Determining cutting energy requirement for rice stem by a pendulum displacement apparatus.

Cutting energy requirement for rice stem is a momentous touchstone in design or optimization of cutting mechanism on harvesting machines. Various parameters such as physical and mechanical properties of plant stem and shearing blade characteristics are effective on cutting energy requirement. Specifying these parameters and their impacts on cutting energy would be especially important in assessment of cutting mechanism efficiency and total energy utilized. In this study, using a test-rig pendulum displacement cutting apparatus, specific cutting energy for single stem cutting of rice stem was determined. The experiments were laid out in factorial based on completely randomized design (CRD) with three replications in order to examine the effects of rice varieties (at four levels: Hashemi, Ali Kazemi, Fajr, and Khazar), cutting angle (at three levels: 25, 30, and 35 degrees), blade bevel angle (at four levels: 25, 30, 35, and 40 degrees), and blade speed (at three levels: 1.5, 2.0, and 2.5 m s-1) on specific cutting energy for rice stem. The results revealed that rice variety and blade speed had significant effects (p0.01) on specific cutting energy. Also, interactions as variety‎ أ cutting angle, variety‎ أ cutting angle‎ أ blade bevel angle, variety‎ أ blade speed, and variety‎ أ cutting angle‎ أ blade speed affected specific cutting energy significantly (p0.01). There were significant differences among varieties in the view of specific cutting energy so that the highest and lowest values belonged to Hashemi (29288.54 J m-2) and Khazar (16808.77 J m-2), respectively. When blade speed increased from 1.5 m s-1 to 2.5 m s-1, specific cutting energy raised about 1.8. Optimum specific cutting energy obtained at cutting and blade bevel angles of 30 and 30 degrees, respectively. Keywords: specific cutting energy, rice stem, cutting angle, bevel angle.