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Static and dynamic testing of machine tools

MTTRF Annual Meeting 2010

7th -8th June

Thomas Liebrich1, Michael Gebhardt2, Stefan Thoma1, Hop Nguyen2, SaschaWeikert2, Wolfgang Knapp1, Konrad Wegener1

1Institute for Machine Tools and Manufacturing (IWF), Swiss Federal Institute of Technology (ETH), Zurich, Switzerland

2inspire AG for Mechatronic Systems and Manufacturing Technology, Zurich, Switzerland

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1 Introduction2 Static Measurements3 Dynamic Measurements4 Preparation for Test Piece Machining5 Future Steps6 Conclusions

Overview

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IWF/inspire research on 5-axis machine tools- geometric testing- compensation- dynamic testing- thermal testing

since begin of 2010 new5-axis machining center- with swiveling rotary

table- vertical machining center

t-(C)-Z-X-Y-b-B-C-w

Introduction

X

Z Y

4

for testing X, Y, Z axes, ball plate on 0 / 80 / 160 / 240 / 320 mm height (Z direction)3D probe system, U (ball plate, spacers, probe, k=2) = 3.2 µm

Static measurements, 3D ball plate

X

Z Y

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results, volumetric accuracy, T = 22 °CVXYZ,X = 11 µm, range of errors in X directionVXYZ,Y = 17 µmVXYZ,Z = 12 µm

Static measurements , 3D ball plate

-100 0 100 200 300 400 500 0 200 400-200

-100

0

100

200

300

400

Y [mm]

Measuring results 3D- ball plate, magnification 3000x

X [mm]

Z [m

m]

-100 0 100 200 300 400 500-200

-100

0

100

200

300

400

Measuring results 3D- ball plate, magnification 3000x

Y [mm]

Z [m

m]

YX view

ZY view

-100 0 100 200 300 400 500-100

0

100

200

300

400

500

Measuring results 3D- ball plate, magnification 3000x

X [mm]

Y [m

m]

6

component errors, straightness error motions

EXY, EZY < 5 µm

straightness error motions of X, EYX, EZX < 2 µmred: Y0/Z0 blue: Y0/Z320green: Y500/Z0 cyan: Y500/Z320

EXZ, EYZ < 6 µm

Static measurements , 3D ball plate

0 50 100 150 200 250 300 350 400 450 500-1

-0.5

0

0.5

1

1.5Straightness deviation of X-axis

EY

X [ μm

]

0 50 100 150 200 250 300 350 400 450 500-2

-1

0

1

2

Position X-axis [mm]

EZX

[ μm

]

0 50 100 150 200 250 300 350 400 450 500-2

-1

0

1

2Straightness deviation of Y-axis

EX

Y [ μm

]

0 50 100 150 200 250 300 350 400 450 500-4

-2

0

2

4

Position Y-axis [mm]

EZY

[ μm

]

0 50 100 150 200 250 300 350-4

-2

0

2

4Straightness deviation of Z-axis

EX

Z [ μ

m]

0 50 100 150 200 250 300 350-4

-2

0

2

4

Position Z-axis [mm]

EY

Z [ μ

m]

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component errors, positioning error motions

EXX < 3 µm

positioning error motion of Y, EYYEYY = 6 µm, on the table, X = 0EYY = 4 µm, on the table, X = 500EYY = 13 µm, 320 above table, X = 0EYY = 16 µm, 320 above table, X = 500EYY = 3 µm, acceptance test EZZ < 18 µm

Static measurements , 3D ball plate

0 50 100 150 200 250 300 350 400 450 500-3

-2

-1

0

1

2

3Positional deviation of X-axis

Position X-axis [mm]

Pos

ition

al d

evia

tion

EX

X [ μ

m]

0 50 100 150 200 250 300 350-20

-15

-10

-5

0

5Positional deviation of Z-axis

Position Z-axis [mm]

Pos

ition

al d

evia

tion

EZZ

[ μm

]

0 100 200 300 400 500-20

-15

-10

-5

0

5

10

Position Y-axis [mm]

Positio

nal devia

tion E

YY

[µm

]

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squareness error C0Y (squareness between X and Y)

C0Y on table +10 to +19 µm/m C0Y 320 mm above table ±2 µm/m

Static measurements , 3D ball plate

-100 0 100 200 300 400 500 600-100

0

100

200

300

400

500

Reference X-axis [mm]

Y-a

xis

[m

m]

8.3µm

-100 0 100 200 300 400 500 600-100

0

100

200

300

400

500

Reference X-axis [mm]Y

-axis

[m

m]

8.3µm

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Static measurements , R-Test

R-Test set-upprecision sphere in spindle3D probe system on rotary table

X

ZY

10

Static measurements , R-Test

150200250 Y-Axis [mm]

C axis axial component

GXYC (axial) = 5 µm

circular deviation, moved axes X, Y, Cevaluation in axial direction (// C)

-200 -100 0 100 200

-200

-100

0

100

200

X-Axis [mm]

Y-Ax

is [m

m]

10μm

-300-200

-1000

100200

-300-200

-1000

100200

300-3

-2

-1

0

1

2

3

X-Axis [mm]Y-Axis [mm]

Z-C

ompo

nent

[μm

]

vertical straightness error of X,Yaxial and tilt error of C

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Static measurements , R-Test

150200250 Y-Axis [mm]

C axis radial component

GXYC (radial) = 6 µmpeaks at reversal points < 2 µm

-200 -100 0 100 200

-200

-100

0

100

200

X-Axis [mm]

Y-Ax

is [m

m]

10μm

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Static measurements , R-Test

150200250 Y-Axis [mm]

C axis radial component

GXYC (radial) = 6 µmpeaks at reversal points < 2 µm

positions and orientations (position and orientation of least squares circle)

X0C=+3.6 µm Y0C= 9 µm A0C=+14 µm/m B0C=+5.1 µm/mX0B=-1.7 µm Z0B=+12 µm A0B=-40 µm/m C0B=-37 µm/m

correction of machine tool model in numerical control

-200 -100 0 100 200

-200

-100

0

100

200

X-Axis [mm]

Y-Ax

is [m

m]

10μm

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Static measurements , R-Test

150200250 Y-Axis [mm]

C axis tangential component

GXYC (tangential) = 12 µmtangential vibration of 5 µm

-200 -100 0 100 200

-200

-100

0

100

200

X-Axis [mm]Y-

Axis

[mm

]

20μm

150200250 Y-Axis [mm]

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Static measurements , R-Test

150200250 Y-Axis [mm]

C axis tangential component

GXYC (tangential) = 12 µmtangential vibration of 5 µm

drift of 1.2 µm during 250 s2kHz sampling rate

-200 -100 0 100 200

-200

-100

0

100

200

X-Axis [mm]Y-

Axis

[mm

]

20μm0 50 100 150 200 250 300-1

01

Dev

. [μm

]

XYZ

80 81 82 83 84 85-0.5

00.5

1

Time [s]

Dev

. [μ m

]

150200250 Y-Axis [mm]

ECC = 25 µm/m amplitudeB radial = 5 µmB tangential = 6 µm B axial = 17 µm

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principle

Cross Talk

center of gravity

rolling elements of guideway

driving force

Z

Y

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principle

Cross Talk

driving force

center of gravity

rolling elements of guideway

cross talk

Z

Y

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Dynamic measurements, X straightness error of Y

step Y 4mm, F=100 mm/min (programmed), < 0.5 µm (start/stop excluded)

-3 -2 -1 0 1 2 3-0.6

-0.4

-0.2

0

0.2

0.4

0.6

Y travel [mm]

X d

evia

tion

[ μm

]

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Dynamic measurements, X cross talk of Y

step Y 4mm, F=6000 mm/min (programmed), amax = 0.4 m/s2, < 1.0 µm

-3 -2 -1 0 1 2 3-0.6

-0.4

-0.2

0

0.2

0.4

Y travel [mm]

X d

evia

tion

[μm

]

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Dynamic measurements, Z cross talk of Y

step Y 4mm, F=6000 mm/min (programmed), amax = 0.4 m/s2, < 1.2 µm

-3 -2 -1 0 1 2 3-0.5

0

0.5

1

Y travel [mm]

Z de

viat

ion

[μm

]

20

Dynamic measurements, Z cross talk of Y

step Y 4mm, F=6000 mm/min (programmed), amax = 0.4 m/s2, < 1.2 µmrepeatability < 0.1 µm

-3 -2 -1 0 1 2 3-0.5

0

0.5

1

Y travel [mm]

Z de

viat

ion

[μm

]

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Dynamic measurements, cross talk

another machining centre, same size200 mm movement

F 100 mm/min,Z straightness of Y < 2 µm

F 2000 mm/min,Z cross talk of Y < 20 µm

concept DCG,Drive in Center of Gravity,not applied

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inclined cone frustrum test piece

test piece designsurface machined with 5 axis simultaneous movement

Test piece for 5-axis machining

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inclined cone frustrum test piece

test piece design movements of linear axes

Test piece for 5-axis machining

-200

0

200-200

0

200

0

100

200

300

y

frame 4: machine coordinate systemphi = 0, C = 0°, B = -15°

α = 45°, β =30°, rA = 129.8

Min2 = [-149.8, 0, 296.034]Ain2 = [-129.8, 0, 330.675]

XM: [-39.79:353], YM: [-129.8:129.8], ZM: [-96.36:296.4]X180 = 353.0017, 2r = 80, Δ X = 392.8, Δ Y = 259.6, Δ Z = 392.8

x

z

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inclined conical test piece, movements of axesdistance to C 150 mmdistance to B 300 mm

Test piece for 5-axis machining

395.8Z – direction260.0Y – direction395.8X – direction

Total movement [mm]

400

200

0

-200

X [

mm

]

200100

0

400

200

0

-200

Z [

mm

]

400

200100

0

C [

°]

300

-50

-100

B [

°]

0

Y[m

m]

� �= 45°, = 30°, r = 130A

0 90 180 270 360

0 90 180 270 360

0 90 180 270 360

0 90 180 270 360

0 90 180 270 360

-100-200

Radial cone angle [°]�

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inclined conical test piece, movements of axesdistance to C 250 mmdistance to B 280 mmlarger movements of linear axes X, Y, Z

Test piece for 5-axis machining

504.2Z – direction460.0Y – direction505.7X – direction

Total movement [mm]

0 90 180 270 360

0 90 180 270 360

0 90 180 270 360

0 90 180 270 360

0 90 180 270 360

400200

0

-200

400

200

0

-200

Z [

mm

]

400

200100

0

C [

°]

300

-50

-100

B [

°]

0

Y[m

m]

-400

� �= 45°, = 30°, r = 230A

Radial cone angle [°]�

400

200

0

-200

X [

mm

]

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inclined conical test piece, movements of axesdistance to C 250 mmdistance to B 280 mmlarger movements of linear axes X, Y, Z

4 reversal points

Test piece for 5-axis machining

504.2Z – direction460.0Y – direction505.7X – direction

Total movement [mm]

0 90 180 270 360

0 90 180 270 360

0 90 180 270 360

0 90 180 270 360

0 90 180 270 360

400200

0

-200

400

200

0

-200

Z [

mm

]

400

200100

0

C [

°]

300

-50

-100

B [

°]

0

Y[m

m]

-400

� �= 45°, = 30°, r = 230A

Radial cone angle [°]�

400

200

0

-200

X [

mm

]

0 90 180 270 360

365

360

355

� �= 45°, = 30°, r = 230A

Radial cone angle [°]�

X [m

m]

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- simulation of machining with tolerances and measurement results of error motions

- manufacturing of test piece- test piece for identification of individual errors- comparison of simulation with machined part- bending of fixture for test piece machining, 1.3 µm for horizontal orientation for

1st version compensation

Future activities, test piece machining

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thermal influences, including rotary axes- drift tests- infrared camera, movement of rotary table axis C with 800 rpm

cold, table at 24°C

Future activities

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thermal influences, including rotary axes- drift tests- infrared camera, movement of rotary table axis C with 800 rpm

cold, table at 24°C after 240 min rotation, table at 27°C

Future activities

3°C, 200 mm excentricity radial deviation 6 µm

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machine tool used for demonstrations and practical exercises in the following

lectures:

manufacturing processes 1 and 2NC programming, milling

production machines 1 and 2design of machine tools, components of machine tools, machine tool performance, modeling of machine tools

quality of machine toolsgeometric and dynamic testing of machine tools, machine tool calibration

engineering tools course in CAMCAD-CAM coupling, machine tool as application example

master and bachelor projectsgeometric, dynamic, thermal measurements; calibration; simulation

Use of machine tool for education

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geometry very gooderror motions, errors in position and orientation are well within tight tolerancesvalues change significantly with position of measuring line

dynamic behavior very goodsmall cross talkconcept ‘Drive in Center of Gravity’, DCG

inclined cone frustrum test pieceoptimized position for large movements of linear axes on NMW 5000 DCGdia. of circular path 80 mm, distance to C of 150 mm, distance to B of 300 mm

future activitiessimulation and machining of 5-axis test piecesdynamic testingthermal testing including rotary axesenhancement of machine tools

Summary

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IWF/inspire thanks MTTRF for supporting research for 5-axis machining centers.

Acknowledgement

Thank you for your attention