•Design parameters for steel/PEEK gear pairs were determined.•Grease lubrication increased the PEEK gear's lifespan by a factor of 1.23.•Trovalisation of the steel gears increased the PEEK gear's ...lifespan by a factor of 2.54.•Indicator of the steel/PEEK gear pair's coefficient of friction was determined.•Tip rounding or tip relief reduces the pressure peaks and the polymer gear's wear.
The parameters necessary for the reliable design of PEEK gears were determined. The effect of a steel gear's surface on the polymer gear's wear was investigated. Values for the wear coefficient of a steel/PEEK gear pair in dry and lubricated conditions are proposed. Testing showed that, on average, grease lubrication extends the lifespan of PEEK gears by a factor of 1.23, while the additional treatment of steel gears with trovalisation and lubrication extends the lifespan by a factor of 2.54. Temperature measurements were used to determine the coefficient of friction that is required to compute the operating temperature of a steel/PEEK gear pair. Using numerical simulations it was found that a proper tooth tip relief can improve the meshing and results in a further extension of the gear's lifespan.
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Increased competition in the global market has forced companies to diversify their product ranges to meet the customers' changing needs and adopt product development strategies for mass customization ...or even one-of-a-kind production, which inevitably requires designing modular products. Product modularity is achieved via platform-based systems, in which various combinations of different modules are assembled within a common platform. The smart factories that are already beginning to appear to employ a completely new approach to product creation. In smart industry, dynamic business and engineering processes enable last-minute changes to design and production, delivering the ability to respond flexibly to disruptions and failures on behalf of suppliers. This paper presents a case study of product development and design process renovation according to agile and lean principles in one-of-a-kind industrial environments. It defines how changeability integrates with robust, concurrent and smart design strategies. Introduction of agility to highly individualized production environments is mostly about enhancing the robustness of new product development processes. Product development and manufacturing processes are interconnected therefore they need to be re-engineered together. The presented work aims to deliver a generalized conceptual framework that demonstrates how companies in such specific environments can improve smartness and profitability through the utilization of agility concepts.
Abstract
The article presents a comprehensive study on the tooth bending strength of spur gears with a progressive curved path of contact, or so-called S-gears. Systematic gear meshing simulations ...were conducted to study the effects of S-gear geometry parameters on tooth bending strength. Different S-gear geometries were analysed in a systematically organized manner, and a comparison was made against a standard 20° pressure angle involute shape. Furthermore, different material combinations, e.g. polymer/polymer, steel/polymer, and steel/steel, of both drive and driven gear were analysed within a meaningful range of loads. The gear profile shape, material combination of the drive and the driven gear, and the transmitted load were found as the main parameters affecting gear tooth bending stress. Complex, non-linear relations between the recognized effects and the corresponding root stress were observed. Based on the numerical results, a shape factor, which considers the above-mentioned effects, was introduced, and a model for root strength control of S-gears was proposed and verified employing the finite element method (FEM).
Graphical Abstract
Graphical Abstract
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•Sliding friction during polymer gear meshing generates dominant part of heat losses.•The developed flash temperature model is based on numerical and analytical tools.•Meshing ...kinematics influence considerably the frictional losses and temperature rise.•Flash temperature model applicable to any type of spur gear geometry.•The model provides necessary groundwork for long term nominal temperature analysis.
The temperature increase that occurs during running of a polymer gear pair can be divided into two components: the nominal and flash temperatures. The latter denotes the short-term temperature increase that takes place during a gear meshing cycle. A thorough analysis of the flash temperature yields an insight into the heat dissipation process, which also determines the nominal temperature increase. We focus here on the flash component using numerical and analytical computation tools, with which we can obtain realistic predictions of the temperature increase during a gear meshing cycle. The analysis is performed using a decoupled procedure that involves a mechanical finite element analysis, followed by a semi-analytical temperature evaluation method based on the computed mechanical response of the system. With it, we obtain an improved flash temperature model that offers an accurate representation of the real life thermo-mechanical processes taking place at the gear teeth contact interfaces.
Abstract
A reliable method of optimization of polymer gears remains, to date, an open challenge, due to the lack of specific material characterization of polymers and to the complex nonlinear ...relations between different geometric and operating parameters. For spur and helical gears, the authors herein have developed the optimization algorithm, which primarily enables variation of geometry according to various criteria: the number of teeth (z1, z2), face width (b), helix angle (β), and normal module (mn). The method enables a better insight into how design parameters influence the target criteria. The main paper contribution is a newly developed multicriteria function that enables a simultaneous consideration of different criteria such as root/flank stress, gear bulk/flank temperature, wear, deformation, quality, cost, and volume.
The main focus of this paper is the empirical modelling of the wear of carbon brushes. Rather than determining the dominant wear mechanisms, an approach towards the prediction of wear under a range ...of different conditions was used. The models were obtained by multiple regression analysis using lifetime (LT) data contributed by the biggest European manufacturer of vacuum cleaner motors. This included reliability data for 607 different test populations involving 3980 motors. Exploration of the data revealed that wear-out parameters behaved in accordance with the existing field theory, giving additional confidence to the models. The numerical appreciation of the wear-out parameters and the resulting conclusions will be beneficial to motor design and reliability engineers. Learned knowledge will be used for faster selection of optimal design and operational motor parameters to meet recent EU regulation 666/2013. Along with the more rapid design of the product, a reduced number of LT tests will result in significant energy savings.
This article examines the influence of incident angle, object colour and measurement distance on the computer numerically controlled laser scanning process. To determine the physical background of ...these influences, the operation of the triangulation sensor, the surface reflection and the colour properties of the measured object were analysed. The various influences and their physical background are explained by using a test-measurement setup, which makes it possible to investigate a specific influencing factor. The article concludes with several guidelines that should be followed in order to obtain better measurement results.
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