ABSTRACT The critical factors for the control of thermal damage in grinding at conventional works... more ABSTRACT The critical factors for the control of thermal damage in grinding at conventional workspeeds have been established with reference to experimental and previously published work. For ferrous materials, significant damage occurs above a maximum workpiece background temperature of 475°C. It is also known that the energy entering the workpiece is reduced due to conduction into the grinding wheel. It has been found that the partitioning of energy between the grinding wheel and the workpiece remains approximately constant. However, the overall partition ratio to the workpiece, which takes account of energy transfer to the chips as well as energy transfer to the wheel, is variable. The effective thermal properties of the grinding wheel may be established by correlating theory with grinding experiments. An effective coefficient for the temperature equation can be obtained corresponding to the use of the geometric contact length in the equation. Using these conclusions, a simplified approach has been developed for control of thermal damage.
A thermal model is presented for deep grinding with particular relevance to the HEDG process. HED... more A thermal model is presented for deep grinding with particular relevance to the HEDG process. HEDG is defined as deep grinding at high workspeeds and very high removal rates. The contact between the workpiece and wheel is represented as a circular surface. ...
Proceedings of the Thirty-Second International Matador Conference, 1997
Application of touch dressing provides potential benefits of stable grinding behaviour and longer... more Application of touch dressing provides potential benefits of stable grinding behaviour and longer wheel life. To utilise the touch dressing technique, detection of the initial contact between wheel and dressing tool is critical. By monitoring high frequency Acoustic Emission (AE) signals, the contact between dressing tool and wheel can be detected unaffected by environmental noise. In this paper, the problems of detecting the contact in the high frequency internal grinding machine were discussed. The main problem was that the contact AE signal was merged in the noise generated from the internal grinding wheel spindle and the dresser spindle. The coolant coupling method is one way to overcome the problem. It was demonstrated that 1 µm of contact interference can be easily detected using coolant coupling. The potential benefits gained from touch dressing are discussed. It is shown that more stable grinding performance and longer wheel life is expected using the touch dressing technique. With touch dressing, the dressing time and wheel consumption in dressing are reduced.
The selection of the most appropriate and cost effective vitrified corundum grinding wheel has, i... more The selection of the most appropriate and cost effective vitrified corundum grinding wheel has, in recent years, become increasingly complex owing to the availability of high and premium quality corundum abrasives. Developments in corundum abrasive materials have been advanced mainly by sol-gel technology and the synthesis of high purity single crystals of corundum. The development of vitrified bonding systems for these new abrasives involves a number of compromises in order to balance the requirements of grinding performance, the ability to manufacture the wheels, wheel safety, and product consistency. The selection of raw materials has a major effect on mixing quality, stability, and the ability to handle the grinding wheel in its green state and on the wheel's viscosity during vitrification heat treatment, whilst the vitrified bond tends to affect the strength, safety, and performance of the product. Traditionally, the type of abrasive selected has been matched to the workpie...
The achievement of accuracy in precision machining depends on the ability to take account of syst... more The achievement of accuracy in precision machining depends on the ability to take account of system deflection. The application of intelligent control to grinding processes is a way to achieve a desired workpiece size and surface integrity. A generic intelligent control system for grinding has been developed based and implemented on a commercially available CNC grinding machine. The implementation has been shown to be successful. The paper reviews previous work towards intelligent grinding control, summarises the previously used adaptive strategies and introduces the structure and operation of the generic intelligent system. Finally, the problems encountered during the system development are discussed.
While many bearings can be designed from very simple rules, more severe problems arise where the ... more While many bearings can be designed from very simple rules, more severe problems arise where the operating requirements involve widely varying speeds and temperature conditions. Exacting applications where hydrostatic bearings may prove of advantage are to be found in machines for primary processes, such as rolling mills and centrifugal casting machines, and in secondary processes involving high rotational speeds, such as ball mills and high-speed lathes. This paper discusses some effects and gives consideration to the consequences of various design alternatives.
Proceedings of the Fourteenth International Machine Tool Design and Research Conference, 1974
It was necessary to examine the nature of deflections in a centreless grinding machine in order t... more It was necessary to examine the nature of deflections in a centreless grinding machine in order to decide priorities in machine design. Static deflections were reported for controlled loading conditions. The results were analysed to reveal the importance of the various machine elements. Areas for design improvements arising from the investigation were suggested. Hydrostatic bearing spindles were substituted for the previous plain bearing spindles and grinding results demonstrated the improvements in sizing, roundness and reduced spark-out time. Particular attention is drawn to the importance of the dwell period for production rate and accuracy in plunge grinding operations. This Lanchester Polytechnic, Coventry
Proceedings of the Institution of Mechanical Engineers, Conference Proceedings, 1969
The diaphragm valve described is of very simple construction and may be used to control opposed p... more The diaphragm valve described is of very simple construction and may be used to control opposed pad hydrostatic bearings as an alternative to capillaries, orifices, or other types of control device. Experiments and analysis for flat pad bearings show good agreement. Data have been computed for a range of operating characteristics in a form suitable for use by designers. A reference bearing system is proposed for correcting errors in long slideways in which the reference is a diaphragm controlled hydrostatic bearing. The computed data provides information necessary to design such a system.
Coefficients are presented for hydrostatic stiffness, hydrodynamic stiffness and squeeze damping ... more Coefficients are presented for hydrostatic stiffness, hydrodynamic stiffness and squeeze damping for capillary, orifice and constant flow control. Due to the linear behaviour of such bearings these coefficients may be used for conservative design and with reasonable accuracy where the displacements are less than half the clearance. The dynamic coefficients may also be employed to predict the onset of whirl. The results are illustrated by application to rotating and non-rotating load situations. It is demonstrated that the squeeze damping constant for the concentric condition may be obtained from a steady loading test for hydrodynamic stiffness since Csq = λhd/(πN). It is argued that this relationship may be generalised for all types of bearings capable of exhibiting half-speed whirl operating at any speed.
Abstract Bearings which operate in extreme environments may incur problems due to: 1 - ambient te... more Abstract Bearings which operate in extreme environments may incur problems due to: 1 - ambient temperature rise, from cold starting to normal running; 2 - temperature difference between the control system and the bearing. Several problems and the effects of the consequent viscosity variations are discussed, and some conclusions are reached concerning the selection of the control device, design pressure ratio, and application of the optimization process. This article should help the designer to clarify the nature of a particular design problem.
Factors affecting component quality are discussed and a relationship between component cost and q... more Factors affecting component quality are discussed and a relationship between component cost and quality is given. The effect of this relationship is analysed and an optimum quality level is found to minimise total product cost, which takes account of machine reliability, machine hour rate and down-time. The parameters affecting machine reliability are reviewed and areas of machine design which require special attention are high-lighted. Dimensionless data and an optimisation procedure is presented to enable the production engineer to evaluate his particular case.
Proceedings of the Institution of Mechanical Engineers, 1970
The paper presents details of a computer solution to the problem of a rotating multi-recess exter... more The paper presents details of a computer solution to the problem of a rotating multi-recess externally pressurized bearing. It is shown that the bearing number Nη/ P8(cD/D)2correlates the results and permits the superposition of hydrodynamic and hydrostatic results for a given geometry. This significantly reduces the computer time necessary for a complete survey of results since only one solution for each of the Laplace equations and the Reynolds equation is required at any eccentricity. The problem of the control circuit is solved separately and is negligible in computer time taken in comparison with the main subroutines of the programme for finding the hydrodynamic and hydrostatic coefficients.
ABSTRACT The critical factors for the control of thermal damage in grinding at conventional works... more ABSTRACT The critical factors for the control of thermal damage in grinding at conventional workspeeds have been established with reference to experimental and previously published work. For ferrous materials, significant damage occurs above a maximum workpiece background temperature of 475°C. It is also known that the energy entering the workpiece is reduced due to conduction into the grinding wheel. It has been found that the partitioning of energy between the grinding wheel and the workpiece remains approximately constant. However, the overall partition ratio to the workpiece, which takes account of energy transfer to the chips as well as energy transfer to the wheel, is variable. The effective thermal properties of the grinding wheel may be established by correlating theory with grinding experiments. An effective coefficient for the temperature equation can be obtained corresponding to the use of the geometric contact length in the equation. Using these conclusions, a simplified approach has been developed for control of thermal damage.
A thermal model is presented for deep grinding with particular relevance to the HEDG process. HED... more A thermal model is presented for deep grinding with particular relevance to the HEDG process. HEDG is defined as deep grinding at high workspeeds and very high removal rates. The contact between the workpiece and wheel is represented as a circular surface. ...
Proceedings of the Thirty-Second International Matador Conference, 1997
Application of touch dressing provides potential benefits of stable grinding behaviour and longer... more Application of touch dressing provides potential benefits of stable grinding behaviour and longer wheel life. To utilise the touch dressing technique, detection of the initial contact between wheel and dressing tool is critical. By monitoring high frequency Acoustic Emission (AE) signals, the contact between dressing tool and wheel can be detected unaffected by environmental noise. In this paper, the problems of detecting the contact in the high frequency internal grinding machine were discussed. The main problem was that the contact AE signal was merged in the noise generated from the internal grinding wheel spindle and the dresser spindle. The coolant coupling method is one way to overcome the problem. It was demonstrated that 1 µm of contact interference can be easily detected using coolant coupling. The potential benefits gained from touch dressing are discussed. It is shown that more stable grinding performance and longer wheel life is expected using the touch dressing technique. With touch dressing, the dressing time and wheel consumption in dressing are reduced.
The selection of the most appropriate and cost effective vitrified corundum grinding wheel has, i... more The selection of the most appropriate and cost effective vitrified corundum grinding wheel has, in recent years, become increasingly complex owing to the availability of high and premium quality corundum abrasives. Developments in corundum abrasive materials have been advanced mainly by sol-gel technology and the synthesis of high purity single crystals of corundum. The development of vitrified bonding systems for these new abrasives involves a number of compromises in order to balance the requirements of grinding performance, the ability to manufacture the wheels, wheel safety, and product consistency. The selection of raw materials has a major effect on mixing quality, stability, and the ability to handle the grinding wheel in its green state and on the wheel's viscosity during vitrification heat treatment, whilst the vitrified bond tends to affect the strength, safety, and performance of the product. Traditionally, the type of abrasive selected has been matched to the workpie...
The achievement of accuracy in precision machining depends on the ability to take account of syst... more The achievement of accuracy in precision machining depends on the ability to take account of system deflection. The application of intelligent control to grinding processes is a way to achieve a desired workpiece size and surface integrity. A generic intelligent control system for grinding has been developed based and implemented on a commercially available CNC grinding machine. The implementation has been shown to be successful. The paper reviews previous work towards intelligent grinding control, summarises the previously used adaptive strategies and introduces the structure and operation of the generic intelligent system. Finally, the problems encountered during the system development are discussed.
While many bearings can be designed from very simple rules, more severe problems arise where the ... more While many bearings can be designed from very simple rules, more severe problems arise where the operating requirements involve widely varying speeds and temperature conditions. Exacting applications where hydrostatic bearings may prove of advantage are to be found in machines for primary processes, such as rolling mills and centrifugal casting machines, and in secondary processes involving high rotational speeds, such as ball mills and high-speed lathes. This paper discusses some effects and gives consideration to the consequences of various design alternatives.
Proceedings of the Fourteenth International Machine Tool Design and Research Conference, 1974
It was necessary to examine the nature of deflections in a centreless grinding machine in order t... more It was necessary to examine the nature of deflections in a centreless grinding machine in order to decide priorities in machine design. Static deflections were reported for controlled loading conditions. The results were analysed to reveal the importance of the various machine elements. Areas for design improvements arising from the investigation were suggested. Hydrostatic bearing spindles were substituted for the previous plain bearing spindles and grinding results demonstrated the improvements in sizing, roundness and reduced spark-out time. Particular attention is drawn to the importance of the dwell period for production rate and accuracy in plunge grinding operations. This Lanchester Polytechnic, Coventry
Proceedings of the Institution of Mechanical Engineers, Conference Proceedings, 1969
The diaphragm valve described is of very simple construction and may be used to control opposed p... more The diaphragm valve described is of very simple construction and may be used to control opposed pad hydrostatic bearings as an alternative to capillaries, orifices, or other types of control device. Experiments and analysis for flat pad bearings show good agreement. Data have been computed for a range of operating characteristics in a form suitable for use by designers. A reference bearing system is proposed for correcting errors in long slideways in which the reference is a diaphragm controlled hydrostatic bearing. The computed data provides information necessary to design such a system.
Coefficients are presented for hydrostatic stiffness, hydrodynamic stiffness and squeeze damping ... more Coefficients are presented for hydrostatic stiffness, hydrodynamic stiffness and squeeze damping for capillary, orifice and constant flow control. Due to the linear behaviour of such bearings these coefficients may be used for conservative design and with reasonable accuracy where the displacements are less than half the clearance. The dynamic coefficients may also be employed to predict the onset of whirl. The results are illustrated by application to rotating and non-rotating load situations. It is demonstrated that the squeeze damping constant for the concentric condition may be obtained from a steady loading test for hydrodynamic stiffness since Csq = λhd/(πN). It is argued that this relationship may be generalised for all types of bearings capable of exhibiting half-speed whirl operating at any speed.
Abstract Bearings which operate in extreme environments may incur problems due to: 1 - ambient te... more Abstract Bearings which operate in extreme environments may incur problems due to: 1 - ambient temperature rise, from cold starting to normal running; 2 - temperature difference between the control system and the bearing. Several problems and the effects of the consequent viscosity variations are discussed, and some conclusions are reached concerning the selection of the control device, design pressure ratio, and application of the optimization process. This article should help the designer to clarify the nature of a particular design problem.
Factors affecting component quality are discussed and a relationship between component cost and q... more Factors affecting component quality are discussed and a relationship between component cost and quality is given. The effect of this relationship is analysed and an optimum quality level is found to minimise total product cost, which takes account of machine reliability, machine hour rate and down-time. The parameters affecting machine reliability are reviewed and areas of machine design which require special attention are high-lighted. Dimensionless data and an optimisation procedure is presented to enable the production engineer to evaluate his particular case.
Proceedings of the Institution of Mechanical Engineers, 1970
The paper presents details of a computer solution to the problem of a rotating multi-recess exter... more The paper presents details of a computer solution to the problem of a rotating multi-recess externally pressurized bearing. It is shown that the bearing number Nη/ P8(cD/D)2correlates the results and permits the superposition of hydrodynamic and hydrostatic results for a given geometry. This significantly reduces the computer time necessary for a complete survey of results since only one solution for each of the Laplace equations and the Reynolds equation is required at any eccentricity. The problem of the control circuit is solved separately and is negligible in computer time taken in comparison with the main subroutines of the programme for finding the hydrodynamic and hydrostatic coefficients.
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Papers by W. Rowe