Small and scattered fields are found for the rapeseed production in the hilly and mountainous regions. It is still lacking on in the mechanized threshing and cleaning equipment for rapeseed. The large grain loss is also observed during the operation of small-sized threshing and cleaning equipment. This study aims to propose a rapeseed harvesting scheme in the hilly areas. The functions of the forced feeding can be integrated by fish-scale double pressure rolls. The threshing and separation can be combined with the rasp bars and spike teeth, and cyclone separation. The 5TYC-120A type rapeseed threshing machine was developed in the production area. The overall structure of the rapeseed threshing machine was determined using the kinematic and dynamic analysis. The parameter range of the forced feeding device was determined with the fish-scale double pressure rolls, in order to realize the adaptive clamping and conveying of the feeding quantity. The threshing and separation device was combined with the rasp bars and spike teeth. The cyclone separation cleaning device was determined for the key influencing parameters on the threshing and cleaning performance. Taking the rapeseed threshing machine in the production area as the test platform, single-factor tests were carried out to determine the influence of the rotational speed of the fish-scale double pressure rolls, the rotational speed of the threshing drum, the threshing gap, and the wind speed at the debris suction opening on the operation performance. The optimal ranges of the parameters were determined after the test. The rotational speed of the threshing drum, the threshing gap, and the wind speed at the debris suction opening were selected as the test factors. A three-factor and three-level quadratic orthogonal combination test was carried out with the loss rate and impurity content rate as the evaluation indexesindices. The regression models between the evaluation indexes and the test factors were constructed after multi-objective parameter optimization. The optimal combination of the operation parameters was determined as follows: The rotational speed of the threshing drum was 450 r/min, the threshing gap was 27.5 mm, and the wind speed at the debris suction opening was 15.76 m/s. The results of the field verification tests showed that, under this optimal parameter combination, the average of threshing loss rate was 3.32%, the average of cleaning loss rate was 1.46%, and the impurity rate was 3.98%. . This finding can also provide a strong reference to optimize the low-loss threshing and cleaning during rapeseed harvesting.

Existing rape combine harvester with a cyclone separation cleaning device has the challenge that the loss rate and the cleaning rate increase and decrease simultaneously. A cleaning process route was proposed, which involves the cyclone separation cleaning device removing light and tiny impurities, and the cylinder sieve device removing coarse and long impurities such as pod shells and short stems. A novel cleaning system combining the cyclone separation cleaning device and cylinder sieve cleaning devices was designed. The ranges of the structure and operation parameters for each component were analyzed based on kinematics and dynamic analysis. A four-factor five-level quadratic orthogonal test was carried out, in which the loss rate and cleaning rate were taken as the evaluation indexes. The velocity at the suction port, the rotation speed of the cylinder sieve, the screw pitch of the spiral blade and the diameter of the sieve hole were taken as the influencing factors. The orthogonal test results showed that the cleaning system performed best at a rotation speed of the winnower is 600 r/min, an airflow velocity at the suction port is 18.25 m/s, a rotation speed of the cylinder sieve is 87 r/min, a screw pitch of the spiral blade is 440 mm and a diameter of the sieve hole is 4.48 mm. At this time, the loss rate of the cleaning system is 3.22%, and the cleaning rate is 95.67%. Compared to the conventional cyclone separation cleaning device, the loss rate is reduced by 2.17% and the cleaning rate is increased by 1.05%. This study can provide a reference for the optimal cleaning system design for rape combine harvesters.

The relationship between the parameters of the bonded-particle model and the macroscopic properties of oilseed rape shoot stalk provides valuable insights into the interaction between the stalks and harvesting machinery. In this study, a discrete element model of oilseed rape shoot stalk was constructed using a method that combined ordered and bimodal distribution filling. The model’s six contact and five bonding parameters were calibrated based on physical and simulated diametral compression tests. The Plackett-Burman design was employed to screen the effects of the parameters on the rupture force. The range of significant parameters was determined using the steepest ascent test. Furthermore, by calculating the second-order regression model and analyzing the significance of parameter combination using the central composite design method, the optimal parameter combination was identified, including a bonded disk radius of 0.78 mm, a normal stiffness per unit area of 4.61×10⁷ Pa, a shear stiffness per unit area of 5.21×10⁷ Pa, and a coefficient of static friction between particles of oilseed rape shoot stalk of 0.47. The simulated rupture force (58.80 N) differed by 6.5% from the average value of the physical test (62.92 N), and the deformation of the compression process was consistent. The results demonstrate that the model effectively reflects the mechanical failure properties of oilseed rape shoot stalk during the diametral compression, providing a reference for modeling other crop stalks and aiding in the study of interactions between clamping-transporting devices and stalks during harvesting.