Download 6_25_Piezo_Solution

CLIC PMQ T2
Electro - Mechanical solution to move the PM for v. 6.25
Assuming the specification for the second family
member remains the same with respect to accuracy, the
following seems a feasible solution.
At the start of the project a Piezo-motor solution was
mentioned briefly. The spatial constraints for the second
family member appear to favour a further look at this
option.
To recap, start the slide show (F5). Press down key then slides advance automatically
03/02/2012
Norbert Collomb
1
Step 1: Top Piezos engaged
Static Marker
28/03/2010
Norbert Collomb
2
Step 2: Top and bottom Piezos engaged
Static Marker
28/03/2010
Norbert Collomb
3
Step 3: Top Piezos disengaged
Static Marker
28/03/2010
Norbert Collomb
4
Step 4: Centre Piezo expands
and moves PM up (step size)
Static Marker
28/03/2010
Norbert Collomb
5
Step 5: Top Piezos re-engaged
Static Marker
28/03/2010
Norbert Collomb
6
Step 6: Bottom Piezos disengaged
Static Marker
28/03/2010
Norbert Collomb
7
Step 7 = 1: Centre Piezo retracts
Static Marker
28/03/2010
Norbert Collomb
8
Step 1R = 7: Centre Piezo extends
Static Marker
28/03/2010
Norbert Collomb
9
Step 2R: Bottom Piezos engage
Static Marker
28/03/2010
Norbert Collomb
10
Step 3R: Top Piezos disengage
Static Marker
28/03/2010
Norbert Collomb
11
Step 4R: Centre Piezo
contracts = moves PM down
Static Marker
28/03/2010
Norbert Collomb
12
Step 5R: Top and bottom Piezos engaged
Static Marker
28/03/2010
Norbert Collomb
13
Step 6R = 1: Bottom Piezos disengaged
Static Marker
28/03/2010
Norbert Collomb
14
CLIC PMQ T2
Advantages (some):
• Infinite stroke
• Step size = accuracy = determined by Piezo stack design
• Step size can be in nanometre
• Forces are not an issue
• Piezo material can be any shape and size
• Material can be used to either expand or contract
• Material does not influence magnetic field (I would prefer to check this)
•Simple Electronic control required (cantilever approach requires 6
channel controller)
• No backlash issues
• No creep (movement over time) issues (material selection!)
• May eliminate Linear Encoder requirement provided datum is defined
• Small and compact and virtually NO moments on core items
• Could be used to align physical and magnetic axis
03/02/2012
Norbert Collomb
15
CLIC PMQ T2
Disadvantages (some):
• Never done before therefore may need more research and design time
• Piezo stack alone can’t be used in shear (top and bottom)
• Needs specific enclosure design and high friction coefficient material
• Requires tighter tolerance in the manufacture of some components
• Assembly process requires great care and attention
• Will require a separate ‘fail safe’ feature to stop PM clashing into nose
• Small step size could lead to longer PM movement than motor driven?
• Cost is comparable to ball-screw principle (initial estimate)
• Need to machine (wide) slots in faceplate and drill holes into yokes (TBD)
• Electronics could be sensitive to radiation
• Depending on size could require large voltage (very low amp)
03/02/2012
Norbert Collomb
16
CLIC PMQ T2
Shroud
Permanent Magnet frame
Yoke
Face-plate
Piezo arrangement
Bronze – Phosphor slide
Permanent Magnet
03/02/2012
Norbert Collomb
17
CLIC PMQ T2
Front View
Side View
240mm
Frame when fully
open: 391 mm
Top View
380 mm
380mm
03/02/2012
Norbert Collomb
18
CLIC PMQ T2
Shroud
Permanent Magnet frame
Yoke
Face-plate
Frame – Bush arrangement
Permanent Magnet
03/02/2012
Norbert Collomb
19
CLIC PMQ T2
Images of principle showing the magnet at different positions.
From left to right the position is 0mm, 38mm and 75mm respectively.
Magnet position:
Gradient: Int. Str:
Magnet fully closed, 43.8T/m, 8.49T
03/02/2012
Magnet position:
Gradient: Int. Str:
Magnet half closed, 25.8T/m, 5.0T
Norbert Collomb
Magnet position: Gradient: Int. Str:
Magnet fully open, 2.9T/m, 0.56T
20
CLIC PMQ T2
Summary:
• Had to introduce 0.1mm gap between Permanent Magnet and yoke by
reducing the thickness of the yoke vertical part.
• To achieve the same we could alter the geometry slightly as an alternative
• Main reason for the above is to keep the aperture the same (R14.0mm)
• A low friction material had to be introduced between the permanent
magnet and surrounding material
• This also serves as a linear guide and cater for the different dimensions
between yoke and shroud
03/02/2012
Norbert Collomb
21
CLIC PMQ T2
Summary:
• Only one side is driven
• The opposite side has a linear guide system to retain square ness
• Adjustment in the shafts (3point, not shown) permit physical axis
alignment
• Top and bottom can be driven independently
• Refinement of design in Technical Development Phase could see
reduction in size in certain areas
03/02/2012
Norbert Collomb
22