ISO公制梯形螺纹 外螺纹和内螺纹的检验 量规尺寸和设计特征

ISO metric trapezoidal screw threads

Gauging of external and internal threads

Gauge dimensions and design features

Metrisches ISO-Trapezgewinde; Lehren für Bolzen- und Muttergewinde, Lehrenmaße und Baumerkmale

Supersedes August 1973 edition.

In keeping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal marker.

This standard gives specifications necessary for manufacturing gauges for ISO metric trapezoidal screw threads.

General specifications relating to the gauging system, nomenclature, gauging of workpieces and handling of gauges have not been separately standardized for gauges for trapezoidal screw threads; for these, DIN 13 Part 16 and Part 18 shall be applied as appropriate.

This standard specifies only the required gauge dimensions and design features. The manufacturing tolerances have been increased in comparison with those specified in DIN 13 Part 17 by about 45 % in order to compensate for the effect of the steeper flanks of the ISO metric trapezoidal thread.

Contents

Continued on pages 2 to 12

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1 Thread profiles

1.1 Profiles with complete flanks

The following gauges shall have a profile as shown in figure 1:

• Go check plug for new solid Go screw ring gauge;
• Go check plug for new solid Not Go screw ring gauge;
• Go screw plug gauge;
• setting plug for Go screw calliper gauge;
• Not Go check plug for new solid Not Go screw ring gauge;
• setting plug for Not Go screw calliper gauge;
• wear check plug for solid or adjustable Not Go screw ring gauge.

Figure 1. Profile with complete flanks

The following gauges shall have a profile as shown in figure 2:

• solid Go screw ring gauge;
• anvils of Go screw calliper gauge.

Figure 2. Profile with complete flanks

These diameters do not exist on anvils of Go screw calliper gauges.

1) P = pitch of single start trapezoidal thread.

The form of the root is at the manufacturer's discretion. The maximum size of the minor diameter and R₂ max shall not be exceeded.

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1.2 Profiles with truncated flanks

The following gauges shall have a profile as shown in figure 3:

Not Go check plug for new solid Go screw ring gauge; wear check plug for solid Go screw ring gauge; Not Go screw plug gauge.

Figure 3. Profile with truncated flanks

The following gauges shall have a profile as shown in figure 4:

solid Not Go screw ring gauge; anvils of Not Go screw calliper gauge.

Figure 4. Profile with truncated flanks

Gauges with truncated flanks have a clearance groove b, the form of which is left to the discretion of the manufacturer. For the symmetry tolerance s of the clearance groove, see table 2.

Figure 5. Symmetry tolerance s of the clearance groove b

The limit deviations for b may be exceeded if the real displacement is less than the symmetry tolerance s, by twice the amount of the difference between the symmetry tolerance s and the real displacement.

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2 Tolerance zones

2.1 Tolerance zones for pitch diameter (see figures 6 and 7)

Figure 6. Tolerance zones for the pitch diameter of gauges for checking external threads

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The pitch diameter of screw ring gauges can be measured directly where it cannot be better checked with check plugs. In order to ensure that a screw ring gauge that has been found to be correct by direct measurement will also be found correct when checked with a Go check plug, it is necessary to shift the pitch diameter tolerance zone of the Go check plug downwards by an amount m, in relation to the pitch diameter tolerance zone of the screw ring gauge (see figure 6). The values specified in table 7 for m represent the sum of the diametral equivalents of the average errors that are likely to occur in the pitch and the flank angles of the check plug and of the screw ring gauge, in relation to the specified tolerances on these thread parameters.

Figure 7. Tolerance zones for the pitch diameter of gauges for checking internal threads

2.2 Tolerance zones for plain gauges (see figures 8 and 9)

Tolerance zones for check gauges for calliper gauges shall be selected in accordance with DIN 7162.

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3 Calculation of gauge dimensions

Figure 8. Tolerance zones for gauges for checking the major diameter of external threads

Figure 9. Tolerance zones for gauges for checking the minor diameter of internal threads

3.1 Gauges for workpiece external threads

In table 3 on pages 7 and 8

d₃, D₄, d, d₂ and D₁ are nominal thread diameters;

T_d2 is the tolerance on the pitch diameter as specified in DIN 103 Part 3;

A₀ is the fundamental deviation for the pitch diameter for the appropriate tolerance position as specified in DIN 103 Part 3.

(A₀ shall be inserted in the table 3 equations omitting the sign specified for the fundamental deviations. For tolerance position h, A₀ = 0)

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