Комп’ютерне моделювання забезпечення точності збірного різального інструменту

Дисертація на здобуття наукового ступеня магістра за спеціальністю 8.05050302 – інструментальне виробництво. – Національний технічний університет України «Київський політехнічний інститут імені Ігоря Сікорського». – Київ, 2018 На основі аналізу сучасних методів забезпечення точності збірок на етапі конструювання різальних інструментів було обрано метод статистичних досліджень, який базується на використанні методики Монте-Карло. Виходячи з результатів порівняльного аналізу систем автоматизованого розрахунку розмірних ланцюгів, було обрано модуль розрахунку 3DCS, та систему автоматизованого проектування CATIA V5, в яку інтегрується даний модуль. Розроблена методика підготовки моделі різального інструменту для дослідження в середовищі проектування. За її допомогою було проведено дослідження характеристик точності збірного різального інструмента. З огляду на конструктивні особливості збірки, було визначено структуру дерева збірки та кінематичні рухи складання. Проведено обробку та аналіз результатів дослідження. Визначено вплив допусків компонентів збірки на зміну діаметра, радіального та торцевого биття досліджуваного інструмента. Запропоновано рекомендації щодо оптимізації допусків та відхилень компонентів збірки.Thesis for a Master's Degree in specialty 8.05050302 – tool production – National Technical University of Ukraine “Kiev Polytechnic Institute of Igor Sikorsky's Name” – Kiev, 2018 On the basis of the analysis of modern methods of assuring the accuracy of assemblies at the stage of the design of cutting tools, a method of statistical research was chosen which is based on the use of the Monte Carlo method. On the grounds of the results of the comparative analysis of automated calculations of dimensional chains, was selected the 3DCS calculation module and the CATIA V5 automated design system, in which this module is integrated. The method of preparing a model of a cutting tool for research in the design environment was developed. With its help, conducted the research of the characteristics of the assembly cutting tool accuracy. Considering the structural features of the assembly, were determined the structure of the assembly tree and the kinematic assembly patterns. The processing and analysis of the research results were carried out. Were determined the influence of the tolerances of assembly components on the change of diameter, radial and face runout of the investigated instrument. Were suggested recommendations for optimization of tolerances and deviations of the assembly components

A static analogy for 2D tolerance analysis

Purpose - This paper aims to present a method for the tolerance analysis of mechanical assemblies that is suitable to nonlinear problems where explicit functional equations are difficult or even impossible to write down. Such cases are usually modelled by linearised tolerance chains, whose coefficients (or sensitivities) are calculated from assembly data. Design/methodology/approach - The method is based on the free-body diagrams of force analysis, which are shown to be related to the sensitivities of linearised functional equations. Such an analogy allows the conversion of a tolerance chain into a corresponding static problem, which can be solved by common algebraic or graphical procedures. Findings - The static analogy leads to a correct treatment of tolerance chains, as the analysis of several examples has confirmed by comparison to alternative methods. Research limitations/implications - Currently, the method has only been tested on two-dimensional chains of linear dimensions for assemblies with nonredundant kinematic constraints among parts. Practical implications - The proposed method lends itself to ready application by using simple operations with minimal software assistance. This could make it complementary to current methods for calculating sensitivities, which are mathematically complex and require software implementation for deployment in industrial practice. Originality/value - Analogy with force analysis, which has not been previously highlighted in the literature, is a potentially interesting concept that could be extended to a wider range of tolerancing problems

COMPUTER AIDED TOLERANCING BASED ON ANALYSIS AND SYNTHETIZES OF TOLERANCES METHOD

International audienceThe tolerancing step has a great importance in the design process. It characterises the relationship between the different sectors of the product life cycle: Design, Manufacturing and Control. We can distinguish several methods to assist the tolerancing process in the design. Based on arithmetic and statistical method, this paper presents a new approach of analysis and verification of tolerances. The chosen approach is based on the Worst Case Method as an arithmetic method and Monte Carlo method as a statistical method. In this paper, we compare these methods and we present our main approach, which is validated using an example of 1 D tolerancing

Model-based definition in computer aided tolerance analyses

Recent advancements in means of data collection and utilization have stepped forward to the realization of model-based definition approaches in product and production development processes. This realization is further facilitated by the presentation of open-source standards for model-based definition including STEP AP 242 and QIF 3.0. As a result, engineers are empowered with a significant amount of data to improve the development processes, particularly the tolerancing and metrology processes. This paper evaluates the opportunities enabled in the era of tolerance analyses, particularly computer-aided tolerance analyses by model-based design approaches particularly through the utilization of STEP AP 242 and QIF 3.0 standards. The main breakthrough in these standards is the semantic representation of tolerancing data in the models. However, the existing methods of modeling and analyzing tolerance information are diverse and not all these methods can utilize the new standards in the same manner. The potential usages of the new standards in different tolerance modeling techniques are reviewed. Furthermore, the research gaps and wishes for further improvements in the tolerance analysis era through model-based definition are discussed

A dimensional tolerancing knowledge management system using Nested Ripple Down Rules (NRDR)

This paper proposes to use a knowledge acquisition (KA) approach based on Nested Ripple Down Rules(NRDR) to assist in mechanical design focusing on dimensional tolerancing. A knowledge approach to incrementally model expert design processes is implemented. The knowledge is acquired in the context of its use, which substantially supports the KA process. The knowledge is captured which human designers utilize in order to specify dimensional tolerances on shafts and mating holes in order to meet desired classes of fit as set by relevant engineering standards in order to demonstrate the presented approach. The developed dimensional tolerancing knowledge management system would help mechanical designers become more effective in the time-consuming tolerancing process of theirdesigns in the future

Проблеми механічної обробки. Частина 2

Розглянуто проблеми механічної обробки під час застосування окремих типів інструментів та результати їх вирішення. Запропоновано конкретні рекомендації для впровадження у промисловість отриманих результатів. Для усунення проблем оброблення зубчастих коліс приведені висновки теоретич-ного аналізу процесів формоутворення з результатами промислового випробування. Розглянуто проблеми та їх усунення при утворенні різьбових з'єднань у титанових матеріалах за допомогою мітчиків. Наведено теоретичні основи проектування торцевих фасонних фрез з конічною передньою поверхнею різального елемента.The problems of machining during the application of certain types of tools and the results of their solution are considered. Specific recommendations for the implementation of the obtained results in the industry are offered. To eliminate the problems of gear machining, the conclusions of the theoretical analysis of molding processes with the results of industrial testing are given. Problems and their elimination at formation of threaded connections in titanium materials by means of taps are considered. Theoretical bases of designing end shaped mills with a conical front surface of a cutting element are given.Рассмотрены проблемы механической обработки при применении отдельных типов инструментов и результаты их решения. Предложены конкретные рекомендации для внедрения в промышленность полученных результатов. Для устранения проблем обработки зубчатых колес приведены выводы теоретического анализа процессов формообразования результатам промышленного испытания. Рассмотрены проблемы и их устранение при образовании резьбовых соединений в титановых материалах с помощью метчиков. Приведены теоретические основы проектирования торцевых фасонных фрез с конической передней поверхностью режущего элемента

A tolerance analysis and optimization methodology: the combined use of 3D CAT, a dimensional hierarchization matrix and an optimization algorithm

We propose a methodology in this study for the analysis and the optimization of assembly tolerances. A combination of three components, it involves the use of 3D CAT software, a table referred to as a “dimensional hierarchization matrix” and a tolerance optimization algorithm. The Antolin Group, a Spanish multinational in the automobile components sector, employs this system to optimize tolerance values and to reduce manufacturing costs. The matrix was designed to enable easy identification, in a single table, of all requirements that fail to meet the specifications in the different approximations, prior to the definition of the dimensional and the geometric tolerances that comply with the functional requirements, and to identify which tolerances contribute most to variations in all of the functional conditions of the mechanism. Through its different iterations, this matrix allows us to see which of the tolerances should first be modified to optimize the design requirement specifications. A tolerance optimization algorithm was also defined, which functions with the data from the dimensional hierarchization matrix