Water-jet Sugar Beet Cutting

Christian Brüser, Hans-Heinrich Harms, Brunswick
A t the Institute of Agricultural Engineering and Fluid Power of the Technical University of Braunschweig, the use of the water jet cutting technique for the cutting of organic materials is being studied. Especially for homogeneous materials, such as sugar beet, this technique proves to be an appropriate alternative to the known methods. At present, intensified studies on the water jet cutting of sugar beet are being carried out. These studies are mainly focusing on the reduction of cutting
more » ... tion of cutting energies and water consumption in order to make this technique even more interesting for mobile application , in addition to stationary use. Power analysis Today, water jet cutting in industry is generally carried out using pressure intensifiers at high pressures of approximately 350 MPa and small nozzle diameters (about 0.254 mm). Since the water volume flow is small due to the operating principle, the largest part of the cutting power is provided by pressure. What is the cutting result, if pressure is lower and water volume flows are larger, while power is constant? In order to answer this question, a series of experiments were carried out at constant power levels and using a wide range of nozzles [1]. The results are shown in Figure 1. In the left diagram, cutting depth is shown for every used nozzle over the applied water-hydraulic power. The largely identical course of the graphs can be discerned clearly. The deviations of the two smallest nozzles can be explained as a result of friction-and damping effects in the cutting gap becoming so significant when a certain cutting depth is exceeded that cutting depth cannot be increased further. In principle, this effect occurs with every nozzle. The larger the mass flow from the nozzle becomes, however, the later the course drops, which is no longer shown in the diagram for nozzle diameters in excess of 0.33 mm. At a power of 9,000 W, a cutting depth of approximately 80 mm can be maintained for each nozzle. The right diagram shows the volume flow over the nozzle pressure for each nozzle. This diagram is based on the same measured values as the left one. The connection of the measuring points of a parameter provides a hyperbola, which is shown for 9,000 W as an example. Every point on the hyperbola stands for an arbitrary combination of pressure and volume flow. If a nozzle having a diameter of 0.254 mm is used, 1.5 l of water per minute flow at an operating pressure of 360 MPa. If a 0.9 mm nozzle is used, however, an operating pressure of 61 MPa in combination with a larger volume flow of 8.8 l/min is sufficient. Therefore, constant water-hydraulic power leads to a constant cutting result in a very wide range. The process of water-jet cutting has established itself in various industry branches. There the many process specific advantages which speak in favour of this geometrically indeterminate cutting edge operating system. Besides the known cutting materials like steel and or stone, agricultural materials can also be cut. Especially homogeneous goods like sugar beets and potatoes have shown favourable cutting results in this respect.