Sunflower threshing is one of the most interesting field processes for making the sunflower ready for seed handling, drying, cleaning and oil extraction. One of the biggest problems observed during the sunflower threshing process is the accumulation of threshed crop on the first third of the threshing roller and passing off some unthreshed parts of sunflower heads. To solve the aforementioned problem and optimize the efficiency of the sunflower threshing process, this research was focused on devising and testing a sunflower threshing machine with a close threshing box system equipped with a screw conveyor that evenly distributed the feedstock of sunflower heads on the entire length of the threshing roller. The machine was tested to assess the seed damage rate, unthreshed seed percentage, threshing efficiency, machine productivity, power requirements and specific energy consumption. The evaluation was done under different roller rotational speeds (150, 200, 250 and 300 rpm) and feeding rates (600, 700, 800 and 900 kg/h). The obtained results revealed that the threshing evaluation parameters were affected significantly by the roller rotational speed and feeding rate. The threshing efficiency was observed to rise with the rise in the roller rotational speed, and it also rose with the increasing feed rate up to 800 kg/h and then started to descend. The unthreshed seed percentage decreased with the increase in the roller rotational speed for all feed rates, and it decreased with the increasing feed rate up to 800 kg/h and then started to increase at the higher feed rates. The damaged seed percentage, power requirement and machine productivity increased with the increase of the roller speed and feed rate. The Buckingham π theorem was followed to find an equation to predict the threshing efficiency, resulting in an equation with an R2 value of 0.9309. With elimination of the blockage problem and better threshing efficiency, this machine could be a good choice for small- to medium-sized sunflower farms.
To solve the problem of grain spatter during harvest by combine harvester headers, a new clamping and conveying device of the sunflower oil harvester header was designed. We investigated plant states during the conveying process. To optimize the parameters of the sunflower oil harvester header, a test bench was built to simulate sunflower plant harvest. The influence of the clamping gap, clamping speed ratio, and clamping length on conveying success rate was explored by a single-factor experiment. Based on this experiment, the secondary regression orthogonal rotation test was carried out. The optimal structural parameter combination was obtained as follows: the clamping gap was 20 mm, the clamping speed ratio was 1.3, and the clamping length was 345 mm. Under this combination parameter condition, the corresponding conveying success rate reached up to 85.16% and the minimum value of conveying grain loss rate was 1.57%. To verify the effect of parameter optimization, a verification test and a comparison test were performed. Results showed that the actual conveying success rate was 83.50% and the actual grain loss rate was 1.49%, which were close to the optimized parameter value. The comparison test showed that the conveying success rate of the flexible clamping and conveying device was 83.50% with a grain loss rate of 1.49%, and that of the rigid clamping and conveying device was 55% with a grain loss rate of 5.17%. This study provides a theoretical basis for the design of a low-loss sunflower oil combine harvester header.
Abstract. Mechanisms to aid fruit harvesting are undergoing constant development with increasing available technologies. However, fruits grown on vines, such as kiwifruit, have complex tree architectures and present difficulties in confirming design parameters. The objective of this research was to develop an end-effector for a kiwifruit harvester based on integrating the physical characteristics of the fruit, such as stem length, the space between mature fruits, and the growing environment provided by a trellised system into the design. These properties contribute to developing a mechanism that is lightweight, battery operated, and requires only one translational joint for positioning. Scissor cutting actuated by a linear solenoid is used to provide the required torque of 1.38 Nm to completely sever Hayward variety kiwifruit at the stem using a curved blade with a 20° relief angle. The cutting of the stem is actuated by a force sensor located on the device that enables cutting at less than 10 N, preventing premature detachment of the fruit and damage to the vine. The cutting time was measured to be 0.1 s ±0.03 s per cut. This end-effector design adds to the body of research aimed at developing a fully mechanized kiwifruit harvester. Keywords: Detachment force, End-effector, Fruit harvester, Kiwifruit, Linear solenoid.
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