Test and analysis of the latest corn stalk crushin

Test and analysis of a new corn stalk crushing and stubble breaking machine

preface

as an organic fertilizer, the stalk is directly returned to the field, which is a necessary measure for stable and high agricultural yield and environmental protection. The current straw crushing and stubble breaking machine has some defects in stubble breaking quality, machine performance and so on: 1) heavy machine development, light mechanism research; 2) The accuracy of stubble breaking is poor; At present, the widely used rotary tillage machines and tools have low stubble crushing quality. The new corn stalk crushing and stubble breaking machine designed by the author adopts a knife roller part and is installed with a fixed blade. The three functions of straw crushing, stubble chopping and surface soil loosening are completed in one operation, and the experiment shows that the performance is reliable

1 working principle of straw crushing and stubble breaking machine

Figure 1 working principle of straw crushing and stubble breaking machine

corn straw crushing and stubble breaking machine uses the reverse rotation of knife roller to cut corn straw and stubble (as shown in Figure 1). The corn straw is crushed by the tractor and straw crushing and stubble breaking machine, and then moves the knife into the soil to cut off the corn root at position i, The rear moving knife pushes the cut corn stalk (including part of the stubble) to position II, and with the cooperation of the fixed knife, cuts the corn stalk and stubble. As the machine keeps moving forward, the knife keeps cutting the corn stalk at position II. The cut stems and stubbles are scattered on the ground under the action of moving knives and cover plates, and then most of them are brought into the soil by passive knives. Because the corn stalk is relatively thick and has certain stiffness and toughness, it can be cut well with the cooperation of the fixed knife. Compared with the previous machines and tools of this type, the machine has a simple structure. A knife roller shaft can complete straw crushing and stubble chopping, and a fixed blade is added to provide a support in the cutting process. Therefore, theoretically, the rotation speed of the knife roller can be reduced and the power consumption can be reduced, which provides a guarantee for further reducing the power consumption of the machine; Moreover, the machine can also be buried in shallow soil, which can not only achieve the purpose of shallow tillage, but also bury some chopped stems and stubbles into the soil

2 stress analysis of working parts

the working parts, namely the moving knife, rotate under the drive of power. When the moving knife enters the soil, its stability is poor, and it is subject to the cutting resistance generated by the soil, including the force on cutting stubbles. This resistance is the combined force of the elastic and plastic deformation force of the soil, the friction force of the soil on the surface of the working parts (including the force on chopping the stubble), the friction force of the working parts on the cutting arc on the uncultivated soil and other forces (see Figure 4). The magnitude and direction of cutting resistance are related to the geometry, motion characteristics, soil properties and working parameters of the working parts

assuming that the cutting resistance of the soil to the working parts during work is RN, the cutting resistance of the soil can be decomposed into RX and ry, and their size and direction change with the change of RN, and are related to the horizontal included angle of RN. When the moving knife rotates for a week, they are the most common instruments in the laboratories of plastic mixing manufacturers, and the cutting resistance of soil changes from rnmax to 0, reaching the maximum at the lowest point. For the vertical component ry, when the forward speed is small, it almost remains unchanged, but when the forward speed increases, it will increase sharply

the process of cutting soil is periodic, which includes squeezing, cutting and tearing soil slices. In a cutting cycle, the change of soil resistance for grass roots reaches 30% - 40%. The more dry and solid the soil is, the greater the change is. On the contrary, the cutting force of plastic soil is almost unchanged

3 test and analysis

3.1 selection of test methods and test factors

orthogonal design is proposed for this test, and its mechanical properties can still maintain the initial 80%; 5. Method of weak acid resistance test. Orthogonal test method is a scientific test method to deal with multi factor tests. With this method, only a few tests can be done to judge the better combination. If the test results are simply statistically analyzed, the test results can be more comprehensively and systematically mastered and the correct judgment can be made. Due to the field test, the selection of factors and levels will be limited by some actual conditions, especially it is difficult to change the level. Finally, three factors are selected: the rotation speed of knife roller, the forward speed of machine and the inclination angle of moving knife. The rotation speed of the knife roller is three levels, the forward speed of the machine is three levels, and the inclination angle of the moving knife is two levels. As shown in Table 1. Table 1 test factor level table

3.2 range analysis of orthogonal test table 2 orthogonal test results and range analysis

this test is to study the influence of changes in various levels on the two indicators of crushing power consumption and crushing qualification rate. The lower the crushing power consumption index value, the better; The higher the index value of crushing qualification rate is, the better. Therefore, the data processing of regression orthogonal test is measured by comprehensive indicators. The calculation method is: first, the two indicators of crushing power consumption and crushing qualification rate obtained from the test are dimensionless, that is, the percentile scoring is carried out, the minimum value is 0, the maximum value is 100, and the corresponding scoring values of other values are calculated according to the size, Take the power consumption as an example to illustrate the calculation process:

where: P - the power consumption value here; Pmin - minimum power consumption in the test; Pmax - maximum power consumption in the test; Y power consumption - the score value after dimensionless processing. In the same way, we can get the score value y after dimensionless treatment of crushing qualification rate

the test prototype has done preliminary tests before, and the crushing qualified rate is good, but the disadvantage is that the power consumption is particularly large. Therefore, when calculating the comprehensive index, the weight of crushing power consumption should be larger so that there is no conflict in production. Therefore, the weight of crushing power consumption is taken as -0.7, because the lower the crushing power consumption is, the better. The weight of crushing qualified rate is taken as 0.3, and the higher the crushing rate is, the better. The comprehensive score obtained by multiplying the scores of the two by their respective weights is the comprehensive index value

the higher the comprehensive index value, the better. The calculated comprehensive index values are shown in Table 2. K1, K2 and K3 are the sum of comprehensive indexes at all levels, and R is extremely poor

4 conclusion

from the average value and range R of the sum of the comprehensive index, it can be seen that the primary and secondary factors affecting the comprehensive index are C, a and B, that is, the forward speed of the machine has the greatest impact on the comprehensive index, followed by the speed of the knife roller, and finally the moving knife. The better combination of factor level is a2b1c1, that is, the rotating speed of knife roller is 582r/min, the inclination angle of moving knife is 6 °, and the forward speed of machine is 0.67km/h. If considering the productivity, the most suitable working speed for the tractor used in the test is 2.9km/h. At this time, the suboptimal combination is a1b3c3, that is, the speed of the knife roll is 480r/min, the inclination angle of the moving knife is 6 °, and the forward speed of the machine is 2.9km/h

Guan Wen --- has been engaged in machinery teaching and scientific research in Colleges and universities for 15 years, and is now the local editorial board member of agricultural machinery magazine. This article was recommended by Guan Wen to agricultural machinery 2009.2