Papers by Keyword: Honing

Abstract: One of the key parameter in evaluation of cylindrical surface quality of the engine liners is surface roughness. A large number of process factors affecting a final surface topography, which has direct impact on fuel consumption and CO₂ emission. A suitable choice of honing conditions can results not only to better surface quality, but it can contributes to reducing of environmental impacts in automobile transport. Twelve different engine cylinder liners were machined in various combinations of cutting parameters. Experimental testing was realised on real production machine tool, where process factors were cutting speed, machining allowance and stone pressure of honing tool. All factors have 4 levels and parameters of surface roughness CR, CF, CL were selected as a variables and suitable indicators for surface quality assessment. The results show that influence of the tool stone pressure on honed surface is more significant than effect of cutting speed. Effect of machining allowance is negligible as well.

Abstract: Honing experiments were carried out for nickel-based superalloy Inconel718 bore. The significance analysis of the four honing parameters: spindle speed, stroke speed, wedge feed per stroke cycle and grain size on the surface roughness, was studied with the orthogonal design method. And the significant degree under the rated conditions was determined. The results showed that: wedge feed per stroke cycle and grain size have a significant influence on surface roughness while spindle speed and stroke speed had no significant effect. Also, there was a positive correlation between surface roughness and wedge feed per stroke cycle and grain size. Furthermore, the honed surface topography was analyzed by the meaning of microscope.

Abstract: The internal combustion engine of the future has to cope with increasing high requirements. A large potential is seen in reducing friction in the piston group. For this purpose a coating technology for cylinder running surfaces, including mechanical machining processes was developed. By substituting the compact cast iron liners (4 mm wall thickness) for the thin coating layer (0.1 mm) the normal forces become more important in the honing process. Due to the different stiffness of the crankcase roundness deviations occur caused by the machining forces as a result of elastic deformation. Content of this paper is the calculation of the elastic deformations using the finite element method. Based on a honing tool model, the effective normal forces are calculated, which afterwards are used as input variables for the crankcase model.

Abstract: The honing is one of the most common processes used for finishing, especially for vehicles motors, ships motors etc. The national and international researches in the field were developed long time ago. They regarded the establishment of some proper working conditions for actual situations, based on the type of the processed material, the type of the abrasive material and on the working equipment. The objective of this research was to establish optimal working parameters: the spindle speed and the linear-alternative speed of the hone and the processing period in order to obtain the desired values of roughness, necessary for the proper functioning of the motors.

Abstract: A variety of current scientific work shows the importance and possibilities of an effective conditioning of tribological contacts to minimize friction and wear, respectively an increase in performance of tribological highly stressed components. By slight modifications of the finishing process positive effects like the increase of lifetime or increase of power can therefore be generated. Based on this approach the tribological system piston ring/cylinder running surface of internal combustion engines is an example with high potential for optimization of production. This paper introduces alternative production and conditioning processes. The evaluation of chemical modifications of boundary layers, which are used in addition to the topography as a representative indicator for the description of the functionalities of produced surfaces is considered to be a special aspect. The present paper combines considerations of manufacturing technology with tribological tests showing the relationships and dependencies between the process characteristics of finishing and the operational behavior of the examined components.

Abstract: Cylinder bore finishing requirements are defined by quality features such as roundness and cylindricity as well as by the manifestation of the surface profile. Honing is a proven manufacturing method s to achieve this. Undesirable distortions of the cylinder shape occur under operating conditions in a reciprocating internal combustion engine. These negatively affect the tribological system of piston, piston ring, and cylinder bore. As a result, efficiency deteriorates and oil consumption rises. The cylinder crank cases are finished in a defined tensioned state to compensate for distortions. This results in a highly complex manufacturing process and is only suited for compensating static distortions. Further increasing machining requirements resulting from strategies such as lightweight construction, downsizing, and friction reduction are pushing conventional honing methods to their technological limits.Adaptronic form honing constitutes a production engineering approach to manufacturing a free form in the cylinder bore. The objective is to keep inverse distortion geometries in store as macro shapes. These will then represent ideal cylinder shapes under the influence of distortion mechanisms in a defined engine operating range. Tool and process development and the analysis of machining results with respect to productivity, shape accuracy, and surface topography are presented and viewed as potential options for optimizing the tribological system of piston, piston ring, and cylinder bore. Other options such as shortening the process chain will be derived.

Abstract: The paper discusses the investigations on combustion engines that aim at the evaluation of the influence of engine design modifications on the exhaust emissions under application of lubricants of different physicochemical parameters. In the engines the authors applied laser treated cylinder liners, piston rings of reduced pressure force on the cylinder liner and optimized the assembling clearances in the slide bearings. The research was carried out in accordance with the ESC and ELR compliant procedures using different engine lubricants. The measurement series were performed for diesel engines of the capacity of 1.3 dm³ of the power outputs of 51 kW and 66 kW. The tested objects were fitted with aftertreatment systems (oxycat and DPF filter).

Abstract: It is known that one of the basic requirements of the market economy is product competitiveness; competitiveness ensures their operating performance and the costs of obtaining them and therefore manufacturing costs. Process smoothing of the cylindrical internal surfaces must ensure a very high diameters precision and a low surface roughness. Cylindrical inner surface smoothing can be achieved through the following processes: indoor spinning roller, honing, lapping, etc. Fine machining processes without material removing, ensures based on the initial surface quality, initial quality metal cutting, work regime that is processed, hardness increasing by (20…60)%, roughness Ra=(1.6…0.4)μm, and fine processing procedures with material removal, ensures a high quality of machined surfaces, resulting in roughness Ra=(0.4…0.02)μm. Deformed layer size reducing at the previous processing, and reducing of micro depths serving as lubricant deposits, contributes to increasing wear resistance of cylinder surface. Cylinder inner surface smoothing by honing machines is performed on honing machines with a specially designed tool called hon. In the honing process, abrasive grain trajectories are forming on the cylinder a network of fine spiral lines. If carried out on a flat surface, these helical lines become straight and intersecting an angle 2α. Processing accuracy depends on the accuracy of the previous bore. In this paper, the focus is on several methods of heat engine cylinder forming the passage of the piston and rings share repair and their effect giving the engine operating parameters specified by eliminating the running operation. With the help of experimental and theoretical data and the methodology of approach to the subject, several aspects have been clarified regarding the depth of the asperities on the honed surface compared to a process-smoothed surface. The influence of all factors on the processing results has not been thoroughly explained. The following research methods shall be discussed in the future: improving the method of adjusting the pressure of the centrifugal rollers with the help of an automatically controlled device and the creation of an auxiliary device to adjust the bars to which the rollers are connected according to the internal diameter of the processed cylinders.

Abstract: On the foundation of researching adhesion mechanism of superalloy honing stone, theoretical analysis and mathematical modeling of parameters were made that affecting the wear particle adhesion rate of superalloy honing stone, then inspect and verify the relation between the adhesion rate and processing parameters through the experiment. Draw the conclusion that when the honing pressure increases or the speed of work piece decreases, the adhesion rate α_a will increase.

Abstract: Optimisation of technological processes is an important field of research of machining processes. Honing process, its aim and results are affected more factors. Effectiveness is expressed by the following parameters: accuracy, surface roughness, complex surface quality (integrity),material removal rate, costs and productivity of the process. Developed method helps the technology planning and with the introduced new goodness indicator, investigates and corrects it. Optimization and minimization of costs can be ensured at given technological circumstances and technological parameters. With adjustment of the pressure (p) and the cutting speed (v_c) economy of the process can be increased in the factory. Developed method can be applied for machining by other abrasive cutting tools. The paper summarizes new results of this theoretical and experimental research.