Мониторинг технологических систем при обработке точных поверхностей сложного контура

The article presents results of the theoretical and experimental research that we conducted to determine the main reasons of errors in the geometry of complex parts on “cold” machine tools. The solution of this problem helps to improve the accuracy of cutting complex parts on CNC machines and semiautomatic machines with copiers. The proposed monitoring system improves the quality of technological systems in general. We developed a new analytical method for assessing the quality of products cut on CNC machine tools. The proposed methodology includes the following:1. Assessing the state of technological systems of machines based on the results of testing the program accuracy and rigidity.2. Controlling the state of machines based on the analysis of technological accuracy of cutting. The obtained dependences of the technological accuracy on the machine accuracy give mathematical support to the problem.3. Controlling the accuracy of cutting by adjusting control programs and changing cutting modes.We fully assessed causes and consequences of potential errors of CNC machines. This allowed us to propose alternative technological solutions and reduce the dispersion of errors of machined surfaces of complex contoured parts. Implementation of the research results in production will improve the level of technological support for the accuracy of complex contoured surfaces and the functionality of the equipment. We analyzed the results of experimental verification and established that the proposed solutions made it possible to increase the level of technological support for the accuracy of complex parts from 53 to 78 %.В статье представлены результаты теоретического и экспериментального исследования, проведенного с целью вскрытия основных причин образования погрешностей геометрии деталей сложной формы на «холодном» станке. Решение данной задачи способствует повышению точности обработки деталей сложной формы как на станках с ЧПУ, так и на полуавтоматах с копировальными устройствами. Предлагаемая система мониторинга повышает качество эксплуатации технологических систем в целом. Авторами разработан новый аналитический метод для оценки качества изделий, получаемых на станках с ЧПУ. Предлагаемая методика включает следующие пункты:1. Оценка состояния технологической системы станка по результатам испытаний на точность отработки программы и проверки на жесткость.2. Контроль состояния станка на основе анализа технологической точности обработки. В качестве математического обеспечения здесь выступают полученные зависимости технологической точности от геометрической.3. Управление точностью обработки по результатам контроля за счет коррекции программы для системы ЧПУ и изменения режимов обработки.Проведена полномасштабная оценка причин и последствий потенциальных погрешностей станков с ЧПУ, которая позволила предложить альтернативные технологические решения и уменьшить дисперсию погрешностей обработанных поверхностей сложноконтурных деталей. Внедрение результатов проведенных исследований в производство позволят повысить уровень технологического обеспечения точности поверхностей сложного контура и функциональных возможностей используемого оборудования. Анализ результатов экспериментальной проверки показал, что предложенные решения позволили повысить уровень технологического обеспечения точности деталей сложной формы от 53 до 78 %

Regenerisanje NC koda primenom 3D identifikacije i analize geometrijskih odstupanja

REZIME: Proizvodnja delova na numerički upravljanim mašinama alatkama jedna je od najzastupljenijih tehnika korišćenih u savremenim proizvodnim procesima. Čak i kod preciznog hladnog i toplog oblikovanja delova ili livenja delova, mnogi od završnih postupaka obrade i delova se obavljaju rezanjem na mašinama alatkama, a takođe se i alati za ove mašine, ovim tehnologijama obrađuju. CAD/CAM sistemi mogu da generišu NC programe na osnovu geometrije dela, ali ne pomažu programerima u izboru odgovarajućih strategija rezanja, geometrije alata i drugih parametara procesa. Komercijalni CAM softveri generišu CNC programe uglavnom sa matematičke tačke gledišta i obično sadrže konstantne parametre rezanja za određenu putanju alata i ne simuliraju očekivani kvalitet i tačnost obrađenih površina, a takođe ne uzimaju u obzir mehaničke aspekte procesa glodanja kao što su sile rezanja i devijacija reznog alata. Savremena merna oprema je sve prisutnija u mašinskoj industriji, pa se može reći da su koordinatne merne mašine postale standard i da se proizvodnja i dokumentacija velikim delom prilagođava koordinatnim mernim mašinama. Sa druge strane se još intenzivnije razvijaju beskontaktni (optički i laserski) merni sistemi. Ovi merni sistemi podrazumevaju kao razultat merenja oblak tačaka, koji zahteva procesiranje i generisanje površina u cilju merenja i kontrole. U okviru disertacije dat je pregled savremene merne opreme i predstavljeni su postupci generisanja površina i merenja odstupanja pomoću softvera, kao što su CATIA, GOM Inspect, PC DMIS i sl. Eksperimentalna istraživanja obuhvataju veoma veliki broj eksperimenata. U okviru prvog eksperimenta analiziran je uticaj širine rezanja na tačnost obrađenog dela. Sledećim eksperimentom obuhvaćen je uticaj brzine rezanja i pomoćnog kretanja na hrapavost obrađenog dela kao i na dimenzionalna i geometrijska odstupanja: ravnost, upravnost i paralelnost. Narednim eksperimentima istraživan je uticaj greške postavljanja (paralelne pomerenosti ose i nagnutosti ose) glodala kao i radijalnog odstupanja zuba glodala, na topografiju površine. Poslednjim eksperimentalnim ispitivanjima određivan je uticaj promene dubine rezanja, odnosno putanje glodala na dobijene dužinske i geometrijske mere. Realizovana eksperimentalna istraživanja su pokazala korelativnu zavisnost između parametara obrade i dobijenih parametara kvaliteta obrađenog dela. Odstupanja obrađenih delova identifikovana su i merena pomoću koordinatne merne mašine i različitih optičkih mernih sistema (ATOS) uz primenu odgovarajućih softvera za merenje. Takođe su izvršena poređenja dobijenih rezultata sa različitih mernih uređaja. Razvijen je algoritam za regenerisanje postojećeg NC koda u cilju korekcije odstupanja obrađenog dela koje se javljaju usled grešaka obrade. Algoritam predviđa postojanje baze podataka koje se potrepljuju eksperimentalnim istraživanjima, podacima iz obradnih procesa, rezultatima modeliranja i simulacija zavisnosti parametara obrade od tačnosti obrade. Regenerisanjem NC koda vrše se korekcije grešaka obrade, odnosno predupređuju se uzroci nastanka grešaka obrade.ABSTRACT: The production of parts using numerically controlled machine tools is one of the most used techniques in modern production processes. Even at the precise cold and hot shaping of parts or casting of parts, most of fine machining and parts are performed with cutting on machine tools, and the tools for these machines are also processed with these technologies. CAD/CAM systems can generate NC programs based on the geometry of a part, but do not help programmers in the selection of the proper cutting strategies, tool geometry and other processing parameters. Commercial CAM software develop CNC programs mostly from the mathematical point of view and commonly contain constant cutting parameters for a specific tool path and they do not simulate the expected quality and accuracy of the machined surfaces, and they also do not take into consideration the mechanical aspects of milling process such as cutting forces and cutting tool deviation. Modern measurement equipment is more present in manufacturing industries, so it can be said that the measuring machine coordinates have became the standard and that the manufacturing and documentation are adjusting to the coordinate measuring machines in a great deal. On the other hand, the non-contact (optical and laser) measuring systems are more intensively developed. These measuring systems as a result include a point cloud, which requires the processing and generating of surfaces for the purpose of measuring and control. In the framework of the dissertation is given the review of modern measuring equipment and the surface generating procedures and deviation measurements using the software, such as CATIA, Gom Inspect, PC DMIS, etc, are presented. Experimental researches include a very large number of experiments. Within the firs experiment, the impact of cutting width on the accuracy of processed part was analyzed. The following experiment included the impact of cutting speed and auxiliary movement of the roughness of the processed part as well as on the dimensional and geometrical deviations: flatness, perpendicularity and parallelism. Subsequent experiments examined the impact of error setup (parallel offset of axis and inclination of the axis) of the milling cutter as well as the radial deviation of mill tooth on the surface topography. In the final experiments the impact of the change of cutting depth, i.e., milling cutter path, on the obtained longitudinal and geometrical measures is determined. Conducted experimental researches have shown the correlative dependence between the cutting parameters and obtained quality parameters of machined part. Deviations of machined parts are identified and measured using the coordinate measuring machine and different optical measuring systems (ATOS) with the application of corresponding measuring software. The comparisons of the results obtained from the different measuring devices are also performed. An algorithm for generation of the existing NC code for the correction of the machined part deviations that occur due to machining error is developed. The algorithm predicts the existence of database that is supported by experimental research, data from machining processes, results of modeling and simulation of machining parameters dependence on the accuracy of the processing. Regeneration of NC code By regenerating the NC code the correction of processing errors is made, i.e., the causes of processing errors are prevented