Tool path generation for milling of free form surfaces with feed rate scheduling

Upotreba slobodnih (skulptorskih) površina u procesu projektovanja proizvoda raste po eksponencijalnom nivou kako iz funkcionalnih tako i iz estetskih razloga. U procesu projektovanja i izrade slobodnih površina neizostavna je upotreba CAD/CAM softvera. Dok su geometrijski aspekti projektovanja relativno dobro pokriveni, problemi i dalje ostaju kada je u pitanju stvarna proizvodnja slobodnih površina. Glavni problemi su povezani sa određivanjem odgovarajuće putanje alata koja bi obezbedila zahtevan kvalitet obrađene površine, minimizaciju ukupnog vremena obrade, kontrolu intenziteta sile rezanja itd. U radu je prikazan algoritam za generisanje putanje alata zasnovan na kriterijumu održanja sile rezanja na konstantnu unapred definisanu vrednost za procese 3-osne obrade loptastim glodalom. U tu svrhu je razvijen model za predikciju sile rezanja koji je uključen u algoritam za generisanje putanje alata i softver koji je kompatibilan sa svim CAD/CAM sistemima. Eksperimentalno je potvđeno da predloženi algoritam ima brojne prednosti u odnosu na strategije obrade komercijalnih CAD/CAM softvera.The use of freeform (sculptured) surfaces in the product design process is accelerating at an exponential rate driven by functional as well as esthetics demands. CAD/CAM software is a must in their design and manufacture. While the geometric aspects of the design are relatively wellcovered, issues still remain when it comes to the actual manufacture of freeform surfaces. The major issues are related to the generation of the proper toolpaths that would assure the required surface quality, the minimization of the total maching time, the control of the magnitude of the cutting forces, etc. This paper presents an algotithmic procedure for tool path generation based on the criterion of maintaing the cutting forces at a constant pre-defined level for 3-axis ball end milling processes. To this end, a model for cutting force prediction is formulated and incorporated into the tolpath generation algorithm and software that is compatible with all CAD/CAM systems. It has been experimentally confirmed that the proposed algorithm offers a number advantages over the machining strategies used in commercial CAD/CAM software

Tool path generation for milling of free form surfaces with feed rate scheduling

Upotreba slobodnih (skulptorskih) površina u procesu projektovanja proizvoda raste po eksponencijalnom nivou kako iz funkcionalnih tako i iz estetskih razloga. U procesu projektovanja i izrade slobodnih površina neizostavna je upotreba CAD/CAM softvera. Dok su geometrijski aspekti projektovanja relativno dobro pokriveni, problemi i dalje ostaju kada je u pitanju stvarna proizvodnja slobodnih površina. Glavni problemi su povezani sa određivanjem odgovarajuće putanje alata koja bi obezbedila zahtevan kvalitet obrađene površine, minimizaciju ukupnog vremena obrade, kontrolu intenziteta sile rezanja itd. U radu je prikazan algoritam za generisanje putanje alata zasnovan na kriterijumu održanja sile rezanja na konstantnu unapred definisanu vrednost za procese 3-osne obrade loptastim glodalom. U tu svrhu je razvijen model za predikciju sile rezanja koji je uključen u algoritam za generisanje putanje alata i softver koji je kompatibilan sa svim CAD/CAM sistemima. Eksperimentalno je potvđeno da predloženi algoritam ima brojne prednosti u odnosu na strategije obrade komercijalnih CAD/CAM softvera.The use of freeform (sculptured) surfaces in the product design process is accelerating at an exponential rate driven by functional as well as esthetics demands. CAD/CAM software is a must in their design and manufacture. While the geometric aspects of the design are relatively wellcovered, issues still remain when it comes to the actual manufacture of freeform surfaces. The major issues are related to the generation of the proper toolpaths that would assure the required surface quality, the minimization of the total maching time, the control of the magnitude of the cutting forces, etc. This paper presents an algotithmic procedure for tool path generation based on the criterion of maintaing the cutting forces at a constant pre-defined level for 3-axis ball end milling processes. To this end, a model for cutting force prediction is formulated and incorporated into the tolpath generation algorithm and software that is compatible with all CAD/CAM systems. It has been experimentally confirmed that the proposed algorithm offers a number advantages over the machining strategies used in commercial CAD/CAM software

Cutting forces prediction: The experimental identification of orthogonal cutting coefficients

U radu je prikazana procedura za određivanje skupa parametara rezanja testovima ortogonalnog struganja koji se koristi za predikciju sila i momenta rezanja. Eksperimenti su izvođeni za kombinaciju materijala obratka (Č4320) i reznog alata (Č9780). Prvi korak u predikciji sila se odnosi na razmatranje relativno jednostavnog procesa ortogonalnog rezanja, da bi se rezultati analize dalje koristili kao osnova za razvoj mnogo opštijeg slučaja kosog rezanja. Sve operacije rezanja dele iste principe mehanike rezanja, ali njihova geometrija i kinematika se razlikuju. Usvojeni linearni model sile uključuje sile usled smicanja i ivične sile. Ukupna sila se određuje na osnovu konkretne geometrije alata sumiranjem po svim aktivnim elementarnim sečivima.In this paper the cutting coefficients were identified applying the orthogonal cutting mechanics, which are used in the cutting forces and torque prediction. The experiments were performed for material combination of the workpiece (16MnCr5) and tool (HSS-E, EMo5Co5). The first step in the forces prediction acting on a cutting tool is to consider a relatively simple orthogonal cutting process in order to continue to use the results of this analysis as a base for the development of a much more general case of oblique cutting. All cutting operations share the same cutting mechanics principles, but their geometry and kinematics are different. The accepted linear forces model includes both components, due to shearing and ploughing. The total forces are calculated based on the tool geometry by summing all active discretized cutting edges

Supervised and Unsupervised Learning of Audio Representations for Music Understanding

In this work, we provide a broad comparative analysis of strategies for pre-training audio understanding models for several tasks in the music domain, including labelling of genre, era, origin, mood, instrumentation, key, pitch, vocal characteristics, tempo and sonority. Specifically, we explore how the domain of pre-training datasets (music or generic audio) and the pre-training methodology (supervised or unsupervised) affects the adequacy of the resulting audio embeddings for downstream tasks. We show that models trained via supervised learning on large-scale expert-annotated music datasets achieve state-of-the-art performance in a wide range of music labelling tasks, each with novel content and vocabularies. This can be done in an efficient manner with models containing less than 100 million parameters that require no fine-tuning or reparameterization for downstream tasks, making this approach practical for industry-scale audio catalogs. Within the class of unsupervised learning strategies, we show that the domain of the training dataset can significantly impact the performance of representations learned by the model. We find that restricting the domain of the pre-training dataset to music allows for training with smaller batch sizes while achieving state-of-the-art in unsupervised learning -- and in some cases, supervised learning -- for music understanding. We also corroborate that, while achieving state-of-the-art performance on many tasks, supervised learning can cause models to specialize to the supervised information provided, somewhat compromising a model's generality

Cartesian compliance identification and analysis of an articulated machining robot

Primena industrijskih robota vertikalne zglobne konfiguracije za višeosnu obradu glodanjem je ograničena na delove od mekših materijala niže klase tačnosti. Osnovni razlog za ovo je nedovoljna krutost serijske strukture robota koja je nekoliko desetina puta manja od krutosti CNC mašina alatki. U radu je predstavljen metod eksperimentalne identifikacije i analize popustljivosti 5-osnog robota za obradu vertikalne zglobne konfiguracije. Za određivanje popustljivosti robota u Dekartovom prostoru korišćen je prošireni konvencionalni pristup koji je baziran na eksperimentalnoj identifikaciji popustljivosti zglobova i Jakobijan matrici. Analitička analiza obuhvata uticaj popustljivosti svakog zgloba ponaosob na popustljivost robota u Dekartovom prostoru. Eksperimentalno određivanje popustljivosti robota u Dekartovom prostoru je izvršeno merenjem apsolutnih pomeraja vrha robota izazvanih statičkim silama u sva tri Dekartova pravca, iz kojih su zatim određene popustljivosti svakog zgloba.The application of industrial robots for machining is currently limited to tasks with low precision demands due to the low stiffness of industrial robots as compared to machine tools. This paper analytically describes an experiment-based compliance identification and analysis method for a 5- axis vertical articulated machining robot. An expansion of the conventional method for the calculation of the robot’s Cartesian space compliance that takes into consideration joint compliances and the Jacobian matrix is used. The analytical analysis considers the effects of the individual joint compliances on the resulting Cartesian space compliance. Experimentally, the Cartesian space compliance is obtained by direct measurement of the absolute displacements induced by static forces along 3-Cartesian directions at the tool tip from which the joint compliances are identified

Melody Transcription From Music Audio: Approaches and Evaluation

Although the process of analyzing an audio recording of a music performance is complex and difficult even for a human listener, there are limited forms of information that may be tractably extracted and yet still enable interesting applications. We discuss melody--roughly, the part a listener might whistle or hum--as one such reduced descriptor of music audio, and consider how to define it, and what use it might be. We go on to describe the results of full-scale evaluations of melody transcription systems conducted in 2004 and 2005, including an overview of the systems submitted, details of how the evaluations were conducted, and a discussion of the results. For our definition of melody, current systems can achieve around 70% correct transcription at the frame level, including distinguishing between the presence or absence of the melody. Melodies transcribed at this level are readily recognizable, and show promise for practical applications

Complex Langevin and other approaches to the sign problem in quantum many-body physics

We review the theory and applications of complex stochastic quantization to the quantum many-body problem. Along the way, we present a brief overview of a number of ideas that either ameliorate or in some cases altogether solve the sign problem, including the classic reweighting method, alternative Hubbard–Stratonovich transformations, dual variables (for bosons and fermions), Majorana fermions, density-of-states methods, imaginary asymmetry approaches, and Lefschetz thimbles. We discuss some aspects of the mathematical underpinnings of conventional stochastic quantization, provide a few pedagogical examples, and summarize open challenges and practical solutions for the complex case. Finally, we review the recent applications of complex Langevin to quantum field theory in relativistic and nonrelativistic quantum matter, with an emphasis on the nonrelativistic case