Design And Experimental Research Of The Rope-winding Mechanism For Round Balers

Straw is a valuable and renewable resource. But because of loose properties, scattered distribution and strong seasonality, straw is difficult to collect, transport and store. Therefore, baling harvest of straw is necessary. As the key baler of crops straw harvest, round baler has the advantages such as relatively simple structure, smaller auxiliary power and the inexpensive price. Round balers are widely used at home and abroad, more small and medium-sized steel-roll round balers are used in China’s countryside. At present, straw bales which were harvested by the steel-roll round baler developed in China, are easy to expansion in transportation and storage. Aiming at these problems, a new rope-winding mechanism for steel-roll round balers is designed, and the rope-winding mechanism was studied and analyzed by experiments in this paper, which provides theory basis for design and development of the rope-winding mechanism. The main researches are as follows:(1) Universal testing machine is used to analyze special hemp rope tensile for the round baler, experimental results show that: three factors selected in experiments have the same order influence on the maximum tension and elongation, the same contribution order is as follows: rope amount>rope length>loading speed, The most significant response of the experimental results is rope amount, rope length and loading speed have little difference. The influence rule of three factors on the maximum tension and elongation: with the increase of the rope length, maximum tension declined slowly, elongation was leveled off after decrease; with the increase of rope amount, maximum tension and elongation showed increasing trend; with the increase of loading speed, maximum tension and elongation declined slowly. Experimental results provide reference for the design of the rope-winding mechanism.(2) Under the condition of experiment, the extrusion stress variation law of rice straw was measured by the steel-roll round baler, and matching the stress relaxation equation. Under the experimental condition, the maximum extrusion stress of rice straw is 7.15 k Pa, the balance extrusion stress is 2.38 k Pa, it is the time for the rope-winding mechanism to put the rope around 20 s after finishing baling. Determination results showed that: the extrusion stress of straw bale reached maximum when baling just completed, immediately putting a rope to wrap around is not suitable at this time, then the extrusion stress declining over time and tending to be stable finally, the balance extrusion stress is the intrinsic factor of the straw bales expansion deformation. Determination results provide reference for analysis of straw bales and adjusting the time to put a rope.(3) Aiming at the steel-roll round baler, a new rope-winding mechanism is designed in this paper, this mechanism is composed of frame, rope-guiding plate, rope-guiding wheel, driving sprocket and driving gear. The Solid Works software is used to build the 3D model of the rope-winding mechanism, virtual assembly and parts interference checking on rope-winding mechanism. On the basis of the assemblage, the working process of the mechanism and the design process of the key components were introduced in this paper. The design of the rope-winding mechanism could provide technical support for the experimental research on the rope-winding mechanism.(4) According to the predetermined structural parameters, the mechanism model was simplified, imported into ADAMS virtual prototype, and ADAMS simulation model was constructed, then adding constraints and kinematic pair, double driving operating model. fitting the on the straw bale surface with movement of rope-winding mechanism. By analysis the simulation results with actual trajectory measured by experiments, the error is less than 3%, which illustrated that the simulation trajectory is extremely believable, the design of the mechanism is reasonable, the structural parameters of the mechanism has important influence on th e result, which provide basis for the rope-winding mechanism.(5) By the steel-roll round baler, the rope-winding mechanism was experimented, the contribution rate of the factors on the irregularity of straw bale: mounting distance, circle number, wheel radius; the contribution rate of the factors on the expansion rate of straw bale: mounting distance, wheel radius, circle number; the contribution rate of the factors on the consumption of ropes: wheel radius, circle number, mounting distance. Through the response surface method, the response surface models, which are about the factors and the evaluation index, were set up. The optimal parameters combination of the rope-winding mechanism determine is as follows: the circle number was 2 circle, the wheel radius was 70 mm, mounting distance was 62 mm. According to the optimal parameters combination, the irregularity of straw bale is 3.23%; the expansion rate of straw bale is 4.72%; the consumption of ropes is 2.93 kg/t.