THE EFFECTS OF TOOL WIDTH AND RAKE ANGLE ON DRAUGHT AND SOIL FAILURE PATTERNS OF MODEL CHISELS FURROWERS

摘要

The study aimed at determining the effect of rake angle on draught and soil failure patterns of model chisels furrowers. Thirty-six geometrically similar model chisels furrowers were used for the 2.experiment. The tool design parameters were cutting edge height, slide angle, rake angle, length, width and height. The performance parameters considered were draught and soil failure. Draught increased with increases in model tool design and operational parameters. Three of the model tools each with 20°slide and 20° rake angles produced the best furrows at 2, 5 and 10 mm cutting edge heights, respectively. The model tool with 20° slide and 20° rake angles and 10 mm cutting edge height created furrows appropriate for Masakwa transplanting at 75 mm soil depth. The different values of the cutting edge height of the model tools led to significant differences in soil failure patterns. The significant effect of the cutting edge height on the furrows created and soil failure patterns indicates that it isa very important design parameter and should be selected carefully when designing the prototype.