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AMTS-RMS 13 Sep 09

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AMTS-RMS 13 Sep 09 Powered By Docstoc
					     Reconfigurable
  Manufacturing Systems
    Research at CSIR
          By Dr. Nkgatho S. Tlale, Mr. Ahmed
          Shaik and Miss. Dithoto Modungwa




Sponsored by the AMTS
and the CSIR
                Contents
1. Requirements of manufacturing environment
2. Flexible Manufacturing Systems
3. Reconfigurable Manufacturing System def.
4. Kinematically Reconfigurable RMT Principle
5. Conceptual Design of RMT for Reconditioning
   of Mould/Die Tool
6. Design Improvement
7. Kinematics and Dynamics Characterisation
8. Conclusion
       1. Requirements of
    manufacturing environment
•   Short product lead-time
•   More variation
•   Low, fluctuating volumes
•   Low price
•   Others
Different Manufacturing Systems
                       Medium pro,
        Transfer        medium
          lines                       Customi-
                      customisation
Product                                sation
         Mass
volume production      Flexible
                     Manufacturing
                       Systems

                                        Job
                                       shop

                   Product variety
     2. Flexible Manufacturing
              Systems
• At least 50 different terms for various
  types of flexibilities (Sethi A. K and Sethi
  S. P., 1990)
• Categories
  – Economic view of flexibility
  – Organisational view of flexibility
  – Manufacturing view of flexibility
•FMS increase process flexibility




      Example of FMS at Vought Aircraft (Source Groover M. P., 2008)
             Group Technology
• Increases machine flexibility




Part-family with
same manufacturing
attributes but
different design
attributes.


                         Manufacturing system layout
                         based on process layout.
Cellular layout using Group Technology (GT)
(Source Groover M. P., 2008)
System organisation and flexible
          resources



                          Flexible control
                                             Enterprise partnerships
                                                  Enterprises
      Flexible hardware


                                                    Factory
                                                  Shop floors
                                                      Cells
                                                   Machines
                 (Source: Bi Z. M., Lang Y. T, Shen W. and
                 Mang L., 2008)
   Basic        Manufacturing           Enterprise
Flexibilities      System               Flexibilities
                 Flexibilities
                                           Program
                  Process
Machine           Routing
Material          Product                 Production
handling
                  Volume
Operation
                 Expansion
                                             Market
  Mechatronics, ICT and advanced control
  Organisational structure and management
                      (Source: Sethi A. K. and Sethi S. P. 1990)
    Machine Level Flexibility
"The machine level provides the basic
  framework for flexibility. Software functions
  cannot help to provide any extra flexibility,
  if the machines are hard and expensive to
  change"

(Source: Ranta, 1989)
 Sources of Machine Flexibility
• Numerical control, easily accessible programs,
  rule-based languages,
• Sophisticated part-loading and tool-changing
  devices for work-pieces and tools
• Size of the tool magazine
• Availability of sufficient pallets and fixtures
• Number of axes
• Automatic chip removal
• Adaptive control to optimize metal removal
• Diagnostic software
• Integration with CAD/CAM
• etc.
   Material Handling Flexibility
• Ability to move different part types efficiently
  for proper positioning and processing through
  the manufacturing facility it serves
• Loading/unloading, transportation and
  storage
• Achieved by forklifts, conveyors, robots,
  automated guided vehicles (AGVs), etc.
• Increase availability of machines and
  utilisation, and reduces throughput times
         Operation Flexibility
• Refers to the ability of a part to be produced in
  different ways
• Process plan for the part (sequence of
  operations) obtained by either interchange or
  substitution of certain operations by others
• Alternate operations’ sequence or use of
  different operations
• Allows easy scheduling of parts in real time,
  increases machine utilisation and availability
           Process Flexibility
• It relates to the set of part types (part-
  families) that the system can produce without
  major setups
• Costs must be relatively stable over widely
  ranging product mixes
• Purpose: reduce batch sizes and reduce
  inventory costs
• It is derived from machine flexibility,
  operation flexibility of parts and flexibility of
  material handling system
3. Reconfigurable Manufacturing
          System def.
• “…is designed at the outset for rapid
  change in structure as well as in the
  hardware and software components”
  (Source: Koren et al, 2002)
• Research Areas:
  – Machine Tool Design Research
  – Manufacturing System Research
  – Fixture Assembly and Mounting Design
    Research
   Basic        Manufacturing    Enterprise
Flexibilities      System        Flexibilities
                 Flexibilities
                                   Program
                  Process
Machine           Routing
Material          Product         Production
handling
                  Volume
Operation
                 Expansion
                                     Market
  Mechatronics, ICT and advanced control
  Organisational structure and management
 Reconfigurable Manufacturing
           Systems
        Transfer            Medium pro,
          lines              medium     Customi-
                Reconfigu- customisation sation
Product    Mass rable
volume productionSystems Flexible
                         Manufacturing
                           Systems
                 Mass                     Job
             customisation               shop

                   Product variety
           RMT Research
• Modular design in hardware and software
• Modules allow re-configurability of machine
  tools as products features change
• By standardisation of modules, modules can
  be re-used as basic element in different
  machines
• Kinematically reconfigurable RMT
• Material removal processes
4. Kinematically Reconfigurable
        RMT Principle

   Robotics            Machine tool
  technology            technology
                PKM


                  RMT
               technology
RMT for Reconditioning of Mould
           and Dies
• Die cast and injection-moulded process
  require die and mould tools
• Mould and die tools are expensive to
  manufacture
• They wear and tear whilst being used
• To reduce costs and increase tool life, they
  can be repaired when worn-out
Examples of Mould/Die Failures
Manufacturing Processes for
Reconditioning of Mould/Die
           Tools
 1. Identification of defects
 2. Cleaning of mould/die tool
 3. Deposition of material (metal)
 4. Welding of material (TIG/laser)
 5. Rough machining and finishing to specs
 6. Polishing
 7. Heat treatment
       Specifications for RMT
Specification       Range                      Tolerance
Minimum 5 degrees   Axis X, Y & Z
  of movement       B- Rotation about Z
  freedom             axis, C- Rotation
                      about X axis
Axis X motion range 150 mm                     ± 0.01mm
Axis Y motion range 150 mm                     ± 0.01mm
Axis Z motion range 50 mm                      ± 0.01mm
B- Rotation about Z 360º                       ± 0.01mi
  axis
C- Rotation about X 60º total, 30º symmetric   ± 0.01min
  axis                about Z axis
Work piece Weight   50Kg
  on table
 Specifications for RMT, cont.
Specification     Range               Tolerance
Table clamping    250x250mm
area
Milling spindle   0 - 10 000RPM, 4 K W Max. Torque
                  Power Chuck Nr 30    = 60N.m
Feed speed in X , 1 meter/ minute
Y&Z
Position          0.01mm
measuring
resolution
Working Height    200mm

Operating         0-100ºC
temperature
5. Conceptual Design of RMT for
Reconditioning of Mould/Die Tool
• Synthesis achieved by study of parallel
  kinematics manipulators (PKMs) and serial
  robots
• Two novel designs of staged or staggered 6
  DOF manipulators achieved. Capable of 6
  DOF of a typical serial robot, but with all
  motors fixed at the base, and rigid link
  actuation transfer (no cables), with a
  machine footprint of a serial robot.
• This places all the dead mass of the
  machine at the base, in turn making the
  machine moving mass lighter. It thus
  increases payload carrying ability and
  machine stiffness. Exotic materials can be
  used to reduce the mass of the machines
  links making it even faster and stiffer.

• 6 DOF → 3 DOFs Translation + 3 DOFs
  Orientation
• The design uses parallelograms to transfer
  actuation. Old 4 DOF hybrid design – uses
  a combination of parallel and serial
  topologies. Cannot disclose new design.
• 3 DOFs Orientation – 2 Designs: linkage
  and geared. Linkage design is based on
  agile eye. Both designs have all 3
  actuating axes concentric.




                                   Agile eye



       and horizontal

               Perspex Model
• Geared design




                                Perspex Model




               and horizontal


• Issues – Linkage design: Restricted
  workspace, large footprint. Geared design:
  Backlash, not exactly a spherical wrist.
• The second design uses only spherical
  geometry and a staged or staggered
  arrangement as mentioned previously, to
  achieve the 6 DOFs – cannot disclose the
  entire design, but the spherical joints are
  illustrated.



                                         3 DOF




         2 DOF
        Measurement Equipment for the
           Reconditioning Process
• Faro Arm – Tactile 6 DOF sensor for acquiring point
  spatial coordinates
• Laser scanner – For acquiring continuous surface
  profiles
• Metris – 6 DOF spatial position sensor – uses cameras
  and LEDs (large volume, better than 0.1mm resolution)
      6. Design Improvement
• 5-axes sufficient to orient tool wrt to work-
  piece (but we can achieve 6 if necessary)
• Normal 5-axes milling machines: 2 rotational
  axes, 3 translational axes (slides)
• Two different kinematics chains: tool and
  work piece
• Choice of configuration of axes of a
  kinematics chain depends on application
• Rotary axes on the work-piece increase
  accessibility to work-piece, but reduce rigidity
   Design Improvement, cont.
• Heavy work-pieces require translational axes
  on work-piece kinematics chain
• Rotary axes on the tool kinematics chain
  increase kinematics reconfigurability, but
  decrease stiffness
• Novel use of translational axes, PKM with
  rotary axes
    7. Kinematics and Dynamics
          Characterisation
•   Workspace analysis
•   Static analysis: action-reaction forces
•   D-H kinematics analysis
•   Dynamics: Newton-Euler and Lagrangian
    methods
             8. Conclusion
• 1 PhD
• 1 MTech
• Collaboration with UKZN, TUT and Florida
  University.
• 2 Possible provisional patents (PCTs) (with
  variations in their design)
• Due to the PCTs no publications can be
  attempted until the intellectual property has been
  secured.

				
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