Abstract:
The cold and dry winter climate has posed severe threats to the freezing damage and even death to grapevines in the open-field grape cultivation areas, particularly in northern China. It is also essential to prune and lay down the vines before winter for the appropriate cold protection, especially for the high-quality and yield of grapes in the following year. Among them, the cold-proof covers have been widely adopted for cold protection, due to the moisture retention, thermal insulation, reusability, and effective prevention of sandstorms. A low-cost and efficient measure is often required for sand control. However, the current manual laying and rolling operations of cold-proof covers have also limited the large-scale production in recent years. In this study, a multifunctional integrated machine was designed for the rolling and laying operation on the cold-proof covers. The high operation efficiency and low labor intensity were also achieved in the spring rolling and winter laying of cold-proof covers in cold-proof areas. Several components were mainly composed of the machine: a main frame, an auxiliary frame, a hydraulic system, a winding core, and a cover spreading frame. The whole machine was connected to the rear of a tractor using the three-point suspension. The high-efficiency rolling of the cold-proof cover was realized in the reverse forward rolling mode; The self-weight of the cold-proof cover drove the winding core to rotate during laying, particularly for the automatic laying. A flexible media model of the cold-proof cover was established using RecurDyn/MTT3D (Media Transport Toolkit 3D). The modeling parameters were calibrated after the simulation. The generation mechanism of wrinkles during rolling was analyzed using simulation and theoretical research. An auxiliary flattening scheme was proposed with the cover spreading frame. Taking the height of the winding core from the ground, the depression angle, and the flattening angle of the cover spreading frame as the experimental factors, the Box-Behnken experimental design was adopted for parameter optimization. The optimal operation parameters were obtained as follows: The height of the winding core from the ground was 1400 mm, the depression angle of the cover spreading frame was 10°, and the flattening angle was 120°. The flattening rate reached 98.2% with a traction resistance of 335.7 N after simulation under the optimal parameters. A prototype was manufactured for the field experiments. The cold-proof cover was effectively distributed to both sides under the action of the cover spreading frame. The winding was relatively flatly rolled during operation. The actual flattening rate was 97.6%, with an error of only 0.6 percentage points, compared with the simulation. The rolling efficiency of the machine was 21.1 seconds per cover, and the laying efficiency was 16 seconds per cover. The machine can fully meet the operational requirements of rolling and laying cold-proof covers for grapes in northern China. The findings can offer technical references on cold-proof cover rolling and laying machinery.