名优茶连续式理条机参数优化设计与试验

    Parameter optimization design and experiment of famous tea continuous carding machine

    • 摘要: 针对传统茶叶理条做形装备主要依靠经验法设计,存在做形质量不佳的问题,该研究运用数值法对连续式茶叶理条机结构与作业参数进行优化,以改善连续式理条机的理条作业性能。通过对连续式理条机进行运动学分析,得到锅槽速度、加速度表达式,并探究锅槽运动与茶叶理条状态之间的关系;通过研究茶叶在连续式理条机锅槽内的运动规律和受力情况,建立茶叶-正U形槽动力学模型,分析了茶叶在锅槽运动周期内各阶段的受力特点及对茶叶成形的作用;运用EDEM软件建立茶叶理条仿真模型,对影响茶叶成形的曲柄转速、锅槽振幅、锅槽倾角、凸棱个数和凸棱高度等关键设计参数进行仿真模拟,得到上述因素作用下茶叶颗粒的平均速度、平均受力与做形时间的关系曲线,并以仿真结果为依据设计三因素三水平正交试验,以成条率、碎茶率为评价指标,利用Design-Expert软件进行数据处理与回归分析,并对优化结果进行验证试验。仿真结果表明:曲柄转速、锅槽振幅和凸棱个数等对理条质量影响较大,茶叶纵向占比率随理条时间增加而升高,促使茶叶主茎脉轴线方向受力形成条状外形;以曲柄转速为195 r/min、锅槽振幅为99 mm、凸棱个数为2的最优参数组合进行验证,成条率为87.39%,碎茶率为1.85%,与优化结果基本一致。研究结果可为连续式茶叶理条机优化设计提供理论参考。

       

      Abstract: A tea carding machine is one of the key equipment in the shaping process of needle-shaped green tea. However, the key parameters are the empirical values in the traditional tea carding equipment, leading to the low carding quality. This study aims to optimize the structural and operation parameters of a continuous tea carding machine using numerical simulation and analogy methods, in order to improve the performance. The kinematics analysis was implemented to express the velocity and acceleration of the pot trough. The motion and force of the pot trough were then determined to explore the relationship between the pot trough movement and the tea carding state. The dynamic model of the tea-U-shaped groove was then established at each stage of the collision motion of tea hitting the convex edge, the rubbing movement of tea at the bottom of the U-shaped groove, the collision motion of tea and the right plate of the U-shaped groove, as well as the collision motion between tea and the left arc inner wall of U-shaped groove. The force characteristics of tea were analyzed to evaluate the tea striping in each stage of the pot trough motion cycle. A single-factor test was carried out to simulate the tea carding using EDEM software. The key parameters were simulated, such as crank rotational speed, pot trough amplitude, pot trough inclination angle, number of convex ridges, and height of convex ridges. The relationship curves were obtained among the average speed, average force, and tea carding time of tea particles. After that, a three-factor and three-level quadratic rotation orthogonal test was designed, where the strip rate and broken tea rate were taken as the evaluation index. The data processing and regression analysis were carried out using Design-Expert software. The experiments were then performed to verify the optimal model. The simulation results show that the crank rotational speed, pot trough amplitude, and the number of convex ridges shared a great influence on the quality of tea carding, where the tea particles were gradually transited from the disordered state at the beginning of carding to the longitudinal ordered state. The longitudinal proportion of tea leaves increased with the increase of time, in order to promote the formation of strip shape in the axis direction of the main stem vein of tea leaves. The orthogonal test results were processed by data processing and regression analysis. The optimal combination of parameters was obtained with the crank rotational speed of 195 r/min, pot trough amplitude of 99 mm, and number of convex edges of 2. The strip rate was 87.39%, whereas, the broken tea rate was 1.85%. The relative error with the optimization was within 5%, indicating the reliability and accuracy after optimization. The findings can also provide a theoretical reference to optimize the continuous carding machine.

       

    /

    返回文章
    返回