Design, Fabrication and Evaluation of Electric Forage Chopper with Adjustable Helix Angle

In this study, we aimed to design and make an electric forage chopper having a cylinder type cutterhead. In recent years, several models of forage chopper have been manufactured but each of these machines has had problems such as type of power supply system, type of cutting mechanism and feeding mechanism, lack of safety, etc. These problems were solved in this study. In the device that was manufactured in this research, feed rolls rotational speed, rotational speed of the cutting cylinder, blades’ helix angle and blades’ rake angle was adjustable. So, with these capabilities, these variables can be optimized for any kind of forage, and this information can be used to design and construct suitable machines for crushing any kind of forage. Alfalfa was used to test the machine, where its test matrix was determined using Response Surface Methodology (RSM) modeling method. The results showed that, on average, power requirements for chopping alfalfa was decreased from ۱۲.۶ to ۹.۷% by increasing the helix angle from ۰° to ۱۰° and from ۱۰° to ۲۰°, respectively. As rotational speed of the cutting cylinder increases from ۵۰۰ to ۸۰۰ rpm, the power used for chopping forage increases by about ۵۶ W. In the conducted tests, maximum power requirements for chopping alfalfa was roughly equal to ۲۰۰W, which was associated with ۱۵۸.۵ rpm feed rolls rotational speed, ۸۰۰ rpm rotational speed of the cutting cylinder, and helix angle of zero. Contrarily, minimum power requirements for chopping alfalfa was ۱۱۴W which was related to ۱۵۸.۵ rpm feed rolls rotational speed, ۵۰۰ rpm rotational speed of the cutting cylinder, and ۲۰º helix angle. Optimizing test results showed that the most suitable values for the feed rolls rotational speed, rotational speed of the cutting cylinder, and helix angle were ۱۵۰ rpm, ۶۷۷ rpm, and ۹.۲۲º, respectively, provided that power requirements and particle size are minimized and device capacity is maximized.