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The modelling of a curl of surfaces associated with a pair of rolling centrodes, when it is known the profile of the rack-gear's teeth profile, by direct measuring, as a coordinate matrix, has as goal the determining of the generating quality for an imposed kinematics of the relative motion of tool regarding the blank. In this way, it is possible to determine the generating geometrical error, as a base of the total error. The generation modelling allows highlighting the potential errors of the generating tool, in order to correct its profile, prior to using the tool in machining process. A method developed in CATIA is proposed, based on a new method, namely the method of "relative generating trajectories". The analytical foundation is presented, as so as an application for knows models of rack-gear type tools used on Maag teething machines. [ABSTRACT FROM AUTHOR]

The transmission based on precessional gear pairs, mostly used for rotation speed reduction, has some important advantages relative to the common gear drives, such as the capability to produce very low transmission ratios, or the high loading capacity/dimensions ratio (due to the fact that all the teeth of a precessional gear pair are simultaneously in contact during its functioning). One among the likeliest constructive solutions for the precessional gear pair uses a satellite built with conical rollers. However, its practical use is restricted by the difficulty to realize the central gear teeth machining without using special and relative complicated devices. This paper introduces a technological substitutive profile for the central gear tooth, which enables the use of a simpler and more productive method for working it, without bringing major negative consequences regarding the teeth contact correctness or the drive loading capacity. The profile was found by analyzing the contact surface and the pressure angle evolution during the contact between conjugate teeth. The paper also presents technological solutions to generate the new tooth profile by milling it with a disk-tool or an end-mill cutter, together with methods to profile the required tools. [ABSTRACT FROM AUTHOR]

The cutting processes with tools that generate “through-winding straight-involute teeth-gears”, tools associated with couples of centrodes-in-rolling (such as the rack-tool), are characterized by a fairly complicated cutting scheme, due to the specific shape of the tools and, at the same time, due to the rolling process of the axodes associated with the tool and the blank. The present solutions are not accorded well enough to the process and lead to significant variations in the detached chip area value regarding the machined wheel teeth number. It is accepted that the main cutting force size depends on the size of the area of the cutting layer (the geometrical area of the once detached chip by the assembly of operative edges of this kind of tools). The geometrical modeling of the generation process proves this and it could be considered a criterion for the reconfiguration of the cutting tool. In this work, there is defined a criterion so as to describe the cutting scheme, and based on this criterion we can compare the variation laws for the chip area size when generating the modeling of the cylindrical straight teethed gears. We propose a modeling of the cutting schemes in order to get new constructive forms of the cutting tools that will lead to cutting schemes adaptable to the number of teeth of the processed gear with the purpose of diminishing the teething cutting force. Also, there is presented a constructive solution for a rack-tool with reconfigurable structure with the purpose of according the teething process with the processed gear number of teeth. [ABSTRACT FROM AUTHOR]