Shared Flashcard Set

Details

Prepared for Shan 1.2
mh-Worm, spur, helical, bevel gears, graduation, index
45
Other
Not Applicable
02/22/2015

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Cards

Term
01. When direct indexing:
Definition
the index crank is not used
Term
02. The formula for direct indexing eight holes in the circumference of a piece of barstock is:
Definition
24/N
Term
03. When milling a square and using the 36 hole plate circle on the direct indexing plate, how many holes are required for the milling of each side?
Definition
H/N=36/4=9
Term
04. In order to revolve the spindle one complete revolution on most dividing or indexing heads, the indexing crank must be revolved:
Definition
40 turns
Term
05. The calculated indexing for cutting 156 teeth on a gear blank is:
Definition
index=40/N=40/156=10/39=sp/hp
Term
06. The calculated simple indexing for cutting 25 teeth on a gear blank is:
Definition
index=40/N=40/25=1 3/5=1 45/75
Term
07. To drill 2 holes 105 degrees apart using direct indexing and the 24 hole plate circle, the number of spaces to move is:
Definition
360/24=15 degrees
105/15=7 spaces
Term
08. When angular indexing, 3 1/2 turns of the index crank will index the work through an angle of:
Definition
index=D/9
D=index*9=3.5*9=31.5 degrees
Term
09. When differential indexing, for negative rotation using compound gearing you should use one idler (T/F)
Definition
simple differential:
+ --> 1 idler
- --> 2 idlers
Compound differential
+ --> 2 idlers
- --> 1 idler
Term
10. Using differential indexing, which gear train would be used to index for 175 divisions? Approximate = 160
Definition
Indexing=40/A
Gearing=(A-N)40/A=(160-175)40/160=-3.75
=72*40/(32*24), 1 idler
Term
11. Before differential indexing can be accomplished:
Definition
disengage the lock or stop pin
Term
12. The milling machine is set to cut a right hand helix, to cut a left hand helix:
Definition
swivel the table clockwise and add an idler
Term
13. Using a milling machine with a standard pitch leadscrew, (4tpi) which of the following gear trains would be used to cut a 28-inch lead? (Gears available 24, 28, 32, 40, 44, 48, 64, 72, 86, 100)
Definition
Gearing=Lmc/Lsc=(1/4*40)/28=.357=DR/dn
=24*40/(48*56)=LS/SP
Term
14. During the linear graduating process, the table and the index head are connected with gears, two turns of the index crank will move the table:
Definition
40turns --> 1rev --> 1/4=.25
2 turns --> 2/40=.05 rev --> .25*.05=.0125"
Term
15. The calculated indexing required for a linear graduation of .03125 inch is:
Definition
40 --> 1 --> .25
5 <--- .125 <--- .03125
Term
16. When linear graduating the table is moved by:
Definition
hand
Term
17. The circular/ radial graduating method would produce ...
Definition
Vernier protractor scales or radial lines about a circle
Term
22. If driving gear has 40 teeth and revolves at 300 rpm, and is in mesh with a driven gear having 15 teeth, the rpm of the driven gear would be:
Definition
Ng*RPMg=Np*RPMp
RPMg=800
Term
23. What is the pitch diameter of each gear whose ratio is 2.5:1 and their center distance is 7 inch?
Definition
PDg=Ng/(Ng+Np)*2*CD

4 inch and 10 inch
Term
24. Three calculations required to mill a helical gear that are not required to produce a spur gears are:
Definition
helix angle, change gears, lead of helix
Term
25. To ensure that a helical groove or spline has the same contour as the form cutter:
Definition
swing the table to the helix angle
Term
26. Helical gears that connect parallel shafts must have ... hands of helix
Definition
opposite
Term
27. Involute milling cutters for cutting helical gears on a milling machine are selected according to Normal Diametral Pitch (T/F)
Definition
T
Term
28. Helical gears cannot connect:
Definition
intersecting shafts
Term
29. Helical gears require more horse power to turn than a similar spur gear (T/F)
Definition
T
Term
30. If the circular pitch of a helical gear with a 25 degrees helix angle is .221" the normal circular pitch will be:
Definition
Cos(helix angle) = DP/NDP=NCP/CP,
NCP=.2
Term
31. Which of the following ratios is an example of hunting tooth ratio:
Definition
145/48 (skip tooth)
Term
32. To cut helical gears with crossing shafts on a horizontal milling machine, swing:
Definition
table clockwise for both gears
Term
33. When cutting a helical gear:
Definition
disengage the index plate locking device
Term
34. To ensure that a worm and worm gear run correctly, the:
Definition
circular pitch must equal the linear pitch
Term
35. To find the centre distance of a worm and worm gear:
Definition
add pitch diameters and divide by two
Term
36. A worm gear has 50 teeth and a pitch diameter of 3. inch. The linear pitch of the worm:
Definition
Cir = pi*PD = CP*N
LP=CP=pi*PD/N = 3.14*3/50 = .188"
Term
37. A 4 start worm with a linear pitch of .25" drives a 40 tooth worm gear. If center distance is 2.2". What is lead angle of the worm?
Definition
Tan (lead angle) = Lw/Cir
Cir = pi*PDw = CP*Np
CD=1/2*(PDw+PDg)

PDg=Cir/pi=CP*Ng/pi=3.183
PDw=2CD-PDg=1.217
lead angle = actan(Lw/(pi*PDw)=14.66 degrees
Term
38. One manufacturing method used to produce worm gears is:
Definition
hobbing
Term
39. The pressure angle of a 29 degrees worm is
Definition
14.5 degrees
Term
40. One application for a coarse pitch worm and worm gear is a:
Definition
hoist or winch
Term
41. A worm gear has 75 teeth and is driven by a 5 start worm. If the center distance is 4. What is the pitch diameter of the worm?
Definition
See the formular specify by saying
Term
42. One application for a fine pitch worm and worm gear is:
Definition
a gauge or meter
Term
43. If a spur and worm gear have the same DP and number of teeth:
Definition
their pitch diameters will be equal
(PD=N/DP)
Term
44. When cutting bevel gear teeth, the index head is swung to the:
Definition
root angle
Term
45. When blanking out a bevel gear, the most important angle to consider would be:
Definition
face angle
Term
46. The chordal thickness of a bevel gear would be measured at the:
Definition
large end of the tooth
Term
47. Which tooth form is not found on a bevel gear?
Definition
slanted
Term
48. Bevel gears with curved teeth can be produced in a:
Definition
bevel gear generator
Term
49. Bevel gear cutters are:
Definition
thinner than spur gear cutters
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