螺旋推进式油茶籽壳低损清选机设计及试验Design and test of spiral-propelled type Camellia oleifera seed shell low-loss sorting machine

针对现有齿光辊式油茶籽壳清选机存在“磕籽”现象，造成油茶籽损失率较高的问题，利用油茶青果脱壳后的籽、壳物理特性的差异，设计了螺旋推进式油茶籽壳低损清选机，对该清选机螺旋辊直径与长度、螺旋辊转速、螺纹形式、螺距和螺旋升角等关键参数进行设计，建立油茶籽受力模型。以清选率和油茶籽损失率为评价指标，采用单因素试验和响应面试验对清洗机工作参数喂入量、螺旋辊转速和对辊间隙进行优化。结果表明：设计的螺旋推进式油茶籽壳低损清选机螺旋辊的直径为50 mm，长度为1 000 mm,转速不超过 200 r/min，螺距为50 mm；螺纹采用双螺旋形式布置，螺纹横截面形式为直角梯形，工作倾角为120°，螺纹高为4 mm；螺旋升角为30°;优化的工作参数为喂入量1.1 t/h、螺旋辊转速170 r/min、对辊间隙12 mm，并在该清选机的上平面设计毛刷以增大清选过程中油茶壳姿态调整的概率，在此优化条件下该清选机的清选率为90.39%，油茶籽损失率为054%。综上，设计的螺旋推进式油茶籽壳低损清选机达到了预期设计目标，可以较好地完成油茶籽壳混合物的清选作业，同时大幅降低油茶籽损失率。In order to solve the problem of high loss rate of Camellia oleifera seed shell toothed-smooth roller sorting machine, using the physical properties differences of the seeds and shells after hulling of Camellia oleifera green fruit, the spiral- propelled type Camellia oleifera seed shell low -loss sorting machine was designed, the key parameters such as screw roller diameter, length and speed, thread form, screw pitch and helix angle were designed to establish a force model for Camellia oleifera seed. Taking the sorting rate and the loss rate of Camellia oleifera seed as the evaluation indexes, single-factor test and response surface methodology were used to optimize the operating parameters such as feeding rate, screw roller speed and roller spacing.The results showed that the sorting machine designed had a screw roller with diameter of 50 mm, length of 1 000 mm，speed not exceeding 200 r/min and pitch of 50 mm, and the thread were arranged in the form of a double helix， the cross-section of the thread was in the form of a right-angled trapezoid, with a working inclination angle of 120°, and the height of the thread was 4 mm; the helix angle was 30°.The optimized operating parameters were the feeding rate 1.1 t/h, the screw roller speed 170 r/min, and the roller spacing 12 mm,in addition designing brushes on the upper plane of the sorting machine to increase the probability of adjusting the posture of the Camellia oleifera shells during the sorting process. Under the optimal conditions, the sorting rate and the loss rate of Camellia oleifera seed were 90.39% and 0.54%,respectively. In conclusion, the designed spiral-propelled type Camellia oleifera seed shell low-loss sorting machine reaches the expected design goal, which can better complete the sorting operation of Camellia oleifera seed shell mixture, and at the same time significantly reduce the loss rate of Camellia oleifera seed.