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Wegener J.K.,Julius Kuhn Institute | Frerichs L.,Institute of Mobile Machines and Commercial Vehicles | Kemper S.,Institute of Mobile Machines and Commercial Vehicles | Sumening F.,Institute of Mobile Machines and Commercial Vehicles
Biomass and Bioenergy | Year: 2015

Experiments made with a model helical chipper have shown that the infeed angle has a huge impact on chip quality parameters. Furthermore, it could be pointed out that the self feeding mechanism of the helical chipper was impeded with larger infeed angles and finally failed. This situation led to the hypothesis that the infeed angle must have an impact on power requirement during chipping. In the present investigation this conclusion was tested. Standardized preformed test rods were chipped with a helical chipper at seven different infeed angles while torque, rotational speed and chipping time were recorded. The experimentation was done using poplar wood with different moisture content. Based on the measurements power requirement and energy consumed was calculated for each test series. The results of the experiments show that power requirement and energy consumed are decreasing with increasing infeed angle. The results seem to be extraordinary since increasing infeed angles lead to decreasing chip sizes being produced. Based on theoretical deliberations and experimental data it can be assumed that besides the anisotropic character of wood geometrical settings of helical chipping could be a reason for the experimental findings. But, because the chipping time is also dependent on the infeed angle there still must be other reasons concerning the occurring forces during helical chipping, too. For this reason there is a need to have a closer look onto the different forces occurring during helical chipping. Against this background the Discrete Element Method (DEM) could be a simulation method for future research. © 2015 Elsevier Ltd.


Kattenstroth R.,TU Braunschweig | Harms H.-H.,Institute of Agricultural Machinery and Fluid Power | Frerichs L.,Institute of Mobile Machines and Commercial Vehicles
Landtechnik | Year: 2012

Besides the harvesting process the cutting of threshed straw and its uniform distribution is of major importance during the grain harvest. The stochastic orientation of less stable stalks in a combine's straw chopper causes uneven cutting lengths. According to the working conditions uneven cutting length could cause problems during their distribution on the field due to fines. Overlong cut stalks induce problems at following cultivation operations. The Institute of Mobile Machines and Commercial Vehicles (former Institute of Agricultural Machines and Fluid Power) at the Technische Universität Braunschweig researches the correlations and parameters of the influence of straw alignment on the cutting quality of a combine's straw chopper by using simulation and practical experiments.

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