Automatic Straightening of Shafts

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Automatic Straightening of Shafts

• How to Improve Productivity and Product Quality
  through Straightening

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Why Straighten?

• Factors causing distortion in shafts
• Heat Treatment
• Stresses from manufacturing processes
• Material handling
• Typical parts requiring straightening
• Axle shafts
• Transmission shafts
• Engine components cams and cranks
• Steering components racks and pinions
• Motors and pump shafts

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Justifications for Straightening

• Material savings less stock allowance required
  for part to clean up
• Reduce costly machine operations like hard
  turning and grinding
• Improve final geometry of part
• More uniform case depth hardness
• Better gear geometry

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Straightening Process

• Determine the critical points to be straightened.
• Bearing Journals
• Gear Teeth
• Determine the base datum for measurement of
  straightness
• Centers
• OD of part
• Total Indicator Runout

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Measurement
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Angle
Goal 1. Determine the runout - TIR 2. If TIR
gt Tolerance Determine angle of highpoint 3.
Position the workpiece 4. Straighten 5. Measure
TIR
Workpiece with runout
½ TIR
Workpiece
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Angle -45 Degrees
Example 1. Runout TIR 0.2mm 2.
Tolerance 0.020mm 3. Angle -45 Degrees
Tolerance 0.020
Workpiece
TIR 0.2
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Angle -45 degrees
Process 1. Determine the runout - TIR -
Rotate through 360 Degrees 2. If TIR gt
Tolerance Determine angle 3. Position the
workpiece
TIR 0.020
Workpiece
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Tolerance 0.020
Workpiece
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Tolerance 0.020
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Tolerance 0.020
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Tolerance 0.020
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Angle 45 degrees

• Process
• If TIR gt Tolerance determine high point angle
• Position workpiece

Tolerance 0.020
Workpiece
TIR 0.2
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Process 3. Workpiece in position 4. Straighten
Angle 0 Degrees
Tolerance 0.020
TIR 0.2
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Process 4. Straighten 5. Static Measurement
gt Tolerance 6. Straighten
Tolerance 0.020
Static Measurement 0.08
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Process 5. Static measurement lt Tolerance 6.
TIR Measurement
Tolerance 0.020
Static Measurement lt Tolerance
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Process 6. TIR Measurement
Tolerance 0.020
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Process 6. TIR Measurement
Tolerance 0.020
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Process 6. TIR Measurement
Tolerance 0.020
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Goal attained 7. TIR Control 8. TIR lt
Tolerance
Tolerance 0.020
TIR 0.015
Part in Tolerance
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Factors affecting measurement of Straightness

• Geometry of the part
• Out of roundness
• Center hole accuracy
• Surface condition of the part
• Heat treat scale
• Parting lines from forging or casting

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Filtering Form Errors From TIR Measurement - FFT
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FFT Fast Fourier TransformationFiltering Form
Error
RLF
90
 
0
180
0
90
180
270
360 Degrees
 
270
1024 Measuring points/Revolution - Better
Calculation of TIR value - Precise High
Point-Positioning 0.35
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FFT Fast Fourier Transformation
 
Position
Highest Value
Precise High-Point Position 0.35
 
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FFT Fast Fourier TransformationFiltering
Form-Error
RLF
90
0
TIR
180
Tolerance
0
90
180
270
360Degrees
270
1024 Measuring Points/Revolution - Better
calculation of TIR value - Precise High-Point
Positioning 0.35
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CALCULATION OF STROKE LENGTH
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DAS Dynamic Adjustment of Stroke

• Straighten in one stroke
• Less stress on material
• Targeted stroke length without overbending the
  workpiece
• Reduction of cracks
• Shorter cycle times

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Stroke Calculation
Stroke

Initial Stroke
85
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Plastic Deformation
TIR mm
0.2
0.1
Stroke Init. Stroke(TIR)
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STRAIGHTENING STATION
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Straightening Station
Straightening Punch
Z1
Z2
Z3
Static Center
Dynamic Center
Straightening Anvil
Measuring Unit
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Straightening Station
Straightening Punch
1
Z1
Z2
Z3
X
2
Static Center
Dynamic Center
Straightening Anvil
Measuring Unit
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Straightening Station
Straightening Punch
2
Z1
Z2
Z3
1
3
Static Center
Dynamic Center
Straightening Anvil
Measuring Unit
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Straightening Station
Straightening Punch
3
Z1
Z2
Z3
2
Y
Static Center
Dynamic Center
Straightening Anvil
Measuring Unit
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Straightening Station
TRAVELING STRAIGHTENING PUNCH
Z1
Z2
Z3
Static Center
Dynamic Center
Straightening Anvil
Measuring Unit
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Straightening Station
TRAVELING STRAIGHTENING PUNCH
Z1
Z2
Z3
Static Center
Dynamic Center
Straightening Anvil
Measuring Unit
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CENTERS
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Centers

• Centers
• Stable Design
• Servo Motor Drive
• Vertical Floating
• Automatic Height Adjustment
• Backlashfree due to use of linear guiderails
  High Repeatability
• Control over Workpiece Slipping
• Centers / Female Centers
• No special centers Standard Morse Taper
• Unclamping device built in to centers

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Centers
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Centers
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Centers
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Centers
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Centers
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Center Height Adjustment
Adjustment from ? 25 to ? 35
? 30
Same distance with different workpiece
diameters No adjustment needed of measuring units
and walking beam conveyor
3
1
2
2
3

Steps
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Center Height Adjustment
Adjustment from ? 35 to ? 45
? 40
Same distance with different workpiece
diameters No adjustment needed of measuring units
and walking beam conveyor
3
1
2
1
3
Steps
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Centers Height Adjustment
Adjustment from ? 45 to ? 55
? 50
Same distance with different workpiece
diamters No adjustment needed of measuring units
and walking beam conveyor
3
1
2
1
2
Steps
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NEW CONCEPT
OLD
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NEW CONCEPT
OLD
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NEW CONCEPT
OLD
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STRAIGHTENING PROCESS Front View
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Straightening Process
Straightening Punch
Center
Str. Anvil
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Centers Advance
Straightening Punch
Center
Str. Anvil
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Centers Advance
Straightening Punch
Center
Str. Anvil
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Measure
Straightening Punch
Center
Str. Anvil
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Measure
Straightening Punch
Center
Str. Anvil
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Measure
Straightening Punch
Center
Str. Anvil
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Measure
Straightening Punch
Center
Str. Anvil
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Punch Advance
Straightening Punch
Center
Str. Anvil
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Straightening Stroke
Straightening Punch
Center
Str. Anvil
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Straightening Stroke
Straightening Punch
Center
Str. Anvil
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Straightening Stroke Target reached
Straightening Punch
Center
Str. Anvil
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Return to Measuring Position
Straightening Punch
Center
Str. Anvil
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Return to Measuring Position
Straightening Punch
Center
Str. Anvil
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Measuring Position
Straightening Punch
Center
Str. Anvil
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Measure
Straightening Punch
Center
Str. Anvil
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Measure
Straightening Punch
Center
Str. Anvil
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Measure
Straightening Punch
Center
Str. Anvil
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Ram Return
Straightening Punch
Center
Str. Anvil
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Centers Retract
Straightening Punch
Center
Str. Anvil
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Ready for Unload
Straightening Punch
Center
Str. Anvil
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STRAIGHTENING PROCESS SIDEWAYS VIEW
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Straightening Punch
Measure Rotate workpiece 360 Degrees
Preset distance for the TIR Measurement
Straightening Anvil
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Straightening Punch
Preset distance for the TIR Measurement
Straightening Anvil
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Straightening Punch
If not in tolerance - Position highpoint up -
? Straighten
Preset distance for the TIR Measurement
Straightening Anvil
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Straightening Punch

• Straighten
• Select Straightening Point

Preset distance for the TIR Measurement
High Point Up
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Straightening Anvil
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Straightening Punch
Shortening of the straightening stroke by the
vertical movement of the punch motion
300mm
Straightening Anvil
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Straightening Punch
299mm
Advance the straightening anvil
Straightening Anvil
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Straightening Punch
298mm
Advance to anvil block
Straightening Anvil
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Straightening Punch
297.5mm
Part on anvil block Initial Stroke Target
0.485mm Stroke distance
0.000mm
Straightening Anvil
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Straightening Punch
297.015mm
Part on anvil block Initital Stroke Target
0.485mm Stroke distance
0.485mm
Straightening Anvil
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Return to Measuring Position 300mm
297.5mm
Straightening Anvil
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Straightening Punch
298mm
Return to measuring position 300mm
Straightening Anvil
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Straightening Punch
299mm
Return to Measuring Position 300mm
Straightening Anvil
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Straightening Punch
300mm
Measuring Position 300mm TIR Control Revolution
Straightening Anvil
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Straightening Punch
300mm
Measuring Position 300mm TIR Control Revolution
Straightening Anvil
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Straightening Punch
300mm
Measurement in Tolerance Measurement not in
tolerance
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start postion
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start postion
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start postiion
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling returns to start position
Straightening Anvil
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Straightening Punch
Straightening Tooling in start postion
Straightening Anvil
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Additional Capabilities

• Crack Detection
• Acoustic Emission
• Ultrasonic
• Eddy Current
• Traceability
• Bar coding
• Output of data in CRV values
• Excel spreadsheets
• Gear form error measurement

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Summary

• Straightening to closer tolerances reduces
  manufacturing costs
• Automatic straightening provides 100 in
  process inspection
• Automatic straightening can help improve all
  processes by providing feedback on part
  distortion
• Automatic straightening is a relatively low cost
  process compared to other processes required for
  the part to clean up.