Self-excited Vibration Subsoiler Design And Experimental Research

The purpose of subsoiling is to break the thick and hard plow pan structure. The resistance and energy consumption are large during the process of tilling, which results in expensive subsoiling expense. On the premise that satisfying the requirement of agriculture production against soil subsoiling, reducing resistance and energy consumption is a problem of much attention among agricultural machinery research workers at home and abroad.This paper combines with the National Science Foundation "self-excited vibration subsoiler parts soil crushing mechanism and drag reduction optimization"(project number:51175354).For seeking the design theory of soil subsoiling equipment, the structure parameters and their influence to working resistance have been discussed. This study adopts the method of combing theoretical analysis and experimental study. Through soil-bin test of subsoiling shovel it studies vibration subsoiling parts' effects to tractive resistance; by means of reaching on the dynamic response characters of subsoiling equipment while subsoiling, it analyzes the interaction rule between vibrating part and soil, soil breaking mechanism and vibration mechanism of vibrating parts, then reveals cause of the vibration of vibration subsoiling parts and the vibration rule. Through simulation of the process of how the subsoiling parts cut the soil, it analyzes the optimal structure configurations of subsoiling parts for the purpose of reducing tractive resistance, thus provides theoretical basis for the designing of subsoiler. Field experiment of the sample subsoiler is done to test the performance of the designed subsoiler and to test whether it meets related industry requirements or not. Based on processing field experiment data of the acceleration and the traction resistance this paper studies the dynamic characteristics of the subsoiler system and the vibration characteristics of vibration parts.With self-induced vibrating subsoiler as study object and targeted realizing minimal tractive resistance, this paper combinedly makes use of dynamics analysis, experimental research and numerical simulation technology to do the research.The main contents are as follows:(1) It analyzes the dynamic properties of soil, through the triaxial compression test and numerical simulation studies the shear properties of soil. The results show that, relative motion creates friction between soil, and thus generates shear force. When the shear force of the soil reaches the failure stress of the soil, the soil crushes. Through the analysis of the drag reduction of vibration tilling parts it finds that the when tractive effort of the vibration is small, the soil smashing performance is good.(2) Soil-bin test of spring-tooth subsoiling shovel and rigid subsoiling shovel. Under the same working process, compared with rigid subsoiling shovel, the tractive resistance of spring-tooth subsoiling shovel has reduced by 9.95%, and as to specific resistance, by 14.52%, thus having better subsoiling drag reduction performance. Comprehensively doing range analysis and variance analysis of orthogonal test and discussing the type of shovel shaft, advance speed, and subsoiling's influence to tractive resistance, power consumption and specific resistance. The experiment results show that:when uses spring-tooth subsoiling shovel,the advance speed is lm/s and the tilling depth is 20cm, all the tractive resistance power consumption and specific resistance present minimal values, which indicates that the spring-tooth subsoiling shovel is more suitable when the tilling depth is 20cm. By analyzing the vibration of subsoiling shovel, we find that the main frequency of the spring-tooth subsoiling shovel is 5.86Hz and the main frequency of the rigid subsoiling shovel is 4.39Hz.The low frequency parts like uneven ground and soil texture lead to constant change of soil resistance in turn cause the vibration of spring-tooth subsoiling shovel.(3) The paper uses LS-DYNA to do finite element analysis of the interaction between subsoiling parts and soil, to analyze action process of subsoiling shovel to soil and the crushing process of soil, then compares the throwing soil tracks of the two types of subsioling shovels. The results indicate that the largest stress of spring-tooth subsoiling shovel occurs at the first bend of S-shape shovel shaft where the soil disturbance range is widest.(4) The development of self-induced vibrating subsoiler. Through numerical simulating of layered operating process of subsoiler and with minimal tractive resistance as target, this paper makes orthogonal rotation combination test and build regression equation in which V means advance speed, H:tilling depth difference between front shovel and rear shovel, L:space between front shovel and rear shovel, then uses MATLAB to find out the optimal solution. The test results find out that with V=1.06m/s,H=95mm, L=402mm, the tractive resistance reaches minimal value F=4.2kN. According to optimal operating configurations, it simulates the working process of layered subsoiling mechanism, and thus studies drag reduction mechanism of layered subsoiling mechanism.(5) Field test of model machine. It measures the physical parameters of the soil and the result shows that 30 cm under the surface the soil strength reaches the maximum. The performance test of subsoiler shows that the subsoiler works stably and its trip under soil is short only 2.2m. Its average loosening width is 30.2cm and the loosening coefficient stability is 97.9%.(6) Study on the dynamic response characteristics of self-induced vibrating subsoiler system. Processing field experiment data of the vibration acceleration and the traction resistance and through preprocessing the time domain curve of vibration acceleration and traction resistance is made out, then it analyzes the property of the curve and finds out that the vibration of spring-tooth subsoiling shovel belongs to complicated periodical vibration. In the forward speed lm/s, tillage depth is 0.3m, compared with the non-vibration, the average traction resistance of vibration is reduced 11.31%. Vibration has obvious drag reduction effect..Frequency domain analysis of vibration acceleration and traction resistance. The dominant frequency of subsoiler is 6.84Hz and the period is 0.15s. The vibration of spring-tooth shovel and spring are the two key factors causing the vibration of the whole machine. By solving the transfer function of subsoiler system and using Routh and Bode stability criterion, we get to know that the vibration system of subsoil is stable.