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GB/T 38575-2021 English PDF (GBT38575-2021)

GB/T 38575-2021 English PDF (GBT38575-2021)

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GB/T 38575-2021: Spectacle frames -- Screw threads
This document specifies the classification and requirements of screw threads used for spectacle frames, the length and tolerances of screws, the thread taps and measuring instruments. This document applies to small threads, ordinary threads and thread taps. This document does not apply to self-tapping screws.
GB/T 38575-2021
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 11.040.70
CCS Y 89
Spectacle frames - Screw threads
眼镜架 螺纹
(ISO 11381:2016, Ophthalmic optics - Spectacle frames - Screw threads,
MOD)
ISSUED ON: APRIL 30, 2021
IMPLEMENTED ON: NOVEMBER 01, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 5
4 Classification and requirements of screw threads ... 5
5 Screw length and tolerance ... 6
6 Thread tap ... 8
7 Measuring instrument ... 8
Appendix A (Informative) Screw thread application ... 9
Foreword
This document was drafted in accordance with the rules given in GB/T 1.1-2020, Directives for standardization - Part 1: Rules for the structure and drafting of standardizing documents.
This document uses the redrafting method to modify and adopt ISO 11381:2016 "Ophthalmic optics - Spectacle frames - Screw threads".
There are structural differences between this document and ISO 11381:2016: Chapter 3 Terms and definitions is added in this document, which makes
subsequent serial numbers postponed.
The technical differences between this document and ISO 11381:2016 and the reasons are as follows:
-- With regard to the normative references, this document makes technical adjustments to adapt to the technical conditions of China. The
adjustments are concentrated in Chapter 2 “Normative references”. The
specific adjustments are as follows:
● Use GB/T 2516 which modifies and adopts international standards to
replace ISO 965-3;
● Use GB/T 3464.1 which modifies and adopts international standards
to replace ISO 529.
● Use GB/T 3934 which modifies and adopts international standards to
replace ISO 1502.
● Use GB/T 15054.2 to replace ISO 1501;
-- Add the scope of the Standard, "This document does not apply to self- tapping screws", because self-tapping screws are used in the production process of domestic spectacle frames, and restrictions need to be made; -- Modify the internal thread grades of M1.0×0.25, M1.2×0.25 and M1.4×0.3 in Table 1; adjust from 5H to 6H. Adjust the enlargement tolerance grade from 5H to 6H to match the domestic production level.
This document makes the following editorial changes:
-- Change the standard name to “Spectacle frames - Screw threads”, to be consistent with our country's existing standard series;
-- Modify the informative appendix; add the application instructions for M1.2×0.25 and M1.6×0.35 specifications in appendix A.
Spectacle frames - Screw threads
1 Scope
This document specifies the classification and requirements of screw threads used for spectacle frames, the length and tolerances of screws, the thread taps and measuring instruments.
This document applies to small threads, ordinary threads and thread taps. This document does not apply to self-tapping screws.
2 Normative references
The contents of the following documents constitute the indispensable clauses of this document through normative references in the text. For dated references, only the version corresponding to that date is applicable to this document; for undated references, the latest version (including all amendments) is applicable to this document.
GB/T 2516, General purpose metric screw threads - Limit deviations (GB/T 2516-2003, ISO 965-3:1998, MOD)
GB/T 3464.1, Machine and hand taps - Part 1: Plain parallel shank machine and hand taps (GB/T 3464.1-2007, ISO 529:1993, MOD)
GB/T 3934, Specification of gauges for general purpose screw threads (GB/T 3934-2003, ISO 1502:1996, MOD)
GB/T 15054.2, Miniature screw threads - Part 2: Tolerances and limits of size 3 Terms and definitions
No terms and definitions need to be defined in this document.
4 Classification and requirements of screw threads
Screw threads are divided into small threads and ordinary threads according to their diameter and pitch.
The size of the small thread is S0.8×0.2; its tolerance shall meet the
requirements of GB/T 15054.2.
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