677 research outputs found
Parametric toolpath design in metal spinning
Toolpaths in metal spinning are still designed by human operators, largely by intuition: a scientific basis remains elusive. In this paper, a parameterised toolpath is proposed based on a quadratic Bezier curve. Experiments are performed varying each of four design parameters in turn, to investigate how tool force, part geometry and various failure modes evolve with key features of the tool path. Analysis of these experimental results reveals some new features of process mechanics and leads to a proposal for a set of rules that may become useful for automatic toolpath generation.The first author is funded by the EPSRC Doctoral Training Account and Primetals Technologies Limited (contract number RG64379)– a joint venture company of Siemens, Mitsubishi Heavy Industries and Partners; the second author by EPSRC Grant EP/K018108/1.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.cirp.2015.04.07
Automatic design of sheet metal forming processes by “un-forming”
Most sheet metal components are made by deep drawing, which requires expensive tooling. Although many new flexible forming processes have been invented, they have largely not had industrial application, so it would be valuable if intelligent means to design new processes existed. This has not previously been attempted, although there has been work to classify both products and processes and to define optimal forming processes. A body of work in garment production examines the optimal flattening of garments, starting from their final form on a human body, to deduce the best cutting pattern from flat fabric. This paper develops a related approach for the first time, “un-forming” sheet metal from its finished geometry to a flat blank without prior specification of a process. An algorithm is developed that allows specification of process constraints and great freedom in implementing un-forming strategies, leading to a prediction of the strain history of the un-forming process. Reversing the direction of this history, allows prediction of the stresses in the workpiece required to form the target part, by use of an appropriate material model. The external forces (boundary conditions) required to maintain equilibrium with this stress state can then be calculated, allowing an iterative refinement of the constraints on un-forming until a physically achievable process has been designed. The approach is validated against a known process, and used to demonstrate how several previously untried forming strategies could lead to specification of new process designs. In future work, the method could be extended to allow an iterative specification of tooling to create the required boundary conditions, and hence to complete automatic process designs.This research was supported by the EPSRC grant EP/K018108/1.This is the final version of the article. It first appeared from Elsevier via https://doi.org/10.1016/j.ijmecsci.2016.04.00
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Potential for energy savings by heat recovery in an integrated steel supply chain
Heat recovery plays an important role in energy saving in the supply chain of steel products. Almost all high temperature outputs in the steel industry have their thermal energy exchanged to preheat inputs to the process. Despite the widespread development of heat recovery technologies within process stages (process heat recovery), larger savings may be obtained by using a wider integrated network of heat exchange across various processes along the supply chain (integrated heat recovery). Previous pinch analyses have been applied to optimise integrated heat recovery systems in steel plants, although a comparison between standard process heat recovery and integrated heat recovery has not yet been explored. In this paper, the potential for additional energy savings achieved by using integrated heat recovery is estimated for a typical integrated steel plant, using pinch analysis. Overall, process heat recovery saves approximately 1.8 GJ per tonne of hot rolled steel (GJ/t hrs), integrated heat recovery with conventional heat exchange could save 2.5 GJ/t hrs, and an alternative heat exchange that also recovers energy from hot steel could save 3.0 GJ/t hrs. In developing these networks, general heat recovery strategies are identified that may be applied more widely to all primary steel production to enhance heat recovery. Limited additional savings may be obtained from the integration of the steel supply chain with other industries.Dr. McBrien’s work on this paper was funded by EPSRC grant EP/G007217/1, and Dr. Serrenho and Professor Allwood were funded by EPSRC grant EP/N02351X/1.This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.applthermaleng.2016.04.09
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Energy and material efficiency of steel powder metallurgy
Concern about global warming motivates the reduction of greenhouse gas emissions from manufacturing but as yet the environmental impact of the whole powder metallurgy production chain has not been assessed. This paper therefore traces the flow of energy and material through the major powder metallurgy processes from liquid steel to final products and assesses the efficiency of both energy and material use. The results show that there is significant opportunity for reducing energy and material requirements in delivering products. Specific opportunities such as avoiding lasers in additive manufacturing or minimizing heat losses in powder sintering are proposed and evaluated
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Haptic metal spinning
Sheet metal spinning is an incremental forming technique practiced for a long time only by experienced, skilled craftsmen. Over the last sixty years, attempts have been made to automate the process, but today the industrial practice still relies heavily on the skill of experienced operators. Complete analytical solutions to predict workpiece failure based on the path of the tool are not available, and finite element simulations of the process are too time-intensive to be of practical use for online toolpath correction. Therefore, today the design of toolpaths to avoid failure in spinning remains an art acquired by practice. In this paper, we approach the issue by designing an enhanced teach-in/playback system. We connect a haptic device to a CNC spinning machine; this device allows a human operator to control the working roller manually while feeling the force applied to the workpiece. Position, force and workpiece shape sensors allow collecting information on the toolpath followed by the operator and on its influence over the mechanics of the process. The opportunities offered by this system to derive rules for toolpath design are explored in two case studies on force control and wrinkling recovery, with new insights on the relationship between toolpaths and failure. A research agenda is outlined to exploit the full potential of haptic metal spinning
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Implementing material efficiency in practice: A case study to improve the material utilisation of automotive sheet metal components
© 2019 There is an opportunity to reduce the amount of sheet metal currently used to manufacture automotive components, despite the available cost and CO2 savings, the automotive industry has not realised the full potential of these saving opportunities. To understand why, a practical case study was set up with an automotive manufacturer. A cross-functional team was established with the scope to make changes to five components using a structured design process to improve material efficiency. The trial identified realistic opportunities to improve material utilisation by 20%pts, and save £9million and 5 kilotonnes of CO2 annually. The greatest saving opportunities were found early in the product development cycle, before the production method is determined by component geometry. Of these, 3%pts were actually implemented on the production vehicle, saving £1.8million and 1.5 kilotonnes of CO2 annually. The case study identified significant barriers to implementing material efficiency strategies in an industrial setting. To overcome these barriers material utilisation should be considered early in the product design process and high in the vehicle platform hierarchy. As a result of this investigation, new business processes are being generated to support design for material utilisation at the automotive manufacturer. This case study approach should be considered to increase implementation for other aspects of material demand reduction.EP/N02351X/
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Scrap, carbon and cost savings from the adoption of flexible nested blanking
Steel accounts for 6% of anthropogenic CO2 emissions, most of which arises during steelmaking rather than downstream manufacturing. While improving efficiency in steelmaking has received a great deal of attention, improving material yield downstream can have a substantial impact and has received comparatively less attention. In this paper, we explore the conditions required for manufacturers to switch to a more materially efficient process, reducing demand for steel and thus reducing emissions without reducing the supply of goods to consumers. Furthermore, we present an alternative processing route where parts can be cut in flexible arrangements to take advantage of optimal nesting across multiple part geometries. For the first time, we determine the potential savings that flexible nested blanking of parts could achieve by calculating the potential for grouping orders with tolerably-similar thickness, strengths, ductility and corrosion-resistance. We found that 1,080 kt of CO2 and 710 kt of steel worth € 430M could be saved each year if this scheme was adopted across all European flat steel mills serving the automotive sector
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A marginal abatement cost curve for material efficiency accounting for uncertainty
Comparing costs of measures to mitigate greenhouse gas is challenging as there are many competing notions of costs, and uncertainties associated with cost estimates. In addition, there are many different types of mitigation measures, from supply-side investment solutions to demand-side efficiency improvements, which may interact, risking double-counting of abatement potentials. This paper presents a novel, transparent methodology for building a marginal abatement cost curve that allows abatement costs and potentials to be compared. This curve improves over existing methods as it allows for abatement measures to be pursued in parallel, takes into account the interplay between abatement measures and captures data on cost uncertainty. The method is applied to build the first bottom-up marginal abatement cost curve for greater material efficiency steel use in the UK. This curve is demonstrated via four material efficiency measures which do not require large changes in final uses of products: reusing steel beams in construction, specifying optimal lightweight beams in construction, choosing smaller cars and specifying high strength steel car bodies. The results show that these strategies could reduce UK steel demand and associated global emissions by approximately 12%. 17% of this potential would be viable at the Department for Business, Energy \& Industrial Strategy (BEIS) 2030 carbon price for policy appraisal (79ÂŁ/tCO2) taking into account emissions savings associated with steel demand only. Once use-phase emissions savings are taken into account this share increases to 60%. These results can be traced directly back to underlying assumptions regarding costs and emissions allocations
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Real and perceived barriers to steel reuse across the UK construction value chain
© 2017 Elsevier B.V. Although steel reuse has been identified as an effective method to reduce the carbon and energy impact of construction, its occurrence is shrinking in the UK. This can be partly explained by the many barriers which have been identified in the literature, but a detailed analysis of how these barriers affect different parts of the supply chain is still lacking. We show that there is a contrast between perceived higher costs and time required to employ reused steel and the assessments of realised projects. Using a novel ranking method inspired from the field of information retrieval (tf-idf), we have analysed interviews of actors across the supply chain to determine the acuteness of the perception of each barrier. We show that demolition contractors, stockists, and fabricators face specific barriers which each need to be addressed at their level. This is in contrast with more generic barriers present throughout the value chain which we show are probably more perception than reality. Finally, we suggest how supply chain integration could facilitate reuse and make it economically viable at scale
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Ring rolling with variable wall thickness
Ring rolling processes today produce axisymmetric rings, wasting material, energy and labour if non-axisymmetric components such as eccentric bearing races and bossed pipe fittings are required. A new process is proposed to roll rings with variable wall thickness. In this work, roll gaps and speeds are controlled online in physical experiments to achieve a defined variable wall thickness, enabled by photogrammetry to capture the ring’s shape and position. The trials revealed two new process limits for which new analytical explanations have been developed: a maximum rate of change of thickness around the circumference and a loss of circularity.The first author is supported by an EPSRC I-Case Studentship (12220703), with Primetals Technologies Ltd. Dr. Arthington and Prof. Allwood were supported by EPSRC grant EP/K018108/1.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.cirp.2016.04.00
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