Design and performance test of rapeseed harvest disc cutter LI Zhong-yi XIE Fang-ping, LIU Ke, TANG Xiang, WANG Xiu-shan, MAO Li-cheng1 (1. College of Engineering, Hunan Agricultural University, Changsha 410128, China; 2. Hunan Modern Agricultural Equipment Engineering Technology Research Center , Changsha 410128, Hunan, China, to study the biophysical properties of single rapeseed, and the height of the rapeseed is 200400mm. The self-propelled self-propelled cutting test device is used to cut the cutting power and the loss of the grain. Single factor and multi-factor orthogonal tests were carried out for cutting height, cutter head inclination and the like. The single factor test results show that the cutting power consumption is 30.19W and the falling weight loss is 1162 when the cutting speed is 700r/min, the cutting height is 300mm, and the cutter head cutting inclination angle is 10. The results of orthogonal test show that the cutting speed is 750r/min, the cutting height is 250mm, the cutting angle of the cutter head is 10°, the forward speed of the device is 0.4m/s, and the blade is the best parameter. It is similar to the orthogonal No. 5 test. It consumes 36.39W and loses 895 grains.
Fund Project: National "Twelfth Five-Year Science and Technology Support Program Project (2011BAD20B08); Hunan Provincial Science and Technology Department Key Project (2013F2006) According to statistics, the average mechanized planting area of ​​rapeseed planting area in the past five years reached 6.914 million hm2, but the average mechanical harvested area Only 223,000 hm2. The rapeseed combine harvester is modified on the basis of the existing rice-wheat combine harvester. Due to the biological characteristics of the overall maturity of the rapeseed plants, and the vibration of the reciprocating cutter during operation, The rapeseed kernels are dropped more, resulting in a large loss of the harvesting of the header. The average harvest loss of rapeseed is 8.54%, and the loss of the header is 7.69%. Therefore, it is necessary to reform the reciprocating cutter to make it more suitable for rape. reward.
Research on disc cutters for sugarcane, corn, soybean and other crops has yielded results. In view of the biological characteristics of the maturity of rapeseed, combined with the structure of the cutter and the blade, the author designed an eccentric arc serrated blade disc cutter. The influencing factors such as cutting speed, cutting position and cutting inclination are selected, and performance tests are carried out on the self-propelled cutting device in order to obtain the optimal working combination of the rape disc cutter.
1 Disc cutter design and working principle 1.1 Disc cutter structure and blade parameter selection Considering that the disc cutter disc is easy to balance and vibrate when rotating at high speed, the eccentric arc blade edge slip angle is outward Gradually increase, saves effort and labor when cutting, and has a cutting buffer effect; sawtooth cutting power consumption is low, low resistance, and has a clamping effect, etc., the blade is designed in the form of an eccentric arc serrated blade, and is connected by bolts. Evenly arrange 6 knives on the plate. The blade of the cutter should have the characteristics of wear resistance, high hardness, small deformation and good toughness. Under the premise of ensuring good cutting efficiency and low breaking rate, according to the diameter of the stem of the rape, the cutter cutter blade and the blade parameters are determined. The blade material is 65Mn steel, the cutter disc diameter is 200mm, the cutter height is A=30mm, the knife width is 30mm, the blade thickness is d=2mm, the cutting edge of the cutting edge curve is 30, and the end slip angle is 60°.
1.2 Blade working principle In the aspect that the blade does not cut and the cutter head does not touch, the eccentric arc serrated blade and other disc cutters work as follows: the blade rotates at high speed with the cutter head, the moment before cutting, the blade serrated tip and the rape Stem porch is a point contact, that is, the critical cutting state (-a), the pressure generated by the point contact serration can quickly tear the stem stalk; after the stalk tears, the blade begins to cut, and the contact between the cutting edge and the rape stem stalk turns into a line. Type contact, continuous serration can effectively clamp the stem and reduce the cutting vibration (-b); after the rapeseed stem is cut, it will fly away from the cutter under the action of inertial force. The sliding cutting angle gradually increases from 30 to 60 along the curve of the cutting edge, and the cutting portion of the small sliding cutting angle is strong, and the cutting resistance is small and the cutting is stable. The whole process is serrated and cut, and the cutting edge is gradually cut. The cutting resistance changes from large to small, resulting in cutting buffer.
a critical cutting state; b cutting state.
Blade cutting process 2 Test materials and methods 2.1 Test material test was carried out in the rapeseed mechanized harvesting demonstration base in Beisheng Town, Liuyang, Hunan. Sampling by the "five-point" sampling method. The average height of the whole rapeseed was 1398mm; the diameter of the base was 5.518.5mm, and the majority was 814.7mm; the branch height of a few bottom fruit pods was below 500mm.
2.2 Method 2.2.1 Impact test The impact test of rapeseed stems was carried out by pendulum impact tester to determine the impact strength and the number of fruit pods. The test process ignores the influence of the cutting impulse and can be regarded as a uniform linear motion at the moment of cutting. Regardless of the friction factor, according to the law of conservation of energy, all the work consumed by cutting is used to cut off the rape stems. Determined and displayed on the torque speed digital display. The work consumed by cutting power consumption; F represents the cross-sectional area of ​​the test material. The rapeseed stems with the same diameter and similar maturity were taken at 100, 200, 300, 400, and 500 mm from the ground. After cutting, the work recorded by the dial was recorded, and the number of fruit pods was counted. Each part was repeated 5 times and the results were averaged.
2.2.2 Cutting test The cutting test was carried out on a self-propelled self-propelled cutting test device. The test device is mainly composed of a self-propelled cutting table, an adjustable clamping device, a measurement and control system and a power system. The cutting height of the test device can be adjusted to 100500mm, the cutting angle can be adjusted to 030, the cutting speed can be adjusted to 1.88 18.82m/s, the cutting advance speed can be adjusted to 0.22m/s, and the number of cutting blades can be varied. 26 pieces. The rapeseed plants were fixed on a 3 m long clamping device, and various parameters were adjusted according to the test requirements; the speed cutter motor driven the lower end of the disc cutter to rotate at a high speed and the device straight forward, and the cutting torque was passed through the torque sensor shaft. 2.2.3 Single factor test In order to examine the effects of cutting speed, cutting height, and cutter cutting inclination on cutting power consumption and grain loss, a single factor test was performed. Maintain the same cutting height of 100 mm, preferably the parameter cutting inclination angle for the cutting test, and record the cutting torque and the statistical amount of falling. After the test obtained the speed range suitable for disc cutting rapeseed, the speed of the minimum grain loss was selected to be 700r/min, and other parameters remained unchanged. The cutting test was carried out at a height of 100, 200, 300, 400, 500mm from the stem. Finally, three cutting inclination angles, that is, 0°, 10°, and 20 were set for the cutting test.
2.2.4 Multi-factor test The single factor test results were analyzed and found that the cutting power consumption and cutting loss of rapeseed stems were related to cutting speed, cutting position, cutting disc inclination and other factors. Due to the many influencing factors involved in the cutting test, orthogonal tests were used to perform multi-factor tests. 7 factor 3 level orthogonal test scale 8 (37) design This test 5 factor 3 level orthogonal test table s (35) (Table 1).
Table 1 orthogonal test factors level table serial number D piece A cutting speed; B cutting height; C cutter head inclination; D blade number; forward speed.
3 Results and analysis 3.1 Determination of suitable cutting height of rapeseed stalk The impact strength of rapeseed stems was characterized by the ability of Stem to resist deformation and fracture under external load. The results of the impact test (Table 2) showed that the average power consumption was 17.5, which was significantly larger than that of other parts, and was cut off from the area where the stem was more than 300 mm from the ground. The average power consumption did not change much; With the increase of the height of the stem, the diameter of the stem of the rapeseed is decreasing, and the diameter of the part of the stem is more than 300mm. Therefore, the impact resistance of the stem of the rapeseed is reduced, and the position of the stem is 300500mm. becoming steady. In addition, from the 300mm from the stem to the ground, the loss of grain loss has increased. The reason is that the resistance of the stem is reduced, and the resistance of the stem is relatively weak, and the deformation caused by the cutting force is large, causing more kernels to fall. Comprehensive comparison, the height of rapeseed stems suitable for cutting is 200400mm. 3.3 The influence of cutting height on power consumption and grain loss As the cutting height increases, the diameter of stems becomes smaller, and the work required for cutting is small, resulting in cutting. Power consumption drops and stabilizes around 30W. After the cutting height of rapeseed stalks exceeds 300mm, the loss of cutting and graining increases due to the decrease of the impact strength of stems. Comprehensive comparison, the preferred cutting height is 250mm. Table 2 The average cost of work and the average grain loss of different cutting heights of rapeseed stalks/stalk height/mm stalk average diameter/mm average power consumption/average impact strength/( Km-2) The effect of average chipping 3.2 cutting speed on power consumption and grain loss As the cutting speed of the cutter head increases, the power consumption shows a significant upward trend. When the speed is low, the cutting force is insufficient, and there is a multi-knife cutoff. The problem is that when the rotation speed is 700r/mm, the rapeseed stem can be cut off with a knife, and the falling weight loss is less than the falling weight loss when the rotation speed is low; when the rotation speed continues to increase, the impact force generated by the cutting is correspondingly increased, and the cutting is broken. The loss shows an increasing trend. Comprehensive comparison, the speed range suitable for cutting is 600750r/min. 3.4 Analysis of the influence of the cutting angle of the cutter head on the power consumption and the loss of the grain loss shows that the cutting power consumption decreases as the angle of the cutter head increases. This is because the stem tissue fibers are bound together by a relatively low-strength material in a certain direction, and the cutting power is saved. At the same time, the cutting cross-sectional area is correspondingly increased, and the impact force of the stem-shaped section is increased. The transient vibration response of rapeseed had a great influence on the loss of grain loss, which led to an increase in the loss of grain loss. For a comprehensive comparison, the angle of inclination suitable for cutting is 10°.
Falling grain loss Cutter cutting inclination/differential cutting inclination power consumption and falling loss 3.5 Multi-factor orthogonal test results The analysis results of the cutting power consumption and the falling loss loss (Table 3) show: affecting cutting power consumption The factors are in turn the cutting speed, the cutter angle, the advance speed, the number of blades, and the cutting position; the factors affecting the loss of the grain are the cutting inclination angle, the number of blades, the cutting speed, the advance speed, and the cutting position. Combining the influence of the two, the optimal combination of low cutting power consumption and small loss of grain loss is close to the test No. 5, and the result of test No. 5 is 2褚2£3 5 2, that is, the speed is 750r. /min, the cutting position from the ground 250 is a group with a smaller data in Table 3, so it can be considered that the set of parameters mm, the cutter head inclination angle of 10 °, the blade 6 pieces, the forward speed of 0.4 m / s. The combination meets low power consumption, Small drop loss requirements.
It can also be seen from Table 3 that the power consumption of rapeseed is low, and the grain loss is shown in Table 3. Orthogonal test results test number/sheet power consumption/w grain loss/grain torque grain loss loss torque ruler
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