The rate of cutting and breaking (the percentage of the number of broken cane and the total number of cuts) is an important indicator to measure the working performance of the sugarcane harvester cutter, and the working factors of the cutter (advance speed, cutter speed) and structural factors ( The blade angle, the blade cutting angle, the angle of the cutter head, the number of blades, and the vibration factors (frequency, amplitude) caused by the unevenness of the ground may affect the breaking rate. The research shows that the influence of the advance speed of the cutter and the cutter speed on the cutting rate is determined, and the cutting speed is 0.6m/s and the cutter speed is 650r/min (the cutter radius is 285mm). Better 11, can guarantee a certain productivity, but did not consider the impact of field vibration factors on the rate of breakage, and at the same time less research on the mechanism of the impact rate. Therefore, considering the influence of vibration on the breaking rate and the mechanism of the influence of various factors on the breaking rate, this paper uses computer visualization simulation technology to observe the cutting state of each sugarcane by continuously cutting the kinematics of sugarcane. Combine the graphic method to study the influence mechanism of the factors affecting the cutting state on the breaking rate.
1 Mathematical model 1.1 Mathematical model In the past, the regression mathematics between the six factors including frequency, amplitude, blade edge angle, blade cutting angle, cutter head inclination and number of blades was obtained under the conditions of soft and hard soil. The model is 0 fund project: Heilongjiang Institute of Science and Technology introduced talent research start-up fund project (06-58) for cutting and breaking rate under soft soil and hard soil test conditions.
1.2 The effect of single factor change on the rate of breakage is to examine the effect of single factor on the rate of breakage. The simulation results are shown.
2Mechanical analysis 2.1 The influence mechanism of vibration frequency and amplitude on the breaking rate (a) and (b) show that the frequency, amplitude and the breaking rate are linear, and the breaking rate increases with the increase of frequency and amplitude, and the frequency and The amplitude has a large influence on the breaking rate.
Using the dynamic simulation analysis software ADAMS to simulate the cutting process of the cutter, the results show that in most cases, the sugarcane can be cut by multi-knife cutting in turn, and the cutting of one knife is almost rare; and due to the existence of vibration, adjacent blades The slit has a fixed height difference which increases as the frequency and amplitude increase, as shown by and .
When cutting with multiple knives, after the first knives are cut, not only a part of the sugar cane is cut, but also the incision of the knives is at the upper part of the front kerf incision (there is a certain height difference), so that after the first knives are cut, the incision is made. The bearing area is reduced, the support strength is reduced, and the sugar cane is subjected to large bending stress and shear stress when cutting. Since the soil is a material with elastoplastic deformation, the actual growth condition of sugar cane is affected by the soil in all directions. The tightening effect of soil on the root during cutting can be simplified to the horizontal reaction force P and method. The reaction force N (as shown) can be used to simplify the cane to be cut before the cutting edge into a cantilever beam. When undergoing two-knife cutting, the residual section (shaded portion) after the first cutting is a dangerous section. In the middle, the blade rotates clockwise at an angular velocity, moving to the right at a speed v horizontally, AA is the difference in cutting height, and F is the cutting force. Assuming that the second knife completely cuts the sugar cane, during the cutting process of the blade, the center of the force F passes through the centroid of the sugar cane stem, and the bending moment M=FAh is generated for the residual section but the force F does not pass through the shape axis y' of the residual section. An additional torque T = F(x'-R) is generated. Since the cutting force varies with the cutting depth, the cutting force reaches the maximum when cutting to 1/2 of the total depth, so the cutting force is maximized when the second cutting is performed, and the bending moment and torque caused by the stem are also maximized, that is, the residual The shape of the mandrel of the partial section is y', the moment of inertia of the residual section to the y' axis is /y., and the moment of inertia of the pole is Ip, and the second knife cut of the gap height difference Ah is the residue after the first knife cut. The bending stress and shear stress T caused by the section are respectively AA, so that the bending moment M and the torque T of the sugarcane are increased at the residual section, and the second moment of the residual section is reduced, so that the bending section coefficient and the torsional section are obtained. The coefficient is also reduced, resulting in an increase in bending stress and shear stress at the dangerous section, and the combined action of the two makes it easy for sugar cane to break at the dangerous section. When the frequency is fixed and the amplitude is increased, the height difference Ah of the adjacent slits is increased, which is equivalent to cutting at the same point, and the cutting depth of each knife is small, the cutting force is small, and the bending moment and torque generated for the sugar cane are small. Therefore, the breaking rate decreases as the number of blades increases.
When the edge angle is around 15, and the number of blades is large, the breaking rate is small. The reason for the interaction is the same as the one-way analysis.
3 Conclusion The frequency and amplitude have an obvious influence on the breaking rate. The breaking rate increases with the increase of frequency and amplitude. When designing the cutter, consideration should be given to increasing the vibration reduction measures. Under the conditions of hard soil test and soft soil test, the test factors have the same influence on the breaking rate, but the breaking rate under the soft soil test conditions is hard. The soil is slightly higher. The reason is that the tightening force of the softer soil on the sugarcane is less than the tightening force of the harder soil on the sugarcane, the sugarcane is subjected to a large impact force when cutting, and the small fastening force reduces the support strength of the sugarcane. Easy to bend, sugar cane is easy to break the head, resulting in a softer soil under the test conditions, the rate of breakage is slightly higher than the soil under the hard test conditions.
The trolley is self-propelled, and the hoist mounted on the trolley moves the steel mold and the needle beam more relative to each other, and the trolley can move forward.
When the needle beam trolley is lining, the bottom, the side and the top are formed at one time. The vertical mold and the mold removal are completed by the hydraulic cylinder, and the positioning is performed by the vertical cylinder and the leveling cylinder of the base. The trolley is self-propelled, and the hoist mounted on the trolley moves the steel mold and the needle beam more relative to each other, and the trolley can move forward.
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