加工番茄果秧分离参数优化及验证

Parameters' optimization and verification for processing tomato fruit-seedling separation

为满足自走式番茄收获机国产化研究不断推进的需要,采用CCD(central composite design)设计与响应曲面分析(response surface methodology,RSM)对果秧分离性能作优化研究。以收获生产率、摇摆器转速、输料链速度为自变量,果秧分离性能(果秧分离率和果实破损率)为响应指标,建立了二者间的多元数学回归模型,探究了因素间的影响规律及最佳水平组合。通过Design Expert 9.0软件对试验参数进行优化,确定了在满足果秧分离率、果实破损率符合番茄收获机作业质量标准(NYT1824-2009)条件下的最优分离参数组合。结果表明:果秧分离率影响因素显著程度顺序为:摇摆器转速>收获生产率>输料链速;果实破损率影响因素显著程度顺序为:摇摆器转速>输料链速>收获生产率;最优参数组合为收获生产率34.2t/h、摇摆器转速为409.3r/min、输料链速为0.71m/s;对应的果秧分离率、果实破损率预测值分别为96.27%、2.12%。经验证,应用响应曲面分析法所得到的果秧分离参数是可行的,该研究可为加工番茄果秧振动分离技术的进一步研究提供理论基础和科学依据,亦可为果品振动收获技术参数的优化提供参考。

In order to meet the needs of localization in China about the self-propelled tomato harvester, two methods of CCD （central composite design） and RSM （response surface methodology） were employed to optimize the performance of fruit-seedling separation. The testing device of fruit-seedling separation was consisted of wiggler （including eccentric block, exciter and timing belt pulleys）, separation roller, separation tine and damper components. Rotary motion from the power source was turned into a variable speed rotary motion by the eccentric drive mechanism of the wiggler, and passed to the separation roller to achieve the fruit-seedling separation through its periodic oscillations. When the testing device worked, tomato plants were transported to the fruit-seedling separation device by the conveying chain and got the separation of fruit and vine. The processing tomatoes were sent to picking boxes through conveying chain after being separated. The velocity of conveying chain and the wiggler speed could be adjusted through the transducer-controlled drive motor. The harvesting productivity was controlled by the amount of tomato plants fed and the separation time in the separation roller. The determination and calculation of fruit-seedling separation rate and fruit damage rate was based on the reference to the tomato harvester work quality standards （NYT 1824-2009）. The productivity, wiggler speed and chain velocity were taken as 3 independent variables and fruit-seedling separation rate and fruit damage rate were the responsive variables. The relationship between these 3 variables and 2 responsive variables was explored by the RSM. The mathematical regression model was established by using the CCD method and the influencing rules of the factors were explored. The experimental parameters were optimized by using the Design Expert 9.0 software. The optimal combination of separation parameters was determined, under the condition that the tomato separation rate and tomato damage rate both met the quality standard for tomato harvester （NYT1824-2009）. The result showed that, in terms of significant degree, the influence factors of separation rate were the wiggler speed, the productivity and the chain velocity, respectively, and the influence factors of damage rate were the wiggler speed, the chain velocity and the productivity, respectively. The optimal combination of parameters was 34.2 t/h of the productivity, 409.3 r/min of the wiggler speed and 0.71 m/s of the chain velocity. The rates of tomato separation and damage predicted by the models were 96.27% and 2.12%, respectively. The model validation tests had been repeated for 5 times on processing tomato fruit-seedling separation device by using the optimization results in the laboratory of agricultural machinery of Xinjiang Production and Construction Corps. Both of the relative errors between the experimental and predicted values of fruit-seedling separation rate and fruit damage rate were less than 5%, which indicated a reasonable choice of optimization conditions. Predicted value of fruit-seedling separation rate was 96.27%, which was greater than 95.5%, and predicted value of tomato damage rate was 2.12%, which was less than 5%. It met the threshold limit values of 95.5% and 5% about operating quality for tomato harvester （NYT1824-2009）. Therefore, the prediction model of separation performance established was appropriate and the optimization separation parameters obtained were also feasible. The test was based on double eccentric vibration generator device and only Riegel 87-5 was selected as the testing object. Further study on fruit-seedling separation properties under different kinds of processing tomatoes and different types of vibration generators was recommended. This study showed that fruit-seedling separation parameters obtained by the RSM were feasible, which might provide a theoretical basis for further research of fruit-seedling vibration separation technology of processing tomato.