1,721,109 research outputs found
Improvement of Disc Cutter Performance by Water Jet Assistance
No full textAbstract This article deals with the problem of assisting
disc cutters by means of high-velocity jets of water, with
the aim of increasing the excavation rate while improving
the working conditions, with particular reference to wear.
The results of an experimental research undertaken at the
Waterjet Laboratory of the University of Cagliari on a
medium–hard abrasive rock clearly show that a higher
removal rate is achieved owing to the weakening action of
a jet directed on one side of the disc, causing deeper
penetration. This outcome is interpreted on the basis of the
scale formation model, which explains why smaller scales
are obtained on the water jet’s side of the groove.
Accordingly, it is suggested that the results can be further
improved if the jet is directed ahead of the tool along the
same path, since, in this way, larger scales can be produced
on both sides
Nuove tecnologie nella coltivazione di rocce ornamentali: il taglio con acqua in pressione
No full text
Waterjet rough finishing of stone surface
No full textThe paper deals with the assessment of the potential application of plain waterjet for surface treatment of stone materials as an alternative to technologies traditionally employed for this task, like bush-hammering, sand-blasting and flaming.Waterjetting has been already proposed in the market for rough finishing of surfaces making use of a fast rotating head provided with multiple nozzles. At the University of Cagliari considerable research has already been carried out using either abrasive or plain waterjet, stationary or pulsed, generated through a fan-type nozzle aiming at obtaining an evenly treated surface.Aparticular goal of the tests described in the paper is that of developing a technique enabling to make engravings on the stone in order to achieve special aesthetic effects. The experimental results obtained on a broad set of rocks show that the technology is viable on both technical and economic grounds, allowing to obtain excellent results at a relatively low processing cost by resorting to multiple line nozzles
Performance assessment of surface treatment with water jet in terms of roughness
No full textSurface treatment methods based on mechanical tools, sand blasting and flaming lead to undesirable features such as chromatic modifications, production of micro-cracks, mechanical alterations. Water jetting is a relatively new process of stone surface treatment based on the action of very high velocity water jets generated at constant pressure. Water jet treated stone surfaces are of higher level of aesthetical appearance than the other methods It is used to increase the roughness to improve its antislip properties while preserving aesthetic appearance of the stone without having thermal shock, mechanical stress and the production of fumes and dust. Therefore roughness is the most important performance parameters in stone surface treatment with a water jet. Because of this, the purpose of this study is to determine the effects of different operational parameters such as; traverse velocity, standoff distance and pump pressure on performance parameter namely roughness in stone surface treatment with a water jet by using Italian basalt natural stone samples, commercially referred to as Sardinian Basalt. 27 surface treatment tests were performed using the Water Jet Cutting-Surface Treatment Machine with a constant nozzle diameter of 0.3 mm at varying standoff distances (50, 100 and 150 mm), traverse velocities (15, 20, 25 m/min) and pump pressures (200, 250, 300 MPa). After each surface treatment, roughness measurements were performed on all of the treated surfaces in two perpendicular directions by using Mitutoyo SJ-400 roughness measurement equipment. The roughness parameter [absolute deviation (Ra)] was then calculated. Absolute deviation can be defined as the average of the absolute deviations of height from the mean. The data obtained from this study were evaluated graphically and the relationships between operational parameters and roughness values were put forth. As a result of this study, it is observed that operational parameters have direct effects on performance namely roughness in surface treatment with water jet
Advanced Granite Cutting Technologies
No full textProc. 14th World Mining Congress, Peking 1990, vol. 2, 685-69
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