Design and parameter optimization of double disk opener mechanism for harvest ditch and stalk-disposing machine

Abstract: In order to advance the seeding quality of harvest ditch and stalk-disposing machine that our research group designed and fabricated, a double disk opener mechanism was designed combining with the harvest ditch and stalk-disposing machine. An electric lifting device was integrated into double disk opener mechanism installed underneath sowing box of the harvest ditch and stalk-disposing machine. To improve the working performance of double disk opener mechanism, the structure and installation parameters of the double disk opener mechanism were calculated. The diameter of double disk opener was 200 mm，the disc included angle of double disk opener was 15°, the accumulation point angle of double disk opener was 81.4°, the maximum entering soil depth of double disk opener was 60 mm, the joint lever length of central point of double disc opener to hinged installation point of bottom of header was 370 mm and the distance of upper connection point of electric lifting gear to ground was 661 mm. The three work factors, forward speed of machine, furrow depth of double disk opener, and horizontal distance of fixed hole central point of sowing pipe's fixed device on furrow opener to exit central point of sowing pipe (shortened horizontal distance of fixed hole), impacted quality of furrow and drill mainly. In order to optimize working quality parameters of double disk opener mechanism, a central composite design method of second order regression orthogonal rotation was carried out. In the experiment, the three work factors were used as the experiment factors and the rate of seeds into the ditch, each row seeding stability coefficient of variation, and seeding uniformity coefficient of variation were used as experiment indicators. In the experiment, forward speed of machine was 0.3-1.2 m/s, furrow depth of double disk opener was 1.5-4.5 cm, and horizontal distance of fixed hole was 14.5-18.5 mm. The variance analysis results of orthogonal experimental showed that among the three factors in the experiment, the horizontal distance of fixed hole had the greatest influence on the rate of seeds into the ditch and each row seeding stability coefficient, while the forward speed of machine had the least influence on the rate of seeds into the ditch and each row seeding stability coefficient, and forward speed of machine had the greatest influence on the seeding uniformity coefficient of variation, while the horizontal distance of fixed hole had the least influence on the seeding uniformity coefficient of variation. Through the MATLAB software, we optimized values of the three factors, and the optimized results showed that the optimal value of forward speed of machine was 0.46 m/s, furrow depth of double disk opener was 3.25 cm, and horizontal distance of fixed hole was 16.16 mm. When the three factors reached the optimal values, the value of the rate of seeds into the ditch was 90.3%, value of each row seeding stability coefficient of variation was 9.3% and value of seeding uniformity coefficient of variation was 10.2%. The validation experiment was carried out for making the rationality of optimal values. The validation experiment showed that when the values of three factors were the same as optimize values, the value of the rate of seeds into the ditch was 89.4%, value of each row seeding stability coefficient of variation was 9.4% and value of seeding uniformity coefficient of variation was 9.8%. The relative error was below 4% of experiment values with optimal values, which validated the optimal values of the three factors.