NPL TUBE FORMING

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E L S E V I E R

Journal o f Mater ia ls P rocess ing Techno logy 54 (1995) 186-192

J~lrmlhff

M a t e r i a l s

P r o c e s s i n g

T e c h n o l o g y

S h e a r s p i n n i n g t e c h n o l o g y f o r m a n u f a c t u r e

t u b e s o f s m a l l b o r e

Ra jn i sh P ra k a sh a '* , R .P . S in g h a l b

Punja b Engineering Col lege , Chandigarh, Ind ia

b Nat ional Phys ica l Labora tory , New Delh i , Ind ia

Received 1 April 1994

o f l o n g t h i n w a l l

I n d u s t r i a l s u m m a r y

Me tal sp inn ing is a p rocess in which the defo r mat io n s t resses are local ized to a smal l reg ion . The mate r ia l i s ma de to f low and m ove

o v er t h e ro t a t i n g m an d re l w i th t h e h e lp o f a sp in nin g to o l m o u n ted o n a s ad d le an d m o v in g a lo n g th e p ro f il e o f t h e m an d re l . T h e

p ro cess h as b een in u se fo r a l o n g t im e to p ro d u ce ax i - sy m m et r i c sh ap es an d tu b u la r p ro d u c t s w i th sm a l l L/D ra t io . However , the

conven t ional p rocess fa i l s to p roduce long , th in -wal l , smal l -bore tubes . The p rocess has been modif ied to sp in long , smal l -bore ,

th in - tubes in hard - to -w ork m ater ia ls such as CP t i tan ium, Inco loy 825 , Inconel 600 and S tain less s teel AISI-304 . The tec hno logy o f

ma k ing tubes in the abo ve mater ia ls has been developed . The effect o f feed, ro l ler p rof i le , perce n tage reduct ion and lubr ican ts used on

the su rface fin ish and the pow er consum pt ion whe n work ing wi th AISI-304 is repor ted . I t is observed that the me chan ical p roper t ies

o f the p rodu ct im prove considerab ly , c lose d imensional to lerances are ob tained on ou ts ide and ins ide d iam eters and the wal l

th ickness , and h igh reduct ions are possib le wi thou t in te rmed iate anneal ing . The new process i s economical ly v iab le fo r p roducing

tubes in h igh-s t reng th m ater ia ls , -par t icu lar ly when the vo lum e o f p rodu ct ion is no t h igh . The special featu res o f the modif ied mac h ine

are given also.

I . I n t r o d u c t i o n

T h e p h i l o s o p h y o f m o v i n g t h e m e t a l r a t h e r t h a n r e -

m o v i n g it a n d s i m u l t a n e o u s l y r e d u c i n g t h e f o r m i n g

f o r c e s a n d t h u s p r e s s c a p a c i t y le d t h e m e t a l - w o r k i n g

i n d u s t r y t o l o c a l i z e t h e d e f o r m a t i o n z o n e t o a s m a l l

v o l u m e o f t h e w o r k p i e c e , t h e r e b y e f f e c t i n g s a v i n g s i n

m a t e r i a l s a n d e n e r g y f o r s e c u ri n g t h e r e q u i r e d f i na l

s h a p e .

S p i n n i n g i s o n e s u c h p r o c e s s , i n w h i c h t h e s t r e s s e s a r e

l o c a l iz e d t o a s m a l l r e g i o n a n d t h e m a t e r i a l i s m a d e t o

f l o w a n d m o v e o v e r t h e m a n d r e l w i t h t h e h e l p o f a s p i n -

n in g t o o l i . e . r o l l e r .

T h e p r o c e s s h a s b e e n i n u s e f o r a l o n g t i m e f o r p r o d u -

c i n g c o n i c a l a n d a x y - s y m m e t r i c a l s h a p e s a n d t u b u l a r

p r o d u c t s w i t h a l a r g e d i a m e t e r - t o - l e n g t h r a t io [ 1 - 5 ] . I n

t h e c a s e o f c o n e s p i n n i n g t h e a x i a l t h i c k n e ss o f t h e p r o d -

u c t c h a n g e s a s p e r t h e S i n e l a w , w h i c h s t a t e s :

t = t o s i n ~ , ( 1)

w h e r e t i s t h e s p u n t h i c k n e s s , t o i s t h e t h i c k n e s s o f t h e

b l a n k a n d a is th e s e m i - c o n e a n g l e o f t h e m a n d r e l . H o w -

* Correspo nding aut hor.

e v e r , t h is l a w d o e s n o t a p p l y i n t h e c a s e o f t u b u l a r

p r o d u c t s , a s t h e s e m i - c o n e a n g l e o f t h e m a n d r e l i s z e r o ,

a n d t h e p e r c e n t a g e r e d u c t i o n i n t h e w a l l t h ic k n e s s b e i n g

g i v e n b y

t o - - t

- - x 1 0 0 % . ( 2 )

to

2 . C o n v e n t i o n a l t u b e s p i n n i n g

T w o p r o c e s s e s i n t h e s h e a r s p i n n i n g o f t ub e s a r e

r e c o g n i z e d, t h e s e b e i ng : (i) t h e F o r w a r d o r D r a w i n g

t y p e ; a n d ( i i) t h e B a c k w a r d o r E x t r u d i n g t y p e ;

o f t u b e s p i n n i n g , b o t h b e i n g w e l l d e s c r i b e d , w i t h

f o r w a r d s p i n n i n g u s u a l l y b e i n g p r e f e r r e d E 6 1 0 ].

T h e m a i n f e a t u r e s o f th e p r o c e s s a r e s h o w n i n F i gs . l (a )

and (b ) .

H o w e v e r , t h i s c o n v e n t i o n a l t u b e s p i n n i n g p r o c e s s i s

n o t s u i t a b l e f o r t h e s h e a r s p i n n i n g o f l o n g t h i n - w a l l ,

s m a l l - b o r e t u b e s , a s t h e m a n d r e l i n t h i s c a s e h a s t o b e

l o n g a n d t h i n , a n d w i l l t h e r e f o r e t e n d t o s a g w h e n h e l d

b e t w e e n t h e h e a d - s t o c k a n d t h e t a i l - s t o c k . D u e t o s a g -

g i n g it w il l n o t b e p o s s i b l e t o r o t a t e t h e w o r k p i e c e a l o n -

g w i t h t h e m a n d r e l , m a k i n g t h e c o n v e n t i o n a l s p i n n i n g

p r o c e s s u n w o r k a b l e .

0924-0136/95/ 09.50 © 1995 Elsevier Science S.A. All righ ts reserved

S S D I

0 9 2 4 - 0 1 3 6 ( 9 5 ) 0 1 9 4 0 - G



R. Prakash, R.P. Singhal / Journal o f Materials Processing T echnology 54 (1995) 186-192

187

a)

r -

ER TR VE

2

b)

= 2

:~ . ' . . _ . 1 ~

. . . ~

Fig. 1. Spinning of tu bul ar products: (a) forward tu be spinning;

(b) backw ard ube spinn ing 1, mand rel; 2, workpiece;3, followerblock;

4, antifrictioncentre; 5, form ing rollers).

3 . M o d i f i e d s h e a r s p i n n i n g

T o b r i n g t h e l o n g , t h i n - w a l l a n d s m a l l - b o r e t u b i n g s

w i t h i n t h e c a p a b i l i t y o f t h e s h e a r s p i n n i n g p r o c e s s , t h e

e x i s t in g p r o c es s h a s b e e n m o d i f i e d a n d a n e w m a c h i n e

d e v e l o p e d ( c o u r t e s y U N D P ) . T h i s is c a p a b l e o f s h e a r

s p i n n i n g t h i n - w a l l ( 0 . 7 5 - 1 . 0 0 m m ) , s m a l l - b o r e ( 2 5 -

3 0 m m ) t u b e s i n l o n g l e n g t h s ( 10 m ) w i t h h i g h d i m e n -

s i o n a l t o l e r a n c e s . S i n c e t h e m a n d r e l h u g s t h e w o r k p i e c e

d u r i n g s p i n n i n g, n o r m a l l y i t c a n n o t b e r e m o v e d f r o m t h e

t u b e m a n u a l l y . T h e r e f o r e , a m a n d r e l r e m o v e r s i m i l a r to

the low-power hydrau l i c d raw-bench has been deve loped

a l so . The m odi f i ed ve rs ion of the m achine has the fo l lowing

bas ic features , and is shown in F igs . 2 and 3. ( i ) The tube

(12) wi th the m an dre l (13) (com pos i te ) m ove s l inea r ly and

the spinn ing tools , i . e . the rol lers (4), rota te . ( i i ) Th e rol lers

(4) a re m o unt ed o n a hy drau l i ca l ly ac tua ted th ree - jaw

chuck (3) replacing i ts original three jaws. ( i i i ) The work-

piece (12) is s l id and clamped over the well- lubricated

m an dre l (13) . ( iv ) The m achine i s adequa te ly ins t rum ented

so tha t the va r ious pa ram ete rs can be recorded and op t i -

mized. (v) Tube s in th e s ize range o f 15-3 2 m m outs ide

d iam ete r , and of 0 . 75-1 .00 m m wal l th ickness and 7000 m m

length can be p roduced on the m achine . (v i ) A th ree- ro ll e r

sys tem ins tead of the usua l two-ro l l er sys tem has been used

to ensure self-a l ignment of the assembly and good concen-

tr ic i ty in the sp un produ ct . (vi i ) A hyd raul ical ly actua ted

6

Fig. 2. Schematic view of the shear spinning machine (1, gripper 3 -jaw chuck; 2, slides; 3, h ydraulic chuck; 4, spinning rollers; 5, ball screw;

6, ball screw nu t; 7, rotatin g cylinder; 8, contr ol pane l; 9, instrum ent panel; 10, loa d cell; 11, cover guard (splash guard)).



188

R. Prakash , R .P. S inghal / Journal o f Materia ls Processing Technology 54 (1995) 18 6-192

c h u c k ( 3 ) i s u s e d s o t h a t t h e r o l l e r s a r e c l o s e d o n t h e

c o m p o s i t e ( w o r k p i e c e ) a f t e r t h e c h u c k h a s a t t a i n e d f ul l

s p e e d . T h i s r e d u c e s t h e i n s t a n t p u l l i n g l o a d i . e . t h e a x i a l

f o r c e , a t t h e s t a r t a n d m a k e s t h e s p i n n i n g o p e r a t i o n

s m o o t h .

3.1. Technical speci fications o f the mach ine

S iz e r a ng e O D

I D

W a l l t h i c k n e s s W T :

L e n g t h

S p e e d o f t h e c h u c k :

P u l l i n g s p e e d ( f e e d )

( 8 0 - 2 0 0 r p m v a r i a b l e )

R e v e r s e s p e e d

C h u c k d i a m e t e r

C l a m p i n g f o r c e

H y d r a u l i c p o w e r p a c k

P r e s s u r e

4 0 m m m a x . ( 1 5 m m t o

3 2 m m )

1 2 m m m i n .

2 5. 5 m m m a x .

1 0.5 m m

0 .7 5 m m

1 0 00 0 m m m a x .

1 52 8 r p m m a x . ( 1 5 00 r p m

n o r m a l )

5 0 8 r p m m i n .

7 50 m m p e r m i n u t e m a x .

2 8 m m p e r 2 8 r a i n m a x .

( 0 . 2 5 - 2 m m p e r r e v o l u t i o n )

5 m / m i n f i x e d (2 0 0 r p m )

4 0 0 m m ( 1 6 i n )

1 0 0 0 k g f

4 0 H P , 1 8 0 0 r p m , m o t o r

s u i t a b l e f o r 4 4 0 V , 3 p h a s e ,

5 0 c / s A C s u p p l y

2 .0 5 M P a ( 3 0 00 p si ) m a x .

1 .5 M P a (2 2 0 0 p s i )

R e v e r s in g m o t o r

L u b r i c an t m o t o r

M a n d r e l r e m o v e r

: 2 H P g e a r e d m o t o r s u i t a b l e

f o r 4 4 0 V , 3 p h a s e , 5 0 c / s A C

s u p p l y

: 2 H P , 3 0 0 0 r p m s u i t a b l e f o r

4 4 0 V , 3 p h a s e , 5 0 c / s A C

s u p p l y

: D r i v e n b y th e s a m e h y d r a u -

l ic p o w e r p a c k a s m a i n m a -

c h i n e

A s c h e m a t i c v i e w o f t h e m a c h i n e i s s h o w n i n F i g. 2 , t h e

s p i n n i n g a r r a n g e m e n t i s s h o w n i n F ig . 3 a n d t h e r o l l e r

a s s e m b l y w i t h f e e d s c r e w i s s h o w n i n F i g . 4 .

4 . E x p e r i m e n t a l s e t - u p

W i t h t h e p r e s e n t s e t - u p i t i s p o s s i b l e t o s h e a r s p i n a n

i n i ti a l w a l l t h i c k n e s s o f 4 m m s a t i s f a c t o r i l y , th e t u b e

b e i n g i n t h e a n n e a l e d c o n d i t i o n a t t h e c o m m e n c e m e n t o f

t h e o p e r a t i o n . A n a r e a r e d u c t i o n o f 7 0 8 0 % w a s p l a n -

n e d , te s t p ie c e s a t r e d u c t i o n s o f a b o u t 4 0 , 6 0 a n d 8 0 %

b e i n g c ut a n d e v a l u a t e d f o r m e c h a n i c a l p r o p e r t i e s , s u r -

f a c e f in i sh a n d a c t u a l d i m e n s i o n s . T h e w o r k w a s c o n d u c -

t e d o n s t a i n l e s s s t e e l A I S I - 3 0 4 u s i n g d i f f e r e n t l u b r i c a n t s ,

t h e l a t t e r b e i n g u s e d s o a s t o b e a b l e t o o p t i m i z e t h e

l u b r i c a n t w i t h r e s p e c t t o t h e s u r f a c e f i n i s h a n d p o w e r

c o n s u m p t i o n .

C

C h u c k r o t a fe a b o u t

i t s ax i s Z

I I -- I'/ /15.~ -L,.~--)---~.

II ROLLE

-

D)

Fig. 3. Tube -spinn ing arran gem ent (1, grippe r chuck ; 4, rolle r; 10, load cell; 12, work piece ; 13, ma ndre l; 14, key; 15, clam ping ring).



R. Prakash, R .P. Singhal / Journal o f Materials Processing Tec hnology 54 (1995) 186-192 189

4.

[ - -

/ ( ~ 4.1. Set-up or spinning

/ @ (i) P re f o r m

t ; i

i i q

, I ~ [ ,

~ J / / / / ~ (ii) P e r ip h e r a l sp eed

of ro l lers

] i I ; ' , , , , ' - ~ 5 2 f f ( ii i) F eed ( P u l l in g s p eed )

L_. '- - ( iv) Lu br ic ant

I

Fig . 4 . Rol ler asse mb ly with the feed screw. (2 , f ixed s lide; 2a, move abl e

s l ide; 4 , ro l ler w ith brg; 12 , workp iece; 13 , screw for feed) .

( v i ) M an d r e l

L e n g t h

I n s id e d i a m e t e r

Wal l t h i ck n es s

Surface f in ish

C o n c e n t r i c i t y

M a n d r e l

T u b e

M a t e r i a l

H a r d n e s s

D i a m e t e r

N u m b e r

D i a m e t e r

L e n g t h

H a r d n e s s

Surface f in ish

8 0 0 m m

1 8 m m

4 m m

as mach in ed ( 3 to

5 g in)

w i th in 0 . 2 mm

1 3 0 m/min .

7 5 0 m m / m i n , m a x .

N ev e r s e i ze

( co mmer c ia l n ame)

S i l i con g r eas e w i th

g r a p h i t e p o w d e r

a d m i x e d 1 0 % s o l u b l e

o i l i n w a te r

A I S I D 2

58 Rc

8 0 m m

th r ee a t 1 2 0 ° i n t e r v a l

1 7 .8 mm

1 0 0 0 0 m m

5 5 R c ( b y co ld w o r k in g )

0 .5 gm

T h e f o l l o w i n g l u b r i c a n t s , i n a d d i t i o n t o t h e N e v e r

s e iz e o n t h e m a n d r e l a n d t h e 1 0 % s o l u b l e oi l o n r o l l er s ,

were iden t i f i ed .

( 1) L u b k o t e ( p r o p r i e t a r y i t e m , g r a p h i t e p o w d e r i n

mineral oi l ) .

T a b l e 1

Lu b r i can t : Lu b k o te ( g r ap h i t e ad m ix ed w i th m in e r a l o i l) (1 k g f /mm 2 = 0 . 1 M P a )

R e d u c t i o n H a r d n e s s U T S 0 . 2 % E l o n g a t i o n S u r fa c e

( % ) ( mV P N ) ( k g f /mm 2 ) p r o o f s t r e s s ( % ) f in i s h

(kgf /m m 2) (g in)

D i m e n s i o n s

( m m )

60 413 120.6 not reco rded 12.3 0 .8 OD 20.90

(42Rc) ID 17.78

75 440 138.9 9.4 0.6 O D 19.82

(44.5Rc) ID 17.85

90 460 64.0 4.3 0.6 O D 18.63

(46Rc) ID 17.93

Tab le 2

Lu b r i ca n t : Gr ap h i t e p o w d er in ca s to r o i l ( 1 k g f /mm 2 = 0 . 1 M P a)

R e d u c t i o n H a r d n e s s U T S 0 . 2 % E l o n g a t i o n S u r fa c e

( % ) ( mV P N ) ( k g f /mm 2 ) p r o o f s t r e s s ( % ) f in i s h

(kgf /mm e) (gm)

D i m e n s i o n s

( m m )

44 378.4 113.6 102.0 12 0.65

(38.5Rc)

50 395.2 118.4 104.6 12 0.80

(40.5Rc)

60 407 121.3 105.0 12 0.65

(41.5Rc)

70 438 132.9 110.0 11 0.80

(44.5Rc)

80 452 143.8 119.8 10 0.65

(45Rc)

OD 22.00

ID 18.10

OD 21.55

ID 18.12

OD 21.04

ID 18.14

OD 20.33

ID 18.22

OD 19.50

ID 18.30



190 R. Prakash, R.P. Singhal / Journal o f Materials Processing Technology 54 (1995) 186-192

( 2) G r a p h i t e p o w d e r ( 3 2 5 m e s h ) c a s t o r o i l a d m i x e d t o

p r e p a r e a m i x t u r e i n t h e f o r m o f a p a s t e .

( 3) O x a l a t e c o a t i n g a c h i e v e d b y a c h e m i c a l r e a c t i o n a t

9 0 1 0 0 ° C w i t h k n o w n c h e m i c a l s ( b o u g h t f ro m M / s

P y r e n e R a i , B o m b a y ) h a v i n g l u b r i c i t y .

( 4 ) M o S 2

p o w d e r ( 3 2 5 ) a d m i x e d i n c a s t o r o i l t o p r e -

p a r e a m i x t u r e i n t h e f o r m o f a p a s t e .

( 5 ) C o p p e r c o a t i n g b y t h e e l e c tr o - d e p o s i t i o n m e t h o d .

T h e r e s u l ts a r e g i v e n i n T a b l e s 1 - 5 . T h e m i c r o h a r d n e s s

r e a d i n g s w er e t a k e n a t 1 0 0 g m l o a d a n d t h e s u rf a ce

f i n i s h e s a r e a l l s p e c i f i e d a s ' R a ' v a l u e s , t h e s u r f a c e r o u g h -

n e s s b e i n g m e a s u r e d o n p i e c e s c u t f r o m s p u n s a m p l e s

w i t h d i f f e r e n t r e d u c t i o n s u s i n g 2 P e r t h o m e t e r , a s t y l u s -

t y p e o f s u r fa c e - r o u g h n e s s m e a s u r i n g i n s t r u m e n t . T h e i n -

s i d e d i a m e t e r w a s m e a s u r e d w i t h a t h r e e - a n v i l i n t r a m i k

( i n s i d e m i c r o m e t e r ) , l e a s t c o u n t o f 0 . 01 m m , a n d t h e o u t -

s i d e d i a m e t e r w a s m e a s u r e d w i t h e x t e r n a l m i c r o m e t e r ,

a l s o o f le a s t c o u n t o f 0 . 01 m m . T h e d i a m e t e r s w e r e m e a s -

u r e d a t b o t h e n d s a n d t h e a v e r a g e d i a m e t e r p r e s e n t e d

i n d i c a t e d i n t h e r e s u l t s .

5 . O b s e r v a t i o n s

B a s e d o n t h e o b s e r v a t i o n s i t c a n b e s a i d t h a t t h e

m i c r o h a r d n e s s d o e s n o t c h a n g e a p p r e c i a b ly a ft er a r e-

d u c t i o n o f a b o u t 6 0 % . W i t h t h e u s e o f d if f er e n t lu b r i -

c a n t s t h e s ur f a c e f i n i s h o n O D o f t h e t u b e i m p r o v e d b u t

d i d n o t s h o w a n y r e a l l y s i g n i f i c a n t c h a n g e , r e m a i n i n g

b e t w e e n 0 . 5 a n d 0 . 8 l am ( R a v a l u e s ) . I t i s c o n c l u d e d t h e r e -

f o r e , t h a t a l u b r i c a n t i s d e s i r a b l e t o c a r r y a w a y t h e h e a t

g e n e r a t e d d u r i n g s p i n n i n g a n d t o i m p r o v e t h e s u r f a c e

T a b l e 3

L u b r i c a n t : O x a l a t e c o a t i n g ( 1 k g f / m m 2 = 0 .1 M Pa)

R e d u c t i o n H a r d n e s s U T S 0 . 2 %

( % ) ( m V P N ) ( k g f / m m 2 ) p r o o f s t r e s s

( k g f / m m 2 )

E l o n g a t i o n S u r fa c e D i m e n s i o n s

{ % ) f i n i s h ( m m )

(p.m)

49 373 116.0 105.8 12.5 0.65 O D 21.72

(38.5R c) 1D 18.15

68 401 127.2 109.4 12.0 0.60 O D 20.44

(41Rc) ID 18 .16

83 432 136.7 116.0 11.0 0.50 O D 19.35

(43 .5Rc) ID 18 .30

T a b l e 4

L u b r ic a n t : M o S 2 a d m i x e d w i t h c a s t o r o i l ( 5 0 : 5 0 ) ( 1 k g f / m m 2 = 0 . 1 M P a )

R e d u c t i o n H a r d n e s s U T S 0 . 2 % E l o n g a t i o n S u r f a c e

( % ) ( m V P N ) ( k g f / m m z ) p r o o f s t r e s s ( % ) f i n is h

( k g f / m m 2 ) ( p m )

40 356 110.6 97 .0 13 0 .75 O D

( 3 6 . 5 R c ) I D

50 378 .3 113 .0 97 .8 12 0 .65 O D

( 3 8 . 5 R c ) I D

61 408 .0 122.4 98 .7 12 0 .70 O D

( 4 1 . 5 R c ) I D

73 438 .0 133.3 100.9 Sa mp le 0 .75 O D

( 4 4 .5 R c ) t e a r e d I D

D i m e n s i o n s

( m m )

22 .30

18.10

21 .67

18.16

20 .90

18.16

20 .06

18.25

T a b l e

5

L u b r i c a n t : C o p p e r c o a t i n g ~ ( t h i c k n e s s 0 . 0 1 m m ) ( 1 k g f / m m 2 = 0 . 1 M P a )

R e d u c t i o n H a r d n e s s U T S 0 . 2 % E l o n g a t i o n S u r f a c e

( % ) ( m V P N ) ( k g f / m m z ) p r o o f s t r e s s ( % ) f i n is h

(kg f /m m z) (p .m)

53 378.4 108.9 95.0 12 0.85

(38 .5Rc)

68 425.6 123.2 107.0 C o u l d n o t 0 .95

( 4 2 . 5 R c ) b e m e a s u r e d

81 438 .0 137.5 116.9 11 0.95

(44 .5Rc)

O D

I D

O D

I D

O D

I D

D i m e n s i o n s

( m m )

21.41

18.12

20 .37

18.15

1 9 . 4 2

18.36



R. Prakash, R.P. Singhal / Journal of Materials Processing Technology 54 (1995) 186-192

191

f in is h . D i f f e r e n t l u b r i c a n t s d o n o t s h o w a n y c h a n g e i n t h e

r e s u l t s a n d s o a n y g o o d g r e a s e c a n b e u s e d a s l u b r i c a n t

o n t h e o u t s i d e d i a m e t e r o f t h e t u b e . T e n p e r c e n t s o l u b l e

o i l i s a d e q u a t e o n t h e r o l l e r s t o c o o l t h e m d u r i n g t h e

p r o c e s s .

T h e s u r f a c e f i n is h i s o f th e o r d e r o f 0 . 9 5 g m , w h i c h

i s c o m m e r c i a l l y a c c e p t a b l e a n d c a n b e o b t a i n e d e a s i l y .

T h e c o n c e n t r i c i ty w a s f o u n d t o b e 8 % o f th e w a l l th i c k -

n e s s o f t h e s p u n t u b e . T h e o u t s i d e d i a m e t e r c a n b e

c o n t r o l l e d t o w i t h i n 0 . 0 5 t o 0 . 0 8 m m w i t h t h e h e l p o f

t h e m i c r o m e t e r s c r e w s u s e d f o r d r i v i n g t h e r o l l e r s . T h e

p r e c i s i o n - g r o u n d m a n d r e l e n s u r e s t h a t t h e i n s i d e d i a -

m e t e r c a n b e m a i n t a i n e d w i t h i n t h e l im i t s o f c o m m e r c i a l

t o l e r a n c e s .

T h e m e c h a n i c a l p r o p e r t i e s w e r e i m p r o v e d c o n s i d e r -

a b l y , a s e x p e c t e d . T h e t e n s i l e s t r e n g t h o f t h e s t a i n l e ss

s te e l A I S I -3 0 4 i n c r e a s e d f r o m 6 5 k g f / m m 2 t o a b o u t

1 4 5 k g f / m m 2 a t a b o u t 8 0 % r e d u c t io n a n d t h e

y i e ld s t r e n g t h ( 0 . 2% p r o o f s t re s s) f o r m 4 4 k g f / m m 2

t o a b o u t 1 3 5 k g f / m m 2. T h e d u c t i li t y d e c r e a s e d t o

b e l o w 1 0 % .

A m a x i m u m r e d u c t io n o f 8 0 % m a y b e p l a n n e d

s a fe l y a n d m a y b e a c h i e v e d w i t h o u t i n t e r m e d i a t e a n n e a l -

i n g . A n 8 3 % r e d u c t i o n s a m p l e o f st a i n le s s s te e l

d e v e l o p e d c r a c k s i n o n e o f th e e x p e r i m e n t s . I f th e

f i n i s h e d s i ze o f t h e t u b e c a n n o t b e a c h i e v e d w i t h u p t o

8 0 % r e d u c t i o n , t h e t u b e s h o u l d b e r e m o v e d f ro m t h e

m a n d r e l a n d a n n e a l e d b e f o r e c o n t i n u i n g w i th t h e p r o c e s s

f u r t h e r .

T h e s p e e d , t h e f e ed a n d t h e r o l l e r p r o f i l e a r e o t h e r

f a c t o r s w h i c h , a p a r t f r o m a f f e c t i n g t h e s u r f a c e f in i s h o n

t h e s p u n t u b e , a f fe c t t h e p r o d u c t i o n c a p a b i l i t y o f t h e

m a c h i n e . T h e m a x i m u m s p e e d s a r e n o t c r i t i c a l i n t h e

s h e a r s p i n n i n g p r o c e s s , b u t f e e d h a s a m a r k e d e f f ec t o n

t h e s u r f a c e f i n i s h o f t h e s p u n t u b e . I f th e f e e d r a t e i s

i n c r e a s e d t h e s u r f a c e f i n i s h b e c o m e s c o a r s e r . T h e r e f o r e ,

a c o m p r o m i s e h a s t o b e e s t a b li s h e d b e t w e e n t h e f e e d , t h e

s p e e d a n d t h e r o l l e r p ro f il e s k e e p i n g t h e p r o d u c t i o n

c a p a b i l i t y , t h e s u r f a c e f i n is h o n t h e s p u n p r o d u c t a n d t h e

p r o d u c t m i x i n v i e w .

T h e t e c h n o l o g y is e c o n o m i c a l l y v i a b le , e s p e c ia l ly w h e n

t h e v o l u m e o f p r o d u c t i o n i s l o w , b e c a u s e o f t h e f lo w c o s t

o f e q u i p m e n t a s a g a i n s t t h e c o s t o f c o n v e n t i o n a l t u b e -

m a k i n g p r o c e s s e s , v i z . h o t e x t r u s i o n o r p i e r c i n g f o l l o w e d

b y d r a w i n g o r p i l g e r i n g , w h i c h a r e h i g h l y c a p i t a l i n t e n -

s iv e . F u r t h e r t h e y i e l d o f t h e f i n i s h e d p r o d u c t i n t h e c a s e

o f t h e c o n v e n t i o n a l p r o c e s s e s e s p e c ia l ly w h i ls t w o r k i n g

w i t h h a r d - t o - w o r k m a t e r i a l s , is v e r y l o w , r e s u l t in g i n

h i g h e r c o s t o f c o n v e r s io n . T h i s is s u b s t a n t i a t e d f u r t h e r

d u e t o : ( i) t h e r e d u c t i o n p e r p a s s i n t h e c a s e o f s p i n n i n g

b e i n g a s h i g h as 4 0 % a g a i n s t a r e d u c t i o n o f 1 0 - 1 5 % i n

c o n v e n t i o n a l p r o c e s se s , (ii) t h e m a x i m u m r e d u c t i o n b e -

f o r e i n t e r m e d i a t e a n n e a l i n g b e i n g a b o u t 8 0 % a g a i n s t

4 0 - 5 0 % i n th e c o n v e n t i o n a l p ro c e s s , r e s u lt i n g in a n

h i g h e r d i s c a r d o f t u b e a t t h e l e a d i n g e n d d u e t o s u c c e s si v e

p o i n t i n g ; a n d ( iii ) t h e n u m b e r o f d r a w i n g p a s s e s t o o b -

t a i n f in a l d i m e n s i o n s b e i n g g r e a t e r in t h e c a s e o f c o n v e n -

t i o n a l p r o c e s s e s t h a n i n s p i n n i n g r e s u l t i n g i n h i g h e r c o s ts

o f th e c o n v e r t i o n .

6. Conclus ions

W i t h t h e f o r e g o i n g d i s c u s s i o n o f t h e r e s u l t s, i t is c o n -

c l u d e d t h a t t h e t e c h n o l o g y o f m a n u f a c t u r i n g s e a m le s s,

l o n g , t h in - w a l l t u b e s h a s b e e n d e v e l o p e d f o r s p e c if i c

u s a g e . T h e m a i n f e a t u r e o f t h e t e c h n o l o g y a r e a s f o ll o w s .

(1 ) T h e m e c h a n i c a l p r o p e r t i e s o f t h e s h e a r s p u n t u b e

i m p r o v e c o n s i d e r a b l y .

(2 ) A t o t a l r e d u c t i o n o f 8 0 % c a n b e a c h i e v e d w i t h o u t

i n t e r m e d i a t e a n n e a l i n g . T h e r e d u c t i o n is , h o w e v e r , a c h -

i eved i n s eve r a l pas ses .

(3 ) C o o l a n t a n d l u b r i c a n t s a r e n e c e s s a ry f o r i m p r o v -

i n g t h e f i n i s h , a n d t o c a r r y a w a y t h e h e a t g e n e r a t e d

d u r i n g t h e p r o c e s s . D i f f e r e n t l u b r i c a n t s d o n o t h a v e s i g -

n i f ic a n t ef fe c ts o n t h e p o w e r c o n s u m p t i o n , t h u s a n y

g o o d - q u a l i t y g r e a s e c a n b e u s e d in a d d i t i o n t o t h e c o o l -

an t .

( 4 ) T h e d i m e n s i o n a l t o l e r a n c e s b o t h o n t h e o u t s i d e

a n d t h e i n si d e d i a m e t e r o f t h e s p u n t u b e a r e b e t t e r t h a n

t h o s e a c h i e v e d b y a n y o t h e r t u b e - m a k i n g p r o c e s s , a n d

t h e c o n c e n t r i c it y is w i t h in c o m m e r c i a l l y - a c c e p t a b l e

l imi t s .

Ac kno w l e dg e me nt s

T h e s e c o n d a u t h o r is g ra t e fu l t o t h e D i r e c t o r , N P L , f o r

p e r m i s s i o n t o p r e s e n t t h i s p a p e r . H e i s g r a t e f u l t o t h e l a te

D r . B . K . A g g a r w a l a , E x - d e p u t y D i r e c to r , N P L , N e w

D e l h i f o r h i s g u i d a n c e . H e w o u l d a l s o l i k e t o p l a c e o n

r e c o r d t h e h e l p r e n d e r e d b y s e v e r a l c o l l ea g u e s w o r k i n g i n

t h e w o r k s h o p , d e s i g n o f f ic e a n d m e t a l f o r m i n g s e c t i o n s o f

N P L . T h e a u t h o r s a r e th a n k f u l t o U N D P f o r p r o v i d in g

t h e s p in n i n g m a c h i n e f o r N P L , w i t h o u t w h i c h t h i s w o r k

w o u l d n o t h a v e b e e n p o s s i bl e .

References

[ 1 ] S . K a lp ak c io g lu , O n th e mech an ic s o f s h ea r s p in n in g ,

J. Eny.

Ind ., Trans. AS M E,

83 (1961) 125-130.

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d u c t io n En g in ee r in g R es ea r ch ( C I R P ) , P r ag u e , C zech o s lo v ak ia ,

1961.

[ 3 ] S . K a lp ak c io g lu , M ax im u m r ed u c t io n in p o w er s p in n in g o f t u b es .

J . o f Eng . Ind ., Trans. A SM E,

86 (1964) 49 54.

[ 4 ] M e ta l s H a n d B o o k , V o l . I V , A m er ican S o c ie ty f o r M e ta l s , M e ta l s

Park , OH-44073, 8 th ed . , USA, 1969 p .p . 201-208 and 317-322.

[ 5 ] M e ta l s p in n in g , M ac h in e r y ' s Ye l lo w B ack S e r i e s N o . 7 , Th e M a-

ch in e r y P u b l i s h in g C o . L td . , Lo n d o n .

[ 6 ] T . R am M o h a n an d R . M is r a , S tu d ie s i n p o w er s p in n in g o f t u b es ,

Int. J. Prod. Res.,

10 (4) (1972) 351-364.



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I-7] M. H aya ma an d H. Kudo, Experim ental s tudy of tube spinning,

B u l l . J S ME ,

22 (167) (1979) 769 775.

1-8] M. Ha yam a and H. Kudo , Analysis of d iametral g rowth an d

workin g forces, B u l l . J S ME , 22 (167) (1979) 776-784.

[9] B.K. Aggarwala , The shear spinning technology of tubes wi th

high dimensional precision,

Proc. Adv. Techn . Plast ic i ty ,

1 (1984)

pp. 401,409.

[10] R.P . S inghal, S .R. Das and Rajnish Prakash, Som e experimental

observat ions in the shear spinning of long tubes,

J . Me c h . Wo rk .

Techn . ,

14 (1987) 149-157.

[11] R.P . S inghal and R ajnish Prakash, An experimental s tudy of the

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Proc. Adv.

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2 (1990) 853 857.

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