A CONTINUOUS WINDING/BONDING TECHNIQUE FOR THE MANUFACTURE OF MULTI-LAYER HELICAL MAGNET WINDINGS

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A CONTINUOUS WINDING/BONDING TECHNIQUE FOR THE MANUFACTURE OF MULTI-LAYER HELICAL MAGNET WINDINGS

P. Hudson, H. Jones, H. Whitworth

To cite this version:

P. Hudson, H. Jones, H. Whitworth. A CONTINUOUS WINDING/BONDING TECHNIQUE FOR

THE MANUFACTURE OF MULTI-LAYER HELICAL MAGNET WINDINGS. Journal de Physique

Colloques, 1984, 45 (C1), pp.C1-55-C1-58. �10.1051/jphyscol:1984111�. �jpa-00223578�

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JOURNAL DE PHYSIQUE

Colloque Cl, supplément au n° 1, Tome 45, janvier 1984 page Cl-55

A CONTINUOUS WINDING/BONDING TECHNIQUE FOR THE MANUFACTURE OF MULTI- LAYER HELICAL MAGNET WINDINGS

P.A. Hudson, H. J o n e s and H.M. Whitworth

University of Oxford, Clarendon Laboratory, Parks Road, Oxford 0X1 SPU, U.K.

RÉSUMÉ

On d é c r i t un nouveau développement de l a t e c h n i q u e " p o l y h é l i c e " p o u r l a c o n - s t r u c t i o n de b o b i n e s à h a u t e p u i s s a n c e , / l / C e t t e méthode emploie une p e l l i - c u l e " s è c h e " é p o x y / n y l o n que l ' o n e n r o u l e e n t r e l e s s p i r e s d ' u n b o b i n a g e e n c u i v r e à p l u s i e u i s c o u c h e s . Une b o b i n e p r o t o t y p e f a b r i q u é e p a r c e t t e méthode f a i t p r e u v e d ' u n e performance e x c e l l e n t e . Une deuxième b o b i n e s e r v i r a à p o u s s e r l a l i m i t e de l a Bobine Hybride de 15,5T à 20T.

ABSTRACT

I n t h i s p a p e r we d e s c r i b e a development t o t h e f a m i l i a r p o l y h e l i x t e c h n i q u e f o r c o n s t r u c t i n g h i g h power s o l e n o i d s . I\l This development c e n t r e s on t h e use of a d r y - f i l m n y l o n m o d i f i e d epoxy r e s i n which i s edge wound between t h e t u r n s of a m u l t i - l a y e r h e l i c a l copper w i n d i n g . We d e s c r i b e a p r o t o t y p e s o l e n o i d whose performance i s h i g h l y s a t i s f a c t o r y . We p r o p o s e t o use t h i s method t o c o n s t r u c t a f u r t h e r s o l e n o i d which w i l l u p r a t e o u r Hybrid Magnet from 15.5T t o 20T.

1 - BACKGROUND

I n October 1980 t h e f o u r i n n e r c o i l s of t h e w a t e r - c o o l e d p o l y h e l i x 111 s e c t i o n of t h e Hybrid Magnet / 3 / b u r n t o u t . Replacement c o i l s were wound u s i n g Redux 308A a d h e s i v e , (Cibe-Geigy L t d . , U.K.) which was e v a l u a t e d i n 1974 as p a r t of a NATO s u p p o r t e d p r o j e c t / 4 / . These c o i l s have performed w e l l over 2\ y e a r s of e x t e n s i v e u s e . T h e i r c o n s t r u c t i o n has b e e n p r e v i o u s l y r e p o r t e d i n r e f e r e n c e s / 5 , 6 / .

The e x i s t i n g p o l y h e l i x s e c t i o n c o n s i s t s of 10 c o i l s n e s t e d c o a x i a l l y and c o - n n e c t e d i n s i x s e r i e s / p a r a l l e l g r o u p s . Because of t h i s c o m p l e x i t y an a l t e r n a t i v e method of f a b r i c a t i n g p o l y h e l i x c o i l s was s o u g h t . We have, b u i l t a p r o t o t y p e r e - p l a c e m e n t c o n s i s t i n g of two m o d u l e s , e a c h of which i s a s i m p l e c o n t i n u o u s l a y e r wound s o l e n o i d bonded u s i n g Redux.

I n t h i s p a p e r we d e s c r i b e the c o n s t r u c t i o n of t h i s p r o t o t y p e and t h e t e c h n i q u e s used t h e r e i n . The p r i n c i p a l dimensions of the c o i l , and o t h e r d a t a , a r e l i s t e d i n t a b l e 1 .

2 - THE ADHESIVE

Redux 308A i s a n y l o n m o d i f i e d epoxy s u p p l i e d i n d r y - f i l m form. I t c o n t a i n s a s m a l l q u a n t i t y of ^ 0 . 0 7 mm d i a . g l a s s bead which h e l p s m a i n t a i n a glue l i n e t h i c k - n e s s of ^ 0.1 mm w i t h a clamping p r e s s u r e of 210-280 KN/m2, c u r i n g r e q u i r e s a mimi- mum of 1 h o u r a t 150-170°C. The uncured a d h e s i v e i s t e m p e r a t u r e s e n s i t i v e ; i t h a n d l e s e a s i l y between 15°C and 25°C, a d h e r e s to s u r f a c e s a t > 25°C and i s f a i r l y f l u i d above 50°C. The a d h e s i v e h a s a h i g h e l o n g a t i o n t h u s making i t s u i t a b l e f o r o u r c o i l w i n d i n g t e c h n i q u e s .

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1984111

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C 1-56 JOURNAL

DE

PHYSIQUE

Table 1

C o i l 1 Coil 2

27 69.5

a2 69.5 106

b 52 5 2

c o n d u c t o r s e c t i o n 4.57 ^X4.57 5.59 X 5 . 5 9

number o f l a y e r s 8 6

channel h e i g h t 0.67 0.51

power r a t i o a t l . 78 MW 1.0 0 . 7

AT at 1 . 7 8 MW ^S3 8 ' ~ % 34Oc

C* = [B(;)' ] see / 7 / 17.4

dimensions i n m. m. F l g , l . 3 - THE W I N D I N G PROCESS

-S

The two modules o f t h e p r o t o t y p e were e

*A3 0

wound from s t a n d a r d s q u a r e s e c t i o n , h i g h con- d u c t i v i t y , h a r d drawn copper ( B . S . 1432).

A f t e r p r e t r e a t m e n t a p r i m e r , Redux 108, i s

a p p l i e d t o t h e f a c e s t o be bonded. As t h e ad- .:*srk>

h e s i v e i s s u p p l i e d i n s h e e t form i t h a s t o b e s l i c e d i n t o a c o n t i n u o u s l e n g t h % 3 mm w i d e , u s i n g a k n i f e t o o l , by making a s i n g l e h e l i c a l c u t i n a s e a m - j o i n t e d c y l i n d e r o f Redux s h e e t

mounted o n a r e v o l v i n g drum o n a l a t h e ( F i g . I ) . F i g . 2 . The c o n d u c t o r , which i s pre-warmed t o

> 250C, i s f e d o n t o a s p e c i a l mandrel ( F i g . 2) v i a a w i n d i n g h e a d assembly ( F i g . 3) which p e r f o r m s s e v e r a l f u n c t i o n s ; ( a ) i t e n s u r e s c o r r e c t a l i g n m e n t o f t h e c o n d u c t o r , (b) i t po- s i t i o n s and p r e s s e s t h e Redux s t r i p on t o one f a c e , and ( c ) i t removes t h e b a c k i n g f i l m from t h e a d h e s i v e . A d d i t i o n a l h e a t , s u p p l i e d by a h o t a i r blower t o t h e t u r n s on t h e m a n d r e l , t o g e t h e r w i t h p r e s s u r e a p p l i e d by two s p r i n g l o a d e d r o l l e r s , c a u s e s t h e a d h e s i v e t o f i l l t h e g l u e l i n e . The whole of t h e c o i l w i n d i n g assembly is mounted o n t h e t o o l p o s t o f t h e c o i l w i n d i n g l a t h e and i s t r a v e r s e d t o match t h e p i t c h o f t h e c o i l . The w i n d i n g s p e e d i s a p p r o x i m a t e l y i-2 rpm b e i n g d e p e n d e n t on t h e r a t e a t which t h e c o n d u c t o r can b e warmed t o s u i t t h e a d h e s i v e . There i s no run-out o f t h e a d h e s i v e s o no p o s t - c u r e machining i s

n e c e s s a r y .

The l a s t t u r n o f e a c h l a y e r i s h e l d i n p l a c e by t h r e a d e d r o d s ( p r o d s ) ( s e e F i g s . 2 and 3 ) mounted o n t h e m a n d r e l . These p r o d s a l s o s e r v e t o d e f i n e t h e h e l i x a n g l e a t t h e b e g i n n i n g o f a l a y e r .

Water c o o l i n g c h a n n e l s a r e formed by g l u e i n g e q u a l l y s p a c e d SRBF s p i l l s ( a l s o u s i n g Redux) around t h e c i r c u m f e r e n c e of a completed l a y e r u s i n g a b r a s s s h i m ' c o r s e t ' , t o s e c u r e them t e m p o r a r i l y d u r i n g c u r i n g . C u r i n g t a k e s 1

F i g . 3.

Fig. 4.

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p l a c e i n - s i t u f o r e a c h l a y e r u s i n g a n i n f r a - r e d oven ( F i g . 4 ) . 4 - MACHINING

The o v e r a l l r u n o u t from c o n c e n t r i c i t y was o n l y ? 0 . 3 mm f o r e a c h o f t h e two modules. To a l l o w f o r t h i s t h i c k e r s p i l l s were u s e d o n t h e l a s t l a y e r o f e a c h module t o a l l o w f o r compensating machining.

5 - COIL SUPPORTS

F +l!

The f i n i s h e d magnet was s u p p o r t e d t o p and b o t t o m by two g l a s s /epoxy l a m i n a t e

'

c a r t - w h e e l s ' F i g . ( 5 ) . These were d r i l l e d a t r e g u l a r i n t e r v a l s t o r e c e i v e 3.2 mm d i a . g l a s s / e p o x y r o d s which were pushed t h r o u g h t o make c o n t a c t w i t h t h e c o i l e n d s w h i l s t t h e ' c a r t w h e e l

'

was p o s i t i o n e d p e r p e n d i c u l a r t o t h e magnet a x i s . Epoxy r e s i n i n - j e c t e d i n t o c o u n t e r b o r e s around t h e r o d s , s e c u r e d them i n po- s i t i o n , and t h e ' c a r t w h e e l s ' were skimmed f l u s h o n t h e i r

r e v e r s e s i d e s . T h i s t e c h n i q u e F i g . 5 . The p r o t o t y p e two module s o l e n o i d p r o v i d e s e x c e l l e n t s u p p o r t t o g e t h e r w i t h s u p p o r t i n g ' c a r t w h e e l s ' , c e n t r e t u b e w i t h o u t c o m p l i c a t e d machining. and c u r r e n t l e a d s .

6 - ELECTRICAL SHORT DETECTION

Checks were made f o r s h o r t s ~ r i o r t o and a f t e r c u r i n g . The ~ o t e n t i a l drop p e r t u r n was measured u s i n g a c u r r e n t of 10 amps. Any t u r n t o t u r n s h o r t s were e a s i l y d e t e c t a b l e u s i n g t h i s method. Remedial a c t i o n p r i o r t o c u r i n g i s p o s s i b l e by i n s e r - t i n g t e m p o r a r y n o n - m e t a l l i c wedges between t u r n s and i n t r o d u c i n g more a d h e s i v e . L i t t l e can b e done a f t e r c u r i n g .

7 - PROBLEMS

The copper s e c t i o n s u s e d f o r e a r l y t e s t s o f t h e w i n d i n g t e c h n i q u e , h a d s m a l l wedge a n g l e s r o l l e d a l o n g t h e i r l e n g t h s t o compensate f o r t h e change i n c r o s s s e c -

t i o n due t o t h e c o i l f o r m i n g p r o c e s s . These a n g l e s p r o v e d i n a d e q u a t e a s i n t e r - t u r n s h o r t s a t t h e i n n e r w i n d i n g f a c e were found. These were c a u s e d by l o c a l i s e d d i s t o r - t i o n o f t h e copper by t h e s p i l l s . The problem was s o l v e d by s l i g h t i n c r e a s e s i n wedge a n g l e s t o 2.5O and 1.5O f o r t h e i n n e r and o u t e r modules r e s p e c t i v e l y .

Two o t h e r mechanisms f o r s h o r t i n g became a p p a r e n t . One was due t o t h e c o n d u c t o r c a n t i n g o r t w i s t i n g d u r i n g w i n d i n g c a u s i n g d i s t r i b u t e d s h o r t s . The o t h e r was due t o e x c e s s i v e a x i a l clamping a t l a y e r e n d s .

8 - TESTING

The r e s u l t s o f t e s t s o f t h e p r o t o t y p e a r e e n c o u r a g i n g . Using t h e l a b o r a t o r y ' s 2 MW s y s t e m 10.0 T e s l a h a s b e e n q c h i e v e d w i t h 1 . 7 8 MW a t 4587 amps w i t h a n i n l e t w a t e r t e m p e r a t u r e o f 320C. The two modules r a n a p p r o x i m a t e l y 380C and 340C above i n l e t w a t e r t e m p e r a t u r e . P o t e n t i a l t a p s o n t h e two c o i l modules a l l o w e d measurements o f c o i l v o l t a g e s . The i n n e r module r a n a p p r o x i m a t e l y 27% c o o l e r t h a n a n t i c i p a t e d w h i l s t t h e o u t e r module was v e r y c l o s e t o t h e c a l c u l a t e d v a l u e . With more power i n hand from t h e 2 MW s y s t e m we e x p e c t t o b e a b l e t o a c h i e v e Q 10.7 T e s l a w i t h a n i n l e t w a t e r t e m p e r a t u r e o f 20°C.

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JOURNAL

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PHYSIQUE

9

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FUTURE PLANS

The p r o t o t y p e magnet i s i n t h e p r o c e s s o f b e i n g i n s t a l l e d i n o n e o f t h e l a b o r a - t o r y ' s r e g u l a r magnet s t a t i o n s i n o r d e r t h a t i t s l o n g t e r m p e r f o r m a n c e c a n b e e v a l u - a t e d .

We p r o p o s e t o b u i l d an i d e n t i c a l c o i l t o r e p l a c e t h e e x i s t i n g w a t e r c o o l e d s e c t i o n o f t h e H y b r i d Magnet, and t h e n a t h r e e module, 30 mm b o r e v e r s i o n , w h i c h , u s i n g 2 MW, w i l l g i v e '1. 13.5 T t h u s e n a b l i n g t h e H y b r i d Magnet t o p r o d u c e a t o t a l o f

*

20T.

ACKNOWLEDGEMENTS

A g r e a t many p e o p l e h a v e c o n t r i b u t e d t o t h e s u c c e s s o f t h e H y b r i d Magnet p r o j e c t , t o o numerous t o m e n t i o n i n d i v i d u a l l y by name. The d e v e l o p m e n t s r e p o r t e d h e r e w e r e a s s i s t e d by h e l p f u l d i s c u s s i o n w i t h t h e Bonded S t r u c t u r e s D i v i s i o n o f Ciba-Geigy (U.K.). The p r o j e c t h a s r e c e i v e d f i n a n c i a l s u p p o r t f r o m D e p a r t m e n t a l s o u r c e s a n d t h e SERC. I t i s w i t h r e g r e t we h a v e t o announce t h e d e a t h o f P.A.Hudson d u r i n g t h e p r e p a r a t i o n o f t h i s p a p e r .

REFERENCES

1 . HUDSON P.A., HANLEY P.E. a n d CARDEN P.O. P r o c . 5 t h I n t . Conf. o n Magnet Technology, Roma, CNEN, 1975, p . 414

2. HUDSON P.A. P r o c . 4 t h I n t . Conf. o n Magnet Technology ,USAEC CONF-720908, 1972 D. 444

3. HUDSON P.A. and JONES H. C r y o g e n i c s , O c t . 1980 p . 5 9 3

4. HUDSON P.A. I n t e r i m R e p o r t : C o n s t r u c t i o n o f P o l ~ h e l i x Magnet C o i l s , 1974, u n ~ u b l i s h e d

5 . H U D S ~ N P . A . a n d JONESH. IEEE T r a n s . M a g n e t i c s Vol. 17, 1981, p . 2242 6 . HUDSON P.A., JONES H. a n d WHITWORTH H.M. S p r i n g e r V e r l a g L e c t u r e N o t e s i n

P h y s i c s No. 177 p . 500

7. SCHNEIDER-MUNTAU H . J . , PICOCHE J . C . , RUB P . and VALLIER J.C. S p r i n g e r V e r l a g L e c t u r e N o t e s i n P h y s i c s No. 177 p . 531