The spindle is a key core component of a cotton picker, and its operating parameters directly affect the quality of cotton harvesting. In this study, the spindle was selected as the research object. The kinematics and mechanics analysis of the cotton-picking process was conducted, the dynamic motion trajectory of the spindle was obtained, and the working parameters affecting the picking performance of the spindle were determined. A test bench for spindle picking performance was built; the spindle speed and feed speed were used as test factors; the seed cotton rejection rate, picking time, and picking force were used as evaluation indices for spindle picking performance; and a full-factor test was conducted. The range, variance, and regression analyses were conducted on the test results, and the results showed that spindle speed and feed speed had significant effects on seed cotton rejection rate, picking force, and picking time (p < 0.01). The primary and secondary order of factors affecting seed cotton rejection rate and picking time were spindle speed and feed speed, and the primary and secondary order of factors affecting picking force were feed and spindle speed. By comprehensively analyzing the influence of factors on the evaluation indices, the best combination was obtained as the spindle speed and feed speed of 4000 r/min and 1.8 m/s, respectively. The research results have theoretical research value and practical significance for revealing the picking law of spindles when rotating at a high speed and then realizing efficient cotton harvesting.

This study investigated the impact of compression molding parameters on the post-molding characteristics of machine-harvested seed cotton and aimed to determine the optimal compression molding parameters. The closed compression test of seed cotton and force analysis on a single cottonseed clarified the boundary conditions for cottonseed crushing and the relationship between crushing rate and compressive force. A seed cotton compression test bench facilitated single-factor and four-factor, three-level quadratic regression orthogonal experiments, varying the moisture content, initial density, compression force, and holding time. Variance analysis revealed each factor’s influence on the dimensional stability coefficient. Utilizing Design Expert 13.0.5, the optimal compression molding parameter ranges were identified: 6–11.7% moisture content, 47.87–74.84 kg/m³ initial density, 3–5.32 kN compression force, and 50–239.75 s holding time. Software predictions within this range indicated an optimal cottonseed crushing rate and dimensional stability coefficient of 2.853% and 3.274, respectively. Further verification experiments yielded a cottonseed crushing rate and dimensional stability coefficient of 2.888% and 3.282, respectively, with a maximum error of 3.85%, validating the model and optimized parameters. Therefore, strictly controlling seed cotton compression molding parameters was shown to reduce the cottonseed crushing rate and dimensional stability coefficient. These findings offer crucial theoretical insights for developing seed cotton compression processes and selecting parameters for cotton harvesting and packing devices.