| Rice straw loose structure makes it difficult to be collected and utilized. To make full use of rice straw, compression is the key step in the utilization. However, plugging phenomenon often appear in baling intact rice straw by the domestic small and midsize steel-roll round baler. Then, a steel-roll round baler was designed, and the steel-roll round baler was experimental studied and analyzed by applied technologies such as force analysis, dye tracing, high-speed camera and force testing in this paper, which is used to support innovative design and development of steel-roll round baler. The main contents and results are as follows:(1) Study on compression characteristics of intact rice strawt. The results showed that: Compared to the horizontal status, rice straw in the disorder status require more compression force when compressed to the same density(220kg/m3), In the status of horizontal and disorder, influence of the four experimental factors on the maximum compression force is similar: Along with the moisture content increase, the maximum compression force decrease obviously; the maximum compression force increased and then decreased gradually with the increase of loading speed. The closer to the root of rice straw, the smaller the maximum compression force was needed. But at the same initial density, along with feeding quantity increase, the maximum compression force increased and then decreased. Among the four factors, moisture content has the greatest impact on compression force, and then the rice straw sampling parts.(2) Effect of different moisture content on the sliding friction characteristics of intact rice straw. The results showed that: Along with the moisture content increase,the sliding friction coefficient between steel and rice straw increased generally. when the moisture content of rice straw in 12%~68%, the range of the sliding friction coefficient between steel and rice straw is 0.47~0.66.(3) Analysis of forming process of rotary straw core. Combine the force analysis of intact rice straw, the study of forming process of rotary straw core by high-speed camera and the mechanics measurement, we can know that the forming process of rotary straw core essentially is the process of inwinding and continuous accumulation of the rice straw in baling chamber; The traction produced by the rotary straw core on the subsequent feeding rice straw was largely; The formation of the rotary straw core mainly depends on the friction of the steel rolls on rice straw and the sustained driving force of the subsequent feeding rice straw; Baling torque needed increased linearly but the torque is generally small, steel rolls do not exert positive pressure on bale.(4) Analysis of compression-baling process. Combine the force analysis of bale, the study of compression-baling process by high-speed camera and the mechanics measurement, we can know that the compressing process of bale essentially is the process of the subsequent feeding rice straw layer inwinding and accumulation in baling chamber; Steel rolls do not exert positive pressure on bale and baling torque needed increased slowly in filling stage, then, in the compressing stage, positive pressure from the steel rolls to bale starting occurrence and the positive pressure increased slowly and then rapidly along with weight of the bale increasing, when the density reached a certain value, the lateral force of the rear chamber starting occurrence and then increased rapidly along with weight of the bale increasing, baling torque needed increased quickly and then rapidly. The radial density of the shaped bale decreases gradually from the external to the internal.(5) Experimental study of forming of rotary straw core. Test results showed that: the contributing rate of every factor on the dry mass of the rotary straw core was as follows: friction effect of the steel roll on rice straw, linear velocity of spring-finger, feeding quantity of rice straw. when the parameters of sliding friction coefficient between steel and rice straw was 0.65, linear velocity of spring-finger was2.23m/s and the feeding quantity of rice straw was 1.5kg/s, the dry mass of rotary straw core was 1.58 kg.(6) Experimental study of stress relaxation characteristics of intact rice straw during rotary compression. In experiments, moisture content of rice straw, dry material quantity of bale, steelroll speed and feeding speed of rice straw were chosen as experimental factors. Stress relaxation times and balance elastic modulus were decided as the evaluation index. Test results showed that: the stress relaxation model of intact rice straw during rotary compression could be expressed by three element equation which is available through one Maxwell unit and one spring parallel composition. The contributing rate of each factor on stress-relaxation times was as follows: moisture content of rice straw > dry material quantity of bale > feeding speed of rice straw > steelroll speed; The contributing rate of each factor on balance elastic modulus was as follows: dry material quantity of bale > moisture content of rice straw > feeding speed of rice straw > steel-roll speed. With the parameters of moisture content of rice straw was 65%, dry material quantity of bale was 17 kg, steel-roll speed was 257r/min, feeding speed of rice straw was 1.6kg/s, the stressrelaxation times was 17.08 s, the balance elastic modulus was 4.01 KPa.(7) Experimental study of power consumption of intact rice straw during rotary compression under the round baler. In experiments, moisture content of rice straw, dry material quantity of bale, steel-roll speed and feeding speed of rice straw were chosen as experimental factors, specific torque were decided as the evaluation index. Test results showed that: the range of the specific torque was 0.29~0.64N·m4·kg-1. The contributing rate of each factor on specific torque was as follows: dry material quantity of bale > steel-roll speed > moisture content of rice straw > feeding speed of rice straw, In the optimal combination of parameters(moisture content of rice straw was 65%, dry material quantity of bale was 17 kg, steel-roll speed was 254r/min, feeding speed of rice straw was 0.55kg/s), the specific torque was 0.282N·m4·kg-1.(8) Optimization of baling parameters of the steel-roll round baler. Combined the test results of the stress relaxation characteristics and the power consumption of intact rice straw during rotary compression, two group of optimal baling parameters of steel-roll round baler was determinated finally, there were as follows: ①When the rice stalk for silage, the optimal baling parameters was that moisture content of rice straw 68%, dry material quantity of bale 17 kg, steelroll speed 260r/min, feeding speed of rice straw 1.5kg/s. In these parameters, the specific torque was 0.36N·m4·kg-1, the stress-relaxation times was 21.36 s, the balance elastic modulus was 4.17 KPa. ②When the rice stalk in normal, the optimal baling parameters was that moisture content of rice straw 14%, dry material quantity of bale 16 kg, steel-roll speed 250r/min, feeding speed of rice straw 1.6kg/s. In these parameters, the specific torque was 0.41N·m4·kg-1, the stressrelaxation times was 55.86 s, the balance elastic modulus was 3.976 KPa. |
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