Design And Research On Cam Driving Mechanism Of Picking Tip Of Comb Crocheting Machine

Mechanized harvesting of red silk is one of the necessary conditions for the development of the safflower industry.Currently,the picking method mainly relies on manual picking,which has great strength and low efficiency.Based on the current situation that the combing-type safflower picking head in the previous study of the research group could not axially tighten the filaments,a cam-driven mechanism was designed to achieve the tightening of the filaments,which was mainly studied from the following aspects:(1)Scheme design: Based on the analysis of the requirements of the motion law of the follower of the cam-driven mechanism,the application of cams designed for the polynomial motion law,trigonometric function motion,and combined motion law of the follower is analyzed.The combined motion law synthesizes polynomials and triangles.The merits of the law of movement of the function,such as small speed change and small impact,combined with the working principle of the picking head,selecting the combined motion law as the motion law of the cam follower;using the analytic method to design the cam contour curve,the basic parameters For: base circle radius 60 mm,working stroke 3 mm,push and return movement angle 30 °,far and near the angle of rest 150 °.(2)Simulation analysis: Through kinematics simulation analysis,the angular displacement of the movable comb teeth of the cam follower ranges from-395.0 to-392 mm,the working stroke of the cam is 3 mm,and the variation of the moving comb teeth speed and acceleration There is no strong fluctuation,indicating that the impact force and wear degree of the movable comb teeth and the cam end face are relatively small;at the same time,a finite element analysis module of the cam is established,in the three materials common alloy steel 28Cr4,hot forging die steel X38CrMoV5-1 and nitriding Under the static analysis of alloy steel 42Cr4,the hot forging die steel X38CrMoV5-1 has the highest cam yield stress,the least strain and the best safety factor.Combined with the working principle of the picking head,the best material for determining the cam is the hot forging die steel X38CrMoV5-1.(3)Experimental study: After the actual measurement of the cam stroke,the stroke was 2.98 mm,the distance between the movable teeth was 2.88 mm,and the average diameter of the single root of the red silk was 0.8 mm,which is much larger than the installation error 0.12 mm when clamping the filament,the hardness of the cam working face was measured as 63.6 HRC,which meets the design requirements;the high speed camera test verifies that the moving trajectory of the moving comb tooth on the cam face is a flat,smooth curve,and the follower has less vibration impact on the end face.The service life of the cam mechanism was increased,and the rationality of the selection of the follower movement law was verified again;using the secondary rotation orthogonal center combination test,the average picking success rate was 38.21%,and the optimization-in Design-Expert 8.0.6 software was used.The Numerical module optimizes and solves.After optimizing the parameters,the initial installation angle of the cam is-6.6°,the picking head speed is 48.35 r/min,and the picking head installation height is 956 mm,the best picking success rate is 65.96%.