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ta3lime
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indexing
04-28-2010

Indexing on milling machines





· Dividing head: is used to divide work piece circumference to equal divisions
· It is one of the more important of milling machine attachments.
· It has a reeducation of ( 40 : 1 ).
· It has a direct indexing plate fixed on spindle.
· Also has indexing plates for ( simple , angular , differential ) indexing.
Plate 1- ( 15 , 16 , 17 , 18 , 19 , 20 holes )
Plate 2- ( 21 , 23, 27 , 29 , 31 , and 33 )
Plate 3- ( 37 , 39, 41 , 43 , 47 , and 49 )
· It has a single start worm meshed worm wheel 40 teeth.
· It has 2 sector arms to be set for indexed holes.
· It has a set of gears have the following teeth : 9 24 , 28 , 32 , 36 , 40 , 44 , 48 , 56 , 64 , 72 , 86 & 100 )


Indexing methods :

1- direct indexing
2- indirect indexing
3- angular indexing
4- differential indexing

No
Method
Formula
1
Direct indexing
Index = no of plate holes / n req. div.
2
Indirect indexing
C.T. = 40 / N TURNS
3
Angular indexing
C.T. = angle req. /9 TURNS
4
Differential indexing
C.T. = 40 ( N1 – N2 ) / N2 TURNS




INDIRECT INDEXING






40 complete turns of crank = one turn of work piece

means : one turn of crank = 1 /40 turn of work piece




no of crank turns = 40 / no of division required

C.T. = 40 / N turns





Example :

1- calculate the no of crank turns to mil a hexagon nut:

C.T. = 40 /N turns

C.T. = 40 / 6 = 6 4/6

= 6 (4X3) / (6 X 3 )
= 6 12/18


6 full turns + 12 holes from 18 holes circle



Angular indexing






One turn of crank rotate the spindle 1 / 40 of 360 degree

One crank turn = 360 /40 = 9 degrees

Example :

By using 40 : 1 dividing head , calculate the indexing required to

obtain the following angles :

a- 72 degrees

b- 60 degrees

c- 182 degrees



Differential indexing






· n1 means required ****** .
· n2 means chosen ****** .
· if the sign is (+ ) the index plate should rotate opposite direction
· if the sign is rotate ( - ) the index plate should rotate in the same direction .

Example :

To cut spur gear have 71 teeth by using a 40 : 1 dividing head calculate the following :

a- no of crank turns required.


Questions bank :

Answer the following questions :

1- fig ( 1 ) shows a dividing head , name the labeled parts:



2- a- name the two indexing methods shown in fig ( 2 )



b- state the function of the labeled gears in fig ( 2-a )










3- by using the index plate shown in fig 3 index for :

a- milling a serrated shaft 34 divisions.



b- Milling two flats apart 18′ 30″


4- using a dividing head having index plate : 15 , 17 , 19 , 25 , 29 , 33 , 39 , 43 & 49 hole circles :

a- index for cutting spur gear 51 teeth .






b- calculate the change gears if the dividing head has spur gear set

of 24 , 28 , 32 , 36 , 40 , 44 , 48 , 56 , 64 , 72 , 86 & 100 teeth









5- name 3 main parts of universal dividing head &state use of each.

1- ……………………….

2- ……………………….

3- ……………………….

6- state 3 advantages of universal dividing head

1- ……………………………………………….

2- ………………………………………………..

3- …………………………………………………


7- compare between plain dividing head & universal dividing head in the method of indexing ;










8- in dividing head , state the use of the following :

a- sectors arms:




b- eccentric handle :





c- worm & worm wheel gear train :





d- index crank :





e- swivel block :






9- write 4 indexing methods & compare :

No
Method
Formula
1



2



3



4




10 – state the use of rotary table :



11- name 3 types of rotary tables :

1- …………………………………

2- ………………………………….

3- ………………………………….

12- name 4 main parts of rotary tables & state use of each one:
name use

1- ………………………… ………………………….

2- …………………………. ………………………….

3- …………………………. …………………………..

13- write 5 safety precautions while working on milling m/c using
dividing head:
1- ………………………………………………………….
2- ………………………………………………………….
3- ………………………………………………………….
4- …………………………………………………………...
5- …………………………………………………………..


14- state the sue of dividing chuck:




15- compare between the plain rotary table 7 dividing chuck:




16- using a 40 : 1 universal head having the following :

a- index plate face 1 ( 15 ,17 , 19 , 25 , 29 , 33 , 39 , 43 , 49 )
face 2 ( 13 , 16 , 18 , 20 , 23 , 27 , 31 , 37 , 41 , 47 )

b- change gears set L24 , 28 ,32 ,36 , 40, 44 ,48, 56,64 ,72 ,86 & 100 )

index for :

1- cutting a spur gear having 74 teeth

2- milling 2 slots on a disc apart 38′ 30″

17- using data in the above question index for:

a- 112 divisions

b- 24′ 20″

18 – using data on question 16 index for:

a- indexing for milling a ratchet having 121 teeth
b- calculate the change gear required

19- using data on question 16 index for the following angles

136′ , 291′ , 12′ 30″ , 42′ 20″

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