Papers by Keyword: Shaft

Abstract: This paper presents the press fit calculation that depends on different methods, the sizes of holes and shafts are quantities distributed according to the normal law, so the tolerance of the joint between the shaft and the hub is also distributed according to the normal law with two parameters: the mean value and the standard deviation. The paper also demonstrates the procedure and computer program for calculating the metal interference joints given by the probability method, thereby giving a chart of choosing tolerance depending on the applied load, simultaneously calculating the interference joints by the min-max method, and comparing it with the probability method, etc. Calculation by the probability method gives more reasonable working parameters. Along with the interference fit parameters, the consideration of materials is mentioned as well.

Abstract: Shaft failures often occur, even in the shafts of centrifugal pumps. This study aims to determine the cause of shaft fracture through experimental and numerical study. The fracture surface was observed using Scanning Electron Microscopy (SEM) to identify the initial crack. The chemical composition test results show that the material used was in accordance with the AISI 420 standard, which is necessary to make Finite Element Analysis (FEA) modelling. Shear stress, strain and stress intensity factors were analysed around the fillet using FEA. The results show that the value of maximum stress intensity factor, K_I, occurs in the multilevel shaft fillets that experienced initial cracks due to torsional loads. The shear stress value, obtained from the FEA, was higher than the shear stress value of the material. The K_I value, also derived from the FEA, was higher than the K_IC value of the material.

Abstract: The screw press is a type of machine press used for extracting crude palm oil from the oil palm’s mesocarp, where its short driveshaft, a mechanical component for transmitting torque and rotation, is often found to be susceptible to failure. Since the initial damage to the short driveshafts in the shaft keyway area is associated with the frequent incidence of shaft failure, this research aimed to discover the root cause of this failure and how to prevent it using visual inspection and stress analysis methods as well as those of the fractography, metallography, chemical composition, and hardness tests. Using the descriptive method to analyse the collected data, the visual inspection and the fractography results of the research indicated that the fatigue crack failure of the short drive shaft in the palm oil screw press machine was caused by the fatigue crack initiation that was safe from stress concentration in its keyway areas. This crack initiation was followed by crack propagation as indicated in beach mark forms. Finally, the ductile fracture observed on the shaft surface was found to have resulted from the continuous rotational motion and the loading and unloading effect of the central shaft driving system.

Abstract: The present case-study was aimed at evaluating and comparing the frictional properties (friction and wear) of alternative concepts for a shaft-bushing component in comparison to the actually used benchmark system. Through the use of a specially designed shaft-bushing tribology labor-sized test setup in combination with a high-precision modular tribometer, the overall performance of alternative concepts were evaluated and compared. Benchmark shafts consisted of nitro-carburized and oxidized bearing steel and benchmark bushings were made of sintered steel. The investigated alternative concepts consisted of shafts with a different thermal pre-treatment against benchmark bushings; benchmark shafts against surface modified bushings; and lubricated benchmark bushings (instead of lubricated shafts) with two different lubrication times before testing. For each concept under study, 3 performance tests were performed in order to assess the reproducibility of the results obtained. The most promising alternative component concepts identified through this labor-sized model screen test were then field tested by IMS Gear and the obtained results were in accordance with the labor test results.

Abstract: The paper focuses on the metallographic analysis of the damaged inner shaft of a centrifugal pump with a magnetic clutch. This pump was used for the pumping of viscous suspensions. The damaged part of the centrifugal pump was made of stainless steel and transmitted power from the magnetic clutch to the impeller of the pump. The pump was overhauled by the Manufacturer after ten years of routine work. Slightly worn parts of the pump, including the inner stainless steel shaft, were replaced by the Manufacturer according to the preserved documentation. The overhauled pump failed after two days of running in the original conditions. The problematic is solved by an analysis of three used inner shafts with the aid of a metallographic analysis of the microstructure of the material, using light microscopy and scanning electron microscopy, and an EDS microanalysis of the chemical composition and hardness measurements.

Abstract: In this work, the behaviour of a palm fruit bunch press shaft is investigated, which has presented early failure several times, not reaching its expected lifetime. The study allows determining the failure mode of the shaft by using the finite element method (FEM). The model is used to estimate the load produced by the fruit bunches over the worm screw and transferred to the shaft. Geometrical analysis of the shaft shape helps to determine failure mode. The stress and strain fields are obtained to determine the critical points of the design, in order to propose modifications to the shaft design. Moreover, after a short time of operation, the structure presented plastic deformation, the hexagonal shape in the shaft is repaired using a welding procedure, as showed metallographic and hardness results obtained on surface and subsurface level of the affected area for the fractographic analysis. This is compared with a raw steel SAE AISI 4340 under tempered like original condition.

Abstract: The straightness is an important indicator in measuring the quality of shaft parts. Laser peening straightening (LPS) is a new mechanical method to straight the shaft through inducing residual compressive stress into the shaft surface. Compared with the traditional method, the process of laser peening correction is high efficiency and can be controlled precisely. In the present work, the mechanism of laser peening straightening for shaft straightness is revealed and a three-dimensional finite model is developed to investigate the effects of laser parameters for shaft straightness correction. The results show that the peak pressure and pulse duration should be more than 4 GPa and 8 ns when laser peening straightening is used to correct the shaft straightness. The straightening amount increases with laser power density, laser pulse duration, multiple laser peening. The maximum correction amount for shaft straightness with LPS is no more than 0.01mm.

Abstract: This article presents the results of a study regarding the structural optimization of the main shaft of a naval winch and its manufacturing technology. Throughout this paper, its design will also be changed and improved. The main purpose of the research here described is to reduce the mass of the shaft from an initial weight of 23 kg. The drum responsible for releasing the boats in the water is placed on the first section of the spindle. The maximum embarkation is 2141 kg (21kN), meaning the safe working load of the davit, consisting in a boat fully equiped with 10 people in it. Moreover, this value of 2141 kg, is multiplied with the safety factor of a minimum 4.5, specific for the maritime industry, in the proceeded analyzes. The other objectives of the study take into consideration the fulfiling of the functional role without having a major intervention upon the other components of the winch, the reduction of costs and the decreasing in manufacturing time. Therefore, starting from a hollow byproduct, through the processes of optimization, redesign and simulation using finite element analysis, the achieved results show a 45% reduction in the weight of the shaft and a significant shortage of the manufacturing time. In this entire proceess, only one component needs technological changes by repositioning its 4 holes. From the economical point of view, by using a tube instead of a bar, it is possible a reduction of almost 6000 USD for a batch of 1000 shafts.

Abstract: The newest technologies in the maritime field have gained a special dynamics over the last years. In particular it has been sought the improvement of the systems, procedures and rules related to environmental protection, but at the same time, lowering the fuel consumption has been targeted through various residual energy recovery methods, with an eye on lowering gas emissions in the atmosphere, in general, and CO₂ in particular.This paper is aimed at just this target and it proposes a new controllable pitch propeller changing mechanism to be analysed, that would lead to lowering of energy consumption and by default to a reduction in the fuel consumption used by the diesel-generator.

Abstract: The paper mainly studied the parametric drawing system of shaft based on feature. Firstly, the shaft was classified, and its characteristic was analyzed. Then, the special menu and image block menu of the system were designed in AutoCAD. And a friendly-interface parametric drawing system of shaft was built with geometry sculpts technology, object-oriented technology and parametric design technology, based on the platform of AutoCAD, with the development tool of Object ARX. It implemented the drawing of hardware working drawing of shaft according to the selected proportion, and improved the efficiency of the shaft design.Overview of shaftShaft is one of the main parts of machinery, depending on the axis shape; shaft can be divided into two categories: direct axis and crank shaft. According to the different load of the nature, direct axis can be divided into three types: spindle, drive shaft and the shaft. According to different shape, direct axis can be divided into two kinds: optical axis and stepped shaft. Optical axis has the following characteristics: simple shape, easy processing, less stress concentration source, optical axis is mainly used for drive shaft; Stepped shaft, in contrast to the optical axis. It is often used in the shaft. The classification of the shaft can be clearly said to use figure 1. In addition, there are some special shaft, such as the camshaft and wire soft shaft, etc.Fig. 1 Classification of the shaftOn the basis of the characteristics, the shaft information model can be considered. Usually a mechanical parts contains numerous features, shape features are the most important characteristics of these, which is the carrier of other information. We can decompose research the shape feature and think that some auxiliary features and the main features combined shape feature of axis, the main characteristics of the spatial position is adjacency relations; Auxiliary features is attached to a primary, auxiliary features can be attached to the main outline of the surface or end^[1].Combining with the actual situation of this system, we analyze the features of commonly used straight shaft parts; we obtained the shape of the feature classification results as shown in table1.Table 1 Straight shaft parts classification of shape feature