified in the process. The result is a control concept for grinding of noncircular workpieces, which opens up fields for major efficiency enhancement. With these two approaches, grinding processes are raised on higher economic level, independently of circular and noncircular workpiece geometries.

scholarly journals Research on selection of abrasive grain size and cutting parameters when grinding of interrupted surface using aluminum oxide grinding wheel with ceramic binder

2022 ◽  
pp. 93-102
Author(s):  
Do Duc Trung ◽  
Le Dang Ha
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Aluminum Oxide ◽  
Feed Rate ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Testing Sample ◽  
Abrasive Grain ◽  
Ceramic Binder

In this article, a study on intermittent surface grinding using aluminum oxide grinding wheel with ceramic binder is presented. The testing material is 20XH3A steel (GOST standard – Russian Federation). The testing sample has been sawn 6 grooves, with the width of each groove of 10 mm, the grooves are evenly distributed on the circumference of sample. The testing sample resembles a splined shaft. An experimental matrix of nine experiments has been built by Taguchi method, in which abrasive grain size, workpiece speed, feed rate and depth of cut were selected as input variables. At each experiment, surface roughness (Ra) and roundness error (RE) have been measured. Experimental results show that the aluminum oxide and ceramic binder grinding wheels are perfectly suitable for grinding intermittent surface of 20XH3A steel. Data Envelopment Analysis based Ranking (DEAR) method has been used to solve the multi-objective optimization problem. The results also showed that in order to simultaneously ensure minimum surface roughness and RE, abrasive grain size is 80 mesh, workpiece speed is 910 rpm, feed rate is 0.05 mm/rev and depth of cut is 0.01 mm. If evaluating the grinding process through two criteria including surface roughness and RE, depth of cut is the parameter having the greatest effect on the grinding process, followed by the influence of feed rate, workpiece speed, and abrasive grain is the parameter having the least effect on the grinding process. In addition, the effect of each input parameter on each output parameter has also been analyzed, and orientations for further works have also been recommended in this article

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.

scholarly journals Análise de Sinais de Emissao Acústica e Estatística Counts na Detecção da Alteração Microestrutural na Retificação de Aço 1045

2018 ◽  
Vol 3 (1) ◽  
pp. 414
Author(s):  
Felipe Aparecido Alexandre ◽  
Martin Antonio Aulestia Viera ◽  
Pedro Oliveira Conceição Junior ◽  
Leonardo Simões ◽  
Wenderson Nascimento Lopes ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Value Added ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Frequency Bands ◽  
Finishing Process ◽  
Grinding Conditions ◽  
Grinding Machine ◽  
1045 Steel ◽  
Selection Of

Grinding is a high-precision, high-value-added finishing process as it is usually the last stage of the manufacturing chain. However, unsatisfactory results may occur, mainly due to changes in the microstructure of the ground workpiece. Such changes are caused by the high temperatures involved in the process due to the grinding conditions in which the part was subjected. In this way, the main objective of this work is the monitoring of the grinding process in order to detect changes in the signal and to relate them with damage occurred in the ground workpiece. The tests were carried out on a surface grinding machine, aluminum oxide grinding wheel and ABNT 1045 steel parts. Metallography was performed on the parts for a more further analysis of their microstructure. The recording of signals was obtained at a sample rate of 2 MHz through an acoustic emission sensor (AE). A frequency study for the selection of the best frequency bands that characterize damage occurred in the ground workpiece. The event counts statistic was applied to the filtered signal in the chosen frequency bands. The results of this work show that the grinding conditions influence the signal and, therefore, its frequency spectrum.Keywords: Manufacturing process; automation, monitoring; grinding process; acoustic emission, damage detection

Estimation of the Grinding Time by Means of the Grinding Process Model

2012 ◽  
Vol 565 ◽  
pp. 52-57 ◽  
Author(s):  
Takazo Yamada ◽  
Hwa Soo Lee ◽  
Kohichi Miura
Keyword(s):  
Process Model ◽  
The Other ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Elastic Deformations ◽  
Residual Stock ◽  
Grinding Machine ◽  
Stock Removal ◽  
Grinding Time

In grinding operation, elastic deformations of the grinding machine and the grinding wheel induce a residual stock removal of workpiece. On the other hand, thermal expansions of the workpiece and the grinding wheel increase the depth of cut. Therefore, calculation of a ground depth of cut and/or the grinding time has to be considered by the elastic deformations and the thermal expansions. From such a viewpoint, in this study, grinding process model taking into account the elastic deformations and the thermal expansions was proposed. This paper aims to estimate the grinding time by means of the proposed grinding process model.

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