Purpose: – The purpose of this paper is to present the use of a CAD system for the analysis of meshing of spiral bevel gears. Design/methodology/approach: – The TCA computer programs are based on a purely mathematical model and require to get the numerical solution of a set of nonlinear equations. There are situations that the programs fail to obtain the proper solution. In such cases, geometrical gear models defined in CAD environment prove to be a good choice. This paper describes a tool for analyzing tooth contact and transmission errors of spiral bevel gear sets with tooth flanks represented as CAD free-form surfaces. Findings: – A new method has been proposed to keep those surfaces in continuous contact in the whole range of meshing of a mating tooth pair. During meshing, the points of contact as well as the corresponding angles of rotation of both the pinion and the ring gear are recorded. Thus, the tooth contact path as well as the motion transmission error graph is determined. Then, the contact pattern that is formed by a set of instantaneous contact ellipses is designated. Practical implications: – The TCA results are essential for the assessment of the gear set quality in the early stages of the process of its development. Originality/value: – All the results presented in graphical form are very illustrative and easy to interpret.

Achieving roughness parameters on tooth flanks for highly loaded gears and creating their non-directional surface texture are key to obtaining the required gearbox lifetime, durability, and performance. Many finishing techniques are well-known and described in technical literature, including gear teeth final grinding, shaving, honing, and superfinishing to create the proper surface condition. Unfortunately, there is still a lack of a simple finishing method which can be applied to highly loaded gears in the manufacturing process in order to optimize cost, time, and waste. This work presents the effect of a non-chemical, abrasive, highly effective process to remove quite a large amount of material from gear teeth flanks. The researched technology is called Stream Finishing (SF). The surface condition was inspected to observe its properties before and after the proper SF process parameters definition. It is useful for transmissions groups to define the proper manufacturing process application for obtaining the required gearbox lifetime within optimized parts cost. For each application the process parameters definition shall be determined individually and tested.

In general, slew bearings are less firmly supported by their mounting structures than small bearings. Hence, the load distribution around the bearing may be vastly different than that predicted by classic bearing formulas. The finite element method has been employed to determine load distribution in a three-row roller slew bearing mounted between two flexible, ring shaped supporting structures composed of beam elements. A special bar element modeling the system of two opposite rollers in contact with its raceways has been elaborated. The influence of the nonlinear force displacement characteristics of each of the rollers, as well as the influence of gaps between the rollers and its raceways have been taken into account. The nonlinear contact problem has been solved utilizing the Newton-Raphson method with continually updated stiffness matrix due to both element nonlinearity and contact status. The effect of a number of design parameters on the load distribution has been investigated.

This study describes the methodology for modelling a worm and worm wheel of a double enveloping worm gear with the use of a CAD system. An algorithm for generating a globoid helix is described. In addition, the methodology for modelling an hourglass worm thread with a straight axial tooth profile is presented. The shape of the hourglass worm tooth end with and without a trace modification is proposed. Moreover, a method for achieving a geometric modification of the tooth trace was developed. Next, the method for modelling the worm wheel teeth is described. A solid model of using a machining worm as a hob is applied. Owing to the limitations of a CAD system, which prevents the use of a direct machining simulation, an indirect modelling method is introduced. In the present study, different CAD techniques, both solid and surface, are applied. Knowledge of the correct modelling of the hourglass worm and worm wheel facilitates their generation and conducting various analyses, including a tooth contact analysis. CAD models are utilised to analyse the geometrical contact pattern in a CAD environment, to carry out FEM analysis, to manufacture real parts or to prototype models using the technique of rapid prototyping. They can be also used as master models for measurement, e.g. in optical technics.

This paper presents a methodology for the quasi-static measurement of the failure torque of polymer gear pairs manufactured using additive manufacturing technologies. A dedicated test method and measurement rig were developed to enable testing of gear pairs subjected to torque loading under quasi-static conditions. The method is based on continuous recording of torque and angular displacement, while the failure torque is identified as the first local maximum of the torque–angle characteristic preceding a rapid loss of load-carrying capacity. Gear pairs manufactured from two polymer materials were investigated: PLA produced using the FFF technology and the RGD720 photopolymer produced using the PolyJet technology. Two design variants of the driven gear were analysed: a reference variant with a hub of constant axial cross-section and a solid load-bearing web, and a modified variant incorporating a thin-walled web and reinforcing ribs. This approach made it possible to assess the influence of modifications to the hub and gear web geometry on the maximum transmitted torque and the failure mechanism. The obtained results showed that modifying the gear geometry reduces its load-carrying capacity, with the extent of this reduction depending on the material and manufacturing technology. For PLA gears, lightweighting of the web reduced the mean failure torque from 245.9 Nm to 214.3 Nm, whereas for RGD720 gears it decreased from 199.8 Nm to 139.0 Nm. Different failure modes were observed: PLA gears failed locally at the teeth, whereas RGD720 gears showed brittle global cracking, especially in the lightweight variant.