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V olumetric  C ompensation  S ystem ( VCS )   for 5 AXES VERTICAL GANTRY MACHINE WITH MOBILE BRIDGE
What is VCS System VCS  is a system to compensate at the tool tip the Geometric and Dynamic machine’s errors in the total ...
Standard Compensation (CEC) <ul><li>In a cartesian 3 axis machine: </li></ul><ul><li>The standard compensation (CEC) compe...
VCS compensation <ul><li>In a cartesian 3 axis machine: </li></ul><ul><li>The VCS compensation  compensate also the 3 squa...
Resulting Errors at the Tool Center Point (TCP) of a 3-Axes Machinetool  <ul><li>Machine Geometric errors </li></ul><ul><l...
ADDITIONAL GEOMETRIC ERRORS IN 5-AXIS MACHINETOOL Tool with orientation Overlap of  positioning  and  orientation error  o...
VOLUMETRIC COMPENSATION SYSTEM - FIELD of APPLICATION VCS compensates the  resulting geometric error at the TCP  for 3- an...
HOW to USE VCS  SYSTEM Step 1 Measure with laser interferometer and Ballbar system the geometric and positioning machine’s...
Step 2 VCS File From the geometric errors  measured,  the Renishaw Software directly generate the data file in VCS format ...
VCS Compile Cycle installed Activate Sinumerik VCS functionality to compensate for the geometric machine error VCS file Me...
Verification of  VCS Improvement by Diagonal Measurament HOW VCS SYSTEM WORKS Step 4 4 3 2 1 Y Z X
Qualitative Example of Volumetric errors before VCS activation
Qualitative Example of Volumetric errors with VCS compensation
DAILY VCS UTILISATION During the daily working operations VCS System taking the feedback from the machine, evaluate for ea...
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Vcs Breton 2009

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With VCS machine tool precision can be increased

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Vcs Breton 2009

  1. 1. V olumetric C ompensation S ystem ( VCS ) for 5 AXES VERTICAL GANTRY MACHINE WITH MOBILE BRIDGE
  2. 2. What is VCS System VCS is a system to compensate at the tool tip the Geometric and Dynamic machine’s errors in the total machine’s working volume. <ul><li>Machine Geometric and Kinematics Model </li></ul><ul><li>Machine Geometry Standard Compensation (CEC) </li></ul><ul><li>Leadscrew/pitch error and measuring system error compensation </li></ul><ul><li>Space error compensation </li></ul><ul><li>Backlash compensation </li></ul><ul><li>Following error compensation (dynamic feed forward control ) </li></ul><ul><li>Friction compensation </li></ul>The VCS system input data are:
  3. 3. Standard Compensation (CEC) <ul><li>In a cartesian 3 axis machine: </li></ul><ul><li>The standard compensation (CEC) compensate 6 geometrics errors for each axis in total 18 errors </li></ul><ul><li>For each linear axis X , Y and Z in total 6 geometric errors can appear (T: Translatory R: Rotatory) : </li></ul><ul><ul><li>Positioning error XTX YTY ZTZ </li></ul></ul><ul><ul><li>Straightness error XTY XTZ YTX YTZ ZTX ZTY </li></ul></ul><ul><ul><li>Yaw XRZ YRZ ZRX </li></ul></ul><ul><ul><li>Pitch XRY YRX ZRY </li></ul></ul><ul><ul><li>Roll XRX YRY ZRZ </li></ul></ul><ul><li>For 3 linear axes this means 18 error sources in total. </li></ul>
  4. 4. VCS compensation <ul><li>In a cartesian 3 axis machine: </li></ul><ul><li>The VCS compensation compensate also the 3 squareness errors than </li></ul><ul><li>in total 21 errors </li></ul><ul><li>Additionally the 3 squareness errors of the linear axes must be taken into account: </li></ul><ul><ul><li>x  y XWY </li></ul></ul><ul><ul><li>x  z XWZ </li></ul></ul><ul><ul><li>y  z YWZ </li></ul></ul><ul><li>In total 21 geometric errors have to be handeled for a 3-axes machine tool. </li></ul>The Siemens VCS Compile Cycle for Sinumerik 840 D takes into account all these 21 geometric errors for compensation, to compensate the machine at the tool tip in the total working volume
  5. 5. Resulting Errors at the Tool Center Point (TCP) of a 3-Axes Machinetool <ul><li>Machine Geometric errors </li></ul><ul><li>positioning error </li></ul><ul><li>straightness </li></ul><ul><li>roll </li></ul><ul><li>yaw </li></ul><ul><li>pitch </li></ul><ul><li>squareness </li></ul><ul><li>Resulting error at TCP </li></ul><ul><li>positioning error </li></ul><ul><li>orientation error </li></ul>The geometric errors of a 3-axes machine tool induce a displacement of the tool both in position and orientation Programmed tool position and tool orientation Real tool orientation Real TCP position
  6. 6. ADDITIONAL GEOMETRIC ERRORS IN 5-AXIS MACHINETOOL Tool with orientation Overlap of positioning and orientation error of the tool caused by linear axis (3-axes kinematics) and rotary axes (rotary head) <ul><li>Additional Head Geometric errors: </li></ul><ul><li>Positioning error (P A , P C ) </li></ul><ul><li>Offset error </li></ul><ul><li>Orientation vector </li></ul><ul><li>Ō A = (O Ax , O Ay , O Az ) </li></ul><ul><li>Orientation vector </li></ul><ul><li>Ō C = (O Cx , O Cy , O Cz ) </li></ul>P A P A <ul><li>Additional error of rotary axes at TCP: </li></ul><ul><li>positioning error </li></ul><ul><li>orientation error </li></ul>Ideal Real O A O C P C
  7. 7. VOLUMETRIC COMPENSATION SYSTEM - FIELD of APPLICATION VCS compensates the resulting geometric error at the TCP for 3- and 5-axes machine tools with cartesian axes configuration 3 axes machine tools VCS-3AX Linear cartesian axes X, Y, Z (including gantry axis) No Compensation of displacement in tool orientation Compensation of Tool Tip Position VCS-5AX 5 axes machine tools Linear cartesian axes X, Y, Z (including gantry axis) Compensation of Tool Tip Position (including activate transformation) <ul><li>Compensation of displacement in tool orientation: </li></ul><ul><li>caused by the rotary axes themselves </li></ul><ul><li>(for all 5- axes configurations) </li></ul><ul><li>additionally </li></ul><ul><li>caused by the linear axes </li></ul><ul><li>(for fork heads only) </li></ul>
  8. 8. HOW to USE VCS SYSTEM Step 1 Measure with laser interferometer and Ballbar system the geometric and positioning machine’s errors <ul><li>3 axis linear positioning errors </li></ul><ul><li>3 axis straightness errors </li></ul><ul><li>3 axis Roll, Pitch and Yaw angular errors </li></ul><ul><li>3 axis squareness errors </li></ul><ul><li>A and C fork head errors </li></ul>
  9. 9. Step 2 VCS File From the geometric errors measured, the Renishaw Software directly generate the data file in VCS format to introduce in the Siemens 840D Control HOW to USE VCS SYSTEM // VCS-Format //----------- // [HEADER] MACHINE_PRODUCER = BRETON MACHINE_TYPE = FLYMILL 2T MACHINE_NUMBER = 0 CONTROL_PRODUCER = SIEMENS CONTROL_TYPE = 840D CONTROL_NUMBER = 0 CONTROL_SOFTWARE_VERSION = 6.5.39 CUSTOMER = RENISHAW OPERATOR = REICHLE DATE = 080129 TEMPERATURE = 23 COMMENT = komplett YTY] AXIS_LENGTH [L_U] = 2000 INTERVAL [L_U] = 200 REF_POS_X [L_U] = 1233 REF_POS_Z [L_U] = -683.5 MEAS_TOOL_Y [L_U] = 170 MEAS_TOOL_Z [L_U] = 110 DEVIATION [D_U] GRIDPOINTS = { 0.0 -1.9 200.0 -2.4 400.0 -4.15 600.0 -5 800.0 -6.9 1000.0 -9 1200.0 -8.4
  10. 10. VCS Compile Cycle installed Activate Sinumerik VCS functionality to compensate for the geometric machine error VCS file Measurements Step 3 CNC CNC Machine model HOW VCS SYSTEM WORKS
  11. 11. Verification of VCS Improvement by Diagonal Measurament HOW VCS SYSTEM WORKS Step 4 4 3 2 1 Y Z X
  12. 12. Qualitative Example of Volumetric errors before VCS activation
  13. 13. Qualitative Example of Volumetric errors with VCS compensation
  14. 14. DAILY VCS UTILISATION During the daily working operations VCS System taking the feedback from the machine, evaluate for each point of the trajectory the compensation to introduce, to have at the tool tip the maximum positioning and orientation precision. The VCS System don’t compensate the temperature variation errors. To have the maximum precision from VCS System the machine must be calibrated at least once in each season With Renishaw calibration system the calibration time is very reduced VCS system can’t be intended as a substitute fro a good mechanical design and build.

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