Large, multi-segmented girth gears do not behave like the relatively compact, rigid, monolithic structures we typically envision when discussing gear manufacturing. Girth gears are very large, non-rigid structures that require special care during the machining of individual mating segments as well as the assembled gear blank itself.
This article presents an analysis of asymmetric tooth gears considering the effective contact ratio that is also affected by bending and contact tooth deflections. The goal is to find an optimal solution for high performance gear drives, which would combine high load capacity and efficiency, as well as low transmission error (which affects gear noise and vibration).
Free form milling of gears becomes more and more important as a flexible machining process for gears. Reasons for that are high degrees of freedom as the usage of universal tool geometry and machine tools is possible. This allows flexible machining of various gear types and sizes with one manufacturing system. This paper deals with manufacturing, quality and performance of gears made by free form milling. The focus is set on specific process properties of the parts. The potential of free form milling is investigated in cutting tests of a common standard gear. The component properties are analyzed and flank load-carrying capacity of the gears is derived by running trials on back-to-back test benches. Hereby the characteristics of gears made by free form milling and capability in comparison with conventionally manufactured gears will be shown.
This paper presents a new approach to repair industrial gears by showing a case study where pressure angle modification is also considered, differently from the past repairing procedures that dealt only with the modification of the profile shift
coefficient. A computer program has been developed to automatically determine the repair alternatives under two goals: minimize the stock removal or maximize gear tooth strength.
Multiple possibilities are available to increase the transmissible power of girth gears. These solutions include: using a larger module, increasing of the gear diameter through the number of teeth, enlarging the face width, and increasing the hardness of the base material. The first three parameters are mostly limited by cutting machine capability. Module, outside diameter, and face width (for a cast gear) can theoretically be increased to infinity, but not the cutting machine dimensions. There are also practical limits with respect to the installation of very large diameter/large face width gears.
At first sight the appearance of 5-axis milling for bevel gears opens new possibilities in flank form
design. Since in comparison to existing machining methods applying cutter heads no kinematic
restrictions exist for 5-axis milling technology, any flank form can be machined.
Nevertheless the basic requirements for bevel gears did not change. Specifications and functional
requirements like load carrying capacity and running behavior are still increasing demands for design
and manufacturing. This paper describes the demands for gear design and gives an overview about
different design principles in the context of the surrounding periphery of the gear set.
In the design process of transmissions, one major criterion is the
resulting noise emission of the powertrain due to gear excitation.
Within the past years, much investigation has shown that the
noise emission can be attributed to quasi-static transmission error.
Therefore, the transmission error can be used for a tooth contact
analysis in the design process, as well as a characteristic value for
quality assurance by experimental inspections.
Excessive machine tool vibration during a precision grinding operation can result in poor workpiece quality in the form of chatter, rough finishes, burn, etc. One possible reason for
excessive vibration is directly associated with the relationship
between natural frequencies of a machine tool system and the
operating speed of the grinding wheel spindle.
This proposed standard would not make any recommendations
regarding the required quality for any application. The
intent is to establish standard pre-finish quality classes for typical
finishing operations, which only include the inspection elements
that are important to properly evaluate pre-finish gear
quality as it applies to the finishing operation. It would be the
responsibility of the manufacturing/process engineer, quality
engineer, or other responsible individual to establish the
required pre-finish quality class for their application.