Papers by Keyword: Water Jet

Abstract: The article is devoted to the study of the technological process of waterjet cutting of cylindrical parts on CNC machines. The results of experimental data on determining the accuracy of dimensional deviation, surface roughness, and taper of cylindrical parts depending on the circular milling of a water jet during waterjet cutting are presented.

Abstract: The dynamic process of an underwater explosion (UNDEX) is a complex phenomenon that involves several facets. After detonation, the shockwave radially propagates at a high speed and strikes nearby structures. Subsequently, bubble oscillation may substantially damage the structures because of the whipping effect, water jet impact, and bubble pulse. This paper presents an application of explicit finite element analyses to simulate the process of an UNDEX bubble in the vicinity of rigid wall, in which the coupled Eulerian-Lagrangian (CEL) approach was developed to overcome the difficulties regarding the classical finite element method (FEM), large deformations, and flow simulation of fluid and gas. The results demonstrate that the method is well suited to manage the UNDEX bubble problem and can be used to model the major features of the bubble dynamics. Furthermore, the behavior of an UNDEX bubble near a rigid wall was also examined in the present study, which showed that the migration of the bubble and the development of the water jet are influenced strongly by the standoff distance between the initial bubble position and the wall. This method can be used in future studies to examine UNDEX bubbles in the vicinity of deformable and complex structures.

Abstract: The search of ornamental rocks cutting technology to meet the market and efficiently together economic, environmental and safety parameters is increasingly requested in the mineral sector. This study tried to compare two cutting technologies with respect to their technical-operational aspects: diamond wire and water jet. The methodology used consists of a bibliographical research raising data of both technologies and organizing them in graphs and tables for the best comparison. The diamond wire offers significant economic advantages over water jet, which limits the use thereof. Regarding the environmental aspects, the two techniques proved to be equivalent, with optimum performance in this parameter. The water jet has advantage in safety factor in relation to the diamond wire, due to its ability to cut by computerized system.

Abstract: In the paper, the resistance of concrete to the erosive effect of water from a water jet was monitored. The tests were performed on concrete without the addition of fibres and on concrete with the addition of polypropylene fibres and steel fibres. The water flow hit the concrete surface at an angle of 90°. The water flow rate was 1.1 l/min and the water pressure was 80 MPa. After blasting the concrete with water jet, no cracks in the concrete were observed and the intended rugged surface relief was created. Steel fibres remained firmly anchored into the cement matrix.

Abstract: Composite systems are materials that due to its characteristics and its achievement of synergistic effects are increasingly applied. The most frequent composites are composites mainly with long fibers. In the interaction with the polymer matrix can be used inorganic fibers, but recently there is a substitution of these fibers with organic fibers. The main advantage of using organic fibers is their low cost, low weight, and availability. The benefits can also cite environmental aspects. The disadvantage is the very nature of the organic material. The paper describes a long-fiber composite system prepared by vacuum infusion and compares the tensile strength of composites with randomly oriented and arranged sisal fibers, depending on the flow direction of the resin during vacuum infusion. Composite systems were cut from boards made by vacuum infusion using a water jet. These boards are widely used by industries such as automotive or building to where the natural fibers can create design function. The use of natural fibers in this process is inexpensive and such materials can be referenced as biocomposites, saving the primary raw material. The paper describes the tensile strength and hardness. Electron microscopy was used to evaluate fracture surfaces and the morphology of the fibers.

Abstract: Since 1950, the use of water jets has grown in the field of cleaning pipes and sewers. The regular cleaning of the materials deposed in sewer networks is realised especially with equipment that uses high pressure water jets. The functioning of this equipment is dependent on certain process parameters that can vary, causing variations of the impact forces. The impact force directly affects the cleaning of sewer systems. This article is a part of research activity what is centered on the study of the cleaning head - sewer system. The purpose of this research is to determine an equation of the impact forces of the water jet that depend on process parameters. The research method used is that of the full factorial plan. For the experimental determination of the impact forces a stand for generating water jets and a device for measuring the forces of impact are used. The equation of the impact forces measured is determined using the software Minitab 17.

Abstract: We have shown the feasibility of using multipass processing for obtaining precision profile cuts of hard-alloys material using the changable cutting feed that leads to significant reduction in deviations from intended form of jet. Found that the decrease in speed around the contour should be proportional to the thickness of the processed material and its physical and mechanical characteristics.

Abstract: The paper presents a database programme which was created on the base of the search focused on working condition impact to generating and extend of vibrations at AWJ technology production systems. The database programme serves for less complicated, but mainly quicker and more effective searching of an optimal combination of technological parametres to get minimal values of vibration parametres during AWJ technology selected materials cutting. The work presents a thematically integrated part of a dissertation.

Abstract: The paper describes abrasive kind and granularity change impact to technology head vibration generating during cutting of seven selected investigated kinds of steel by means of AWJ technology. The investigation of abrasive granularity impact is carried out for three speeds of the technology head shift. A set of 3D comparative graphs of vibration parameter relations for seven analyzed kinds of steel from graphical records of vibration acceleration amplitude to frequency relation was created. On the base of the comparative graphs a discussion about results is generated and conclusions are defined. The work presents a thematically integrated part of a dissertation results and completes a group of recent knowledge focused on production systems working state diagnostics with the water jet technology.

Abstract: The submitted paper presents a technical system for vibration measuring, processing and evaluating The technical system is presented as a part of a survey which main goal was to find out an influence of working conditions on creation and extend of vibration within production systems. The work introduces a demonstrational example of measured, processed and evaluated data of an experiment where parametres of vibrations, which were created due to water jet technological head parametres changes, were scanned.