GB/T 38575-2021Spectacle frames - Screw threads (English PDF)

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 M1.0x0.25, M1.2x0.25 and M1.4x0.3

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

M1.2x0.25 and M1.6x0.35 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 S0.8x0.2; its tolerance shall meet the

requirements of GB/T 15054.2.

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