| 1. |
- Repo, Jari
(författare)
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Condition monitoring of machine tools and machining processes using internal sensor signals
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Condition monitoring of critical machine tool components and machining processes is a key factor to increase the availability of the machine tool and achieving a more robust machining process. Failures in the machining process and machine tool components may also have negative effects on the final produced part. Instabilities in machining processes also shortens the life time of the cutting edges and machine tool. The condition monitoring system may utilise information from several sources to facilitate the detection of instabilities in the machining process. To avoid additional complexity to the machining system the use of internal sensors is considered. The focus in this thesis has been to investigate if information related to the machining process can be extracted directly from the internal sensors of the machine tool. The main contibutions of this work is a further understanding of the direct response from both linear and angular position encoders due the variations in the machining process. The analysis of the response from unbalance testing of turn tables and two types of milling processes, i.e. disc-milling and slot-milling, is presented. It is shown that operational frequencies, such as cutter frequency and tooth-passing frequency, can be extracted from both active and inactive machine axes, but the response from an active machine axis involves a more complex analysis. Various methods for the analysis of the responses in time domain, frequency domain and phase space are presented.
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| 2. |
- Aganovic, Dario, 1974-
(författare)
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On Manufacturing System Development in the Context of Concurrent Engineering
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents an extension of the contemporaryengineering design theory towards a unified view onsimultaneous development of products and manufacturing systems,i.e. concurrent engineering. The traditional engineering design theory explains therealization of a product design as a development of productstructure from four perspectives: technical process, function,technical solution, and physical embodiment. This thesisextends the engineering design theory with a set of definitionsand universal statements. These definitions and universalstatements describe manufacturing systems from same fourperspectives. In that context they also describe therelationship between a product and its manufacturing system.The thesis contributes to the creation of a single theoreticalsystem based on an integration of theories from two engineeringdesign schools, the WDK and the Axiomatic Design. WDKtheoriesare in this new context utilized for qualitative synthesis ofthe developed artifacts, while the Axiomatic Design is utilizedfor structuring and analyzing the corresponding quantitativeparameters. The definitions and universal statements describe thedevelopment structures for productsand manufacturing systems.This description is utilized for definition of a system fordevelopment of these structures, i.e. (i) a stage-gate-basedmanufacturing system development process, (ii) a developmentmethodology toolbox, and (iii) an information managementframework consisted of an information model harmonized with thesystems engineering data management standard STEP AP 233. The research has been carried out in a close collaborationwith Swedish manufacturing industry. The utilized researchmethodology is the hypothetic- deductive method, with casestudy as an observation method. Keywords:Concurrent Engineering, Engineering Design,Development Methods and Tools, Manufacturing System,Information Management.
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| 3. |
- Alhusin Alkhdur, Abdullah, 1980-
(författare)
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Toward a Sustainable Human-Robot Collaborative Production Environment
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This PhD study aimed to address the sustainability issues of the robotic systems from the environmental and social aspects. During the research, three approaches were developed: the first one an online programming-free model-driven system that utilises web-based distributed human-robot collaboration architecture to perform distant assembly operations. It uses a robot-mounted camera to capture the silhouettes of the components from different angles. Then the system analyses those silhouettes and constructs the corresponding 3D models.Using the 3D models together with the model of a robotic assembly cell, the system guides a distant human operator to assemble the real components in the actual robotic cell. To satisfy the safety aspect of the human-robot collaboration, a second approach has been developed for effective online collision avoidance in an augmented environment, where virtual three-dimensional (3D) models of robots and real images of human operators from depth cameras are used for monitoring and collision detection. A prototype system is developed and linked to industrial robot controllers for adaptive robot control, without the need of programming by the operators. The result of collision detection reveals four safety strategies: the system can alert an operator, stop a robot, move away the robot, or modify the robot’s trajectory away from an approaching operator. These strategies can be activated based on the operator’s location with respect to the robot. The case study of the research further discusses the possibility of implementing the developed method in realistic applications, for example, collaboration between robots and humans in an assembly line.To tackle the energy aspect of the sustainability for the human-robot production environment, a third approach has been developed which aims to minimise the robot energy consumption during assembly. Given a trajectory and based on the inverse kinematics and dynamics of a robot, a set of attainable configurations for the robot can be determined, perused by calculating the suitable forces and torques on the joints and links of the robot. The energy consumption is then calculated for each configuration and based on the assigned trajectory. The ones with the lowest energy consumption are selected.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Andersson, Oscar, 1968-
(författare)
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Digital process planning of joining by numerical models in the automotive industry
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The automotive industry is striving towards reduction of greenhouse gas emission by reducing product weight and improving fuel efficiency of their products. The introduction of lightweight materials have imposed greater pressure not only on the product development but also on manufacturing systems. One integral aspect of manufacturing systems, which is meeting these challenges is joining technology. In order to achieve successful joining of new automotive products, joining process planning must be equally successful.This research aims at improving process planning of joining by introducing digital tools into the process planning work method. The digital tools are designed to reduce lead times and increase accuracy of the process planning to realize more advanced, complex and environmentally friendly product solutions in the vehicles of the future.The research has two main focuses. Firstly, the joining process planning structure and organization have been analysed. The analysis has identified specific instances where digital tools can be introduced to improve the process planning and make it more efficient. Digital tools, such as numerical models for prediction and databases for re-use of knowledge, have been suggested for the process planning. An assessment of the impact of the introduction of these tools in an industrial test case has been performed to show the possible reduction in lead times.Secondly, geometrical distortions due to laser beam welding have been investigated, both by experimental trials and numerical modelling. The influences of design and process parameters on the distribution and magnitude of geometrical distortions have been established. Numerical models of different modelling detail and complexity have been developed and evaluated in order to find modelling approaches with reduced computation times aimed at industrial implementation. The predictive accuracy and computational efficiency of the numerical models have been assessed and evaluated with regard to industrial implementation.
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| 8. |
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| 9. |
- Archenti, Andreas, 1973-
(författare)
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Model-Based Investigation of Machining Systems Characteristics : Static and Dynamic Stability Analysis
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The increasing demands for precision and efficiency in machining call for new control strategies for machining systems based on the identification of static and dynamic characteristics under operational conditions. By considering the machining system as a closed-loop system consisting of a machine tool structure and a machining process, the join system characteristics can be analyzed. The capability of a machining system is mainly determined by its static and dynamic stiffness. The goal of this thesis is to introduce some concepts and methods regarding the identification of machining system stability. Two methods are discussed, one for the static behaviour analysis of a machine tool, and one for dynamic stability of a machining system. Preliminary results are indicating unambiguous identification of capabilities of machining systems static and dynamic characteristics. The static behaviour of a machine tool is evaluated by use of a loaded double ball bar (LDBB) device. The device reproduces the real interaction between the join system, the machine tool elastic structure and the cutting process. This load is not equivalent to real cutting forces, but it does have a similar effect on the structure. This has been investigated both trough simulation and experimental work. It is possible to capture the process – machine interaction in a machining system by use of the model-based identification approach. The identification approach takes into consideration this interaction and can therefore be used to characterize the machining system under operational conditions. The approach provides realistic prerequisites for in-process machining system testing. The model parameters can be further employed for control and optimization of the cutting process. Using different classification schemes, the model-based identification method is promising for the detection of instability. Furthermore, it is the author’s belief that a model-based stability analysis approach is needed to exploit the full potential of a model driven parts manufacturing approach.
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| 10. |
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| 11. |
- Bayard, Ove, 1967-
(författare)
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Investigation of Forces and Contact Area for Modelling Turning Processes
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is focused on an investigation of forces andcontact area for modelling turning processes. The primary taskin short term research has been to take a first steptowards animproved model of the cutting process. The ultimate goal is tofind predictive models and thereby reduce the number of cuttingtests necessary to perform before an“unknown”tool-material combination can be considered for machining.Today, lot of time and money is spent to gather appropriatecutting data and material parameters. This is, nevertheless,necessary to understand and characterise the fundamentalbehaviour of a workpiece, when it is machined. To describe the complicated nature of the deformationprocess in cutting, analytical shear plane models are oftenemployed. In this thesis, a review of some classic models ispresented. The validity of a proposed model can be confirmed ifthe values generated can be correlated to experimental results.A difficulty is often to find a method that gives the desiredexperimental parameters. An important source for information isthe samples generated through Quick Stop tests. A reliableQuick Stop Device (QSD) has therefore been developed and ispresented in the thesis. Since the focus for this investigation has been to propose atentative model for cutting forces in turning, a number offorce measurements have been performed. Two different steelgrades have been evaluated in orthogonal machining, AISI-1045and AISI-12L13. Cutting force measurements (feed- and maincutting force), were conducted with a high accuracydynamometer. To investigate contact area conditions, Quick Stopspecimens, chips and inserts were examined. The evaluation wasperformed both in an Optical Light Microscope and a ScanningElectron Microscope. Three different models can be used tocharacterise the contact area. According to the contactconditions these models refer to sticking friction, flow-zoneand sliding friction region. Results from model simulations were fitted to those ofexperimental cutting investigations in order to evaluate theaccuracy of the cutting force and contact area approach. Thetest results are also used as reference data for a proposedsimple tentative model presented in this thesis. The model isrestricted to orthogonal machining. The proposed model consistsof several steps. The first step is to determine the maincutting force Fc. Expressions that describe Fcas a function of the cutting velocity (vc) for different feed (f) values have been derived.To be able to evaluate the feed force, the contact length lchas first to be determined. Relationships where lcis expressed as a function of vcfor different feeds have been derived. Tocalculate the feed force, a formula for Ff/Fcas a function of lcis applied. Equations for determiningΛ, hchandΦ have also been derived. In short,the functions found are: Fc= f(vc; f), lc= f (vc; f), Ff= f(Fc; lc),Λ = f(lc; f) andΦ = f(vc; f). This research work shows that it is of utmost significance,in order to generate realistic values, that a predictive modelis supported by adequate reference data. It is also shown thatthe contact area is an important parameter that has to beconsidered in modelling. Keywords:Modelling, turning processes, cutting forces,contact length, Quick Stop Device, QSD, simulation programs,FEM, predictive models.
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| 12. |
- Bejhem, Mats
(författare)
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Machining Monitoring and Control : Based on Parametric Modelling
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this work was the development of aMachining Control prototype system for turning, whichintegrates three fundamental aspects of Machining Controltechnology: Monitoring, Control and Optimisation. MachiningControl refers to the detection and automatic handling ofdisturbances in machining processes. Consequences ofdisturbances can be classified in three major groups:Breakdowns, production rejects and non-optimal production. Byminimising these consequences, the efficiency of the machiningprocess can be improved, which in turn will have a major impacton productivity, machining economy and product quality as well.This calls for user friendly supervisory systems that cansupport the human operator and perform monitoring, control andoptimisation tasks, i.e. Machining Control (MC) systems. The MC system presented in this thesis is developed around aturning centre, and consists basically of a PC equipped with amodular DSP multiprocessor, sensor systems for vibration andcutting force measurements, as well as machine tool interfaces.The basic structure of the MC system allows flexibleimplementation of tasks, which can interact with the machinetool controller and other auxiliary devices. In other words,the MC system combines virtually all essential features toperform advanced real time supervision. An important aspect in the development of this MC system wasthe access to accurate data, reflecting the underlyingmachining process. Therefore, the turning centre is equippedwith an integrated dynamometer and an acoustical sensor systemthat have access to the tool-workpiece interface. To ensurereliable cutting force measurements, a three-axis calibrationmethod has been developed that performs a transformation ofoutput signals from the force sensor system to accurate cuttingforces at the tool tip. A good knowledge of tool vibration andinstantaneous cutting forces allows the safer use of moreaggressive machining operations, thus utilising most of theavailable tool life withoutcausing costly breakdowns andproduction rejects. Two MC functions for in-process tool condition monitoringhave been developed and are discussed from both theoretical andexperimental point of view. Classical models have been used toanalyse the dynamic behaviour of the machining system, whileparametric modelling was employed for in-process monitoring andcontrol of dynamic stability. It is shown that an efficientcontrol of dynamic stability only can be performed if propertooling is selected. Some efficient solutions for improving thedynamic properties of tooling are presented. Finally, a modulefor an automatic optimisation of cutting conditions isdescribed. This module takes advantage of all the features thatare implemented in the MC system. This research work shows a successful application of anintegrated MC system for an effective combination betweenpeople and technology in future manufacturing systems. Keywords:Machining Control, tool condition monitoring,in-process dynamic stability monitoring and control,optimisation of cutting conditions, MC, DSP, TCM
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| 13. |
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| 14. |
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| 15. |
- Berglund, Anders, et al.
(författare)
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Investigation of the Effect of Microstructures on CGI Machining
- 2007
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Konferensbidrag (refereegranskat)abstract
- The aim of this investigation is to evaluate the effect of microstructures on CGI machining and to compare to gray iron reference material. Special designed workpieces, to reproduce real situations, were machined in face milling. The project planning was based on factorial analysis of design of experiments. The results showed that the strongest parameter affecting tool life is the pearlite content. Furthermore it is clear that due to imprecision of manufacturing process it is difficult to obtain test specimens with homogenous microstructures and corresponding varying mechanical properties, when the specimen presents a complex geometrical form. Thin sections found in walls tend to have higher nodularity, resulting in spherical graphite. To refine the investigation of the effect of microstructures on CGI machining it would be preferred to use test specimens without holes or slots to minimise noise in the factor analysis.
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| 16. |
- Bjelkemyr, Marcus, 1975-
(författare)
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System of Systems Characteristics in Production System Engineering
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a systems view of production, where production systems are compared and contrasted with other large and complex systems, commonly labeled System of Systems (SoS). The rationale for this approach lies in the evolution of production systems towards being holistic, sustainable, and agile; which increases the need for an improved understanding of both how internal system are interrelated, and how the production system interacts with its environment. In turn, this leads to an increase of complexity for the production system, which leads to new requirements on systems engineering.The definition of SoS is extensively discussed, and in this thesis formalized with regards to certain system characteristics that SoS exhibit. The presence of these characteristics is evaluated for three different levels of production systems to determine if they should be considered SoS. In the second part of the thesis, the SoS characteristics are addressed from an engineering point of view, i.e. if and how SoS properties are currently addressed in production systems engineering.Two main results are presented in this thesis: (1) production systems exhibit SoS characteristics; (2) SoS characteristics are not and cannot be addressed with current systems engineering methods. How SoS characteristics can be addressed is briefly discussed in the frame of reference.An additional purpose of this thesis is to initiate a new research area where production systems research and complex systems research are merged.
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Chen, Danfang
(författare)
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Information management for the factory planning process
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is based on the present needs for the factory planning support, of which the most important ones are: • A structured reuse of knowledge and support for industries. Because today the industry handbook in factory planning is not satisfying enough to support this complex process. • Better methods to represent and communicate data between software within the factory layout area for easier data communication and thereby information access, exchange and reuse. To support the factory planning, based on the mentioned needs, a mapping of the present factory planning process is made based on knowledge from industry and academy. Since the factory planning process is a huge and complex process that no one can handle by themself, a puzzle work is performed. Based on gathered information and knowledge an activity model is developed, to structure the data and information. The model gives a better overview on the actual course of events and in this way also “captures” the most important information to be represented for data exchange among different software applications and different people. In this thesis the most important information in factory layout is gathered and structured in a concept model for factory layout. Since the concepts depend on the context in which they are used, it is extremely important to present every concept in its relationship with other related concepts within the area. A general theory and state-of-the-art definitions in the area is presented and discussed for a factory planning information management system. An evaluation and discussion is made for the state-of-the-art software in the area of concern.
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| 21. |
- Clausson, Leif, 1946-
(författare)
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Business Innovation by utilizing Engineering Design Theory and Methodology
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Industrial companies that carry on innovation and operation must have well-organized and capable business systems and processes. Customer needs, market demands, global competition and technological changes drive the companies to be more adaptable, flexible and dynamic. By working in network structures as extended enterprises, the companies face new possibilities and new challenges. Design, manufacturing and delivery of high quality products to competitive prices to the customers are essential for industrial companies. Holistic view of the product life cycle from technology development, via product and business system development and realization, to business operation, is important for sustainable industrial companies. A company with engineering and manufacturing of products in a business context needs to have effective innovation of business system and process. Business innovation encompasses the area from business idea to business operation and includes customer demands and solutions. The main part of business innovation is development of the product platform including product and support structures. Product variants are created and realized by various configurations of products and production systems. The thesis is elucidating that business innovation can be carried out by working in a systematic and structured way and by utilizing engineering design theories and methods. The business models, based on a new theory with a new navigation tool for interactions, are describing which activities should be performed in business innovation with product platform development and product structuring. For companies in business with changes, innovations can create new markets and products. Well-managed and innovative companies have good possibilities to be competitive in a tough business environment. The creation of business innovation models has been carried out according to a hermeneutic research method. The research work followed the hermeneutic circle or spiral. The thesis introduces a new dimension to the design area, namely business innovation or engineering, corresponding to business design and development. Business innovation is also a new type of innovation, combining technological, product, process, market and organizational innovations in industrial companies.
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| 22. |
- Daemi, Bita, 1982-, et al.
(författare)
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Analysis of camera image repeatability using manual and automatic lenses
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Autofocus lenses are conveniently used for applications such as video metrology. In this study we investigate the stability of capturing images and show that for precision metrology applications the autofocus lenses are not as accurate as manual lenses. The investigation was done by analyzing series of seven repeated images captured from a highly accurate reference artifact using two different lenses; autofocus and manual, mounted on a same camera system.
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| 23. |
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| 24. |
- Daemi, Bita, 1982-, et al.
(författare)
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Performance evaluation of a micro screen printing installation
- 2017
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Micro- and nano-manufacturing is an expanding industry and many different manufacturing techniques are used, from advanced focused ion beam treatment to reasonably simple printing technologies. Common to all of them are the needs to verify the manufactured geometries and dimensions. This report presents the results of the second round of benchmarking activities within the EUMINAfab European Research Infrastructure, in order to establish more knowledge about the capabilities of a screen printing installation. To obtain a better understanding of the accuracy of the screen printing installation, a precise verification test is needed to measure the absolute performance of the machine. Predicted performance and capability information is based on specifications given for the machine installation by the machine deliverer. But, in practice the absolute performances of the installation is often off from the specification. When forming the EUMINAfab infrastructure consortium it was decided that independent high precision verification tests should be made on different installations to help the micro-manufacturers to get the real capability information of their equipment and be able to improve performance to a higher EUMINAfab level. In this study a comprehensive verification test was designed and carried out by using an ultra-precision metrology method in order to establish more knowledge about the capabilities of the screen printing equipment. The measurement results show the machine’s X,Y position accuracy, pseudo-repeatability and reproducibility. It is not as good as predicted.
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| 25. |
- Daghini, Lorenzo
(författare)
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Theoretical and experimental study of tooling systems : passive control of machining vibration
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vibration control has been and still remains a subject of primary importance in modern manufacturing industry. To be able to remove high volumes of material in shorter time as well as to be able to get the right quality of the parts at the first time are goals that many shops would like to achieve. Tooling systems, and especially cantilever tools, and cantilever structural units of machine tools are the least rigid components of machining systems and therefore the most prone to vibration. Boring tools are often encountered as rotating tools in machining centres or as stationary tools in internal turning. In this thesis the focus is on internal turning. Internal turning is widely known as a very delicate operation and it is often carried out with cutting parameters far from optimal, from a productivity point of view, due to limitations imposed by vibration. Another type of tooling system whose functionality is impaired by vibration is the parting-off tool. The design of damped parting-off tool is one of the focus of this thesis as well. Vibration control has the purpose to achieve an efficient energy dissipation of a vibrational system. Basically this is achieved by controlling the damping of the system. Since damping involves the conversion of energy associated with a vibration to other forms, there are several mechanisms to remove energy from a vibrating system. Typically these mechanisms are divided in two classes: 1. Mechanisms that convert mechanical energy to heat, i.e. passive damping. 2. Mechanisms that transport energy away from vibrating systems, i.e. active damping. Both these techniques have been used during the years and both have been giving excellent results. The active vibration control mechanisms are more expensive and not suitable for machining due to the cables they necessitate that could interfere with the machining operation. This work proposes an original approach to vibration damping in machining systems, the objects of vibration dissipation being the structural components on the link between turret and cutting insert. The idea is to use composite materials to create damping interfaces between and within the different structural components. Different clamping system designs are being compared in order to see how these influence the performance of the machining system and different cutting inserts have been compared for machining hardened steel. The newly designed components have been going through both extensive off-line (modal analysis) and on-line dynamic testing (machining test) and the results show that the new tool holders used in combination with hydrostatic clamping system are the most optimal solution among the tested ones. The new design for the turret has been giving promising results and more can be achieved by bringing minor changes to it, these changes are being implemented at the time of writing this thesis.
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