Machinery's Handbook, 31st Edition
Spur Gearing
2239
6) Maximum permissible hob tip radius, r c (max). The dedendum factor is 1.25. (12) 7) If the hob tip radius r c is 0.30, determine if the pinion involute is undercut. (13) 8) Therefore there is no involute undercut. 9) Pinion HPSTC, d H (14) ( ) . . . . . . max r 1 034202 0 785398 0 93969 1 25 0 34202 04719inch c # # = − − = . . . . . . . . 034202 125 030 030 05 23 034202 3 0776 3 9332 # # 1 # − + . . tan d d 013713 23 628318 041031 . 22 1832 ° ′ ′′ = = + =
. . 10 092515 23 093969 2 3362 inches . # #
=
d
H
(15)
=
10) Gear HPSTC, D H
. . D 020267 31 628318 040535 . + =
tan D
= =
(16)
22 355 ° ′ ′′
. . 10 092676 31 093969 3 1433 inches . # #
=
D
(17)
H
=
11) Pinion TIF diameter, d TIF
. 036397 23 4 −
. 064279 125 030 . .
. 2 093969 030 .
− +
tan e
a
k
=
4 3136 #
(18)
. 007917
e
=
° ′ ′′
=
. . 10 099688 23 093969 2 1681 inches . # #
=
d
TIF
(19)
=
12) Gear TIF diameter, D TIF
. 036397 31 4 −
. 064279 125 030 . .
. 2 093969 030 .
− +
tan E
a
k
=
8 4050 #
(20)
. 015267
E
=
° ′ ′′
=
. . 10 098855 31 0 93969 2 9468 inches . # # =
=
D
(21) Gear Blanks for Fine-Pitch Gears.— The accuracy to which gears can be produced is con- siderably affected by the design of the gear blank and the accuracy to which the various surfaces of the blank are machined. The following recommendations should not be re- garded as inflexible rules, but rather as minimum average requirements for gear-blank quality compatible with the expected quality class of the finished gear. TIF
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