Machinery's Handbook, 31st Edition
Cutter Grinding
899
Angles of Elevation for Milling Straight Teeth in 80- and 85-degree Blanks Using Single-Angle Fluting Cutters
Angle of Fluting Cutter
No.of Teeth
90 °
80 °
70 °
60 °
50 °
90 °
80 °
70 °
60 °
50 °
80 ° Blank
85 ° Blank
6 8
… … 2 ° 30 ′ 1 ° 44 ′ 0 ° 55 ′
… …
5 ° 2 ′ 3 ° 30 ′ 1 ° 52 ′ 76 551 431 3 ° 2 ′
332 255 215 1 ° 29 ′ 0 ° 34 ′
1 ° 8 ′
10 12 14 16 18 20 22 24
8 7 7 5 559 444 311 4 3 332 259 221 135 8 41 7 48 6 52 5 48 4 29 4 20 3 53 3 25 2 53 2 15 9 2 816 728 632 524 430 4 7 343 315 242 915 835 751 7 3 6 3 437 417 356 330 3 1 924 848 810 726 633 442 424 4 5 343 316 9 31 8 58 8 24 7 44 6 56 4 46 4 29 4 12 3 52 3 28 936 9 6 835 759 715 448 433 418 359 337
940 913 843 811 730 450 436 422 4 5 345 Spline-Shaft Milling Cutter.— The most efficient method of forming splines on shafts is by hobbing, but special milling cutters may also be used. Since the cutter forms the space between adjacent splines, it must be made to suit the number of splines and the root diam eter of the shaft. The cutter angle B equals 360 degrees divided by the number of splines. The following formulas are for determining the chordal width C at the root of the splines or the chordal width across the concave edge of the cutter. In these formulas, A = angle between center line of spline and a radial line passing through the intersection of the root circle and one side of the spline; W = width of spline; d = root diameter of splined shaft; C = chordal width at root circle between adjacent splines; N = number of splines.
B
C
W C = d sin ( – A ) N 180
W
sin A = d
A
d
Splines of involute form are often used in preference to the straight-sided type. Dimen sions of the American Standard involute splines and hobs are given in the section on splines. Cutter Grinding Wheels for Sharpening Milling Cutters.— Milling cutters may be sharpened by using either the periphery of a disk wheel or the face of a cup wheel. The latter grinds the lands of the teeth flat, whereas the periphery of a disk wheel leaves the teeth slightly concave back of the cutting edges. The concavity produced by disk wheels reduces the effective clear ance angle on the teeth, the effect being more pronounced for wheels of small diameter than for wheels of large diameter. For this reason, large diameter wheels are preferred when sharpening milling cutters with disk type wheels. Irrespective of what type of wheel is used to sharpen a milling cutter, any burrs resulting from grinding should be care- fully removed by a hand stoning operation. Stoning also helps to reduce the roughness
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