Design and optimization experiment of working performance of sliding push opener

Abstract: When a large number of fertilizers were applied, deep fertilization was performed to avoid damaging seeds and causing environmental pollution in China. But when deep fertilization was used, it was difficult to control sowing depth which would influence the sowing quality and reduce the crop yield, so the sliding push opener was designed. The sliding push opener consisted of 2 parts: the shovel handle and the sliding pusher. The sliding pusher mainly relied on its surface to work. The surface of the sliding pusher consisted of a curve, a top side and a bottom side. The top side was wider than the bottom side and the vertical height between them was set to be 150 mm. The sliding push opener was an obtuse opener. Shovel handle was a 30 mm × 50 mm steel tube through which seeds could be delivered. As the sliding push opener's top side was wider than the bottom one, it was easy to push disturbed soil back into the furrow and control the sowing depth. In order to get the optimal structural parameters of the sliding push opener, the single factor tests, the response surface tests and the verifying tests were carried out. When the sliding push angle was 45°, the single factor tests were carried out for the top width (ranging from 30 to 78 mm) and 5 levels were set; when the top width was 33 mm, the single factor tests were carried out for the sliding push angle (ranging from 45° to 65°) and 5 levels were set. In the response surface tests, the testing factors were top width (ranging from 42 to 66 mm) and sliding push angle (ranging from 35° to 55°), and 3 levels were set for each factor. The response surface testing scheme designed with the central composite face-centered design (CCF) method was a two-factor three-level testing scheme. The response surface analysis method was used to analyze the testing data and optimize the working parameters of the sliding push opener. The Design-expert 8.0.5b software was used to analyze the test data, and then the credible regression mathematical models were obtained; after that the genetic algorithm NSGA-II of multi-objective optimization was used to optimize the regression mathematical models. The results indicated that the order for primary and secondary factors affecting soil returning quantity was: sliding push angle > top width, and that affecting forward resistance was: sliding push angle > top width. The optimal structure parameters were obtained: the bottom width was 30 mm, the height difference of the top and bottom part of sliding push was 150 mm, the top width was 54 mm and the sliding angle was 48°. Under the condition, back soil returning quantity was 8.67 g/cm and the forward resistance was 925.56 N. On the basis of the results of the verifying tests, it was found that the average soil returning quantity was 7.6 g/cm, and the average forward resistance was 935.78 N. The comparison between the optimization results and the verifying results showed that the relative error of soil returning quantity was 14.8% and that of forward force was 1.1%, which meant the optimization results were reliable. The design of the sliding push opener is very important for the consistency of sowing depth. The results of this research can provide new ideas and reference for the design and application of openers.