Predicting of milling forces in a virtual manufacturing system

Predviđanje sila duž putanje alata jedna je od osnovnih funkcija cilja virtualnog obradnog sustava za operacije CNC glodanja. U ovom radu, razmatranje je ograničeno na glodanje kontura u ravnini z=const, ravnim vretenastim glodalima. Predviđanja se zasnivaju na simulaciji trenutnih vrijednosti komponenata sile glodanja na jednom okretaju alata. U simulaciji se koristi diskretizirana rezna geometrija (diskovi) vretenastog glodala. Predstavljena su dva pristupa za rekonstruiranje kontaktne površine alata i radnog predmeta. Prvi pristup podrazumijeva aproksimaciju obujma obratka pomoću z-mape. Drugi predstavljeni pristup odnosi se na izračunavanje ulaznih/izlaznih kutova zahvata u operacijama 2D obrade glodanjem, pri konstantnoj dubini. Rekonstrukcija tih kutova zasniva se na poznavanju prethodno formiranog bočnog dodatka za obradu i na opisu putanje alata. Predstavljene procedure predviđanja sila glodanja su implementirane u Matlab okruženju. Pokazani su rezultati eksperimentalne verifikacije predloženih procedura.Forces prediction along the tool path is one of the basic goal functions of the virtual machining system for CNC milling operations. In this paper, the discussion is limited to the contour milling in the plane z=const, using the flat end mills. Predictions are based on the simulation of the instant values of the milling force components during one tool revolution. Simulation uses discretized cutting geometry (discs) of end mill. This paper presents two approaches for reconstruction of tool/workpiece contact area. The first one implies the approximation of the workpiece volume using the z-map. The second presented approach calculates entry/exit angles at the 2D milling operations with the constant depth. Reconstruction of these angles is based on the analysis of previously formed radial stock and description of the tool path. Presented procedures for the predicting of milling forces have been implemented in the Matlab. Results of experimental verification of the proposed procedures are presented

A Tool Path Modification Approach to Cutting Engagement Regulation for the Improvement of Machining Accuracy in 2D Milling With a Straight End Mill

In two-dimensional (2D) free-form contour machining by using a straight (flat

Process planning for an Additive/Subtractive Rapid Pattern Manufacturing system

This dissertation presents a rapid manufacturing process for sand casting patterns using a hybrid additive/subtractive approach. This includes three major areas of research that will enable highly automated process planning; a critical need for a rapid methodology. The first research area yields a model for automatically determining the locations of layers, given the slab height, material types and part geometry. Layers are chosen such that it will avoid catastrophic failures and poor machining conditions in general. First, features that are possible thin material machining positions are defined, and methods for detecting these feature positions from an STL model are studied. Next, a layer thickness calculation model is presented according to positions of these features. The second area focuses on tools and parameters for the subtractive side of processing each layer. A tool size and machining parameter selection model is presented that can automatically select tool sizes and machining parameters, given layer thickness, part geometry, and material types. Machining strategies and related machining parameters are studied first. Then the method for Stepdown parameter calculation is presented. Finally, an algorithm based on both accessibility and machining efficiency is proposed for the selection of tool sizes for the rough cutting operation, finish cutting operation and optional semi-rough cutting operation. The final research area focuses on a cutting force analysis for thin material machining with additional layer thickness & tool size interaction. Popular cutting force models are reviewed, and a suitable model for cutting force calculation in this process is evaluated. Then, a cantilever beam model is used to analyze the thin material machining failure problem, and a minimum layer thickness model is presented. Third, a combined layer thickness & tool size model is constructed based on the machining tool deflection under cutting forces. This rapid pattern manufacturing process and related software has been implemented, and experimental data is presented to illustrate the efficacy of this system and its process planning methods

Método de geração de trajetórias trocoidais e espirais combinadas para o fresamento de desbaste de cavidades 2,5D com múltiplas ferramentas

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-graduação em Engenharia Mecânica, Florianópolis, 2013Para o fresamento de cavidades as estratégias de geração de trajetórias mais utilizadas são a paralela ao contorno e a paralela a uma direção, apesar de que as trajetórias geradas com essas estratégias normalmente gerem segmentos com um elevado ângulo de incidência da ferramenta em cantos e em regiões estreitas. A utilização das trajetórias trocoidais tem sido proposta recentemente para evitar ou minimizar esses segmentos que são considerados críticos. Nesta dissertação é apresentado um método para gerar trajetórias trocoidais de ferramentas para cavidades de 2,5D utilizando a transformada do eixo médio, a qual foi implementada na linguagem Octave, e a sua avaliação foi efetuada em provas reais de fresamento. O método proposto, denominado OC2PATH, parte de representações poligonais da cavidade, incluindo ilhas, e o diagrama do eixo médio é calculado como uma série de pontos. Esses pontos são ordenados e agrupados formando linhas. Os pontos são utilizados para gerar uma trajetória trocoidal gerando círculos com centro sobre esses pontos. Com o intuito de evitar que a ferramenta percorra duas vezes a mesma área é utilizada uma simulação baseada em pixel aplicada ao tempo de geração da trajetória. Também e apresentado um método que utiliza as trajetórias geradas e as informações de uma família de ferramentas para obter a sequência de ferramentas que permite minimizar os tempos de fresamento. Para avaliar esta proposta, foi usinada uma cavidade complexa em aço P-20 utilizando tanto com a implementação em Octave do método quanto o programa computacional comercial NX (da Siemens) para gerar as trajetórias. São apresentadas análises detalhadas dos tempos para cada programa, comparando-se as demandas de potência de usinagem ao longo do tempo. O método apresentado gera as trajetórias para a usinagem de cavidades, e de fato há uma limitação da profundidade radial de corte ao longo da trajetória, porém as trajetórias trocoidais normalmente têm um comprimento maior (de 1,5 a 2,5 vezes) do que as trajetórias paralelas ao contorno e aquelas que utilizam estratégias combinadas (como a trajetória gerada pelo software comercial usado na comparação) Abstract: The two most used tool-path generation strategies for milling a pocket are direction-parallel and contour-parallel, although the tool paths obtained with these strategies usually create regions with a high cutter sweep angle in corners and narrow slots which can be problematic to machine. The utilization of a trochoidal tool path has been proposed recently in order to avoid the occurrence of these regions. In this dissertation, a method for generating trochoidal tool paths for 2½D pocket milling using a medial axis transform is proposed, which is implemented in the Octave computer language, and an evaluation of the resulting tool path in real milling tests is presented. In order to achieve this goal, first the pocket and islands are represented as polygons, and the medial axis transform is calculated as a series of points. The points are then sorted and grouped, generating lines by an algorithm. After that, they are used as centers of circles in order to generate the trochoidal tool path. The tool path length is generated using a pixelbased simulation limiting air cuts. A method for minimize the machining time by cutting tool selection and area segmentation using the generated tool-paths is also presented. The presented method was evaluated through machining a pocket in a P20 tool steel, using tool paths generated with the proposed method (referred to as OC2PATH) and the commercial software NX (from Siemens). Detailed analysis for each tool and tool path is carried out, including graphs and images of cutting power requirements. The proposed method generates the toolpaths and NC code, and in fact there is a limitation in the radial depth of cut along the toolpath. However, the obtained toolpaths are lengthier (usually between 1.5 and 2.5 times) than the contour-parallel toolpaths and combined tool-paths (as those obtained with the commercial software used as a means of comparison)

Trajectoire de type spirale adaptative pour l'usinage haute vitesse des cavités

Ce travail de recherche étudie le comportement des nouvelles trajectoires spiralées, adaptées à l'usinage haute vitesse de pochettes, dans le domaine de l'aéronautique. Principalement, il sera question de vérifier comment réagissent les trajectoires spiralées lorsqu'elles s'adaptent au contour géométrique de la cavité. À cet effet, un programme prototype a été développé en Visual Basic afin de générer automatiquement les parcours d'outils adaptés à des pochettes de formes variables. Les paramètres entrant dans la définition de ces trajectoires ont démontré un impact sur les conditions d'usinage. Les résultats obtenus à partir d'essais expérimentaux révèlent le comportement des trajectoires spiralées adaptatives, et illustrent leur potentiel concernant la réduction du temps d'usinage d'environ 15% pour les opérations d'ébauche. La contribution de ces travaux a favorisé l'implantation des tactiques de coupe spiralées et de nouveaux types d'approche hélicoidales utilisables dans les logiciels de CFAO. L'algorithme prend également en considération les murs inclinés, ce qui accroît la quantité de matériel retirée

Proceedings of the 4th International Conference on Innovations in Automation and Mechatronics Engineering (ICIAME2018)

The Mechatronics Department (Accredited by National Board of Accreditation, New Delhi, India) of the G H Patel College of Engineering and Technology, Gujarat, India arranged the 4th International Conference on Innovations in Automation and Mechatronics Engineering 2018, (ICIAME 2018) on 2-3 February 2018. The papers presented during the conference were based on Automation, Optimization, Computer Aided Design and Manufacturing, Nanotechnology, Solar Energy etc and are featured in this book