Design and experiment of 2ZGK-6 type spacing-adjustable wide-narrow row high speed rice transplanter

Abstract: Rice production is distributed broadly in China. The rice growing environment conditions are different in different regions, so there is large difference in rice transplanting spacing. Even in the same growing area, the rice transplanting density and the planting spacing are different due to the difference of the transplanting rice species and the growing conditions. The wide-narrow row planting is beneficial to the field management, which can effectively use the field marginal effects, improve the performance of air and light, and enhance the plant photosynthesis. The microclimate in the field is changed to reduce the humidity between plants, and the pests and diseases of rice. Considering the diversity of rice species and the conditions of soil, water and fertilizer, the conventional transplanter which had fixed row spacing, including the constant row spacing transplanter and the wide-narrow row spacing transplanter, could not meet the rice spacing requirements and caused the low adaptability and the low efficiency. For overcoming above shortcomings together with considering the quality of mechanized transplanting and the agronomic requirements of rice, a spacing-adjustable wide-narrow row high speed rice transplanter, which could transplant the rice seedlings with wide row spacing of 300 mm and adjustable narrow row spacing in the range of 200-300 mm, was designed creatively by using the technology of multi-body dynamics, multidisciplinary design optimization, virtual prototyping and simulation. The force analysis of seeding box, supporting beam and screw shaft was carried out to achieve their reasonable structures. The transplanting spacing of this machine was adjustable according to the requirements of specific rice planting density. The machine could meet the agronomic requirements of rice planting spacing in the different regions, and achieved the full potential of individual strain and rice population and improved the adaptation scope and use efficiency. The rice tranplanter was developed based on the Kubota SPU68C high speed rice transplanter. The key structural parameters of the machine were determined according to the adjustable spacing performance requirements. A coaxial forward and reverse double-helix adjusting mechanism, an eccentric locking mechanism, a separable combination seeding box and other key parts were designed and manufactured. According to the agronomic requirements of mechanized transplanting technology for different rice species, the single cropping mid-season rice species Xinliangyou 98 and the double cropping late rice species Zhendao 18 were chosen as test materials, the field experiments were carried out with the prototype of spacing-adjustable wide-narrow row high speed rice transplanter, and the transplanting seedling quality and the machine performance were studied. Field test results showed that the machine performance was pretty good, the damaged rate of seedling was less than 2.5%, the leakage transplanting rate was less than 3%, the qualified rate of relative uniformity degree was more than 96%, the floating rate of seedling was less than 2.5%, the overturning rate of seedling was less than 2.5%, and the acceptance rate of planting depth was more than 92%, which met the Criteria of Rice Transplanter Technical Conditions (GB/T 20864-2007). The good actual yield results were also achieved with planting the single cropping mid-season rice species Xinliangyou 98 with wide row spacing of 300 mm and narrow row spacing of 250 mm, and the double cropping late rice species Zhendao 18 with wide row spacing of 300 mm and narrow row spacing of 200 mm. The effect of transplanting spacing on the yield of the double cropping late rice is larger than that on the single cropping mid-season rice. The machine has changed the conventional mechanical rice transplanting method. It meets the actual rice production requirements in different regions, effectively solves the problems of the transplanter with fixed spacing which is difficult to meet the diversity of rice species and growing environments, improves the adaptability and the efficiency of machine, and raises the productivity and the mechanization level of rice production.