| As one of the important economic crops in our country, tobacco plays an important role in agricultural production. Tobacco is a kind of crops which dominated by way of seedling transplant. The traditional manual transplanting mainly by a large number of human resources, animals resources, traditional production tools as well as production mode, with high labor intensity but low production efficiency, is not suitable for large-scale planting. While mechanized transplanting can not only improve the quality of tobacco seedlings, reduce the cost of breeding, but also can greatly reduce the labor intensity of farmers, to strive for more spring planting time and greatly improve the crop planting efficiency. In recent years, with the promotion of the departments of tobacco production management and the participation of the scientific research departments in our country, Tobacco transplanting mechanization has begun to independent research and development or introduced overseas related equipment, but for the domestic existing models still have a long way to reach actual production application, farming and agronomic are not closely linked, causing transplanting mechanization in our country has been unable to carry out large area promotion.This article is based on the study of previous members study "basket tobacco transplanting duplex operation machine", combined with tobacco bowl seedling physical and mechanical properties test results and Northern tobacco seedling transplanting agronomic requirements, and summarizes the problems of transplanting machine early field trials, to improve the design and Experimental Research on the key components of tobacco pot seedling, so as to improve the performance and quality of the field work of the tobacco bowl seedling transplanting machine.Research is mainly from the following aspects:(1) The basic geometric parameters of the tobacco seedling in Northeast tobacco growing areas were determined, and the variation range and the distribution law of the geometric characteristics of tobacco seedlings were analyzed statistically.(2) Using the universal material testing machine, the shear, compression, bending and tensile tests were carried out on the stems of tobacco bowl seedlings during the transplanting period.(3) Described the requirements and improvement of agronomic seedling of northern tobacco seedling and transplanting of basket tobacco seedling transplanting machine structure and working principle, according to preliminary test of tobacco seedling transplanting machine in the problem, and its components and design improvement of tobacco seedling feeding mechanism of seedling transplanting machine.(4) Established the kinematics and dynamics model of the transplanting mechanism of tobacco seedling transplanting machine, analyzed the theoretical analysis of the point mechanism, and to carry out the virtual simulation analysis based on Adams software.(5) Simulated the movement hole parts of field operations, built into hole component test, using orthogonal test method, to forward speed, rotational speed of the crankshaft, spade wide as experiment factors, forward resistance and hole size as the test index, designed to point components performance test. According to the performance test results of the components, the finite element analysis based on ANSYS was carried out to verify the stability and safety of spade.(6) Under the condition of the requirements of transplanting machine agronomic, refered to the dry land planting machinery industry standard, field experiments were carried out on key parts of tobacco seedling transplanting machine. The single factor and quadratic regression orthogonal rotation design method, the moving speed, seedling height and a spade width factor test, smoke in the upright seedlings is qualified rate and coefficient of variation of row spacing for evaluation index of experimental research.From the above research, this paper obtains the following conclusions:(1) Through analysis of tobacco seedlings of geometric parameters of statistics that tobacco seedling height change interval [115.7,188.3]mm, distributed mainly range in [135,175] mm, accounting for 80% of the total number of samples; seedling width change interval for [80.8,182.0]mm, main distribution in[100,160] mm, accounting for 74% of the total number of samples; seedling near the root stem diameter variation interval for [3.45,4.39]mm, main distribution in [3.55,4.30]mm, accounting for 90% of the total number of samples. The test results for feeding seedling mechanism of improved design provides the basis.(2) The tobacco seedling stem cutting position had significant effects on shear failure load, shear, shear strength (?= 0.05). Northern tobacco seedling transplanting stems from the sampling sites in the surface of the 5?10mm bowl at the shear breaking load, shear power and shear strength values are the largest. In order to avoid the damage of tobacco seedlings, the seedlings with clamping position should choose 5?10mm from the surface of the pot body at the stem. By calculating the obtained tobacco stem rod the maximum shear strength average value (1.10±0.12) MPa. The compressive strength of average (1.03±0.11) MPa, flexural strength average value for (11.16±0.28) MPa, tensile strength average value for (0.66±0.15) MPa, the average tensile stress (7.49±2.47) N. The experimental results provide the basis for the design of tobacco pot seedling parts in the northern tobacco growing areas.(3) By kinematics simulation and theoretical analysis on the hole forming mechanism, get into the trajectory of the spade, analysis of the spade different direction of displacement, velocity and acceleration variation; by the dynamic simulation analysis get into hole mechanism of the rod hinge point by force changes and maximum force and verify the into hole mechanism of function and structure design of rationality, into hole mechanism of structure optimization.(4) The test results of hole parts performance analysis component performance show that when the travel resistance get minimum, optimal combination of experimental factors for crankshaft speed 36r/min, a spade width 40mm, speed 0.3m/s. Hole size in the optimal combination of factors, meet design requirements of hole mechanism. Based on ANSYS finite element analysis to obtain the points to meet the strength requirements perform.(5) Single factor and multiple factor experimental results showed that test factors impact on the qualification rate of upright degree of significant degree from high to low as follows:seedling height, forward velocity, wide spade; experimental factors on the coefficient of variation of row spacing effects to a significant degree as follows:forward speed, wide spade and seedling height. To meet the upright degree qualified rate more than 90%, plant spacing coefficient of variation of less than 5% of the agronomic requirements under the premise of optimized. The optimal parameter combination:when the seedling height from 140mm, forward speed 0.3-0.4m/s, spade wide 67-74mm.This study provides basic data and reference value for the tobacco seedling transplanting machine for further improvement of design and actual field work. |
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