| As one of important biomass resources, crop residue can be utilized in many ways. The efficient utilization of crop residue will be in favor of the sustainable development of agriculture and rural areas. Due to the disperse and low-density characterizations of crop residue, it is very difficult for the efficient collection of crop residue. The application of squared baler, which can compress crop residue into high-density and regular bale, plays an important role in breaking the bottleneck of collection of crop residue. D-bale knotter as the key equipment of squared baler affects the knotting rate and baler quality. This study aims to the following issues:reverse reconstruction of D-bale knotter and the precision analysis of all the reconstructed working surfaces; the motion simulation and the time sequence analysis of reconstructed D-bale knotter; and the mechanical analysis of bill hook during straw baling. Detailed contents are as follows:1. The surface point data of D-bale knotter were obtained by Handy SCAN700TM laser scanner. These data were used to build the3D models of D-bale knotter based on reverse reconstructed technique. The precision analyses on all the reconstructed working surfaces were carried out. The results showed that more than90%of surface domains arrived to accurate level and therefore the reconstructed D-bale knotter with high precision can meet the requirements of its motion simulation.2. Reconstructed parts of D-bale knotter were assembled in Solidworks software. The reconstructed D-bale knotter was run and no interference phenomenon was found. The freedom degrees of twine holder, bill hook, and wiping arm were calculated. The results showed that they can meet the motion requirements of D-bale knotter. The motion simulation of reconstructed D-bale knotter was carried out. The angular velocity and angular displacement data of card line wheel, bill hook, upper jaw, and dropping rope rod were obtained. The time sequence analysis of reconstructed D-bale knotter was further analyzed:the card line wheel firstly rotated, the bill hook rotated after0.03s, the upper jaw splayed after0.06s, the dropping rope rod wiggled after0.11s, the former three parts stopped after0.12s, and the dropping rope rod stopped after0.34s.3. Baling experiment was carried out using Huade9YFQ-1.5baler. The experimental scheme of tension sensor, high-speed camera, and synchronous control was firstly proposed. The rope tension and acting position between rope and knotter during crop residue baling were obtained. The transfer model of rope around stump was built. The results showed that the highest interaction force between rope and bill hook was314.89N. Based on the interaction force and acting position, the finite element mechanical analysis of bill hook was performed by ANSYS. The results showed that the stress concentration happened between the shaft end of bill hook and the stress arrived to755.52MPa. Two solutions were proposed to decrease the stress concentration and extend the lifetime of D-bale knotter. |
