In both the chemical and mechanical pulping process, the logs are cut into wood chips by a cone shape tool before fiber separation. To make the wood chopping process more efficient, one has to investigate in detail the coupling between process parameters and the quality of the chips. One objective of thesis was to obtain an understanding of the fundamental mechanisms behind the creation of wood chips. Another objective with the thesis was to investigate whether it was possible to, in a way, tailor the chopping process so as to reduce the energy consumption in a following mechanical refining process.
Both experimental & analytical/numerical approaches have been taken in this work. The first part of the experimental investigations, were performed with developed chopping tool. The results from the experimental investigation showed that the friction between log and chopping tool is probably one crucial factor for the chip formation. Further more it was found that indentation process is approximately self-similar, and that the stress field over the entire crack-plane is critical for cutting the chop wood. The developed analytical model products the normal and shear strain distribution and to be more specific, the model can predict compression stresses parallel to the fiber direction for an assumed linear elastic & Orthotropic material. The project deals with design and fabrication of a wood chopping machine with less effort and safely considering manual methods which was followed in traditional way. The following objects were met from the project.
• To reduce the time required for wood chopping when compared with manual method.
• To reduce the effort required for wood chopping.
• To eliminate improper way of chopping wood.
• To carryout safe chopping of wood with help of fixture and accessory when used.
• To increase the efficiency of wood chopping.
• To eliminate injuries that may occur during wood chopping.
• To minimize the time and effort required for wood chopping by using fixture and accessory.
• To reduce the labor cost for wood chopping.