ASPECTS REGARDING OPTIMAL DESIGN FOR THE WORM-GEAR DRIVE

It is known that, from the point of view of the accuracy of a machine-tool, at its design, the dynamic behaviour of each element of the kinematic chains prevails. Worm-gear drives are widely used in the different machine-tools and robots. Therefore, it is important that during meshing, as far as possible, there are no vibrations, shocks, power losses, noise and low durability. These requirements can be met if, for example, the gear ratio is constant during meshing, without transmission errors, which means that the worm-gear drive should have a high accuracy. The accuracy improvement of the worm-gear drive has long been a focus of attention for machine-tools designers. Thus, this paper presents various approaches to solving such problems, based on modelling and simulation, such as: estimating the load share of worm-gear drives and to calculate the instantaneous tooth meshing stiffness and loaded transmission errors; the desired worm-gear drive design configuration by altering the optimum set of worm-gear drive design parameters which are suitable for the required performance by associating it with SVM (Support Vector Machine); optimization approach for design of worm-gear drive based on Genetic Algorithm; design optimization of worm-gear drive with reduced power loss; etc. The optimization of the worm-gear design is an important problem for the research because the design variables are correlated to each other. An optimal design algorithm developed by the authors of this paper, for worm-gear drive, is also presented.

Worm Gear Drives with Improved Kinematic Accuracy

This paper presents the fundamentals of the design and applications of new worm gear drive solutions, which enable the minimisation of backlash and are characterised by higher kinematic accuracy. Different types of worm surfaces are briefly outlined. Technological problems concerning the principles of achieving a high degree of precision in machining are also described. Special attention is paid to the shaping of conical helical surfaces. Increasing the manufacturing precision of drive components allows one to achieve both lower backlash values and lower levels of its dispersion. However, this does not ensure that backlash can be eliminated, with its value being kept low during longer periods of operation. This is important in positioning systems and during recurrent operations. Various design solutions for drives in which it is possible to reduce backlash are presented. Results of experiments of a worm gear drive with a worm axially adaptive only locally, in its central section, are presented. In this solution, it is possible to reduce backlash by introducing adjustment settings without disassembling the drive. An important scientific problem concerned defining the principles of achieving a compromise between the effectiveness of reducing backlash and the required load capacity of the drive. In this paper it has been shown that in worm gear drives with a locally axially adaptive worm, as well as with a worm wheel with a deformable rim, it is possible to achieve significant reduction of backlash. In high precision drives—for example, those with an average backlash value of <15 micrometers—this can enable more than a two-fold reduction of the average backlash value and more than a three-fold decrease of the standard deviation of local backlash values.

Stresses Analysis of Roller Gear Drive

The roller worm gear drives have been widely adopted in numerous industrial applications such as robot joint reducer, heavy-duty production line. This study is to improve the performance of a roller gear drive by utilizing an iterative optimization scheme to improve the tooth profile of the hourglass worm gear in the roller gear drive. Dedicated design of the variable-pitch slot on the hourglass worm gear can remedy the power efficiency of the roller gear drive by enhancing the contact ratio dramatically. This research showed that the roller gear drive is a better mechanism for the high reduction ratio reducers. The CAD design and performance analysis of a roller gear drive by SolidWorks have provided the engineers an optimizing methodology.

TOOTH CONTACT ANALYSIS OF A DESIGNED PLANETARY GEAR DRIVE FOR THE VEHICLE INDUSTRY

A planetary gear drive consists of a sun gear, planet pinions and an internal gear. We designed a complex gear system which is usable in the field of the vehicle industry into the automatized robots. The system was designed by GearTeq software which is connected with the SolidWorks designer software. After the assembly and the motion simulations tooth contact analysis (TCA) was made to analyse the normal stresses and the normal deformations on the connecting surface of the planet pinions and the internal gear by different load moments.

Using the Box–Behnken Response Surface Method to Study Parametric Influence to Improve the Efficiency of Helical Gears

Studying gear power loss theoretically and determining the efficiency of a helical gear drive depend on many geometrical and working parameters, such as rotation speed, tooth number, gear ratio, helix angle, and torque, among others. In this paper, the Plackett–Burman screening design and the Box–Behnken response-surface method are used to consider how the above parameters influence gear drive efficiency, and experimental models are provided to evaluate these influences. The present results can be used to select the efficiency when calculating and designing gear transmissions and to choose the parameters for improving gear transmission efficiency.

Exhaust Gas Turbine

As discussed in Chapter 2, the supercharger (basically, an air compressor) can also be driven by an exhaust gas turbine. In this case, the overall system is referred to as a turbocharger or turbosupercharger (Abgasturbolader in German). The focus in Kollmann’s manuscript is exclusively on radial compressors used as superchargers driven by a gear drive connected to the main engine shaft. This is not so surprising considering that, although significant R&D effort was spent on the turbine design (especially, turbine blade cooling), turbocharged German aircraft engines did not enter service until the end of the war. Even then, the service experience was limited to Junkers Ju 388 (mostly for high altitude reconnaissance) powered by two 1,500-HP BMW 801 J turbocharged engines. Many other designs (e.g., the DB 623) were eventually abandoned. The dilemma facing the German engineers at the time (1940s) was this: whether to develop an aircraft engine from the get-go with a turbocharger or to develop a turbocharger to be fitted into an existing engine (e.g., the DB 603). Since the need for the turbochargers arose during the war by the need for higher flight altitudes (10 to 14 km), e.g., to attack the Allied bomber formations and their fighter escort, the urgency of the situation made the choice for them1. Not surprisingly, they went with the latter option.

Development of a Bionic Dolphin Flexible Tail Experimental Device Driven by a Steering Gear

In order to study the mechanism of the tail swing of the bionic dolphin, a flexible tail experimental device based on a steering engine was developed. This study was focused on the common three joint steering gear and its use in a bionic dolphin tail swing mechanism, and it was found that the bionic dolphin driven by the steering gear had the problem of excessive stiffness. In order to solve this problem, we designed a bionic dolphin tail swing mechanism. The tail swing mechanism was designed rationally through the combination of a steering gear drive and two flexible spines. Analysis of kinematic and dynamic modeling was further completed. Through simulation using, the research on the bionic dolphin tail swing mechanism was verified. Experiments showed that the swing curve formed by the steering gear-driven bionic dolphin tail swing mechanism with two flexible spines fit the real fish body wave curve better than the original bionic dolphin tail swing mechanism.