Papers by Keyword: Gear

Abstract: Generally, hard finishing is the final step in manufacturing cylindrical gears. The most established processes for hard finishing are continuous generation grinding and discontinuous profile grinding [1]. Despite the wide industrial application of the continuous generation grinding process, only few scientific investigations exist. One possible reason for this are the complex contact conditions between tool and gear flank. Modelling the complex contact conditions between grinding worm and gear to calculate cutting forces, characteristic values as well as micro- and macroscopic gear geometry are the topics of this paper. The approaches are introduced and results for validation are presented and discussed.

Abstract: Cold forging enables industrial mass production of steel based components characterized by high strength and precision. The present study focuses on the FE-based analysis of a forward extrusion process. The investigated process is the so called “Samanta”-process. In practice, this is also refered to extrusion in package. During the forming, multiple blanks are pressed sequentially through a die. The results reveal the process-specific "crown-shaped" area in the upper end region of the components. Furthermore, the tribological conditions reveal a great influence on the resulting component properties.

Abstract: For the process design of a cutting process, the knowledge of the cutting force is of fundamental importance. The cutting force influences the dimensioning of machine components and process parameters [1]. A precise interpretation of those process elements enables for high manufacturing and component accuracy. Due to the complexity of the chip geometries, the cutting force in gear hobbing is calculated by using a penetration calculation. The applied cutting force models have been developed by BOUZAKIS [2] and GUTMANN [3] in the 1980s. These models are based on data from longitudinal turning processes. Advancements in machine tool technology of the past decades have led to more efficient processes. The use of new cutting materials allows for higher speeds and feeds. This led to larger chip thicknesses. The bases of the models by GUTMANN and BOUZAKIS covers today's usual hobbing parameters not extensive enough. The influence of tempered levels on the cutting force is not included in the models. Therefore, the aim is to create a cutting force model and adjust the calculation base after GUTMANN. A radial turning process with interrupted cutting is used as analogy process. The influence of the heat treatment at 42CrMo4 is to be examined for the cutting force. This will be compensated in three different tensile strengths. The investigated process parameters are extended beyond the current state of the art.

Abstract: In order to improve load carrying capacity and noise behaviour, case hardened gears are usually hard finished. One possible process for hard finishing of gears is generating gear grinding, which has replaced other grinding processes in batch production of small and middle sized gears due to high process efficiency. Especially generating gear grinding of large module gears with a module higher than mn > 8 mm can be challenging due to high process forces and the resulting excitation, which can influence gear quality negatively. TÜRICH suggested applying a pitch diameter shift during generating gear grinding to equal out the number of contact points between the left and right flanks of the gear with the grinding tool [1]. This qualitative approach is not sufficient to predict the process behaviour because it does not take the changing radii of the curvature of the involute into account and, therefore, the changing contact conditions along the gear profile. In this paper a methodology to quantify the influence of pitch diameter shift on the generating gear grinding process using a manufacturing simulation is introduced. Additionally this methodology is validated for one manufacturing test case.

Abstract: One research objective for generating gear grinding is to increase economic efficiency and productivity of the process. Furthermore, the gear quality must be equal or higher compared to the non optimised process. In addition to the grinding process and the grinding tools, the dressing process can be suitable to lead to an increase of efficiency of generating gear grinding. Due to the variety of dressing tool specifications process users have the problem of selecting the best fitting dressing tool for their demands. Therefore, it is necessary to know the interactions of dressing tool specification and dressing tool wear. But the influence of the dressing tool specification onto dressing tool wear has yet not been sufficiently investigated for generating gear grinding.

Abstract: As is known, the gearing seems the principal excitation source into the components of the power transmission. The momentary movements of pinion driving gear and driven gear are represented by six liberty degrees, three translations and three rotations. The fluctuations of the conveyance error and of the gearing rigidity are the principal causes of the excitations associated to this one. For the conveyance error, it is necessary to tell the consequences of the elastic deformations from the kinematic consequences associated to the gearing of the non-mating profiles. In this paper is presented the simulation of the conveyance error associated to the eccentricity faults. In order to obtain the dynamic response it is suggested the using of the integral Laplace’s transform.

Abstract: In this paper is presented the development of a wheelchair intended to be use by the people with locomotors disabilities. They are presented various solutions of kinematics schemes proposed to be implemented as a mechanical transmission for the wheelchair. The developed wheelchair integrates a mechanical transmission which allows the movement in a straight line, and also in cornering. The mechanical transmission implemented contains a bevel gearbox. The purpose of the bevel gearbox is to multiply the moment transmitted to the motor wheels for movement on uneven terrain. They are presented aspects concerning the design of the wheelchair frame an of implemented bevel gearboxes.

Abstract: The increase of transverse contact ratio (ε_α) value usually allows reducing general level of gear vibroactivity. Article put to the test influence of coefficient ε_α value on dynamic forces in mesh zone with use of dynamic model of toothed gear. From theoretical point of view, the optimum value of transverse contact ratio is equal 2, what mean, that in mesh are always two pair of teeth. Obtainment such value of coefficient ε_α requires another construction of toothed wheels – wheels with HCR (High Contact Ratio) profile teeth. On result of occurrence of different deviations in toothed gears, as well as the dynamic phenomena, obtainment of continuous two-pair cooperation of gear pair is impossible and when this necessary is, solutions with near or exceed optimum value of coefficient are applied.

Abstract: Reverse engineering process has been demonstrated to be reliable solution in solving problems regarding missing information and/or details referred to the functional areas of parts. Based on the specific activities of the chain of processes that defines the reverse engineering concept it can be collected essential information in order to reconstitute important zones of broken parts. The present paper describes an approach that was used to recover a plastic gear part. The case study provided a moulded injected plastic part that was broken during the normal function. The entire process supposed scanning the toothed area that remained and rebuild the contour that was used in CAM software as input data and especially the machining strategy used to perform both sides of the part. The machining process was employed on a CNC graving machine tool.

Abstract: The manufacturing of steel gears by cold forging can be realized by using the so called Samanta process. The present study focuses on the one hand on the FE based analysis of the forming of gears in forward extrusion and on the other hand on the modelling of a Samanta process, using the software Simufact.forming. Thereby the influence of different tool geometries and the tribological conditions on the forming are investigated. The aim is to obtain a basic understanding of the material flow and the filling of the tooth cavity depending on the geometry of the Samanta process. For the investigations the common heat-treatable steel 1.7131 (16MnCr5) was used. As an input parameter for the simulation the true stress-true strain curve of the material has been determined within compression tests. For the analysis of the forming the material flow into the cavities and the shape of the tooth flanks are evaluation criteria. Thus the influence of the different parameters on the distribution of equivalent plastic strain, the forming and the reachable accuracy have been investigated.