Characteristic Analysis And Experimentation Study On Driving Wheelset Of Self-propelled Dual-track Orchard Transport

In the four models, developed by our group, which including7YGD-35self-propelled monorail transports,7YGS-45-type self-propelled two-track transports,7YGDQ-50towed monorail transport aircraft and7YGWQ-50traction trackless transport aircraft, the working conditions of self-propelled two-track transports is most complex, and the requirements on the performance of the transport aircraft itself is highest, therefore, in order to achieve safe and efficient operation of transport aircraft, we need to seriously study the running stability and smooth of the transport plane, the driving characteristics of the drive components and the wear mechanism, which has practical significance. In order to solve the problems about test and analysis for the optimization problem of the mountain orchards transport aircraft's operating parameters and structural parameters, we build a test platform. The test platform can be used to analyze the changes of the spindle torque, speed, wear rate of the driving wheel slot, wire rope slip rate and other indicators, as well as the running speed and vibration of the transport plane in different operating parameters of the load, preload, speed and slope. The platform can also be used for the overall performance parameters test of other small-scale track transports, which provides the experimental conditions and theoretical basis for the optimization of transport aircraft operating performance. Specifically, we have done the following research(1) According to actual needs, we build a transport aircraft automatic control test platform which mainly composed of the rack, the automatic control system and the testing system. Complete the circuit design by selecting the appropriate frequency conversion motor, frequency converter, PLC, and other critical hardware; Complete the PLC program design by using fuzzy PI controller in Siemens's Step-7authoring environment; Complete interface design in the Eviews editing software EV500. After the continuous adjustment, the system can run stably and uniformly in various conditions such as stop in an emergency, an emergency starter, speed change, instantaneous change of goods bias, cargo rolling random changes. Experimental platform vibration is very small, and the vibration of the truck itself is also very small, so it can meet the test requirements enough.(2) The test system consists mainly of the orchard truck, torque and speed sensors, eddy current sensors, rotary encoders, accelerometers and displacement sensors, as well as data acquisition equipment, computers and testing software. Under the principle of not changing the body structure or as little as possible of not changing additional components, install a variety of testing components in the transport aircraft, then measure the driving shaft torque and rotational speed, the driven shaft torque and rotational speed, the guide wheel speed, the amount of wear of the driving shaft's driving wheel on the wheel groove, the amount of wear of the driven shaft's driving wheel on the wheel groove,the vehicle vibration acceleration and other physical quantities.Convert physical signals into electrical signals with different sensors, and then convert the electrical signals into signals the computer can handle. The acquisition system consists of A/D data acquisition card connected to the PC and the corresponding data acquisition software obtains the signal. In the final, it is displayed after the treatment of the PC. Measurement data can be stored traced back. The acquisition and processing software ensures data acquisition being a variety of convenient and practical method, at the same time saving the data files in real time or historically and processing data offline.(3) Put the rope which used to drive and the driving wheel in self-propelled two-track orchard transport aircraft as the research object, through analyzing the additional friction of the rope and the driving wheel on the contact surface of the wheel groove, to solve the optimum operating parameters of the driving shaft torque. Analyze the effect on the spindle torque from the number of driving wheel grooves, center distance a, driving wheel radius r and wrap angle α h, the preload force F. Establish a functional relationship between the parameters and spindle torque. Use genetic algorithm optimization, found the optimal combination of structural parameters:preload of130N, the slot number4, center distance of0.3058, the driving wheel radius of0.0995, spindle torque390, wrap angle al of131.237degrees. Do the experimental study on effect of operating parameters on the spindle torque. Test the effect of operating parameters including motor speed, load, gradient, preload on the spindle torque.Use the single variable method to analyzing the impact of each factor on the spindle, and set the other three factors constant. The results showed that:when the motor frequency is15Hz or30Hz,the spindle torque is very smooth, and ensure sufficient torque; Spindle torque will gradually increase in the increase of the load, however, when the load is increased to a certain extent, spindle torque do not change significantly. Load cannot increase infinitely, or wheels will slip, because spindle torque will not increase. When the gradient changes from5°to45°, the spindle torque shows an upward trend; Preload had no significant impact on the shaft torque.(4) Through the tensile stress and strain analysis on the tight and slack side of the rope, establish a mathematical model of the driving wheel and the slip rate. Get the relationship between the slip rate and the driving wheel radius, preload, the center distance, and do simulation analysis on the change of the slip rate. It's believed that the slip rate mainly is caused by the speed difference between the wheels caused by deformation of the wire rope. Factors which affecting the rope deformation, includes wrap angle α, preload Fo, the elastic modulus of the wire rope E, contact arc length of the rope and the driving wheel L, cross-sectional area of the wire rope A, driving wheel radius r1, driving wheel center distance L0, rope diameter d. Through comprehensive analysis of the factors mentioned above, a functional relationship between the slip rate and them is established, and get the slipping rate changes under different conditions by using matlab programming. It's concluded that:the relationship between the driving wheel radius and slip rate is nonlinear, wheels slip rate gradually decreases as the radius increases; the relationship between preload and slip rate is linear, because the wrap angle becomes larger as the center distance increases, the slip rate decreases. If r, is kept constant, ε%increases as Lo increases; If L0is kept constant, ε%decreases as r, increases. In the experimental study on the driving wheels slip rate, it's found that by analysis of variance the affect from the load on the slip rate between the motor and drive wheel is the most significant, and the role of the other three factors is not obvious; the affect from the load and gradient on the slip rate between the driving wheel and driven wheel is large, and other two factors have no significant influence on the slip rate; the affect from the load and gradient on the slip rate between the driven wheel and guide wheel is large, and other two factors have a small impact influence on the slip rate.(5) Use the eddy current sensor and laser displacement sensor respectively to determine the amount of wear by measuring the displacement. The test shows that the data measured by the two methods presents the same rules, and the parameter value of the wear increases as the number of tests increases, which conforms the characteristics of these three stages including the breaking-in stage, stable wear stage and severe wear stage. During the previous three years, driving wheels are basically at the breaking-in stage, and driving wheel pairs and the wire rope are adapted to each other, so wear volume changes largely. From the fourth to the seventh year, wear volume changes slowly, and driving wheels enter the stable wear stage gradually, so wear at this time belongs to the normal wear. Wear of the driving wheel is relatively small, and life is relatively long.(6) Use the MTC wire rope computer flaw detector to do the wire rope wear detecting test, after three groups of testing,the first wire rope is damaged seriously, which leads the transport plane cannot run. After four groups of test, the second wire rope is damaged seriously, which leads the transport plane cannot run; The second wire rope can be recycled approximately500-800round-trip, which is equivalent to a rope can be used for about3-4years. Rope LF and LMA data and curves show the total number of broken wires, the maximum number of broken wires; the cumulative maximum number of broken wires away from twist are showing good regularity and increase the gradient, and intensify gradually; The location of the broken wire is relatively concentrated; the maximum number of broken wires away from twist is up to14, and the rope reaches the criteria for scrapping, which is consistent with the actual situation. Along with the emergence of broken wire, the internal and external wear of the rope occurs simultaneously; the wire rope metallic cross-sectional area loss rate also shows a gradual increasing trend, and the maximum cross-sectional area loss rate can reach16.46%.