Content .. 55 56 57 58 ..

Technology of watch production - part 57

pedal

The c a m shaft housing

( 5 )

is m ounted on the b as e . The following

working a s s e mblies o f the ma chine are m ounted on and inside the cams haft

housing b o dy : the worm s haft, the cams haft , the c utter and table l evers ,

and the tab l e - lifting l e ve r .

The s p indle head

( 6 )

is a cylindrical b o dy ins ide

which the cutte r s pindl e r e vo l ves in four b e a rings (s e e technical data ) .

T h e m ac hine is e quipped with t w o elect ri c motors . O n e m otor (Figure

22 )

d rives the cam shaft and is m o unted inside the b e d . The s econd motor
d rives the cutt e r s pindl e and is m o unted in the b ody of the head on a speci al

b ra c k e t . P u l l e y

( 1 , 2, 3 )

on the f i r s t m o to r d rives t h e reduction - gear pul

ley

(4, 5 , 6 )

through a round b e l t .

planetary trans m is s io n , consis ting of

the four gears

( 1 3 , 1 4 , 1 5 , 1 6 ),

with a trans mission ratio

1 : 3 . 8 7 ,

is m ount

ed inside pulley

(4, 5, 6 ).

Two brake pull eys

( 1 9, 2 0 )

are m ounted on the

reductio n - gea r s hafts .

21
22

Reduction-gear shaft

FIGURE

22 .

K i nematic diagram of the

S - 5 0

machine

The planetary gea r , intended to reduce the s p e e d of r otation of the r e

duction - gear s haft, consists of t h e two s u n gea r s ,

( 1 3 )

with

3 1

te eth and

( 1 6 )

with

teeth, a pinion and two b rake p ull eys .

The s un gear

( 1 3 )

and the b rake pull ey

( 1 9 )

are rigidly connected to each

o th e r , but revolve fre ely on the reduc tion-gea r s h af t .

two - s tep sp rocket

wheel

( 7 -

8 )

is rigidly c onnected with the s un gear

( 1 6 )

and the b rake

( 2 0 ) .

The th r e e - s tep pulley

( 4 , 5 , 6 )

i s the planet-pinion c a r d e r . T h e pinion

i n turn c ons ists of two ge a rs ,

( 1 4 )

with

t e eth and

( 1 5 )

with

3 1

teeth.

The reduc tio n - gear s haft drives the worm s h aft through the sp rocket

wheels

( 7 ), ( 8 ), ( 9 ), (1 0 )

and a rol l e r chain .

The worm s haft d ri ves the

c a m s haft through the worm

( 1 7 )

tooth ) a nd wheel

( 1 8 ) (45

teeth ) . Six dif

ferent c am s haft s p e e ds can b e achieved using the thre e - s tep pulley

(4 , 5, 6 )

a n d the two - s tep s p ro c ke t

( 7 -

8 )

Three cams a r e fitted on the ve rtic al

2 2 !1

c a m s haft . The upp e r flat cam

) controls the angul a r displacement of

the cutter s pindle . The m iddle c a m

(2 2 ), also a flat cam , c ontrols the

angul ar displ a c e m e nt of t h e table . The l o wer cam

3 ) , a bell cam , c ontrols

the vertical displ a c e m ent of the table when m il ling to various d ep ths .

The l o w e r cam

( 2 3 ) and cam ( 2 2 ) are one uni t . The table l ev e r ( 2 4 ) is

fas tened to the f ront p a r t of t h e m achine hea d . Its l o n g a rm h a s a prism atic
follower at its e xtrem ity, which i s p r e s s e d again s t c a m

(22 ) by a s p ring.

The s hort arm s upports the work tabl e . The work is mounted o n a s p e c ial

pin plate on the t ab l e and is p r e s s e d a gainst it by a cleat b y m eans of a

spe cial handl e .

Lever

( 2

)

whic h s upports the cutter s pindl e , i s m ounted o n the body

of the m ac hine head . Its l o n g a rm is equal in length to the l o n g arm of the
table l e ve r

( 2 4 ) and on its s hort arm are mounted the cutte r spindle and the

bracket with the electric moto r . The m o tor drives the spindle through pul

leys

( 1 1 )

and

( 1 2 )

and a round b e l t . Pulley

( 1 1 )

d rives the spindle t h rough

a c lutch in o r d e r to relieve the spindle of t h e b e nding m o m e n t f rom the belt.

Belt position

TABLE 4

Duration of cycles of the S-50 machine

Pulleys antl sprocket

heels

Ca mshaft

period

Ca111shaft

( tillle/cycle),

rp111

sec

95.G

0 . 63

1 .1 5

4 0

1 .5

33.5

1 . S

2 .76

4 .:!

Nu111bcr of
spi ntl le re

volutions
per calll

shaft re

volution

8100

4500

3-<00

2 900

H !OO

1 1 7 0

Leve r

( 2 6 ) is m ounted inside the body of the h ea d . One of its arms has

at its ext remity a roll e r follower in contact with the bell cam

( 2 3 ) . The

o the r  a rm  i s   in  contact  with  a  dis k  o n   the  tab l e   spindl e .   The  m achine  has
a djusting  fixtures  for  the  c o r r e c t   pos itioning  of  work  and  c utte r .   Data  on
the  m ac hine-cycle  duration  as  a  function  of  the  pos ition  o f   the  b el t   and  c hain
o n   the  pulleys  and  sp rocke t  wheel s  are  given  in  Tabl e

4 .

The c a m s haft s p e e d rem ains constant throughout the cycl e .

The ma chine i s s ta rted b y a rota ry s witch, which s ta rts both m o tors

s im ul taneously but does not s ta r t the cams haft . The parts a r e p o s itioned
and removed m anually .

T h e c a m s haft is s tarted by p res sing the right - hand p e dal; t h i s frees pul

l ey

(2 0 ) and brakes pulley

( 1 9 ).

The m achine i s switched off automatically after one cam shaft revolutio n .

T h e cams haft can b e rotated m anually f o r m achine adjus t m e n t .

2 2 6

Technic�l d ata,

S -50

se miautomatic milli ng m.1chinc

Max imum m i l l ing di ameter or fit?ld, mm . . . . . .

Maximum m illing depth,

111111

•

Ann ratio of l�vers (24) and (25)

•

A r m ratio of lever

(2G)

. . . . . . . . • . . . . . . . . . .

Angular rotation of cuttt.�r- spindlc

lever (25), Uegrees

Angular rotation of rabk

lever

(24),

degre<'S . . . .

Design Jiamctcr of the cams,

Illm . . . . . . . . . . .

Maximum cam diameter, mm . . . . . . . . . . . . . .

Minimum cam Jiamcter,

Jlllll

•

Height accuracy.

nuu . . . . . . . . . . . . . . . . . . .

Conrour accuracy, mm

. .

Surface-finish-quality class, GOST 2789-51

•

Production rate , operations per shifr

•

Cutter-spindle motor

Camshaft motor

•

. . .

9 0 : 27 6

1 : 4

l'rom -6.5 to +

1'1 .5

From

to +

1 4 .5

2 02

3 2 0

l :iO

0 . 01

0 . 02

4 0 0 - 2 0 0 0

0 .35 1<w ,

3 0 0 0

rpm

0 .25 1M ,

1 5 0 0

rpm

Setup Calculation for the S- 50 Semiautomatic Machine

The cams for the S - 5 0 semiautomatic machine are calculated in the

following way.

1 . The part to be machine (Figure 2 3 ) is drawn to a scale of 2 0 : 1 . The

sequence of contour - m achining operations is marked on the drawing, and

the cutter center pitch is drawn at a distance from the contour equal to half

the cutter diameter. The length of the cutter path in machining and the

length of the idle movem ents are calculated s eparately. For large idle

movem ents it is suggested to as sign 4

5 mm rise and 6

7 mm drop per

cam degree . The total cam angle required for machining and that required

for idle movements are then determined.

The length of path per degree of cam shaft rotation is then calculated for

the machining and idle portions , and secto rs corresponding to 1 camshaft

degree are marked and numbered from 0 to 3 6 0 . Sectors of the same depths

are milled consecutively and continuously.

2. A sheet of tracing paper with a degree network (Figure 24) drawn to

the s am e s cale as the part drawing (20: 1 ) is superpos ed over the part draw

ing. The network must be s o superposed that the contour to be m illed is

near the maximum radius, as this will make the cam curves less steep .

The initial pos ition of the cutter must be outs ide the zone whe re the part is

located in order to facilitate positioning and remo val, but near the firs t

plunge point and the exit point so as not to require too much rise and drop

on the cam s .

3 . After the tracing paper has been fastened on the drawing, the <:>.ngles

of rotation of both leve rs for each point on the cutte r path are visually de

termined. The values of the angles of rotation t.� and t.r (Figure 2 5 ) are

translated by m eans of a special table (A ppendix 4 ) into increments t. R

of the cam radii, which are written into the cam - figuring sheet.

The radial increm ent t.R is measured from the design diam eter, 2 02 mm,

( R

101 mm ), with positive sign when the lever is lifted, and with negative

sign when it is lowered.

227

4 .

The m a ximum m i ll i ng depth is d e t e rmined from the pa rt d ra wing. The

maximum depth co rresponds to th e m a ximum height of the cyl indrical cam

to a s c a l e of 4: 1 . The m aximum height o n t h e cam a c c o rding to the des ign
data for the machine m us t not exce.ed

1 8

m m , and therefore the m illing depth

I B

cannot exceed

4 . 5 m m . The cam an gl e of r i s e ( relative to the hori -

zontal l in e ) must not b e g r e a t e r than 5 0° , and the angl e of drop m u s t not
exceed 7 5° . The angles are m ea s u red f rom the z e ro line of th e tabl e cam .

l'lC URE 23. Curter parh f,, nracllining

rece�)es

in lilt' plate of "' Molniya

poci<�t "arches

The z e ro l ine o f cam ( 2 3 ) i s s hifted by 1 7 7" rel ative t o the z e ro line of

cam (22 ) .

Plotting the degree network.

T h e d e g r e e ne two rk s hould be d rawn a s

accurat e l y as p o s s ib l e . T h e wo r king angle of rota tion for table and cutter

l e ve rs lies within t h e l i m i ts of b e t w e e n + 1 4 ° 3 0 ' and 6 ° 3 0 ' . The o rigi n of

coo rdinates on the netwo r k c o rr e s ponds to the zero pos ition o f t h e l e vers
when the cutter c ente r coincides with the tab l e c en t e r , and the cam followe rs

l i e on the c i rc um ference of the cams a t t h e des ign diam e te r of 2 0 2 mm . The

2 2 8

Content .. 55 56 57 58 ..