Function of the couplings in modern drives of mining machines

zeszrar kauxoto po l x t e c h n ik i

S o r i a ! CM5rNICTVO z. 180

_________1989 Nr k o l.i0 < * 3

INTERNATIONAL CONFERENCE: DYNAMICS OF |MjINING MACHINES DYNAMACH '8 9

S y l v e s t e r MARKUSXK T r a n s p o r t D ep a rta m en t

S i l e s i a n U n i v e r s i t y o f T e c h n o lo g y

FUNCTION OF THE COUPLINGS IN MODERN DRIVES OF MINING MACHINES

Summary. T h is a r t i c l e p r e s e n t s s e l e c t i o n p r i n c i p l e s o f t h e ty p e o f c o u p l i n g s f o r d r i v e s o f m in in g m a c h in e s 1f o r ex a m p le: c o n v e y o r s , p lo u g h s o r v i b r a t i n g s c r e e n s . I t h a s b e e n s t a t e d , t h a t s t a r t i n g c o u p l i n g s i n t h e d r i v e s o f t h e b e l t an d s c r a p e r c o n v e y o r s c a n b e i n many c a s e s r e p l a c e d b y c h e a p e r p erm a n en t f l e x i b l e c o u p l i n g s , t h a t a r e p r o d u c in g i n P o la n d , O v e r lo a d c o u p l i n g s i n th e s c r a p e r c o n v e y o r s an d c o a l p lo u g h s s h o u ld b e l o c a t e d on s lo w s p e e d s h a f t o f t h e d r i v e b u t t h i s c o n d i t i o n r e q u i e r s c r e a t i n g a new c o n s t r u c t i o n o f h ig h to r q u e o v e r l o a d c o u p l i n g s ,

INTRODUCTION

I n t h e d r i v e s o f t h e m in in g m a c h in e s f o r e x a m p le : c o n v e y o r s o r p lo u g h s in t h e c o a l - m i n i n g m o st o f t e n u s e d a r e c a g e e l e c t r i c e n g in e s and make s t a r t e a s i e r i n t h e c a s e o f b i g p ow er d r i v e s - s t a r t i n g c o u p l i n g s . I n th e d r i v e s , due t o many a p p e a r in g d y n a m ics o v e r lo a d s com in g from w ork m a c h in e ,

¡so u p lin g s h o u ld h a v e th e l e a d o f m ech a n ic " s a f e t y d e v i c e " . The c h a r a c t e r of s t a r t i n g b e l t and s c r a p e r c o n v e y o r s d ep en d l a r g l y on d r i v e c h a r a c t e r i s ­ t i c , ch a n g e o f t h e f o l l o w i n g w ork p a r a m e te r s i n tim e : e l e c t r i c e n g in e , c o u p li n g and moment o f r e s i s t a n c e , U n p r o p o r t io n s t e r e s i s t a n c e moment com ing from : w ork m a ch in e ( f o r e x a m p l e : s t r i k e s o f t h e lump o f c o a l f o r i d l e r s , u n e q u a l f e e l i n g up th e c h u t e s , e t c , ) , e l e c t r i c e n g in e (d yn am ic c h a r a c t e r i s t i c ) , s h o u ld b e " f i l t e r e d " b y t h e c o u p li n g . C o m p lic a te d dyna­

m ics p r o c e s s e d i n t h e s l e c t r o m e c h a n i c s y s t e m s ( g e n e r a l i n th e sy s te m : e n g in e - w o r k m a c h in e ) r e q u i r e c a l l i n g s p e c i a l a t t a n t i o n t o t h e l e a d o f c o u p li n g i n t h e d r i v e j^L. 2 J . I n t h e c a s e when u n p r o p o r t io n a t e r e s i s t a n c e moment from work m a ch in e a c h i e v e s b i g v a l u e s , i n m ech a n ic d r i v e s o f c o a l m a c h in e s , m u st b e s i t u a t e d on s u i t a b l e s t a g e o f t h e g e a r - o v e r l o a d cou p ­ l i n g . I n t h e d r i v e s of b e l t c o n v e y o r s we d o n ' t u s e o v e r lo a d c o u p l i n g s , because the lead of "safety device" i s p la y e d b y f r i c t i o n c o u p li n g b etw een t h e pulley drive and the belt. As for today’ c o n s t r u o t io n a overload

106 S. Marfcuaik

c o u p lin g » have b een u sed : f l u i d c o u p lin g « o r f r i c t i o n c l u t c h . T h ese coup­

lin g « was b een s i t u a t e d in th e d r iv e moat o f t e n be tween e l e c t r i c e n g in e and h ig h sp eed s h a f t o f th e to o th e d g e a r . L o c a tio n o f th e o v e r lo a d coup­

l i n g on t h e h ig h sp e e d s h a f t o f th e j d r iv e p r o t e c t s from o v e r lo a d o n ly th e e l e c t r i o e n g in e . The o h o io e o f s u i t a b l e ty p e s o f c o u p lin g s and p la c e s o f t h e i r lo c a t i o n i n th e d r iv e s o f s c r a p e r co n v e y o r s (or A.FĆ) and p lo u g h s , has a d e c i s i v e im p ortan ce i n c o r r e c t end r e a l i e b l e work o f t h e s e m a ch in es.

STARTING COUPLINGS FOR ¡BELT AND SCRAPSR CONVEYORS

As th e s t a r t i n g c o u p lin g s in t h e s e m ach ines many y e a r s we h ave been u s in g f l u i d ( h y d r o c in e t i c ) or more o f t e n powder c o u p lin g s ( s p e c i a l l y i n power in d u s t r y ) £ l . ¿ ] . I t i s u s in g f o r d r iv e s o f power o v e r 1*0 k ¥ . ¥ e h a v e n 't g o t any t e c h n i c a l p r e m ise s f o r r i g i d keep o f t h i s u sa g e o f th e b o rd er f o r s t a r t i n g c o u p lin g s . In many t e c h n i c a l works h as b een a s c e r ­

t a in e d £ l . 2J , th a t c h o ic e o f c o u p lin g ty p e f o r th e d r iv e sh o u ld be a n a ly ­ s e d i n d y v i d u a lly , d ep en d in g o f th e k in d o f m achine and c o n d it i o n s o f i t s s t a t e and s t a r t i n g work. T h is i s due to th e u sa g e o f s t a r t i n g c o u p lin g d e c id in g o n ly mass o f i n e r t i a . The d r iv e sh o u ld d u r in g th e s t a r t i n g tim e a c c e l e r a t e t h i s mass g e t o v e r and o v e r b a la n c e th e m otor moment o v e r th e r e s i s t a n c e moment o f th e work m ach in e. B ig power d r iv e s i n s lo p e co n v ey o rs but r a t h e r s h o r t may have perm anent f l e x i b l e c o u p lin g s , b e c a u se a la r g e p a r t o f e n g in e power i s p r e d e s t in a t e f o r l i f t i n g th e mass on d e f i n i t e v a l t l t u d e and o n ly r e s t o f t h a t power i s u se d f o r overcom in g i n e r t i a o f th e co n v e y o r . The c o n fir m a tio n o f n e c e s s i t y o f u s in g th e d r iv e s t a r t i n g c o u p lin g , can be o b ta in e d by num bering s im u la t io n o f th e work c o n d it i o n s o f th e m ach ine, t h a t was done on th e exam ple o f b e l t co n v e y o r s b y means o f com puter program SYPTA-8 3. S y m u la tio n programs due to th e enormous d evelopm ent o f com p u ters, s p e c i a l l y m icro co m p u ters, become su p p o r te r t o o l s f o r d e s ig n e r s and u s e r s o f th e s e m a ch in e s. E x p e r ie n c e s b a se d on a p p li c a t io n o f h ig h f l e x i b l e c o u p lin g s such aa ZERKOPOL ( f i g . 1 , t a b . l ) i n d r iv e s o f sc r a p e r co n v ey o rs ( AFC) i n th e "Knurov" M ine, a llo w to assume t h a t in th e m achines o f b i g dynam ic, i n th e s t a r t i n g and c o n s t a n t p e r io d , we c a n u se s u e c e s f u l i y permanent f l e x i b l e c o u p li n g s i n s t e a d o f ( f l u i d ) ( d y d r a u l i o ) c o u p l i n g s .

B ut w hat k in d o f f e a t u r e s s h o u ld th e f l e x i b l e c o u p li n g h a s , t h a t we can u se i n t h e d r iv e i n s t e a d o f s t a r t i n g c o u p lin g ? T e c h n ic a l p a r a m e te r s o f t h i s c o u p l i n g sh o u ld mark h ig h e l a s t i c i t y o f c cranec t o r s ( b i g a n g le o f t o r s io n ) and l a r g e f a c t o r o f dumping. Of c o u r s e , f o r th e p rogram s o f co m p u ter sy m u la tio n i t i s n e c e s s a r y t o h a v e th e k n o w leg e o f dynam ic c h a r a c t e r i s t i c s o f th e f l e x i b l e c o u p lin g . U t i l i t y v a lu e s o f th e f l e x i b l e c o u p lin g a r e th e f o llo w in g : h ig h d u r a b i l i t y o f th e counce t o r e s and s e r v ic e

s i m p l i c i t y , f o r exam pia: rep la cem en t o f th e v ea r o d co m m otor w ith o u t th e u n e c e s s it y o f p u t t i n g away th e e n g in e .

function of the o m g j j j g i in... 109

a) ^b)

d )

F ig . 1. C o n str u c tio n o f th e f l e x i b l e c o u p lin g s f o r s h a f t s

a - w ith r a d i a l disassembly co n n e c to r s (ty p e TS 130 - ZERKOPOL) , b - with a x ia l d is a s s e m b ly c o n n e c to r s ( t y p e TS 2Ù0 - ZERKOPOL) , c - membrane coup­

l i n g , d - p in s (b u s c h e s ) c o u p lin g

Couplingsinthsdrivssofths

.110 S. M&rtcusik

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Function of the couplings in,,

111 I t i s a l s o im p o r ta n t, t h a t th e p r ic e o f th e f l e x i b l e c o u p lin g s a r e low er than th e p r i c e o f s t a r t i n g c o u p lin g s , u se d now. T ab le 1 p r e s e n t s u se areas o f p a r t i c u l a r ty p e s and s i z e s o f c o u p lin g s f o r d r iv e s o f m achines u sed i n c o a l and s t r i p m in in g . P r e s e n te d f l e x i b l e c o u p lin g s o f ZERKOPOŁ ( f i g . 1 a and b ) i n th e t a b le 1, d o n 't show a l l th e ty p e s o f permanent f l e x i b l e c o u p lin g s ( f o r exam ple: f i g . 1 c and d ) , produced in Poland now.

On p r i n c i p l e , pem am ent f l e x i b l e c o u p lin g i n b i g power d r iv e o f work machine sh o u ld have h ig h e l a s t i c i t y and dumping. H igh l e v e l o f e l a s t i c i t y makes t h a t o r i t i c a l sp eed r o t a t i o n n ^ . o f d r iv e i s to be under i d l e running o f m ach ine. H igh dumping in th e c o u p lin g makes i t p o s s ib le to g e t sm all a m p litu d e s o f v i b r a t i o n , t h a t have evok ed by i r r e g u l a r i t i e s o f r o ­ t a t i o n . T h is f e a t u r e i s in p a r t i c u l a r im p ortan t when r o t a t io n c r o s s in g through r e so n a n c e a r e a , but i n th e o v e r c r i t i c a l a r e a sm a ll dumping i s p r o f i t a b l e . Requirem ent o f h ig h t o r s io n e l a s t i c i t y assumes th a t u s in g s o f t e la s to m e r f o r c o n n e c to r s o f c o u p lin g w hich alw ays g iv e s weak dumping.

These f e a t u r e s o f th e c o u p lin g d eterm in ed by i t s c h a r a c t e r i s t i c , th a t we d e s c r ib e by s t i f f n e s C and dumping K. The c h a r a c t e r i s t i c may be s t a t i c or dynam ic, d ep en d in g on to r q u e , w hich i s tak en in t o c o n s id e r a tio n

( f i B . 2 ):

With r e g a r d f o r t h e i r c h a r a c t e r i s t i c , c o u p lin g s may be o f c o n s ta n t s t i f f n e s ( f i g . 2 ) , w ith dumping or n o t and n o n - lin e a r c h a r a c t e r i s t i c .

M I

D epending of th e k in d o f work machine and d r iv e e n g in e ( e l e c t r i c motor o r com b ustion e n g in e ) , th e in f lu e n c e o f c o u p lin g on n o n -c o n s ta n t c a r r y on to r q u e i s g r e a t .

For c o u p lin g w ith dumping by p r e l i ­ m inary s t r e s s , th e dynamio f a c t o r m u lt ip ly a m p litu d e o f v ib r a t io n i s :

F ig . 2 . C h a r a c t e r is t ic o f th e

f l e x i b l e c o u p lin g where: nn - nom in al r o t a t io n o f d r iv e , n ^ - r o t a t io n o f reson an ce sys­

tem.

Dumping f a o t o r o f f l e x i b l e o o u p lin g i s [ l.. lj ( f i g . 1 ):

112 S. Markua 11c w herei A^ - th® a r e a o f work dumping' d u r in g 1 c y c l e o f work,

Ag - th e a r e a of e l a s t i c d efo rm a tio n f o r 1 cycle of ^work.

For f l e x i b l e c o u p lin g s , su oh ZERKOPQL, th e dumping f a c t o r h as o b t a i­

ned Y 3' 1 , 0 5 , c o u p lin g s w ith rubber c o n n e c to r s

Y

* .

i/¡ ^ T T T s f

max If Y V

and i s 6 f o r ZEKKOPOL c o u p lin g s and 7 ,8 5 f o r ru b ber c o n n e c to r s c o u p lin g s ( ty p e SPP). From f ig u r e 3 we s e e , th a t h ig h e l a s t i c i t y c o u p lin g h as p r o f it a b le in f l u a n e e on dynamic p e c u l i a r i t i e s o f d r iv e sy stem o n ly than V < 1 , 1 , i t i s whom n ^ / n ^ 7> V ? .

The h ig h e l a s t i c i t y c o u p lin g sh o u ld s t i l l work on o v e r c r i t i c a l r o t a ­ t i o n (n ;> 350 rpm ), c r o s s in g reso n a n ce on th e b e g in n in g o f th e p e r io d o f s t a r t i n g , when dynamic moment i s n ' t to o h ig h .

OVERLGD COUPLINGS FOR SCRAPER CONVEYORS AND COAL PLOUGHS

In th e m achines w ith h y d r a u lic d r iv e s th e problem o f o v e r lo a d c o u p lin g d o e s n 't ap pear. T h is f u n c t io n h as b een dene b y o v e r flo w v a lv e l o c a t e d i n f r o n t o f work mechanism in th e p r e s s u r e n etw o r k . I n th e m echanic d r i­

v e s , th e problem o f o v e r lo a d s com ing from work m achine ( f o r exam ple!

e x c e p t io n a l c u t t i n g r e s i s t a n c e , s t a r t o f f u l l lo a d in g s c r a p e r co n v ey o r and so on) sh o u ld be s o lv e d b y l o c a t i o n o f o v e r lo a d c o u p lin g on th e s u i ­ t a b le s h a f t o f th e d r iv e . As f o r to d a y c o n s t r u c t io n s o f d r i v e s : sc r a p e r c o n v e y o r s , c o a l p lo u g h s , r e c la im e r s and w h eel e x c a v a to r s we u se th e f o l l o w i n g co u p lin g s¡p e r m a n e n t f l e x i b l e , f l u i d or m u lt ip le d ls o c u l t c h . T h ese c o u p lin g s are “s a f e t y d e v i c e ” o f th e d r iv e and th e y a r e lo c a t e d b e tw e e n e l e c t r i c e n g in e and h ig h sp ee d s h a f t o f th e to o th e d g e a r . The p r o b le m o f th e b e s t c h o ic e o f p la c e f o r o v e r lo a d c o u p lin g can b e s o lv e d o n ly b y means o f o v e r lo a d s s i z e a n a i y s s i s , t h a t occu r on th e s e p a r a te s s t a g e s o f t h e s e m echanism . Vhen we a c c e p t , t h a t a d r iv e o f th e m achine i s a system o f d o u b le m a sse s , th e n th e maximum lo a d moment i n t h i s sy stem w i l l be eq u a l ( f i g , k ):

J, *

M®ax “ ^op * M± s i n i cut — — — • V = M

J 1 + J 2

w h ere: — s t a t i c r e s i s t a n c e moment o f w ork m a ch in e d u r in g s t a r t i n g . F ig , 3 , M u lti f a c t o r o f v ib r a ­

t io n am p litu d e

Funotion of the coupling» in.. 113

Workmachine Engine

Fig. *». Drive model of conveyor or coal plough

In such e drive we define nominal factor of overload Y"1, that charac­

terize possibilities of overloading work machine and loading interval, where overload coupling should work [i,. 2^].

* _ !ta*

*1 " _op

Overload factor of drive has the shape:

- in the starting period on a first shaft of drive:

M

- ♦ I, I2 C— + X. I.

op . ?a it. - 1 I, + I, _{1 2} * 7 M op

in the brake period on a first shaft of drive:

I “5 _ * I ^_{2 M l R}

* i h * ---- X “h

^zr '“op

. 1 oph

X iT~~ l ~_{z r op} FT—

where:

Ms - moment o f a l e c t r i e e n g in e ,

Mg - brake moment,

Xzx,=I1+ I 2 - red u ced moment o f i n e r t i a ( f i g . U ),

Moph ” r ®s i * ta n c ® moment o f m achine d u rin g b ra k in g .

D uring s t a r t i n g m ost o v e r lo a d s i n th e d r iv e w i l l occu r on th e en gin e s h a ft, when i t g e t s maximum moment. In th e brake p e r io d , i n th e mechanism w ill ta k e p la c e th e a c t i v e r e s i s t a n c e moment M0pij» i t comes from la r g e moment o f i n e r t i a o f work m achine. Stream o f power flo w s in t h i s c a s e , from th e work m achine to th e b ra k e. Overload f a o t o r o f d r iv e on *i* s t a g e of d r iv e , d u r in g b rek in g period will be equal:

11* S. Markuslk

F ig . 5 . O verload coupling of the Vestfalia Liinen Company (Vest Germany)

Function of the couplings 1b.. ₁₁₅

Styk ato SUrkKa ro

tłącsnika zewrzeć

\

\

Slyf ' Oo Wi Silmka ro

yiqczntha zewrzeć

sygnał przeciążana do innej przekładni

przestać

___

\

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•

iygnat przeciążenia do innej przekfodrH

przestać

Sprzęgło Sprzęgło

za sp rzę$ (tć zasprzęgtić

Styk wyłącznika Styk wyłącznika

Silnika zewrzeć silnika zewrzeć

■

.

im pulsy

N a p ę d Napęd

u su n ą ć

g ł ó w n y

'

pomocniczy

Słrugtem Si m ę te m

pracow ać pracow ać

Fig. 6. Prinoipla algorithm of the overload coupling in drive of coal plough«

1 1 6 S. Markusik

H_{In — x}

ioph = 1 ? m * *1

This formula shows tha necessity of loo a ting the overload ooupling on slow speed shaft (the closest to work mechanism), specially In machines of big moment of Inertia and small efficiency of these mechanisms. Small efficiencies of mechanisms are result multistage toothed gears using In drives (for example differential gears). It is due to the of neoessity assuring minimal rotation speed of the work mechanism. Using overload coupling on a alow speed shaft of the drive require building new genera­

tion of overload couplings with Immense torque (Mm = 25 - 200 kNm).

Some companies specialising In overload couplings already have first new oonstruotion of these couplings. For example, Westfalia Lunen Company

(Vest Germany) In the new construction of coal plough use overload coup­

ling (fig. 5) located on last shaft In the gear of drive. It's multi—

pledisc coupling with control torque. Functioning algorithm of this coupling In the drive of plough can be see on fig. 6.

Fig. 7. Shams of hydraulio control by moment of the overload coupling

« g tq c rrx K c U n tetu ow y

Function of the couplings in,. 11?

S przęgło i w y łą c za snę

* i > °

| Hamulec i w łą c za się

Silniki wyłączają się

r

Sprzęgło t wyłącza się

S i > 0

\

H a m u le c 2

włącza się

'n i* o

Mmwltt i Hamulec 2

w yłącza się Strug gotowy w y łą c za Się

Sprzęgło i tfo pracy S p r z ę g ła !

w łącza się w łą c z a się

Fig. 8. Principle working of the overload coupling in drive of the coal p lo u g h s

1 1 8 S. Markusik

S tu d ie s on now con s tr u e t i o n o f h ig h moment o v e r lo a d c o u p lin g s a re c a r ­ r i e d i n some d e s ig n in g c e n t e r s i n P o la n d . Ve can a l s o f i n d o v e r lo a d cou­

p l i n g s , where c o n n e c to r s have th e sh ap e o f s m a ll g l o b u l e s , th e q u a n t it y o f p r e s s u r e to t h e d i s c s o f c o u p lin and q u a n t it y o f tourqu e i n th e cou­

p l i n g maybe c o n t r o l l e d , f o r ©rampie h y d r a u l i c a l l y ( f i g . 7 ) . Working p r i n c i p l e o f su ch c o u p lin g i n th e d r iv e o f c o a l p lo u g h can b e s e e on f i g . 8 .

CONCLUSIONS

- Using starting oouplings in drives of conveyor« and coal ploughs should follow starting analyssis of maximum loaded machines. Ve should oreat mathematical models of these machines and with the help of computer starting symulation oaloulate starting time. It permits that designer of the machine to deoide about the necessity of starting coupling application.

- In the oaee of short starting time of conveyor drive or plough we shoud use much cheaper permanent flexible couplings.

- Taking into consideration a large ununiform loading in scraper con­

veyors, coal ploughs and vibrating screen, we recommend using flexible oouplings with high elasticity (torsion angle

¥

ping factor or ZERKOPOL type. In drives of belt conveyors because of belt elasticity we can use simple and cheaper flexible couplings with connectors or joint flexible type SPP.

- Ve should creat Polish construction of overload coupling for scraper conveyors and coal ploughs that would have a big torque, which could be located on slow speed shaft of the drive.

l it e r a t u r a

[ij Markusik S.i Sprzęgła m ech a n iczn e. WNT, Warszawa 1979

[ 2 j Markusik S . i S p r z ę g ła rozruchow e 1 p r z e c ią ż e n io w e w napędach p r z e ­ nośników oraz stru g ó w . A u tom atyzacja i M ech an izacja G órnictw a n r 8

1988

.

Recenzent: P r o f , d r h a b . i n ż . J a n Grlaoz

Function of the coupllngs in.. 1t9

DOBÓR SPRZĘGIEŁ DO WSPÓŁCZESNYCH HAPĘDÓ¥ MAS ZYK GÓRNICZYCH

S t r e s z c z e n i e

¥ a r t y k u l e p r z e d s t a w io n o z a s a d y doboru ty p u s p r z ę g ł a do napędów m aszyn g ó r n ic z y c h t a k i c h j a k j p r z e n o ś n i k i , s t r u g i lu b p r z e s i e w a c z e . S tw ie r d z o n o , że s p r z ę g ł a ro z r u c h o w e w n a p ę d a c h p r z e n o ś n ik ó w taśm ow ych i z g r z e b ło w y c h można w w i e l u p r zy p a d k a ch z a s t ą p i ć dużo ta ń s z y m i s p r z ę g ła m i n i e r o ż ł ą c z o ­ nymi p o d a tn y m i produkow anym i w P o l s c e . S p r z ę g ła p r z e c i ą ż e n io w e w n ap ęd ach p r z e n o śn ik ó w z g r z e b ło w y c h o r a z w s t r u g a c h p ow in n y b yć u sy tu o w a n e na s t o p ­ n iu w olnoobrotow ym n a p ę d u , c o wymaga je d n a k s t w o r z e n i a n ow ej k o n s t r u k c j i s p r z ę g i e ł p r z e c i ą ż e n io w y c h wysokom om entowyeh.

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