Christy Poff [Internet Bonds 09] Terms of Surrender [WCP] (pdf)
H101. Herries Anne Tajemnice Opactwa Steepwood 09 Szansa dla dwojga
Fred Saberhagen Vlad Tepes 09 A Sharpness on the Neck
Klasyka literatury kobiecej 09 Czahary Rodziewiczowna Maria
Mackenzie Myrna Rodzinne sekrety 09 Zauroczenie
Miecze śÂ›wietlne
0076.Darcy Emma śÂšlub po wśÂ‚osku
Forsyth Frederick Opowiadania
D074. Riggs Paula Detmer Czlowiek honoru
Hogan, James P Voyage from Yesteryear
[ Pobierz całość w formacie PDF ]
The value for B in the loop diagram is:
" Largest outer boundary = ".0626 + ".0022 = ".0648
" Smallest inner boundary = ".0624 ".0024 = ".0600
" Nominal diameter = (".0648 + ".0600)/2 = ".0624
Equal bilateral tolerance = ".0024
As shown earlier, the easier conversion for position at MMC, is:
LMC ±(total size tolerance + tolerance in the feature control frame)
= ".0624 ±(.0002+.0022) = .0624+/-.0024
The equation for the Gap in Fig. 9-13 is: Gap = -A/2+B
where
A = .0624 ±.0024
B = .2250 ±0
Converting an Internal Feature at LMC to a Nominal Value with an Equal Bilateral
Tolerance
Fig. 9-14 shows a hole that is positioned at LMC.
The value for B in the loop diagram is:
" Largest outer boundary = ".52+".03 = ".55
" Smallest inner boundary = ".48-".07 = ".41
" Nominal diameter = (".55+".41)/2= ".48
Equal bilateral tolerance = ".07
Traditional Approaches to Analyzing Mechanical Tolerance Stacks 9-31
Figure 9-14 Position at LMC
internal feature
For position at LMC, an easier way to convert this is:
MMC ±(total size tolerance + tolerance in the feature control frame)
= ".48 ± (04+.03) = .48 ±.07
The equation for the Gap in Fig. 9-14 is: Gap = A B/2
where
A = .70 ±0
B = .48 ±.07
Converting an External Feature at LMC to a Nominal Value with an Equal Bilateral
Tolerance
Fig. 9-15 shows a boss that is positioned at LMC.
Figure 9-15 Position at LMC external
feature
The value for B in the loop diagram is:
" Largest outer boundary = "1.03 + ".10 = "1.13
" Smallest inner boundary = ".97 ".04 = ".93
" Nominal diameter = ("1.13 + ".93)/2 = "1.03
Equal bilateral tolerance = ".10
9-32 Chapter Nine
As shown earlier, the easier conversion for position at LMC is:
MMC ±(total size tolerance + tolerance in the feature control frame)
= "1.03 ±(.06+.04) = 1.03 +/-.10
The equation for the Gap in Fig. 9-15 is: Gap = A-B/2
where
A = .70 ± 0
B = 1.03 ±.10
9.3.3.5 Composite Position
Fig. 9-16 shows an example of composite positional tolerancing.
Figure 9-16 Composite position and composite profile
Composite positional tolerancing introduces a unique element to the variation analysis; an under-
standing of which tolerance to use. If a requirement only includes the pattern of features and nothing
else on the part, we use the tolerance in the lower segment of the feature control frame. Since Gap 1 in
Fig. 9-16 is controlled by two features within the pattern, we use the tolerance of ".014 to calculate the
variation for Gap 1.
Gap 2, however, includes variations of the features back to the datum reference frame. In this situa-
tion, we use the tolerance in the upper segment of the feature control frame (".050) to calculate the
variation for Gap 2.
Traditional Approaches to Analyzing Mechanical Tolerance Stacks 9-33
9.3.4 Runout
Analyzing runout controls in tolerance stacks is similar to analyzing position at RFS. Since runout is
always RFS, we can treat the size and location of the feature independently. We analyze total runout the
same as circular runout, because the worst-case boundary is the same for both controls.
Fig. 9-17 shows a hole that is positioned using runout.
Figure 9-17 Circular and total runout
We model the runout tolerance with a nominal dimension equal to zero, and an equal bilateral toler-
ance equal to half the runout tolerance.
The equation for the Gap in Fig. 9-17 is: Gap = + A/2 + B C/2
where
A = .125 ±.008
B = 0 ±.003
C = .062 ±.005
9.3.5 Concentricity/Symmetry
Analyzing concentricity and symmetry controls in tolerance stacks is similar to analyzing position at RFS
and runout.
Fig. 9-18 is similar to Fig. 9-17, except that a concentricity tolerance is used to control the ".062
feature to datum A.
Figure 9-18 Concentricity
9-34 Chapter Nine
The loop diagram for this gap is the same as for runout. The equation for the Gap in Fig. 9-18 is:
Gap = + A/2 + B C/2
where
A = .125 ±.008
B = 0 ±.003
C = .062 ±.005
Symmetry is analogous to concentricity, except that it is applied to planar features. A loop diagram for
symmetry would be similar to concentricity.
9.3.6 Profile
Profile tolerances have a basic dimension locating the true profile. The tolerance is depicted either equal
bilaterally, unilaterally, or unequal bilaterally. For equal bilateral tolerance zones, the profile component is
entered as a nominal value. The component is equal to the basic dimension, with an equal bilateral
tolerance that is half the tolerance in the feature control frame.
9.3.6.1 Profile Tolerancing with an Equal Bilateral Tolerance Zone
Fig. 9-19 shows an application of profile tolerancing with an equal bilateral tolerance zone.
Figure 9-19 Equal bilateral tolerance profile
The equation for the Gap in Fig. 9-19 is: Gap = -A+B
where
A = 1.255 ±.003
B = 1.755 ±.003
Traditional Approaches to Analyzing Mechanical Tolerance Stacks 9-35
9.3.6.2 Profile Tolerancing with a Unilateral Tolerance Zone
Fig. 9-20 shows a figure similar to Fig. 9-19 except the equal bilateral tolerance was changed to a unilateral
tolerance zone.
The equation for the Gap is the same as Fig. 9-19: Gap = A + B
Figure 9-20 Unilateral tolerance profile
In this example, however, we need to change the basic dimensions and unilateral tolerances to mean
dimensions and equal bilateral tolerances.
Therefore,
A = 1.258 ±.003
B = 1.758 ±.003
9.3.6.3 Profile Tolerancing with an Unequal Bilateral Tolerance Zone
Fig. 9-21 shows a figure similar to Fig. 9-19 except the equal bilateral tolerance was changed to an unequal
bilateral tolerance zone. [ Pobierz całość w formacie PDF ]
