This standard specifies the standard tolerance values ​​for the intermediate tolerance grades IT5 to IT10. This standard applies to the dimensional tolerances of cylindrical surfaces and other surfaces or structures with basic dimensions up to 18 mm in timing instruments. QB/T 2267-1996 Tolerances and fit dimensions for timing instruments with standard tolerance values ​​for the intermediate tolerance grades up to 18 mm QB/T2267-1996 Standard download decompression password: www.bzxz.net

QB/T2267-1996
This standard is not equivalent to the Swiss watch industry standard NIHS04-01 basic tolerance (1961 edition). The differences between this standard and NIHS 04-01 are as follows: the basic size of this standard is up to 18mm; the basic size of NIHS04-01 is up to 50mm; this standard inserts IT5.5, IT6.5, IT7.5, IT8.5.IT9.5 intermediate tolerance grades; NIHS04-01 inserts IT6.5IT8.5.IT9.5 intermediate tolerance grades;
The rounding of the mantissa of the tolerance value of this standard shall be carried out according to the rounding rules in GB/T8170-1987 "Rules for Rounding off Numerical Values": the rounding of the tolerance value of NIHS04-01 shall be carried out according to the even number system. This standard is revised from the original professional standard ZBY11025-1989 "Tolerances and fit dimensions for timing instruments to 18mm insertion intermediate tolerance grades". The technical content of this standard is consistent with the original professional standard: the writing format and expression method are implemented in accordance with GB/T1.1-1993 Standardization Work Guide Unit 1: Drafting and Expression Rules of Standards Part 1: Basic Provisions for Standard Writing". Appendix A of this standard is a prompt appendix.
This standard is proposed by the Quality Standards Department of China Light Industry General Association. This standard is under the jurisdiction of the National Clock and Watch Standardization Center. The drafting unit of this standard: Clock and Watch Research Institute of China Light Industry General Association. The main drafter of this standard: Xiao Zhaoquan.
From the date of implementation of this standard, the professional standard ZBY11025-1989 issued by the former Ministry of Light Industry. "Tolerances and fit dimensions for timing instruments to 18mm insertion intermediate tolerance grades" will be invalid. 96
Light Industry Standard of the People's Republic of China
Tolerances and fits for timing instruments
Dimensions up to 18mm for insertion of intermediate tolerances
Standard tolerance values ​​for grades
This standard specifies the standard tolerance values ​​for insertion of intermediate tolerances in tolerance grades IT5 to IT10. QB/T 2267—1996
This standard applies to the dimensional tolerances of cylindrical surfaces and other surfaces or structures with basic dimensions up to 18mm in timing instruments. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T1800—1979 General theory of tolerances and fits Standard tolerances and basic deviations GB/T1803--1979 Tolerances and fits Dimensions up to 18mm hole and shaft tolerance zones 3 Insert standard tolerance values ​​of intermediate tolerance grades In the GB/T1800 standard tolerance value dimensions up to 18mm, insert the intermediate tolerance grades of IT5.5, IT6.5.IT7.5.IT8.5 and IT9.5 respectively. The standard tolerance values ​​of the intermediate tolerance grades are shown in Table 1. 4 Insert limit deviation values ​​of intermediate grades wwW.bzxz.Net
When the limit deviation using the standard values ​​in GB/T1803 cannot meet the use requirements, insert the standard tolerance values ​​of the intermediate tolerance grades according to Table 1 or insert the intermediate limit deviation values ​​according to the calculation method in Appendix A (suggestive appendix). Table 1
Basic dimensions
Basic dimensions
IT01IT0ITIT2IT3IT4IT5T5.5IT6T6.5ITT7.5IT8T8.5μm
Approved by China Light Industry General Association on January 27, 1997
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IT15IT16IT17
Implemented on September 1, 1997
Basic dimensions
QB/T2267—1996
Table 1 (Complete)
Note: When the basic dimensions are less than 1mm, there is no IT to IT18.98
A1 Calculation method
QB/T 2267—1996
Appendix A
(Suggested Appendix)
Calculation method of standard plastic value for inserting intermediate tolerance grade The calculation method of standard plastic value for inserting intermediate tolerance grade is to use the geometric mean of the first and last tolerance grades to be inserted, that is, to multiply the first and last two numbers and then take the square root. The rounding of the mantissa value of the calculation result shall be carried forward according to the rounding rule in GB/T8170. A2 Example
In the dimension to 3mm dimension segment, an intermediate tolerance grade IT8.5 is inserted between tolerance grades IT8 and IT9, and the tolerance value is: IT8.5=IT8×IT9=/14×25~19μm. 99
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