The dynamic balancing of the drive mechanism for the roller forming unit with balanced drive is consideredin order to increase reliability and durability. Two dynamic balancing problems are solved in the simulation process of the drive mechanism balancing: the inertia forces balancing which applied in the masses centers of the motion links, and the torque balancing which reduced to rotation axis of the drive shaft, that arise from the inertia forces action.Wherein all kinematic characteristics of the unit forming trolleys are determined, the change functions of the kinetic energy for the unit each element and whole system, the inertia forces of the unit each element and the total inertia force, the total moment from the inertia forces action are written.The unit motion equation is compiled based on the Lagrange equations of the second-order, and the generalized force and moment on the drive motor shaft are determined.The drive mechanism imbalance is estimated by the maximum and root-mean-square values of the total inertia forceand total torque from the inertia forces action, the dimensionless coefficients, which express the root-mean-square values ratio of the total inertia force and inertia forces, that act on each trolley, and the root-mean-square values ratio of the moment from the inertia forces action of the whole mechanism and moment components from the inertia forces action of the individual elements.It is established that the best balancing of the inertia forces applied in the masses centers of motion links, and the torque balancing which reduced to rotation axis of the drive shaft, that arise from the inertia forces action, are observed at the cranks displacement angle value Δφ=90° for the roller forming unit with balanced drive. The work results may in the future are used to refine and improve the existing engineering methods for estimating the drive mechanisms of roller forming machines, both at design stages and in practical use.
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The impact of the cranks displacement angle on the motion non-uniformity is determined for three forming trolleys of a roller forming unit with an energy-balanced drive mechanism. At the same time, the specified unit is presented by a dynamic model with one freedom degree, where the extended coordinate is taken as the angular coordinate of the crank rotation. For such a model, a differential equation of motion is written, for solved which a numerical method was used. The inertia reduced moment of the whole unit, and the resistance forces moment, reduced to the crank rotation axis, to move of forming trolleys during the formation of products from building mixtures are determined, and also the nominal rated power of the electric motor was calculated, when solved a differential equation of motion. According to these data, asynchronous electric motor with a short-circuited rotor was chosen, for which a mechanical characteristic is constructed by the Kloss formula. Having solved the differential equation of motion with all defined characteristics, we obtain the change function of the crank angular velocity from start-up moment and during steady motion mode. After that, we calculated the time corresponding to the angular velocity value, and obtained the change function of the crank angular acceleration from start-up moment and during steady motion mode. The motion non-uniformity of the roller forming unit has been determined by the motion non-uniformity factor, the motion dynamism factor and the extended factor of motion assessment during steady motion mode. The impact of drive cranks displacement angle on the motion non-uniformity has been traced, as a result, the specified factors have the minimum values at cranks displacement on the angle Δφ=60°. The results may in the future are used to refine and improve the existing engineering methods for estimating the drive mechanisms of roller forming machines, both at design stages and in practical use.
У даній роботі розглянуто створення фізичної моделі установки для різання високоабразивних матеріалів абразивними армованими кругами для проведення експериментальних досліджень. З метою дослідження процесу взаємодії робочого органу з робочим середовищем виникає необхідність проведення експериментальних досліджень, для яких, як правило, використовуються натурні об’єкти дослідження або їх моделі. При фізичному моделюванні зберігається фізична природа явищ, але змінюється їх масштаб. Використовуючи теорему подібності та фізичне моделювання, визначено умови подібності установки для різання високоабразивних матеріалів абразивними армованими кругами, в якій взаємодія робочого органу та робочого середовища описується силовим рівнянням із врахуванням їх параметрів. При цьому параметри натурального процесу взаємодії робочого органу та робочого середовища записано через параметри фізичної моделі та коефіцієнти подібності. В результаті ділення відповідних доданків силових рівнянь натурної установки та моделі між собою отримано систему з двох рівнянь, яка зв’язує між собою вісім невідомих величин коефіцієнтів подібності. Шість з цих величин було задано з конструктивних міркувань, а два коефіцієнти розраховано. Отримані значення коефіцієнтів подібності дали можливість побудувати фізичну модель установки для різання високоабразивних матеріалів абразивними армованими кругами, що подібна натурній установці для різання високоабразивних матеріалів. В якості фізичної моделі установки з врахуванням коефіцієнтів подібності та передбачених задач досліджень було доопрацьовано динамометричний стенд реєстрації силового навантаження авторської конструкції КНУБА для дослідження процесу різання високоабразивних матеріалів абразивним армованим кругом, що дозволяє провести повноцінні експериментальні дослідження з врахуванням всіх чинних факторів взаємодії робочого середовища та робочого органу під час різання з подачею води в зону різання для обезпилення робочого процесу. В якості робочого середовища запропоновано використання вогнетривкої цегли, а в якості робочого органу – абразивний армований круг для різання високоабразивних матеріалів міцністю до 60МПа.
In order to increase the reliability and durability of the roller forming installation, the optimal dynamic mode of the reciprocating movement of the forming carriage was calculated. When calculating the optimal dynamic mode of motion, the criterion action is used as a criterion for the motion mode, which is an integral over time with an integral function expressing the "energy" of accelerations. The functions of changing the kinematic characteristics of the forming trolley during its movement from one extreme position to another, which correspond to the optimal dynamic mode of reciprocating movement, were calculated. With this mode of movement, the movement and speed of the forming carriage change smoothly, without creating significant dynamic loads in the installation, which in turn has a positive effect on its durability. Taking into account the functions of changing the speed of the forming carriage, the law of changing the angular speed of rotation of its rolling rollers was calculated. The design of a roller forming unit with a drive from a high-torque stepper motor, which is mounted in the rolling rollers of a forming carriage and provides an optimal dynamic mode of reciprocating movement of the forming carriage, is proposed. When using the specified drive in the installation, the quality of the surface of the processed concrete mixture increases, dynamic loads in the elements of the drive mechanism are reduced, unnecessary destructive loads on the frame structure disappear and, accordingly, the reliability and durability of the installation as a whole increases. The results of the work may be useful in the future for clarifying and improving the existing engineering methods for calculating the drive mechanisms of roll forming machines both at the design/construction stages and in real operation modes. Also, the results of the work can be useful in the design or improvement of mechanisms with reciprocating movement of executive elements.
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