GB/T 15054.4-1994 Small thread tolerances

GB/T 15054.4-1994 Small thread tolerance GB/T15054.4-1994 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Miniature screw threads
Tolerances
This standard refers to the international standard ISO/R1501--70 "ISO small screw threads". 1 Subject content and scope of application
GB/T15054.4--94
Replaces GB19563
This standard specifies the tolerances of small screw threads whose tooth profile conforms to GB/T15054.1 and whose diameter and pitch conform to GB/T15054.2. This standard applies to small screw threads for general purposes with a nominal diameter range of 0.3~1.4mm. 2 Reference standards
GB/T15054.1 Small thread tooth profile
GB/T15054.2 Small thread diameter and pitch series 3 Tolerance zones
The tolerance zones of internal and external threads are shown in Figures 1 and 2 respectively. Design tooth type
Tolerance zone is 4H5 or 4H6
Figure 1 Internal thread tolerance zone
Approved by the State Bureau of Technical Supervision on May 3, 1994t
Implemented on March 1, 1995
In the figure: D-—
Major diameter of internal thread;
D2—Medium diameter of internal thread;
Minor diameter of internal thread;
Medium diameter tolerance of internal thread;
Minor diameter tolerance of internal thread;
Basic deviation of major diameter and medium diameter.
In the figure: d----Major diameter of external thread;
Medium diameter of external thread;
Minor diameter of external thread;
-Major diameter tolerance of external thread;
Medium diameter tolerance of external thread;
Minor diameter tolerance of external thread.
3.1 Tolerance zone position
GB/T15054.4-94
(b) Tolerance zone is 3G5 or 3G6
Continued Figure 1
Figure 2 External thread tolerance zone is 5h3 ​​or 5h5
Design tooth type
3.1.1 The position of the tolerance zone is determined by the basic deviation. The basic deviation of the external thread is the upper deviation es, and the basic deviation of the internal thread is the lower deviation 21
GB/T15054.4—94
2 The tolerance zone position of the external thread major diameter d, middle diameter d and minor diameter d: is h (see Figure 2), and its basic deviation is zero. 3.1.2
3.1.3 The tolerance zone position of the internal thread minor diameter D is H; there are two tolerance zone positions for the internal thread pitch diameter D, HC see Figure 1a)) and GC see Figure 1(b)). The basic deviation of H is zero, and the basic deviation of G is a positive value. The tolerance zone position of the internal thread major diameter D is the same as the tolerance zone position of its corresponding pitch diameter. The basic deviation values ​​of the internal thread major diameter and pitch diameter are listed in Table 1. Table 1 Basic deviations of major and middle diameters of internal threads
3.2 Tolerance grades
Major diameter D and middle diameter D2
3.2.1 This standard specifies the following tolerance grades for internal and external thread diameters:
Internal thread middle diameter D2
Internal thread minor diameter D
External thread major diameter d
External thread middle diameter da
External thread minor diameter d
3.2.2 The top diameter tolerance values ​​of internal and external threads are listed in Table 2. Table 2 Tolerance of top diameter of internal and external threads
Internal thread minor diameter D1
Tolerance grade
Tolerance grade
External thread major diameter d
Tolerance grade
GB/T15054.4-94
Continued Table 2
Internal thread minor diameter D,
Tolerance grade
3.2.3 The tolerance values ​​of the middle diameter of internal and external threads are listed in Table 3. 3.2.4||tt ||The tolerance values ​​of the minor diameter of external threads are listed in Table 4.
Table 3 Tolerances of the pitch diameter of internal and external threads
Pitch diameter D of internal threads
Tolerance grade
Tolerance of minor diameter (d:) of external threads
Major diameter d of external threads
Tolerance grade
Pitch diameter d2 of external threadsbZxz.net
Tolerance grade
Tolerance grade
3.3 Tolerance zone of pitch diameter of internal threads
GB/T 15054.4—94
There are only two types of tolerance zones for pitch diameter of internal threads, 4H and 3G. 3.4 Tolerance zone of coated threads
For threads that need to be coated with a protective layer, if there are no special provisions, any point of the actual profile of the coated thread should not exceed the maximum solid tooth profile determined by H and h.
3.5 Preferred tolerance zone
Under normal circumstances, the preferred tolerance zone of threads specified in Table 5 should be used. Table 5 Preferred tolerance zone of internal and external threads
4 Thread marking
The marking of small threads consists of the code of small threads and the code of tolerance zone. 4.1 See GB/T15054.2 for the code of small threads.
4.2 The code of tolerance zone of small threads includes the code of tolerance zone of middle diameter and the code of tolerance grade of top diameter. The code of tolerance zone consists of the tolerance grade indicating its size and the letter indicating its position. 4.3 The tolerance zone of thread pair shall indicate the tolerance zone code of internal and external threads respectively. The former is the tolerance zone code of internal thread and the latter is the tolerance zone code of external thread, separated by a slash in the middle.
4.4 Marking example
Internal thread: S0.9-4H5
Top diameter tolerance grade code
External thread: So.9LH-5h3
Thread pair: S0.9-4H5/5h3
Additional instructions:
Mid-diameter tolerance zone code
-Top diameter tolerance grade code
Mid-diameter tolerance zone code
This standard is proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard is drafted and managed by the Standardization Research Institute of the Ministry of Machinery Industry. The main drafters of this standard are Li Xiaobin, Yu Yuan and Yu Minhui. 25-1
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