Design And Experinent Of Micro Rotarytillage Weeding Machine Of Vegetables Line Spacing

Developing new weeding machines to alleviate and even put an end to the dependence on herbicide is a route we must take towards green agriculture. Taibai Vegetable Experimental Station of Northwest Agriculture and Forestry University has been working on this subject for many years with joint efforts of its own experts and vegetable growers, but the results are discouraging. They haven't been able to develop a perfectly reliable mini weeding machine adapting to the narrow vegetable rows that could loosen the soil and work in a stable velocity while saving manpower. Therefore, a new design of mini-rotary tillage weeding machine that could work between vegetable rows and loosen the soil is proposed. According to the design, it uses cutter shaft to drive land wheels. The primary feature of the new mini-tillage weeding machine is that by utilizing a gear-like transmission mechanism, the machine set could transmit the force directly to the drive axle, providing a driving torque for uniform velocity. Details and results of the researches are as follows:1. Research on the driving system for mini-tillage weeding machine of the simple and light-weighted type. Based on the planting characteristics of rows(with a 200-250 mm width) for vegetables and other crops in our country and being mindful of the affordability of the vegetable growers in one-time investment, researchers decide to make simple and light-weighted type as their primary object. According to the general design, the mini-tillage weeding machine should be structurally simple and compact, the speed of its working parts and machine set should not be higher than the actual needs, and the total weight of the machine should be less than 35 kg. Therefore, the simple and light-weighted mini-tillage machine utilizes cutter shaft to drive land wheels through a gear-like mechanism, which ensures the machine set to move forward at a uniform velocity.2. Study on mechanical analysis of rotary tillage knife roller and cutter shaft strength design method. The strength of the knife roller part of the new mini-tillage weeding machine is an important component of the machine set's design. The traditional design method is laborious and time-consuming. Benchmarked against the strength of knife roller part of certain approved product of ISG9-50 with reasonable design which has been used for a long time and based on ANSYS, an analysis has been conducted on the knife roller of the newly designed min-tillage weeding machine. Based on stress analysis and comparison of the benchmark cutter shaft and the cutter shaft of the originally designed mini-tillage weeding machine, the cutter shaft design of the original mini-tillage weeding machine is improved. This study has provided a new method for reasonably making use of materials, reducing products cost, and especially for improving and optimizing the mechanical structure. The cutter shaft of the improved mini-tillage weeding machine has changed from solid shaft with the diameter of 19 to hollow shaft with the outside diameter × inside diameter × wall thickness of 20×8×6, which reduces material consumption by 7%, and its maximum equivalent stress is 55.808 Mpa, which is reduced by 8.3% and smaller than that of the cutter shaft of rotary tillage weeding machine of 56.818 Mpa. The maximum deformation of the improved cutter shaft is 0.0202 mm, which is smaller than that of the original design of 0.0206 mm and that of the benchmark cutter shaft of 0.02934 mm. The results show that if the newly designed part has the same stress and strain as the benchmark product, then the strength reliabilities of them are the same. The cutter shaft of the improved mini-tillage weeding machine has more reasonable stress, structure and size.3. Test for the performance of the new machine set. The uniformity of the forward speed of the new machine set and the weeding ratio is tested, which show that the average forward speeds of the newly-designed machine set on hard and soft soil are 0.25m/s and 0.22m/s respectively. As a comparison, the average speed of the mini-tillage weeding machine without driving wheels on hard soil is 1.8m/s; on soft soil with hard spots it can be as high as 1.3m/s while on normal soft soil, it can be as low as 0.0m/s. In the 3 tested areas, after 7 days of test, the average weeding ratio of the new machine set is 64.3%. The above test results show that uniformity of the forward speed of the new machine set is superior to the comparison machine without driving wheels and that the operating comfortableness is effectively improved to reduce the working intensity.