Elastic hydrodynamic lubrication analysis for a sine movable tooth drive

The sine movable tooth drive has small radial dimension such that the heat, caused by friction, becomes an important factor in deciding its load-carrying ability. It is important to determine the amount of tooth lubrication in order to reduce the heat caused by the friction. This study provides equations for the meshing performance and provides the forces for the sine movable tooth drive. Using these equations, the minimum oil film thickness for the drive system is investigated. Results show that the minimum film thickness between the movable tooth and input shaft or shell changes periodically along the input shaft rotation angle. A large movable tooth radius and a movable tooth rotation radius could increase the film thickness between the movable tooth and the input shaft or the shell. In addition, a large speed ratio could increase the film thickness between the movable tooth and the input shaft, but this would also decrease the film thickness between the movable tooth and the shell. A large sine amplitude could increase the film thickness between the movable tooth and the input shaft, but this does not change the film thickness between the movable tooth and the shell. Under normal operation speeds, the hydrodynamic lubrication condition occurs between the movable tooth and the input shaft, and the partial membrane hydrodynamic state occurs between the movable tooth and the shell.

МЕТРОЛОГIЧНЕ ЗАБЕЗПЕЧЕННЯ ВИПРОБУВАНЬ ЕЛЕКТРОННИХ РЕГУЛЯТОРIВ ГТД – СТЕНД-IМIТАТОР ДВИГУННИХ ДАТЧИКIВ

Testing of electronic control systems (further “regulators”) FADEC for gas turbine engines in the manufacturer laboratory conditions is described. The main attention is devoted to the control of the metrological characteristics of the regulator measuring channels. The results of constructively separated sensor imitators application, what interacts with the controller, including DBSCT and vibration sensor, are presented in this article. It is shown the expediency and results of the stand application, which united all the imitators necessary for testing of serial production. Data on verifying imitators and ensuring accuracy coefficients is given. In the framework of testing the electronic regulators of gas turbine engines, JSC Element experts developed, manufactured and certified all the necessary specialized stands that provide both a full-fledged inspection in the test-laboratory of monitoring and functions checking and additionally checking of the metrological characteristics of the regulators measuring channels. For reduced testing time in the serial production of the RDTs-450M regulator, in addition to the previously used structurally isolated sensors imitators, a stand was designed and manufactured combining all the imitators necessary for measuring channels testing. This new imitator provided usability and reduced testing time. The simulators used for test procedure. These simulators provide output signals of real sensors. These signals check by standardized measuring equipment. Systematic verification use certified stands, which create a normalized influence on the input signal of measuring (pressure, vibration acceleration, shaft rotation angle are also available). Further improvement of the test equipment will consist in automating of procedures for checking the metrological characteristics of the regulators channels by creating of programmatically controlled simulators. The replacement of individual simulators with a specialized stand markedly increased the productivity of work on the calibration and verification of the regulators measuring channels.

Influence of Water and Mineral Oil on the Leaks in Satellite Motor Commutation Unit Clearances

The article describes the flow rates of mineral oil and water flowing, as working media, through the commutation unit of a hydraulic satellite motor. It is demonstrated that geometrical dimensions of commutation unit clearances change as a function of the machine shaft rotation angle. Methods for measuring the rate of this flow and the pressure in the working chamber are presented. The results of pressure measurements in the working chamber during the transition from the filling cycle to the emptying cycle are included. The pressure in the motor’s working chamber changes linearly as a function of the shaft rotation angle, which has a significant effect on the leakage in the commutation unit clearances. The paper presents new mathematical formulas in the form: Q=f(Δpγ) to calculate the flow rate of water and mineral oil in the commutation unit clearances. The γ factor is described as a function of fluid viscosity and clearance length (the motor shaft rotation angle). The coefficients used in these formulas were determined based on the results of laboratory tests of a motor supplied with water and mineral oil.

Study of the press forming mechanism of a thermoforming machine

The paper presents kinematic and dynamic investigations of the main press forming mechanism of a thermoforming machine. A multibody analysis of this press forming mechanism, which lifts and rotates a press bed, was carried out. Press bed lifting, which is necessary to form the component, is performed by means of a first rod and toggle mechanism. Press bed rotation to eject the formed component is produced by means of a second rod and must be appropriately shifted. These rods are oscillating followers driven by cams, making it possible to precisely define trajectories as a function of the motor shaft rotation angle. Analysis is performed by numerically solving the equations of motion. Cam synthesis on the basis of the oscillating followers’ trajectories makes it possible to obtain cam profiles in order to evaluate pressure angles and check that there is no undercutting. System dynamics is investigated in order to evaluate motor torque and analyse internal stresses on the hinges. In addition, some experimental results and those obtained with the dynamic model are compared. Performance improvement of the actual machine is carried out by modifying the trajectory of the press bed by means of a numerical code at the purpose developed. This approach is more convenient than the use of a commercial multibody code, which is not specifically built for parametric studies.

An Induced Shaft Deflection for Rotating Shaft Crack Detection

Over the years various techniques have been developed to extract information on the dynamic state of the rotating machinery. This paper introduces a new method based on the phase data of the shaft rotation angle. Usually the phase data is omitted and only the frequency components of the vibration spectrum are taken into consideration. However, the transverse shaft crack has a specific angular location about the shaft axis. Therefore, it is supposed that by measuring the vibration response of the rotor deflected by an additional constant force applied perpendicularly to the shaft axis at different angular locations, different vibration signatures can be obtained. Such signatures can then be used to detect the crack. The method utilizes also the coupling phenomenon between the lateral/torsional vibrations of the cracked rotor, since the shaft is additionally excited by an external harmonic torque. The computer simulation study is based on the uncracked and cracked rotor models obtained by using the finite element (FE) approach. The results of the numerical analysis demonstrate the potential of the suggested method for the effective shaft crack detection.

Dynamic Model and Numerical Simulation for Synchronal Rotary Compressor

The synchronal rotary compressor (SRC) has been developed to resolve high friction and severe wear that usually occur in conventional rotary compressors due to the high relative velocity between the key tribo-pairs. In this study, the working principle and structural characteristics of the SRC are presented first. Then, the kinematic and force models are established for the key components—cylinder, sliding vane, and rotor. The velocity, acceleration, and force equations with shaft rotation angle are derived for each component. Based on the established models, numerical simulations are performed for a SRC prototype. Moreover, experiments are conducted to verify the established models. The simulated results show that the average relative velocity between the rotor and the cylinder of the present compressor decreases by 80–82% compared with that of the conventional rotary compressors with the same size and operating parameters. Moreover, the average relative velocity between the sliding contact tribo-pairs of the SRC decreases by 93–94.3% compared with that of the conventional rotary compressors. In addition, the simulated results show that the stresses on the sliding vane are greater than those on the other components. The experimental results indicate that the wear of the side surface of the sliding vane is more severe than that of the other components. Therefore, special treatments are needed for the sliding vane in order to improve its reliability. These findings confirm that the new SRC has lower frictional losses and higher mechanical efficiency for its advanced structure and working principle.