Zalieskis R. Integration of designing sheet steel products and their manufacturing processes : Master thesis of mechanical engineer / research advisor associate prof. habil. dr. A.Bargelis, Šiauliai university, department of technologic, department of mechanical engineering. – Šiauliai, 2006. – 38 p. Sheet steel is used wide in a modern manufacturing. In this paper I researched the work one of the factories manufacturing sheet steel products. It was analysed all manufacturing operations and equipment needed to make a box. I researched the designing of sheet steel products and their manufacturing processes on purpose to improve designing process. The designer can use results obtained from this paper and estimate outlay of newly designed product in early design stage. Scientific novelty of the work In this paper method of mathemamatical statistics was used and firstly created classificator of sheet steel products on purpose to estimate outlay of manufacturing.

Thesis (PhD) - Swinburne University of Technology, Faculty of Engineering and Industrial Sciences, 2005. / Thesis submitted to Swinburne University of Technology, for the degree of Doctor of Philosophy, 2005. Typescript. Bibliography p. 144-149.

The nature and scope of this thesis can be divided into four categories: • FORMING PARAMETERS • Identification of various laser forming parameters in order to produce specimens of similar dimension (radius of curvature). • TEMPERATURE AND MICROSTRUCTURE • To study the effect of maximum temperature reached during the forming operation on the microstructure of the various specimens. • FATIGUE LIFE • Compare the fatigue life of the specimens produced by various laser parameters to that of the original material, and also the fatigue life of mechanical formed specimens. • RESIDUAL STRESS PROFILE Determine if the laser forming process induces detrimental residual stress magnitudes in the specimens. The main objective of this thesis was to gain an understanding of the way in which laser forming affects the fatigue performance and residual stress magnitude / distribution of dual phase steel. Although lasers have been used successfully in various manufacturing processes (welding, cutting, marking, etc.), little information is available on the influence of laser forming on many automotive alloys such as dual phase steel. The first part of the work involved a literature review of the process and factors affecting the laser forming process. It became clear from the literature overview that laser forming of sheet material thicker than 1mm is complex in nature. The variables that can influence the process are complicated and their interaction with each other is not easily controlled. The main parameters that were thus controlled in this study are as follows: • Laser power (P) • Laser head travel speed (v) • Laser beam size (mm) The chapters that follow the literature review, deals with the laser forming process of dual phase steel and the production of fatigue specimens using various laser parameters. It was found that the following laser parameters resulted in specimens with approximately the same radius of curvature: Laser power KW Beam diameter mm Interval spacing % Overlap Scanning velocity m/min Line Energy J/m 5 20 10 50 2,5 2000 3,1 14 10,5 25 2 1550 1,5 7,5 7,5 0 1,2 1250 From the results obtained from fatigue testing specimens produced with the above settings, it is clear that the laser forming process has the potential to be employed as a production stage in the manufacture of wheel centre discs while maintaining adequate fatigue strength. Large beam diameters which cause heat penetration through the thickness of the specimen and hence microstructure breakdown should be avoided, since it was shown that these specimens exhibited impaired mechanical properties than those produced with a smaller laser beam diameter. The microstructural changes observed during the forming process needs to be considered since the mechanical properties of the material changes with a change in microstructure. A dramatic change in microstructure was observed; therefore it is of crucial importance that microstructural evaluation plays an important part in deciding optimum laser parameters for the forming process of ferrous alloys. During residual stress analysis, trends were observed between measurements taken at the same location of the samples; regardless whether measurements were taken on the laser irradiated side or the reverse side of the specimen. The only difference was the magnitude of the relieved residual stress. In most cases the obtained relieved residual stress was much smaller in magnitude than that of the original plate (in the bulk of the material). The surface indicated a slight tensile residual stress for most samples evaluated. A good correlation in distribution profile was obtained between microhardness and relieved residual stress distribution at the ‘middle of sample’ location. This indicates that an increase in hardness indicates an increase in residual stress magnitude for the laser formed specimens. In conclusion, this research has proved that it is possible to deform metal plate of a 3,5mm thickness with a CO2 laser system. The research also established the effect of process parameters on the final product’s shape/bend angle and characterised the effect of the laser forming process on the material’s mechanical properties and structural integrity.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 2016 / This dissertation presents a parametric study conducted on the dimensions of an inverted box rib (IBR) sheet. The objectives of the study were (i) to obtain the optimum dimensions that would be used to simulate new IBR profiles made from standard sheet input coils whilst meeting the stiffness criterion; and (ii) to perform a cost analysis to determine the most economic simulated profile. The dimensions which were varied in the parametric study were rib-height, rib-width, sheet thickness and the number of pans per 686 mm cover width of a single IBR 686 sheet. Numerical experiments were conducted using the Finite Elements Method and Abaqus/CAE software. The results were compared to the predictions obtained from Euler-Bernoulli beam theory. The outputs from the experiments were the sheet deflection from which stiffness was determined, and eigenvalues from which the profiles’ stability and buckling modes were calculated. This study found that sheet stiffness increased as the rib-height, sheet thickness and number of pans per 686 mm cover width increased. In contrast, the rib-width had little effect on the sheet stiffness. Hence, it was concluded that, for any IBR sheet profile, the rib-width should be kept at approximately 23 mm to avoid using more material in the sheet. The optimum dimensions found were rib-height of 34 mm, rib-width of 23 mm and four pans per 686 mm cover width. The commercially available IBR 686 sheet is made up of four pans and has a rib-height and a rib-width of 37 and 33 mm, respectively. It is manufactured from an input sheet coil of 925 mm. Reducing the rib-height from 37 mm to 34 mm and the rib-width from 33 mm to 23 mm resulted in increasing the cover width by 8 %. The optimum dimensions were further used to simulate profiles made from the 925, 940, 1000, 1175, 1219, 1225, 1250 and 1320 mm standard sheet coils in order to find the most economic IBR profiles that met the stiffness criterion. The 1250 mm coil yielded the most economical IBR profile, which has six 97 mm wide pans, and a 996 mm cover width. This profile resulted in a 10 % cost saving compared with the next closest profile. / MT2017

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

The current work used discrete event simulation techniques to model the economics of quality within an actual automotive stamping plant. Automotive stamping is a complex, capital intensive process requiring part-specific tooling and specialised machinery. Quality control and quality improvement is difficult in the stamping environment due to the general lack of process understanding and the large number to interacting variables. These factors have prevented the widespread use of statistical process control. In this work, a model of the quality control techniques used at the Ford Geelong Stamping plant is developed and indirectly validated against results from production. To date, most discrete event models are of systems where the quality control process is clearly defined by the rules of statistical process control. However, the quality control technique used within the stamping plant is for the operator to perform a 100% visual inspection while unloading the finished panels. In the developed model, control is enacted after a cumulative count of defective items is observed, thereby approximating the operator who allows a number of defective panels to accumulate before resetting the line. Analysis of this model found that the cost sensitivity to inspection error is dependent upon the level of control and that the level of control determines line utilisation. Additional analysis of this model demonstrated that additional inspection processes would lead to more stable cost structures but these structures many not necessarily be lower cost. The model was subsequently applied to investigate the economics of quality improvement. The quality problem of panel blemishes, induced by slivers (small metal fragments), was chosen as a case stuffy. Errors of 20-30% were observed during direct validation of the cost model and it was concluded that the use of discrete event simulation models for applications requiring high accuracy would not be possible unless the production system was of low complexity. However, the model could be used to evaluate the sensitivity of input factors and investigating the effects of a number of potential improvement opportunities. Therefore, the research concluded that it is possible to use discrete event simulation to determine the quality economics of an actual stamping plant. However, limitations imposed by inability of the model to consider a number of external factors, such as continuous improvement, operator working conditions or wear and the lack of reliable quality data, result in low cost accuracy. Despite this, it still can be demonstrated that discrete event simulation has significant benefits over the alternate modelling methods.

Na maioria das construções utilizam-se estruturas de madeira para coberturas e muitas são executadas no sistema convencional, empregando treliças. Com o avanço da arquitetura, no que diz respeito a empregabilidade da madeira, outras formas vêm sendo utilizadas, tornando o ambiente mais livre e harmônico, e para isso, a necessidade de vigas maiores, para vencer maiores vãos. Desta forma, os materiais dos elementos estruturais têm importante papel, a fim de demandar continuidade das peças, dentro dos padrões de segurança. As Normas Brasileiras apresentam formas de ligações onde, o emprego da madeira e o aço, garantem a estabilidade para ambos os materiais, visto a utilização de parafusos e pinos como elemento de ligação, empregados nas construções. Neste trabalho, a proposta é avaliar os conjuntos dos materiais de ligações aparafusadas entre madeira/madeira e compará-la com a ligações madeira/chapa de aço/madeira; a chapa dobrada a frio e prensada entre as peças não está aparente. Portanto, a ligação ficará a cargo dos parafusos, mas, com a chapa a resistência será maior suportando aos esforços cortantes causados pela flexão dos parafusos e inserida diretamente na madeira, que tem grande importância quanto à direção das fibras e do esforço aplicado. / In most constructions are used wooden structures for roofs and many are executed in the conventional system using trusses. With the advancement of architecture, with regard the employability of timber, other ways have been used making the free and harmonious environment, and for this, the need for larger beams, to win larger spans. Therefore, the materials of the structural elements have an important role in order to demand continuity of parts with in the safety standards. Brazilian Standards of forms of links where the use of timber and steel, ensure stability for both materials, as the use of bolts and pins as liaison, used in buildings. In this paper, the proposal is to assess the joint of bolted connections materials between timber / timber and compare it with the connections timber / steel plate / timber; the folded plate and cold pressed between the parts is not apparent. Therefore, the connection will fall on the bolts, but with the plate resistance will be higher by supporting the shearing caused by the bending of the bolts and inserted directly on timber, which is very important as to the direction of the fibers and of the applied load.

<p> This thesis investigates the characteristics of noise generation in the gas wiping process, including the effects of the various parameters manipulated in the process and countermeasures used to reduce noise levels. The process of gas wiping is used in many industrial applications such as drying of pulp and paper, photograph production and some high performance cooling applications. One of the most important industrial applications of gas wiping is the production of hot-dipped galvanized sheet steel. Gas wiping is a very efficient and reliable process to control coating thickness and uniformity of galvanized steel products, and can be used for very high line speeds and production rates. Changing the various process parameters such as the jet to strip distance (z), the jet slot width (h), plenum pressure (P) and jet inclination angle (α) allows manufacturers to control the coating thickness and quality of the finished product.</p> <p> The gas wiping process is also responsible for the generation of very high levels of noise, which can be a factor in limiting the overall production rates and indirectly increase production costs for manufacturers. To maintain a constant coating thickness as the line speed and production rate is increased, the plenum pressure supplied to the jets and thus the incident jet velocity must be increased, or the jet-to-strip distance must be decreased. Noise production in the gas wiping process is acknowledged to be proportional to the incident jet velocity and inversely proportional to the jet-to-strip distance. Thus, for a given coating thickness, as the production rates increase, the noise generated by the process must also increase. Ergonomic restrictions in the workplace, which limit the exposure to high sound pressure levels and audible acoustic tones, may indirectly limit the maximum line speed for a steel sheet with a given coating thickness. This limitation is particularly relevant to the production of high quality automotive sheet steels, which often have very thin coating thicknesses and have higher than normal coating uniformity tolerances, which necessitate the use of high plenum pressures and small jet-to-strip distances.</p> <p> At present, the state of knowledge for noise generation in the gas wiping process is very limited. Only two previous investigations have been devoted to this problem, and the experiments for these studies have only modeled specific individual cases, with no attempt at a comprehensive modeling of noise in this process. For the current study, measurements have been performed in both an actual manufacturing environment and on a scaled galvanizing simulator in a laboratory environment. A comprehensive set of experiments over a wide range of gas wiping parameters was performed in order to provide a broad overview of noise generation in the gas wiping process and allow for process optimization to reduce noise and allow higher production rates and efficiency. The creation of noise maps, modeling the overall sound pressure level and tone intensity for gas wiping as function of the various operating parameters of the process, as well as a set of equations and models to determine the frequency of discrete acoustic tones are presented. A full analysis of the frequency response, as well as the acoustic modes generated in various jet impingement regions has also been provided.</p> / Thesis / Master of Applied Science (MASc)

The objective of this research was to establish a relationship between arc spot weld shear strength and the arc time used to form the weld. Lap shear tests were performed on both 3/4 in. and 5/8 in. nominal diameter welds. Each weld was formed in one-, two-, or four-layers of sheet steel ranging from 22 gauge (0.028 in.) to 16 gauge (.057 in.). Three distinct time series were tested for each unique weld size, thickness of sheet steel and layer configuration. The first of these series were the full-time welds. The two remaining series, 2/3-time and 1/3-time welds, had arc times equal to 2/3 and 1/3 of the average full-time weld arc time, respectively. Both weld shear strength tests and weld sectioning were performed for each series of weld. Strength tests were performed on a minimum of three specimens from every weld series. If the strength of any specimen deviated by over ten percent from the mean strength, an additional specimen was tested, helping to better understand the true behavior of the weld. Comparisons were made between the strengths of full-time, 2/3-time and 1/3-time welds. Comparisons were also made between the observed strength of each weld and the strengths calculated using the 2001 AISI Specification. Each sectioning test involved measuring and documenting the visual diameter, average diameter and effective diameter of the weld. Weld penetrations were also documented as sufficient or insufficient and any porosity was noted. A single sectioning test was performed for each full-time series, while three were performed for every 2/3-time and 1/3-time series. The data taken from the strength tests and the sectioning samples proved that welds formed using reduced arc times were considerably smaller and weaker than full-time welds. The tests also proved that proper penetration is not dependent on the arc time, but is instead a function of the welding current and sheet steel thickness. / Master of Science

Dans l’industrie automobile, les exigences en matière d’émissions polluantes conduisent à alléger les véhicules, notamment en réduisant l’épaisseur des tôles. Ce travail en partenariat avec ArcelorMittal porte sur le soudage par résistance par point de tôles fines d’acier. L’objectif est d’identifier les phénomènes qui induisent les difficultés de soudabilité opératoire rencontrées avec une combinaison dissymétrique de trois tôles revêtues, incluant une tôle très mince galvanisée de moins de 0,6 mm, une tôle de DP600 et une tôle en Usibor® emboutie à chaud. Des observations par caméra infrarouge montrent que les échauffements initiaux se produisent principalement au niveau des interfaces avec la tôle d’Usibor®1500, et que le noyau se forme du côté de cette tôle, loin de la tôle mince. Les valeurs très élevées des résistances de contact électrique et thermique, mesurées aux interfaces avec la tôle d’Usibor®, sont imputables au revêtement Alusi® et sont à l’origine des forts échauffements initiaux observés à ces interfaces. Un modèle numérique, limité aux aspects électrothermiques et développé sur COMSOL Multiphysics®, a permis de montrer que la zone fondue s’initie très rapidement dans la tôle d’Usibor® 1500 sous l’effet des fortes résistances de contact adjacentes, et que son développement en épaisseur et diamètre est piloté par les évolutions des rayons de contact électrode-tôle. Les résistances de contact entre électrode et tôle mince, le profil du courant de soudage et les rayons de courbure des faces actives des électrodes sont les paramètres prépondérants à optimiser pour améliorer la pénétration du noyau dans la tôle mince. / In the automotive industry, the requirements for polluting emissions lead to light vehicles, especially in decreasing the steel sheet thickness. This work in partnership with ArcelorMittal focuses on resistance spot welding of steel sheets. The aim is to identify the phenomena that induce operating weldability difficulties encountered with an asymmetrical stack of three coated steel sheets, including a very thin galvanized sheet of less than 0.6 mm, a sheet of DP600, and a hot stamped Usibor® sheet. Infrared camera observations show that the initial heating takes placeat the interfaces with the Usibor®1500 sheet, and that the nugget appears inside this sheet, away from the thin sheet. The very high values of the electrical and thermal contact resistances, measured at the interfaces with the Usibor®1500 sheet, are due to the Alusi® coating and are at the origin of the strong initial heating at these interfaces. A numerical model, limited to the electro- thermal aspects and developed with COMSOL Multiphysics®, shows that the nugget is initiated very quickly in Usibor®1500 sheet under the effect of adjacent contact resistances, and that its development is driven by the evolutions of the electrode-sheet contact areas. The contact resistances between the electrode and the thin sheet, the welding current evolution, and the curvature radius of electrode tips are the most efficient parameters to be optimized to improve the penetration of the nugget in the thin sheet.