During the harvesting of cut-stem vegetables, the structural parameters of cutters have an important influence on the harvesting effect. Structural parameters of stalks directly affect the cutting effect of the cutter. The thickness of the stalk xylem has a strong influence on the cutting stability and cutting surface effect of the cutter. In this paper, the effect of the broccoli stalk xylem on conventional toothless cutters was investigated using broccoli stalks as the cutting object. It was found that a thicker xylem leads to shear force fluctuations, which in turn affects the smooth operation of the cutting device. Taking locust mouthparts as the research object, a bionic multi-tooth cutting method is proposed in this paper to obtain the contour curve based on the locust upper jaw cutting tooth lobe. By establishing the regression equation, the contour curve of the cutting teeth is fitted accurately. The cutter edge is designed with the locust’s maxillary incisive lobe as the bionic object. ANSYS software was used to simulate the cutting of a double disc cutter and broccoli stalk. The effect of each factor was analyzed by response-surface regression to determine the optimal cutter speed, machine forward speed, cutting inclination, blade overlap, and optimal cutting position. The cutting test is verified via broccoli stalks and a cutting test bench to further determine the cutting device operating parameters. The optimal operating parameters of the cutting device were 0.239 m/s forward speed, 30.974-degree cutting edge angle, 10.066 mm blade overlap, and 467.511 rpm.

Stem cutting is the main process of broccoli harvesting, and the structure and mechanical properties of the stem significantly affect the cutting efficiency. In the current research, the structural characteristics and component contents of the broccoli stem are analyzed. Through different processing methods of stretching, compressing and bending, the aim is to obtain the parameters for mechanical properties of broccoli stem, and to provide basic data and reference for establishing visual models of broccoli stem. The test results show: The content of rind is highest in the middle of the stem, the content of xylem is highest in the bottom of the stem, and the content of pith is highest in the top of the stem. The densities of rind, xylem and pith of broccoli stem were 1056.1, 938.9 and 1009.9 kg·m⁻³, respectively. The elastic modulus of the rind of broccoli stem was 27.2~47.5 MPa, the elastic modulus of the xylem was 19.2~110.7 MPa, and the elastic modulus of the pith was 6.5~7.5 MPa. The compressive elastic modulus of the stem was 1.3~2 MPa. The bending strength of the broccoli stem was 6.9 MPa, and the bending modulus was 3.1 MPa. The mechanical model of broccoli stem established in this study provides a theoretical basis for cutting and other processes.

The briquetting technology of rice straw could increase the bulk density of the straw, reduce transportation and storage costs, and improve resource utilization. This paper analyzed the working principle of the air-conveying integrated device in briquetting machines. High-speed photography technology was used to track and record the movement process of crushed straw material in the air-conveying cylinder area. It was compared with the simulation results of the average velocity of crushed straw material to verify the reliability of the simulation. The results showed that the flow of straw scraps in the straw-shredding and air-conveying integrated device was relatively stable when the impeller speed was 630 r/min, the number of blades was three, the blades were tilted back 15°, and the radius of curvature of the air-conveying tube elbow was 700 mm. At the same time, the speed distribution was uniform, and the highest throwing speed reached 4.5 m/s to 4.8 m/s. After optimization, the average increase rate of briquette density was 2.61% and the average increase rate of briquette productivity was 2.52%. The fluid movement law of the straw-shredding and air-conveying integrated device studied in this paper could be used to optimize the air-conveying device, improve the efficiency of straw briquetting and the utilization rate of straw resources.