Design and experiment of a comb-and-scrape Idesia Polycarpa Maxim threshing device

Currently, Idesia polycarpa Maxim is used as a woody oil crop and the edible oil extracted from it has a very high unsaturated fatty acid content. Therefore, this crop has also been increasingly planted industrially. However, its fruit picking work relies on manual use of high pruning shears to complete, the efficiency is low. Based on this problem, this paper designs an integrated device for picking and threshing. After the relevant physical properties of the fruit were tested, the harvesting method was indeed brush-type harvesting. Then the test was carried out by simulation using comb plates with different cross-sectional shapes. The results show that the maximum separating force on a single grain produced by a comb plate with a diamond-shaped cross-section is 15 N, which is larger than that produced by a rectangular shape (7.5 N) and a circular shape (2.1 N), and the vibrational agitation produced by the fruit is minimized under the operation of a diamond-shaped comb plate. The experiments with cross-section shape as a single factor also showed that the diamond-shaped cross-section shape comb plate has more excellent threshing effect. On this basis, the performance indexes of picking rate, breakage rate and stalking rate, the factors of comb gap and comb moving speed were used to conduct the bench test, and the response surface analysis of the central combination design was carried out. The results showed that the three performance indexes were best when the comb gap was 4.4 mm and the traveling speed was 0.06 m/s. Validation experiments were conducted using this optimal parameter combination, and the results showed that the picking clean rate, breakage rate, and rate with stalks were increased by 8.01%, 34.33%, and 5.41%, respectively, compared with those before optimization. The design of this device can solve the problem of mechanized picking of santolina and provide design ideas for the picking of cluster-shaped granular crops.