scholarly journals Applications of Contact Length Models in Grinding Processes

2009 ◽  
Vol 404 ◽  
pp. 113-122 ◽  
Author(s):  
H.S. Qi ◽  
B. Mills ◽  
Xi Peng Xu
Keyword(s):  
Contact Length ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Grinding Processes ◽  
Orthogonal Relationship ◽  
Creep Feed ◽  
Contact Behaviour ◽  
Wide Range ◽  
The Individual ◽  
Grinding Power

The nature of the contact behaviour between a grinding wheel and a workpiece in the grinding process has a great effect on the grinding temperature and the occurrence of thermal induced damage on the ground workpiece. It is found that the measured contact length le in grinding is considerably longer than the geometric contact length lg and the contact length due to wheel-workpiece deflection lf. The orthogonal relationship among the contact lengths, i.e. lc2 = (Rrlf)2 + lg2, reveals how the grinding force and grinding depth of cut affect the overall contact length between a grinding wheel and a workpiece in grinding processes. To make the orthogonal contact length model easy to use, attempts on modification of the model are carried out in the present study, in which the input variable of the model, Fn’, is replaced by a well-established empirical formula and specific grinding power. By applying the modified model in this paper, an analysis on the contributions of the individual factors, i.e. the wheel/worpiece deformation and the grinding depth of cut, on the overall grinding contact length is conducted under a wide range of grinding applications, i.e. from precise/shallow grinding to deep/creep-feed grinding. Finally, using a case study, the criterion of using geometric contact length lg to represent the real contact length lc, in terms of convenience versus accuracy, is discussed.

Effects of Grinding Parameters on Creep Feed Grinding

2013 ◽  
Vol 658 ◽  
pp. 255-258
Author(s):  
X.F. Bi
Keyword(s):  
Contact Length ◽  
Grinding Wheel ◽  
Workpiece Surface ◽  
Working Zone ◽  
Grinding Performance ◽  
Creep Feed Grinding ◽  
Grinding Parameters ◽  
Creep Feed ◽  
High Depth

Creep feed grinding can obtain an excellent grinding performance for its creep feed with high depth of cutting. However the large contact length and large feed result in large amount of heat accumulating in working zone and cause burn on workpiece surface. A series of grinding tests are performed to obtain burn variation with grinding parameters using different grinding wheel and workpiece in this paper. Grinding energy is also recorded and used to evaluate the influence of grinding parameter on burn.

Grain-Workpiece Interaction Study of Grinding Process through Single Grain Cutting Simulation

2010 ◽  
Vol 431-432 ◽  
pp. 269-272 ◽  
Author(s):  
Lan Yan ◽  
Zhi Xiong Zhou ◽  
Feng Jiang ◽  
X.K. Li ◽  
Yi Ming Rong
Keyword(s):  
Cutting Force ◽  
Removal Rate ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Micro Cutting ◽  
Wide Range ◽  
Single Grain ◽  
Workpiece Interaction

Grinding process can be considered as micro-cutting processes with the irregular abrasive grains on the surface of grinding wheel. The grain-workpiece interface directly forms the workpiece surface. Therefore, the study of the grain-workpiece interaction through micro-cutting analysis becomes necessary. But the experiments for single grain cutting are difficult to perform. Aimed at this problem, single grain cutting simulations of AISI D2 steel with a wide range of cutting parameters have been carried out with AdvantEdgeTM in this study. The effect of cutting parameters on cutting force, specific cutting force, material removal rate and critical depth of cut has been analyzed.

Control of Cutting Force for Creep-Feed Grinding Processes Using a Multi-Level Fuzzy Controller

2006 ◽  
Vol 129 (4) ◽  
pp. 480-492 ◽  
Author(s):  
Chengying Xu ◽  
Yung C. Shin
Keyword(s):  
Real Time ◽  
Grinding Force ◽  
Open Architecture ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Stable Range ◽  
Creep Feed Grinding ◽  
Creep Feed ◽  
Multi Level

In this paper, a multi-level fuzzy control (MLFC) technique is developed and implemented for a creep-feed grinding process. The grinding force is maintained at the maximum allowable level under varying depth of cut, so that the highest metal removal rate is achieved with a good workpiece surface quality. The control rules are generated heuristically without any analytical model of the grinding process. Based on the real-time force measurement, the control parameters are adapted automatically within a stable range. A National Instrument real-time control computer is implemented in an open architecture control system for the grinding machine. Experimental results show that the cycle time has been reduced by up to 25% over those without force control and by 10–20% compared with the conventional fuzzy logic controller, which indicates its effectiveness in improving the productivity of actual manufacturing processes. The effect of grinding wheel wear is also considered in the creep-feed grinding process, where the grinding force/power can be maintained around the specified value by the proposed MLFC controller as the wheel dulls gradually.

Contact length in grinding: Part 1: Contact length measurement

1997 ◽  
Vol 211 (1) ◽  
pp. 67-76 ◽  
Author(s):  
H. S. Qi ◽  
W. B. Rowe ◽  
B Mills
Keyword(s):  
Power Source ◽  
Contact Length ◽  
Measurement Methods ◽  
Grinding Wheel ◽  
Reliable Measurement ◽  
Real Contact ◽  
Contact Behaviour ◽  
Length Measurements ◽  
Three Stages ◽  
Definition Of

The nature of the contact behaviour between a grinding wheel and a workpiece in the grinding process was investigated by measurement and a model evaluation. In Part 1 of this paper measurement methods for assessment of contact length were investigated. The applied power source (APS) method was judged to give the most reliable measurement of contact length. The interpretation of contact length measurements is discussed. The contact signal can be distinguished in three stages which may correspond to the action of an active grain through the contact zone: cutting, ploughing and rubbing. The definition of contact length in grinding is discussed and it is found that it is difficult to use a single value to represent it. The measured results confirm that the measured contact length in grinding is considerably longer than the geometric contact length. There is considerable evidence that the measurements represent real contact phenomena.

Paper 40: Measurement and Control of the Residual Stress Produced by Grinding Operations

1967 ◽  
Vol 182 (11) ◽  
pp. 205-210 ◽  
Author(s):  
J. Loxham ◽  
J. Purcell
Keyword(s):  
Residual Stress ◽  
Graphical Form ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Full Explanation ◽  
The Individual ◽  
Grinding Operations ◽  
And Control ◽  
Measurement And Control ◽  
Made In

The grinding process is surveyed and a technique is described which enables the efficiency of the grinding wheel, coolant, and machine tool system to be determined. The analysis is made in terms of the maximum possible depth of cut that can be taken by the individual grits of the grinding wheel and the volume of material removed from the workpiece at this loading per unit volume of grinding wheel lost. Suggestions are made for the practical application of the technique to minimize the residual stress which is produced by the grinding operation. The results which have been achieved are shown in graphical form, and suggestions are made for the full explanation of the technique.

The Microcontact Analysis of Contact Length between Wheel and Workpiece in Precise Grinding

2010 ◽  
Vol 146-147 ◽  
pp. 1930-1936 ◽  
Author(s):  
Jeng Haur Horng ◽  
Chin Chung Wei ◽  
Yang Yuan Chen ◽  
Yuh Ping Chang
Keyword(s):  
Traditional Method ◽  
Contact Length ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Curvature Radius ◽  
Square Root ◽  
Roughness Factor ◽  
Analysis Method ◽  
Experimental Values

This paper analyzes theoretically the contact length derived from elastic-plastic mechanics and microcontact theory with the aim of improving the traditional method of predicting roughness factor though experiments. The accuracy of the analysis is verified through experiments. It transpires from the theoretical model that the contact length between a grinding wheel and a workpiece increases with decreasing curvature radius of peak, increasing hardness of the workpiece as well as increasing depth of cut. It is also revealed that the contact length is directly proportional to the square of 0.32 of the hardness, approximately, whilst the square root of surface roughness and the density of peak of the grinding wheel show less influence on the contact length. The analysis method has reduced the variation between predicted and experimental values than that of the old methods. These results will be beneficial in analysing and designing the product quality of grinding.

Prediction of lobe growth and decay in centreless grinding based on geometric considerations

2002 ◽  
Vol 216 (9) ◽  
pp. 1201-1216 ◽  
Author(s):  
A J L Harrison ◽  
T R A Pearce
Keyword(s):  
Time Domain ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Time Domain Simulation ◽  
Stability Diagrams ◽  
Wide Range ◽  
Machine Stiffness ◽  
Set Up ◽  
Intuitive Method ◽  
Rates Of Decay

The growth and decay of lobes during centreless grinding have been studied by previous researchers using physical tests, time-domain simulation and identification of the roots of the Laplace transform of the characteristic equation. In this paper, the authors have extended these latter two methods to generate complete stability diagrams encompassing the entire practical range of machine set-up angles. These diagrams indicate that by varying the set-up angles in a prescribed manner during grinding, rapid rounding of arbitrarily lobed components can be achieved. This is verified via time-domain simulation. Secondly, a novel and arguably more intuitive method of predicting the lobe growth and decay during centreless grinding is presented. The method considers the locations of the three points of contact between a lobed workpiece and the regulating wheel, the support plate and the grinding wheel. Axial symmetry is assumed. A unique circle can be drawn through these three points. The centre and radius of this circle vary continually as the workpiece rotates, in a manner dependent upon the workpiece's profile and the set-up angles. An above-average instantaneous radius leads, via machine stiffness, to a correspondingly larger grinding force and so to an increased instantaneous depth of cut. If this occurs when the trough of a lobe is being ground, the trough will become deeper and lobe growth will result. By contrast, if the instantaneous radius is below average when the trough is being ground, the lobe will decay. From this simple geometric consideration, the authors have calculated the rates of decay and growth of a range of numbers of lobes, across a wide range of set-up angles. The results are shown to agree well with those given using the previous methods.

Automatic dwell control in computer numerical control plunge grinding

1997 ◽  
Vol 211 (7) ◽  
pp. 565-575 ◽  
Author(s):  
D R Allanson ◽  
W B Rowe ◽  
X Chen ◽  
A Boyle
Keyword(s):  
Time Constant ◽  
Power Level ◽  
Accurate Estimate ◽  
Numerical Control ◽  
Power Measurement ◽  
Grinding Wheel ◽  
High Signal ◽  
Time Constants ◽  
Wide Range ◽  
The Individual

Accuracy in precision grinding is strongly affected by variations in the normal grinding force. The force gives rise to deflections of the machine, grinding wheel and workpiece. To allow relaxation of the deflection a dwell period is included at the end of the grinding cycle. Estimation of the time constant during grinding allows the automatic selection of the correct dwell time for the individual workpiece and current force level. A new strategy has been developed for the estimation of the time constant based on power measurement during dwell. The strategy employs the weighted least mean squares technique together with weightings based on classification of the power level into bands. The power bands are designed so as to employ lower weightings to be applied to power samples in the regions of the power curve most prone to causing an inaccurate estimate of the time constant. The complete system was implemented on an adaptive system comprising a PC and an Allen Bradley 8200 CNC (computer numerical controller). The time constant identification and dwell control algorithms were executed within the PC and synchronized to the grinding cycle executed under the control of the CNC. The system was successfully tested under laboratory and industrial conditions. It was shown to produce a reliable and accurate estimate of the time constant with workpieces exhibiting time constants in a range from 0.7 to 55 s. The system was shown to cope with this wide range of time constants without user intervention and to be tolerant of the high signal noise levels typically encountered in an industrial environment.

scholarly journals The Effects of Wear upon the Axial Profile of a Grinding Wheel in the Construction of Innovative Grinding Wheels for Internal Cylindrical Grinding

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
K. Nadolny ◽  
B. Słowiński
Keyword(s):  
Removal Rate ◽  
Grinding Wheel ◽  
Grinding Wheels ◽  
Cylindrical Grinding ◽  
Single Pass ◽  
Grinding Processes ◽  
Sintered Corundum ◽  
Internal Cylindrical Grinding ◽  
Axial Profile ◽  
Grinding Power

The article describes the effects of wear upon the axial profile of a grinding wheel in the axial cylindrical grinding processes. This mechanism was used to develop a grinding wheel with zone diversified structure made of microcrystalline sintered corundum abrasive grains and vitrifies bond. Such a grinding wheel is characterized by the conical rough grinding zone that is made by grains of a relatively large size, and a cylindrical finish grinding zone with grains of a smaller size and can be used in the single-pass grinding processes. Investigative tests conducted using newly-developed grinding wheels were described. Investigations were operated in the single-pass internal cylindrical grinding process of 100Cr6 steel. A comparison of results obtained using a zone diversified structure grinding wheel, with reference to a grinding wheel with grains of one size, were given. The analysis provides the roughness of the grinded surface, the grinding power, as well as chosen indicators of grinding efficiency. Experimental results obtained with use of a zone-diversified grinding wheel, built from relatively cheap grains of microcrystalline sintered corundum, showed that it is possible to obtain large material removal rate up to approximately 24 mm3/s and high quality of machined surface ( μm).

THE VALUE OF LOVE IN THE SYSTEM OF FORMATION OF THE PROFESSIONAL MATURITY OF THE EDUCATOR

2020 ◽  
Vol 1 (10(79)) ◽  
pp. 12-18
Author(s):  
G. Bubyreva
Keyword(s):  
Russian Federation ◽  
The State ◽  
Educational Process ◽  
Wide Range ◽  
The Family ◽  
The Russian Federation ◽  
The Government ◽  
The Individual ◽  
The Right

The existing legislation determines the education as "an integral and focused process of teaching and upbringing, which represents a socially important value and shall be implemented so as to meet the interests of the individual, the family, the society and the state". However, even in this part, the meaning of the notion ‘socially significant benefit is not specified and allows for a wide range of interpretation [2]. Yet the more inconcrete is the answer to the question – "who and how should determine the interests of the individual, the family and even the state?" The national doctrine of education in the Russian Federation, which determined the goals of teaching and upbringing, the ways to attain them by means of the state policy regulating the field of education, the target achievements of the development of the educational system for the period up to 2025, approved by the Decree of the Government of the Russian Federation of October 4, 2000 #751, was abrogated by the Decree of the Government of the Russian Federation of March 29, 2014 #245 [7]. The new doctrine has not been developed so far. The RAE Academician A.B. Khutorsky believes that the absence of the national doctrine of education presents a threat to national security and a violation of the right of citizens to quality education. Accordingly, the teacher has to solve the problem of achieving the harmony of interests of the individual, the family, the society and the government on their own, which, however, judging by the officially published results, is the task that exceeds the abilities of the participants of the educational process.  The particular concern about the results of the patriotic upbringing served as a basis for the legislative initiative of the RF President V. V. Putin, who introduced the project of an amendment to the Law of RF "About Education of the Russian Federation" to the State Duma in 2020, regarding the quality of patriotic upbringing [3]. Patriotism, considered by the President of RF V. V. Putin as the only possible idea to unite the nation is "THE FEELING OF LOVE OF THE MOTHERLAND" and the readiness for every sacrifice and heroic deed for the sake of the interests of your Motherland. However, the practicing educators experience shortfalls in efficient methodologies of patriotic upbringing, which should let them bring up citizens, loving their Motherland more than themselves. The article is dedicated to solution to this problem based on the Value-sense paradigm of upbringing educational dynasty of the Kurbatovs [15].

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