To further the research done in machining complex surfaces, Jensen [1993] developed an algorithm that matches the normal curvature at a point along the surface with the resultant radius formed by tilting a standard flat end mill. The algorithm called Curvature Matched Machining (CM2) is faster and more efficient than conventional three-axis machining [Jensen 1993, Simpson 1995 & Kitchen 1996]. Despite the successes of CM2 there are still many areas available for research. Consider the machining of a mold or die. The complex nature of a mold requires at least 20-30 weeks of lead time. Of those 20-30 weeks 50% is spent in machining. Of that time 50-65% is spent in rough machining. For a mold or die that amounts to 7 to 8 weeks of rough machining. If one could achieve as much as a 10-15% reduction in machining time that would amount to almost one week worth of time savings. As can be seen, small improvements in time and efficiency for rough machining can yield significant results [Fallbohmer 1996]. This research developed an algorithm that focused on reducing the overall machining time for parts and surfaces. Particularly, the focus of this research was within rough machining. The algorithm incorporated principles of three-axis rough cutting with five-axis CM2, hence Rough Curvature Matched Machining (RCM2). In doing so, the algorithm ‘morphed‘ planar machining slices to the semi-roughed surface allowing the finish pass to be complete in one pass. This roughing algorithm has significant time-savings over current roughing techniques.

<p>Examensarbetet som beskrivs i denna rapport handlar om byte av styrsystem i en CNC-svarv på företaget Precisionsdetaljer Mekatronik i Linköping. Ett Fanuc 5 styrsystem har ersatts av ett modernare Fanuc 21i-styrsystem. Rapporten beskriver det nya styrsystemet och redovisar hur arbetet med att praktiskt byta system har gått till. Arbetet indelades i tre delar, informationssökning, praktiskt arbete och dokumentation. Informationssökningen behövdes både för hopkoppling av de olika delarna och för parameter- och ladderprogrammering. Det praktiska arbetet bestod i att koppla tillsammans de delar som fanns beställda och de delar som skulle tas från det gamla styrsystemet. Dokumentationen ska finnas för framtida bruk, då service och utveckling av systemet ska ske. </p> / <p>This examination work describes changing of a control system in a CNC-lathe. The work has been done at Precisionsdetaljer Mekatronik AB in Linköping, a company with eight to nine employees. One Fanuc 5 control system has been replaced by a modern Fanuc 21i-system. This report describes the new control system and how the practical work has been done. The work has been divided into three parts, information searching, practical work and documentation. Information searching is needed for how to connect the different parts and for parameter-and ladder programming. The practical work consisted of connecting the new parts that were ordered and the parts that should be used from the old control system. The documentation may be used in the future, when service and development of the system will be done.</p>

Today’s   market   is   subjected   to   numerous   changes   due   to   the   need   of   continuous improvement  of  different  commercial  brands  in  order  to  survive  against  competitors.  This competition  drives  the  evolution  of  industrial  processes,  to  satisfy  the  high  customers’ requirements. It means that factors such as flexibility, adaptability and agility are crucial for the  successful  development  of  industries,  which  experience  some  degrees  of  uncertainty due  to  machine  breakdowns,  delays  and  market  fluctuations  among  others.  The  current trend  in  manufacturing  industries  consists  in  the  implementation  of  distributed  control systems (DCS), substituting the earlier programmable logic controllers (PLC) systems where a main  processor  operated  as  the  central  unit  of  the  system.  To  this  end,  the  application  of function  blocks  (FB)  compliant  with  the  IEC  61499  standard  represents  an  innovative technique  for  dealing  with  the  design  and  programming  of  DCSs.  These  FBs  enable  the creation  of  event-driven  networks  governed  by  embedded  algorithms  that  can  be  used  to enhance  the  flexibility  and  portability  of  industrial  job-shops  based  on  a  distributed architecture.  Job-shop  floors  represent  a  principal  concept  in  manufacturing  industries.  This  project  is focused on the integration of a computer numerically controlled (CNC) machine and a gantry robot  which  must  be  coordinated  and  cooperate  for  the  achievement  of  an  industrial machining  and  assembly  process.  It  implies  the  design  of  a  PLC-managed  distributed  cell using  nxtControl  software.  This  software  facilitates  the  construction  of  FBs-networks  to control both machines and enables the communication process via service interface function blocks (SI-FB). Likewise, the whole process will be monitored using an interface also created within nxtControl which will allow the operator to decide the batch and characteristics of the production.  This project is also intended to set the basis for the understanding of the FB concept defined in  IEC  61499  which  moves  away  from  earlier  scan-based  systems  to  event-driven  models, aiming to contribute to the development of future research in the function blocks area.

The purpose of the present study is to develop techniques for manufacturing anatomically-shaped substrates of implants made from calcium polyphosphate (CPP) ceramic. These substrates have tissue-engineered cartilage growing on their top surfaces and can be used as implants for osteochondral focal defect repair. While many research groups have been fabricating such substrates using standard material shapes, e.g., rectangles and circular discs, it is considered beneficial to develop methods that can be integrated in the substrate fabrication process to produce an implant that is specific to a patient’s own anatomy (as obtained from computer tomography data) to avoid uneven and/or elevated stress distribution that can affect the survival of cartilage. The custom-made, porous CPP substrates were fabricated with three-dimensional printing (3DP) and computer numerically controlled (CNC) machining for the first time to the best of the author’s knowledge. The 3DP technique was employed in two routines: indirect- and direct-3DP. In the former, 3DP was used to fabricate molds for pre-shaping of the CPP substrates from two different powder size ranges (<75 μm and 106-150 μm). In the latter, CPP substrates were produced directly from the retrofitted 3DP apparatus in a layer-by-layer fashion from 45-75 μm CPP powder with a polymeric binder. The prototyped samples were then sintered to obtain the required porosity and mechanical properties. These substrates were characterized in terms of their dimensional shrinkage and density. Also, SEM images were used to assess the particle distribution and neck and bond formations. The substrates produced using the indirect-3DP method yielded densities (<75 μm: 66.28 ± 11.62% and 106-150 μm: 65.87 ± 6.12%), which were comparable to the substrates used currently and with some success in animal studies. Geometric adjustment factors were devised to compensate for the slight expansion inherent in the 3DP mold fabricating process. These equations were used to bring the plaster molds into true dimension. The direct-3DP method has proven to be the ultimate choice due to its ability to produce complex anatomically-shaped substrates without the use of a chemical solvent. In addition, it allows for precise control of both pore size and internal architectures of the substrates. Thus, the direct-3DP was considered to be superior than the indirect-3DP as a fabrication method. In the alternative CNC machining approach to fabrication, the ability to machine the CPP ceramic was feasible and by careful selection of the machining conditions, anatomically-shaped CPP substrates were produced. To develop strategies for optimizing the machining process, a mechanistic model was developed based on curve fitting the average cutting forces to determine the cutting coefficients for CPP. These cutting coefficients were functions of workpiece material, axial depth of cut, chip width, and cutter geometry. To explore the utility of this modelling approach, cutting forces were predicted for a helical ball-end mill and compared with experimental results. The cutting force simulation exhibits good agreement in predicting the fundamental force magnitude and general shape of the actual forces. However, there were some discrepancies between the predicted and measured forces. These differences were attributed to internal microstructure defects, density gradients, and the use of a shear plane model in force prediction that was not entirely appropriate for brittle materials such as CPP. The present study successfully developed 3DP and CNC fabrication methods for manufacturing anatomically-shaped CPP substrates. Future studies were recommended to explore further optimization of these fabrication methods and to demonstrate the utility of accurate substrates shapes to the clinical application of focal defect repair implants.

The purpose of the present study is to develop techniques for manufacturing anatomically-shaped substrates of implants made from calcium polyphosphate (CPP) ceramic. These substrates have tissue-engineered cartilage growing on their top surfaces and can be used as implants for osteochondral focal defect repair. While many research groups have been fabricating such substrates using standard material shapes, e.g., rectangles and circular discs, it is considered beneficial to develop methods that can be integrated in the substrate fabrication process to produce an implant that is specific to a patient’s own anatomy (as obtained from computer tomography data) to avoid uneven and/or elevated stress distribution that can affect the survival of cartilage. The custom-made, porous CPP substrates were fabricated with three-dimensional printing (3DP) and computer numerically controlled (CNC) machining for the first time to the best of the author’s knowledge. The 3DP technique was employed in two routines: indirect- and direct-3DP. In the former, 3DP was used to fabricate molds for pre-shaping of the CPP substrates from two different powder size ranges (<75 μm and 106-150 μm). In the latter, CPP substrates were produced directly from the retrofitted 3DP apparatus in a layer-by-layer fashion from 45-75 μm CPP powder with a polymeric binder. The prototyped samples were then sintered to obtain the required porosity and mechanical properties. These substrates were characterized in terms of their dimensional shrinkage and density. Also, SEM images were used to assess the particle distribution and neck and bond formations. The substrates produced using the indirect-3DP method yielded densities (<75 μm: 66.28 ± 11.62% and 106-150 μm: 65.87 ± 6.12%), which were comparable to the substrates used currently and with some success in animal studies. Geometric adjustment factors were devised to compensate for the slight expansion inherent in the 3DP mold fabricating process. These equations were used to bring the plaster molds into true dimension. The direct-3DP method has proven to be the ultimate choice due to its ability to produce complex anatomically-shaped substrates without the use of a chemical solvent. In addition, it allows for precise control of both pore size and internal architectures of the substrates. Thus, the direct-3DP was considered to be superior than the indirect-3DP as a fabrication method. In the alternative CNC machining approach to fabrication, the ability to machine the CPP ceramic was feasible and by careful selection of the machining conditions, anatomically-shaped CPP substrates were produced. To develop strategies for optimizing the machining process, a mechanistic model was developed based on curve fitting the average cutting forces to determine the cutting coefficients for CPP. These cutting coefficients were functions of workpiece material, axial depth of cut, chip width, and cutter geometry. To explore the utility of this modelling approach, cutting forces were predicted for a helical ball-end mill and compared with experimental results. The cutting force simulation exhibits good agreement in predicting the fundamental force magnitude and general shape of the actual forces. However, there were some discrepancies between the predicted and measured forces. These differences were attributed to internal microstructure defects, density gradients, and the use of a shear plane model in force prediction that was not entirely appropriate for brittle materials such as CPP. The present study successfully developed 3DP and CNC fabrication methods for manufacturing anatomically-shaped CPP substrates. Future studies were recommended to explore further optimization of these fabrication methods and to demonstrate the utility of accurate substrates shapes to the clinical application of focal defect repair implants.

Industrial demands for higher productivity rates and more stringent part tolerances require faster production machines that can produce, assemble, or manipulate parts at higher speeds and with better accuracy than ever before. In a majority of production machines, such as machine tools, ball screw drives are used as the primary motion delivery mechanism due to their reasonably high accuracy, high mechanical stiffness, and low cost. This brings the motivation for the research in this thesis, which has been to develop new control techniques that can achieve high bandwidths near the structural frequencies of ball screw drives, and also compensate for various imperfections in their motion delivery, so that better tool positioning accuracy can be achieved at high speeds. A precision ball screw drive has been designed and built for this study. Detailed dynamic modeling and identification has been performed, considering rigid body dynamics, nonlinear friction, torque ripples, axial and torsional vibrations, lead errors, and elastic deformations. Adaptive Sliding Mode Controller (ASMC) is designed based on the rigid body dynamics and notch filters are used to attenuate the effect of structural resonances. Feedforward friction compensation is also added to improve the tracking accuracy at velocity reversals. A bandwidth of 223 Hz was achieved while controlling the rotational motion of the ball screw, leading to a servo error equivalent to 1.6 um of translational motion. The motor and mechanical torque ripples were also modeled and compensated in the control law. This improved the motion smoothness and accuracy, especially at low speeds and low control bandwidths. The performance improvement was also noticeable when higher speeds and control bandwidths were used. By adding on the torque ripple compensation, the rotational tracking accuracy was improved to 0.95 um while executing feed motions with 1 m/sec velocity and 1 g acceleration. As one of the main contributions in this thesis, the dynamics of the 1st axial mode (at 132 Hz) were actively compensated using ASMC, which resulted in a command tracking bandwidth of 208 Hz. The mode compensating ASMC (MC-ASMC) was also shown to improve the dynamic stiffness of the drive system, around the axial resonance, by injecting additional damping at this mode. After compensating for the lead errors as well, a translational tracking accuracy of 2.6 um was realized while executing 1 m/sec feed motions with 0.5 g acceleration transients. In terms of bandwidth, speed, and accuracy, these results surpass the performance of most ball screw driven machine tools by 4-5 times. As the second main contribution in this thesis, the elastic deformations (ED) of the ball screw drive were modeled and compensated using a robust strategy. The robustness originates from using the real-time feedback control signal to monitor the effect of any potential perturbations on the load side, such as mass variations or cutting forces, which can lead to additional elastic deformations. In experimental results, it is shown that this compensation scheme can accurately estimate and correct for the elastic deformation, even when there is 130% variation in the translating table mass. The ED compensation strategy has resulted in 4.1 um of translational accuracy while executing at 1 m/sec feed motion with 0.5 g acceleration transients, without using a linear encoder. This result is especially significant for low-cost CNC (Computer Numerically Controlled) machine tools that have only rotary encoders on their motors. Such machines can benefit from the significant accuracy improvement provided by this compensation scheme, without the need for an additional linear encoder.

Plastic  deformation of tubes can be achieved in numerous ways. One of the most useful type is CNC tube bending machines which is used in many industries such as aerospace, automotive, HVAC systems and so on. It is important that all components of system should mate properly after producing and because of this bend shaping requires sensitive operation on each components to ensure regularity of production processes with high quality end-product. Thus, the CNC tube bending industry to become widespread. However it brings some troubleshooting like wrinkling, springback, breakage and ovalisation. This failures depends on geometry of the material such as bending radius, tube thickness and also friction factor between dies and the tube. Effects of all parameters should be examined before generating the theory for a best solution. Therefore, prediction of the required moment for the proper bending process with low cost and shortened production time is needed. All of these requirements can be achieved through a C++ form application program.

Industrial demands for higher productivity rates and more stringent part tolerances require faster production machines that can produce, assemble, or manipulate parts at higher speeds and with better accuracy than ever before. In a majority of production machines, such as machine tools, ball screw drives are used as the primary motion delivery mechanism due to their reasonably high accuracy, high mechanical stiffness, and low cost. This brings the motivation for the research in this thesis, which has been to develop new control techniques that can achieve high bandwidths near the structural frequencies of ball screw drives, and also compensate for various imperfections in their motion delivery, so that better tool positioning accuracy can be achieved at high speeds. A precision ball screw drive has been designed and built for this study. Detailed dynamic modeling and identification has been performed, considering rigid body dynamics, nonlinear friction, torque ripples, axial and torsional vibrations, lead errors, and elastic deformations. Adaptive Sliding Mode Controller (ASMC) is designed based on the rigid body dynamics and notch filters are used to attenuate the effect of structural resonances. Feedforward friction compensation is also added to improve the tracking accuracy at velocity reversals. A bandwidth of 223 Hz was achieved while controlling the rotational motion of the ball screw, leading to a servo error equivalent to 1.6 um of translational motion. The motor and mechanical torque ripples were also modeled and compensated in the control law. This improved the motion smoothness and accuracy, especially at low speeds and low control bandwidths. The performance improvement was also noticeable when higher speeds and control bandwidths were used. By adding on the torque ripple compensation, the rotational tracking accuracy was improved to 0.95 um while executing feed motions with 1 m/sec velocity and 1 g acceleration. As one of the main contributions in this thesis, the dynamics of the 1st axial mode (at 132 Hz) were actively compensated using ASMC, which resulted in a command tracking bandwidth of 208 Hz. The mode compensating ASMC (MC-ASMC) was also shown to improve the dynamic stiffness of the drive system, around the axial resonance, by injecting additional damping at this mode. After compensating for the lead errors as well, a translational tracking accuracy of 2.6 um was realized while executing 1 m/sec feed motions with 0.5 g acceleration transients. In terms of bandwidth, speed, and accuracy, these results surpass the performance of most ball screw driven machine tools by 4-5 times. As the second main contribution in this thesis, the elastic deformations (ED) of the ball screw drive were modeled and compensated using a robust strategy. The robustness originates from using the real-time feedback control signal to monitor the effect of any potential perturbations on the load side, such as mass variations or cutting forces, which can lead to additional elastic deformations. In experimental results, it is shown that this compensation scheme can accurately estimate and correct for the elastic deformation, even when there is 130% variation in the translating table mass. The ED compensation strategy has resulted in 4.1 um of translational accuracy while executing at 1 m/sec feed motion with 0.5 g acceleration transients, without using a linear encoder. This result is especially significant for low-cost CNC (Computer Numerically Controlled) machine tools that have only rotary encoders on their motors. Such machines can benefit from the significant accuracy improvement provided by this compensation scheme, without the need for an additional linear encoder.

A tool path generation method for sculptured surfaces defined by triangular meshes is presented in this thesis along with an algorithm that helps determine the best type of cutter geometry to machine a specific surface. Existing tool path planning methods for sculptured surfaces defined by triangular meshes require extensive computer processing power and result in long processing times mainly since surface topology for triangular meshes is not provided. The method presented in this thesis avoids this problem by offsetting each triangular facet individually. The combination of all the individual offsets make up a cutter location surface. A single triangle offsetting results in many more triangles; many of these are redundant, increasing the time required for data handling in subsequent steps. To avoid the large number of triangles, the proposed method creates a bounding space to which the offset surface is limited. The original surface mesh describes the bounding surface of a solid, thus it is continuous with no gaps. Therefore, the resulting bounding spaces are also continuous and without gaps. Applying the boundary space limits the size of the offset surface resulting in a reduction in the number of triangular surfaces generated. The offset surface generation may result in unwanted intersecting triangles. The tool path planning strategy addresses this issue by applying hidden-surface removal algorithms. The cutter locations from the offset surface are obtained using the depth buffer. The simulation and machining results show that the tool paths generated by this process are correct. Furthermore, the time required to generate tool paths is less than the time required by other methods. The second part of this thesis presents a method for selecting an optimal cutter type. Extensive research has been carried out to determine the best cutter size for a given machining operation. However, cutter type selection has not been studied in-depth. This work presents a method for selecting the best cutter type based on the amount of material removed. By comparing the amount of material removed by two cutters at a given cutter location the best cutter can be selected. The results show that the optimal cutter is highly dependent on the surface geometry. For most complex surfaces it was found that a combination of cutters provides the best results.

Werkstattgerechte Nutzerunterstützung bei der Freiformflächenbearbeitung Die Bearbeitung von Freiformflächen ist vor allem im Modell- und Formenbau dadurch gekennzeichnet, daß die gefertigten Teile Unikate sind und in der Regel sehr komplizierte Oberflächengeometrien aufweisen. Sowohl die Bearbeitungszeit als auch die Verantwortung der Werker an den automatisierten Bearbeitungsmaschinen ist sehr groß. Trotz dieser Besonderheiten unterscheidet sich die Arbeitsorganisation nicht von der Fertigung größerer Stückzahlen. Im Rahmen des Verbundvorhabens &quot; Werkstattgerechte Nutzerunterstützung bei der Freiformflächenbearbeitung&quot; werden die bestehende Arbeitsorganisation zwischen Arbeitsvorbereitung und Werkstatt untersucht und Vorschläge für eine Vervollkommnung der Organisationsformen, der Benutzungsoberflächen sowie für Eingriffsmöglichkeiten der Werker in den automatisierten Prozeßablauf erarbeitet, die die stärkere Einbeziehung und Nutzung des Erfahrungswissens der Facharbeiter zu Ziel haben. Dank der Förderung durch das Bundesministerium für Bildung, Wissenschaft und Techno-logie unter der Projektträgerschaft Arbeit &amp; Technik war es möglich, dieses Forschungs-Verbundvorhaben erfolgreich zu bearbeiten. Die großen Resonanzen aus der Industrie bestätigten auf drei Workshops die Wichtigkeit des Anliegens und die Qualität der erzielten Ergebnisse. Dem Forschungsverbund gehörten nachfolgende wissenschaftliche Einrichtungen und Industrieunternehmen mit den genannten Bearbeitern an: • Technische Universität Dresden, Institut für Arbeitsingenieurwesen - AIW (Projektleitung und Koordination) – für alle Universitären Partner Prof. Dr.-Ing. habil. E. Kruppe (Projektleiter), Dr.-Ing. A. Becherer, Dr.-Ing. V. Bormann • Technische Universität Dresden, Institut für Produktionstechnik Lehrstuhl Produktionsautomatisierung / Steuerungstechnik – PAS Prof. Dr.-Ing. habil. D. Fichtner, Dipl.-Ing. U. Carlsen, Dipl.-Ing. Ch. Rehm • Universität Dortmund, Institut für Spanende Fertigung – ISF Prof. Dr.-Ing. K. Weinert, Dipl.-Inf. J. Friedhoff, Dipl.-Ing. G. Guntermann, Dipl.-Ing. A. Enselmann • Universität Stuttgart, Institut für Steuerungstechnik der Werkzeugmaschinen und Fertigungseinrichtungen – ISW Prof. Dr.-Ing. A. Storr, Dr.-Ing. C. Itterheim, Dipl.-Ing. H. J. Stöhle • andron GmbH, Wasserburg/Bodensee (Steuerungshersteller) Dipl.-Ing. W. J. Blümlein, Dipl.-Ing. W. Natterer • GIB-Gesellschaft für Industrieberatung Dresden mbH (Softwareentwickler) Dipl.-Ing. F. Adam, Dipl.-Ing. I. Lopez, Dipl.-Ing. P. Flehmig • MIKROMAT Werkzeugmaschinen GmbH &amp; Co. KG Dresden (Maschinenhersteller) Dipl.-Ing. M. Hoch, Dipl.-Ing. A. Kretzschmar • Modellbau Schönheide GmbH (Maschinenanwender für die Freiformflächenbearbeitung) Dipl.-Ing. H. Ott, Dipl.-Ing. R. Gierschick. / Workshop-adequate User Assistance for Processing of Sculptured Surfaces Especially in model and pattern making the processing of sculptured surfaces is characterized by the fact that the parts produced are unique specimens, which are very complex, as a rule. The process time as well as the high qualified workers responsibility is very high. In spite of these peculiarities, the work organization does not differ from that of the manufacturing of larger numbers of pieces. Within the framework of the project &quot;Workshop-adequate User Assistance for the Processing of Sculptured Surfaces&quot; the existing work organization between the preparation for work and the workshop is investigated and pro-posals for perfection of organization, using surfaces and possibilities of worker controlled process influences have been developed to support the better utilization and integration of the workers' empirical knowledge.