WP3 meeting
08/10/2014
Fabrication of test coil for D1
2m model
Michinaka SUGANO
KEK
Purposes of test coil fabrication 1
To verify the following items
-
Toolings for winding (Mandrel, Forming block, …)
Operation test for winding machine, hydraulic press, heater,…
Design of end spacers, winding and measurement of coil end
Confirmation of curing cycle (temperature profile and homogeneity, pressure)
Practice for quality assurance
electrical tests of coil (ground fault, cable resistance, turn-turn insulation,…)
Once test coil fabrication is completed, it will be used for
- Commissioning of coil size measurement
- Practice for attaching voltage leads
- 200mm-long mechanical model
1
Purposes of test coil fabrication 2
- Radiation resistant GFRP end spacers and wedges
End spacers and wedges made of
BT resin + S2 glass fibre were used for
the first time
End spacers were machined in house
Can newly developed hard GFRP end spacers
be accommodated to the cable by curing ?
- Curing with radiation resistant cyanate ester adhesive
Curing temperature around 200oC is needed, while it should not influence
on contact resistance between the strands
(lower than melting point of Stabrite coating)
To consider compromised heat treatment condition
and check if bonding strength is strong enough even for single layer coil
2
Coil structure
Cable: NbTi MB cable with APICAL and PIXEO insulation supplied by CERN
Coil configuration:
- Single layer coil
- 44 turns, 4 coil blocks
- Coil length: 2020 mm (between the end saddles)
- 2D cross-section for HX-hole of 50 mm (old version)
Ramp box
Center post
Pole shim (GFRP)
Wedge(GFRP)
Mandrel
MP shim(GFRP)
Pushing bar
3
Coil end
- Coil end shape was slightly modified based on the result of practice winding
Practice winding
The cable angle was inclined too much and
large gap between the cable and end spacer remained
End spacer was re-designed to accommodate to
the inclined cable
(but further modification for the 2m-model coils
should be needed)
Lead end
Return end
4
Layer jump
2D cross-sections of the layer jump
Coil layer at the straight section
A
Pole turn
Collar layer at the lead end
B
C
Ramp box was designed in such a
way that the layer jump turn go out
uprightly
Ramp box
C
B
A
5
Coil winding
Winding machine
Tensioner
Feeder
Winding mandrel
Measurement of cable positions and
angles
Turn table
Winding tension: Started from 40.9 kgf,
decreased by 0.25 kgf/turn
6
Fitting of end spacer to cable
Gap between the end saddle and the cable remained
 We checked if the gap can be closed after curing
7
Preparation for curing
SUS liner + Midplane shim
Pushing bars
Alignment pin
SUS protective liner
8
Transfer of coil into forming block
Pushing the coil
into the groove
by screwing the bolts
Forming block
Insertion tooling
The coil was successfully inserted to the
forming block using the alignment pin
and jigs
9
How much should coil be compressed in curing ?
Final size of coil is determined by yoking
Pressure applied to coil
Curing: 50 MPa
Yoking: 100 MPa (max)  80 MPa
From the results of 10 stack measurement (22 cables),
coil after curing should be larger by 0.9 mm
than the final size
Gap
Curing pressure
Pushing bar
0.9mm-thick shim Mandrel
Forming block
0.9 mm-thick shims were inserted
and coil was compressed until the gap
was closed
10
Curing press
90 ton hydraulic rams x3x7 over the length of 2m-coil
Longitudinal load
(5.2 tonf)
Hydraulic ram
Thickness gauge
Vertical load was applied incrementally
until the gap was closed
11
Determination of curing pressure
1
2
3
Forming
block
Mandrel
4
5
Check by Fuji paper
6
Gap
Coil pressure:
50 MPa
Pressure pattern
by pushing bars
Gap was closed at hydraulic pressure of 23 MPa
Pressure in curing
12
Configuration of heater and thermometers
Form-block
Mandrel Used for heater control
Heater
(Both sides)
Thermocouples
1m-long cartridge heater
Heaters in mandrel
4 in forming block
2 in winding mandrel
Thermocouples
10 in forming block
5 in winding mandrel
2 at cartridge heater for mandrel
Heaters in forming block
13
Consideration for heat treatment profile
Heat treatment condition for cyanate ester
Recommended curing pattern given by the company:
150oC x 4h + 180oC x 4h + 220oC x 4h
Adopted pattern: 150oC x 4h + 180oC x 8h
Heat treatment condition for PIXEO
T > 190oC is necessary, but maximum temperature should be limited lower than
220oC (melting point of SnAg coating)
Temperature (oC)
Test with short sample cable and GFRP plate
#3
#3
#1
#1
#2
#3: Adopted pattern, thinly painted
#1: Adopted pattern, thickly painted
#2: Shortened pattern (no plateau), thinly painted
Leakage of adhesive
after HT in thickly painted
sample
“Adopted pattern + thinly painted”
was selected
Elapsed time (hr)
Heat treatment condition for curing
150oC x 4h + 180oC x 8h + >190oC x 0.5h
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Heat treatment profile for curing
Temperature
4h
8h
0.5h
Pressure
190℃
Temperature
180℃
150℃
100℃
90℃
Longitudinal press
Time
- Maximum temperature was selected to be 190oC
- Vertical pressure was unloaded/reloaded during heat treatment
- Longitudinal pressure was applied from the both ends of the coil
15
Actual temperature trend in curing
Bonding of polyimide insulation
190oC
180oC
150oC
NN N
F-E
M
F-W
M
S
SS
Temperature profile to harden cyanate ester (150oC x 4h + 180oC x 8h) was obtained
as expected
Max. temperature could be controlled at 190 - 210oC (< 220oC)
Expected temperature profile was realized
16
Coil after curing
The gap between the end saddle and
the cable was closed after curing
Hard BT resin + S2 glass GFRP can
be accomodated to the cable
Bonding between the cable and
the wedges is sufficiently strong
 Effectiveness of heat treatment
profile is verified
17
Electrical tests after curing
- No ground fault throughout winding and curing
- No change of cable resistance (for 44 turn)
After winding
242.9 mW
Under curing pressure,
before curing
242.5 mW
After curing
242.2 mW
- No damage of cable insulation checked
by a bundle of fine Nb-Ti filaments
- No turn-turn insulation failure at least
up to 1 kV (Surge test)
- Coil inductance: 2.3 mH
Surge test
Electrical soundness of the coil
was confirmed
18
Issues to be modified 1
Protective liner
The protective liner was plastically deformed after curing
Slit for the layer jump
Bottom surface of the
ramp box
Ramp box is slightly
popping up
Groove for the layer jump
Protective liner
Forming block
Width of the groove should be made smaller
Additional support is needed for the layer jump
19
Issues to be modified 2
There is a gap at the boundary of the end
spacer and the cable
The leads for the QPH could be damaged
Approach 1: Modification of coil end shape
To make the cable more upright by elongating the length of coil end
Approach 2: Filling the gap with shoe
20
Preparation for coil size measurement
Same system as CERN (Thanks to G. Kirby)
-
50 ton hydraulic press
Coil pressure up to 130 MPa
Continuous measurement using the 5.4 m-long bench
Two pushing bars each having 5 x 20mm-wide fingers
Pushing bars with strain gauges
50 ton loading test for checking the support structure
and
calibration of load-strain relationship for pushing bars
have been completed
Measurement using the test coil will be carried
out soon
21
Future plan
Test coil fabrication
- Coil size measurement:
- Mechanical short model:
Oct 2014
Dec 2014
2m-model magnet development
- Coil winding:
- Delivery of collar and yoke plates:
- Instrumentation:
- Collaring:
- Yoking:
Dec 2014 ~ Jan 2015
end of Jan 2015
Feb 2015
~ end of Feb 2015
Mar ~ April 2015
Test station
- Delivery of 15kA current leads:
- Inspection by local government:
- Commissioning:
- Cold test of 1st model magnet:
~end of March 2015
May 2015
Jun 2015
Sep 2015
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Summary
- 2m-long test coil for D1 was wound and cured.
- Radiation resistant BT resin + S2 glass GFRP spacers and wedges were used for
winding for the first time. Fairly good fitting was confirmed between the spacers
and the cable after curing.
- Heat treatment up to 190oC for cyanate ester was tried and sufficiently strong
bonding was confirmed.
- Coil size measurement will be carried out soon.
- Mechanical short model will be assembled using straight section cut out from the
test coil.
- We found some issued to be solved such as support of the ramp box and gap
between the top of the cable and end spacer. Modification would be applied to the
future 2m-long model coils.
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