Papers by Keyword: Bearing

Abstract: Planetary speed reducers are used in the actuation of the revolute kinematic joints thanks to their specific advantages. However, in order to achieve a good positioning accuracy for the kinematic chains, these must have reduced backlash and high torsional stiffness. Therefore the deformations of the elements composing the mechanical structure under the action of gearing forces should be as low as possible, thus leading to backlash reduction. This also becomes important since the presence of backlash in the structure of the planetary speed reducer affects the stability of the overall kinematic chain. In this paper, a novel computation method for bearing deflections is proposed, starting from the kinematic diagram of the planetary speed reducer. Having known the kinematic diagram, it becomes possible to compute the gearing forces, keeping in mind the non-uniform power distribution on the planetary gears. The bearing reactions were computed in two cases: when the planetary gears are free to spin on the planetary carrier and when the planetary gears are fixed on the planet carrier, being supported at the extremities. Based on the computed values for bearing reactions, the corresponding deflections are determined. Once the values of the bearing reactions and deflections had been determined, the load-deflection and stiffness-deflection diagrams were elaborated for ball and roller bearings, allowing the determination of the bearing type that ensures low deflections and high stiffness. Based on the results, some recommendations are made, allowing the reduction of bearing deflections, and increasing the torsional stiffness.

Abstract: Presented article describes the methodology of material flows planning for bearings production in digital factory. Article analyses the production programme on example in a several steps. It decides about organization of production into the lines and optimizes suggestion of production sequences. In the end of article it presents the basic production parameters. The target of article was creation of complete procedure for suggestion of manufacturing system of bearings production.

Abstract: This study propose a new nonlinear model for offset printing press gear-cylinder-bearing system by the lumped parameter approach. The multi-DOF model consists of helical gear pairs and spur gear pairs with time-varying meshing stiffness. Bearing and shaft flexibilities are include in the model as well. The equations of motion are obtained by Darren Bell principle and Runge-Kutta numerical method is used to slove the equations of motion. The results show that meshing stiffness and bearing stiffness significantly affect critical speed, vibration acceleration and meshing force. Multi-body dynamics software are applied to compare with lumped parameter model. The results show that there are many similarities in different aspects. Results of experimental study on offset printing press are also presented for validation of different models. After Discrete Fourier Transform, the graphics display that acceleration peaks frequencies are an integer multiple of the gear mesh frequency. It demonstrate that mechanical vibration is mainly from gear transmission system at high printing speed and gear transmission system lead to nonlinear vibration. This work provide a foundation for further improvement of the dynamics of gear system.

Abstract: Progress in the field of microelectronics and micromechanics has created new opportunities for the development of fluid power microsystems and microhydraulics. Miniaturization of hydraulic elements allows replacing the classical hydraulics with microhydraulics, where due to size or weight the former cannot be applied. Gear pumps are common use due to their reliability, resistance to working medium impurities, high efficiency, small size in comparison with other pumps and simple and compact design. Therefore micropumps often associate with a gear pump type. A micropump entails microbearings production. This requirement leads to cost increasing due to requirements to high accuracy of manufacturing. The paper focuses on a method for micropumps production without bearings. The idea based on application of materials with satisfactory friction coefficient in pairs. Friction pairs analysis made from different polymer and composite materials was carried out. As a result a gear micropump was designed and produced.

Abstract: Bearings are one of the most important components in rotating machineries. Their failures will lead to great production loss and increase the maintenance cost. So, condition monitoring work of bearings can save and avoid the potential loss caused by bearing fault. Lucy-Richardson deconvolution (LRD) algorithm, as an image processing technique, started to be used in bearing fault diagnosis. However, only data of bearings working in electric motor are used to validate the method. In engineering cases, most bearings are working in gearbox. Therefore, the bearing fault signals are very weak compared to the gear vibration signal. It is usually difficult to detect the bearing fault in this case. LRD algorithm is used to enhance the bearing fault diagnosis and some characteristics in this case are discussed. Experiment data analysis demonstrates that LRD can enhance the periodic impulse signal effectively. Otherwise, if the desired fault signal is weak compared to non-desired signal, then, the desired fault signal will be continued weaken by LRD which is not benefit to bearing’s incipient fault detection.

Abstract: This article deals with optimization and typing of the frames of the assembly presses which are used for assembly process of rolling bearings. The article describes the solution of technical problem from conception phase of the press frame to the phase of final CAD model design. Final solution contains of proposal for typing of dimensional series with five different sizes for five different press forces. The optimization of the shape and the dimensions, as well as typing, reduces manufacturing cost of the assembly presses. The build dimensions are reduced as well, while required stiffness and strength are preserved.

Abstract: This article deals about experimental analysis of the operational loads on the agricultural machine in real conditions. The goal of this work is to gain boundary conditions which stress frame, joints, screw connections, bearings and other parts of agricultural machines.

Abstract: Piecewise non-smooth model of three-degree-of-freedom rolling bearing system with fault in outer Ring is established by the method of the nonlinear theory. The Neimark-Sacker bifurcation of bearing system is first studied in this paper. The switching matrixes of system are obtained at the switching boundaries, and theNeimark-Sacker bifurcation of non-smooth bearing system is analyzed by combining the switching matrixes with the Floquet theory for smooth systems. The numerical method is used to further reveal the Neimark-Sacker bifurcation of bearing system through establishing the Poincare mapping on the collision plane. When the rotating frequency is increased to reach the critical bifurcation point, a pair of complex conjugate Floquet multipliers is on the unit circle and others into a unit circle , and the Neimark-Sacker bifurcation appears.The study of bifurcation of the fault bearing system provides reliable basis for the design and fault diagnosis and provides theoretical guidance and technical support for the actual design in the safe and stable operation of large high-speed rotating machinery.

Abstract: The article is dedicated to investigate possibility of diagnostics bearing faults of induction motors by stator currents analysis. The main features of stator currents analysis are studied. The possibility of identifying air-gap eccentricity due to the working with damaged bearings by stator currents investigating is revealed. The recommendations of monitoring and configuration of a proper diagnosis of induction motor are provided.

Abstract: This paper deals with the possibilities of bearing fault diagnosis of induction motors by stator currents analysis based on Park’s vector approach. The main theoretical aspects, the experimental results and their analysis are presented. It is shown that preventive stator current diagnostics of induction motors based on Park’s vector allows us early detection of bearing defects in the inner and outer races. The current spectra additional harmonics appearing in the case of bearing damage are found.