7,567 research outputs found
The Development of a Technological Processor as a Part of a Workpiece Programming System
The cost of turning on NC-lathes is substantially sensative to cutting conditions. The use of optimum cutting conditions is limited by a large number of constraining factors such as chip disposal, chucking possibility, available power, required accuracy etc. The present way of work preparation, even when using the available workpiece programming systems, does hardly allow of generating acceptable values for the cutting variables. Moreover, the combination of geometrical and a technological processor in one workpiece programming system will save substantial time in work preparation.\ud
Starting from a former reported development, this article deals with the development of a technological processor of improved design and extended possibilities, as for instance the handling of the chucking problem, as a part of a complete workpiece programming system. At choice the output of this processor may be presented in graphes, showing the limited working area and indicating the preferential working point.\ud
Another feature is the possibility of automatic tool selection by comparing the working area of the machine tool with the working areas of the different potential tools.\ud
The overall system design is modular and well structured to further portability and flexibility
Distributed machining control and monitoring using smart sensors/actuators
The study of smart sensors and actuators led, during the past few years, to the development of facilities which improve traditional sensors and actuators in a necessary way to automate production systems. In an other context, many studies are carried out aiming at defining a decisional structure for production activity control and the increasing need of reactivity leads to the autonomization of decisional levels close to the operational system. We suggest in this paper to study the natural convergence between these two approaches and we propose an integration architecture dealing with machine tool and machining control that enables the exploitation of distributed smart sensors and actuators in the decisional system
Modular Machining Line Design and Reconfiguration: Some Optimization Methods
http://www.intechopen.com/articles/show/title/modular_machining_line_design_and_reconfiguration__some_optimization_methodsInternational audienc
Eco-efficient process based on conventional machining as an alternative technology to chemical milling of aeronautical metal skin panels
El fresado químico es un proceso diseñado para la reducción de peso de pieles metálicas que, a
pesar de los problemas medioambientales asociados, se utiliza en la industria aeronáutica desde los
años 50. Entre sus ventajas figuran el cumplimiento de las estrictas tolerancias de diseño de piezas
aeroespaciales y que pese a ser un proceso de mecanizado, no induce tensiones residuales. Sin
embargo, el fresado químico es una tecnología contaminante y costosa que tiende a ser sustituida.
Gracias a los avances realizados en el mecanizado, la tecnología de fresado convencional permite
alcanzar las tolerancias requeridas siempre y cuando se consigan evitar las vibraciones y la flexión
de la pieza, ambas relacionadas con los parámetros del proceso y con los sistemas de utillaje
empleados.
Esta tesis analiza las causas de la inestabilidad del corte y la deformación de las piezas a través
de una revisión bibliográfica que cubre los modelos analíticos, las técnicas computacionales y las
soluciones industriales en estudio actualmente. En ella, se aprecia cómo los modelos analíticos y las
soluciones computacionales y de simulación se centran principalmente en la predicción off-line de
vibraciones y de posibles flexiones de la pieza. Sin embargo, un enfoque más industrial ha llevado al
diseño de sistemas de fijación, utillajes, amortiguadores basados en actuadores, sistemas de rigidez
y controles adaptativos apoyados en simulaciones o en la selección estadística de parámetros.
Además se han desarrollado distintas soluciones CAM basadas en la aplicación de gemelos virtuales.
En la revisión bibliográfica se han encontrado pocos documentos relativos a pieles y suelos
delgados por lo que se ha estudiado experimentalmente el efecto de los parámetros de corte en su
mecanizado. Este conjunto de experimentos ha demostrado que, pese a usar un sistema que
aseguraba la rigidez de la pieza, las pieles se comportaban de forma diferente a un sólido rígido en
términos de fuerzas de mecanizado cuando se utilizaban velocidades de corte cercanas a la alta
velocidad. También se ha verificado que todas las muestras mecanizadas entraban dentro de
tolerancia en cuanto a la rugosidad de la pieza. Paralelamente, se ha comprobado que la correcta
selección de parámetros de mecanizado puede reducir las fuerzas de corte y las tolerancias del
proceso hasta un 20% y un 40%, respectivamente. Estos datos pueden tener aplicación industrial en
la simplificación de los sistemas de amarre o en el incremento de la eficiencia del proceso.
Este proceso también puede mejorarse incrementando la vida de la herramienta al utilizar
fluidos de corte. Una correcta lubricación puede reducir la temperatura del proceso y las tensiones
residuales inducidas a la pieza. Con este objetivo, se han desarrollado diferentes lubricantes, basados
en el uso de líquidos iónicos (IL) y se han comparado con el comportamiento tribológico del par de
contacto en seco y con una taladrina comercial. Los resultados obtenidos utilizando 1 wt% de los
líquidos iónicos en un tribómetro tipo pin-on-disk demuestran que el IL no halogenado reduce
significativamente el desgaste y la fricción entre el aluminio, material a mecanizar, y el carburo de
tungsteno, material de la herramienta, eliminando casi toda la adhesión del aluminio sobre el pin, lo
que puede incrementar considerablemente la vida de la herramienta.Chemical milling is a process designed to reduce the weight of metals skin panels. This process
has been used since 1950s in the aerospace industry despite its environmental concern. Among its
advantages, chemical milling does not induce residual stress and parts meet the required tolerances.
However, this process is a pollutant and costly technology. Thanks to the last advances in
conventional milling, machining processes can achieve similar quality results meanwhile vibration
and part deflection are avoided. Both problems are usually related to the cutting parameters and the
workholding.
This thesis analyses the causes of the cutting instability and part deformation through a literature
review that covers analytical models, computational techniques and industrial solutions. Analytics
and computational solutions are mainly focused on chatter and deflection prediction and industrial
approaches are focused on the design of workholdings, fixtures, damping actuators, stiffening
devices, adaptive control systems based on simulations and the statistical parameters selection, and
CAM solutions combined with the use of virtual twins applications.
In this literature review, few research works about thin-plates and thin-floors is found so the
effect of the cutting parameters is also studied experimentally. These experiments confirm that even
using rigid workholdings, the behavior of the part is different to a rigid body at high speed machining.
On the one hand, roughness values meet the required tolerances under every set of the tested
parameters. On the other hand, a proper parameter selection reduces the cutting forces and process
tolerances by up to 20% and 40%, respectively. This fact can be industrially used to simplify
workholding and increase the machine efficiency.
Another way to improve the process efficiency is to increase tool life by using cutting fluids.
Their use can also decrease the temperature of the process and the induced stresses. For this purpose,
different water-based lubricants containing three types of Ionic Liquids (IL) are compared to dry and
commercial cutting fluid conditions by studying their tribological behavior. Pin on disk tests prove
that just 1wt% of one of the halogen-free ILs significantly reduces wear and friction between both
materials, aluminum and tungsten carbide. In fact, no wear scar is noticed on the ball when one of
the ILs is used, which, therefore, could considerably increase tool life
Thin-Wall Machining of Light Alloys: A Review of Models and Industrial Approaches
Thin-wall parts are common in the aeronautical sector. However, their machining presents
serious challenges such as vibrations and part deflections. To deal with these challenges, di erent
approaches have been followed in recent years. This work presents the state of the art of thin-wall
light-alloy machining, analyzing the problems related to each type of thin-wall parts, exposing the
causes of both instability and deformation through analytical models, summarizing the computational
techniques used, and presenting the solutions proposed by di erent authors from an industrial point
of view. Finally, some further research lines are proposed
Integrated process planning for a hybrid manufacturing system
A hybrid manufacturing system integrated CNC machining and laser-aided layered deposition and achieves the benefits of both processes. In this dissertation, an integrated process planning framework which aims to automate the hybrid manufacturing process is investigated. Critical components of the process planning, including 3D spatial decomposition of the CAD model, improvement of the toolpath generation pattern, repairing strategies using a hybrid manufacturing system, etc., are discussed --Abstract, page iv
ERP-machining centre integration: a modular kitchen production case study
Manufacturing Engineering Society International Conference 2017, MESIC 2017, 28-30 June 2017, Vigo (Pontevedra), SpainThis document presents an ERP system connection with a CNC machining center application in a kitchen furniture manufacturing facility. This has contributed to allow individually designed product to every customer through high process flexibility and integration. A Dynamic Structure Parametric Bill Of Materials is used as basic element in the management information system. The machining center used to perform the preassembly machining with different drilling, milling and sawing modules provides a process versatility that would not be possible using single machines. A standardization of the preassembly machining process for about 99% of the furniture is allowed. This means a very significant saving in material and labor costs and an improvement in the quality of the final product
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