Working Mechanism And Experimental Research On Key Components Of Vertical Roll-type Corn Harvester

Lying at the world golden corn production region, the Songliao Plain, the three northeast provinces of China are charged with an important task of national food security. Since the twenty-first century, the mechanization level of China's major crops has rapidly increased. By the end of 2008, integrated mechanization level has reached more than 45%. At the time of harvest mechanization for wheat is basically realized and for rice has been greatly developed, the harvest mechanization level for corn, one of the three major crops, is unsatisfactory with average level of less than 10%.Mechanized harvesting of corn is region dependable. We should make research and develop machine models based on specific growing conditions, agronomic requirements applicable to local conditions. Based on some characteristics in Northeast China such as ridge planting, big planting density, high yield, sturdy plant and stalk recovery, and intergrated into my study as a leader in recent years on Jilin Scientific and Technological Development Projects"Research on Snapping Mechanism and Snapping Roll Parameters of Corn Harvester"(Project number is 20060541) and" Collaborative Research on Vertical Roll-type Corn Harvester Key Components "( Project number is 20070711), this paper chooses the topic of" Experimental Research on Working Components of Vertical Roll-type Corn Harvester" as a research direction. It starts from theoretical analysis and basic experiments with a view to provide technical support for the development and designing of corn harveser.For corn harvesting mechanisation, an important reason for its slow development will contribute to its strong seasonal feature and short appropriate havesting time. In order to shorten the cycle of this experimental research, for the first time, this paper establishes a multi-parameter adjustment corn harvest test bed based on virtual instrument technique. Through theoretical and lots of experimental analysis during three years, the paper makes exploration on the snapping mechanism of the vertical roll-type corn harvester, improves and perfects the structure and configuration of various working parts, and analyses the effect of motion parameters and components structure on operating performance and harvest loss of the corn harvester. Also a large number of experimental data is processed by orthogonal test method, and through variance and range analysis, the effect degree of motion parameters on harvest loss and power consumption is determined, the best combination of motion parameters is discovered. A neural network prediction model, which can make a more reasonable forecast on operation effects of different parameters combinations, is set up based on the measured data during tests.The main results achieved are:1) Through theoretical and experimental analysis, the paper makes exploration on the snapping mechanisms of vertical roll-type corn harvester. That is, the snapping mechanisms are mainly lies at the squeeze of snapping ribs on the husk of big ear end, the impact of snapping ribs on the big ear end, the squeeze of base snap roll circle on the ear stem, the bending force of snap ribs on ear stem, and other reasons.2) The paper makes analysis on principles and conditions of smooth roll and toothed roll, and verifies that the friction theory and rolling equation also applies to research on toothed roll pure tension snapping. A twist snapping method is proposed, and its feasibility was demonstrated. Theoretical studies have shown that twist snapping can effectively reduce the required pull force and positive pressure on big-ear compared with pure tension, thereby reducing power consumption and shattering loss.3) To solve the poor reliability of vertical roll-type corn harvester, a new clamping parts drive solution is developed, that is, the clamping chain driving sprocket is separated from the snapping roll and configured in front of it. Tests showed that this solution effectively eliminates the additional tension of stalk on the chain, solves the problems of chain drop and rupture. The service life of chain is greatly improved.4) The structure of clamping transportation passage is improved. The compression spring is replaced with a tension spring, therefore the problem of clamping passage blockage and stuck is solved and equipment reliability is improved.5) A good test result is achieved when helical hook claw rolls on horizontal roll-type are applied to the vertical roll-type and the double rows roll is replaced with a single row roll.6) The chopping knife with curved surface and straight edge is applied to corn stalk chopping device. This unit is not only simple in structure, good in quality, but also can complete throw and recovery. It is an ideal type of component for stalk chopping and recovery. With the characteristic of wear-resistant and good smashing effect, T-type rotary tool is the preferred type for field straw chopper.7) Impact of the type of peeling roll on the index of grain broken rate is extremely significant, impact of roll resolution on the index of production is extremely significant; impacts of the type and angle of peeling roll on peeling rate is significant. The best combination of parameters: peeling roller inclination of 10 degrees, revolution of 350rpm, suppression device revolution of 35-45rpm and B-type peeling roll.8) During snapping process, the main factors that contribute to shattering loss indicator are snapping roll parameters, such as speed, roll type (confidence level 95%), etc., followed by clamping chain conveyor speed. Its power consumption is also depends on the type and the speed of snap roll.9) The best-fit values for the performance parameters are: snap roll resolution of 1000rpm, clamping chain speed of 2.7 m/s, operating speed of 1.67 m/s and of dome pattern snap roll.10) For the established neural network prediction model, some indicators such as harvest losses and power consumption will be predicted only if you input parameters such as snap roll revolution, clamping chain speed, operating speed, feeding number and other parameters. Its characteristics are convenient, rapid and high degree of generalization.Major innovations:1) A vertical roll-type corn harvester test bed is studied and designed, also a test control system based on virtual instrument technique is developed. They provide means for the research and development on corn harvester key components, effectively avoid the shortcomings of field test and solve the problem of short appropriate harvest time. The test control system adopts SCM intergrated with electromagnetic governor motor controller. Not only several units inter-linkage, but also a single unit independent testing is realized, which leads to more convenient operation and more precise control.2) Applying theories of kinematics and dynamics, the paper firstly made comprehensive analysis on the working mechanism of the key corn harvester components such as conveyor, snapping, peeling and stalk shattering parts and established the related models, which provides a theoretical basis for the design of key components. And thus some bottleneck problems that has long constrainted the working performance and reliability of vertical roll-type corn harvester, such as low snapping efficiency, large shattering loss, chain drop and shortage with clamping transportation components, blockage and stuck of stalk compression mechanism and so forth, are solved.3) Aiming at the structure and operating parameters for vertical roll-type corn harvester key working components, a large number of experiments are made using orthogonal experimental design method. The paper makes analysis on primary and secondary factors that affect the working performance and puts forward the best combination of structural parameters and operating parameters which provides a reliable practice basis for the design of complete machine and key components of vertical roll-type corn harvester.4) On the basis of a large number of experiments at vertical roll-type corn harvester, some prediction models that aiming at impropant indicators of operating performance such as power consumption and shattering loss are set up using orthogonal experimental design combined with neural network analysis method,which provide means for corn harvester automation, performance analysis and numerical simulation, it is convenient, rapid and has high degree of generalization compared with experimental measurement method.The study in this paper is closely linked with the actual production. In 2008, our institute cooperated with Anshan Haihong Machinery Companies and successfully developed a 4YZL-4 self-propelled vertical roll-type corn Harvester. The working components of this machine are basically come from the research result of this paper, a good test result was achieved in the fall test. In 2009, the machine carryied out small-volume production, and is included in the "2009 National Agricultural Machinery Promotion List" and "2009 Liaoning Province Agricultural Machinery Product Subsidize Purchase Catalog." In the same year, 4YZL-4 self-propelled corn harvester obtained utility model patent (patent number: 200820014663.4), and also the invention patent is in pending status.