D. R. Allanson

The effects of cutting fluid application methods on the grinding process

It is well known that a boundary layer of air is entrained around a rotating grinding wheel. The effects of the boundary layer have been under some scrutiny in recent years with most research being based on trying to overcome the boundary layer. The current investigation aims to show through experiment and modelling, the effects of the boundary layer on cutting fluid application and how it can be used to aid delivery by increasing flow rate beneath the wheel. Results from three experiments with different quantities of cutting fluid passing through the grinding zone are presented.

Analysis and simulation of the grinding process. Part IV: Effects of wheel wear

A method of simulating dressing and grinding was described in Parts I and II of this paper. In Part IV, the effects of wheel wear and wheel characteristics on grinding performance are simulated and compared with experimental results. The results show that grinding performance is strongly affected by dressing conditions immediately after dressing. As grinding continues, the grinding power, and also the surface roughness, tends to converge towards similar values for all dressing conditions when the same grinding conditions are employed. Results from the simulation show that the influence of wheel wear is affected by the wheel fracture characteristics. The convergence of the grinding behaviour shown in the simulation and experiments suggests that stable grinding performance in a wheel redress life cycle may be achieved by selecting dressing conditions, taking account of the grinding behaviour.

Film pressure distribution in water-lubricated rubber journal bearings

Abstract Measurements of fluid film pressures were made on water-lubricated rubber journal bearings. The measurements indicated that the film pressure profiles are very different from those of conventional rigid bearings. The relatively low film pressures caused significant rubber deflections but were too low to produce lubricant viscosity changes. Integration of the pressure in the bearings showed that they operate in the regime of mixed lubrication. The behaviour of the bearings was theoretically investigated using computational fluid dynamics. There was reasonable agreement between computational fluid dynamics and experimental results.

Analysis and simulation of the grinding process. Part III: Comparison with experiment

A method of simulating dressing and grinding was described in Parts I and II of this three-part series. In Part III, the effects on grinding performance of varying the dressing conditions are simulated and compared with experimental results. The results show that a coarse dressing condition leads to low grinding force and grinding power but a high workpiece surface roughness. The grinding performance of the wheel in the dwell period for “spark-out” is simulated. Simulated and experimental results both show that grinding power in the dwell period decreases following an exponential decay function, however the reduction of surface roughness does not follow an exponential decay.

A Grinding Power Model for Selection of Dressing and Grinding Conditions

The grinding power is often used as a parameter for monitoring the grinding process. The power may also be used to monitor the effects of dressing. Empirical models are required to guide the selection of the dressing and grinding conditions. In this paper, the effects of dressing conditions and grinding conditions on grinding force and grinding power are reviewed. The effects of grinding conditions and dressing conditions on grinding force and grinding power are related to the shape of the idealized chip thickness. It is found that the grinding force and grinding power can be related to the dressing operation by considering the effective density of the cutting edges on the wheel surface. The semi-empirical model developed in this paper can be used to predict the variation of the grinding power during the wheel redress life cycle. Therefore the model can be used to guide the selection of dressing and grinding conditions. The potential use of the model for adaptive control of the grinding process is also described.

Application of intelligent CNC in grinding

Abstract The application of AI technologies using modern computers and controllers is seen as a way forward to produce higher quality components more efficiently with smaller batch sizes and more frequent changeovers. Users continue to demand better accuracy, surface integrity, and shorter cycle times with reduced operator intervention and increased flexibility. This paper reviews research into the use of intelligent control and optimisation techniques in grinding and propose the incorporation of intelligent techniques into computer numerical controls (CNCs). Two main trends are evidenced in the development of AI technologies in grinding: desktop systems to assist tool and parameter selection and self-optimising systems integrated within the machine controller. It is predicted that future developments will favour increasing incorporation of intelligence into CNC. The development of modular systems which are sufficiently robust to plan, supervise and control abrasive processes requires ongoing research and development.

Intelligent CNC for Grinding

The aim of this research was to improve productivity in grinding by bringing together process technology and microprocessor technology in an adaptive CNC system. The main objective was to produce parts satisfying specified geometrical, metallurgical and surface finish requirements. A secondary objective was to perform grinding under optimal conditions at a maximum production rate. In order to facilitate the application of a flexible range of strategies for control of the grinding process it was decided to formulate a modular conceptual framework. A variety of strategies and process models were incorporated within the framework according to the requirements of the process in question. This philosophy can be extended to a range of processes. The system was implemented using an OSAI A-B 8600 controller to control a Cincinnati centreless grinding machine. Initial production trials proved satisfactory in that the system ‘learned’ the properties of the parts produced, produced parts within specification and reduced the floor-to-floor time.

Suitability of the Upper Airway Models Obtained from MRI Studies in Simulating Drug Lung Deposition from Inhalers

No HeadingPurpose.In this study, the suitability of the upper airway models, obtained by applying a magnetic resonance imaging method, in simulating in vivo aerosol deposition data is determined.Methods.Depositions of salbutamol sulfate from two nebulizers in two models, one with constriction at the oropharynx (the constricted cast) and another model without that constriction (the wide cast), were determined.Results.For the Sidestream and Ventstream nebulizer, 76 ± 3% (mean ± standard deviation) and 81 ± 2% of the emitted dose deposited in the constricted cast, whereas 51 ± 2% and 49 ± 3% of the emitted dose deposited in the wide cast, respectively. These values were in good agreement with in vivo data. Mostly, increasing nebulizer charge volume (by normal saline) from 2.5 ml to 5 ml increased significantly the lung dose. However, the lung doses from the Sidestream and Ventstream nebulizer with 2.5 ml charge volume via the wide cast were (1.37 ± 0.06 and 1.38 ± 0.05 mg) significantly larger than those for the constricted cast with 5 ml charge volume (0.87 ± 0.15 and 0.86 ± 0.21 mg, respectively) (p = 0.005).Conclusions.The upper airway models closely simulated the in vivo deposition data. Optimizing the upper airway posture during inhalation via the nebulizers would be more efficient in increasing drug lung delivery than diluting their contents.

Effective Thermal Properties of Grinding Wheels and Grains

Abstract The thermal properties of the grinding wheel are required for energy partitioning in grinding. This paper describes an investigation of the effective thermal properties of alumina and cubic boron nitride (CBN) grinding wheels. Results are presented for a novel sensor that was designed to measure the bulk thermal properties of grinding wheel samples. The effective bulk thermal properties of the grinding wheel and the effective thermal properties of the abrasive grains were also investigated. It was found that the bulk thermal property is dominated by the properties of the bond and does not account for the improved thermal performance of CBN compared with alumina. Values of the effective thermal conductivities for alumina and CBN abrasive grains are therefore proposed. It is concluded that the effective thermal conductivity of the grains is best obtained inversely from grinding experiments.

Application of delay-time analysis via Monte Carlo simulation

This paper presents a methodology for the application of delay-time analysis via Monte Carlo Simulation. The aim is to demonstrate the worth of delay-time analysis and how its application can provide engineers with more information when making maintenance decisions. The methodology has been applied to two case studies.