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

Finding the Maximum Subset with Bounded Convex Curvature

We describe an algorithm for solving an important geometric problem arising in computer-aided manufacturing. When machining a pocket in a solid piece of material such as steel using a rough tool in a milling machine, sharp convex corners of the pocket cannot be done properly, but have to be left for finer tools that are more expensive to use. We want to determine a tool path that maximizes the use of the rough tool. Mathematically, this boils down to the following problem. Given a simply-connected set of points P in the plane such that the boundary of P is a curvilinear polygon consisting of n line segments and circular arcs of arbitrary radii, compute the maximum subset Q of P consisting of simply-connected sets where the boundary of each set is a curve with bounded convex curvature. A closed curve has bounded convex curvature if, when traversed in counterclockwise direction, it turns to the left with curvature at most 1. There is no bound on the curvature where it turns to the right. The difference in the requirement to left- and right-curvature is a natural consequence of different conditions when machining convex and concave areas of the pocket. We devise an algorithm to compute the unique maximum such set Q. The algorithm runs in O(n log n) time and uses O(n) space. For the correctness of our algorithm, we prove a new generalization of the Pestov-Ionin Theorem. This is needed to show that the output Q of our algorithm is indeed maximum in the sense that if Q\u27 is any subset of P with a boundary of bounded convex curvature, then Q\u27 is a subset of Q

Pengoptimuman jarak laluan mata alat menggunakan algoritma koloni semut untuk proses pengisaran poket

Pada masa kini, proses pemesinan kisar poket menggunakan mesin Kawalan Komputer Berangka (CNC) banyak digunakan dalam pemotongan logam. Terdapat dua langkah pemesinan di dalam proses pengisaran poket iaitu pemesinan kasar dan kemasan. Pemesinan kasar mengambil masa lebih 50 % dari keseluruhan masa pemotongan kerana sejumlah besar bahan kerja dipotong sehingga hampir menyerupai bentuk yang dikehendaki. Oleh itu, adalah penting untuk mempercepatkan masa pemesinan kasar. Pemesinan kontur selari dapat menghasilkan masa pemesinan kasar yang lebih rendah berbanding zigzag dan satu hala. Walau bagaimanapun, terdapat satu masalah di dalam pemesinan kontur iaitu berlaku bahagian lebihan tidak terpotong pada bahagian bucu dan tengah. Kawasan lebihan tidak terpotong ini berlaku kerana penetapan nilai selang antara kontur (ω) yang melebihi jejari mata alat (r). Salah satu cara untuk memotong kawasan lebihan ini adalah dengan menambahkan satu laluan mata alat tambahan (Llt) ke atas laluan asal, iaitu laluan kontur selari. Kaedah penghasilan laluan mata alat tambahan yang diperkenalkan kajian terdahulu berjaya untuk memotong keseluruhan kawasan lebihan ini. Namun, laluan yang dihasilkan oleh kajian sebelum ini tidak mempertimbangkan pergerakan mata alat yang menyumbang kepada peningkatan jarak laluan mata alat dan masa pemesinan kasar. Oleh itu, objektif kajian ini adalah untuk mengoptimumkan laluan mata alat bagi menentukan jarak laluan mata alat yang minimum di dalam proses pengisaran poket berdasarkan pemesinan kontur selari menggunakan kaedah cerdik buatan (AI). Algoritma kontur selari (Algo-KS) dibina bagi menghasilkan laluan mata alat secara kontur selari dan untuk menentukan kawasan lebihan tidak dipotong. Algoritma Koloni Semut berdasarkan aturan peralihan baru (ACO-PB) telah diperkenalkan untuk menentukan pergerakan mata alat bagi memotong kawasan lebihan berdasarkan aturan peralihan dan jarak minimum di antara dua kawasan lebihan. ACO-PB telah diuji keberkesanannya ke atas dua model iaitu model pertama dan model kedua bagi menentukan masa pemesinan kasar (Tmk). Seterusnya, Tmk yang diperoleh ini disahkan keputusannya menggunakan proses uji kaji pemesinan. Uji kaji dilakukan dengan mempraktikkan laluan mata alat yang dihasilkan berdasarkan ACOPB ke dalam mesin kisar CNC tiga-paksi. Bahan kerja Aluminium 6061 dan mata alat jenis keluli laju tinggi (HSS) hujung rata yang bersalut Titanium Nitrida digunakan sepanjang proses pemesinan kasar. Hasil kajian mendapati terdapat perbezaan Tmk sebanyak 7.2 % di antara Tmk ACO-PB dan uji kaji. Keputusan ini telah mengesahkan bahawa ACO-PB yang dibangunkan berupaya untuk meminimumkan jarak laluan mata alat dan dapat dipraktikkan di dalam proses pemesinan sebenar. Llt dan Tmk yang dihasilkan ACO-PB juga telah dibandingkan dengan Llt dan Tmk yang diperoleh berdasarkan kajian terdahulu. Keputusan simulasi menunjukkan ACO-PB telah menghasilkan laluan mata alat yang lebih pendek sebanyak 23.7 % dan pengurangan Tmk sebanyak 4.95 % berbanding kajian terdahulu. Kajian ini juga telah membandingkan Tmk yang diperoleh menggunakan ACO-PB dan Mastercam dan mendapati ACO-PB berjaya mengurangkan Tmk sebanyak 46.5 %. Sebagai kesimpulan, kajian ini telah berjaya membangunkan algoritma ACO-PB yang berupaya untuk meminimumkan jarak laluan mata alat di dalam pemesinan kontur selari dan mengurangkan masa pemotongan bagi proses pemesinan kasar

A knowledge-based approach for the extraction of machining features from solid models

Computer understanding of machining features such as holes and pockets is essential for bridging the communication gap between Computer Aided Design and Computer Aided Manufacture. This thesis describes a prototype machining feature extraction system that is implemented by integrating the VAX-OPS5 rule-based artificial intelligence environment with the PADL-2 solid modeller. Specification of original stock and finished part geometry within the solid modeller is followed by determination of the nominal surface boundary of the corresponding cavity volume model by means of Boolean subtraction and boundary evaluation. The boundary model of the cavity volume is managed by using winged-edge and frame-based data structures. Machining features are extracted using two methods : (1) automatic feature recognition, and (2) machine learning of features for subsequent recognition. [Continues.

Automated Rapid Manufacturing Feedback for Design Considering Advanced Joining Processes

As manufacturing advancements continue to develop, designers must be able to consider these technologies during the design process. Unfortunately, many of these new technologies, such as additive and advanced joining, have many nuances that require expert knowledge to effectively apply. Additionally, new design techniques, such as topology optimization, allow users to create geometries that are traditionally not manufacturable. The approach presented in this thesis bridges the gap of expert knowledge between component design and a new advanced manufacturing technique, specifically linear friction welding to form monolithic components from multiple individual raw material blanks. The first step of the approach analyzes a part geometry to determine the unmachinable regions. This is done by converting an input tessellated shape into a voxelized solid and analyzing different axial cutting tool approach directions that could occur during a milling operation. Areas that the tool cannot access remain, which indicate regions of unmachinable solids. These solids are then used to determine areas where pre-joining machining could occur, taking advantage of the capabilities of linear friction welding. This is done using an existing part decomposition method while using a two-objective search optimizing total cost of manufacturing and total unmachinable volume. Decomposition configurations yield new set-ups of individual sub-volumes to determine unmachinable volume remaining and manufacturing plans are created by rebuilding the configurations to determine total cost of manufacturing. Results of the work demonstrate the ability to determine manufacturing plans and the potential tradeoffs of complex geometries, processing, and costs

City Building on the Eastern Frontier

America's westward expansion involved more than pushing the frontier across the Mississippi toward the Pacific; it also consisted of urbanizing undeveloped regions of the colonial states. In 1810, New York's future governor DeWitt Clinton marveled that the "rage for erecting villages is a perfect mania." The development of Rochester and Syracuse illuminates the national experience of internal economic and cultural colonization during the first half of the nineteenth century. Architectural historian Diane Shaw examines the ways in which these new cities were shaped by a variety of constituents—founders, merchants, politicians, and settlers—as opportunities to extend the commercial and social benefits of the market economy and a merchant culture to America's interior. At the same time, she analyzes how these priorities resulted in a new approach to urban planning.According to Shaw, city founders and residents deliberately arranged urban space into three segmented districts—commercial, industrial, and civic—to promote a self-fulfilling vision of a profitable and urbane city. Shaw uncovers a distinctly new model of urbanization that challenges previous paradigms of the physical and social construction of nineteenth-century cities. Within two generations, the new cities of Rochester and Syracuse were sorted at multiple scales, including not only the functional definition of districts, but also the refinement of building types and styles, the stratification of building interiors by floor, and even the coding of public space by class, gender, and race. Shaw's groundbreaking model of early nineteenth-century urban design and spatial culture is a major contribution to the interdisciplinary study of the American city

Partial Discharge Mitigation in Power Modules using an Automation-Driven Design Rule Development Method

Power modules used for the conversion and conditioning of electrical power for applications like electric vehicles, more-electric aircraft, the power grid, etc., are largely designed manually by engineers. Design automation of power modules is starting to gain recognition as a timely and necessary alternative to intuitive manual design and fabrication. With increasing need for wide bandgap materials that can operate at higher voltages, and the need to make modules more compact, hazards like electrical breakdown are more likely. Partial discharge (PD) is a silent and invisible precursor to electrical breakdown. It is compounded with compaction, creating a potential for electrical breakdown and catastrophic failure of the module package. Instead of being the limiting factor, or even a hazard, power module packages need to keep pace with the advancements being made in wide bandgap technology. While the automation of power module design is still new, and research and standards on PD in power modules are limited, this dissertation is a significant step in designing for high voltage operation while assessing tradeoffs against module compaction in an electronic design automation tool. This dissertation describes a method of systematically accounting for partial discharge in power modules using a unique approach where improvements to a module layout are determined in terms of design rules. Trace gaps, in this method, are designed to be functions of operating voltage, substrate and encapsulant material choice, and layer thicknesses of the substrate. These design rules are based on simulations that are validated by physical PD experiments. Furthermore, filleting is performed on the final layouts to further reduce PD by reducing the E-field concentrations by a third. This methodology has been implemented in PowerSynth, an in-house hardware-validated electronic design automation tool that performs electro-thermal and mechanical layout optimization. Before the implementation of this work, layouts were agnostic to PD. From the contribution of this work, the layouts now generated by the tool are PD-mitigated, with a maximum operating voltage for each layer stack. Below the rated voltage, the user can choose multiple voltage-trace gap trade off options for the layout. Demonstrating this implementation in this work shows that the user can achieve either a 24% improvement in voltage level, or a 20% improvement in area reduction, or a trade-off combination of the two. As layouts increase in complexity, these improvements will likely grow. The implementation of this work allows room for growth by allowing customized PD data libraries from various manufacturing lines to inform design rules much like a process design kit in the field of integrated circuit design. The designer using PowerSynth can: 1.) Use default libraries for design rules, or 2.) Perform their own simulations to augment the existing PD data library according to the method presented here, or 3.) Fabricate their own test structures and design corresponding simulations to develop their own complete PD data library and import it to PowerSynth. The manufacturable modules resulting from this tool are thus designed to be practical and reliable for high voltage operation

Goodsprings: A historical archaeological review of the Yellow Pine Mining District

This thesis consists of a comparative analysis of the written historical record and surface archaeological features relevant to three mines of the Yellow Pine Mining District. The intent is to discover if field observations do indeed confirm historical documentation. Using archival sources combined with an intuitive non-random sampling method, various feature systems associated with mining were recorded in order to discern chronological and historical accuracy. Research questions concerning length of mining activities, number of men employed at the mines, feature systems utilized, and the current condition of each site were addressed to confirm documentation and the historical significance of these sites; The results of the field study has confirmed that the mines were active during the periods documented through various archival sources. Little physical evidence remains of the thematic feature systems associated with the once busy Yellow Pine Mining District. The most productive economic mining period of southern Nevada does not possess the physical criteria to be considered historically significant in regards to preservation. Nevada\u27s cultural resources associated with mining have almost totally vanished because of the ephemeral nature of mining operations