The ultrasonic vibration-assisted milling process was used to study the difficult-to-machine aerospace material titanium alloy TC4 and explore the milling parameters that fit the processing. Based on the orthogonal experimental method, the changes in cutting force, roughness, and surface morphology under conventional and ultrasonic-assisted milling conditions were studied, and the relationship between various processing parameters and their effects was obtained. The results showed that the cutting force was most affected by the feed per tooth and cutting depth. Adding ultrasonic vibration could change the surface texture and significantly impact roughness. By adding an appropriate amplitude of ultrasonic-assisted milling, the maximum average cutting force can be reduced by more than 20.66%, and the maximum surface roughness can be reduced by 44.23%, making the workpiece surface produce regular “sine/cosine” patterns and improving the surface quality of the workpiece. Compared with conventional milling, the deformation layer of the workpiece slightly increased under ultrasonic-assisted milling. The cutting force and surface roughness of titanium alloy TC4 under ultrasonic-assisted milling were reduced. A reasonable selection of processing parameters can further improve cutting force and other parameters, providing a reference basis for the processing of aerospace materials.

This study aimed to develop a longitudinal ultrasonic-assisted milling system to investigate the machinability of titanium (Ti) Alloy Ti-6Al-4V (TC4). Aiming at reduced milling force and enhanced surface quality, ultrasonic-assisted milling was investigated taking into account the following processing parameters: spindle speed (cutting rate) n, feed per tooth f_z, milling depth a_p, and ultrasonic amplitude A. A comparison was made with conventional milling. The results of univariate tests demonstrated that the ultrasonic amplitude had the most significant impact on the milling force along the z-axis, resulting in a reduction of 15.48% compared with conventional milling. The range analysis results of multivariate tests demonstrated that a_p and f_z were the dominant factors influencing the cutting force. The minimum reduction in the milling force in ultrasonic-assisted milling along the x-, y-, and z-axes was 11.77%, 15.52%, and 17.66%, respectively, compared with that in conventional milling. The ultrasonic-assisted milling led to reduced surface roughness and enhanced surface quality; the maximum surface roughness in ultrasonic-assisted milling was 25.93%, 36.36% and 26.32% in terms of n, f_z, and a_p, respectively. In longitudinal ultrasonic-assisted milling, the periodic “separation-contact” was accompanied by microimpacts, resulting in even smaller intermittent periodic cutting forces. Hence, regular fish scale machining mesh was observed on the processed surface, and the workpiece surface exhibited high cleanness and smoothness. The reasonable configuration of ultrasonic-assisted milling parameters can effectively improve the milling force and surface quality of Ti alloys and accumulate reference data for the subsequent machining process research.

The mechanical harvesting of corn has always been a problem for the development of the corn industry. In the present investigation, a tangential flow–transverse axial flow threshing test system was designed based on the 4YL-4/5 harvester. The structure design was modular, and the threshing drum and other key parts could be changed, or the technical parameters could be adjusted according to the needs. Thus, the system becomes suitable to carry out the threshing test of various grains. In this paper, two kinds of systems, a cylindrical plate-tooth mixed row threshing drum and a full cylindrical threshing drum, were designed. Using the same materials and technical conditions, a comparative experiment of the corn grain harvest was carried out to explore the mechanical–technical conditions and methods to reduce the grain breakage rate of corn’s direct harvest.The results showed that the threshing ability and adaptability of the cylinder with a plate-tooth mixed arrangement structure were higher than those of the full cylinder arrangement structure. It was also found that for a higher moisture content (above 28%) of the maize ear, the grain breakage rate met the national standard. On the other hand, the cylinder with a plate-tooth threshing drum can support a wider range of moisture contents and drum peripheral velocities than the full cylinder threshing drum. Within the range of all tested moisture contents and drum peripheral velocities, the minimum grain breakage rate of the full cylinder tooth drum was 3.7%, and the minimum grain breakage rate of the cylinder with the plate-tooth threshing drum was 1.5%, which means a reduction of 59.5% of the breakage rate was achieved.

This study attempts to optimize the arc-shaped coned disk affecting the uniformity of the earlier designed fertilizer apparatus (FA), in particular, for application in the rice–oil rotation region in the middle and lower reaches of the Yangtze River, China. Based on theoretical analysis, a circular coned disk with the curvature gradual decline (GD) from top to bottom was designed, and the equation of the circular cone was determined. The EDEM discrete element software was used, using the coefficient of variation of the fertilization amount consistency in every row, the coefficient of variation of the fertilization amount stability, and the coefficient of variation of the fertilization amount consistency in the same row as evaluation indices. Simulations and comparative tests of FA performance were performed for three cases of the busbar top-to-bottom curvature variation: (i) gradual increase (GI), (ii) gradual decline (GD), and (iii) zero (0) variation. The experimental results show that at the FA rotation speed of 100~120 r/min and tilt of 1°~5°, the optimized FA had the optimal performance. High tilts and low rotation speeds provided the worst performance, with the variation coefficient of inter-row fertilization amount consistency of the FA below 10.23%. The variation coefficient of fertilizing amount stability was lower than 6.74%. The variation coefficient of intra-row fertilizing amount consistency was lower than 3.52%, while all performance indicators met the quality requirements of fertilizer discharge. Bench tests of the FA revealed that the variation coefficient of inter-row fertilizing amount consistency of the FA was below 10.23%, the variation coefficient of fertilizing amount stability was below 6.74%, and the variation coefficient of intra-row fertilizing amount consistency was below 3.52%. Field tests of the FA revealed that the variation coefficient of inter-row fertilizing amount consistency was below 7.68%, the variation coefficient of fertilizing amount stability was below 4.95%, and the variation coefficient of intra-row fertilizing amount stability was below 3.57%. All parameters were better than the industry standard, demonstrating that the FA had good fertilizing performance and met the quality requirements of field fertilization operations.

To improve the pod-picking efficiency of the combine harvester for both peanut seedlings and peanuts, a longitudinal axial flow pod-picking device is designed in this study. The fixation and adjustment modes of the pod-picking rod were determined. The pod-picking roller’s rotational speed, the pod-picking roller’s diameter, the pod-picking roller, the pod-picking roller’s effective rod-picking length, and the screw-feeding stirrer’s critical parameters were determined by theoretical calculation. A combined design of quadratic regression orthogonal rotation was achieved by using Box-Behnken design (BBD) response surface optimization analysis in Design-Expert, with the linear speed of the pod-picking roller, the clearance between the concave screen and the pod-picking roller, and the spacing between the pod-picking rods as the testing factors, and the picking rate and the crushing rate as the indicators. The optimized parameters are as follows: a linear speed of the pod-picking roller of 6.8 m/s, a clearance between the concave screen and the pod-picking roller of 28.5 mm, and a spacing between the pod-picking rods of 18.60 mm. The performances of conventional peanut full-feeding pod-picking devices and the proposed peanut root-disk full-feeding longitudinal axial flow pod-picking device were investigated and compared to clarify the pod-picking performance of the proposed peanut root-disk full-feeding longitudinal axial flow pod-picking device under optimized parameters. The results showed that the picking and crushing rates of the proposed peanut root-disk full-feeding longitudinal axial flow pod-picking device under optimized parameters were 98.93 and 1.62%, respectively, both of which were superior to those of conventional peanut full-feeding pod-picking devices. A pod-picking device matching the combine harvester for peanut seedlings and peanuts was processed under optimized parameters. Field tests revealed that the picking and crushing rates of the proposed harvester were 99.07 and 1.58%, respectively, meeting the industry standards. These findings are instrumental in the further improvement of peanut pod-picking devices.

The amplifier rod, also known as a concentrator, is an important component in ultrasonic transducer devices. Its main functions are amplitude amplification and impedance matching, playing a crucial role in ultrasonic machining systems. This article conducts modal analysis and harmonic response analysis of the horn and the tool-added horn, using simulation software, gradually studying the dynamic performance of the catenary linear horn in ultrasonic machining. The optimized frequency of the amplitude rod is obtained, and the effect of the resulting vibration frequency in actual processing is verified through atomization effect tests. The results show that the resonance frequency obtained by finite element analysis has a small error with the actual test, only 0.789%, and magnification error of about 0.165%, which meet the design requirements. It provides reliable design basis and data foundation for the engineering application of the variable rod in ultrasonic machining.