Analysis of application of the material force response to the abrasive water jet impact

Abstract

The abrasive waterjet is already well described in terms of physics, but descriptions of the waterjet machining process are very complex and unsuitable for monitoring of this process, so it is important to look into the problem from the other side. The response of the material has been studied in past but the idea of using this response for online monitoring of the process remains unexplored. This thesis aims at studying this response using series of experiments. Two parameters that were selected as the best for this thesis were the forces exerted by the abrasive water jet upon the material and the vibrations of the sample. These parameters were measured at different workstation and upon different materials. Measured values were then compared and constants were defined that determine the effect of the used material and workstation on the measured force. These constants might help to determine, if the machining process was without errors. Measured force should be approximately equal to the product of these constants and the ideal force. This ideal force is calculated as a product of the applied pumping pressure and the cross-section area of the water nozzle. Measured vibrations are expected to be inversely proportional to the mass of the workpiece. They can be also expected to be proportional to the measured forces. The theoretical and experimental values were compared, and it was discovered that in the axis of the jet flow direction the errors are the lowest and fairly consistent. If the relative error exceeded some threshold values, it was discovered that the cut was not completed. This can be used in practice for monitoring of the cutting process in a real time to determine, if any error in the machining process or failure occurred.