Today, drilling can be considered the most common of all metal cutting operations. Drilling can be accomplished on nearly all machines that can produce a relative rotation of the spindle, and/or the workpiece. These machines can include drill presses, lathes, milling machines and machining centers. Of the more than 1.70 million machine tools in the United States, that are located in plants employing more than twenty workers, more than half of these machines can, and probably are performing drilling functions. Drilling has been studied in numerous investigations with the objective of increasing drill performance. Severely lacking in this research has been the use of statistically designed experiments. Traditional experimental techniques in tooling have been conducted under a one variable at a time methodology. The twist drill, however, is one of the most complex metal cutting tools in existence today. Changing one variable at a time can lead to unwanted changes in other variables. With today's statistical techniques and computers, variables and variable interactions should be able to be adjusted and controlled. Because drilling is one of the leading metal cutting operations, an ever so slight increase in the level of drill performance could yield important benefits to manufacturing. Investigation into drill geometry and variable interaction may also lead to significant increases in drill performance. A quantitative analysis was performed to determine the effect of different independent variables on tool life for Titanium Nitride Coated tools. This was accomplished in two stages. In Stage 1, the variables lip height, helix angle, and margin width were tested one at a time for their effect on tool life. In Stage 2, the variable lip height from Stage 1 and the independent variables, speed and feed, were tested for their effect on tool life in a three variable, two level factorial treatment design. Secondary measurements were also taken in Stage 2 on acceleration, torque and face wear. Stage 1 showed that tighter tolerances on lip height could improve tool life. The 39 degree helix angle was more of a detriment than an aid, to increase tool life. The lowest level of margin width had lower tool life than either of the other two levels. In stage 2 feed and lip height had a significant effect on tool life at the 90% confidence level. Speed did not have an effect on tool life. No variable in Stage 2 had an significant effect on acceleration at either the 95% or 90% confidence level. At the low level of the feed, acceleration readings seemed applicable in determining pending tool failure. The largest values of crater width on the face were associated with the low values of feed. No true distinction can be made with torque, between any of the combinations of levels tested. This research has attempted to further quantify some of the variables and variable interactions associated with drilling for Titanium Nitride Coated tools. / M.S.

This thesis presents a detailed analysis of the plane rake faced drill design, its grinding method and grinding wheel geometry. A fundamental geometrical analysis has then been carried out on the major cutting edges of the modified drills according to the national and international standards. It has been shown that this new drill design results in a significant increase in the normal rake angle at lips as well as point relieving at the chisel edge region. Geometrical models for the various drill point features have been established which uniquely define the drill point features of the modified drill design. A comprehensive experimental investigation has been carried out to study the drilling performance of the modified drills, when drilling a high tensile steel, ASSAB 4340, with TiN coated high speed steel drills over a wide range of drilling conditions. Comparing to the drilling performance with conventional twist drills under the corresponding conditions, it has been found that the modified drills can reduce the thrust force by as much as 46.9% with the average of 23.8%; the reduction of drilling torque is also significant at an average of 13.2% and the maximum of 24.9%. Similarly, the new drill design shows great superiorities over the conventional drills in terms of drill-life. In the drill-life tests, a few conventional drills were broken, but all plane rake faced drills performed very well. In order to estimate the cutting performance in process planning on a mathematical and quantitative basis when drilling with the modified drills, predictive cutting force models have been developed based on the unified-generalized mechanics of cutting approach. The models have been assessed qualitatively and quantitatively and showed good agreements with the experimental thrust, torque and power. Empirical-type force equations have also been developed to provide simple alternatives for practical applications.

This thesis presents a detailed analysis of the plane rake faced drill design, its grinding method and grinding wheel geometry. A fundamental geometrical analysis has then been carried out on the major cutting edges of the modified drills according to the national and international standards. It has been shown that this new drill design results in a significant increase in the normal rake angle at lips as well as point relieving at the chisel edge region. Geometrical models for the various drill point features have been established which uniquely define the drill point features of the modified drill design. A comprehensive experimental investigation has been carried out to study the drilling performance of the modified drills, when drilling a high tensile steel, ASSAB 4340, with TiN coated high speed steel drills over a wide range of drilling conditions. Comparing to the drilling performance with conventional twist drills under the corresponding conditions, it has been found that the modified drills can reduce the thrust force by as much as 46.9% with the average of 23.8%; the reduction of drilling torque is also significant at an average of 13.2% and the maximum of 24.9%. Similarly, the new drill design shows great superiorities over the conventional drills in terms of drill-life. In the drill-life tests, a few conventional drills were broken, but all plane rake faced drills performed very well. In order to estimate the cutting performance in process planning on a mathematical and quantitative basis when drilling with the modified drills, predictive cutting force models have been developed based on the unified-generalized mechanics of cutting approach. The models have been assessed qualitatively and quantitatively and showed good agreements with the experimental thrust, torque and power. Empirical-type force equations have also been developed to provide simple alternatives for practical applications.

A preparação das arestas de corte é um processo que tem chamado a atenção na indústria de fabricação e recondicionamento de ferramentas em função dos benefícios que tem trazido especialmente na vida útil da ferramenta. Este processo dá um grande diferencial competitivo àqueles que detém o conhecimento de como aplicá-lo e por isso é mantido como um segredo industrial. No que se refere a brocas helicoidais a escassez de informações é ainda maior, em função da alta complexidade da ferramenta e do processo. O presente trabalho traz os resultados da influência da preparação das arestas de corte (alteração da microgeometria) de brocas helicoidais no processo de furação do aço SAE 4144M temperado e revenido com 38 HRC. O processo manual de escovamento foi utilizado para preparar as ferramentas com arestas arredondadas e o processo manual de limagem para as ferramentas com arestas chanfradas. Foram medidas várias características das peças usinadas tais como: diâmetro, circularidade, desvio de posição, rugosidade dos furos obtidos, dureza, microdureza dos corpos-de-prova, força de avanço e torque do processo de furação, avaliação do tipo e forma dos cavacos gerados no processo. Os resultados mostraram que o processo de preparação de arestas aumenta a resistência da ferramenta ao desgaste e consequentemente aumenta sensivelmente sua vida, especialmente as de arestas arredondadas. Além disso, exerce influência na integridade superficial do furo obtido (circularidade e rugosidade) e na microdureza da região próxima à parede do furo obtido. Não houve diferença significativa no torque entre as geometrias analisadas, porém a força de avanço foi menor para a ferramenta apenas afiada sem preparação de aresta. / The cutting edge preparation is a process which has drawn attention from the tool’s manufacturing and refurbishing industry due to specialization to its benefits specially to tool useful life. This process results in a major competitive advantage to those who have the knowledge of its application and, for this reason, it is kept as a trade secret. As far as the twist drills are concerned, the scarcity of information is even greater, due to the high complexity of the tool and process itself. This dissertation presents the results of the influence of the preparation of the twist drills cutting edges microgeometry alteration in steel drilling process SAE 4144M quenched and tempered steel with 38 HRC. The manual brushing process was used to prepare tools with rounded edges and manual filing process was used to prepare tools with chamfered edges. Several features from the machined parts were measured, such as diameter, roundness, position deviation, roughness of the obtained holes, hardness and microhardness of specimens, feed force and torque of the drilling process, assessment of type and shape of the chips from the process. The results showed that the edges preparation process increases the wear resistance of the tool and thereby increases its useful life significantly, especially for tools with rounded edges. In addition, it influences the surface integrity of the obtained hole (circularity and roughness) and the hardness of the region near the wall of the obtained hole. There was no significant difference in torque between the analyzed geometries, however the thrust force was lower for the sharpened tool without any edge preparation.

published_or_final_version / Applied Geosciences / Master / Master of Science

Orientador: Victor Orlando Gamarra Rosado / Banca: Fernando de Azevedo Silva / Banca: Maurício Guimarães da Silva / Resumo: Controlar a pressão de poços petrolíferos durante a perfuração pode ser um dos processos mais complexos e perigosos da etapa de exploração. O sistema de perfuração varia constantemente e aleatoriamente, isto principalmente, devido à mudança da profundidade de perfuração, a qual faz variar outros parâmetros do processo. Assim, a aplicação de um controle variante no tempo torna-se necessário. Este estudo propõe o projeto de um controlador Gain Scheduling (GS) no controle da pressão no fundo de poços durante a perfuração. Este controlador GS consiste na sintonia dos ganhos relacionados aos diferentes pontos operacionais, para este caso, a profundidade do poço. Primeiro, apresentam-se as teorias a serem utilizadas durante o desenvolvimento do trabalho. Segundo, obtém-se o modelo matemático do processo o qual se fundamenta na mecânica dos fluidos. Da linearização do modelo, a função de transferência resultante apresenta um elemento integrador o que faz que a dinâmica do processo seja difícil de manipular. Também se adiciona um tempo de atraso, o que torna mais complexo o controle do processo. Na terceira parte, utilizaram-se três tipos de metodologias IMC (Internal Model Control) para sintonizar os ganhos do controlador PID (Proporcional, Integral e Derivativo) para diferentes profundidades de perfuração procurando o melhor desempenho, estabilidade e robustez do sistema. Finalmente, escolhe-se a estratégia de melhor desempenho (IMC de dois graus de liberdade) para especificar e mo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Controlling the pressure of oil wells during drilling can be one of the most complex and dangerous processes of exploration stage. The drilling system is constantly end randomly changing due, among other things, the drilling depth, which varies other process parameters, accordingly to apply a time variant control becomes necessary. This study proposes the design of a Gain Scheduling controller to control the pressure at the bottom of wells during drilling. The GS controller is based on the corresponding tuning gains at different operating points in this case, the depth. First, presents the theories that will be used during development work. In the second part, was obtained a mathematical model of the process which is based on fluid mechanics. In the linearization of the, the final transfer function presents an integrating element which makes the process dynamics more difficult to handle. It becomes even more complex in the presence of time delay. In the third part, three IMC controllers' types were used to tuning the PID (Proportional, Integral and Derivative) controller gains for different depths of drilling looking for the best performance, stability and robustness. Finally, was chose the best performing strategy (IMC of two degrees of freedom) to specify and assemble the GS controller table, which is evaluated by simulations of problems that usually occur during drilling, considered as disturbances, which check its viability. Also, the results of the controlled GS system a... (Complete abstract click electronic access below) / Mestre

Thesis. 1977. Mech.E.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by K. Subramanian. / Mech.E.

Thesis (Ph.D.)--University of Tulsa, 1994. / Includes bibliographical references (leaves 87-92).

Orientador: Mauro Hugo Mathias / Coorientador: Gerhard Thonhauser / Banca: Edson Cocchieri Botelho / Banca: João Andrade de Carvalho Junior / Banca: José Luis Gonçalves / Banca: Behzad Elahifar / Abstract: Pre-salt basins and their exploration have become more and more frequently mentioned over the years, not just for their potential reserves, but also for the implicit challenges in terms of operations to face in order to make these fields commercially viable. Several research efforts aimed at addressing these related barriers, in which drilling optimization and efficiency are presented as a considerably complex area. The problematic is concentrated in the low drillability and in the high cost involved when drilling the pre-salt carbonates. The outcome of this research is based in studies performed on top of eight pre-salt wells, addressing drilling operational time savings referenced by benchmarks and drilling mechanics parameters choosiness. The studies were based on simulations performed with penetration rate (ROP) modeling combined with specific energy (SE). The Bourgoyne Jr. and Young Jr. (1974) ROP model was used given the high errors presented for the other models, higher than 40% and, in terms of SE, the formulations from Teale (1965) and Pessier et al. (1992) were used. All these classic literature are still present in the industry and the software Oracle Crystal Ball was used as a supportive tool for the simulations. This research yielded four important results: 1) the polycrystalline diamond compact (PDC) is the most suitable drill-bit choice for pre-salt, presenting the lowest teeth-cutters wear rate, 0.28 [%/ m]; 2) the possible spare in operational time encountered for the pre-salt operations represent a saving of approximately 13,747,550.00 [USD] for the analyzed pre-salt wells; 3) the final mathematical model developed, after the adjustments for pre-salt, foresee an improvement dropping the relative error from 36.52% to 23.12% in terms of comparing the calculated and modeled ROP with the field measured ROP... (Complete abstract click electronic access below) / Resumo: As bacias do pré-sal e sua exploração se tornaram cada vez mais mencionadas ao longo dos anos, não apenas por seu potencial de reservatório, mas também devido aos grandes desafios implícitos em termos de operações a serem enfrentados para tornar estes campos comercialmente viáveis. Várias pesquisas vêm sendo desenvolvidas visando contornar estas barreiras, das quais a otimização e eficiência de perfuração se apresentam como uma área consideravelmente complexa. A problemática se concentra nas baixas taxas de penetração e no alto custo envolvido ao se perfurar as seções dos carbonatos do pré-sal. Os resultados da pesquisa apresentados nesta tese baseiam-se em análises com oito poços do pré-sal, abordando economia de tempo operacional com base em análises referenciadas em benchmarks e escolhas de parâmetros mecânicos de perfuração. Os estudos foram baseados em simulações realizadas com modelagem de taxa de penetração (ROP) combinadas com energia específica (SE). Utilizou-se o modelo de ROP de Bourgoyne Jr.e Young Jr. (1974) face aos altos erros apresentados pelos outros modelos, superiores a 40% e, em termos de SE, utilizouse o equacionamento de Teale (1965) e Pessier et al. (1992). Todas estas literaturas classicas ainda estão presentes na indústria e o software Oracle Crystal Ball foi utilizado como uma ferramenta de apoio para as simulações. Os resultados deste trabalho mostraram quatro conclusões importantes: 1) a broca de perfuração do tipo polycrystalline diamond compact (PDC) é a mais adequada para o pré-sal, apresentando uma taxa de desgaste de dentes-cortadores de 0.28 [%/ m]; 2) a possível diminuição de tempo de operação encontrada após análises de performance de operação pode resultar em uma economia de aproximadamente 13,747,550.00 [USD] para os poços do pré-sal analisados... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

To remain competitive in today’s demanding economy, there is an increasing demand for improved productivity and scrap reduction in manufacturing. Traditional manufacturing metal removal processes such as turning and boring are still one of the most used techniques for fabricating metal products. Although the essential metal removal process is the same, new advances in technology have led to improvements in the monitoring of the process allowing for reduction of power consumption, tool wear, and total cost of production. Replacing used CNC lathes from the 1980’s in a manufacturing facility may prove costly, thus finding a method to modernize the lathes is vital. This research focuses on Phase I and II of a three phase research project where the final goal is to optimize the simultaneous turning and boring operation of a CNC Lathe. From the optimization results it will be possible to build an adaptive controller that will produce parts rapidly while minimizing tool wear and machinist interaction with the lathe. Phase I of the project was geared towards selecting the sensors that were to be used to monitor the operation and designing a program with an architecture that would allow for simultaneous data collection from the selected sensors at high sampling rates. Signals monitored during the operation included force, temperature, vibration, sound, acoustic emissions, power, and metalworking fluid flow rates. Phase II of this research is focused on using the Response Surface Method to build empirical models for various responses and to optimize the simultaneous cutting process. The simultaneous turning and boring process was defined by the four factors of spindle speed, feed rate, outer diameter depth of cut, and inner diameter depth of cut. A total of four sets of experiments were performed. The first set of experiments screened the experimental region to iii determine if the cutting parameters were feasible. The next three set s of designs of experiments used Central Composite Designs to build empirical models of each desired response in terms of the four factors and to optimize the process. Each design of experiments was compared with one another to validate that the results achieved were accurate within the experimental region. By using the Response Surface Method optimal machining parameter settings were achieved. The algorithm used to search for optimal process parameter settings was the desirability function. By applying the results from this research to the manufacturing facility, they will achieve reduction in power consumption, reduction in production time, and decrease in the total cost of each part.