Design And Research Of Clamping Comb-type Safflower Picking Device

With the increasing of the planting area of Safflower in Xinjiang,problems such as low efficiency of artificial picking,high labor intensity and serious filaments residue are becoming increasingly prominent.The development of safflower industrialization is seriously restricted,so it is urgent to realize mechanized picking of safflower.At present,the research of safflower picking machinery is mostly focused on air suction,air-suction-comb shearing,there are many problems such as high energy consumption,low efficiency,serious drop loss and so on,which have not been popularized and applied.The difficulty of mechanical picking of safflower is that the branches are flexible,the position of flower ball is difficult to fix,and the height of flower ball is different.The clamping comb-type picking device was developed by this research group,the position of the flower ball was fixed under the joint action of comb teeth and limit rod,and then comb teeth clamped the filaments and rotated to realize the filaments drawing,which has great significance to improve the picking efficiency and realize the mechanized picking of safflower.Through the study of the physical characteristics and picking mechanical properties of safflower,the paper provides a reference for the design of picking device.The height of safflower,the effective picking height,the diameter of branch and the variation range of diameter of flower ball were measured;The moisture content of branches in flowering 3d~6d was not changed much,the moisture content of filaments in flowering 3d~4d was 65%~80%,and the moisture content of 4d~6d in flowering decreased sharply to30%;the branch density was 0.7244 g/cm~3 and flower ball was 0.2091 g/cm~3;the minimum friction coefficient between filaments and filaments was 0.23,and the minimum friction coefficient between filaments and die steel was 0.45.The releationship between filaments strectching resistance,the gripping number and the moisture content was built,and the elastic modulus and bending strength of brunch were obtained by three point bending test.Through the analysis on demand of picking safflower,whole clamping comb scheme was determined and the ideal picking process was put forward.The key parts of the picking device are designed and the structural parameters are determined by the calculation of parameters and mechanical analysis of combs.The kinematic simulation analysis of reciprocating mechanism was carried out,and the result showed that the movement of the designed picking device was stable and impactless.The combing strength was checked and the designed picking device met the design requirements.Based on ansys/ls-dyna platform,a simplified picking model of combing clip was established and the process of combed picking was analyzed.By analyzing the effects of different structures and motion parameters of comb-picking device on the motion posture of flower balls and branches,the optimal parameters were determined.The working speed was 0.7m/s,the combed teeth rotation speed was 150r/min,the horizontal distance between the axis of the limit bar and the center of the comb teeth rotation was30mm,and their installation center distance was 85 mm,which can pick the relative height of 30 mm flower ball with comb teeth.The main work of combing is the top of the teeth,which is independent of the length of the comb.The angle from the teeth crest from contact with filaments to away from filaments were60°and 70°with horizontal direction respectively,the combing angle was10°.By optimizing the structure of combed picking device,the angle of cam clamping was 10°,the number of comb rows was 6,and the contact area between the top of comb teeth and filaments was increased in order to increase the feeding quantity of filaments.The physical prototype of comb picking device was constructed.The theoretical design of the picking device was verified by measuring the clamping force of the comb teeth,the accuracy of virtual picking model was verified by high-speed camera test and picking test.The test results show that 56%of the flower balls can reach the ideal picking position,and the average recovery rate of a single flower ball was 48.5.