The damages of corn grain during threshing depend on many factors, the main of which is timely removal of grain from the threshing chamber what depends on the design of the deck. The functional parameters of the deck in self-propelled combines and stationary threshers used for threshing of seed corn have been studied. Studies of factors affecting the separation process of a mixture consisting of grain and other parts of corn cobs in the threshing chamber were carried out. It has been proved that the shape, size and layout of the deck holes have the greatest impact on the timeliness of the output of the threshed corn grain from the threshing chamber. In this case the deck should consist of three parts of different lengths: 1) a part of the deck of the chamber of the primary damage of the integrity of the cob grain structure; 2) the deck part of the main threshing chamber; 3) the deck part of the finish threshing chamber. The evaluation criteria for choosing the lengths of the deck parts are the average of the double ratio of the linear dimensions of the corn grain of the six main subspecies and the maximum length and diameter of the cobs of 65 main varieties cultivated in Russia. The ratio of the lengths of the first two sections of the deck should correspond to the Fibonacci golden section-1.618 and the double ratio of the linear dimensions of all three sections-1.29. The studies have evaluated the effect of the shape of the holes: round, round lunate, square, rectangular, and hexagonal. At the same time, the pattern of holes on the hexagon and the square and the square holes, additionally, at an angle 45 º to the rotor axis was studied. The feasibility of using round holes in the deck with a diameter of at least 10…14 mm has been established. As a result of using the deck of the proposed design, the conditions for timely removal of threshed grain from the threshing chamber with a reduced probability of damage are created.
To increase the efficiency of the process of seed corn threshing in stationary conditions, an axial-rotor thresher with a pneumoadaptive deck is proposed and constructed, which allows differentiating the threshing forces in the threshing chamber. The index of unthreshed seeds loss on cobs and free grain loss, defined in previous studies, allowed one to establish a rational interval of the rotor speed of the proposed thresher, which is 150 … 170 min-1. The rationality of this interval was checked by the grain-crushing index, which is an indicator of the effective use of the threshing force of the impact. Experimental studies of this indicator were carried out in the range of rational rotor rotation frequencies (150 … 170 min-1), as well as to study the regularity of grain crushing changes, additional studies were carried out at a frequency of 190 min-1. It was found that at rotor speed 170 min-1 grain crushing is 1.4%, and at 190 min-1 it significantly exceeds the permissible value. A mathematical expression is proposed that shows the dependence of the force of the working bodies of the pneumoadaptive deck hitting the grain on the rotor speed, confirming the correctness of choosing a rational interval of the rotor speed. Research results indicate that when the rotor speed does not exceed 170 min-1, the stresses in the grain body under the impact of the working bodies do not reach the maximum permissible value. At the same time, the grain retains its integrity, and the crushing index remains minimal.
Based on an overview of methods for hardening and restoring parts of agricultural machines, it has been found that the methods currently used are highly labour intensive and are not well suited for hardening the cutting edge of tillage machine discs. A method of electromechanical hardening of ploughshare discs due to simultaneous thermal action and plastic deformation is disclosed. Electromechanical hardening modes are justified on the example of standard cylindrical samples. The developed technique contains the following stages: determining the steel grade of a part; planning of the experiment based on the plan of the full two-factor three-level experiment with selection of influences and response function; experimental hardening of laboratory samples at the installation; microstructural analysis of hardened samples; numerical processing of experiment results. Based on the optical emission analysis, it was found that the samples are made of steel 65G. The factors of influence are: current strength X1(Ir) = 800...1200 A on the reinforcing tool in the form of a roller and the pressing force X2(Fk) = 100...300 N of the tool to the part. The hardness of the surface layer Y(HRC) is adopted as the response function. Microstructural analysis showed that a layer consisting of several zones was formed on the hardened surface of the sample: white, light non-flowing and dark martensitic, passing into the ferrite-pearlite structure of the base. On the basis of multiple regression analysis, an empirical mathematical model is obtained and its graphical interpretation in the studied area of factors values is given. According to the criterion of providing wear resistance of working edges of disks, maximum hardness is achieved at current strength X1(Ir) = 1060 A and force X2(Fk) = 210 N in the contact zone. Developed technique and tested modes of electromechanical hardening are suitable for development of process of hardening of disk ploughshares of grain-grass seeders.
A high yield of grain and green mass of corn can be obtained only when using the seeds of the first generation of zoned hybrids, which are threshed in the conditions of processing enterprises after pre-drying the cobs to a humidity of 12…18 %. At this humidity, the strength of the shell of corn grains is maximal and the connection of the grain with the rod is weakened, which allows for threshing with minimal damage to the grain. An experimental design of an axial-rotary threshing device, which rotor is equipped with multi-helical spiral winding of variable height, is developed. The winding height decreases from the entrance to the threshing chamber to the exit from it. Rotor fully covered pneumatic-adaptive studded deck is installed so that the gap between the rotor shaft and the independent movable pins decreases from the input to the output. All pins are pressed against the deck by means of rubber pneumatic bags with an internal overpressure. In addition, the threshing chamber has the ability to change its spatial position relative to the horizon. These dimensional characteristics are justified foe a stationary axial-rotary threshing device with a productivity of up to 4.5 t•h -1 . As the result of experimental studies, the following rational intervals of values of the modes of operation of the threshing device were established: the rotor speed 150…170 min -1 , the angle of inclination of the threshing chamber 10…14º, the force of pressing the movable pins to the cobs 35…55 N, feed 0.8…1.1 kg•s -1 . As a result, the productivity of the axial-rotary threshing device is in the range 2.88…3.96 t•h -1 and the energy intensity of the threshing process is 0.5…0.7 kWh•t -1 , grain on the cob after threshing is less than 1.5 %, free grain in threshed corn cobs 1.16 %.
Results of assessment of operability of the crankshaft of the K05-12 compressor installed in the Maxima 1000/1300 refrigeration unit on the Volvo cars are provided. As a criterion of refusal sudden physical destruction of the console site of the two-piece line crankshaft in a zone of a belt drive sheave at an early stage of operation is accepted. As a result of researches the microstructural analysis of material of original and replacement crankshafts is carried out, the rated scheme taking into account geometrical parameters of a part under the influence of operational loadings at an adverse combination to a static tension is made, analytical assessment of durability of the crankshaft is executed, the graphic 3D-model of a part executed by means of CAD-technology of the computer-aided engineering system COMPAS 3D is received. For the purpose of automation and increase in productivity and reliability of rated assessment of durability and rigidity of the crankshaft, test calculations are executed on the basis of CAE-technology by means of the computer-aided engineering system automated workplace АРМ WinMachine in the АРМ Studio automated workplace rated module. In the course of assessment comparative calculations of parameters of durability and rigidity at production of crankshafts are made of the VCh 40 high-strength cast iron (a replacement part) and VCh 70 (an original part), when performing fillets in a zone of destruction of a shaft on radius 0.5; 1.0 and 2.0 mm and also at the modes of normal and extreme operational loading. The end results were estimated in sizes of equivalent normal stresses from a bend and torsion, total linear movement, reserve factor on the flowability, static and fatigue resistance, quantity of cycles before fatigue failure. As a result of calculations emergency conditions of loading and basic reasons of failure of the crankshaft by physical destruction are established.
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